Transmitters and receivers for wireless energy transfer

• US 8,378,523 B2
• Filed: 09/16/2008
• Issued: 02/19/2013
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Cook, Nigel, Widmer, Hanspeter, Sieber, Lukas, Dominiak, Stephen
• Primary Examiner(s): KAPLAN, HAL IRA
• Application Number:
  US12/211,706
• Publication Number:
  US 20090079268A1
• Time in Patent Office: 1,617 Days
• Field of Search: 307/104, 361/143, 361/159
• US Class Current: 307/104
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/248 provided with an AC/DC converting device, e.g. rectennas
• 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

Abstract

Techniques for wireless power transmission. An antenna has a part that amplifies a flux to make the antenna have a larger effective size than its actual size.

Claims

1. A system for receiving magnetic transmission of power, comprising:

an antenna circuit comprising a wire loop antenna, the wire loop antenna comprising a wire formed into at least one loop, the antenna circuit having an inductance and a capacitance with an L/C value tuned for receiving the power from a magnetic field of a first frequency, the antenna circuit configured to produce an output that includes electrical power based on receiving the power from the magnetic field; and

a first electrical part configured to increase an equivalent radius of the wire loop antenna without increasing a physical radius of the wire loop antenna.

2. The system of claim 1, wherein the at least one loop comprises a rectangular loop.

3. The system of claim 2, wherein the rectangular loop has rounded corners.

4. The system of claim 1, wherein the first electrical part is configured to increase the magnetic field such that the wire loop antenna operates as if the equivalent radius of the wire loop antenna is greater than the physical radius of the wire loop antenna.

5. The system of claim 1, wherein at least a portion of the first electrical part comprises a ferrite material.

6. The system of claim 1, wherein at least a portion of the first electrical part comprises a material that increases magnetic flux in the system.

7. The system of claim 1, wherein the first electrical part comprises a flux magnification part.

8. The system of claim 7, wherein the flux magnification part comprises a rod, wherein an amount of flux magnification is related to a length of the rod.

9. The system of claim 8, further comprising a housing, wherein the rod is positioned within the housing, and wherein the at least one loop of the wire loop antenna is wound around the rod.

10. The system of claim 9, further comprising at least one opening in the housing allowing the magnetic field to pass through the opening and to interact with the rod.

11. The system of claim 10, wherein the rod comprises a ferrite material.

12. The system of claim 9, further comprising a slot in the housing.

13. The system of claim 12, wherein the housing comprises a conductive material.

14. The system of claim 7, further comprising a housing, wherein the wire loop antenna is placed along at least a portion of a surface of the housing.

15. The system of claim 14, wherein the portion of the surface of the housing comprises a perimeter of the housing.

16. The system of claim 14, wherein the housing comprises a metallic material, and wherein the wire loop antenna is separated from the metallic material.

17. The system of claim 16, wherein a gap is formed between the wire loop antenna and the metallic material, the gap being of a size through which the magnetic field can pass through.

18. The system of claim 16, further comprising a ferrite portion coupled to the housing and configured to hold at least a part of the wire loop antenna separated from the housing.

19. The system of claim 14, wherein the wire loop antenna is separable from the housing and movable relative thereto.

20. The system of claim 1, further comprising a connection to a wireless power circuit configured to power a load using the output.

21. A method for receiving a magnetic transmission of power, comprising:

receiving power using an antenna circuit comprising a wire loop antenna, the antenna circuit having an inductance L and a capacitance C with an L/C ratio tuned to a value that is resonant with a frequency of a magnetic field, the wire loop antenna having an equivalent radius that is greater than a physical radius of the wire loop antenna, wherein a first electrical part is used to provide the equivalent radius; and

powering a load using the received power.

22. The method of claim 21, wherein the wire loop antenna comprises a rectangular loop.

23. The method of claim 22, wherein the rectangular loop has rounded edges.

24. The method of claim 21, wherein the first electrical part is configured to increase magnetic flux of the magnetic field.

25. The method of claim 21, wherein the first electrical part is configured to magnify a flux produced by the antenna circuit.

26. The method of claim 21, wherein the wire loop antenna is placed substantially along at least one portion of a surface of a housing.

27. The method of claim 26, wherein the portion of the surface of the housing comprises a perimeter of the housing.

28. The method of claim 26, wherein the housing comprises a metallic material, and wherein the wire loop antenna is separated from the metallic material.

29. The method of claim 28, wherein a gap is formed between the wire loop antenna and the metallic material such that the magnetic field can pass through the gap.

30. The method of claim 26, wherein the wire loop antenna is separable from the housing, wherein the method further comprises allowing movement of the wire loop antenna relative to the housing.

31. A method, comprising:

determining whether there are greater dielectric losses than eddy current losses in an environment for receiving power via a magnetic field;

receiving power using a first resonator if the dielectric losses are greater than the eddy current losses in the environment; and

receiving power using a second resonator if the eddy current losses are greater than the dielectric losses in the environment.

32. The method of claim 31, wherein the first resonator comprises an inductive loop with at least 3 turns.

33. The method of claim 31, wherein the second resonator comprises an inductive loop with two or fewer turns.

34. The method of claim 31, wherein the first resonator has a Q factor greater than 1500.

35. The method of claim 31, wherein a first inductance to capacitance ratio of the second resonator is greater than a second inductance to capacitance ratio of the first resonator.

36. A system for receiving wireless power, comprising:

a housing configured to house mobile electronics; and

an antenna circuit configured to receive power via a magnetic field to power or charge a load, wherein the antenna circuit comprises a loop antenna portion placed along at least a portion of a surface of the housing.

37. The system of claim 36, wherein the portion of the surface of the housing comprises a perimeter of the housing.

38. The system of claim 36, wherein the housing comprises a nonmetallic material, and wherein the loop antenna portion is physically in contact with the nonmetallic material.

39. The system of claim 36, wherein the housing comprises a metallic material, and wherein the loop antenna portion is separated from the metallic material.

40. The system of claim 39, wherein a gap is formed due to the loop antenna portion being separated from the metallic material, wherein the gap is of a size through which magnetic field can pass through.

41. The system of claim 36, wherein the loop antenna portion is separable from the housing and movable relative to the housing.

42. The system of claim 36, further comprising a ferrite portion coupled to the housing and configured to hold at least a part of the loop antenna portion.

43. A system for receiving wireless power, comprising:

a housing;

a coil winding form extending across the housing from at least a first side of the housing to a second side of the housing;

a coil wound around the coil winding form; and

at least one opening in the housing configured to allow magnetic fields to interact with the coil winding form.

44. The system of claim 43, wherein the coil winding form comprises a ferrite material.

45. The system of claim 43, further comprising a slot in the housing.

46. The system of claim 43, wherein the housing comprises a conductive material.

47. The system of claim 43, wherein the coil winding form is a cylindrical shaped form.

48. An RFID system, comprising:

a first layer comprising a first material that converts mechanical strain to electrical energy;

a second layer in mechanical contact with the first layer, wherein the second layer comprises a second material that changes position in response to an applied magnetic field; and

a first output terminal, connected to receive the electrical energy from the second layer.

49. The RFID system of claim 48, wherein the second material comprises an electrically conductive magnetostrictive material.

50. The RFID system of claim 48, wherein the first material comprises a piezoelectric material.

51. The RFID system of claim 48, wherein the output terminal is connected directly to the second layer.

52. The RFID system of claim 51, further comprising a third layer comprising the second material, wherein the first layer is sandwiched between the second layer and the third layer, wherein the second layer and the third layer are electrically conductive, wherein the system further comprises a second output terminal, and wherein the first and second output terminals are connected to receive electrical energy from the second and third layers.

53. The RFID system of claim 48, wherein the first layer is arranged such that the first layer is compressed when the second layer changes position in response to the applied magnetic field.

54. A system for magnetic transmission of power, comprising:

an antenna circuit comprising a wire loop antenna, the wire loop antenna comprising a wire formed into at least one loop, the antenna circuit having an inductance L and a capacitance C, with an L/C value tuned for transmitting a magnetic field of a first frequency; and

a first electrical part configured to increase an equivalent radius of the wire loop antenna without increasing a physical radius of the wire loop antenna.

55. The system of claim 54, wherein the at least one loop comprises a rectangular loop.

56. The system of claim 55, wherein the rectangular loop has rounded edges.

57. The system of claim 54, wherein the first electrical part increases the magnetic field such that the wire loop antenna operates as if the equivalent radius of the wire loop antenna is greater than the physical radius of the wire loop antenna.

58. The system of claim 54, wherein at least a portion of the first electrical part comprises a ferrite material.

59. The system of claim 54, wherein at least a portion of the first electrical part comprises a material that adds magnetic flux.

60. The system of claim 54, wherein the first electrical part comprises a flux magnification part.

61. The system of claim 60, wherein the flux magnification part has a relative permeability, wherein an amount of flux magnification is increased by a square root of the relative permeability.

62. The system of claim 60, wherein the flux magnification part includes a rod, and wherein an amount of flux magnification is related to a length of the rod.

63. The system of claim 54, further comprising a connection to an AC power source.

64. A system for receiving magnetic transmission of power, comprising:

means for wirelessly receiving power having an inductance L and a capacitance C with an L/C value tuned for receiving the power from a magnetic field of a first frequency, the means for wirelessly receiving power comprising means for producing an output that includes electrical power based on receiving the power from the magnetic field; and

means for increasing an equivalent radius of the means for wirelessly receiving power without increasing a physical radius of the means for wirelessly receiving power.

65. The system of claim 64, wherein at least a portion of the means for increasing an equivalent radius comprises a ferrite material.

66. The system of claim 64, wherein at least a portion of the means for increasing an equivalent radius comprises a material that increases magnetic flux in the system.

67. The system of claim 64, wherein the means for wirelessly receiving power comprises an antenna circuit comprising a wire loop antenna.

68. A system for receiving wireless power, comprising:

a housing configured to house mobile electronics; and

means for receiving power via a magnetic field at a level sufficient to power or charge a load, wherein the means for receiving power is placed along at least a portion of a surface of the housing.

69. The system of claim 68, wherein the portion of the surface of the housing comprises a perimeter of the housing.

70. The system of claim 68, wherein the means for receiving power is seperable from the housing and movable relative to the housing.