JPH09261989A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent calculation error of a motor control signal due to disturbance of an encoder output pulse to realize the speed control in higher accuracy by providing a control means which executes speed control operation from the time where the predetermined time has passed without execution of the speed control operation when the motor is started and for the predetermined period from change of speed. SOLUTION: A microprocessor (CPU) 11 executes the speed control after the predetermined time has passed, without execution of the speed control during the predetermined time, on the occasion of executing the drive frequency control or PWM control depending on the target speed. Thereby, during the predetermined period where a pulse signal of a sensor 20 is disturbed, the speed control operation is not executed even when the CPU 11 inputs a pulse signal and when the operation returns to the normal condition, the CPU 11 inputs a pulse signal to calculate the actual speed of the motor. As a result, the speed control is performed in the higher accuracy depending on the preset target speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for controlling speed by using output pulses of an encoder for detecting motor rotation.

[0002]

2. Description of the Related Art There is a motor control device provided with an encoder for detecting a motor rotation, and feeding back an output pulse of the encoder to control a speed. Such a motor control device is provided with control means for setting a desired motor speed (target speed), and this control means increases the motor speed in accordance with a target speed setting signal, and While decelerating, the encoder output pulses are counted to monitor whether or not the actual speed of the motor reaches the target speed.

[0003]

In the motor controller as described above, the output pulse of the encoder is disturbed immediately after the motor is started or the speed is changed. That is, immediately after start-up or immediately after speed change, a response delay occurs in the encoder, and an overshoot or undershoot occurs in the motor speed, so the encoder output pulse is increased. Is in a disordered state.

For this reason, when the motor control signal is calculated by counting the output pulses of the encoder, an error occurs in the calculated value, and there is a problem that accurate speed control cannot be performed.

Therefore, an object of the present invention is to propose a motor control device capable of controlling the speed with high accuracy in accordance with a set target speed.

[0006]

SUMMARY OF THE INVENTION In the present invention, however, the output pulse of the encoder for detecting the motor rotation is counted to monitor the motor speed, and the speed control is performed according to the target speed to be set. The present invention relates to a motor control device.

In the present invention, there is provided a control means for performing speed control operation from the start of the motor and speed change for a predetermined time after the speed change, and after the predetermined time has elapsed. ing.

In the motor control device having such a configuration, even if the encoder output pulse is disturbed immediately after the motor is started or the speed is changed, the control means does not perform the speed control operation for the predetermined time, and the predetermined speed control operation is performed. After the output pulse returns to normal due to the passage of time, the output pulse is counted and the motor speed is monitored. Therefore, there is no error in the calculation of the motor control signal, and the speed control can be performed with high accuracy. it can.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a circuit of a motor control device. A required rotation speed (target speed) of the ultrasonic motor 10 is set in a CPU (microprocessor) 11, and a voltage signal according to this set value is generated by the CPU 11 To V
It is sent to the / f conversion / sawtooth wave generation circuit 12 as an fD / A signal. The CPU 11 sets the D / A according to the set value.
By changing the setting input, the f.D / A signal generator (for example, a register) outputs the f.D / A signal whose voltage level changes.

The V / f conversion / sawtooth wave generation circuit 12 is a CPU
The voltage signal input from 11 is subjected to voltage-frequency conversion to create a sawtooth signal of frequency fn, which is sent to the distributor 13. The divider 13 shapes the sawtooth wave signal of fn into a rectangular wave while delaying the phase by 90 ° by the clock of 4fn, and divides it into four. That is, a rectangular wave signal is output from φ3 with a phase delay of 90 ° from φ1, a phase of 90 ° from φ3, a phase of φ2 from φ2, and a phase of 90 ° from φ2.

The four-divided rectangular wave signal is the AND circuit 14
It is input to the first input terminals of a to 14d. Also, the ultrasonic motor 1 is connected to the second input terminals of the AND circuits 14a to 14d.
An ON / OFF signal of 0 is input, and the pulse frequency signals output from the AND circuits 14a to 14d during the gate opening are amplified by the transistors 15a to 15d.
Input to the base.

