Hybrid Electric Vehicles

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Hybrid Electric Vehicles

Development Processes & Challenges

Dr. Olivier Imberdis, IAV France

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Content

• Driving forces for alternative drive trains

• Classification & Potentials of HEV

• Impact on development processes

• Outlook

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Content

• Classification & Potentials of HEV • Impact on development processes

• Outlook

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Availability of Oil

world wide oil production 1900 - 2050

Quelle: BGR 2004 accumulated oil convent. Oil Projection non conventional oil resources (oil shale, fat oil...)

1900 1925 1950 1975 2000 2025 2050 2075 2100 2125 2150 0 1 2 3 4 G t

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Estimated Vehicles Count

vehicles on the road world wide until 2050

Africa

Latin America

Middle East

India

other asian states

China

East Europe

GUS

OECD Pacifik OECD Europa

OECD Nord Amerika 0 0,5 1 1,5 2 M ill ia rd e n 2000 2010 2020 2030 2040 2050

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CO

₂

Emission Goals – Manufacturers penalties

between 5 and 25 € from 1 to 3 g/km

95 € per excess gramm over 3g/km

Manufacturer penalties

CO2 emissions with NEDC

80 100 120 140 160 180 200 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 2 0 0 9 2 0 1 0 2 0 1 1 2 0 1 2 2 0 1 3 2 0 1 4 2 0 1 5 2 0 1 6 2 0 1 7 2 0 1 8 2 0 1 9 2 0 2 0 C O 2 e m is s io n s [ g /k m ] 0 20 40 60 80 100 120 1995 2000 2005 2010 2015 2020 v e h ic le r e s p e c ti n g C O 2 e m is s io n s [ % ]

CO2 ACEA target [g/km] Gasoline [g/km] Diesel [g/km]

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Content

• Classification & Potentials of HEV

• Outlook

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Classification & Potentials

Hybrid Systems Introduction

Classification

Potentials of HEV

... According to Topology

... Gasoline and Diesel

... Fuel Efficiency

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Hybrid Systems Introduction

Classification

Potentials of HEV

... Fuel Efficiency

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Parallel Hybrid

pure mechanical power transfer

modification of operating point dependent on electric power

numerous technical designs (Mild / Full Hybrid) possible

Power Split Hybrid

power transfer both mechanical and electrical

strong modification of operating point possible

biggest fleet based on hybrid electric vehicles from Toyota

Series Hybrid

pure electrical power transfer

complete modification of engine operating point possible

application in electric vehicles as range extender

Classification based on Topology

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Parallel Hybrid

Hybrid Systems Introduction

pure mechanical power transfer

1 electric machine is sufficient

transmission needed

several technical configurations

• Mild / Full hybrid • torque addition

• single- / double-shaft

Advantages:

+ scaleable system regarding the electrical power

+ good efficiency chain

Disadvantages:

- regenerative braking depending on the technical configuration

- limited modification of ICE operating point

- limited power assist and regenerative braking by low power of the electric motor

Examples:

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Power Split Hybrid

Hybrid Systems Introduction

power transfer both mechanical and electrical

minimum 2 electric machines

eCVT function possible with planetary gear set installation

Advantages:

+ wide range of operating point adjustment

+ high regenerative braking rate

Disadvantages:

- partially unfavourable efficiency chain - by eCVT an ICE power support through

the electric motor required - High costs

Examples:

• biggest fleet based on hybrid electric vehicles from Toyota (in total 1 million hybrid vehicles sold)

• Toyota „Hybrid Synergy Drive“ (Prius) • „Lexus Hybrid Drive“ (LS 600h)

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Series Hybrid

Hybrid Systems Introduction

pure electrical power transfer

minimum 2 electric machines

no transmission

Advantages:

+ complete variable engine operating point + optimal operative strategy for fuel

efficiency and exhaust emissions possible

+ maximum regenerative braking

Disadvantages:

- efficiency chain with high losses (ICE, generator, EM)

- approx. 3x installed power needed for permanent full load

- high weight - high costs - package

Examples:

• Renault Kangoo Elect‘road (electric vehicle Kangoo Electri‘cite w/ Range Extender) • PML Flightlink Mini QED (4x 120kW

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Power Split (front) Parallel Hybrid (front) conventional Fuel efficiency 0 + + Acceleration 0 + + Comfort 0 +

