UNINTERRUPTIBLE POWER SUPPLY

This application provides an uninterruptible power supply. A rectifier of the uninterruptible power supply includes six first rectifier diodes, six second rectifier diodes, three alternating current side relays, six direct current side relays, a DC/DC conversion unit, and a controller. The other end of each alternating current side relay is connected to anodes of two first rectifier diodes, and cathodes of the two first rectifier diodes are respectively connected to two phases of positive input ends of the DC/DC conversion unit. The other end of each alternating current side relay is further connected to cathodes of two second rectifier diodes, and anodes of the two second rectifier diodes are respectively connected to two phases of negative input ends of the DC/DC conversion unit. In response to voltage abnormality of three phases of alternating current input ends, the controller controls the DC/DC conversion unit to stop operation, and controls the three alternating current side relays to turn off; and after the three alternating current side relays are turned off for first preset duration, controls the six direct current side relays to turn on. By using this application, circuit costs of the uninterruptible power supply can be reduced.