Wireless non-radiative energy transfer

• US 8,022,576 B2
• Filed: 03/31/2009
• Issued: 09/20/2011
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Karalis, Aristeidis, Soljacic, Marin, Joannopoulos, John D.
• Primary Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US12/415,650
• Publication Number:
  US 20090195332A1
• Time in Patent Office: 903 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 5/79 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

The electromagnetic energy transfer device includes a first resonator structure receiving energy from an external power supply. The first resonator structure has a first Q-factor. A second resonator structure is positioned distal from the first resonator structure, and supplies useful working power to an external load. The second resonator structure has a second Q-factor. The distance between the two resonators can be larger than the characteristic size of each resonator. Non-radiative energy transfer between the first resonator structure and the second resonator structure is mediated through coupling of their resonant-field evanescent tails.

Claims

1. A method for wirelessly providing electromagnetic power to a load comprising:

providing a first electromagnetic resonator structure receiving power from an power supply, said first resonator structure having a 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 structure being positioned distal from said first resonator structure and not electrically wired to the first resonator structure, said second resonator structure coupled to the load and having a mode with a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and a second Q-factor Q₂=ω

₂/(2Γ

₂), and

wirelessly providing electromagnetic power from said first resonator structure to said second resonator structure 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,

wherein the electromagnetic resonator structures are designed to have (√

{square root over (Q₁Q₂)})>

100 .

2. The method of claim 1, wherein said first resonator structure comprises a capacitively-loaded conducting-wire loop, where the radius of the loop defines a characteristic size L₁ for the first resonator structure.

3. The method of claim 1, wherein said second resonator structure comprises a capacitively-loaded conducting-wire loop, where the radius of the loop defines a characteristic size L₂ for the second resonator structure.

4. The method of claim 1, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2.

5. The method of claim 4, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

6. The method of claim 5, wherein D/L₂>

5.

7. The method of claim 4, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

8. The method of claim 7, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

9. The method of claim 8, wherein D/L₂>

5.

10. The method of claim 1, wherein D>

1 cm.

11. The method of claim 1, wherein D>

30 cm.

12. The method of claim 1, wherein D>

1 m.

13. The method of claim 1, wherein the first resonator structure has a characteristic size L₁ and the second resonator structure has a characteristic size L₂, and D/L₁>

1 and D/L₂>

1.

14. The method of claim 1, further comprising applying a feedback mechanism to at least one of the resonator structures to correct for detuning of its resonant frequency.

15. The method of claim 1, wherein the first and second resonator structures are movable relative to one another.

16. The method of claim 1, wherein Q₁>

100.

17. The method of claim 16, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

18. The method of claim 17, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

19. The method of claim 18, wherein D/L₂>

5.

20. The method of claim 17, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

21. The method of claim 20, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

22. The method of claim 21, wherein D/L₂>

5.

23. The method of claim 1, wherein Q₂>

100.

24. The method of claim 23, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

25. The method of claim 24, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

26. The method of claim 25, wherein D/L₂>

5.

27. The method of claim 24, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

28. The method of claim 27, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

29. The method of claim 28, wherein D/L₂>

5.

30. The method of claim 1, wherein Q₁>

200.

31. The method of claim 30, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

32. The method of claim 31, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

33. The method of claim 32, wherein D/L₂>

5.

34. The method of claim 31, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

35. The method of claim 34, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

36. The method of claim 35, wherein D/L₂>

5.

37. The method of claim 1, wherein Q₂>

200.

38. The method of claim 37, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

39. The method of claim 38, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

40. The method of claim 39, wherein D/L₂>

5.

41. The method of claim 38, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

42. The method of claim 41, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

43. The method of claim 42, wherein D/L₂>

5.

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

₁/2π and

f₂=ω

₂/2π

are each at least 5 MHz.

89. The method of claim 1, wherein the power supply and load are driven to increase the ratio of useful-to-lost power for the wireless energy transfer.

92. The method of claim 1, wherein the second resonator structure and the load are part of a mobile wireless receiver.

93. The method of claim 92, wherein the mobile wireless receiver is a robot, a cell phone, a vehicle, or a computer.

44. A system for wirelessly providing power to a load, the system comprising:

a first electromagnetic resonator structure configured to receive power from a power supply, said first resonator structure having a mode with a resonant frequency ω

₁, an intrinsic loss rate Γ

₁, and a first Q-factor Q₁=ω

₁(2Γ

₁), and

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 configured to be coupled to the load and having a mode having a resonant frequency ω

₂, said second resonator structure having a second mode with a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and a second Q-factor Q₂=(2Γ

₂),

wherein said first resonator is configured to wirelessly transfer electromagnetic energy 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,

wherein the electromagnetic resonator structures are designed to have (√

{square root over (Q₁Q₂)})>

100 .

45. The system of claim 44, wherein said first resonator structure comprises a capacitively-loaded conducting-wire loop, where the radius of the loop defines a characteristic size L₁ for the first resonator structure.

46. The system of claim 44, wherein said second resonator structure comprises a capacitively-loaded conducting-wire loop, where the radius of the loop defines a characteristic size L₂ for the second resonator structure.

47. The system of claim 44, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

48. The system of claim 47, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

49. The system of claim 48, wherein D/L₂>

5.

50. The system of claim 47, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

51. The system of claim 50, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

52. The system of claim 51, wherein D/L₂>

5.

53. The system of claim 44, wherein D>

1 cm.

