UF engineers: Wireless charger provides efficient cord-free charging

Published: December 12 2007

Category:Engineering, Research, Technology

GAINESVILLE, Fla. — Good news about that annoying jumble of electronic device charger power cords — it may soon be history.

researchers have built and successfully tested a pad that can charge cell phones, PDAs, laptops and other electronic devices via wireless technology. Rather than plug in the electronics to different cords and outlets, users simply place them anywhere atop the flat, thin pad, where they begin charging automatically.

The researchers are not the first to design a wireless charging device — in fact, at least four small companies, including one based around the UF research — are competing to bring a charger to market. Some products are expected to reach store shelves as soon as next year.

But the UF team says its device is unusually efficient, transmitting an average of about 70 percent of the power flowing from the outlet to the devices’ batteries. The team has filed paperwork for seven patents on the technology in the past three months.

“Our advantage is that thanks to a new transmitter design, we can achieve high power charging with high efficiency,” said , a UF professor of .

With today’s electronic devices requiring separate cords, consumers are all too familiar with confronting a tangled mess of wires, not to mention the inconvenience that comes with forgetting one cord or another while traveling. That’s why researchers and companies are working so hard to design and market a universal charging device that requires only one plug — for its own power. It’s anticipated that companies could sell as many as 1.9 billion chargers each year, according to one company official.

But the technical challenges are significant.

Electrical engineers have to figure out how to transmit power uniformly to a broad range of devices that operate at different power levels. They also have to design receivers that are cheap, small and uniform enough to be added on — and eventually fit into — everything from the tiniest cell phone to the most powerful laptop.

The UF researchers began working on the problem in 2006, when Ryan Tseng, a former electrical and computer engineering undergraduate, made it a senior design project and his honors thesis research. Lin was Tseng’s adviser on his research.

Tseng, now an MBA student at the , later founded a company, Florida-based to sell a charge pad device. WiPower has provided funds to sponsor the continued UF research, with the contributing matching funds.

Lin said his research team, led by UF doctoral student Zhen Ning Low, have made rapid progress on the charge pad, broadening its charging ability from cell phones to laptops while also making it considerably more efficient.

Key steps have included a redesign of the internal electronic architecture of the transmitter, as well as an adaptive power control mechanism that varies charging power based on the type of device and distance from the pad, Lin said.

The researchers demonstrated the device using a digital picture frame that displays photos stored in a memory stick. A video showed how the frame — which usually has to be plugged in to turn on — began displaying pictures and videos once it was moved to within an inch or so above the pad. The researchers also demonstrated the pad charging a standard cell phone and a receiver-equipped light bulb that turned on when placed near the pad

Lin said the UF charger differs from others because it transmits nearly as much power as its standard wired counterparts. The most efficient wired transmitter sends about 90 percent of the power tapped from the wall, while the UF wireless transmitter can average 70 percent. Lin said he thinks he will be able to boost that average, even eclipsing the wired level. The more efficient the devices, the less consumers will pay for electricity.

Hurdles include making the pads — and the needed receivers — hardier and useful in a bigger variety of devices. The chargers and receivers must be standardized, a difficult problem because it will require cooperation among scores of electronic-device manufacturers. To sell their chargers, companies will have to persuade manufacturers to include receivers.

“The biggest problem is standardization,” Tseng said. “If you can standardize, the chicken-and-egg issues should be minimized. Look at Bluetooth and WiFi.”

Those challenges aside, Lin said he envisions a day when charge pads could be included in, for example, desk furniture or seat back tray tables in airliners. “Hopefully in the future we can create something like WiFi,” he said, “except it becomes wireless power.”


Aaron Hoover, ahoover@ufl.edu, 352-392-0186
Zhen Ning Low, znlow@ufl.edu, 352-870-8181

Category:Engineering, Research, Technology