JP2001290504A - Control device - Google Patents

Abstract

(57) [Problem] To remove small fluctuations and noise components included in a control amount and an operation amount without causing a delay in a control response of the control amount to a command value. A compensator calculator 10, when the absolute value of the difference value C ₁ of the first operation amount U and the second manipulated variable U 'is equal to or larger than the reference value L is the difference value C ₁ and K ₂ the multiplied value to the compensation amount C _4, the compensation amount of the C ₄ second manipulated variable U 'output the value T _OUT obtained by adding to the controlled object 11, the first manipulated variable U and the second manipulated variable U' If the absolute value of the difference value C _{1 from} the reference value L is smaller than the reference value L, the second operation amount U ′ is output to the control target 11 as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for performing feedback control based on a control amount of a control object.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a configuration of a conventional control device. This control device is a host device (not shown)
Is a control device that controls the controlled object 11 to operate in accordance with the command value R output from the controller. When the control amount Y is the speed of the control target 11, the command R is a speed command for the control target 11, and when the control amount Y is the current of the control target 11, the command value R is It is a current command. A detector (not shown) for detecting the control amount Y is attached to the control target 11, and the detector detects and outputs the control amount Y. This control device monitors the control amount Y output from the detector and monitors whether the control target 11 is operating according to the command value R. Such a control device includes, for example, an inverter device that drives an electric motor.

A proportional-integral (hereinafter PI) controller 1 performs a PI calculation based on a deviation E between a command value R and a control amount Y detected and fed back by a detector, and performs a first operation of a controlled object 11. The quantity U is calculated and output. Usually, the control amount Y detected by the detector often fluctuates finely even in a steady state. Further, the control amount Y may include noise when fed back from the detector. The aforementioned PI controller 1 determines the first operation amount U based on the control amount Y. For this reason, the first operation amount U directly includes the fine fluctuation and the noise component included in the control amount Y.

[0004] In the control device shown in FIG. 3, the first operation amount U output from the PI controller 1 is reduced by a low-pass filter 2 in order to prevent excessive reaction to these fluctuations and noise components.
To remove the above-mentioned fluctuation component and noise component from the first manipulated variable U, and to input the second manipulated variable U ′ output from the low-pass filter 2 to the control target 11.

As a method for removing the noise component included in the first operation amount U, besides the method using the low-pass filter 2 as described above, a method disclosed in Japanese Patent Publication No. 3-78679 can be used. There is a method using a moving average. The method using the moving average is a method of determining an amount at a certain time by taking an average value of a certain amount before and after the time as the amount at the time.

As described above, in the control device shown in FIG.
By using the low-pass filter 2, fine fluctuations and noise components included in the first operation amount U can be removed. However, since the second manipulated variable U ′, which is the output of the low-pass filter 2, is delayed with respect to the first manipulated variable U, the control device described above causes a delay in the control response of the control amount Y to the command value R. There was a problem that would.

[0007] Japanese Patent Application Laid-Open No. 8-47258 discloses a digital control device with improved control responsiveness. This control device is intended to shorten the time for PI calculation and the like in one sampling cycle, and to improve the control response. However, this control device does not include a countermeasure against a minute fluctuation of the control amount Y or a noise component, and this control device does not solve the above-described response delay due to the low-pass filter 2.

Japanese Patent Application Laid-Open No. HEI 9-154283 discloses a control system for reducing the influence of current pulsation caused by pulse width modulation (hereinafter referred to as PWM). In this control system, the PWM carrier cycle and the sampling cycle of the control device are synchronized, and a current value when the pulsation component value is minimum and a current value when the pulsation component value is maximum are sampled. By using the intermediate value as the detected current value, a decrease in control performance due to current pulsation due to PWM is prevented. However, the fine fluctuation and the noise component of the control amount Y described above fluctuate randomly and do not have periodicity. Therefore, this control system has no effect on the fluctuation of the control amount Y having no periodicity.

[0009]

As described above, in the conventional control device, in order to prevent the control amount of the controlled object from fluctuating or excessively reacting to the noise component, the control unit is determined based on the control amount. The first operation amount is input to a low-pass filter or the like to remove a noise component, and the second operation amount output from the low-pass filter is input to a control target. However, in the conventional control device, since the second operation amount is behind the first operation amount, there is a problem that a control response of the control amount to the command value is delayed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device capable of removing fine fluctuations and noise components included in an operation amount without causing a delay in a control response of the control amount to a command value. I do.

