Active damping control strategy for grid-connected inverters by splitting the capacitor of LCL filter

Among the existing current control methods of LCL grid-connected inverter, the split-capacitor method divides the capacitor of LCL-filter into two parts, which can degrade the system from third-order to first-order through the feedback of the current between the two capacitor branches. However, the cancelled poles in the deflation progress of the splitting capacitor method are critical steady poles. This characteristic makes the whole close-loop system incompletely controllable because the signal component at resonant frequency is not included in the current feedback. Active damping control strategy is an effective way to attenuate the resonant peak and to improve the waveform of output current. Finally, simulation results indicate the correctness of the theoretical analysis and the proposed control method.