TABLE OF CONTENTS Any vehicle that has more than one power source can be classified as a hybrid electric vehicle (HEV), but most frequently the term is used for a vehicle which combines electric drive with a heat engine using a fossil-fuel energy source.
The heat engine-electric hybrid vehicle, first conceived as long ago as 1900, is intended to overcome the limited range and long recharge time of the pure electric vehicle which relies for its energy source only on its battery. It usually achieves this desirable objective by combining electric drive with a conventional heat engine using a fossil fuel energy source. This engine may use any of a wide range of heat-engine technologies including two- and four-stroke spark-ignited gasoline engines; two- and four-stroke diesel engines; Stirling engines; or gas turbines. These engines are designed for operation at maximum efficiency to reduce fossil-fuel consumption and emissions to the lowest possible level, and this is achieved by the use of various methods of combining the two propulsion systems and by sophisticated control strategies to optimise their interaction.
The basic conventional automotive drive system uses an internal combustion engine coupled to the transmission and the road wheels through a gearbox that is used as a matching device between the engine and its load. To provide sufficient power at the road wheels for adequate acceleration and hill climbing (gradeability) at an acceptable speed, it is necessary to use an engine with a maximum power output about ten times greater than would be required to...
