Abstract: To enhance the performance of the conventional speed control system for permanent magnet synchronous motor （PMSM）
and eliminate the adverse effects of centralized disturbances in the system, a novel sliding mode controller （SMC） for the PMSM speed loop is proposed, which integrates a new fast exponential reaching law with an improved sliding mode torque observer. This controller achieves high-efficiency robust speed regulation while improving the system′s dynamic response and anti-disturbance capability.Specifically, the strategy incorporates a sliding mode surface function into the reaching law coefficients and replaces the traditional signum function with a hyperbolic tangent function. Finally, an integral sliding mode surface is adopted to design the speed loop SMC, leading to a significant improvement in the dynamic performance and stability of the PMSM speed control system. Additionally, the new reaching law is applied to the traditional sliding mode observer to develop an improved sliding mode torque observer, which provides feedforward compensation of disturbance information for the speed loop SMC. Simulation results demonstrate that the proposed control strategy outperforms the traditional sliding mode control in terms of control accuracy, robustness, and dynamic performance, while effectively suppressing the chattering of sliding mode control.

Key words: permanent magnet synchronous motor, integral sliding mode, novel reaching law, sliding mode torque observer,
disturbance compensation