[0011]

In order to solve the above-mentioned problems, the present invention provides a first operation amount based on a deviation between a command value output from a host device and a feedback control amount of a control target. And a low-pass filter that removes a frequency component equal to or higher than a predetermined frequency from the first manipulated variable and outputs the result as a second manipulated variable. When the absolute value of the difference value from the second operation amount is equal to or greater than a predetermined value, a value obtained by multiplying the difference value by a predetermined value is used as a compensation amount, and a value obtained by adding the compensation amount to the second operation amount is obtained. It is characterized by further comprising compensation calculating means for outputting to the control target, and outputting the second manipulated variable to the control target when the absolute value is smaller than a predetermined value.

In the control device according to the present invention, by providing the above-described compensation operation means, fine fluctuation included in the first operation amount is removed by the low-pass filter, and the first operation amount is equal to or more than the predetermined value. In the case of, the compensation amount for compensating for the delay of the second operation amount is added to the second operation amount and output to the control target. Therefore, the control device of the present invention can remove fine fluctuation and noise components included in the operation amount without causing a delay in the control response of the control amount to the command value.

[0013]

Next, a control device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG.
It is a block diagram showing the composition of the control device of this embodiment.
The control device of the present embodiment is different from a conventional control device in that the control device includes a compensation arithmetic unit 10. Compensation calculator 10
Is a dead zone calculator 3, an amplifier 5, and a limiter circuit 6.
, A subtractor 8 and an adder 9.

The subtractor 8 is output from the PI controller 1
Output from the low-pass filter 2 from the first manipulated variable U
The second manipulated variable U ′ is subtracted, and the subtracted value is output to the output C₁When
And output. The dead zone calculator 3 determines whether the first manipulated variable U is
Difference value C from the manipulated variable U 'of FIG. ₁Is the specified value.
If the reference value L is equal to or greater than_TwoAs the difference value C₁To
Output and the difference value C₁If the absolute value of is less than the specified value
Has output C_TwoIs output as 0. Amplifier 5 is insensitive
Output C of band calculator 3_TwoTo K_Two(K_Two> 0) times the output C_ThreeWhen
And output. Then, the limiter 6 outputs the output of the amplifier 5.
C_ThreeIs greater than or equal to a preset limiter value,
The limiter value is calculated as the compensation amount C_FourAnd outputs the
Output C_ThreeIs smaller than the limiter value,
Output C_ThreeIs the compensation amount C_FourOutput as

As described above, the compensation calculator 10 has the first
Manipulated variable U and the compensation amount C values of difference values C ₁ and _two times K is the absolute value of the difference value C ₁ and the second manipulated variable U 'is equal to or larger than the reference value L as a compensation amount C _{4 4} is added to the second manipulated variable U ′, and a value T _OUT is output to the control target 11, and the first manipulated variable U is output.
The absolute value of the difference value C ₁ between the second operation amount U ′ and the second operation amount U ′ is the reference value L.
If it is smaller, the second operation amount U ′ is
Output to

Next, the operation of the control device of the present embodiment will be described with reference to the drawings. FIG. 2 is a graph showing the operation of the control device of the present embodiment. Here, in order to simplify the explanation, the 1 the value of the gain K ₂ of the amplifier 5 in FIG. 1, it has a limiting value of the limiter 6 is infinite. Further, the proportional gain of the PI controller 1 is set to 1, and the integration time is set to infinity. Reference value L of dead zone calculator 3
Is set to the level of the noise component in the steady state of the control amount Y.

[0017] The time t ₁ or earlier, the command value R has become a 0, the control target 11 is in a steady state. However,
As described above, since the control amount Y of the control target 11 fluctuates finely due to a noise component or the like, the deviation E shown in FIG. 2A fluctuates finely. Therefore, the first manipulated variable U, which is the output of the PI controller 1 shown in FIG. 2B, also fluctuates finely, but the second manipulated variable U ′ which is the output of the low-pass filter 2 shown in FIG. 2C. Is stable to zero. Before the time t ₁ , the fluctuation of the difference value C ₁ between the first operation amount U and the second operation amount U ′ (FIG. 2D) is small, and is smaller than the reference value L. Accordingly, the output C ₂ of the dead zone operation unit 3 becomes 0, which results in a compensation amount C ₄ is also 0. Therefore, the output T to the control target 11 before the time t _1
out (FIG. _2E ) is the same as the value of the second manipulated variable U ′, and the output T _out from which the fluctuation component of the control amount Y has been removed is input to the control target 11.

