Researchers from North Carolina State University have developed a new technology for wireless power transmission that could bring the goal of dynamic wireless EV charging a step closer to reality.
“We’ve made changes to both the receiver and the transmitter in order to make wireless energy transfer safer and more efficient,” says Dr. Srdjan Lukic, an assistant professor of electrical engineering at NC State and senior author of a paper on the research.
The researchers developed a series of segmented transmitter coils, each of which broadcasts a low-level electromagnetic field, and a receiver coil that is the same size as each of the transmitter coils (coils of the same size transfer energy more efficiently).
The researchers modified the receiver so that when it comes into range and couples with a transmitter coil, that specific transmitter coil automatically increases its current, boosting its magnetic field strength and the related transfer of energy by 400 percent. The transmitter coil’s current returns to normal levels when the receiver passes out of range.
One previous approach used large transmitter coils, but this created a powerful and imprecise field that could couple to the frame of a car or other metal object, which raised safety concerns and reduced system efficiency. Another approach used smaller transmitter coils, which addressed safety and efficiency concerns, but would require a large number of transmitters to cover a section of roadway, adding substantial cost and requiring very precise vehicle position detection technology. “We tried to take the best from both of those approaches,” Lukic says.
Lukic and his team have developed a small working prototype of their system, and are now working to scale it up and increase the power. Currently, the system can transmit energy at a rate of up to 0.5 kW. “Our goal is to move from 0.5 kW into the 50 kW range,” Lukic says.