| 摘要 |
1,237,677. Control of D.C. motors. MEIDENSHA K.K. 4 Dec., 1969 [9 Dec., 1968], No. 59248/69. Heading H2J. When main and auxiliary thyristors 2, 3b are fired, current passes from direct-current source 1 to load 9 through reactors 5a and 8. At the same time, capacitor 4 is charged through reactors 5a and 5d, until the thyristor 3b is turned off by reversal of current. When thyristor 3a is fired, the capacitor 4 is discharged through diode 6a and reactors 5a, 5b. The capacitor 4 is then re-charged so that the cathode of the thyristor 3a becomes positive, the re-charge voltage being higher than the previous charge voltage. During the re-charging period, the main thvristor 2 is reverse biased and is turned off by a transient voltage produced by the components 4, 5a and 5b. The thyristor 3a is turned off when re-charging of the capacitor 4 is completed. The thyristor 3b is then turned on so that capacitor 4 is discharged through reactors 5d, 5c and diode 6b. The capacitor 4 is afterwards re-charged, whereby the cathode of thyristor 2 becomes positive, the thyristor 3b being turned off by the resonance of components 4, 5d and 5c. The cycle of operations is repeated by re-firing the thyristors 2, 3b. Power is returned from the load 9 to the source 1 by firing the thyristor 2 and turning thyristor 11 on and off. The capacitor 4 is charged so that the cathode of thyristor 3a becomes positive when thyristor 11 is fired, the power of the load 9 being stored in reactor 8. The capacitor is discharged through thyristor 3b, reactors 5d, 5c, and diode 6b, the thyristor 11 being turned off. Reversal of current also turns off the thyristor 3b. The power stored in the reactor 8 is returned to the source 1 through diode 6a.
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