Power conversion circuit for use in an uninterruptable power supply, and uninterruptable power supply including the power conversion circuit

A power conversion circuit (1000) comprises at least one converter module (1100) comprising a first (1110) and a second (1120) step-up converter for converting a rectified AC voltage and/or a DC voltage into a DC supply voltage; an inverter module (1330) with a three-level inverter circuit converting the DC supply voltage into an AC voltage (line out); and an intermediate module (1200) connecting the converter module to the inverter module. The intermediate module (1200) additionally includes snubbers (1130,1140, 1310,1320) comprising series connections of a diode and a capacitor collecting transient energy of parasitic inductances. A first and second step-down converter (1210,1220) convert the resulting voltage into the DC power supply voltage providing that voltage to the input terminals of the converter module. Maybe used in an uninterruptible power supply and shall improve the effectiveness.