Thermal simulation approach to the cooling of a power IGBT by heat pipes

In this work, we have developed a model in order to simulate the cooling of a power IGBT module by heat pipe systems. The IGBT is modeled by a RC thermal circuit approach on the basis on its thermal characteristics delivered by the manufacturer. The heat pipe is also modeled by a RC thermal circuit. The thermal resistances and capacitances of the heat pipe model are determined by both experiments and theoretical calculations. The model aims to determine the junction temperature of the IGBT as well as the heat pipe temperatures in response to a periodic heat input power as a function of different parameters such as the cyclic ratio and the switching frequency. The simulations results indicate that for, a given switching frequency, the cyclic ratio affects the junction temperature which oscillates between a minimum value and a maximum one. Indeed, the maximum as well as the minimum junction temperatures increase with increasing cyclic ratio. For a given cyclic ratio, the junction temperature is also affected by the switching frequency. The maximum junction temperature increases with the switching frequency, however, the minimum junction temperature decreases as the switching frequency increases. In all cases, the junction temperature value remains less than the maximum value allowed for the safety operation of the IGBT.