DI/DT evaluation of a SI N-type GTO designed for pulsed power applications

Pulsed power systems which utilize solid state switching devices, rather than spark/gas-type devices, could potentially exhibit increased energy density, repetition rate, operational lifetime, and ruggedness. However, further evaluation of advanced solid state devices, such as thyristor type devices, is required to better understand their operation for pulsed power applications. This paper details experimental evaluation of the dI/dt capabilities of a silicon (Si) n-type, asymmetric-blocking gate turn-off thyristor (GTO) manufactured by Silicon Power. The device under test (DUT) is rated to block up to 4 kV with rated dI/dt of 30 kA/μs. The DUT was designed as a solid state replacement for spark/gas-type switching devices in pulsed power applications. A low inductance test circuit was designed and built to evaluate the dI/dt capabilities of the DUT. Specific care was taken to minimize the parasitic inductance and thereby exploit the achievable dI/dt ratings by the test devices. An external fiber-driven gate driver is used to trigger the device with gate current (IG) of approximately 1.3 A and rate of current change (dIG/dt) of approximately 25.5 A/μs. Experimental dI/dt values greatly exceeded rated values; specifically dI/dt values of approximately 77 kA/μs were readily achieved at 4 kV. No device degradation was observed over the course of evaluation.