Dielectric coupling from electrified roadway to steel-belt tires characterized for miniature model car running demonstration

This paper demonstrates the feasibility of the wireless power transfer using dielectric coupling between a steel belt in a tire and a metal plate in a roadway. The scheme is called Tire Dielectric Coupling. We designed and prototyped the feeding subsystem using 1/32 scale models. The feeding subsystem is constructed of metal plates, tires and steel belts. We measured S-parameter of the feeding subsystem. As results, S₁₁ is -0.06 dB and S₂₁ is -30.3 dB. With the S-parameter, we built an equivalent circuit model of the feeding subsystem at a wide frequency range in VHF band. We designed and prototyped impedance matching circuits based on an equivalent circuit technique. After tuning, measured S₂₁ of the feeding subsystem with the impedance matching circuits achieved -1.2 dB. This result is as high efficiency as charge/discharge efficiency of lithium-ion battery.