Power Losses and Thermal Impedance Characterization of Power Modules

Abstract

The trend of electrification in automotive industry over the last years, has lead to the production of numerous vehicles that have either fully electric or hybrid drivetrains. The main component of the power electronics in the drive-train of such vehicles, are the power modules. During driving cycles, the heat produced from power losses at power electronics, forces the power modules to thermal cycling, consequently to thermal-mechanical stress. Thus, sufficient knowledge of the power losses and the thermal behavior of the power modules is necessary for the sake of proper dimensioning and reliability. This thesis deals with the measurement of power losses for an IGBT power module, the extraction of the power losses according to its manufacturer and the comparison between them. In addition, a Finite Element model of a power module is built and verified with experimental measurements, to extract the self and mutual thermal impedances of its silicon chips. As a result, look-up tables with power losses of the power module in several operating points are obtained, as well as mathematical models that describe the thermal behavior of the module are derived after simulations.