Control strategy for motor drive system of electric vehicle

Abstract

An induction motor drive system is widely used in electric vehicles (EVs). However, most control strategies of these EVs focus only on control of the induction motor without considering the switching of different driving conditions and the changing of motor parameters. The upper limits of the torque generated by the motor are different under different motor parameters and driving conditions, which may lead to the fluctuation of the driving torque and affect the comfort and safety of the driver. This paper proposes a vector‐control‐based flexible control strategy to deal with this problem. First, the threshold values of the automatic speed regulator (ASR) and the automatic voltage regulator (AVR) could change with respect to the state variables of the motor including the change in driving conditions and some motor parameters; second, a backward proportional integral controller, which has a dynamically adjustable threshold, is added to the output of the ASR and AVR to achieve the flexibility of driving torque. Finally, a calculator that has threshold value is added to the input of the ASR and AVR controller. The results of simulation show that the designed flexible control strategy can achieve the stability of motor current, torque, and speed during the switching of different driving conditions. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.