Passivity Design for LCL-Type Grid-Tied Inverter Based on The Constraint of Realizing Passivity by Capacitor Current Control

The frequency-domain passivity theory offers an effective way to access the stability of the inverter connecting to complex grid conditions. The inverter with passivity in the entire frequency range can connect to the grid regardless of grid impedance, indicating a plug-and-play performance. To realize passivity for the grid-side current controlled LCL-type grid-connected inverter, this article firstly derives the constraints of realizing passivity by the capacitor-current-feedback (CCF) active damping, which shows that the inverter passivity depends on the damping characteristics of CCF control. On this basis, the passivity of the inverter with different CCF control methods is analyzed and designed, which shows that the first-order phase lead compensator-based and second-order phase lead compensator-based CCF control can provide enough passivity margin so that the inverter can cope with wide parameters variation. Finally, the correctness of the theoretical analysis and the effectiveness of the design results are verified by experiments.