JP2008191774A - Motor controller and mechanical vibration suppressing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanical vibration suppressing method capable of solving a problem that a motor has conventionally malfunctioned by detecting by a sensor minute mechanical vibration that cannot be suppressed even when the motor stops. <P>SOLUTION: An acceleration detection unit (a sensor) 2 is attached to a part having the maximum mechanical vibration of a machine 1 having a mechanical resonance characteristic. After phase-adjusted by a phase adjusting unit 7, an output signal from the acceleration detection unit (the sensor) 2 is input into an insensitive unit 8 for making a signal that is below a preset value zero before input into an acceleration feedback gain unit 9 and multiplied by a gain. Thereby, in the case of minute vibration, generation of position-deviation vibration by making the output signal of the insensitive unit 8 zero is suppressed so as to suppress both the mechanical vibration and a positional deviation vibration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor control apparatus that drives a load machine having mechanical resonance characteristics with an electric motor and a method for suppressing the mechanical vibration, and more particularly to control for suppressing vibration by feeding back an acceleration of a load.

FIG. 6 is a structural diagram showing an example of a machine having mechanical resonance characteristics to which the present invention is applied.
In FIG. 6, reference numeral 1 denotes a machine having mechanical resonance characteristics, 3 denotes an electric motor, 11 denotes a mechanical drive element composed of a ball screw mechanism rotated by the electric motor 3, and 12 denotes a mechanical drive attached to the mechanical drive element 11 by forward / reverse rotation of the electric motor 3. A movable table of a single-axis slider that moves forward / backward on the mechanical drive element 11 along the element 11, and 13 is a load machine (arm) mounted on the movable table 12. The arm 13 is vibrated by a change in acceleration when the movable table 12 moves forward and backward. Here, reference numeral 2 denotes an acceleration detection unit attached to the tip of the load machine 13. The acceleration detection unit 2 is attached to a place where the amplitude is the largest in the load machine 13 to detect vibration of the load machine 13 or the drive system.
The electric motor 3 moves the movable table 12 by rotating the mechanical drive element 11 composed of a ball screw mechanism, and thereby the load machine 13 on the movable table 12 is moved.
In the case of using a linear motor that is a direct acting motor, the movable table 12 can be linearly driven by replacing the mechanical drive element 11 and the motor 3 with a linear motor (not shown). Therefore, in the following description, the “motor” includes a direct acting motor (linear motor) in addition to the rotating type unless otherwise specified.

FIG. 7 is a block diagram of a conventional motor control device that controls a motor that drives a machine.
In the figure, 1 is a machine having mechanical resonance characteristics, 3 is an electric motor, 21 is an electric motor control device for controlling the electric motor 3, 4 is an electric motor drive unit, 5 is an electric motor speed detection unit, 6 is an electric motor speed control unit, and 10 is an electric motor. A position controller 31 is an electric motor position detector.
In general operation, the difference between the position command generated by a position commander (not shown) and the actual moving distance calculated by the motor position detection unit 31 is calculated by the motor position control unit 10 to perform motor speed control. It is converted into a speed command for the unit 6. In the motor speed control unit 6, calculation processing is performed based on a deviation between the speed command from the motor position control unit 10 and the actual speed detected by the motor speed detection unit 5, and torque to the next motor drive unit 4 ( (Thrust) command (in the case of a linear motor, this is a thrust command). The electric power of the electric motor drive unit 4 is supplied to the electric motor 3 and the electric motor 3 rotates, whereby the position control of the machine 1 is achieved.

FIG. 8 shows a partial modification of the control block diagram of the electric motor of FIG.
As shown in FIG. 8, 3 is an electric motor, 31 is an electric motor position detector, and 32 is a detected position differentiator. Utilizing the fact that the speed is a derivative of the position, the motor speed detector 5 detects the position of the motor 3 and the motor position detector 31 detects the position of the motor 3 and the detection position that differentiates the detection position that is the output of the motor position detector 31. The speed is obtained by differentiating the position output of the motor position detector 31 with the detected position differentiator 32, and the motor speed detector 5 (FIG. 7) is omitted.

