Article ID: 22.20250257
IGBT module requires accurately intermediate layer temperatures (ILT) monitoring to ensure system safety and reliability. Considering critical failure factor of solder layer voids, this paper implements real-time monitoring to IGBT module ILT using DT. By deriving the nonlinear relationship between thermal resistance of solder layer and junction temperature, a mathematical model is refined to more precisely reflect the actual thermal behavior of IGBT. A nonlinear intermediate layer temperatures observer is designed to further improve the accuracy. Experimental validation demonstrates that, the proposed observer significantly enhances the precision with an error of only 0.1% compared to traditional methods.