WO2024143256A1 - 角度検出装置 - Google Patents

角度検出装置 Download PDF

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Publication number
WO2024143256A1
WO2024143256A1 PCT/JP2023/046355 JP2023046355W WO2024143256A1 WO 2024143256 A1 WO2024143256 A1 WO 2024143256A1 JP 2023046355 W JP2023046355 W JP 2023046355W WO 2024143256 A1 WO2024143256 A1 WO 2024143256A1
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magnet
angle
signal
section
pole pair
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French (fr)
Japanese (ja)
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周平 村瀬
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Nidec Corp
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Nidec Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/16—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance

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  • Patent Document 1 discloses a method for estimating the rotational position of a motor with high accuracy using a set of a multi-pole pair magnet and at least three magnetic sensors, and a set of a single pole pair magnet and two or three magnetic sensors.
  • Patent Document 1 requires at least five magnetic sensors to estimate the rotational position of the motor with high accuracy. Therefore, there is a demand for the development of an angle detection device that can reduce the number of magnetic sensors required to estimate the rotational position, thereby reducing costs.
  • One aspect of the angle detection device of the present invention includes a first magnet that rotates in synchronization with a rotating body and has two or more pole pairs, a second magnet that rotates in synchronization with the rotating body and has one pole pair, three first magnetic sensors that face the first magnet and are arranged at predetermined intervals in the circumferential direction of the first magnet, one second magnetic sensor that faces the second magnet, and a signal processing device that calculates the absolute angle of the rotating body based on a composite signal that is the sum of the output signals of the three first magnetic sensors and an output signal of the second magnetic sensor, where the output signals of the three first magnetic sensors have a phase difference of 120 degrees in electrical angle from each other, and the phase difference between the composite signal and the output signal of the second magnetic sensor is 90 degrees in mechanical angle.
  • the above aspect of the present invention makes it possible to provide an angle detection device that can reduce costs by reducing the number of magnetic sensors required to calculate the absolute angle of a rotating body to four, compared to the technology of Patent Document 1.
  • FIG. 1 is a diagram illustrating a schematic configuration of an angle detection device according to the present embodiment.
  • FIG. 2 is a flowchart showing the learning process executed by the processing unit.
  • FIG. 3 is an explanatory diagram regarding learning data acquired by the learning process.
  • FIG. 4 is an enlarged view of the first sensor signals Hu, Hv, and Hw included in one pole pair region.
  • FIG. 5 is a flowchart showing the angle calculation process executed by the processing unit.
  • FIG. 6 is a diagram showing a first modified example.
  • FIG. 7 is a diagram showing a second modified example.
  • FIG. 8 is a diagram showing a third modified example.
  • the angle detection device 100 is a device for detecting the absolute angle of a rotating body (not shown).
  • the rotating body is a rotor shaft of a motor such as a three-phase brushless DC motor.
  • the angle detection device 100 includes a first magnet 10, a second magnet 20, three first magnetic sensors 30, 40, and 50, one second magnetic sensor 60, and a signal processing device 70.
  • the first magnet 10 is a plate-shaped magnet having a ring shape.
  • the second magnet 20 is a plate-shaped magnet having a disk shape, and is arranged inside the first magnet 10.
  • the cross section perpendicular to the circumferential direction of the first magnet 10 is, for example, rectangular.
  • the cross section perpendicular to the circumferential direction of the first magnet 10 may be circular or elliptical.
  • the first magnet 10 and the second magnet 20 are arranged concentrically.
  • the second magnet 20 may be a plate-shaped magnet having a ring shape. In this case, since an axial rotating body such as a rotor shaft can be inserted into the second magnet 20, the second magnet 20 can be easily attached to the rotating body together with the first magnet 10.
  • the angle detection device 100 includes a circuit board that faces the first magnet 10 and the second magnet 20, and the first magnetic sensors 30, 40, and 50, the second magnetic sensor 60, and the signal processing device 70 are arranged on the circuit board.
  • the first magnetic sensors 30, 40, and 50 are arranged on the circuit board facing the first magnet 10 and at a predetermined interval in the circumferential direction of the first magnet 10.
  • the first magnetic sensors 30, 40, and 50 are TMR (Tunnel magnetoresistance effect) sensors, Hall elements, or linear Hall ICs.
