Appliance Design - March 2009 - (Page 18)

POWER in this area. When developing this idea, Soljacic theorized that if close-range induction coupling was efficient in transferring power, than it might be possible to transfer energy over longer distances. In June, Soljacic and his colleagues demonstrated the technology using two, 60-cm copper coils, which were designed to resonate together at 10MHz and were oriented along the same axis. By running current through the transmitting coil, an electromagnetic field was generated. The field crossed 7 ft. to the second coil, which converted the energy into electricity. With this power, they were able to light a 60 W bulb. However, the efficiency of the transfer was not great. At a distance of 7 ft., the power efficiency was about 45 percent. By reducing the distance to about 3 ft., energy transfer neared 80 percent. Most of the energy that did not transfer was reabsorbed by the transmitting coil. The technology has been spun off into WiTricity, which is currently working with OEMs to develop products based on Soljacic’s work. WiTricity has designed systems that can transfer power at distances several times the diameter of the coils, says David Schatz, director of business development and marketing. The system can transfer power from milliwatts to kilowatts. As with the RF broadcast systems, efficiency varies by distance. If the coils are separated by half a meter, the efficiency can approach 90 percent, says Schatz. In the field, that number may drop sharply. Movement of the receiving unit can also add to the challenge, but Schatz says The future of a home might include multiple power hot spots that will transfer energy to various appliances. Graphic: Fulton Innovation. colors • textures special effects functionality color consulting & technical service 2nd generation bonded metallics large or small volumes custom colors, fast global partnership …any questions? colorworksforyou AD08084Tige.indd 1 www.tiger-coatings.com 800.243.8148 7/14/08 11:08:51 AM that the resonant technology helps to better direct the magnetic fields. The amount of power that can be broadcast was evident by the number of devices that were directly powered during CES. Schatz says that the WiTricity technology can be embedded into a variety of products and systems. He says that the physics of resonant inductive coupling enables WiTricity engineers to design power sources and devices of varying shapes and sizes, to match both the packaging requirements and the power transfer requirements for a given OEM application. Intel is using the resonant coupling technology to develop products under its Wireless Energy Resonant Link (WERL) program. Joshua Smith, an Intel researcher and senior application engineer, says the goal is to develop a product to efficiently transfer tens of watts or power with variable geometry between the transmitter and receiver. In August, the company demonstrated the use of a resonant inductive field to light a 60 W bulb from about 3 ft. It lost about 25 percent of the power in the transmission. The coil size was about 12 in., which Smith says is a size that could fit into the lid of a laptop computer. For smaller electronics, the antennas would also need to be smaller, and receivers are under development for various applications. Intel’s chief technology officer, Justin Rattner, has said that the technology could be embedded in tables and work surfaces so that they can start to charge when an appliance is brought into a room or if it is put down on an appropriately equipped device. While this broadcast technology continues its advancement, and new products begin to enter the market, broadcast technology still faces hurdles for larger implementation. These issues include efficiency, electromagnetic interference, and safety. Some of these concerns are more perception than reality, but either way, the suppliers have devoted many resources to them. Efficiency is critical for through-the-air power transfer. With even the best technology topping out at between 70 and www.applianceDESIGN.com 18 applianceDESIGN March 2009 http://www.tiger-coatings.us/ http://www.tiger-coatings.us/ http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - March 2009

Appliance Design - March 2009 Contents Editorial Shipments/Forecasts News Watch Transmitting Power Wirelessly Promises to Reduce the Ever-Growing Tangle of Cords and Cables Found in the Modern Home. There Are Different Technological Approaches for Achieving this Goal, and Some Are Already on the Market. Electrochemical Capacitors Can Provide an Extra Peak-Power Boost in Battery-Operated Appliances, Allowing Product Designs to Have Smaller Battery Packs. Metallic Foams Put the Properties of Metals into Lightweight Packages. Applications for this Emerging Technology Include Gas Burners, Heat Exchangers, and Electronics Housings. Hall-Effect Switches Are Compact and Provide a High Degree of Reliability and Durability as They Virtually Eliminate Mechanical Wear, Shock, and Contact Oxidation. Blowing Agents for Polyurethane Foam Insulation Face Increased Scrutiny Due to Global Warming Concerns, but Alternatives with Lower GWP Values May Provide Solutions to Meet These Challenges. Design Marts Association Report: AHAM Advertisers' Index

Appliance Design - March 2009

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