Dc-dc converter and control method

A control method executed by a DC-DC converter of an isolated type, the DC-DC converter including:

• a first switch that is provided on a first path connecting an input terminal and a ground terminal;
• a second switch that is provided on the first path and connected in series with the first switch;
• a third switch that is provided on a second path connecting the input terminal and the ground terminal, the second path being different from the first path;
• a fourth switch that is provided on the second path and connected in series with the third switch;
• a transformer that includes a primary winding connected between a first node and a second node, the first node being located between the first switch and the second switch on the first path, the second node being located between the third switch and the fourth switch on the second path;
• and
• a rectifier circuit that is connected to a secondary winding of the transformer,
• the control method comprising:
• controlling switching of the first switch, the second switch, the third switch, and the fourth switch to cause an effective value of a current flowing through at least one switch among switches to be larger than an effective value of a current flowing through any of the switches other than the at least one switch, the switches being the first switch, the second switch, the third switch, and the fourth switch,
• wherein one of the following is satisfied:
• on-resistance of the at least one switch is lower than on-resistance of any of the switches other than the at least one switch;
• cooling performance of a cooling structure of the at least one switch is higher than cooling performance of a cooling structure of any of the switches other than the at least one switch;
• or
• heat resistance of the at least one switch is higher than heat resistance of any of the switches other than the at least one switch.