WIRELESS POWER TRANSMISSION

• US 20170288446A1
• Filed: 04/01/2016
• Published: 10/05/2017
• Est. Priority Date: 04/01/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Elkhouly, Essam, Yang, Songnan, Yao, Zhen
• Granted Patent: US 10,491,027 B2
• Time in Patent Office: Days
• 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 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

Techniques for modifying the electrical current distribution of transmit coil of a wireless power transmitting unit are described. An example power transmitting unit includes a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area. The power transmitting unit can also include a power source to transmit an alternating electrical current to an input terminal of the transmit coil and a plurality of reactive elements placed in series with the transmit coil. In some examples, the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal. The power transmitting unit can also include a controller to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit.

Claims

1. A power transmitting unit, comprising:

a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;

a power source to transmit an alternating electrical current (A/C) to an input terminal of the transmit coil;

a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal; and

a controller to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit or a change in the transmit coil of the power transmitting unit.

2. The power transmitting unit of claim 1, wherein the input terminal attaches to the center of the transmit coil.

3. The power transmitting unit of claim 1, wherein the input terminal of the transmit coil attaches to an outer edge of the transmit coil.

4. The power transmitting unit of claim 3, wherein the plurality of reactive elements of the transmit coil attach to the center of the transmit coil.

5. The power transmitting unit of claim 2, wherein the plurality of reactive elements attach to the transmit coil at an edge of the transmit coil.

6. The power transmitting unit of claim 1, wherein the plurality of reactive elements comprise a plurality of fixed capacitors, inductors, tunable inductors, or tunable capacitors.

7. The power transmitting unit of claim 1, wherein the plurality of reactive elements connect to the transmit coil at a plurality of symmetric locations.

8. The power transmitting unit of claim 1, wherein adjusting the current distribution of the transmit coil causes the transmit coil to have a reactance value below a threshold proximate the input terminal.

9. The power transmitting unit of claim 1, wherein the characteristic of the power receiving unit comprises a metal backing.

10. The power transmitting unit of claim 1, wherein the characteristic of the power receiving unit comprises a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit.

11. A method of manufacturing a power transmitting unit, comprising:

forming a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;

conductively coupling a power source to transmit an alternating electrical current to an input terminal of the transmit coil;

conductively coupling a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal; and

conductively coupling a controller to the transmit coil to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit or a change in the transmit coil of the power transmitting unit.

12. The method of claim 11, wherein the input terminal attaches to the center of the transmit coil.

13. The method of claim 11, wherein the input terminal of the transmit coil attaches to an outer edge of the transmit coil.

14. The method of claim 13, wherein the plurality of reactive elements of the transmit coil attach to the center of the transmit coil.

15. The method of claim 12, wherein the plurality of reactive elements of the transmit coil attach to an edge of the transmit coil.

16. The method of claim 11, wherein the plurality of reactive elements comprise fixed capacitors, inductors, tunable inductors, or tunable capacitors.

17. The method of claim 11, wherein the plurality of reactive elements connect to the transmit coil at a plurality of symmetric locations.

18. The method of claim 11, wherein the adjusting the current distribution of the transmit coil causes the transmit coil to have a reactance value below a threshold proximate the input terminal.

19. The method of claim 11, wherein the characteristic of the power receiving unit comprises a metal backing.

20. The method of claim 11, wherein the characteristic of the power receiving unit comprises a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit.

21. A wireless charger, comprising:

a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;

a power source to transmit an alternating electrical current to an input terminal of the transmit coil;

a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal; and

a controller to modify a reactance value of the plurality of reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit with a metal backing, the characteristic comprising a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit.

22. The wireless charger of claim 21, wherein the input terminal attaches to the center of the transmit coil.

23. The wireless charger of claim 21, wherein the input terminal of the transmit coil attaches to an outer edge of the transmit coil.

24. The wireless charger of claim 23, wherein the plurality of reactive elements attach to the center of the transmit coil.

25. The wireless charger of claim 22, wherein the plurality of reactive elements attach to an edge of the transmit coil.