Passivity-Based Stability of LCL-Type Grid-Connected Inverter via All-Pass Filters

The impedance interaction between the variable grid impedance and the LCL-type inverter leads to resonance of the system. Passivity-based stability design is widely used for grid-connected applications. In this paper, an all-pass filter-based grid current feedback is proposed to reshape the phase response of the control output impedance, which is easy to implement, and simulations verify the effectiveness of the proposed method while ensuring the dynamic performance.