Extending the distance range of near-field wireless power delivery

• US 10,135,257 B1
• Filed: 11/13/2015
• Issued: 11/20/2018
• Est. Priority Date: 11/13/2015
• Status: Active Grant

• Current Assignee: X Development LLC (Alphabet Inc.)
• Original Assignee: X Development LLC (Alphabet Inc.)
• Inventors: Adolf, Brian John, DeVaul, Richard Wayne
• Primary Examiner(s): Cox, Cassandra
• Application Number:
  US14/940,391
• Time in Patent Office: 1,103 Days
• Field of Search: None
• CPC Class Codes: H02J 2310/44 for aircrafts
• CPC Class Codes: H02J 50/05 using capacitive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

A system and method for wireless resonant power transfer is disclosed. The system may include a transmitter that, in addition to being configured for resonantly coupling power into an oscillating electric and/or magnetic field, is also configured to transmit one or more test signals. Test signals can include single frequency continuous wave test signals, frequency sweep test signals, and time-pulsed modulated test signals. By comparing measurements of phase and amplitude of both the transmitted test signal and one or more reflections of the test signal reflected by one or more reflecting entities, electromagnetic properties of the one or more reflecting entities may be determined. The determined properties may then be used to enhance the efficiency and/or effectiveness of power transfer, and/or to distinguish between legitimate and illegitimate consumption of wirelessly transferred power by devices in the oscillating field.

Claims

1. A system for wireless power transfer comprising:

a transmitter comprising;

a transmit-resonator configured to couple power from a power source into an oscillating field generated by the transmit-resonator resonating at a resonant frequency, the oscillating field being at least one of an oscillating electric field or an oscillating magnetic field;

a signal generator, separate from the transmit-resonator, and configured to transmit one or more electromagnetic test signals at one or more frequencies, wherein the test signals are distinct from the oscillating field;

a test-signal receiver configured to receive a reflection of any given transmitted test signal from one or more reflecting entities that reflect at least a portion of the any given transmitted test signal; and

a source-device processor configured to determine one or more electromagnetic properties of a reflecting entity of the one or more reflecting entities based on at least a corresponding reflection from the reflecting entity;

at least one repeater comprising;

a coupling resonator configured to resonate at the resonant frequency in response to coupling to the oscillating field,

wherein the at least one repeater is configured to, in response to the coupling resonator resonating at the resonant frequency, re-emit the oscillating field; and

at least one receiver, the at least one receiver including;

a receive-resonator configured to resonate at the resonant frequency in response to coupling to the oscillating field,

wherein the at least one receiver is configured to, in response to the receive-resonator resonating at the resonant frequency, transfer at least a portion of power of the oscillating field to a load associated with the at least one receiver.

2. The system of claim 1, wherein each of the one or more reflecting entities is one of a repeater, an authorized receiver, an unauthorized receiver, or a parasitic load,

wherein an authorized receiver device is a receiver authorized by the transmitter to receive power from the transmitter via the oscillating field,

wherein an unauthorized receiver is a receiver that attempts to receive power from the transmitter via the oscillating field while not being authorized to do so by the transmitter,

and wherein a parasitic load is an entity that passively consumes power from the oscillating field in response to being situated the oscillating field.

3. The system of claim 1, wherein each of the one or more electromagnetic properties of the reflecting entity is at least one of impedance, admittance, or coupling constant.

4. The system of claim 1, wherein each transmitted test signal comprises sweep of multiple frequencies over an interval of time.

5. The system of claim 4, wherein the source-device processor is further configured to determine an electrical distance to the reflecting entity based on phase delay between a transmitted frequency sweep and a corresponding reflection of the frequency sweep from the reflecting entity.

6. The system of claim 1, wherein the source-device processor is further configured to determine one or more electromagnetic properties of a propagation path between the transmitter and the reflecting entity.

7. The system of claim 6, wherein each of the one or more electromagnetic properties of the propagation path between the transmitter and the reflecting entity is at least one of:

characteristic path impedance, presence of one or more intervening reflecting entities, or an impedance of one or more intervening reflecting entities.