Returning to FIG. 7, for example, when the motor 3 is a synchronous motor based on three-phase alternating current, the motor driving unit 4 converts the voltage amplifier for three phases by the normal PWM method and the dq axis that drives the voltage amplifier into three phases. A dq-axis to 3-phase conversion unit and a current control unit that converts the detected three-phase current of the motor into a dq axis and feeds back to each of the dq axes. Therefore, assuming that the d-axis command of the current control unit is normally zero, the q-axis current command value becomes a value proportional to the torque (thrust) generated by the electric motor. Usually, a correction operation such as dividing the torque (thrust) command by a torque (thrust) constant is performed to obtain a q-axis current command.
As described above, the position deviation, which is the difference between the position of the motor detected by the motor position detection unit 31 and the position command, is input to the motor position control unit 10. The motor position control unit 10 performs feedback control so that the position of the motor 3 matches the position command.
When the position deviation is equal to or smaller than a certain value (hereinafter referred to as a positioning completion width), “positioning completion” is set, and a “positioning completion” signal (not shown) is output from the motor position control unit 10 to the controller.
The controller calculates and outputs the position command of the electric motor so as to position the movable table at a desired position based on the lead length of the mechanical drive element using a ball screw, a belt or the like. The controller confirms that the position control unit has output the “positioning complete” signal, and outputs the next movement command.
When the mechanical drive element has high rigidity, the positioning of the movable table is completed at the same time as the positioning of the electric motor is completed.
However, when a load machine having mechanical resonance characteristics is driven by an electric motor, although the electric motor moves stably, the load machine vibrates due to the mechanical resonance characteristics, and a desired operation (for example, positioning operation) cannot be performed on the load machine. There was a problem.
When the mechanical resonance characteristics of the mechanical drive element are the main (when the frequency is low, etc.), the above problems such as the movable table shaking are well known, but the rigidity of the mechanical drive element is high (the natural frequency is high) Even so, there was the above problem.
For example, as shown in FIG. 6, when the arm 13 is fixed on the movable table 12 and the end effector at the tip of the arm is operated, even if the rigidity of the mechanical drive element 11 is high, the arm 13 has its own natural frequency. The tip shakes. In particular, when the damping coefficient of the natural vibration is small, even if the positioning of the electric motor 3 has been completed, the arm tip continues to vibrate, so that the work at the tip of the arm 13 cannot be performed.

FIG. 9 is a position deviation waveform diagram of the load machine tip position and the motor when the conventional motor position control device shown in FIG. 7 is used. In the figure, the vertical axis is the displacement, and the horizontal axis is the time axis.
According to this figure, since the motor position deviation is within the positioning complete width at the second square in the time axis direction, the motor is completely stopped, but the load machine tip position (arm tip) vibrates. continuing.
In such a case, it is necessary to wait until the vibration is sufficiently damped after the positioning is completed (waiting time) before outputting the next positioning command. This waiting time has a problem that the throughput of the machine is significantly deteriorated.
In this way, the mechanical resonance elements such as the mechanical resonance element of the machine drive system and the mechanism on the movable table are collectively set as the resonance characteristic of the load machine.