54. The system of claim 44, wherein D>

30 cm.

55. The system of claim 44, wherein D>

1 m.

56. The system of claim 44, wherein the first resonator structure has a characteristic size L₁ and the second resonator structure has a characteristic size L₂, and D/L₁>

1 and D/L₂>

1.

57. The system of claim 44, further comprising a feedback mechanism coupled to at least one of the resonator structures to correct for detuning of its resonant frequency.

58. The system of claim 44, wherein the first and second resonator structures are movable relative to one another.

59. The system of claim 44, wherein Q₁>

100.

60. The system of claim 59, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

61. The system of claim 60, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

62. The system of claim 61, wherein D/L₂>

5.

63. The system of claim 60, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

64. The system of claim 63, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

65. The system of claim 64, wherein D/L₂>

5.

66. The system of claim 44, wherein Q₂>

100.

67. The system of claim 66, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

68. The system of claim 67, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

69. The system system of claim 68, wherein D/L₂>

5.

70. The system of claim 67, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

71. The system of claim 70, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

72. The system of claim 71, wherein D/L₂>

5.

73. The system of claim 44, wherein Q₁>

200.

74. The system of claim 73, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

75. The system of claim 74, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

76. The system of claim 75, wherein D/L₂>

5.

77. The system of claim 74, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

78. The system of claim 77, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

79. The system of claim 78, wherein D/L₂>

5.

80. The system of claim 44, wherein Q₂>

200.

81. The system of claim 80, wherein the rate of energy transfer from said first resonator structure to said second resonator structure is denoted by κ

, and wherein the resonator structures are designed to have Q₁ and Q₂ satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

0.2 .

82. The system of claim 81, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

83. The system of claim 82, wherein D/L₂>

5.

84. The system of claim 81, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1.

85. The system of claim 84, wherein the second resonator structure has a characteristic size L₂ and D/L₂>

1.

86. The system of claim 85, wherein D/L₂>

5.

88. The system of claim 44, wherein the resonant frequencies f₁=ω

₁/2π and

f₂=ω

₂/2π

are each at least 5 MHz.

90. The system of claim 44, further comprising the power supply coupled to the first resonator and the load coupled to the second resonator.

91. The system of claim 90, wherein during operation the power supply and load are driven to increase the ratio of useful-to-lost power for the wireless energy transfer.

94. The system of claim 90, wherein the second resonator and the load are part of a mobile wireless receiver.

95. The system of claim 94, wherein the mobile wireless receiver is a robot, a cell phone, a vehicle, or a computer.

96. The system of claim 44, wherein at least one of the resonators is tunable.

97. The system of claim 44, wherein each of the electromagnetic resonators comprises a capacitance and an inductance.

98. A mobile wireless receiver for use with a first electromagnetic resonator coupled to a power supply, the first resonator having a mode with a resonant frequency ω

an intrinsic loss rate Γ

₁, and a first Q-factor Q₁=ω

₁/(2Γ

₁), the mobile wireless receiver comprising;

a load; and

a second electromagnetic resonator configured to be coupled to the load and movable relative to the first resonator, the second resonator having a mode with a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and a second Q-factor Q₂=ω

₂/(2Γ

₂),

wherein the second resonator is configured to be wirelessly coupled to the first resonator to provide resonant non-radiative wireless power to the second resonator from the first resonator with a wireless energy transfer rate κ

, and

wherein (√

{square root over (Q₁Q₂)})>

100 .

99. The receiver of claim 98, wherein Q₂>

100.

100. The receiver of claim 98, wherein the second resonator is tunable.

101. The receiver of claim 98, wherein the mobile wireless receiver is a robot, a cell phone, a vehicle, or a computer.

102. The receiver of claim 98, wherein the resonant frequency f₂=ω

₂/2π

is at least 5 MHz. the resonant frequencies.

103. The receiver of claim 98, wherein during operation the load is driven to increase the ratio of useful-to-lost power for the wireless energy transfer.

104. The receiver of claim 98, wherein the second resonator comprises a capacitance and an inductance.

105. A power source for wirelessly providing power to a mobile wireless receiver, the power source comprising:

a power supply; and

a first electromagnetic resonator coupled to a power supply, the first resonator having a mode with a resonant frequency ω

₁, an intrinsic loss rate Γ

₁, and a first Q-factor Q₁=ω

₁/(2Γ

₁), the portable electronic device,

wherein the first resonator is configured to be wirelessly coupled to a second electromagnetic resonator in the mobile wireless receiver to provide non-radiative wireless power to the second resonator from the first resonator with a wireless energy transfer rate κ

,

wherein the second electromagnetic resonator is coupled to a load in the mobile wireless receiver and movable relative to the first resonator, the second resonator having a mode with a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and a second Q-factor Q₂=ω

₂(2Γ

₂),

wherein (√

{square root over (Q₁Q₂)})>

100 .

106. The power source of claim 105, wherein Q₁>

100.

107. The power source of claim 105, wherein the first resonator is tunable.

108. The power source of claim 105, wherein the wireless mobile receiver is a is a cell phone, a computer, a robot, or a vehicle.

109. The power source of claim 105, wherein the resonant frequency f₁=ω

₁/2π

is at least 5 MHz.

110. The power source of claim 105, wherein during operation the power supply is driven to increase the ratio of useful-to-lost power for the wireless energy transfer.

111. The receiver of claim 105, wherein the first resonator comprises a capacitance and an inductance.