Uninterruptible Power Supply and Power Supply Switchover Method

An uninterruptible power supply includes a first power input, a second power input, a load end, a bypass, a main circuit, and a controller. The bypass includes a bidirectional switch, and the main circuit includes a rectifier circuit and an inverter circuit. The controller is configured to control a voltage that is output by the inverter circuit to be greater than a voltage that is input to the bypass, so that when currents are input to the bypass and the inverter circuit separately, a current that is output by the inverter circuit is transmitted to the load end. In response to a fault at the load end, the voltage that is output by the inverter circuit suddenly drops below the voltage that is input to the bypass, and a current that is output by the bypass is transmitted to the load end.