Wireless non-radiative energy transfer

• US 8,395,282 B2
• Filed: 03/31/2009
• Issued: 03/12/2013
• 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:
  US12/415,667
• Publication Number:
  US 20090267710A1
• Time in Patent Office: 1,442 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 system, comprising:

a source resonator, configured to be coupled to an energy source, the source 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 resonator, the second 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 at least one of the resonators has a characteristic size greater than or equal to 1 cm, and

wherein the source resonator and second resonator are configured to be electro-magnetically coupled to exchange energy over a distance a few times the characteristic size via non-radiative wireless energy transfer.

7. The system of any one of claims 1 to 6, further comprising the energy source coupled to the source resonator and an energy drain coupled to the second resonator.

8. The system of any one of claims 1 to 6, wherein Q₁>

100 or Q₂>

100.

9. The system of any one of claims 1 to 6, wherein √

{square root over (Q₁Q₂)}>

100.

10. The system of any one of claims 1 to 6, wherein the resonators are movable relative to one another.

11. The system of any one of claims 1 to 6, wherein at least 10 Watts of power is delivered to the second resonator.

12. The system of any one of claims 1 to 6, wherein the efficiency of the wireless energy transfer is at least 20%.

13. The system of any one of claims 1 to 6, wherein each resonator comprises an inductive element and a capacitive element.

14. The system of any one of claims 1 to 6, wherein the source resonator is coupled to the energy source and wherein the second resonator is coupled to an energy drain, and wherein the energy drain comprises a robot, vehicle, computer, cell phone, or a portable electronic device.

15. The system of any one of claims 1 to 6, wherein at least one of the resonators is a tunable resonator.

16. The system of any one of claims 1 to 6, wherein the resonant frequencies f₁=ω

₁/2π and

f₂=ω

₂/2π

of the resonators are each at least 5 MHz.

17. The system of any one of claims 1 to 6, wherein the source resonator and the second resonator have different characteristic sizes.

18. The system of any one of claims 1 to 6, wherein Q₁>

100 and Q₂>

100.

19. The system of any one of claims 1 to 6, wherein Q₁>

200 or Q₂>

200.

20. The system of any one of claims 1 to 6, further comprising the energy source coupled to the source resonator and an energy drain coupled to the second resonator to provide useful power to the second resonator, and wherein the energy source is configured to provide energy to the source resonator at a rate that varies with a rate of wireless energy transfer κ

between the source resonator and the second resonator.

21. The system of claim 20, 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 second resonator.

22. The system of claim 20, 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.

2. A system, comprising:

a source resonator, configured to be coupled to an energy source, the source 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 resonator, the second 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 at least one of the resonators has a characteristic size greater than or equal to 30 cm, and

wherein the source resonator and second resonator are configured to be electro-magnetically coupled to exchange energy over a distance a few times the characteristic size via non-radiative wireless energy transfer.

3. A system, comprising:

a source resonator, configured to be coupled to an energy source, the source 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 resonator, the second 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 at least one of the resonators has a characteristic size greater than or equal to 60 cm, and

wherein the source resonator and second resonator are configured to be electro-magnetically coupled to exchange energy over a distance a few times the characteristic size via non-radiative wireless energy transfer.

4. A system, comprising:

a source resonator, configured to be coupled to an energy source, the source 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 and Q₁=ω

₁/(2Γ

₁), and

a second resonator, the second 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 second resonator are configured to be electro-magnetically coupled to exchange energy over a distance greater than 30 cm via non-radiative wireless energy transfer.

5. A system, comprising:

a source resonator, configured to be coupled to an energy source, the source 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 Q=ω

/(2Γ

₁), and

a second resonator, the second 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 second resonator are configured to be electro-magnetically coupled to exchange energy over a distance greater than 60 cm via non-radiative wireless energy transfer.

6. A system, comprising:

a source resonator, configured to be coupled to an energy source, the source 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 resonator, the second 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 second resonator are configured to be electro-magnetically coupled to exchange energy over a distance of a few meters via non-radiative wireless energy transfer.