Sensorless Control Strategy of Permanent Magnet Synchronous Motor Based on Extended Sliding Mode Observer and the Feedforward Phase Compensator

This paper proposes a sensorless speed control strategy for a permanent-magnet synchronous motor (PMSM) based on an extended sliding-mode observer (SMO), which combines an improved SMO with error compensation and model reference adaptive (MRA). This strategy suppresses pulsation and improves the accuracy of position estimation. First, the extended SMO state equation and the estimated dynamic equation of the back-EMF are used as the reference model and adjustable model, respectively. Then the feedforward phase compensator is used to decrease the error of back-electromotive force (back-EMF). Finally, by applying the MRA control and the Lyapunov stability principle, an appropriate adaptive law is chosen to make the adjustable model approach the reference model. The proposed strategy enables the extraction of rotor speed and back-EMF signals. Meanwhile, the error of estimated angle and speed decreases significantly. The simulation results verify the effectiveness and accuracy of the proposed strategy.