Dc-dc converter

A DC-DC converter comprising:

• a first full-bridge circuit including four switching elements that include a capacitor serving as a parasitic capacitance or an external parallel-connected capacitor;
• a second full-bridge circuit including four switching elements that include a capacitor serving as a parasitic capacitance or an external parallel-connected capacitor;
• a transformer including a first winding and a second winding, the first winding being connected to said first full-bridge circuit, and the second winding being connected to said second full-bridge circuit and magnetically coupled to said first winding;
• an inductance component connected in series with said first winding or said second winding;
• and
• a control circuit that controls soft switching of each switching element in each of said first full-bridge circuit and said second full-bridge circuit,
• wherein an inductor current flowing through an equivalent inductor at a time of switching of turning on or off each switching element is greater than or equal to a threshold current, the equivalent inductor being equivalent to said transformer and said inductance component, and
• when said first full-bridge circuit and said second full-bridge circuit have different output voltages, said control circuit causes said inductor current at a start time of a polarity inversion period to approach said inductor current at an end time of said polarity inversion period, the polarity inversion period being a period in which an output of said first full-bridge circuit and an output of said second full-bridge circuit have reverse polarities.