Hybrid Electric Vehicles

Hybrid Electric Vehicles Development Processes & Challenges Dr. Olivier Imberdis, IAV France 12 th SIA CNAM Conferences Serie, March 8 th 2011 Excellence in Automotive R&D

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Outlook 2

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Outlook 3

Availability of Oil world wide oil production 1900-2050 Gt Projection 4 3 non conventional oil resources (oil shale, fat oil...) 2 1 accumulated oil 0 1900 1925 1950 1975 2000 2025 2050 2075 2100 2125 2150 convent. Oil Quelle: BGR 2004 4

Estimated Vehicles Count vehicles on the road world wide until 2050 Milliarden 2 1,5 1 0,5 0 2000 2010 2020 2030 2040 2050 Africa Latin America Middle East India other asian states China East Europe GUS OECD Pacifik OECD Europa OECD Nord Amerika source: VDA/WBCSD 5

CO 2 Emission Goals Manufacturers penalties CO2 emissions with NEDC CO2 emissions [g/km] 1995 2000 2005 2010 2015 2020 200 120 180 160 140 120 100 80 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 100 80 60 40 20 0 vehicle respecting CO2 emissions [%] CO2 ACEA target [g/km] Gasoline [g/km] Diesel [g/km] Manufacturer penalties over 3g/km from 1 to 3 g/km 95 per excess gramm between 5 and 25 source: ACEA 6

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Outlook 7

Classification & Potentials Hybrid Systems Introduction Classification... According to Topology... According to Powertrain Functionality Potentials of HEV... Fuel Efficiency... Gasoline and Diesel 8

Classification & Potentials Hybrid Systems Introduction Classification... According to Topology... According to Powertrain Functionality Potentials of HEV... Fuel Efficiency... Gasoline and Diesel 9

Classification based on Topology Hybrid Systems Introduction 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 10

Parallel Hybrid Hybrid Systems Introduction Advantages: pure mechanical power transfer 1 electric machine is sufficient transmission needed several technical configurations Mild / Full hybrid torque addition single- / double-shaft + 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: Honda Civic Hybrid VW Touareg Hybrid 11

Power Split Hybrid Hybrid Systems Introduction Advantages: power transfer both mechanical and electrical minimum 2 electric machines ecvt function possible with planetary gear set installation + 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) 12

Series Hybrid Hybrid Systems Introduction Advantages: pure electrical power transfer minimum 2 electric machines no transmission + 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 wheelhub motors) In application by ships (Pod-engine) 13

Comparison Full Hybrid Systems Hybrid Systems Introduction conventional Parallel Hybrid (front) Power Split (front) Source: according to M.Lehna (AUDI) Fuel efficiency 0 + + Acceleration 0 + + Comfort 0 + ++ Electric power 0 100% Approx. 300% Costs 0 - - - 14

Classification & Potentials Hybrid Systems Introduction Classification... According to Topology... According to Powertrain Functionality Potentials of HEV... Fuel Efficiency... Gasoline and Diesel 15

Hybrid Powertrain Functionality Hybrid Systems Introduction Electric accessory drives Minimal regenerative braking Comfort cranking Micro Hybrid High speed cranking Torque smoothing Stall protection Power assist (boost) Operating point modification Full regenerative braking Full power assist / electric drive Mild Hybrid Full Hybrid Source: according to Ford 16

Classification & Potentials Hybrid Systems Introduction Hybrid Systems... According to Topology... According to Powertrain Functionality Potentials of HEV... Fuel Efficiency... Gasoline and Diesel 17

Potentials Hybrid Systems Introduction Extended Dynamics Increase in driving dynamics through boost function Torque Vectoring / enhanced heavy terrain drivability Comfort / Safety 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) Environment Fuel efficiency, reduced CO 2 emissions Improved NVH behaviour Zero-emission and driving in congested areas 18

Potentials Hybrid Systems Introduction Technology / Innovation 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) 19

