Investigation of end-winding proximity losses in electromagnetic devices

This paper presents an investigation into proximity losses in end-windings informed from the 3D finite element analysis of an ac power inductor. The proximity effect in winding conductors is a result of circulating ac currents caused by magnetic fields generated by nearby conductors. The calculated results confirm that the effects within the end-winding whist significant are lower compared to those with the active length of the conductors. The common approach of predicting proximity losses using 2D field analyses accounts for active length of the conductors only, and therefore an end-winding correction factor is needed to obtain a more accurate estimate of loss. The theoretical prediction of losses within the inductor has been validated experimentally on a prototype inductor. The effect of winding temperature on proximity loss is also discussed.