Novel DC to Single-Phase Isolated AC Converter Using Coupled Inductor with Power Decoupling Capability

This paper proposes a novel active power decoupling converter topology, where additional components are not necessary in order to minimize the power decoupling circuit. In conventional EV/PHV battery charger systems with the power decoupling capability require several passive components and switching devices in order to absorb the power ripple at twice grid frequency. Thus, these topologies restrict the downsizing. In order to avoid the additional components for the power decoupling capability, this paper proposes the isolated DC to single-phase AC converter with an employment of a coupled inductor. This converter consists of a full-bridge inverter, a high frequency transformer and an indirect matrix converter in order to eliminate DC-link smoothing capacitors. Moreover, the additional inductor for the power decoupling circuit in the conventional topology can be substituted with leakage inductor of the coupled inductor in the proposed converter. In the proposed circuit, the coupled inductor is an isolation between the DC and the AC equipment for safety and the boost inductance. These characteristics result in a high-power-density converter. The validity of the proposed circuit is experimentally confirmed by a simulation and experiment at prototype. As a simulation result, the proposed method reduces the second-order harmonic of the power ripple by 97.5% at 3-kW of the output power. As experimental results, the proposed converter reduces the DC current ripple generated by a single-phase AC load by 46.5%.