JPH05168275A - Controller for three-phase motor - Google Patents

Abstract

PURPOSE:To obtain a three-phase AC motor controller having a code plate comprising absolute patterns capable of detecting the rotating position of a plurality of three-phase AC motors with different resolutions. CONSTITUTION:The number of divided pieces of an absolute pattern of one track formed on a code disk connected to the rotating shaft of a three-phase motor is determined to 3 times the common multiple of the number of magnetic pole of a plurality of three-phase AC motors with different number of magnetic poles. In addition, resolution designating means 48, rotation position data output means 42 to 46 and 49 for outputting rotation position data in accordance with the resolution designated by the resolution designating means, and current control means 47 for controlling the rotation position of three-phase AC motor and controlling three-phase current based on the rotation position data output are provided in this three-phase AC motor controller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a three-phase AC motor, and more particularly to a controller for detecting the rotational position of a three-phase AC motor with an absolute encoder.

[0002]

2. Description of the Related Art In a conventional three-phase AC motor control device, a rotary encoder is connected to the rotary shaft of a three-phase AC motor, and the rotary position is detected by the code plate of the rotary encoder that rotates together with the rotary shaft. The detected rotational position data is input to the current control device, and the current control device is configured to control the three-phase current based on the input rotational position data to control the rotational position of the three-phase AC motor. ..

A three-phase AC motor requires at least three U-phase, V-phase, and W-phase coils for supplying three-phase current to each magnetic pole, and the three-phase AC motor has at least three times the number of magnetic poles. The coil is provided. In order to detect the positional relationship between each magnetic pole and each coil, the rotational position of the code plate rotating with the magnetic pole is detected. Therefore, the code plate is required to have a resolution divided into at least three times the number of magnetic poles.

As shown in FIG. 4, the code plate of the rotary encoder includes a disc-shaped code plate 51, on which U-phase, V-phase and W-phase of a three-phase current for controlling the rotational position of a three-phase AC motor are respectively provided. Corresponding to three tracks 51b, 51c, 5
1d were arranged concentrically. A light-dark pattern was formed on each track by dividing one track into the same number as the number of magnetic poles. Three trucks 51b, 51
c and 51d were arranged with a shift of 120 degrees from each other, and a resolution obtained by dividing the number of magnetic poles by three times was obtained. The detectors 52b, 52c, and 52d are arranged in the radial direction on each track with a slight gap from the code plate 51, and the arbitrary rotation of the code plate is achieved by combining the light and dark outputs of the detectors. The position could be detected. The code plate of FIG. 4 is a code plate corresponding to the number of magnetic poles of 2, and a bright and dark pattern obtained by dividing one track into two is formed on three tracks.

[0005]

In the above-mentioned conventional technique, when the number of magnetic poles of the controlled motor changes, it is necessary to change to a code plate having a pattern of resolution matching the number of magnetic poles. there were. The present invention has been made in view of such problems, and an object of the present invention is to enable one type of code plate to cope with a change in the number of magnetic poles of a controlled motor. ..

[0006]

In order to solve the above-mentioned problems, the three-phase AC motor control device of the present invention includes a code plate 11 on which absolute patterns 11c and 11d of one track are formed, and the code plate 11 of the code plate 11. Reading means 12c, 12d for reading a pattern, and position data output means 42, 43, 44, 4 for outputting rotational position data of the code plate 11 from the pattern read by the reading means 12c, 12d.
5, 46, 49 and current control means 47 for controlling the rotational position of the three-phase AC motor based on the position data.
And further, the absolute pattern 11
The division number of c and 11d is set to a common multiple of three times the number of magnetic poles of a plurality of three-phase AC motors having different numbers of magnetic poles, and the resolution required by the controlled motor of the plurality of three-phase AC motors is specified. A resolution designating unit 4 which has a resolution designating member and outputs a signal corresponding to the resolution designated by the member.
8, the resolution specifying means 48 is connected to the position data output means 42, 43, 44, 45, 46, 49, and the position data output means 42, 43, 44, 4 are connected.
Reference numerals 5, 46 and 49 output rotational position data based on the resolution designated by the resolution designating means 48.

