Cooling System Architecture Design for FCS Hybrid Electric Vehicle

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Cooling System Architecture Design for FCS Hybrid Electric Vehicle

Sungjin Park, Dohoy Jung, Zoran Filipi, and Dennis Assanis

The University of Michigan

In collaboration with Thrust Area 5

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Outline• Background

• Motivation and Challenges

• Objectives

• SHEV Configuration

• Cooling System Component Modeling

• Cooling System Architecture

• Results and Discussion

• Summary and Future Plan

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Army Ground Vehicle Propulsion Challenges

1.Cooling

2.Cooling

3.Cooling

4.Fuel Effects

5.Filtration The Army vehicle cooling point is high tractive effort to weight under desert-like operating conditions (ex. 5 ton wheeled vehicle ~0.6 while 15 ton tracked vehicle ~0.7 both at 120 F ambient)

This slide is from the keynote by Dr. Pete Schihl during the 2007 ARC annual conference

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Future Combat System (FCS)

• Series Hybrid Electric Vehicle (SHEV) is under development for the automotive platform of FCS.– Improved fuel economy

– Greater electric power requirements for advanced weapon system

– Exportable electric power

– Enhanced low speed maneuverability

– Low acoustic signature and stealth operation

– Pulse power necessary to drive weapon/mobility/communication/protective systems

– Better maintenance: non-mechanical coupling of the power generation unit with drive train architecture

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Case Study Objectives

• Develop a guideline/methodology for cooling system architecture selection for the SHEV

• Develop cooling system models for optional architectures.

• Explore and demonstrate proper architectures and strategies for thermal management of hybridized powertrain

• Optimize the cooling system and component design for performance, size and minimal parasitic loss

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Motivation and Challenges

• SHEVs need additional components– Generator, Motor, Battery, and Power bus

• SHEVs also have a dedicated cooling system for the hybrid components with different requirements

• Cooling system design for SHEV requires more strategic approach– Multiple cooling circuits due to additional components– Different operating temperature and driving modes

• Numerical approach is an efficient way for complicated HEV cooling system design and development.

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Vehicle Cooling system for Future Combat System (FCS): Challenges

• Heavy-duty operation (20 ton, 400-500 hp vehicle)

• Severe military operation under extreme ambient conditions

• Shielded cooling system for survivability

• Complicated cooling system architecture in SHEV due to the additional heat sources with various requirements

• Vehicle cooling system operation and performance varies with powertrain operation, control, and driving conditions.

Generator

Radiator3

FAN

ElectricPump3

Grille

Radiator2

CAC

Radiator1Oil Cooler

Thermostat

Pump1

By-

Pas

s

Engine

Pump2

Motor(A/B)

PowerBus

Radiator1

Radiator2

FAN

ElectricPump

Grille

ElectricPump

A/C Condenser

Conventional Cooling System

SHEV Cooling SystemComponent

Heat generation @grade load (kW)

Control Target Temp.

(oC)

Engine 190 120

Oil cooler 40 125

Charge air cooler

13 -

Motor 27 95

Generator 65 95

Power bus 5.9 70

Battery 12 45

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Objectives

• Develop an efficient cooling system architecture for the SHEV and Optimize the cooling system design using numerical approach:– Configure a SHEV model using VESIM– Model the components of the cooling system for SHEVs– Develop cooling system model integrating the

components models– Evaluate the cooling system designs and architectures– Optimize the cooling system

• SHEVs need effective cooling system design that has least impact on fuel economy and cost

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SHEV Configuration (VESIM)

Engine

Generator

Vehicle

Motor

BatteryController

PowerBus

Engine400 HP

(298 kW)

Motor2 x 200 HP (149 kW)

Generator400 HP

(298 kW)

Battery

(lead-acid)

18Ah /

120 modules

Vehicle20,000 kg

(44,090 lbs)

Maximum speed

45 mph

(72 kmph)

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Power Management of Hybrid Vehicle

Discharging mode Charging/Electric Drive mode Braking mode

• Battery is the prime power source

• When power demand exceeds battery ability, the engine is activated to supplement power demand

Power Flow

Active ConditionallyActive

Inactive

• Engine/Generator is the prime power source

• When battery SOC is lower than limit, engine supplies additional power to charge the battery

• Once the power demand is determined, engine is operated at most efficient point

• Regenerative braking is activated to absorb braking power

• When the braking power is larger than motor or battery limits, friction braking is used

SOC High Limit

SOC Low Limit

Charge Discharge Charge

SOC

Engine Speed

En

gin

e T

orq

ue

Efficiency ( engine + generator )

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SIMULINK Based Vehicle Cooling System SimulationVehicle Cooling System Simulation (VCSS)

