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.