PBSTRACT
Due to the development of thyristors
with turn-off times below lous it has become
possible to use an antiparallel diode
for turn-off . Xter "charging" the diode
to a high carrier concentration by irradiation
of infrared light or by a forward
biased current puls, it can carry the load
current at nearly zero voltage drop. If
this period lasts for a time of at least one turn-off time, the thyristor switches off. The following completion of the diode
recovery process causes a moderate rate
of rise of the blocking voltage.
radiation is more elegant, but the re- quirement to use high.power laser may be
prohibitive. "Charging" by a current puls on the other hand has proofed to allow for
a less expensive turn-off circuit compared
to the usual forced commutation arrangement.