JP2012005233A - Controller of linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an absolute position of a needle without using an optical absolute encoder.SOLUTION: A controller includes: a first magnet portion having a plurality of first magnets where N poles and S poles are alternately arranged in an arranging direction at equal intervals; a first magnetic sensor which is disposed in an armature in a manner to face the first magnet portion, detects a magnetic field generated by the first magnet, and outputs a signal corresponding to the detected magnetic field; a second magnet portion which has a plurality of second magnets which uniquely identify sections obtained by dividing a movable range of the needle in the arranging direction into a plurality of sections and which are arranged in the arranging direction at the equal intervals; a second magnetic sensor which is disposed in the armature in a manner to face the second magnet portion, and outputs a signal corresponding to the magnetic flux density of a magnetic field generated by the second magnet; and a position calculating portion calculating a position of the needle based on the section detected from the signal which the second magnetic sensor outputs and on an electric angle calculated from the signal which the first magnetic sensor outputs.

Description

  The present invention relates to a control device for a linear motor.

  In the position detection of the mover provided in the linear motor, if information on the relative position (absolute position) with respect to a predetermined origin is required, an absolute encoder that detects the position of the mover is used. For the absolute encoder, for example, an optical sensor as described in Patent Document 1 is used.

JP 2005-12963 A

  However, in an optical absolute encoder, a linear scale marked with a scale read by a sensor is expensive because a high technique is required to form the scale. For this reason, the linear motor device using an optical absolute encoder has a problem of becoming expensive.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a control device that detects the absolute position of a mover in a linear motor without using an optical absolute encoder.

  In order to solve the above problem, the present invention includes a driving magnet unit including a plurality of driving magnets in which N poles and S poles are alternately arranged at equal intervals, and an armature including a plurality of coils. And either one of the armature or the driving magnet unit becomes a mover, and the mover generates a magnetic field generated by passing current through a plurality of coils provided in the armature, and the drive magnet. Is a linear motor control device that linearly moves in the arrangement direction in which the driving magnets are arranged by a magnetic field generated by the magnetic field, and N poles and S poles are alternately arranged in the arrangement direction at equal intervals. A first magnet unit including a plurality of first magnets, and a first magnetic sensor provided in the armature so as to face the first magnet unit, wherein the first magnet generates the first magnet unit. Output a signal corresponding to the detected magnetic field. A magnetic sensor, an electrical angle calculation unit that calculates an electrical angle based on a signal received from the first magnetic sensor, and a section in which the movable range of the movable element in the arrangement direction is divided into a plurality of sections. A plurality of second magnets, a second magnet part comprising a plurality of second magnets arranged at equal intervals in the arrangement direction, and the armature facing the second magnet part A second magnetic sensor provided for outputting a signal corresponding to the magnetic flux density of the magnetic field generated by the second magnet, and the second magnetic sensor received from the second magnetic sensor Based on a section detection unit that detects the section where the armature is located based on a signal, a section detected by the section detection unit, and an electrical angle calculated by the electrical angle calculation unit, the movable range Calculate the position of the mover at A control system for a linear motor comprising: a position calculating unit that.

  According to the present invention, in the linear motor, the absolute position of the mover relative to the stator can be detected without using an optical absolute encoder.

It is the schematic which shows the linear motor apparatus which comprises the control apparatus in 1st Embodiment. It is a perspective view which shows the principle of MR sensor in the same embodiment. It is a perspective view of the linear motor in the same embodiment. It is a front view of the linear motor in the embodiment. It is a figure which shows sectional drawing along the moving direction of the needle | mover in the same embodiment. It is a schematic diagram which shows the relative position of MR sensor and a coil in the same embodiment, and the drive magnet 24, and the relative position of a Hall sensor and a scale magnet. It is a schematic block diagram which shows the structure of the control apparatus in the same embodiment, a stator, and a needle | mover. In the embodiment, an example of the relationship among the magnetic pole position θ of the armature with respect to the driving magnet, the electrical angle α calculated by the electrical angle calculation unit, the signal output from the MR sensor, and the voltage applied to the coil. It is a graph to show. It is a figure for demonstrating an example in which the control apparatus in the embodiment calculates the position of a needle | mover. It is a figure for demonstrating an example in which the control apparatus in 2nd Embodiment calculates the position of a needle | mover. It is a figure which shows the linear motor apparatus of a modification.

