COIL ARRANGEMENTS IN WIRELESS POWER TRANSFER SYSTEMS FOR LOW ELECTROMAGNETIC EMISSIONS

• US 20140125140A1
• Filed: 03/05/2013
• Published: 05/08/2014
• Est. Priority Date: 11/02/2012
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Widmer, Hanspeter, Keeling, Nicholas A.
• Granted Patent: US 10,014,104 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• 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: H01F 2003/005 Magnetic cores for receiving several windings with perpendicular axes, e.g. for antennae or inductive power transfer
• 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 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• 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 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• 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: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

This disclosure provides systems, methods and apparatus for wireless power transfer. In one aspect the disclosure provides an apparatus for wirelessly communicating power. The apparatus includes a first conductive structure, with a length greater than a width, configured to wirelessly receive power via a magnetic field. The first conductive structure includes two substantially co-planar loops. The first conductive structure has a first edge and a second edge each intersecting a geometric line along the length of the first conductive structure. The apparatus further includes a second conductive structure, with a length greater than width, positioned between the first conductive structure and a magnetic material and configured to wirelessly receive power via the magnetic field. The length of the second conductive structure is substantially equal to at least a distance along the geometric line between the first edge and the second edge of the first conductive structure.

Claims

1. An apparatus for wirelessly communicating power, comprising:

a first conductive structure configured to wirelessly receive power via a magnetic field, the first conductive structure having a length greater than a width, the first conductive structure comprising a first loop and a second loop enclosing a first area and a second area, respectively, the first loop having a first lower surface and the second loop having a second lower surface that are substantially coplanar, the first conductive structure having a first edge and a second edge each intersecting a first geometric line along the length of the first conductive structure; and

a second conductive structure positioned between the first conductive structure and a magnetic material and configured to wirelessly receive power via the magnetic field, the second conductive structure comprising a third loop enclosing a third area, the second conductive structure having a length greater than a width, the length of the second conductive structure being substantially equal to at least a distance along the first geometric line between the first edge and the second edge of the first conductive structure.

2. The apparatus of claim 1, wherein the magnetic material, the first conductive structure, and the second conductive structure are substantially rectangular having lengths aligned along the first geometric line.

3. The apparatus of claim 2, wherein the first conductive structure and the second conductive structure are configured to be positioned over a third conductive structure configured to generate the magnetic field, the third conductive structure being substantially rectangular and having a second geometric line intersecting the length of the third conductive structure that is perpendicular to the first geometric line when the first conductive structure and the second conductive structure are positioned over the third conductive structure.

4. The apparatus of claim 2, wherein a first rectangle defined collectively by the magnetic material, first conductive structure, and second conductive structure has a width c and a length c+d, and wherein c divided by d is substantially equal to c+d divided by c.

5. The apparatus of claim 3, wherein a second rectangle formed by the third conductive structure has a width a and a length a+b, and wherein a divided by b is substantially equal to a+b divided by a.

6. The apparatus of claim 2, wherein the first and second conductive structures collectively define a first center point located in a center of a geometric rectangle covering the surface areas of the first and second conductive structures, wherein the third conductive structure defines a second center point located in a center of a geometric rectangle covering the surface area of the third conductive structure, and wherein a set of points, defined by offset distances between the first and second points, at which an amount of coupling is above a threshold defines a substantially rectangular region, the amount of coupling defined at least in part by a value derived from a first coupling coefficient measuring coupling between the first conductive structure and the third conductive structure and a second coupling coefficient measuring coupling between the second conductive structure and the third conductive structure.

7. The apparatus of claim 6, wherein the third conductive structure comprises a loop defining a fourth area, wherein a length of the substantially rectangular region is substantially equal to plus or minus one-half multiplied by a value derived from a difference between a length of the fourth area and a width of the third area.

8. The apparatus of claim 7, wherein the third conductive structure has a first outer edge along a first side and a first inner edge along the first side and a second outer edge along a second side and a second inner edge along the second side, and wherein a width of the substantially rectangular region is substantially equal to plus or minus one-half multiplied by a distance between a first center point between the first outer edge and the first inner edge and a second center point between the second outer edge and the second inner edge.

