Magnetic fields spell hope for improved wireless power supply
February 15th, 2010 - 2:56 pm ICT by ANILondon, Feb 15 (ANI): Researchers at the Massachusetts Institute of Technology (MIT) have determined that using magnetic fields to induce a current in a distant device is the most promising approach for wireless power supply.
According to a report in new Scientist, the researchers tune the transmitter and receiver to magnetically resonate at the same frequency to maximize efficiency.
Waves carry energy most effectively between objects that resonate at the same frequency, an effect at work when a singer smashes a nearby glass with the right note.
In 2007, physicist Marin Soljacic’s team reported they could light a 60-watt bulb from across a room.
Now, they have shown that it is possible to power two devices wirelessly when they are placed on either side of a single 1-square-metre coil.
A network analyzer measured the efficiency of the power transfer, while the researchers varied the distance between the source and receivers from 1.6 metres to 2.7 metres.
The researchers found that power transfer was 10 per cent more efficient with two devices receiving rather than one, regardless of how efficient the transfer was to begin with.
Their models suggested that efficiency would be even greater with more devices.
“Because the efficiency boost is always roughly 10 percentage points, the relative improvement is greatest when a lone device is joined by another,” said Andre Kurs, lead author of the research paper on the experiments.
That makes it possible to power a collection of devices with poor individual links, perhaps because they are scattered across a room far from the coil.
“We could have reasonably good efficiency over a room-sized area from a coil embedded in ceiling or a wall in order to power multiple gadgets or devices,” said Kurs.
The efficiency increases because more of the broadcasting coil’s field falls on receptive receivers.
“This is a promising road to full wireless connectivity, not just for signals but also for power,” said electrical engineer Luk Arnaut of Imperial College London. (ANI)
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