Speed and rotor position estimators for PMSM with sliding mode EMF observer front

The paper discusses the problem of speed and rotor position estimation for the Permanent Magnet Synchronous Motor (PMSM) and presents a family of estimation methods. Estimation is done sequentially: first, the EMFs are obtained using a sliding mode observer; then, the speed is estimated. The estimators are based on the model of the PMSM in the stationary reference frame. The paper presents an SM observer for the EMFs (the front observer) and various observers for the speed (the back observers). It is shown that the speed estimation process offers many mathematical options - it can be adaptive, sliding-mode based, algebraic, or it can use a doublemanifold sliding mode structure. The properties of the various speed observers and their feasibility and accuracy are discussed. The method can be applied in a sensorless PMSM drive where the speed and rotor position angle are needed for control implementation. The paper presents the design of the observers along with simulation results and experimental tests.