JPS60234483A - Speed controller of motor - Google Patents

Abstract

PURPOSE:To obtain a speed controller of motor having a power source circuit including less heating and high reliability by controlling a supply current to the motor so that the rotating speed of the motor becomes constant on the basis of the variation in the voltage of the power source of the motor. CONSTITUTION:A pulse signal of an encoder 5 mounted on a rotational shaft of a motor 1 is produced from an optical sensor 6, and the phase difference from a reference clock CLK of a period to become the reference of the rotating speed of the motor is detected in a phase difference detector 8. An operational amplifier 11 for amplifying the difference between the output voltage of a smoothing circuit 3 and a reference voltage is provided. A speed control signal is output to a transistor 10 on the basis of both the phase difference signal from the detector 8 and a voltage signal from the amplifier 11 in the rotating speed control circuit. Thus, the heat in the power source decreases, and the reliability of the power source circuit is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a motor speed control device G having a simple circuit configuration and a highly reliable power supply circuit.

(B) Prior Art Conventionally, motors have been used as drive sources in various fields, and various speed control methods are known. FIG. 1 shows an example of a conventionally known speed control bag a, in which 1 is a DC motor, 2 is a transformer, 3 is a smoothing circuit, and 4 is a stabilized power source. Even if the motor 1 is driven by a power supply circuit with such a configuration, the speed may fluctuate due to changes in the load on the motor 1. Therefore, an encoder 5 is attached to the rotating shaft of the motor 1.
The optical sensor 6 sends a pulse signal corresponding to 50 rotations of the encoder.
After being amplified by an amplifier 7, a phase difference detection circuit 8
The phase difference between the cycle and the reference clock CLK, which is the reference for the rotational speed of the motor, is detected. The rotation speed control circuit 9 outputs a control signal based on the phase difference, and the transistor 1
By controlling the on/off of 0, speed control is performed in response to load fluctuations.

The stabilized power supply 4 used in the power supply circuit of such a speed control device generates a reference voltage internally, compares the output voltage of the smoothing circuit 3 with this reference voltage, and uses transistors to always output a constant voltage. Because of this, a single integrated circuit configuration was required, and the transistors generated a certain amount of heat, which caused problems in terms of economy and reliability.

(c) Object and structure of the invention The present invention has been made in view of the above points, and the speed of a motor having a highly reliable power supply circuit that generates little heat is
The purpose is to propose a lit control device, and in order to achieve this purpose, a detection means for detecting fluctuations in the power supply voltage of the motor is provided, and the rotation speed of the motor is made constant based on the output of the detection means. The motor is configured to control the current supplied to the motor.

) Example The present invention will be explained below based on the drawings.

FIG. 2 shows an embodiment of a motor speed control device according to the present invention, in which the same reference numerals as in FIG. 1 indicate the same components.

In this practical example, the difference between the output voltage of the smoothing circuit 3 and the reference voltage E? An operational amplifier 11 for amplification is provided, and the configuration is configured to output a speed control signal based on both the phase difference signal from the rotational speed control circuit 9ij and the phase difference detection circuit 8 and the mixed pressure signal from the operational amplifier 11.

FIG. 31 shows an embodiment of the rotation speed control circuit 9, where 9] is a comparator that compares the output of the operational amplifier 11 and the output of the triangular wave generator 93, and 92ij is a comparator that compares the output of the operational amplifier 11 and the output of the triangular wave generator 93, and 92ij shows the phase difference signal from the phase difference detection circuit 8 and the triangular wave generator. A triangular wave generator 93 generates a triangular wave signal based on the reference clock CLK. 94 is an OR circuit that takes the logical sum of the outputs of both comparators 91 and 92, and its output is a transistor (Figure 2).
supplied to the base of FIG. 4 shows a time chart of signals in each part of the circuit to explain the operation of the rotation speed control circuit 9, and (a) shows the reference clock supplied to the triangular wave generator 93, which is It is the same as the reference clock supplied to the phase difference detection circuit 8. Same figure (b)
is a triangular wave signal generated by the triangular wave generator 93 based on the reference clock.

In FIG. 2, if the power supply voltage now fluctuates and drops as shown by the broken line in FIG. ), the pulse width becomes wider. Assuming that there is no load fluctuation at this time, the output of the comparator 92 does not change because the phase difference detection circuit 8 does not change, and therefore the output of the comparator 92 does not change.
The R circuit 94 outputs wide pulses and signals that compensate for the drop in power supply voltage. As a result, transistor 10 (second
The conduction period shown in the figure) becomes longer, the current supplied to the motor 1 increases, and the decrease in rotational speed is corrected.

On the other hand, if the load decreases and the rotational speed of the motor 1 increases when the power supply voltage is constant, then the phase difference detection circuit 8
The output of increases as shown in the 41st chain (b). Therefore, the pulse width of the pulse signal output from the comparator 92 becomes narrow as shown in FIG. At this time, since the output of the comparator 91 does not change, the OR circuit 94 outputs a narrow pulse signal that compensates for the increase in rotational speed due to the decrease in load. As a result, the conduction period of the transistor 10 is shortened, the current supplied to the motor 1 is reduced, and the increase in rotational speed is compensated for.

In the above explanation, the case where the power supply voltage fluctuated and the case where the load fluctuated were explained separately, but if both fluctuations occur at the same time, it goes without saying that the above correction operation is performed at the same time. Figure (e) shows a case where both the power supply voltage and the load fluctuate.

In this way, in the rotation speed control circuit 9, the phase difference detection circuit 8
A speed control signal is output based on the phase difference signal from the operational amplifier 11 and the voltage fluctuation signal from the operational amplifier 11. When the speed control signal has a large phase difference or a large voltage fluctuation, @ is a signal that lengthens the on time of the transistor 10, and vice versa, shortens the on time.

(E) Detailed Description of the Invention As described above, the present invention provides a motor speed control device having a control means for detecting the rotation speed of the motor and controlling the current supplied to the motor so that the rotation speed is constant. , a detection means for detecting fluctuations in the power supply voltage of the motor is provided,
Since the power suppressing means controls the current supplied to the motor based on the output of the detecting means, a constant voltage can be obtained with a simple circuit configuration without using a stabilized power source. According to the present invention, since there is only one control system, the reliability of the power supply circuit is improved and heat generation in the Iz source section is reduced.

[Brief explanation of the drawing]

Figure 1 shows the electric circuit of a conventional motor speed control device, Figure 2
The figure shows an electric circuit of an embodiment of the motor speed control device according to the present invention, FIG. 3 shows an embodiment of the rotation speed control circuit shown in FIG. 2, and FIG. 5 is a time chart of signals in each part of the circuit for explaining the operation of the control device. 1... DC motor, 2... Transformer, 3... Smoothing circuit, 5... Encoder, 6... Optical sensor, 8...
Phase difference detection circuit, 9... Rotation speed control circuit, 91.92
... Comparator, 93 ... Triangular wave generator Patent applicant Konishiroku Photo Industry Co., Ltd. Agent Patent attorney Hiroshi Suzuki Figure 1 Figure 2

Claims (1)

[Claims] In a motor speed control device having a control means for detecting the rotation speed of a motor and controlling the current supplied to the motor so that the rotation speed of the motor is constant, a detection means for detecting fluctuations in the power supply voltage of the motor is provided. , wherein the 1IJlj control means is configured to control the current supplied to the motor based on the output of the detection means.
111 (all installation.