Fully soft-switched bidirectional resonant dc-dc converter with a new CLLC tank

A bidirectional dc-dc converter with a new CLLC type resonant tank, which features in ZVS for the input inverting port switches and ZCS for the output rectifier port switches, regardless of the direction of the power flow, is proposed. If the MOSFETs are implemented as all of the main switches, the proposed converter has a minimized switching loss. The detail operation principles, as well as the design considerations, are presented. A prototype, which interfacing the 400 V/48 V DC buses for the UPS system with a power rating of 500 VA, whose highest conversion efficiencies for the bidirectional mode both exceed 96%, was developed to verify the validity and applicability of this proposed converter.