Fast Smooth Super-Twisting SMC and Super-Twisting Disturbance Estimation for PMSM Speed Control

This paper presents a novel control framework for permanent magnet synchronous motor drives that combines a fast smooth super-twisting sliding mode control strategy with a finite-time super-twisting disturbance observer. This approach addresses the challenges posed by parameter variations, nonlinear friction, and external disturbances. First, an accurate dynamic model of the PMSM is developed by incorporating the uncertainties and nonlinearities commonly encountered in practical systems. Subsequently, the observer is employed to estimate and compensate for lumped disturbances in real time, thereby enhancing the robustness of the system. Based on this estimation, a continuous control law is designed to ensure high-precision speed tracking while effectively suppressing chattering, which is an inherent issue in conventional sliding mode control. The finite-time convergence and stability of the proposed scheme are rigorously established via Lyapunov analysis. To validate its performance, the FSSTSMC is compared with two existing controllers: the classical sliding mode controller and the continuous fixed-time super-twisting sliding mode controller. Both simulation and experimental results demonstrate that the proposed method achieves a superior transient response, improved steady-state accuracy, and stronger robustness against parametric uncertainties and load disturbances, making it highly suitable for high-performance PMSM drive applications in consumer electronics and industrial systems.