Extending the inductor operating frequency for optimally-coupled wireless power transfer systems

This paper presents a technique for extending the operating frequency of an inductive link used for wireless power transfer. The extension is achieved by segmenting the primary inductor. A circuit model is proposed for a single-coil squared inductor, which provides the basis for the model of the segmented inductor. These models help to understand the operation of the segmented inductor and serve as a guide to its design. A prototype of the link was fabricated, in which the primary inductor has an average diameter of 22mm and four segments. The secondary inductor has an average diameter of 4mm and the two inductors are expected to be optimally coupled at the distance of 15 mm. The operating frequency was experimentally validated to be 980MHz which is higher than the 415MHz measured for a conventional inductive link of same dimensions, while the link efficiency is maintained at the same value of 30%.