Fractional-order Feedback Control Method for PMLSMs Based on Closed-loop Identification Model

In order to improve the tracking accuracy of PMLSMs, a fractional-order feedback control method was proposed based on closed-loop identification model. By precisely adjusting the error amplitude characteristics of the feedback control system in a specific fractional-order form, the following errors of PMLSMs might be effectively suppressed. A closed-loop identification model was derived for the PMLSM and the parameter selection method of the fractional-order lead-lag compensator was determined based on analysis of the error amplitude characteristics. With the properly defined fractional-order parameters, the fractional-order feedback control system might accurately describe the frequency-domain characteristics of the PMLSM, and the identification accuracy and control performance of the PMLSM might thus be improved. The proposed method was experimentally validated on a PMLSM gantry motion platform through identification methods, tracking experiments with different motion planning, and circular trajectory motion experiments. The experiments on system closed-loop identification and motion tracking with different plannings were performed. The experimental results show that the closed-loop identification method may effectively suppress the influences of external interferences on the identification signals, and the closed-loop identification model is accurate for the control system, the proposed fractional-order feedback control method may greatly reduce the tracking errors of the PMLSMs, and compared to the PID control method, the proposed control method may reduce the root mean square error (RMSE) tracking errors by at least 82.47% under different motion scenarios. The experimental results demonstrate the effectiveness of the proposed method in improving the tracking accuracy of PMLSMs. © 2023 China Mechanical Engineering Magazine Office. All rights reserved.