Introduction

By incorporating into the driveline of the vehicle the capability to generate electricity onboard the vehicle from a chemical fuel, a hybrid-electric vehicle has the characteristics of both an electric vehicle and a conventional internal combustion engine (ICE) vehicle and can be operated either on wall-plug electricity stored in a battery or from a liquid fuel (e.g., gasoline) obtained at a service station. This essay discusses technologies for hybrid-electric vehicles that can attain significantly higher fuel economy and lower emissions than conventional ICE vehicles of the same size, performance, and comfort.

Hybrid-Electric Vehicle Design Options

There are a large number of ways an electric motor, engine, generator, transmission, battery, and other energy storage devices can be arranged to make up a hybrid-electric driveline. Most of them fall into one of two configurations—series and parallel. In the series configuration (Figure 1, Top), the battery and...