Analytical Modeling of Plate Fin Heat Sinks for Natural Convection Cooling in Power Electronics

Natural convection cooling offers advantages such as low cost, high reliability, noiseless operation and positioning independent from other cooling circuits. Since the main disadvantage is a relatively low heat transfer, an analytic model is required to efficiently design natural convection heat sinks according to the applied design constraints. This paper describes a natural convection thermal model which can be applied to parallel plate heat sinks in order to find an optimum heat sink design. First, the theoretical model was applied to different commercially available heat sink profiles, from which the most suitable profile was chosen for an inverter prototype. As a reference, FEM simulations were performed. Thermal measurements were carried out to validate the model. Then, the achieved thermal performance was compared to the theoretical optimum design. It was found out that described model predicts the resulting heat sink temperatures with a practical accuracy compared to measurements. Therefore, the approach described in this paper is a mathematically simple and validated model for the design of natural convection heat sinks. Furthermore, with an optimum design the heat sink volume can be reduced by 45% compared to a commercially available heat sink profile.