++

Electric power 0 100% Approx. 300%

Costs 0 -

-Source: according to M.Lehna (AUDI)

Comparison Full Hybrid Systems

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Hybrid Systems Introduction

Classification

Potentials of HEV

... Fuel Efficiency

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Hybrid Powertrain Functionality

Hybrid Systems Introduction

S o u rc e : a c c o rd in g t o F o rd

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H

y

b

ri

d

M

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ro

H

y

b

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d

ri

d

Full regenerative braking Power assist (boost) Stall protection

Torque smoothing High speed cranking Comfort cranking

Minimal regenerative braking Electric accessory drives

Full power assist / electric drive Operating point modification

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Classification & Potentials

Hybrid Systems Introduction

Hybrid Systems

Potentials of HEV

... Fuel Efficiency

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Comfort / Safety

Potentials

Hybrid Systems Introduction

Extended Dynamics

Environment

Increase in driving dynamics through boost function

Torque Vectoring / enhanced heavy terrain drivability

Fuel efficiency, reduced CO₂emissions

Improved NVH behaviour

Zero-emission and driving in congested areas

Increase of HVAC comfort (A/C by standstill)

Reduced NVH emissions

Off-board-supply of electrical devices

Active support of vehicle stability control systems (electric braking, torque vectoring)

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Potentials

Hybrid Systems Introduction

Development and integration of new components and technologies for the automobile industry

Electric motors, batteries, power electronics, etc.

Innovative cross-linked powertrain control strategies

Further development of the conventional gasoline and diesel ICE (downsizing, selective operating points)

Energy management

On-demand control of the accessory drives through electrification

Efficiency improvement of the electric power generation for the electric loads

Realisation of 4WD without transfer gear, differential, drive shafts (e4WD)

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City traffic (congested) City traffic (flowing) Overland/ Highway

Gasoline vs. Diesel Hybrids

Hybrid Systems Introduction

Increase in fuel efficiency in comparison to conventional gasoline powertrain

Source: GM b e tt e r Diesel Hybrid Diesel conventional Mild-Hybrid

with gasoline ICE

V e h ic le s p e e d

Time Time Time

Full-Hybrid with gasoline ICE Power Split-Full-Hybrid with optimised ICE

Parallel Mild Hybrid without optimised ICE Depending on hybrid concept, ICE optimisation and driving cycle

Parallel Full-/ Mild-Hybrid with

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Content

• Driving forces for alternative drive trains • Classification & Potentials of HEV

• Outlook

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Selection of Architecture

Simplified Proceeding

IAV analysis

Architecture Topology Selection customer requirement e.g.

• power

• distance of operation • noise

• cost

• identification of possible powertrain configurations (of the shelf)

• decision matrix setup considering boundary conditions

• e.g. serial, parallel,

• identify effort of modification

• e-cvt 1-mode, two-mode, combined parts

Performance

Topology

Functionality

Analysis • % fuel saving • functions • …

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Selection of Architecture

Simplified Proceeding IAV analysis

Database

Simulation /

Velodyn

Process

• technology / supplier choice based on database

•proof of selected concept through simulation (performance targets, ... )

•iteration step if needed

•modification of chosen off the shelf system by

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Hybrid Specific Demands

Safety

Standards and

regu-lations also applicable

for Hybrid Electric

Vehicle

ISO 26262 EN 61508 R100 •High Voltage isolation monitoring active discharge

touch protection design

•Torque

securisation of all driver demands vs. actual torque

•Functional X - by wire etc

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Content

• Outlook

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Simulation benefits

• Early prediction of the dynamic behavior

• Large modeling know-how for specific fields of application

• Covers almost every domain

• Decreases the needs of physical prototypes • Shortens the overall development time

Motivation

Simulation in the development process

Source: IAV

Challenges related to Hybrid technology

• Increases the powertrain complexity

• New opportunities for powertrain architecture • Advanced control functions for energy

management and traction optimization

Objective: develop a cross-operating numerical solution to investigate the entire vehicle performance offered by complex hybrid strategies

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Continuous Use of Simulation

Simulation in the development process

Integration into the product development process

• Support of the project decision phases • Functions validation and testing

• CiL and HiL simulation • Debugging support Concept selection Requirements specifications Design specifications Realization Testing phase Prototypes

Phases of the development process

Requirements on the simulation concept

• Be fully configurable and standardized • All the components or modules

developed should be easy to combine • Clear separation between physical models and control units models

