JPH0531389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a motor control device that can set the rotational speed of a motor to a desired value.

(Prior Art) FIG. 1 is a diagram showing an example of a conventional motor control device of this type. In this figure, the rotation speed of the motor M is converted by an encoder EC into a pulse train signal having a frequency corresponding to the rotation speed. This pulse train signal is passed through a frequency-voltage converter (hereinafter referred to as F/
It is converted to DC voltage B by FVC (abbreviated as V converter), the difference from the set value R is determined by subtracter SUB, and this difference voltage is amplified by servo amplifier SA.
This is the driving voltage for the motor M. In such a servo mechanism, the output of the subtracter SUB is automatically controlled to be zero, and by changing the set value R, the rotation speed of the motor can be changed accordingly.

However, in such conventional motor control devices, the constants of the system that converts the rotation speed of the motor M into DC and provides feedback (F/V converter composed of a monomulti, filter, etc.) and the aging of elements, The F/V conversion rate of the F/V converter changes due to temperature changes, the temperature characteristics of the resistance, etc. in the setting device (usually the reference voltage is divided by a resistor), and changes over time. There was a drawback that the motor rotation speed varied for the same set value.

The present invention has been made in view of these drawbacks, and an object of the present invention is to provide a motor control device that can always control the motor to a desired rotation speed.

(Structure of the Invention) The structure of the present invention that achieves this object is a motor control device that performs rotation control to rotate the motor at a desired rotation speed and rotation calibration to accurately perform this rotation control. a set voltage generation means for generating a set voltage for rotating the motor at a desired rotation speed; a rotation speed signal generation means for generating a rotation speed signal corresponding to the rotation speed of the motor; and a rotation speed signal generating means for generating a rotation speed signal according to the rotation speed signal; and a calculation means that receives the set voltage and the voltage signal and generates a control voltage for rotation control during rotation control, and generates a calibration signal during rotation calibration. and driving means for driving the motor based on the control voltage; and oscillation for generating a rotation speed signal substantially equal to the rotation speed signal generated by the rotation speed signal generation means when the motor rotates at a desired rotation speed. and a calibration signal generated by the calculation means that receives the voltage signal generated by the voltage signal generation means that receives the rotation speed signal from the oscillation means and the set voltage generated by the set voltage generation means becomes a predetermined value. a set voltage control means for controlling the set voltage generation means, and a set voltage control means for supplying a rotation speed signal from the oscillation means to the voltage signal generation means during rotation calibration, and supplying a calibration signal from the calculation means to the set voltage control means. switching means for switching to supply the rotation speed signal from the rotation speed signal generation means to the voltage signal generation means and supply the control voltage from the calculation means to the drive means during rotation control; It is characterized by having the following.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a configuration diagram showing an embodiment of the present invention. In the figure, MM is a monomulti, and a switch
The output (rotation speed signal) of the encoder EC selected by SW1 or _the oscillator OSC is energized at the rising edge of the reference clock, and outputs a pulse signal with a pulse width determined by the time constant _R1.C1 . This pulse output is smoothed by a filter FL and then guided as a voltage signal to an adder ADD.
μCP is a microcomputer and a D/A converter.
Outputs data that gradually changes (increases or decreases) from zero for DA. The output (set voltage) of this D/A converter DA is led to an adder ADD.
CMP is a comparator that compares the output (calibration signal) of the adder ADD obtained via switch SW2 with zero, and when they match, the microcomputer μCP
A stop signal is given to stop the output change. It should be noted that the adder ADD can be configured to have an integral function or a simple addition function by connecting or not connecting a capacitor to the feedback path (selectable by switch SW3). Furthermore, the output of the adder ADD is
SW2 allows the motor to be guided to the servo amplifier SA during actual motor control. Note that the microcomputer μCP and the D/A converter DA constitute a set voltage generation means for generating the set voltage,
The encoder EC constitutes a rotation speed signal generation means that generates a rotation speed signal, the monomulti MM and the filter FL constitute a voltage signal generation means that generates a voltage signal according to the rotation speed of the motor, and the adder
ADD constitutes a calculation means that generates a control voltage for rotation control during rotation control and also generates a calibration signal during rotation calibration, servo amplifier SA constitutes drive means that drives the motor, and oscillator
The OSC constitutes an oscillation means, the switch SW1 and the switch SW2 constitute a switching means, and the comparator CMP constitutes a set voltage control means for controlling a set voltage generating means.

