FOREIGN OBJECT DETECTION IN WIRELESS ENERGY TRANSFER SYSTEMS

• US 20140111019A1
• Filed: 10/21/2013
• Published: 04/24/2014
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: WiTricity Corporation
• Inventors: Kurs, Andre B., Verghese, Simon, Kesler, Morris P., Hall, Katherine L., Lou, Herbert Toby, Roy, Arunanshu Mohan, Katz, Noam, Buenrostro, Christopher
• Granted Patent: US 9,465,064 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2250/10 by alarm
• CPC Class Codes: B60L 2270/147 electro magnetic [EMI]
• 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: B60L 53/36 by positioning the vehicle
• CPC Class Codes: B60L 53/38 specially adapted for charging by inductive energy transfer
• CPC Class Codes: B60L 53/65 involving identification of vehicles or their battery types
• CPC Class Codes: G01R 29/0814 Field measurements related to measuring influence on or from apparatus, components or humans EMC, EMI and similar testing in general G01R31/001, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00
• CPC Class Codes: G01V 3/10 using induction coils
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005
• 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 50/12 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 50/90 involving detection or optimisation of position, e.g. alignment
• 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 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles
• CPC Class Codes: Y02T 90/167 : Systems integrating technologies related to power network operation and communication or information technologies for supporting the interoperability of electric or hybrid vehicles, i.e. smartgrids as interface for battery charging of electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: Y04S 30/14 : Details associated with the interoperability, e.g. vehicle recognition, authentication, identification or billing

Abstract

The disclosure features apparatus, methods, and systems for wireless power transfer that include a power source featuring at least one resonator, a power receiver featuring at least one resonator, a first detector featuring one or more loops of conductive material and configured to generate an electrical signal based on a magnetic field between the power source and the power receiver, a second detector featuring conductive material, and control electronics coupled to the first and second detectors, where during operation, the control electronics are configured to measure the electrical signal of the first detector and compare the measured electrical signal of the first detector to baseline electrical information for the first detector to determine information about whether debris is positioned between the power source and the power receiver.

Claims

1. A wireless power transfer system, comprising:

a power source comprising at least one resonator;

a power receiver comprising at least one resonator, wherein the power receiver is configured to receive electrical power transmitted wirelessly by the power source;

a first detector comprising one or more loops of conductive material, wherein the first detector is configured to generate an electrical signal based on a magnetic field between the power source and the power receiver;

a second detector comprising conductive material; and

control electronics coupled to the first and second detectors, wherein during operation of the system, the control electronics are configured to;

measure the electrical signal of the first detector;

compare the measured electrical signal of the first detector to baseline electrical information for the first detector to determine information about whether debris is positioned between the power source and the power receiver;

measure an electrical signal of the second detector, wherein the electrical signal of the second detector is related to a capacitance of the second detector; and

compare the measured electrical signal of the second detector to baseline electrical information for the second detector to determine information about whether a living object is positioned between the power source and the power receiver.

2. The system of claim 1, wherein the power source is a component of a vehicle charging station.

3. The system of claim 1, wherein the power receiver is a component of a vehicle.

4. The system of claim 1, wherein the electrical signal generated by the first detector comprises at least one of a voltage and a current.

5. The system of claim 1, wherein the electrical signal of the second detector comprises at least one of a voltage and a capacitance.

6. The system of claim 1, wherein the baseline electrical information for the first detector corresponds to an electrical signal of the first detector when no debris is positioned between the power source and the power receiver.

7. The system of claim 1, wherein the baseline electrical information for the second detector corresponds to an electrical signal of the second detector when no living objects are positioned between the power source and the power receiver.

8. The system of claim 1, wherein determining information about whether debris is positioned between the power source and the power receiver comprises comparing a likelihood value that debris is positioned between the power source and the power receiver to a threshold value.

9. The system of claim 8, wherein the control electronics are configured to determine the likelihood value by calculating mean and covariance matrices for the baseline electrical information for the first detector, and determining the likelihood value based on the mean and covariance matrices.

10. The system of claim 1, wherein determining information about whether a living object is positioned between the power source and the power receiver comprises comparing the measured electrical signal of the second detector to a threshold value.

11. The system of claim 1, wherein the first detector comprises multiple loops of conductive material positioned in at least a first plane between the power source and the power receiver.

12. The system of claim 11, wherein the second detector comprises a length of conductive material positioned in at least a second plane between the power source and the power receiver.

13. The system of claim 12, wherein the first and second planes are parallel.

14. The system of claim 12, wherein the first and second planes are the same plane.

15. The system of claim 12, a magnetic field generated by the power source in the second plane has a full width at half maximum cross-sectional distribution, and wherein a circular perimeter of minimum size that encircles the second detector in the second plane has an enclosed area that is 100% or more of the full width at half maximum cross-sectional distribution.

16. The system of claim 15, wherein the circular perimeter has an enclosed area that is 150% or more of the full width at half maximum cross-sectional distribution.

