| 摘要 |
This invention relates to a PFC circuit for an uninterrupted power supply. Such a PFC circuit includes a first converter, a second converter, an energy storing branch composed of two capacitors in series, and a controller. Each of the first and the second converters has an input terminal and two output terminals. The input terminal is connected with the AC live wire of the commercial power, while the two output terminals of each converter are connected in parallel with the two ends of the energy storing branch, with the parallel joints acting as the output terminal of the positive and the negative voltages respectively. The common nod of the two capacitors in series serves as the common output terminal of the positive and the negative voltages, and it is connected with the neutral of the commercial power. By controlling the switch transistors of the first and the second converters, the controller allows the first and the second converters to output the positive and the negative DC voltages respectively, and brings the phase and the waveform of the input voltage of the commercial power and the current to be consistent with each other. The PFC circuit of the invention can be easily connected with a single battery or two batteries. It is capable of realizing AC-to-DC conversion, DC-to-AC conversion and power factor correction, and it is particularly suitable for using in the online UPS.
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