| 摘要 |
PURPOSE:To make possible to use a simple thyristor switch in a mode change- over device, by applying electric charge of a capacitor to the thyristor switch during change-over of the mode into its converter mode so that the thyristor switch it turned off. CONSTITUTION:A series circuit 23 consisting of a capacitor 21 and a resistor 22 is connected between the d.c. output terminals of a thyristor converter 2, electrical charge in the polarity as shown in the drawing is made during the comparator mode operation of the thyristor converter 2, and d.c. power is fed to a positive d.c. bus 3 through a diode 6a in a converter-inverter change-over device 5. Further, during generation of regenerative power thyristor switches 7a, 7b in the change-over device 5 are turned on to turn the converter 2 into the inverter mode, and the electrical charge in the capacitor 21 is discharged to be charged in a reverse polarility. When the regeneration is nearly completed, the mode is turned into the converter mode while signals fed to the switches 7a, 7b are stopped. At this time the charge in the capacitor 21 is applied to the switch 7a as a reverse voltage so that it is turned off.
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