| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve a problem that it is difficult to achieve the quick turn-off of an AC switch including a thyristor. <P>SOLUTION: First, second and third AC input terminals 1a, 1b and 1c are connected with a load 9 and a power conversion circuit 10 through first, second and third AC switches 2a, 2b and 2c. A DC terminal of the power conversion circuit 10 is connected with a DC power supply 5. When an abnormality of a power supply voltage is detected by an abnormality detection circuit 30, the on-control of the first to the third AC switches 2a-2c are stopped and a voltage added with a pulse is generated simultaneously from the power conversion circuit 10, thus applying a reverse bias voltage to the thyristors included in the two AC switches selected from the first, second and third AC switches 2a, 2b and 2c. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
