| 摘要 |
PURPOSE: To provide a converter device which prevents the generation of an overcurrent, an overvoltage or the like the moment that the power supply of the converter device is changed over to a commercial power supply from a nonutilit generator in an uninterruptible DC power-supply apparatus and whose constitution is simple. CONSTITUTION: A converter device 13 is connected across three-phase AC power supplies 7, 8, 9 and a DC power supply 14, and it converts an alternating current into a direct current. The converter device is constituted in such a way that the three-phase AC power supplies are judged to be abnormal when the arc tangent value θ of the quotient in which one component on the side of two phases obtained by converting every phase voltage or every line voltage in the three-phase AC power supplies into two phases from three phases is divided by the other component is changed by a prescribed value or higher within a unit time. Consequently, the abnormality of the AC power supplies of the converter device can be detected quickly by a simple constitution, and it is possible to prevent the generation of an overcurrent or an overvoltage. When the inverter device is used for an uninterruptible power-supply apparatus, its effect is especially remarkable. |