  Hereinafter, a control device according to an embodiment of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic diagram showing a linear motor device 1 including a control device 10 according to the first embodiment of the present invention. As shown in the figure, the linear motor device 1 includes a control device 10 and a linear motor 20.
The control device 10 is a device that controls the linear motor 20 by driving it. The linear motor 20 includes a long stator 21, a mover 25 that moves on the stator 21, and a pair of guide devices 22 and 22 for assembling the stator 21 and the mover 25.

  The guide device 22 includes, for example, a track rail 23 and a slide block 26 assembled via a ball. The track rail 23 of the guide device 22 is fixed to the base 54 of the stator 21, and the slide block 26 of the guide device 22 is fixed to the mover 25. Thereby, the mover 25 is freely guided along the track rail 23 on the stator 21.

  The stator 21 includes a plurality of driving magnets 24 arranged between the pair of track rails 23 and 23. The plurality of drive magnets 24 are arranged so that the N-pole and S-pole magnetic poles alternate in the moving direction of the mover 25 (hereinafter referred to as the moving direction). In addition, each drive magnet 24 has the same length in the moving direction, and a constant thrust can be obtained regardless of the position of the mover 25.

A plurality of scale magnets 31 for identifying a section where the mover 25 is positioned on the stator 21 are attached to the side wall of the base 54. The section identified by the scale magnet 31 is a section obtained by equally dividing the movable range of the mover 25 in the movement direction. Each of the plurality of scale magnets 31 is associated with each section.
Further, the plurality of scale magnets 31 are arranged in parallel to the arrangement direction of the drive magnets 24, that is, in the moving direction, with the N and S poles alternately arranged. Here, “parallel to the arrangement direction of the drive magnets 24” means that a straight line connecting the centers of the scale magnets 31 is parallel to a straight line indicating the arrangement direction.
Further, for example, one end of the plurality of scale magnets 31 arranged becomes the origin 30 when the position of the mover 25 is indicated.

The mover 25 includes an armature 60 having a plurality of coils, a table 53 to which a moving object is attached, an MR (Magnetoresitive Elements) sensor 27, and a Hall sensor 29.
The MR sensor 27 detects a magnetic field generated by the driving magnet 24 disposed on the stator 21 and outputs a signal corresponding to the detected magnetic field to the control device 10. Specifically, the MR sensor 27 outputs a signal corresponding to the direction of the magnetic flux line of the magnetic field generated by the driving magnet 24 to the control device 10. The hall sensor 29 is, for example, a level output type hall sensor, and outputs a signal corresponding to the magnetic flux density of the magnetic field generated by the scale magnet 31 to the control device 10. The MR sensor 27 and the hall sensor 29 are attached to the mover 25 so that the distance from the origin 30 is equal in the movement direction.

  FIG. 2 is a perspective view showing the principle of the MR sensor 27 in the present embodiment. As shown in the figure, it is formed of a ferromagnetic thin film metal of an alloy mainly composed of a silicon (Si) or glass substrate 271 and a ferromagnetic metal such as nickel (Ni) or iron (Fe) formed thereon. Magnetoresistive element 272. The resistance value of the magnetoresistive element 272 changes according to the angle formed by the direction of the magnetic flux passing through the magnetoresistive element 272 with respect to the direction of current flow (Y-axis direction).

  The MR sensor 27 is configured so that a plurality of magnetoresistive elements 272 are combined to form two full bridge circuits, and the two full bridge circuits output a signal having a phase difference of 45 °. Thus, an element whose resistance value changes in a specific magnetic field direction is referred to as an AMR (Anisotropic Magneto-Resistance) sensor (reference document: “Vertical type MR sensor technical document”, [online], October 1, 2005, Hamamatsu Photoelectric Co., Ltd., “May 6, 2010 search”, Internet <URL; http://www.hkd.co.jp/technique/img/amr-note1.pdf>).

  Returning to FIG. 1, the control device 10 calculates the position of the mover 25 on the stator 21 based on the signal output from the MR sensor 27 and the signal output from the Hall sensor 29. Moreover, the control apparatus 10 sends an electric current through the some coil which the armature 60 has according to the calculated position of the needle | mover 25 and the position command information input from the outside. Accordingly, the mover 25 is driven along the track rail 23 by the action of the magnetic field generated in the plurality of coils and the magnetic field generated by the driving magnet 24 disposed in the stator 21.

