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
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oci
ty (
MP
H)
Time (s)
Driving schedule
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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
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time(sec)-1500
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-500
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time(sec)
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time(sec)
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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
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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
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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
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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)
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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
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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
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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)
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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!