[0007]

In the present invention, the number of divisions of the absolute pattern of one track formed on the code plate connected to the rotary shaft of the three-phase AC motor is determined by the number of magnetic poles of a plurality of three-phase AC motors having different magnetic pole numbers. Since it is set to a common multiple of 3 times, it is possible to set a resolution obtained by equally dividing one round of the track by a divisor of the common multiple. These resolutions include the resolutions required when controlling the rotational positions of the plurality of three-phase AC motors. Further, since the rotational position data according to the resolution designated by the resolution designating means can be detected, even if the number of magnetic poles of the controlled motor changes, one type of code plate can be used to provide the resolution required by each motor. The rotation position can be detected based on.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, which is a code plate 11 which rotates together with a rotary shaft of a three-phase AC servomotor,
1 shows absolute detection element groups 12c and 12d arranged on the code plate 11 with a slight gap therebetween. The code plate 11 is provided with four tracks 11a, 11b, 11c and 11d concentric with the rotation center of the code plate 11. A very fine incremental pattern for speed control is formed on the outermost track 11a. Figure 1
For simplicity, omit the incremental pattern,
The lines are drawn in a mesh pattern. Second track 11 from the outside
In b, one track is divided into 144, and an incremental pattern in which light and dark are alternately repeated is formed. The incremental pattern is formed by a minimum reading pattern having a half width of the minimum reading pattern of the absolute pattern formed on the two tracks 11c and 11d on the inner side of the track, and a bright and dark pattern is formed at the center of the minimum reading pattern of the absolute pattern. Are arranged so that they switch. Third track 11c from the outside
In this, an absolute pattern is formed by dividing one track into 72. The absolute pattern of the present embodiment can be applied to five types of three-phase AC motors having the number of magnetic poles of 2, 4, 6, 8, and 12. The number of divisions of the absolute pattern can be set to the number of magnetic poles of 2, 4, 6, 8, 1
The common multiple 72 of the number 6, 12, 18, 24, 36 which is 3 times 2
Stipulated in. The absolute pattern, which is the maximum period sequence (M-sequence), as shown in FIG. 2, except for the solutions in parentheses from the solution of the primitive irreducible polynomial ^{"X 7 + X 5 + X} 2 + X 1 + X 0" 72 data are extracted and "0"
Are arranged in one track with "1" as a dark part and "1" as a dark part. The seven absolute detection element groups 12c are arranged along the track at the intervals of the minimum reading pattern of the absolute pattern. The same absolute pattern as that of the third track 11c is formed on the fourth track 11d from the outside. The pattern of the fourth track 11d and the pattern of the third track 11c are arranged with a shift of 1/2 width of the minimum read pattern of the absolute pattern. The seven absolute detection element groups 12d are arranged along the track at the intervals of the minimum reading pattern of the absolute pattern, and are offset from the absolute detection element group 12c by 1/2 width of the minimum reading pattern like the pattern. .. The two tracks 11c and 11d having the same pattern are provided to prevent the uncertain portion of the absolute signal from being included when the light and dark of the absolute pattern is switched. A means for achieving the same effect is disclosed in Japanese Patent Application Laid-Open No. 2-168115.
In Japanese Patent Laid-Open No. 168115/1990, a half width of a minimum read pattern is set to 1 on an absolute pattern of one track.
Two sets of detection elements are continuously arranged every other piece. In this embodiment, there are provided two tracks and two sets of detection elements having a shift of 1/2 width of the minimum reading unit pattern of the absolute pattern. By using the method of the present embodiment, the size of the detection element can be made the same as the minimum reading pattern of the absolute pattern, so even if the minimum reading pattern of the absolute pattern becomes fine, the detection element can be created. Is easy.

