| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for detecting turn-off of a thyristor for sure changing of a circuit, by not turning ON the thyristor of a different circuit, when a voltage exists between the gate and the cathode, and by connecting a voltage detection sensor between the gate and the cathode of the thyristor. SOLUTION: In this method, a circuit where a circuit to which two thyristors are connected antiparallel is connected to a transformer; a circuit to which two other thyristors are connected antiparallel is connected to the transformer, control circuits are incorporated in the circuits and a voltage detector is connected between the gates and cathodes of the thyristors; an the gate signal of the thyristor of one of the circuits is turned on. Then, the load voltage is adjusted, without having to interrupt the supplying of power of a load of the transformer; and when the gate signal of the thyristor is turned OFF and detection voltage of the voltage detector becomes 0V at the time of turning off one circuit from ON and switching the other circuit from OFF to ON; and a control circuit detects and judges it as turn-on of the thyristor and turns on the gate signal of the other thyristor. COPYRIGHT: (C)2008,JPO&INPIT
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