JPS62244287A - Digital control device for dc motor - Google Patents

Abstract

PURPOSE:To enable soft start-stop, by a method wherein energizing duty to a DC motor is increased or decreased by a definite value for a definite time. CONSTITUTION:A control means 3 dirscriminates acceleration or deceleration based on speed command 4. If acceleration is discriminated, present energizing duty is increased by definite value, and after a lapse of definite time it is discriminated whether speed of a motor 1 from an encoder 2 becomes the command speed or not. If not, after a lapsed of definite time, the process is returned to increase of energizing duty. If deceleration is discriminated, the energizing duty is decreased by each definite time. In this constitution, even if the speed command value does not vary linearly with respect to the rotational speed, the soft start-stop can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital control device for a DC motor, and particularly to a digital control device for a DC motor suitable for performing soft start and stop at low cost.

[Conventional technology]

As described in Utility Model Application No. 59-109296, a conventional digital control device for a DC motor that performs soft start and stop calculates the speed command to be followed by the DC motor from zero to the externally input command speed and performs a soft start. The soft stop is performed by calculating the command speed input from the outside to zero.

[Problem that the invention seeks to solve]

However, this is a DC motor digital control device that measures the cycle (time) of the output signal of the rotation detector and converts it to the rotation speed of the DC motor to control the rotation.For example, when rotating at low speed, the time required for one cycle is If you measure the time of several cycles during high-speed rotation, and then roughly equalize the time required to measure the cycles and perform accurate rotation control, when changing speed, you need to measure the time of several cycles. In addition, the speed command value during high-speed rotation is not necessarily larger than the speed command value during low-speed rotation, and as described above, the speed command value can be added or subtracted to No consideration was given to the fact that starting and stopping would be difficult.

The above conventional technology applies when the speed command value does not change linearly with the rotation speed, that is, when a control method is used in which the speed command value at high speed rotation is not necessarily larger than the speed command value at low speed. The purpose of the present invention is to change the speed command value linearly with the number of revolutions. An object of the present invention is to provide a digital control device for a DC motor that is capable of soft start and stop when not in use.

Means for Solving Problem c] The above object is achieved by increasing/decreasing the energization duty to the DC motor by a constant value at regular intervals.

[Effect]

As long as the load on the DC motor does not change, the energization duty to the DC motor during high-speed rotation is greater than the energization duty during low-speed rotation. As a result, soft start and stop can be performed by directly increasing or decreasing the 1 energization duty.

〔Example〕

An embodiment of the present invention will be described below. Figures 1 and 2
Fig. 3 shows a flowchart showing the soft start/stop procedure of the present invention.
is a DC motor M, 2 is an encoder E which is a rotation detector coupled to the DC motor M, 3 is a control means for driving and controlling the DC motor M, and 4 is a speed command input from the outside. A speed command 4 is externally inputted to the control means 3, and the control means 3 drives the DC motor M based on the speed command 4. A signal is output from the encoder E in accordance with the rotation of the DC motor M, and this signal is input to the control means 3, and the control means 3 uses this signal as a feedback signal to control the rotation of the DC motor M. At this time, Control means 3 for starting, stopping, and changing speed of DC motor M
The control procedure will be explained with reference to FIGS. 1 and 2. In FIG. 1 and FIG. 2, the control means 3 first determines whether or not to start the motor, and if the motor does not start, this judgment is repeated until the motor is started. is taken in from the outside. 0th order increases the current energization duty by a certain value. Measures the speed of the 0th order i motor. 1st order determines whether the motor speed has reached the commanded speed or not. If not, it continues for a certain period of time. After the elapse of 1, return to the procedure of increasing the energization duty and repeat the following. When the command speed is reached, perform constant speed control to rotate the DC motor M while maintaining the command speed. 0 Next, stop the motor, or If the speed command 4 is not stopped, it is determined whether the speed command has been changed or not, and if there is no change, the process returns to the constant speed control procedure and repeats the following.
If there is a change in the speed command, determine whether it is an acceleration or not.
If acceleration, increase the current energization duty by a certain value 1
Next, the speed of the motor is measured, and it is determined whether the speed has reached the command speed or not. If not, after a certain period of time has elapsed, the process returns to the procedure of increasing the energization duty and repeats the following steps.

When the command speed is reached, return to the constant speed control procedure and repeat the following.If it is not acceleration, that is, if it is deceleration.

Decrease the current energization duty by a certain value 1st Measure the speed of the motor, judge whether the speed has reached the commanded speed or not, and if not, reduce the energization duty by 1 after a certain amount of time has elapsed When the command speed is reached, return to the constant speed control procedure and repeat the steps below. To stop the motor, reduce the current energization duty by a certain value. 6. Measure the speed of , exit control.

As described above, according to the present invention, even when the speed command value does not change linearly with the rotation speed, soft start and
A stop can be made.

〔Effect of the invention〕

According to the present invention, even when the speed command value does not change linearly with respect to the rotational speed, soft start and stop can be easily performed.

[Brief explanation of drawings]

FIGS. 1 and 2 are flowcharts showing the procedure of an embodiment of the present invention, and FIG. 3 is a block diagram of an embodiment of the present invention. 1... DC motor M, 2... Encoder E, 3...
...Control means, 4...Speed command.

Claims (1)

[Claims] 1. A DC motor, a rotation detector coupled to the DC motor, and receiving the output of the rotation detector, driving the DC motor according to a command speed input from the outside, and controlling the rotation speed. In a digital control device for a DC motor serving as a control means, soft start/stop is performed by increasing/decreasing the energization duty to the DC motor by a fixed value at fixed time intervals when starting, stopping, or changing speed of the DC motor. A digital control device for a DC motor, which is characterized by: