SELECTIVELY CONTROLLABLE ELECTROMAGNETIC SHIELDING

• US 20120112552A1
• Filed: 09/23/2011
• Published: 05/10/2012
• Est. Priority Date: 09/26/2010
• Status: Active Grant

• Current Assignee: Philips IP Ventures B.V. (Koninklijke Philips N.V.)
• Original Assignee: Access Business Group International LLC (Alticor Incorporated)
• Inventors: Baarman, David W., Stoner, William T. Jr., Schwannecke, Joshua K., Moes, Benjamin C., Turner, Kaitlyn J.
• Granted Patent: US 9,161,484 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 53/124 Detection or removal of foreign bodies
• 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 27/36 Electric or magnetic shields or screens movable for varying inductance H01F21/10
• CPC Class Codes: H01F 27/366 made of ferromagnetic material
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• 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: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H05K 9/002 with localised screening
• CPC Class Codes: H05K 9/0088 comprising a plurality of shielding layers; combining different shielding material structure
• 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
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A selectively controllable electromagnetic shield having an electromagnetic shielding material and a mechanism for selectively generating an aperture in the shield. The mechanism for selectively generating an aperture may be a magnetic field source that generates a magnetic field of sufficient strength to substantially saturate all or a portion of the shielding material. For example, a permanent magnet or DC electromagnet may be used to selectively saturate the shield. In its un-saturated state, the magnetic shield has a high permeability and functions as a flux path for the magnetic field. Once saturated, the permeability of the shield is substantially reduced so that the magnetic field lines are no longer drawn into the shield to the same degree. As a result, once saturated, a substantially greater amount of the electromagnetic field may flow through or around the shield in the saturated region.

Claims

1. An electromagnetic shielding system comprising:

an electromagnetic shield having a permeability substantially greater than a permeability of ambient space such that said electromagnetic field provides an electromagnetic flow path of lesser resistance than ambient space; and

a magnetic field source positioned or positionable proximate said electromagnetic shield, said magnetic field source generating a magnetic field of sufficient strength to selectively substantially saturate at least a portion of said shield, thereby selectively reducing said permeability of said electromagnetic shield such that said electromagnetic shield no longer provides an electromagnetic flow path of lesser resistance than ambient space.

2. The system of claim 1 wherein said magnetic field source is an electromagnet that can be selectively actuated to selectively generate a DC magnetic field of sufficient strength to substantially saturate said electromagnetic shield.

3. The system of claim 2 wherein said magnetic field source includes a plurality of electromagnets arranged in a pattern adjacent said electromagnetic shield, said electromagnets being separately operable to selectively saturate different regions of said electromagnetic shield.

4. The system of claim 1 wherein said magnetic field source is a permanent magnet that is removably positionable near said electromagnetic shield.

5. The system of claim 1 wherein said magnetic field source is a magnet carried by a remote device, whereby placement of the remote device adjacent said electromagnetic shield results in said magnet substantially saturating said electromagnetic field.

6. The system of claim 1 wherein said magnetic field source is capable of selectively varying a strength of said magnetic field.

7. The system of claim 1 wherein said electromagnetic shield is configured to be substantially coextensive with an electromagnetic transfer surface of a wireless power supply.

8. The system of claim 7 wherein said magnetic field source is selected to generate a DC magnetic field of sufficient strength to selectively substantially saturate only a portion of said shield, thereby selectively producing an aperture through said shield.

9. The system of claim 7 wherein said magnetic field source includes a plurality of separately-operable electromagnets arranged in a pattern adjacent said shield, said electromagnets being selectively operable alone or in combination to produce one or more localized apertures in said shield.

10. The system of claim 1 wherein said electromagnetic shield is manufactured from a flexible composite ferrite.

11. The system of claim 1 further including supplemental shielding separate from said shield.

12. The system of claim 10 wherein:

said supplemental shield is disposed adjacent an electromagnetic field source for generating an electromagnetic field; and

said magnetic field source configured to selectively substantially saturate at least a portion of said electromagnetic shield without substantially saturating said supplemental shield, whereby actuation of the magnetic field source allows substantially more of the electromagnetic field to pass through said saturated portion of said electromagnetic shield while said supplemental shield continues to contain the electromagnetic shield substantially unchanged by said magnetic field source.

13. The system of claim 12 wherein said supplemental shield and said electromagnetic shield cooperatively substantially surround the electromagnetic field source, whereby the electromagnetic field is substantially contained within said supplemental shield and said electromagnetic shield when said electromagnetic shield is unsaturated.

