Based on an Improved Sliding Mode Observer for Position Estimation of PMSM

Abstract

To reduce the chattering problem resulted from signum function in conventional sliding mode observer (SMO), a sensorless speed controller based on an improved SMO is proposed for permanent magnet synchronous motor (PMSM), where signum function is substituted for sigmoid function and the stability of the proposed SMO is verified using the Lyapunov method, the influence of different tilt parameters on position estimation is analyzed as well. To reduce phase delay in position estimation in conventional SMO, a new observer which has the structure of an extended Kalman filter is designed for back electromotive force estimation, which is expected to decrease estimation error of improved SMO. Based on improved SMO position sensorless control is modeled in MATLAB/SIMULINK, and result of simulation demonstrates correctness of improved SMO.