Core and air gap influence on the accuracy of inductor AC winding resistance calculation methods

This paper discusses the accuracy of typical AC resistance calculation methods in gapped inductors. It is shown that despite the additional losses caused by fringing flux induced eddy currents, the calculated resistances can be overestimated considerably due to non-tangential field distribution and reduced winding proximity losses. However, this phenomenon is not so significant with windings having only a few winding layers; in such cases 1D calculation methods can be useful in predicting the winding resistances. It is also demonstrated how the fringing flux induced losses affect the calculated results and how they can be taken into account when using the 1D methods.