SYSTEMS, METHODS, AND APPARATUS FOR DETECTION OF METAL OBJECTS IN A PREDETERMINED SPACE

• US 20140015329A1
• Filed: 03/08/2013
• Published: 01/16/2014
• Est. Priority Date: 07/13/2012
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Widmer, Hanspeter, Bittner, Markus, Sieber, Lukas, Fischer, Marcel
• Granted Patent: US 9,726,518 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 2200/12 Bikes
• CPC Class Codes: B60L 2200/22 Microcars, e.g. golf cars
• 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 2240/525 Temperature of converter or components thereof
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2270/147 electro magnetic [EMI]
• CPC Class Codes: B60L 2270/32 of electricity
• CPC Class Codes: B60L 2270/34 of parts
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 3/0038 relating to sensors
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 53/12 Inductive energy transfer
• CPC Class Codes: B60L 53/122 Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil
• 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 53/30 : Constructional details of charging stations
• CPC Class Codes: B60L 53/305 : Communication interfaces
• CPC Class Codes: B60L 53/36 : by positioning the vehicle
• CPC Class Codes: B60L 53/37 : using optical position determination, e.g. using cameras
• CPC Class Codes: B60L 53/63 : in response to network capacity
• CPC Class Codes: B60L 53/65 : involving identification of vehicles or their battery types
• CPC Class Codes: B60L 53/68 : Off-site monitoring or control, e.g. remote control
• CPC Class Codes: B60L 55/00 : Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements
• CPC Class Codes: B60L 58/10 : for monitoring or controlling batteries
• CPC Class Codes: G01D 5/2006 : by influencing the self-induction of one or more coils G01D5/22 takes precedence
• CPC Class Codes: G01N 27/725 : by using magneto-acoustical effects or the Barkhausen effect
• CPC Class Codes: G01V 3/10 : using induction coils
• 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 50/60 : responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H04B 5/73 : for taking measurements, e.g. using sensing coils
• CPC Class Codes: H04B 5/79 : for data transfer in combination with power transfer
• CPC Class Codes: Y02E 60/00 : Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• 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 10/126 : the energy generation units being or involving electric vehicles [EV] or hybrid vehicles [HEV], i.e. power aggregation of EV or HEV, vehicle to grid arrangements [V2G]
• CPC Class Codes: Y04S 30/12 : Remote or cooperative charging
• CPC Class Codes: Y04S 30/14 : Details associated with the interoperability, e.g. vehicle recognition, authentication, identification or billing

Abstract

This disclosure provides systems, methods and apparatus for detecting foreign objects. In one aspect an apparatus for detecting a presence of an object is provided. The apparatus includes a resonant circuit having a resonant frequency. The resonant circuit includes a sense circuit including an electrically conductive structure. The apparatus further includes a coupling circuit coupled to the sense circuit. The apparatus further includes a detection circuit coupled to the sense circuit via the coupling circuit. The detection circuit is configured to detect the presence of the object in response to detecting a difference between a measured characteristic that depends on a frequency at which the resonant circuit is resonating and a corresponding characteristic that depends on the resonant frequency of the resonant circuit. The coupling circuit is configured to reduce a variation of the resonant frequency by the detection circuit in the absence of the object.

Claims

1. An apparatus for detecting a presence of an object, the apparatus comprising:

a resonant circuit having a resonant frequency, the resonant circuit comprising a sense circuit comprising an electrically conductive structure;

a coupling circuit coupled to the sense circuit; and

a detection circuit coupled to the sense circuit via the coupling circuit, the detection circuit configured to detect the presence of the object in response to detecting a difference between a measured characteristic that depends on a frequency at which the resonant circuit is resonating and a corresponding characteristic that depends on the resonant frequency of the resonant circuit, and the coupling circuit configured to reduce a variation of the resonant frequency by the detection circuit in the absence of the object.

2. The apparatus of claim 1, wherein the coupling circuit comprises one of:

a capacitor electrically connected between the sense circuit and the detection circuit, the resonant circuit comprising the capacitor and the sense circuit;

a coupling loop electrically connected to the detection circuit, the coupling loop inductively coupled to the sense circuit;

or

a capacitive voltage divider configured to capacitively couple the detection circuit to the sense circuit.

3. The apparatus of claim 2, wherein the capacitor is configured to reduce variation of the resonant frequency by the detection circuit in the absence of the object, the capacitor further configured to attenuate electrical signals having frequencies lower than the resonant frequency.

4. The apparatus of claim 2, wherein the sense circuit comprises a capacitor electrically connected to the electrically conductive structure, the electrically conductive structure comprising an inductor, and wherein the capacitor and the electrically conductive structure substantially form the resonant circuit and substantially determine the resonant frequency.

