Efficient calculation of transient temperature fields responding to fast changing heatsources over long duration in power electronic systems

A method is presented, which describes the evolution of the complete temperature field in electronic systems by multiplication of two low order matrices, one depending on position, the other one on time. The first matrix constitutes the model and is fitted with a linear and fast algorithm to measurement or simulation. A very fast and accurate calculation of the temperature evolution in multichip-modules (MCM) is achieved, which is beyond the practicability of finite element method (FEM)-analysis in case of high frequency power pulses over long time intervals. The problem of temperature response to arbitrarily fast heat-source changes is solved by an analytical result, which gives the steepness of the thermal impedance at time zero. The method is applied to a high frequency dc/dc-converter and a dc/ac-converter [integrated starter generator (ISG)] module both for automotive applications. A new methodology is presented for constructing thermal equivalent circuits for electrothermal simulation with a multitude of temperature dependent heat sources.