JP5412726B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device that controls a motor using torque feedforward.

  When high-speed responsiveness of position control or speed control is required, such as a component mounting machine or a machine tool, there is a limit to the responsiveness only with the usual feedback control. Therefore, the above problem is solved by using both feedforward control and feedback control.

For example, a method has been proposed for improving the responsiveness by speed feedforward control in which the position command is differentiated once to the speed command or torque feedforward control in which the speed command is differentiated once to the torque command. (For example, refer to Patent Document 1).
JP-A-9-171410

  However, in the above-described technique, the velocity feed-forward is differentiated once, and the torque feed-forward is further differentiated the velocity corresponding to the position differentiation once, which is easily affected by noise. Although a first-order lag filter is used to remove the noise component, the response must be sacrificed by this, and there is a problem that the high-speed response performance that is the original purpose cannot be fully exhibited. is there.

  In particular, in torque feedforward in speed control, the speed command is often an analog input from the outside, the noise component becomes extremely large, and torque feedforward control may not function normally.

  The present invention solves the above-described conventional problems, and provides a motor control device that minimizes the delay time for removing the noise component superimposed on the torque feedforward output and maximizes the performance of the torque feedforward function. The purpose is to do.

  The motor control device according to claim 1 is a motor control device that controls the speed of the motor to coincide with the speed command value, and includes a position detection unit that detects a position of the motor and a position detected by the position detection unit. Speed calculation means for calculating the motor speed, speed control means for controlling the difference between the speed command and the motor speed detected by the speed calculation means to be zero, and the speed command is input to be differentiated once, Torque feed forward gain is applied, torque feed forward calculation means for torque feed forward output, filter means for filtering the torque feed forward output to obtain filter output, and input of the filter output, correction value The correction means outputs a threshold value in which the absolute value of the filter output is set in advance. Remote and corrected output 0 if small, in the case large performs processing to output as the filter output, and an output and the output torque command those obtained by adding the correction means of the speed control means.

  In the motor control device according to claim 2, the threshold value is set by a parameter with a maximum value (noise component) of the filter output when the acceleration is zero.

  According to the motor control device of the first and second aspects, the time constant of the first-order lag filter can be minimized by the correction process, and the performance of the torque feedforward function can be maximized.

  According to the motor control device of the second aspect, the threshold value can be easily adjusted by the parameter.

The position detection means for detecting the position of the motor, the speed calculation means for calculating the motor speed from the position detected by the position detection means, and the difference between the speed command and the motor speed detected by the speed calculation means is set to zero. Speed control means for controlling to perform, torque feed forward calculating means for differentiating once by inputting the speed command, multiplying the torque feed forward gain to obtain torque feed forward output, and filtering the torque feed forward output Filter means for providing a filter output, and a correction means for inputting the filter output and outputting a correction value, wherein the correction means has an absolute value of the filter output smaller than a preset threshold value. 0 is used as the correction output, and when it is large, the filter output is output as it is. What the output of the degree control means by adding the outputs of said correction means and a torque command.
(Embodiment 1)
Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a block diagram of a main control part in the motor drive apparatus of the present invention.

  In FIG. 1, a speed command 11 is input to the torque feedforward calculation means 1, and an acceleration command is calculated by differentiating once, and converted to a torque unit by multiplying the acceleration command by (motor inertia + load inertia). Then, it is output as a torque feed forward output 12. The torque feedforward output 12 is input to the filter unit 2, performs filter processing such as a first-order lag filter, and outputs the filter output 13 to the correction unit 3. The correction means 3 outputs a correction output 14 with respect to the input filter output 13 according to a threshold value described later.

  The speed control means 4 outputs a speed control output 16 for controlling a speed deviation 15 that is a difference between the speed command 11 and the motor speed 18 to zero. The position detection means 5 detects the motor position 17 from a position detector such as an encoder or resolver. The speed calculation means 6 detects the motor speed 18 from the difference of the motor position 17.

  The motor control device according to the present invention is characterized in that the torque command 19 is obtained by adding the correction output 14 obtained by processing the output of the filter means 2 with the threshold value of the correction means 3 and the speed control output 16 of the speed control means 4. It is. Except for the correction means 3, the speed control configuration is provided with a general torque feed forward function.