5. The apparatus of claim 2, wherein the capacitive voltage divider comprises a first capacitor and a second capacitor, wherein the sense circuit comprises the first capacitor that is coupled to the electrically conductive structure that comprises an inductor, wherein the first capacitor and the electrically conductive structure substantially form the resonant circuit and substantially determine the resonant frequency, the second capacitor determining an amount of coupling between the sense circuit and the second capacitor.

6. The apparatus of claim 1, wherein the sense circuit substantially alone forms the resonant circuit and determines the resonant frequency.

7. The apparatus of claim 1, wherein the measured characteristic comprises at least one of a measured resonant frequency or a measured quality factor (Q-factor) of the resonant circuit, and wherein the corresponding characteristic is at least one of the resonant frequency or the Q-factor of the resonant circuit.

8. The apparatus of claim 1, wherein the detection circuit comprises a lead line electrically connected to the coupling circuit, and wherein the coupling circuit is further configured to reduce variation of the resonant frequency by the lead line in the absence of the object.

9. The apparatus of claim 1, wherein the electrically conductive structure is a first electrically conductive structure, and wherein the apparatus further comprises a second electrically conductive structure, different from the first electrically conductive structure, the second electrically conductive structure configured to wirelessly transmit power via a magnetic field at a level sufficient to power or charge a load.

10. The apparatus of claim 9, further comprising a transmit circuit configured to apply an alternating current to the second electrically conductive structure at a frequency, wherein the resonant frequency of the resonant circuit is higher than the frequency of the alternating current.

11. The apparatus of claim 9, wherein the first electrically conductive structure comprises a first loop defining a first plane, wherein the second electrically conductive structure comprises a second loop defining a second plane substantially parallel with the first plane, wherein the first loop is positioned over at least one of an area enclosed by the second loop or overlapping the second loop.

12. The apparatus of claim 11, further comprising a plurality of sense circuits including the sense circuit including the first loop, each of the plurality of sense circuits comprising respective electrically conductive structures each forming respective loops, the loops of the plurality of sense circuits positioned in a multi-dimensional array collectively defining a third plane, wherein the loops collectively cover at least the area enclosed by the second loop.

13. The apparatus of claim 12, wherein a diameter of each of the loops of the plurality of sense circuits is substantially equal to or less than ten percent of a diameter of the second loop.

14. The apparatus of claim 12, wherein a diameter of each of the loops of the plurality of sense circuits is substantially equal to or greater than twice a size of the object.

15. The apparatus of claim 12, wherein at least each of the sense circuits form respective resonant circuits having respective resonant frequencies, wherein the detection circuit is further configured to detect the presence of the object in response to detecting a difference between respective measured characteristics that depend on frequencies at which each of the resonant circuits are resonating and corresponding characteristic that depend on the respective resonant frequencies.

16. The apparatus of claim 1, wherein the measured characteristic comprises a measured resonant frequency, and wherein the detection circuit is configured to measure an impedance response of the resonant circuit over a range of frequencies including the resonant frequency and configured to determine the measured resonant frequency based on the impedance response.

17. The apparatus of claim 1, wherein the measured characteristic comprises a measured resonant frequency, wherein the detection circuit comprises at least one of:

a swept frequency generator configured to drive the resonant circuit with a signal over a range of frequencies and stopping driving the resonant circuit when resonance is detected to determine the measured resonant frequency;

a pulse generator configured to measure a frequency response of the resonant circuit to determine the measured resonant frequency;

or

a pseudo-random noise generator configured to measure the frequency response of the resonant circuit to determine the measured resonant frequency.

18. The apparatus of claim 1 wherein the sense circuit is a first sense circuit and the resonant circuit is a first resonant circuit, wherein the resonant frequency is a first resonant frequency, wherein the coupling circuit is a first coupling circuit,

wherein the apparatus further comprises a second resonant circuit having a second resonant frequency and comprising a second sense circuit comprising a second electrically conductive structure, the apparatus further comprising a second coupling circuit, the detection circuit coupled to the second sense circuit via the second coupling circuit, and

wherein the detection circuit is configured to detect the presence of the object further in response to detecting a difference between a second measured characteristic that depends on a frequency at which the second resonant circuit is resonating and a corresponding second characteristic that depends on the second resonant frequency of the second resonant circuit, the second coupling circuit further configured to reduce variation of the second resonant frequency by the detection circuit in the absence of the object.

19. The apparatus of claim 18, wherein the first resonant frequency of the first resonant circuit is different than the second resonant frequency of the second resonant circuit.

