CONTROLLING FIELD DISTRIBUTION OF A WIRELESS POWER TRANSMITTER

• US 20170005481A1
• Filed: 09/25/2015
• Published: 01/05/2017
• Est. Priority Date: 07/02/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Von Novak, William Henry III, Carobolante, Francesco
• Granted Patent: US 10,084,321 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Abstract

Exemplary embodiments are directed to an apparatus for controlling magnetic field distribution including a wireless transmit antenna configured to generate a magnetic field for wirelessly transferring power to a charge-receiving device with the wireless transmit antenna, a parasitic antenna located near the wireless transmit antenna, and a switch configured to selectively enable the parasitic antenna to modify the magnetic field in response to an antenna parameter that indicates the presence of the charge-receiving device relative to the parasitic antenna.

Claims

1. An apparatus for controlling magnetic field distribution, comprising:

a wireless transmit antenna configured to generate a magnetic field for wirelessly transferring power to a charge-receiving device with the wireless transmit antenna;

a parasitic antenna located in the region of the magnetic field generated by the wireless transmit antenna; and

a switch configured to selectively enable the parasitic antenna to modify the magnetic field in response to an antenna parameter that indicates the presence of the charge-receiving device relative to the parasitic antenna.

2. The apparatus of claim 1, wherein the antenna parameter comprises at least one of a voltage parameter at the wireless transmit antenna, a voltage parameter at a wireless receive antenna at a receiver, a reactance parameter at the wireless transmit antenna, and a reactance parameter at the wireless receive antenna at the receiver.

3. The apparatus of claim 1, wherein the parasitic antenna is configured to amplify the magnetic field in response to the antenna parameter.

4. The apparatus of claim 1, wherein the parasitic antenna is configured to operate in a resonant tuned state in response to the antenna parameter.

5. The apparatus of claim 1, wherein the parasitic antenna is configured to operate in a resistive state in response to the antenna parameter.

6. The apparatus of claim 1, wherein the parasitic antenna is configured to change an impedance of the wireless transmit antenna in response to the antenna parameter.

7. The apparatus of claim 1, wherein the parasitic antenna is configured to operate in at least one of a capacitive tuned state or a inductive tune state in response to the antenna parameter.

8. The apparatus of claim 1, further comprising a plurality of parasitic antennas including the parasitic antenna, wherein the apparatus further comprises a housing defining a charging surface for placement of a plurality of charge-receiving devices including the charge-receiving device, the housing configured to house the wireless transmit antenna and the plurality of parasitic antennas.

9. The apparatus of claim 1, further comprising:

a plurality of parasitic antennas in a set of parasitic antennas comprising the parasitic antenna, each of the plurality of parasitic antennas configured to momentarily and sequentially be activated to determine a location of the charge-receiving device on a charging surface; and

at least one selected parasitic antenna of the plurality of parasitic antennas configured to be enabled to modify the magnetic field in a location on the charging surface having no charge-receiving device.

10. The apparatus of claim 1, further comprising:

a first circuit wirelessly coupled to the magnetic field, the first circuit configured to generate a power signal in response to power coupled via the magnetic field, the power signal configured to power a second circuit that controls the switch.

11. The apparatus of claim 10, wherein the second circuit is electrically coupled to the first circuit, the second circuit configured to generate a control signal to control a state of the switch, the control signal responsive to the power signal and a modulation signal developed by the wireless transmit antenna.

12. A method for controlling magnetic field distribution, comprising:

generating a magnetic field for wirelessly transferring power to a charge-receiving device using a wireless transmit antenna; and

selectively enabling a switch to modify the magnetic field using a parasitic antenna located in the region of the magnetic field generated by the wireless transmit antenna in response to an antenna parameter that indicates the presence of the charge-receiving device relative to the parasitic antenna.

13. The method of claim 12, further comprising selectively enabling the switch responsive to any of a voltage parameter and a reactance parameter at the wireless transmit antenna.

14. The method of claim 12, further comprising amplifying the magnetic field in response to the antenna parameter.

15. The method of claim 12, further comprising operating the parasitic antenna in a resonant tuned state in response to the antenna parameter.

16. The method of claim 12, further comprising changing an impedance of the wireless transmit antenna in response to the antenna parameter.

17. The method of claim 16, further comprising operating the parasitic antenna in any of a capacitive tuned state and an inductive tuned state in response to the antenna parameter.

18. The method of claim 12, further comprising operating the parasitic antenna in a resistive state in response to the antenna parameter.

19. The method of claim 12, further comprising generating a power signal in response to the magnetic field the power signal configured to power the switch.

20. The method of claim 19, further comprising generating a control signal to control a state of the switch, the control signal responsive to the power signal and a modulation signal developed by the wireless transmit antenna.

21. The method of claim 12, further comprising:

momentarily and sequentially activating each of a plurality of parasitic antennas in a set of parasitic antennas including the parasitic antenna;

determining a location of the charge-receiving device on a charging surface; and

enabling selected parasitic antennas of the plurality of parasitic antennas in locations on the charging surface having no charge-receiving device.

22. The method of claim 21, wherein determining a location of the charge-receiving device further comprises detecting a voltage change at the transmit antenna.

23. The method of claim 21, wherein determining a location of the charge-receiving device further comprises detecting a reactance change at the transmit antenna.

24. A device for controlling magnetic field distribution, comprising:

means for generating a first magnetic field for wirelessly transferring power to a charge-receiving device;

means for generating a second magnetic field that alters the first magnetic field; and

means for selectively enabling the means for generating the second magnetic field in response to an antenna parameter that indicates the presence of the charge-receiving device relative to the means for generating the second magnetic field.

25. An apparatus for controlling magnetic field distribution, comprising:

a wireless transmit antenna configured to generate a magnetic field for wirelessly transferring power to a charge-receiving device with the wireless transmit antenna;

a parasitic antenna located in the region of the magnetic field generated by the wireless transmit antenna; and

a switch configured to selectively enable the parasitic antenna to modify the magnetic field in response to an antenna parameter that indicates the presence of the charge-receiving device relative to the parasitic antenna, the switch powered by the magnetic field.

26. The apparatus of claim 25, further comprising a capacitive coupling configured to power the switch, wherein the switch is responsive to the capacitive coupling.

27. The apparatus of claim 25, further comprising an inductive coupling configured to power the switch, wherein the switch is responsive to the inductive coupling.

28. The apparatus of claim 25, further comprising a coupling circuit configured to power the switch, wherein the switch is responsive to the coupling circuit.

29. The apparatus of claim 25, wherein the magnetic field is modulated with a signal and the switch is responsive to the modulated signal.

30. The apparatus of claim 29, wherein the modulated signal is at least one of an amplitude modulated signal and a frequency modulated signal.