Aiming at the problems of parameter perturbation, external disturbance and poor robustness in permanent magnet synchronous motor (PMSM) speed regulation systems, this paper proposes a predefined-time model-free sliding mode control strategy combined with a predefined-time disturbance observer. Based on the ultra-local model, a predefined-time sliding mode surface and reaching law are designed to realize fast convergence independent of initial values. The observer accurately estimates lumped disturbances in real time for feedforward compensation. The analysis of Lyapunov stability has given a proof that convergence in predefined time is achieved. Both the simulation results and the hardware-in-the-loop experiment results have proven that the method put forward by us obviously decreases overshoot and settling time, strengthens the ability to reject disturbance, and thus has better performance than the traditional PI control in terms of dynamic response and robustness.
