Disturbance observer based discrete PI control system with back-calculation anti-windup technique for improvement transient performance of PMSM

Abstract

In this paper disturbance observer-based control (DOBC) system for PMSM has been proposed. The cascade structure of the discrete-time PI-PI control system with back-calculation anti-windup scheme for both loops has been adopted. High order disturbance observer (HODO) has been adopted to estimate the total disturbance and compensate it in the speed loop of the PMSM control system. In the HODO, the disturbance estimation is based on the motion equation which takes into account torque losses due to the drug resulting from the time-varying flux, hysteresis, and friction. Unlike the traditional observers, the HODO does not require the derivatives of the disturbance to be zero, which is considered as its main advantage. The fast-varying disturbance as cogging torque and a high-frequency electromagnetic noise in the PMSM system also affect on the performance of control system, which are analyzed in the study. In the real-time experiments, the proposed control system achieves less speed errors and faster response comparing with controller without disturbances observer. The experimental results have proved the feasibility of the proposed control scheme.