FIG. 3 is a block diagram of the signal processing circuit of the present invention. The motor driver 47 has a reset circuit 44.
And request signal 41 is output. Reset circuit 44
Is connected to the absolute detection circuit 42 and the bidirectional shift register 45, and outputs a reset signal to the absolute detection circuit 42 and the bidirectional shift register 45. The incremental detection circuit 43 is connected to the absolute detection circuit 42 and the motor driver 47, and outputs incremental signals 43a and 43b. The absolute detection circuit 42 includes the absolute detection element 12
c, 12d (see FIG. 1) and the signal conversion circuit 49, and based on the incremental signal 43a input from the incremental circuit 43, two absolute signals 42a detected by the absolute detection elements 12c, 12d, One of 42b is selected and output to the signal conversion circuit 49. The signal conversion circuit 49 I / V converts the absolute signal input from the absolute detection circuit 42 to shape the waveform, and then serially outputs it to the bidirectional shift register 45. Bidirectional shift register 45
Outputs the absolute rotational position data from the signal conversion circuit 49 to the ROM 46 in parallel. The ROM 46 outputs absolute rotational position data to the motor driver 47 based on the resolution designated by the resolution designating circuit 48 connected to the ROM 46. The motor driver 47 controls the three-phase current based on the input rotational position data and outputs it to the three-phase AC servomotor.

The signal processing operation of the signal processing circuit configured as described above will be described. The resolution designating circuit 48 sets the resolution required by the controlled servomotor. At the time of rotation start, the absolute position request signal 41 from the motor driver 47 that controls the three-phase current related to the rotation of the controlled servomotor.
Is input to the reset circuit 44, the reset circuit 44
Outputs a reset signal to clear the rotational position data of the absolute detection circuit 42 and the bidirectional shift register 45. At the same time, the absolute detection element group 12
The absolute pattern at the time of starting is read at c and 12d (see FIG. 1). Two absolute tracks 1
The first signal 42a and the second signal 42b of the two absolute pulse signals obtained from 1c and 11d (see FIG. 1) have a phase difference corresponding to 1/2 of the minimum pulse width in each pulse signal. On the other hand, from the incremental detection circuit 43, the incremental track 11b
(See FIG. 1), the incremental pulse signal 43a having a repetition period substantially equal to the minimum pulse width is output. This incremental pulse signal 43a
Is the first signal 42 of the two absolute pulse signals.
a, the second signal 42b is advanced or delayed by a phase difference corresponding to about ¼ of the minimum unit pulse width. Therefore, the rising and falling of the pulses of the first signal 42a and the second signal 42b are synchronized with the time point substantially at the center of the pulse of the incremental pulse signal 43a.
In the absolute detection circuit 42, the rising and falling edges of the pulse of the first signal are the incremental pulse signal 4
If it is synchronized with the high level of 3a, only the first signal 42a is output, and if the rising and falling edges of the pulse of the second signal 42b are synchronized with the high level of the incremental pulse signal 43a, the second signal 42b is output. Select the absolute pulse signal so that only the absolute pulse signal is output. Since the rising and falling of the absolute pattern are read at a time point approximately at the center of the high and low level of the incremental pulse signal 43a, the uncertain portion of the signal at the time of switching the light and dark of the absolute pattern is not included. The rotational position data at the time of starting is input to the signal conversion circuit 49 via the absolute detection circuit 42,
After I / V conversion and waveform shaping, it is input to the bidirectional shift register 45 as serial data. The rotational position data input to the bidirectional shift register 45 has a division number 72
R in parallel as rotational position data based on the resolution of
Output to OM46. The ROM 46 converts the input rotational position data based on the resolution of the division number 72 into rotational position data based on the resolution determined by the resolution designating circuit 48, and outputs the rotational position data to the motor driver 47. For example, in the case of changing the three-phase current based on the rotational position data according to the resolution of the division number 12 in the servo motor having the number of magnetic poles of 4, when the resolution of the division number 12 is set by the resolution designating circuit 48, the division number 72 is set in the ROM 46. Rotation position data based on the resolution of "1" to "72", "1 to 6""
1a "and" 7-12 "are" 2a "and" 13-18 "are"
3a "and" 19 to 24 "are replaced by" 4a "and" 25 to 30 "
"5a", "31-36" to "6a", "37-4
2 "is" 7a "," 43-48 "is" 8a "," 49-
54 "is" 9a "," 55-60 "is" 10a "," 6 "
1-66 "is" 11a "and" 67-72 "is" 12 "
a ″, which is converted into rotational position data based on the resolution of the division number 12 and output.
Based on the rotational position data, the phase and magnitude of each phase of the three-phase current are controlled and sent as a starting current to the controlled servo motor to rotate the controlled servo motor. While the controlled servo motor is rotating, the incremental pulse signal 43b is output from the incremental detection circuit 43 to the motor driver 47. Motor driver 47
Detects the rotational position by counting the number of pulses of the incremental pulse signal 43b with the absolute position at the start as a reference. The motor driver 47 always receives the rotational position data of the motor, and the motor driver 47
Outputs a three-phase current controlled on the basis of the rotational position data to the three-phase AC servomotor to control the rotational position of the three-phase AC servomotor.

