Energy efficient heat sink design: Natural vs. forced convection cooling

In highly efficient converter systems the power consumption of the cooling system (fans) significantly influences the total system efficiency as well as the power density. This paper investigates the potential of free convection cooled heat sinks and compares their performance to forced convection cooled heat sinks on the basis of their volume and power consumption. Underlying theoretical concepts for both types of cooling systems are summarized and validated with prototype heat sinks. Finally, it is shown that by free convection cooling not only the efficiency but also the power density can be increased in specific cases. In this case by paralleling semiconductor devices the losses decrease approximately by a factor of three while simultaneously the heat sink volume can be reduced by approximately 50%.