ARC

Simulink Based Vehicle Cooling Simulink Based Vehicle Cooling System Simulation;System Simulation;

Series Hybrid Vehicle Cooling Series Hybrid Vehicle Cooling System SimulationSystem Simulation

13th ARC Annual Conference May 16, 2007

SungJin Park, Dohoy Jung, and Dennis N. Assanis

University of Michigan

ARC

Outline

• Introduction– Motivation– Objectives

• Simulation and Integration

• Hybrid vehicle system modeling [VESIM]

• Cooling system modeling

• Configuration of HEV cooling system

• Summary

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Vehicle thermal management and cooling system design

• Motivation– Additional heat sources

(generator, motor, power bus, battery)

– Various requirements for different components

• Objective– Develop the HEV Cooling System

Simulation for the studies on the design and configuration of cooling system

– Optimize the design and the configuration of the HEV cooling system Conventional Cooling System

Radiator1

Oil Cooler

FAN

Thermostat

Pump

By-

Pa

ss

CAC2

Grille

A/C Condenser

HEV Cooling System

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Overview of Cooling System Simulation•Cooling system model use simulation data from the hybrid system model

•Minimizes computational cost for optimization of design and configuration

Hybrid Propulsion System Model [VESIM] HEV Cooling System Model

0

10

20

30

40

50

60

0 200 400 600 800 1000 1200 1400

Vel

oci

ty (

MP

H)

Time (s)

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)

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Hybrid propulsion system configuration and VESIM

Engine

Generator

Vehicle

Motor

BatteryController

PowerBus

EngineGenerator

Power Bus

Battery

Motor

Wheel

Engine400 HP

(298 kW)

Motor2 x 200 HP (149 kW)

Generator400 HP

(298 kW)

Battery

(lead-acid)

18Ah /

25 modules

Vehicle20,000 kg

(44,090 lbs)

Maximum speed

45 mph

(72 kmph)

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Hybrid vehicle power management

Discharging mode Charging mode Braking mode

W h e e lM

oto

r

Generator

Mo

tor

Power BusController

Engine

Battery

W h e e l

W h e e lM

oto

r

Generator

Mo

tor

Power BusController

Engine

Battery

W h e e l

• Battery is the primary power source

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

Power Flow

Active ConditionallyActive

Inactive

• Engine / generator is the primary 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

W h e e lM

oto

r

Generator

Mo

tor

Power BusController

Engine

BatteryW h e e l

• 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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0.55

0.6

0.65

0.7

0.75

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)

-200

-100

0

100

200

0

500

1000

1500

2000

2500

3000

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)

Vehicle simulationVehicle driving cycle

Cycle simulation results ( engine / generator / motor / battery)

Vehicle simulation model [VESIM]

Engine Speed Generator Speed Motor Speed

Engine BMEP Generator Torque Motor Torque

0

10

20

30

40

50

60

0 100 200 300 400 500

vehicle speed (demand)vehicle speed (actual)

time(sec)

Battery SOC

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Cooling system modeling;Configurations

Configuration A

Motor(A/B)

Generator

PowerBusRadiator1

Engine

Radiator2

FAN

Thermostat

Pump

ElectricPump

By-

Pas

s

CAC1

Grille

Radiator1

Oil Cooler

FAN

Thermostat

Pump

By-

Pas

sCAC2

Grille

A/C Condenser

HEV Cooling System Model in Matlab Simulink

Cooling Circuit for Electric Parts

Cooling Circuit for Engine

Cooling Circuit Tower 2

cac spec

inler air v elocity

inlet air temperature

turbo charger

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 v elocity , m/s

inlet air temp, oC

Ramass1

Tcoolout

thermodelP1

RadelP, bar

to f an

outlet air temp, K

radiator1

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 f low rate (kg/s)

coolant temp in (K)

coolant temp

mc temp

motor(A,B)/controller <mc>

coolant f low rate (kg/s)

coolant temp in (K)

coolant temp

gc temp

generator/controller <gc>

0.2102

0.05466

0.1089

0.3737

0.003829

336.5

flowrate 1flowrate 2flowrate 3

flow sum

dptemp1

heat rejection, kW

cool mass1

coolant temp

Tcool_out

f low coef f a/b/c

engine block

heat rejection rate

pump speed

engine

pump speed

pressure rise, bar

coolant temp

coolant mass

pressure rise

cool mass, kg/s

coolant temp, K

coolant density , kg/m1

coolant pump2

pump speed

pressure rise, bar

coolant temp

coolant mass

pressure rise

cool mass, kg/s

coolant temp, K

coolant density , kg/m3

coolant pump1

T_pb

T_gen

T_mot

motor_rpm

f an on/of f

coolant pump motor/controller

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

collector4

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

radiator2 spec

radiator1 spec

radi out air T

inlet air v el 1, m/s

inlet air v el 2, m/s

inlet air temp, oC

air side, fan

Teng

Telec

f an_rpm

V_speed

Ta

air side input

rad_air_temp

To File6

delp.mat

To File5

mass.mat

To File4

temp.mat

To File3

delp_e.mat

To File2

mass_e.mat

To File1

temp_e.mat

To File

Terminator2

Terminator

coolant temp1

coolant mass

delP

recirculate mass

radiator mass

coolant temp2

Re delP

thermo delP

T/S temp

delP1

T/S2

Load input data

C_m (kg/s)

