System and method for inductance compensation in wireless power transfer

• US 9,376,026 B2
• Filed: 07/08/2013
• Issued: 06/28/2016
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Keeling, Nicholas A., Budhia, Mickel, Widmer, Hanspeter, Fischer, Marcel, Sieber, Lukas
• Primary Examiner(s): Whitmore, Stacy
• Application Number:
  US13/937,154
• Publication Number:
  US 20140111151A1
• Time in Patent Office: 1,086 Days
• Field of Search: 320107-109, 361/93.6, 361/93.9, 307/104
• US Class Current: 1/1
• 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: G05F 1/14 using tap transformers or tap changing inductors as final control devices
• CPC Class Codes: H01F 2027/348 Preventing eddy currents
• 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 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• 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

Abstract

This disclosure provides systems, methods and apparatus for wireless power transfer. In one aspect an apparatus for wirelessly transferring power from a charging power source to a device is provided. The apparatus includes a first strand wound in one or more turns and operationally coupled to the charging power source and a second strand wound together with the first strand in one or more turns and operationally coupled to the charging power source. The apparatus further includes an inductor circuit connected to the first strand and disconnected from the second strand. The inductor circuit is further configured to reduce a current difference between a first current flowing through the first strand and a second current flowing through the second strand.

Claims

1. An apparatus for wirelessly transferring power from a charging power source to a device, the apparatus comprising:

a first strand wound in one or more turns and operationally coupled to the charging power source;

a second strand wound together with the first strand in one or more turns and operationally coupled to the charging power source; and

an inductor circuit connected to the first strand and disconnected from the second strand, the inductor circuit configured to reduce a current difference between a first current flowing through the first strand and a second current flowing through the second strand.

2. The apparatus of claim 1, wherein the inductor circuit is configured to compensate for the current difference due to a difference in self-inductance of the first strand and the second strand.

3. The apparatus of claim 1, wherein at least one first segment of the first strand and at least one second segment of the second strand are placed in parallel with each other.

4. The apparatus of claim 1, wherein at least one first segment of the first strand and at least one second segment of the second strand are twisted, crossed over, or braided with each other.

5. The apparatus of claim 1, wherein the inductor circuit comprises a loop wire having a first end of the loop wire connected to a first end of the first strand and having a second end of the loop wire connected to a second end of the first strand.

6. The apparatus of claim 1, wherein the inductor circuit comprises an inductor having a first end of the inductor connected to a first end of the first strand and having a second end of the inductor connected to a second end of the first strand.

7. The apparatus of claim 1 further comprising a third strand wound in one or more turns and operationally coupled to the charging power source, wherein the inductor circuit is further configured to reduce at least another current difference between a third current flowing through the third strand and at least one of the first current and the second current.

8. The apparatus of claim 7, wherein the at least another current difference is at least in part caused by a mutual inductance imbalance between a first mutual inductance between the first strand and the third strand and a second mutual inductance between the second strand and the third strand.

9. The apparatus of claim 1 further comprising:

a first lead operationally coupled to the first strand, the first lead placed on a first plane and around a first axis line that is perpendicular to the first plane; and

a second lead operationally coupled to the second strand, the second lead placed on a second plane and around a second axis line that is perpendicular to the second plane.

10. The apparatus of claim 9, wherein the first plane is perpendicular to the second plane.

11. The apparatus of claim 9, wherein the first plane and the second plane are substantially the same.

12. The apparatus of claim 9, wherein the first plane is substantially parallel to the second plane.

13. The apparatus of claim 1 further comprising:

an inner heat shrink around which the first strand is wound; and

an outer heat shrink around which the second strand is wound.

14. The apparatus of claim 1, wherein the first strand and the second strand form a gap therebetween.

15. The apparatus of claim 1, wherein the first strand and the second strand are wound in respective positions that reduce the current difference.

16. An apparatus for wirelessly transferring power from a charging power source to a device, the apparatus comprising:

a first strand wound in one or more turns and operationally coupled to the charging power source;

a second strand wound together with the first strand in one or more turns and operationally coupled to the charging power source;

a first transformer connected to the first strand and disconnected from the second strand; and

a second transformer connected to the second strand and disconnected from the first strand, the first transformer and the second transformer configured to collectively reduce a current difference between a first current flowing through the first strand and a second current flowing through the second strand.

17. The apparatus of claim 16, wherein the first transformer and the second transformer are further configured to compensate for the current difference due to a difference in self-inductance of the first strand and the second strand.

