Patent ID: 7098558

Claim:
A power-converting apparatus, capable of holding an output AC voltage at a constant voltage level when a variation in voltage input via an AC power-supply source remains within a predetermined range, the power-converting apparatus comprising: separating means for electrically separating an AC power-supply source from input terminals of said power-converting apparatus; a battery; an AC/AC converting circuit; a DC/DC converting circuit connected to the AC/AC converting circuit; and a capacitor connected to the AC/AC converting circuit and the DC/DC converting circuit, wherein said AC/AC converting circuit initially rectifies AC current input via said AC power-supply source and then causes said capacitor to smooth said rectified current to convert said AC current into DC current, and then further converts said DC current into AC current, wherein said DC/DC converting circuit enables said capacitor to be charged with a DC voltage delivered from said battery and further enables said battery to be charged with a DC voltage delivered from said capacitor, and wherein said DC/DC converting circuit charges said capacitor with said battery up to a voltage level substantially above the peak value of said AC power-supply source, while said AC power-supply source is electrically separated from the input terminals of said power-converting apparatus by said separating means, and wherein said AC power-supply source is electrically connected to the input terminals of said power-converting apparatus after said capacitor has been charged with said battery.