Wireless power transmitter with a plurality of magnetic oscillators

• US 9,601,267 B2
• Filed: 11/11/2013
• Issued: 03/21/2017
• Est. Priority Date: 07/03/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Widmer, Hanspeter, Cook, Nigel P., Bittner, Markus
• Primary Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US14/077,102
• Publication Number:
  US 20150008751A1
• Time in Patent Office: 1,226 Days
• US Class Current: 1/1
• 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 50/12 of the resonant type
• CPC Class Codes: H02J 50/50 using additional energy repeaters between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/32 for charging batteries from a charging set comprising a non-electric prime mover rotating at constant speed
• CPC Class Codes: H03B 15/006 using spin transfer effects or giant magnetoresistance
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A power transmitter is configured to wirelessly transfer power to at least one power receiver. The power transmitter includes at least one excitation circuit configured to generate a time-varying first magnetic field in response to a time-varying electric current flowing through the at least one excitation circuit. The time-varying first magnetic field has an excitation frequency. The power transmitter further includes a plurality of magnetic oscillators. Each magnetic oscillator of the plurality of magnetic oscillators has a mechanical resonant frequency substantially equal to the excitation frequency. The plurality of magnetic oscillators is configured to generate a time-varying second magnetic field in response to the first magnetic field.

Claims

1. A power transmitter configured to wirelessly transfer power to at least one power receiver, the power transmitter comprising:

at least one excitation circuit configured to generate a time-varying first magnetic field in response to a time-varying electric current flowing through the at least one excitation circuit, the time-varying first magnetic field having an excitation frequency; and

a plurality of magnetic oscillators, each magnetic oscillator of the plurality of magnetic oscillators having a mechanical resonant frequency substantially equal to the excitation frequency, the plurality of magnetic oscillators configured to generate a time-varying second magnetic field in response to the first magnetic field.

2. The power transmitter of claim 1, wherein the at least one excitation circuit comprises at least one coil surrounding at least a portion of the plurality of magnetic oscillators.

3. The power transmitter of claim 1, wherein an impedance of the at least one excitation circuit has an imaginary component that is equal to zero at a frequency substantially equal to the mechanical resonant frequency.

4. The power transmitter of claim 1, further comprising at least one substrate mechanically coupled to the plurality of magnetic oscillators.

5. The power transmitter of claim 1, wherein the plurality of magnetic oscillators is a micro-electro-mechanical system (MEMS) structure.

6. The power transmitter of claim 1, wherein each magnetic oscillator of the plurality of magnetic oscillators comprises a movable magnetic element configured to rotate about an axis in response to a torque applied to the movable magnetic element by the first magnetic field.

7. The power transmitter of claim 6, wherein the movable magnetic element comprises at least one spring configured to apply a restoring force to the movable magnetic element upon rotation of the movable magnetic element.

8. The power transmitter of claim 1, wherein the plurality of magnetic oscillators is arranged in a three-dimensional array.

9. The power transmitter of claim 8, wherein the three-dimensional array comprises:

at least one first plane comprising a first set of magnetic oscillators of the plurality of magnetic oscillators, each magnetic oscillator of the first set of magnetic oscillators having a magnetic moment pointing in a first direction, the first set of magnetic oscillators having a first summed magnetic moment comprising a time-varying component and a time-invariant component; and

at least one second plane comprising a second set of magnetic oscillators of the plurality of magnetic oscillators, each magnetic oscillator of the second set of magnetic oscillators having a magnetic moment pointing in a second direction, the second set of magnetic oscillators having a second summed magnetic moment comprising a time-varying component and a time-invariant component, wherein the time-invariant component of the first summed magnetic moment and the time-invariant component of the second summed magnetic moment have substantially equal magnitudes and point in substantially opposite directions.

10. The power transmitter of claim 8, wherein the three-dimensional array comprises:

a first plane comprising a first set of magnetic oscillators of the plurality of magnetic oscillators arranged to have a first polarity; and

a second plane adjacent to the first plane, the second plane comprising a second set of magnetic oscillators of the plurality of magnetic oscillators arranged to have a second polarity different than the first polarity to at least partially reduce a quasi-static portion of a summed magnetic moment generated by the first set of magnetic oscillators and the second set of magnetic oscillators.

11. A method of transmitting power wirelessly, the method comprising:

generating a time-varying first magnetic field having an excitation frequency; and

generating a time-varying second magnetic field by applying the first magnetic field to a plurality of magnetic oscillators, each magnetic oscillator of the plurality of magnetic oscillators having a mechanical resonant frequency substantially equal to the excitation frequency.

12. The method of claim 11, wherein generating the time-varying first magnetic field comprises flowing an electrical current through at least one excitation circuit comprising at least one coil surrounding at least a portion of the plurality of magnetic oscillators.

13. The method of claim 12, wherein an impedance of the at least one excitation circuit has an imaginary component that is equal to zero at a frequency substantially equal to the mechanical resonant frequency.

14. The method of claim 11, wherein the plurality of magnetic oscillators is a micro-electro-mechanical system (MEMS) structure.

15. The method of claim 11, wherein generating the time-varying second magnetic field comprises rotating a movable magnetic element of each magnetic oscillator of the plurality of magnetic oscillators about an axis in response to a torque applied to the movable magnetic element by the first magnetic field.

16. The method of claim 15, further comprising applying a restoring force to the movable magnetic element upon rotation of the movable magnetic element.

17. The method of claim 11, wherein the plurality of magnetic oscillators is arranged in a three-dimensional array.

18. The method of claim 17, wherein the three-dimensional array comprises:

at least one first plane comprising a first set of magnetic oscillators of the plurality of magnetic oscillators, each magnetic oscillator of the first set of magnetic oscillators having a magnetic moment pointing in a first direction, the first set of magnetic oscillators having a first summed magnetic moment comprising a time-varying component and a time-invariant component; and

at least one second plane comprising a second set of magnetic oscillators of the plurality of magnetic oscillators, each magnetic oscillator of the second set of magnetic oscillators having a magnetic moment pointing in a second direction, the second set of magnetic oscillators having a second summed magnetic moment comprising a time-varying component and a time-invariant component, wherein the time-invariant component of the first summed magnetic moment and the time-invariant component of the second summed magnetic moment have substantially equal magnitudes and point in substantially opposite directions.

19. A power transmitter configured to wirelessly transfer power to at least one power receiver, the power transmitter comprising:

means for generating a time-varying first magnetic field having an excitation frequency; and

means for generating a time-varying second magnetic field in response to the time-varying first magnetic field.

20. The power transmitter of claim 19, wherein the means for generating the time-varying first magnetic field comprises at least one excitation circuit configured to have a time-varying electric current flowing through the at least one excitation circuit.

21. The power transmitter of claim 19, wherein the means for generating the time-varying second magnetic field comprises a plurality of magnetic oscillators, each magnetic oscillator of the plurality of magnetic oscillators having a mechanical resonant frequency substantially equal to the excitation frequency.