Thermal management of compact nanocrystalline inductors for power dense converters

Enhanced thermal management continues to be the key to the miniaturisation of high-frequency magnetic components and to increased converter power densities. Thermal finite element analysis has been used to examine the use of high-thermal-conductivity ceramic heat spreaders in the potted structure of a nanocrystalline-cored DC inductor to mitigate the local temperature rise due to the concentrated gap losses. The thermal performance of different heat spreader and potting materials has also been investigated. The heat spreader technique is validated by experimental results on two 350 A, 60 kHz DC inductors, showing a hot spot temperature reduction of 20 °C with embedded aluminium nitride heat spreaders, which may allow a smaller core to be used. By using the heat spreaders about 30 % weight reduction is illustrated for a higher frequency DC inductor design (300 A, 150 kHz). Furthermore, the impact of the potting compound's thermal conductivity is studied, revealing that a size reduction of up to 50% is possible with the heat spreaders in addition to an improved potting material.