JPS61210884A - Speed controller for dc motor - Google Patents

Abstract

PURPOSE:To finely regulate the rotating speed of a motor by enabling to input a digital signal for finely regulating the rotating speed to a motor controller. CONSTITUTION:An encoder is mounted coaxially in a DC motor M, and a rectangular pulse of a period tauE is output when the motor rotates. A microcomputer MCPU detects the actual rotating speed of the motor by the period tauE, and controls the DC motor so as to coincide with the speed command signal given by a signal SCP. A signal SAJ is input as a signal for finely regulating the speed to the microcomputer MCPU. The microcomputer MCPU can finely regulate the rotating speed predetermined by the input setting in the amount of DELTAN.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to motor speed control, and particularly to fine adjustment of a preset motor rotation speed.

[Background of the invention]

Conventional speed control methods for DC motors include feeding back the output of a speed generator attached to the motor shaft and comparing it with a command voltage value, and controlling the phase difference between the pulse of an encoder attached to the motor shaft and the speed command pulse. Analog methods were mainly used, such as methods for detecting and controlling.

With the recent progress in digital semiconductor technology, digital methods have come into use1.For example, in the case of a digital control method, as shown in the Institute of Electrical Engineers of Japan Information Processing Study Group material IP-82-34, the speed command value is a digital quantity, and there is a method of converting this value and a signal from an encoder attached to the motor shaft into a digital quantity and comparing it for control.
If there is no consideration given to the method of giving the speed command as a digital quantity, and the speed is determined in advance, there is no problem, but
When specifying the speed from the outside, a digital control device is required as a command device.

So we... We have developed a method to convert the pulse width given as a signal to a control device other than a motor into a speed command. ``This will be explained using a device for mixing a chemical solution and water as shown in FIG. 3.

In order to keep the concentration of the chemical solution constant, this device uses a flow sensor to detect the amount of mixed liquid used, and determines the amount of chemical solution and water commensurate with the amount used. The amount of chemical liquid can be controlled by changing the pulse width output to the solenoid valve for controlling chemical liquid. In other words, when the amount of chemical solution is large, it is necessary to keep the concentration constant. It is necessary to increase the speed of the motor and increase the amount of water supply, so use the main controller. Calculate the motor speed command. It controlled by sending 8 to 12 bit data to the motor controller. We converted the speed command that this main controller was using. I decided to do it with a motor controller.

That is, T in FIG. 1 is output from the main controller to the solenoid valve for controlling the chemical liquid. The pulse width shown by is measured by the motor controller using clock pulses, and the result is converted into a speed command.

As shown in FIG. 2, when the pulse width T0 becomes wider.

The motor rotation speed was determined based on the pulse width so that the motor rotation speed N would be high.

However, both the chemical liquid control device and the water supply device vary depending on the machine, and the amount of mixed liquid used is detected by a flow sensor.
It has become difficult to maintain a constant concentration by simply determining the amount of chemical solution and the amount to be used.

[Purpose of the invention]

The present invention allows fine adjustment of a predetermined amount of water with respect to this predetermined amount of chemical solution. The purpose is to finely adjust the rotational speed of the motor to keep the concentration of the mixed liquid constant and absorb variations in the equipment.

[Summary of the invention]

For this reason. Input a digital signal for fine adjustment of rotation speed to the motor controller, and use this digital amount to
This is to finely adjust the preset rotation speed.

[Embodiments of the invention]

Embodiments of the present invention will be explained with reference to FIGS. 1 and 2. 1st
The diagram is. The motor controller and motor section are shown.

The signal given to the chemical liquid control solenoid valve from the main controller is a signal with a pulse width T0, and at the same time. Motor controller microcomputer MC
It is input to the PU as a signal SCP. The microcomputer MCPU has a pulse width T based on the clock. The pulse width is measured, and the pulse width is determined by the pulse width as shown by the solid line in Figure 2. As a motor rotation speed command, a DC motor M is rotated by a resistor R and a transistor TR. An encoder E is coaxially mounted on the DC motor M, and outputs a rectangular wave pulse of one period τ as the motor rotates. The microcomputer MCPU detects the actual rotational speed of the motor using this period τ and controls the DC motor so as to match the speed command signal given by the SCP.

On the other hand, SAJ is input to the microcomputer MPU as a signal for fine speed adjustment. By using this input setting, the microcomputer MPU can finely adjust the predetermined rotation speed indicated by the solid line by ΔN, as shown by the broken line in FIG. ΔN is the speed fine adjustment signal SAJ
It can be set to any value by setting .

In the embodiment shown in Fig. 1, a setting example using a switch was explained, but it is also possible to detect the detection result of a flow rate sensor or the concentration and input this result as a signal for fine adjustment. be.

〔Effect of the invention〕

According to the present invention, it is possible to absorb the variations in the entire apparatus shown in FIG. 1 and to operate the apparatus in an optimal state without changing the control of the main controller.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 is a circuit diagram of the motor controller section, and FIG. 2 is a diagram showing the relative relationship between pulse width and motor rotation speed in the embodiment. FIG. 3 is a control block diagram of the device to which the present invention is applied. ■...DC! ! , M...DC motor, E...encoder, TR...transistor, R...resistance, S
CP...Chemical liquid control solenoid valve drive signal, SAJ
...Rotation speed fine adjustment signal, Ta...Pulse width of chemical liquid control solenoid valve drive signal, τ8...Encoder m cycle, N...Motor rotation speed, ΔN...Fine motor rotation speed Adjust rotation speed.

Claims (1)

[Claims] 1. A control device that controls the rotational speed of the motor shaft using pulse signals from an encoder attached to the motor shaft.In devices where the speed command value is given by the width of the pulse signal, the motor rotation speed is set in advance by the pulse width. A speed control device for a DC motor, characterized in that the speed can be finely adjusted from the outside.