Angle detection device and electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-2018252511-A1
Application number	US-201615748228-A
Country	US
Kind code	A1
Filing date	May 31, 2016
Priority date	Nov 26, 2015
Publication date	Sep 6, 2018
Grant date	—

Abstract

Included are: a sensor magnet which rotates integrally with a rotating shaft centering on the rotating shaft, and generates a magnetic field for angle detection which is for detecting the angle of rotation; a first sensor and a second sensor each of which is arranged opposite to the sensor magnet at a position separated in angle by 90 degrees on the circumference centered on the rotating shaft, and outputs a signal corresponding to the magnetic field for angle detection; and an angle calculator that calculates a rotation angle by using the signals from the first sensor and the second sensor.

First claim

1 . An angle detection device comprising:
a sensor magnet configured to rotate integrally with a rotating shaft centering on the rotating shaft, and to generate a magnetic field for angle detection that is for detecting the angle of rotation; a first sensor and a second sensor each configured to be arranged at a position separated in angle by 90 degrees on the circumference centered on the rotating shaft, and to output a signal corresponding to the magnetic field for angle detection; and an angle calculator configured to calculate a rotation angle by using the signals from the first sensor and the second sensor.

2 . The angle detection device according to claim 1 ,
wherein the signals outputted by the first sensor and the second sensor according to the magnetic field for angle detection are an angle; and the angle calculator sets the average of the angle outputted by the first sensor and the angle outputted by the second sensor as a rotation angle.

3 . The angle detection device according to claim 1 ,
wherein the signals outputted by the first sensor and the second sensor according to the magnetic field for angle detection are a sine signal and a cosine signal; and the angle calculator sets the average of the angle calculated from the sine signal and the cosine signal which are outputted by the first sensor and the angle calculated from the sine signal and the cosine signal which are outputted by the second sensor, as a rotation angle.

4 . The angle detection device according to claim 1 ,
wherein the signals outputted by the first sensor and the second sensor according to the magnetic field for angle detection are a sine signal and a cosine signal; and the angle calculator sets the average of the angle calculated from the sine signal outputted by the first sensor and the sine signal outputted by the second sensor and the angle calculated from the cosine signal outputted by the first sensor and the cosine signal outputted by the second sensor, as a rotation angle.

5 . The angle detection device according to claim 1 ,
wherein the signals outputted by the first sensor and the second sensor according to the magnetic field for angle detection are a sine signal and a cosine signal; and the angle calculator calculates the rotation angle from a sine signal after correction which is obtained from the sum or the difference of Ks times of the sine signal outputted by the first sensor and Kc times of the cosine signal outputted by the second sensor, and a cosine signal after correction which is obtained from the sum or the difference of Kc times of the cosine signal outputted by the first sensor and Ks times of the sine signal outputted by the second sensor.

6 . The angle detection device according to claim 5 ,
wherein either of gain Ks to be multiplied to the sine signal or gain Kc to be multiplied to the cosine signal is 1; and the other is based on the ratio of (2p+1)th order components (where, p is a natural number) of the sine signal and the cosine signal.

7 . The angle detection device according to claim 5 ,
wherein the angle calculator calculates the rotation angle after multiplying the ratio of amplitude of the fundamental waves of the sine signal after correction and the cosine signal after correction and any of the signals together.

8 . The angle detection device according to claim 1 ,
wherein the signals outputted by the first sensor and the second sensor according to the magnetic field for angle detection are a sine signal and a cosine signal; and the angle calculator calculates the rotation angle from a sine signal after correction which is obtained from the sum of the sine signal outputted by the first sensor and the sine signal outputted by the second sensor, and a cosine signal after correction which is obtained from the sum of the cosine signal outputted by the first sensor and the cosine signal outputted by the second sensor.

9 . The angle detection device according to claim 3 ,
wherein the angle calculator calculates the rotation angle from the sine signal and the sine signal at the position separated by 90 degrees when the cosine signal of one of the sensors fails, or calculates the rotation angle from the cosine signal and the cosine signal at the position separated by 90 degrees when the sine signal of one of the sensors fails.

10 . The angle detection device according to claim 1 ,
wherein the angle calculator calculates a rotation angle after m time correction (where, m is a natural number) by correcting a 4nth order (where, n is a natural number) angle error with respect to the rotation angle calculated by the signals of the first sensor and the second sensor.

11 . The angle detection device according to claim 3 ,
wherein in the angle calculator, at least one of the sine signal, the cosine signal, the sine signal after correction, or the cosine signal after correction, which is used for calculating the rotation angle is one in which a (2q−1)th order (where, q is a natural number) signal error is corrected.

12 . The angle detection device according to claim 11 ,
wherein the angle calculator corrects the signal error by a previous rotation angle value.

13 . The angle detection device according to claim 11 ,
wherein the angle calculator corrects the signal error by an estimated rotation angle based on a previous rotation angle value.

14 . The angle detection device according to claim 1 ,
wherein the angle calculator calculates the rotation angle from output information of the other sensor when one of the sensors fails, and calculates a rotation angle after m time correction (where, m is a natural number) by correcting a 2nth order (where, n is a natural number) angle error with respect to the rotation angle.

15 . An electric power steering apparatus comprising:
the angle detection device as set forth in claim 1 ; and an AC rotary machine configured to generate assist torque that is for assisting driver's steering.

Assignees

• Mitsubishi Electric Corp

Inventors

• Furukawa Akira
• Kawano Yu
• Takizawa Yuji

Classifications

• H02P6/10

  Arrangements for controlling torque ripple, e.g. providing reduced torque ripple · CPC title

• B62D6/10

  characterised by means for sensing {or determining} torque · CPC title

• B62D5/0463

  calculating assisting torque from the motor based on driver input · CPC title

• G01B7/30 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title

• H02P6/16

  Circuit arrangements for detecting position · CPC title