Backstepping-Adaptive Resonant Controller for Low-Speed PMSM Operation Considering Periodic and Aperiodic Disturbances

This paper proposes a novel backstepping-adaptive resonant controller (BARC) specifically designed for low-speed permanent-magnet synchronous machines (PMSMs) to mitigate speed fluctuations caused by both periodic and aperiodic disturbances. First, the conventional adaptive resonant controller (ARC) is analyzed for its capability to eliminate periodic disturbances with uncertain frequencies. Given the nonlinear characteristics of the friction torque during low-speed reciprocating operation, a backstepping control method based on the LuGre friction model is employed to further suppress aperiodic disturbances. This method utilizes dual nonlinear observers and adaptive laws to estimate the nonlinear friction and load torque. Simultaneously, these estimated aperiodic disturbances are adapted to the adaptive resonant controller to enhance its robustness. Furthermore, the convergence and stability of the proposed strategy are analyzed by Lyapunov theory, and the influence of parameter variation is evaluated. The effectiveness of the proposed strategy is experimentally validated on a low-speed PMSM drive platform. Experimental results show that the speed fluctuation is reduced by 87% compared to PI controller and both dynamic response and steady accuracy are improved over the conventional ARC.