| 摘要 |
PURPOSE:To prevent the failure of commutation in a frequency converter by generating a gate reverse bias signal synchronously with the trigger signal from a thyristor and simultaneously automatically tracing the variations of a load to thereby stably control the converter via a gate circuit. CONSTITUTION:A thyristor 7 and a feedback diode 8 are connected in an anti- parallel connection, and connected in parallel with a series resonance circuit of a capacitor 9 and an otuput coil 10 forming a commutating circuit of the thyristor 7. The thyristor 7 is driven by a gate circuit 12, and high frequency operation is started or stopped by starting and stopping means 11. A signal from a charging and discharging circuit 20 operated in response to the on or off of the thyristor 7 in the gate circuit 12 is applied to first and second voltage comparators 21, 22. The output of the first comparator allows the thyristor 7 to supply its trigger signal to the gate circuit of the thyristor, and the output of the seond comparator allows the thyristor 7 to supply its reverse bias signal to the gate circuit. Accordingly, it can conduct stable contol via the gate circuit to thereby prevent the failure of commutation in a frequency converter. |
