POWER CONVERTER

摘要

PROBLEM TO BE SOLVED: To provide a large capacity power converter which can detect a turn-off failure in a short time and protect GTOs from chain breakdowns to improve reliability by adding and changing a low cost and small-sized circuit. SOLUTION: The voltage between the terminals of an off-gate output switch 25 is amplified by a preamplifier 26. If the output voltage V of the preamplifier 26 is higher than a reference voltage Vref in steady state after the turn-off, it is determined that the turn-off has failed, and a controller 1 is instructed so as not to output turn-on signals to all GTOs so as to protect normal GTOs from breakdown.