JPH0519804A - Automatic controller - Google Patents

Abstract

PURPOSE:To prevent an output manipulated variable from varying abruptly when various gains are switched as to the automatic controller equipped with at least a P control system and an I control system. CONSTITUTION:The automatic controller which is equipped with at least a proportional operation element KP and an integral operation element KI capable of being switched in gain for inputted control deviation signals respectively is provided with a 1st correction arithmetic means 21 which operates a proportional gain switching compensation quantity DELTAP corresponding to the difference DELTAGp between gains before and after switching and an adding means which adds the proportional gain switching compensation quantity calculated by this 1st correction arithmetic means 21 to the input of the integral operation element KI so that the proportional switching compensation quantity has the negative polarity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with at least a proportional operating element and an integral operating element capable of switching a gain with respect to an input control deviation signal. The present invention relates to an automatic control device that outputs a signal.

[0002]

2. Description of the Related Art For example, a PI control type automatic control device for controlling the speed of an electric motor, which uses both proportional operation (P) control and integral operation (I) control, or P
A PID control type in which differential control (D) control is added to I control is generally used. FIG. 3 illustrates a PID control type motor speed control device.

FIG. 3 shows a device for controlling the speed of an electric motor for driving a rolling mill. Although two rolling stands 2 and 3 arranged in tandem for rolling the strip material 1 are shown,
Here, a control device for controlling the speed of the electric motor 4 that drives the rolling stand 3 on the downstream side will be described. The speed N _F of the electric motor 4 is detected by the speed detector 5 and is matched with a separately provided speed reference N _R, and the speed controller 7 controls the current controller 8 and the power converter so as to reduce the deviation (speed deviation) ΔN. Electric motor 4 via device 6
The speed N _F is controlled.

The speed controller 7 is a proportional operation (P) control system K.
P, integral action (I) control system KI, and differential action (D)
It has a control system KD. P control system KP is speed deviation ΔN
It has a proportional gain multiplier 9 which multiplies by a proportional gain G _p . The I control system KI has an integral gain multiplier 10 that multiplies the speed deviation ΔN by an integral gain G _i , and an integrator 11 that integrates the output (ΔN · G _i ) of the integral gain multiplier 10. The D control system KD is a differentiator 12 that differentiates the speed deviation ΔN, and an output ΔD (= dΔN / dt) of the differentiator 12.
It has a differential gain multiplier 13 that multiplies by the differential gain G _d . In the I control system KI, the arrangement positions of the integral gain multiplier 10 and the integrator 11 may be reversed, and similarly, in the D control system KD, the arrangement positions of the differentiator 12 and the differential gain multiplier 13 may be reversed. Good.

The control outputs of the P control system KP, the I control system KI, and the D control system KD are added to each other, and the speed control device 7
_Is input to the current controller 8 as the output manipulated variable S _t .

In such a conventional speed control device for an electric motor, one of the proportional gain G _p , the integral gain G _i , and the differential gain G _d is used to change the speed response during low speed operation and during high speed operation. , or when switching a whole, output operation amount S _t of the speed control device 7 is changed stepwise, as a result, there is the rotational speed of the motor 4 that stand is rapidly changed. This speed change causes a tension variation in the strip material 1 and causes the quality of the strip material 1 as a product to deteriorate.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and at least a P control system and an I
An object of the present invention is to prevent an abrupt change in the output operation amount when various gains are switched in an automatic control device having a control system.

[0008]

In order to achieve the above object, the present invention comprises at least a proportional operating element and an integral operating element capable of switching a gain for an input control deviation signal, and at least a proportional operating element. In an automatic control device that outputs a signal of the sum of respective outputs of the integral operation element as a manipulated variable signal, proportional gain switching compensation according to the difference between the gain after the gain switching and the gain before the switching when the gain of the proportional operation element is switched. A first correction calculation means for calculating the amount, and an addition means for negatively adding the proportional gain switching compensation amount calculated by the first correction calculation means to the input of the integral operation element. To do.

