Repetitive Fractional-Order Active Disturbance Rejection Control for Permanent Magnet Synchronous Motor

In order to reduce the impact of various disturbances on the permanent magnet synchronous motor (PMSM) system especially during low-speed (0–300 rpm), this paper proposes a novel repetitive fractional-order active disturbance rejection control (RFO-ADRC) method. It combines repetitive control and fractional-order active disturbance rejection control (FO-ADRC) innovatively in an cascaded structure. Repetitive compensation is employed to handle the periodic disturbances arising from the structural characteristics of PMSM. FO-ADRC is employed to compensate for the residual aggregated disturbances. It novely replaces the nonlinear error feedback control (NLSEF) link in active disturbance rejection control (ADRC) with fractional-order control, and then incoportes an improved smooth function into the extended state observer (ESO), effectively reducing parameter adjustment complexity and mitigating inherent chattering. Finally, the proposed RFO-ADRC is validated on a 1.5 kW PMSM experimental platform and compared with PI, ADRC, and FO-ADRC. Experimental results show that RFO-ADRC achieves a start-up time of 0.36 s fastest, zero overshoot, a steady-state speed error within ±2.27 r/min lowest, a total harmonic distortion (THD) of 6.47% lowest, and a recovery time of 0.22 s under sudden load changes fastest, demonstrating superior performance.