  • the first magnetic sensors 30, 40, and 50 each output an analog signal whose electrical signal varies according to the magnetic field strength. If the number of pole pairs of the first magnet 10 is N, one electrical angle cycle of each analog signal corresponds to 1/N of one mechanical angle cycle. In this embodiment, since the number of pole pairs N of the first magnet 10 is "4", one electrical angle cycle of each analog signal corresponds to 1/4 of one mechanical angle cycle, or 90 degrees in mechanical angle.
  • the output signal of the second magnetic sensor 60 may be referred to as the second sensor signal.
  • the second magnetic sensor 60 outputs a second sensor signal HB2 to the signal processing device 70.
  • the position of the second magnetic sensor 60 is a position where the phase difference between the composite signal HB1, which is the sum of the first sensor signals Hu, Hv, and Hw, and the second sensor signal HB2 is 90 degrees in mechanical angle.
  • the signal processing device 70 is a device that processes the output signals of the first magnetic sensors 30, 40, and 50 and the output signal of the second magnetic sensor 60. Specifically, the signal processing device 70 calculates the absolute angle of the rotating body based on a composite signal HB1, which is the sum of the first sensor signals Hu, Hv, and Hw, and the second sensor signal HB2.
  • the signal processing device 70 includes a processing unit 71 and a memory unit 72.
  • FIG. 2 is a flowchart showing the learning process executed by the processing unit 71.
  • the processing unit 71 executes the learning process shown in FIG. 2 when the power of the angle detection device 100 is turned on for the first time before the angle detection device 100 is shipped from the manufacturing factory.
  • one electrical angle cycle of the second sensor signal HB2 corresponds to one mechanical angle cycle.
  • the period from time t1 to time t9 corresponds to one mechanical angle cycle.
  • one electrical angle cycle of each of the first sensor signals Hu, Hv, and Hw corresponds to 1/4 of one mechanical angle cycle, i.e., 90 degrees in mechanical angle.
  • the period from time t1 to time t3, the period from time t3 to time t5, the period from time t5 to time t7, and the period from time t7 to time t9 each correspond to 90 degrees in mechanical angle.
  • the first sensor signals Hu, Hv, and Hw have a phase difference of 120 degrees in electrical angle from each other.
  • the processing unit 71 calculates a composite signal HB1, which is the sum of the first sensor signals Hu, Hv, and Hw (step S2). Since the first magnetic sensors 30, 40, and 50 each detect not only the magnetic flux of the first magnet 10 but also the magnetic flux of the second magnet 20, the first sensor signals Hu, Hv, and Hw each contain not only the magnetic flux component of the first magnet 10 but also the magnetic flux component of the second magnet 20.
  • the first sensor signal Hu is expressed by the following formula (1):
  • a ⁇ sin(N ⁇ ) is the magnetic flux component of the first magnet 10 contained in the first sensor signal Hu
  • B0 ⁇ sin ⁇ is the magnetic flux component of the second magnet 20 contained in the first sensor signal Hu.
  • Hu A sin(N ⁇ ) + B sin ⁇ ... (1)
  • the first sensor signal Hv is expressed by the following formula (2):
  • a ⁇ sin ⁇ N ⁇ ( ⁇ - ⁇ ) ⁇ is the magnetic flux component of the first magnet 10 contained in the first sensor signal Hv
  • B0 ⁇ sin( ⁇ - ⁇ ) is the magnetic flux component of the second magnet 20 contained in the first sensor signal Hv.
  • Hv A sin ⁇ N ( ⁇ - ⁇ ) ⁇ + B0 sin( ⁇ - ⁇ ) ...
  • the composite signal HB1 which is the sum of the first sensor signals Hu, Hv, and Hw, is a signal that includes only the magnetic flux component of the second magnet 20.
  • one electrical angle period of the composite signal HB1 corresponds to one mechanical angle period.
  • the second magnetic sensor 60 is disposed at a position where the phase difference between the composite signal HB1 and the second sensor signal HB2 is 90 degrees in mechanical angle. That is, the phase difference between the composite signal HB1 and the second sensor signal HB2 is 90 degrees in mechanical angle. Therefore, the second sensor signal HB2 output from the second magnetic sensor 60 is expressed by the following formula (7).
  • HB2 B2 ⁇ cos ⁇ ... (7)
  • the processing unit 71 divides one mechanical angle cycle into four pole pair regions linked to pole pair numbers representing the pole pair positions of each of the four pole pairs of the first magnet 10, further divides each of the four pole pair regions into multiple sections, and links each of the multiple sections to a segment number representing the rotational position of the rotating body (step S4).
