Researchers Demonstrate Wireless Power

Jun 13, 2007 3:41 PM
By Mark Valentine, Technical Editor, Power Electronics Technology

A combined research team at The Massachusetts Institute of Technology (MIT) has demonstrated a process referred to as WiTricity, to wirelessly transmit electrical power at ranges usable for indoor applications. This introduces the possibility of a practical system for eliminating wires for recharging portable electronics, the initial inspiration for the concept.

In addition to improving the convenience of charging portable devices, the elimination of cords enabled by WiTricity can also improve the safety and aesthetics of stationary appliances, such as floor lamps and table lamps. Furthermore, given the challenge of achieving regulatory compliance for electrical safety in medical power supplies (such as for patient-leakage requirements), the technology may have tremendous possibilities in bioinstrumentation. According to Robert Moffatt, research team member and undergraduate in physics at MIT, the system might even be made to work in underwater environments with careful engineering.

Figure. MIT has demonstrated wireless power transmission from the coil on the left to the coil on the right, where it powers a 60-W light bulb. Members of the team that performed the experiment are, front row: Peter Fisher (left) and Robert Moffatt; second row: Marin Soljacic; third row: Andre Kurs (left), John Joannopoulos,and Aristeidis Karalis.

The WiTricity system uses a process referred to as magnetically coupled resonance, in which non-radiating magnetic fields perform the transfer of energy. Because the system uses magnetic fields rather than electromagnetic radiation, such as microwaves, calculations show that it is possible to build a WiTricity system that complies with IEEE’s safety standards for general population exposure. The energy transfer process between the source and load is also omni-directional, so line-of-sight obstructions, such as normal room traffic, do not affect operation.

To emphasize these aspects of operation, the members of the research team that developed the concept are pictured in the Figure with the system in operation. Note that a few of the team members are directly in the line of sight between the transmitter and receiver as the system powers a conventional incandescent light bulb.

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