Thermal component model for electrothermal analysis of IGBT module systems

The insulated gate bipolar transistor (IGBT) modules are getting more accep ted and increasingly used in power electronic systems as high power and hig h voltage switching components. However, IGBT technology with high speed an d greater packaging density leads to higher power densities on the chips an d increases higher operating temperatures. These operating temperatures in turn lead to an increase of the failure rate and a reduction of the reliabi lity. In this paper, the static and dynamic thermal behavior of IGBT module System mounted on a water-cooled heat sink is analyzed. Although three-dim ensional finite element method (3-D FEM) delivers very accurate results, it s usage is limited by an imposed computation time in arbitrary load cycles. Therefore, an RC Component Model (RCCM) is investigated to extract thermal resistances and time constants for a thermal network. The uniqueness of th e RCCM is an introduction of the time constants based on the Elmore delay, which represents the propagation delay of the heat flux through the physica l geometry of each layer. The dynamic behavior predicted by the thermal net work is equivalent to numerical solutions of the 3-D FEM. The RCCM quickly offers insight into the physical layers of the components and provides usef ul information in a few minutes for the arbitrary or periodic power wavefor ms. This approach enables a system designer to couple the thermal predictio n with a circuit simulator to analyze the electrothermal behavior of IGBT m odule system, simultaneously.