A sensorless permanent magnet synchronous motor control strategy for improved sliding mode observers with stator parameters identification

An improved sliding mode observer (SMO) with the feature of identifying stator parameters in real time for permanent magnet synchronous motor(PMSM) control is proposed to address the case that the stator resistance and the inductance randomly change when a PMSM is running. An approximate saturation function is used as the switch function in the improved SMO control system to reduce the system chattering. The improved SMO estimates the stator resistance and inductance values by employing Lyapunov stability theorem on the premise of ensuring the stability of the observer and feedbacks them to the PMSM model to improve the estimation accuracy of rotor's position and velocity. The rotor's position and velocity information are estimated from the back electromotive force based on the principle of phase-locked loop. Simulation results show that the improved SMO quickly and accurately tracks the position and the velocity of a rotor, and has an attractive dynamic performance by estimating the resistance and inductance of the stator in real time and correcting the PMSM model.