14. The system of claim 12 wherein said magnetic field source is carried by a remote device having an electromagnetic field receiver, whereby placement of the remote device adjacent said electromagnetic shield positions said magnetic field source to saturate at least a portion of said electromagnetic shield and positions the electromagnetic field receiver to receive the electromagnetic field passing through said saturated portion of said electromagnetic shield.

15. The system of claim 14 wherein said magnetic field source includes a permanent magnet.

16. The system of claim 14 wherein said magnetic field source includes an electromagnet.

17. The system of claim 1 wherein said electromagnetic shield is manufactured from a soft magnetic material having a permeability curve with a first region of high permeability, a second region of low permeability and a transition region between said first region and said second region, said magnetic field source having a field strength selected to transition said electromagnetic shield from said first region to said second region.

18. The system of claim 12 further including a transfer surface of sufficient size to simultaneously receive a plurality of said remote devices, the electromagnetic field source being capable of delivering the electromagnetic field to the remote device disposed anywhere on said transfer surface, said magnetic field source being capable of saturating only a portion of said electromagnetic shield.

19. The system of claim 1 further including:

an electromagnetic receiver configured to receive an electromagnetic field generated by an electromagnetic field source;

said electromagnetic shield substantially surrounding said receiver, said electromagnetic shield having sufficient permeability to substantially reduce an efficiency of a coupling between said electromagnetic receiver and an external electromagnetic field source; and

wherein at least a first portion of said electromagnetic shield is manufactured from soft magnetic material having a permeability curve with a first region of high permeability, a second region of low permeability and a transition region between said first region and said second region, said material being readily transitioned from said first region to said second region by a DC magnetic field of appropriate strength.

20. The system of claim 19 wherein said electromagnetic shield includes a supplemental portion manufactured from a material capable of remaining unsaturated when in a DC magnetic field of appropriate strength to substantially saturate said first portion.

21. The system of claim 20 further including an electromagnet, said electromagnet being capable of selectively generating a DC magnetic field of sufficient strength to substantially saturate at least a region of said electromagnetic shield without substantially saturating said supplemental portion of said electromagnetic shield.

22. The system of claim 20 further including a plurality of separately operable electromagnets, each of said electromagnets being capable of selectively generating a DC magnetic field of sufficient strength to substantially saturate an adjacent region of said electromagnetic shield without substantially saturating said supplemental portion of said electromagnetic shield.

23. The system of claim 19 wherein said electromagnetic receiver is capable of receiving at least one of wireless power and wireless communications via an external electromagnetic field.

24. An electromagnetic transfer system comprising:

an electromagnetic field generator capable of generating an electromagnetic field;

an electromagnetic field receiver capable of receiving said electromagnetic field;

an electromagnetic shield disposed between said field generator and said receiver, said electromagnetic shield being selectively capable of substantially reducing an ability of said electromagnetic field to reach said electromagnetic field receiver; and

a DC magnetic field source selectively operable to selectively saturate at least a portion of said electromagnetic shield such that a substantially greater portion of said electromagnetic field is capable of passing through said electromagnetic shield to reach said electromagnetic field receiver.

25. The system of claim 24 wherein said magnetic field source includes an electromagnet disposed proximate to said electromagnetic shield, said electromagnet being selectively activated to selectively generate a magnetic field of sufficient strength to substantially saturate at least a portion of said electromagnetic shield.

26. The system of claim 25 wherein said electromagnetic field receiver is carried by a remote device;

and

further including circuitry for determining when said remote device is positioned adjacent said electromagnetic shield and circuitry for activating said electromagnet as a function of said determination.

27. The system of claim 24 wherein said magnetic field source is separate from and removably placeable adjacent to said electromagnetic shield.

28. The system of claim 27 wherein said magnetic field source includes a permanent magnet.

29. The system of claim 24 wherein said electromagnetic field receiver and said magnetic field source are carried by a remote device, whereby placement of said remote device adjacent said electromagnetic shield positions said magnetic field source to saturate at least a portion of said electromagnetic shield and positions said electromagnetic field receiver to receive said electromagnetic field passing through said saturated portion of said electromagnetic shield.

30. The system of claim 29 wherein said magnetic field source includes a permanent magnet.

31. The system of claim 24 wherein said electromagnetic field generator generates an electromagnetic field to wirelessly transfer power.

32. The system of claim 31 wherein said electromagnetic field generator is disposed adjacent to a transfer surface on which said electromagnetic field receiver may be removably placed, said electromagnetic shield disposed between said electromagnetic field generator and said transfer surface.

33. The system of claim 24 wherein said DC magnetic field source is capable of selectively varying a strength of a magnetic field generated by said DC magnetic field source.

34. The system of claim 24 wherein said electromagnetic field generator generates an electromagnetic field to wirelessly transfer at least one of power and communications.