9. The apparatus of claim 1, wherein the first conductive structure has a substantially horizontally polarized magnetic moment, wherein the second conductive structure has a substantially vertically polarized magnetic moment.

10. The apparatus of claim 1, wherein the first conductive structure and the second conductive structure are positioned to maintain a substantial absence of mutual coupling between the first conductive structure and the second conductive structure.

11. The apparatus of claim 10, wherein a net sum of a magnetic field generated by the first conductive structure and that intersects the second conductive structure is substantially zero.

12. The apparatus of claim 1, wherein the first conductive structure comprises at least one of:

a first coil wound to enclose the first area and the second area;

or

a second and third coil wound to enclose the first area and second area, respectively.

13. The apparatus of claim 1, wherein the first and second conductive structures are capacitively loaded and configured to resonate at a resonant frequency substantially equal to a frequency of the magnetic field, and wherein the first and second conductive structures are configured to inductively receive power via the magnetic field at a level sufficient to charge or power a vehicle.

14. The apparatus of claim 1, further comprising a receive circuit coupled to the first and second conductive structures and configured to power or charge an electric vehicle based on at least a portion a combination of the power received via the first and second conductive structures.

15. The apparatus of claim 1, further comprising a controller configured to receive measurements indicative of an amount of coupling between each of the first and second conductive structures and a transmitter conductive structure, the controller configured to selectively de-activate the first or second conductive structure based on the amount of coupling.

16. The apparatus of claim 1, wherein the apparatus further comprises a controller configured detect an amount of coupling between each of the first and second conductive structures and a transmitter conductive structure and configured to control at least one of an amplitude or a phase of currents in the first and second conductive structures based on the amount of coupling.

17. The apparatus of claim 16, wherein the controller is configured to control at least one of the amplitude or the phase of the currents to maintain a level of electromagnetic emissions below a threshold.

18. A method of wirelessly communicating power comprising:

wirelessly receiving power via a first conductive structure via a magnetic field, the first conductive structure having a length greater than a width, the first conductive structure comprising a first loop and a second loop enclosing a first area and a second area, respectively, the first loop having a first lower surface and the second loop having a second lower surface that are substantially coplanar, the first conductive structure having a first edge and a second edge each intersecting a geometric line along the length of the first conductive structure; and

wirelessly receiving power via a second conductive structure positioned between the first conductive structure and a magnetic material, the second conductive structure enclosing a third area, the second conductive structure having a length greater than a width, the length of the second conductive structure being substantially equal to at least a distance along the geometric line between the first edge and the second edge of the first conductive structure.

19. The method of claim 18, wherein the magnetic material, the first conductive structure, and the second conductive structure are substantially rectangular having lengths aligned along the first geometric line, wherein the first conductive structure and the second conductive structure are configured to be positioned over a third conductive structure configured to generate the magnetic field, the third conductive structure being substantially rectangular and having a second geometric line intersecting the length of the third conductive structure that is perpendicular to the first geometric line when the first conductive structure and the second conductive structure are positioned over the third conductive structure.

20. The method of claim 19, wherein the first and second conductive structures collectively define a first center point located in a center of a geometric rectangle covering the surface areas of the first and second conductive structures, wherein the third conductive structure defines a second center point located in a center of a geometric rectangle covering the surface area of the third conductive structure, and wherein a set of points, defined by offset distances between the first and second points, at which an amount of coupling is above a threshold defines a substantially rectangular region, the amount of coupling defined at least in part by a value derived from a first coupling coefficient measuring coupling between the first conductive structure and the third conductive structure and a second coupling coefficient measuring coupling between the second conductive structure and the third conductive structure.

21. The method of claim 18, wherein the first conductive structure and the second conductive structure are positioned to maintain a substantial absence of mutual coupling between the first conductive structure and the second conductive structure.

22. The method of claim 18, wherein the first and second conductive structures are capacitively loaded and configured to resonate at a resonant frequency substantially equal to a frequency of the magnetic field, and wherein the wirelessly receiving power comprises inductively receiving power via the magnetic field at the first and second conductive structures at a level sufficient to charge or power a vehicle.

