A novel soft-switching and low-conduction-loss bidirectional DC-DC converter

A novel soft-switching and low-conduction-loss bidirectional DC-DC converter is proposed. Designed for low-output voltage applications, the converter has a full-bridge circuit on the primary side and a current-fed push-pull circuit on the secondary side. The flow of current is controlled by phase-shift pulse-width modulation. By adding an active-clamp circuitry on the secondary side and using suitable gate drives, not only the converter can achieve zero-voltage-switching (ZVS), but also the circulating current is eliminated and the conduction loss is reduced. All switches including auxiliary switches in the converter have ZVS characteristics in both charging mode and discharging mode. The proposed converter employs a saturable inductor and simple external passive-commutation circuit, which makes ZVS possible for almost entire load range. Design considerations and experimental results are presented