System and method for reducing leakage flux in wireless charging systems

• US 9,923,406 B2
• Filed: 09/04/2015
• Issued: 03/20/2018
• Est. Priority Date: 09/04/2015
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Percebon, Leandro, Werner, Michael, Kuerschner, Daniel, Chlebosz, Wojciech
• Primary Examiner(s): Rossoshek, Helen
• Application Number:
  US14/846,394
• Publication Number:
  US 20170070075A1
• Time in Patent Office: 928 Days
• 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: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• 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 90/14 Plug-in electric vehicles

Abstract

One innovation includes a system for reducing magnetic flux of a wireless charging field in a wireless power charging system. The system comprises a wireless power transmitter configured to generate the wireless charging field, the field comprising the magnetic flux and a collector comprising a ferromagnetic material and configured to reduce the magnetic flux. The collector is positioned between a first distance and a second distance at a third distance from the transmitter. The collector is configured to reduce the magnetic flux at a first level at the first distance, at a second level at the second distance, and at a third level at the third distance, the third level greater than each of the first and second levels.

Claims

1. An apparatus for reducing leakage magnetic flux of a wireless charging field in a wireless power charging system, the apparatus comprising:

a wireless power transmitter having a transmitter edge and configured to generate the wireless charging field; and

a collector having a collector edge and comprising a ferromagnetic material that reduces the leakage magnetic flux of the wireless charging field,

the collector edge positioned at a distance dist_x between the transmitter edge and the collector edge,

wherein the collector provides a reduction of the leakage magnetic flux greater than about 26% when positioned at the distance dist_x between the transmitter edge and the collector edge.

2. The apparatus of claim 1, wherein the collector is selected to have a first cross section that is less than or equal to a second cross section, wherein a first reduction of the magnetic flux is substantially the same at a third cross section that is greater than the second cross section as a second reduction of the magnetic flux at the second cross section.

3. The apparatus of claim 2, wherein the second cross section of the collector depends on at least one of a material of the collector, a location of the collector in relation to the transmitter, or a geometry of the collector.

4. The apparatus of claim 1, wherein the distance dist_x between the transmitter edge and the collector edge are dependent on at least one of a material of the collector, a location of the collector in relation to the transmitter, or a geometry of the collector.

5. The apparatus of claim 1, wherein the reduction of the leakage magnetic flux depends on at least one of a material of the collector, a location of the collector in relation to the transmitter, a type of the transmitter, or a geometry of the collector.

6. The apparatus of claim 1, wherein the transmitter is disposed below a wireless power receiver and wherein the collector is disposed above the transmitter or below the transmitter.

7. The apparatus of claim 1, wherein the collector and the transmitter are disposed on the ground and wherein the collector surrounds the transmitter.

8. The apparatus of claim 1, wherein the transmitter and the collector are disposed on the ground above which a vehicle comprising a wireless power receiver configured to receive a charge via the field is positioned.

9. The apparatus of claim 8, wherein the collector is positioned around the transmitter at the distance dist_x and reduces the magnetic flux beyond a perimeter of the vehicle.

10. The apparatus of claim 1, wherein the collector has a first perimeter greater than a second perimeter of the transmitter and wherein the collector at least partially surrounds the transmitter.

11. The apparatus of claim 1, wherein the collector is shaped in one of a square, a rectangle, a circle, a triangle, a polygon, or a semicircle, and wherein a perimeter of the collector extends away from a bottom of a vehicle comprising a wireless power receiver below the receiver.

12. The apparatus of claim 1, wherein the transmitter comprises a resonant circuit comprising a transmit coil configured to generate the field for coupling power to a receiver to charge an electric vehicle including the receiver.

13. The apparatus of claim 1, wherein the transmitter comprises another ferromagnetic material and wherein the collector is configured to reduce the magnetic flux at the distance dist_x while the other ferromagnetic material is configured to guide, alter, shape, or enhance the wireless charging field regardless of the collector at the distance dist_x.