• Possibility to simulate the function of each component on its own as well as in

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Missions of the Simulation Approach

Simulation in the development process

Concept studies of E-machine, converter, battery

Reduction of losses of the mechanical components

Demand controlled auxiliaries (Thermal management, X-by-Wire)

Operating strategy

Synchronization of ICE and electric drive operation

Energy management and energy recovery

Topology studies

Engine concept

Torque investigations

Fuel consumption, Emissions

Powertrain Concept

Electrical Concept & Auxilliaries

Powertrain & Energy Management ANALYSE

DESIGN

TEST EARLY

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Modular & Flexible Simulation Strategy

Simulation in the development process

Model Based design

• Possible Cooperation work in components modelling • Modularity and potential of reuse

• High reactivity to updates

• Easy maintenance of complex systems

VeLoDyn - Vehicle Longitudinal Dynamics

Increased Complexity

Modelling of any type of powertrain

• Any powertrain architecture can be modelled (front wheel drive, 4x4, serial hybrid, parallel hybrid, …)

Variable modelling level

• Level of components details Trade off between simulation / development speed and accuracy of results

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Description of a Simulation-Based Decision Process

Simulation in the development process

Backward

Backward simulationsimulation

Customer Customer needs needs Mission profiles Mission profiles Powertrain

Powertrain designdesign

Powertrain

Powertrain first first sizingsizing

Forward

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Distributed Simulation for System Investigations

Simulation in the development process

Distributed Simulation Concept

• Linking domains of chassis and powertrain control

• Consideration of lateral dynamics in HEV powertrain development

• Use of non-local SW-licenses • Reduction of computation time by

distributed simulation

• Use of each simulation tool's native environment

• Function development for global chassis control

• Integration of electrical components into HEV powertrains

Powertrain model

• detailed Powertrain model representing hybrid architecture and contains operational strategy

• detailed vehicle chassis model

• detailed environmental description including a maneuver controller for longitudinal/lateral maneuver setup

veDYNA Vehicle model

• detailed vehicle chassis model

• detailed environmental description including a maneuver controller for longitudinal/lateral maneuver setup

veDYNA veDYNA Vehicle model Use of EXITE-ACE as co-simulation tool to connect IAV-powertrain model VeLoDyn and common handling simulation tool veDyna

Integration tool

Tool adapter for MATLAB®, Simulink®, Real-Time Workshop®; TargetLink, ASCET, Dymola, Rhapsody® in C, Rapsody® in C++, C/C++ …

Use of EXITE-ACE as co-simulation tool to connect IAV-powertrain model VeLoDyn and common handling simulation tool veDyna

Integration tool

Use of EXITE-ACE as co-simulation tool to connect IAV-powertrain model VeLoDyn and common handling simulation tool veDyna

Integration tool

Tool adapter for MATLAB®, Simulink®, Real-Time Workshop®; TargetLink, ASCET, Dymola, Rhapsody® in C, Rapsody® in C++, C/C++ …

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Content

• Outlook

• Simulation as a continuous development tool

Hybridization & impact on stability

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Content

• Outlook

• Simulation as a continuous development tool

Hybridization & impact on stability

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Powertrain Hybridization – Impact on Stability

Torque distribution with E-machine integration

1. Propulsion mode

Applying / superimposing drive torque 2. Generator mode

Applying / superimposing drag torque

3. Combined operations with at least 2 E-machines

Power transfer between axles and wheels (directly or battery buffered)

E-machine potential operating modes:

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Powertrain Hybridization – Impact on Stability

Integration of E-machines in conventional powertrains

Fundamental system characteristics:

Maintain the speed / torque coupling between axles (wheels)

The effect of the regeneration process is similar to an additional drag torque

ASR/MSR brake interventions always act on both axles

Remark:

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Fundamental system characteristics:

No mechanical coupling between axles or wheels!