The operation of the motor control device having such a configuration will now be described with reference to FIG. The rotation speed of motor M is determined by the encoder attached to the motor shaft.
Pulse train signal output from EC (a in Figure 3)
is converted to a DC level using a monomulti MM and a filter FL, and this is used as the feedback amount. Therefore, the rotation speed of the motor can be seen as the pulse train frequency of the encoder.
Now, if the encoder EC is 10 pulses/rotation,
60r.pm can be replaced by a frequency of 10p.ps. Now, by flipping switch SW1 to the oscillator OSC side and inputting a 10p.ps pulse, the circuit can simulate the operation when the motor is rotating at 60rpm. Therefore, first, the operation when determining the set value will be explained. A clock corresponding to the output frequency of the encoder EC (b in Figure 3) is sent from the oscillator OSC to the monomulti MM via switch SW1.
Enter. Mono-multi MM output (Figure 3c)
is converted into a DC voltage as shown in FIG. 3d by the filter FL, and is applied to the adder ADD. The adder ADD is set to function as a simple adder by an internal switch SW3, and is set to function as a simple adder.
Microcomputer μCP via A converter DA
The output of the filter FL (FIG. 3 d) is added to the voltage (FIG. 3 f) that gradually decreases from the zero level given by . The added value is input to the comparator CMP via switch SW2, and when the added value becomes zero, that is, when the set value given by the D/A converter DA and the absolute value of the output of the filter FL become equal, The output of comparator CMP is
As shown in FIG. 3e, the signal falls from "H" to "L". As a result, the microcomputer μCP stops changing its output (f in FIG. 3) and fixes the output value as the set value. In other words, if the output of the filter FL changes due to changes in circuit constants,
The set value is determined in conjunction with this. Therefore, the influence of changes in circuit constants is absorbed.

Next, the operation when the motor is actually driven will be explained. Connect switch SW1 to the encoder EC side and switch SW2 to the servo amplifier SA side.
Switch SW3 is opened and the adder ADD also has an integral function. With this switch setting, the feedback voltage corresponding to the rotation speed of the motor M is input to the adder ADD and matched with the set value, and the motor M is adjusted so that the difference becomes zero.
The rotation speed is automatically controlled. At this time, since the set value has been calibrated as described above, the rotational speed does not fluctuate due to changes in circuit constants.

In addition, when rotating at other rotation speeds, use an oscillator.
This is done by changing the frequency of the clock from the OSC. As the variable frequency oscillator OSC, one composed of a crystal oscillator and a frequency divider is suitable, and the desired frequency can be obtained by changing the frequency division ratio of the frequency divider.

Next, a specific example of the control circuit shown in FIG. 2 will be described. First, the filtered level of the mono-multi MM is set to a constant so that it outputs 5V at a motor rotation speed of 3000 rpm, and as the motor rotates forward and reverse, this output changes between positive and negative. Let it change. Also, as a D/A converter DA
Using 12bit, binary code
Make it possible to output ±5V centered on 100000000000 (±0.05% resolution).

Here, suppose the motor rotation speed is 600 r.p.
If you want m., if the encoder EC outputs 500 pulses per revolution, you can give 5KHz oscillation output from the oscillation OSC to the mono multi MM, and the output of the filter FL is approximately -1V. It should be. Therefore, the input of the D/A converter DA is
When increasing bit by bit from 100000000000, the output of comparator CMP reaches a certain value (approximately 1V)
It drops to zero level. D/A converter DA at this time
If you memorize the input to the motor and output it as a set value during actual operation, the motor will rotate with an accuracy of ±0.05%.

If the rotation direction is reversed, the output of the filter FL may be inverted and the output of the D/A converter DA may be set to a negative value.

(Effects of the Invention) As explained above, according to the present invention, set values are calibrated to offset fluctuations caused by aging of constants and elements in the feedback system in the servo circuit, setting devices, etc., temperature changes, etc. Because
The motor can be rotated at a desired rotation speed without being affected by these fluctuations.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a conventional motor control device, FIG. 2 is a circuit diagram showing an embodiment of a motor control device according to the present invention, and FIG. 3 is an operating waveform of each part of the device shown in FIG. It is a diagram. SA...Servo amplifier, M...Motor, EC...
...Encoder, MM...Mono multi, OSC...
Oscillator, FL...filter, μCP...microcomputer, DA...D/A converter, ADD...
Adder, CMP...Comparator, SW1, SW
2, SW3...Switch.

Claims (1)

[Scope of Claims] 1. In a motor control device that performs rotation control for rotating a motor at a desired rotation speed and rotation calibration for accurately performing this rotation control, settings for rotating the motor at a desired rotation speed. A set voltage generating means for generating a voltage; a rotation speed signal generating means for generating a rotation speed signal according to the rotation speed of the motor; and a voltage generating means for generating a voltage signal according to the rotation speed of the motor based on the rotation speed signal. a signal generation means; a calculation means for receiving the set voltage and the voltage signal to generate a control voltage for rotation control during rotation control and to generate a calibration signal during rotation calibration; oscillating means for generating a rotational speed signal substantially equal to a rotational speed signal generated by the rotational speed signal generating means when the motor rotates at a desired rotational speed; and rotation from the oscillation means. The set voltage generating means is controlled so that the calibration signal generated by the arithmetic means that receives the voltage signal generated by the voltage signal generating means that receives the number signal and the set voltage generated by the set voltage generating means becomes a predetermined value. a set voltage control means for supplying a rotation speed signal from the oscillation means to the voltage signal generation means during rotation calibration, and supplying a calibration signal from the calculation means to the set voltage control means; A motor characterized by comprising switching means for switching to supply a rotational speed signal from a number signal generating means to the voltage signal generating means and supplying a control voltage from the calculating means to the driving means. Control device.