Circuit-Based Electrothermal Modeling of SiC Power Modules With Nonlinear Thermal Models
Salvatore Race, Aron Philipp, Michel Nagel, Thomas Ziemann, Ivana Kovacevic-Badstuebner, Ulrike Großner
Abstract
Silicon carbide (SiC) power devices have the potential to operate at high temperatures beyond the capabilities of silicon power devices. At increased temperatures, the temperature-dependent material properties of the SiC die and the package multilayer structure can influence the electrothermal (ET) device performance. In this article, a new step-back-correction technique implemented in a finite-difference-method-based thermal modeling tool is proposed to reduce the computational cost while maintaining a good accuracy of ET simulations for multichip power modules. The simulations take the temperature dependence of the thermal conductivity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k(T)$</tex-math></inline-formula> and both conduction and switching losses into account. The importance of considering <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k(T)$</tex-math></inline-formula> for the accurate temperature prediction of SiC power devices is demonstrated for thermal impedance evaluations characterized by high-temperature swings, as well as for a 100-kHz boost converter with low device temperature amplitudes in the steady state. The proposed ET modeling is validated by COMSOL simulations and infrared camera measurements on an example of a custom-designed and custom-manufactured half-bridge SiC power module.