Coil arrangements in wireless power transfer systems for low electromagnetic emissions

• US 10,014,104 B2
• Filed: 03/05/2013
• Issued: 07/03/2018
• Est. Priority Date: 11/02/2012
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Widmer, Hanspeter, Keeling, Nicholas A.
• Primary Examiner(s): Tran, Thienvu
• Assistant Examiner(s): Sun, Pinping
• Application Number:
  US13/786,231
• Publication Number:
  US 20140125140A1
• Time in Patent Office: 1,946 Days
• 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 generated by a base pad having a length greater than a width, 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 and 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 generated by the base pad, 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 equal to at least a distance along the first geometric line between the first edge and the second edge of the first conductive structure,

wherein the length of the first conductive structure is disposed substantially parallel to the length of the second conductive structure and substantially perpendicular to the length of the base pad.

2. The apparatus of claim 1, wherein the magnetic material, the first conductive structure, and the second conductive structure are 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 the base pad configured to generate the magnetic field, the base pad being rectangular and having a second geometric line intersecting the length of the base pad that is perpendicular to the first geometric line when the first conductive structure and the second conductive structure are positioned over the base pad.

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 equal to c+d divided by c.

5. The apparatus of claim 3, wherein a second rectangle formed by the base pad has a width a and a length a+b, and wherein a divided by b is 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 surface areas of the first and second conductive structures, wherein the base pad defines a second center point located in a center of a geometric rectangle covering a surface area of the base pad, 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 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 base pad and a second coupling coefficient measuring coupling between the second conductive structure and the base pad.

7. The apparatus of claim 6, wherein the base pad comprises a loop defining a fourth area, wherein a length of the 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 base pad 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 rectangular region is 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 first polarized magnetic moment in a first direction, wherein the second conductive structure has a second polarized magnetic moment in a second direction perpendicular to the first direction.

10. The apparatus of claim 1, wherein the first conductive structure and the second conductive structure are positioned to maintain an 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 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 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 generated by a base pad having a length greater than a width, 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 and 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 generated by the base pad 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 equal to at least a distance along the geometric line between the first edge and the second edge of the first conductive structure,

wherein the length of the first conductive structure is disposed substantially parallel to the length of the second conductive structure and substantially perpendicular to the length of the base pad.

19. The method of claim 18, wherein the magnetic material, the first conductive structure, and the second conductive structure are 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 the base pad comprising a third conductive structure configured to generate the magnetic field, the third conductive structure being 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 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 a 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 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 an 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 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. A system for wirelessly communicating power, the system comprising:

a base pad having a length greater than a width and configured to generate a magnetic field to transmit wireless power; and

a vehicle pad comprising;

a first conductive structure configured to wirelessly receive power via a magnetic field generated by the base pad, 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 and 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 generated by the base pad, 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 equal to at least a distance along the first geometric line between the first edge and the second edge of the first conductive structure,

wherein the length of the first conductive structure is disposed substantially parallel to the length of the second conductive structure and substantially perpendicular to the length of the base pad.

24. The system of claim 23, wherein the length of the second conductive structure is along the length of the first conductive structure.

25. The system of claim 24, wherein the base pad comprises a third conductive structure having a width along a first axis and a length along a second axis perpendicular to the first axis, the width of the third conductive structure greater than the length of the third conductive structure.

26. The system of claim 25, wherein during wireless power transmission, the width of the second conductive structure is positioned along the first axis and the length of the second conductive structure is positioned along the second axis.

27. The system of claim 25, wherein the first conductive structure has an axis of polarization along the length of the first conductive structure, the axis of polarization oriented perpendicularly to the first axis.

28. The system of claim 23, wherein the magnetic material, the first conductive structure, and the second conductive structure are rectangular having lengths aligned along the first geometric line.

29. The system of claim 28, wherein the first conductive structure and the second conductive structure are configured to be positioned over the base pad, the base pad having a second geometric line intersecting a length of the base pad and oriented perpendicularly to the first geometric line when the first conductive structure and the second conductive structure are positioned over the base pad.

30. The system of claim 28, 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 equal to c+d divided by c.

31. The system of claim 30, wherein a second rectangle formed by the base pad has a width a and a length a+b, and wherein a divided by b is equal to a+b divided by a.

32. The system of claim 28, wherein the first and second conductive structures collectively define a first center point located in a center of a geometric rectangle covering surface areas of the first and second conductive structures, wherein the base pad defines a second center point located in a center of a geometric rectangle covering a surface area of the base pad, 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 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 base pad and a second coupling coefficient measuring coupling between the second conductive structure and the base pad.

33. The system of claim 32, wherein the base pad comprises a loop defining a fourth area, wherein a length of the 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.

34. The system of claim 33, wherein the base pad 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 rectangular region is 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.

35. The system of claim 23, wherein the first conductive structure has a first polarized magnetic moment in a first direction, wherein the second conductive structure has a second polarized magnetic moment in a second direction perpendicular to the first direction.

36. The system of claim 23, wherein the first conductive structure and the second conductive structure are positioned to maintain an absence of mutual coupling between the first conductive structure and the second conductive structure.

37. The system of claim 36, wherein a net sum of a magnetic field generated by the first conductive structure and that intersects the second conductive structure is zero.

38. The system of claim 23, 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 eclose the first area and second area, respectively.

39. The system of claim 23, wherein the first and second conductive structures are capacitively loaded and configured to resonate at a resonant frequency 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.

40. The system of claim 23, 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.

41. The system of claim 23, further comprising a controller configured to receive measurements indicative of an amount of coupling between each of the first and second conductive structures and the base pad, the controller configured to selectively de-activate the first or second conductive structure based on the amount of coupling.

42. The system of claim 23, wherein the apparatus further comprises a controller configured detect an amount of coupling between each of the first and second conductive structures and the base pad 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.

43. The system of claim 42, 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.