Magnetic field sensors having virtual signals

Patent metadata

Field	Value
Publication number	US-10598739-B2
Application number	US-201916290017-A
Country	US
Kind code	B2
Filing date	Mar 1, 2019
Priority date	Jun 18, 2018
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

A magnetic field sensor includes a plurality of magnetic field sensing elements configured to generate at least two measured magnetic field signals indicative of a magnetic field affected by an object and having a first predetermined phase difference with respect to each other and a controller responsive to the at least two measured magnetic field signals. The controller is configured to generate at least one virtual magnetic field signal having a second predetermined phase difference with respect to at least one of the measured magnetic field signals. In embodiments, the virtual magnetic field signal has the second predetermined phase difference with respect to each of the at least two measured magnetic field signals.

First claim

What is claimed is:

1. A magnetic field sensor, comprising:
a plurality of magnetic field sensing elements configured to generate at least two measured magnetic field signals indicative of a magnetic field affected by an object and having a phase difference with respect to each other; and
a controller responsive to the at least two measured magnetic field signals and configured to generate at least a first virtual quadrature magnetic field signal and at least a second virtual quadrature magnetic field signal having a predetermined phase difference with respect to the first virtual quadrature magnetic field signal.

2. The magnetic field sensor of claim 1 , wherein the predetermined phase difference is 90-degrees.

3. The magnetic field sensor of claim 1 , wherein the first virtual quadrature magnetic field signal is generated by averaging the at least two measured magnetic field signals.

4. The magnetic field sensor of claim 1 , wherein the second virtual quadrature magnetic field signal is generated by determining a difference between the at least two measured magnetic field signals.

5. The magnetic field sensor of claim 1 , wherein an amplitude correction factor is applied to the second virtual quadrature signal, the amplitude correction factor being based upon the phase difference between the at least two measured magnetic field signals.

6. The magnetic field sensor of claim 5 , wherein the amplitude correction factor is programmed into a memory of the magnetic field sensor based upon an expected value of the phase difference between the at least two measured magnetic field signals as characterized at a time of manufacture.

7. The magnetic field sensor of claim 5 , wherein the amplitude correction factor is stored as a look-up table.

8. The magnetic field sensor of claim 5 , wherein the controller is further configured to determine the phase difference between the at least two measured magnetic field signals and use the determined phase difference to select the amplitude correction factor.

9. The magnetic field sensor of claim 1 , wherein the controller is further configured to process the first virtual quadrature magnetic field signal and the second virtual quadrature magnetic field signal according to a mathematical function that characterizes a relationship between the first and second virtual quadrature magnetic field signals in order to generate at least one virtual magnetic field signal having a second predetermined phase difference with respect to at least one of the first and second virtual quadrature magnetic field signals.

10. The magnetic field sensor of claim 1 , wherein the plurality of magnetic field sensing elements comprises one or more Hall effect elements and/or magnetoresistance elements.

11. The magnetic field sensor of claim 1 , wherein the plurality of magnetic field sensing elements comprises at least one first element having a first axis of maximum sensitivity in a first plane and at least one second element having a second axis of maximum sensitivity in a second plane orthogonal to the first plane.

12. The magnetic field sensor of claim 1 , further comprising a back bias magnet to generate the magnetic field and wherein the object comprises a ferromagnetic object.

13. A method comprising:
generating at least two measured magnetic field signals indicative of a magnetic field affected by an object, wherein the at least two measured magnetic field signals have a phase difference with respect to each other; and
processing the at least two measured magnetic field signals to generate at least a first virtual quadrature magnetic field signal and at least a second virtual quadrature magnetic field signal having a predetermined phase difference with respect to the first virtual quadrature magnetic field signal.

14. The method of claim 13 , wherein processing the at least two measured magnetic field signals comprises:
averaging the at least two measured magnetic field signals to generate the first virtual quadrature magnetic field signal.

15. The method of claim 13 , wherein processing the at least two measured magnetic field signals comprises:
determining a difference between the at least two measured magnetic field signals to generate the second virtual quadrature magnetic field signal.

16. The method of claim 13 , wherein processing the at least two measured magnetic field signals comprises:
applying an amplitude correction factor to the second virtual quadrature signal, the amplitude correction factor being based upon the phase difference between the at least two measured magnetic field signals.

17. The method of claim 13 , further comprising processing the first and second virtual quadrature magnetic field signals according to a mathematical function that characterizes a relationship between the first and second virtual quadrature magnetic field signals in order to generate at least one virtual magnetic field signal having a second predetermined phase difference with respect to at least one of the first and second virtual quadrature magnetic field signals.

18. An apparatus comprising:
means for generating at least two measured magnetic field signals indicative of a magnetic field affected by an object, wherein the at least two measured magnetic field signals have a phase difference with respect to each other; and
means for processing the at least two measured magnetic field signals to generate at least a first virtual quadrature magnetic field signal and at least a second virtual quadrature magnetic field signal having a predetermined phase difference with respect to the first virtual quadrature magnetic field signal.

19. The apparatus of claim 18 , wherein the processing means comprises:
means for averaging the at least two measured magnetic field signals to generate the first virtual quadrature magnetic field signal.

20. The apparatus of claim 18 , wherein the processing means comprises:
means for determining a difference between the at least two measured magnetic field signals to generate the second virtual quadrature magnetic field signal.

21. A magnetic field sensor, comprising:
a plurality of magnetic field sensing elements configured to generate at least two measured magnetic field signals indicative of a magnetic field affected by an object and having a first phase difference with respect to each other; and
a controller responsive to the at least two measured magnetic field signals and configured to generate at least one virtual magnetic field signal having a second predetermined phase difference with respect to at least one of the measured magnetic field signals.

22. The magnetic field sensor of claim 21 , wherein the first phase difference is predetermined and is based on a shape of the object and an airgap between the magnetic field sensor and the object.

23. The magnetic field sensor of claim 21 , wherein the second predetermined phase difference is 90 degrees.

24. The magnetic field sensor of claim 21 , wherein the second predetermined phase difference is one or more of 30-degrees, 60-degrees, 90-degrees, 120-degrees, 150-degrees, 36-degrees, 72-degrees, 108-degrees, 144-degrees, 45-degrees, 90-degrees, and 135-degrees.

25. The magnetic field sensor of claim 21 , wherein the controller is configured to generate a plurality of virtual magnetic field signals, each having a phase increment based on a number of intended output commutations, wherein the number of intended output c

Assignees

• Allegro Microsystems Llc

Inventors

• Shoemaker Eric G
• Richards Zachary
• Foletto Andrea

Classifications

• G01R33/07

  Hall effect devices · CPC title

• G01R33/0029 Primary

  Treating the measured signals, e.g. removing offset or noise · CPC title

• G01R33/072 Primary

  Constructional adaptation of the sensor to specific applications · CPC title

• G01R33/0047

  Housings or packaging of magnetic sensors (packaging of semiconductor devices H10W99/00); Holders · CPC title

• G01R33/091

  Constructional adaptation of the sensor to specific applications · CPC title