Power conversion apparatus

A power conversion apparatus comprising:

• a transformer that includes a primary winding and a secondary winding, which is magnetically coupled with the primary winding;
• an inverter circuit that converts a direct current voltage supplied from a direct current power supply into an alternating current voltage and that supplies the alternating current voltage to the primary winding;
• a connector that includes a first end and a second end electrically connectable to at least either a commercial power system or a load;
• a first switching device inserted between the first end of the connector and a first end of the secondary winding;
• a second switching device inserted between the second end of the connector and the first end of the secondary winding;
• a third switching device inserted between the first end of the connector and a second end of the secondary winding;
• a fourth switching device inserted between the second end of the connector and the second end of the secondary winding;
• and
• a control unit that controls an amplitude of at least either an output voltage or an output current of the connector,
• wherein the control unit turns on at least either the first switching device or the fourth switching device at a first on time in a first period, in which a voltage of the secondary winding is positive,
• wherein the control unit turns on at least either the second switching device or the third switching device at a second on time in a second period, in which the voltage of the secondary winding is negative, after the first period, and
• wherein the control unit controls the amplitude of at least either the output voltage or the output current by shifting at least either the first on time or the second on time.