JPH02280686A - Speed controller for dc motor - Google Patents

Abstract

PURPOSE:To improve the stability of speed control by a method wherein the gain of an error amplifier, producing the current reference of an armature from a difference between a speed feedback signal and a speed reference, is increased or decreased in accordance with a difference between the changing rate of the speed feedback signal with respect to the speed reference and a reference changing rate. CONSTITUTION:A gain corrector 23 reads a speed reference N* and an actual speed N to operate the changing rate of the actual speed N with respect to the speed reference N*, compare the result of the operation with a speed responding reference and output a gain correcting signal corresponding to the difference into an error amplifier 11A as a gain control signal. Accordingly, the output of the error amplifier 11A is changed slowly even when the actual speed is changed suddenly and the output of the error amplifier 11A will never be changed suddenly even when sudden speed change is generated due to the backlash of gears, the torsion of a shaft and the like whereby the backlash of gears, the torsion of the shaft and the like may be prevented from becoming an external disturbance with respect to a control system.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improving control stability in a speed control device for a DC motor.

[Conventional technology]

FIG. 4 shows, for example, the circuit configuration of a thyristor Leonard device shown in the Electrical Engineering Handbook, P2S5, published February 28, 1986. In the figure,
1 is the input transformer, 2 is the main circuit of the thalistor power converter,
3 is a DC motor, 4 is a pulse oscillator, 5 is a DC motor 3
6 is the field input transformer, 7 is the main circuit of the field controller, 8 is the field of the DC motor 3, 6 windings, 9
The speed sensor 10 detects the actual speed N of the DC electric motor a3 from the output of the pulse oscillator 4 and sends out a speed feedback signal.The speed standard setter 11 sets the speed standard N". 13 is a current transformer for detecting the armature current Ta of the DC motor 3, and 14 is a current sensor 15 that detects the armature current 1a from the deviation from the speed reference N. 16 is a gate pulse generator; 17 is a field reference setting device for setting field current reference If; and 18 is for detecting field current If. A current transformer, 19 a current sensor, 20 a field current If and a field current reference If"
21 is a gate pulse generator.

Reference numeral 30 indicates a speed control unit for the DC motor, and reference numeral 31 indicates a drive unit for the DC motor.

For speed control in this configuration, an armature current reference 1a'' is created by amplifying the deviation between the speed base ($N1 and the actual speed N) using an error amplifier 11, and the difference between this armature current reference 1a'' and the armature current Ia is The armature voltage of the DC motor is controlled to eliminate the difference, and the amplification factor of the error amplifier 11 is set to obtain a predetermined speed response based on CD'' of the DC motor 3 and CD2 of the roll 5. .

[Problem to be solved by the invention]

In this conventional configuration, speed control is performed by feeding back the rotational speed of the DC motor 3, and since the amplification factor of the error amplifier 11 is constant, the DC motor 3 and the roll 5 which is the load
Due to the gear backlash of the coupling mechanism between the CD
” changes (CD of DC motor 3 → CD of DC motor 3 + GDt of roll 5), CD of roll 5”
If this is large, the speed response changes, which causes a disturbance to the control system, which may cause a hunting phenomenon and impair the stability of the speed control system.

This invention was made to solve the above problem.
An object of the present invention is to provide a speed control device for a DC motor that can prevent control stability from being inhibited by changes in CD''.

[Means to solve the problem]

In order to achieve the above object, in the invention of claim 1, the gain of the error amplifier that creates the armature current reference from the deviation between the speed feedback signal and the speed reference is adjusted to the rate of change of the speed feedback signal with respect to the speed reference. In the second aspect of the present invention, a limiter is provided to limit the output of an error amplifier that creates the armature current reference from the deviation between the speed feedback signal and the speed reference. The limiter is
The output of the error amplifier is configured to be limited to a predetermined value when the rate of change of the speed feedback signal exceeds an upper limit value, and in the invention of claim 3, an integrator for manually inputting the speed feedback signal is provided, and When the rate of change of the speed feedback signal exceeds a set value, an armature current reference is created from the output of the integrator and the speed reference.

[Effect]

In the invention of claim I, when the speed response changes, the gain of the error amplifier is adjusted in a direction to cancel the change, and the current reference output from the error amplifier is always maintained at a constant level.

In the second aspect of the invention, since the limiter operates when the speed response exceeds the upper limit value, the output of the error amplifier is suppressed to a predetermined value or less.

In the invention of claim 3, when the speed response exceeds the reference value, the integrated value is inputted to the error amplifier instead of the detected value of the actual speed, so that the output of the error amplifier follows the sudden change in the speed response. This will prevent sudden changes.

〔Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, the error amplifier 11A that detects the deviation between the speed base t$N1 and the actual speed (velocity feedback signal) N is a variable gain error amplifier. 22 is a speed response standard setter. 23 is a gain corrector which takes in the speed reference N° and the actual speed N, calculates the rate of change of the actual speed N with respect to the speed reference N1, compares this calculation result with the speed response standard, and calculates the deviation. A corresponding gain correction signal is sent to the error amplifier 11A as a gain control signal.

Since the other configurations are the same as those in FIG. 4, the same components are given the same reference numerals.

