Wireless energy transfer across variable distances with high-Q capacitively-loaded conducting-wire loops

• US 8,772,971 B2
• Filed: 12/30/2009
• Issued: 07/08/2014
• 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 Number:
  US12/649,813
• Publication Number:
  US 20100133919A1
• Time in Patent Office: 1,651 Days
• Field of Search: 307/104
• 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 at least one source resonator coupled to an energy source generating an oscillating near field region, and at least one device resonator optionally coupled to an electronic device located at a variable distance within the at least one source resonator'"'"'s near-field region, where at least two of the resonators comprise high-Q capacitively-loaded conducting-wire loops.

Claims

1. A system, comprising:

at least one source resonator configured to be coupled to an energy source to generate an electromagnetic near field region; and

at least one device resonator located at a variable distance D from the at least one source resonator within the at least one source resonator'"'"'s near-field region to enable resonant wireless energy transfer between the at least one source resonator and the at least one device resonator when the at least one source resonator is coupled to the energy source,

wherein at least two of the resonators comprise high-Q capacitively-loaded conducting-wire loops,

wherein the first high-Q capacitively-loaded conducting wire loop has a resonant frequency ω

₁ and an intrinsic loss rate Γ

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

₁/(2Γ

₁) greater than 100,

wherein the second high-Q capacitively-loaded conducting wire loop has a resonant frequency ω

₂ and an intrinsic loss rate Γ

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

₁/(2Γ

₂) greater than 100, and

wherein D is less than the wavelengths λ

₁=c/2π

ω

₁ and λ

₂=c/2π

ω

₂ corresponding to the resonant frequencies ω

₁ and ω

₂, respectively, where c is the speed of light.

2. The system of claim 1 wherein the distance between the resonators is greater than 5 cm.

3. The system of claim 1 wherein the distance between the resonators is greater than 10 cm.

4. The system of claim 1 wherein that distance between the resonators is larger than the characteristic size of the smaller of the first resonator and the second resonator.

5. 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.

6. The system of claim 5, wherein the loops of the electrical conductors of each of the source and device resonators are in substantially the same plane.

7. The system of claim 5, 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.

8. The system of claim 5, 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.

9. The system of claim 5, 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.

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

11. The system of claim 10, wherein the energy drain comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

12. The system of claim 1, further comprising the energy source configured to be coupled to the first high-Q capacitively-loaded conducting wire loop and an energy drain configured to be coupled to the second high-Q capacitively-loaded conducting wire loop to provide useful power to the energy drain, and wherein the energy source is configured to provide energy to the first high-Q capacitively-loaded conducting wire loop at a rate that varies with a rate of wireless energy transfer κ

between the first high-Q capacitively-loaded conducting wire loop and the second high-Q capacitively-loaded conducting wire loop.

13. The system of claim 12, wherein the energy source is configured to provide energy to the first high-Q capacitively-loaded conducting wire loop at a rate that substantially minimizes the energy stored in the first high-Q capacitively-loaded conducting wire loop and the second high-Q capacitively-loaded conducting wire loop.

14. The system of claim 12, wherein the energy source is configured to provide energy to the first high-Q capacitively-loaded conducting wire loop at a rate that substantially maximizes a ratio of the useful power to lost power from the energy source to the energy drain.

15. 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.

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

17. The system of claim 1, wherein Q₁>

200 and Q₂>

200.

18. The system of claim 1, further comprising the energy source coupled to the source resonator and a vehicle having the device resonator, and wherein the system is configured to provide wireless power to the vehicle from the source resonator to the device resonator.

19. The system of claim 17, further comprising the energy source coupled to the source resonator and a vehicle having the device resonator, and wherein the system is configured to provide wireless power to the vehicle from the source resonator to the device resonator.

20. The system of claim 1, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1 for a range of the variable distance D in the near-field region, wherein κ

is the wireless energy transfer rate.

21. The system of claim 20, wherein the range of variable distance D includes distances greater than the characteristic size L₂ of the second high-Q capacitively-loaded conducting wire loop.

22. The system of claim 20, wherein the range of variable distance D includes distances greater than twice the characteristic size L₂ of the second high-Q capacitively-loaded conducting wire loop.

23. A method, comprising:

providing at least one source resonator coupled to an energy source generating an electromagnetic near field region; and

providing at least one device resonator located at a variable distance D from the at least one source resonator within the at least one source resonator'"'"'s near-field region to enable resonant wireless energy transfer between the at least one source resonator and the at least one device resonator,

wherein at least two of the resonators comprise high-Q capacitively-loaded conducting-wire loops,

wherein the first high-Q capacitively-loaded conducting wire loop has a resonant frequency ω

₁ and an intrinsic loss rate Γ

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

₁/(2Γ

₁) greater than 100,

wherein the second high-Q capacitively-loaded conducting wire loop has a resonant frequency ω

₂ and an intrinsic loss rate Γ

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

₁/(2Γ

₂) greater than 100, and

wherein D is less than the wavelengths λ

₁=c/2π

ω

₁ and λ

₂=c/2π

ω

₂ corresponding to the resonant frequencies ω

₁ and ω

₂, respectively, where c is the speed of light.

24. The method of claim 23 wherein the distance between the resonators is greater than 5 cm.

25. The method of claim 23 wherein the distance between the resonators is greater than 10 cm.

26. The method of claim 23 wherein that distance between the resonators is larger than the characteristic size of the smaller of the first resonator and the second resonator.

27. The method of claim 23, wherein each resonator comprises an electrical conductor shaped into one or more loops wound in substantially a single plane circumscribing a substantially planar area.

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

29. The method of claim 23, wherein the energy source is coupled to the first high-Q capacitively-loaded conducting wire loop and an energy drain is coupled to the second high-Q capacitively-loaded conducting wire loop to provide useful power to the energy drain, and wherein the energy source provides energy to the first high-Q capacitively-loaded conducting wire loop at a rate that varies with a rate of wireless energy transfer κ

between the first high-Q capacitively-loaded conducting wire loop and the second high-Q capacitively-loaded conducting wire loop.

30. The method of claim 29, wherein the energy source provides energy to the first high-Q capacitively-loaded conducting wire loop at a rate that substantially maximizes a ratio of the useful power to lost power from the energy source to the energy drain.

31. The method of claim 29, wherein the energy source provides energy to the first high-Q capacitively-loaded conducting wire loop at a rate that substantially minimizes the energy stored in the first high-Q capacitively-loaded conducting wire loop and the second high-Q capacitively-loaded conducting wire loop.

32. The method of claim 23, wherein Q₁>

200 and Q₂>

200.

33. The method of claim 32, wherein a vehicle carries the device resonator, and wherein the method provides wireless power to the vehicle from the source resonator to the device resonator.

34. The method of claim 23, wherein a vehicle carries the device resonator, and wherein the method provides wireless power to the vehicle from the source resonator to the device resonator.

35. The method of claim 23, wherein κ

/√

{square root over (Γ

₁Γ

₂)}>

1 for a range of variable distance D in the near-field region, wherein κ

is the wireless energy transfer rate.

36. The system of claim 35, wherein the range of variable distance D includes distances greater than the characteristic size L₂ of the second high-Q capacitively-loaded conducting wire loop.

37. The system of claim 35, wherein the range of variable distance D includes distances greater than twice the characteristic size L₂ of the second high-Q capacitively-loaded conducting wire loop.