Methods and apparatus for magnetic field strength measurement

• US 9,562,955 B2
• Filed: 09/22/2014
• Issued: 02/07/2017
• Est. Priority Date: 01/20/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Von Novak, William Henry III
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US14/493,165
• Publication Number:
  US 20150204949A1
• Time in Patent Office: 869 Days
• Field of Search: 324/258, 324/207.17
• US Class Current: 1/1
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence
• CPC Class Codes: H02J 50/12 of the resonant type

Abstract

This disclosure provides methods and apparatus for wireless power field testing. An apparatus for sensing magnetic field strength of a wireless charging pad is provided. The apparatus includes a plurality of conductive loops each configured to sense a strength of a magnetic field passing through a respective one of the plurality of conductive loops. The apparatus includes at least one pair of terminals configured to be electrically connected to one or more of the plurality of conductive loops and configured to provide a voltage signal having a magnitude proportional to the strength of the magnetic field passing through the one or more of the plurality of conductive loops. In some implementations, the apparatus further includes a multiplexer circuit configured to individually electrically connect each of at least a subset of the plurality of conductive loops to the at least one pair of terminals.

Claims

1. An apparatus for sensing magnetic field strength of a wireless charging pad, comprising:

a plurality of conductive loops, each configured to sense a strength of a magnetic field passing through a respective loop of the plurality of conductive loops;

at least one pair of terminals configured to be electrically connected to one or more of the plurality of conductive loops and configured to provide a voltage signal having a magnitude proportional to the strength of the magnetic field passing through the one or more of the plurality of conductive loops; and

a processing circuit configured to;

sum the voltage signal from, each of the plurality of conductive loops and

determine a magnetic field strength of the magnetic field intersecting the plurality at least in part on thee signals.

2. The apparatus of claim 1, further comprising a multiplexer circuit configured to individually electrically connect each of at least a subset of the plurality of conductive loops to the at least one pair of terminals.

3. The apparatus of claim 2, wherein the multiplexer circuit is configured to sequentially provide the voltage signal having the magnitude proportional to the strength of the magnetic field passing through each of at least a subset of the plurality of conductive loops to the at least one pair of terminals.

4. The apparatus of claim 1, wherein the at least one pair of terminals comprises a plurality of pairs of terminals configured to simultaneously provide the voltage signal having the magnitude proportional to the strength of the magnetic field passing through each of at least a subset of the plurality of conductive loops.

5. The apparatus of claim 1, wherein the plurality of conductive loops are arranged in an array.

6. The apparatus of claim 1, wherein a first subset of the plurality of conductive loops overlaps a second subset of the plurality of conductive loops.

7. The apparatus of claim 1, wherein at least a first subset of the plurality of conductive loops have a different size than a second subset of the plurality of conductive loops.

8. The apparatus of claim 1, wherein each of the plurality of conductive loops are electrically isolated from each other loop of the plurality of conductive loops.

9. A method for sensing magnetic field strength of a wireless charging pad, comprising:

sensing a voltage signal having a magnitude proportional to a strength of a magnetic field passing through each of at least a subset of a plurality of conductive loops;

determining the strength of the magnetic field passing through each of at least the subset of the plurality of conductive loops based at least in part on the voltage signal;

summing the voltage signal from each of at least the subset of the plurality of conductive loops; and

determining a magnetic field strength of the magnetic field intersecting at least the subset of the plurality of conductive loops based at least in part on the summed voltage signals.

10. The method of claim 9, further comprising individually electrically connecting each of at least the subset of the plurality of conductive loops to at least one pair of terminals utilizing a multiplexing circuit.

11. The method of claim 9, wherein the sensing comprises sequentially sensing the voltage signal having the magnitude proportional to the strength of the magnetic field passing through each of at least the subset of the plurality of conductive loops.

12. The method of claim 9, wherein the sensing comprises simultaneously sensing the voltage signal having the magnitude proportional to the strength of the magnetic field passing through each of at least the subset of the plurality of conductive loops.

13. The method of claim 9, wherein the plurality of conductive loops are arranged in an array.

14. The method of claim 9, wherein a first subset of the plurality of conductive loops overlaps a second subset of the plurality of conductive loops.

15. The method of claim 9, wherein at least a first subset of the plurality of conductive loops have a different size than a second subset of the plurality of conductive loops.

16. The method of claim 9, wherein each of the plurality of conductive loops are electrically isolated from each other loop of the plurality of conductive loops.

17. An apparatus for sensing magnetic field strength of a wireless charging pad, comprising:

a plurality of means for sensing a strength of a magnetic field passing through each of a plurality of predefined spatial areas;

means for providing a voltage signal having a magnitude proportional to the strength of the magnetic field passing through one or more of the plurality of means for sensing, wherein the means for providing are configured to be electrically connected to one or more of the plurality of means for sensing;

means for summing the voltage signal from each of the plurality of means for sensing; and

means for generating a magnetic field strength of the magnetic field intersecting the plurality of means for sensing based at least in part on the summed voltage signals.

18. The apparatus of claim 17, further comprising means for individually electrically connecting each of at least a subset of the plurality of means for sensing to the means for providing the voltage.

19. The apparatus of claim 17, wherein the means for providing the voltage is configured to sequentially provide the voltage signal having the magnitude proportional to the strength of the magnetic field passing through each of at least a subset of the plurality of predefined spatial areas.

20. The apparatus of claim 17, wherein the means for providing the voltage comprises a plurality of pairs of terminals configured to simultaneously provide the voltage signal having the magnitude proportional to the strength of the magnetic field passing through each of at least a subset of the plurality of predefined areas.