18. The apparatus of claim 16, wherein at least one first segment of the first strand and at least one second segment of the second strand are placed in parallel with each other.

19. The apparatus of claim 16, wherein at least one first segment of the first strand and at least one second segment of the second strand are twisted, crossed over, or braided with each other.

20. The apparatus of claim 16 further comprising a third strand wound in one or more turns and operationally coupled to the charging power source, wherein at least one of the first transformer and the second transformer is further configured to reduce at least another current difference between a third current flowing through the third strand and at least one of the first current and the second current.

21. The apparatus of claim 20, wherein the at least another current difference is at least in part caused by a mutual inductance imbalance between a first mutual inductance between the first strand and the third strand and a second mutual inductance between the second strand and the third strand.

22. The apparatus of claim 16, wherein a first end of the first transformer is connected to a first end of the first strand, and wherein a second end of the first transformer is connected to a second end of the first strand.

23. The apparatus of claim 16, wherein the second transformer is connected in series with or parallel to the first transformer.

24. The apparatus of claim 16 further comprising a first power source connected to the first transformer, the first power source configured to be regulated to a voltage level that is sufficient to drive the first transformer and to reduce the current difference.

25. The apparatus of claim 24 further comprising a second power source connected to the second transformer, the first power source and the second power source configured to drive the first transformer and the second transformer and to reduce the current difference.

26. The apparatus of claim 25 further comprising:

a third strand wound in one or more turns and operationally coupled to the charging power source; and

a third transformer operationally coupled to the third strand, wherein the third transformer is configured to reduce at least another current difference between a third current flowing through the third strand and at least one of the first current and the second current.

27. The apparatus of claim 26, wherein the third transformer is connected in series with at least one of the first transformer and the second transformer.

28. The apparatus of claim 16, wherein at least one of the first transformer and the second transformer has a transformation ratio that is greater than 1 or less than 1.

29. A method of wirelessly power transfer from a charging power source to a device, the method comprising:

transmitting power via a first strand wound in one or more turns and operationally coupled to the charging power source;

transmitting power via a second strand wound together with the first strand in one or more turns and operationally coupled to the charging power source;

providing power via an inductor circuit to the first strand, the inductor circuit connected to the first strand and disconnected from the second strand; and

reducing a current difference between a first current flowing through the first strand and a second current flowing through the second strand.

30. The method of claim 29, wherein at least one first segment of the first strand and at least one second segment of the second strand are placed in parallel, twisted, crossed over, or braided with each other.

31. The method of claim 29, wherein providing the power via the inductor circuit to the first strand comprises providing the power via a loop wire to the first strand, the loop wire having a first end of the loop wire connected to a first end of the first strand and having a second end of the loop wire connected to a second end of the first strand.

32. The method of claim 29, wherein providing the power via the inductor circuit to the first strand comprises providing the power via an inductor to the first strand, the inductor having a first end of the inductor connected to a first end of the first strand and having a second end of the inductor connected to a second end of the first strand.

33. The method of claim 29, wherein transmitting the power via the first strand further comprises transmitting the power via a first lead operationally coupled to the first strand, the first lead placed on a first plane and around a first axis line that is perpendicular to the first plane, wherein transmitting the power via the second strand comprises transmitting the power via a second lead operationally coupled to the second strand, the second lead placed on a second plane and around a second axis line that is perpendicular to the second plane, wherein the first plane is different than, substantially perpendicular to or substantially parallel to the second plane.

34. The method of claim 29, wherein transmitting power via a first strand comprises wrapping an inner heat shrink around which the first strand is wound, wherein transmitting power via a second strand comprises wrapping an outer heat shrink around which the second strand is wound, wherein the first strand and the second strand form a gap therebetween, and wherein the first strand and the second strand are wound in respective positions that reduce the current difference.

35. A method of wirelessly power transfer from a charging power source to a device, the method comprising:

transmitting power via a first strand wound in one or more turns and operationally coupled to the charging power source;

transmitting power via a second strand wound together with the first strand in one or more turns and operationally coupled to the charging power source;

providing power via a first transformer connected to the first strand, the first transformer disconnected from the second strand;

providing power via a second transformer connected to the second strand, the second transformer disconnected from the first strand; and

reducing a current difference between a first current flowing through the first strand and a second current flowing through the second strand.

36. The method of claim 35, wherein at least one first segment of the first strand and at least one second segment of the second strand are placed in parallel, twisted, crossed over, or braided with each other.