35. The system of claim 34 wherein said electromagnetic shield is manufactured from a flexible composite ferrite.

36. The system of claim 24 wherein said electromagnetic shield is manufactured from a soft magnetic material having a permeability curve with a first region of high permeability, a second region of low permeability and a transition region between said first region and said second region, said DC magnetic field source having a field strength selected to transition said shield from said first region to said second region.

37. The system of claim 24 wherein said magnetic field source includes a plurality of electromagnets arranged in a pattern adjacent to said electromagnetic shield, each of said electromagnets being selectively operable to selectively generate a magnetic field of sufficient strength to substantially saturate an adjacent portion of said electromagnetic shield, whereby said electromagnets may be individually actuated to selectively produce regionalized apertures through said shield.

38. The system of claim 24 wherein said electromagnetic field generator includes a plurality of primaries;

and

wherein said DC magnetic field source includes a plurality of electromagnets.

39. The system of claim 24 wherein said electromagnetic field generator is disposed adjacent to a transfer surface of sufficient size to simultaneously receive a plurality of said electromagnetic field receivers, said electromagnetic shield disposed between said electromagnetic field generator and said transfer surface, said electromagnetic field generator being capable of delivering said electromagnetic field to an electromagnetic field receiver disposed anywhere on said transfer surface.

40. A wireless power system comprising:

a wireless power supply having an electromagnetic field source capable of generating an electromagnetic field;

a remote device separate from wireless power supply and being capable of being selectively placed adjacent to said electromagnetic field source;

an electromagnetic shield disposed between said electromagnetic field source and said remote device, said electromagnetic shield having sufficient permeability to prevent passage of a significant portion of said electromagnetic field from said electromagnetic field source to said remote device; and

a magnetic field source selectively operable to substantially saturate at least a region of said electromagnetic shield such that a substantial greater portion of said electromagnetic field is capable of passing from said electromagnetic field source to said remote device through said saturated region.

41. The system of claim 40 wherein said electromagnetic field source includes a primary coil and a driver for applying power to said primary coil to generate and electromagnetic field.

42. The system of claim 41 further including a power transfer surface disposed adjacent said primary coil.

43. The system of claim 40 wherein said electromagnetic shield is incorporated into said wireless power supply between said primary coil and said power transfer surface.

44. The system of claim 43 wherein said magnetic field source is carried by said remote device, whereby placement said remote device on said power transfer surface positions said magnetic field source in a position to substantially saturate at least a portion of said electromagnetic shield.

45. The system of claim 44 wherein said magnetic field source includes one or more electromagnets.

46. The system of claim 44 wherein said magnetic field source includes one or more permanent magnets.

47. The system of claim 46 wherein said one or more permanent magnets are selected to open an aperture in said electromagnetic shield of appropriate size and shape to allow said electromagnetic field to reach said remote device.

48. The system of claim 43 wherein said magnetic field source includes a plurality of electromagnets arranged in a pattern adjacent to said electromagnetic shield, each of said electromagnets being selectively operable to selectively generate a magnetic field of sufficient strength to substantially saturate an adjacent portion of said electromagnetic shield, whereby said electromagnets may be individually actuated to selectively produce regionalized apertures through said shield.

49. The system of claim 40 wherein said electromagnetic field generator includes a plurality of primary coils;

and

wherein said magnetic field source includes a plurality of electromagnets.

50. The system of claim 40 wherein said magnetic field source is capable of selectively varying a strength of a magnetic field generated by said magnetic field source.

51. The system of claim 40 wherein said electromagnetic shield is manufactured from a soft magnetic material having a permeability curve with a first region of high permeability, a second region of low permeability and a transition region between said first region and said second region, said DC magnetic field source having a field strength selected to transition said shield from said first region to said second region.

52. A method of selective shielding comprising the steps of:

providing an electromagnetic field generator;

providing an electromagnetic shield capable of selectively transitioning between a saturated state and an unsaturated state;

providing a DC magnetic field source capable of producing a DC magnetic field of sufficient strength to cause at least a portion of the electromagnetic shield to transition from the unsaturated state to the saturated state;

positioning the shield between the electromagnetic field generator and an electromagnetic field receiver;

operating the electromagnetic field generator to produce an electromagnetic field; and

selectively saturating at least a portion of the shield with the DC magnetic field generator to selectively cause at least a portion of the electromagnetic shield to transition to the saturated state, whereby the shield in the saturated state permits a substantially greater portion of the electromagnetic field to reach the electromagnetic receiver than in the unsaturated state.

53. The method of claim 52 wherein said selectively saturating step is further defined as positioning a permanent magnet adjacent the shield.

