Real-Time Extraction of SiC mosfets' Degradation Features Under Improved Accelerated Power Cycling Tests for DC-SSPC Application

The SiC mosfet is a key component of the dc solid-state power controller (DC-SSPC). The reliability of DC-SSPCs can be improved by real-time online monitoring of the degradation of SiC mosfets. At present, the degradation of SiC mosfets can be indirectly monitored using thermosensitive electrical parameters (TSEPs); however, their degradation can cause nonnegligible measurement errors. Another limitation is that one type of TSEPs can only reflect a certain form of the degradation process. On this basis, in this article, the real-time extraction method of SiC mosfets' degradation features under improved accelerated power cycling tests for DC-SSPC application (i.e., average and standard deviation of the on-state resistance change rate (avgk and stdk) of the improved accelerated power cycling test) is proposed. The avgk and stdk can be easily obtained by simple calculations. This method can not only directly monitor the severe degradation of bonding wires, but it can also monitor the severe degradation of the solder layer without measuring the junction temperature (T-J). Compared with the traditional solder layer degradation feature extraction method using thermal resistance, for which T-J is essential, the monitoring results using the proposed method are not affected by the degradation of TSEPs. Finally, the effectiveness of the proposed method is verified by experimental results.