VEHICLE ELECTRIFICATION INCREASES EFFICIENCY AND CONSUMPTION SENSITIVITYHenning Lohse-Busch, Ph.D.Argonne National Laboratory

SAE INTERNATIONAL

Argonne’s Center for Transportation Research

2

Materials Research− Tribology

− Thermal Mechanical

Advanced Technology Vehicle Competition (Collegiate)

Modeling and Simulation- CFD Engine Combustion

- Vehicle PT Energy & Controls

Advanced PowertrainResearch Facility

Basic & Applied Combustion Research

- Fuels and After treatment

EV-Smart Grid Interoperability

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Advanced Powertrain Research Facility

3

Vehicle level•Energy consumption

(fuel + electricity)•Emissions•Performance•Vehicle operation and strategy

‘In-situ’ component & system testing•Component performance,

efficiency, and operationover drive cycles

•Component mapping

•Test summary results

•10Hz data of major signals

•Analysis Presentations2WD chassis dynamometer

•Up to medium duty

opened 2002, upgraded 2011

opened 2009

Supportcodes and standards development with

expertise and independent data

Assess state-of-the-art transportation technology

for the Department of Energy and Argonne

research interests

Technology Assessment Codes and Standards

Downloadable Dynamometer Database www.transportation.anl.gov/D3/

Research Oriented Test Facilities Vehicle Technology Assessment

4WD chassis dynamometer•Thermal

Chamber: 0F to 95F

• Solar emulation

You can download all the data in this presentation and recreate the

analysis!

The APRF team enabled this presentation

SAE INTERNATIONAL

OverviewAmerican Retrospective on Automotive EfficiencyPowertrain background• Relentless Progress of Conventional Vehicle• Powertrain Electrification Observations• Electrification Complicates Efficiency CalculationsElectrification Enables Higher Vehicle EfficiencyFactors Impacting Energy Consumption• Impact of Climate Control on Electric Vehicles• Impact of Ambient Temperatures on Hybrid Electric Vehicles• Cold Start Losses on Different PowertrainsSummary Illustration

4

SAE INTERNATIONAL

OverviewAmerican Retrospective on Automotive EfficiencyPowertrain background• Relentless Progress of Conventional Vehicle• Powertrain Electrification Observations• Electrification Complicates Efficiency CalculationsElectrification Enables Higher Vehicle EfficiencyFactors Impacting Energy Consumption• Impact of Climate Control on Electric Vehicles• Impact of Ambient Temperatures on Hybrid Electric Vehicles• Cold Start Losses on Different PowertrainsSummary Illustration

5

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Vehicle Efficiency History in the United States

6

Observations:• From 1985 to 2005 fuel

economy improved minimally while the engine power almost doubled. People buying trucks over cars increases CO2 average.

• In 2005 significant fuel economy improvements occurred corresponding to fuel price volatility at the pump and increased CAFE (Corporate Average Fuel Economy)

EPA report updated annually: www.epa.gov/oms/fetrends.htm

690

640

590

540

490

440

390

340

Adju

sted

CO

2 Em

issi

ons

(g/m

i)

431

400

369

337

306

275

244

212

Adju

sted

CO

2 Em

issi

ons

(g/k

m)

Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel

Economy Trends: 1975 Through 2014

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EPA implemented the new 5 Cycle Fuel Economy Label to close the gap to real world fuel economy the consumer can expect.

EPA’s 5 Cycles Tests for Fuel Economy Label

7

HWFET @ 75 F

0 200 400 600 800 1000 1200 1400 16000

10

20

30

40

50

60

70

80

Time [s]

Spee

d [m

ph]

PhaseTrace

UDDS @ 20 F

0 200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

Time [s]

Spee

d [m

ph]

Phase x10Trace

US06 @ 75 F

0 100 200 300 400 500 6000

10

20

30

40

50

60

70

80

90

Time [s]

Spee

d [m

ph]

Phase x10Trace

0 100 200 300 400 500 6000

10

20

30

40

50

60

Time [s]

Spee

d [m

ph]

Phase x10Trace

SC03 @ 95 FFTP UDDS @ 75 F

0 200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

Time [s]

Spee

d [m

ph]

Phase x10Trace#1 Cold start

#2 Hot start

Classic cycles! Aggressive cycle! Extreme Temperatures!

