To make a protection by detecting the overvoltage protective ignition of a Vbo free thyristor.
Vbo free thyristors 1a-1n are given gate pulses 7 from a gate pulse generating circuit 3, at the same time, through supply paths 31a-31n. Forward voltage detecting circuits 4a-4n are connected in parallel with these thyristors 1a-1n and snubber circuits 2a-2n. The forward voltage detection signals from these forward voltage detecting circuits 4a-4n are transmitted to Vbo detecting circuits 6a-6n via, for examples, optical fibers 5a-5n. The Vbo detecting circuits 6a-6n detect breakover voltage (Vbo) of the thyristors 1a-1n, by using the gate pulses 7 and the forward voltage detecting signals, and output Vbo detection signals 8a-8n. Then, the gate pulse generating circuit 3 carries out treatment, such as, to immediately stop the output of the gate pulses 7, when the Vbo detection signals 8a-8n occurs, even from a single point of the thyristors 1a-1n.
SATO KATSUO
YAMAZAKI AKIMITSU
YAMASHITA KEIICHI
| JP2005210791A | 2005-08-04 | |||
| JP2006271084A | 2006-10-05 |
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