METHOD FOR OPERATING POWER FACTOR CORRECTION CIRCUIT AND METHOD FOR OPERATING UNINTERRUPTIBLE POWER SUPPLY APPARATUS

A method for operating a power factor correction (PFC) circuit (110) of an uninterruptible power supply (UPS) apparatus (100) is provided. The PFC circuit (110) includes two T-type converters, and each of the T-type converters includes four switching tubes (Q1-Q4, Q5-Q8). The method includes: converting AC input voltage into a positive bus voltage (V1) across a first capacitor (C1) and a negative bus voltage (V2) across a second capacitor (C2) that is connected in series with the first capacitor (C1) when the UPS apparatus (100) is operated under a normal supply mode; and controlling conduction states of the switching tubes (Q1-Q8) of the T-type converters to balance the positive bus voltage (V1) and the negative bus voltage (V2) when the UPS apparatus (100) is operated under a battery supply mode.