A configuration of the linear motor 20 in the present embodiment will be described with reference to FIGS. 3 and 4.
FIG. 3 is a perspective view of the linear motor 20 in this embodiment (including the cross section of the table 53). FIG. 4 is a front view of the linear motor 20 in the present embodiment.
As described above, in the linear motor 20, the mover 25 is linearly moved relative to the stator 21 having a plurality of plate-like drive magnets 24 magnetized with N or S poles. This is a flat type linear motor. The armature 60 provided in the mover 25 is opposed to the driving magnet 24 via the gap g.

  The plurality of driving magnets 24 described above are arranged in a row in the moving direction on the elongated base 54 of the stator 21. The base 54 includes a bottom wall portion 54a and a pair of side wall portions 54b provided on both sides in the width direction of the bottom wall portion 54a. The plurality of driving magnets 24 described above are attached to the bottom wall portion 54a.

  Each drive magnet 24 has an N pole and an S pole formed on both end faces in a direction (vertical direction in FIG. 4) perpendicular to the moving direction. The plurality of drive magnets 24 are arranged in a state where the magnetic poles are reversed with respect to a pair of adjacent drive magnets 24. Thereby, when the mover 25 moves with respect to the MR sensor 27 attached to the mover 25, the magnetic poles of the N pole and the S pole of the drive magnet 24 are alternately opposed.

  The plurality of scale magnets 31 described above are attached to one side wall 54 b of the base 54. Each of the scale magnets 31 has an N pole and an S pole formed on both end faces in a direction orthogonal to the moving direction (left and right direction in FIG. 4). The plurality of scale magnets 31 are arranged in a state in which the magnetic poles are reversed with respect to a pair of adjacent scale magnets 31. Thereby, when the mover 25 moves with respect to the Hall sensor 29 attached to the mover 25 via the bracket 55, the N pole and the S pole of the scale magnet 31 are alternately opposed to each other. It has become.

  The track rail 23 of the guide device 22 is attached to the upper surface of the side wall 54b of the base 54. As described above, the slide block 26 is slidably assembled to the track rail 23. A plurality of balls are interposed between the track rail 23 and the slide block 26 so as to allow rolling motion (not shown). The slide block 26 is provided with a track-shaped ball circulation path for circulating a plurality of balls. When the slide block 26 slides with respect to the track rail 23, a plurality of balls roll and move between them, and the plurality of balls circulate in the ball circulation path. Thereby, the smooth linear motion of the slide block 26 is attained.

  A table 53 of the mover 25 is attached to the upper surface of the slide block 26 of the guide device 22. The table 53 is made of, for example, a nonmagnetic material such as aluminum, and a moving object is attached to the table 53. An armature 60 is suspended from the lower surface of the table 53. As shown in the front view of FIG. 4, a gap g is provided between the driving magnet 24 and the armature 60. The guide device 22 maintains the clearance g constant even when the armature 60 moves relative to the drive magnet 24.

FIG. 5 is a cross-sectional view taken along the moving direction of the mover 25 in the present embodiment.
An armature 60 is attached to the lower surface of the table 53 via a heat insulating material 63. The armature 60 includes a core 64 made of a magnetic material such as silicon steel, and the above-described plurality of coils, and coils 28u, 28v, and 28w wound around the salient poles 64u, 64v, and 64w of the core 64. . A three-phase alternating current having a phase difference is supplied from the control device 10 to each of the coils 28u, 28v, 28w. After winding the three coils 28u, 28v, 28w around the salient poles 64u, 64v, 64w, the three coils 28u, 28v, 28w are sealed with resin.
A pair of auxiliary cores 67 are attached to the lower surface of the table 53 with the armature 60 interposed therebetween. The auxiliary core 67 is provided to reduce cogging generated in the linear motor 20.

