ROTATIONAL ANGLE DETECTION APPARATUS AND ROTATIONAL ANGLE DETECTION METHOD

• US 20190316939A1
• Filed: 04/12/2019
• Published: 10/17/2019
• Est. Priority Date: 04/13/2018
• Status: Active Grant

• Current Assignee: Asahi Kasei Microdevices Corporation (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Microdevices Corporation (Asahi Kasei Corporation)
• Inventors: YAMAMOTO, Takeo, TANAKA, Ryuta, FUKASE, Satoshi, SOGO, Kenta
• Granted Patent: US 11,243,095 B2
• Time in Patent Office: Days
• CPC Class Codes: G01D 3/032 affecting incoming signal, e.g. by averaging; gating undesired signals
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/24476 Signal processing G01D5/2448 - G01D5/24495 take precedence
• CPC Class Codes: G01D 5/24495 using previous values

Abstract

To reduce the error in a rotational angle detected by a rotational angle detection apparatus, provided is a rotational angle detection apparatus that detects a rotational angle of a magnetic field generation source, including a magnetic field detection apparatus that detects magnetic field components in at least two directions, and outputs resulting detection data; a correction value calculating section that calculates correction values for correcting an angle error of the rotational angle, based on a steady-state error that does not depend on rotation of the magnetic field generation source; and an angle computing section that calculates the rotational angle of the magnetic field generation source based on the detection data and the correction values, and outputs an angle signal indicating the rotational angle.

Claims

1. A rotational angle detection apparatus that detects a rotational angle of a magnetic field generation source, comprising:

a magnetic field detection apparatus that detects magnetic field components in at least two directions, and outputs resulting detection data;

a correction value calculating section that calculates correction values for correcting an angle error of the rotational angle, based on a steady-state error that does not depend on rotation of the magnetic field generation source; and

an angle computing section that calculates the rotational angle of the magnetic field generation source based on the detection data and the correction values, and outputs an angle signal indicating the rotational angle.

2. The rotational angle detection apparatus according to claim 1, wherein

the correction value calculating section calculates the correction values based on the steady-state error and the detection data output by the magnetic field detection apparatus for at least two angle states between which the rotational angle of the magnetic field generation source differs.

3. The rotational angle detection apparatus according to claim 2, further comprising:

an angle error calculating section that calculates a reference angle error between a detection angle corresponding to the detection data and a reference angle in a first coordinate system in which the magnetic field generation source rotates, for each rotational angle, wherein

the correction value calculating section calculates the correction values based on an average value of the reference angle error in the at least two angle states.

4. The rotational angle detection apparatus according to claim 3, wherein

the correction value calculating section calculates the correction values based on a result obtained by performing a Fourier transform on the reference angle error, using a detection reference angle obtained by adding the average value of the reference angle error to the reference angle.

5. The rotational angle detection apparatus according to claim 4, wherein

the correction value calculating section calculates the average value of the reference angle error based on the detection data in a number of angle states equal to the number of angle states used to perform the Fourier transform on the reference angle error.

6. The rotational angle detection apparatus according to claim 3, further comprising:

an angle error calculating section that calculates a reference angle error between a detection angle corresponding to the detection data and a reference angle in a first coordinate system, for each rotational angle, wherein

the correction value calculating section calculates the correction values based on a median value of the reference angle error in the at least two angle states.

7. The rotational angle detection apparatus according to claim 1, further comprising:

a first signal processing section that outputs a first signal corresponding to a magnetic field in a first direction detected by the magnetic field detection apparatus;

a second signal processing section that outputs a second signal corresponding to a magnetic field in a second direction detected by the magnetic field detection apparatus; and

a correction processing section that corrects the first signal and the second signal output by the first signal processing section and the second signal processing section, based on the correction values.

8. The rotational angle detection apparatus according to claim 1, further comprising:

a first signal processing section that outputs a first signal corresponding to a magnetic field in a first direction detected by the magnetic field detection apparatus; and

a second signal processing section that outputs a second signal corresponding to a magnetic field in a second direction detected by the magnetic field detection apparatus, wherein

the angle computing section calculates the rotational angle based on the correction values and the first signal and the second signal output by the first signal processing section and the second signal processing section.

9. The rotational angle detection apparatus according to claim 3, further comprising:

a first signal processing section that outputs a first signal corresponding to a magnetic field in a first direction detected by the magnetic field detection apparatus; and

a second signal processing section that outputs a second signal corresponding to a magnetic field in a second direction detected by the magnetic field detection apparatus, wherein

the correction value calculating section calculates the correction values based on results of a Fourier transform performed on the first signal output by the first signal processing section and the second signal output by the second signal processing section, using a detection reference angle obtained by adding the average value of the reference angle error to the reference angle.

10. The rotational angle detection apparatus according to claim 9, further comprising:

a correction processing section that corrects the first signal and the second signal output by the first signal processing section and the second signal processing section, based on the correction values, wherein

the angle computing section calculates the rotational angle based on the signals corrected by the correction processing section.

11. The rotational angle detection apparatus according to claim 9, wherein

the correction value calculating section calculates an average value of the reference angle error based on the detection data in a number of angle states equal to the number of angle states used to perform the Fourier transform on the first signal output by the first signal processing section and the second signal output by the second signal processing section.

12. The rotational angle detection apparatus according to claim 3, further comprising:

a first signal processing section that processes a first signal corresponding to a magnetic field in a first direction detected by the magnetic field detection apparatus; and

a second signal processing section that processes a second signal corresponding to a magnetic field in a second direction detected by the magnetic field detection apparatus, wherein

the correction value calculating section calculates the correction values based on results of the Fourier transform performed on the first signal output by the first signal processing section and the second signal output by the second signal processing section using a reference angle in the first coordinate system.

13. The rotational angle detection apparatus according to claim 12, further comprising:

a correction processing section that corrects the first signal and the second signal output by the first signal processing section and the second signal processing section, based on the correction values, wherein

the angle computing section calculates the rotational angle based on the signals corrected by the correction processing section.

14. A rotational angle detection method for detecting a rotational angle of a magnetic field generation source based on magnetic fields detected by a magnetic field detection apparatus that detects magnetic fields in at least two directions, comprising:

calculating correction values for correcting an angle error of the rotational angle, based on a steady-state error that does not depend on rotation of the magnetic field generation source; and

calculating the rotational angle of the magnetic field generation source based on detection data of the magnetic field detection apparatus and the correction values, and outputting an angle signal indicating the rotational angle.

15. A rotational angle detection apparatus comprising:

a data acquiring section that acquires detection data in a magnetic field detection apparatus, in at least two angle states between which a rotational angle of the magnetic field generation source differs; and

a correction value calculating section that calculates correction values for correcting an angle error of the rotational angle corresponding to a difference between a first coordinate system in which the magnetic field generation source rotates and a second coordinate system of the magnetic field detection apparatus, based on the detection data in the at least two angle states and a steady-state error of the rotational angle corresponding to the difference between the first coordinate system and the second coordinate system.