  • step S4 will be specifically explained below. Note that since the contents of the processing of step S4 are disclosed in Japanese Patent No. 6233532, the processing of step S4 will be briefly explained below. Please refer to Japanese Patent No. 6233532 for details of the processing contents.
  • the processing unit 71 recognizes, among the zero crossing points of the first sensor signal Hu, the zero crossing point obtained at the sampling timing (time t3) when the mechanical angle is 90 degrees as the start point of the pole pair area linked to pole pair number "1".
  • the processing unit 71 also recognizes, among the zero crossing points of the first sensor signal Hu, the zero crossing point obtained at the sampling timing (time t5) when the mechanical angle is 180 degrees as the end point of the pole pair area linked to pole pair number "1". In other words, the processing unit 71 determines the section between the zero crossing point obtained at time t3 and the zero crossing point obtained at time t5 as the pole pair area linked to pole pair number "1".
  • the processing unit 71 recognizes, among the zero crossing points of the first sensor signal Hu, the zero crossing point obtained at the sampling timing (time t5) when the mechanical angle is 180 degrees as the start point of the pole pair area associated with pole pair number "2". Furthermore, the processing unit 71 recognizes, among the zero crossing points of the first sensor signal Hu, the zero crossing point obtained at the sampling timing (time t7) when the mechanical angle is 270 degrees as the end point of the pole pair area associated with pole pair number "2". In other words, the processing unit 71 determines the section between the zero crossing point obtained at time t5 and the zero crossing point obtained at time t7 as the pole pair area associated with pole pair number "2".
  • the processing unit 71 recognizes, among the zero crossing points of the first sensor signal Hu, the zero crossing point obtained at the sampling timing (time t7) when the mechanical angle is 270 degrees as the start point of the pole pair area linked to pole pair number "3".
  • the processing unit 71 also recognizes, among the zero crossing points of the first sensor signal Hu, the zero crossing point obtained at the sampling timing (time t9) when the mechanical angle is 360 degrees as the end point of the pole pair area linked to pole pair number "3". In other words, the processing unit 71 determines the section between the zero crossing point obtained at time t7 and the zero crossing point obtained at time t9 as the pole pair area linked to pole pair number "3".
  • FIG. 4 is an enlarged view of the first sensor signals Hu, Hv, and Hw included in one pole pair region shown in FIG. 3.
  • the reference value (reference signal level) of the amplitude is "0."
  • the digital value of the amplitude that is a positive value represents, as an example, the digital value of the magnetic field strength of the north pole.
  • the digital value of the amplitude that is a negative value represents, as an example, the digital value of the magnetic field strength of the south pole.
  • the processing unit 71 determines the section between zero cross point P1 and intersection point P2 as the section associated with section number "0". The processing unit 71 determines the section between intersection point P2 and zero cross point P3 as the section associated with section number "1". The processing unit 71 determines the section between zero cross point P3 and intersection point P4 as the section associated with section number "2". The processing unit 71 determines the section between intersection point P4 and zero cross point P5 as the section associated with section number "3”. The processing unit 71 determines the section between zero cross point P5 and intersection point P6 as the section associated with section number "4". The processing unit 71 determines the section between intersection point P6 and zero cross point P7 as the section associated with section number "5".
  • segment 0 a segment assigned segment number "0" will be referred to as “segment 0,” and a segment assigned segment number "11” will be referred to as “segment 11.”
  • a linear function ⁇ ( ⁇ x) representing a segment is expressed by the following formula (9):
  • i is a segment number and is an integer from 0 to 47.
  • the linear function ⁇ ( ⁇ x) expressed by the following formula (9) may be referred to as an angle estimation formula.
  • ⁇ ( ⁇ x) k[i] ⁇ x+ ⁇ res[i] ... (9)
  • k[i] is a coefficient called a normalization coefficient.
  • k[i] is a coefficient that represents the slope of the i-th segment.
  • the normalization coefficient k[i] is expressed by the following formula (10).
  • ⁇ Xnorm[i] is the deviation of the digital value between the start point and the end point of the i-th segment.
  • ⁇ Xnorm[i] of the segment corresponding to the 0th section is the deviation of the digital value between the zero cross point P1 and the intersection point P2.
  • ⁇ Xnorm[i] of the segment corresponding to the 1st section is the deviation of the digital value between the intersection point P2 and the zero cross point P3.
