Optimal Integral Sliding Mode for Speed Control of Permanent Magnet Synchronous Motor

In this paper, optimal integral sliding mode controller is proposed to control the speed of permanent magnet synchronous motor (PMSM). The conventional sliding mode speed controller and the sliding mode controller with variable switching gain are considered. To increase the robustness of both controllers integral sliding surface is used. Although, these methods can guarantee asymptotic stability and satisfactory performance of the closed-loop system, it suffers from non-optimality and no saturation limit for q-axis reference current. In order to solve the non-optimality problem in the presence of saturation limit for q-axis reference current all the parameters of both controllers are derived via particle swarm optimization (PSO) algorithm in order to minimize an appropriate cost function. Compared with the conventional optimal PI controller, numerical simulations of the proposed schemes show a remarkably better improvement in performance and robustness in the presence of saturation in q-axis current, unknown parametric drifts and unknown load torque.