A New Speed Sensorless Controller Based on Double Observers for Permanent-Magnet Synchronous Motor

A new sensorless speed control method which is based on new sliding-mode observer (SMO) is proposed for permanent-magnet synchronous motor (PMSM). The main basis of the observer is the back electromotive force (EMF). The rotor speed is estimated by the back EMF observer (BEMFO). The method can be better than low-pass filter in accuracy. In the observer, the stator resistance also is as an estimator to improve the robustness of the system. The stability of the system is proved by the Lyapunov theory. And numerical simulations based on M-file in Matlab is put into practice. The simulation results testify that the novel sensorless speed control method based on sliding-mode observer is fast and pinpoint for speed tracking control of PMSM.