Patent ID: 7130202

Claim:
An uninterrupted power supply, comprising an AC input end; a rectifying circuit; a battery branch; a power factor correction branch; and an inverter branch, wherein an input end of said rectifying circuit is connected with said AC input end, said battery branch is connected in parallel with positive and negative ends of said rectifying circuit on a DC output side, an input end of said inverter branch is connected in parallel with positive and negative ends of said power factor correction branch on the DC output side, an output end of said inverter branch is a single-phase AC output, and said power factor correction branch is placed between said battery branch and said inverter branch, characterized in that said power factor correction branch includes two positive boost converters connected in parallel, two negative boost converters connected in parallel, a generating circuit of driving signal of power factor correction, and a holding and shifting circuit of driving pulse-width, wherein said positive and negative boost converters have a switch transistor respectively, said holding and shifting circuit of driving pulse-width being placed after the generating circuit of driving signal of power factor correction, and the signals from its input and output ends being connected to the control ends of the switch transistors of said positive boost converters or the switch transistors of said negative boost converters.