Propulsion systems for electric cars

Proper selection of the propulsion system to meet the requirements of an electric passenger vehicle is of prime importance. Choice may be made among alternating current, direct current, or combined systems. Each approach can be implemented by utilizing various control techniques and power elements. For instance, an ac system may use an adjustable voltage inverter (AVI) or a pulse-width-modulated inverter (PWMI) for the power processor, and an induction motor or a synchronous motor for the rotating element. Similar alternatives exist for a dc system. The choice of a suitable manner of implementation must be. based on information characterizing the various elements and tradeoffs matching them to the vehicle requirements. This paper describes various ac and dc techniques, characterizes AVI, PWM, and representative dc chopper power processors and examines their interface with a variety of motors such as series, shunt, induction, etc.