Adaptive sliding mode control based on a combined state/disturbance observer for the disturbance rejection control of PMSM

An improved adaptive sliding mode controller (ASMC) based on a combined state/disturbance observer (CSO) is proposed for the high-performance control of permanent magnet synchronous motor (PMSM). In order to estimate the unknown state and the disturbance including the parameter uncertainty and the external disturbance, the CSO is proposed. Different from the extended state observer (ESO) or generalized ESO (GESO), the CSO uses the linear combination of the extended high-order states to construct the new estimation. The CSO resolves the contradiction between the estimation accuracy and the noise insensitivity, so it is more applicable to time-varying disturbances. Then, the CSO and the ASMC are integrated in the PMSM speed controller by the feed-forward compensation to enhance the system robustness. A simple nonlinear adaptive law is presented to solve the unknown upper bound of the estimation error and minimize the chattering. The theoretical analysis shows that the global stability of the closed-loop system is strictly guaranteed. The simulation and experimental results are presented to demonstrate the effectiveness of the proposed control method.