Rapid Thermal Analysis of Nanocrystalline Inductors for Converter Optimization

To capitalize fully on modern component technologies such as nanocrystalline cores and wide bandgap devices, multi-objective converter design optimization is essential, requiring simple and accurate component models. In this article, a lumped parameter (LP) thermal model is presented for nanocrystalline inductors with ceramic heat spreaders. The key challenge is the nonuniform loss distribution in gapped, tape-wound cores, particularly the high loss densities adjacent to the gaps. However, uneven loss distributions are not handled easily by the LP techniques. It is shown that by treating the ceramic heat spreaders as “passive” heat sources, a simple thermal model of the inductor can be derived to estimate the hot-spot temperature of the core. The model is validated through comparison to 3-D finite element analysis (FEA) and experimental measurements on a 60-kW dc-dc converter. The proposed model offers a comparable level of accuracy to the FEA with a fraction of the running time, executing in 99μs in MATLAB.