In this embodiment, after detecting the absolute rotational position from the absolute pattern at the time of starting, the incremental pulse signal is counted to detect the rotational position. However, the absolute position detection circuit 42 always detects the rotational position data. You may output. In addition, a signal path is provided from the incremental detection circuit 43 to the signal conversion circuit 49, and an arithmetic unit is provided in the signal conversion circuit 49. If the rotational position data at the time of starting can be detected, the continuous rotational position data can be obtained by the arithmetic unit. Therefore, the incremental pulse signal is input to the signal conversion circuit 49, and the rotation obtained by the arithmetic unit according to the incremental pulse signal is input. It is also possible to sequentially output the position data to the bidirectional shift register 45, shift the rotational position data of the bidirectional shift register 45, and output the rotational position data to the ROM 46 in parallel.

It should be noted that the absolute pattern of one track may be any absolute pattern that does not become the same no matter where seven adjacent data out of 72 data are extracted, and the M series pattern of this embodiment. It is not limited to.

[0013]

As described above, according to the present invention,
The number of divisions of the absolute pattern of one track formed on the code plate is set to a common multiple of three times the number of magnetic poles of a plurality of three-phase AC motors having different numbers of magnetic poles. The resolution required for each AC motor can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a pattern of a code plate of a rotary encoder in a three-phase AC motor control device according to an embodiment of the present invention.

[Fig. 2] Primitive irreducible polynomial "X ⁷ + X ⁵ + X ² + X ¹ + X
It is a solution of ⁰ ″.

FIG. 3 is a block diagram of a signal processing circuit according to an embodiment of the present invention.

FIG. 4 is a diagram showing a pattern of a code plate of a rotary encoder in a conventional three-phase AC motor control device.

[Explanation of symbols]

 11 Code plate 11a Incremental track 11b Incremental track 11c Absolute track 11d Absolute track 12c Absolute detection element group 12d Absolute detection element group 41 Request signal 42 Absolute detection circuit 42a Absolute b incremental signal 43 Incremental signal 43 Incremental signal 43b Circuit 45 Bidirectional shift register 46 ROM 47 Motor driver 48 Resolution designation circuit 49 Signal conversion circuit 51 Code plate 51a Incremental track 51b Bright / dark pattern track 51c Bright / dark pattern track 51d Bright / dark pattern track 52a Detection element 52b Detection element 52c Detection element

Claims (1)

[Claims] 1. A code plate on which an absolute pattern of one track is formed, reading means for reading the pattern of the code plate, and position data output means for outputting rotational position data of the code plate from the pattern read by the reading means. And a current control unit for controlling the rotational position of the three-phase AC motor based on the position data, the three-phase AC motor control device, wherein the absolute pattern is divided into a plurality of three different numbers of magnetic poles. A common multiple of three times the number of magnetic poles of the phase alternating current motor is provided, and a resolution specifying member for specifying the resolution required by the controlled motor among the plurality of three phase alternating current motors is provided, and the resolution specified by the member is provided. A resolution designating means for outputting a corresponding signal is provided, and the resolution designating means is connected to the position data output means, The three-phase AC motor control device is characterized in that the position data output means outputs rotational position data based on the resolution designated by the resolution designating means.