Active Damping for LC-Filtered PMSM Based on Low-Pass Filter Capacitor Current Feedback and Extended State Observer

Active damping is critical to suppress resonance for LC-filtered permanent magnet synchronous motor (PMSM), and capacitor current feedback (CCF) is commonly used due to the simple implementation and good damping effect. However, the slow response and extra sensors are the shortages of the original CCF damping. This article proposes a novel CCF damping control scheme to significantly enhance both damping effect and dynamic response without additional sensors, in which two improvements are presented. One is the introduction of a negative coefficient low-pass filter (LPF) in parallel with the traditional CCF (TR-CCF) loop, which can reduce the low-frequency gain while ensure medium- and high-frequency gains of the CCF loop, thus decreasing the resonance peak while improving the open-loop cutoff frequency. The other is the proposed current reconstruction with extended state observer (ESO), which can estimate motor-side currents and filter capacitor currents with simple design and high accuracy, hence realizing the LPF-CCF active damping independent of additional sensors. The stability, accuracy, robustness, and steady-state and dynamic performance of the proposed damping scheme are analyzed. The experimental results about a 1.1-kW PMSM are provided to verify the effectiveness of the proposed ESO-LPF-CCF scheme.