A high efficiency high power density AC-DC converter with holdup time extension capability

This paper proposes a high efficiency high power density AC/DC converter with holdup time extension capability. The proposed AC/DC converter is composed of a proposed two-phase PFC circuit and a ZVS/ZCS current fed isolated converter. During brief interruption of input power, the proposed PFC circuit operates as a boost regulator in order to keep a constant output voltage. Bulk storage capacitors in the PFC circuit are almost discharged in the boost operation. As a result, the storage capacitor volume can be greatly reduced and low-withstandvoltage elements can be used for the rectifier elements in the secondary side of the isolated converter. A bridgeless PFC circuit with the proposed technique is presented as a family circuit. The proposed AC/DC converter is verified by a simulation and an experiment. A 300W/12V AC/DC converter prototype achieves 93% efficiency at full load.