| 摘要 |
PURPOSE:To prevent a GTO from damaging due to an overvoltage by providing forward voltage detectors at respective GTOs, applying an OFF gate signal, and then applying an ON gate to all the GTOs when an unbalance occurs in sharing the voltage. CONSTITUTION:In a circuit in which semiconductor elements (GTO)1a, 1b having a plurality of self-extinguishing ability are connected in series or series-parallel, forward voltage detecting means are connected with the GTOs 1a, 1b. The detecting means may employ light emitting diodes 5a, 5b, 13a, 13b. After an OFF gate signal (b) is applied, the forward voltage of the GTOs 1a, 1b are detected after the prescribed time. When the forward voltage is detected any of the GTOs, an ON gate signal (a) is immediately applied to turn all the GTOs ON. Thus, even if an extinguishing impossibility occurs, it can prevent the elements from damaging. |
