A fractional-order active disturbance rejection control for permanent magnet synchronous motor position servo system

This paper introduces a novel control scheme for the permanent magnet synchronous motor (PMSM) position servo system using a fractional-order active disturbance rejection control (ADRC) approach. Specifically, a first-order ADRC is employed in the current loop, while a fractional-order ADRC is designed for the position loop. In the latter, a linear extended state observer (LESO) is utilized to estimate and compensate for disturbances, while a fractional-order proportional derivative (FO[PD]) feedback controller is employed to enhance the control performance. Moreover, a parameter tuning method is presented based on frequency domain specifications. This technique utilizes the flat phase constraint as a design constraint to ensure that the phase is flat near the gain crossover frequency, thus ensuring that the closed-loop system remains robust to loop gain variations. Simulation and experimental results demonstrate that the proposed fractional-order ADRC control scheme yields improved dynamic response, disturbance rejection, and robustness to loop gain variations.