Tokyo Metropolitan University Designs Rotating Table Device for Researching Wireless Charging of Electric Vehicles

According to foreign media reports, scientists from Tokyo Metropolitan University have developed a rotating desktop device for studying wireless charging of electric vehicles. Conducting tests on real tracks requires substantial space and is costly. In addition to building a prototype, the team used simulation technology to verify its safety and demonstrated charging performance comparable to that achieved with linear tracks. They successfully simulated operation at a speed of 40 km/h, potentially accelerating global research into next-generation electric vehicle charging technologies.

The relevant paper was published in the journal "IEEE Open Journal of Vehicular Technology".

Source: Tokyo Metropolitan University

Electric vehicles are the cornerstone of global sustainability initiatives. In conjunction with renewable energy, the goal is to significantly reduce carbon emissions by phasing out gasoline-powered vehicles. However, electric vehicles face numerous challenges, primarily due to their cost and range. To extend the range, electric vehicles require larger battery capacities, which further drives up their cost.

To solve this problem, researchers have been exploring dynamic wireless power transfer (DWPT) technology, which charges vehicles while they are in motion. If electric vehicles can be charged while driving, the required battery capacity can be significantly reduced. Specifically, the transmitting coils are embedded beneath the road, and the receiving unit on vehicles passing over the road can be charged.

Although this is a clever solution, it is extremely difficult to study in practice. To test the charging situation of vehicles traveling at high speeds, a test track is usually required to install the transmitting coils. This is not only costly but also takes up a large amount of space, which many smaller institutions, especially academic institutions, often lack.

To transfer DWPT testing from test tracks to the laboratory, a team led by Assistant Professor Ryosuke Ota developed a rotating device that simulates the process of a vehicle’s charging system passing over a transmitting coil—a testing concept that has become increasingly popular in recent research.

The receiver unit is mounted on a balance arm rotated by a servo motor; the bean-shaped transmitting coil is installed beneath the balance arm. Through electromagnetic field simulation, the research team demonstrated that the magnetic field generated by this transmitting coil is comparable to that produced by linear track coils.

When designing the prototype, the research team carefully evaluated the mechanical stress during high-speed rotation, and the results showed that it was a practical DWPT testing platform with an environment comparable to real electric vehicles.

The research team also addressed several key issues, such as how the coupling between the transmitter and receiver changes when they are misaligned. The team also simulated a scenario where a car travels at 40 km/h with a power transfer of 3 kilowatts.

Although similar results have previously been achieved in laboratory settings, the design principles of the device and the evaluation framework proposed by the team are expected to significantly accelerate research on DWPT systems, enabling them to move from the lab to real-world roads someday.