Active Damping Strategy for Inverter-Side Inductor Voltage Integral Feedback to Suppress DC Offset

Integrating the voltage across the inverter-side inductor for feedback effectively suppresses resonance spikes in LCL-type filters. Due to the low-pass filtering characteristic of integration, it also effectively suppresses high-frequency switching noise, improving the smoothness of the feedback signal. Compared to conventional feedback filter capacitor current measurement, this approach significantly enhances the system's output impedance. However, traditional pure integrators are highly sensitive to DC bias in the input signal, easily leading to integrator saturation. This can compromise resonance suppression effectiveness and even threaten system stability. To address this, this paper proposes an active damping strategy for inverter-side inductor voltage feedback based on a third-order generalized integrator. By incorporating a DC suppression loop into the second-order generalized integrator (SOGI), this strategy achieves ideal integration characteristics at fundamental frequencies while effectively attenuating DC bias and higher harmonics in the input signal. Theoretical analysis and experimental results demonstrate the strategy's superior performance in suppressing resonance and overcoming integration saturation. It significantly enhances system robustness and grid-connected current quality, thereby achieving highly robust active damping control.