Passivity Enhancement-Based General Design of Capacitor Current Active Damping for LCL-Type Grid-Tied Inverter

Grid-side current control based on capacitor-current-feedback (CCF) active damping is a common control method for LCL-type grid-tied inverters. The control system should not only ensure inverter stability under complex grid conditions, but also be simple in structure. Therefore, the multiobjective design for the CCF control is proposed to enhance the passivity, while improving the internal stability. First, the passive constraint of CCF control is derived, from which two general control schemes, namely, negative CCF-based phase-lead (N-Lead) control scheme and positive CCF-based phase-lag (P-Lag) control scheme, are proposed. Then, the two schemes are implemented by the design of a first-order phase-lead CCF controller and a first-order phase-lag compensator-based positive CCF controller. Besides, the parameters design is also given for the convenience of engineering application. Finally, the experimental results verify the theoretical analysis and the effectiveness of the proposed design methods.