Ferrite antennas for wireless power transfer

• US 8,253,278 B2
• Filed: 06/05/2009
• Issued: 08/28/2012
• Est. Priority Date: 06/05/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sieber, Lukas, Widmer, Hanspeter, Schwaninger, Peter, Cook, Nigel P
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US12/479,581
• Publication Number:
  US 20110095617A1
• Time in Patent Office: 1,180 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core
• CPC Class Codes: H02J 50/12 of the resonant type

Abstract

Ferrite core antenna used for transmitting or receiving wireless power. The antenna can move relative to the core.

Claims

1. A wireless power system, comprising:

a circuit configured to transmit a modulated power signal having a first frequency or to receive power via a wireless field and rectify the received power;

a ferrite core positioned stationarily in a device;

a loop base;

a main inductive loop that has a first number of loop turns on the loop base, the main inductive loop being electrically coupled to the circuit; and

a coupling loop having a second number of loop turns on the loop base, the coupling loop having fewer loop turns than the main loop, the coupling loop and the main loop being physically coupled to one another, being positioned adjoining to each other, and being movable relative to the stationarily positioned ferrite core, such that both the main loop and the coupling loop move together on the loop base,

the device comprising a housing surrounding the main loop, and the coupling loop and the circuit.

2. A system as in claim 1, wherein the circuit receives power via a wireless field at a frequency that is resonant with said main inductive loop, and creates a power output, the circuit coupled to provide an output to the main inductive loop.

3. A system as in claim 1, wherein the circuit creates a power output, at a frequency that is resonant with said main inductive loop, the circuit receiving power from the main inductive loop and transmitting power via a wireless field.

4. A system as in claim 1, additionally comprising a connection that includes a plurality of flexible wires, that connect to the coupling loop, wherever it is moved on said loop base.

5. A system as in claim 1, wherein the stationary ferrite core is located within the diameter of the loop base having the main inductive loop and the coupling loop, and wherein the main inductive loop and the coupling loop are wound on the exterior surface of the loop base.

6. A system as in claim 1, wherein a number of windings on the coupling loop is used to set an input impedance of the system.

7. A system as in claim 1, further comprising a capacitance, coupled across said main inductive loop.

8. A system as in claim 7, wherein said capacitance has a value such that an LC value of said inductance and capacitance together is resonant with the first frequency.

10. A system as in claim 1, wherein the main inductive loop is not concentric with the coupling loop on the loop base.

9. A system as in claim eight, wherein said first frequency is 135 kHz.

11. A method of transmitting power via a wireless field, comprising:

receiving power from a power source via a coupling loop of a coil, the coil having a ferrite core positioned stationarily in a device;

transferring power to a main inductive loop of the coil mechanically adjoined to the coupling loop on a movable loop base, the main inductive loop being electrically isolated from the coupling loop, the main inductive loop and the coupling loop being movable on the loop base relative to the stationarily positioned ferrite core so as to position the main inductive loop and the coupling loop; and

transmitting power, via the wireless field, based on the configured position of the coupling loop and the main inductive loop against the stationarily positioned ferrite core, the device comprising a housing surrounding the main inductive loop, the coupling loop and the ferrite core.

12. A method as in claim 11, wherein the coupling loop is configured according to a desired input impedance of the coil.

13. A method as in claim 11, further comprising coupling a capacitor across the main loop, wherein said main loop and said capacitor collectively create an LC constant which is resonant with a first frequency of the wireless transmission of power.

14. A method as in claim 13, wherein said first frequency is 135 kHz.

15. A method as in claim 13, wherein the coupling loop and the main inductive loop are physically connected on the loop base, the method further comprising moving the connected coupling loop and main inductive loop to new locations to configure a characteristic of the coupling loop and main inductive loop.

16. A method as in claim 15, further comprising winding the coupling loop and the main inductive loop on a core, and wherein said moving is relative to said stationarily positioned core.

17. A method as in claim 11, wherein transmitting power comprises transmitting the power from a wireless power transmitter that produces a modulated power signal at a selected frequency.

18. A method of receiving power via a wireless field associated with a receiver, comprising:

receiving power via the wireless field with a main inductive loop of the coil connected to the receiver, the coil having a ferrite core positioned stationarily in a device;

transferring power to a coupling loop of the coil, the main inductive loop being mechanically adjoined to the coupling loop on a movable loop base, the main inductive loop and the coupling loop being electrically isolated from each other, the main inductive loop and the coupling loop being movable on the loop base relative to the stationarily positioned ferrite core so as to position the main inductive loop and the coupling loop; and

transferring power to a load based on the configured position of the coupling loop and the main inductive loop against the stationarily positioned ferrite core, the device comprising a housing surrounding the main loop, and the coupling loop.

19. A method as in claim 18, wherein the coupling loop is configured according to a desired input impedance of the coil.

20. A method of as in claim 18, further comprising coupling a capacitor across the main inductive loop, wherein said main inductive loop and said capacitor collectively create an LC constant which is resonant with a first frequency of said transmission of wireless power.

21. A method as in claim 20, wherein said first frequency is 135 kHz.

22. A method as in claim 20, wherein the coupling loop is connected to the main inductive loop, the method further comprising moving the connected coupling loop and main inductive loop to new locations to configure a characteristic of the coupling loop and main inductive loop.

23. A method as in claim 18, wherein receiving power comprises receiving the power at the receiver that rectifies the received power.

24. A system for transmitting power via a wireless field, comprising:

means for receiving power from a power source;

means for transferring power to a main inductive loop, the main inductive loop being mechanically adjoined to the means for receiving power on a movable loop base, the main inductive loop being electrically isolated from the means for receiving power, the main inductive loop and the means for receiving power being movable on the loop base relative to a ferrite core positioned stationarily in a device, the device comprising a housing surrounding the main inductive loop, the means for receiving power and the ferrite core; and

means for transmitting power, via the wireless field, based on a configured position of the means for receiving power and the main inductive loop against the stationarily positioned ferrite core.

25. A system as in claim 24, wherein the means for receiving power comprises a coupling loop, and wherein at least a selected coil parameter is configured separately in each of the coupling loop and main loop.

26. A system as in claim 24, wherein the means for transmitting power comprises a power transmitter that produces a modulated power signal at a selected frequency.

27. A system for receiving power via a wireless field associated with a receiver, comprising:

means for receiving power via a wireless field associated with the receiver, the means for receiving power being connected to the receiver;

first means for transferring power from the means for receiving power to a coupling loop, the coupling loop being mechanically adjoined to the first means for transferring power on a movable loop base, the coupling loop and the first means for transferring power being electrically isolated from each other and movable relative to a ferrite core positioned stationarily in a device, the device comprising a housing surrounding the coupling loop, the first means for transferring power and the ferrite core; and

second means for transferring power to a load based on the configured position of the coupling loop and the means for receiving power against the stationarily positioned ferrite core.

28. A system as in claim 27, wherein the first means for transferring power comprises a main inductive loop, and wherein at least a selected coil parameter is configured separately in each of the coupling loop and main inductive loop.