Resonant converter with less voltage rating of power switches and wide voltage operation

Abstract

A resonant converter with less voltage rating of power switches and wide voltage operation is investigated in this Letter for medium voltage applications. Four active switches and two split capacitors are adopted on the primary side to reduce the voltage rating on power semiconductors. The resonant converter is adopted in the converter to have a wide soft switching operation range. Two flying capacitors are used in the presented circuit to operate as the resonant capacitor and also to achieve voltage balance of two input split capacitors. The variable winding turns are used on the secondary side to overcome the problem of the limited voltage operation in the conventional resonant converter. If the input voltage is in the low-input voltage range, the low turns-ratio of the power transformer is used to increase the voltage gain of the resonant converter. If the input voltage is in a high-voltage range, then the high turns-ratio of the transformer is adopted to reduce the voltage gain. Thus, the proposed converter can achieve wide input voltage operation. Experimental results with a 0.8 kW prototype are provided to confirm the effectiveness of wide input voltage operation from 260 to 800 V.