Preliminary evaluation of super GTOS in pulse application

Compact high-action solid state switches are essential to weapon and protective systems for future Army vehicles. The Army Research Laboratory, Adelphi, MD, has been evaluating conventional and unconventional devices for an extended period of time. Large diameter thyristors have been explored and evaluated at currents in excess of 200 kA. Reverse dynistors, a Russian device, have shown even better performance than conventional thyristors due to their very fine gate structure (10-100s of microns). Fine gate structure leads to faster turnon, so that the switch is in full conduction much faster than those with more conventional gates, which vastly improves the reliability and lifetime of such devices. Silicon power corporation (SPCO) has produced a thyristor with an even finer gate structure than the dynistor. This super GTO (SGTO) also differs from conventional high-current thyristors in that it is modular rather than a single wafer design. Aside from a potential reduction in cost due to improved yield, the SGTO may be easily configured to produce the desired level of peak current by adding or subtracting individual chips in the module. This year, the Army Research Laboratory will obtain the first 400-kA SGTOs, which is double the prior current carrying capability of previous single wafer thyristors. A more critical parameter will be an increase of di/dt on turn-on by an order of magnitude. Single wafer thyristors of large diameter have had di/dt measured in kA/us. The objective of the SGTO switch is in excess of 40 kA/us. This paper presents the first experimental data from a prototype device, rated at 80-kA peak current. Data from this round of evaluation will provide critical design data for the realization of switch modules of 400 kA and beyond.