Reducing local concentrated gap loss of a nanocrystalline core by applying alloy gap

An alloy gap is used in the place of air gap to mitigate the concentrated gap loss of nanocrystalline core of an LCL filter inductor in a high frequency converter. A finite element analysis (FEA) model has been developed to examine the performance of the proposed method and validated by experiments. Based on FEA results, the maximum eddy current loss density can be reduced by around 89% and 69% for two different winding placements, respectively. The total eddy current loss of the air-gapped inductor can be reduced by 29% and 27% with gap winding placement and side winding placement respectively by applying an alloy gap. As a result, the hotspot temperature can be reduced corresponding to a lower and more uniform loss distribution.