Possible superimposition of wheel individual (failure-) regeneration torque

ASR/MSR brake interventions not automatically distributed on both axles

Challenges:

Safety relevant aspects related to torque distribution

Consideration of all potential failures and associated failsafe modes

Powertrain Hybridization – Impact on Stability

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Powertrain Hybridization – Impact on Stability

Potential Hybrid strategy

• Battery charging during normal driving • Basic Recuperation

(engine drag torque superposition) • Brake recuperation (system blending). • Transmission shift support (boost) • Driving with E-machine only

• 4WD-strategy and rear axle boost

Virtual AWD Battery buffered

• Safety strategy for:

– Driving with E- machine in a “fail-safe“ mode – Erroneous Torque set-point / sign

– Slip intervention (ASR/MSR) – ESC and ABS intervention

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Powertrain Hybridization – Impact on Stability

Simulation settings for a real 3D track definition

3D-Two-Lane Alpe d’Huez road profile Vehicle

parameterization

Advanced driver settings and road conditions

The representativity of the model needs to be verified through

comparison with physical data

Validation process

Vehicle Model w/ lateral dynamics consideration

Detailled modelling of chassis kinematics, driver reaction and road definition.

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Powertrain Hybridization – Impact on Stability

Validation process

Vehicle system tests & validation

Tests definition according to driving manoeuvres for qualitative and

quantitative evaluation (standards, customer specific, certification criteria)

Networking and diagnostics tests

Mechanical and parametrical calibration

Data base management w/ self-developed tools (IAV CalGuide)

Various high-end measuring systems and robotics

Trained and experienced test & calibration engineers

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Powertrain Hybridization – Impact on Stability

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Powertrain Hybridization – Impact on Stability

Simulation settings for a real 3D track definition

3D-Two-Lane Alpe d’Huez road profile

• Front and rear E-Machine scaled from longitudinal optimization

• Driver used form veDyna except gear shifting

• All hybrid functions enabled • SOC at start: 70 %

• 4WD torque split strategy:

1. As much as possible with front axle, then add rear axle 2. Permanent 4WD support SOC dependent • ASR on Vehicle parameterization Advanced driver settings and road conditions

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Powertrain Hybridization – Impact on Stability

Vehicule behavior while regenerative braking

160 seconds on the road

MSR / ESC off

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Content

• Outlook

• Simulation as a continuous development tool Hybridization & impact on stability

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Enhanced driving dynamics through Torque-Vectoring

Rear axle differential with active torque distribution

M_Rad

Understeering driving behavior without active torque distribution

Active longitudinal and lateral torque distribution

Positive effect on

• Traction

• Critical cornering speed • Self-steering response

• Handling and cornering characteristics • Agility

• Yaw damping / yaw boosting • Reducing brake intervention

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Enhanced driving dynamics through Torque-Vectoring

Rear Axle differential with active torque distribution

Open differential

Wheel-specific torque vectoring

• Existing engine/transmission configurations (MT, AMT, DCT, CVT, AT) can be carried over • Rear-axle module: supplier add-on

Integration of two electric machines in the

differential casing Control

Compact electric machines

Using a suitable storage system

• Parallel hybrid

• Improved longitudinal dynamics • Avoidance of traction interruption

Energy storage

Optional for hybrid capability

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Enhanced driving dynamics through Torque-Vectoring

Torque-Vectoring functionality µ low 1000 N 350 Nm 350 Nm i = 4 175 Nm

Moving off with µ-split

µ high

1000 N

Mechanical torque

transmission superimposed by electrical power flow when necessary

TV torque of 700 Nm for • optimizing traction

• influencing transverse dynamics independently of drive torque

350 Nm 350 Nm 350 Nm Generator mode E-machine mode 350 Nm +700 Nm 1000 N +2000 N 175 Nm +175 Nm

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Enhanced driving dynamics through Torque-Vectoring

Simulations results of lateral dynamics ISO 4138

Steady-state skid-pad driving R = 100 m (test to ISO 4138) E -m a c h in e t o rq u e l e v e ls S te e ri n g a n g le

area of optimizing control linearization gain approx. 30% lateral acceleration gain approx. 5% 2 x 350 Nm 2 x 230Nm Self-steering response impact predictable driving

behavior also on upper lateral acceleration

increase the speed of cornering

possibility to

recuperate transversal dynamics energy

possibility to realize a lane keeping system

Steer. angle w/o el. hyb. Powertrain Steer. angle w/ el. hyb. powertrain Torque, left

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Enhanced driving dynamics through Torque-Vectoring

Simulations results of lateral dynamics ISO 7401

Step steering-angle change from 0 to 50°(300°/s at 80 km/h, test to ISO 7401) E -m a c h in e t o rq u e l e v e ls Y a w r a te Time ½ steering angle Steering angle Overshoot reduced from

