A Back-EMF Sliding-Mode Observer for PMSM Sensorless Control with Online Stator Resistance Estimation

In permanent magnet synchronous motor (PMSM) drive systems, the model-based sensorless control methods are widely used due to the limitations of position sensors. However, the stator resistance changes with the external temperature. Thus, the stator resistance in the model is no longer accurate, affecting the accuracy of observation. To improve the parameter robustness, an extended back electromotive force (EMF) sliding-mode observer is proposed with online resistance estimation. The Lyapunov function is used to design the adaptive law of resistance estimation. Then, it is applied to the observer to eliminate the influence of resistance mismatch. The observer gain is designed reasonably according to stability analysis. The experimental results show the superiority of the proposed method.