Component Approach Implementation

Heat ExchangerThermal resistance concept 2-D

FDMFortran (S-Function)

Pump Performance data-based model Matlab/Simulink

Cooling fan Performance data-based model Fortran (S-Function)

Thermostat Modeled by three-way valve Fortran (S-Function)

Engine Map-based performance model Matlab/Simulink

Engine block Lumped thermal mass model Matlab/Simulink

Generator Lumped thermal mass model Matlab/Simulink

Power bus Lumped thermal mass model Matlab/Simulink

Motor Lumped thermal mass model Matlab/Simulink

Oil coolerHeat exchanger model (NTU

method)Matlab/Simulink

Turbocharger Map-based performance model Matlab/Simulink

Condenser Heat addition model Matlab/Simulink

Charge air coolerThermal resistance concept 2-D

FDMFortran (S-Function)

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Heat Source Components

Component Heat generation model Heat transfer model Pressure drop model

EngineMap-based performance model

Lumped thermal mass model

Experimental correlation:

Generator

Flow in smooth pipe

Laminar:

Turbulent:

Power bus

Battery is charged and motor is working

Motor is working

Motor is generating

MotorMotor: Generator:

TurbochargerMap-based performance model

N/A N/A

p

extgenwall

C

QQQ

dt

dT

int

flowwall TThAQ intint )(

)(

)(44extwallext

extwallextext

TTA

TThAQ

CVBVAp

1_ gengengcQ

4

128

d

VLp

75.175.44

1

4

3

241.0 VdLp

mc

mcmccopbgenpb

wVIVIQ

1(1_

mc

mcmcpbgenpb

wQ

1_

mcmcmcpbgenpb wQ 1_

1

1_

mcmcgenmcQ

1_ mcmcgenmcQ

),(_ engenggentc rpmfQ

),(_ engenggeneng rpmfQ

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264.1Reln79.0 DfC

46.0

1.133.0

39.0Re9.11 finfin

louv

fin

louvf H

H

T

H

HC

),(_ engenggenoc rpmfQ

minC

UANTU

))1(exp(1

))1(exp(1

rr

r

CNTUC

CNTU

)( ,,min icih TTCQ

4

128

d

VLp

75.175.44

1

4

3

241.0 VdLp

),( pumppump PNfV

radheatpassbyheatpump PPPPP

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Delivery Media Components

Component Flow rate model Heat transfer model Pressure drop model

Pump

Performance data-based model

N/A N/A

Cooling fanPerformance data-based model

N/A N/A

Thermostat

Modeled by a pair of valves

Lumped thermal mass model

),( pumppump PrpmfV

radiatorheatpassbyheatpump PPPPP

),( fanfan PrpmfV

21 radradcondensergrillfan PPPPP

rera PP

raretotal VVV

radvalveSTrapiperacircuit PPPP _/__

radra

lossra

ra

rara P

VK

V

D

Lf

22

22

valveSTrepiperecircuit PPP _/__

22

22re

lossre

re

rere

VK

V

D

Lf

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Cooling System Architecture Development

Motor(A/B)

Generator

PowerBus Rad

Engine

Rad

T/S

MP

EP

By

-Pas

s

Grille

FAN

Grille

A/C Condenser

Oil Cooler

CAC

Ambient Air

Architecture A

(1) Separate cooling circuit is added for electric components.

(2) Electric pumps are used for electric heat sources to separate the cooling circuit for electric components from engine module

(3) The radiators are arranged in the order of control target temperature of heat source which is cooled by the radiator

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Motor(A/B)

Generator

PowerBus Rad

Engine

Rad

T/S

MP

EP

By-

Pas

s

Grille

FAN

Grille

A/C Condenser

Oil Cooler

CAC

Ambient Air

Motor(A/B)

Generator

PowerBus

Engine

Rad

T/S

MP

EP

By-

Pas

s

FAN

Grille

A/C Condenser

Oil Cooler

CAC

Ambient Air

RadEP

Grille

Rad

Architecture A Architecture B

(1) Cooling circuit for electric components is further divided into two circuits based on control target temperatures.

(2) Electric pumps are used for electric heat sources to separate the cooling circuit for electric components from engine module

(3) The radiators are arranged in the order of control target temperature of heat source which is cooled by the radiator.

ComponentControl target

temp. (oC)

Engine 120

Motor / controller

95

Generator / controller

95

Charge air cooler

-

Oil cooler 125

Power bus 70

Battery 45

Control Target Temp. of Heat Sources

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(1)The heat source components are allocated into two cooling modules based on the operating groups to minimize redundant operation of the cooling fan.

