Enhanced composite adaptive sliding mode reaching law for speed regulation in SPMSM

This paper presents an enhanced composite adaptive sliding mode reaching law (ECASMRL) for improving the dynamic speed accuracy of a surface-mounted permanent magnet synchronous motor (SPMSM) control system based on sliding mode control and disturbance compensation techniques. The key characteristics of ECASMRL is that it reduces the time required for the system trajectory to reach the sliding surface faster than the existing reaching law while effectively reducing chattering and providing notable performance. Moreover, an extended sliding-mode disturbance observer is utilized to estimate the unknown external disturbances and provide feedforward compensation to the SPMSM control system, reducing the additional chattering induced by the lumped disturbances and enhancing disturbance rejection capabilities. The stability of the proposed method is validated through the Lyapunov theory. Simulation results and comparisons with other approaches demonstrate the superior performance of the proposed reaching law. • ECASMRL is proposed to overcome the inherent trade-off between chattering attenuation and rapid system response in SMC by adjusting the control gains. It guarantees finite-time convergence, accurately calculates and defines the convergence time, and includes a comparison with existing approaches. • An ESMDO was employed to estimate and compensate for lumped disturbances in real time. The proposed ECASMRL with ESMDO-based speed controller enhances the robustness and control accuracy of the SPMSM system while improving chattering attenuation capabilities without requiring high control gains. • The performance of the proposed control method was validated through simulations under various speed and disturbance conditions, demonstrating robust anti-disturbance rejection capabilities against uncertain load torque and dynamic performance.