Wireless energy transfer

• US 9,450,422 B2
• Filed: 03/24/2015
• Issued: 09/20/2016
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Karalis, Aristeidis, Kurs, Andre B., Moffatt, Robert, Joannopoulos, John D., Fisher, Peter H., Soljacic, Marin
• Primary Examiner(s): Fleming, Fritz M
• APPLICATION: US 20150194818A1
• Time in patent office: 546 Days
• Field of Search: 320/108, 307/104
• US Class Current: 1/1
• CPC Class Codes: B60L 11/182 by inductive energy transfer
• CPC Class Codes: B60L 2210/20 AC to AC converters
• 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: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 9/04 Resonant antennas
• CPC Class Codes: H02J 5/005 with inductive power transfer for charging H02J7/025
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/025 using non-contact coupling, e.g. inductive, capacitive
• CPC Class Codes: H04B 5/0037 for power transfer
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7005 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 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 10/725 AC to AC power conversion
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/122 by inductive energy transmission
• CPC Class Codes: Y02T 90/127 Converters or inverters for charging
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y10T 29/4902 : Electromagnet, transformer or inductor

Abstract

Disclosed is an apparatus for use in wireless energy transfer, which includes a first resonator structure configured to transfer energy non-radiatively with a second resonator structure over a distance greater than a characteristic size of the second resonator structure. The non-radiative energy transfer is mediated by a coupling of a resonant field evanescent tail of the first resonator structure and a resonant field evanescent tail of the second resonator structure.

Claims

1. A wireless power system comprising:

a source resonator and a power supply coupled to the source resonator to provide power to the source resonator, the source resonator having a resonant frequency ω

₁, an intrinsic loss rate Γ

₁, and an intrinsic quality factor Q₁=ω

₁/(2Γ

₁), the source resonator comprising at least one loop of conductive material; and

a device resonator and a load coupled to the device resonator to receive power from the device resonator and provide power to the load, the device resonator having a resonant frequency ω

₂, an intrinsic loss rate Γ

₂, and an intrinsic quality factor Q₂=ω

₂/(2Γ

₂), the device resonator comprising at least one loop of conductive material,

wherein the device resonator is configured to be movable relative to the source resonator over a range of distances D between the source resonator and the device resonator,

wherein the source resonator and the device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the device resonator using non-radiative electromagnetic induction having a coupling coefficient κ

, and wherein the intrinsic loss rates satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

1 over the range of distances D, and

wherein the power provided to the load from the device resonator defines a work drainage rate Γ

_w, and wherein the work drainage rateΓ

_w, is configured to be set such that Γ

_w=Γ

₂√

{square root over (1+wp·

(κ

²/Γ

₁·

Γ

₂))} for some value of the coupling coefficient κ

in the range of distances D, wherein wp is a parameter satisfying wp>

1.

2. The wireless power system of claim 1, wherein the parameter wp satisfies 1<

wp≦

10.

3. The wireless power system of claim 1, wherein the parameter wp is set to decrease energy stored in the device resonator.

4. The wireless power system of claim 3, wherein the parameter wp is set to decrease energy stored in the device resonator to prevent breakdown of a capacitor material providing a capacitance for the device resonator.

5. The wireless power system of claim 1, further comprising a portable electronic device comprising the device resonator and the load, wherein the portable electronic device is a cell phone, a computer, or a robot, wherein f₁=ω

₁/(2π

) and f₂=ω

₂/(2π

), and f₁ and f₂, are between 1 MHz and 10 MHz, and wherein each intrinsic loss rate comprises a resistive component and a radiative component.

6. The wireless power system of claim 5, wherein Q₁>

100.

7. The wireless power system of claim 6, wherein the intrinsic quality factors satisfy √

{square root over (Q₁Q₂)}>

100.

8. The wireless power system of claim 5, wherein power provided to the load from the device resonator is at least 1 Watt.

9. The wireless power system of claim 8, wherein the wirelessly coupled electromagnetic power transferred between the source and device resonators operates with a radiation loss less than about 10%.

10. The wireless power system of claim 9, wherein the wirelessly coupled electromagnetic power transferred between the source and device resonators operates with a radiation loss less than about 1%.

11. The wireless power system of claim 5, wherein the source resonator has a characteristic size L₁ and the device resonator has a different characteristic size L₂.

12. The wireless power system of claim 5, further comprising a second portable electronic device comprising a second device resonator and a second load coupled to the second device resonator to receive power from the second device resonator and provide power to the second portable electronic device, and

wherein the second device resonator is moveable relative to the source resonator and wherein the source resonator and the second device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the second device resonator using non-radiative electromagnetic induction.

13. The wireless power system of claim 1, wherein the parameter wp satisfies 1<

wp≦

10, and wherein the parameter wp is set to prevent breakdown of a capacitor material providing a capacitance for the device resonator.

14. The wireless power system of claim 13, further comprising a portable electronic device comprising the device resonator, wherein the portable electronic device is a cell phone, a computer, or a robot, wherein f₁=ω

₁/(2π

) and f₂=ω

₂/(2π

), and f₁ and f₂, are between 1 MHz and 10 MHz, and wherein each intrinsic loss rate comprises a resistive component and a radiative component.

15. The wireless power system of claim 14, wherein Q₁>

100, wherein power provided to the load from the device resonator is at least 1 Watt, and wherein the source resonator has a characteristic size L₁ and the device resonator has a different characteristic size L₂.

16. The wireless power system of claim 15, wherein the intrinsic quality factors satisfy √

{square root over (Q₁Q₂)}>

100.

17. The wireless power system of claim 15, wherein the wirelessly coupled electromagnetic power transferred between the source and device resonators operates with a radiation loss less than about 10%.

18. The wireless power system of claim 15, and wherein the wireless power system further comprises a second portable electronic device comprising a second device resonator and a second load coupled to the second device resonator to receive power from the second device resonator and provide power to the second portable electronic device, and

wherein the second device resonator is moveable relative to the source resonator and wherein the source resonator and the second device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the second device resonator using non-radiative electromagnetic induction.

19. The wireless power system of claim 1, further comprising an intermediate resonator having a resonant frequency ω

₃, an intrinsic loss rate Γ

₃, and an intrinsic quality factor Q₃=ω

₃/(2Γ

₃), the intermediate resonator comprising at least one loop of conductive material and having a capacitance, and wherein the source resonator and the device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the device resonator through the intermediate resonator.

20. The wireless power system of claim 19, wherein Q₃>

100.

21. The wireless power system of claim 13, further comprising a vehicle comprising the device resonator, wherein the load is coupled to the device resonator to receive power from the device resonator, wherein the power provided to the load from the device resonator is greater than 10 Watts, and wherein f₁=ω

₁/(2π

) and f₂=ω

₂/(2π

), and f₁ and f₂, are between 10 kHz and 1 MHz.

22. The wireless power system of claim 21, wherein f₁ and f₂, are between 10 kHz and 100 kHz.

23. The wireless power system of claim 22, wherein the power provided to the load from the device resonator is on the order of 1 kW, wherein the intrinsic loss rates satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

5 over the range of distances D, and wherein Q₁>

200 and Q₂>

200.

24. The wireless power system of claim 21, wherein the intrinsic loss rates satisfy κ

/√

{square root over (Γ

₁Γ

₂)}>

5 over the range of distances D.

25. The wireless power system of claim 21, wherein the power provided to the load from the device resonator is on the order of 1 kW.

26. The wireless power system of claim 21, wherein Q₁>

100 and Q₂>

100.