  In a general torque feedforward configuration, noise components included in the torque feedforward output 12 calculated by one-time differentiation of the speed command are removed only by the filter means 2 such as a first-order lag filter. The time constant of this first-order lag filter is adjusted according to the magnitude of the noise component. Especially when the speed command is configured to easily superimpose noise components, such as analog input from the outside, The constant needs to be quite large. Increasing the filter time constant means that the effect of improving the speed response, which is the original purpose of torque feedforward, is greatly impaired.

The motor control device of the present invention can suppress the delay of the filter due to noise removal to a minimum by adding the correction means 3 to the conventional configuration, and as a result, the effect of improving the speed responsiveness by torque feedforward. Can be maximized.

  Hereinafter, the correction means 3 will be described in detail. The correction means 3 sets the correction output 14 to 0 when the filter output 13 is less than or equal to the threshold value, and outputs the value of the filter output 13 as it is as the correction output 14 when it is larger than the threshold value (see FIG. 2). That is, the torque feed forward function is disabled only when the filter output 13 is smaller than the threshold value. The reason why the effect of improving the speed response by the torque feed forward function is not impaired by this correction processing will be described next.

  In the torque feedforward function, a torque value corresponding to the acceleration is added to the output of the speed feedback control process, but the speed responsiveness can be improved to some extent by the speed feedback control itself.

  FIG. 3 is a graph for explaining the relationship between responsiveness (vertical axis) and acceleration (horizontal axis) when only speed feedback control is performed and when a torque feedforward function is added.

  In FIG. 3, the response of 1 means that the response is made without delay. By adding the torque feed forward function, the responsiveness can be improved up to a region where acceleration is large. That is, when the acceleration is small, speed response can be achieved by speed feedback control without a torque feed forward function.

  It can be considered that the necessity of torque feedforward can be switched according to the magnitude of acceleration, that is, the magnitude of the filter output 13. Further, when the acceleration is small, the influence of the noise component is large. However, as the acceleration increases, the ratio of the noise component to the basic component decreases, so that the influence of the noise becomes difficult.

  As described above, the correcting unit 3 can switch between setting the correction output to 0 or outputting the filter output value as it is depending on the size of the filter output 13, and can hardly be affected by noise.

  As a result, the time constant of the first-order lag filter by the filter means 2 can be minimized, and as a result, the deterioration of the speed response in the region where the effect of the torque feedforward function is truly required is minimized. Can do.

  Further, regarding the threshold value used in the correction means 3, the filter output 13 when the acceleration is 0 is a component due to noise. Therefore, the influence of the noise component can be eliminated by setting the maximum value at that time as the threshold value. Further, it is desirable that the threshold setting method can be adjusted by providing it as a parameter.

  The motor driving device of the present invention is useful for a device in which a speed command is an analog input from the outside and a noise component is easily superimposed.

The block block diagram of the control principal part in Embodiment 1 of this invention Explanatory drawing of filter output (threshold value) and correction output in correction means of the present invention Comparison of speed feedback and torque feed forward functions

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torque feedforward calculation means 2 Filter means 3 Correction means 4 Speed control means 5 Position detection means 6 Speed calculation means 11 Speed command 12 Torque feedforward output 13 Filter output 14 Correction output 15 Speed deviation 16 Speed control output 17 Motor position 18 Motor Speed 19 Torque command

Claims (2)

In the motor control device that controls the motor speed to match the speed command value,
Position detecting means for detecting the position of the motor;
Speed calculating means for calculating a motor speed from the position detected by the position detecting means;
Speed control means for controlling the difference between the speed command and the motor speed detected by the speed calculation means to be zero;
A torque feedforward calculating means for inputting the speed command, differentiating the torque command once, multiplying the torque feedforward gain, and obtaining a torque feedforward output;
Filter means for filtering the torque feedforward output to produce a filter output;
A correction means for inputting the filter output and outputting a correction value;
The correction means performs a process of outputting 0 as a correction output when the absolute value of the filter output is smaller than a preset threshold value, and outputting the filter output as it is when larger.
A motor control apparatus characterized in that a torque command is obtained by adding the output of the speed control means and the output of the correction means.   The motor control device according to claim 1, wherein the threshold value is a parameter that sets a maximum value (noise component) of the filter output when the acceleration is zero.

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