| 摘要 |
<p>PURPOSE:To prevent an overexcitation in a low velosity region and improve a responsibility of rapid demagnetization at the interruption of a load by a method wherein a signal related to an output frequency of the generator is directly obtained in a waveform shaping circuit without using a small generator for detecting a speed. CONSTITUTION:An amplifier 12 controls a voltage detecting signal from a voltage detecting circuit 7, the voltage detecting signal between field winding terminals from a stabilizing circuit 11 and an oscillation frequency of a loosen oscillation circuit 13 according to a deviation between a signal and a reference signal from a V/F detector 14, and in addition controls a firing angle of an exciting thyristor 6. The V/F detector 14 feeds out an signal when a charging voltage of a capacitor C5 charged according to the frequency of the generator. At the interruption of the load, the contacts inserted in the loosen oscillation circuit 13 is closed to cause the output voltage of the waveform shaping circuit 15 to be applied to a base of a transistor T2 of the loosen oscillation circuit 13, and the exciting thyristor 6 is inverter-operaed to rapidly be demagnetized.</p> |
