A Junction Temperature and Package Aging Decoupling Evaluating Method for SiC MOSFETs Based on the Turn-on Drain-Source Current Overshoot

Junction temperature and package aging levels are key factors related to the reliability of SiC metal oxide semiconductor field effect transistors (MOSFETs). Many methods have been proposed to evaluate them for device health management. However, indicators in existing evaluating methods are usually affected by both junction temperature and package aging levels. Thus, these methods can hardly be used in real industrial applications because both two key factors are unknown. To solve this problem, a decoupling evaluating method for junction temperature and package aging levels of SiC MOSFETs is proposed in this article. The turn-ON drain-source current overshoot is used as the indicator. First, it is discovered that there is a turning temperature point which can divide the indicator curve into two regions. Only in one region, it is sensitive to the junction temperature, but in all regions, it increases obviously with the package aging levels. Second, an evaluating strategy is proposed based on the discovered characteristic of the indicator. Aging levels can be evaluated first in a low temperature case, and the junction temperature can be obtained subsequently. Thus, the two key factors can be evaluated individually which is hard to achieve with existing methods. Finally, the effectiveness of the proposed method is verified by experiments.