Chris_Mi_handout
.pdf
Hybrid Electric Vehicles: Control,
Design, and Applications
Prof. Chris Mi
Department of Electrical and Computer Engineering
University of Michigan - Dearborn
4901 Evergreen Road, Dearborn, MI 48128 USA
email: chrismi@umich.edu
Tel: (313) 583-6434
Fax: (313)583-6336
Part 6
Parallel HEV Design and Modeling
1
Contents
•Parallel hybrid architecture
•Control strategy of series HEV
•Sizing of major components
•Design example
•Modeling of parallel HEV
Parallel Architecture
•Two energy converters
•Engine and motor mechanically coupled
•Different configurations possible
Mechanical. coupling
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Operation Mode of Parallel
Architecture
•Battery alone mode: engine is off, vehicle is powered by the battery only
•Engine alone mode: power from ICE/G
•Combined mode: both ICE/G set and battery provides power to the traction motor
•Power split mode: ICE/G power split to drive the vehicle and charge the battery
•Stationary charging mode
•Regenerative braking mode (include hybrid braking mode)
Advantages of Parallel Architecture
•ICE operation can be optimized, with motor assist or share the power from the ICE
•Flexible in configurations and gives room for optimization of fuel economy and emissions
•Reduced engine size
•Possible plug-in hybrid for further improved fuel economy and emission reduction
•Disadvantages
–Complicated control strategy
–Complex transmission
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Torque Coupling
• Splits engine torque
• Or combine engine torque and motor torque
• Regenerative braking |
Tout |
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k1 |
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Commonly Used Torque Coupling |
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k |
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k =1, k |
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r4 |
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r1 |
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Gear box |
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k1 =1 |
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Chain assembly |
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k2 =1 |
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Shaft |
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Two Transmission Design
• Flexibility in
design
• Complex two transmissions
Two Shaft Design – torque before transmission
• One transmission design
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Separated Axle Configuration |
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Engine |
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Motor |
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mission |
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mission |
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Motor |
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controller |
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Batteries |
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Speed Coupling
• Splits engine torque
• Combines engine speed and motor speed
• Regenerative braking |
ωout |
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6
Speed Coupled HEV
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Lock 2 |
Clutch |
Lock 1 |
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Engine
Transmission
Motor
Motor controller
Batteries
Torque and Speed Coupling
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Control Objectives
•Control objectives
–To satisfy performance requirements including acceleration, gradeability, and maximum cruising speed
–To achieve overall high efficiency
–To maintain battery SOC
–To recover braking energy
Control Strategy
•Categories of the control strategy
–Supervisory: vehicle controller
–Component controllers: engine controller, motor controller, battery controller
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Control Scheme for Parallel HEV
•Two different modes: propelling and
braking
• Vehicle controller gather commands from accelerator and brake pedal
• And gather data from 
vehicle speed and 
SOC 
•Sends commands to component controller
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Accelerator pedal |
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Brake pedal |
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Propelling |
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position signal |
Brake |
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Vehicle speed |
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Vehicle controller |
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Batteries’ SOC |
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Engine power |
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power |
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power command |
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Motor |
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Engine controller |
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Engin |
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Moto |
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Engine |
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Motoring |
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braking power |
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Transmission |
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Wheels |
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Driving wheels |
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Control Strategy and Power Management
•Motor alone:
–Speed V<Vlow
–SOC>SOClow
•Combined
–Pt>Pe-opt
–SOC>SOClow
•Power split
–Pt<Pe-opt
–SOC<SOClow
•Engine alone
–Pt<Pe-opt
–SOC>SOChigh
•Engine off
–V<Vhysteresis
–SOC>SOClow
•Avoid engine on/off too often
• Regen
• Hybrid
braking
•Example: Vlow=25mph
•Vhysteresis=15mph
•SOClow=0.6
•SCOhigh=0.99
9
Mild Hybrids
•Reduce size of battery (cost, weight and volume)
•Reduce complexity of drivetrain (reduced cost)
•Reduce energy consumption during engine idle (shut off engine, as well as transmission loss saved)
•Drawbacks
–Not able to drive vehicle alone using the motors
–Not be able to recover majority of braking energy
Parallel Mild Hybrid
•Example, Honda Civic: 10kW motor (10 percent of engine)
•Operation Modes
–Engine alone
–Motor alone (ultra low speed)
–Regen mode
–Combine mode
–Power split mode
Accelerator |
Brake |
pedal |
pedal |
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Drivetrain |
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Battery SOC |
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Motor |
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Battery |
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controller |
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Engine
Clutch Motor Transmission
Final drive
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