JP2008253088A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a motor controller that achieves high-precision fully-closed control by using only a linear scale. <P>SOLUTION: The motor controller has a machine-position input means 20, which inputs a detection signal of a machine-position detector so as to output a machine position, a speed control means 8, which inputs a sum of a differential-speed estimation value and a machine speed as a speed feedback signal so as to output a torque command that allows the speed feedback signal to follow a speed command, a torque control means 9 for controlling motor torque on the basis of a magnetic-pole position, a speed detection means 10 for differentiating the machine position so as to output a machine speed, and a differential-speed estimation means 11 that inputs a torque command so as to output a differential-speed estimation value being an estimation value of a difference between a motor speed and a machine speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control device that performs full-closed control, and more particularly to a motor control device that performs full-closed control of a machine having a large mechanical resonance.

  As a control method for controlling the position of the movable part of the machine with high accuracy, full-closed control for detecting the position of the movable part and performing feedback control is known. FIG. 3 shows a control block diagram of a conventional motor control device that performs full-closed control (see, for example, Patent Document 1 and Patent Document 2). In FIG. 3, an encoder 2 is attached to the motor 1. The encoder 2 detects the speed and position of the motor 1. A ball screw 3 is connected to a drive shaft of the motor 1 via a coupling 4. The motor 1 causes the table 5 which is a movable part of the machine to linearly move by rotating the ball screw 3. The linear scale 6 functions as a mechanical position detecting means and detects the position of the table 5 that moves linearly.

  The position control means 7 inputs a position command given from a host controller (not shown), and inputs the machine position detected by the linear scale 6 as a position feedback signal so that the position of the table 5 follows the position command. Output a speed command. The speed control means 8 inputs the speed command that is the output of the position control means 7 and also inputs the motor speed detected by the encoder 2 as a speed feedback signal so that the speed of the motor 1 follows the speed command. Outputs a torque command. The torque control means 9 inputs a torque command that is the output of the speed control means 8, controls the motor torque based on the magnetic pole position of the motor detected by the encoder 2, and drives the motor.

  The conventional full-closed control apparatus is configured as described above, and a position control loop is configured by feeding back the position of the machine movable portion detected by the linear scale 6 to the position control means 8. Since the position of the table 5 which is a movable part of the machine is directly detected by the linear scale 6 and feedback control is performed so that the position of the movable part matches the position command, even if the machine has errors such as deviation or thermal deformation The position of the table 5 can be positioned with high accuracy.

Japanese Patent Application Laid-Open No. 07-225615 (page 3, FIG. 1) JP 2001-309676 A (2nd page, FIG. 13)

  As described above, in a conventional motor control device that performs full-closed control, position control is performed using the position of the machine movable portion detected by the linear scale 6, and the speed and magnetic pole position of the motor 1 detected by the encoder 2. Speed control and torque control were performed using For this reason, it is necessary to use two detectors of the encoder 2 and the linear scale 6, and there is a problem that the control system becomes expensive.

  As a method for solving such a problem and performing full-closed control with only one detector, a method in which a control system is configured with only a linear scale signal without using an encoder can be considered. When the rigidity of the machine is high and there is no machine error, the motor position detected by the encoder matches the position of the machine movable part detected by the linear scale. In such a case, it is also possible to realize full closed control only with a linear scale. However, if the machine has low rigidity and the machine is distorted, the position of the motor detected by the encoder and the position of the machine moving part detected by the linear scale will not match, making accurate full-closed control difficult. Become.

  First, if the position information detected by the linear scale in torque control is used as the magnetic pole position, the magnetic pole position does not coincide with the actual magnetic pole position of the motor. It becomes impossible.

  Further, if the speed control loop is configured by feeding back the speed of the machine movable part detected by the linear scale, there is a problem that the speed gain cannot be increased and the speed control performance deteriorates. The reason for this will be described with reference to the drawings.

  FIG. 4 shows the frequency response from the motor torque to the speed feedback signal when the rigidity of the machine is low. FIG. 4A is a frequency response from the motor torque to the motor speed detected by the encoder, and is a frequency response when the motor speed is a speed feedback signal. FIG. 4B is a frequency response from the motor torque to the speed of the machine movable part detected by the linear scale, and is a frequency response when the speed of the machine movable part is a speed feedback signal.

