"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV

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"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
Issue 68                      FEV CUSTOMER MAGAZINE

                       "DEVELOPMENT SOLUTIONS
                       FOR A SUSTAINABLE MOBILITY"
     Zero-Impact
Combustion Engine

 Fuel Cell Systems
   for Heavy Duty
Applications: From
Concept to System
         Validation

 The 3.0L Duramax
 Diesel Engine Sets
    New Standards

Urban Air Mobility –
  A New Market for
Automotive Players
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
TABLE OF CONTENTS

    Dear Readers,
                                                                              PAGE 04                                    PAGE 24                            PAGE 32
    Sustainable drive systems are becoming increasingly important
    with the tightening of emission standards. The decision as to which
    sustainable drive system is best suited for the respective application
    depends on various factors. These include costs, efficiency and
    legal requirements.

    On this basis, FEV develops solutions for tomorrow's mobility for
    its customers. In this issue of SPECTRUM, we would like to present
    the latest results of our work, including under which conditions a
    climate-neutral combustion engine is possible.

    A current further development in the field of diesel engines is the
    3.0L Duramax for pickup trucks, which sets new standards with its
    low fuel consumption and impressive performance. In addition,
    we will use a concept vehicle to show how further potentials can
    be tapped for hybrid drives with predictive and automated driving        Predictive Functions in the              Fuel Cell Systems for Heavy         Urban Air Mobility – A New Market
    functions with regard to their energy requirements.                      HYBex3 Concept Vehicle                   Duty Applications: From Concept     for Automotive Players
                                                                                                                      to System Validation
    For heavy-duty applications, we examine the development and
    validation of fuel cell systems from the point of view of total oper-
    ating costs.

    How will future mobility develop into space? In the field of urban       01 SUSTAINABLE DRIVE SOLUTIONS                            02 RESEARCH AND DEVELOPMENT
    airspace transport, we show access potentials for companies in the
    automotive industry. Exciting (3D) lighting concepts and efficient
    data management round off the variety of topics covered in this          04         Zero-Impact
                                                                                        Combustion Engine                              36         Exhaust Gas Condensate for Self-
                                                                                                                                                  Contained Water Injection System

                                                                             12                                                        40
    SPECTRUM.
                                                                                        Mild-Hybrid-Diesel-Powertrain                             Carbon-Neutral Transport –
    We hope you enjoy reading this issue. Further information and news                  with a Pre-Turbine                                        with Synthetic Fuels
                                                                                        Exhaust Aftertreatment
    about FEV can be found at www.fev.com.

                                                                             18                                                        46
                                                                                                                                                  Stepcom®-2 Step Variable
                                                                                        Predictive Functions in the                               Compression Ratio System Integration
                                                                                        HYBex3 Concept Vehicle                                    and Industrialization

                                                                             24         Fuel Cell Systems for Heavy
                                                                                        Duty Applications: From Concept
                                                                                        to System Validation
                                                                                                                                       52         SCR on Filter Technology
                                                                                                                                                  for Off-Highway Applications

    Professor Stefan Pischinger                                              30         The 3.0L Duramax Diesel
                                                                                        Engine Sets New Standards                      56         Urban Air Mobility – A New Market
                                                                                                                                                  for Automotive Players

                                                                                                                                       60
    President and CEO of the FEV Group
                                                                                                                                                  Workflow-Based Information Management
                                                                                                                                                  for Powertrain Testing Facilities

                                                                             03 NEWS
                                                                                                                                       66         NVH-Requirements of Electric
                                                                                                                                                  Drive Units in the Vehicle Interior

                                                                             70         Efficient Data Management:
                                                                                        Cooperation Between
                                                                                        FEV and Microsoft

                                                                             74         Light in Sight: FEV Subsidiary
                                                                                        Develops Micro-Lens Array
                                                                                        for Automotive Applications

2                                                                                                                                                                                              3
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                               Emission reduction

    EMISSION REDUCTION

                                     A
                                                                                                                       Development methodologies
    ZERO-IMPACT                                  further tightening of emission legislation with Euro7
                                                 is expected. FEV’s hypothesis for the key challenges                  FEV has developed extensive patented and patent-pending

    COMBUSTION ENGINE                            of the next European emission legislation consist of
                                                 the following major topics:
                                                                                                                       development methods in the field of simulation, as well as
                                                                                                                       testing and aging of emission-relevant components, which
                                     „„   A general reduction of the gaseous emission limits                           make it possible to demonstrate high robustness and forecast
                                          CO: 500 mg/km . HC: 50 mg/km . NOX: 35 mg/km                                 accuracy at an early stage of development.
                                     „„   Non-allowance of auxiliary emission strategies that can
                                          lead to high emissions
                                     „„   Particle number emissions measured down to 10 nm                             RDE emission simulation and
                                          instead of 23 nm                                                                 identification of worst case cycles
                                     „„   Incorporation of further emission                                                         Emission simulation at FEV is an essential pillar in
                                          components limits for the lab tests                                                             the frontloading of development. Presented
                                     „„   Extension of the RDE legislation                                                                    for the first time in 2016 at the Vienna
                                          framework to incorporate                                                                               Engine Symposium, and further refined
                                          further emission                                                                                         since then, this modular FEV simula-
                                          components and short                                                                                       tion toolchain based on the GT-Suite
                                          driving trips                                                                                               software environment is now an
                                                                                                                                                       essential part of FEV development
                                     FEV has investigated how ul-                                                                                       activities. Engine raw emissions are
                                     timately even a zero-impact                                                                                        modeled based on stationary and
                                     combustion engine could be                                                                                        transient measurement data from
                                     achieved, causing less emissions                                                                                 engine and roller test benches. The
                                     than those contained in the am-                                                                                simulation models of the exhaust
                                     bient air. In particular the following                                                                       aftertreatment follow a map-based
                                     targets have been set:                                                                                    approach. Still, discretization of the cat-
                                     „„ Emissions in WLTC                                                                                   alyst monoliths allows a good description
                                         NOX: 40 µg/m³ (corresponds to                                                                 of the warm-up behavior to take into account
                                         approx. 0.03 mg/km)                                                                     individual, temperature-dependent conversion rates.
                                         PM (2.5): 25 µg/m³ (corresponds to approx. 0.02 mg/km)                        Figure 1 depicts the all relevant variables which are included in
                                                                                                                       the calculation of the conversion.
                                     Compared to today's Euro 6d legislation, this means a reduc-
                                     tion of NOX emissions by 99.9 percent and PM emissions by                         Knowledge of which vehicle- and powertrain-specific cycles can
                                     99.2 percent.                                                                     lead to the highest emissions is essential for reliable compliance
                                                                                                                       with all emission limits under RDE conditions. FEV has realized
                                                                                                                       an abstraction of such real driving conditions. The result is a deri-
                                                                                                                       vation of a concise number of parameters. This parameterization
                                                                                                                       allows machine learning techniques to be applied to identify the
                                                                                                                       worst case RDE cycles based on an analysis of a few hundreds
                                     Temperature calculation
                                                                                          QReaction                    of simulated cycles. This methodology has meanwhile been
                                          Exhaust mass flow                                                            successfully applied in many development projects.
                                                                                          TCat
                                     Exhaust temperature

                                     Efficiency                                           TCat, Element i
                                     calculation
                                      Engine out emissions                                                  Reaction enthalpy
                                                                  ηCO = f(TCat, SV, θ)                      calculation
                                                                                          Emissions
                                                          TCat    ηHC = f(TCat, SV, θ)    downstream        QReaction = f
                                                                  ηNOx = f(TCat, SV, θ)   catalyst          (Converted CO,
                                                           SV
                                                                                                            HC, NOx)

                                     Oxygen storage model                    θ
                                                 AFR upstr. Cat
                                                                          θ=f                λ nach Cat
                                                          TCat
                                                                  (TCat, SV, AFRu Cat)       θ                     	Calculation scheme for the efficiency
                                                           SV
                                                                                                                      calculation in the catalytic converter

4                                                                                                                                                                                              5
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS

    Catalyst and gasoline particle filter                                        Exhaust aftertreatment concept                                         the level needed for sufficient conversion efficiency.
    characterization                                                             to achieve zero-impact emissions                                       Therefore, a secondary air pump is used to flow air
    In the course of the development of FEV'S RDE emission sim-                  Five building blocks form the exhaust aftertreatment concept           across the electrically heated catalysts prior to the
    ulation methodology, it was identified that initially catalysts              for achieving zero-impact emissions.                                   engine start in order to heat up the main catalyst as
    could hardly be modeled with sufficient precision. The reason                1.	Optimization of NOX raw emissions during cat heating               well. Figure 4 illustrates the heat up process of the final
    for this lies in the mostly limited measurement data available               2.	Exhaust aftertreatment with readiness immediately                  system configuration. The convective heat transfer can
    from catalyst manufacturers and OEMs. However, for a precise                     after engine start                                                 clearly be seen in the lower half of the diagram. As soon
    prediction of the emissions under RDE boundary conditions,                   3.	HC emission adsorption                                             as the engine is started the higher exhaust mass flow
    knowledge of the conversion rate at highest space velocities                 4.	Increase of total catalyst volume                                  leads to even better convective heat transfer but at
    and in a wide temperature range is of high importance. FEV                   5.	GPF with improved filtration efficiency                            the same time also a reduction in the temperatures.
    there-fore developed its own equipment that can be used to
    characterize catalysts under exactly these conditions. The system            The individual building blocks are discussed below.                    Emissions can be further optimized by ensuring that
    shown in Figure 2 is designed and proven for exhaust gas mass                                                                                       the catalyst system maintains a high temperature
    flows up to those produced by turbocharged V12 engines to                                                                                           level. In a hybrid engine, this can be supported by the
    measure the conversion efficiency at high mass flows and cold                NOX optimized catalyst heating                                         operation strategy and re-activation of the electrically
    temperatures, such as they occur in a full load acceleration                 NOX aw emissions can be optimized by an adaptation of cat              heated catalysts.
    shortly after an engine start.                                               heating calibration. For very retarded ignition timings, a high
                                                                                 amount of fuel is required to generate an IMEP that matches
                                                                                 the FMEP. This results in dethrottling and a lower rate of internal
    Catalyst and gasoline particle filter aging                                  EGR. The cylinder peak temperature increases and remains on
    FEV has established a method for rapid aging of catalysts and                a high level over a longer period of time. As a result, the NOX
    GPFs, as well. For GPF aging, the burner test bench is modified              emissions increase. To achieve a drastic reduction in NOX emis-
    allowing oil to be burned in order to generate ash. Different                sions, an optimized cat heating calibration would therefore use
    methods have been investigated and finally oil injection was                 only a mild spark timing retardation. As a consequence, HC raw
    chosen. FEV generated a cycle and oil dosing strategy that is                emissions would increase, and additional measures need to be
    able to reproduce similar aging characteristics as they are found            implemented to address this.
    during vehicle durability testing.

