MMC-based online uninterrupted power supply system

The utility model discloses an MMC-based on-line uninterruptible power supply system. The system comprises a main power supply loop, a bypass power supply loop and a DC power supply. Wherein the mainpower supply loop provides an uninterrupted power supply for an alternating-current load through an alternating-current main input switch, an MMC type rectifier, an MMC type inverter, a static switchand an output switch; the bypass power supply loop provides an uninterrupted power supply for an alternating current load through an alternating current bypass input switch, a maintenance switch or abypass switch, a static switch and an output switch; and the direct-current power supply supplies direct-current power to the MMC type inverter through the direct-current bus and the direct-current switch. According to the utility model, the DC power supply electric energy quality can be ensured without configuring a filtering link, and the operation reliability of the online uninterrupted power supply system can be improve