| 摘要 |
<p>PURPOSE:To prevent decrease in cut-off capability caused by insufficient charging of a commutation capacitor, by turning on a commutation thyristor by a retriggering pulse immediately before turning on a main thyristor in thyristor chopper circuit. CONSTITUTION:A motor 3 is driven by a Jones-type chopper circuit CH which includes a main thyristor 4, a commutation thyristor 5, a commutation capacitor 7, and a reactor 9. A control circuit for the thyristors 4 and 5 is constituted by an oscillator including an accelerating means 100 and a transistor 115, a first comparator 140 which inverts the operation of an integrator 130 when the output of the integrator 130 reaches the first specified voltage, and a second comparator 150 which is operated by the second specified voltage. The commutation thyristor 5 is turned on immediately before the main thyristor 4 is turned on. In this constitution, the inversion charges that are sufficient to turn on the main thyristor can be always obtained, and the stable operation can be secured.</p> |