C_Tin(K)

C_m(kg/s)

C_Tout(K)

Reservoir2

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

Power Bus<pb>

u(1)-273

K->oC

1800

Display3

371.1

Display1

Clock

f(u)

C2K

cool_mass

coolant temp, K

inlet air v elocity , m/s

inlet air temp, oC

coolant density , kg/m3

Tcoolout

f low coef f a/b/c

outlet air temp, K

cac spec

1st charge air cooler

MotorGenerator PowerBus

Radiator1

Radiator2

T/S

ElectricPump

Engine

CAC1

ParallelCircuit

ParallelCircuit

Mech.Pump

EngineBlock

Fan

TurboCharger

Cooling Circuit Tower 1* Run Tower2 first

copy "to_ cac2_ t_ T.mat"

cac spec

inler air v elocity

inlet air temperature

turbo charger

Ramass

thermodelP

coolant temp, K

inlet air v elocity , m/s

inlet air temp, oC

coolant density , kg/m3

Ramass1

Tcoolout

thermodelP1

RadelP, bar

to f an

outlet air temp, K

radiator

f(u)

oC->K

pump speed

heat rejection rate

engine

pump speed,

pressure rise, bar

coolant temp

coolant mass

pressure rise (bar)

cool mass, kg/s

coolant temp, K

coolant density , kg/m1

coolant pump

Remass

Recooltemp

RedelP

Ramass

Racooltemp

RadelP

enginedelP

thermodelP

coolant mass

coolant temp

pressure drop2

collector1

f an speed, rpm

v ehicle speed, km/h

inlet air temp, oC

radiator2 spec

radiator1 spec

radi out air T

inlet air v el 1, m/s

inlet air v el 2, m/s

inlet air temp, oC

air side, fan

Tcool out

f an_rpm

V_speed

Ta

air side input

rad_air_temp

To File

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)

Reservoir1

coolant f low rate (kg/s)

coolant temp in (K)

heat rejection rate(kW)

coolant temp

cool mass

Oil cooler dp(bar)

Oil cooler1

f(u)

K->oC

0

Display4

0

Display3

0

Display20

Display11

0

Display1

Clock

inlet air v elocity , m/s

inlet air temp, oC

to f an

outlet air temp, K

A/C

cool_mass

coolant temp, K

inlet air v elocity , m/s

inlet air temp, oC

coolant density kg/m3

cool_mass1

Tcoolout1

outlet air temp, oC

cac spec

delP(bar)

2nd charge air cooler

Radiator

A/CCondenserT/S

CAC2

Mech.Pump

Fan

OilCooler

ARC

Guide Lines of Cooling system configuration

Criteria for system configuration• Radiators for different heat

source components are allocated in two towers based on operation group

• The radiators are arranged in the order of maximum operating temperature

• Electric pumps are used for electric heat sources

• The A/C condenser is placed in the cooling tower where the heat load is relatively small

• Battery is assumed to be cooled by the compartment A/C system due to its low operating temperature (Lead-acid: 45oC)

ComponentHeat

generation (kW) *

Control Target

T (oC)

Operation group**

Engine 190 120 A

Motor / controller

27 95 B

Generator / controller

65 95 A

Charge air cooler

13 - A

Oil cooler 40 125 A

Power bus (DC/DC

converter)5.9 70 C

Battery*** 12 45 D

* Grade Load condition

** The heat sources that generate heat simultaneously during driving cycle are grouped together.

*** Maximum speed condition / Lead-acid

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ConfigurationsConfiguration B

Motor(A/B)

PowerBus

Radiator1

Radiator2

FAN

ElectricPump

Grille

ElectricPump

A/C Condenser

Generator

Radiator3

FAN

ElectricPump

Grille

Radiator2

CAC

Radiator1

Oil Cooler Thermostat

Pump

By-

Pas

s

Engine

Pump

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

Configuration C

Po

wer

Gen

erat

ion

Veh

icle

Pro

pu

lsio

n

ARC

Modeling ApproachComponent 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 a pair of valves 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 Input and Exchange Model for Engine Block and Electric Components– Lumped thermal mass model– Heat transfer to cooling path (Qint) and to

outer surface (Qext; radiation and natural convection)

• Engine– Map based engine performance model– Heat rejection rate as a function of speed

and load is provided by map

• Turbo Charger– Map base turbo charger performance

model– The temperature and flow rate of the

charge air as functions of speed and load are provided by map

Schematic of Heat Exchange Model at Engine and Electric components

Coolant Flow

Q

Qint

Qext

Modeling Approach:Heat source

Engine heat rejection rate

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Modeling Approach:Heat sources (cont.)

