Wireless energy transfer over distances to a moving device

• US 8,766,485 B2
• Filed: 12/30/2009
• Issued: 07/01/2014
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Joannopoulos, John D., Karalis, Aristeidis, Soljacic, Marin
• Primary Examiner(s): Fleming, Fritz M
• APPLICATION: US 20100187911A1
• Time in patent office: 1644 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: B60L 11/182 by inductive energy transfer
• CPC Class Codes: B60L 53/126 Methods for pairing a vehicle and a charging station, e.g. establishing a one-to-one relation between a wireless power transmitter and a wireless power receiver
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H01Q 9/04 Resonant antennas
• CPC Class Codes: H02J 17/00 Systems for supplying or distributing electric power by electromagnetic waves
• CPC Class Codes: H02J 5/005 with inductive power transfer for charging H02J7/025
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7005 Batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/7088 Charging stations
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/122 by inductive energy transmission
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

Described herein are embodiments of a source resonator coupled to an energy source generating an oscillating near field region; and at least one device resonator optionally coupled to at least one energy drain and freely moving within the near field region of the source resonator. The source resonator and the at least one device resonator may be coupled to transfer electromagnetic energy wirelessly from said source resonator to said at least one device resonator as the at least one device resonator moves freely within the near field region, where the source resonator and the at least one device resonator may be coupled to provide κ/sqrt(Γ₁Γ₂)>0.2 over an operating region.

Claims

1. A system, comprising:

a source resonator configured to be coupled to an energy source to generate a near field region comprising a temporally oscillating magnetic field; and

at least one device resonator configured to be freely moving within the near field region of the source resonator,

wherein the source resonator and the at least one device resonator are configured to be coupled to transfer electromagnetic energy wirelessly from said source resonator to said at least one device resonator at a rate κ

as the at least one device resonator moves freely within the near field region when the source resonator is coupled to the energy source,

wherein the source resonator has a resonant frequency ω

₁, an intrinsic loss rate Γ

₁, and is capable of storing electromagnetic energy with a high intrinsic quality factor Q₁=ω

₁/(2Γ

₁), and

wherein the device resonator has a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and is capable of storing electromagnetic energy with a high intrinsic quality factor Q₂=ω

₂/(2Γ

₂), and

wherein κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than the characteristic size L₂ of the device resonator, and

wherein Q₁>

100 and Q₂>

100.

2. The system of claim 1, wherein each resonator comprises an electrical conductor shaped into one or more loops wound in substantially a single plane circumscribing a substantially planar area.

3. The system of claim 2, wherein the loops of the electrical conductors of each of the source and device resonators are in substantially the same plane.

4. The system of claim 2, wherein a line drawn from the center of the source resonator to the center of the at least one device resonator is substantially normal to the circumscribed planar area of each resonator.

5. The system of claim 2, wherein a line drawn from the center of the source resonator to the center of the at least one device resonator is substantially parallel to the circumscribed planar area of each resonator.

6. The system of claim 2, wherein a line drawn from the center of the source resonator to the center of the at least one device resonator forms a different angle to the surface area circumscribed by the source resonator than to the circumscribed planar area of each resonator.

7. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than twice the characteristic size L₂ of the device resonator.

8. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than three times the characteristic size L₂ of the device resonator.

9. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than five times the characteristic size L₂ of the device resonator.

10. The system of claim 9, wherein the resonator have quality factors Q₁ and Q₂ satisfying √

{square root over (Q₁Q₂)}>

100.

11. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than the characteristic size L₂ of the device resonator.

12. The system of claim 11, wherein the resonator have quality factors Q₁ and Q₂ satisfying √

{square root over (Q₁Q₂)}>

100.

13. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than twice the characteristic size L₂ of the device resonator.

14. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than three times the characteristic size L₂ of the device resonator.

15. The system of claim 1, wherein κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than five times the characteristic size L₂ of the device resonator.

16. The system of claim 1, wherein the resonator have quality factors Q₁ and Q₂ satisfying √

{square root over (Q₁Q₂)}>

100.