  When the rigidity of the machine is low, the frequency response from the motor torque to the motor speed detected by the encoder has anti-resonance and resonance characteristics as shown in FIG. That is, the gain characteristic has a notch characteristic in which the gain decreases at the anti-resonance frequency, and the gain increases at the resonance frequency and has a resonance peak. The phase characteristic is 90 degrees with the phase advanced by 180 degrees at the anti-resonance frequency, and becomes -90 degrees with a delay of 180 degrees at the resonance frequency. It is known that the control system becomes unstable when the gain becomes 0 db or more at a frequency where the phase is −180 degrees, but in FIG. 4-1, the phase does not become smaller than −90 degrees. The control system does not become unstable even if the speed control gain is set large. Accordingly, when the speed control loop is configured by feeding back the motor speed, it is possible to set a large speed control gain and to perform highly accurate speed control.

  On the other hand, the frequency response from the motor torque to the speed of the machine moving part detected by the linear scale has a characteristic having only resonance as shown in FIG. In this case, since the phase is −180 degrees at the resonance frequency, it can be seen that the control system becomes unstable when the gain at the resonance peak becomes 0 db or more. That is, when a speed control loop is configured by feeding back the speed of the movable part, it is necessary to set the speed control gain so that the resonance peak gain is 0 db or less, and the speed gain cannot be increased. .

  Thus, if the speed detected by the linear scale is fed back to configure the speed control loop, the speed control gain must be made smaller than when the motor speed is used, and the speed control performance will deteriorate. .

  Furthermore, the same can be said for the position control loop. When the position control loop is configured by feeding back the position of the machine moving part detected by the linear scale, the position control gain must be set smaller than when the motor position is used. As a result, the position control performance deteriorates.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a motor control device that can realize highly accurate full-closed control using only a linear scale without using an encoder. Yes.

  In order to solve the above-described problems and achieve the object, the motor control device of the present invention includes a machine position input means for inputting a detection signal of a machine position detector and outputting a machine position, and a differential speed estimated value described later. And a speed control means for inputting a speed command and outputting a torque command such that the speed feedback signal follows the speed command, a torque command and a magnetic pole of the motor Torque control means for controlling the torque of the motor based on the magnetic pole position, speed detection means for inputting the machine position, differentiating the machine position and outputting the machine speed, and inputting a torque command And a differential speed estimating means for outputting a differential speed estimated value that is an estimated value of the difference between the motor speed and the machine speed.

  Another motor control device of the present invention inputs a machine position input means for inputting a detection signal of a machine position detector and outputs a machine position, inputs a motor speed estimated value described later as a speed feedback signal, and outputs a speed command. Speed control means for inputting and outputting a torque command such that the speed feedback signal follows the speed command, and torque control for controlling the torque of the motor based on the magnetic pole position by inputting the torque command and the magnetic pole position of the motor Means, speed detection means for inputting the machine position, differentiating the machine position and outputting the machine speed, and inputting the machine speed to output a motor speed estimated value which is an estimated value of the motor speed from the machine speed And a motor speed estimating means.

  According to the present invention, the speed of the motor and the position of the motor are estimated based on the torque command of the motor and the position of the machine moving part, and the estimated value is used to control the speed control, the position control, and the torque. Since the control is performed, there is an effect that it is possible to realize highly accurate full-closed control using only a linear scale without using an encoder.

Embodiment 1 FIG.
1 is a block diagram of a motor control apparatus according to Embodiment 1 of the present invention. In FIG. 1, a ball screw 3 is further connected to the motor 1 via a coupling 4. The motor 1 causes the table 5 which is a movable part of the machine to linearly move by rotating the ball screw 3. The linear scale 6 functions as a mechanical position detection unit and detects the position of the table 5.

  The motor control device 101 according to the present embodiment includes a position control means 7, a speed control means 8, a torque control means 9, a speed detection means 10, a differential speed estimation means 11, a differential position estimation means 12, and a machine position input means 20. is doing.

  The position control means 7 inputs a position command given from a host controller (not shown), and inputs the sum of a machine position detected by the linear scale 6 and a difference position estimated value described later as a position feedback signal. A speed command is output so that the position of the position follows the position command.

  The speed control means 8 inputs a speed command that is an output of the position control means 7 and inputs the sum of a machine speed detected by the encoder 2 and a differential speed estimated value described later as a speed feedback signal. A torque command is output so that the speed follows the speed command.

  The torque control means 9 inputs a torque command that is the output of the speed control means 8, controls the torque of the motor based on the magnetic pole position obtained from the position feedback signal, and drives the motor.

  The machine position input means 20 inputs the detection signal detected by the linear scale 6 and outputs it as the position of the machine movable part (machine position). The speed detection means 10 differentiates the position of the machine movable part (machine position) input from the machine position input means 20 and outputs the speed (machine speed) of the machine movable part.