In order to solve this problem, the applicant of the present invention feeds back the vibration of the load machine measured by the acceleration sensor to the speed control unit of the motor control device through a band pass filter constituted by a low pass filter and a high pass filter. In this way, a technique for reducing the vibration of the load machine has been developed (Non-Patent Document 1).
Alternatively, as vibration suppression control by acceleration feedback, the output of the acceleration sensor attached to each axis is negatively fed back to the speed control unit of the corresponding axis via a low-pass filter and gain to form a closed loop for vibration isolation Has also been proposed (see Patent Document 1).
Japanese Patent Laid-Open No. 10-100085 JP-A-9-56183 Kura et al., "Yaskawa Electric, Vol. 48, 1984, No. 2," pp. 105-109

In the conventional method, the output of the acceleration sensor is fed back to the speed control through a filter and gain, so it is possible to reduce the vibration with a large amplitude to some extent, but the vibration is completely suppressed. There was a problem that it could not be done.
For example, as shown in FIG. 6, the conventional acceleration feedback design method shown in Non-Patent Document 1 or Patent Document 1 is applied to a machine 1 in which an arm 13 is attached to a movable table 12 of a single-axis slider and work is performed at the tip of the arm. In this case, the vibration attenuation can be increased. Naturally, the vibration suppression effect increases as the acceleration feedback gain is increased. However, if the gain is increased too much, the positional deviation or torque (or thrust) of the electric motor 3 after the positioning operation is completed is almost stopped. Regardless, there was a problem that moved up and down.
If the motor torque (or thrust) fluctuates inadvertently, as shown in FIG. 2, the arm tip (load machine) is stopped, but the motor fluctuates at the stop position. As a result, the machine cannot be positioned.
Further, there may be a problem that the wobbling of the movable table 12 excites the natural vibration of the arm 13 so that the arm vibration cannot be removed.
In addition, the load factor of the motor 3 increases carelessly by consuming unnecessary power due to unnecessary operation of the torque (or thrust) of the motor 3, so sudden acceleration / deceleration and operation pause time There is a problem that a high tact operation such as taking a short time cannot be performed (the load factor increases in the high tact operation, but the load factor of the electric motor 3 needs to be 100% or less due to limitation of heat generation).
In this way, even if you try to apply acceleration feedback strongly in order to suppress machine vibration and improve machine operation throughput, the actual machine will reduce machine operation throughput due to inadvertent fluctuations in position deviation and torque (thrust). There was a big problem that it could not be raised as much as I thought.
In spite of such problems, there has been no improvement in the past considering this stage as the limit of acceleration feedback.
The present invention has been obtained by the above-described experiment (FIG. 2) and consideration thereof, and suppresses inadvertent torque (thrust) fluctuations of the electric motor, and completely suppresses vibration of the mechanism portion by applying acceleration feedback strongly. It provides a method that can be used.

In order to solve the above-mentioned problem, an invention according to claim 1 relates to an electric motor control device, and relates to a machine including mechanical resonance characteristics and a motor that drives the machine and includes vibration due to resonance characteristics. An acceleration detection unit that detects acceleration, an electric motor drive unit that controls torque (thrust) of the electric motor, an electric motor speed detection unit that detects the speed of the electric motor, and a feedback of the speed of the electric motor speed detection unit to the electric motor A motor speed control unit that outputs a torque command to the drive unit, a motor position detection unit that detects the position of the motor, and a position command of the motor position detection unit is fed back to output a speed command to the motor drive unit. An electric motor position control unit, a phase adjustment unit that adjusts the phase of the acceleration signal output from the acceleration detection unit, and an output of the phase adjustment unit to the motor speed control unit In an electric motor control device including an acceleration feedback gain unit that performs feedback, a dead zone that sets a signal equal to or lower than a preset value to zero is provided between the output side of the phase adjustment unit and the input side of the acceleration feedback gain unit. It is characterized by that.
According to a second aspect of the present invention, there is provided a method for suppressing mechanical vibration of an electric motor control apparatus, comprising: a machine having mechanical resonance characteristics; and an electric motor that drives the machine, wherein the machine includes vibration due to resonance characteristics. An acceleration detection unit that detects acceleration, an electric motor drive unit that controls torque (thrust) of an electric motor that drives the machine, an electric motor speed detection unit that detects the speed of the electric motor, and feedback of the speed of the electric motor speed detection unit A motor speed control unit that outputs a torque command to the motor drive unit, a motor position detection unit that detects the position of the motor, and a speed to the motor drive unit by feeding back the position of the motor position detection unit. A motor position control unit that outputs a command; a phase adjustment unit that adjusts a phase of an acceleration signal output from the acceleration detection unit; and an output of the phase adjustment unit In the mechanical vibration suppression method of the motor control device configured by an acceleration feedback gain unit that feeds back to the speed control unit, when the output of the phase adjustment unit is equal to or less than a preset value, an input signal to the acceleration feedback gain unit Is characterized by zero.

