An improved fixed-time reaching law of disturbance observer-based sliding mode control for surface mounted permanent magnet synchronous motors

This paper proposes an improved fast fixed-time sliding mode control (SMC) with a fixed-time disturbance observer (DoB) for the surface-mounted permanent magnet synchronous motor (SPMSM) control system. The proposed reaching law achieves faster convergence time while guaranteeing system stability without relying on the initial state. Furthermore, a speed controller with a disturbance observer based on the proposed reaching law are designed based on the field oriented control strategy to suppress the load torque of the motor. Lyapunov theorem is utilized to verify the stability of the proposed reaching law and control method. The experimental results show that the proposed control strategy achieves fastest response with the stability time in start-up is about 0.09 s and reduces speed error to 0.8% under load change scenario with the recovery time is about 0.06 s, proving high efficiency, robustness and feasibility of the proposed controller for SPMSM drive structure in practical implementation.