Research on Sensorless Control of Permanent Magnet Synchronous Motor Based on Adaptive Gate Filter

Permanent magnet synchronous motor (PMSM) sensorless control system is widely used in some special environments, such as water immersion, oil immersion and high temperature and so on. A novel improved adaptive gate filter without attenuation and phase lag is proposed to solve the problems of the low-pass filter when the classical sliding mode observer (SMO) control algorithm is applied to PMSM sensorless control. Meanwhile, the saturation function is adopted to replace the traditional switching function, which effectively improves the problems of discontinuous jitter at the switch interface. The experimental results show that the proposed method can effectively eliminate the influence of filter and the chatting and effectively improve position tracking ability. Compared with the classical algorithm, the amplitude attenuation of the observed back EMF signal is reduced from about 34% to about 4%, and the high frequency buffeting component caused by the sliding mode structure is effectively filtered. As a result, the estimated rotor position error decreases from −52°~−35° to −2°~2°. When applied to the sensorless speed servo control of PMSM, the speed fluctuation is −30r/min ~ +30r/min and the motor runs smoothly.