Improved AC-Resistance of Multiple Foil Windings by Varying Foil Thickness of Successive Layers

Abstract

Abstract: A novel optimization strategy for planar inductor design, based on a per-layer approach for calculation of the optimal foil thickness is presented in this paper. Implementation of this strategy results in reduced ac- and dcresistance of the winding. Inductor windings optimized for sinusoidal excitation were constructed and the resistance measured. Results are shown for air core inductors and the performance of the same windings in gapped magnetic cores is also reported. An optimisation technique for non-sinusoidal excitation is also proposed. Air gap proximity losses can be reduced by notching the winding in the region of the air gap. This technique combined with the newly proposed layer optimisation strategy is also investigated for a trapezoidal current waveform