Dc/dc converter, and control method for dc/dc converter

A control method for a DC/DC converter in which the DC/DC converter comprising a main circuit including a switching circuit and a control unit to convert a DC input into high-frequency outputs at a plurality of different voltage levels, wherein the control unit includes the following modes between each of a power level before transition and a power level after transition:

• a first mode that conducts constant-current control to implement a transition period between a power level before transition and a power level after transition;
• a third mode that conducts constant-voltage control to implement a retention period for retaining the power level before transition and the power level after transition;
• and
• a second mode that conducts the constant-voltage control to implement a buffer period to shift from the transition period to the retention period, in which
• an estimated output voltage based on a capacitance current is used as an output voltage to be fed back in the first mode and the second mode,
• a value that makes a second capacitance current command value smaller than a first capacitance current command value is used as a gain A1 of the main circuit in the second mode,
• a value that cancels out a voltage detection value in the third mode is used as a gain A2 of the main circuit in the third mode, and thereby
• the control unit repeats the three modes in sequence to output the high-frequency outputs at the plurality of voltage levels.