Magnet-based wireless EV charger could be smaller, safer and cheaper

The new magnet-based wireless EV charger system has operated for about a year, avoids the usage of power cords.


"One of the major challenges of electric vehicles is the need to connect cords and sockets in often cramped conditions and in bad weather," said David Woodson, Managing Director of UBC Building Operations. "Since we began testing the system, the feedback from drivers has been overwhelmingly positive—all they have to do is park the car and the charging begins automatically."

Other experts on wireless EV charging technology doubted the ultimate practicality of the UBC development. "It's really nothing new," said John M. Miller, Center Director in the Power Electronics and Electric Machinery Research Group at Oak Ridge National Laboratory in TN. "Too many moving parts; it all comes down to the number of energy conversions that are involved. Here, it goes from electrical to mechanical to electric field and back to mechanical and then to electrical," the electrical engineer explained. Each step entails a loss in energy efficiency that adds up.

A top maker of automotive recharging equipment also was similarly skeptical. "First, let me emphasize that our technology is fully safe," says David Schatz, Vice President of Sales & Business Development at WiTricity in Watertown, MA. "We crossed that threshold two years ago in certifying that to the satisfaction of the carmakers," who must concern themselves with potential liability issues beforehand. "The codes and standards are being written now."

"Leading edge automakers are designing wireless EV technology that will be produced and introduced around 2015 to 2017," he said. The biggest interest is to place them in so-called plug-less hybrids, Schatz continued. In addition, the industry expects the forthcoming devices to "be approaching the size and shape of a sheet of paper and lightweight to boot." WiTricity's power-transfer technology, which has no moving parts, exploits a special-design, high-efficiency coupling between transmitter and receiver—a one-step energy transfer.

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