17. The system of claim 12, wherein the length of conductive material forms a serpentine pathway in the second plane.

18. The system of claim 12, wherein the length of conductive material comprises a plurality of segments extending substantially in a common direction, and wherein a spacing between at least some of the segments varies in a direction perpendicular to the common direction.

19. The system of claim 18, wherein a magnetic flux density generated by the power source in a first region of the second plane is larger than a magnetic flux density in a second region of the second plane, and wherein a spacing between successive segments in the first region is smaller than in the second region.

20. The system of claim 11, wherein the first detector comprises a plurality of loops spaced from one another in the first plane, and wherein a spacing between adjacent loops varies.

21. The system of claim 20, wherein a magnetic flux density generated by the power source in a first region of the first plane is larger than a magnetic flux density in a second region of the first plane, and wherein the spacing between adjacent loops is smaller in the first region than in the second region.

22. The system of claim 14, wherein the first and second planes are positioned closer to the power receiver than to the power source.

23. The system of claim 1, wherein a total cross-sectional area of the at least one resonator of the power receiver is 80% or more of a full-width at half maximum cross-sectional area of a magnetic field generated by the power source at a position of the power receiver.

24. The system of claim 23, wherein the total cross-sectional area is 100% or more of the full-width at half maximum cross-sectional area of the magnetic field.

25. The system of claim 1, wherein the power source is configured to transfer 1 kW or more of power to the power receiver.

26. The system of claim 1, wherein the power source is configured to transfer power at multiple different energy transfer rates to the power receiver.

27. The system of claim 26, wherein the control electronics are configured to:

adjust the power source to transfer power at a selected one of the multiple different energy transfer rates; and

obtain baseline electrical information that corresponds to the selected energy transfer rate.

28. The system of claim 27, wherein obtaining the baseline electrical information comprises retrieving the information from an electronic storage unit.

29. The system of claim 27, wherein the control electronics are configured to measure the baseline electrical information by:

activating the power source with no debris in the vicinity of the power source to generate a magnetic flux through the first detector; and

measuring the electrical signal of the first detector in response to the magnetic flux.

30. The system of claim 29, wherein the control electronics are configured to activate the power source and to measure the electrical signal of the first detector with the power source and the power receiver at least partially aligned.

31. The system of claim 29, wherein the control electronics are configured to activate the power source and to measure the electrical signal of the first detector without power transfer occurring between the power source and the power receiver.

32. The system of claim 1, wherein the power source is configured to generate a magnetic flux of at least 6.25 μ

T at a position between the power source and the power receiver.

33. The system of claim 1, wherein the first detector comprises multiple loops, and wherein the control electronics are configured to measure electrical signals generated by at least some of the multiple loops to determine information about misalignment between the power source and the power receiver based on the measured electrical signal.

34. The system of claim 33, wherein the at least some of the multiple loops are positioned adjacent to an edge of the power source.

35. The system of claim 34, wherein the control electronics are configured to determine the information about misalignment by comparing electrical signals generated by the at least some of the multiple loops.

36. The system of claim 8, wherein the control electronics are configured so that if the likelihood value corresponding to whether debris is positioned between the power source and the power receiver exceeds the threshold value, the control electronics interrupt wireless power transfer between the power source and the power receiver.

37. The system of claim 8, wherein the control electronics are configured so that if the likelihood value corresponding to whether debris is positioned between the power source and the power receiver exceeds the threshold value, the control electronics reduce an energy transfer rate between the power source and the power receiver.

38. The system of claim 8, wherein the control electronics are configured so that if the likelihood value corresponding to whether debris is positioned between the power source and the power receiver exceeds the threshold value, the control electronics provide a warning indicator to a user of the wireless power transfer system.

39. The system of claim 10, wherein the control electronics are configured so that if the measured electrical signal of the second detector exceeds the threshold value, the control electronics interrupt wireless power transfer power the power source and the power receiver.

40. The system of claim 10, wherein the control electronics are configured so that if the measured electrical signal of the second detector exceeds the threshold value, the control electronics reduce a magnitude of a magnetic field generated by the power source.

41. The system of claim 10, wherein the control electronics are configured so that if the measured electrical signal of the second detector exceeds the threshold value, the control electronics provide a warning indicator to a user of the wireless power transfer system.

42. The system of claim 1, wherein each resonator in the power source is an electromagnetic resonator having a resonant frequency f=ω

/2π

, an intrinsic loss rate Γ

, and a Q-factor Q=ω

/(2Γ

), and wherein the Q-factor for at least one of the resonators in the power source is greater than 100.

43. The system of claim 42, wherein each resonator in the power source has a capacitance and an inductance that define the resonant frequency f.

44. The system of claim 42, wherein the Q-factor for at least one of the resonators in the power source is greater than 300.

45. The system of claim 1, wherein each resonator in the power receiver is an electromagnetic resonator having a resonant frequency f=ω

/2π

, an intrinsic loss rate Γ

, and a Q-factor Q=w/(2Γ

), and wherein the Q-factor for at least one of the resonators in the power receiver is greater than 100.

