MULTI-MODE, MULTI-STANDARD WIRELESS POWER TRANSMITTER COIL ASSEMBLY

• US 20160211702A1
• Filed: 03/31/2016
• Published: 07/21/2016
• Est. Priority Date: 08/03/2012
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Riehl, Patrick Stanley, Muratov, Vladimir A.
• Granted Patent: US 10,658,869 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01F 27/38 Auxiliary core members; Auxiliary coils or windings
• 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 50/10 using inductive coupling
• 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 50/80 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 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

Apparatus and methods for dual-mode wireless power transfer are described. Two power transmit coils may be configured to provide magnetic resonant and magnetic inductance wireless power transfer from a same charging area of a wireless power transmitter. The coils and magnetic backing may be arranged to provide similar power transfer performance for the two power transfer methodologies.

Claims

1. A multi-mode wireless power transmitter comprising:

a first transmit coil spanning a first area and configured for operation at a first frequency;

a second transmit coil spanning a second area that is located within the first area and that is smaller than the first area, wherein the second transmit coil is configured for operation at a second frequency that is at least a factor of 20 lower than the first frequency; and

a platform having a designated charging area within which to place a wireless receiving device, wherein the platform is located vertically from the first transmit coil and second transmit coil.

2. The multi-mode wireless power transmitter of claim 1, wherein the first transmit coil and second transmit coil are configured such that a first mutual voltage transformation ratio for a first device receiving power at the first frequency and placed centrally within the designated charging area is between approximately 50% and approximately 200% of a second mutual voltage transformation ratio for a second device receiving power at the second frequency and placed centrally within the designated charging area.

3. The multi-mode wireless power transmitter of claim 2, wherein the first transmit coil and second transmit coil are configured such that a third mutual voltage transformation ratio for the first device misaligned within the designated charging area by up to one-half a minor diameter of the first transmit coil is between approximately 50% and approximately 150% of the first mutual voltage transformation ratio.

4. The multi-mode wireless power transmitter of claim 2, wherein the first transmit coil and second transmit coil are configured such that a third mutual voltage transformation ratio for the first device misaligned within the designated charging area by one-half a minor diameter of the first transmit coil is between approximately 75% and approximately 125% of the first mutual voltage transformation ratio.

5. The multi-mode wireless power transmitter of claim 3, wherein the first transmit coil and second transmit coil are configured such that a fourth mutual voltage transformation ratio for the second device misaligned within the designated charging area by one-half the minor diameter of the first transmit coil is between approximately 50% and approximately 150% of the second mutual voltage transformation ratio.

6. The multi-mode wireless power transmitter of claim 3, wherein the first transmit coil and second transmit coil are configured such that a fourth mutual voltage transformation ratio for the second device misaligned within the designated charging area by one-half the minor diameter of the first transmit coil is between approximately 75% and approximately 125% of the second mutual voltage transformation ratio.

7. The multi-mode wireless power transmitter of claim 1, wherein windings of the first transmit coil do not cross windings of the second transmit coil.

8. The multi-mode wireless power transmitter of claim 1, wherein the first frequency is approximately 6.78 MHz and the second frequency is between approximately 80 kHz and approximately 300 kHz.

9. The multi-mode wireless power transmitter of claim 1, further comprising at least one power converter arranged to drive the first transmit coil and the second transmit coil, wherein a common electrical connection is made to the first transmit coil, the second transmit coil, and the at least one power converter.

10. The multi-mode wireless power transmitter of claim 1, further comprising a first magnetic backing located on a first side of the first transmit coil opposite the platform.

11. The multi-mode wireless power transmitter of claim 10, wherein the first magnetic backing covers at least a portion of the first area but does not extend more than 10% beyond a lateral dimension of the first area.

12. The multi-mode wireless power transmitter of claim 10, wherein the first magnetic backing has a relative magnetic permeability between approximately 60 and approximately 200.

13. The multi-mode wireless power transmitter of claim 10, further comprising a second magnetic backing located on a first side of the second transmit coil opposite the platform.

14. The multi-mode wireless power transmitter of claim 13, wherein the second magnetic backing covers at least a portion of the second area but does not extend more than 10% beyond a lateral dimension of the second area.

15. The multi-mode wireless power transmitter of claim 13, wherein the first magnetic backing has a relative magnetic permeability between approximately 60 and approximately 200 and the second magnetic backing has a relative magnetic permeability between approximately 400 and approximately 500,000.