FIG. 6 is a schematic diagram showing the relative positions of the MR sensor 27 and the coils 28u, 28v, 28w and the driving magnet 24 and the relative positions of the Hall sensor 29 and the scale magnet 31 in the present embodiment. FIG.
As described above, on the stator 21, the driving magnet 24 </ b> N disposed on the bottom wall portion 54 a of the base 54 with the N pole facing the MR sensor 27, and the S pole facing the MR sensor 27. The drive magnets 24S arranged in a row are alternately arranged in the movement direction. In the mover 25, the coils 28 u, 28 v, 28 w are arranged in the movement direction so as to face the driving magnet 24 disposed in the stator 21.
The MR sensor 27 is attached at a position passing through the center of each driving magnet 24 and passing on a straight line parallel to the moving direction. As a result, the MR sensor 27 can pass through the position where the magnetic field generated by the drive magnet 24 is strongest.

Further, as described above, in the stator 21, the scale magnet 31 is arranged side by side on the side wall part 54 b of the base 54 so that the magnetic poles of the N pole and the S pole alternate in the moving direction of the base 54. . The hall sensor 29 is disposed at a position facing the central portion of each scale magnet 31 so as to pass through the position where the magnetic field generated by the scale magnet 31 is the strongest.
Further, the length (dimension) of the scale magnet 31 in the moving direction of the base 54 is half of the length of the driving magnet 24 in the moving direction.

FIG. 7 is a schematic block diagram illustrating the configuration of the control device 10, the stator 21, and the mover 25 in the present embodiment. As illustrated, the control device 10 includes a control unit 11, a drive unit 12, an electrical angle calculation unit 13, a section detection unit 14, and a position calculation unit 15.
In addition, the stator 21 includes the scale magnet 31 and the drive magnet 24 as described above. The mover 25 includes coils 28 u, 28 v, 28 w and an MR sensor 27 that are disposed to face the drive magnet 24, and a hall sensor 29.

The control unit 11 moves the mover 25 based on position command information input from the outside, the electrical angle calculated by the electrical angle calculation unit 13, and the position of the mover 25 calculated by the position calculation unit 15. Therefore, a current command value indicating a current value flowing through each of the coils 28u, 28v, 28w is calculated, and the calculated current command value is output to the drive unit 12.
The drive unit 12 is a motor driver that drives the linear motor 20 based on the control of the control unit 11. The drive unit 12 applies a voltage to the coils 28u, 28v, 28w based on the current command value input from the control unit 11.

The electrical angle calculation unit 13 calculates the electrical angle of the armature 60 provided in the mover 25 with respect to the driving magnet 24 based on the two signals input from the MR sensor 27. Here, the two signals input from the MR sensor 27 are a sine wave signal and a cosine wave signal having a phase difference of 45 ° with respect to the sine wave signal. The section detection unit 14 detects a section where the movable element 25 on the stator 21 is positioned on the track rail 23 based on a signal input from the hall sensor 29. For example, in the section detection unit 14, the level of the signal output from the hall sensor 29 and information indicating each section are stored in advance, and information indicating the section corresponding to the level of the input signal is stored. By reading, the section where the mover 25 is located is detected.
The position calculation unit 15 calculates the position of the mover 25 based on the electrical angle calculated by the electrical angle calculation unit 13 and the section detected by the section detection unit 14.

  FIG. 8 shows the magnetic pole position θ of the armature 60 provided in the mover 25 with respect to the driving magnet 24, the electrical angle α calculated by the electrical angle calculator 13, and the MR sensor 27 in this embodiment. 2 is a graph showing an example of a relationship between two signals and voltages applied to coils 28u, 28v, and 28w. In the figure, the horizontal axis indicates the magnetic pole position θ and the electrical angle α with respect to the driving magnet 24 of the armature 60, and the vertical axis indicates the sine wave signal Ssin and cosine wave signal Scos output from the MR sensor 27, and the driving unit 12. The voltages Vu, Vv, and Vw applied to the coils 28u, 28v, and 28w are shown. In the vertical axis direction, the sine wave signal Ssin and the cosine wave signal Scos, and the voltages Vu, Vv, and Vw are values normalized by the maximum values.