37. The method of claim 35, wherein a first end of the first transformer is connected to a first end of the first strand, and wherein a second end of the first transformer is connected to a second end of the first strand.

38. The method of claim 35, wherein the second transformer is connected in series with or parallel to the first transformer.

39. The method of claim 35 further comprising:

regulating a first power source to a voltage level that is sufficient to drive the first transformer and to reduce the current difference; and

regulating a second power source to another voltage level that is sufficient to drive the second transformer and to collectively reduce the current difference.

40. The method of claim 35, wherein at least one of the first transformer and the second transformer has a transformation ratio that is greater than 1 or less than 1.

41. An apparatus for wirelessly transferring power from a charging power source to a device, the apparatus comprising:

first means for transmitting wireless power to the device;

second means for transmitting wireless power to the device; and

means for reducing a current difference between a first current flowing through the first means for transmitting and a second current flowing through the second means for transmitting, the means for reducing connected to the first means for transmitting and disconnected from the second means for transmitting.

42. The apparatus of claim 41, wherein the first means for transmitting comprises a first strand, wherein the second means for transmitting comprising a second strand, and wherein at least one first segment of the first strand and at least one second segment of the second strand are placed in parallel, twisted, crossed over, or braided with each other.

43. The apparatus of claim 41, wherein the first means for transmitting comprises a first strand, wherein the second means for transmitting comprising a second strand, and wherein the means for reducing comprises a loop wire having a first end of the loop wire connected to a first end of the first strand and having a second end of the loop wire connected to a second end of the first strand.

44. The apparatus of claim 41, wherein the first means for transmitting comprises a first strand, wherein the second means for transmitting comprising a second strand, and wherein the means for reducing comprises an inductor having a first end of the inductor connected to a first end of the first strand and having a second end of the inductor connected to a second end of the first strand.

45. The apparatus of claim 41, wherein the first means for transmitting comprises a first strand and a first lead, the first lead operationally coupled to the first strand and placed on a first plane and around a first axis line that is perpendicular to the first plane, and wherein the second means for transmitting comprising a second strand and a second lead, the second lead operationally coupled to the second strand and placed on a second plane and around a second axis line that is perpendicular to the second plane.

46. The apparatus of claim 41, wherein the first means for transmitting comprises a first strand and an inner heat shrink, the inner heat shrink around which the first strand is wound, and wherein the second means for transmitting comprising a second strand and an outer heat shrink, the outer heat shrink around which the second strand is wound.

47. An apparatus for wirelessly transferring power from a charging power source to a device, the apparatus comprising:

first means for transmitting wireless power to the device;

second means for transmitting wireless power to the device;

first means for reducing a current difference between a first current flowing through the first means for transmitting and a second current flowing through the second means for transmitting, the first means for reducing connected to the first means for transmitting and disconnected from the second means for transmitting; and

second means for reducing the current difference connected to the second means for transmitting and disconnected from the first means for transmitting.

48. The apparatus of claim 47, wherein the first means for transmitting comprises a first strand, wherein the second means for transmitting comprising a second strand, and wherein at least one first segment of the first strand and at least one second segment of the second strand are placed in parallel, twisted, crossed over, or braided with each other.

49. The apparatus of claim 47, wherein the first means for transmitting comprises a first strand, wherein the second means for transmitting comprising a second strand, wherein the first means for reducing comprises a first transformer having a first end of the first transformer connected to a first end of the first strand and having a second end of the first transformer is connected to a second end of the first strand, wherein the second means for reducing comprises a second transformer having a first end of the second transformer connected to a first end of the second strand and having a second end of the second transformer connected to a second end of the second strand, and wherein the second transformer is connected in series with or parallel to the first transformer.

50. The apparatus of claim 47, wherein the first means for transmitting comprises a first strand, wherein the second means for transmitting comprising a second strand, wherein the first means for reducing comprises a first transformer and a first power source, the first power source configured to generate a voltage level that is sufficient to drive the first transformer and to reduce the current difference, and wherein the second means for reducing comprises a second transformer and a second power source, the second power source configured to generate another voltage level that is sufficient to drive the second transformer and to collectively reduce the current difference.

51. The apparatus of claim 47, wherein the first means for reducing comprises a first transformer, wherein the second means for reducing comprises a second transformer, and wherein at least one of the first transformer and the second transformer has a transformation ratio that is greater than 1 or less than 1.