Power conversion device and control method thereof

A power conversion device, comprising:

• a main circuit unit configured to perform a step-up operation or a step-down operation;
• and
• a controller configured to control an operation of the main circuit unit, wherein
• the main circuit unit includes
• a first switch and a second switch connected in series between a first node and a second node,
• an inductor connected between a third node and a connection node of the first and second switches, and
• a current detector configured to detect whether a current flowing in the inductor is positive or negative,
• the controller is configured to
• define one of the first and second switches as a synchronous rectification switch, define the other one of the first and second switches as a control switch, and define a positive direction of an inductor current,
• perform, in each switching cycle, an operation of turning the control switch on and afterward off while the synchronous rectification switch is off, and then turning the synchronous rectification switch on and afterward off while the control switch is off,
• obtain, in a first switching cycle, a detection result from the current detector at a detection timing backed by a predetermined period from a timing at which the synchronous rectification switch switches from on to off, and
• correct, based on whether the inductor current is positive or negative indicated by the detection result, an on-period of the synchronous rectification switch in a second switching cycle after the first switching cycle.