                                                                                 Electrically heated catalysts
                                                                                 Two electrically heated catalysts are integrated upstream of the
                                                                                 main catalyst (4 kW per disc, 8 kW in total). The metallic substrate
                                                                                 heats up rapidly achieving light-off after a few seconds. However,
                                                                                 an engine start followed by cold exhaust gas flowing across the
                                                                                 electrically heated catalysts would drop their temperature below

                                                  Temperature in Three-Way Catalyst / °C
                                            800                                                         800
    	Equipment for catalyst
       characterization and
       conversion efficiency                700                                                         700
                                                          90                                                        90
       maps of an aged                                                                                                       50
       Euro6d-TEMP three                    600                                                         600          70
       way catalyst                                         70         50                                                   30     10
                                            500                                                         500
                                                                  30        10                                                                                  TW, out 1                TW, in 1
                                            400                                                         400                                                θ1                            m1

                                            300                    NOx emission conver-                 300                       HC emission conver-                                    TW, in 2
                                                                                                                                                                TW, out 2
                                                                   sion efficiency / %                                            sion efficiency / %                                    m2
                                            200                                                         200                                                θ2
                                                  0     100,000    200,000        300,000                     0     100,000       200,000   300,000
                                                          Space velocity / (1 / h)                                       Space velocity / (1 / h)                            Counterflow
                                                                                                                                                                            heat exchanger          Three-Way
                                                                                                                                                           θ3                                        Catalyst

                                                                                                                                                          Throttle

6
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                                       Emission reduction

                                                                                                                                                                                                            CO2 mass flow / (g/s)                             Exhaust gas mass flow / (g/s)
                                                                                                                                                                                                      4                                                 20

                                                                                                                                                                                                      3                                                 15
    Emission adsorption                                                    levels. This includes the volume of electrically heated catalysts.   The final results for the optimal oper-               2                                                 10
    before catalyst light-off                                              As a consequence, the space velocity at rated power is reduced       ation strategy are depicted in Figure 8.              1                                                  5
    One way to achieve emission adsorption is by dedicated coatings.       to values at which high conversion efficiency can be maintained      The remaining NOX emissions –
                                                                                                                                                                                                      0                                                  0
    In order to achieve a high adsorption efficiency, low temperatures     even in aged conditions.                                             although hardly visible – mainly result
                                                                                                                                                                                                            HC emissions / ppm                                HC mass flow / (g/s)
    are necessary. This matches with the lower incoming exhaust                                                                                 from the first seconds after engine start.         2000                                               0.020
    gas temperatures due to advanced ignition timings during cat                                                                                The oxygen storage capacity of the cat-            1500                                               0.015
    heating. A metal substrate is considered since this allows high        GPF with improved filtration efficiency                              alyst is completely filled at that time
                                                                                                                                                                                                   1000                                               0.010
    thermal inertia and thus low temperature increase in the first         Best-in-class Euro 6c and Euro 6d-TEMP engines without GPF           and initial rich operation is required
    seconds of engine operation and an even distribution of the            already achieve PM emissions in WLTC of only 0.12 – 0.28 mg/km.      to purge the catalyst before full NOX               500                                               0.005

    secondary air mass flow to the inlet face of the electrically heated   Compared to the zero-impact target of 25 µg/m³ (approx. 0.02         conversion efficiency is achieved. In                 0                                               0.000
    catalyst. With a temperature limit of 850 °C the adsorption catalyst   mg/km), there is the need for a further PM emission reduction        the remaining part of the WLTC, NOX                         NOx emissions / ppm                               NOx mass flow / (g / s)
                                                                                                                                                                                                    400                                               0.020
    dictates the position of the exhaust aftertreatment system to be       by 83 – 93 percent. This can well be achieved with a second          emission slips remain minimal. The
    not closed coupled which in turn has benefit regarding thermal         generation GPF.                                                                                                          300                                               0.015

    aging. Figure 5 shows a comparison of cat heating with and                                                                                                                                      200                                               0.010
    without HC adsorption, in this case downstream of the catalyst.                                                                                                                                 100                                               0.005
                                                                           Final results and outlook
                                                                                                                                                                                                      0                                               0.000
    For exhaust aftertreatment systems targeting at catalyst pre-heat-     The outlined exhaust aftertreatment system is finally assessed
                                                                                                                                                                                                            CO emissions / %                                  CO mass flow / (g / s)
    ing with a burner instead of electrically heated catalysts, the        in combination with a 2.0 l 4-cyl. turbocharged GDI engine in a                                                           0.8                                              0.100
    adsorption of the burner emissions via a small carbon canister         plug-in hybrid configuration. Figure 6 shows the final exhaust                                                            0.6                                              0.075
    positioned downstream of the catalyst might be a good solu-            aftertreatment system.
                                                                                                                                                                                                     0.4                                              0.050
    tion as well.
                                                                           Extensive DoE investigations have been performed in order to                                                              0.2                                              0.025

                                                                           achieve the zero-impact emission level while minimizing the fuel                            Raw emission results         0.0                                              0.000
                     Increased catalyst volume                             consumption penalty that arises from the electric pre-heating                                    in steady-state cat            15 10 5 0 -5 10 -15 -20 -25 -30                    15 10 5    0 -5 10 -15 -20 -25 -30

                        The catalyst volume is increase by 30 percent      of the catalysts. Figure 7 depicts the correlation between the                             heating operation mode                   Spark advance / 0 CA BTDC                       Spark advance / 0 CA BTDC

                          compared to the Euro 6d-TEMP base-line           electrical pre-heating energy and all resulting gaseous emissions.
                                                                                                                                                                                                                    E-catalyst
                             which is already using a bigger catalyst      Valid points fulfill the zero-impact target of NOX emissions lower
                                                                                                                                                                                                                       Support brick     E-catalyst           Main catalyst
                              volume compared to former Euro 6b/c          than 40 µg/m³ as well as a balanced SOC of the battery at the
                                                                                                                                                                                                                                                                         1000
                                                                           end of the cycle. The optimum for meeting the zero-impact target                                                                                                                               900
                                                                                                                                                                                                                                                                          800
                                                                           at best possible fuel consumption is found slightly below 0.4                                                                                                                                  700
                                                                                                                                                                                                                                                                          600
                                                                           kWh. HC and CO emissions remain well below FEV's anticipated                                                                                                                                   500
                                                                                                                                                                                                                                                                          400
                                                                           Euro 7 limits. But, due to the concept, those emissions are not                                                                                                                                350
                                                                                                                                                                                                                                                                          300
                                                                           as drastically reduced as the NOX emissions.                                                                                                                                                   275   Temperature /
                                                                                                                                                                                                      Time                                                                250
                                                                                                                                                                                                                                                                                °C
                                                                                                                                                                                                                                                                          225
                                                                                                                                                                         Heat up process of                                                                              200
                                                                                                                                                                                                                                                                          175
                                                                                                                                                                   the exhaust aftertreatment                                                                             150
                                                                                                                                                                       system with electrically                                                                           125
                                                                                                                                                                                                                                                                          100
                                                                                                                                                                             heated catalysts                                                                              75
     EV HAS DEVELOPED
    F                                                                                                                                                                                                                                                                      50
                                                                                                                                                                                                                                                                           25

    EXTENSIVE DEVELOP-                                                                                                                                                                                                                 Length

    MENT METHODS IN THE                                                                                                                                                                                        THC tailpipe emissions / ppm
    FIELD OF SIMULATION,                                                                                                                                                                          2,500

    AS WELL AS TESTING AND                                                                                                                                                     HC emissions
                                                                                                                                                                              with adsorption
                                                                                                                                                                                                  2,000

    AGING OF EMISSION-
                                                                                                                                                                                                  1,500

                                                                                                                                                                                                  1,000
    RELEVANT COMPONENTS,                                                                                                                                                                           500
    WHICH MAKE IT POSSIBLE                                                                                                                                                                           0
    TO DEMONSTRATE HIGH                                                                                                                                                                                    THC absorption efficiency of activated carbon trap / %
    ROBUSTNESS AND                                                                                                                                                                                 100

    FORECAST ACCURACY
                                                                                                                                                                                                    75

                                                                                                                                                                                                    50

                                                                                                                                                                                                    25

                                                                                                                                                                                                     0
                                                                                                                                                                                    TWC + GPF              0                1 0                  2 0                    3 0                   4 0
8                                                                                                                                                            TWC + GPF + Activated carbon trap
                                                                                                                                                                                                                                                Time / s                                            9
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                                                                      Emission reduction

                                                                                                                  E-catalyst +                                         Temperature / °C                                                                   Power / kW
     electrically heated catalysts are re-activated                                     Adsorption                  support                   GPF                800                                                                                12
                                                                                        brick                                                                                                                                                                           E-catalyst system:      Energy      Power

