A Variable Structure ADRC for Enhanced Disturbance Rejection and Improved Noise Suppression of PMSM Speed System

It is well-known that there is a trade-off between robustness to disturbances and measurement noise sensitivity in the active disturbance rejection control (ADRC) framework based on extended state observer (ESO). To this end, this article proposes a novel variable structure ADRC (VSADRC) for permanent magnet synchronous motor (PMSM) speed control to enhance the disturbance rejection and the noise suppression simultaneously. In this technology, a variable structure ESO (VSESO) with two-stage interconnected observer is proposed to avoid directly employing noise-contaminated signal, in which the extended disturbance differential is appended to achieve higher-level disturbance estimation. By doing this, at low frequencies, the magnitude curve slope is 40 dB/dec for the VSESO and 20 dB/dec for ESO, while at high frequencies, it is $-$40 dB/dec for the VSESO and $-$20 dB/dec for ESO. Furthermore, the stability and output characteristics of the proposed strategy are comprehensively investigated. It is revealed that the superiority of the studied scheme in disturbance rejection and noise suppression. Finally, the experimental results verify the feasibility and effectiveness of the proposed VSADRC.