The collectors of the transistors 15a and 15b are connected to both ends of the primary coil of the step-up transformer 16, and the collectors of the transistors 15c to 15d are the step-up transformer 1.
7 are connected to both ends of the primary coil, respectively. The output terminals of the secondary coils of the step-up transformers 16 and 17 are connected to the ultrasonic motor 10.

Further, according to the target speed set in the CPU 11, the P / D for PWM control is controlled by the CPU 11.
/ A signal is output and this P · D / A signal is compared.
The data is sent to the first input terminal of the input terminal 19. In addition,
The CPU 11 changes the D / A setting input according to the speed setting value P. The voltage level changes from the D / A signal generator P.
D / A signal is output.

Then, the comparator 19 inputs the sawtooth wave signal sent from the V / f conversion / sawtooth wave generation circuit 12 to the second input terminal and outputs P as a result of comparison with the P.D / A signal.
It outputs a WM signal.

2 and 3 show a PWM signal output from the comparator 19, and FIG. 2 shows a case where the P.D / A signal is set to "0" volt and the PWM signal is fully output. Shows the case where the P · D / A signal is raised to limit the PWM signal.

The PWM signal output from the comparator 19 in this manner is input to the third input terminals of the AND circuits 14a to 14d. That is, as shown in FIG. 4, each AND circuit 14a to 14d inputs the above-mentioned PWM signal,
The pulse frequency signals Pa1, Pa2, Pb1, Pb2 whose pulse widths are changed according to the M signal are output.

Further, the motor controller is equipped with a sensor 20 for detecting the actual rotation speed of the ultrasonic motor 10. The sensor 20 can be composed of an impeller rotated by the ultrasonic motor 10 and a photo interrupter outputting a pulse signal in accordance with the rotation of the impeller. This sensor 20 is provided as an encoder for sending a pulse signal according to the actual speed of the ultrasonic motor 10 to the CPU 11, and the CPU 11 inputs the output pulse of this encoder, and counts the pulse to obtain an ultrasonic wave. The actual speed of the sound wave motor 10 is monitored.

The motor control device thus implemented is
Frequency of power supply pressure (driving frequency) with constant WM signal
Is operated as the first control for changing the speed, and conversely, the second control for changing the speed by changing the PWM signal while keeping the driving frequency constant.

When the PWM signal is constant (for example, full output as shown in FIG. 2) and the speed is controlled by the driving frequency, the f.D / A setting input of the CPU 11 is changed to change the speed setting value. As a result, fD /
A signal from CPU 11 to V / f conversion / sawtooth wave generation circuit 12
Since the f · D / A signal is subjected to voltage-frequency conversion, a sawtooth signal having a frequency of fn is sent to the distributor 13.

As described above, the distributor 13 delays the rectangular wave signal by 90 ° and inputs it to the first input terminals of the AND circuits 14a to 14d. At this time, therefore, the second inputs of the AND circuits 14a to 14d are input. If the ON signal is input to the terminals, the AND circuits 14a to 14d output the pulse frequency signals Pa1, Pa2, Pb1, and Pb2.

Therefore, the transistors 15a to 15d are rendered conductive in the order in which the pulse frequency signals are base-inputted, and the primary coil current flows through the step-up transformers 16 and 17. As a result, the output voltage induced in the secondary coils of the step-up transformers 16 and 17 is applied to the ultrasonic motor 10 as the feeding pressures Va and Vb, and the frequencies (driving frequencies) of the feeding pressures Va and Vb are followed. Ultrasonic motor 1 at rotation speed
0 rotates.

If the target speed is changed by changing the speed setting value of the CPU 11, the power feeding pressures Va, V are changed according to this setting value.
Since the frequency of b changes, the rotation speed of the ultrasonic motor 10 increases or decreases according to the frequency.

When the speed is controlled by the PWM signal while keeping the driving frequency constant, the voltage level of the P.D / A signal changes according to the target speed set in the CPU 11,
Therefore, the PWM signal having the pulse width determined by the P · D / A signal is input to the third input terminals of the AND circuits 14a to 14d. From this, the transistors 15a-1
The pulse frequency signal input to the 5d base is P ・ D / A
The effective values of the feed pressures Va and Vb output from the step-up transformers 16 and 17 are modulated according to the signal, and the rotation speed of the ultrasonic motor 10 is increased toward the set target speed and decelerated. To do.