                                                                                                                                                                                                                                                                                                                    Energy / kW
     for short intervals during the cycle to ensure                                                                                                              600
                                                                                                                                                                                                                                                     8
     the temperatures stay on a sufficiently high                                                                                                                400
                                                                                                                           Main catalyst                         200                                                                                 4
     level at all times. Fuel consumption increases                                                                                                                0
                                                                                                                                                                                                            TTWC, avg   TInlet, BTWC
                                                                                                                                                                                                                                                     0
     by 4.3 percent compared to the Euro 6d-TEMP                                                                                                                       CO massATWC / g                                                                    battery energy content / kWh
     baseline.                                                                                                                                                   15                                                                                 1.6
                                                                             Secondary air pump                                                                                                           EU7 limit

                                                                                                                                                                                                                                        η CO / %
                                                                                                                                                                 10                                                                                 1.4
                                                                                                                                                                            Cum. masse          Conver. efficiency η
     The zero-impact emission concept presented                                                                                                                   5                                                                                 1.2
                                                          Final exhaust aftertreatment system
     here is extremely biased towards achieving                                                                                                                   0                                                                                 1.0
     minimal NOX emissions. For the fulfillment of                                                                                                                     HC masseATWC / g                                                                   Vehicle speed / (km / h)
                                                                                                                                                                 1.5                                                                                150
     "just" the Euro 7 emission limit, several concep-                                                                                                                                                     EU7 limit

                                                                                                                                                                                                                                        η HC / %
                                                                                                                                                                 1.0                                                                                100
     tual adaptations are possible, e.g. reduction of
                                                                                                                                                                 0.5                                                                                 50
     the number of electrical heated catalysts from            CO ATWC / (g/km)                                  Fuel consumption / (I / 100 km)
                                                         0.4                                                                                              8.0    0.0                                                                                  0
     two to one. Moreover, the adsorption catalyst
                                                                                                                                                                       NOx masseATWC / g                                                                  0   200      400   600     800 1,000 1,200 1,400 1,600 1,800
     could be eliminated, allowing the entire cata-      0.3                                                                                              7.5    0.9                                       EU7 limit                                                                 Time / s
     lyst system to be re-located back to a closed

                                                                                                                                                                                                                                        η NOx / %
                                                                                                                                                                 0.6
     coupled position.                                   0.2                                                                                              7.0
                                                                                                                                                                 0.3
                                                         0.1                                                                                              6.5    0.0
                                                                                                                                                                       0   200    400     600   800 1,000 1,200 1,400 1,600 1,800
                                                         0.0                                                                                              6.0                                    Time / s

                                                               HCATWC / (mg / km)                                                NOxATWC / (mg / km)             	Final results with optimized e-catalyst
                                                         40                                                                                               100       and hybrid operation strategy
                                                         30                                                                                               10
                                                                                                                                                                   By
                                                         20                                                                                               1                                                                                                 Summary
                                                                                                                                                                   Matthias Thewes · thewes@fev.com
                                                                                                                                                                   Andreas Balazs · balazs@fev.com                                                       Zero-impact emissions are possible
                                                         10                                                                                               0.1
                                                                                                                                                                   Surya Kiran Yadla · yadla@fev.com                                                 To achieve them, the exhaust gas aftertreatment
                                                          0                                                                                               0.01     Michael Görgen · goergen_m@fev.com                                           needs to operate on high conversion efficiency as soon as
                                                               0.2     0.3        0.4       0.5      0.6   0.2   0.3       0.4          0.5         0.6            Jörg Seibel · seibel_j@fev.com                                            the engine is started
                                                                                                                                                                   Johannes Scharf · scharf@fev.com                                       > Electrically heated catalysts in combination with
                                                               Electrical energy consumption for catalyst heating / kWh
                                                                   Model points        Valid points        Optimum                                                                                                                         convective heat transfer prior to the engine start is identified
                                                                                                                                                                                                                                         as one possible enabler for this
                                                         	DoE results showing correlations between gaseous emissions and                                                                                                             >H
                                                                                                                                                                                                                                         C emission adsorption can support low NOX emissions by also
                                                            fuel consumption vs. the electrical energy used for catalyst heating
                                                                                                                                                                                                                                        allowing to apply an adapted catalyst heating calibration
                                                                                                                                                                                                                                       > Second generation GPFs enable a high filtration efficiency
                                                                                                                                                                                                                                           Further improvement of the system is possible with even higher
                                                                                                                                                                                                                                              convective heat transfer
                                                                                                                                                                                                                                                The exhaust aftertreatment concept can be degraded
                                                                                                                                                                                                                                               for purely meeting Euro 7 requirements
                                                                                                                                                                                                                                                    FEV has established the required know-how to
                                                                                                                                                                                                                                                     support you in the development of your next
                                                                                                                                                                                                                                                          generation exhaust aftertreatment system

10                                                                                                                                                                                                                                                                                                                                11
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                   Mild-Hybrid Diesel

     MILD-HYBRID DIESEL

     MILD-HYBRID-DIESEL-
                                                                                              T
                                                                                                         he main concept was to locate       compared to a conventional arrange-                               the exhaust system heats up, a thermal
                                                                                                         the exhaust aftertreatment sys-     ment (Figure 2). The introduction of a                            lag and overall temperature offset is seen

     POWERTRAIN WITH A PRE-TURBINE                                                                       tem (EATS) directly downstream
                                                                                                         of the exhaust manifold, but up-
                                                                                                                                             48V electric system to the vehicle enables
                                                                                                                                             the incorporation of a pre-turbine after-
                                                                                                                                                                                                               as a result of the higher thermal mass
                                                                                                                                                                                                               upstream of the turbine. The heat loss

     EXHAUST AFTERTREATMENT                                                                   stream of the turbine as shown in Figure
                                                                                              1, so that the best CO2 reduction potential
                                                                                                                                             treatment system via the integration of
                                                                                                                                             an e-TC which compensates the loss of
                                                                                                                                                                                                               profile over the PT-EATS leads to a cal-
                                                                                                                                                                                                               culated cumulative enthalpy loss of ~ 4
                                                                                              and the best aftertreatment performances       pressure and temperature caused by the                            percent over a WLTC (Figure 2). In order
     The potential to achieve a simultaneous reduction in both NOx and CO2 emissions via      can be achieved simultaneously.                increased thermal inertia of the PT-EATS.                         to maintain the boost pressure levels in
     fitting of a pre-turbine exhaust aftertreatment system (PT-EATS) in combination with a                                                                                                                    such low enthalpy phases, the electric
     mild-hybrid concept was investigated via simulation. The main engine and hybrid system   The engine hardware and PT-EATS were           In the early phases of operation, the tem-                        turbocharger generates additional boost
     hardware were specified and thereafter, the operating strategies for recuperation and    designed and optimized via simulation          perature before turbine is significantly                          pressure, it is also used to recuperate
     turbocharger control were determined to enable the system to meet a defined tail-        to identify the best layout of the catalysts   lower than without the PT-EATS, owing                             excess energy whenever possible.
     pipe NOX emissions value of 40 mg/km with a conformity factor (CF) of 1 over all         and to quantify the potential benefits for     to the increased thermal mass, but as
     real-world driving cycles. The performance and drivability of the demonstrator           CO2 and NOX emissions reduction. The
     are defined to be equivalent to the                                                      48V system, made up of a belt starter
     base vehicle.                                                                            generator (BSG) with the associated                                     Urea Injector 1
                                                                                                                                                                                                          eTurbo
                                                                                                                                                                                                           VGT                    Urea Injector 2
                                                                                              control components, an electric assisted                                         S
                                                                                                                                                                               C SCRF
                                                                                              turbocharger (e-TC) and the 48V battery                                          R                                                             SCR
                                                                                                                                                                         Mixer
                                                                                                                                                                                                                                   Mixer
                                                                                              as well as PT-EATS, were integrated to
                                                                                              the existing engine model. The simula-                                  DOC        PreTurbo                                             Underfloor
                                                                                                                                                                                                                        Filter
                                                                                              tions optimized EATS component sizes to                                                                                   Cooler
                                                                                                                                                                                               Valve
                                                                                              achieve successfully the integration within                                                                                             LP-EGR
                                                                                                                                                                                               Cooler                   Valve
                                                                                              the engine bay. The e-Turbo was dimen-                                                                                                      HFM        Air Filter
                                                                                                                                              AC
                                                                                                                                                                                    HP-EGR         WCAC
                                                                                              sioned in GT Power and moreover the

                                                                                                                                                   BSG
                                                                                              EGR strategy was optimized to meet the          DC                                            Throttle                   Throttle
                                                                                                                                                                  DC                                                               2.0 L I4 EU6c
                                                                                              extremely low engine-out NOx emission                                DC
                                                                                                                                                                                                                                   430 Nm @ 1750 rpm
                                                                                                                                                         48 V             12 V
                                                                                              targets. Furthermore, the recuperation                     Li-lon          Lead-Acid                                                 132 kW @ 4000 rpm
                                                                                              potential was established by using the                     Battery         Battery             HCU
                                                                                              simulation model. The original exhaust
                                                                                              manifold was rotated 180 °C to enable           Pre-turbine aftertreatment system and 48V powertrain setup
                                                                                              the integration of the turbocharger and
                                                                                               a larger EGR cooler was inserted to allow
                                                                                                  EGR to be used during full-load oper-             Temperature at TC inlet / 0C
                                                                                                                                             600                                                                                                3.0 .107
                                                                                                    ation. Additional design modifica-
                                                                                                      tions were made to the intercooler     500                                                                                                2.5 .107
                                                                                                        bracket, the water lines and air
                                                                                                         lines to allow the complete         400                                                                                                2.0 .107
                                                                                                           packaging within the engine
                                                                                                            bay of the chosen J-Segment      300                                                                                                1.5 .107 cum.
                                                                                                            demonstrator vehicle.                                                                                                                        enthalpy / J
                                                                                                                                             200                                                                                                1.0 .107