For example, if the ratio between the CD'' of the DC motor 3 and the CD'' of the roll 5 is 60, when the speed of the DC motor 3 shown in FIG. , the speed response W changes to 1:60, the speed change rate increases, the actual speed N overshoots with respect to the speed reference N1, and the stability of the control system B is lost. In the embodiment, when the rate of change of the actual speed N with respect to the speed reference N0 changes with respect to the speed response reference, the gain of the error amplifier 11A is adjusted according to the deviation, so gear backlash, shaft twist, etc. Even if there is a sudden change in speed due to the change in speed, the output of the error amplifier 11A does not follow this sudden change in speed and remains constant, thereby preventing disturbances to the control system due to gear breakage, shaft twisting, etc.

FIG. 2 shows an embodiment of the second invention, and in the figure, 24 is a speed change rate upper limit setter. 25 is a limiter that determines the magnitude of the rate of change of the output of the error amplifier 11 (the rate of change of the actual speed N with respect to the speed reference N9) and the output of the speed change rate upper limit setter 24, and determines whether the rate of change is the speed change rate. If the upper limit is exceeded, the output of the error amplifier 11 is limited to a predetermined value and sent to the error amplifier 15. Conversely, if the rate of change is less than or equal to the speed change rate upper limit, the output of the error amplifier 11 is directly sent to the error amplifier 15.

In this embodiment, when the rate of change of the actual speed N with respect to the speed reference N1 exceeds the upper limit set by the speed change rate upper limit setter 24, the output of the error amplifier 11 is limited.
Even if there is a sudden speed change due to gear backlash or shaft twist, a sudden change of 1% of the current standard will be prevented, and gear backlash or shaft twist will cause disturbance to the control system. can be prevented.

FIG. 3 shows an embodiment of the third invention, in which numeral 26 is an integrator serving as a delay element, which integrates the actual speed N. 27 is a computing unit. This computing unit 27
takes in the speed reference N0 and the actual speed N, and sets the speed reference N”
The rate of change of the actual speed N relative to the actual speed N is calculated, and this calculation result is compared with the speed response standard. If the rate of change is greater than the speed response standard, an energizing signal to energize the relay 28 is sent out. When the switching contact 28A of the relay 28 does not receive the above-mentioned energizing signal, it is in the state shown in the figure and feeds back the actual speed N to the error amplifier 11. However, when the rate of change exceeds the speed response standard, the switching contact 28A 28A to input the output of the integrator 26 to the error amplifier 11.

In this embodiment, when the rate of change of the actual speed N with respect to the speed reference N1 exceeds the speed response standard, the integral value is supplied to the error amplifier 11 instead of the actual speed N, so that the actual speed N does not suddenly change. However, the output of the error amplifier 11 shows gradual changes. Therefore, even if there is a sudden speed change due to gear backlash or shaft twist, the error amplifier 1
1's output does not change suddenly, and it is possible to prevent disturbances to the control system due to gear backlash, shaft torsion, etc.

〔Effect of the invention〕

As explained above, when the rate of change of the actual speed with respect to the speed reference is large, this invention determines whether the gain of the error amplifier that creates the current reference is adjusted, the output of the error amplifier is limited by a limiter, and the actual speed By applying the integrated value of Since sudden changes in can be suppressed, the stability of control can be improved compared to the conventional method.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 respectively show the first invention;
A block diagram showing embodiments of the second invention and the third invention, and FIG. 4 is a block diagram showing a conventional thyristor Leonard device. In the figure, 2 - power converter, 3 - DC motor, 5 - roll as load, 10 - speed reference setter, 11.1
1A15-・error amplifier, 16-gated pulse generator,
22-Speed response standard setter, 23-gain corrector, 24
-Speed change rate upper limit setter, 25・-Limiter, 26・-
Integrator, 27-Arithmetic unit, 28-Relay In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A speed control device for a DC motor that creates an armature current reference from the deviation between the speed feedback signal and the speed reference, and controls the armature voltage so that the deviation between this armature current reference and the actual armature current is eliminated. , the gain of an error amplifier that creates an armature current reference from the deviation between the speed feedback signal and the speed reference is increased or decreased in accordance with the deviation from the reference value of the rate of change of the speed feedback signal with respect to the speed reference. Electric motor speed control device. (2) A speed control device for a DC motor that creates an armature current reference from the deviation between the speed feedback signal and the speed reference, and controls the armature voltage so that the deviation between this armature current reference and the actual armature current is eliminated. has a limiter that limits the output of an error amplifier that creates an armature current reference from the deviation between the speed feedback signal and the speed reference; A speed control device for a DC motor, characterized in that the output of the error amplifier is limited to a predetermined value. (3) A speed control device for a DC motor that creates an armature current reference from the deviation between the speed feedback signal and the speed reference, and controls the armature voltage so that the deviation between this armature current reference and the actual armature current is eliminated. has an integrator that receives the speed feedback signal as input, and when the rate of change of the speed feedback signal with respect to the speed reference exceeds a set value, an armature current reference is created from the output of the integration circuit and the speed reference. This is a speed control device for a DC motor.