Discontinuous-current mode operation of a semi-dual-bridge resonant converter

A semi-dual-bridge resonant converter derived from the popular dual-bridge resonant converter (DBRC) topology is proposed in this paper for applications requiring only unidirectional power flow such as various types of DC power supplies, battery chargers in electric vehicles and dc-dc stage of different types of photovoltaic inverters. Based on the similarity of topology to the DBRC converter, the new converter is expected to inherit most advantages from the DBRC converter - such as soft-switching, high power density and simple control. Besides, the proposed converter has a simpler structure with lower cost and the high circulation energy in output bridge is eliminated. The operating principles and waveforms in discontinuous-current mode (DCM) are presented in detail. It can be shown that all switches can be turned off softly at zero current. Steady-state analysis of the converter in DCM is performed using differential equation (DE) approach. A design example based on the analysis results is presented and then verified through simulation and experiment.