                                                                                                           Enthalpy impacts                  100                                                                                                5.0 .106

                                                                                                          Placing the aftertreatment           0                                                                                  WLTC          0.0 .100
                                                                                                          system upstream of the
                                                                                                         turbine results in an altered             0            200      400        600      800       1,000   1,200    1,400     1,600    1,800
                                                                                                        enthalpy and thermal inertia                                                          Time / s
                                                                                                       profile over the turbocharger
                                                                                                                                                   Temperature, EATS after TC                 Temperature, EATS before TC                  Enthalpy, EATS after TC
                                                                                                                                                   Enthalpy, EATS before TC                   Boosting required                            Recuperation possible

                                                                                                                                              Temperature behavior and enthalpy input at the turbocharger

12                                                                                                                                                                                                                                                                      13
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                                                                                 Mild-Hybrid Diesel

            BSFC / g/kWh                                                                                     Pumping mean effective pressure v/ bar                                                                     6%                                      3%             30 %              	Fuel penalty as function of different
     280                                                                                            - 0.30
                                                                                                                                                                                                                                                                                                    EATS volumes and EGR concept
                                                                                                    - 0.35                                                                                           rel. fuel 120
     270                                                                                                                                                                                          penalty by
                                                                                                    - 0.40                                                                                    e-TC boosting / 100
     260
                - 1.8 %                       - 3.3 %                                                                                                                                                  100 %
                                                                                                    - 0.45                                                                                                      80
     250
                                                                                                    - 0.50
                                                                                                                                                                                                               60
     240
                                                                                                    - 0.55       + 32 – 44 %
     230                                                                                                                                                                                                       40
                                                                                                    - 0.60
     220                                                                                                                                                                                                       20
                                                                                                    - 0.65
                                                                              - 1.1 %
               - 0.3 %
     210                                                                                            - 0.70                                                                                                      0
           0        125    250     375       500        625         750       875       1,000                0        125       250     375      500       625    750    875     1,000        EATS volume /L           4,5 L                3L                2,4 L              3L
                                                                                                                                                                  mech. power / W                                                   HP-EGR only                            HP & LP-E-GR
           e-TC recuperation           BSG recuperation             4 bar, 2000 U / min         11 bar, 2000 U / min

     	Comparison of recuperation strategies at 2 part load points

                                                                     pump losses, as seen in Figure 3, right. It                      there was minimal benefit to upsizing                   the acceleration time increases to 13.0 s,         package space. All the above variables          on the difference between desired and
     Recuperation potential                                          should be noted however that increasing                          the e-TC as the electrical boost required               confirming that an e-Turbo is required. An         were combined to create an optimised            actual turbine torque. An additional
     The recuperation potential of the sys-                          recuperation increases fuel consumption                          during transient operation would be in-                 increase in the E-machine power above              air path strategy. Combining LP and HP-         e-boost control factor is introduced to
     tem was investigated at two part load                           as additional power is needed to generate                        creased so a smaller turbine was chosen.                11 kW showed no significant reduction in           EGR, with a comparatively small turbine         balance and adjust the responsiveness of
     operating points, shown in Figure 3. The                        the same effective power.                                        The key criteria in determining the size                response time (9.0 s to 9.4 s) as accelera-        and an 11 kW electric motor allows for          the model-calculated torque demand to
     comparison of the brake specific fuel con-                                                                                       of the e-machine used is the transient                  tion was limited by the electrical machine         the lowest possible boost requirement           the e-machine against the electric energy
     sumption for 2 recuperation strategies                                                                                           response behavior of the vehicle. An                    speed to 180000 min-1.                             during transient driving conditions. The        consumption. The fuel consumption pen-
     was investigated and shown in Figure 3.                         Turbocharger sizing                                              acceleration from a standstill to 100 km/h                                                                 additional energy requirement for this          alty and NOx engine-out emissions as a
     Recuperation at the turbocharger via VGT                        The sizing of the e-TC was considered, as a                      was simulated with different sizes of e-TC                                                                 configuration over a WLTC was approx.           function of the e-boost control factor are
     is compared with the extraction of the                          larger turbine could reduce fuel consump-                        to see which could achieve a comparable                 EGR strategy                                       52 Wh when omitting recuperation at the         shown, in Figure 6 for the WLTC.
     same power over the BSG via an operating                        tion via optimized pumping losses, but,                          acceleration behavior to the base vehicle               Regarding the potential to reduce the              BSG or e-Turbo.
     point load shift. The latter strategy shows                     as typical passenger car driving scenarios                       (8.7 s in the sprint to 100 km/h). These                cost and complexity of the EGR circuit,                                                            When applying small e-boost control
     a more energy-efficient path by up to 3.3                       are not significantly impacted by pumping                        simulations are seen in Figure 4. Illustrat-            the use of an HP-EGR-only strategy was                                                             factors, the electric machine only sup-
     percent, as closing the VGT increases the                       loss based fuel consumption penalties,                           ing that without electrical boost support,              investigated which would consist of recu-          Air path control                                ports during very high differences be-
                                                                                                                                                                                              perating excess exhaust gas energy, while          The electrical VGT turbocharger requires        tween desired and actual turbine torque,
                                                                                                                                                                                              controlling the VGT position to achieve            a dedicated control strategy to optimize        while for higher control factor values, the
            Speed / kmh                                             TC speed / krpm                                         e-TC boosting / kw
     120                                                      210                                                      18                                                                     the required back pressure to drive higher         the different operating states. For this con-   e-machine supports for smaller deltas
                                                                                                                                                                               6kW eTC
                                                              180                                                      16
                                                                                                                                                                               11kW eTC
                                                                                                                                                                                              EGR rates at comparable boost pressure.            cept configuration, the electric machine is     in turbine torque. As such, the NOx en-
     100                                                      150                                                      14
                                                                                                                       12                                                      17kW eTCn      The results showed, that including the             mainly used for transient support during        gine-out emissions are reduced at higher
      80                                                      150
                                                              120
                                                                                                                       10                                                      PT-EATS w/TC   LP-EGR path reduces the required elec-             boost pressure build-up and recuperation        e-boost control factor values, whereas
                                 9.4                                                                                    8
      60
                                 9.0                           90                                                       6                                                      Base vehicle   trical energy over the WLTC by about 30            during deceleration or in overrun oper-         the fuel consumption increases signifi-
                                             13.0
      40                                                       60                                                       4                                                                     percent, therefore both HP- and LP- EGR            ation. The conventional boost pressure          cantly in consequence of the increased
                                 8.7         10.3
                                                               30                                                       2
      20                                                        0                                                       0
                                                                                                                                                                                              are used. As the PT-EATS volume was                control for the VGT was extended with           electric power demand. These trends
           0    2     4    6 8 10            12     14              0     2      4      6 8 10         12        14         0     2      4      6      8     10     12                        found to show only minor impacts on                an advanced model-based control for the         were combined to determine the target
                            Time / s                                                     Time / s                                             Time / s
                                                                                                                                                                                              the fuel consumption, compared to the              power, respectively torque of the electric      operation area.
      Simulation of acceleration from standstill to 100 km/h                                                                                                                                 EGR strategy influence, Figure 5, the EATS         machine. In this approach the torque of
                                                                                                                                                                                              volumes were chosen to fill the available          the electric machine is calculated based

             HE KEY CRITERIA IN DETERMINING THE SIZE
            T
            OF THE E-MACHINE USED IS THE TRANSIENT
            RESPONSE BEHAVIOR OF THE VEHICLE

14                                                                                                                                                                                                                                                                                                                                             15
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                      Mild-Hybrid Diesel

                                                                      Fuel penalty @                            Engine-out NOx /
                                                                      const. TP-NOx / %                                 mg / km
                                                                 12
                                                                                                                     Target
                                                                                                                      area
                                                                                                                                     400
                                                                                                                                                                    S THE RECUPERATED
                                                                                                                                                                   A
                                                                 20                                                                  380
                                                                                                                                                                   ENERGY EXCEEDS THE
                                                                  8                                                                  360                           ELECTRICAL ENERGY
                                                                  6                                                                  340                           CONSUMPTION, APPROX.
                                                                  4                                                                  320                           30 PERCENT IS USED TO
                                                                  2                                                                  300                           CHARGE THE 48V BATTERY
                                                                  0                                                                  280
                                                                      0      20           40         60              80        100
                                                                                  e-boost control factor / %

                                                                                                                                                                    The balance of the electrical energy within the 48V system over
                                                                                                                                                                    the WLTC is shown in Figure 8. Recuperation takes place almost
                                                                                                                                                                    exclusively by the BSG, whereas the energy consumption is split in
                                                                                                                                                                    roughly equal parts between the supply of the consumers in the 12V
                                                                                                                                                                    network and to support the electrical boosting. As the recuperated
                                                                                                                                                                    energy exceeds the electrical energy consumption, approx.
                                                                                                                                                                    30 percent is used to charge the 48V battery.

