Model-free Recursive Nonsingular Terminal Sliding Mode Control of PMSM Speed Loop Based on Fractional-order Extended Sliding Mode Disturbance Observer

Aiming at the problems of parameter changes and external load disturbances in the speed loop of permanent magnet synchronous motors, a novel model-free recursive nonsingular terminal sliding mode control (MFRNTSMC) method for the speed loop based on the fractional order extended sliding mode disturbance observer is proposed in this study to improve the response speed and anti-disturbance capability of a speed control system. First, a novel ultra-local model of a permanent magnet synchronous motor based on the traditional mathematical model is developed. Second, a model-free recursive nonsingular terminal sliding mode controller located in the speed loop is designed by combining the novel ultra-local model and the recursive nonsingular terminal sliding mode control theory; a fractional order extended sliding mode disturbance observer is designed, which not only accurately compensates the unknown portion of the system but also improves the anti-disturbance ability of the speed loop controller. Finally, the superiority of the proposed sliding mode control method is verified by comparing simulation and experiment results.