| 摘要 |
PURPOSE:To reduce the harmonic component contained in a current waveform by providing two sets of switching elements connected in parallel with one another and flowing a small current to an induction machine, thereby slowing rising the current. CONSTITUTION:Either one of sub-thyristors 24, 25 is fired and conducted by a gate pulse from a firing cicuit 29, but since a resistor 28 is connected in series with them, a current which flows to an induction motor 2 is reduced that much. When a voltage is generated at the resistor 28 by the current, a firing circuit 7 is operated by the voltage, and a gate pulse is applied to one of the gates of the thyristors 3, 4. Accordingly, one of the thyristors 3, 4 is fired and conducted. The current which flows through the motor 2 at this time is increased as compared with the previous current since no resistor 28 is inserted. |