で与えられる。 The differential speed estimation means 11 receives a torque command, estimates the difference between the motor speed and the speed of the machine movable part (machine speed), and outputs it as a differential speed estimated value. The transfer function of the differential speed estimation means 11 is as follows: when the moment of inertia of the machine including the motor is Ja, the resonance angular frequency of the machine is ωr, the resonance damping coefficient is ζr, the antiresonance angular frequency is ωa, and the antiresonance damping coefficient is ζa. ,

Given in.

である。 The difference position estimation means 12 receives a torque command, estimates the difference between the motor position and the position of the machine movable part (machine position), and outputs it as a difference position estimated value. Its transfer function is

It is.

（３）式と（４）式から、モータ速度ｖｍと機械可動部の速度ｖｌの差Δｖは

で得られる。差速度推定手段１１の伝達関数は（１）式であるから、差速度推定手段１１は、トルク指令を用いてモータ速度ｖｍと機械可動部の速度ｖｌの差Δｖ＝ｖｍ−ｖｌを推定して出力していることになる。 Next, the operation will be described. The differential speed estimation means 11 inputs a torque command and outputs a difference Δv = vm−vl between the motor speed vm and the speed vl of the machine movable part. When the rigidity of the machine is low and the machine resonance is large, the transfer function from the motor torque τm to the motor speed vm and the machine moving part speed vl can be written as follows using the above symbols.

From the expressions (3) and (4), the difference Δv between the motor speed vm and the machine moving part speed vl is

It is obtained by. Since the transfer function of the differential speed estimation means 11 is the equation (1), the differential speed estimation means 11 estimates the difference Δv = vm−vl between the motor speed vm and the machine moving part speed vl using the torque command. It is output.

  The output of the differential speed estimating means 11 is added to the speed vl of the machine movable part which is the output of the speed detecting means 10 and input to the speed control means 8 as a speed feedback signal. The output of the differential speed estimator 11 is an estimated value of the difference Δv = vm−vl between the motor speed vm and the speed vl of the machine movable part. When this is added to the speed vl of the machine movable part, the estimated value of the motor speed vm Is obtained. The estimated value of the motor speed vm obtained in this way is input to the speed control means 8, and a speed control loop is configured.

  As described above, when the speed control loop is configured by feeding back the speed of the machine movable part, there is a problem that the gain of the speed control cannot be increased as compared with the case where the motor speed is used. However, according to the present embodiment, since the motor speed is estimated and fed back, the speed control gain can be increased to the same extent as when the motor speed is detected and fed back, and the speed is high. Control can be performed.

となる。
（６）式と（７）式から、モータ位置θｍと機械可動部の位置θｌの差Δθ＝θｍ−θｌは

となる。差位置推定手段１２の伝達関数は（２）式であるから、差位置推定手段１２はトルク指令を用いてモータ位置θｍと機械可動部の位置θｌの差Δθ＝θｍ−θｌを推定して出力していることになる。 Next, the position control loop will be described. The transfer function from the motor torque τm to the motor position θm and the position θl of the machine moving part is

It becomes.
From the equations (6) and (7), the difference Δθ = θm−θl between the motor position θm and the machine movable portion position θl is

It becomes. Since the transfer function of the difference position estimation means 12 is the equation (2), the difference position estimation means 12 estimates and outputs the difference Δθ = θm−θl between the motor position θm and the position θl of the machine movable part using a torque command. Will be.

  The output of the difference position estimation means 12 is added to the position θl of the machine movable part that is the output of the linear scale 6 and is input to the position control means 7 as a position feedback signal. The output of the difference position estimator 12 is an estimated value of the difference Δθ = θm−θl between the motor position θm and the machine movable part θl, and when this is added to the position θl of the machine movable part, can get. That is, by adding the output of the linear scale 6 and the output of the difference position estimation means 12, an estimated value of the motor position θm is obtained, and this is input to the position control means 7 as a position feedback signal, and the position control loop is executed. It is composed.

  Even in the position control, there is a problem that if the position control loop is configured by feeding back the position of the machine movable portion, the gain of the position control cannot be increased as compared with the case where the motor position is fed back. However, according to the present embodiment, since the motor position is estimated and fed back, the position control gain can be increased to the same extent as when the motor position is detected and fed back, and the position with high accuracy is obtained. Control can be performed.

  Further, the estimated value of the motor position obtained as described above is used as the magnetic pole position of the motor in the torque control means 9. Accordingly, the accuracy of the magnetic pole position is improved as compared with the case where the position of the machine movable portion detected by the linear scale 6 is used as the magnetic pole position, so that highly accurate torque control is possible.

