| 摘要 |
PURPOSE: To suppress the rush current flowing to an input transformer or an AC filter capacitor by turning on an AC input switch after inverting a converter, which constitutes an uninterruptible power supply, with a storage battery as a DC power source, and reversely exciting an input transformer or an AC filter capacitor. CONSTITUTION: A voltage establishment detecting circuit 31 for an AC power source 1 is provided, and in condition that the voltage of the AC power source 1 is not established, an AC input switch 2 is opened, and the gate signal of a converter 6 is given by a logical circuit 21 so as to stop the converter 6. In case that the voltage of the AC power source 1 is established, the gate signal is given to the converter 6 and the converter 6 is started, using the DC power of the storage battery 10, and the magnitude and the phase of the AC voltage on the input side of the converter 6 are accorded with those of the AC power source, and then an AC input switch 2 is closed. Hereby, a rush current can be reduced. Accordingly, the voltage ripple of the AC power source 1 can be prevented, and a transformer 3 can be downsized. |
