Highly Efficient 11.1 kW Wireless Power Transfer Utilizing Nanocrystalline Ribbon Cores

Nanocrystalline alloys have been recently considered as an alternative to ferrite as the magnetic cores in inductive power transfer systems due to their superior properties such as higher saturation flux density and permeability. They are also less brittle, more stable to temperature variations, and have a higher thermal conductivity. To take advantage of these properties, a dedicated design approach is required, different from the one used for ferrite cores. In this paper, special considerations and methods for the design of nanocrystalline ribbon cores are presented. An 11.1 kW pad is designed and compared with one with identical ferrite cores. Results show that IPT pads with nanocrystalline ribbon cores yield superior magnetic performance in terms of inductances and coupling factors. Higher efficiency and power density were also achieved with the proposed design. Furthermore, compared to ferritebased pads, they showed lower leakage flux and a superior stability to temperature variations.