| 摘要 |
PURPOSE:To prevent destruction of a VBO-free optical thyristor by continuing an optical gate signal given to the VBO-free optical thyristor during the period till its current interruption, generated by a vibratory current, disappears. CONSTITUTION:When VBO-free optical thyristors 6-1 to 6-N are VBO-ignited, a VBO firing signal (e) becomes 1 by actuating a VBO firing detecting circuit 18. This signal is input to a monomulti-vibrator circuit 16, which then produces a pulse E having duration long enough to suppress a high frequency vibratory current, generated by VBO firing, below a main circuit current. By inputting this pulse E to an OR circuit 17, a gate signal (f) of length T1 is generated to give an optical gate pulse to the VBO-free optical thyristors 6-1 to 6-N. In this way, all the VBO-free optical thyristors 6-1 to 6-N can be ignited immediately when forward voltage is applied. |
