JPH0454601A - Controller - Google Patents

Abstract

PURPOSE:To shorten the setting time to a target set value of the process quantity by limiting the proportional arithmetic quantity to a value obtained by considering the derivative arithmetic quantity. CONSTITUTION:An output arithmetic part 5 computes (prescribed quantity - derivative arithmetic quantity), and gives a data LV which has this result as a limit range to a limiting means 6. The limiting means 6 receives this data, and executes a limit so that a proportional arithmetic result (P) from a proportional arithmetic part 2 is held in this limit range. An integral operation control means 7 receives the compensation quantity CV for designating output tracking from the output arithmetic part 5, and gives the control to the integral arithmetic quantity (I), based on comparison of (proportional arithmetic quantity P + derivative arithmetic quantity D) and a prescribed value. In such a way, even at the time of coming out suddenly from a tracking state, a smooth migration to a control state is realized.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a controller suitable for controlling the temperature of an electric furnace, etc., and more specifically, to a controller suitable for controlling the temperature of an electric furnace, etc. This invention relates to a controller that can smoothly set a process amount to a target setting value by devising a device.

<Prior Art> FIG. 11 shows the configuration of a conventionally known controller. The deviation DV between the process amount PV and the target set value SP is applied to the proportional calculation section 11 and the integral calculation section 12, and , the process amount PV is applied to the differential calculation unit 13, and each proportional, integral,
The signals from the differential calculation section are added by the output performance section 14 to obtain a manipulation signal MV, which is output to a manipulation end such as a pulp.

Now, the variable range of the target setting value SP is 0 to 100%, and the reception range of the corresponding process amount is 0 to 1o.

%, control output amount (operation signal) MV operation range from 0 to 10
When treated as 0%, the amount 0UT1 transmitted from the proportional calculation unit 11 to the operation signal MV is as shown in equation (1).

0UT1= (SP-PV)* (100/PB)%・
...(1) However, PB is the proportional band constant in formula (1), for example, if PB = 10%, (sp
-pv) becomes 10% or more, the control output becomes 100% or more, that is, becomes saturated.

The integral calculation unit 12 calculates the amount of (SP-PV)*(100/PB) every time corresponding to the integral time constant, corresponding to the deviation DV of (SP-PV) and the proportional band constant PB. I'm going to pile it up.

Here, the internal calculation value of the integral calculation unit 12 is 100%, 20%
Conventionally, an output drugging method has been used as a method for preventing overintegration states such as 0% and 300%.

In this method, for example, for f(P)+(D))>=110%, CV=110-+(P)+(D)) is transmitted to the integral calculation unit 12,
(I)=Specifies execution of CV.

Note that (P), (I), and (D) are the calculation outputs of the proportional integral and differential calculation sections.

<Problem to be solved by the invention> According to such conventional methods, it is possible to obtain a certain effect when the process amount PV or set value SP changes slowly, but when these change rapidly, the tracking Disadvantages arise when a sudden escape from the state occurs.

FIG. 12 is a diagram showing the control characteristics when the set value SP is suddenly changed in the conventional device, and it can be seen that the tracking state is quickly pulled out due to the change in the set value SP. For this purpose, the output amount (
1) is left as a negative value, and the deviation is integrated to obtain the operation signal M.
Until V is raised, the process amount PV decreases, causing a problem in that it is not able to follow the new set value smoothly.

The present invention has been made in view of the above points, and its purpose is to provide an effective tracking method to achieve a smooth control state even when the process amount Pv or set value SP fluctuates rapidly. The objective is to realize a controller that can perform the transition.

Means to solve problems〉 In order to solve the above problems, the present invention has the following features: Input the target set value and process amount and perform proportional calculation.

In a controller equipped with a control calculation section that performs integral calculations and differential calculations and outputs a control operation amount to a process, a limit means that provides a limit of (predetermined amount - differential calculation amount) for the output signal from the proportional calculation means. and an integral calculation regulating means for regulating the integral calculation amount based on a comparison between (proportional calculation amount + differential calculation amount) and a predetermined value.

Function> The limit means is configured to control the transmission of the proportional calculation amount (predetermined amount -
Gives a limit on the amount of differential calculations).

The integral calculation regulating means restricts the transmission of the integral calculation amount based on a comparison between (proportional calculation amount + differential calculation amount) and a predetermined value.

This realizes a smooth transition to the control state even when abruptly exiting the tracking state.

<Embodiment> FIG. 1 is a configuration block diagram showing an embodiment of a controller according to the present invention.

In FIG. 1, 1 is a difference calculation circuit into which the target setting value SP and the process amount Pv from process 2 are input, and calculates the deviation DV between the two; 2 is a proportional calculation unit which inputs the deviation signal DV and performs a proportional calculation; Outputs the proportional calculation result (P). Reference numeral 3 denotes an integral calculation unit which inputs the deviation signal DV and performs an integral calculation, and outputs an integral calculation result (I). Reference numeral 4 denotes a differential calculation unit which inputs the process amount Pv and performs differential calculation, and outputs the differential calculation result (D). Reference numeral 5 denotes an output calculation unit that adds the calculation results from each calculation unit 2, 3.4, and outputs a control output amount (operation signal) MV for controlling an operation end such as a valve.

