Research Initiation: Combined Thermal-Magnetic Model for Design of High-Frequency Power Transformers

兆赫范围内的开关频率正被用于为下一代计算机和其他应用提供电源的开发。变压器铁心内部产生的热量与频率、局部磁场强度和材料性质成正比。高频设计所需的最小核心体积受到铁心损耗和热因素的限制，但目前还不存在优化设计的方法。本课题在变压器设计中考虑了热磁耦合和强化换热的机理。建立了电力变压器的通用有限元模型，该模型考虑了温度场、磁场、几何和材料特性之间的耦合。该模型将通过电能平衡来确定铁心和绕组损耗，并通过红外热成像来验证，以绘制原型高频电力变压器的表面温度图。这项拟议的研究将改进高频磁体可用的设计工具。这项工作有望首次展示磁场和热场之间的耦合对设计优化的影响。这项工作还将展示通过改善远离变压器的热传递和由此导致的温度水平降低而获得的性能收益。以往的工作完全忽略了强化换热。这项研究的结果将使工业进一步推进电力电子技术。

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.