Switching frequencies in the megahertz range are being used in the development of power supplied for the next-generation computers and other applications. The internal heat generation in a transformer core is proportional to frequency, local magnetic field strength and material properties. The minimum core volume required for a high- frequency design is limited by core loss and thermal considerations, yet no method for design optimization currently exists. This project considers the mechanisms of thermal-magnetic coupling and enhanced heat transfer for transformer design. A generic finite-element model of a power transformer that accounts for coupling between the temperature field, magnetic field, geometry and material properties will be developed. The model will be validated by an electrical energy balance to determine core and winding losses, and by infrared thermal imaging to map the surface temperatures of prototype high- frequency power transformers. The proposed research will improve the design tools available for high-frequency magnetics. This work is expected to show for the first time the impact of coupling between the magnetic and thermal fields on design optimization. This work will also demonstrate the performance gains obtainable through improved heat transfer away from the transformer and the resulting decrease in temperature level. Previous work has neglected heat transfer enhancement altogether. The results of this research will allow industry to further advance power electronics technology.
