Switching device

Abstract

Abstract PURPOSE:To detect quickly the breakdown of a field effect transistor FET by attaching a temperature sensor to a resistance element connected in series to a gate terminal. CONSTITUTION:Firing signals 7a and 7b are sent alternately from a control circuit 11, and gate drive circuits 3a and 3b send gate voltages on the basis of these signals. FETs 1a and 1b are turned on and off alternately repeatedly thereby. If the FET 1a is broken down by same cause, its gate and source are short-circuited and a large current is flowed to a resistance element 2a. The resistance element 2a generates heat by this current, and the contact of a temperature sensor 8a is closed when the temperature exceeds a prescribed value. This close information is transmitted to an amplifier 13a to short-circuit the output, and sending of the firing signal 7a is stopped. As the result, the gate voltage is not sent from the gate drive circuit 3a and the current is not flowed to the resistance element 2a, and the element 2a is not burnt therefore.

Inventors

• 👤 Tsukasa Fukushima
• 👤 司 福島
• 👤 Kaneya Noda
• 👤 野田　金矢

Bibliographic Details