Bridgeless Push-Pull Resonant AC/DC Converter Featuring Balanced Switching Loss Distribution

This article proposes a bridgeless push-pull resonant ac-dc converter featuring naturally balanced switching loss at the primary side. The proposed converter employs a current-fed push-pull structure and two rectifier diodes at the primary side and a series resonance circuit at the secondary side. By incorporating two rectifier diodes, a diode bridge can be removed from the grid side of the proposed converter, and thereby that the number of components and primary-side conduction loss are reduced. One major advantage of the proposed converter is balanced loss distribution over one cycle of grid voltage, which guarantees high power transfer capability with enhanced overall switch utilization. The series-resonant circuit provides zero-current switching turn-OFF at the output diode, thereby reducing the reverse recovery loss. The operating principles and theoretical derivations of the converter are discussed in detail. The validity and performance of the proposed converter are verified using a prototype with 1.65 kW output power.