Researchers at the University of British Columbia (UBC) led by Dr. Lorne Whitehead in the Sustainability Solutions Applied Physics Laboratory have developed a low-frequency wireless power transfer (WPT) technology based on the magneto-dynamic coupling (MDC) of two rotating permanent magnets in transmitter and receiver, rather than on resonant inductive technology.
The system, according to the UBC team, can transfer power across a wide air gap at high efficiency and at low frequency and has successfully been demonstrated for the wireless charging of a fleet of electric vehicles run by UBC Building Operations with the support of a Natural Sciences and Engineering Research Council of Canada (NSERC) Idea to Innovation Grant (I2I).
The rotation of a magnet in the transmitting unit causes a second magnet in the receiving unit—which also experiences that rotating magnetic field to rotate in a synchronized manner. The rotating second magnet then generates an electric current.
Power can be transferred through metal without significant loss of performance, and the system is also tolerant to significant misalignment between the transmitter and receiver, removing the need for precise alignment mechanisms. Transmitter units are controlled by very simple electronic wiring and components, providing the potential for simpler and therefore lower-cost construction.
Tests show the system is more than 90% efficient compared to a cable charge. A full charge takes four hours and enables the vehicle to run throughout an eight-hour shift.
As power transfer occurs at such a low frequency, and in such a localized area, there is almost no risk of interference with other high frequency wireless devices and systems in homes and workplaces. Perceived potential health risks of exposure to high-frequency electromagnetic fields associated with other wireless technologies may pose a barrier to their adoption. This is not a factor with the low-frequency UBC wireless technology.
In December 2011, the first wireless charging station was installed at the UBC Building Operations site. This fully automated system performed successfully in a variety of weather conditions including snow, rain and sub-zero temperatures, and has since been rolled out in multiple vehicles in the fleet, utilizing improved designs to the charging unit and occupying a smaller footprint than competing technologies.
UBC is interested in exploring collaborative opportunities regarding the technology.