Inverse currents injection module for direct current interrupters

It is well known, actual trend in power electronics about exchange power thyristors with devices more flexible from point of view of commutation and possibility of command (IGBT, MOS transistors, GTO). There are applications, for example, DC high voltage electrical energy transmission, where because of high power switched, power thyristors remain an efficient solution. In this paper, is presented a thyristors modulator used for d.c intrerupters disconnecting at short-circuit. Design methodology of turn off groups for autonomous modulator with LC turn off circuit, it is processed by Mc. Murray and Shattuck paper. The expressions proposed for designing turn off groups are calculated in the following steps: calculation of reverse polarization time, by solving transcendental equation; determination of accumulated energy in turn off coil and finally result expressions for turn off inductivity, respective for turn off capacity.