Parallel soft switching converter with fewer switch counts

A parallel direct current (DC) to DC converter is presented for medium power applications. 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 the current stress of power devices at low-voltage side. Each half-bridge circuit supplies one-third of the total power to the output load. Asymmetric pulse-width modulation is employed to generate the gated signals of the switches and regulate the output voltage. Based on the resonant behaviour of the output capacitance of power switches and the leakage inductance of the transformer, the zero-voltage switching turn-on of power switches can be achieved. Current doubler rectifier topology is adopted at the low-voltage side to have the advantage of low ripple current at output capacitor. A laboratory prototype with 1440 W power is built to verify theory analysis and effectiveness of the studied converter.