[0009]

In the automatic control device having at least the proportional action element and the integral action element, when the gain of the proportional action element is changed, the proportional gain change compensation amount according to the difference between the gain after the gain change and the gain before the change action is integrated. By adding a negative polarity to the input of the element, it is possible to reduce the fluctuation of the operation amount due to the gain switching, and to prevent, for example, the quality deterioration of the strip material as the product of the rolling mill.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a so-called PID control type sampling control type automatic control device having a proportional action element, an integral action element and a derivative action element. Here, the same symbols as those in FIG. 3 indicate the same elements as those in FIG. The apparatus of this embodiment is different from the apparatus of FIG. 3 in that a total gain multiplier 20, a first correction calculator 21 that calculates a proportional gain switching compensation amount ΔP, and a second correction that calculates a differential gain switching compensation amount ΔD. Calculator 22,
It is characterized in that an output gain multiplier 23 is additionally provided. The integrator 11 has an output ΔI from the integral gain multiplier 10.
To the first correction calculator 21 and the second correction calculator 22
Is subtracted from each output (proportional gain switching compensation amount ΔP and differential gain switching compensation amount ΔD).

The total gain multiplier 20 has a speed deviation ΔN.
Is input, and the control amount A is output by multiplying it by the total gain G _t . That is, A = ΔN · G _t (1) The proportional gain multiplier 9 receives the output control amount A of the total gain multiplier 20 and multiplies it by the proportional gain G _p to output the proportional operation amount P. That is, P = A · G _p = ΔN · G _t · G _p (2) The integral gain multiplier 10 receives the output control amount A of the total gain multiplier 20, and multiplies it by the integral gain G _i. The control amount ΔI is output. That is, ΔI = A · G _i = ΔN · G _t · G _i (3) The differentiator 12 is the output control amount A of the total gain multiplier 20.
Is input, and it is differentiated to output the controlled variable D ₀ . That is, D ₀ = dA / dt = {d (ΔN · G _t ) / dt} (4) The differential gain multiplier 13 receives the output control amount D ₀ of the differentiator 12 and multiplies it by the differential gain G _d . Then, the differential manipulated variable D is output. That is, D = D ₀ · G _d = {d (ΔN · G _t ) / dt} G _d (5) Here, the total gain G _t before gain switching set in the total gain multiplier 20 is G _t1. , The total gain G _t after the gain switching is G _t2 , the proportional gain G _p before the gain switching set in the proportional gain multiplier 9 is G _p1 , the proportional gain G _p after the gain switching is G _p2 , and the differential gain multiplier The differential gain G _d before gain switching set to 13 is G _d1 , the differential gain G _d after gain switching is G _d2 , and the output gain G _o before gain switching set to the output gain multiplier 23 is G _o1 , and the output gain G _o after gain switching is G _o2 . Then, it is defined that ΔG _t = G _t2 −G _t1 ΔG _p = G _p2 −G _p1 ΔG _d = G _d2 −G _d1 ΔG _o = G _o2 −G _o1 . These gain variations ΔG _t , ΔG _p , Δ
In the case of sampling control, G _d and ΔG _o correspond to the difference between the gain at the current sampling and the gain at the previous sampling.

The first correction calculator 21 receives the control deviation, that is, the speed deviation ΔN, the total gain G _t , the proportional gain G _p , and the output gain G _o as the gains of the gain multipliers 20, 9, and 23, and Proportional gain switching compensation amount ΔP
Is calculated by the following equation.

ΔP = ΔN · (ΔG _t + ΔG _p + ΔG _o ) ... (6) The second computing unit 22 controls the control deviation, that is, the speed deviation ΔN,
The total gain G _t , the differential gain G _d , and the output gain G _o are gains of the gain multipliers 20, 13, and 23.
Is input and the differential gain switching compensation amount ΔD is calculated by the following equation.

