Impact of Position Measurement Angle Error on Performance of PMSM Drives for Electric Power Steering in a Wide Speed Range

ABSTRACT The permanent magnet synchronous motor (PMSM) serves as the power source for the electric power steering (EPS) system, which directly influences the steering feeling. Therefore, the control performance of the PMSM drive is crucial for the EPS system's overall performance. The position measurement angle error (contains measurement delay angle and periodic angle error) plays a significant role in PMSM drives, especially when the motor is rotating in the flux weakening (FW) region. In this paper, the impact of the position angle error on the performance of PMSM drives for EPS across a wide speed range is thoroughly examined. The effect of the measurement delay angle is analysed by considering the voltage and current constraint boundaries of the motor at different rotation speeds. Then, calibration and compensation of the position measurement delay angle are presented. Furthermore, the impact of the periodic angle error on current/torque ripple has been elaborated, and a sensorless control scheme is proposed to mitigate the current/torque ripple caused by such periodic error. According to the experimental results, it has been determined that the motor can operate stably over a wide speed range with an appropriate compensation of the measurement delay angle, and the current/torque ripple caused by the periodic angle error can be effectively eliminated with the proposed sensorless control scheme. As a result, it is confirmed that the analysis and discussion, as well as corresponding compensation methods, demonstrated in this paper can improve the steering feeling of the EPS.