Parts of these cycles compute into a

City and a Highway Fuel Economy

CAFE (only city and highway)

+850 W/m2

SAE INTERNATIONAL

OverviewAmerican Retrospective on Automotive EfficiencyPowertrain background• Relentless Progress of Conventional Vehicle• Powertrain Electrification Observations• Electrification Complicates Efficiency CalculationsElectrification Enables Higher Vehicle EfficiencyFactors Impacting Energy Consumption• Impact of Climate Control on Electric Vehicles• Impact of Ambient Temperatures on Hybrid Electric Vehicles• Cold Start Losses on Different PowertrainsSummary Illustration

8

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General technology improvement trends:• Improved aerodynamics and lighter weight• Advanced transmissions (high gear number, DCT,

aggressive locking, CVT…)• Advanced engines (VVT, GDI, turbo down sized,

cylinder deactivation, …) • Vehicle system level (start-stop, deceleration fuel cut

off, accessory load electrification)

Relentless Progress of Conventional Vehicles2004 Focus 2012 Focus

Acce

lera

tion

Bra

king

Acce

lera

tion

Bra

king

Vehicle Speed Vehicle Speed

Engine speed [rpm]

Fuel cut off during deceleration

Optimized engine loading

1000

rpm

1500

rpm

2000

rpm

Idle

2L GDI6 spd DCT

2L PFI4 spd auto

Lowered engine speed for 2012

Freq

uenc

y

Engine not fueled

9

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Engine Size, Transmission and Hybrid Efficiency

10

4 cyl. 6 cyl.HEV

6 sp

eed

CVT

6 sp

eed

6 sp

eed

8 sp

eed

Conventional

2013

Niss

an A

ltim

a

2013

Hyu

ndai

Son

ata

2011

For

d Fu

sion

2012

For

d Fu

sion

2012

Chr

ysle

r 300

2010

For

d Fu

sion-

Hybr

id

2011

Hyu

ndai

Son

ata-

Hybr

id

(UDDS cycle) (HWFET cycle)City driving Highway driving

4 cyl. 6 cyl.HEV

6 sp

eed

CVT

6 sp

eed

6 sp

eed

8 sp

eed

Conventional

2013

Niss

an A

ltim

a

2013

Hyu

ndai

Son

ata

2011

For

d Fu

sion

2012

For

d Fu

sion

2012

Chr

ysle

r 300

2010

For

d Fu

sion-

Hybr

id

2011

Hyu

ndai

Son

ata-

Hybr

id

Vehicle efficiency depends on the driving style.

City driving: transient and lower loads with idle periods impact efficiency

Highway driving: higher steady engine loads for higher average efficiency

Technology observationEngine size: smaller engine

higher average efficiencyCVT & 8 speed: enables

optimized engine loading in city driving

HEV: increased freedom to leverage engine operation and enables regenerative braking

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Conventional and Hybrid Vehicle in City Driving

2013 Sonata Conventional: 8.2 l/100km Hybrid system enables:• Engine Start-Stop • EV Operation• Engine Load

Optimization• Regenerative

braking• Accessory HV

electrification (AC, PS,…)

2011 Sonata HEV: 4.9 l/100km

11 Sonata HEV

13 Sonata 2.4L

11

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Engine Load Optimization with Hybrid Systems

12

Fuel

ene

rgy

usag

e [k

J]

2011 Sonata HEV2013 Sonata 2.4L

Engine speed [rpm]1000 1500 2000500

Engine speed [rpm]1000 1500 2000500

150

100

50

0

Fuel

Pow

er [k

W]

Idle fuel

Clustered high load

area

Engine is “ON” 32%

of time

Engine is always “ON”

Spread engine

operation

Data note: UDDS hot start @ 72F Ambient

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How Much Energy Can Be Recovered?B

raki

ng E

nerg

y [W

h]

