Future Electric Vehicle to Run Far Beyond

Toyohashi University of Technology
Sept 20, 2011

Electrically powered vehicles (EV) are promising environmentally friendly alternatives for combustion engine-based automobiles. Electric motors offer significant advantages including high energy efficiency; low noise emission; low temperature operation; no emission of exhaust gases; and the possibility of power regeneration from kinetic motion when a vehicle slows down.

However, batteries used in present-day EV limit the continuous running distance from one charge. Furthermore, it takes an impractical long time to recharge the batteries, and loading larger batteries increases the onboard load, which leads to greater consumption of energy to move vehicles. And notably, batteries are too expensive for use in replacing all existing cars, buses, and trucks.

Here, Masahiro Hanazawa at Toyota Central R&D Labs. and Takashi Ohira at Toyohashi University of Technology (Toyohashi Tech) propose a potentially revolutionary solution for powering EVs capable of running unlimited distances. The basic concept stems from electric railways, where each car of the train is power from an overhead wire while the car runs on tracks. The researchers imagined how an automobile running along a road could do so without resorting to dangerous contacting devices such as pantographs, and finally came up with a profound and novel idea: 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.

The researchers conducted feasibility experiments to test their ideas, and to explore the RF frequencies where such power transfer is effective and practical. In the experiments, the researchers put small metal plates on the floor and inside a tire, and positioned another metal plate above the tire. Finally, they measured the electrical impedance between the two plates. This set-up should be equivalent to double the impedance between a plate and a steel belt.
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