Modeling and Analysis of Thermal Resistances and Thermal Coupling Between Power Devices

The recent trend in the design of the high-power density power converter generally reduces the rate of the device cooling process. As a result, increased thermal coupling among devices exists. Based on measurements, a thermal coupling resistances network (TCRN) model is proposed in this article. Considering different spacings and current values at a fixed value of case temperature ( {T} _{\text {c}} ), the relationships between the case-to-ambient thermal resistance ( {R} _{\text {ca}} ) of individual power devices and their thermal coupling resistance ( {R} _{\text {cp}} ) to the adjacent device are established. The close correspondence of {T} _{\text {c}} from the calculation of the different spacing and experimental results obtained from a thermal coupling measurement platform confirms the established TCRN model and the relationships. Traditional thermal models do not consider the changes of {R} _{\text {ca}} and also ignore the effect of thermal coupling among the adjacent devices. Compared with these models, the proposed thermal resistances modeling approach provides a better understanding of the thermal behavior of power devices.