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Powering Down

Thayer team develops energy-saving device

On Mar. 7 at the Applied Power Electronics Conference (APEC) in Austin, Texas, the  U.S. Environmental Protection Agency (EPA) and  the California Energy Commission announced the  winners of Efficiency Challenge 2004, an  international design competition for power supply  efficiency. The winners included Thayer School of  Engineering Ph.D. candidates Jennifer D. Pollock  (project leader), Xi Nan, and Satish Prabhakaran,  and M.S. candidate Magdalena Dale. Associate  Professor of Engineering Charles Sullivan served  as faculty advisor for the team.

The winning Thayer team, front row from left: Magdalena Dale, Xi Nan, and Jennifer Pollock.  Back row, from left:  Charles Sullivan, Satish Prabhakaran (photo by Katie Tippit)

The Dartmouth entry, called "Big Green," was a  litz wire high-frequency transformer designed to  power an office phone and computer. The entry won  "Best in Class" in the Open Category which  showcases the most efficient power supply designs  from industry and academia without cost or  packaging constraints. "Power supplies of a  similar type generally hover at 60 percent  efficiency, and the Dartmouth team showed that 88  percent efficiency is possible," said Chris  Calwell, Efficiency Challenge judge. "We  congratulate them for their outstanding design."

Open Category entries were received from  companies and universities in the United States,  Taiwan, and Hong Kong. Said Professor Sullivan,  "The overall winner in the 'open category' was  Hong Kong Polytechnic University. Although Hong  Kong had lower efficiency than we did, they chose  to attempt a more difficult class, in which they  could get more points for lower  efficiency...Dartmouth's entry was outstanding,  even when compared only to the other winners.  Congratulations to Jenna, Xi, Satish, and  Magdalena."

More than 3.1 billion power supplies are  currently in use in the United States. Power  supplies are devices that convert incoming AC  (alternating current) power from wall outlets  into low voltage DC (direct current) power needed  for numerous consumer and office electronic  products. In most power supplies, the magnetic  components-transformers and inductors-are  responsible for the most energy loss and are the  largest, most expensive and most difficult to  design. EPA has identified AC-DC power supplies  as a major opportunity for reducing global energy  consumption and estimates that efficient external  power supplies alone could save the United States  5 billion kWh per year, equivalent to preventing  the emissions of 700,000 cars.

"The vision for Efficiency Challenge was to  achieve dramatic improvements in the energy  efficiency of the most widely purchased types of  power supplies," said Art Rosenfeld, California  Energy Commissioner and presiding member of its  research and development committee.

Visit  the Efficient Power Supplies website  for more information.

By CATHARINE LAMM

Questions or comments about this article? We welcome your feedback.

Last Updated: 12/17/08