An Improved Sliding Mode Control Using Reduced-order PI Observer for PMSM system

This paper proposes an adaptive sliding mode control combined with a disturbance observer method for permanent magnet synchronous motors (PMSMs). The main advantages of the proposed method are that it improves speed control of the motor when parameter uncertainties and external load torque exist in the speed loop as an unknown disturbance. First, a sliding mode control method based on an adaptive sliding mode reaching law (ASMRL) is proposed to improve sliding mode chattering. Then, considering the influence of the unknown disturbance in the speed control, the reduced-order PI observer is employed to estimate the disturbance and feed it forward to the ASMRL as a compensation signal. Therefore, the robustness of the ASMRL will be maintained under the combination of ASMRL+ROPIO. The results in practical experiments show the effectiveness of the ASMRL+ROPIO method for reducing chattering and dealing with unknown disturbances.