Junction Temperature Estimation to Improve Accuracy of SiC MOSFET Lifetime Model Using Diode Forward Voltage Measurement Circuit

Abstract

SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) are widely employed in many power conversion applications owing to their excellent switching characteristics. The failure rate of power semiconductors constitutes a significant portion of the overall failures in power conversion devices, and this has driven the research on life-prediction methods to enhance long-term reliability and performance. The life prediction of SiC MOSFETs relies on offline life models. The accuracy of these models depends on precisely estimating the junction temperatures of the devices. In this study, a measurement circuit is proposed that improved temperature estimation accuracy by utilizing the body diode forward voltage, one of the key temperature-sensitive electrical parameters, to enhance the accuracy of life model predictions. Further, a comprehensive analysis of the proposed circuit is provided, including a parameter design procedure for minimizing the voltage error and optimizing performance. The experimental results confirmed a temperature estimation accuracy of less than 0.5 degrees C and demonstrated the applicability of the proposed circuit for deriving offline lifetime model parameters under Power Cycling Test conditions.