Failure detection method for electric vehicles and fail-safe control

Abstract

An object of the present invention is to secure safe driving of electric vehicles by enabling torque control regardless of sensor disorder. In the present invention, the mode of current sensor disorder is detected by a sensor disorder detection means. If it is found as a result that only 1 out of 3 current sensors is failing, the current of the failing current sensor is estimated by 2 normal current sensors and the torque control of the motor is continued by the ordinary torque control system. If 2 or more current sensors are found to be failing, a torque control system based on an AC current reference operation means is formed to control the motor torque based on the AC current reference. If a sensor failure detection means determines that only 1 phase is failing in the speed sensor, the motor torque is controlled by using the remaining 1 phase to detect the rotating angular speed of the motor. If all speed sensors are failing but the current sensors are normal, the motor torque is controlled by estimating the motor torque from the 3 phase AC current. If both the current sensors and the speed sensors are found to be failing, the motor torque is controlled based on the estimated torque control and rotating angular speed to continue the driving that is needed to avoid dangerous situations.