Ferrite-Less Circular Pad With Controlled Flux Cancelation for EV Wireless Charging

In this paper, a new ferrite-less wireless charging pad, called circular nonferrite pad, for roadway applications is introduced. The pad is characterized by having the ability to control leakage flux to reduce the electromagnetic fields outside the charging region. In addition, the pad shows low sensitivity to changes in the self-inductance due to secondary pad misalignment. A comparison of this new pad with similar-sized ferrite pads and single spiral couplers is presented. A formal mathematical description of the pad is shown here with finite element method simulations along with lab measurements to verify the validity of the models. The costs, advantages, and limitations of the new pad are also investigated.