Gasoline vs. Diesel Hybrids Hybrid Systems Introduction Increase in fuel efficiency in comparison to conventional gasoline powertrain Source: GM better Mild-Hybrid with gasoline ICE Diesel Hybrid Diesel conventional Full-Hybrid with gasoline ICE Power Split- Full-Hybrid with optimised ICE Parallel Full-/ Mild- Hybrid with optimised ICE Depending on hybrid concept, ICE optimisation and driving cycle Vehicle speed City traffic (congested) City traffic (flowing) Overland/ Highway Time Time Time Parallel Mild Hybrid without optimised ICE 20

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Outlook 21

Selection of Architecture Simplified Proceeding Performance customer requirementiav e.g. analysis power % fuel saving distance of operation functions noise cost Analysis Topology identification of possible powertrain configurations (of the shelf) decision matrix setup considering boundary conditions Architecture Topology Selection Functionality e.g. serial, parallel, identify effort of modification e-cvt 1-mode, two-mode, combined parts 22

Selection of Architecture Simplified Proceeding IAV analysis Database technology / supplier choice based on database Simulation / Velodyn proof of selected concept through simulation (performance targets,... ) Process iteration step if needed modification of chosen off the shelf system by combining certain solutions, e.g. asynchron instead of synchron e-motor etc... 23

Hybrid Specific Demands Safety Standards and regulations also applicable for Hybrid Electric Vehicle High Voltage isolation monitoring active discharge touch protection design ISO 26262 EN 61508 Torque securisation of all driver demands vs. actual torque R100 Functional X - by wire etc auto startup for battery charge 24

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Outlook 25

Motivation Simulation in the development process Challenges related to Hybrid technology Increases the powertrain complexity New opportunities for powertrain architecture Advanced control functions for energy management and traction optimization 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 Source: IAV Shortens the overall development time Objective: develop a cross-operating numerical solution to investigate the entire vehicle performance offered by complex hybrid strategies 26

Continuous Use of Simulation Simulation in the development process Integration into the product development process Support of the project decision phases Concept selection Phases of the development process Requirements specifications Design specifications Realization Testing phase Prototypes Functions validation and testing CiL and HiL simulation Debugging support 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 the overall vehicle 27

Missions of the Simulation Approach Simulation in the development process Powertrain Concept ANALYSE Topology studies Engine concept Torque investigations Fuel consumption, Emissions DESIGN TEST EARLY OPTIMISE Electrical Concept & Auxilliaries Concept studies of E-machine, converter, battery Reduction of losses of the mechanical components Demand controlled auxiliaries (Thermal management, X-by-Wire) Powertrain & Energy Management Operating strategy Synchronization of ICE and electric drive operation Energy management and energy recovery 28

Modular & Flexible Simulation Strategy Simulation in the development process VeLoDyn - Vehicle Longitudinal Dynamics Model Based design Possible Cooperation work in components modelling Modularity and potential of reuse High reactivity to updates Easy maintenance of complex systems 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 Direct hardware integration Direct C compilation possible (i.e. for HiL tests) 29

Description of a Simulation-Based Decision Process Simulation in the development process Customer needs Mission profiles Backward simulation Powertrain design Forward simulation Powertrain first sizing 30

Distributed Simulation for System Investigations Simulation in the development process Use of EXITE-ACE as co-simulation tool to connect IAV-powertrain model VeLoDyn and common handling simulation tool vedyna Powertrain model detailed Powertrain model representing hybrid architecture and contains operational strategy Integration tool Tool adapter for MATLAB, Simulink, Real-Time Workshop ; TargetLink, ASCET, Dymola, Rhapsody in C, Rapsody in C++, C/C++ Vehicle model vedyna detailed vehicle chassis model detailed environmental description including a maneuver controller for longitudinal/lateral maneuver setup 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 Functional validation 31

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Hybridization & impact on stability Enhanced driving dynamics Outlook 32

