Finite-Time Fast Integral Terminal Sliding-Mode Speed Control Method With Disturbance Observer for SPMSM

To enhance the dynamic performance and disturbance rejection of the surface-mounted permanent magnet synchronous motor (PMSM) speed control system, a new sliding-mode controller is proposed in this work. First, a new variable gain reaching law is introduced by incorporating the variable exponential and adaptive terms to reduce the time to reach the equilibrium point and suppress the chattering. Second, a new fast integral terminal sliding-mode surface is designed to improve the convergence speed, both near and away from the equilibrium point. To compensate for internal and external disturbances, an extended sliding-mode disturbance observer is developed. This new framework improves both the dynamic and steady-state performances of the system, with stability guaranteed through the Lyapunov theory. Finally, experimental results confirm that the proposed method enhances the speed response, tracking accuracy, and disturbance rejection capability in PMSM control.