Wireless Resonant Energy Link (WREL)

screen capture of video of magnetically coupled resonators
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WREL uses coupled magnetic resonators to wirelessly transfer power safely and efficiently to mobile devices and consumer electronics. Our research focuses on extending range, improving efficiency, and demonstrating a clear pathway to integration in mobile systems.



netbook powered by WREL
A netbook directly powered by WREL. Note that the battery pack has been removed.

Coupled Magnetic Resonance

Coupled magnetic resonance is a near-field phenomenon where power transfer can be highly efficient between the source and receiver with negligible coupling to environmental objects.

In conventional inductive coupling, efficiency drops off as 1/distance3. Charging mats and wireless toothbrushes use these methods and can only transfer appreciable power when the receiving device is within a few millimeters.

In contrast, WREL can deliver tens of watts of power over several feet with > 80% efficiency.



magic regime 3D graph
Power transfer efficiency can be nearly constant within the "magic regime."

The Magic Regime

Coupled resonator systems with sufficiently high-Q coils exhibit a surprising behavior: power transfer efficiency can be maximal and nearly independent of distance and orientation. In this regime, which typically extends several feet for our frequency and coil designs, the system is said to be over-coupled.

We call this regime the "magic regime," though, since it is what fundamentally differentiates this technology. The extent of the magic regime, which is bounded by a critical coupling point, is a key figure of merit which can be used to compare performance of disparate implementations.



Cutting the Last Cord

diagram of power transfer
Main power transfer occurs between two tightly coupled resonators.

Wireless power offers the potential for notebook computers and mobile phones to require less frequent charging.

Eliminating power cords could free up desktop space and remove clutter in offices and living spaces.

Additionally, wireless power offers the potential to eliminate connectors and reduce the size of batteries, which could lead to new mobile device form factors.

Our current research focuses on:

  • Optimizations to increase efficiency, range and orientation invariance to create a seamlessly mobile experience
  • Integration of wireless power systems into mobile and consumer electronics device platforms
  • Association strategies for delivering power from one ore more source nodes to multiple devices with disparate power requirements

Project Team
Alanson Sample, UW EE
Ben Waters, UW EE
Joshua Smith, (PI) UW CSE & EE