13% to approx. 2%

area of optimizing control

peak response time reduced by approx. 30%

Driving dynamics impact

low response time by fast actuator speed (~10 ms)

enhancement of steering response (yaw rate gain)

reduction of undesired yaw rate response (yaw rate damping)

reduction of body motion

Yaw rate w/o el. hyb. powertrain Yaw rate with el. hyb. powertrain Torque, left

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Enhanced driving dynamics through Torque-Vectoring

Simulations results of lateral dynamics FMVSS 126

Sine with dwell for 6.5xA (test to FMVSS 126) Driving stability impact impact of tracking stability vehicle stabilization without braking increase of driving dynamics by pre controlled intervention T ra n s v e rs a l d e fl e c ti o n Y a w r a te v s . m a x. . Y a w r a te Oversteer criterion Understeer criterion Steering input in e t o rq u e l e v e ls Y a w r a te S te e ri n g a n g le l Time

Yaw rate response

Yaw deflection

Yaw rate w/o el. hyb. powertrain Yaw rate w/ el. hyb. powertrain Torque, left

Torque, right

position w/o el. hyb. powertrain position with el. hyb. powertrain

w/o el. hyb. powertrain with el. hyb. powertrain

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Enhanced driving dynamics through Torque-Vectoring

Combined system layout optimisation

Installed Total Torque in Nm

Y a w r a te d e v ia ti o n (a b s .) 2 x 20kW 2 x 30kW Consumption potential from

longitudinal dynamics

Influence of additional torques for stabilizing potential Based on: FMVSS 126 at max. steering angle amplification

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Advantages of Simulation (Co-Simu)

• supports every phase of the development process • covers all levels, from component to system

• functional development support and testing • hybrid strategy verification (torque distribution, regeneration…)

• influence of HY specific functions on vehicle stability • supports safety analysis and failsafe modes definition

Simulation in the Development Process of Hybrid

Powertrains

Characteristics of the simulation concept

• Fully configurable and standardized

• Easy combination of all the components or modules developed

• Clear separation between physical models and control units models

• Possibility to simulate the function of each component on its own as well as in the overall vehicle

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Content

• Outlook

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Perspectives in HEV Technologies

Ultimate Obejctive: Zero Emission

What kind of vehicle do I need?

PEV readiness report by Roland Berger Consulting:

„…cities and other stakeholders should educate and prepare consumers to accelerate PEV transition from niche toy of the elite to mass market…”

Individual mobility perspective:

„lease / rent by actual need“

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Perspectives in HEV Technologies

Driving range distribution

Estimation of the daily average range

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Perspectives in HEV Technologies

Ultimate Obejctive: Zero Emission

Driving Range?

Energy supply network?

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Perspectives in HEV Technologies

Ultimate Obejctive: Zero Emission

Driving Range?

Energy supply network?

Costs of ownership?

How to support E-mobility expansion on the market?

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Perspectives in HEV Technologies

Status & IAV‘s vision

CO₂emission

baseline

Conventional

Luxury & SUV

Class E, F

Compact & medium vehicles

Class B, C, D

Urban vehicles

Class A 100

0

Target Pure EV - Electric Vehicles

Requires significant changes in energy storage technologies (i.e. batteries) and / or charging technology and infrastructures

Full electric * T a n k to w h e e l 100%* Micro-hybrid Mild-hybrid Full-hybrid Double drive Full-hybrid Single shaft Parallel HEV 4-10% 10-20% 20-50% 20-40%

Stop & Start

E-axle Integrated

e-machine BISG

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Perspectives in HEV Technologies

Status & IAV‘s vision

CO₂emission baseline Full electric Conventional * T a n k to w h e e l

Luxury & SUV

Class E, F

Compact & medium vehicles

Class B, C, D Compact vehicles Class B, C Urban vehicles Class A 100 0 Micro-hybrid Mild-hybrid Full-hybrid Double drive Full-hybrid Single shaft 100%* Parallel HEV Range Extender Series HEV 50-90%* Plug-in

Serial hybrid plug-in architecture: Two mission profiles :

Long range application

Urban application 4-10% 10-20% 20-50% 20-40%

Stop & Start

E-axle Integrated

e-machine BISG

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Merci

Olivier Imberdis

IAV France

70-80 Rue des Champs Philippe - 92250 La Garenne-Colombes 4 Rue Guynemer - 78280 Guyancourt