Embodiment 2. FIG.
FIG. 2 is a block diagram of a motor control apparatus according to Embodiment 2 of the present invention. In FIG. 2, the motor control apparatus 102 of the present embodiment includes a position control means 7, a speed control means 8, a torque control means 9, a speed detection means 10, a motor degree estimation means 13, a motor position estimation means 14, and a machine position input. Means 20 are provided.

である。 The motor degree estimating means 13 estimates the motor speed based on the speed (machine speed) of the machine movable part, which is the output of the speed detecting means 10, and outputs it as a motor speed estimated value. The motor position estimation means 14 estimates the motor position based on the position (machine position) of the machine movable part input from the machine position input means 20 and outputs it as a motor position estimated value. However, when the anti-resonance angular frequency of the machine including the motor is ωa and the anti-resonance damping coefficient is ζa, the transfer function of the motor speed estimation means 13 and the transfer function of the motor position estimation means 14 are both

It is.

を得る。さらに、ζａが十分小さいとすると、上式は、

と近似できる。これは、モータ速度推定手段１３の伝達関数であるので、モータ速度推定手段１３の出力はモータ速度ｖｍの推定値となる。モータ速度推定手段１３の出力であるモータ速度ｖｍの推定値は速度制御手段８に入力され、速度制御ループが構成される。 From the equations (3) and (4), the transfer function from the speed vl of the machine movable part to the motor speed vm is obtained.

Get. Furthermore, if ζa is sufficiently small,

Can be approximated. Since this is a transfer function of the motor speed estimating means 13, the output of the motor speed estimating means 13 is an estimated value of the motor speed vm. The estimated value of the motor speed vm, which is the output of the motor speed estimation means 13, is input to the speed control means 8, and a speed control loop is configured.

  According to the second embodiment, since the motor speed vm is estimated and fed back by the motor speed estimating means 13, the gain of the speed control can be increased as in the case of detecting and feeding back the motor speed vm. High-accuracy speed control can be performed.

と近似できる。これは、モータ位置推定手段１４の伝達関数と同じであり、モータ位置推定手段１４は、モータ位置θｍの推定値を出力する。モータ位置推定手段１４の出力であるモータ位置θｍの推定値は位置制御手段７に入力され、位置制御ループが構成される。 Further, when the transfer function from the position θl of the machine movable portion to the motor position θm is obtained from the expressions (6) and (7), as in the expression (11).

Can be approximated. This is the same as the transfer function of the motor position estimating means 14, and the motor position estimating means 14 outputs an estimated value of the motor position θm. The estimated value of the motor position θm, which is the output of the motor position estimating means 14, is input to the position control means 7, and a position control loop is configured.

  As described above, according to the second embodiment, since the motor position is estimated by the motor position estimating unit 14 and fed back, the gain of position control is increased in the same manner as when the motor position is detected by the encoder and fed back. Therefore, highly accurate position control can be performed.

  Further, the estimated motor position value obtained as described above is used as the magnetic pole position of the motor in the torque control means 9. Accordingly, the accuracy of the magnetic pole position is improved as compared with the case where the position of the machine movable portion detected by the linear scale 6 is used as the magnetic pole position, so that highly accurate torque control is possible.

  Further, the transfer functions of the motor speed estimating means 13 and the motor position estimating means 14 include a second-order term of s as shown in the equation (9). Therefore, the output includes the second derivative of the input signal, and the noise component of the input signal is amplified and output. When this becomes a problem, a noise component may be removed from the input signal or output signal through a low-pass filter.

  As described above, in the first and second embodiments, ωa is the anti-resonance angular frequency of the machine. However, if the anti-resonance angular frequency of the machine is not accurately known, ωa is the resonance angular frequency. A value smaller than ωr may be set. 4-1 and 4-2 show the comparison of frequency response when the motor speed is fed back and when the speed of the machine moving part is fed back. The essential difference between the two is the presence or absence of anti-resonance. This determines whether the speed control gain and the position control gain can be increased. That is, if the transfer function from the motor torque to the speed feedback signal has anti-resonance characteristics at a frequency lower than the resonance frequency, the control gain can be increased. For this reason, in the first and second embodiments, if ωa is set to a frequency lower than the resonance frequency, the frequency characteristics from the motor torque to the speed feedback become the same frequency characteristics as in FIG. 4-1. The control gain can be increased to the same extent as when the motor speed and motor position are fed back, and high-precision control can be realized.

  The motor control device according to the present invention is suitable for use as a motor control device that performs full-closed control of a machine having low mechanical rigidity and large mechanical resonance.