(UDDS cycle) (HWFET cycle)City driving Highway driving

(US06 cycle)Aggressive driving

2010

Priu

s

2010

Son

ata

HEV

2011

Vol

t

2010

Priu

s

2010

Son

ata

HEV

2011

Vol

t

2010

Priu

s

2010

Son

ata

HEV

2011

Vol

t

The ability to recapture braking energy is fairly complicated and includes:

• Drive cycle• Regen ramp in• Max force and

vehicle dynamics• Limitation may

be other then system limitation

Other: Battery state of charge, Mode/gear shifting, powertrain warm-up, drivability and safety issues (cornering, low friction roads, pot holes…)

13

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Electrification Complicates Efficiency Calculations

14

2012 Focus 2L 2013 Focus BEVBattery

Motor

Fuel

Engine Bi-directional power flow

Irreversible power flow

0 200 400 600 800 1000 1200 14000

500

1000

1500

2000

Time [s]En

ergy

[Wh]

0 200 400 600 800 1000 1200 14000

500

1000

1500

2000

Time [s]

Ener

gy [W

h]

in

out

EnergyEnergyEfficiency =

Regenerative braking reverses the power flow and charges the high voltage battery (In & Out reverse)

Conventional Vehicle Electric Vehicle

SAE J2951 defines “Cycle Energy” as the integration of positive powerat the wheel over the cycle (regenerative braking = “free” energy)

SAE INTERNATIONAL

OverviewAmerican Retrospective on Automotive EfficiencyPowertrain background• Relentless Progress of Conventional Vehicle• Powertrain Electrification Observations• Electrification Complicates Efficiency CalculationsElectrification Enables Higher Vehicle EfficiencyFactors Impacting Energy Consumption• Impact of Climate Control on Electric Vehicles• Impact of Ambient Temperatures on Hybrid Electric Vehicles• Cold Start Losses on Different PowertrainsSummary Illustration

15

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Electrification Enables Higher Vehicle Efficiency

16

0

0.2

0.4

0.6

0.8

1

1.2

0.0 0.2 0.4 0.6 0.8 1.0

Vehi

cle

effic

ienc

y [%

]

Degree of Hybridization (M/(M+E))

72F

Conventional2012 Ford Focus2013 Jetta TDI2013 Chevy Cruze Diesel

Hybrid Electric

2013 Chevy Malibu Eco2013 VW Jetta HEV2013 Honda Civic HEV2010 Prius 2013 Ford Cmax HEV2014 Honda Accord HEV

Battery Electric

2012 Nissan Leaf2013 Nissan Leaf BEV2015 BMW i3 BEV2015 Chevy Spark BEV2013 Ford Focus BEVData note:

UDDS hot start

Peak ICE effPeak ICE eff + regen

SAE

J295

1 de

finiti

on

Conventional BatteryElectric(incl. charger)

Hybrid Electric Observations:• Increased electrification

provides efficiency increase in city type driving to a certain limit

• Pure electric Vehicles are not bound by ICE efficiency

SAE INTERNATIONAL

OverviewAmerican Retrospective on Automotive EfficiencyPowertrain background• Relentless Progress of Conventional Vehicle• Powertrain Electrification Observations• Electrification Complicates Efficiency CalculationsElectrification Enables Higher Vehicle EfficiencyFactors Impacting Energy Consumption• Impact of Climate Control on Electric Vehicles• Impact of Ambient Temperatures on Hybrid Electric Vehicles• Cold Start Losses on Different PowertrainsSummary Illustration

17

SAE INTERNATIONAL

Different Factors Influencing Energy Consumption

18

generation

AccLoads

wheelPowertrain

wheel

Efficiency

dtPower

PowerTempEfficiency

dtPowerEnergy ∫∫ +=

)&(

Powertrain types (CVs, HEVs, PHEVs, BEVs) influence the powertrain efficiency.

