Half-bridge integrated ZVS three-level DC-DC converter with Wide ZVS range and Reduced Circulting current

A half-bridge (HB) integrated three-level (TL) DC-DC converter, which has wide range of zero-voltage switching (ZVS) and reduced filter size, is proposed in this paper. Both TL converter and HB converter have transformer of their own, and they share the lagging-leg switches together. By using the current of the magnetizing inductor of the HB converter, the proposed converter extends its soft-switching range that its lagging-leg switches can achieve ZVS even at light loads. In addition, a blocking capacitor is combined to reduce the circulating current in the primary side of the TL converter. To suit for the high voltage output application, full-bridge rectifier, which has lower voltage stress of the rectifier diodes, is used in the secondary side. The characteristics of the proposed converter are analyzed in this paper and its performance is verified by an experimental prototype with 600V input and 250V-420V/3A output.