A simplified composite current-constrained control for permanent magnet synchronous motor speed-regulation system with time-varying disturbances.

Under the single-loop structure, the problem of overcurrent protection for permanent magnet synchronous motor (PMSM) is investigated in this paper. Due to the combination of speed loop and current loop, the q-axis current become a state of PMSM control system, instead of the output of current loop in the cascade control. As a consequence, the conventional controllers can not restrict the q-axis current into a safe zone. But an oversize transient current may lead to damage of hardwares and property loss. To this end, a new current-constrained controller is proposed to deal with the issue of over-current protection. Different from previous methods of state constraints, the effects of disturbance is taken into account of controller design. A reduced-order generalized proportional integral observer (RGPIO) is adopted to estimate the uncertainties and disturbances. Our method can be considered as a composition of current-constrained control plus feed-forward compensation based on RGPIO. A rigorous stability analysis for the closed-loop system is presented. Compared with the conventional PID controller, the proposed method not only limits q-axis current to a safe range, but also has a good anti-disturbance ability. The feasibility and efficiency of the proposed method is validated by both simulation and experimental results. [ABSTRACT FROM AUTHOR]