54. The method of claim 52 wherein said selectively saturating step is further defined as operating an electromagnet positioned proximate to the shield to generate the DC magnetic field.

55. The method of claim 52 wherein said positioning step is further defined as positioning the shield between the electromagnetic field generator and a transfer surface;

and

further including the step of a placing a remote device on the transfer surface, the remote device including the electromagnetic receiver.

56. The method of claim 52 wherein the DC magnetic field source is a permanent magnet;

and

said step of selectively saturating includes placing the permanent magnet adjacent the shield.

57. The method of claim 56 wherein the permanent magnet is carried by a remote device;

and

said step of selectively saturating includes placing the remote device adjacent the shield.

58. The method of claim 52 wherein the electromagnetic field generator is a plurality of primaries;

and

said step of operating the electromagnetic field generator includes operating at least one of the plurality of primaries.

59. The method of claim 58 wherein said selectively saturating step is further defined as saturating the shield in a region proximate to the at least one operating primary.

60. The method of claim 52 wherein said operating step includes operating the electromagnetic field generator to produce an electromagnetic field to wirelessly transfer power.

61. The method of claim 52 wherein said operating step includes operating the electromagnetic field generator to produce an electromagnetic field to wirelessly transfer communications.

62. The method of claim 52 wherein said operating step includes operating the electromagnetic field generator to produce an electromagnetic field to wirelessly transfer power and to wirelessly transfer communications.

63. The method of claim 52 further including the step of manufacturing the shield from a soft magnetic material having a permeability curve with a first region of high permeability, a second region of low permeability and a transition region between said first region and said second region;

and

wherein the DC magnetic field source has a field strength selected to transition the electromagnetic shield from the first region to the second region.

64. The method of claim 63 wherein the soft magnetic material is a flexible composite ferrite.

65. The method of claim 52 further including the step of selectively varying a strength of a DC magnetic field generated by the DC magnetic field source to selectively vary saturation of the electromagnetic shield.

66. A wireless power transfer system comprising:

a wireless power supply having an electromagnetic field source capable of generating an electromagnetic field, said wireless power supply having a power transfer surface;

an electromagnetic shield disposed adjacent said electromagnetic field source between said electromagnetic field source and said power transfer surface, said electromagnetic shield having sufficient permeability to prevent pass-through of a significant portion of said electromagnetic field from said electromagnetic field source to said power transfer surface; and

a plurality of remote devices separate from wireless power supply and being capable of being selectively placed on said power transfer surface, each of said remote devices including a magnetic field source operable to substantially saturate at least a region of said electromagnetic shield such that a substantially greater portion of said electromagnetic field is capable of passing through said electromagnetic shield from said electromagnetic field source to said remote device through said saturated region.

67. The system of claim 66 wherein said magnetic field source is a variable strength magnetic field source.

68. The system of claim 66 wherein said magnetic field source is an electromagnet having an adjustable strength.

69. The system of claim 68 wherein each of said remote devices includes a received power sensor and a magnetic field strength control system for adjusting said strength as a function of an output of said received power sensor.

70. The system of claim 69 wherein said received power sensor includes at least one of a current sensor and a voltage sensor.

71. The system of claim 70 wherein said magnetic field strength control system includes a controlled current source coupled to said electromagnet.

72. The system of claim 71 wherein said magnetic field strength control system is operatively coupled to said controlled current source to control an output level of said controlled current source as a function of said received power sensor and a desired received power.

73. The system of claim 66 wherein each of said remote devices includes a communication circuit for communicating a power requirement to said wireless power supply;

and

wherein said wireless power supply includes a communication circuit to receive said power requirement from each of said remote devices and a power output controller to control an output power of said wireless power supply as a function of said received power requirements from each of said remote devices.

74. The system of claim 66 wherein said wireless power supply includes a communication circuit to receive communications from said remote device and a power output controller to control an output power as a function of said communications received from said remote devices.

75. The system of claim 74 wherein said magnetic field source is an electromagnet having an adjustable strength;

and

wherein at least one of said remote devices is configured to send a communication to said wireless power supply when said electromagnet is at full strength and said remote device is not receiving sufficient power.

76. The system of claim 66 wherein said transfer surface is capable of simultaneously receiving a plurality of remote devices, whereby said wireless power supply is capable of simultaneously wirelessly transferring power to more than one of said remote devices;

and

wherein said magnetic field source is a magnetic field source having a variable strength, each of said remote devices including a received power sensor and a magnetic field strength control system for adjusting said strength as a function of an output of said received power sensor, whereby each of said remote devices is capable of individually controlling an amount of power received from said wireless power supply.