Operation principles of bi-directional full-bridge DC/DC converter with unified soft-switching scheme and soft-starting capability

A new bi-directional dual full-bridge DC/DC converter with a unified soft-switching scheme and soft-start capability is proposed in this paper. A simple voltage clamp branch is used to limit transient voltage across the current-fed bridge and realize zero-voltage-switching (ZVS) in boost mode operation, while achieving hybrid zero-voltage/zero-current switching (ZVZCS) for the voltage-fed bridge in buck mode operation. The theory of operations including soft-start-up process is discussed in this paper.