Estimation of Rotor Velocity and Stator Resistance for PMSM Drive using Back-EMF SMO

Background: Sensorless control of permanent magnet synchronous motor (PMSM) at low speed remains a challenging task. Introduction: In this paper, a sensorless vector control of PMSM using a new structure of a back EMF sliding mode observer (SMO) is proposed. Methods: To remove the mechanical sensors, a back EMF-SMO is built to estimate the rotor position and speed of PMSM drives. The SMO, which replaces a sign function with a sigmoid function, can reduce the chattering phenomenon. This sensorless speed control shows great sensitivity to stator resistance and system noise. Results & Discussion: To improve the robustness of sensorless vector control, the back EMFSMO technique has been used for stator resistance estimation. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. Conclusion: The validity of the proposed SMO with a 1.1 kw low-speed PMSM sensorless vector control has been demonstrated by real experiments.