31. The apparatus of claim 1, wherein a surface area of a cross section of the collector is equal to a value above which an increase of the surface area of the cross section does not result in a proportional increase in the reduction of the leakage magnetic flux.

14. A method of reducing leakage magnetic flux of a wireless charging field in a wireless power charging system, the method comprising:

generating, via a wireless power transmitter having a transmitter edge, the wireless charging field; and

reducing the magnetic flux, via a collector having a collector edge and comprising a ferromagnetic material that reduces the leakage magnetic flux of the wireless charging field, the collector positioned at a distance dist_x between the transmitter edge and the collector edge,

wherein the collector provides a reduction of the leakage magnetic flux greater than about 26% when positioned at the distance dist_x between the transmitter edge and the collector edge.

15. The method of claim 14, wherein the collector has a first cross section that is less than or equal to a second cross section and wherein a first reduction of the magnetic flux is substantially the same at a third cross section greater than the second cross section as a second reduction of the magnetic flux at the second cross section.

16. The method of claim 15, wherein the second cross section of the collector depends on at least one of a material of the collector, a location of the collector in relation to the transmitter, or a geometry of the collector.

17. The method of claim 14, wherein the distance dist_x between the transmitter edge and the collector edge are dependent on at least one of a material of the collector, a location of the collector in relation to the transmitter, or a geometry of the collector.

18. The method of claim 14, wherein the reduction of the leakage magnetic flux depends on at least one of a material of the collector, a location of the collector in relation to the transmitter, a type of the transmitter, or a geometry of the collector.

19. The method of claim 14, wherein the transmitter is disposed below a wireless power receiver and wherein the collector is disposed above the transmitter or below the transmitter.

20. The method of claim 14, wherein the collector and the transmitter are disposed on the ground and wherein the collector surrounds the transmitter.

21. The method of claim 14, wherein the transmitter and the collector are disposed on the ground above which a vehicle comprising a wireless power receiver configured to receive a charge via the field is positioned.

22. The method of claim 21, wherein the collector is positioned around the transmitter at the distance dist_x and reduces the magnetic flux beyond a perimeter of the vehicle.

23. The method of claim 14, wherein the collector has a first perimeter greater than a second perimeter of the transmitter and wherein the collector at least partially surrounds the transmitter.

24. The method of claim 14, wherein the collector is shaped in one of a square, a rectangle, a circle, a triangle, a polygon, or a semicircle, and wherein a perimeter of the collector extends away from a bottom of a vehicle comprising a wireless power receiver below the receiver.

25. The method of claim 14, further comprising coupling power to a receiver of an electric vehicle via the generated magnetic flux.

26. The method of claim 14, further comprising guiding, altering, shaping, or enhancing the wireless charging field via another ferromagnetic material integrated with the transmitter regardless of the collector at the distance dist_x.

27. An apparatus for reducing leakage magnetic flux of a wireless charging field in a wireless power charging system, the apparatus comprising:

means for generating the wireless charging field; and

means for reducing the magnetic flux configured to reduce the leakage magnetic flux of the wireless charging field,

the reducing means being positioned at a distance distx between the generating means and the reducing means,

wherein the reducing means provides a reduction of the leakage magnetic flux greater than about 26% when positioned at the distance distx between the generating means the reducing means.

28. The apparatus of claim 27, wherein the generating means comprises a wireless power transmitter and wherein the reducing means comprises a collector comprising a ferromagnetic material that reduces the leakage magnetic flux of the wireless charging field.

29. The apparatus of claim 27, wherein the reducing means has a first cross section that is less than or equal to a second cross section and wherein a first reduction of the magnetic flux is substantially the same at a third cross section that is greater than the second cross section as a second reduction of the magnetic flux at the second cross section.

30. The apparatus of claim 27, wherein the reducing means is positioned around the generating means at the distance dist_x and reduces the magnetic flux beyond a perimeter of a vehicle comprising a wireless power receiver for configured to receive a charge via the field.