An Optimized Resonant Power Supply for Soft Switching VSI in Electric and Hybrid Vehicle

The three-phase induction motor is the trend in electric & hybrid vehicles. The Voltage Source Inverter (VSI) which is driver and speed controller of the motor suffers from many problems. Resonant DC link is showing tremendous promise for next generation VSI used in adjustable speed AC machine drives. Although the resonant dc link inverter has many advantages but it has two major problems. The first problem is the resonant link voltage overshoot. The second one is the resonant link voltage zero-crossing failure. This paper presents an initial current optimization technique to solve the resonant voltage overshoot and zero crossing failure for smooth inverter and in turn vehicle operation, minimum weight & cooling requirements, low audible noise and improved efficiency. The resonant circuit has been mathematically analyzed to establish the proposed technique. A group of performance curves which allow the designer getting the optimum initial current at different resonant tank parameters. The circuit had been simulated and experimental results are presented to show the superior operation of the proposed technique.