CONTROLLING CURRENT FLOW PATH IN WIRELESS ELECTRIC VEHICLE CHARGING SYSTEMS FOR MITIGATING RF RADIATED EMISSIONS

• US 20150197155A1
• Filed: 09/17/2014
• Published: 07/16/2015
• Est. Priority Date: 01/10/2014
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Lu, Lin, Guckian, Paul, Nadakuduti, Jagadish
• Granted Patent: US 10,391,871 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 2270/147 electro magnetic [EMI]
• 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 53/126 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 50/90 involving detection or optimisation of position, e.g. alignment
• 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 mitigating electromagnetic radiation emissions. In one aspect, a power transfer device of a wireless electric vehicle charging (WEVC) system is provided. The power transfer device includes a ferrite material and at least one electrically conductive coil. The ferrite material and the at least one coil are configured to wirelessly transfer energy either from or to a second power transfer device of the WEVC system. The power transfer device further includes at least one shield comprising a plurality of electrically conducting regions and one or more electrically insulating regions. The plurality of electrically conducting regions and one or more electrically insulating regions are configured to mitigate electromagnetic radiation emissions from the WEVC system that do not contribute to the wireless power transfer between the at least one electrically conductive coil and the second power transfer device.

Claims

1. A power transfer device of a wireless electric vehicle charging (WEVC) system, the power transfer device comprising:

a ferrite material and at least one electrically conductive coil, the ferrite material and the at least one coil configured to wirelessly transfer energy either from or to a second power transfer device of the WEVC system; and

at least one shield comprising a plurality of electrically conducting regions and one or more electrically insulating regions, the plurality of electrically conducting regions and the one or more electrically insulating regions configured to control induced currents in the at least one shield during operation of the WEVC system, the induced currents mitigating electromagnetic radiation emissions from the WEVC system that do not contribute to wireless power transfer between the at least one electrically conductive coil and the second power transfer device.

2. The power transfer device of claim 1, wherein the plurality of electrically conducting regions comprises a metal material.

3. The power transfer device of claim 1, wherein the one or more electrically insulating regions comprises one or more gaps between two or more of the electrically conducting regions.

4. The power transfer device of claim 1, wherein the one or more electrically insulating regions comprises a solid electrical insulating material.

5. The power transfer device of claim 1, wherein the power transfer device is configured to be mounted on a vehicle and configured to receive power wirelessly from the second power transfer device, the second power transfer device comprising a base pad.

6. The power transfer device of claim 1, wherein the power transfer device comprises a base pad configured to transmit power wirelessly to the second power transfer device, the second power transfer device mounted on a vehicle.

7. The power transfer device of claim 1, wherein the one or more electrically insulating regions are configured to control flow of the induced currents between two or more of the electrically conducting regions.

8. The power transfer device of claim 7, wherein the one or more electrically insulating regions are configured to control flow of the induced currents such that a vector summation of electromagnetic fields arising from a combination of the induced currents and electrical currents flowing through the at least one coil mitigates the electromagnetic radiation emissions from the WEVC system that do not contribute to wireless power transfer between the at least one electrically conductive coil and the second power transfer device.

9. The power transfer device of claim 7, wherein the one or more electrically insulating regions are configured to control flow of the induced currents by constraining the flow of the induced currents to be only in one or more predetermined directions.

10. The power transfer device of claim 7, wherein the one or more electrically insulating regions are configured to control flow of the induced currents such that a first amount of induced currents flowing in a first electrically conducting region of the at least one shield is increased as compared to a second amount of induced currents flowing in a second electrically conducting region of the at least one shield.

11. The power transfer device of claim 7, wherein the one or more electrically insulating regions are configured to allow some flow of the induced currents between the two electrically conducting regions on either side of the electrically insulating region.

12. The power transfer device of claim 7, wherein the one or more electrically insulating regions are configured to prevent flow of the induced currents between the two electrically conducting regions on either side of the electrically insulating region.

13. A power transfer device of a wireless electric vehicle charging (WEVC) system, the power transfer device comprising:

means for wirelessly transferring energy either from or to a second power transfer device of the WEVC system; and

means for mitigating electromagnetic radiation emissions from the WEVC system that do not contribute to said wirelessly transferring energy, the mitigating means comprising a plurality of electrically conducting regions and one or more electrically insulating regions.

14. The power transfer device of claim 13, wherein the wirelessly transferring energy means comprises a ferrite material and at least one electrically conductive coil.

15. The power transfer device of claim 14, wherein the mitigating means comprises at least one shield comprising the plurality of electrically conducting regions and the one or more electrically insulating regions, the plurality of electrically conducting regions and the one or more electrically insulating regions configured to control induced currents in the at least one shield during operation of the WEVC system, the induced currents mitigating the electromagnetic radiation emissions from the WEVC system that do not contribute to said wirelessly transferring energy.

16. A method of mitigating electromagnetic radiation emissions from a wireless electric vehicle charging (WEVC) system, the method comprising:

providing a power transfer device comprising a ferrite material and at least one electrically conductive coil, the ferrite material and the at least one coil configured to wirelessly transfer energy either from or to a second power transfer device of the WEVC system, the power transfer device further comprising at least one shield; and

orienting the power transfer device and the second power transfer device relative to one another such that induced currents in the at least one shield mitigate electromagnetic radiation emissions from the WEVC system that do not contribute to wireless power transfer between the at least one electrically conductive coil and the second power transfer device.

17. The method of claim 16, wherein orienting the power transfer device and the second power transfer device relative to one another comprises mounting the power transfer device to a vehicle such that, upon positioning the vehicle for wireless power transfer using the WEVC system, a vector summation of electromagnetic fields arising from a combination of the induced currents and electrical currents flowing through the at least one coil mitigates the electromagnetic radiation emissions from the WEVC system that do not contribute to wireless power transfer between the at least one electrically conductive coil and the second power transfer device.

18. The method of claim 16, wherein the at least one shield comprises a plurality of electrically conducting regions and one or more electrically insulating regions, the plurality of electrically conducting regions and the one or more electrically insulating regions configured to control the induced currents in the at least one shield during operation of the WEVC system.

19. The method of claim 18, wherein the one or more electrically insulating regions constrain the flow of the induced currents to be only in one or more predetermined directions.

20. The method of claim 18, wherein the one or more electrically insulating regions increase a first amount of induced currents flowing in a first electrically conducting region of the at least one shield as compared to a second amount of induced currents flowing in a second electrically conducting region of the at least one shield.

21. The method of claim 18, wherein the one or more electrically insulating regions allow some flow of the induced currents between the two electrically conducting regions on either side of the electrically insulating region.

22. The method of claim 18, wherein the one or more electrically insulating regions prevent flow of the induced currents between the two electrically conducting regions on either side of the electrically insulating region.

23. A method of mitigating electromagnetic radiation emissions from a wireless electric vehicle charging (WEVC) system, the method comprising:

wirelessly transferring energy via a first power transfer device comprising a ferrite material, at least one electrically conductive coil, and at least one shield, the energy wirelessly transferring either from or to a second power transfer device of the WEVC system; and

controlling induced currents in the at least one shield during operation of the WEVC system to mitigate electromagnetic radiation emissions from the WEVC system that do not contribute to wireless power transfer between the first power transfer device and the second power transfer device.

24. The method of claim 23, wherein the at least one shield comprises a plurality of electrically conducting regions and one or more electrically insulating regions.

25. The method of claim 23, wherein controlling induced currents comprises constraining the flow of the induced currents to be only in one or more predetermined directions.