Application of sliding mode observer for induced e.m.f., position and speed estimation of permanent magnet motors

This paper presents a method for speed, position and induced e.m.f. estimation in permanent magnet synchronous machines (PMSM) through application of the sliding mode technique. The electrical dynamic equations of a PMSM are modified to obtain the sliding mode observer model where the induced e.m.f., position and speed are estimated using measured stator currents and voltages. The observer of the induced e.m.f. is implemented using analog devices and the estimated speed and position variables are numerically implemented. From the estimated position another modified method is proposed for speed estimation based on an adaptive method. Simulation results are used to analyse the proposed induced e.m.f., position and speed observer. Experimental results prove the expected performance of the observer