JPS5456352A - Gate control system for high-voltage thysistor converter - Google Patents

Abstract

PURPOSE: To decrease the gate power source capacity and to reduce the cost by supplying the first gate pulse to be supplied within the normal conduction period and the second gate pulse of forced ignition for evervoltage protecting purpose at the shortage time of the floating angle to the gate of SCR.

CONSTITUTION: The forward and backward voltage detecting signals are converted to the electric signals through light guide 2 and via light-electric signal converter circuit 31. And floating angle shortage signal (f) is generated through floating angle decision circuit 33 to be turned to the input of pulse generator circuit 36, and output pulse (k) featuring a wide duration is delivered when the floating angle is short. On the other hand, operation signal (b) and forward voltage detection signal (c) are supplied to AND circuit 35 with output signal (e) used for the input of circuit 36. Circuit 36 produces pulse signal (j) of a narrow duration at the conduction start and intermittent time. Signal (j) and (k) are turned to signal via OR circuit 34 and then converted to the light through electric-light signal converter circuit 37 to be transmitted to the high-potential part via light guide 2. Pulse (j) featuring a narrow pulse duration is transmitted more frequently than signal (k). As a result, the gate power source capacity can be decreased as a whole, thus ensuring the cost reduction

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