Power conversion system and auxiliary power supplying method thereof

An auxiliary power supplying method of a power conversion system, wherein the power conversion system comprises an AC port, a DC port, an AC-DC converter, a bus capacitor and a control board, the AC port receives or provides an AC voltage, the DC port provides or receives a DC voltage, the AC-DC converter has an AC terminal and a DC terminal electrically connected to the AC port and the DC port respectively, the bus capacitor is electrically connected to the DC terminal, and the auxiliary power supplying method comprises:

• providing a first auxiliary source of the power conversion system, wherein the first auxiliary source is electrically connected to the bus capacitor for receiving a capacitor voltage across the bus capacitor;
• electrically connecting an output terminal of the first auxiliary source to an energy consumption equipment of the power conversion system;
• and
• discharging the bus capacitor by supplying power to the energy consumption equipment when the capacitor voltage across the bus capacitor is higher than a first preset value or the power conversion system is shut down.