WIRELESS CHARGING COIL PLACEMENT FOR REDUCED FIELD EXPOSURE

• US 20170179731A1
• Filed: 12/22/2015
• Published: 06/22/2017
• Est. Priority Date: 12/22/2015
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Kwasnick, Robert F., Yang, Songnan, Sindia, Suraj, Yao, Zhen
• Granted Patent: US 10,516,304 B2
• Time in Patent Office: Days
• CPC Class Codes: H02J 50/10 using inductive coupling
• 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

Abstract

An apparatus is described herein. The apparatus includes a power transmit unit coil and an active shielding coil. The power transmit unit coil includes a set of main windings, positioned at a first location on a structure, to carry a first current in a first direction, wherein the first current is to cause an electromagnetic field to emanate from the power transmit unit coil. The active shielding coil is positioned at a second location on the structure and is to carry a second current in a direction substantially opposite the first direction wherein the second current is to cause a reduction of the size of the electromagnetic field.

Claims

1. An apparatus, comprising:

a power transmit unit coil, including a set of main windings, positioned at a first location on a structure, to carry a first current in a first direction, wherein the first current is to cause an electromagnetic field to emanate from the power transmit unit coil; and

an active shielding coil, positioned at a second location on the structure, to carry a second current in a direction substantially opposite the first direction wherein the second current is to cause a reduction of the size of the electromagnetic field.

2. The apparatus of claim 1, wherein the power transmit unit coil and the active shielding coil are placed in circular patterns and positioned in substantially the same plane with substantially the same center.

3. The apparatus of claim 2, wherein an average radius of the active shielding coil is greater than an average radius of the power transmit unit coil.

4. The apparatus of claim 1, wherein the active shielding coil is to reduce a magnetic field leakage through cancellation of a magnetic field from the set of main windings.

5. The apparatus of claim 1, wherein a feedback mechanism is to control, at least partially, an active charging current that is to result from the electromagnetic field.

8. The apparatus of claim 1, wherein the second current is to cancel a leaked magnetic field at a pre-defined distance.

9. The apparatus of claim 1, wherein the second location is selected to mitigate interference between the set of main windings and a second power transmit unit.

6. The apparatus of claim 6, wherein the active charging current is modified via adjustments to the first current and the second current.

7. The apparatus of claim 7, wherein the active charging current is modified in response to a power level of a receiving device, a magnetic field leakage as the receiving device is powered, another source of magnetic field interference, or any combination thereof.

10. A system, comprising:

a power transmit unit comprising a set of main windings, positioned at a first location on a structure, to carry a first current in a first direction;

an active shielding coil, positioned ata second location on the structure, to carry a second current in a direction substantially opposite the first direction wherein the second current is to cause a reduction of the size of the electromagnetic field; and

electronic circuitry that is to drive current into the power transmit unit and the active shielding coil to create a resonant inductive coupling with a power receive unit.

11. The system of claim 11, wherein a magnetic field leakage is reduced to a level lower than a predefined limit.

12. The system of claim 11, wherein the active shielding turn is to reduce magnetic field leakage through cancellation of magnetic fields.

13. The system of claim 11, wherein the set of main windings is placed in a circular pattern, and the active shielding coil is placed outside at least a portion of an outermost winding of the set of main windings in substantially the same plane with substantially the same center.

14. The system of claim 14, wherein the power transmit unit is positioned in an area substantially encompassed by the active shielding coil.

15. A method for coil placement, comprising:

positioning a power transmit unit is a structure to minimize exposure to magnetic fields;

calculating an error based on a potential magnetic field of the power transmit unit and a maximum magnetic field, and

re-positioning the power transmit unit in response to the error being greater than a pre-defined threshold.

16. The method of claim 16, wherein the power transmit unit is positioned iteratively until the error is less than the pre-defined threshold.

17. The method of claim 16, wherein the power transmit unit is encompassed by an active shielding coil that is to reduce magnetic field leakage through cancellation of magnetic fields.

19. The method of claim 16, wherein an initial position of the power transmit unit is determined based on, at least partially, an exponential decay model of the potential magnetic field.

18. The method of claim 18, wherein the active shielding coil is to reduce magnetic field leakage in a region between multiple power transmit units through cancellation of magnetic fields.

20. A tangible, non-transitory, computer-readable medium comprising instructions that, when executed by a processor, direct the processor to:

position a power transmit unit is a structure to minimize exposure to magnetic fields;

calculate an error based on a potential magnetic field of the power transmit unit and a maximum magnetic field; and

re-position the power transmit unit in response to the error being greater than a pre-defined threshold.

21. The computer readable medium of claim 21, wherein the power transmit unit is positioned iteratively until the error is less than the pre-defined threshold.

22. The computer readable medium of claim 21, wherein the power transmit unit is encompassed by an active shielding coil that is to reduce magnetic field leakage through cancellation of magnetic fields.

24. The computer readable medium of claim 21, wherein an initial position of the power transmit unit is determined based on, at least partially, an exponential decay model of the potential magnetic field.

23. The computer readable medium of claim 23, wherein the active shielding coil is to reduce magnetic field leakage in a region between multiple power transmit units through cancellation of magnetic fields.