Determination of average heat transfer coefficient value in compact thermal models

The investigations presented in this paper illustrate the problem of modelling the average value of the convective heat transfer coefficient in the case of a free convection cooled power device with a heat sink. The total junction-to-ambient thermal resistance is dominated then by its component reflecting the heat exchange with the ambient at outer surfaces of the heat sink. Therefore, the proper modelling of this physical phenomenon is crucial for the accurate prediction of device junction temperature. Based on obtained temperature measurement results an empirical formula is proposed allowing the determination of the average heat transfer coefficient value in function of the heat sink surface temperature rise.