Analysis and implementation of a bidirectional converter with high conversion ratio

A bidirectional dc converter with high conversion ratio is presented in this paper to have the capability of bidirectional power flow. Two boost conversion stages are adopted in the converter to achieve high voltage step-up conversion. The other power flow direction can also be achieved in the proposed converter with low voltage step-down conversion. Comparison with the conventional boost converter with narrow turn-off period, the proposed converter has wide conversion ratio so that the higher or lower output voltage can be achieved. To reduce the switching losses and limit the voltage stress on the power switch, the boost type of active snubber is used in the converter. The resonance based on the output capacitance of power switch and resonant inductance at the transition interval will make the power switches to turn on at zero voltage switching (ZVS). The circuit configuration, principle operation, system analysis, and design consideration of the proposed converter are presented. Finally, experiments conducted on a laboratory prototype are presented to verify the effectiveness of the proposed converter.