23. An apparatus for wirelessly communicating power, comprising:

a first means for wirelessly receiving power via a magnetic field, the first receiving means having a length greater than a width, the first receiving means comprising a first loop and a second loop enclosing a first area and a second area, respectively, the first loop having a first lower surface and the second loop having a second lower surface that are substantially coplanar, the first receiving means having a first edge and a second edge each intersecting a geometric line along the length of the first receiving means; and

a second means for wirelessly receiving power via the magnetic field positioned between the first receiving means and a magnetic material, the second receiving means enclosing a third area, the second receiving means having a length greater than a width, the length of the second receiving means being substantially equal to at least a distance along the geometric line between the first edge and the second edge of the first receiving means.

24. The apparatus of claim 23, wherein the magnetic material, the first receiving means, and the second receiving means are substantially rectangular having lengths aligned along the first geometric line, wherein the first receiving means and the second receiving means are configured to be positioned over a means for generating the magnetic field, the generating means being substantially rectangular and having a second geometric line intersecting the length of the generating means that is perpendicular to the first geometric line when the first receiving means and the second receiving means are positioned over the generating means.

25. The method of claim 24, wherein the first and second receiving means collectively define a first center point located in a center of a geometric rectangle covering the surface areas of the first and second receiving means, wherein the generating means defines a second center point located in a center of a geometric rectangle covering the surface area of the generating means, and wherein a set of points, defined by offset distances between the first and second points, at which an amount of coupling is above a threshold defines a substantially rectangular region, the amount of coupling defined at least in part by a value derived from a first coupling coefficient measuring coupling between the first receiving means and the generating means and a second coupling coefficient measuring coupling between the second receiving means and the generating means.

26. The method of claim 23, wherein the first receiving means and the second receiving means are positioned to maintain a substantial absence of mutual coupling between the first receiving means and the second receiving means.

27. The method of claim 23, wherein the first and second receiving means are capacitively loaded and configured to resonate at a resonant frequency substantially equal to a frequency of the magnetic field, and wherein the wirelessly receiving power comprises inductively receiving power via the magnetic field at the first and second receiving means at a level sufficient to charge or power a vehicle.

28. An apparatus for wirelessly communicating power comprising:

a transmit circuit configured to output a time-varying signal; and

a conductive structure configured to receive the time-varying signal and to generate an electromagnetic field at a level sufficient to wirelessly transfer power for powering or charging a receiver device, the conductive structure having a rectangular form factor having a width a and a length a+b, and wherein a divided by b is substantially equal to a+b divided by a.

29. The apparatus of claim 28, wherein conductive structure forms a first layer, wherein the apparatus further comprises a magnetic material forming a second layer and a conductive back plate forming a third layer, wherein the magnetic material is positioned between the conductive structure and the conductive back plate.

30. The apparatus of claim 29, wherein a rectangle defined by the magnetic material extends beyond the conductive structure along both the length and the width.

31. The apparatus of claim 30, wherein the rectangle defined by the magnetic material extends beyond the conductive structure by substantially a value derived from 0.15 multiplied by the width a.

32. The apparatus of claim 28, wherein the receiver device comprises a pad affixed to a vehicle, the pad comprising a conductive structure configured to wirelessly receive the power, wherein a rectangle defined by the pad has a width c and a length c+d, and wherein c divided by d is substantially equal to c+d divided by c.

33. The apparatus of claim 28, wherein the conductive structure has a substantially vertically polarized magnetic moment.

34. The apparatus of claim 28, wherein the conductive structure is capacitively loaded and configured to resonate at a frequency of the time-varying signal.

35. The apparatus of claim 28, wherein the conductive structure comprises a coil wound to enclose a single area.

36. A method of wirelessly communicating power comprising:

outputting a time-varying signal from a transmit circuit; and

receiving the time-varying signal and generating, at a conductive structure, an electromagnetic field at a level sufficient to wirelessly transfer power for powering or charging a receiver device, the conductive structure having a rectangular form factor having a width a and a length a+b, and wherein a divided by b is substantially equal to a+b divided by a.

37. The method of claim 36, wherein the conductive structure has a substantially vertically polarized magnetic moment, wherein the conductive structure is capacitively loaded and configured to resonate at a frequency of the time-varying signal.

