Wireless power transfer boosted by magnetic field enhancer

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Research shows that passing wireless power transfer through a magnetic resonance field enhancer (MRFE) can boost the transfer efficiency by at least 100 per cent compared to transferring through air.

MRFE use could potentially boost transfer efficiency by as much as 5,000 per cent in some systems, said experts from from North Carolina State University and Carnegie Mellon University.

Wireless power transfer works by having a transmitter coil generate a magnetic field; a receiver coil then draws energy from that magnetic field. One of the major roadblocks for development of marketable wireless power transfer technologies is achieving high efficiency.

“Our experimental results show double the efficiency using the MRFE in comparison to air alone,” said David Ricketts, an associate professor of electrical and computer engineering at NC State and corresponding author of a paper describing the work.

From left to right are: performance of wireless power transfer using an MRFE, a metamaterial, and through air alone
From left to right are: performance of wireless power transfer using an MRFE, a metamaterial, and through air alone

Enhancing wireless power efficiency has been a major goal of many research groups and metamaterials have been the leading candidates proposed for enhancing efficiency.

“We performed a comprehensive analysis using computer models of wireless power systems and found that MRFE could ultimately be five times more efficient than use of metamaterials and 50 times more efficient than transmitting through air alone,” Ricketts said in a statement.

By placing the MRFE between the transmitter and the receiver (without touching either) as an intermediate material, the researchers were able to enhance the magnetic field, increasing its efficiency.

“We realised that any enhancement needs to not only increase the magnetic field the receiver ‘sees,’ but also not siphon off any of the power being put out by the transmitter,” said Ricketts. “The MRFE amplifies the magnetic field while removing very little power from the system.”

The researchers conducted an experiment that transmitted power through air alone, through a metamaterial, and through an MRFE made of the same quality material as the metamaterial. The MRFE is said to have significantly outperformed both of the others. In addition, the MRFE is less than one-tenth the volume of metamaterial enhancers.

“This could help advance efforts to develop wireless power transfer technologies for use with electric vehicles, in buildings, or in any other application where enhanced efficiency or greater distances are important considerations,” said Ricketts.

A pre-proof draft of the paper, ”Magnetic field enhancement in wireless power with metamaterials and magnetic resonant couplers,” is published online in IEEE Antennas and Wireless Propagation Letters.