Patent ID: 8305779

Claim:
An uninterrupted power supply (UPS) circuit, comprising: a neutral; a battery having a positive terminal receiving a first DC voltage and a negative terminal; a first PFC boost converter, comprising: a first PFC circuit outputting a second and a third DC voltages, and comprising: a first inductor having a first terminal coupled to the positive terminal and a second terminal; a first rectifying bridge comprising a first and a second bypass diodes coupled to a first middle point coupled to the second terminal of the first inductor, and having a first terminal, and a second terminal coupled to the negative terminal; a first switch bridge comprising a first upper and a first lower switches coupled to a second middle point, and having a first terminal coupled to the first terminal of the first rectifying bridge and a second terminal coupled to the second terminal of the first rectifying bridge; a first control switch having a first terminal coupled to the second middle point and a second terminal coupled to the neutral; and a first inverter receiving the second and the third DC voltages and outputting a first AC voltage; and a second PFC boost converter, comprising: a second PFC circuit outputting the second and the third DC voltages, and comprising: a second inductor having a first terminal coupled to the positive terminal and a second terminal; a second rectifying bridge comprising a third and a fourth bypass diodes coupled to a third middle point coupled to the second terminal of the second inductor, and having a first terminal and a second terminal coupled to the negative terminal; a second switch bridge comprising a second upper and a second lower switches coupled to a fourth middle point, and having a first terminal coupled to the first terminal of the second rectifying bridge and a second terminal coupled to the second terminal of the second rectifying bridge; a second control switch having a first terminal coupled to the fourth middle point and a second terminal coupled to the neutral, wherein the UPS circuit operates under one of a DC mode having a positive and a negative half-cycles, and an AC mode having a positive and a negative half-cycles, the first and the second control switches are turned on while under one of the positive half-cycle of the DC mode and the AC mode, and the first and the second control switches are turned off while under the negative half-cycle of the DC mode; and a second inverter receiving the second and the third DC voltages and outputting the first AC voltage.