Department of Mathematics

McCleer Power, Inc.

Parallel Hybrid Vehicle Design*

Hybrid electric vehicles (HEVs) combine the internal combustion engine of a conventional vehicle with the battery and electric motor of an electric vehicle. This combination offers the extended range and rapid refueling that consumers expect from a conventional vehicle, with the significant energy savings and environmental benefits of an electric vehicle.

The practical benefits of HEVs include improved fuel economy and lower emissions compared to conventional vehicles. Hybrid power systems were conceived as a way to compensate for the shortfall in current battery technology: batteries can supply only enough energy for short trips.

An HEV with a parallel configuration has a direct mechanical connection between the engine and the wheels, as in a conventional vehicle, but also has an electric motor that drives the wheels simultaneously, that is "in parallel." For example, the vehicle can use the (relatively constant) power produced by the engine for constant-
speed driving and the electric motor for accelerating and decelerating.

An HEV is essentially an electric machine that can electronically ``balance the engine'' (function as an electronic flywheel), start the engine, and convert engine power into electricity. It can also provide extra power to the drive train when needed for hill climbing or quick acceleration.

The project objective is to determine, for a given vehicle size and driving pattern, what is the optimum relative power balance between the internal combustion engine and the electric motor. It is desired to maximize fuel economy --- which we assume corresponds to the minimum pollution --- subject to the constraint that the
vehicle 'handling' should be comparable to a conventional vehicle.

The ideal completed project deliverable would be a generic mathematical model that, given vehicle size, EPA driving patterns, and handling characteristics, will decide the optimum power ratio between engine and
motor. This is a large project and must be pruned to some interesting but useful portion.

*This summary prepared by R. E. Svetic and C. R. MacCluer with the assistance of Dr. P. J. McCleer, President, McCleer Power Incorporated, Jackson, Michigan.

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