Development of a parallel hybrid electric vehicle

This paper describes the development of a prototype parallel hybrid electric vehicle (HEV). Parallel configuration of HEV is achieved through an epi-cyclic transmission. A single stage epi-cyclic transmission is designed, developed and integrated into a vehicle equipped with conventional manual transmission. An internal combustion diesel engine and an electric motor are connected through epi-cyclic transmission to the propeller shaft of the vehicle. This parallel HEV provides five basic modes of operation namely engine mode, electric mode, power mode, engine/charge mode and regenerative braking mode. Each of these modes is obtained with the help of an electromagnetic clutch and brake integrated in the epi-cyclic gearbox. The selection of a mode depends upon the requirements of the vehicle. A feasible clutching logic and control strategy of parallel HEV is developed for operation of the vehicle in city, highway and high power requirement conditions. The advantage of such hybrid electric vehicle is that the performance of parallel HEV on engine mode is almost the same as that of the unmodified vehicle while it is also capable of purely electric low speed operation including launch from rest. The operational flexibility and better performance of the developed hybrid vehicle makes it a good choice for a parallel HEV.