Impact of the powertrain

( ) VFtVmPower roadloadwheel ×

+

∂∂

×=

Depends on:• vehicle characteristics

(mass, aero, tires,…)• Driver: speed and

acceleration

Impact of vehicle and driving style

Impact of accessory loads

Air conditioning system, electric heater, ECU, lights,…

Observations:• Interdependence between wheel power and efficiency

• If powertrain efficiency is high and wheel energy low, the accessory loads can very become significant on energy consumption

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Higher Efficiency Powertrains Are More Sensitive

19

Conventional BatteryElectric(incl. charger)

Hybrid Electric

Conventional2012 Ford Focus2013 Jetta TDI2013 Chevy Cruze Diesel

Hybrid Electric

2013 Chevy Malibu Eco2013 VW Jetta HEV2013 Honda Civic HEV2010 Prius 2013 Ford Cmax HEV2014 Honda Accord HEV

Battery Electric

2012 Nissan Leaf BEV2013 Nissan Leaf BEV2015 BMW i3 BEV2015 Chevy Spark BEV2013 Ford Focus BEVData note:

UDDS hot start

Peak ICE effPeak ICE eff + regen

Observations:• Everything matters down to

the accessory loads in electric vehicles.

SAE

J295

1 de

finiti

on

SAE INTERNATIONAL

Electric Vehicles are efficient. It takes about 4-5 kW of electricity on average to complete a city drive cycle

Electric powertrains do not have enough waste heat to warm up the cabin in freezing temperatures

An 4-6 kW electric heater is needed to warm up the cabin

This more than doubles the energy consumption and cuts the range in half

Heater and Air Conditioning Impact on Electric Consumption

UDDS#1 (Cold Start)

20F 72F 95Fsun

20F 72F 95F

20

0 200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

Time [s]

Spee

d [m

ph]

Phase x10Trace

UDDS (City Driving)

2012 Focus BEV

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Electric Range Depends on Drive Cycle, Ambient Temperature and Climate Control Settings

21

20F ambient 95F ambient + 850W/m2

72F ambient

Ran

ge [m

i]

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2010 Toyota Prius Fuel Consumption Results for Different Climate Control Modes

22

Additional mechanical

friction energy.

Additional energy to heat up the cabin.

Permanent extra energy due to colder engine

temperature and constant powertrain friction losses.

Constant extra energy required to run the AC system.

Warm ambient temperature helps improve powertrain

efficiency.

10 Prius

0 200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

Time [s]

Spee

d [m

ph]

Phase x10Trace

UDDS (City Driving)

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Engine Operation of 2010 Prius on UDDS a Range of Ambient Temperatures

23

Observations: 20F fuel island at lower

speed load and engine usage very frequent 95F higher power level

for AC and engine usage more frequent

20F with heater 95F (850 W/m2) with AC72F

Hot s

tart

UDD

S

Hot s

tart

UDD

S

Hot s

tart

UDD

S 10 Prius

0 200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

Time [s]

Spee

d [m

ph]

Phase x10Trace

UDDS (City Driving)

Cold

star

t UDD

S

Cold

star

t UDD

S

Cold

star

t UDD

S

Fuel

ene

rgy

usag

e [k

J]

EO = Engine On time in [%]Histogram is frequency

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Cold Start Penalty at Different Temperatures

24

20F: Highest cold start penalty– Penalty is due to high

powertrain losses with high friction for all vehicles

– The losses during a cold start are higher for a powertrain using an engine

72F: – Baseline 95F:

– PEVs show higher cold start penalties at 95F which may be due to cabin temperature pull down and higher baseline powertrain efficiencies

Energy consumption increase between cold start and hot start UDDS

SAE INTERNATIONAL

OverviewAmerican Retrospective on Automotive EfficiencyPowertrain background• Relentless Progress of Conventional Vehicle• Powertrain Electrification Observations• Electrification Complicates Efficiency CalculationsElectrification Enables Higher Vehicle EfficiencyFactors Impacting Energy Consumption• Impact of Climate Control on Electric Vehicles• Impact of Ambient Temperatures on Hybrid Electric Vehicles• Cold Start Losses on Different PowertrainsSummary Illustration

25

SAE INTERNATIONAL

Using the Heater in an Electric Car may Double the Energy Consumption in City Type Driving

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

UDDS(City driving)

Hea

ter

AC

20F 95F72F

HWFET(Highway driving)

US06(Aggressive driving)

2012 Nissan Leaf

Electric Vehicle+91%

+20%

Test Notes: • Cold start vehicle soaked at target

temperature for at least 12hr. Powertrain is hot in the other tests.

