Angle sensor and angle sensor system

Patent metadata

Field	Value
Publication number	US-2020309871-A1
Application number	US-202016901580-A
Country	US
Kind code	A1
Filing date	Jun 15, 2020
Priority date	Sep 30, 2016
Publication date	Oct 1, 2020
Grant date	—

Abstract

An angle sensor includes first and second detection units and an angle detection unit. Each of the first and second detection units generates two detection signals. The first and second detection units are arranged in a positional relationship that establishes predetermined phase relationships among the detection signals they generate. The angle detection unit includes first and second computing circuits and an angle computing unit. The first and second computing circuits generate first and second signals in each of which an error component corresponding to a fifth harmonic contained in the detection signals is reduced. The angle computing unit calculates a detected angle value on the basis of the first and second signals. The angle computing unit performs correction processing for reducing an error occurring in the detected angle value due to an error component corresponding to a third harmonic contained in the detection signals.

First claim

What is claimed is:

1 . An angle sensor for generating a detected angle value, the detected angle value having a correspondence with an angle that a direction of a rotating magnetic field in a reference position forms with respect to a reference direction,
the angle sensor comprising:
a first detection circuit and a second detection circuit configured to each detect the rotating magnetic field and each generate two detection signals; and
a processor configured to calculate the detected angle value based on the two detection signals generated by the first detection circuit and the two detection signals generated by the second detection circuit, wherein
the first detection circuit generates, as the two detection signals, a first detection signal and a second detection signal, each of the first and second detection signals corresponding to a first angle that the direction of the rotating magnetic field in a first position forms with respect to a first direction;
the second detection circuit generates, as the two detection signals, a third detection signal and a fourth detection signal, each of the third and fourth detection signals corresponding to a second angle that the direction of the rotating magnetic field in a second position forms with respect to a second direction;
the first and second detection circuit are arranged in a predetermined positional relationship such that a high-order harmonic contained in the first detection signal and a high-order harmonic contained in the third detection signal are canceled each other out,
and that a high-order harmonic contained in the second detection signal and a high-order harmonic contained in the fourth detection signal are canceled each other out; and
the processor performs correction processing by which an error occurring in the detected angle value due to a lower-order harmonic contained in each of the first to fourth detection signals is reduced relative to a case where the correction processing is not performed.

2 . The angle sensor according to claim 1 , wherein the positional relationship between the first detection circuit and the second detection circuit is such that the first position and the second position are different from each other so that the direction of the rotating magnetic field in the first position and the direction of the rotating magnetic field in the second position are different from each other.

3 . The angle sensor according to claim 1 , wherein the positional relationship between the first detection circuit and the second detection circuit is such that the first direction and the second direction are different from each other while the direction of the rotating magnetic field in the first position and the direction of the rotating magnetic field in the second position are same.

4 . The angle sensor according to claim 1 , wherein
each of the first to fourth detection signals contains an ideal component that varies periodically so as to trace an ideal sinusoidal curve, when the direction of the rotating magnetic field varies with a predetermined period, and the phase difference between the ideal components of the first and second detection signals and the phase difference between the ideal components of the third and fourth detection signals are both 90°.

5 . The angle sensor according to claim 1 , wherein the first and second detection circuits include first to fourth magnetic detection elements, which generate the first to fourth detection signals, respectively.

6 . The angle sensor according to claim 5 , wherein at least one of the first to fourth magnetic detection elements includes at least one magnetoresistance element.

7 . The angle sensor according to claim 6 , wherein the at least one magnetoresistance element includes a magnetization pinned layer whose magnetization direction is pinned, a free layer whose magnetization direction varies depending on the direction of the rotating magnetic field, and a nonmagnetic layer located between the magnetization pinned layer and the free layer.

8 . The angle sensor according to claim 1 , wherein
each of the first to fourth detection signals contains an ideal component that varies periodically so as to trace an ideal sinusoidal curve, when the direction of the rotating magnetic field varies with a predetermined period, the high-order harmonic is a fifth harmonic of the ideal component, and the lower-order harmonic is a third harmonic of the ideal component.

9 . The angle sensor according to claim 1 , wherein the processor is a computer or an application-specific integrated circuit.

10 . An angle sensor for generating a detected angle value, the detected angle value having a correspondence with an angle that a direction of a rotating magnetic field in a reference position forms with respect to a reference direction,
the angle sensor comprising:
a first detection circuit configured to generate a first detection signal and a second detection signal, each of the first and second detection signals corresponding to a first angle that the direction of the rotating magnetic field in a first position forms with respect to a first direction;
a second detection circuit configured to generate a third detection signal and a fourth detection signal, each of the third and fourth detection signals corresponding to a second angle that the direction of the rotating magnetic field in a second position forms with respect to a second direction, the second detection circuit being arranged in a positional relationship, relative to the first detection circuit, that establishes a first phase relationship between the first and third detection signals, in which an n-th harmonic contained in the first detection signal and an n-th harmonic contained in the third detection signal are canceled each other out, and a second phase relationship between the second and fourth detection signals, in which an n-th harmonic contained in the second detection signal and an n-th harmonic contained in the fourth detection signal are canceled each other out; and
a processor configured to calculate the detected angle value on the basis of the first to fourth detection signals, and to perform correction processing by which an error occurring in the detected angle value due to an m-th harmonic which is a lower-order harmonic than the n-th harmonic contained in each of the first to fourth detection signals is reduced relative to the case where the correction processing is not performed.

11 . An angle sensor for generating a detected angle value, the detected angle value having a correspondence with an angle that a direction of a rotating magnetic field in a reference position forms with respect to a reference direction,
the angle sensor comprising:
a first detection circuit configured to generate a first detection signal and a second detection signal, each of the first and second detection signals corresponding to a first angle that the direction of the rotating magnetic field in a first position forms with respect to a first direction;
a second detection circuit configured to generate a third detection signal and a fourth detection signal, each of the third and fourth detection signals corresponding to a second angle that the direction of the rotating magnetic field in a second position forms with respect to a second direction; and
a processor, wherein
when the direction of the rotating magnetic field varies with a predetermined period, each of the first to fourth detection signals contains an ideal component, a first error component, and a second error component,
the ideal component varies periodically so as to trace an ideal sinusoidal curve,
the first error componen

Assignees

• Tdk Corp

Inventors

• Watanabe Kazuya
• Uchida Keisuke
• Hirabayashi Hiraku

Classifications

• G01R33/093 Primary

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• G01R33/098

  comprising tunnel junctions, e.g. tunnel magnetoresistance sensors · CPC title

• G01D18/004

  Continuous recalibration · CPC title

• B60L3/0038

  relating to sensors · CPC title

• G01D5/24495

  using previous values · CPC title