FOREIGN OBJECT DETECTION IN WIRELESS ENERGY TRANSFER SYSTEMS

• US 20130069441A1
• Filed: 09/10/2012
• Published: 03/21/2013
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: WiTricity Corporation
• Inventors: Verghese, Simon, Kesler, Morris P., Hall, Katherine L., Lou, Herbert Toby
• Granted Patent: US 9,442,172 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 53/12 Inductive energy transfer
• CPC Class Codes: B60L 53/124 Detection or removal of foreign bodies
• CPC Class Codes: G01R 33/10 Plotting field distribution ; Measuring field distribution
• CPC Class Codes: G01V 3/10 using induction coils
• CPC Class Codes: H01F 27/2804 Printed windings
• 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 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• 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

A wireless energy transfer system includes a foreign object debris detection system. The system includes at least one wireless energy transfer source configured to generate an oscillating magnetic field. The foreign object debris may be detected by at least one field gradiometer positioned in the oscillating magnetic field. The voltage of the at least one field gradiometer may be measured using readout circuitry and a feedback loop based on the readings from the gradiometers may be used to control the parameters of the wireless energy source.

Claims

1. A foreign object debris detection system for a wireless energy transfer system comprising:

at least one magnetic field sensor, and

at least one readout circuit to measuring electrical parameters of the at least one magnetic field sensor,

wherein the at least one magnetic field sensor is positioned within the magnetic field of the wireless energy transfer system.

2. The system of claim 1, wherein the at leat one magnetic field sensor comprises a magnetic field gradiometer.

3. The system of claim 2, wherein the at least one magnetic field gradiometer comprises a figure-8 quadrupole conductor loop.

4. The system of claim 2, wherein the at least one magnetic field gradiometer comprises an octupole conductor loop.

5. The system of claim 2, wherein the readout circuit has an input impedance sufficient to substantially prevent circulating currents in the gradiometer loop.

6. The system of claim 3, wherein the figure-8 quadrupole conductor loop is printed on a circuit board.

7. The system of claim 6, wherein the figure-8 quadrupole conductor loop is rectangular

8. The system of claim 3, wherein the system comprises an array of gradiometer loops positioned in the magnetic field of the wireless energy transfer.

9. The system of claim 8, wherein the system comprises multiple layers of offset and overlapped gradiometer loops.

10. The system of claim 5, wherein the readout circuitry is multiplexed among a plurality of gradiometer loops.

12. The system of claim 2, wherein the gradiometer is at least twice the size of a smallest foreign object debris (FOD) to be detected.

11. The system of claim , further comprising a feedback loop to adjust the parameters of the wireless energy transfer based on readings from the foreign object debris detection system.

13. A wireless energy transfer system with foreign object debris detection, the system comprising:

at least one wireless energy transfer source configured to generate an oscillating magnetic field;

at least one magnetic field gradiometer positioned in the oscillating magnetic field;

a readout circuit to measure electrical parameters of the field gradiometer; and

a feedback loop to control the parameters of the wireless energy transfer source in response to the measured electrical parameters of the field gradiometer.

14. The system of claim 13, further comprising at least one temperature sensor wherein the temperature sensor is positioned to measure the temperature near the wireless energy transfer source.

15. The system of claim 13, wherein a reading from the gradiometer is used to shut down the energy transfer of the at least one wireless energy transfer source.

16. The system of claim 13, wherein the system further comprises an array of field gradiometers connected to high-input-impedance readout circuitry.

17. The system of claim 16, wherein the high impedance readout circuitry monitors the voltage of the gradiometer loops.

18. The system of claim 17, wherein the high impedance readout circuitry monitors the phase of the voltage signal of the gradiometer loops.

19. The system of claim 18, further comprising a field sensing loop for synchronizing the readout circuitry with a frequency of the oscillating magnetic fields of the at least one wireless energy transfer source.