Power converter with a failure detector of a self-turn-off semiconductor element

Claim 1

A power converter, comprising: a plurality of serially connected self-turn-off semiconductor elements; first control circuit means for producing a plurality of first control signals; plural second control circuit means connected to said first control circuit means for receiving respective of said first control signals and for producing and supplying non-conduction control signals to respective of said self-turn-off semiconductor elements to turn off said respective elements upon reception of said first control signals; a plurality of failure detection means connected to respective of said self-turn-off semiconductor elements for detecting a fault thereof and for producing a fault detection signal when the respective of said self-turn-off semiconductor elements has failed; and a plurality of blocking means connected to respective of said failure detection means and to said first control circuit means for blocking at least a selected one of asid first control signals and said non-conduction control signals upon detection of a failure in the respective self-turn-off semiconductor element so that a non-conduction control signal is not produced and not applied to the failed semicondcutor element and the remaining non-failed self-turn-off semiconducctor elements continue to have respective non-conduction signals produced and supplied thereto.