  • k[i] ⁇ norm[i]/ ⁇ Xnorm[i]... (10)
  • ⁇ norm[i] is the absolute angle deviation between the start point and end point of the i-th segment, and is expressed by the following formula (11).
  • t[i] is the time between the start point and end point of the i-th segment
  • t[0] is the time between the start point and end point of the 0-th segment
  • t[47] is the time between the start point and end point of the 47-th segment.
  • t[0] is the time between the zero crossing point P1 and the intersection point P2.
  • ⁇ norm[i] ⁇ t[i]/(t[0]+...+t[47]) ⁇ 360[degM]...(11)
  • ⁇ res[i] is a constant (the intercept of the linear function ⁇ ( ⁇ x)) called the angle reset value of the i-th segment.
  • the angle reset value ⁇ res[i] is expressed by the following equation (12).
  • the segment number "i” is any of "1” to "47”
  • the processing unit 71 acquires the correspondence between the pole pair numbers, section numbers, and segment numbers, the characteristic data of each section, and the angle estimation formula of each segment as learning data.
  • the characteristic data of each section is the magnitude relationship and positive/negative signs of the digital values of the first sensor signals Hu, Hv, and Hw included in each section.
  • the normalization coefficient k[i] and the angle reset value ⁇ res[i] that constitute the angle estimation formula of each segment are acquired as learning data.
  • the processing unit 71 determines the pole pair number corresponding to the current value of the absolute angle ⁇ as the initial position of the rotating body based on the learning data stored in the memory unit 72 (step S14). For example, assume that a value in the range of 90° to 179° has been calculated as the current value of the absolute angle ⁇ . As described above, in the learning data, the pole pair number "1" is associated with absolute angles ⁇ from 90° to 179° in the mechanical angle time series data. Therefore, when a value in the range of 90° to 179° is calculated as the current value of the absolute angle ⁇ , the processing unit 71 determines the pole pair number "1" corresponding to the current value of the absolute angle ⁇ as the initial position of the rotating body.
  • the first magnet 10 and the second magnet 20 are different magnets.
  • the first magnet 10 and the second magnet 20 may be a single magnet.
  • the single magnet has a first magnetization pattern in which there are two or more pole pairs, and a second magnetization pattern in which there is one pole pair. A portion of the first magnetization pattern corresponds to the first magnet 10, and a portion of the second magnetization pattern corresponds to the second magnet 20.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
PCT/JP2023/046355 2022-12-28 2023-12-25 角度検出装置 Ceased WO2024143256A1 (ja)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001264112A (ja) * 2000-03-14 2001-09-26 Hitachi Metals Ltd エンコーダー、ｍｒセンサーおよびパワーステアリング装置
US20110273169A1 (en) * 2006-01-12 2011-11-10 Timken Us Corporation Magnetic sensor with high and low resolution tracks
JP2012215415A (ja) * 2011-03-31 2012-11-08 Oriental Motor Co Ltd アブソリュートエンコーダ装置及びモータ
JP2016161441A (ja) * 2015-03-03 2016-09-05 株式会社ミツトヨ 位相調整器及びエンコーダ
JP2017181235A (ja) * 2016-03-30 2017-10-05 日本電産サンキョー株式会社 モータシステム
US20170322014A1 (en) * 2016-05-04 2017-11-09 Research & Business Foundation Sungkyunkwan University Angle determinating method using encoder signal with noise suppression, adjusting method for output signal of encoder and absolute encoder

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001264112A (ja) * 2000-03-14 2001-09-26 Hitachi Metals Ltd エンコーダー、ｍｒセンサーおよびパワーステアリング装置
US20110273169A1 (en) * 2006-01-12 2011-11-10 Timken Us Corporation Magnetic sensor with high and low resolution tracks
JP2012215415A (ja) * 2011-03-31 2012-11-08 Oriental Motor Co Ltd アブソリュートエンコーダ装置及びモータ
JP2016161441A (ja) * 2015-03-03 2016-09-05 株式会社ミツトヨ 位相調整器及びエンコーダ
JP2017181235A (ja) * 2016-03-30 2017-10-05 日本電産サンキョー株式会社 モータシステム
US20170322014A1 (en) * 2016-05-04 2017-11-09 Research & Business Foundation Sungkyunkwan University Angle determinating method using encoder signal with noise suppression, adjusting method for output signal of encoder and absolute encoder

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