Development of a 2.6-kV light-triggered thyristor for electric power systems

The status of a present Electric Power Research Institute, Inc. (EPRI) funded research program on a directly light-triggered thyristor for high-voltage direct current (HVDC) application is reviewed. An existing 53-mm, 2600-V, 1000-A electrically fired device was suitably modified to be turned on with an incident photopulse of 30 nJ, the basic problem being the retension of a 2000-V/µs capability. Design tradeoffs between and gate sensitivity are discussed as well as problems encountered in turning on a 2-in device with such a small gate signal. Special experiments and design and analysis computer programs have helped in assessing temperature excursion during turn-on and led to improved design with a capability approaching that of the original electrically gated device.