Researchers at North Carolina State University in conjunction with Carnegie Mellon University have shown that passing wireless power transfer through a magnetic resonance field enhancer (MRFE) increases efficiency by at least 100% as compared to air alone. The MRFE can be something as simple as a copper loop and has the potential to boost efficiency by 5,000% in certain systems. David Ricketts, an associate professor of electrical and computer engineering at NC State and corresponding author of the paper describing the work, says, “Our experimental results show double the efficiency using the MRFE in comparison to air alone.”
“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,” says Ricketts.
Since the major challenge for wireless charging to be mass marketed is its efficiency, this could be considered a world-changing discovery. Or at least a step in that direction. Wireless power transfer works by the transmitter coil generating a magnetic field and the receiver drawing power from that field. While magnetic coupling, or inductive coupling, is being used already, for it to be universally useful, the transfer must be made highly efficient from a greater distance; as of now its highest efficiency is from a few centimeters.
One method of increasing efficiency is the use of metamaterials (MM), artificial structures constructed with particular electromagnetic properties as opposed to the MRFE which can be a simple copper ring. MM have been found to increase efficiency only a fraction compared to MRFE, 9% to 49% percent. Researchers discovered MM, while increasing the magnetic field’s “visibility” to receivers, were also siphoning a substantial amount of power from the system. MRFEs reduce this loss of power significantly. Additionally, MRFEs are about one tenth the volume of their MM counterparts.
“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,” Ricketts says.