                                                                                                                                                                   WLTC                                                                  	Schematic architecture of
      Fuel consumption penalty                                                                                                                                                                                                             the investigated concept
     and NOx engine-out emissions                                                                                                                                                                      128
     as a function of the e-boost
     control factor.
                                                                                                                                                                                            - 437                                        Electric energy balance (Wh)
                                                                                                                                                                                                                                              State of charge
                                                                                                                                                                                                       309                                  Consumption
                                                                                                                                                                                                                                            Recuperation
                                                                                                                                                                           1 % by e-TC                           BSG boost 1 %

     Overall hybrid strategy optimization                                  liable supply for the on-board 12V network under all operating
     The additional benefits of the 48V mild-hybrid system architecture    conditions and simultaneously maximizes the potential of the                   by BSG   99 %                             by 12 V consumer   51 %      48 %    e-TC boost
     shown in Figure 7 were evaluated. A 48V belt starter generator        various 48V components to balance transient support during
     replaces the conventional 12V generator, a 48V battery with a         boost pressure build-up and recuperation potential at engine
     capacity of 0.5 kWh, and the electrically supported electrical VGT    overrun operation and high enthalpy flow upstream turbine.
     turbocharger were integrated with the 12V on-board power supply                                                                                               Electric energy                                     Electric energy
                                                                                                                                                                    recuperation                                        consumption
     provided via a bidirectional DC/DC converter. When optimizing
     the control of the electrical VGT turbocharger, a priority manager
     governs available power for the different consumers, based on
                                                                                               ICE
     the current state of the electric system. The simulation model
     uses a higher-level energy management strategy to ensure re-                                               AT                                                  The second part of this paper in an upcoming SPECTRUM issue                       By
                                                                                                                              12 V
                                                                                                      Starter

                                                                                      BSG                                                                           will detail the PT–EATS system optimization and the overall                       Dr. Lynzi Robb
                                                                                               eTC
                                                                                                                               12 V-
                                                                                                                                            DC 12 V Net
                                                                                                                                                                    system performance over key RDE cycles.                                           robb@fev.com
                                                                                                                              Battery
                                                                                                                                           DC
                                                                                                                              48 V
                                                                                                                                                 48 V-
                                                                                                                                                Battery

                    Balance of electrical energy in the 48V system

16                                                                                                                                                                                                                                                                            17
"DEVELOPMENT SOLUTIONS FOR A SUSTAINABLE MOBILITY" - FEV
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                    Efficient Mobility

     EFFICIENT MOBILITY

     PREDICTIVE FUNCTIONS IN
     THE HYBEX3 CONCEPT VEHICLE

                                                                                                        C
     The hybridization of powertrains is an important step toward efficient and clean                              ombined with the development of predictive and automat-
     mobility. In particular, the possibility of shifting the operation of the combustion                          ed driving functions, further potentials can be tapped. The
     engine to ranges with a higher efficiency level and representing purely electric                              key factor for an actual reduction of the energy require-
     driving modes is one of the main advantages of hybrid drives. This shifting of the                            ment under real driving conditions is a precise forecast
     load point can be further optimized on the basis of route data that includes the                   of the future development of a traffic situation. This forecast can
     expected vehicle speed as well as the road gradient, and is considered to be the                   be based on a multitude of potential sources, such as sensor data,
     state of the art with regard to modern hybrid drives                                               high-resolution maps, and vehicle communication, whereby all the
                                                                                                        data is fused into a comprehensive environmental model.

                                                                                                        Based on the information from this model, the longitudinal guid-
                                                                                                        ance of the vehicle and the powertrain control can be optimized.
                                                                                                        In cooperation with the Institute for Combustion Engines of RWTH
                                                                                                        University Aachen, Germany, FEV has developed a function structure
                                                                                                        that is capable of using a multitude of potential data sources. This
                                                                                                        creates a solution space for predictive speed profile optimization.
                                                                                                        This speed profile can then be used in order to optimize the operation
                                                                                                        of torque distribution between the hybrid components.

                                                                                                        The function structure was integrated in a hybrid prototype vehicle
                                                                                                        constructed jointly with DENSO. A robust, real-time model predic-
                                                                                                        tive control algorithm is used in order to optimize the longitudinal
                                                                                                        guidance of the vehicle.

                                                                                                        The HYBex3 concept vehicle
                                                                                                        The HYBex3 (”HYBrid power exchange 3 modes“) vehicle was devel-
                                                                                                        oped in order to determine the impact of a cost-effective DHT trans-
                                                                                                        mission concept on the driveability of the vehicle and test it under
                                                                                                        real conditions. It was developed jointly with DENSO AUTOMOTIVE
                                                                                                        Germany. The base vehicle is a MINI Cooper with a turbocharged
                                                                                                        100 kW three-cylinder combustion engine. The serial transmission
                                                                                                        was replaced with the hybrid transmission to be examined, which
                                                                                                        was specially developed for the application case.

                                                                                             HE HYBEX3 VEHICLE WAS DEVELOPED IN
                                                                                            T
                                                                                            ORDER TO DETERMINE THE IMPACT OF A
                                                                                            COST-EFFECTIVE DHT TRANSMISSION CONCEPT
                                                                                            ON THE DRIVEABILITY OF THE VEHICLE AND
                                                                                            TEST IT UNDER REAL CONDITIONS

18                                                                                                                                                                               19
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                                      Efficient Mobility

     The powertrain topology is equivalent to a mixed hybrid equipped           combustion engine, without compromising the overall dynamic           Predictive functions                           Further information can be obtained from        In contrast, the camera sensor can only
     with two electric engines (EE) in a P2/P3 layout. The P2 machine           of the powertrain. The operating strategy was optimized with a        The function structure developed for pre-      the on-board navigation systems, which          provide estimates regarding the relative
     is located between the electrohydraulically powered clutch and             Design of Experiments. For this purpose, the parameters of the        dictive longitudinal dynamic control is        indicate speed limits, road gradients and       speed and the distance, but can precisely
     the two-stage spur gear component. The synchronization ele-                stop-start strategy of the combustion engine were optimized           designed in such a way that a multitude of     curvatures as well as, potentially, inter-      determine whether the detected object
     ments are also actuated electrohydraulically. The P3 machine is            simultaneously with the parameters of the battery charging            data sources, optimization routines, and       section data for the most probable path         is in the same lane as the vehicle under
     positioned at the transmission output and therefore has a fixed            strategy. For the final parameterization, a compromise between        powertrain structures can be represented       of the vehicle via an "electronic horizon".     consideration. After the fusion of several
     transmission ratio to the wheel.                                           the layouts for different driving cycles was selected.                in said function structure.                    If the navigation system is connected to        data sources, an aggregated object list
                                                                                                                                                                                                     the internet, data on average speeds along      is created, which only contains valid and
     Various operating modes can be represented with this DHT                   The distribution of the torques of the two electric engines,          The first step is an aggregation and fusion    the planned route and traffic jams can          relevant data for all detected objects, and
     transmission. For purely electric driving, the combustion engine           both in parallel operation and in fully electric driving, is deter-   of the available data into an environmen-      be provided.                                    generates a corresponding environmental
     is stopped and the clutch is opened. Electric engine P2 can                mined by an online optimization patented by FEV. The search           tal model, followed by a prediction of                                                         model.
     therefore be operated in both transmission stages. In addition             algorithm varies the torque distribution until the energetically      the traffic situation. This enables an op-     Additional data can be obtained through
     to a high starting torque in the first gear, this enables a maximum        optimal case is found. In doing so, both the battery limits and       timization of the speed profile. On the        the future connection of vehicles using 5G      Before an optimization of the vehicle
     vehicle speed of 140 km/h in the second gear.                              the power limits of the electric engines are taken into account       basis of that, an acceleration control of      or ETSI ITS G5. This Vehicle-to-everything      trajectory can be carried out, there must
                                                                                for the current situation.                                            the vehicle is carried out. The planned        (V2X) communication should include,             be a forecast of the development of the
     In hybrid operation, serial or parallel driving is possible. In parallel                                                                         speed profile can also be used in order        among other things, the positions, di-          current situation. This forecast is based
     operation, one of the two gear sets is engaged. In serial operation                                                                              to adjust the charging status strategy. If     rection, and speeds of other vehicles, as       on the relevant objects that the environ-
     mode, the transmission is shifted to neutral. The combustion                                                                                     the desired charging performance is de-        well as the layout of intersections and the     mental model provides. The first step is
                                                                                    EMS w /           2 Gear          3-Cylinder
     engine is then exclusively connected to electric engine P2 while            reduction gear    transmission      gasoline ICE      Front axle     termined, the torque distribution between      status of traffic light systems. The vehicle    the determination of the speed limit along
     electric engine P3 operates the wheels. All gear changes are                                                                                     the powertrain components is carried out       communication can therefore provide             the prediction horizon. Based on that and
     synchronized entirely electrically, so that the friction clutch can          P2 EM                                                               on the basis of said performance and the       data that goes beyond the horizon de-           the current condition of detected vehicles
     remain closed even in hybrid operation. The serial operation in                                                                                  wheel torque requirement.                      tectable via on-board sensors.                  driving ahead, the speed and position
     the low speed range and the parallel operation at higher speeds                                                                                                                                                                                 trajectory of these vehicles is forecast.
     enable a significant increase of the system efficiency level.                                                                                    The precise forecast of the current traffic    Since the same object can therefore be
                                                                                                                                                      situation requires the aggregation of all      detected multiple times by various data         On the basis of this, a solution space is
     The operating strategy provides for the combustion engine                                                                                        available data. This includes, for instance,   sources, the data aggregation must also         spread out in which the downstream op-
     being operated at a very low dynamic and the implementation                                                                                      RADAR sensors, LIDAR sensors, or opti-         include a functionality for data fusion. This   timization algorithm can operate. The
                                                                                  P3 EM
     of fast load changes by the electric path. The transmission ratios                                                                               cal cameras that traffic participants can      is especially advantageous for hardware         function structure developed by FEV and
     enable a significant reduction of the rotational speed of the                                                                                    identify with the help of image recogni-       setups with different types of sensors,         the Institute for Combustion Engines
                                                                                 HYBex3 transmission topology                                        tion techniques. Usually, these sensors        e.g. a RADAR sensor and camera sensor.          enables the implementation of differ-
                                                                                                                                                      indicate the type (passenger car, truck,       The RADAR sensor can precisely define           ent algorithms to this end. Depending
                                                                                                                                                      pedestrian, etc.), the relative positions      the distance to and the relative position       on the requirement, simple, rule-based
                                                                                                                                                      and, potentially, the relative speed of the    of a vehicle driving ahead, but cannot          approaches, as well as model predictive
                                                                                                                                                      detected objects.                              determine the lateral position of the ve-       control or discrete dynamic programming
                                                                                                                                                                                                     hicle in relation to the road markings.         methods can be represented.