As described above, in the control device according to the present embodiment, if the reference value L is set to the fluctuation level and the noise level of the control amount Y in the steady state, the fluctuation from the output T _out to the control target 11 is obtained. And noise components can be removed. Also, a new command value R is added at time t _1, the deviation E shown in FIG. 2 (a), the magnitude E ₁
It is assumed that a step-like waveform is obtained. Since the proportional gain of the PI controller 1 is 1 and the integration time is infinite, the first manipulated variable U, which is the output of the PI controller 1,
(B), the the same value E ₁ and the value of the deviation E.
When the first operation amount U becomes step-like waveform shown in FIG. 2 (b) to the size shown is E _1, the second waveform operation quantity U 'which is the output of the low-pass filter 2, Figure 2 (C). Then, the first operation amount U and the second operation amount U ′
Difference value C ₁ and is as shown in FIG. 2 (d). Since the magnitude of the gain K ₂ of the amplifier 5 is 1 and the limiter value is infinite, the compensation amount C ₄ has the same value as the difference value C ₁ ,
The output T _OUT to the control target 11 is as shown in FIG.
In FIG. 2, an output T _out to the control target 11 is an output equivalent to the first manipulated variable U. Therefore, at time t ₁
Immediately thereafter, the control target 11 outputs the output _Tout without delay with respect to the first operation amount U.

Immediately after the time t ₁ , the output T _out to the control target 11 is a value to which the compensation amount C ₄ including the fine fluctuation component and the noise component of the control amount Y is added, and thus slightly fluctuates due to the fluctuation. . However, after a lapse of time, the difference value C ₁ between the second manipulated variable U ′ and the first manipulated variable U becomes equal to the reference value L.
At the time t ₁ when a steady state is reached.
As before, the compensation amount C ₄ becomes 0 again, and the control target 11
Output _Tout is obtained by removing the fluctuation component of the control amount Y.

As described above, the control device of the present embodiment is provided with the compensation calculator 10 so that small fluctuations contained in the first operation amount U are removed by the low-pass filter 2 and the first operation amount is reduced. 'compensation amount C ₄ and the second operation amount U to compensate for the delay of' control is added to the target 11 when the amount U is equal to or greater than the reference value L is its second manipulated variable U
Output to Therefore, in the control device of the present embodiment, it is possible to remove small fluctuations and noise components included in the control amount Y and the operation amount U without causing a delay in the control response of the control amount Y to the command value R. it can.

In the control device of the present embodiment, the responsiveness of the control amount Y to the command value R is improved by increasing the gain K ₂ of the amplifier 5 in the compensation calculator 10 to increase the compensation amount C _4. be able to. Limiter 6
It is intended to apply a limit to not become too large compensation amount C ₄ obtained is amplified by the amplifier 5.

In the control device of the present embodiment, a P controller may be used instead of the PI controller 1. Further, the control device of the present embodiment may be an analog control device or a digital control device that operates at a constant sampling cycle.

[0023]

According to the control device of the present invention, the provision of the compensation arithmetic unit removes small fluctuations contained in the first manipulated variable by the low-pass filter and makes the first manipulated variable equal to or more than a predetermined value. In the case of, the compensation amount for compensating for the delay of the second operation amount is added to the second operation amount and output to the control target. Therefore, the control device of the present invention can remove fine fluctuations and noise components included in the control amount and the operation amount without causing a delay in the control response of the control amount to the command value.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control device according to an embodiment of the present invention.

FIG. 2 is a graph showing an operation of the control device according to the embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PI controller 2 Low-pass filter 3 Dead-zone calculator 5 Amplifier 6 Limiter 10 Compensation calculator 11 Control target

Claims (2)

[Claims] A control unit that outputs a first operation amount based on a deviation between a command value output from a host device and a feedback control amount of a control target; A control device comprising: a low-pass filter that removes a frequency component equal to or higher than a frequency and outputs the result as a second operation amount, wherein an absolute value of a difference value between the first operation amount and the second operation amount is a predetermined value. If the absolute value is smaller than a predetermined value, a value obtained by adding the compensation amount to the second operation amount is output as the compensation amount using a value obtained by multiplying the difference value by a predetermined value. The control device according to claim 1, further comprising a compensation calculation unit that outputs the second operation amount to the control target. 2. The control device according to claim 1, wherein said compensation calculation means uses the limiter value as the compensation amount when an absolute value of a value obtained by multiplying the difference value by a predetermined value exceeds a limiter value.