FOREIGN OBJECT DETECTION IN WIRELESS ENERGY TRANSFER SYSTEMS

• US 20150323694A1
• Filed: 05/07/2015
• Published: 11/12/2015
• Est. Priority Date: 05/07/2014
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: WiTricity Corporation
• Inventors: Roy, Arunanshu Mohan, Katz, Noam, Atnafu, Nathaniel Endale
• Granted Patent: US 10,018,744 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 2270/147 electro magnetic [EMI]
• CPC Class Codes: B60L 53/124 Detection or removal of foreign bodies
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00
• CPC Class Codes: G01V 3/104 using several coupled or uncoupled coils G01V3/101 takes precedence
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

Systems and methods for detecting foreign object debris around a wireless power transfer system include a plurality of detectors, each detector featuring one or more loops of conducting material, and a controller configured to measure at least one of a voltage and a current in each detector and to determine, based on the measurements, whether foreign object debris is present around the wireless power transfer system, where at least some of the plurality of detectors include a first number of loops of the conducting material, and at least some of the plurality of detectors include a second number of loops of the conducting material larger than the first number.

Claims

1. An apparatus for detecting foreign object debris around a wireless power transfer system, the apparatus comprising:

a plurality of detectors, each detector comprising one or more loops of conducting material; and

a controller configured to measure at least one of a voltage and a current in each detector and to determine, based on the measurements, whether foreign object debris is present around the wireless power transfer system,

wherein at least some of the plurality of detectors comprise a first number of loops of the conducting material, and at least some of the plurality of detectors comprise a second number of loops of the conducting material larger than the first number.

2. The apparatus of claim 1, wherein at least some of the plurality of detectors contain one loop and wherein at least some of the plurality of detectors comprise two loops.

3. The apparatus of claim 2, wherein at least some of the plurality of detectors comprise three loops.

4. The apparatus of claim 1 wherein during operation, the apparatus is positioned so that magnetic flux generated by a wireless power transfer source passes through the plurality of detectors, and wherein detectors comprising the first number of loops are positioned in regions where the magnetic flux is larger than in regions in which detectors comprising the second number of loops are positioned.

5. The apparatus of claim 1, wherein the plurality of detectors form an array.

6. The apparatus of claim 5, wherein spacings between at least some adjacent detectors in the array are different.

7. The apparatus of claim 5, wherein cross-sectional areas of at least some detectors in the array are different from cross-sectional areas of at least some other detectors in the array.

8. A method for detecting foreign object debris around a wireless power transfer system, the method comprising:

measuring at least one of a voltage and a current in each one of a plurality of detectors; and

determining, based on the measurements, whether foreign object debris is present around the wireless power transfer system,

wherein each of the detectors comprises one or more loops of conducting material; and

wherein at least some of the plurality of detectors comprise a first number of loops of the conducting material, and at least some of the plurality of detectors comprise a second number of loops of the conducting material larger than the first number.

9. A wireless power transfer system comprising:

a wireless power transfer source configured to generate a source magnetic field at a first frequency to transfer power to a wireless power receiver;

an auxiliary magnetic field source configured to generate an auxiliary magnetic field at a second frequency;

at least one detector configured to generate an electrical signal in response to perturbations in the auxiliary magnetic field generated by the auxiliary magnetic field source; and

a controller configured to determine whether foreign object debris is present around the wireless power transfer system based on the electrical signal.

10. The wireless power transfer system of claim 9, wherein the auxiliary magnetic field source comprises at least one auxiliary coil and at least one amplifier.

11. The wireless power transfer system of claim 9, wherein the first frequency is equal to the second frequency.

12. The wireless power transfer system of claim 9, wherein the first frequency is different from the second frequency.

13. The wireless power transfer system of claim 9, further comprising a power supply coupled to the wireless power transfer source and configured to provide power to drive the wireless power source, and wherein the power supply is turned off when the auxiliary magnetic field source is generating an auxiliary magnetic field.

14. The wireless power transfer system of claim 9, wherein the auxiliary magnetic field source comprises up to four auxiliary coils and up to four amplifiers.

15. The wireless power transfer system of claim 10, wherein the wireless power source comprises a source resonator coil wound over a first area, and wherein the at least one auxiliary coil is configured to be wound over the first area.

16. The wireless power transfer system of claim 15, wherein the at least one auxiliary coil comprises two sets of conductor windings connected in series, each of the two sets of conductor windings being wound over one of a second and a third area, respectively.

17. The wireless power transfer system of claim 16, wherein a sum of the second and third areas is substantially equal to the first area.

18. The wireless power transfer system of claim 15, wherein the at least one auxiliary coil comprises four sets of conductor windings connected in series, each of the four sets of conductor windings being wound over one of a second, third, fourth, and fifth area, respectively.

19. The wireless power transfer system of claim 18 wherein a sum of the second, third, fourth, and fifth areas is substantially equal to the first area.

20. The wireless power transfer system of claim 15, wherein the auxiliary magnetic field induces a current in the source resonator coil, and wherein the current in the source resonator coil generates a magnetic field having a strength greater than the auxiliary magnetic field.

21. The wireless power transfer system of claim 15, wherein the at least one auxiliary coil comprises a first portion of a conductor winding on a first circuit board and a second portion of a conductor winding on a second circuit board, and wherein a connector between the first and second circuit boards provides an electrical connection between the first and second portions of the conductor winding.