8. The system of claim 1, wherein the transmitted test signal has an amplitude and phase, and the corresponding reflection has an amplitude and phase,

and wherein the source-processor is configured to determine the one or more electromagnetic properties of the reflecting entities based further on a comparison of the transmitted test signal and its corresponding reflection, wherein the comparison comprises a comparison of the amplitude and phase of the transmitted test signal with the amplitude and phase of its corresponding reflection.

9. The system of claim 1, wherein the reflecting entity is the at least one receiver,

and wherein the source-device processor is further configured to:

determine a receiver-load impedance of a receiver load associated with the at least one receiver based on at least one of;

an amount of power of the oscillating field reflected from the receiver to the transmitter, or an impedance parameter reported by the receiver to the transmitter over a wireless communication channel;

cause the receiver to adjust at least one of (i) the receiver-load impedance, (ii) the resonant frequency of the receive-resonator, or (iii) a time interval for wireless power delivery, based on the determined one or more electromagnetic properties of the reflecting entity; and

in correspondence with the receiver adjustment, adjust at least one of (i) an impedance-matching network of the transmitter to match the adjusted receiver-load impedance, (ii) the resonant frequency of the transmit-resonator, or (iii) the time interval for wireless power delivery.

10. The system of claim 2, wherein the source-device processor is further configured to:

determine whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized receiver or a parasitic load, based on the determined one or more electromagnetic properties of the reflecting entity; and

responsive to determining that the reflecting entity is one of an unauthorized receiver or a parasitic load, disrupting wireless delivery of power to the reflecting entity by adjusting at least one of the resonant frequency of the transmit-resonator or a time interval for wireless power delivery.

11. The system of claim 2, wherein the source-device processor is further configured to:

determine an electrical distance to the reflecting entity; and

determine whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized or a parasitic load based on the determined electrical distance.

12. The system of claim 2, wherein the source-device processor is further configured to:

determine a number of repeaters on a propagation path between the transmitter and the reflecting entity; and

determine whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized receiver or a parasitic load based on the determined number.

13. A method in a transmitter of a system configured for wireless power transfer, the method comprising:

a transmit-resonator of the transmitter coupling power from a power source into an oscillating field generated by the transmit-resonator resonating at a resonant frequency, the oscillating field being at least one of an oscillating electric field or an oscillating magnetic field;

transmitting by a signal generator of the transmitter one or more electromagnetic test signals at one or more frequencies, wherein the signal generator is separate from the transmit-resonator, and the test signals are distinct from the oscillating field;

receiving by a test-signal receiver of the transmitter a reflection of any given transmitted test signal from one or more reflecting entities that reflect at least a portion of the any given transmitted test signal; and

determining by a source-device processor of the transmitter one or more electromagnetic properties of a reflecting entity of the one or more reflecting entities based on at least a corresponding reflection from the reflecting entity.

14. The method of claim 13, wherein the system comprises the transmitter, and further comprises:

at least one repeater comprising;

a coupling resonator configured to resonate at the resonant frequency in response to coupling to the oscillating field,

wherein the at least one repeater is configured to, in response to the coupling resonator resonating at the resonant frequency, re-emit the oscillating field; and

at least one receiver, the at least one receiver including;

a receive-resonator configured to resonate at the resonant frequency in response to coupling to the oscillating field,

wherein the at least one receiver is configured to, in response to the receive-resonator resonating at the resonant frequency, transfer at least a portion of power of the oscillating field to a load associated with the at least one receiver.

15. The method of claim 13, wherein each transmitted test signal comprises a sweep of multiple frequencies over an interval of time.

16. The method of claim 14, wherein each of the one or more reflecting entities is one of a repeater, an authorized receiver, an unauthorized receiver, or a parasitic load,

wherein an authorized receiver device is a receiver authorized by the transmitter to receive power from the transmitter via the oscillating field,

wherein an unauthorized receiver is a receiver that actively attempts to receive power from the transmitter via the oscillating field while not authorized to do so by the transmitter,

and wherein a parasitic load is an entity that passively consumes power from the oscillating field in response to being situated the oscillating field.

