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UBC wireless power transfer technology uses magneto-dynamic coupling rather than inductive technology

24 November 2012

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.

November 24, 2012 in Brief | Permalink | Comments (11) | TrackBack (0)

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Comments

Dr Rube is paging Dr Goldberg!

Looks not so tiny as described. What would be manufacturing and integration cost?

A rotating permanent magnet is a quadrature coil pair minus the resistance losses.

Looks clever to me, but also like a throwback to another era.  Power transfer is proportional to peak flux times frequency, or something like that.  I'm not quite sure what's optimized in this case.

The UBC charging system is clever and practical...though power transfer through permanent magnets isn't new. Here's a simplified version I developed 5 years ago:
"Faucet Powered Head Lamp Generator"
http://www.youtube.com/watch?v=9DOzgSOFh_4

Too complex, too many moving parts & subject to wear, low overall efficiency (90%) and probably more costly than recent induction units.

On the positive side = less radiated high frequency energy?

Wireless, even misaligned, non-high frequency expense, year+(2013 Jan.), 90%+ power transfer in actual fleet operation seems a damn good start.

Do people accept 10% waste when filling their gasoline tank ? Is plugging in a cable such a chore ?

philippe, just forgetting to plugin and being unable to get to work once could make wireless recharge seem attractive.

Cars are getting smart enough that they could beep at you if you walk away without plugging it in, or send a text message to your phone.

I think the real issue is going to come with V2G, which the wireless schemes can't support as well (or maybe at all).

Engineer-Poet, owners may come to ignore alerts if they occur whenever the charge is below 100 or X%.

"I think the real issue is going to come with V2G.." is interesting, because sending battery charge to the grid could leave the EV too discharged at an unprogrammed time(.. emergency, unplanned travel,..).

The magneto-dynamic coupling seems more compact than resonant inductive coil systems and two spinning magnets may be reliable. Perhaps transfer can be refined to ~99%.

V2G would mostly be used for regulation, not peak-shaving.  Changing SOC by ±2% on top of the normal charging curve wouldn't affect usage of the vehicle significantly, and squeezing more value out of the battery during its calendar lifetime helps everything.

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