Nominal sliding mode control of PMSM based on friction and disturbance compensation

Considering that the position tracking accuracy of permanent magnet synchronous motor (PMSM) servo systems is easily affected by uncertainties such as friction and load disturbances, this paper proposes a nominal sliding mode control (SMC) with friction and disturbance compensation, which integrates nominal model-based SMC, Lund–Grenoble (LuGre) friction feed-forward compensation and active disturbance rejection control (ADRC) in a novel, coordinated framework, addressing limitations of existing composite control approaches. First, a nominal motor model and a nominal controller are established for the PMSM. The sliding mode controller is designed based on the position tracking error between the nominal motor model and the actual motor model. The nominal controller and the sliding mode controller work in coordination to ensure position tracking accuracy. Second, a LuGre friction model is established, and its dynamic and static parameters are identified. Feed-forward friction compensation control is used to cancel the friction torque. In addition, an active disturbance rejection compensation controller is designed to handle various uncertainties, such as load disturbances, thereby improving the system's robustness and reducing the chattering phenomenon of the sliding mode. Finally, variable-load experiments and parameter sensitivity analysis validate the method's superior dynamic response, low chattering, high precision and robustness.