• Oil Cooling Circuit– Heat addition model : heat is directly added to the oil– Heat rejection rate as a function of speed and load is provided by map

• Condenser– Heat addition model: heat is directly added to the cooling air– Constant value is used for heat rejection rate

Heat generation from generator is handled as 2-D lookup table indexed by rotor speed and input torque

Map based Generator and Controller model

1_ TQ genm

• Charge air coolers– 2-D FDM-based model– In contrast to radiator, heat

transfer occurs from air to coolant

• Generator– Heat generation is calculated

using a 2D look-up table indexed by speed and input torque

– Lumped thermal mass model

ARC

Power Bus Model

mc

mcmccopbgenpb

wTVIVIabsQ

)1(1_

Battery charging & Motor is working

Otherwise :Motor is working

Motor is generating

mc

mcmcpbgenpb

wTQ

1_

mcmcmcpbgenpb wTQ 1_

Modeling Approach:Heat sources (cont.)

• Motors– Heat generation is calculated

using a 2D look-up table indexed by speed and input torque

– Lumped thermal mass model

• Power bus– Power bus regulates the power

from electric power sources and supply the power to electric power sink

– Heat generation is determined by battery and motor power

– Lumped thermal mass model

Heat generation from motor is handled as 2-D lookup table indexed by rotor speed and output torque

Map based Motor and Controller model

1

1_

TQ genm

Motor

Battery

Power Bus

Motor

Battery

Power Bus

Motor

Battery

Power Bus

ARC

Modeling Approach:Heat sinks

• Heat exchanger (radiator)– Design variables

• Core size • Water tube : depth, height, thickness• Fin : depth, length, pitch, thickness• Louver : length, height, angle, pitch

– Based on thermal resistance concept– 2-D Finite Difference Method

05.028.068.023.029.014.027.049.0

90Re

l

f

l

t

l

l

l

t

l

f

l

fP P

t

P

P

P

L

P

D

P

L

P

Pj

l

i=12 .

..

Ni

j=1

2

.

.

.

.

.

.

.

Nj

Staggered grid system for FDM

Design parameters of CHE core

Structure of a typical CHE

3/2

,

Prapaa

a

CV

hj

Empirical correlation for ha

(by Chang and Wang)

ARC

Modeling Approach:Heat sinks(cont.)

• Oil cooler– Finned concentric pipe heat exchanger model

for Oil Cooler• Counter flow setup• NTU approach is used to calculate the exit

temperature of two fluids

NTU MethodSchematic of Heat Exchange at Engine and Electric components

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Modeling Approach:Delivery media (Coolant)

• Coolant Pumps– The coolant flow rate is calculated

with calculated total pressure drop by cooling system components and the pump operating speed

– Performance map is used to calculate the coolant flow rate

– The mechanical pump is driven by engine and electric pump is driven by electric motor

by- pass coolant pump

engine

passbyheatpump PPP

radiatorheat PP

by- pass by- pass

coolant pump

Heat 1

thermostat

radiator

Coolant circuit (driven by engine)

passbypump PPP

radiatorPP

Heat 2

coolant pump

engine

pumpP radiatorheat PP

coolant pump

Heat 1

radiator

Coolant circuit (driven by motor)

pumpP radiatorPP

Heat 2

Performance Maps of Mechanical Pump

EfficiencyFlow rate

Performance Maps of Electric Pump

EfficiencyFlow rate

ARC

Open

Close

Modeling Approach:Delivery media (Coolant)

radiatorvalveSTrapiperacircuit PPPP _/__

valveSTrepiperecircuit PPP _/__

22

22

reloss

re

re

rere

VK

V

D

Lf

QPV

KV

D

Lf radiator

raloss

ra

ra

rara

22

22

P Pipe (radiator circuit)P radiatorP radiatorP

P Pipe (re-circulate circuit)PP T/S_ to_re-circulateP

P T/S_ to_radiatorP

To PumpFrom Heat

Sources

Valve lift curve of T/S

recircuitracircuit PP __ recircuitracircuit PP __

Coolant flow calculation based on pressure drop

radiatorcerecirculatctotalc QQQ ___ radiatorcerecirculatctotalc QQQ ___

• Thermostats– Two way valve with Hysteresis characteristics– Coolant flow rate to re-circulate circuit and radiator are determined by

the pressure drops in each circuit

-2

0

2

4

6

8

10

12

14

365 370 375 380

Temperature (K)

Open

Close

T/S valve lift with hysteresis

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Modeling Approach:Delivery media (Oil/Air)

