Online Junction Temperature Estimation for SiC MOSFETs Using Drain Voltage Falling Edge Time

Abstract

The junction temperature is vital for the reliability evaluation and health management in silicon carbide (SiC) MOSFET applications. This article proposes a novel method to estimate the junction temperature under actual operating conditions, using the drain voltage falling edge time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t_{f,\text {edge}}}$ </tex-math></inline-formula> ) as temperature-sensitive electrical parameters (TSEPs). Experimental results show that the proposed circuit can estimate the junction temperature with good linearity, high-temperature sensitivity, and load current independence. Furthermore, the proposed method is verified with the aged SiC MOSFET after the power cycling test. It shows a tiny impact of the bond wire degradation on the junction temperature estimation accuracy.