Soft switching DC/DC converter for high-input voltage and medium-power applications

A new soft switching DC/DC converter for high-input voltage and medium-power applications is presented in this study to achieve zero-voltage switching (ZVS) turn-on for all power switches, implement load current sharing, reduce the voltage stress of switches at Vin/2 and decrease current rating of the rectifier diodes and the output inductors. Three three-level ZVS DC/DC circuits with the same active switches are adopted in order to reduce the current rating of the rectifier diodes and output filter inductors for high-input voltage and high-load current applications. Three centre-tapped rectifiers are connected in parallel at the secondary side such that the current rating of the transformer windings, rectifier diodes and output filter inductors are reduced and have only one diode conduction loss in the forward current path. Phase-shift pulse-width modulation scheme is used to control four power switches and regulate the output voltage. Based on the resonant behaviour by the output capacitance of active switches and the leakage inductance (or external inductance) at the transition interval, power switches are turned on at ZVS. Finally, experiments with 1 kW prototype are provided to verify the effectiveness of the proposed converter.