The MR sensor 27 outputs a sine wave signal Ssin and a cosine wave signal Scos in accordance with the direction of the magnetic flux generated by the opposing drive magnet 24. Further, when the magnetic poles of the opposing driving magnet 24 change in order of N pole, S pole, and N pole, the MR sensor 27 corresponds to two cycles corresponding to the change in the direction of the magnetic flux generated by each of the driving magnets 24. A sine wave signal (Ssin) and a cosine wave signal (Scos) are output. That is, when the armature 60 of the mover 25 is positioned at a magnetic pole position having a phase difference of 180 °, the value of the sine wave signal output from the MR sensor 27 becomes the same value at each magnetic pole position, and the cosine. The value of the wave signal is also the same value.
Further, the electrical angle calculation unit 13 calculates the electrical angle α based on the level of the sine wave signal Ssin and the level of the cosine wave signal Scos. Specifically, the electrical angle calculation unit 13 calculates the electrical angle α by calculating arctan (arc tangent) with respect to (level of the sine wave signal Ssin) / (level of the cosine wave signal Scos).

  The figure also shows excitation patterns corresponding to the coils 28u, 28v, 28w corresponding to the magnetic pole position θ and the electrical angle α. The excitation pattern is a ratio of voltages Vu, Vv, and Vw applied to the coils 28u, 28v, and 28w corresponding to the magnetic pole position θ. Further, the control unit 11 stores the excitation pattern shown in the figure in association with the magnetic pole position. Then, the control unit 11 calculates the magnetic pole position θ from the position calculated by the position calculation unit 15 and the electrical angle calculated by the electrical angle calculation unit 13, and based on the excitation pattern corresponding to the calculated magnetic pole position θ, A current value applied to the coils 28 u, 28 v, 28 w is calculated, and a current command value indicating the calculated current value is output to the drive unit 12.

FIG. 9 is a diagram for explaining an example in which the control device 10 according to the present embodiment calculates the position of the mover 25. In FIG. 9A, the drive magnet 24, the scale magnet 31 (31-N1, 31-S1,...), And the levels of signals output from the MR sensor 27 and the Hall sensor 29 are shown in association with each other. Has been.
9A shows the arrangement of the scale magnets 31 (31-N1, 31-S1,...) And the level of the signal output from the hall sensor 29 in association with each other. In the figure, the horizontal axis indicates the position of the mover 25, and the vertical axis indicates the level of the signal output from the hall sensor 29. FIG. 9A shows a sine wave with respect to the electrical angle calculated by the electrical angle calculation unit 13.
In the figure, the pitch between the magnetic poles of the drive magnet 24 is set to 10 mm, and the pitch between the magnetic poles of the scale magnet 31 is set to 5 mm, which is half of the pitch between the magnetic poles of the drive magnet 24.

  In the same figure, among the magnets for scale 31, the magnets for scale 31-N1, 31-N2, 31-N3, etc., whose magnetic poles on the surface facing the hall sensor 29 are N poles, all have their respective magnetic flux densities. In contrast, the magnetic flux densities are arranged so as to monotonously decrease in order from the origin 30. Further, among the scale magnets 31, the scale magnets 31 -S 1, 31 -S 2, 31 -S 3,... Whose magnetic poles on the surface facing the hall sensor 29 are S poles have the same magnetic flux density. In contrast, the magnetic flux densities are arranged so as to monotonously decrease in order from the origin 30. That is, the scale magnet 31 has a different combination of the polarity of each magnetic pole and the magnetic flux density for each section.

  Further, the electrical angle α in the odd-numbered section from the origin 30 is 0 ° ≦ α ≦ 180 °, and the electrical angle α in the even-numbered section is at a position where 180 ° ≦ α <360 °. (31-N1, 31-S1,...) Are arranged with respect to the drive magnet 24. That is, the position calculation unit 15 treats the electrical angle calculated by the electrical angle calculation unit 13 as 0 ° depending on whether the section indicated by each scale magnet 31 is an odd number or an even number from the origin 30. And the case of handling as 360 ° are distinguished.

  Moreover, FIG.9 (b) is a perspective view which shows the arrangement | sequence of the magnet 31 for a scale (31-N1, 31-S1, ...). As shown, the scale magnets 31 (31-N1, 31-S1,...) Are arranged so that the magnetic poles on the side through which the Hall sensor 29 passes are alternately N and S poles.

  When the MR sensor 27 and the hall sensor 29 are at the position C shown in FIG. 9A, the control device 10 calculates the position of the mover 25 as follows.

