Sensorless Control of PMSM Based on Improved Adaptive Super-Twisting Sliding Mode Observer and IST-SMC

In view of the low accuracy and chattering problem of the traditional sliding mode observer of permanent magnet synchronous motor (PMSM), an improved adaptive super-twisting sliding mode observer (IAST-SMO) is proposed. Its variable gain sliding mode observer is designed to adaptive control, in which the gain varies with the estimated speed. In addition, to suppress the chattering problem of sliding mode controller, a new softsign function is designed to replace the conventional sign function in switching function. And for purpose of avoiding the overshoot problem, the introduction of improved super-twisting sliding mode controller (IST-SMC) further optimizes motor speed regulation in speed loop, significantly improving the robustness of the control system. Simulation results show that the novel observer and sliding mode controller have advantages of quick response, small chattering and curb overshoot. It can realize accurate observation of motor speed and position information.