Failsafe Control Methods for EVs with the Failsafe Structure Driven by Front and Rear Wheels Independently

This paper describes failsafe control methods for electric vehicles (EVs) with the failsafe structure in which front and rear wheels are driven independently. Based on failure-diagnosis results, the failsafe control is done by dividing fault states into two types, i.e. a slight failure such as a current or a speed sensor failure and a serious failure such as an inverter or a motor failure. For the latter, the EV keeps on driving with only the healthy drive system by separating the drive system including the failed inverter or motor. On the other hand, for the former, a fault tolerant control is performed that keeps on driving while compensating for the function of the failed sensors so that the drive performance before failure can be maintained as much as possible. Effectiveness of the proposed methods is verified through simulations and experiments using bench test equipment which is equivalent to the actual EV drive systems and a prototype EV.