20. The apparatus of claim 18, wherein the first and second sense circuits comprise a first and a second loop, respectively, the first and second loops substantially co-planar.

21. The apparatus of claim 20, wherein the first loop at least partially overlaps the second loop.

22. The apparatus of claim 1, wherein the coupling circuit is at least one of weakly coupled with the sense circuit or galvanically isolated from the sense circuit.

23. A method for detecting a presence of an object, the method comprising:

applying a signal to a resonant circuit having a resonant frequency, the resonant circuit comprising a sense circuit comprising an electrically conductive structure, a coupling circuit is coupled to the sense circuit; and

detecting the presence of the object via a detection circuit coupled to the sense circuit via the coupling circuit in response to detecting a difference between a measured characteristic that depends on a frequency at which the resonant circuit is resonating and a corresponding characteristic that depends on the resonant frequency of the resonant circuit, the coupling circuit configured to reduce a variation of the resonant frequency by the detection circuit in the absence of the object.

24. The method of claim 23, wherein the electrically conductive structure is a first electrically conductive structure, and wherein the method further comprises wirelessly transmitting power via a second electrically conductive structure, different from the first electrically conductive structure, the power transmitted via a magnetic field at a level sufficient to power or charge a load.

25. The method of claim 24, wherein the first electrically conductive structure comprises a first loop defining a first plane, wherein the second electrically conductive structure comprises a second loop defining a second plane substantially parallel with the first plane, wherein the first loop is positioned over at least one of an area enclosed by the second loop or overlapping the second loop, wherein applying the signal further comprises applying a signal to a plurality of sense circuits including the sense circuit, each of the plurality of sense circuits comprising respective electrically conductive structures each forming respective loops, the loops of the plurality of sense circuits positioned in a multi-dimensional array collectively defining a third plane.

26. The method of claim 23, wherein the coupling circuit comprises one of:

a capacitor electrically connected between the sense circuit and the detection circuit, the resonant circuit comprising the capacitor and the sense circuit;

a coupling loop electrically connected to the detection circuit, the coupling loop inductively coupled to the sense circuit;

or

a capacitive voltage divider configured to capacitively couple the detection circuit to the sense circuit.

27. An apparatus for detecting a presence of an object, the apparatus comprising:

means for resonating at a resonant frequency;

means for detecting the presence of the object in response to detecting a difference between a measured characteristic that depends on a frequency at which the resonating means is resonating and a corresponding characteristic that depends on the resonant frequency of the resonating means; and

means for reducing variation of the resonant frequency by the detection means in the absence of the object.

28. The apparatus of claim 27, wherein the apparatus further comprises means for wirelessly transmitting power via a magnetic field at a level sufficient to power or charge a load.

29. The apparatus of claim 28, further comprising a plurality of means for resonating including the resonating means positioned in a multi-dimensional array, wherein the means for detecting further comprises detecting the presence of the object in response to a difference between a measured characteristic that depends on frequencies at which each of the plurality of means for resonating is resonating and a corresponding characteristic that depends on the resonant frequencies of each of the plurality of the resonating means.

30. The apparatus of claim 27, wherein the means for reducing variation of the resonant frequency comprises one of:

a capacitor electrically coupled to the detecting means, the resonating means comprising the capacitor;

a coupling loop coupled to the detecting means, the coupling loop inductively coupled to the resonating means;

or

a capacitive voltage divider configured to capacitively couple the detection means to the resonating means.

31. An apparatus for detecting a presence of an object, the apparatus comprising:

a first sense circuit comprising a first electrically conductive structure, at least the first sense circuit forming a first resonant circuit having a first resonant frequency;

a second sense circuit comprising a second electrically conductive structure, at least the second sense circuit forming a second resonant circuit having a second resonant frequency, the second resonant frequency different than the first resonant frequency; and

a detection circuit coupled to the first and second sense circuits, the detection circuit configured detect the presence of the object in response to detecting;

a difference between a first measured characteristic that depends on a frequency at which the first resonant circuit is resonating and a first corresponding characteristic that depends on the first resonant frequency, or

a difference between a second measured characteristic that depends on a frequency at which the second resonant circuit is resonating and a second corresponding characteristic that depends on the second resonant frequency.

32. The apparatus of claim 31, wherein the detection circuit is further configured detect a position of the object relative to at least one of the first and second electrically conductive structures in response to the detecting.

33. The apparatus of claim 31, wherein the first and second sense circuits each comprise a capacitor having a value tuned to determine the first and second resonant frequencies, respectively.

