Stability Analysis and Key Parameters Design for Grid-Connected Current-Source Inverter With Capacitor-Voltage Feedback Active Damping

In a three-phase grid-connected current-source inverter system with the capacitor-voltage feedback (CVF)-based active damping method, a high-pass filter is usually employed in the CVF loop to mitigate its impact on system dynamics. Meanwhile, the inherent delays in a digital control system brought by pulsewidth modulation (PWM) and the digital control will make stability analysis and parameters design of the control system more complicated. In this article, the impacts of the high-pass filter and the inherent delays are considered for stability analysis and parameters design. The impacts of the cutoff frequency of the high-pass filter and the CVF damping coefficient on the system stability are analyzed in the discrete domain, and an optimal CVF damping coefficient is obtained. Moreover, a key parameters design method for the control system is proposed. The method simplifies the procedure of key parameters designing, which can mitigate the resonance of the system caused by the CL filter effectively with better dynamics and steady state performance. Finally, simulation and experimental results are provided to verify the effectiveness of the proposed method in this article.