| 摘要 |
PROBLEM TO BE SOLVED: To protect a switching device from any overvoltage, by bringing a thyristor into a fault when the voltage state across the switching device gives to it a potential damage, and by feeding to the switching device such a low impedance as to make a reverse directional inversion across it impossible. SOLUTION: A protection block 300 shunts insulated gate bipolar transistors(IGBT) 101 across them, and has at its terminal an asymmetric thyristor (ASCR) 307 connected in parallel with the transistors 101. Hereupon, the ASCR 307 has the characteristics of a high dV/dt-factor and a low reverse voltage factor, etc. Thereby, there is no possibility that the IGBT switching device 101 to be protected reaches a dangerous operating state before it is turned on, making its very highly reliable protection possible. |
