An Improved Super-Twisting Sliding Mode Single-Loop Control With Current-Constraint for PMSM Based on Two-Time Scale Disturbance Observer

In this article, an improved super-twisting (ST) sliding mode control (ISTSMC) strategy is proposed for permanent magnet synchronous motors (PMSMs) with the consideration of parameter uncertainties and external load disturbances. First, to achieve precise speed tracking and current protection, the motor drive model is transformed into an error system considering
${q}$
-axis current-constraint. Then, a single-loop speed controller based on ISTSMC with the terminal term is designed, which has a simple structure, and the direct speed control of PMSMs is realized. Moreover, to ensure the robustness of the proposed control strategy, a time-varying two-time scale disturbance observer (TV-TTSDO) is designed to estimate the lumped disturbances which include the matched and mismatched disturbances, and they are carried out to provide compensation for the proposed controller. In addition, the proposed observer is easy to complete and it can eliminate the estimated peaks at the initial time. Subsequently, the convergence time is calculated, and the stability of the control system is analyzed and proved by the Lyapunov theory. Finally, the experimental verifications are completed, and the results confirm the effectiveness and advantages of the proposed control strategy, such as smaller overshoot, faster transient response, and stronger robustness under different operating conditions.