  With the above motor control device and its mechanical vibration suppressing method, minute vibrations can be eliminated from the control loop, so that the vibration of the mechanism can be completely suppressed, and therefore the vibration of the machine having mechanical resonance characteristics. As a result, the positioning of the motor can be completed.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1 is a control block diagram of an electric motor control apparatus which is a prior art of the present invention.
Therefore, first, based on FIG. 1, the cause of the fluctuation of the motor torque (or thrust) will be considered.
In FIG. 1, 1 is a machine having mechanical resonance characteristics, 3 is an electric motor, 21 is an electric motor control device that controls the electric motor 3, 2 is an acceleration detection unit, 4 is an electric motor drive unit, 5 is an electric motor speed detection unit, and 6 is an electric motor. A speed control unit, 7 is a phase adjustment unit, 9 is an acceleration feedback gain unit, 10 is an electric motor position control unit, and 31 is an electric motor position detection unit. If the machine 1 has the same configuration as the machine shown in FIG. 6, for example, the movable table 12 is driven by a ball screw. Since the following description is the same for a mechanical element that drives the movable table 12 such as a belt or a gear, the description will be made in the case of a ball screw.
As shown in the figure, the electric motor 3 drives a movable table 12 by a mechanical drive element 11 having a ball screw mechanism to drive a load machine 13 on the movable table 12. In the load machine (arm) 13, the acceleration detector 2 is attached to a place where the amplitude is the largest (referred to as “antinode” of vibration), and the vibration of the load machine or drive system is detected. In the case of using a linear motor that is a direct acting motor, the movable table 12 can be linearly driven by replacing the mechanical drive element 11 and the motor 3 with a linear motor (not shown). Therefore, in the following description, the “motor” includes a direct acting motor (linear motor) in addition to the rotating type unless otherwise specified.
The electric motor 3 is driven by the electric motor drive unit 4. For example, when the motor 3 is a three-phase AC synchronous motor, although not shown, the motor driving unit 4 performs a three-phase conversion from a dq axis that drives a voltage amplifier and a voltage amplifier for three phases by a normal PWM method to three phases. And a current control unit that converts the detected three-phase current of the motor 3 into the dq axes and feeds back to each of the dq axes. Assuming that the d-axis command of the current control unit is normally zero, the q-axis current command value is proportional to the torque (thrust) generated by the electric motor 3. Usually, a correction operation such as dividing the torque (thrust) command by a torque (thrust) constant is performed to obtain a q-axis current command. A torque command (thrust command) is used as an input to the motor drive unit 4.