(2) The condenser used for the air conditioning of the compartment is placed in the cooling module where the heat load is relatively lower.

Generator

Rad

FAN

EP

Grille

Rad

CAC

Rad

T/S

MP

By

-Pa

ss

Engine

MP

Grille

Oil Cooler

Ambient Air

Motor(A/B)

PowerBus

Rad

Rad

FAN

EP

Grille

EP

A/C Condenser

Grille

Ambient Air

Cooling Module 1 Cooling Module 2

ComponentOperation

group

Engine A

Motor / controller

B


A

Charge air cooler A

Oil cooler A

Power bus C

Battery -

Operation Group of Heat Sources

Architecture C

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cac spec

inler air v elocity

inlet air temperature

turbo charger

f(u)

sum

Ramass

thermodelP

coolant temp, K

inlet air v elocity , m/s

inlet air temp, oC

Ramass1

Tcoolout

thermodelP1

RadelP, bar

to f an

outlet air temp, K

radiator2

Ramass

thermodelP

coolant temp, K


inlet air temp, oC

Ramass1

Tcoolout

thermodelP1

RadelP, bar

to f an

outlet air temp, K

radiator 1

coolant m(kg/s)

coolant density ,kg/m3

f low coef f cac

f low coef f egn

coolant f low 1

coolant f low 2

coolant f low 3

m_sum

dp(bar)

parallel coolant circuit2

coolant m(kg/s)

coolant density ,kg/m3

coolant f low 1

coolant f low 2

coolant f low 3

m_sum

dp

parallel coolant circuit1

coolant temp1

coolant mass

oil cooler spec

by pass mass

oil cooler mass

delP

orifice

0flowrate 1flowrate 2flowrate 3

flow sum

dptemp1

heat rejection rate

pump speed

engine1

heat rejection, kW

cool mass1

coolant temp

Tcool_out

f low coef f a/b/c

engine block

pump speed

pressure rise, bar

coolant temp

coolant mass

pressure rise

cool mass, kg/s

coolant temp, K

coolant density , kg/m3

coolant pump2

T_pb

T_gen

T_mot

motor_rpm

coolant pump motor/controller

pump speed

pressure rise, bar

coolant temp

coolant mass

pressure rise

cool mass, kg/s

coolant temp, K


coolant pump 1

coolant temp1

coolant mass

delP

recirculate massradiator masscoolant temp2

Re delPthermo delP

delP1

Remass

Recooltemp

RedelP

Ramass

Racooltemp

RadelP

enginedelP

thermodelP

coolant mass

coolant temp

pressure drop2

collector5

Remass

Recooltemp

RedelP

Ramass

Racooltemp

RadelP

enginedelP

thermodelP

coolant mass

coolant temp

pressure drop2

collector3

T1

T2

m1

m2

Tsum

collector1

T1

T2

T3

m1

m2

m3

Tsum

collector0

f an speed, rpm

v ehicle speed, km/h

inlet air temp, oC

radiator3 spec

radiator2 spec

radiator1 spec

radi out air T1

inlet air v el, m/s 01



inlet air temp, oC 1

air side, fan

elec_pump_rpm

Coolant_temp

f an_rpm

V_speed

Ta

air side input1

rad_air_T

To File6

heat_gen

To File3

Terminator2

Terminator

coolant temp1

coolant mass

delP1

delP2

recirculate mass

radiator mass

coolant temp2

Re delP

thermo delP

T/S temp

delP_sum

T/S

Load input data

C_m (kg/s)

C_Tin(K)

C_m(kg/s)

C_Tout(K)

Reservoir4

C_m (kg/s)

C_Tin(K)

C_m(kg/s)

C_Tout(K)

Reservoir1

coolant f low rate (kg/s)

coolant temp in (K)

coolant temp

pb temp

dp(bar)

Power Bus


coolant temp in (K)

oil f low rate (kg/s)

oil temp in (K)

cool mass

Oil cooler dp(bar)

cool temp out

oil temp out

Oil dp(bar)

oil cooler spec

Oil cooler

pump speed

heat

press rise

Toil_in

Toil_out

oil mass

Oil circuit


coolant temp in (K)

coolant temp

mc temp

dp(bar)

Motor/controller A,B

f(u)

K2C

f(u) K->oC


coolant temp in (K)

coolant temp

gc temp

dp(bar)

Generator/controller_new

[h_cac]

From5

[h_oc]

From4

[h_eng]

From3

[h_mc]

From2

[h_pb]

From1

[h_gc]

From

0

Display6

0

Display5

0

Display4

0

Display2

0

Display1

f(u)