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Hybridization & impact on stability Enhanced driving dynamics Outlook 33

Powertrain Hybridization Impact on Stability Torque distribution with E-machine integration E-machine potential operating modes: 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) A non-adapted torque distribution can lead to a clear vehicle instability 34

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: AWD stability condition: traction tendency 35

Powertrain Hybridization Impact on Stability Integration on individual axles - Virtual AWD 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 36

Powertrain Hybridization Impact on Stability Potential Hybrid strategy Battery charging during normal driving Basic Recuperation (engine drag torque superposition) Virtual AWD Battery buffered Brake recuperation (system blending). Transmission shift support (boost) Driving with E-machine only 4WD-strategy and rear axle boost 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 Toyota Prius battery pack 37

Powertrain Hybridization Impact on Stability Simulation settings for a real 3D track definition Vehicle Model w/ lateral dynamics consideration Vehicle parameterization Advanced driver settings and road conditions The representativity of the model needs to be verified through comparison with physical data Validation process 3D-Two-Lane Alpe d Huez road profile Detailled modelling of chassis kinematics, driver reaction and road definition. 38

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/ selfdeveloped tools (IAV CalGuide) Various high-end measuring systems and robotics Trained and experienced test & calibration engineers 39

Powertrain Hybridization Impact on Stability Validation process vehicle instrumentation 40

Powertrain Hybridization Impact on Stability Simulation settings for a real 3D track definition Front and rear E-Machine scaled from longitudinal optimization Vehicle parameterization Advanced driver settings and road conditions 3D-Two-Lane Alpe d Huez road profile Driver used form vedyna except gear shifting All hybrid functions enabled SOC at start: 70 % 4WD torque split strategy: ASR on 1. As much as possible with front axle, then add rear axle 2. Permanent 4WD support SOC dependent MSR on/off 41

Powertrain Hybridization Impact on Stability Vehicule behavior while regenerative braking 160 seconds on the road MSR / ESC off Up-hill drive with maximum recuperation torque at rear axle 42

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Hybridization & impact on stability Enhanced driving dynamics Outlook 43

Enhanced driving dynamics through Torque-Vectoring Rear axle differential with active torque distribution M Rad Understeering driving behavior without active torque distribution Positive effect on Active longitudinal and lateral torque distribution Traction Critical cornering speed Self-steering response Handling and cornering characteristics Agility Yaw damping / yaw boosting Reducing brake intervention 44

Enhanced driving dynamics through Torque-Vectoring Rear Axle differential with active torque distribution Integration of two electric machines in the differential casing Control Open differential Energy storage Compact electric machines Optional for hybrid capability Wheel-specific torque vectoring Existing engine/transmission configurations (MT, AMT, DCT, CVT, AT) can be carried over Rear-axle module: supplier add-on Using a suitable storage system Parallel hybrid Improved longitudinal dynamics Avoidance of traction interruption Utilization of wheel-specific coefficient of friction 45

Enhanced driving dynamics through Torque-Vectoring Torque-Vectoring functionality Moving off with µ-split Generator mode E-machine mode 350 Nm 350 Nm 350 Nm 350 Nm i = 4 350 Nm +700 Nm 1000 N 1000 N +2000 N µ low Mechanical torque transmission superimposed by electrical power flow when necessary 175 Nm +175 Nm TV torque of 700 Nm for optimizing traction influencing transverse dynamics independently of drive torque µ high 46

Enhanced driving dynamics through Torque-Vectoring Simulations results of lateral dynamics ISO 4138 Steer. angle w/o el. hyb. Powertrain Steer. angle w/ el. hyb. powertrain Torque, left Torque, right lateral acceleration gain approx. 5% Steady-state skid-pad driving R = 100 m (test to ISO 4138) Self-steering response impact E-machine torque levels Steering angle linearization gain approx. 30% area of optimizing control 2 x 230Nm 2 x 350 Nm 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 Lateral acceleration 47

