Improved Sliding-Mode Observer for Position Sensorless Control of PMSM

In the traditional sliding mode observer, the low-pass filter and position compensation will decrease accuracy and dynamic response of the speed observation. An improved SMO is designed to optimize the performance of PMSM drive system. A back electromotive force observer is adopted. Through this way, not only is rotor angle compensation no longer needed, but also the accuracy of the observer is improved. Based on the above method, an improved SMO is constructed to improve the steady state performance, which can dynamically change the feedback gain according to the speed. The algorithm identified stator resistance online is proposed which can help update the parameters of sliding mode observer by using the Lyapunov function. The results of simulations show that the proposed algorithm can suppress the chattering problem and enhance the accuracy of estimation.