                                                                                                                                                              Input                Data handling and interpretation                          Powertrain control optimization

                                                                                                       	HYBex3 concept vehicle
                                                                                                          based on a MINI Cooper                                                                                                 Longitudinal
                                                                                                                                                                                                         Situation                                    Acceleration             ICE torque
                                                                                                                                                             Camera                                                               trajectory
                                                                                                                                                                                                         prediction                                     control                  request
                                                                                                                                                                                                                                 optimization
                                                                                                                                                                                      Data
                                                                                                                                                                                  aggregation
                                                                                                                                                            Electronic                                                                                Torque split             EM1 torque
                                                                                                                                                                                      into
                                                                                                                                                             horizon                                                                                  optimization              request
                                                                                                                                                                                  environment
                                                                                                                                                                                     model

                                                                                                                                                              V2X,                                                                                    Charge power             EM2 torque
                                                                                                                                                                                                                                 SoC strategy
                                                                                                                                                            Radar …                                                                                    calculation              request

                                                                                                                                                       Function architecture for predictive functions

20                                                                                                                                                                                                                                                                                                 21
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                          Efficient Mobility

             Input                       Data aggregation                                         Situation prediction

                                 Data fusion          Fellow vehicle          Relevant fellow            Fellow             Position
            Camera                                                                                                                              Distance / m                                  Velocity / (km / h)                               Acceleration / (m / s2)
                                                           data                  selection             prediction        solution space   400                                            50                                                1
                                                                                                                                                                                         40                                              0.5
                                                                                                                                          300
                                                                                                                                                                                                                                           0
           Electronic                                   Traffic light           Traffic light         Green phase                                                                        30
            horizon                                        data                  selection             selection                          200                                                                                           - 0.5
                                                                                                                                                                                         20
                                                                                                                                                                                                                                          -1
                                                                                                                                          100                                            10                                             - 1.5
                                                      Road gradient
           Radar, ...                                                                                                                       0                                             0                                               -2
                                                          data
                                                                                                                                                0    5     10   15    20   25   30            0    5       10       15   20   25   30           0    5       10     15    20   25   30
                                                                                                                                                Time / s                                      Time / s                                          Time / s
                                                                                 Velocity
              V2X                                      Speed limits
                                                                              solution space
                                                                                                                                                           POSITION                                       VELOCITY                                     ACCELERATION

     	Function architecture
        for data aggregation and
        situation prediction

     Application in the vehicle
     To test the function structure, a real time-compatible model predictive                By
     control (MPC) was implemented in the rapid prototyping control unit of                 Dr. Georg Birmes . birmes@fev.com
     the HYBex3 concept vehicle and various test scenarios were carried out. In             Dr. Rene Savelsberg . savelsberg@fev.com
     a first demonstration, the functionality and real-time compatibility of these
     scenarios for a predictive adjustment of the HYBex3 concept vehicle was                Marius Wegener
     proven. With an efficient implementation of the MPC using the qpOASES                  Prof. Jakob Andert
     tool, an optimization of the speed curve for a horizon of 10 s can be carried          Institute for Combustion Engines,
     out within less than 100 µs.                                                           RWTH Aachen University, Germany

                                                                                                                                                      0.0 %                           37.7 km / h - 0.4 m / s2
     In the future, the modular design of the function structure can be used to             Ulrich Schwarz
     expand the forecast horizon of the vehicle – for instance, with traffic lights         DENSO AUTOMOTIVE
     ahead – or to represent predictive, automated driving functions such as                Deutschland GmbH
     Predictive Cruise Control (PCC).                                                                                                       ACCELERATOR PEDAL                                            VELOCITY                                  ACCELERATION

                                                                                                                                            Experimental validation of the functions on the test track

22                                                                                                                                                                                                                                                                                       23
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                      Fuel Cell

     FUEL CELL

     FUEL CELL SYSTEMS FOR                                                                                  Use cases for fuel cell electric vehicles                             Although in the passenger car segment, higher quantities are

     HEAVY DUTY APPLICATIONS:                                                                               As fuel cell systems and batteries do not emit hazardous green-
                                                                                                            house gases during their utilization, their implementation into
                                                                                                                                                                                  generally achieved, commercial vehicles could first possibly
                                                                                                                                                                                  experience greater market penetration of fuel cell electric pow-

     FROM CONCEPT TO                                                                                        passenger cars, light commercial vehicles and heavy duty ap-
                                                                                                            plications can contribute to the reduction of CO2 emissions
                                                                                                                                                                                  ertrains. However, compared to the passenger car segment, the
                                                                                                                                                                                  implementation of fuel cell systems in heavy duty applications
     SYSTEM VALIDATION                                                                                      from the transport sector, if the hydrogen for their operation is
                                                                                                            generated with e.g. electricity from renewable energy sources.
                                                                                                                                                                                  brings new challenges. One of the major challenges is the
                                                                                                                                                                                  required lifetime of approximately 20,000 h, which is almost
                                                                                                            Compared to battery electric vehicles (BEV), fuel cell electric       three times higher than for passenger cars.
     Since the transport sector has not seen the gradual decline of CO2 emissions as other sectors          vehicles (FCEV) allow for larger driving ranges, shorter refueling
     have, it is more than ever at the forefront of public attention, as well as priority for research.     times - comparable to the refueling process of vehicles with diesel
     Particularly for the heavy duty (HD) transport with its high specific CO2 emissions, major research
     and development programs are ongoing for the implementation of low- and zero-emission
                                                                                                            or gasoline engines - as well as reduced powertrain weight, and
                                                                                                            therefore higher payloads.                                                  SPECIALLY FOR HEAVY
                                                                                                                                                                                       E
     powertrains. Not only does the reduction of the fleet’s average CO2 emissions to prevent high                                                                                     DUTY VEHICLES WITH
     financial charges for exceeding CO2 emission limits, but also the system efficiency, durability,
     reliability and total cost of ownership (TCO) need to be considered to find competitive
                                                                                                            The decision as to which powertrain is the most suitable for an
                                                                                                            application and use case depends on several factors such as
                                                                                                                                                                                       HIGH ANNUAL MILEAGE,
     alternatives to internal combustion engines for heavy duty transport.                                  costs, efficiency and durability. However, the focus must be on            FUEL CELL ELECTRIC
                                                                                                            the benefit to the customer.                                               POWERTRAINS SHOULD
     Exclusive usage of pure battery electric powertrains for heavy duty applications is not yet a
     viable option, as large batteries are necessary, which lead to high powertrain weight, increased       Considering driving range and vehicle weight, Figure 1 provides a
                                                                                                                                                                                       BE FAVORED
     power demand and reduced payloads. That is why proton ex-change membrane fuel cells                    general overview about suitable electric powertrains for different
     (PEMFC) in combination with smaller batteries represent a promising approach for heavy duty            vehicles. Due to their high efficiency, but also lower power den-
     vehicles with electric drives.                                                                         sity, battery electric powertrains (BEV) are expected to be more
                                                                                                            suitable for light duty vehicles with small driving ranges, whose
     The Institute of Combustion Engines (VKA) of the RWTH Aachen University, Germany and FEV               daily trips are primarily inner-city. For larger driving ranges and
     Europe GmbH investigate, inter alia, the implementation of PEMFCs in transport applications. In        heavy duty applications, fuel cell electric powertrains, supple-
     order to assess alternative powertrains for commercial vehicles, the investigation of total cost of    mented with small-size batteries for peak power and
     ownership for different powertrains, considering different scenarios for electricity generation from   re-cuperation (FC-HEV) should be
     renewable sources, is important to make decisions on the development of future HD powertrain           favored in partic-
     systems.

     The following details FEV’s and VKA’s development and validation of fuel cell systems
     with advanced operating strategies for heavy duty applications up to 250 kWnet power
     output. Fuel cell degradation mechanisms and their mitigation strategies
     are introduced to optimize the hybrid operating strategy
     and to prove durability and reliability of the
     designed systems.                                                                                                                                                                                                              The
                                                                                                                                                                                                                           importance of
                                                                                                                                                                                                                  TCO in the commercial
                                                                                                                                                                                                                        vehicle segment
                                                                                                                                                                                  A main technology driver within the commercial vehicle segment
                                                                                                                                                                                  has always been Total Cost of Ownership (TCO). Beneath the
                                                                                                                                                            ular, also with       vehicle price and the resell value, the operational costs represent
                                                                                                                                                   regard to overall power-       the most relevant factor of TCO. An FEV study on the TCO for dif-
                                                                                                                                         train weight. A combination of a fuel    ferent commercial vehicle segments analyzed various use cases
                                                                                                                               cell system and a medium-sized battery (FC-        to determine whether conventional diesel powertrains, battery
                                                                                                                    PHEV) is often the most promising option. The question        electric or fuel cell electric powertrains will have the lowest TCO
                                                                                                            about where the sweet-spot of the fuel cell system power and          in the future. Considering target driving profiles, as well as the
                                                                                                            the battery power/capacity is, remains a subject of discussion        mainstream fuel cell boosters and inhibitors, the study came
                                                                                                            and is still a major focus of research.                               to the result that especially for heavy duty vehicles with high

24                                                                                                                                                                                                                                                      25
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                                                                                 Fuel Cell

                                                                                                                                                                                                                                                                                                                Fuel Cell Stack
                                                                                                                                                            Long
                                                                                                                                                            Distance                                                                                                      Coolant                Ion
                                                                                                                                                                                                                                                 Expansion tank            pump
                                                                                                                                FC-HEV                                                                                                                                                           exchanger

