Patent ID: 8143835

Claim:
A method of driving a chopper-type DC/DC converter including at least one reactor, at least one switching device and three parallel phase arms, each of the three phase arms comprising an upper arm switching device and a lower arm switching device, the method comprising the steps of: setting a target duty ratio; setting a first duty ratio and a second duty ratio based on the target duty ratio; driving said switching device for ON times corresponding respectively to the target duty ratio, the first duty ratio and the second duty ratio; allotting the target duty ratio, the first duty ratio, and the second duty ratio to the three phase arms, respectively; and turning on each of the three phase arms with the duty ratio allotted thereto, wherein one of the duty ratios is the maximum duty ratio and another one of the duty ratios is the minimum duty ratio, and the remaining one of the duty ratios is a ratio between the maximum duty ratio and the minimum duty ratio.