High-Precision Position Error Correction Method for the PMSM Based on Low-Order Harmonic Suppression

Accurate rotor position is necessary for high-performance control of a permanent-magnet synchronous motor. Compared with the methods using position sensors to detect rotor position, the sensorless methods can simplify the motor structure and enhance the reliability. To improve the estimation accuracy of sensorless methods, the position error correction method based on the low-order harmonic suppression is proposed in this article. The low-order harmonics generated by the position error are analyzed in detail, which will cause extra motor losses. The position error signal can be reconstructed by low-order harmonics that are extracted by rotating the frame transformation and low-pass filter. And the estimated position can be corrected using the reconstructed signal. The proposed method can not only improve the position estimation accuracy, but also suppress the low-order harmonics, which can reduce motor losses and enhance the motor performance. Based on space vector pulsewidth modulation, the proposed method is independent of motor parameters. It can be applied to the sensorless methods that can obtain voltages. The position error correction method has well dynamic performance and great robustness. The effectiveness is verified by the experiments on the turbo molecular pump.