6 is a limit means for giving a limit of (predetermined amount - differential calculation amount) to the calculation result from the proportional calculation section 2 and outputs the limited signal to the output calculation section 5; 7 is <proportional calculation amount + differential calculation amount Based on the comparison between the amount of integral calculation (I
) is an integral calculation regulating means.

The operation of the device configured in this way will be explained next.

The output calculation section 5 calculates (predetermined amount - differential calculation amount),
Limiting means 6 sets the data LV to this limit range.
give to The limit means 6 receives this data and limits the proportional calculation result (P) from the proportional calculation section 2 so that it falls within this limit range.

For example, assuming 110% as the predetermined amount, the data indicating the limit range is from +-1io%-(D)) to (1io%-(D)).
10% (D)), and the proportional calculation amount (P) is limited to this range and transmitted to the output calculation section 5.

The integral calculation regulating means 7 receives the compensation amount CV specifying output dragging from the output calculation unit 5, and sets the integral calculation amount (
1) Give regulations.

Now, when the deviation Dv (=sp-pV) is large and the proportional calculation amount (P) is limited to the above-mentioned limit range by the limit hand Pi6, the proportional calculation amount PLim transmitted to the output calculation section 5 is, for example, The equation (1) is obtained.

PLim=(110%-(D)) (1) The output calculation unit 5 inputs the proportional calculation amount PLim thus limited, and based on this value, calculates the amount according to, for example, equation (2). A compensation amount CV to be given to the integral calculation regulating means 7 is calculated.

CV=110%-(110%-(D)+(D)1...
(2) In this case, the compensation amount Cv obtained by the equation (2) becomes 0.

Also, for the state where the negative deviation is limited,
The control output amount is tracked near the lower limit (for example, -10%), that is, the compensation amount CV is given as CV=-10-(P)+(D).

When the proportional calculation amount (P) is limited to the lower limit value by the limit means 6, the proportional calculation amount PLim transmitted to the output calculation section 5 is as shown in equation (3), for example.

PLim-1-110%-(D))... (3) The compensation amount CV in this case is CV=-10%-(110%-(D)+(D)1...
-(4) The compensation amount CV obtained from equation (4) is 100%.

In this way, by limiting the proportional calculation amount (P) to the range based on the (predetermined differential calculation amount) and transmitting it to the output calculation section 5, it is possible to Since the integral calculation amount (I) tracks to a point where it can be easily surpassed, such as a zero value, the problem that the integral calculation amount (I) is left behind at a negative value is eliminated.

FIG. 2 is a diagram showing control characteristics when the present invention is applied.

As is clear from a comparison with the conventional example shown in Fig. 12, the problem that the integral calculation amount (4) is left behind at a negative value has been resolved, and the process amount P is smoothly set to the set value SP. It is supposed to be done.

FIG. 3 is a diagram showing the relationship between the data LV that determines the limit range given to the limit means 6, the tracking conditions, and the compensation amount CV given to the integral calculation regulating means 7 in the embodiment of FIG.

In this figure, the amount of compensation C given to the integral calculation regulating means 7
For the relationship of V, use CVl or Cv in Figure 3 instead of Cv.
A relationship like 2 may also be used.

Here, A and B are predetermined amounts, A is, for example, 110%, B is, for example, -(A-100)%, α, β are correction amounts, α is, for example, 32%, and β is, for example (-α). takes the value of Also, K
is a coefficient, for example, a value such as 0.5.

Next, the effect of setting the relationship between the compensation amount Cv given to the integral calculation regulating means 7 as shown in CVI in FIG. 3 will be explained.

This example aims to prevent overshoot from occurring in the process amount PV in cases where the target setting value SP is significantly changed or in response to disturbances.

FIG. 4 is a general control characteristic diagram of disturbance response.

In general, it is difficult to prevent the overshoot of the process amount Pv during disturbance response even if you tune parameters such as the proportional band, m-minute time, and differential time. Regarding the response, it is possible to obtain good control characteristics as shown in FIG. 5 by tuning each parameter.

From this situation, for example, the process amount P at the time of disturbance response
If some measure is taken to prevent the overshoot described in (2) above, even if the overshoot can be prevented in response to a disturbance, excessive braking may be applied when responding to the set value.

Therefore, when taking measures against overshoot during disturbance recovery, it is desirable that the characteristics for the set value response be the control characteristics shown in FIG.

That is, when the target setting value SP is changed significantly, the process amount PV preferably has a characteristic that involves some overshoot.

From this point of view, as shown in CVI in Figure 3, the amount of correction α
, β are introduced and the predetermined values A and B are corrected to correct the tracking point of the integral calculation amount (1) as indicated by the ☆ marks in FIGS. 5 and 6, for example. Thereby, as shown in FIG. 6, an overshoot is generated in response to a change in the eye Ia constant value SP.