ΔD = ΔN · (ΔG _t + ΔG _d + ΔG _o ) (7) As described above, the integrator 11 includes the first correction calculator 21 and the first correction calculator 21 based on the output control amount ΔI of the integral gain multiplier 10. The value obtained by subtracting each output control amount (proportional gain switching compensation amount ΔP and differential gain switching compensation amount ΔD) of the second correction calculator 22 is input. Therefore, the integral manipulated variable I output from the integrator 11 is I = I ₁ + (ΔI−ΔP−ΔD) (8), where I ₁ is the output manipulated variable at the previous sampling.

The manipulated variable S finally obtained is as follows.

S = (P + I + D) G _o (9) Now, in the apparatus of FIG. 1, first, when the proportional gain, integral gain, and differential gain are switched, and then when the total gain is switched. Further, the operation in each case when the output gain is switched will be sequentially described.

In the first case, the gain of the proportional gain multiplier 9 is switched from G _p1 to G _p2 , and the integral gain of the integral gain multiplier 10 is switched from G _i1 to G _i2 .
It is assumed that the differential gain of the differential gain multiplier 13 is switched from G _d1 to G _d2 . It is assumed that there is no change in the total gain G _t and the output gain G _o . In this case, the output control amount P of the proportional control system KP and the differential control system K
The output manipulated variable D of D is the same as that of the conventional device without both correction calculators 21 and 22 (see FIG. 3), and is expressed as follows from equations (2) and (5), respectively.

P = ΔN · G _t · G _p (10) D = {d (ΔN · G _t ) / dt} G _d (11) The first correction calculator 21 is proportional based on the equation (6). Control system K
The proportional gain switching compensation amount ΔP corresponding to the change amount of the output operation amount of P is calculated according to the following equation.

ΔP = ΔN · (ΔG _t + ΔG _p + ΔG _o ) ... (12) Further, the second correction calculator 22 is based on the equation (7), and the differential gain corresponding to the change amount of the output operation amount of the differential control system KD. The switching compensation amount ΔD is calculated according to the following equation.

ΔD = ΔN · (ΔG _t + ΔG _d + ΔG _o ) ... (13) The output manipulated variable I of the integral control system KI at this time is I = I ₁ + (ΔI-ΔP-ΔD according to the equation (8). ) (14) A signal corresponding to the sum of the manipulated variables P, D, and I calculated according to the expressions (9), (10), and (13) in this way is input to the output gain multiplier 23. _Is multiplied by the output gain G _o to obtain the final manipulated variable S. That is, S = (P + I + D) · G _o (15) As described above, when the proportional gain, the integral gain, and the differential gain are switched during the PID control, the characteristic of the integral control system KI in the PID control is (15 By presetting according to the equation), it is possible to reduce the fluctuation of the PID output when the gain is changed. FIG. 2 shows ΔP, ΔD when the proportional gain G _p , the integral gain G _i, and the differential gain G _d are switched one after another with a time difference.
2 shows changes in the output manipulated variable S _t in the case of the apparatus (without correction) and the output manipulated variable S in the case of the invention of FIG. 1 (with correction). As can be seen from this figure, according to the present invention, the output manipulated variable S when the gains G _p , G _i , and G _d are switched.
You can avoid sudden changes in.

Next, when the gain G _t of the total gain multiplier 20 is switched from G _t1 to G _t2 , in this case, the proportional term manipulated variable P and the differential term manipulated variable D are expressed by the equation (2). And is output according to equation (5). The proportional gain switching compensation amount ΔP and the differential gain switching compensation amount ΔD are
In equations (6) and (7), the second and third terms in the parentheses on the right side are set to zero, and the following is obtained.

