Recharging without stopping

June 05, 2014

Researchers at NC State have been working on an exciting new technology that would make electric cars much more attractive. Their final goal is to create a highway station where electric vehicles can drive by and be recharged without having to stop.

Dr. Srdjan Lukic, assistant professor of electrical engineering, and his team have developed a small, functional prototype of their system. Now, they are working to scale it up and increase the power of the system. The new approach improves on previous mobile, wireless power transfer techniques.

"We've made changes to both the receiver and the transmitter in order to make wireless energy transfer safer and more efficient," Lukic said. "We tried to take the best from both of those approaches." Demonstration of the prototype. 
Demonstration of the prototype.

One previous approach involved using large transmitter coils. However, this created a powerful and imprecise field that could potentially couple to the frame of a car or other metal objects passing through the field. These electromagnetic field leaks raised safety concerns and reduced system efficiency.

Another approach used smaller transmitter coils. In this scenario, a very large number of transmitters were required to effectively cover a section of the roadway. An increased number of transmitters added substantial cost and complexity to the system and also required very precise vehicle position detection technology.

At peak efficiency, the new system can transmit energy at a rate of 0.5 kilowatts (kW).

"Our goal is to move from 0.5 kW into the 50 kW range," Lukic said. "That would make it more practical."

Researchers will continue to improve upon this innovative technique. The new approach could lead to a large increase in the number of electric cars on the road. Who wouldn't want to drive a car that didn't need to be refueled?

Credit: From NC State Engineering Spring 2014 Magazine feature "Recharging without stopping."