                                                                                                                                                                                                                                                                Compressor Motor
                                                                                                                                                                                                                                                               Inverter                          Humidifier
                                                                                                                FC-PHEV
                                                                                                                                                                                                                                                              Air filter Compressor Charge
                                                                                                                                                                                                                                                                                   air cooler
                                                                                                       BEV
                                                                                                                                                                                                                                                                    Muffler                Throttle       SoV
                                                                                                                                                            City                                                     Hydrogen storage
                                                                                                                                                                                                                     and supply module                                                            Drain valve
                                                                                                                                                                                                                                                                       Purge valve
                                                                                                                                                                                                                                                                              Dosage
                                                                                                    Light Duty                         Heavy Duty                                                                                                TPRD                         valve              Water
                                                                                                                                                                                                                                                                                                 separator
                                                                                                                                                                                                                         H2-Tank
                                                                                                                                                                                                                                                   Pressure                     Jet pump
                                                                                                                                                                                                                                                    reducer                                                         CVM
     	Use cases for battery electric vehicles (BEV), fuel cell plug-in hybrid electric vehicles (FC-PHEV)                                                                                                                                                                   H2 recirculation
        and fuel cell hybrid electric vehicles (FC-HEV)                                                                                                                                                                                                                       module

                                                                                                                                                                                                                      TPRD	Thermally activated pressure relief device
                                                                                                                                                                                                                      CVM	Cell voltage measurement                                                           Hydrogen path
                                                                                                                                                                                                                      FCCU	Fuel cell control unit                                                            Air path
     annual mileage and occasional trips > 400 km, fuel cell electric               as feedstock, their costs are a linear function of the hydrogen                                                                   SoV Shut-off valve                                                                      Coolant path
     powertrains should be favored. Further-more, in zero emission                  costs. Currently, only hydrogen produced via steam reforming
     zones, especially in cold regions, a stringent environmental policy,           can compete with the low costs of conventional diesel fuel.
                                                                                                                                                                                                                       Simplified system layout of a fuel cell system concept
     as well as a hydrogen price < 4 €/kgH2 can boost the implemen-
     tation of fuel cell systems for heavy duty applications. The fuel              To further reduce the TCO of fuel cell electric vehicles, the devel-
     prices have a large impact on the operational costs. Especially                opment and production costs of fuel cell systems also need to
     for hydrogen, the future cost and price remains uncertain due to               be taken into consideration. Due to the high required lifetime of                  Since the power demand varies with the application and use                  different phases starting with the requirements specification, and
     the high dependence on the production process, energy source                   fuel cell systems for heavy duty applications, improving reliability               case, the fuel cell stacks and their BoP components need to be              the concept until the first tests and the final system validation.
     and taxation. In Figure 2, the hydrogen costs depending on the                 and durability is of utmost importance to avoid the premature                      scaled. To reach cost efficiency for fuel cell electric vehicles in the     At first, the FCEV is decomposed into its different subsystems,
     primary energy source and production process, as well as the                   replacement of fuel cell stacks and auxiliary components, as                       low quantity commercial vehicle segment, synergies with fuel                such as the hybrid system. Then it can be further decomposed
     costs of petroleum based diesel fuel and several promising                     well as minimize unscheduled maintenance and downtimes.                            cell systems for passenger car                                                                                 into the traction battery and the
     E-fuels are shown. Currently, most of the hydrogen is produced                                                                                                    applications need to be utilized.                                                                              fuel cell system, fuel cell stack
     via steam reforming (fossil H2) with costs of approximately
     0.6 to 2.9 €/kgH2. Aiming to establish green hydrogen, produced                Scaling of fuel cell systems
                                                                                                                                                                       A modular approach is desired
                                                                                                                                                                       to avoid the new design of sev-
                                                                                                                                                                                                                   HE INTEGRATION OF
                                                                                                                                                                                                                  T                                                                   and BoP components. These
                                                                                                                                                                                                                                                                                      subsystems can be further di-
     via electrolysis, leads to costs of approximately 4.5 to 7.3 €/                and synergy effects                                                                eral BoP components or even                SIMULATED COMPONENTS                                                vided into their individual com-
                              kgH2, if wind is used as renewable ener-
                                   gy source. Using photovoltaics as a
                                                                                    Fuel cell systems consist of several components which ensure
                                                                                    that the fuel cell stack is operated as optimally as possible. These
                                                                                                                                                                       the whole system. On the other
                                                                                                                                                                       hand, production costs need to
                                                                                                                                                                                                                  REDUCES DEVELOPMENT                                                 ponents, which are not shown
                                                                                                                                                                                                                                                                                      in Figure 5 for the sake of clarity.
                                      renewable energy source, leads to             so-called ‘Balance of Plant Components’ (BoP) can be assigned                      be considered, which are higher            COSTS AND ACCELERATES                                               For all the subsystems and their
                                       costs of approximately 7.3 to 10             to the air path, fuel path, coolant path and high voltage system.                  for the modular approach than              SYSTEM DEVELOPMENT                                                  components, the requirement
                                        €/kgH2. Since the production of             An exemplary layout of a fuel cell system is shown in Figure 3.                    for a scaled fuel cell system. By                                                                              specification needs to be for-
                                        most E-fuels requires hydrogen                                                                                                 using scaled fuel cell systems,                                                                                mulated in close consultation
                                                                                                                                                                       it is also possible to reach higher system efficiency, since the            with the customer. This has to be conducted not only on hard-
                                                                                                                                                                       fuel cell system can be adapted optimally to the particular                 ware, but also on the software level. In this work, the focus will
                                                                                                                                                                       application. Figure 4 shows that within the commercial vehicle              be on the calibration of the fuel cell system during start-up and
                                                                    Fossil H2                H2 from Wind                H2 from PV                                    segment, these scaling methods offer a flexibility in design and            shut-down, and the system validation.
                                       Fuel cost         450                                                                               OME3-5 (Trioxan Route)      need to be investigated in detail. However, the key arguments
                                    [€-ct / Liter        400                                                                               FT-Alcohol                  for the modular approach are the high carry-over rate from
                                    Diesel equivalent]
                                                         350
                                                                                                                                           OME1 (Me Oh Route)
                                                                                                                                           Methan (200 bar)            the passenger car segment, as well as the potential to achieve              System validation for
                                                         300                                                                               Methanol                    increased reliability and durability of the fuel cell systems. By           heavy duty applications
                                                         250                                                                               DME                         using several fuel cell systems, advanced operating strategies              Especially the optimization of water management on cathode,
                                                         200                                                                               H2 (800 bar)
                                                                                                                                                                       can be developed to run the different fuel cell stacks each on a            as well as anode side, the optimal membrane humidifier size
                                                         150                                      Fossil Diesel: Incl. tax
                                                                                                  for mineral oil & sales tax                                          different constant load to reduce excessive voltage cycling and             and the active and/or passive recirculation of hydrogen on the
                                                         100
                                                                                                  Fossil Diesel: Netto                                                 mitigate degradation.                                                       anode side in combination with an improved purge and drain
                                                          50
                                                                                                                                                                                                                                                   logic are important aspects during calibration. The software
                                                           0
                                                               0    1    2      3      4      5         6       7        8      9     10                                                                                                           for the control of the entire fuel cell system (Fuel Cell Control
                                                                                      H2 Cost (€ / kg)
                                                                                                                                                                       Development of fuel cell systems                                            Unit, FCCU) needs to be calibrated so that in various operat-
                                                                                                                                                                       for heavy duty applications                                                 ing points and during dynamic operation stack and system
                                                               	Hydrogen costs depending on production process/energy source                                         The V-Model for the development process of a fuel cell electric             performance, operational stability and durability are ensured.
                                                                  and related E-fuel and diesel fuel costs                                                             vehicle (FCEV) is represented in Figure 5. It is characterized by           During calibration, the start-up and shut-down procedure of

26                                                                                                                                                                                                                                                                                                                                27
01 SUSTAINABLE DRIVE SOLUTIONS                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              Fuel Cell

        Application case                                                                                                                                                                                                                                                                                                                                                                                Efficiency / %
                                                                                                                                                                                                                                                                                                                                                                                                   70                                                                        1                                    Stack efficiency
        Power range                                 30 – 70 kW                                                  50 – 120 kW                                                                                                                                        > 200 kW
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  System efficiency
                                                                                                                                                                                                                                                                                                                                                                                                   60
                                                                                                                                                                                                                                                                                                                                                                                                                                                                             0.8                                  Stack power
        Stack platforms                                                                                               or                                                                                                                                                                                                                                                                                                                                                                                          System power
                                                                                                                                                                                                                                                                                                                                                                                                   50
        Synergies                                  Off-Highway                                                                                                                                                                                        Passenger Cars                                                                                                                                                                                                         0.6
                                                                                                                                                                                                                                                                                                                                                                                                   40
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   P / P Max.1 Stack
        Possibilities of                                                                                                                                                                                                                                                                                                                                                                           30
                                                                                                                                                                                                                                                                                                                                                                                                                                                                             0.4
        system scaling                Parallel arrangement of                            Combination of scaling and                                                                                                                          Completely scaled system
                                      independent identical systems                      multiple usage of components                                                                                                                                                                                                                                                                              20
                                                                                                                                                                                                                                                                                                                                                                                                                                                                             0.2
                                         Full redundancy                                    Partly redundancy                                                                                                                                  Optimally adapted system                                                                                                                            10
                                         Lowest development costs                         	Lowest costs (component-wise                                                                                                                       Lowest component unit costs                                                                                                                                                                                                                                	Stack and
                                                                                            decision about multiple usage
                                                                                            or customized development                                                                                                                                                                                                                                                                               0                                                                        0                               system performance
                                                                                            based on the expected quantities)                                                                                                                                                                                                                                                                        0.2                   0.4           0.6                 0.8         1

                                         Highest production costs                                                                                                                                                                               No redundancy
                                         Potentially lower efficiency                                                                                                                                                                         	Potentially highest component
                                                                                                                                                                                                                                                development costs

