powertrain efficiency: evaluating different techniques for ... · whilst all electric vehicles use...

#LCV2019 @LCV_Event

Powertrain Efficiency: Evaluating Different

Techniques for Improving the Energy

Efficiency of the Electric PowertrainGreg Harris

Global Strategy Lead for Electrification – HORIBA MIRA

LCV2019 Event Sponsor:

© HORIBA MIRA Ltd. 2019© HORIBA MIRA Ltd. 2019

Greg Harris – Global Lead for Electrification

2

The development of energy efficient

electric vehicles

© HORIBA MIRA Ltd. 2019© HORIBA MIRA Ltd. 2019 3

HORIBA MIRA: A global-leader in engineering, research and product testing

Technology Park


4

Addressing challenges for EV adoption

▪ Global OEMs face the challenge of increasing the

range of electric and hybrid vehicles whilst reducing the

cost

▪ OEM stated range is based on regulation drive cycles

not real world drive conditions – leading to bad press

▪ Achieving that range whilst providing driver comfort is

another challenge

▪ Improvements in technology help to increase range but

come with a cost penalty and/or time to market

▪ Increasing the energy efficiency of the EV is a low cost

method to increase range and improve performance


Example: Chinese Government’s approach to push for EV efficiency:

Subsidy

NEV credit

Road right

* New policy published on March 26th 2019

Recent Policy changes:- Threshold range for subsidy for BEV

increased from 150km to 250km

- Threshold energy density for subsidy for

BEV increased from 105wh/kg to 125wh/kg


Examples of top selling Chinese BEV in 1st half

2018

6

Drive Range (NEDC Cycle)航続距離（NEDCサイクル）

Battery Energy Densityバッテリーエネルギー密度

Energy Efficiencyエネルギー効率

Both the range and efficiency are assessed in calculating the subsidy

NEV CreditNEVクレジット

This graph is base on the data each company officially published


Effect of real world conditions on EV range

7Source : https://ev-database.uk/

Tesla

Model X

Audi e-

tron

Mercede

s EQC

400

Jaguar i-

PaceKia Niro

Hyundai

Kona

Nissan

Leaf e+

VW e-

GolfBMW i3

Renault

Zoe

ZE40

Tesla

Model 3

Hyundai

Ioniq EV

Tesla

Model S

WLTP 233 259 259 292 283 279 239 143 193 186 348 174 280 miles

WLTP Efficiency 310 320 305 290 225 225 250 220 195 215 210 160 255 Wh/mile

Range @ -10C with

Heating on185 190 190 200 195 205 185 100 120 135 245 100 215 miles

Efficiency @ -10C 390 440 420 420 325 310 320 320 315 300 300 280 335 Wh/mile

Total Battery energy

kWh75 95 85 90 67.1 67.1 62 35.8 42.2 44.1 75 30.5 75 kWh

Useable Battery energy

kWh72.5 83.6 80 84.7 64 64 60 32 37.9 41 74 28 72.5 kWh

▪ EV Range can reduce between 20-40% in low temperature conditions depending on

the vehicle and the efficiency of it’s thermal system

https://ev-database.uk/


An Energy Efficient Solution

MIRA take a system approach to

optimising electric vehicles that can

increase the range by more than 20% in

real world driving conditions


Start with the Battery: Optimising the usable energy

▪ Optimising the useable energy of the

battery pack can deliver significant

benefits towards increasing AER.

▪ If battery pack sizing is optimised, this

reduces the cost, size and weight of

the battery pack and improves energy

efficiency at a system level.

Usable energy optimisation


MIRA process for battery usable energy optimisation

▪ MIRA have developed a process for optimising the battery design and BMS algorithms for

maximum usable energy:

− Define the application specific requirements

− Analyse manufacturer data for candidate cell

− Define battery configuration

− Create initial simulation models and analyse

− Characterise cells and update models

− Define optimal BMS strategy for maximising usable

energy

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Start with the Battery: Optimising the usable energy


Analysing the energy usage

▪ This graph shows the energy split for the

baseline electric vehicle (once the useable

energy from the battery pack has been

optimised)

▪ This clearly defines the areas of most

significant losses at a system level and

therefore areas of potential improvements

Usable energy optimisation

1.1%

23.9%

8.3%

3.0%

2.8%

1.4%

36.2%

20.8%

2.4%

0% 10% 20% 30% 40% 50%

Thermal LV

Cabin Heating

Battery Heating

Inverter

E-Motor Loss

Other LV Loads (Inc. DCDC)

Mechanical (Useful) Power

Aerodynamic Losses

Rolling Losses

Energy Consumption by Category (% of Total)

Baseline Vehicle Energy Split with Optimised Battery DoD▪ Simulation and modelling of the vehicle

energy systems was undertaken

▪ This highlights the main energy losses

and therefore the target areas to

maximise energy efficiency

▪ Aerodynamics and rolling losses were

not considered in this approach


Thermal management techniques for

different powertrains

▪ On electric vehicles all the energy for heating or cooling must come from the HV

battery, making it critical to optimise thermal management to minimise the loss of

range

Thermal Management

▪ In traditional IC vehicles, concepts for recovering thermal energy are well proven,

such as supplying cabin heat by recovering a small amount of heat from the engine

coolant.

