Modeling and Analysis of Monitoring Gate-Oxide Degradation of SiC Power MOSFETs in Circuit by the Fingerprints of Voltage Switching Transient

In this article, we have investigated the sensing principle and method of gate-oxide degradation of SiC power <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small>s based on fingerprints of voltage switching transient. The modeling of the voltage switching rate during the turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> process related to the oxide trap of SiC power <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> is established. The method and the model for monitoring the voltage switching rate are proposed based on the capacitive-coupled principle. The variations of the voltage switching rate caused by the oxide trap charge are converted into the voltage of the capacitive sensor, and the difference of peak of sensor voltage between fresh and degraded SiC power <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small>s increases with the increase of oxide trap density. The experiment by in situ degradation monitoring of the SiC-based boost converter is carried out to verify the possibility of the proposed method, and the results show a good agreement with the proposed model. The proposed method, which does not affect normal operation, can be used for online degradation monitoring of the SiC power <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small>s in the power conversion system.