34. The apparatus of claim 31, further comprising a coupling circuit coupled between the first and second sense circuits and the detection circuit, the coupling circuit configured to reduce variation of the first and second resonant frequencies by the detection circuit in the absence of the object.

35. The apparatus of claim 34, wherein the coupling circuit comprises:

a coupling loop electrically connected the detection circuit, the coupling loop inductively coupled to the first and second sense circuits, the first and second sense circuits substantially alone forming the first and second resonant frequencies, respectively.

36. The apparatus of claim 34, wherein the first and second sense circuits comprise a first and second capacitor, respectively, the first and second capacitors each having values tuned to determine the first and second resonant frequencies, respectively, wherein the coupling circuit comprises a third capacitor coupled between the detection circuit and the first and second sense circuits, at least the third capacitor and the first capacitor forming a capacitive voltage divider.

37. The apparatus of claim 34, wherein the first and second sense circuits comprise a first and second capacitor, respectively, the first and second capacitors each having values tuned to determine the first and second resonant frequencies, respectively, wherein the coupling circuit comprises a third capacitor coupled between the detection circuit and the first sense circuit and a fourth capacitor coupled between the detection circuit and the second sense circuit, the third capacitor and the first capacitor forming a first capacitive voltage divider, and the fourth capacitor and the first capacitor forming a second capacitive voltage divider.

38. The apparatus of claim 31, wherein the apparatus further comprises a third electrically conductive structure, different from the first and second electrically conductive structures, the third electrically conductive structure configured to wirelessly transmit power via a magnetic field at a level sufficient to power or charge a load.

39. The apparatus of claim 31, further comprising a plurality of sense circuits including the first and second sense circuits, each of the plurality of sense circuits comprising respective electrically conductive structures including the first and second electrically conductive structures, the respective electrically conductive structures each forming respective loops, the loops positioned in a multi-dimensional array defining a first plane substantially parallel with a second plane defined by the third electrically conductive structure, wherein the loops collectively cover at least an area covered by the third electrically conductive structure.

40. The apparatus of claim 39, wherein at least each of the plurality of sense circuits form respective resonant circuits having respective resonant frequencies, wherein the detection circuit is configured detect the presence of the object in response to detecting a difference between respective measured characteristics that depend on frequencies at which the respective resonant circuits are resonating and respective corresponding characteristics that depend on the respective resonant frequencies.

41. The apparatus of claim 31, wherein the first and second measured characteristics are at least one of first and second measured resonant frequencies or first and second measured quality factors (Q-factor) of the first and second resonant circuits.

42. The apparatus of claim 31, wherein the first and second electrically conductive structure comprise first and second loops, respectively, a diameter of each of the first and second loops substantially equal to or less than twice a size of the object.

43. A method for detecting a presence of an object, the method comprising:

applying a first signal to a first sense circuit comprising a first electrically conductive structure, at least the first sense circuit forming a first resonant circuit having a first resonant frequency;

applying a second signal to a second sense circuit comprising a second electrically conductive structure, at least the second sense circuit forming a second resonant circuit having a second resonant frequency, the second resonant frequency different than the first resonant frequency; and

detecting the presence of the object via a detection circuit in response to detecting;

a difference between a first measured characteristic that depends on a frequency at which the first resonant circuit is resonating and a first corresponding characteristic that depends on the first resonant frequency, or

a difference between a second measured characteristic that depends on a frequency at which the second resonant circuit is resonating and a second corresponding characteristic that depends on the second resonant frequency.

44. The method of claim 43, wherein detecting further comprises detecting a position of the object relative to at least one of the first and second electrically conductive structures in response to the detecting.

45. The method of claim 43, further comprising wirelessly transmitting power via a third electrically conductive structure, different from the first and second electrically conductive structures, the power transmitted via a magnetic field at a level sufficient to power or charge a load.

46. An apparatus for detecting a presence of an object, the apparatus comprising:

a first means for resonating at a first resonant frequency;

a second means for resonating at a second resonant frequency, the second resonant frequency different than the first resonant frequency; and

means for detecting the presence of the object in response to detecting;

a difference between a first measured characteristic that depends on a frequency at which the first resonating means is resonating and a first corresponding characteristic that depends on the first resonant frequency, or

a difference between a second measured characteristic that depends on a frequency at which the second resonating means is resonating and a second corresponding characteristic that depends on the second resonant frequency.

47. The apparatus of claim 46, wherein the means for detecting further comprises means for detecting a position of the object relative to at least one of the first and second resonating means in response to the detecting.

48. The apparatus of claim 46, further comprising means for wirelessly transmitting power via a magnetic field at a level sufficient to power or charge a load.