46. The system of claim 45, wherein each resonator in the power receiver has a capacitance and an inductance that define the resonant frequency f.

47. The system of claim 45, wherein the Q-factor for at least one of the resonators in the power receiver is greater than 300.

48. A method, comprising:

measuring an electrical signal generated by a first detector comprising one or more loops of conductive material positioned between a power source and a power receiver in a wireless power transfer system;

comparing the measured electrical signal generated by the first detector to baseline electrical information for the first detector to determine information about whether debris is positioned between the power source and the power receiver;

measuring an electrical signal generated by a second detector comprising conductive material, wherein the electrical signal of the second detector is related to a capacitance of the second detector; and

comparing the measured electrical signal generated by the second detector to baseline electrical information for the second detector to determine information about whether a living object is positioned between the power source and the power receiver.

49. The method of claim 48, wherein the power receiver is a component of a vehicle, the method comprising using the power source to transfer electrical power to the vehicle.

50. The method of claim 48, wherein the baseline electrical information for the first detector corresponds to an electrical signal of the first detector when no debris is positioned between the power source and the power receiver.

51. The method of claim 48, wherein the baseline electrical information for the second detector corresponds to an electrical signal of the second detector when no living objects are positioned between the power source and the power receiver.

52. The method of claim 48, wherein determining information about whether debris is positioned between the power source and the power receiver comprises comparing a likelihood value that debris is positioned between the power source and the power receiver to a threshold value.

53. The method of claim 52, further comprising determining the likelihood value by calculating mean and covariance matrices for the baseline electrical information for the first detector, and determining the likelihood value based on the mean and covariance matrices.

54. The method of claim 48, wherein determining information about whether a living object is positioned between the power source and the power receiver comprises comparing the measured electrical signal of the second detector to a threshold value.

55. The method of claim 48, further comprising using the power source to transfer 1 kW or more of power to the power receiver.

56. The method of claim 48, wherein the power source is configured to transfer power at multiple different energy transfer rates to the power receiver, the method comprising:

adjusting the power source to transfer power at a selected one of the multiple different energy transfer rates; and

obtaining baseline electrical information that corresponds to the selected energy transfer rate.

57. The method of claim 56, wherein obtaining the baseline electrical information comprises retrieving the information from an electronic storage unit.

58. The method of claim 56, further comprising:

activating the power source with no debris in the vicinity of the power source to generate a magnetic flux through the first detector; and

measuring the electrical signal of the first detector in response to the magnetic flux to obtain the baseline electrical information for the first detector.

59. The method of claim 58, further comprising activating the power source and measuring the electrical signal of the first detector with the power source and the power receiver at least partially aligned.

60. The method of claim 58, further comprising activating the power source and measuring the electrical signal of the first detector without power transfer occurring between the power source and the power receiver.

61. The method of claim 48, further comprising generating a magnetic flux of 6.25 μ

T or more between the power source and the power receiver.

62. The method of claim 48, further comprising measuring electrical signals generated by multiple loops of the first detector, and determining information about misalignment between the power source and the power receiver based on the measured electrical signals.

63. The method of claim 62, further comprising determining the information about misalignment by comparing electrical signals generated by the multiple loops.

64. The method of claim 52, further comprising interrupting wireless power transfer between the power source and the power receiver if the likelihood value corresponding to whether debris is positioned between the power source and the power receiver exceeds the threshold value.

65. The method of claim 52, further comprising reducing an energy transfer rate between the power source and the power receiver if the likelihood value corresponding to whether debris is positioned between the power source and the power receiver exceeds the threshold value.

66. The method of claim 52, further comprising providing a warning indicator if the likelihood value corresponding to whether debris is positioned between the power source and the power receiver exceeds the threshold value.

67. The method of claim 54, further comprising interrupting wireless power transfer between the power source and the power receiver if the measured electrical signal of the second detector exceeds the threshold value.

68. The method of claim 54, further comprising reducing an energy transfer rate between the power source and the power receiver if the measured electrical signal of the second detector exceeds the threshold value.

69. The method of claim 54, further comprising providing a warning indicator if the measured electrical signal of the second detector exceeds the threshold value.

70. An apparatus for detecting debris and living objects, the apparatus comprising:

a first detector comprising one or more loops of conductive material, wherein the first detector is configured to generate an electrical signal based on a magnetic field between a power source and a power receiver of a wireless power transfer system;

a second detector comprising conductive material; and

control electronics coupled to the first and second detectors, wherein during operation of the wireless power transfer system, the control electronics are configured to;

measure the electrical signal of the first detector;

compare the measured electrical signal of the first detector to baseline electrical information for the first detector to determine information about whether debris is positioned between the power source and the power receiver of the wireless power transfer system;

measure an electrical signal of the second detector, wherein the electrical signal of the second detector is related to a capacitance of the second detector; and

compare the measured electrical signal of the second detector to baseline electrical information for the second detector to determine information about whether a living object is positioned between the power source and the power receiver of the wireless power transfer system.