The electrical angle calculator 13 calculates the electrical angle α based on the sine wave signal and the cosine wave signal output from the MR sensor 27. At this time, the electrical angle α calculated by the electrical angle calculation unit 13 is 0 ° (or 360 °) as shown in FIG.
The section detection unit 14 detects from the level of the signal output from the hall sensor 29 that the hall sensor 29 is located in the fifth (L = 5) fifth section from the origin 30.

  When the interval detected by the interval detector 14 is an odd number from the origin 30, the position calculator 15 calculates the distance in the moving direction of the MR sensor 27 and the hall sensor 29 from the origin 30 using the following equation (1). To do. Further, when the section detected by the section detection unit 14 is an even number from the origin 30, the position calculation unit 15 calculates the distance using the following equation (2). Here, L indicates the number of the section detected by the section detection unit 14 from the origin 30.

(Distance from origin) = (Magnetic pole pitch of drive magnet 24) ÷ 2 × (L−1)
+ (Magnetic pole pitch of driving magnet 24) × (electrical angle α) ÷ 360 (1)
(Distance from origin) = (Magnetic pole pitch of drive magnet 24) ÷ 2 × (L−2)
+ (Magnetic pole pitch of drive magnet 24) × (electrical angle α) ÷ 360 (2)

Therefore, the position calculation unit 15 calculates the distance from the origin 30 at the position C in FIG. 9A as 20 mm as shown in the following equation (3).
(Distance at position C) = 10 ÷ 2 × (5-1) + 10 × 0 ÷ 360 = 20 (3)

When the section detection unit 14 detects that the position C in FIG. 9A is the fourth section, the position calculation unit 15 calculates the distance from the origin 30 of the position C as shown in the following equation (4). , 20 mm.
(Distance at position C) = 10 ÷ 2 × (4-2) + 10 × 360 ÷ 360 = 20 (4)

As described above, in the control device 10, the section detection unit 14 detects the section in the movable range of the mover 25 based on the signal output from the hall sensor 29, and the electrical angle calculation unit 13 is output from the MR sensor 27. The electrical angle in each section is calculated based on the signal. Then, the position calculation unit 15 applies the mover 25 to the mover 25 according to the above formula (1) or formula (2) based on the section detected by the section detection unit 14 and the electrical angle calculated by the electrical angle calculation unit 13. The positions of the MR sensor 27 and the hall sensor 29 provided are calculated.
As a result, the absolute position of the mover 25 relative to the stator 21 can be detected without using an optical absolute encoder.

  In this embodiment, as described above, the scale magnet 31 is provided to detect the absolute position. As a result, the scale magnet 31 can utilize the technology for manufacturing the drive magnet 24 and can be manufactured at a low cost. Therefore, the absolute position of the mover 25 can be compared with the case where an optical absolute encoder is used. It is possible to realize the function of detecting Further, by using the driving magnet 24 for absolute value detection, the cost required for absolute position detection can be reduced.

In this embodiment, the magnetic pole pitch between the scale magnets 31 is set to be half the magnetic pole pitch between the drive magnets 24.
As a result, when the hall sensor 29 is located at a position facing the boundary of the arranged scale magnets 31, the position detector 15 detects any one of the two possible sections. Can calculate the correct distance (absolute position) from the origin 30 based on the electrical angle calculated by the electrical angle calculator 13.

In the present embodiment, the scale magnet 31 is configured such that the magnetic poles of the N pole and the S pole are alternately arranged in the moving direction, and the combination of the polarity of each magnetic pole and the magnetic flux density is different for each section.
Thereby, the combination of the polarity of the magnetic pole and the magnetic flux density can be associated with each section, and compared to the case where the section is identified only by the magnetic flux density, the section twice (N pole and S pole) can be represented. . Or compared with the case where a section is identified only by magnetic flux density, the interval of the difference of the magnetic flux density in each magnet 31 for a scale can be doubled, and the fall of the detection accuracy of the section detection part 14 can be prevented.

Second Embodiment
The linear motor device according to the second embodiment of the present invention is that the magnetic pole facing the hall sensor 29 of the magnet of the scale magnet is only one of the N pole and the S pole. Different from device 1. Hereinafter, the arrangement of the magnets for scale will be described, and other configurations are the same as those in the first embodiment, so the same reference numerals are given and the description thereof is omitted.

