High-Frequency Signal Injection using Extend State Observer for Position Sensorless PMSM Drives

In sensorless vector control of Permanent Magnet Synchronous Motor (PMSM) drives, it is important to obtain accurate rotor position. High-frequency (HF) voltage injection method is usually used to estimate the rotor position of the motor at low speed. However, the use of the digital filter reduces the estimation accuracy of the rotor position. In this paper, an improved signal processing method based on the HF square-wave voltage injection method is used to obtain the rotor position error signal. A third-order extended state observer (ESO) is used to estimate the rotor position and speed. Compared with the traditional sensorless control strategy, the proposed method reduces the use of the digital filter, simplifies the signal processing, eliminates the influence of the inverter nonlinearity on the accuracy of rotor position estimation and improves the dynamic performance of the system. Experimental results are provided to verify the effectiveness of the proposed method.