A Physical Thermal Network Model of Press Pack IGBTs Considering Spreading and Coupling Effects

Abstract

With the advantages of high-power density, easy series connection, and failure short-circuit mode, the press pack packaging technology has been widely adapted in insulated gate bipolar transistors (IGBTs) which are applied for high-voltage and high-power density power apparatuses. Accurate modeling of temperature field in the press pack IGBTs (PP IGBTs) is vitally significant with the increasing power density. First, the heat dissipation structure in the PP IGBTs is analyzed in detail in this article. Then, a physical network model is established, which has physical meaning and can be applied in structural design of the PP IGBTs. The heat spreading and thermal coupling effects which mainly are introduced by larger size electrode plates have been considered in the proposed model. For accurate and fast extraction of thermal resistance, an analytical method is proposed and compared with the traditional fixed angle method and finite element method (FEM), respectively. The comparison result shows that the proposed analytical method has enough accuracy, good convergency, and low calculated amount. The proposed new model not only could be fast set by using the analytical method but also can reflect the influence of submodule position, heat dissipation condition, and adjacent submodules, which cannot be contained in the conventional model. The proposed model has maintained accuracy close to the 3-D FEM model, but its calculation amount is much less. The accuracy of the proposed model is also verified through an experiment. Moreover, based on the analytical solution derived, the influence of different factors on submodule path thermal resistance and coupling thermal resistances is revealed and discussed.