ΔP = ΔN · ΔG _t (16) ΔD = ΔN · ΔG _t (17) Therefore, the control amount ΔI is ΔI = ΔN · G _t · G _i (18) Integral according to the equation (3). The term operation amount I follows the formula (8), and I = I ₁ + (ΔI−ΔP−ΔD) = I ₁ + ΔN (G _t · G _i −2 · ΔG _t ) ... (19)

The output manipulated variable S is obtained by multiplying the sum of the P, I, and D output manipulated variables obtained as described above by the output gain G _o . As described above, when the total gain G _t is changed during control, the integral term of the PID control is output according to the equation (19), so that the fluctuation of the PID output at the time of changing the gain can be reduced.

Next, the gain G _o of the output gain multiplier 23
Is switched from G _o1 to G _o2 . In this case, the proportional term manipulated variable P and the differential term manipulated variable D are (2)
It is output according to the equation and the equation (5). The proportional gain switching compensation amount ΔP and the differential gain switching compensation amount ΔD are (6)
In the equation and the equation (7), the first term and the second term in the parentheses on the right side are set as zero, and the following is obtained.

ΔP = ΔN · ΔG _o (20) ΔD = ΔN · ΔG _o (21) The control amount ΔI follows the formula (3) and ΔI = ΔN · G _t · G _i (22) Integral term operation amount I follows the formula (8) and becomes I = I ₁ + (ΔI-ΔP-ΔD) = I ₁ + ΔN (G _t · G _i −2 · ΔG _o ) ... (23)

The output manipulated variable S is obtained by multiplying the sum of the P, I and D output manipulated variables obtained as described above by the output gain G _o . As described above, when the output gain G _o is changed during the control, the PID output when the gain is changed can be reduced by outputting the integral term of the PID control according to the equation (23).

[0028]

According to the present invention, PI control type or PI
In the D control type control device, when the gain of each control system is switched, the proportional gain switching compensation amount and the differential gain switching compensation amount are transiently subtracted from the original integral term manipulation amount, so that a final output manipulation amount is obtained. It is possible to prevent sudden changes in the temperature.

[Brief description of drawings]

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

FIG. 2 is a time chart showing one mode of a control operation by the apparatus of FIG.

FIG. 3 is a block diagram of a conventional PID operation type automatic control device.

[Explanation of symbols]

1 strip material 2 rolling stand 3 rolling stand 4 drive motor 5 Speed detector 6 Power converter 8 Current control device 9 multiplier 10 multiplier 11 integrator 12 Differentiator 13 Multiplier 20 multiplier 21 Correction calculator 22 Correction calculator 23 Multiplier

Claims (2)

[Claims] 1. An at least proportional operation element and an integral operation element capable of switching a gain with respect to each input control deviation signal, and a manipulated variable of a signal of a sum of respective outputs of the at least the proportional operation element and the integral operation element. In an automatic control device for outputting as a signal, a first correction calculation means for calculating a proportional gain switching compensation amount according to a difference between a gain after gain switching and a gain before switching when the gain of the proportional operation element is switched, An automatic control apparatus comprising: an addition unit that adds the proportional gain switching compensation amount calculated by the first correction calculation unit to the input of the integral operation element with a negative polarity. 2. A proportional operating element, an integral operating element, and a differential operating element capable of switching the gain with respect to each input control deviation signal, and each output of the proportional operating element, the integral operating element and the differential operating element. In an automatic control device that outputs a sum signal as a manipulated variable signal, at the time of gain switching of the proportional action element, a proportional gain switching compensation amount is calculated and output according to the difference between the gain after gain switching and the gain before switching. A second correction calculation means for calculating and outputting a differential gain switching compensation amount according to the difference between the gain after the gain switching and the gain before the switching when the gain of the differential operation element is switched; The proportional gain switching compensation amount calculated by the first correction calculation means and the differential gain switching compensation amount calculated by the second correction calculation means are used for the integration operation. Automatic control apparatus is characterized by providing and adding means for adding with a negative polarity to the input of.