Power conversion device

Abstract

A control unit (50) performs phase difference control for controlling a primary-side full-bridge circuit (30) and a secondary-side full-bridge circuit (40) so as to obtain a combination of a first phase difference and a second phase difference that can output a required power and satisfy a condition 1 and a condition 2 in at least one of a light load mode and a heavy load mode. The control unit (50) performs frequency control for controlling the primary-side full-bridge circuit (30) and the secondary-side full-bridge circuit (40) so as to be able to output the required power and obtain the frequencies of a two-level voltage and a three-level voltage that satisfy the condition 1 and the condition 2. The control unit (50) switches the phase difference control to the frequency control in accordance with a primary-side condition current value, a secondary-side condition current value, or an output power. The control unit (50) switches the frequency control to the phase difference control in accordance with the primary-side condition current value, the secondary-side condition current value, the output power, or the frequency.