Patent ID: 8797774

Claim:
A manufacturing method for a plurality of chopper circuits, each chopper circuit using soft switching operation in which the timing of switching of an auxiliary switching element is controlled to thereby control a voltage applied to a main switching element at the time of switching of the main switching element, the manufacturing method comprising: identifying devices that constitute each of the chopper circuits and that are relevant to determining time at which the voltage applied to the main switching element during operation of the chopper circuit takes a minimum value; calculating a design representative value of an observed device that is at least one of the identified devices 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 of the observed devices are subjected to statistical processing; manufacturing the plurality of chopper circuits using the plurality of the observed devices; and setting the representative value, instead of the rated value of the electrical characteristic of the observed device, in a switching control unit in each of the chopper circuits, which controls the timing of switching of the main switching element and the timing of switching of the auxiliary switching element on the basis of the electrical characteristics of the identified devices.