Combination of Thermal Subsystems Modelled by Rapid Circuit Transformation

Y.C. Gerstenmaier (1) , W. Kiffe (1) , G. Wachutka (2)

1 Siemens AG [Munich]
2 Institute for Physics of Electrotechnology

This paper will deal with the modeling-problem of combining thermal subsystems (e.g. a semiconductor module or package with a cooling radiator) making use of reduced models. The subsystem models consist of a set of Foster-type thermal equivalent circuits, which are only behavioral models. A fast al-gorithm is presented for transforming the Foster-type circuits in Cauer-circuits which have physical behavior and therefore allow for the construction of the thermal model of the complete system. Then the set of Cauer-circuits for the complete system is transformed back into Foster-circuits to give a simple mathematical representation and applicability. The transfor-mation algorithms are derived in concise form by use of recur-sive relations. The method is exemplified by modeling and measurements on a single chip IGBT package mounted on a closed water cooled radiator. The thermal impedance of the complete system is constructed from the impedances of the sub-systems, IGBT-package and radiator, and also the impedance of the package can be inferred from the measured impedance of the complete system.

Mots clés: rapid circuit transformation; Thermal modelling; subsystems; thermal equivalent circuits

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Y.C. Gerstenmaier, W. Kiffe, G. Wachutka. Combination of Thermal Subsystems Modelled by Rapid Circuit Transformation. THERMINIC 2007, Sep 2007, Budapest, Hungary. pp.115-120. ⟨hal-00202545⟩