Superconducting Coil Pushes Wireless Power Out at Over 5kW — But Keeping It Cool Is a Challenge
Clever coil system shows promise for robotics, healthcare, and even electric vehicles — if you can keep it at a chilly -321°F.
Scientists from Technische Universität München, the Slovak Academy of Sciences, and industry have come up with a new contactless power transmission system based on superconducting wire coils — and claim it can transmit more than five kilowatts without serious losses.
"The basic idea with superconducting coils is to achieve the lowest possible alternating current resistance within the smallest possible winding space and thus to compensate for the reduced geometric coupling," explains first author Christoph Utschick of the work behind the recently-published paper. The trick, though: Avoiding current losses as the surface temperature of the superconducting wires rise.
The team's solution was a novel coil design which separates individual windings with spacers. "This trick significantly reduces alternating current loss in the coil," Utschick explains. "As a result, power transmission as high as the kilowatt range is possible."
The resulting coil design can transmit power entirely wirelessly at an output power of 6kW, with a claimed DC-to-DC efficiency over 97 percent — meaning very little of the power is wasted as a result of the transmission. There's a catch, of course: In order for the superconducting wire to remain superconducting, it has to be kept immersed in a liquid nitrogen bath to maintain a chilly 77 Kelvin temperature (around -321°F).
Despite this, Utschick and colleagues believe the technology has promise for fields including industrial robotics, autonomous vehicles, and medical equipent — and even for electric racing vehicles, which could be charged as they travel around the track.
The team's work is available under open-access terms on arXiv.org.