A Novel Single-Phase Common-Ground Rectifier With Active Power Decoupling for DC Microgrids

To suppress the leakage current in non-isolated rectifiers and reduce DC-link capacitance, this paper proposes a novel single-phase common-ground rectifier with active power decoupling as the interface between an AC power supply system and a DC load. Leakage current is minimized by connecting the ground on the AC side to the negative terminal on the DC side. By transferring dual-frequency power fluctuations to decoupling capacitors without any additional switches, the DC-link capacitance is significantly reduced, thereby decreasing the size of the rectifier. The topology derivation and the operating principle is described, the voltage across the semiconductors and decoupling capacitor, state space model and constraint are analyzed respectively. The mathematical model of the proposed rectifier is built and a voltage-current dual closed-loop controller is designed to regulate the output DC voltage. The passive component parameters are also designed. The principle and performance of the proposed rectifier are demonstrated through static and dynamic experiments. A comparison with other step up and step-down rectifiers is discussed, which reveals that the proposed rectifier offers better performance in terms of higher efficiency and lower DC-side capacitance.