International Journal of Modern Communication Technologies & Research (IJMCTR)

7 www.erpublication.org  Abstract— The main objective of this paper is to provide a position sensorless control scheme for permanent magnet synchronous motor (PMSM) drive using a sliding mode observer (SMO). The rotor position and speed are estimated with only measuring stator voltages and currents. Compared with traditional SMO, the sign function is replaced by a sigmoid function in order to weaken the inherent chattering problem and increase estimation accuracy of the rotor position. The observer structure and its design method are discussed. The simulation results of the overall system are presented to demonstrate the effectiveness of the approach.