• Climate control setting to 72F automatic.

• 95F include 850 W/m2 of radiant energy.

26

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Driving at Higher Speeds and Aggressively will Increase the Energy Consumption in an Electric Car

UDDS(City driving)

72F

HWFET(Highway driving)

US06(Aggressive driving)

72F 72F

2012 Nissan Leaf

Electric Vehicle+19%

+72%

27

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

SAE INTERNATIONAL

Generally Increased Driving Intensity Translate to Higher Consumption Except for the Conventional due to Low Efficiency in the City

28

72F 72F 72F

+19%+72%

+4%

+5%

-32% +60%

UDDS(City driving)

HWFET(Highway driving)

US06(Aggressive driving)

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

2010 Toyota Prius

Full Hybrid

2012 Nissan Leaf

Electric Vehicle

Conventional

2012 Ford Focus

SAE INTERNATIONAL

Cold Start Energy Consumption is Larger than Hot Start Energy Consumption

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

UDDS(City driving)

Hea

ter

AC

20F 95F72F

HWFET(Highway driving)

US06(Aggressive driving)

2012 Nissan Leaf

Electric Vehicle+11%

+7% +12%

29

SAE INTERNATIONAL

Largest Energy Consumption Increase for an EV Occurs at 20F and for a Conventional at 95F

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

UDDS(City driving)

Hea

ter

AC

20F 95F72F

HWFET(Highway driving)

US06(Aggressive driving)

2010 Toyota Prius

Full Hybrid

2012 Nissan Leaf

Electric Vehicle

Conventional

2012 Ford Focus

+91%

+20%

+65% +56%

+7%

+27%

Note:• At 20F, the EV has to use an electric heater to heat the cabin and the conventional can use the engine heat. • At 95F the conventional uses the mechanical compressor belted to the engine which is less efficient than the high voltage compressor in the EV. • The powertrain operation change for hybrids at 20F and 95F compared to 72F.

30

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A Conventional Vehicle has the Largest Absolute Energy Consumption Penalty on a Cold Start

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

UDDS(City driving)

Hea

ter

AC

20F 95F72F

HWFET(Highway driving)

US06(Aggressive driving)

2012 Nissan Leaf

Electric Vehicle

Conventional

2012 Ford Focus

+1%

+6%

+8%

+15%

+7%

+4%

+11%

+7% +12%

2010 Toyota Prius

Full Hybrid

31

SAE INTERNATIONAL

Ener

gy c

onsu

mpt

ion

[Wh/

mi]

UDDS(City driving)

HWFET(Highway driving)

US06(Aggressive driving)

Hea

ter

AC

20F 95F72F

Hea

ter

AC

20F 95F72F

Hea

ter

AC

20F 95F72F

2012 Nissan Leaf

Electric Vehicle

Conventional

2012 Ford Focus

2010 Toyota Prius

Full Hybrid

Driving Usage and Climates Affect Energy Consumption Across Different Powertrains

Test Notes: 1) Cold start vehicle soaked at target temperature for at least 12hr. Powertrain is hot in the other tests. 2) Climate control setting to 72F automatic. 3) 95F includes 850 W/m2 of radiant energy 32

VEHICLE ELECTRIFICATION INCREASES EFFICIENCY AND CONSUMPTION SENSITIVITYHenning Lohse-Busch, Ph.D.Argonne National Laboratory

www.transportation.anl.gov/D3

Work sponsored by Lee Slezak

and David Anderson from

the Vehicle Technologies

Office at the U.S. Department of

Energy