Protection circuit for semiconductor switch element for power

Abstract

Abstract PURPOSE:To unnecessitate a discharge current control resistance and to reduce the loss of power by a method wherein the energy of a capacitor for absorbing an overvoltage is regenerated on the DC supply side. CONSTITUTION:A transistor TR is subjected to a chopping control in a constant cycle during a period when a GTO thyristor THU or THX is ON. When the transistor TR is turned ON, an energy accumulated in a capacitor C1 is taken in as a primary current of a reactor transformer T, and when the transistor TR is turned OFF, it is sent from a secondary wiring to a DC power source via a diode D2 and regenerated therein as a rectified current. By this chopping control, the energy of the capacitor C1 is all regenerated in the DC power source during the period when each of the GTO thyristors THU and THX is ON, the voltage thereof is returned to a state of discharge, and thus it becomes possible to absorb an overvoltage in the next turn-off of the thyristors. The chopping control of the transistor TR is synchronized with a gate control signal by a gate control circuit GC for the GTO thyristors THU and THX, etc.

Inventors

• 👤 Tetsuo Sueoka
• 👤 末岡　徹郎
• 👤 Yoshisuke Takita
• 👤 滝田　義介

Bibliographic Details