Wireless energy transfer in lossy environments

• US 9,742,204 B2
• Filed: 04/13/2016
• Issued: 08/22/2017
• Est. Priority Date: 09/27/2008
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: WiTricity Corporation
• Inventors: Kurs, Andre B., Hall, Katherine L., Kesler, Morris P., Soljacic, Marin, Giler, Eric R.
• Primary Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US15/097,622
• Publication Number:
  US 20160301253A1
• Time in Patent Office: 496 Days
• CPC Class Codes: B60L 2200/26 Rail vehicles
• 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 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/50 using additional energy repeaters between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• 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 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance

Abstract

Described herein are improved configurations for a wireless power transfer for electronic devices that include at least one source magnetic resonator including a capacitively-loaded conducting loop coupled to a power source and configured to generate an oscillating magnetic field and at least one device magnetic resonator, distal from said source resonators, comprising a capacitively-loaded conducting loop configured to convert said oscillating magnetic fields into electrical energy, wherein at least one said resonator has a keep-out zone around the resonator that surrounds the resonator with a layer of non-lossy material.

Claims

1. A wireless power source for transferring power to a wirelessly chargeable mobile electronic device, the wireless power source comprising:

a source magnetic resonator comprising a capacitively-loaded conducting loop configured to generate an oscillating magnetic field to transfer wireless power to a device magnetic resonator of the electronic device, wherein the source magnetic resonator has an unperturbed source quality factor Q_S; and

material positioned to space lossy material from at least a portion of the conducting loop and thereby form a keep-out zone,

wherein the keep-out zone enables the source magnetic resonator to have a perturbed source quality factor, Q_S,perturbed, that is at least 50% of the unperturbed source quality factor Q_S when the lossy material is positioned immediately outside the keep-out zone.

2. The power source of claim 1, wherein the keep-out zone extends for a distance of more than 0.25 mm outward from the source magnetic resonator.

3. The power source of claim 1, wherein a maximum dimension of the keep-out zone is approximately 1.0% greater than a characteristic size of the source magnetic resonator.

4. The power source of claim 1, wherein a maximum dimension of the keep-out zone is approximately 0.1% greater than a characteristic size of the source magnetic resonator.

5. The power source of claim 1, wherein the source magnetic resonator further comprises a magnetic material.

6. The power source of claim 1, wherein the unperturbed source quality factor Q_S is greater than 100.

7. The power source of claim 1, further comprising source power and control circuitry coupled to the source magnetic resonator, wherein the keep-out zone extends beyond at least one surface of the source power and control circuitry.

8. The power source of claim 1, wherein the material forming the keep-out zone is a layer of material positioned to cover at least one side of the conducting loop.

9. The power source of claim 8, wherein the capacitively-loaded conducting loop of the source magnetic resonator is built on a printed circuit board (PCB).

10. The power source of claim 9, wherein the layer of material forming the keep-out zone and the printed circuit board are on opposite sides of the capacitively-loaded conducting loop.

11. The power source of claim 8, wherein the material forming the keep-out zone is insulation material on the conducting loop.

12. The power source of claim 1, wherein the lossy material has a non-zero, but finite conductivity.

13. The power source of claim 1, wherein the perturbed source quality factor, Q_S,perturbed is at least 50% of the unperturbed source quality factor Q_S when the lossy material spans the outside of the keep-out zone.

14. The power source of claim 13, wherein the perturbed source quality factor, Q_S,perturbed is at least 50% of the unperturbed source quality factor Q_S when the lossy material spans the outside of the keep-out zone and the lossy material has a resistivity of 0.2 ohms·

meters at the frequency of the oscillating magnetic field.

15. The power source of claim 1, wherein the keep-out zone extends from the conducing loop by less than 1 cm.

16. The power source of claim 1, further comprising packaging for the source magnetic resonator, and wherein the material forming the keep-out zone is part of the packaging.

17. The power source of claim 1, wherein the material forming the keep-out zone comprises plastics, composites, plastic composites, Teflon, Rexolite, ABS, or ceramics.

18. The power source of claim 1, wherein the unperturbed source quality factor Q_S corresponds to the intrinsic quality factor of the source resonator.

19. A module for use in a wireless power system, the module comprising:

a magnetic resonator comprising a capacitively-loaded conducting loop built on a printed circuit board, wherein the magnetic resonator has an intrinsic quality factor Q greater than 100; and

a layer of insulating material positioned to cover the capacitively-loaded conducting loop and space lossy material from the conducting loop to thereby form a keep-out zone,

wherein the keep-out zone extends from the conducting loop by less than 1 cm and enables the magnetic resonator to have a perturbed quality factor, Q_perturbed, that is at least 50% of the intrinsic quality factor Q when the lossy material is positioned immediately outside the keep-out zone and covers the keep-out zone.

20. The module of claim 19, wherein the perturbed quality factor, Q_perturbed, is at least 50% of the intrinsic quality factor Q when the lossy material is positioned immediately outside the keep-out zone, covers the keep-out zone, and has a resistivity of 0.2 ohms·

meters at the resonant frequency of the magnetic resonator.