A Sliding Mode Observer for PMSM speed and rotor position considering saliency

Sliding mode observer (SMO) for permanent magnet synchronous motor (PMSM) speed and rotor position is used to realize sensorless control. Most of the current researches studying the PMSM SMO are based on non-saliency PMSM model and ignore the difference between d- and q-axes inductances. This paper studies a novel SMO based on PMSM´s extended EMF (EEMF) model, considering the saliency of PMSM. It is more precise than the conventional SMO and also the structure is simple. The EEMF based SMO structure is presented in this paper, there is an extra loop feeding back the estimated speed to the observer. The stability condition of EEMF based SMO is studied to make sure that the observer is stable in converging to the sliding mode plane. This paper analyzes the structure and performance of the improved SMO strategy with SIMULINK based simulation and DSP based experiments. Results show that the proposed SMO of PMSM can satisfactorily estimate the position and speed of PMSM with saliency.