Uninterruptible Power Supply (UPS) is a system device that connects a battery to the host unit and converts DC power into AC power through module circuits such as the host inverter. It is mainly used to provide stable, uninterrupted power supply to a single computer, computer network systems, or other power electronic devices such as solenoid valves and pressure transmitters.

When the mains power is normal at 380/220V AC, the DC main circuit has a DC voltage, which supplies the DC‑AC inverter to output a stable 220V or 380V AC voltage. At the same time, the mains power charges the battery after rectification. Whenever the mains power is undervoltage or suddenly fails, the battery pack feeds power back to the DC circuit through a DC‑DC converter, thereby maintaining the UPS output stable AC voltage without interruption.