Enhanced sliding mode speed control for PMSM integrating novel composite reaching law and sliding mode disturbance observer

To enhance the response speed and robustness of permanent magnet synchronous motors (PMSMs), this paper proposes a compound control strategy based on a bounded adaptive novel composite sliding mode reaching law (NCSMRL). Firstly, the proposed NCSMRL incorporates the arcsine function, enabling the control gain to adaptively adjust with the system states and sliding surface while inherently retaining a saturation upper bound. This design not only enables fast convergence but also mitigates, to a certain extent, the risk of system instability induced by excessive gain in traditional sliding mode control (SMC). Secondly, the traditional single switching term is decomposed into two independently regulated components, which respectively, respond to variations in state variables and the sliding surface. When the system is far from the sliding surface, this configuration enables rapid convergence; when it approaches the sliding surface, chattering suppression is achieved—thus effectively balancing dynamic response speed and steady-state performance. Furthermore, a sliding mode disturbance observer (SMDO) is integrated to form a composite controller. By performing real-time estimation of load disturbance and implementing feedforward compensation, the robustness of system against parameter perturbation and external disturbance is enhanced. Simulation and experimental results validate the effectiveness of the proposed method.