A Variable Rate Super-Twisting Sliding Mode Speed Control with Overcurrent Protection for PMSM Considering Aperiodic and Periodic Disturbances

Aiming at improving the speed regulation performance of permanent magnet synchronous motor (PMSM) under aperiodic and periodic disturbances, a variable rate supertwisting (VRST) sliding mode control strategy based on a novel disturbance observer (NDO) is proposed in this paper considering overcurrent protection. Firstly, the model of PMSM considering aperiodic disturbances and periodic harmonic disturbances is established. Secondly, to enhance the anti-disturbance performance and the control accuracy, a NDO is designed to estimate periodic harmonic disturbances and aperiodic disturbances, such as load torque, parameter uncertainties. Furthermore, the variable rate nonlinear term is introduced into the super-twisting sliding mode control algorithm, and a VRST sliding mode single-loop speed controller is proposed to improve the transient performance. Meanwhile, an improved q-axis current penalty function is designed to avoid excessive current, which can effectively balance dynamic performance and overcurrent protection. Subsequently, based on the Lyapunov theory, the stability of the control system is analyzed. Finally, the superiority and effectiveness of the proposed control scheme are verified through a series of comparative experiments