FIG. 10 is a diagram for explaining an example in which the control device 10 according to the second embodiment calculates the position of the mover 25. FIG. 10A shows a case where the scale magnet 31A (31A-N1, 31A-N2, 31A-N3,...) Is arranged so that only the N pole faces the hall sensor 29. Is shown as an example.
FIG. 10A shows the arrangement of the scale magnets 31A (31A-N1, 31A-N2, 31A-N3,...) And the level of the signal output from the hall sensor 29 in association with each other. Yes. In the figure, the horizontal axis indicates the position of the mover 25, and the vertical axis indicates the level of the signal output from the hall sensor 29. FIG. 10A shows a sine wave with respect to the electrical angle calculated by the electrical angle calculation unit 13.

In the figure, the pitch between the magnetic poles of the drive magnet 24 is set to 10 mm, and the pitch between the magnetic poles of the scale magnet 31 is set to 5 mm, which is half of the pitch between the magnetic poles of the drive magnet 24.
Further, in the drawing, the scale magnets 31A-N1, 31A-N2,... Are arranged so that the magnetic flux densities thereof are all different and the magnetic flux densities are monotonously decreased in order from the origin 30.

  Further, the electrical angle α in the odd-numbered section from the origin 30 is 0 ° ≦ α ≦ 180 °, and the electrical angle α in the even-numbered section is at a position where 180 ° ≦ α <360 °. Is arranged with respect to the drive magnet 24. That is, the position calculation unit 15 determines whether the section indicated by each scale magnet 31A (31A-N1, 31A-N2,...) Is odd-numbered or even-numbered from the origin 30 according to the first embodiment. Similarly, the case where the electrical angle calculated by the electrical angle calculation unit 13 is treated as 0 ° is distinguished from the case where it is treated as 360 °.

  FIG. 10B is a perspective view showing the arrangement of the scale magnets 31A (31A-N1, 31A-N2,...). As illustrated, the scale magnets 31A (31A-N1, 31A-N2,...) Are arranged such that the magnetic poles on the side through which the Hall sensor 29 passes are N poles.

When the MR sensor 27 and the hall sensor 29 are at the position D shown in FIG. 10A, the control device 10 calculates the position of the mover 25 as follows.
The electrical angle α calculated by the electrical angle calculation unit 13 is 180 ° as shown in FIG. In addition, the section detection unit 14 detects a fifth (L = 5) th fifth section from the origin 30.
And the position calculation part 15 calculates the position D like following Formula (5) by said Formula (1).

  (Distance at position D) = 10 ÷ 2 × (5-1) + 10 × 180 ÷ 360 = 25 (5)

  Further, when the section detection unit 14 detects that the position D in FIG. 10A is the sixth section, the position calculation unit 15 calculates the position D of the following formula (6) by the above formula (2). Calculate as follows.

  (Distance at position D) = 10 ÷ 2 × (6-2) + 10 × 180 ÷ 360 = 25 (6)

As described above, the distance (absolute position) from the origin 30 can be calculated even if the magnetic pole facing the hall sensor 29 of the scale magnet 31A is either the N pole or the S pole.
Compared with the case where two poles are magnetized by making the magnetic pole facing the Hall sensor 29 of the scale magnet 31A one of the N poles and the S poles as in the present embodiment, it is troublesome to magnetize. And the manufacture of the scale magnet 31A can be facilitated.

  In the first and second embodiments described above, the scale magnet 31 (31A) has been described so that the magnetic flux density is monotonically increased from the origin 30. However, the present invention is not limited to this. The magnetic flux density may be different so that the section corresponding to the scale magnet 31 can be uniquely detected.

In the first embodiment and the second embodiment described above, the configuration in which the electrical angle is calculated using the driving magnet 24 of the linear motor 20 has been described. However, as shown below, you may make it the structure which provides the magnet for calculating an electrical angle separately.
FIG. 11 is a diagram illustrating a linear motor device 2 according to a modification of the first embodiment and the second embodiment. As shown in the figure, in order to calculate the electrical angle in parallel to the moving direction of the mover 25, the electrical angle magnet 32 composed of a plurality of magnets is provided. Different from the second embodiment. Since other configurations are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.
The plurality of magnets of the electrical angle magnet 32 are arranged at equal intervals in parallel with the moving direction of the mover 25. Here, “parallel to the moving direction of the mover 25” means that the straight line connecting the centers of the plurality of magnets of the electric angle magnet 32 is parallel to the straight line indicating the moving direction of the mover 25.

