| 摘要 |
PURPOSE:To protect series thyristor elements by generating continuos pulse when a load current decreased to a value lower than the prescribed value and applying the pulse to the gate pulse of the thyristor, thereby balancing the sharing voltages of the series thyristor element circuit. CONSTITUTION:Electric power is supplied to a load 13 through a power converter 12 which has series element circuits 14-19 connected with a plurality of thyristor elements in series with each other, the output of a current detector 11 is compared with the set value by a control circuit 21, and the gates of the element circuits 14-19 are controlled via a gate generator 20. Further, a pulse generator 30 is provided, the output of the detector 11 is compared with the output of a setter 31 for setting the load current to intermittent limit to generate a continuous pulse, which is applied to the generator 20. Accordingly, the sharing voltage of the series element circuits can be balanced, and even if the load current is intermittently flowed, the thyristor elements is not abruptly damaged, thereby improving the reliability. |
