Researchers at the Tokyo Metropolitan University have designed a rotating benchtop device that simulates wireless charging in electric vehicles (EVs).
The device helped simulate vehicular movement at nearly 25 miles per hour (40 km/h), while transferring 3 kilowatts of power to the receiver unit, the university team says.
Electric vehicles are the future of transportation, offering commuters an environmentally friendly option for last-mile connectivity. Countries are aiming to reduce significant annual emissions by switching from fossil-fuel-powered vehicles to electric vehicles that do not produce tailpipe emissions.
While adoption of EVs is on the rise, there are still hurdles to their widespread use. The battery pack is the most expensive component of an electric vehicle, and to address range anxiety, manufacturers are forced to install even more powerful battery packs, which further increase the vehicle’s price.
Wireless charging: an option
Car manufacturers could potentially reduce the size of the battery pack if EVs can be charged wirelessly. This would help the cars store energy in their battery packs without having to stay stationary at a charging point.
Called dynamic wireless power transfer (DWPT), this technology can be deployed on highways, allowing cars to be recharged as they travel distances. However, testing this technology is also expensive, since it requires transmitter coils to be embedded in the track.
Research laboratories typically do not have the financial bandwidth to build such tracks for research purposes, prompting Ryosuke Ota, an assistant professor at Tokyo Metropolitan University, to devise a benchtop apparatus that could simulate recharging conditions of the track inside the laboratory.
How does the benchtop device work?
The benchtop device is designed to replicate the movement of the EV’s receiving unit over the charger’s transmitter coils. The receiving unit is mounted on a counterbalanced arm that can be precisely moved by a servo motor.
Beneath the arm, the researchers installed a bean-shaped transmitter coil and then simulated the electromagnetic environment that would be generated when the coil was installed on a highway.
By comparing electromagnetic field readings from the test track and the benchtop device, the researchers confirmed that their device accurately simulated the test conditions.
In the prototype, the researchers also examined the mechanical stress as the device was rotated at high speeds. As the movement replicated scenarios of an EV moving at 25 miles per hour (40 km/h), the researchers were keen to see whether nontrivial forces jeopardized its durability or precision.
The researchers demonstrated a power transmission of 3 kW between the coils in their benchtop device. However, more importantly, they were able to study the impact of misalignments between the two coils, which often occur on the road.
Coupling efficiency is critical in determining how much power can be transmitted in such a setup. While attempts have been made to study it before, research in the area remains limited. But a benchtop device could now make it easier to analyze different alignments in more realistic conditions.
The benchtop device not only opens new avenues for DWTP research but also enables smaller research labs to engage in the field of wireless charging, thereby helping advance it rapidly.
The research findings were published in the journal IEEE Open Journal of Vehicular Technology.