Enhanced driving dynamics through Torque-Vectoring Simulations results of lateral dynamics ISO 7401 E-machine torque levels Yaw rate peak response time reduced by approx. 30% Overshoot reduced from 13% to approx. 2% ½ steering angle area of optimizing control Steering angle Yaw rate w/o el. hyb. powertrain Yaw rate with el. hyb. powertrain Torque, left Torque, right Step steering-angle change from 0 to 50 (300 /s at 80 km/h, test to ISO 7401) 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 Time 48

Enhanced driving dynamics through Torque-Vectoring Simulations results of lateral dynamics FMVSS 126 Steering input Understeer criterion position w/o el. hyb. powertrain Sine with dwell for 6.5xA E-machine torque levels Yaw rate Steering anglel Time Yaw rate response Yaw deflection Yaw rate w/o el. hyb. powertrain Yaw rate w/ el. hyb. powertrain Torque, left Torque, right Transversal deflection Yaw rate vs. max..yaw rate Oversteer criterion position with el. hyb. powertrain w/o el. hyb. powertrain with el. hyb. powertrain (test to FMVSS 126) Driving stability impact impact of tracking stability vehicle stabilization without braking increase of driving dynamics by pre controlled intervention Time Time 49

Enhanced driving dynamics through Torque-Vectoring Combined system layout optimisation Influence of additional torques for stabilizing potential Based on: FMVSS 126 at max. steering angle amplification Yaw rate deviation (abs.) Consumption potential from longitudinal dynamics 2 x 20kW 2 x 30kW Installed Total Torque in Nm Simulated Vehicle category: SUV, (not fully verified) 50

Simulation in the Development Process of Hybrid Powertrains 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 Characteristics of the simulation concept Pixelio 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 Re-use of former models for spin-off projects 51

Content Driving forces for alternative drive trains Classification & Potentials of HEV Impact on development processes Simulation as a continuous development tool Outlook 52

Perspectives in HEV Technologies Ultimate Obejctive: Zero Emission Driving Range? 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 53

Perspectives in HEV Technologies Driving range distribution Estimation of the daily average range (source MTZ 10/2009 volume 70): 54

Perspectives in HEV Technologies Ultimate Obejctive: Zero Emission Driving Range? Energy supply network? Home-plug (AC) Fast charge (DC) Inductive Energy 55

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? By keeping advantages of E-traction and to get rid of inconvenient. 56

Perspectives in HEV Technologies Status & IAV s vision CO 2 emission Compact & medium vehicles Luxury & SUV Urban vehicles 100 baseline Stop & Start 4-10% Class B, C, D 10-20% 20-40% Class E, F 20-50% Class A 0 Conventional Microhybrid BISG Mild-hybrid Integrated e-machine Full-hybrid Single shaft E-axle Full-hybrid Double drive? 100%* Full electric * Tank to wheel Parallel HEV Target Pure EV - Electric Vehicles Requires significant changes in energy storage technologies (i.e. batteries) and / or charging technology and infrastructures Need an affordable alternative to compensate the actual technology gap, satisfy the customers needs and environment policies 57

Perspectives in HEV Technologies Status & IAV s vision CO 2 emission 100 baseline Stop & Start 4-10% Compact & medium vehicles Class B, C, D 10-20% 20-40% Luxury & SUV Class E, F 20-50% Compact vehicles Class B, C Urban vehicles Class A BISG 50-90%* 0 Conventional Microhybrid Mild-hybrid Integrated e-machine Full-hybrid Single shaft E-axle Full-hybrid Double drive Plug-in Range Extender 100%* Full electric * Tank to wheel Parallel HEV Series HEV Serial hybrid plug-in architecture: Two mission profiles : Long range application Urban application 58

Merci Olivier Imberdis IAV France 70-80 Rue des Champs Philippe - 92250 La Garenne-Colombes 4 Rue Guynemer - 78280 Guyancourt olivier.imberdis@iav.de Excellence in Automotive R&D