Foreign object detection in wireless energy transfer systems

Patent metadata

Field	Value
Publication number	US-9404954-B2
Application number	US-201314059141-A
Country	US
Kind code	B2
Filing date	Oct 21, 2013
Priority date	Oct 19, 2012
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

The disclosure features apparatus, methods, and systems for wireless power transfer that include a power source featuring at least one resonator, a power receiver featuring at least one resonator, a first detector featuring one or more loops of conductive material and configured to generate an electrical signal based on a magnetic field between the power source and the power receiver, a second detector featuring conductive material, and control electronics coupled to the first and second detectors, where during operation, the control electronics are configured to measure the electrical signal of the first detector and compare the measured electrical signal of the first detector to baseline electrical information for the first detector to determine information about whether debris is positioned between the power source and the power receiver.

First claim

What is claimed is:

1. A wireless power transfer system, comprising:
a power source comprising at least one resonator;
a power receiver comprising at least one resonator, wherein the power receiver is configured to receive electrical power transmitted wirelessly by the power source;
a detector positioned between the power source and the power receiver, wherein the detector is configured to generate an electrical signal based on a magnetic field between the power source and the power receiver; and
control electronics coupled to the power source and detector, wherein the control electronics are configured to:
activate the power source to generate a magnetic field between the power source and the power receiver;
measure the electrical signal of the detector; and
determine whether debris is positioned between the power source and the power receiver by comparing baseline information to the measured electrical signal,
wherein the baseline information comprises information about an electrical signal generated by the detector when no debris is positioned between the power source and the power receiver; and
wherein the control electronics are configured to compare the baseline information to the measured signal by determining mean and covariance matrices for the baseline information and determining whether debris is positioned between the power source and the power receiver based on the mean and covariance matrices.

2. The system of claim 1 , wherein the control electronics are configured to calculate a likelihood value that debris is positioned between the power source and the power receiver based on the mean and covariance matrices.

3. The system of claim 2 , wherein the control electronics are configured to calculate a probability value between 0 and 1 that debris is positioned between the power source and the power receiver, based on the likelihood value.

4. The system of claim 2 , wherein the control electronics are configured to determine whether debris is positioned between the power source and the power receiver by comparing the likelihood value to a threshold likelihood value.

5. The system of claim 1 , wherein the control electronics are configured to obtain the baseline information.

6. The system of claim 5 , wherein the control electronics are configured to obtain the baseline information by retrieving the information from an electronic storage unit.

7. The system of claim 5 , wherein the control electronics are configured to obtain the baseline information by activating the power source with no debris in the vicinity of the power source to generate a magnetic flux through the detector, and measuring the electrical signal of the detector in response to the magnetic flux.

8. The system of claim 7 , wherein the control electronics are configured to activate the power source and to measure the electrical signal of the detector with the power source and the power receiver at least partially aligned.

9. The system of claim 7 , wherein the control electronics are configured to activate the power source and to measure the electrical signal of the detector without power transfer occurring between the power source and the power receiver.

10. The system of claim 1 , wherein the baseline information comprises information about electrical signals generated by the detector that correspond to different operating states of the system.

11. The system of claim 10 , wherein the different operating states correspond to different energy transfer rates between the power source and the power receiver.

12. The system of claim 10 , wherein the different operating states correspond to different alignments between the power source and the power receiver.

13. The system of claim 10 , wherein the different operating states correspond to different spacings between the power source and the power receiver measured along a direction orthogonal to a plane defined by the at least one resonator of the power source.

14. The system of claim 7 , wherein the control electronics are configured to obtain the baseline information by measuring the electrical signal of the detector multiple times in response to the magnetic flux, and wherein the mean and covariance matrices include contributions from the multiple measurements of the electrical signal.

15. The system of claim 10 , wherein the control electronics are configured to generate mean and covariance matrices that correspond to each of the different operating states.

16. The system of claim 15 , wherein the control electronics are configured to determine the operating state of the system by comparing the measured electrical signal of the detector to the mean and covariance matrices corresponding to each of the different operating states.

17. The system of claim 1 , wherein the power source is a component of a vehicle charging station.

18. The system of claim 1 , wherein the power receiver is a component of a vehicle.

19. The system of claim 1 , wherein the electrical signal generated by the detector comprises at least one of a voltage and a current.

20. The system of claim 1 , wherein the detector comprises multiple loops of conductive material positioned between the power source and the power receiver.

21. The system of claim 20 , wherein the multiple loops are spaced from one another in the plane, and wherein a spacing between adjacent loops varies.

22. The system of claim 21 , wherein a magnetic flux density generated by the power source in a first region of the plane is larger than a magnetic flux density in a second region of the plane, and wherein the spacing between adjacent loops is smaller in the first region than in the second region.

23. The system of claim 1 , wherein the detector is positioned closer to the power receiver than to the power source.

24. The system of claim 1 , wherein a total cross-sectional area of the at least one resonator of the power receiver is 80% or more of a full-width at half maximum cross-sectional area of a magnetic field generated by the power source at a position of the power receiver.

25. The system of claim 1 , wherein the power source is configured to transfer 1 kW or more of power to the power receiver.

26. The system of claim 10 , wherein the control electronics are configured to compare the measured signal to a portion of the baseline information that corresponds to the operating state of the system.

27. The system of claim 1 , wherein the power source is configured to generate a magnetic flux of 6.25 μT or more between the power source and the power receiver.

28. The system of claim 12 , wherein the detector comprises multiple loops of conductive material each configured to generate an electrical signal when the power source generates a magnetic field, and wherein the control electronics are configured to measure the electrical signals generated by at least some of the multiple loops and to determine information about misalignment between the power source and the power receiver based on the measured electrical signals.

29. The system of claim 28 , wherein the at least some of the multiple loops are positioned adjacent to an edge of the power source.

30. The system of claim 29 , wherein the control electronics are configured to determine the information about misalignment by comparing electrical signals generated by the at least some of the multiple loop

Assignees

• Witricity Corp

Inventors

• Roy Arunanshu Mohan
• Katz Noam
• Kurs Andre B
• Buenrostro Christopher
• Verghese Simon
• Kesler Morris P
• Hall Katherine L
• Lou Herbert Toby

Classifications

• B60L53/65

  involving identification of vehicles or their battery types · CPC title

• B60L53/12

  Inductive energy transfer · CPC title

• B60L2250/10

  by alarm · CPC title

• B60L2210/40

  DC to AC converters · CPC title

• B60L2270/147

  electro magnetic [EMI] · CPC title