Tokyo, Japan – Scientists from Tokyo Metropolitan University have devised a rotating tabletop device to study wireless charging in electric vehicles. Testing on real tracks takes up vast areas at significant cost. The team not only built a prototype but used simulations to demonstrate safety and similar charging to a linear track. They successfully reproduced movement at 40 kilometers per hour, promising accelerated global research into next-gen charging for EVs.
Electric vehicles (EVs) are a cornerstone of global sustainability initiatives. Combined with renewable energy, the goal is to significantly cut carbon emissions through a phase out of fossil-fuel-powered cars. But EVs face an uphill struggle, largely due to their cost and range. To stretch travel range, EVs require more battery storage, making them even more expensive.
To get around this problem, researchers have been looking into dynamic wireless power transfer (DWPT), charging vehicles while they are moving on roads. If EVs could be charged while they are traveling, the battery capacity they need will be significantly less. Specifically, a transmitter coil is buried under roads, while a receiver unit on the vehicle passing over it will be able to charge.
While this is an elegant solution, it is a notoriously difficult problem to study for practical reasons. To test charging of vehicles moving at speed, you would usually need a test track to install transmitter coils. Not only is this costly, but it takes up a lot of space which smaller facilities, particularly academic institutions, will not have.
To bring the testing of DWPT from the test track into the lab, a team led by Assistant Professor Ryosuke Ota have implemented a rotating device which replicates the passage of charging systems on vehicles over transmitter coils, an increasingly popular testing concept in recent research. A receiving unit is mounted on a counterbalanced arm which is rotated by a servo motor; a bean-shaped transmitter coil is then installed below the path of the arm. Through simulations of electromagnetic fields, they were able to show that the transmitter coil produced a field which was comparable to those made by coils on linear tracks. As they designed their prototype, they also carefully assessed the mechanical stress in their device as it was rotated at high speeds, finding that it was a practical testing bed for DWPT in settings comparable to a real EV.
The team were able to address important questions such as how the coupling between transmitter and receiver changes when they are misaligned. They were able to replicate conditions of a car moving at 40 kilometers per hour, with a power transmission of 3 kilowatts. While similar results have been achieved before on the benchtop, the design principles for the device and the evaluation framework the team have introduced promise to significantly accelerate research into DWPT systems, so that they might one day leap back from the lab into real roads.
This work was partially supported by the TEPCO Memorial Foundation.
IEEE Open Journal of Vehicular Technology
24-Dec-2025