▪ With hybridised vehicles, this is more difficult to achieve due to the difference in

operating temps of the electrified portion of the powertrain and the hotter combustion

side

▪ For pure electric vehicles, the temperature of the wasted heat is relatively low which

means that for some operations such as cabin heating, the waste heat may not be

sufficient


Waste heat recovery and optimised battery heating

-30°C to -15°C

Status▪ Cold powertrain

▪ Battery in power-limit

mode

▪ No waste-heat

available

Solution

▪ Use on-board heating

(PTC)

▪ Powered externally (if

plugged in)

▪ Pack insulation may

be beneficial

-15°C to -5°C

Status▪ Powertrain and

battery heating up

▪ Limited waste-heat

available

Solution

▪ Use limited waste

heat from powertrain

▪ Reduce on-board

heating (PTC)

▪ Operate in closed

loop

-5°C to +25°C

Status

▪ Powertrain and

battery at temp

▪ Sufficient waste-heat

available

Solution

▪ Use waste heat from

powertrain

▪ Operate in closed

loop

+25°C to +50°C

Status

▪ Powertrain and

battery over-temp

▪ Excess waste-heat

available

Solution

▪ On-board cooling

required

▪ Chiller or low temp

radiator


Brake energy recovery optimisation

▪ Whilst all electric vehicles use regenerative braking, the system is often not optimised.

▪ A detailed analysis of the electrical loads on the vehicle can be used to increase the capacityfor regen braking – allowing for higher regen rates then the battery alone can manage

▪ Another option to maximise the brake energy recovery is by increasing the lift-off regenerative braking.

Brake energy recovery optimisation

HV Battery

Auxiliaries

DC/DC

Converters

12V

Battery

HV components

Motor 2Motor 1


0.00

2.00

4.00

6.00

20 30 40 50 60

Mfd

d (

m/s

^2)

Brake Pedal Travel (mm)

Matching BBW performance to Original brake performance

OEM BbW (fr1.5) BbW2

15

Brake-by-wire

▪ However, high levels of lift off regen can feel unpleasant to the driver

▪ To overcome this you can implement brake-by-wire; as the friction brakes are no longer

connected to the brake pedal you can maximise regen braking

Brake-by-wire

▪ Brake pedal feeling can then be adjusted to match

the original or ideal brake performance.

▪ For example, here we have results for matching

deceleration performance on a customer vehicle

using MIRA developed BBW


Dual battery configuration to maximise regen

▪ Another concept proposed for this project, though not implemented, was a dual battery system

▪ By adding a separate 48V battery using power cells, the regen can be increased further or used when the HV battery is full

▪ This also benefits the HV battery as it reduces the load under regen, leading to reducedcooling requirements and a longer life – but cost and efficiency need to be considered

HV Battery

Auxiliaries

DC/DC

Converters

12V

Battery

48V

Battery

Motor 2Motor 1

Dual-battery configuration


▪ This graph shows the

increased range that has

been achieved through each

of the optimisation activities0.0%

7.4%

8.3%

10.1%

17.7%

21.3%

0% 5% 10% 15% 20% 25%

Baseline Implementation

Waste Heat Recovery (WHR)

Optimised ThermalControl Strategy

ImprovedTorque Management

Liftoff Regeneration

Brake-by-Wire

Range Improvements due to Vehicle Optimisation in Cold Conditions (WLTP, -17°C ambient)

17

Range improvements in -17℃ WLTP simulation

▪ In total, these improvements

have led to a total increase of

21.3% in vehicle AER in low

temperature conditions


Range improvements in 0°C WLTP drive cycle

0.0%

2.8%

6.5%

7.7%

15.8%

21.1%

0% 5% 10% 15% 20% 25%

Baseline Implementation

Waste Heat Recovery (WHR)

Optimised ThermalControl Strategy

ImprovedTorque Management

Liftoff Regeneration

Brake-by-Wire

Range Improvements due to Vehicle Optimisation in Cold Conditions (WLTP, 0°C ambient)

▪ With an optimised thermal

strategy, active heating can be

completely withdrawn, with waste

heat recovery only being used.


Summary

▪ The incremental improvements shown through this work highlight the benefits that can be

gained from a detailed simulation and analysis of the systems involved

▪ Range improvements of more than 20% were achieved in all simulation conditions.

▪ Importantly the increased range has been achieved without implementing new components

except in the case of brake-by-wire


HORIBA MIRA Ltd.

Watling Street,

Nuneaton, Warwickshire,

CV10 0TU, UK

T: +44 (0)24 7635 5000

F: +44 (0)24 7635 8000

www.horiba-mira.com

Firstname SecondnameQualifications / Affiliations

Job Title

Direct T: +44 (0)24 7635 5xxx

M: +44 (0)7xxx xxxxxx

E: firstname.secondname@horiba-

mira.com

Contact Details

20

HORIBA MIRA Ltd.

