Power conversion apparatus having a switching circuit unit that includes a switching device and an auxiliary switching device

A power conversion apparatus comprising:

• a transformer that includes a primary winding and a secondary winding, the secondary winding being 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 is electrically connected to at least one of a commercial power system and a load;
• a switching circuit unit that includes a switching device connected to the secondary winding and the connector;
• an inductor inserted between the secondary winding and the switching device;
• and
• an auxiliary switching device inserted between the secondary winding and the switching device, in parallel to the inductor, wherein
• an amplitude of at least one of an output voltage and an output current of the connector is controlled by a control of turning on or off the switching device,
• the auxiliary switching device is in an off state, in a power supply mode in which the output voltage and the output current of the connector have the same polarity, and
• the auxiliary switching device is in an on state, in a power regeneration mode in which the output voltage and the output current of the connector have different polarities.