JPH02101983A - Motor controller - Google Patents

Abstract

PURPOSE:To enable highly accurate rotation control by providing an F/V converter for converting the frequency of a speed converter into voltage and driving a unilateral thyristor based on the comparison between the output voltage from the F/V converter and a reference voltage. CONSTITUTION:The motor controller comprises a speed detector 16 for detecting the rotary section of a motor 5, an F/V converting means 38 for converting the output from the speed detector 16 into a voltage, and a drive means for comparing the output voltage from the F/V converting means 38 with a reference voltage corresponding to the rotation of the motor 5 to be controlled and driving a bidirectional thyristor 25. By such arrangement, rotation can be regulated through random regulation of supply voltage of the motor 5. Consequently, highly accurate rotation control can be made regardless of manufacturing fluctuation of the speed detector 16 or the temperature variation and an inexpensive motor controller can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an electric motor that performs accurate rotation speed control.

[Conventional technology]

FIG. 2 is a circuit diagram of a control device for a conventional electric motor disclosed in Japanese Patent Application Laid-Open No. 54-142516. In the figure, 1 is a power supply terminal to which AC 100V power is applied, 2 is a movable contact, 3.4 is a fixed contact, 5 is an electric motor, 6 is a full-wave rectifier, 9 is a thyristor as a voltage control element, 12 is a transistor, 14 16 is a variable resistor for setting to create a reference voltage; 16 is a speed detector that detects the rotational speed of the motor 5;
17 is a bridge for full-wave rectification of the AC output of the speed detector 16, and 23 is a trigger element for the thyristor 9. In addition, 8. -10.15.18.20, 21.22.24 are resistors, 7.13 are capacitors, 11 is diode, 19
is a smoothing capacitor.

Next, the operation will be explained. First, the output voltage of the speed detector 16 which is directly connected to the electric motor 5 and rotates is determined by the bridge 17.
, a resistor 18 and a smoothing capacitor 19 convert it into a DC voltage proportional to the rotation speed of the motor 5, which is differentially applied to the reference voltage set by the setting variable resistor 14 and applied to the base of the transistor 12. The input zero order is
Transistor 12 causes a collector current to flow in inverse proportion to this base voltage to charge capacitor 13. and,
The trigger element 23 fires the thyristor 9 and supplies power to the motor 5 when the charging voltage of the capacitor 13 becomes higher than the voltage set by the resistors 21 and 22.

In this way, since the setting voltage of the setting variable resistor 14 is used as a reference, when the rotational speed of the motor 5 attempts to fluctuate, a control voltage is applied to the transistor 12 to eliminate the fluctuation. Therefore, by changing the charging time of the capacitor 13, the conduction angle of the thyristor 9 is changed, and the voltage supplied to the motor 5 is adjusted to adjust the rotation speed to the set value.

[Problem to be solved by the invention]

However, in such conventional motor control devices, the output voltage changes due to manufacturing variations in the speed detection n16 and changes in temperature, and the correlation between rotation speed and voltage varies widely, making it difficult to achieve the target rotation speed. The disadvantage was that the error was large.

For this reason, a speed detector 16 has been proposed in which the change in output voltage is small due to manufacturing variations or changes in temperature, but this has the disadvantage that the control device becomes expensive.

The present invention has been made to eliminate the above-mentioned drawbacks, and it is possible to control the rotation speed with high precision regardless of variations in the manufacturing process of the speed detector 16 or changes in temperature.
An object of the present invention is to obtain a control device for an electric motor that is constructed at low cost.

[Means to solve the problem]

The electric motor control device according to the present invention includes a speed detector that detects the rotational speed of the electric motor, an F/V converter that converts the output of the speed detector into a voltage, and an output voltage from the F/V converter. and a driving means for driving the bidirectional cyrisk by comparing the voltage with a reference voltage corresponding to the rotational speed of the electric motor to be controlled.

[Effect]

The output of the speed detector is converted into a voltage proportional to the rotational speed of the motor using an F/V conversion means, and this voltage is compared with a reference voltage corresponding to the rotational speed of the motor to be controlled to calculate the bidirectional risk. Drive.

