| 摘要 |
PURPOSE:To prevent excess cross current from being transiently generated, by making responding speeds in the increasing direction and the reducing direc tion of the output voltage of two sets of thyristor converters(groups), coincide with each other. CONSTITUTION:A three-phase-bridge-connected thyristor is connected to a load 2 in inverse parallel with each other via the cross current suppressing reactor 3a-3b of two sets of thyristor converters 1a-1b, and constant cross current Ic is permitted to flow and is fed from the respective ones. As a current control ling system, a comparator CO, a current controlling section 4, an adder AD and a subtracter DE, and an ignition pulse controller PHC are arranged. In this case, rate-of-change limiting sections 6a-6b for limiting a change degree on every sample of input signals ECa-ECb of said controller PHC are arranged, and the characteristic of the variable gain is turned into characteristic changing a gain in both the positive and negative directions of a control error. As a result, the variable gain is varied, and speeds in the increasing and reducing directions of the output voltage Va, Vb of the thyristor converters 1a-1b can be made equal to each other, and the control in good order can be performed.
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