A new approach for transmitting power wirelessly to electric automobiles could bring the development of highway stations capable of powering fast-moving vehicles closer to reality.
Researchers at North Carolina State University have developed new techniques for transferring power to moving electric vehicles that improves on previous methods. The team designed a series of segmented transmitter coils that broadcast a low-level electromagnetic field and a receiver coil of a similar size that can be placed in a mobile car or other moving platform. According to the researchers, the size of the coils is important because coils of the same size transfer energy more efficiently.
In addition, the researchers modified an existing receiver so that its electric current automatically increases when it comes into range and couples with a transmitter coil. When coupled with the receiver, the transmitter coil’s current increases, boosting its magnetic field strength and energy transfer rate by 400 percent. When the receiver coil passes out of range, the transmitter coil’s current returns to normal levels.
“We’ve made changes to both the receiver and the transmitter in order to make wireless energy safer and more efficient,” said Dr. Srdjan Lukic, Ph.D., an assistant professor of electrical engineering at NC State and senior author of a paper on the research, said in a press release from NC State University.
Scientists have previously tried to develop such a system, but these earlier attempts employed the use of large transmitter coils, which created a strong and imprecise field that posed the risk of coupling with metal objects passing through it. Another approach used smaller coils, but the number of transmitters required to cover a section of roadway was deemed too expensive.
With the newest system, “we tried to take the best from both of those approaches,” Lukic said.
The researchers are currently working to increase both the size and power of their small existing prototype. The system currently transmits energy at a rate of 0.5 kW, but Lukic and his colleagues hope to increase it to a more practical level in the 50 kW range.