        Key                                  Blower representing all auxiliary components                                                                                                                                                    Stack incl. end plate
                                                                                                                                                                                                                                                                                                                                                                                                   Real-time network for the investigations of the
      	Power demand for fuel cell systems in various commercial vehicle application cases                                                                                                                                                                                                                                                                                                        advanced fuel cell electric powertrains
         and scaling methods for fuel cell systems                                                                                                                                                                                                                                                                                                                                                 The real-time communication between different component test benches as                                By
                                                                                                                                                                                                                                                                                                                                                                                                   shown in Figure 8, enables the further improvement of the fuel cell system                             Dr. Marius Walters
                                                                                                                                                                                                                                                                                                                                                                                                   and hybrid system already in early development phases. The integration of                              walters@fev.com
      the developed fuel cell system must be given special attention.                                  evenly over a bleed resistance, fuel/air fronts and reverse current                                                                                                                                                                                                                         simulated components reduces development costs and accelerates system                                  FEV Europe GmbH
      This is illustrated in Figure 6. The implementation of diagnostic                                phenomena during following start-up procedures and related                                                                                                                                                                                                                                  development. By setting up virtual powertrains, the interactions between
      functions to detect malfunctioning components and ensure                                         degradation mechanisms, especially the carbon corrosion of                                                                                                                                                                                                                                  different components, the dynamic behavior in varying driving cycles, and the                          Johannes Buchmann
      proper communication is as essential as the checks of cathode/                                   the catalyst support, can be reduced.                                                                                                                                                                                                                                                       advantages and disadvantages of different HV-topologies can be analyzed to                             buchmann@fev.com
      anode valves and leakproofness.                                                                                                                                                                                                                                                                                                                                                              improve the control strategies on vehicle and fuel cell system level. Powertrains                      FEV Consulting GmbH
                                                                                                       After the calibration and commissioning of the fuel cell system,                                                                                                                                                                                                                            with a fuel cell system power of up to 250 kW can be investigated, which are
      To prevent the condensation of excess water during the shut-                                     the performance and efficiency during normal operation is in-                                                                                                                                                                                                                               suitable not only for heavy-duty applications for road, but also for rail trans-                       Steffen Dirkes
      down procedure, after the reduction of stack power, a drying rou-                                vestigated. System efficiencies between 41 at full load and more                                                                                                                                                                                                                            port. Especially for cold start studies, a climate chamber with temperatures                           Institute for Combustion Engines,
      tine is conducted. In this way, the fuel cell system is well-prepared                            than 53 percent at part load are achieved as shown in Figure 7.                                                                                                                                                                                                                             reaching from -42 to 110 °C can be used within this framework.                                         RWTH Aachen University, Germany
      for longer downtimes even in cold environments. By inertizing
      the cathode and dissipating the residual potential of the cells

                                                                                                                                                                                                                                                                    Start-up     produce
                                                                                                                                                                                                                                                                       Start-up procedure
                                                                 De

                                                                                                                                                                                                                              1                                                                                                                     1

     Fuel Cell Stack                 BoP Components                                                1                                                                                                                                                                1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      	Functional principle of
                                                                   co

                                                                                                                                                                                                                                                                                                                                                          Average cell voltage / V
                                                                                                                                                                                                                                                     Voltage
                                                                                                                                                                                                                                                         Voltage                                           3
                                                                                                                                                                                                                                                                                                                                                                                                                                                    Real-time Network
                                                                                                       System off
                                                                      m

                                                                                                                                              0 0
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         the real-time network
                                                                                                                                                                                                                           0.8                                                                                                                      0.8
                                                                                                                                System off
       Fuel Cell System                                                                                                                                                                                                                              Current
                                                                                                                                                                                                                                                         Current
                                                                        po

                                                                                                 0.8                                                                                                                                                                0.8

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         for the fuel cell electric
                                                                          sit

                                                                                                                                                                                                                                                                                                                                                               Average cell voltage / V
                                                                                                                                                                                                                           0.6                                                                                                                      0.6
                                                                                                                                                                                                      procedure

           Hybrid System                                                                               Standby
                                                                                                                                                                                                                  l / l max

                                                                                                                                 Standby      1 1
                                                                                                                                                                                                                     max
                                                                             i
                                                                            on

                                                                                                                                                                                                                                         1               2                                                             4           5
                                                                                                                                                                                                                                                                                Average cell voltage / V

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         vehicle setup
                                                                                                 0.6                                                                                                                                                                0.6
                                                                                                                                                                                                                   I/I

                                                                                                                                                                                                                                                                                                                                                                                                                      Fuel Cell System + DC/DC                               Inverter + Electric Engine
                                                                                                                                                                                                                           0.4                                                                                                                      0.4
                                                                                           max

            Fuel Cell Electric Vehicle                                                                 Cooling system scheck
                                                                                                                       Cooling system check
                                                                                                                                              2   2
                                                                                                                                                                                                                                                                                                                                  Idle
                                                                                          I/I

                                                                                                                                                                                                                                                                                                                                   Idle
                                                                                                 0.4                                                                                                                       0.2                                      0.4                                                                             0.2
                                                                                                                                                                                      Start-up procedure

                                                                                                       Cathode check
                                                                                                                              Cathode check       3
                                                                                                                                                                                                                                                                                                                                                                                                            H2 + 02
                                                                                                                                                                           procedure Start-up

                                                                                                                                              3
                                                                                                                                                                                                                              0                                                                                                                     0

              Customer Value
                                                                                                 0.2                                                                                                                                                                0.2
                                                                                                                                                                                                                                                                                                               Time
                                                                                                                                                                                                                                                                                                                Time

                                                                                                       Anode check
                                                                                                                               Anode check
                                                                                                                                              4
                                                                                                                                                  4
                                                                                                                                                                                                                                                                   Shut-down      produce
                                                                                                                                                                                                                                                                      Shut-down procedure
                                                                                                                                                                                                                                                                                                                                                                                                               Fuel Cell                    DC/DC                                                      Electric
                                    Re ecifi

                                                                                                                                                                                                                              1                                                                                                                     1
                                                                                                   0                                                                                                                                                                0
                                                                                                                                                                                                                                                                                                                                                                                                                                                                        Inverter
                                     sp

                                                                           Abstraction
                                      qu cat

                                                                                                                             Warm up phase Time
                                                                                                                                             5
                                                                                                                                                                                                                                                                                                                                                                                                                System                       FCS
                                                                                                                                                                                                                                                                          Single cell voltage / V

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Engine
                                                           ses

                                                                                                       Warm up phase                          5
                                                                                                                                                                                                                                                                                                                                                          Average cell voltage / V

              Operating Principle
                                        ire ion

                                                                                                                                                                                                                           0.8                                                                                                                      0.8
                                                          t ca
                                           me

                                                                                                                           Normal operation       6
                                                                                                       Normal operation                       6                                                                                    6
                                                       Tes

                                                                                                                                                                                                                           0.6                                                                                                                      0.6
                                              nt

                                                                                                                                                          Shut-down procedure

                                                                                                                                                                                                                  l / l max

                                                                                                                                                                                                                                                                                                                                                                Average cell voltage / V
                                                                                                                                                        Shut-down

              Technical Solution
                                                                                                                                                                                                                     max

                                                                                                                                                                                                                                  Part
                                                                                                                                 Drying           7
                                                                                                       Drying
                                                                                                                                                                                                                                  load
                                                                                                                                                                                                                   I/I

                                                                                                                                              7
                                                                                                                                                                                                                                                                                                                                                                                                                                                    DC Bus                                                   Virtual Shaft
                                                                                                                                                                                                                           0.4                                                                                                                      0.4

                                                                                                                       Cathode inertization       8                                                                                           7                                                                            Time
                                                                                                       Cathode inertization
                                                                                                                                                                                                   1                                                                                                                                                1
                                                                                                                                              8
                                                                                                                                                                                                                                             Idle                                                                                      Voltage
              Industrialization
                                                                                                                                                                                                                           0.2                                                                                                            Voltage   0.2
                                                                                                                                                                                                                                              Idle

                                                                                                                       Emergency shut-down        9                           0.8
                                                                                                                                                                                                                                                     8                                                                                 Current
                                                                                                                                                                                                                                                                                                                                          Current
                                                                                                                                                                                                                                                                                                                                                    0.8

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    Differential +
                                                                                                                                                                                                                              0                                                                                                                     0

                                                                                                       Emergency shut-down                    9                                                                                                                                                                Time
                                                                                                                                                                                                                                                                                                                Time
                                                                                                                                                                                                                                                                                                                                                                                                                                            DC/DC
                                                                                                                                                                                                                                                                                                                                                                        Average cell voltage / V

                                                                                                                                                                                                                                                                                                                                                                                                               Traction
                                                                                                                                                                              0.6                                                                                                                                                                   0.6

                                    Deliverables                                                                                                                                                                                                                                                                                                                                                                                                                                    Transmission
                                                                                                                                                      max

                                                                                                                                                                                                                                                                                                                                                                                                               Battery                       BAT
                                                                                                                                                  I/I

                                                                                                                                                                              0.4                                                                                                                                                                   0.4

                                                                                                                                                                              0.2                                                                                                                                                                   0.2

      	V-Model of the FCEV development process                                                 	Simplified illustration of the most important operational                                                                                                                                                                                                                                                                                                                                                                           Hardware
         with its decomposition into sub-systems                                                    states (left); stack voltage and normalized stack current
                                                                                                                                                                                                   0                                                                                                                                                0
                                                                                                                                                                                                                                                                                                                                                                                                                      Traction Battery + DC/DC                                     Transmission
                                                                                                                                                                                                                                                                                      Time
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        Simulated
                                                                                                    during start-up (top right); stack voltage and normalized
                                                                                                    stack current during shutdown (bottom right); zoomed
                                                                                                    in view: minimum, maximum and selected cell voltages
                                                                                                    during cathode inertization (measured data, plotted partly
                                                                                                    schematically).

28                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    29
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