Optimized Winding Layout for Minimized Proximity Losses in Coils With Rod Cores

In many cases, the proximity effect is the dominating loss mechanism in coils with rod cores at high frequencies. Therefore, overall power losses are influenced significantly by the winding layout of the coil. In this paper, we calculate the winding losses of inductors with rod cores, taking into account the two-dimensional field distribution at the wire positions as well as the magnetic fields caused by the eddy currents in adjacent windings. We show that the losses can be reduced by avoiding winding positions close to the ends of the ferrite core. We verify the results by measurements.