FIG. 7 is a diagram showing control characteristics when overshoot occurs by introducing correction amounts α and β like CVI.
This figure is a diagram showing control characteristics obtained by taking measures to suppress overshoot with respect to FIG. 7.

As is clear from this characteristic, overshoot can be effectively suppressed in each situation.

Next, the effect of setting the relationship between the compensation amount CV given to the integral calculation regulating means 7 as shown in CV2 in FIG. 3 will be explained.

In this example, by introducing correction amounts α and β into the predetermined amounts A and B, and by introducing *SP into the value obtained by multiplying the target set value SP by the coefficient K, the set value of the overshoot amount in the set value response is calculated. Reduce dependence.

It is designed to always obtain negative response characteristics.

FIG. 9 is a diagram showing controllability when *SP is not introduced into the correction amounts α, β, and the value obtained by multiplying the target setting value SP by the coefficient K.

The regulation value of the integral calculation amount (I) at the time of output saturation, that is, the tracking point specified by the compensation amount Cv is indicated by ■ in Fig. 9.
It is constant as shown in ~■, and the tracking point at the time of output lower limit saturation is also constant as shown in ■~■.

FIG. 10 shows a relationship like CV2 in FIG. 3, that is,
Correction amount α, β, value KI multiplied by coefficient K by target setting value SP
It is a figure which shows the controllability when SP is introduced.

The tracking points are ■~■ and ■~■ in Figure 10.
Each has been modified in different ways as shown in the figure below. As a result, the overshoot seen at point A or point B in FIG. 9 is replaced by a good response characteristic as shown at point A or point B in FIG. 10.

It should be noted that the change in the compensation amount CV due to the introduction of *SP to the correction amounts α, β, and the value obtained by multiplying the target setting value SP by the coefficient K, was made considerably until the difference in overshoot between Figs. 9 and 10 was achieved. Therefore, changing the compensation amount in this way is highly safe.

<Effects of the Invention> As explained in detail above, according to the present invention, by limiting the proportional calculation amount (P) to a value that takes into account the differential calculation amount (D), the integral calculation amount (I ) can be selected in the vicinity of 0 to 100%, and the settling time of the process amount to the target setting value can be shortened.

In addition, by correcting the compensation amount Cv of the integral calculation amount (I), it is possible to prevent overshoot in each situation, and also to reduce the dependence of the overshoot amount on the set value in the set value response, so that -Various response characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing one embodiment of the controller according to the present invention, FIG. 2 is a diagram showing control characteristics when the present invention is applied, and FIG. 3 is a diagram showing the limit A diagram showing the relationship between data LV that determines the limit range given to the means, tracking conditions, and compensation amount Cv given to the integral calculation regulating means. Figure 4 is a general control characteristic diagram of disturbance response, and Figure 5 shows good control. Figure 6 is a diagram showing the desired control characteristics for the set value response when countermeasures are taken against overshoot during disturbance recovery. Figure 7 is a diagram showing the desirable control characteristics for the set value response when taking measures against overshoot during disturbance recovery. Figure 7 shows the overshoot caused by introducing correction amounts α and β. FIG. 8 is a diagram showing the control characteristics obtained by taking measures to suppress overshoot, and FIG. 9 is a diagram showing the control characteristics obtained when the correction amounts α, β,
Figure 10 shows the controllability when *SP is not introduced to the value obtained by multiplying the set value SP by the coefficient K. Figure 10 shows the correction amounts α, β,
A diagram showing the controllability when a value KI SP, which is a value obtained by multiplying the target set value SP by a coefficient K, is introduced. Figure 11 is a configuration diagram of a conventionally known controller. Figure 12 is a diagram showing the case where the set value SP is suddenly changed. FIG. DESCRIPTION OF SYMBOLS 1... Difference calculation circuit, 2... Proportional calculation part, 3... Integral calculation part, 4... Differential calculation part, 5... Output calculation part, 6... Limit means, 7...・Integral calculation regulation means, Figure 1, Figure 3, p, Blarfr's feet, C(, βa%rit,
Figure 2

Claims (3)

[Claims] (1) Input the target set value and process amount, perform proportional calculation,
In a controller equipped with a control calculation section that performs integral calculations and differential calculations and outputs a control operation amount to a process, means for giving a limit of (predetermined amount - differential calculation amount) to the output signal from the proportional calculation section; , (proportional calculation amount + differential calculation amount) and a predetermined value. (2) The integral calculation regulating means determines (predetermined value + correction amount) − (
2. The controller according to claim 1, wherein the integral calculation amount is restricted by the value of the proportional calculation amount + the differential calculation amount. (3) The integral calculation regulating means calculates (predetermined value + correction amount + amount related to the target setting value) - (proportional calculation amount + differential calculation amount) based on a comparison between (proportional calculation amount + differential calculation amount) and a predetermined value. 2. The controller according to claim 1, wherein the amount of integral calculation is restricted by the value of .