• Oil Pump– Map based gear pump model for Oil

Pump

• Cooling fans– Total pressure drop is calculated from

the air duct system model based on system resistance concept

– Performance map is used to calculate the air flow rate Map Based Gear Pump Model

Cooling air flow circuit

upstream

cooling air flow

Cooling air flow circuit

down stream

radiator2 grilleradiator1fan & shroud

Air duct system based on system resistance concept

condenser

Fan & Shroud

Radiator 1,2

Grille

Condenser

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Test conditions• Test condition for sizing components and evaluating cooling

system configuration

• The thermal management system should be capable of removing the waste heat generated by the hardware under extreme operating condition

• Grade load condition is found to be most severe condition for cooling system

-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 of off-road condition

Ambient Temperature 40 oC

45mi/h 30mi/h

30mi/h

7%

Grade Load Maximum Speed Off-Road

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Configuration test;Grade Load (30 MPH, 7 %)

Max. SOC: 0.7Min. SOC: 0.6Initial SOC: 0.6

0 200 400 600 800 1000 1200 1400 1600 18000

200

400

600

800

1000

1200

1400

1600

1800

2000

time [sec]

spee

d [r

pm

]

Engine speed

0 200 400 600 800 1000 1200 1400 1600 18000

200

400

600

800

1000

1200

1400

1600Engine BMEP

time [sec]

BM

EP

[kP

a]

0 200 400 600 800 1000 1200 1400 1600 18000.5

0.55

0.6

0.65

0.7

0.75

0.8

time [sec]

SO

C

Battery State of Charge

30mi/h

7%

Grade Load

Engine Speed Engine BMEP

Battery SOC

ARC

Configuration A and B

Motor(A/B)

Generator

PowerBusRadiator1

Engine

Radiator2

FAN

Thermostat

Pump

ElectricPump

By-

Pas

s

CAC1

Grille

Motor(A/B)

PowerBus

Radiator1

Radiator2

FAN

ElectricPump

Grille

ElectricPump

A/C Condenser

Generator

Radiator3

FAN

ElectricPump

Grille

Radiator2

CAC

Radiator1

Oil Cooler Thermostat

Pump

By-

Pas

s

Engine

Pump

Radiator1

Oil Cooler

FAN

Thermostat

Pump

By-

Pas

s

CAC2

Grille

A/C Condenser

• Config. A could not meet the cooling requirements of electric components

Configuration A Configuration B

Generator Generator

Motor

PowerBus PowerBus

Motor

ARC

Configuration A and B

Motor(A/B)

Generator

PowerBusRadiator1

Engine

Radiator2

FAN

Thermostat

Pump

ElectricPump

By-

Pas

s

CAC1

Grille

Motor(A/B)

PowerBus

Radiator1

Radiator2

FAN

ElectricPump

Grille

ElectricPump

A/C Condenser

Generator

Radiator3

FAN

ElectricPump

Grille

Radiator2

CAC

Radiator1

Oil Cooler Thermostat

Pump

By-

Pas

s

Engine

Pump

Radiator1

Oil Cooler

FAN

Thermostat

Pump

By-

Pas

s

CAC2

Grille

A/C Condenser

• Performance of one CAC in Config. B was better than that of two CAC in Config. A

Configuration A Configuration B

CAC1

CAC2

CAC

ARC

Configuration B and C

Motor(A/B)

PowerBus

Radiator1

Radiator2

FAN

ElectricPump

Grille

ElectricPump

A/C Condenser

Generator

Radiator3

FAN

ElectricPump

Grille

Radiator2

CAC

Radiator1

Oil Cooler Thermostat

Pump

By-

Pas

s

Engine

Pump

• Config. C is designed by adding a coolant by-pass line to Oil Cooler in Config. B

• Power consumption of pump is reduced by 5% adding the bypass circuit

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

Configuration B Configuration C

2.5

2.75

3

3.25

3.5

3.75

4

0 300 600 900 1200 1500 1800

no by-passmean (no by-pass)by-passmean (by-pass)

time (sec)

ARC

Summary

• The HEV Cooling System Simulation is developed for the studies of the cooling system design and configuration

• The HEV cooling systems are configured using the simulation

• In hybrid vehicle, the heat rejection from electric components is considerable compared with the heat from the engine ( Grade Load : heat from electric components ≈ 98kW, heat from engine module ≈ 240kW)

• Proper configuration of cooling system is important for hybrid vehicle components, because the electric components work independently and have different target operating temperatures

• Parasitic power consumption by the cooling components can be reduced by optimal configuration design

• Optimization study of cooling system is conducted using developed model (Symposium II, “Optimal design of electric-hybrid powertrain cooling system”)

ARC

Acknowledgement

• General Dynamics, Land Systems (GDLS)

ARC

Thank you!