Wireless energy transfer with high-Q similar resonant frequency resonators

• US 8,400,022 B2
• Filed: 12/23/2009
• 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:
  US12/646,442
• Publication Number:
  US 20100096934A1
• Time in Patent Office: 1,182 Days
• Field of Search: 307/104, 333/195, 320/108
• 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 transferring electromagnetic energy that includes providing a first electromagnetic resonator structure receiving energy from an external power supply, said first resonator structure having a first mode with a resonant frequency ω₁, an intrinsic loss rate Γ₁, and a first Q-factor Q₁=ω₁/(2Γ₁), providing a second electromagnetic resonator structure being positioned distal from said first resonator structure and not electrically wired to the first resonator structure, said second resonator structure having a second mode with a resonant frequency ω₂, an intrinsic loss rate Γ₂, and a second Q-factor Q₂=ω₂/(2Γ₂), and transferring electromagnetic energy from said first resonator structure to said second resonator structure over a distance D that may be smaller than each of the resonant wavelengths λ₁ and λ₂ corresponding to the resonant frequencies ω₁ and ω₂, respectively. The electromagnetic resonator structures may be designed to have Q₁>100 and Q₂>100. The absolute value of the difference of said angular frequencies ω₁ and ω₂ may be smaller than the magnitude of the coupling rate, κ.

Claims

1. A method of transferring electromagnetic energy comprising:

providing a first electromagnetic resonator receiving energy from a power supply, said first resonator having a first mode with a resonant frequency ω

₁, an intrinsic loss rate Γ

₁, and a first Q-factor Q₁=ω

₁/(2Γ

₁);

providing a second electromagnetic resonator being positioned distal from said first resonator and not electrically wired to the first resonator, said second resonator having a second mode with a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and a second Q-factor Q₂=ω

₂/(2Γ

₂); and

transferring electromagnetic energy wirelessly from said first resonator to said second resonator over a distance D that is smaller than each of resonant wavelengths λ

₁ and λ

₂ corresponding to the resonant frequencies ω

₁ and ω

₂, respectively,

wherein the electromagnetic resonators are designed to have √

{square root over (Q₁Q₂)}>

100; and

wherein the absolute value of the difference of said resonant frequencies ω

₁ and ω

₂ is smaller than a magnitude of the wireless energy transfer rate, κ

.

2. The method of claim 1, wherein an energy drain is coupled to the second electromagnetic resonator.

3. The method of claim 2, wherein the energy drains comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

4. The method of claim 1, wherein Q₁>

100.

5. The method of claim 1, wherein Q₂>

100.

6. The method of claim 1, wherein Q₁>

100 and Q₂>

100.

7. The method of claim 1, wherein a third electromagnetic resonator, optionally coupled to an energy drain, is located at a variable distance from the first electromagnetic resonator, and wherein the first electromagnetic resonator and the third electromagnetic resonator are coupled to wirelessly transfer electromagnetic energy from the first electromagnetic resonator to the third electromagnetic resonator.

8. The method of claim 7, wherein the energy drain is coupled to the third electromagnetic resonator.

9. The method of claim 1, wherein a third electromagnetic resonator, optionally coupled to another power supply, is located at a variable distance from the second electromagnetic resonator, and wherein the third electromagnetic resonator and the electromagnetic second resonator are coupled to wirelessly transfer electromagnetic energy from the third electromagnetic resonator to the second electromagnetic resonator.

10. The method of claim 1, wherein at least one of the electromagnetic resonators is a tunable resonator.

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

12. The method of claim 11, wherein the range of distances include 5 cm.

13. The method of claim 11, wherein the range of distances includes 10 cm.

14. The method of claim 11, wherein the range of distances includes 30 cm.

15. The method of claim 11, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 over the range of distances.

16. The method of claim 15, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.5 over the range of distances.

17. The method of claim 15, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1 over the range of distances.

18. The method of claim 11, wherein an efficiency of the wireless energy transfer is at least 20% over the range of distances.

19. The method of claim 1, wherein resonant frequencies f₁=ω

₁/2π and

f₂=ω

₂/2π

are each at least 5 MHz.

20. The method of claim 1, wherein a feedback mechanism is coupled to at least one of the resonators to correct for detuning.