It is a block diagram of the motor control apparatus of Embodiment 1 of this invention. It is a block diagram of the motor control apparatus of Embodiment 2 of this invention. It is a block diagram of the conventional full closed control. It is a frequency response from a motor torque to a motor speed detected by an encoder, and is a diagram showing a frequency response when the motor speed is a speed feedback signal. It is a frequency response from the motor torque to the speed of the machine movable part detected by the linear scale, and is a diagram showing the frequency response when the speed of the machine movable part is a speed feedback signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Encoder 3 Ball screw 4 Coupling 5 Table 6 Linear scale 7 Position control means 8 Speed control means 9 Torque control means 10 Speed detection means 11 Differential speed estimation means 12 Differential position estimation means 13 Motor speed estimation means 14 Motor position estimation means 14 20 Machine position input means 101, 102 Motor control device

Claims (13)

Machine position input means for inputting the detection signal of the machine position detector and outputting the machine position;
Speed control means for inputting a sum of a differential speed estimated value described later and a machine speed described later as a speed feedback signal, and inputting a speed command, and outputting a torque command such that the speed feedback signal follows the speed command. When,
Torque control means for inputting the torque command and the magnetic pole position of the motor and controlling the torque of the motor based on the magnetic pole position;
Speed detecting means for inputting the machine position, differentiating the machine position and outputting the machine speed;
A motor control device comprising: a differential speed estimating means for inputting the torque command and outputting a differential speed estimated value that is an estimated value of a difference between the motor speed and the machine speed. The transfer function of the differential speed estimation means is

Wherein S is a Laplace operator, Ja is a moment of inertia of a machine including a motor, ωr is a resonance angular frequency of the machine, ζr is a resonance damping coefficient, and ωa <ωr. Motor control device. Differential position estimation means for inputting the torque command and outputting a differential position estimated value that is an estimated value of the difference between the motor position and the machine position;
Position control that inputs the sum of the machine position and the estimated difference position value as a position feedback signal, and inputs the position command value, and outputs the speed command so that the position feedback signal follows the position command The motor control device according to claim 1, further comprising: means. The transfer function of the difference position estimating means is

Wherein S is a Laplace operator, Ja is a moment of inertia of a machine including a motor, ωr is a resonance angular frequency of the machine, ζr is a resonance damping coefficient, and ωa <ωr. Motor control device. A differential position estimating means for inputting the torque command and outputting a differential position estimated value that is an estimated value of a difference between the motor position and the machine position;
The torque control means obtains the magnetic pole position of the motor based on the sum of the machine position and the estimated difference position, and controls the torque of the motor based on the magnetic pole position. Or the motor control apparatus of Claim 2. The transfer function of the difference position estimating means is

6, wherein S is a Laplace operator, Ja is a moment of inertia of a machine including a motor, ωr is a resonance angular frequency of the machine, ζr is a resonance damping coefficient, and ωa is an antiresonance angular frequency. Motor control device. Machine position input means for inputting the detection signal of the machine position detector and outputting the machine position;
A speed control means for inputting a motor speed estimation value described later as a speed feedback signal, inputting a speed command, and outputting a torque command such that the speed feedback signal follows the speed command;
Torque control means for inputting the torque command and the magnetic pole position of the motor and controlling the torque of the motor based on the magnetic pole position;
Speed detecting means for inputting the machine position, differentiating the machine position and outputting a machine speed;
And a motor speed estimating means for inputting the machine speed and outputting the estimated motor speed value which is an estimated value of the motor speed from the machine speed. The transfer function of the motor speed estimating means is

However, S is a Laplace operator, ζa is an anti-resonance damping coefficient, and ωa is a value smaller than the resonance angular frequency of the machine. Motor position estimation means for inputting the machine position and outputting a motor position estimation value that is an estimated value of the motor position from the machine position; inputting the motor position estimation value as a position feedback signal; and inputting a position command The motor control device according to claim 7, further comprising: position control means for outputting the speed command so that the position feedback signal follows the position command. The transfer function of the motor position estimating means is

Here, S is a Laplace operator, ζa is an anti-resonance damping coefficient, and ωa is a value smaller than the resonance angular frequency of the machine. Motor position estimating means for inputting the machine position and outputting a motor position estimated value that is an estimated value of the motor position from the machine position;
The said torque control means calculates | requires the magnetic pole position of the said motor based on the said motor position estimated value, and controls the torque of the said motor based on this magnetic pole position. Motor control device. The transfer function of the motor position estimating means is

The motor control device according to claim 11, wherein S is a Laplace operator, ωa is an anti-resonance angular frequency, and ζa is an anti-resonance damping coefficient. The motor control device according to any one of claims 2, 4, 8, and 10, wherein the ωa is an anti-resonance angular frequency of a machine.

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