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Hybrid Vehicle Smart Scheduling

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What is HEV?

• HEV – Stands for Hybrid Electric Vehicle

• An HEV is a vehicle which involves multiple

sources of power

 – An EV is an electric vehicle, battery operated only.Sole power by electric motor

 – A traditional vehicle has sole propulsion by ICE or

diesel engine – Energy source can be gas, natural gas, battery,

ultra capacitor, fly wheel, solar panel, etc.

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Why HEV?

• Optimize the fuel economy

 – Optimize the operating point of ICE

 – Stop the ICE if not needed

 – Recover the kinetic energy at braking

• Reduce emissions

 – Minimize the emissions when ICE is optimize

operation – Stop the ICE when it’s not needed

• Quiet Operations

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Current Status of HEV

Source: Alternative Fuels and Advanced Vehicle Data Center (U.S. DoE)

Year % of all vehicles Units sold

1999 0.0001% 17

2002 0.24% 36,035

2006 1.77% 252,636

2010 2.37% 274,210

2012 2.97% 322,227

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Types of HEV

• Parallel HEV: multiple propulsion sources can

be combined, or drive the vehicle alone with

one of the energy sources

• Series HEV: sole propulsion by electric motor,

but the electric energy comes from another

energy source, such as ICE

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Operation Mode of Parallel HEV

• Motor alone mode: engine is off, vehicle ispowered by the battery/motor only

• Engine alone mode: ICE drive the vehicle alone

•

Combined mode: both ICE and motor providepower to drive the vehicle

• Power split mode: ICE power split to drive thevehicle and charge the battery

•

Stationary charging mode• Regenerative braking mode (include hybrid

braking mode)

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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

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Existing Algorithms• Rule-based

1) Below 20MPH, only the EM is used.

2) If the demanded power is greater than the maximumengine power, the motor is used to produce excesspower.

3) Charges the batteries by regenerative braking.

4) If the battery SOC is lower than 60% of the capacity,the engine should provide additional power to charge

the battery.

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Existing Algorithms

• Optimization-based

 – Global (Offline) Optimization

• Have all the data beforehand

• For specific driving practice• min + 1

=0  ( , )=0  

 – Online Optimization

• Depends on instantaneous data

• Have good portability

•   ( += ) 

•  

(),

()  

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Comparison of Existing Algorithm

Complexity Portability Real Time Optimality

A-ECMS Low High Yes Middle

Rule-based Lowest Low Yes Low

Global

Optimization

Highest Low No Best