Extended-range positioning system based on foreign-object detection

Patent metadata

Field	Value
Publication number	US-11142084-B2
Application number	US-201916284959-A
Country	US
Kind code	B2
Filing date	Feb 25, 2019
Priority date	Jul 31, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

Systems and methods are described for an extended-range positioning system based on foreign-object detection (FOD). In particular, a power-transfer apparatus is disclosed that includes a coil and a foreign-object-detection (FOD) system. The coil is configured to generate a magnetic field based on an electric current running through the coil for transferring power to a receiver device. the FOD system includes a plurality of FOD sense loops, FOD circuitry, and active-beacon receive circuitry. The FOD sense loops detect metal objects within the magnetic field based on changes to an electrical characteristic(s) of one or more of the FOD sense loops. The FOD circuitry processes a modulation pattern of the electrical characteristic(s) of the one or more FOD sense loops and provides first positioning information. The active-beacon receive circuitry processes induced voltage in at least two sense loops to provide second positioning information.

First claim

What is claimed is:

1. A power-transfer apparatus comprising:
a coil configured to generate a magnetic field based on an electric current running through the coil for transferring power to a receiver device; and
a foreign-object-detection (FOD) system including:
a plurality of FOD sense loops configured to detect metal objects within the magnetic field generated by the coil based on changes to one or more electrical characteristics of one or more FOD sense loops of the plurality of FOD sense loops;
FOD circuitry configured to process a modulation pattern of the one or more electrical characteristics of the one or more FOD sense loops and provide first positioning information; and
active-beacon receive circuitry configured to process induced voltage in at least two sense loops to provide second positioning information.

2. The power-transfer apparatus as described in claim 1 , wherein the FOD system is configured to provide the first positioning information and the second positioning information to a system that provides feedback to a driver of an electric vehicle or autonomous driving system to enable the driver or autonomous driving system to correctly align the electric vehicle with the power-transfer apparatus.

3. The power-transfer apparatus as described in claim 1 , wherein:
the first positioning information corresponds to a first position of a passive beacon in the receiver device when the passive beacon is located directly over the one or more FOD sense loops; and
the second positioning information corresponds to a second position of an active beacon of the receiver device when the active beacon is located in an approach sector, the approach sector comprising an area proximate to and outside of a target sector defined by the plurality of FOD sense loops.

4. The power-transfer apparatus as described in claim 1 , further comprising ferrite configured to channel magnetic flux of the magnetic field, the at least two sense loops each comprising a circular receiver coil disposed proximate to the coil on an opposite side of the coil from the ferrite.

5. The power-transfer apparatus as described in claim 4 , wherein the circular receiver coil defines a planar area that is smaller than an area of a surface of the ferrite.

6. The power-transfer apparatus as described in claim 1 , wherein the active-beacon receive circuitry comprises a parallel-tuned circuit.

7. The power-transfer apparatus as described in claim 1 , wherein the induced voltage in the at least two sense loops is induced by a horizontally-polarized transmitter at the receiver device.

8. The power-transfer apparatus as described in claim 1 , wherein the second positioning information includes an estimated distance from a target position to an active beacon in the receiver device.

9. The power-transfer apparatus as described in claim 1 , wherein the second positioning information includes a lateral offset defining a distance that an active beacon in the receiver device is offset from a centerline of the coil.

10. The power-transfer apparatus as described in claim 1 , wherein the first positioning information is based on a passive beacon at the receiver device.

11. The power-transfer apparatus as described in claim 1 , wherein the second positioning information is based on an active beacon at the receiver device.

12. The power-transfer apparatus as described in claim 1 , wherein the FOD system further comprises a controller configured to:
use the second positioning information until the modulation pattern of the one or more electrical characteristics of the one or more FOD sense loops is detected; and
when the modulation pattern is detected, switch to using the first position information obtained from the FOD circuitry.

13. A wireless-power receiver apparatus, comprising:
a receive coil;
a passive-beacon circuit comprising a beacon loop configured to generate a modulation, based on a modulated impedance state of the passive-beacon circuit, that is detectable by a foreign-object-detection (FOD) system at a wireless-power transmitter apparatus for determining first positioning information of the beacon loop relative to the FOD system; and
an active-beacon circuit comprising a signal generator circuit configured to couple to a portion of a tuning capacitor of the receive coil, the active-beacon circuit configured to inject an electric current into the receive coil to cause the receive coil to act as a beacon transmission antenna that generates an active beacon signal that is detectable by the FOD system for determining second positioning information of the receive coil relative to the FOD system.

14. The wireless-power receiver apparatus as described in claim 13 , wherein the receive coil is horizontally polarized such that a polarization of the receive coil is substantially parallel to a plane defined by the receive coil.

15. The wireless-power receiver apparatus as described in claim 13 , wherein:
the active-beacon circuit comprises a rejection filter incorporated into a coupling transformer based on stray inductance of the coupling transformer connected in parallel to a shunt capacitor; and
the rejection filter is connected with a series capacitor to create a series resonant circuit to boost the active beacon signal.

16. The wireless-power receiver apparatus as described in claim 13 , wherein the second positioning information indicates a position of the receive coil as the receive coil approaches the wireless-power transmitter apparatus.

17. The wireless-power receiver apparatus as described in claim 13 , wherein the second positioning information includes an estimated distance from the receive coil to a target position over the FOD system and an estimated offset distance from a centerline of the FOD system.

18. The wireless-power receiver apparatus as described in claim 13 , wherein the first positioning information indicates a position of the beacon loop when the beacon loop is directly above one or more sense loops of the FOD system.

19. The wireless-power receiver apparatus as described in claim 13 , wherein the active-beacon circuit comprises one or more rejection filters to suppress voltages induced due to power transfer between the wireless-power receiver apparatus and the wireless-power transmitter apparatus.

20. A method for detecting presence and position of an active beacon, the method comprising:
detecting an induced voltage in two or more foreign-object-detection (FOD) sense loops of a FOD system in response to a magnetic field generated by a beacon transmitter in a receiver device;
measuring a magnitude of the induced voltage at each of the two or more FOD sense loops;
estimating a distance between the active beacon and a target position on the FOD system based on the magnitudes measured at the two or more FOD sense loops;
determining a lateral offset of the receiver device relative to the FOD system based on a comparison between the magnitudes of the two or more FOD sense loops; and
generating position information based on the estimated distance and the lateral offset, the position information usable to align the receiver device with a power-transfer apparatus for transferring power to an electric device connected to the receiver device.

21. The method as described in claim 20 , wherein the two or more FOD sense loops are each disposed proximate to a corner of a rectangular array of FOD sense loops of the FOD system.

22. The method as described in claim 20 , further comprising measuring

Assignees

• Witricity Corp

Inventors

• Sieber Lukas
• Daetwyler Andreas
• Fischer Marcel

Classifications

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H01F27/36

  Electric or magnetic shields or screens (movable for varying inductance H01F21/10) · CPC title

• H01F27/402

  Association of measuring or protective means · CPC title

• H02J50/12

  of the resonant type · CPC title

• Y02T10/7072

  Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors · CPC title