A Japanese university has developed a new wireless power supply technology for cars that can supply power even through 10cm thick concrete

Toyohashi University of Technology demonstrated electric field coupled wireless power supply technology using life-size car tires and roads at the wireless technology exhibition "Wireless Technology Park (WTP) 2012" held at the Pacifico Yokohama International Convention Center from July 5 to 6.

Practical demonstrations using life-size wheels and road concrete.

The research group of Professor Ohira Takashi of the Department of Electrical, Electronics and Information Engineering at the university is studying the use of electric field coupling (or inductive coupling) wireless power supply technology to power moving cars.

This publication differs from the previous publications of the research team in two aspects: (1) a large power of 50 to 60 W is transmitted to a life-size wheel; and (2) there is a concrete layer of about 10 cm thick between the metal plate on the power transmission side and the wheel. The power transmission efficiency between the metal plate under the ordinary concrete simulating the road and the light bulb installed on the side of the wheel is "as high as 80 to 90% or more" (Ohira).

In particular, Ohira said that regarding (2), "it is expected that power can be supplied even when the thickness of concrete exceeds 20 cm (commonly used in actual roads)" because the dielectric constant of concrete is high. Although the power to be transmitted in actual use will increase by two digits compared to this demonstration, "the relevant parts are relatively cheap and there will be no major impact."

Details of the wheel

An example of charging a model car. The wheels can still turn even through 10cm thick concrete.