Isolated double step-down DC-DC converter

An isolated double step-down converter with high efficiency and high step-down function is proposed in this paper. Proposed converter employs one additional capacitor in the primary side. As compared to the conventional full-bridge converter, proposed circuit has double step-down feature with reduced voltage stress at the primary side of transformer. Moreover, voltage stress of three primary side switches is half of input voltage, and one is same as input voltage. Compared with conventional full-bridge converter it achieves high efficiency by improved ZVS range under the light-load condition. In addition to these, transformer saturation problem is automatically solved by additional capacitor and no additional circuit or control scheme is required to address this situation. A 1 kW experimental prototype is constructed to verify performance of the proposed converter.