SYSTEMS, METHODS, AND APPARATUS FOR FOREIGN OBJECT DETECTION LOOP BASED ON INDUCTIVE THERMAL SENSING

• US 20150331135A1
• Filed: 05/15/2014
• Published: 11/19/2015
• Est. Priority Date: 05/15/2014
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Widmer, Hanspeter
• Granted Patent: US 10,295,693 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01V 3/10 using induction coils
• CPC Class Codes: G01V 3/101 by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26
• 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

This disclosure provides systems, methods and apparatus for detecting foreign objects. An apparatus for detecting a presence of an object is provided. The apparatus includes a coil configured to inductively sense a presence of an object based on an electrical characteristic of the coil that varies as a function of a temperature of the object when the object is exposed to an alternating magnetic field. The apparatus further includes a controller configured to detect a change in the electrical characteristic.

Claims

1. An apparatus for detecting an object, comprising:

a coil configured to inductively sense a presence of the object based on an electrical characteristic of the coil that varies as a function of a temperature of the object when the object is exposed to an alternating magnetic field; and

a controller configured to detect a change in the electrical characteristic.

2. The apparatus of claim 1, wherein the electrical characteristic comprises an equivalent resistance, equivalent inductance, resonant frequency, a complex resonant frequency, a dampening factor, a Q-factor, an impedance, or a phase when the coil is tuned on resonance and excited by a sinusoidal signal source.

3. The apparatus of claim 1, wherein the electrical characteristic comprises an impulse response of the coil when the coil is excited by a pulse signal source, a response of the coil when the coil is excited by any of a voltage or current time function, or a response of the coil when the coil is tuned on resonance and excited by a voltage or a current time function.

4. The apparatus of claim 1, wherein the coil comprises a plurality of coils and wherein the controller is further configured to multiplex measurements of a plurality of changes in the electrical characteristic of the plurality of coils.

5. The apparatus of claim 1, wherein the controller is further configured to:

schedule an exposure cycle for the magnetic field; and

compare the detected change in the electrical characteristic over at least a portion of time of the exposure cycle with the exposure cycle over the same period of time; and

determine the presence of the object based on the comparison of the detected change in the electrical characteristic with the exposure cycle.

6. The apparatus of claim 5, wherein the controller is further configured determine the presence of the object when the detected change in the electrical characteristic during the exposure cycle exceeds a threshold.

7. The apparatus of claim 5, wherein the controller is further configured to compare a derivative of the detected change in the electrical characteristic over at least a portion of time of the exposure cycle with the exposure cycle over the same period of time.

8. The apparatus of claim 5, further comprising a transmitter configured to transmit a signal to adjust the magnetic field exposure.

9. The apparatus of claim 8, further comprising a receiver configured to receive a feedback signal indicating a timing schedule for the exposure cycle and a strength of the magnetic field exposure.

10. The apparatus of claim 9, wherein the receiver is further configured to receive a reference signal from a device generating the exposure magnetic field exposure indicating electrical characteristics of a power signal used to generate the exposure magnetic field.

11. The apparatus of claim 1, wherein the coil and the controller are positioned within a wireless power transmitter.

12. A method for detecting a presence of an object, comprising:

sensing a presence of the object based on an electrical characteristic of a coil that varies as a function of a temperature of the object when the object is exposed to an alternating magnetic field; and

detecting a change in the electrical characteristic.

13. The method of claim 12, wherein the electrical characteristic comprises an equivalent resistance, equivalent inductance, resonant frequency, a complex resonant frequency, a dampening factor, a Q-factor, an impedance, or a phase when the coil is tuned on resonance and excited by a sinusoidal signal source.

14. The method of claim 12, wherein the electrical characteristic comprises an impulse response of the coil when the coil is excited by a pulse signal source, a response of the coil when the coil is excited by any of a voltage or current time function, or a response of the coil when the coil is tuned on resonance and excited by a voltage or a current time function.

15. The method of claim 12, wherein detecting a change in an electrical characteristic comprises:

detecting a change in an electrical characteristic in each of a plurality of coils; and

multiplexing measurements of the change in the electrical characteristic in each of the plurality of coils.

16. The method of claim 12, further comprising:

scheduling an exposure cycle for the magnetic field;

comparing the detected change in the electrical characteristic over at least a portion of time of the exposure cycle with the exposure cycle over the same period of time; and

determining the presence of the object based on the comparison of the detected change in the electrical characteristic with the exposure cycle.

17. The method of claim 16, wherein determining the presence of the object comprises determining the presence of the object when the detected change in the electrical characteristic during the exposure cycle exceeds a threshold.

18. The method of claim 16, wherein comparing the detected change in the electrical characteristic comprises comparing a derivative of the detected change in the electrical characteristic over at least a portion of time of the exposure cycle with the exposure cycle over the same period of time.

19. The method of claim 16, further comprising transmitting a signal to adjust the magnetic field exposure.

20. The method of claim 19, further comprising receiving a feedback signal indicating a timing schedule for the exposure cycle and a strength of the magnetic field exposure.

21. The method of claim 20, further comprising receiving a reference signal from a device generating the exposure magnetic field indicating electrical characteristics of a power signal used to generate the exposure magnetic field.

22. An apparatus for detecting an object, comprising:

means for sensing a presence of the object based on an electrical characteristic of the sensing means that varies as a function of a temperature of the object when the object is exposed to an alternating magnetic field; and

means for detecting a change in the electrical characteristic.

23. The apparatus of claim 22, wherein the electrical characteristic of the sensing means comprises an equivalent resistance, equivalent inductance, resonant frequency, a complex resonant frequency, a dampening factor, a Q-factor, an impedance, or a phase when the coil is tuned on resonance and excited by a sinusoidal signal source.

24. The apparatus of claim 22, wherein the electrical characteristic comprises an impulse response of the sensing means when the sensing means is excited by a pulse signal source, a response of the sensing means when the sensing means is excited by any of a voltage or current time function, or a response of the sensing means when the sensing means is tuned on resonance and excited by a voltage or a current time function.

25. The apparatus of claim 22, further comprising:

means for scheduling an exposure cycle for the magnetic field;

means for comparing the detected change in the electrical characteristic of the sensing means over at least a portion of time of the exposure cycle with the exposure cycle over the same period of time; and

means for determining the presence of the object based on the comparison of the detected change in the electrical characteristic with the exposure cycle.

26. The apparatus of claim 22, wherein the determining means further comprises means for determining the presence of the object when the detected change in the electrical characteristic of the sensing means during the exposure cycle exceeds a threshold.

27. The apparatus of claim 22, wherein the comparing means further comprises means for comparing a derivative of the detected change in the electrical characteristic of the sensing means over at least a portion of time of the exposure cycle with the exposure cycle over the same period of time.

28. The apparatus of claim 22, further comprising means for transmitting a signal to adjust the magnetic field exposure.

29. The apparatus of claim 22, further comprising means for receiving a feedback signal indicating a timing schedule for the exposure cycle and a strength of the magnetic field exposure.

30. The apparatus of claim 29, wherein the receiving means further comprises means for receiving a reference signal from a device generating the exposure magnetic field indicating electrical characteristics of a power signal used to generate the exposure magnetic field.