In this manner, in the linear motion type apparatus other than the linear motor 20, the scale magnet 31 and the electric angle magnet 32 are provided with the stator 21, and the MR sensor 27 and the hall sensor 29 are arranged at positions facing each other. The absolute position can be calculated.
The scale magnet 31 and the electrical angle magnet 32 may be provided at a place other than the stator 21.

In the first and second embodiments described above, the linear motor has a structure in which the armature 60 moves. However, the linear structure has a structure in which the armature 60 is fixed and the driving magnet 24 moves. It may be a motor.
In the first embodiment and the second embodiment described above, the MR sensor 27 uses an MR sensor that outputs a sine wave signal Ssin and a cosine wave signal Scos according to the direction of the magnetic field. . However, the present invention is not limited to this, and the MR sensor 27 may use an MR sensor that outputs a sine wave signal Ssin and a cosine wave signal Scos according to the strength of the magnetic field.

  The control device 10 described above may have a computer system inside. In this case, the operation processes of the control unit 11, the electrical angle calculation unit 13, and the section detection unit 14 described above are stored in a computer-readable recording medium in the form of a program, and the computer reads and executes this program. Thus, the above operation is performed. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  DESCRIPTION OF SYMBOLS 1, 2 ... Linear motor apparatus, 10 ... Control apparatus, 11 ... Control part, 13 ... Electrical angle calculation part, 14 ... Section detection part, 15 ... Position calculation part, 20 ... Linear motor, 21 ... Stator, 24 ... Drive Magnets 25 ... Movers 27 ... MR sensors (first sensors) 29 ... Hall sensors (second sensors) 31,31A ... Scale magnets (second magnets) 32 ... Electric angle magnets (First magnet), 60 ... armature

Claims (5)

A driving magnet unit including a plurality of driving magnets in which N poles and S poles are alternately arranged at equal intervals; and an armature including a plurality of coils, the armature or the driving magnet unit Any one of the movable elements is arranged, and the movable elements are arranged by arranging the driving magnets by a magnetic field generated by passing a current through a plurality of coils provided in the armature and a magnetic field generated by the driving magnets. A linear motor control device that linearly moves in the arranged direction,
A first magnet unit comprising a plurality of first magnets in which N poles and S poles are alternately arranged at equal intervals in the arrangement direction;
A first magnetic sensor provided in the armature so as to face the first magnet unit, detects a magnetic field generated by the first magnet, and outputs a signal corresponding to the detected magnetic field. A first magnetic sensor for outputting;
An electrical angle calculator that calculates an electrical angle based on a signal received from the first magnetic sensor;
A plurality of second magnets for uniquely identifying each of the sections obtained by dividing the movable range of the mover in the arrangement direction into a plurality of sections, and a plurality of second magnets arranged at equal intervals in the arrangement direction. A second magnet part;
A second magnetic sensor provided in the armature so as to face the second magnet portion, and outputs a signal corresponding to the magnetic flux density of the magnetic field generated by the second magnet. Magnetic sensor of
A section detecting unit for detecting the section in which the armature is located based on a signal received from the second magnetic sensor;
A linear motor comprising: a position calculating unit that calculates a position of the mover in the movable range based on the section detected by the section detecting unit and the electrical angle calculated by the electrical angle calculating unit. Control device. The linear motor control device according to claim 1, wherein the first magnet unit is the driving magnet. The plurality of second magnets provided in the second magnet portion have the same length in the arrangement direction as the section, and the length of the first magnet in the arrangement direction. The linear motor control device according to claim 1, wherein the linear motor control device is a half of the linear motor control device. In the plurality of second magnets provided in the second magnet unit, magnetic poles of N poles and S poles are alternately arranged in the arrangement direction, and the polarity and magnetic flux density of each magnetic pole are The combination is different. The linear motor control device according to any one of claims 1 to 3, wherein the combination is different. 4. The linear motor according to claim 1, wherein the plurality of second magnets provided in the second magnet unit have different magnetic flux densities for each of the sections. 5. Control device.

Images