Low-frequency WPT technologies based on moving magnets are developed by a few research groups and one startup company around the world.

Since 2010, Professor David Arnold from the University of Florida (USA) began to develop electrodynamic wireless power transfer (EWPT), building on his expertise on electromagnetic vibrational energy harvesters. Based on electromagnetic transductions, the technical solutions evolved over the years from cantilever based resonant EWPT [1][2], to torsional resonant EWPT [3] and continuous rotating EWPT [4][5].

In parallel, around 2009, Professor Lorne Whitehead from the University of British Columbia (UBC, Canada) developed the magnetodynamic coupling WPT (MDC WPT) [6]. This technology is based on two coupled rotating magnets forming a magnetic gear. In 2013, an UBC spin-out, Elix Wireless, was created to develop and to commercialize charging systems based on this principle. This startup is mainly focused on the autonomous vehicle segment and proposes solutions with transfer capability up to 8 kW [7].

Recently, in 2018, Professor Shad Roundy from University of Utah developed an hybrid WPT technology called magneto-mechanoelectric WPT including both an electromagnetic transduction (transmitter to receiver coupling) and a piezoelectric transduction (internal to the receiver) [8][9].

Finally, since 2019, in continuity to his work with Pr Arnold at the University of Florida, Dr Nicolas Garraud is actively conducting research with Dr Sébastien Boisseau to develop WPT activities at LETI, a research institute on electronics and information technologies of the CEA (French alternative energies and atomic energy commission) in France.

References:

[1] V R Challa et al., "Wireless power transmission to an electromechanical receiver using low-frequency magnetic fields", Smart Mater. Struct. 21 115017, 2012

[2] V R Challa et al., "The role of coupling strength in the performance of electrodynamic vibrational energy harvesters", Smart Mater. Struct. 22 025005, 2013

[3] K M McEachern et al., "Electrodynamic wireless power transmission to a torsional receiver", J. Phys.: Conf. Ser. 476 012004, 2013

[4] A Garraud et al., "Electrodynamic wireless power transmission to rotating magnet receivers", J. Phys.: Conf. Ser. 557 012136, 2014

[5] N Garraud et al., "Modeling and experimental analysis of rotating magnet receivers for electrodynamic wireless

power transmission", J. Phys. D: Appl. Phys. 52 185501, 2019

[6] L Whitehead, "Systems and methods for dipole enhanced inductive power transfer", US Patent US9071062, 2015

[7] Elix Wireless website: www.elixwireless.com.

[8] B D Truong et al., "Wireless power transfer system with center-clamped magneto-mechanoelectric (MME) receiver: model validation and efficiency investigation", Smart Mater. Struct. 28 015004, 2019

[9] B D Truong et al., "Experimentally validated model and analytical investigations on power optimization for piezoelectric-based wireless power transfer systems", J. Intell. Mater. Syst. and Struct., 30 (16), 2464, 2019