While the speed is being controlled as described above, the pulse signal according to the actual speed of the ultrasonic motor 10 is transmitted to the sensor.
It is input to the CPU 11 from 20 and the CPU 11 judges the state of the actual speed from the count processing of this pulse signal, and detects an inappropriate control range or control point of speed control. For example, if the motor becomes low speed due to the speed control by the drive frequency and the motor speed does not change even if the drive frequency is changed, the CPU 11 sets the PWM as the limit point of the control amount.
Switch to speed control by control.

When the drive frequency control or the PWM control is performed according to the set target speed, the CPU 11 operates so as not to control the speed for a predetermined time but to control the speed after the lapse of the predetermined time.

That is, when the motor speed changes due to the speed control, the response delay of the sensor 20, the overshoot or the undershoot of the motor speed, etc., as described above. The pulse signal sent from the sensor 20 is disturbed, but during the predetermined time when the pulse signal is disturbed, the speed control operation is not performed even if the CPU 11 inputs the pulse signal. Then, when the pulse signal of the sensor 20 returns to normal, the CPU 11 inputs the pulse signal and calculates the actual speed of the motor.

On the other hand, when the actual speed deviates from the target speed, the CPU 11 outputs the f.D / A signal or the P.D / A signal corrected based on the deviation amount as a motor control signal. Therefore, by counting the pulse signal of the sensor 20 as described above, a highly accurate motor control signal is output.

FIG. 5 shows a time chart when the drive frequency is changed to control the speed. As can be seen from this figure, f is set according to the target speed set in the CPU 11.
When the D / A signal rises, the motor rotation speed increases, but at this time, the rotation speed becomes overshooting and then becomes stable.

Therefore, the pulse signal of the sensor 20 becomes abnormal due to its overshoot, but C
The PU 11 does not perform the speed control operation during the predetermined time T including the time when the pulse signal is disturbed. Then, counting is started from the time when this time T has elapsed, and the actual speed data is calculated from the count value. The predetermined time T is, for example, 5 to 1
It is preferably set to 0 msec.

Further, since the overshoot of such a motor rotation speed occurs immediately after the motor is started, in the present embodiment, from the time when a predetermined time elapses after the motor is started. The CPU 11 is configured to monitor the motor speed from the pulse signal of the sensor 20.

FIG. 6 shows a case where the motor speed is undershooted due to the down of the fD / A signal.
In this case as well, the CPU 11 performs the speed control operation by the pulse signal after the elapse of the predetermined time T, so that it is not affected by the disturbance of the pulse signal caused by the undershoot.

Although one embodiment of the control device for the ultrasonic motor has been described above, the present invention is not limited to the ultrasonic motor and is similarly implemented as a control device for various other motors. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit example of a motor control device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an output operation of a PWM signal when the P · D / A signal is set to “0” volt.

FIG. 3 is an explanatory diagram showing an output operation of a PWM signal when a P · D / A signal is raised.

FIG. 4 is a time chart of a pulse frequency signal whose pulse width is modulated according to a P · D / A signal.

FIG. 5 is a sensor generated immediately after increasing the motor speed.
Disturbance of output pulse signal and C inputting the pulse signal
It is a wave form diagram which shows operation | movement of PU.

FIG. 6 is a waveform diagram similar to FIG. 5, showing the operation of the CPU immediately after the motor speed is reduced.

[Explanation of symbols]

 10 Ultrasonic Motor 11 CPU 12 V / f Conversion / Sawtooth Wave Generation Circuit 13 Distributor 14a to 14d AND Circuit 15a to 15d Transistor 16, 17 Step-up Transformer 19 Comparator 20 Sensor-

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoichi Miyauchi 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Works (72) Inventor Go Okutani 2-chome Tamagawadai, Setagaya-ku, Tokyo No. 9 Inside Kyocera Corporation Tokyo Yoga Works

Claims (1)

[Claims] 1. A motor control device for monitoring the motor speed by counting output pulses of an encoder for detecting motor rotation and controlling the speed according to a target speed to be set. A motor control device comprising a control means for performing a speed control operation from a time point when the predetermined time elapses without performing the speed control operation for a predetermined time from the start-up and the speed change.