Power conversion device and power supply system using same

A power conversion device comprising:

• a first low voltage side circuit and a first high voltage side circuit which are connected via a first transformer;
• a second low voltage side circuit and a second high voltage side circuit which are connected via a second transformer;
• and
• a control circuit configured to:
• control switching timings of the first high voltage side circuit and the second high voltage side circuit such that a current difference of an input current to the first low voltage side circuit and an input current to the second low voltage side circuit during a step-up operation is reduced and becomes smaller than a predetermined value to balance the input currents, and
• control the first high voltage side circuit and the second high voltage side circuit during the step-up operation such that a period for electrically short-circuiting both terminals of any one transformer of the first transformer and the second transformer at the switching timing of the first high voltage side circuit or the second high voltage side circuit is provided.