17. The method of claim 13, wherein each of the one or more electromagnetic properties of the reflecting entity is at least one of impedance, or coupling constant.

18. The method of claim 13, further comprising:

determining by the source-device processor an electrical distance to the reflecting entity based on phase delay between a transmitted frequency sweep and a corresponding reflection of the frequency sweep from the reflecting entity.

19. The method of claim 13, further comprising:

determining by the source-device processor one or more electromagnetic properties of a propagation path between the transmitter and the reflecting entity.

20. The method of claim 19, wherein each of the one or more electromagnetic properties of the propagation path between the transmitter and the reflecting entity is at least one of:

characteristic path impedance, presence of one or more intervening reflecting entities, or an impedance of one or more intervening reflecting entities.

21. The method of claim 13, wherein the transmitted test signal has an amplitude and phase, and the corresponding reflection has an amplitude and phase, and wherein the method further comprises:

determining by the source-processor the one or more electromagnetic properties of the reflecting entity by comparing the amplitude and phase of the transmitted test signal with the amplitude and phase of the reflection.

22. The method of claim 14, wherein the reflecting entity is the at least one receiver,

and wherein the method further comprises:

determining by the source-device processor a receiver-load impedance of a receiver load associated with the at least one receiver based on at least one of;

an amount of power of the oscillating field reflected from the receiver to the transmitter, or an impedance parameter reported by the receiver to the transmitter over a wireless communication channel;

causing the receiver to adjust at least one of (i) the receiver-load impedance, (ii) the resonant frequency of the receive-resonator, or (iii) a time interval for wireless power delivery, based on the determined one or more electromagnetic properties of the reflecting entity; and

in correspondence with the receiver adjustment, adjust at least one of (i) an impedance-matching network of the transmitter to match the adjusted receiver-load impedance, (ii) the resonant frequency of the transmit-resonator, or (iii) the time interval for wireless power delivery.

23. The method of claim 16, further comprising:

determining by the source-device processor whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized receiver or a parasitic load, based on the determined one or more electromagnetic properties of the reflecting entity; and

responsive to determining that the reflecting entity is one of an unauthorized receiver or a parasitic load, disrupting wireless delivery of power to the reflecting entity by adjusting at least one of the resonant frequency of the transmit-resonator or a time interval for wireless power delivery.

24. The method of claim 16, further comprising:

determining by the source-device processor an electrical distance to the reflecting entity; and

determining by the source-device processor whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized or a parasitic load based on the determined electrical distance.

25. The method of claim 16, further comprising:

determining by the source-device processor a number of repeaters on a propagation path between the transmitter and the reflecting entity; and

determining by the source-device processor whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized receiver or a parasitic load based on the determined number.

26. A non-transitory computer-readable medium having instructions stored thereon that, when executed by one or more processors of a transmitter, cause the transmitter to carry out operations including:

causing a transmit-resonator of the transmitter to resonate at a resonant frequency in order to generate an oscillating field and to couple power from a power source into the oscillating field, the oscillating field being at least one of an oscillating electric field or an oscillating magnetic field;

causing a signal generator of the transmitter to transmit one or more electromagnetic test signals at one or more frequencies, wherein the signal generator is separate from the transmit-resonator, and the test signals are distinct from the oscillating field;

causing a test-signal receiver of the transmitter to receive a reflection of a given one of the transmitted test signals from a reflecting entity of one or more reflecting entities; and

determining one or more electromagnetic properties of the reflecting entity of the one or more reflecting entities based on at least the reflection from the reflecting entity.

