Researching for Sensorless Control of PMSM Based on a Novel Sliding Mode Observer

In view of the low accuracy and slow convergence rate of the traditional sliding mode observer of permanent magnet synchronous motor (PMSM), a novel integral nonsingular fast terminal sliding mode observer (NINFTSMO) is proposed. Based on conventional nonsingular fast terminal sliding mode surface, the integral term is introduced to eliminate the noise and signal distortion of the differential state. The exponential term is introduced to accelerate the approach rate. In addition, in order to suppress the chattering problem of sliding mode control, a new sigmoid function is designed to replace the traditional sign function. For purpose of avoiding the phase lag problem, the position and velocity of the rotor are estimated from the phase locked loop tracking strategy. Simulation results show that the novel observer has advantages of quick response, small chattering and no phase lag. High observation precision and strong robustness of the novel observer can realize accurate observation of motor speed and position information.