21. The method of claim 1, wherein an energy drain is coupled to the second electromagnetic resonator, and wherein the power supply and energy drain are driven to increase a ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the first electromagnetic resonator and the second electromagnetic resonator.

22. The method of claim 1, wherein the first electromagnetic resonator and second electromagnetic resonator are adjustably tuned to increase a ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the first electromagnetic resonator and the second electromagnetic resonator.

23. The method of claim 1, wherein the first electromagnetic resonator and the second electromagnetic resonator have different characteristic sizes.

24. A system of transferring electromagnetic energy comprising:

a first electromagnetic resonator receiving energy from a power supply, said first resonator having a first mode with a resonant frequency ω

_l, an intrinsic loss rate Γ

₁, and a first Q-factor Q₁=ω

₁/(2Γ

₁); and

a second electromagnetic resonator being positioned distal from said first resonator and not electrically wired to the first resonator, said second resonator having a second mode with a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and a second Q-factor Q₂=ω

₂/(2Γ

₂),

wherein electromagnetic energy is wirelessly transferred from said first resonator to said second resonator over a distance D that is smaller than each of resonant wavelengths λ

₁ and λ

₂ corresponding to the resonant frequencies ω

₁ and ω

₂, respectively,

wherein the electromagnetic resonators are designed to have √

{square root over (Q₁Q₂)}>

100; and

wherein the absolute value of the difference of said resonant frequencies ω

_l and ω

₂ is smaller than a magnitude of the wireless energy transfer rate, κ

.

25. The system of claim 24, further comprising an energy drain coupled to the second resonator.

26. The system of claim 25, wherein the energy drain comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

27. The system of claim 24, wherein Q₁>

100.

28. The system of claim 24, wherein Q₂>

100.

29. The system of claim 24, wherein Q₁>

100 and Q₂>

100.

30. The system of claim 24, further comprising a third electromagnetic resonator, optionally coupled to an energy drain, located at a variable distance from the first electromagnetic resonator, and wherein the first electromagnetic resonator and the third electromagnetic resonator are coupled to wirelessly transfer electromagnetic energy from the first electromagnetic resonator to the third electromagnetic resonator.

31. The system of claim 30, further comprising the energy drain coupled to the third electromagnetic resonator.

32. The system of claim 24, further comprising a third electromagnetic resonator, optionally coupled to another power supply, located at a variable distance from the second electromagnetic resonator, and wherein the third electromagnetic resonator and the second electromagnetic resonator are coupled to wirelessly transfer electromagnetic energy from the third electromagnetic resonator to the second electromagnetic resonator.

33. The system of claim 24, wherein at least one of the electromagnetic resonators is a tunable resonator.

34. The system of claim 24, wherein the electromagnetic resonators are movable relative to one another and wherein the wireless energy transfer occurs over a range of distances.

35. The system of claim 34, wherein the range of distances includes 5 cm.

36. The system of claim 34, wherein the range of distances includes 10 cm.

37. The system of claim 34, wherein the range of distances includes 30 cm.

38. The system of claim 34, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 over the range of distances.

39. The system of claim 38, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

0.5 over the range of distances.

40. The system of claim 38, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1 over the range of distances.

41. The system of claim 34, wherein an efficiency of the wireless energy transfer is at least 20% over the range of distances.

42. The system of claim 24, wherein resonant frequencies f₁=ω

_1/2π and

f₂=ω

₂/2π

are each at least 5 MHz.

43. The system of claim 24, further comprising a feedback mechanism coupled to at least one of the resonators to correct for detuning.

44. The system of claim 24, wherein an energy drain is coupled to the second electromagnetic resonator, and wherein the power supply and energy drain are configured to be driven to increase a ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the first electromagnetic resonator and the second electromagnetic resonator.

45. The system of claim 24, wherein the first electromagnetic resonator and second electromagnetic resonator are configured to be adjustably tuned to increase a ratio of useful-to-lost power for varying wireless energy transfer rates κ

between the first electromagnetic resonator and the second electromagnetic resonator.

46. The system of claim 24, wherein the first electromagnetic resonator and the second electromagnetic resonator have different characteristic sizes.