Cascade Terminal Sliding Mode Control for PMSM with Nonlinear Disturbance Observer

This paper investigates speed and current tracking control for permanent magnet synchronous motor (PMSM) based on terminal sliding mode control (TSMC) with nonlinear disturbance observer (NDOB). First, terminal sliding mode controllers with exponential reaching law are designed for both current loop and speed loop. The controller can achieve the current and speed error convergence in finite time, which can realize fast transient response. Meanwhile, nonlinear disturbance observers are implemented to reduce large chattering phenomenon caused by high switching gains of sliding mode control. The composite controller may take a smaller switching gain without sacrificing disturbance rejection performance. Simulation results show that the proposed method has excellent speed and current tracking performance and strong robustness.