Adaptive Periodic Disturbance Observer Based on Fuzzy Logic Compensation for Speed Fluctuation Suppression of PMSM under Periodic Loads

The permanent magnet synchronous motor (PMSM) in a single-rotor compressor suffers from speed fluctuations during operation as a result of periodic extreme load disturbances, which leads to serious noise and vibration issues. In this paper, a rotor position-based periodic disturbance observer (PDOB) combined with fuzzy logic controllers (FLC) is proposed to improve system anti-interference capability. Firstly, the first-order PDOB is constructed to extract the load disturbance with periodic characteristics. The impacts of the PDOB parameter are analyzed to provide guidance for parameter design. Furthermore, a rotor position-based PDOB is proposed to avoid notch frequency shifts due to fractional delay effects in the time domain. Since low-pass filters (LPF) in the system induce the phase shift and amplitude decay of the compensated current, the FLCs are designed to adjust the phase and amplitude based on the speed fluctuation and its difference. The validity of the proposed schemes is verified with both simulation and experimental results.