38. The method of claim 36, wherein the conductive structure comprises a coil wound to enclose a single area.

39. An apparatus of wirelessly communicating power comprising:

means for outputting a time-varying signal; and

means for generating an electromagnetic field based on the time-varying signal, the electromagnetic field at a level sufficient to wirelessly transfer power for powering or charging a receiver device, the generating means having a rectangular form factor having a width a and a length a+b, and wherein a divided by b is substantially equal to a+b divided by a.

40. The apparatus of claim 39, wherein the generating means forms a first layer, wherein the apparatus further comprises a magnetic material forming a second layer and a conductive back plate forming a third layer, wherein the magnetic material is positioned between the conductive structure and the conductive back plate, wherein a rectangle defined by the magnetic material extends beyond the conductive structure along both the length and the width.

41. The apparatus of claim 39, wherein the generating means has a substantially vertically polarized magnetic moment, wherein the generating means is capacitively loaded and configured to resonate at a frequency of the time-varying signal.

42. The apparatus of claim 39, wherein the generating means comprises a coil wound to enclose a single area.

43. An apparatus for wirelessly communicating power, comprising:

a first conductive structure configured to wirelessly transmit or receive power via a first electromagnetic field at a level sufficient to power or charge a load, the first conductive structure comprising a first loop enclosing a first area; and

a second conductive structure configured to wirelessly transmit or receive power via a second electromagnetic field at a level sufficient to power or charge the load, the second conductive structure positioned inside the first area and substantially co-planar with the first conductive structure, the second conductive structure comprising a second loop and a third loop enclosing a second area and a third area, respectively, the second loop having a second lower surface and the third loop having a third lower surface that are substantially coplanar.

44. The apparatus of claim 43, wherein the apparatus further comprises a controller configured detect an amount of coupling between each of the first and second conductive structures and a third conductive structure and configured to control at least one of an amplitude or a phase of currents in the first and second conductive structures based on the amount of coupling.

45. The apparatus of claim 43, wherein the first conductive structure and the second conductive structure are positioned to maintain a substantial absence of mutual coupling between the first conductive structure and the second conductive structure.

46. The apparatus of claim 43, wherein the first and second conductive structures are capacitively loaded and configured to resonate at a first frequency of the first time-varying signal and a second frequency of the second time-varying voltage, respectively.

47. A method of wirelessly communicating power, comprising:

wirelessly transmitting or receiving power, at a first conductive structure, via a first electromagnetic field at a level sufficient to power or charge a load, the first conductive structure comprising a first loop enclosing a first area; and

wirelessly transmitting or receiving power, at a second conductive structure, via a second electromagnetic field at a level sufficient to power or charge the load, the second conductive structure positioned inside the first area and substantially co-planar with the first conductive structure, the second conductive structure comprising a second loop and a third loop enclosing a second area and a third area, respectively, the second loop having a second lower surface and the third loop having a third lower surface that are substantially coplanar.

48. The method of claim 47, wherein the first conductive structure and the second conductive structure are positioned to maintain a substantial absence of mutual coupling between the first conductive structure and the second conductive structure.

49. The method of claim 47, wherein the first and second conductive structures are capacitively loaded and configured to resonate at a first frequency and a second frequency, respectively.

50. An apparatus for wirelessly communicating power, comprising:

a first means for wirelessly transmitting or receiving power via a first electromagnetic field at a level sufficient to power or charge a load, the first means comprising a first loop enclosing a first area; and

a second means for wirelessly transmitting or receiving power via a second electromagnetic field at a level sufficient to power or charge the load, the second means positioned inside the first area and substantially co-planar with the first means, the second means comprising a second loop and a third loop enclosing a second area and a third area, respectively, the second loop having a second lower surface and the third loop having a third lower surface that are substantially coplanar.

51. The apparatus of claim 50, wherein the first means and the second means are positioned to maintain a substantial absence of mutual coupling between the first means and the second means.

52. The apparatus of claim 50, wherein the first and second means comprise coils that are capacitively loaded and configured to resonate at a first frequency and a second frequency, respectively.