Manufacturing method for chopper circuit, chopper circuit, DC/DC converter, fuel cell system, and control method

A DC/DC converter comprising:

• a DC input unit that is connected to a direct-current power supply;
• a chopper circuit that converts a voltage of a direct-current power input from the DC input unit, that includes a main switching element and an auxiliary switching element, and that uses soft switching operation in which the timing of switching of the auxiliary switching element is controlled to thereby control a voltage applied to the main switching element at the time of switching of the main switching element;
• a DC output unit that outputs the direct-current voltage of which a voltage is converted by the chopper circuit;
• and
• a switching control unit that is configured to control the timing of switching of the main switching element and the timing of switching of the auxiliary switching element using a design representative value of an observed device that is at least one of specific devices that constitute the chopper circuit and that are relevant to determining time at which the voltage applied to the main switching element takes a minimum value, wherein the representative value is calculated in such a manner that a plurality of the observed devices are prepared and then variations from a rated value in electrical characteristic of each observed device are subjected to statistical processing.

A fuel cell system comprising:

• a fuel cell that supplies electric power to a load;
• a DC/DC converter that uses a chopper circuit having a main switching element and an auxiliary switching element to control a voltage of the electric power, wherein the chopper circuit uses soft switching operation in which the timing of switching of the auxiliary switching element is controlled to thereby control a voltage applied to the main switching element at the time of switching of the main switching element;
• and
• a switching control unit that is configured to control the timing of switching of the main switching element and the timing of switching of the auxiliary switching element using a design representative value of an observed device that is at least one of specific devices that constitute the chopper circuit and that are relevant to determining time at which the voltage applied to the main switching element takes a minimum value, wherein the representative value is calculated in such a manner that a plurality of the observed devices are prepared and then variations from a rated value in electrical characteristic of each observed device are subjected to statistical processing.