Masahiro Hanazawa of Toyota Central R&D Labs and Takashi Ohira from Toyohashi University are working on a solution for avoiding battery recharge headaches in powering electric cars. They are working on a prototype of electric cars that are powered by the road itself–electric roads for electric cars. While the idea of cars powered from the ground is not new, the system that they propose is an interesting way to power electric cars as the cars travel along the road through steel belts placed inside tires and a metal plate in the road.
Toyohashi University newsletter report describes their system: “The source of energy from power lines is up-converted into radio frequency (RF) by high-speed inverters implanted along tracks in the road. The RF voltage is applied to a balanced metal track embedded under the surface of the road. The EV picks up the RF voltage via electrical capacitance between the metal and a steel belt installed inside of the tires of the EV.”
In their experiments, the researchers put small metal plates on the floor and inside a tire, and positioned another metal plate above the tire. They measured the electrical impedance between the two plates. The team presented their work in May at the International Microwave Workshop Series on Innovative Wireless Power Transmission in Kyoto, Japan. While their tests involved low voltages, the researchers believe energy transfer from the road to a running automobile is feasible. With enough power the system could run typical passenger cars, says Ohira.
Their system would require smaller battery packs, rather than heavier packs, to get back and forth from electrified highways, which is viewed as a benefit as well.