Zero-voltage switching DC/DC converter with two half-bridge legs and series-parallel transformers

A new zero-voltage switching (ZVS) converter with the series half-bridge legs for high DC bus application is presented. Two circuit modules with the interleaved pulse-width modulation are adopted to share the load current. In each circuit module, a series resonant converter with two transformers that are series-connected in primary side and parallel-connected in secondary side is used to achieve load current sharing and reduce the current stresses of rectified diodes and transformer secondary windings. Based on the series resonant behaviour, power metal-oxide semiconductor field-effect transistors (MOSFETs) are turned on at ZVS and rectifier diodes can be turned off at zero current switching. Therefore the switching losses of power semiconductors are reduced. Two half-bridge legs and two split capacitors are connected in series such that the voltage stress of each active switch is clamped to one-half of DC bus voltage. Thus, the low voltage stress of MOSFETs can be used in high DC bus application. The principle of operation, steady-state analysis and design consideration of the proposed converter are provided and discussed. Experiments with a laboratory prototype with 24 V/40 A output are provided to verify the effectiveness of the proposed converter.