27. The non-transitory computer-readable medium of claim 26, wherein the transmitter is comprised in a system configured for wireless power transfer, and wherein the system further comprises:

at least one repeater comprising;

a coupling resonator configured to resonate at the resonant frequency in response to coupling to the oscillating field,

wherein the at least one repeater is configured to, in response to the coupling resonator resonating at the resonant frequency, re-emit the oscillating field; and

at least one receiver, the at least one receiver including;

a receive-resonator configured to resonate at the resonant frequency in response to coupling to the oscillating field,

wherein the at least one receiver is configured to, in response to the receive-resonator resonating at the resonant frequency, transfer at least a portion of power of the oscillating field to a load associated with the at least one receiver.

28. The non-transitory computer-readable medium of claim 26, wherein each transmitted test signal comprises sweep of multiple frequencies over an interval of time.

29. The non-transitory computer-readable medium of claim 27, wherein each of the one or more reflecting entities is one of a repeater, an authorized receiver, an unauthorized receiver, or a parasitic load,

wherein an authorized receiver device is a receiver authorized by the transmitter to receive power from the transmitter via the oscillating field,

wherein an unauthorized receiver is a receiver that actively attempts to receive power from the transmitter via the oscillating field while not authorized to do so by the transmitter,

and wherein a parasitic load is an entity that passively consumes power from the oscillating field in response to being situated in the oscillating field.

30. The non-transitory computer-readable medium of claim 26, wherein each of the one or more electromagnetic properties of the reflecting entity is at least one of impedance, or coupling constant.

31. The non-transitory computer-readable medium of claim 26, wherein the operations further include:

determining an electrical distance to the reflecting entity based on phase delay between a transmitted frequency sweep and a corresponding reflection of the frequency sweep from the reflecting entity.

32. The non-transitory computer-readable medium of claim 26, wherein the operations further include:

determining one or more electromagnetic properties of a propagation path between the transmitter and the reflecting entity.

33. The non-transitory computer-readable medium of claim 32, wherein each of the one or more electromagnetic properties of the propagation path between the transmitter and the reflecting entity is at least one of:

characteristic path impedance, presence of one or more intervening reflecting entities, or an impedance of one or more intervening reflecting entities.

34. The non-transitory computer-readable medium of claim 26, wherein the transmitted test signal has an amplitude and phase, and the reflection has an amplitude and phase,

and wherein the operations further include:

determining the one or more electromagnetic properties of the reflecting entity by comparing the amplitude and phase of the transmitted test signal with the amplitude and phase of the reflection.

35. The non-transitory computer-readable medium of claim 27, wherein the reflecting entity is the at least one receiver,

and wherein the operations further include:

determining a receiver-load impedance of a receiver load associated with the at least one receiver based on at least one of;

a magnitude and phase of power of the oscillating field reflected from the receiver to the transmitter, or an impedance parameter reported by the receiver to the transmitter over a wireless communication channel;

causing the receiver to adjust at least one of (i) the receiver-load impedance, (ii) the resonant frequency of the receive-resonator, or (iii) a time interval for wireless power delivery, based on the determined one or more electromagnetic properties of the reflecting entity; and

in correspondence with the receiver adjustment, adjust at least one of (i) an impedance-matching network of the transmitter to match the adjusted receiver-load impedance, (ii) the resonant frequency of the transmit-resonator, or (iii) the time interval for wireless power delivery.

36. The non-transitory computer-readable medium of claim 29, wherein the operations further include:

determining whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized receiver or a parasitic load based on the determined one or more electromagnetic properties of the reflecting entity; and

responsive to determining that the reflecting entity is one of an unauthorized receiver or a parasitic load, disrupting wireless delivery of power to the reflecting entity by adjusting at least one of the resonant frequency of the transmit-resonator or a time interval for wireless power delivery.

37. The non-transitory computer-readable medium of claim 29, wherein the operations further include:

determining an electrical distance to the reflecting entity; and

determining whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized or a parasitic load based on the determined electrical distance.

38. The non-transitory computer-readable medium of claim 29, wherein the operations further include:

determining a number of repeaters on a propagation path between the transmitter and the reflecting entity; and

determining whether the reflecting entity is (i) an authorized receiver or (ii) one of an unauthorized receiver or a parasitic load based on the determined number.