Method and circuitry for controlling and equalising the blocking voltages of series-connected, gate-controlled semiconductors

摘要

The reverse voltage of one semiconductor, e.g. thyristor, is converted by an up-down counter into a numerical mean value. Its voltage is compared with the reverse voltages of the other thyristors and the differences converted by the counter into numerical values. According to whether the result lies above or below the mean value the individual turn-off times are adjusted so that the thyristors block simultaneously. An Independent claim is also provided for a control circuit.