The motor speed control unit 6 feeds back the speed of the motor 3 detected by the motor speed detection unit 5 attached to the motor 3 and outputs a torque command (thrust command) to the motor drive unit 4 to speed the speed of the motor 3. Control to be equal to the command value.
The motor speed detection unit 5 can be configured by an electric motor position detection unit 31 that detects the position of the electric motor 3 and a detection position differentiation unit 32 that differentiates the detection position (see FIG. 8). Moreover, it can also be comprised by the speed detection part which detects the speed of the electric motor 3 directly like a speed generator or a gyro.
The acceleration including the natural vibration of the load machine 13 and the vibration of the machine drive element 11 detected by the acceleration detection unit 2 is input to the phase adjustment unit 7. The output of the phase adjustment unit 7 is fed back to the motor speed control unit 6 through the acceleration feedback gain unit 9. Alternatively, the output of the phase adjustment unit 7 may be added (or subtracted) to the speed command.
The phase adjustment unit 7 can extract vibrations of the load machine 13 and the mechanical drive element 11 by being configured with a low-pass filter and a high-pass filter, for example, as in the first conventional example. Alternatively, the vibration can be attenuated more effectively by adjusting the time constant of the low-pass filter with respect to the vibration frequency (as already shown in Patent Document 2).
Thus, acceleration feedback can be performed to the speed control system of the electric motor.
When controlling the position of the load machine 13, the motor position control unit 10 that feeds back the output of the motor position detection unit 31 that detects the position of the motor 3 and outputs a speed command to the motor speed control unit 6 is provided. It ’s fine. For example, the motor position control unit 10 may be configured to subtract a feedback signal (output of the position detection unit 31) from the position command, apply a position gain, and output the result to the motor speed control unit 6 as a speed command.

Generally, since a mechanical drive unit such as a ball screw has friction (particularly static friction), the electric motor and the movable table do not move unless the motor generates torque (or thrust) that overcomes Coulomb friction or static friction.
Therefore, even if the positioning operation with the same acceleration and deceleration characteristics is performed, the acceleration torque becomes larger by a value corresponding to the correction amount of the frictional force than the calculated value from the commanded acceleration. On the contrary, the deceleration torque is a deceleration force corresponding to the frictional force, and therefore the torque is smaller than the calculated value.
In a normal state in which acceleration feedback is not applied, when the motor position reaches the positioning target position and the motor speed becomes zero, the motor torque slowly approaches zero or maintains a constant value equal to or less than the static friction force.
In the acceleration feedback gain optimally adjusted by the prior art shown in FIG. 1, the motor torque at the time of stop is stable as described above.
When the operation of the machine of FIG. 6 is examined in detail with the electric motor completely stopped, for example, the acceleration sensor is operated because the vibration of the arm tip remains even after the acceleration of the movable table 12 becomes zero and the stopped state. Although a minute signal is detected and the speed command is fed back as an acceleration feedback signal, the motor 3 does not move due to the static frictional force (the movable table is stopped) with the conventional acceleration gain.
However, when the acceleration feedback gain is made larger than the optimally adjusted value, the torque (or thrust) generated by the electric motor increases as the static friction is overcome, and the electric motor 3 moves.
Therefore, although the arm tip (loading machine) is stopped, the electric motor 3 fluctuates at the stop position, so that the movable table 12 of the single-axis arm performs an inadvertent operation and cannot be positioned as a machine.

An example of experimental data when the vibration suppression control by the conventional acceleration feedback shown in FIG. 1 is performed is shown in FIG. FIG. 2 shows the position error waveform of the load machine tip position and the electric motor, and the load machine tip position was measured for displacement using a laser length measuring device (displacement meter). In the figure, the vertical axis is the displacement, and the horizontal axis is the time axis.
According to FIG. 2, the load machine tip position (arm tip) is completely stopped.
The motor position deviation is not stable when entering or leaving the positioning completion width.
In this case, since the electric motor is out of the positioning completion width, the controller 3 does not determine that the positioning is complete, and there arises a big problem that it is not possible to proceed to the next positioning operation even though the arm tip is stopped.
Thus, in the prior art, when the acceleration feedback gain is increased, even if the motor stops, the acceleration sensor detects a minute signal when the arm moves slightly, and as a result, the motor operates and is therefore movable. There was a case where a malfunction occurred that the table was operated.
An object of the present invention is to prevent such a malfunction by preventing an electric motor from operating even when an acceleration sensor detects a minute signal.

FIG. 3 is a control block diagram of the motor control device of the present invention.
In the figure, 1 is a machine having mechanical resonance characteristics, 2 is an acceleration detection unit, 3 is an electric motor, 21 is an electric motor control device for controlling the electric motor 3, 4 is an electric motor drive unit, 5 is an electric motor speed detection unit, and 6 is an electric motor speed. A control unit, 7 is a phase adjustment unit, 8 is a dead zone for zeroing a signal equal to or less than a preset value, 9 is an acceleration feedback gain unit, 10 is an electric motor position control unit, and 31 is an electric motor position detection unit.
As described above, the first embodiment is characterized in that the dead zone 8 is provided between the phase adjustment unit 7 and the acceleration feedback gain unit 9 with respect to the prior art described in FIG.

FIG. 4 is a flow chart (a) for explaining the operation of the dead zone 8 of FIG. 3 and its operation characteristic chart (b). 3A, when the output signal of the phase adjustment unit 7 in FIG. 3 is input to the dead zone 8, if the absolute value of the output signal of the phase adjustment unit 7 is larger than the preset absolute value in the dead zone 8, The output (the output signal of the phase adjustment unit 7) is input to the acceleration feedback gain unit 9 of FIG. 3, and conversely, if the output signal of the phase adjustment unit 7 is equal to or less than a preset value, the output is set to 0 in FIG. The signal is output to the acceleration feedback gain unit 9.
In FIG. 5B, the horizontal axis represents input, the vertical axis represents output, and the horizontal axis has predetermined thresholds on both the positive and negative sides. If the input is within the threshold range, the output is 0. When the input exceeds the threshold value, an output proportional to the input size is output. The same applies to the negative input side.
In this way, when the output signal of the phase adjustment unit 7 is input to the dead zone 8 in FIG. 3, the dead zone 8 is not the first time that the absolute value of the output signal of the phase adjustment unit 7 is greater than the preset absolute value. The output is output to the acceleration feedback gain unit 9.
Therefore, if the output signal of the phase adjustment unit 7 is larger than a preset value, the output of the dead zone 8 is sent to the acceleration feedback gain unit 9, and the output of the acceleration feedback gain unit 9 is fed back to the motor speed control unit 6. Desired feedback control is performed.
However, when the acceleration sensor detects a minute signal due to slight movement of the arm 13 even when the motor 3 is stopped, the dead zone portion 8 does not output to the acceleration feedback gain portion 9, and subsequent feedback control. Is not performed, and the electric motor 3 remains stopped.

FIG. 5 shows an example of experimental data when the vibration suppression control by acceleration feedback according to the present invention shown in FIG. 3 is performed. FIG. 5 shows the position error waveform of the load machine tip position and the electric motor, and the load machine tip position was measured using a laser length measuring device as in FIG.
In the figure, the vertical axis is the displacement, and the horizontal axis is the time axis. According to this figure, although the load machine front end position (arm front end) slightly fluctuates, the motor position deviation goes into the stationary state after entering the positioning completion width and is in a stable state.
As described above, in the prior art, when the acceleration feedback gain is increased, the acceleration sensor detects a minute signal when the arm moves slightly even when the motor is stopped. As a result, the motor malfunctions and the motor is positioned. In some cases, the vibration of the machine 1 may increase due to malfunction of the electric motor. However, in the present invention, the dead zone 8 is detected even if the acceleration sensor detects a minute signal. Thus, the motor does not malfunction, and the vibration of the machine 1 having the mechanical resonance characteristic as shown in FIG. 5 can be almost completely eliminated, and at the same time, the positioning of the motor can be completed.
In the embodiment of FIG. 3, the dead zone 8 is described between the output side of the phase adjustment unit 7 and the input side of the acceleration feedback gain unit 9, but the dead zone is provided on the output side of the acceleration feedback gain unit 9. Even if 8 is inserted, the same effect can be obtained. Alternatively, even if the dead zone 8 is provided on the input side of the phase adjustment unit 7, the same effect can be obtained. That is, the same effect can be expected if a dead zone is put in the feedback path of the acceleration signal including the phase adjusting unit 7 and the acceleration feedback gain unit 9.
Thus, according to the present invention, after adjusting the phase of the acceleration sensor attached to the portion with the largest mechanical vibration, the mechanical vibration can be suppressed by multiplying the gain and feeding back to the speed command. If it is too much, vibration of position deviation is generated. Therefore, a dead zone is provided before multiplying the gain so as to suppress both mechanical vibration and vibration of position deviation at the same time, so that the vibration of the machine 1 having mechanical resonance characteristics is suppressed. It is possible to complete the positioning of the motor at the same time that it is almost completely eliminated.

