| 摘要 |
PROBLEM TO BE SOLVED: To provide an uninterruptible power supply device which is quickly and accurately capable of detecting the abnormality of an AC power supply and stably supplying power to a normal load. SOLUTION: A changeover relay 16 switches a power supply route between a a route, through which a power is supplied from a commercial power supply 12 to a load and a route through which a reserve power is supplied from a battery 14 to the load, in accordance with the level of a changeover command signal Sa. A full-wave rectifying circuit 17 generates a power supply voltage signal Sp obtained through the full-waver rectification of the commercial power supply voltage. A reference signal generating circuit 19 generates a reference signal Sr, which has a same period as the period of the commercial power supply voltage and has an absolute-value sinusoidal waveform which rises from the zero-cross point of each period. The amplitude of the reference signal Sr is selected to be smaller than the amplitude of the power supply voltage signal Sp, which is generated while the commercial power supply 12 is in a normal state. A power supply abnormality monitor circuit 18 makes the level of the changeover command signal Sa H, when the power supply voltage signal Sp becomes smaller than the reference signal Sr. As a result of this process, an inverter circuit 15 is driven, and moreover the changeover relay 16 is switched to a contact 16a side. |
