Active Damping of LCT-Filtered PMSM with Phase Correction and Band-Pass Filter-Based Capacitor Current Feedback

A high-order inductor-capacitor-trap (LCT) filter can be used for permanent magnet synchronous motor (PMSM) to reduce high-frequency current harmonics more effectively; however, the inherent resonance characteristics will affect system instability, thus appropriate active damping control is important for the resonance suppression. By introducing two improvements to the traditional CCF (TR-CCF) active damping, this article proposes a novel phase correction and band-pass filter-based capacitor current feedback (PC-BPF-CCF) damping method. First, the original proportional gain is replaced by the BPF, decreasing the targeted resonance peaks without attenuating the low-frequency gain. Second, a second-order lead compensator (SOLC) is cascaded with the BPF to compensate for phase lag, further enhancing resonance suppression and expanding the damping region. The experimental results demonstrate that, the proposed PC-BPF-CCF damping achieves better resonance attenuation with a fast dynamic response, owing to its frequency-selective damping and phase compensation features. Compared to the TR-CCF damping, the proposed BPF-CCF and PC-BPF-CCF damping methods reduce total harmonic distortion (THD) by approximately 8% and 10%, respectively, and improve the dynamic response by more than 20%.