16. The multi-mode wireless power transmitter of claim 13, wherein the second transmit coil and second magnetic backing are located a vertical distance toward the platform from the first magnetic backing that is greater than zero but less than approximately 25% of a minor diameter of the first magnetic backing.

17. The multi-mode wireless power transmitter of claim 13, wherein the second transmit coil and second magnetic backing are located a vertical distance toward the platform from the first magnetic backing that is greater than zero but less than approximately 25% of a minor diameter of the first transmit coil.

18. The multi-mode wireless power transmitter of claim 1, wherein the second transmit coil is located between approximately 2 mm and approximately 4 mm from the first transmit coil, and the platform is located less than approximately 12 mm from the first transmit coil.

19. The multi-mode wireless power transmitter of claim 1, wherein the second transmit coil is located between approximately 9 mm and approximately 12 mm from the first transmit coil, and the platform is located less than approximately 12 mm from the first transmit coil.

20. The multi-mode wireless power transmitter of claim 1, further comprising a third transmit coil spanning a third area that is approximately equal to the second area, wherein the third transmit coil is configured for operation at the second frequency and is located within the first area.

21. The multi-mode wireless power transmitter of claim 20, wherein the third transmit coil overlaps a portion of the second transmit coil.

22. A method of operating a dual-mode wireless transmitter, the method comprising:

applying a first drive signal at a first frequency to a first transmit coil that spans a first area and that is vertically spaced from a platform having a designated charging area; and

applying a second drive signal at a second frequency that is at least a factor of 20 lower than the first frequency to a second transmit coil that spans a second area that is located within the first area and is smaller than the first area.

23. The method of claim 22, further comprising:

transferring power from the first transmit coil to a first wireless receiving device located centrally within the designated charging area, so that the first wireless receiving device exhibits a first mutual voltage transformation ratio; and

transferring power from the second transmit coil to a second wireless receiving device located centrally within the designated charging area, so that the second wireless receiving device exhibits a second mutual voltage transformation ratio, wherein the first mutual voltage transformation ratio is between approximately 50% and approximately 200% of the second mutual voltage transformation ratio.

24. The method of claim 23, further comprising transferring power from the first transmit coil to the first wireless receiving device misaligned within the designated charging area by one-half a minor diameter of the first transmit coil, so that the first wireless receiving device exhibits a third mutual voltage transformation ratio that is between approximately 50% and approximately 150% of the first mutual voltage transformation ratio.

25. The method of claim 24, further comprising transferring power from the second transmit coil to the second wireless receiving device misaligned within the designated charging area by one-half a minor diameter of the first transmit coil, so that the fourth wireless receiving device exhibits a mutual voltage transformation ratio that is between approximately 50% and approximately 150% of the first mutual voltage transformation ratio.

26. The method of claim 22, wherein the first frequency is approximately 6.78 MHz and the second frequency is between approximately 80 kHz and approximately 300 kHz.

27. The method of claim 22, further comprising condensing magnetic field from the first coil with a first magnetic backing located on a first side of the first transmit coil opposite the platform, wherein the first magnetic backing has a relative magnetic permeability between approximately 60 and approximately 200.

28. The method of claim 27, further comprising condensing magnetic field from the second coil with a second magnetic backing located on a first side of the second transmit coil opposite the platform, wherein the second magnetic backing has a relative magnetic permeability between approximately 400 and approximately 500,000.

29. The method of claim 22, wherein the second transmit coil and second magnetic backing are located a vertical distance toward the platform from the first magnetic backing that is greater than zero but less than approximately 25% of a minor diameter of the first magnetic backing.

30. The method of claim 22, wherein the second transmit coil and second magnetic backing are located a vertical distance toward the platform from the first magnetic backing that is greater than zero but less than approximately 25% of a minor diameter of the first transmit coil.

31. The method of claim 22, further comprising applying the second drive signal at the second frequency to a third transmit coil that spans a third area that is located within the first area and is smaller than the first area.

32. The method of claim 29, where the second drive signal is applied to the second and the third transmit coils via at least one common wire connected to the first and the second transmit coils.

33. The method of claim 29, where the second drive signal is applied to the second and the third transmit coils via at least one common wire connected to the second and the third transmit coils.