POWER SUPPLY UNIT AND METHOD FOR BACKFEED PROTECTION THEREOF

摘要

This power supply unit is provided with: an alternating current circuit extending from an input terminal to an output terminal; a first voltage sensor that detects an input voltage at the input terminal; a second voltage sensor that detects an output voltage at the output terminal; a bidirectional inverter connected to the alternating current circuit; a storage battery connected to the alternating current circuit via the bidirectional inverter; an AC switch disposed between the input terminal and a point of contact of the bidirectional inverter with the alternating current circuit; and a control unit that controls the bidirectional inverter and the AC switch, and determines that the AC switch is malfunctioning and stops the bidirectional inverter if, while the AC switch is controlled to be open, passage of an electric current through the AC switch is detected on the basis of the operating state of the bidirectional inverter, the input voltage, and the output voltage.