Parallel soft switching converters: Analysis, design and implementation

This paper studies a parallel soft switching converter with less switch counts for medium power application. The studied converter includes three half-bridge circuits with sharing two power switches at high voltage side to reduce switch counts. Three half-bridge circuits are connected by primary-parallel and secondary-parallel to reduce current stress of power devices at low voltage side. Each half-bridge circuit supplies one-third of total power to output load. Asymmetric pulse-width modulation is employed to generate the gated signals of the switches and regulate output voltage. Based on the resonant behavior by the output capacitance of power switches and the leakage inductance of transformer, the zero-voltage switching turn-on of power switches can be achieved. Current doubler rectifier topology is adopted at low voltage side to have the advantage of low ripple current at output capacitor. A laboratory prototype with 1440W rated power is constructed and experiments are provided to verify the theory analysis and demonstrate the effectiveness of the studied converter.