It is a control block diagram of the electric motor control apparatus which is a prior art of this invention. 2 is a position deviation waveform of a load machine tip position and a motor when vibration suppression control by acceleration feedback according to the prior art of FIG. 1 is performed. It is a control block diagram of the motor control device of the present invention. FIG. 4 is a flowchart (a) for explaining the operation of the dead zone in FIG. 3 and its operation characteristic diagram (b). FIG. 4 is a position deviation waveform of a load machine tip position and a motor when vibration suppression control by acceleration feedback according to the present invention of FIG. 3 is performed. 1 is a structural diagram illustrating an example of a machine to which the present invention is applied. It is a control block diagram of the conventional electric motor control apparatus. It is a figure which shows the speed detection part of an electric motor. FIG. 8 is a position deviation waveform diagram of the load machine tip position and the motor when the conventional motor position control device shown in FIG. 7 is used.

Explanation of symbols

1 Machine 2 Acceleration detector (sensor)
DESCRIPTION OF SYMBOLS 3 Motor 4 Motor drive part 5 Motor speed detection part 6 Motor speed control part 7 Phase adjustment part 8 Dead zone part 9 Acceleration feedback gain part 10 Motor position control part 11 Machine drive element 12 Movable table 13 Load machine (arm)
21 Electric motor control device 31 Electric motor position detection unit 32 Detection position differentiation unit

Claims (2)

A machine having mechanical resonance characteristics and an electric motor driving the machine,
An acceleration detector for detecting the acceleration of the machine including vibrations due to resonance characteristics;
An electric motor drive unit for controlling the torque (thrust) of the electric motor;
An electric motor speed detecting unit for detecting the speed of the electric motor;
A motor speed control unit that feeds back the speed of the motor speed detection unit and outputs a torque command to the motor drive unit;
An electric motor position detecting unit for detecting the position of the electric motor;
An electric motor position controller that feeds back the position of the electric motor position detector and outputs a speed command to the electric motor driver;
A phase adjustment unit for adjusting the phase of the acceleration signal output by the acceleration detection unit;
In the motor control device configured by an acceleration feedback gain unit that feeds back the output of the phase adjustment unit to the motor speed control unit,
An electric motor control apparatus comprising: a dead zone for setting a signal equal to or less than a preset value to zero between an output side of the phase adjustment unit and an input side of the acceleration feedback gain unit. A machine having mechanical resonance characteristics and an electric motor driving the machine,
An acceleration detector for detecting the acceleration of the machine including vibrations due to resonance characteristics;
An electric motor drive unit that controls torque (thrust) of an electric motor that drives the machine;
An electric motor speed detecting unit for detecting the speed of the electric motor;
A motor speed control unit that feeds back the speed of the motor speed detection unit and outputs a torque command to the motor drive unit;
An electric motor position detector for detecting the position of the electric motor;
An electric motor position controller that feeds back the position of the electric motor position detector and outputs a speed command to the electric motor driver;
A phase adjustment unit for adjusting the phase of the acceleration signal output by the acceleration detection unit;
In the mechanical vibration suppression method of the motor control device configured with an acceleration feedback gain unit that feeds back the output of the phase adjustment unit to the motor speed control unit,
When the output of the phase adjustment unit is equal to or less than a preset value, the input signal to the acceleration feedback gain unit is set to zero.

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