A High-Resolution In Situ Condition Monitoring Circuit for SiC Gate Turn-Off Thyristor in Grid Applications

Silicon carbide (SiC) gate turn-off (GTO) thyristor is attractive for grid applications due to the excellent performances of high blocking voltage and low ON-resistance. However, the short-circuit reliability issue has become one of the limiting factors. An in situ condition monitoring method for the reliability of SiC GTO is presented in this work. It uses the forward I-V characteristics of anode-gate p-n junction as the reliability degradation precursor of SiC GTO. The monitoring circuit shows a current resolution of 64 mu A with the current range of -31 similar to 1027 mA. It provides full electrical isolation with 2-kV isolation voltage. Finally, a set of short-circuit power cycling tests are conducted with the monitoring circuit, and the results show that the method proposed in this article can effectively detect the change of I-V characteristics of SiC GTO to predict the degradation of device physical health.

Automated summary

Silicon carbide gate turn-off thyristor is favored for grid applications due to its high blocking voltage and low ON-resistance. However, the short-circuit reliability issue is a limiting factor. This study presents an in situ condition monitoring method for SiC GTO reliability, using the forward I-V characteristics of anode-gate p-n junction as a precursor for degradation. The monitoring circuit demonstrates high current resolution, current range, and electrical isolation capabilities.