17. The system of claim 1, further comprising an energy drain coupled to the at least one device resonator.

18. The system of claim 17, wherein the energy drain comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

19. The system of claim 1, further comprising the energy source configured to be coupled to the source resonator and an energy drain configured to be coupled to the at least one device resonator to provide useful power to the energy drain, and wherein the energy source is configured to provide energy to the source resonator at a rate that varies with the rate of wireless energy transfer κ

between the source resonator and the at least one device resonator.

20. The system of claim 19, wherein the energy source is configured to provide energy to the source resonator at a rate that substantially minimizes the energy stored in the source resonator and the at least one device resonator.

21. The system of claim 19, wherein the energy source is configured to provide energy to the source resonator at a rate that substantially maximizes a ratio of the useful power to lost power from the energy source to the energy drain.

22. The system of claim 1, wherein f₁=ω

₁/(2π

) and f₂=(ω

₂/(2π

), and each of f₁ and f₂ is between about 5 MHz and 380 MHz.

23. The system of claim 1, wherein each intrinsic loss rate comprises a resistive component and a radiative component.

24. A method, comprising:

providing a source resonator coupled to an energy source and generating a near field region comprising a temporally oscillating magnetic field; and

providing at least one device resonator coupled to at least one energy drain and freely moving within the near field region of the source resonator,

wherein the source resonator and the at least one device resonator are coupled to transfer electromagnetic energy wirelessly from said source resonator to said at least one device resonator at a rate κ

as the at least one device resonator moves freely within the near field region,

wherein the source resonator has a resonant frequency ω

₁, an intrinsic loss rate Γ

₁, and is capable of storing electromagnetic energy with a high intrinsic quality factor Q₁=ω

₁/(2Γ

₁), and

wherein the device resonator has a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and is capable of storing electromagnetic energy with a high intrinsic quality factor Q₂=ω

₂/(2Γ

₂), and

wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than the characteristic size L₂ of the device resonator, and

wherein Q₁>

100 and Q₂>

100.

25. The method of claim 24, wherein each resonator comprises an electrical conductor shaped into one or more loops wound in substantially a single plane circumscribing a substantially planar area.

26. The method of claim 25, wherein the loops of the electrical conductors of each of the source and device resonators are in substantially the same plane.

27. The method of claim 25, wherein a line drawn from the center of the source resonator to the center of the at least one device resonator is substantially normal to the circumscribed planar area of each resonator.

28. The method of claim 25, wherein a line drawn from the center of the source resonator to the center of the at least one device resonator is substantially parallel to the circumscribed planar area of each resonator.

29. The method of claim 25, wherein a line drawn from the center of the source resonator to the center of the at least one device resonator forms a different angle to the surface area circumscribed by the source resonator than to the circumscribed planar area of each resonator.

30. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than twice the characteristic size L₂ of the device resonator.

31. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than three times the characteristic size L₂ of the device resonator.

32. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

0.2 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than five times the characteristic size L₂ of the device resonator.

33. The method of claim 32, wherein the resonator have quality factors Q₁ and Q₂ satisfying √

{square root over (Q₁Q₂)}>

100.

34. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than the characteristic size L₂ of the device resonator.

35. The method of claim 34, wherein the resonator have quality factors Q₁ and Q₂ satisfying √

{square root over (Q₁Q₂)}>

100.

36. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than twice the characteristic size L₂ of the device resonator.

37. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than three times the characteristic size L₂ of the device resonator.

38. The method of claim 24, wherein the source resonator and the at least one device resonator are coupled to provide κ

/sqrt(Γ

₁Γ

₂)>

1 as the at least one device resonator moves freely within the near field region over distances from source resonator larger than five times the characteristic size L₂ of the device resonator.

39. The method of claim 24, wherein the resonator have quality factors Q₁ and Q₂ satisfying √

{square root over (Q₁Q₂)}>

100.

40. The method of claim 24, wherein each intrinsic loss rate comprises a resistive component and a radiative component.