Watling Street,

Nuneaton, Warwickshire,

CV10 0TU, UK

www.horiba-mira.com

Greg HarrisBEng

Global Electrification Services

Leader

Direct T: +44 (0)24 7635 8156

E:[email protected]

General Enquiries

+44 (0)24 7635 5000

www.horiba-mira.com/enquiries

#LCV2019 @LCV_Event

Development and Test of MAGSPLIT

Dedicated Hybrid Transmission (DHT) for

Vehicles Cross-Platform ApplicationGboyega Oshin

Project Manager – Magnomatics

LCV2019 Event Sponsor:

®

COMMERCIALLY CONFIDENTIAL

®

23Confidential

DEVELOPMENT AND TEST OF MAGSPLIT

DEDICATED HYBRID TRANSMISSION (DHT) FOR

CROSS-PLATFORM APPLICATION

Gboyega Oshin, Stuart Calverley, Jeff Birchall

Magnomatics Ltd, UK

®

24Confidential

John Boyega

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25Confidential

MAGSPLIT Dedicated Hybrid Transmission Unit

MAGSPLIT - Combining engine and electrical power to provide highly efficient powertrain

• Dedicated hybrid transmission for passenger cars, buses and trucks

• Low cost, high efficiency transmission

• Simple, proven and flexible

Innovate UK sponsored project – Magnomatics Limited, Romax Technology, Changan UK, CMCL

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26Confidential

Simple Concept

• One input shaft and one output shaft, with electronic ratio control

• Magnetic interaction of the input rotor, output rotor and the stator changes speed ratio of

input/output

Input rotor

Output rotor

Electronic ratio control

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27Confidential

Typical Powersplit Architecture

• Magsplit replaces planetary gear and a motor/generator in a typical powersplit

• There is still a need to add electrical power boost into the drivetrain using a second electrical motor

®

28Confidential

Cross-Platform Application

• Machines sized to meet requirements for performance (Vmax, 0-50 kph and 0-100 kph) and

gradeability for both HEV and EV modes

• Transmission sized for two vehicles: C/D segment passenger and Sports Utility Vehicle platforms

• Engine and transmission assessed for sport, mid-range and entry level, PHEV and HEV variants

EADO

CS75

√ √ √

√√ √

√ with ERAD

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29Confidential

Concept Evaluation – Coaxial vs Parallel Layout

Coaxial:

• Simpler machine with fewer parts

• Larger traction motor diameter

• Packaging more challenging

Parallel axis:

• Separate gear stage allows

for smaller and faster traction

motor

• Easier to package

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30Confidential

Concept Selection additional considerations

• Packaging

• Fuel consumption

• Durability

• Complexity

• Cost

Parallel axis with 1-speed offered the best trade-off

4

4.5

5

5.5

6

6.5

7

7.5

NEDC WLTP Artemis

Co

rrect

ed

fu

el

con

sum

pti

on

(litr

es/

100

km

)

coaxial 1-speed

coaxial 2-speed

parallel 1-speed

Fuel Consumption

®

31Confidential

Detail Design - Analysis

Magnet rotor structuralTransmission modal analysis

Drivetrain structural Pole Piece rotor structural

®

32Confidential

Detail Design - Analysis

Mesh analysis of oil flow network

Coolant flow CFD

®

33Confidential

Brass Board Testing and Controller Development

Engine

Magsplit Traction

motor

Torque

transducer

• Magsplit DHT system separated into main

components for brass board testing

• Torque transducer between system components

and current shunts connected to electric machine

informs the power flow between components

• SIL, HIL and brass board testing used for

controller development

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34Confidential

Transmission build

Stators and sleeves in caseGeartrain Dry Build

MAGSPLIT Input and

output rotor assembly

®

35Confidential

Sub-system Testing – Gearbox

Lubrication system testing

Gearbox drag loss testing

®

36Confidential

Sub-system Testing – Traction Motor

• Back-to-back testing allows full range

testing of traction motors (14,500 rpm and

225 Nm)

• Thermal mapping; heat soak test

• Oil distribution and coolant flow rate

• Machine loss map at two temperatures

TM rotor TM in case for sub-system

testing

• Very capable EV mode – high power

density and high efficiency

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37Confidential

Testing Results

• Factory Acceptance Tests

• Loss measurements

• Thermal Performance

80oC225 Nm

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38Confidential

Transmission Assembly

®

39Confidential

Transmission Cost and Fuel Economy Walk

Full BOM costed by FEV (Europe)

High volume manufacture at European labour and material rates

“Equivalent” DCT costed using the same assumptions on quantities, labour, etc

MAGSPLIT DHT cost 20% lower than equivalent hybrid DCT

DCT Magsplit

20%

powertrain efficiency: evaluating different techniques for ... · whilst all electric vehicles use...

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