Propulsion system design of electric vehicles

There is a growing interest in electric vehicles due to environmental concerns. Recent efforts have been directed toward developing an improved propulsion system for electric vehicle applications. This paper is aimed at developing the system design philosophies of electric vehicle propulsion systems. The vehicle´s dynamics are studied in an attempt to find an optimal torque-speed profile for the electric propulsion system. This study reveals that the vehicle´s operational constraints, such as initial acceleration and grade, can be met with minimum power rating if the powertrain can be operated mostly in the constant power region. Several examples are presented to demonstrate the importance of constant power operation. Operation of several candidate motors in the constant power region are also examined. Their behaviors are compared, and conclusions are made