C2K


inlet air temp, oC

to f an

outlet air temp, K

A/C

cool_mass

coolant temp, K


inlet air temp, oC


Tcoolout

f low coef f a/b/c

outlet air temp, K

cac spec

1st charge air cooler

SIMULINK Based Vehicle Cooling System Simulation Vehicle Cooling System Simulation (VCSS)

Engine Engine BlockBlock

Radiator1Radiator1

Coolant Coolant pumppump

EngineEngine ThermostatThermostat

Radiator2Radiator2Fan & Fan &

cooling aircooling air

ParallelParallelCoolingCoolingCircuitCircuitCoolant Coolant

pumppump

Electric ComponentsElectric Components

Cooling circuit for electric components

Cooling circuit for engine module

Charge AirCharge AirCoolerCooler

ParallelParallelCoolingCoolingCircuitCircuit

Motor(A/B)

Generator

PowerBus Rad

Engine

Rad

T/S

MP

EP

By

-Pas

s

Grille

FAN

Grille

A/C Condenser

Oil Cooler

CAC

Ambient AirA/CA/C

CondenserCondenser

OilOilCoolerCooler

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Sequential SHEV-Cooling System Simulation

• Operation history of each HEV component from VESIM is fed into Cooling system Model as input.

• Better computational efficiency compared to co-simulation

Hybrid Vehicle Model Cooling System Model

Driving schedule

-200

-100

0

100

200

0

500

1000

1500

2000

2500

3000

0 100 200 300 400 500

time(sec)

0

100

200

300

400

-100

0

100

200

300

400

500

600

700

0 100 200 300 400 500

time(sec)

-1500

-1000

-500

0

500

1000

1500

-200

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500

time(sec)

-1000

-500

0

500

1000

1500

2000

0

500

1000

1500

2000

2500

3000

0 100 200 300 400 500

time(sec)

0

10

20

30

40

50

0 300 600 900 1200 1500 1800Time(sec)

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Cooling System Test Conditions

• Three driving were selected to size the components of cooling system and to evaluate cooling system design performance

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 200 400 600 800 1000

distance(m)

Road profile for off-road

Ambient Temperature : 40 oC

Maximum Speed (Governed)

Off-Road

45mi/h 30mi/h

Grade Load

7%

30mi/h

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Power Consumption of Cooling System(Grade load condition)

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Driving Schedulefor the Evaluation of Cooling System

City + Cross countryDriving Schedule

0

10

20

30

40

50

0 300 600 900 1200 1500 1800Time(sec)

-20

-10

0

10

20

30

0 300 600 900 1200 1500 1800Time(sec)

Heat Rejection Rate of Each Component over Driving Schedule

0

50

100

150

0

10

20

30

40

50

0

10

20

30

40

50

0

10

20

30

40

50

0 300 600 900 1200 1500 1800

• Realistic driving schedule is needed to evaluate the cooling system

• City + Cross country driving schedule is used

ComponentOperation

group

Engine A

Motor / controller

B


A

Charge air cooler

A

Oil cooler A

Power bus C

Battery -

Operation Group of Heat Sources

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Power Consumption and Cooling Performance during Driving Schedule

Power Consumption Electric Component Temperature

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Cooling System Power Consumptions

0

2

4

6

8

10

12

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Configuration AConfiguration BConfiguration C

8.08.6 8.3

5.9

7.8 7.7

City + Cross CountryDriving Schedule

9.1

5.8

11.6

10.2

8.5

5.7

Grade LoadCondition

Off-RoadCondition

Maximum SpeedCondition

Improvement of Power Consumptionby Cooling System Redesign

Portion of Cooling SystemPower Consumption in Engine Power

0

0.2

0.4

0.6

0.8

1

1.2

Architecture AArchitecture BArchitecture C

-12.2%

-27.8%+12.6%

-26.0%

+7.5%-24.0%

+9.0%

-27.0%

Urban + Cross CountryDriving Schedule

Grade LoadCondition


Off-RoadCondition

0

0.2

0.4

0.6

0.8

1

1.2

Architecture AArchitecture BArchitecture C

-12.2%

-27.8%+12.6%

-26.0%

+7.5%-24.0%

+9.0%

-27.0%

Urban + Cross CountryDriving Schedule

Grade LoadCondition


Off-RoadCondition

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Summary and Future Plan

• SHEV model was configured with the previously developed VESIM.

• Cooling system model for the SHEV was developed.

• The results show that strategic approach to cooling system architectural design of SHEVs can reduce the power consumption and enhance the performance significantly.

• Co-simulation of VESIM and Cooling system model is needed to evaluate

- Fuel economy impact

- Interaction between the powertrain system and cooling system

Cooling System Architecture Design for FCS Hybrid Electric Vehicle

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