PARALLEL CONNECTED POLYPHASE THYRISTOR POWER SUPPLY CONTROLLING DEVICE

PURPOSE:To prevent the unbalanced current flowing to the group in parallel as well as to perform a high degree of excellent control over the current by a method wherein the characteristic difference of a phase controlling circuit and a thyristor converter is controlled by performing a correction. CONSTITUTION:The current running on thyristor converters 2 and 3 and a load coil 1 is detected by DCCT (transformer for converter) 6, 14 and 15, and the result is inputted to a controller 13. The output of the DCCT6 is level-converted to one half by a level converter 16, and after the above has been compared with the output of DCCT14 and 15, the result is given to amplifiers 19 and 20. This value becomes the correction value to be used to correct the characteristic difference of the phase controlling circuits 11 and 12. On the other hand, the current of the load coil is compared with the reference value to be set by the potentiometer 8 through the intermediary of a level converter 7. The deviation of the above is inputted to an amplifier 9 and an arithmetic operational unit, and the amount of operation of the phase controlling circuits 11 and 12 is determined.