Wireless energy transfer with high-Q devices at variable distances

• US 8,400,020 B2
• Filed: 12/16/2009
• Issued: 03/19/2013
• 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 Number:
  US12/639,967
• Publication Number:
  US 20100123354A1
• Time in Patent Office: 1,189 Days
• Field of Search: 307/104, 333/195
• US Class Current: 307/104
• 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 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02M 1/0064 Magnetic structures combining different functions, e.g. storage, filtering or transformation
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H04B 5/0037 for power transfer
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. 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 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

Described herein are embodiments of a source high-Q resonator, optionally coupled to an energy source, and a second high-Q resonator, optionally coupled to an energy drain that may be located a variable distance from the source resonator. The source resonator and the second resonator may be coupled to transfer electromagnetic energy from said source resonator to said second resonator over a distance D that is smaller than each of the resonant wavelengths λ₁ and λ₂ corresponding to the resonant frequencies ω₁ and ω₂, respectively.

Claims

1. A system, comprising:

a source high-Q resonator, configured to be coupled to an energy source, the source high-Q resonator having a resonant frequency ω

₁ and an intrinsic loss rate Γ

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

₁/(2Γ

₁); and

a second high-Q resonator, located a variable distance from the source resonator, the second high-Q resonator having a resonant frequency ω

₂ and an intrinsic loss rate Γ

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

₂ (2Γ

₂),

wherein the source resonator and the second resonator are configured to be coupled to wirelessly transfer electromagnetic energy from said source resonator to said second resonator over a distance D that is smaller than each of the resonant wavelengths λ

₁ and λ

₂ corresponding to the resonant frequencies ω

₁ and ω

₂, respectively.

2. The system of claim 1, further comprising the energy source coupled to the source resonator.

3. The system of claim 1, further comprising an energy drain coupled to the second resonator.

4. The system of claim 3, wherein the energy drain comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

5. The system of claim 1, wherein Q₁>

100 or Q₂>

100.

6. The system of claim 5, wherein Q₁>

100 and Q₂>

100.

7. The system of claim 1, wherein √

{square root over (Q₁Q₂)}>

100.

8. The system of claim 1, further comprising a third high-Q resonator, optionally coupled to an energy drain, located at a variable distance from the source resonator, and wherein the source resonator and the third resonator are coupled to wirelessly transfer electromagnetic energy from the source resonator to the third resonator.

9. The system of claim 8, further comprising the energy drain coupled to the third resonator.

10. The system of claim 1, further comprising a third high-Q resonator, optionally coupled to an energy source, located at a variable distance from the second resonator, and wherein the third resonator and the second resonator are coupled to wirelessly transfer electromagnetic energy from the third resonator to the second resonator.

11. The system of claim 1, wherein at least one of the resonators is a tunable resonator.

12. The system of claim 1, wherein the resonators are movable relative to one another and wherein the wireless energy transfer occurs over a range of distances.

13. The system of claim 12, wherein the range of distances includes 5 cm.

14. The system of claim 12, wherein the range of distances includes 10 cm.

15. The system of claim 12, wherein the range of distances includes 30 cm.

16. The system of claim 12, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 over the range of distances, wherein κ

is the wireless energy transfer rate, Γ

₁ is the intrinsic loss rate of the source resonator, and Γ

₂ is the intrinsic loss rate of the second resonator.

17. The system of claim 16, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.5 over the range of distances.

18. The system of claim 16, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1 over the range of distances.

19. The system of claim 12, wherein the efficiency of the wireless energy transfer is at least 20% over the range of distances.

20. The system of claim 1, wherein the resonant frequencies f₁=ω

₁/2π and

f₂=ω

₂/2π

are each at least 5 MHz.

21. The system of claim 1, further comprising a feedback mechanism coupled to at least one of the resonators to correct for detuning.

22. The system of claim 1, wherein the energy source is coupled to the source resonator, an energy drain is coupled to the second resonator, and wherein the energy source and energy drain are configured to be driven to increase the ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the source resonator and the second resonator.

23. The system of claim 1, wherein the source resonator and second resonator are configured to be adjustably tuned to increase the ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the source resonator and the second resonator.

24. The system of claim 1, wherein the source resonator and the second resonator have different characteristic sizes.

25. A method, comprising:

providing a source high-Q resonator configured to be coupled to an energy source and a second high-Q resonator, wherein the second high-Q resonator is located a variable distance from the source resonator,

the source high-Q resonator having a resonant frequency ω

₁ and an intrinsic loss rate Γ

₁, and capable of storing electromagnetic energy with a high intrinsic quality factor Q₁=(2Γ

₁) and the second high-Q resonator having a resonant frequency ω

₂ and an intrinsic loss rate Γ

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

₂/(2Γ

₂),

wherein the source resonator and the second resonator are configured to be coupled to wirelessly transfer electromagnetic energy from said source resonator to said second resonator over a distance D that is smaller than each of the resonant wavelengths λ

₁ and λ

₂ corresponding to the resonant frequencies ω

₁ and ω

₂, respectively.

26. The method of claim 25, wherein the energy source is coupled to the source resonator.

27. The method of claim 25, wherein an energy drain is coupled to the second resonator.

28. The method of claim 27, wherein the energy drain comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

29. The method of claim 25, wherein Q₁>

100 or Q₂>

100.

30. The method of claim 29, wherein Q₁>

100 and Q₂>

100.

31. The method of claim 25, wherein √

{square root over (Q₁Q₂)}>

100.

32. The method of claim 25, wherein a third high-Q resonator, optionally coupled to an energy drain, is located at a variable distance from the source resonator, and wherein the source resonator and the third resonator are coupled to wirelessly transfer electromagnetic energy from the source resonator to the third resonator.

33. The method of claim 32, wherein the energy drain is coupled to the third resonator.

34. The method of claim 25, wherein a third high-Q resonator, optionally coupled to an energy source, is located at a variable distance from the second resonator, and wherein the third resonator and the second resonator are coupled to wirelessly transfer electromagnetic energy from the third resonator to the second resonator.

35. The method of claim 25, wherein at least one of the resonators is a tunable resonator.

36. The method of claim 25, wherein the resonators are movable relative to one another and wherein the wireless energy transfer occurs over a range of distances.

37. The method of claim 36, wherein the range of distances includes 5 cm.

38. The method of claim 36, wherein the range of distances includes 10 cm.

39. The method of claim 36, wherein the range of distances includes 30 cm.

40. The method of claim 36, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 over the range of distances, wherein κ

is the wireless energy transfer rate, Γ

₁ is the intrinsic loss rate of the source resonator, and Γ

₂ is the intrinsic loss rate of the second resonator.

41. The method of claim 40, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.5 over the range of distances.

42. The method of claim 40, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1 over the range of distances.

43. The method of claim 36, wherein the efficiency of the wireless energy transfer is at least 20% over the range of distances.

44. The method of claim 25, wherein the resonant frequencies f₁=ω

₁/2π and

f₂=ω

₂/2π

are each at least 5 MHz.

45. The method of claim 25, wherein a feedback mechanism is coupled to at least one of the resonators to correct for detuning.

46. The method of claim 25, wherein the energy source is coupled to the source resonator, an energy drain is coupled to the second resonator, and wherein the energy source and energy drain are driven to increase the ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the source resonator and the second resonator.

47. The method of claim 25, wherein the source resonator and second resonator are adjustably tuned to increase the ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the source resonator and the second resonator.

48. The method of claim 25, wherein the source resonator and the second resonator have different characteristic sizes.