〔Example〕

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

FIG. 1 is a circuit diagram of a motor control device showing an embodiment of the present invention. In FIG. 0, l is a power source, 5 is a motor,
16 is a speed detector that generates an alternating current voltage proportional to the rotation speed of the electric motor 5; 25 is a bidirectional thyrisk that controls the voltage supplied to the electric motor 5; 2G is a triac photocoupler that ignites the bidirectional thyrisk 25; 27, 29.31
is a transistor, 28, 40.41 is a comparator, 3
8 is an F/V converter that inputs the number of pulses and outputs a voltage proportional to the number; 37 is a variable resistor for setting a reference voltage proportional to the target rotation speed; 32 is a reference voltage for variable resistor 37. and the output voltage of the F/V converter 38, a power transformer 33 lowers the voltage of the power supply l, and 34 rectifies and smoothes the AC voltage of the power transformer to produce a DC power supply. A power supply circuit, 35 and 36 are output DC voltage sources, 39 is a rectifier that performs full-wave rectification of one of the secondary voltages of the power transformer, and 42 is an exclusive circuit that converts the rectangular wave output voltage of the comparator 4I into a pulse wave. Target O
It is an R gate IC.

Next, the operation will be explained. First, the rectifier bridge 39
The comparator 40 generates a pulse synchronized with the zero cross of the power supply voltage and turns on the transistor 31, thereby making the charge in the capacitor 30 zero. The charging current of the capacitor 30 is determined by the voltage applied to the base of the transistor 29, and reaches a certain voltage value in a time proportional to the magnitude of the charging current, making the output of the comparator 28 rHJ. The comparator 28
When the output of HJ is input, the transistor 27 is turned on, and further the triac photocoupler 26 is turned on.

As a result, the bidirectional thyristor 25 is turned on and power is supplied to the electric motor 5.

The above operation is performed every pulse signal of the comparator 40, that is, every half wave of the power supply 1. Therefore, if the charging current to the capacitor 30 is small, the time from the zero cross point of the power supply 1 to the firing of the bidirectional thyristor 25 becomes longer, so the power supplied to the motor 5 becomes smaller, and conversely, the charging current to the capacitor 30 becomes longer. When the current is large, the time until the bidirectional thyristor 25 fires becomes short, and the supplied power becomes large. By arbitrarily adjusting the power supplied to the electric motor 5 in this way, the rotation speed can be adjusted.

Here, since the frequency of the output AC voltage of the speed detector 16 directly connected to the electric motor 5 is exactly proportional to the rotation speed of the electric motor 5, a pulse signal proportional to the frequency is sent to the comparator 4.
1 and exclusive OR gate IC42, F/
input to the V converter 38. Then, the F/V converter 38 outputs a DC voltage proportional to the frequency of this pulse signal to the integral calculator 32. Next, the integral calculator 32 outputs a DC voltage proportional to the frequency of this pulse signal to the integral calculator 32. The difference with the output voltage of the V converter 38 is integrated and the voltage is output to the base of the transistor 29. As a result, for example, if the motor 50 rotation speed is smaller than the set rotation speed, the difference (reference voltage and F
A voltage proportional to the magnitude of the integral of the difference between the output voltage and the output voltage of the /V converter 38 is decreased from the base voltage of the transistor 29, and the charging current to the capacitor 30 is increased. Therefore, as the power supplied to the electric motor 5 increases, the number of rotations increases. On the other hand, if the rotation speed of the electric motor 5 is larger than the set rotation speed, the base voltage is increased,
By reducing the supply voltage and the rotational speed, the rotational speed is controlled so that the rotational speed is always set by the variable resistor 37.

In this way, the electric motor control device in this embodiment is provided with an F/V converter that converts the frequency of the speed detector into voltage,
Since the bidirectional cyrisk is driven by comparing the output voltage of the F/V converter with the reference voltage, highly accurate rotation control is possible, and it has the excellent effect of being able to be constructed at low cost.

〔Effect of the invention〕

As explained above, the present invention includes an F/V conversion means for converting the output of a speed detector into a voltage, and an output voltage from the F/V conversion means and a reference voltage corresponding to the rotational speed of the motor to be controlled. Since it is provided with a driving means for driving both the same-sex cylisks, highly accurate rotation control is possible, and it has the excellent effect of being able to be constructed at low cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a control device for an electric motor showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a control device for a conventional electric motor. DESCRIPTION OF SYMBOLS 1... Power supply, 5... Electric motor, 16... Speed detector, 25... Bidirectional cyrisk, 26... Triac photocoupler, 27,29° 31... Transistor, 28.40 .41... Comparator, 32...
Integral calculator, 33... Power transformer, 34... Power supply circuit, 35° 36... DC voltage source, 37... Variable resistor, 38... F/V converter, 39... Rectifier bridge, 42...exclusive OR gate IC. Figure 2

Claims (1)

[Scope of Claims] A motor control device that controls the rotational speed of an electric motor using a bidirectional thyristor, comprising: a speed detector that detects the rotational speed of the electric motor; and an F/F converter that converts the output of the speed detector into a voltage. and a driving means for driving the bidirectional thyristor by comparing the output voltage from the F/V converting means with a reference voltage corresponding to the rotational speed of the electric motor to be controlled. An electric motor control device characterized by: