JPH0519805A - Interpolative feedback type controller - Google Patents

Abstract

PURPOSE:To enable the best interpolative feedback control by properly using PID arithmetic and other arithmetic for the difference between a set value and a process value and altering the contents of PID according to variation of a process. CONSTITUTION:The interpolative feedback type controller which controls the process 4 by using simulation transfer functions corresponding to static characteristics and dynamic characteristics of the process 4 to be controlled properly use the PID arithmetic by a PID operation circuit 2 and other arithmetic by another circuit 3 for the difference between the set value and process value and alters the contents of the PID according to the variation of the process 4. Therefore, the characteristics of the simulation transfer function on a controller side can easily be altered according to the variation of the characteristics of the process 4. Consequently, even when the process-side characteristics vary, the best interpolative feedback control is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a complementary feedback type controller used in an automatic process control system or the like.

[0002]

2. Description of the Related Art A complementary feedback type controller is known as one of the controllers used in an automatic process control system or the like.

FIG. 3 is a block diagram showing an example of such a complementary feedback type controller.

The complementary feedback type controller shown in this figure comprises a subtraction circuit 101, a static characteristic circuit 102, an addition circuit 103 and a dynamic characteristic circuit 104, and a set value SV set in a setter or the like. , The control value MV is obtained based on the process value PV output from the process 105,
This is supplied to the process 105 to supply the process value PV.
The process 105 is controlled so that the relationship between the value and the set value SV satisfies a preset condition.

The subtraction circuit 101 calculates a difference (deviation) between a set value SV set in a setter or the like and a process value PV output from the process 105, and a signal obtained by this calculation operation is calculated. It is supplied to the characteristic circuit 102.

The static characteristic circuit 102 gives the static characteristic represented by the following equation to the deviation output from the subtraction circuit 101, and supplies the signal obtained by this to the addition circuit 103.

[0007]

[Equation 1]

The adder circuit 103 adds the value of the signal output from the static characteristic circuit 102 and the value of the fed back signal, and supplies the signal obtained by this addition operation to the dynamic characteristic circuit 104. The signal is a control value
The MV is supplied to the process 105 to control it.

The dynamic characteristic circuit 104 gives a dynamic characteristic represented by the following equation to the signal output from the adder circuit 103,
The signal thus obtained is supplied to the adder circuit 103.

[0010]

[Equation 2]

[0011]

By the way, in such a complementary feedback type controller, the static characteristic unit 10 is used.
When the static characteristic of No. 2 matches the static characteristic of the process 105 and the dynamic characteristic of the dynamic characteristic unit 104 matches the dynamic characteristic of the process 105, the best complementary feedback control can be performed, but some cause By Figure 4
When the characteristics of the actual process 105 and the characteristics of the simulated transfer function on the side of the complementary feedback controller (characteristics represented by static characteristics and dynamic characteristics) deviate from each other, as shown in FIG. There was a problem.

Therefore, when such a characteristic deviation occurs, the static characteristic of the static characteristic portion 102 or the dynamic characteristic of the dynamic characteristic portion 104 provided on the side of the complementary feedback controller is changed according to the actual characteristic of the process 105. Although methods have been taken, such methods are difficult to adjust, and in many cases are virtually impossible to adjust.

In view of the above circumstances, the present invention can easily change the characteristics of the simulated transfer function on the controller side according to the change in the characteristics of the process, and even if the characteristics of the process side are changed, the best complement is achieved. It is an object of the present invention to provide a complementary feedback type controller that can perform feedback control.

[0014]

In order to achieve the above object, a complementary feedback controller according to the present invention uses a simulated transfer function according to the static characteristic and the dynamic characteristic of a process to be controlled to perform the process. In the complementary feedback type controller for controlling the PID calculation, the PID calculation and the other calculation are performed separately for the difference between the set value and the process value, and the content of the PID is changed according to the change of the process. There is.

[0015]

In the above structure, the PID calculation and the other calculations are performed separately for the difference between the set value and the process value, and the contents of the PID calculation are changed according to the change of the process, The characteristic of the simulated transfer function on the controller side is changed according to the characteristic change, and even if the characteristic on the process side changes, the best complementary feedback control is performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to a detailed circuit description of the present invention,
The basic principle of the present invention will be described.

Now, considering the characteristics of a general process and the characteristics of the complementary feedback controller for controlling this process, the normal process and the complementary feedback controller for controlling this process can be represented as shown in FIG. it can.

At this time, the transfer function of the arithmetic unit 106 constituting the complementary feedback controller can be expressed by the following equation.

[0019]

[Equation 3]

Here, the replacement shown in the following equation is performed,

[0021]

[Equation 4]

By substituting this equation (4) into the denominator of the above equation (3) and expanding it, the following equation is obtained.

[0023]

[Equation 5]

As is clear from the equation (5), the transfer function of the complementary feedback controller shown in FIG.
It can be divided into an ID element and other elements (fixed elements).

Since the characteristic of the PID element can be easily changed, the simulated transfer function characteristic of the complementary feedback controller can be easily changed only by changing the characteristic of the PID element.

FIG. 1 is a block diagram showing a first embodiment of a complementary feedback controller according to the present invention using the above-mentioned basic principle.

The complementary feedback type controller shown in this figure comprises a subtraction circuit 1, a PID operation circuit 2 and other operation circuits 3, and a set value SV set in a setter or the like and a process 4 The control value MV is obtained based on the output process value PV and is supplied to the process 15 so that the relationship between the process value PV and the set value SV satisfies the preset condition. 15
To control.

The subtraction circuit 1 includes a set value SV set in a setter and the process value PV output from the process 4.
The difference (deviation) is calculated and the signal obtained by this calculation operation is supplied to the PID operation circuit 2.

The PID operating circuit 2 gives the PID characteristic shown in the following equation to the deviation output from the subtracting circuit 1, and supplies the signal obtained by this to the other operating circuit 3.

[0030]

[Equation 6]

The other operating circuit 3 gives the integration characteristic shown in the following equation to the signal output from the PID operating circuit 2, and supplies the signal obtained by this to the process 4 as the control value MV. Control this.

[0032]

[Equation 7]

As described above, in this embodiment, the characteristic of the simulated transfer function on the controller side is determined by the PID characteristic of the PID operating circuit 2 and the characteristic of the other operating circuit 3, so that the characteristic of the process 4 is obtained. The characteristic of the simulated transfer function on the controller side can be easily changed according to the change, and thus the best complementary feedback control can be performed even when the characteristic on the process 4 side changes.

Next, the basic principle of the second embodiment of the complementary feedback controller according to the present invention will be described.

First, the approximate expression shown in the following expression is applied to the expression (5).

[0036]

[Equation 8]

In this case, an expansion expression on the left side is created for each of the variables "Q1", "Q2", "P3", and "P4" shown in these expressions (8) and (9), and 2 of "S" is created. If the following coefficient is set as an equal value, the value shown in the following equation is obtained.

[0038]

[Equation 9]

When the equation (8) is applied to the {} in the equation (5), the following equation is obtained:

[0040]

[Equation 10]

The equation (5) can be expressed as the following equation.

[0042]

[Equation 11]

When the approximation shown in the following equation is used for the equation (12),

[0044]

[Equation 12]

The above equation (12) can be expressed by the following equation.

[0046]

[Equation 13]

As is clear from the equation (14), FIG.
The transfer function of the complementary feedback controller shown in is a PID element and other elements (fixed elements) that are easy to calculate.
Can be divided into

Since the characteristic of the PID element can be easily changed, the simulated transfer function characteristic of the complementary feedback controller can be easily changed only by changing the characteristic of the PID element.

FIG. 2 is a block diagram showing a second embodiment of the complementary feedback controller according to the present invention using the above-mentioned basic principle.

The complementary feedback type controller shown in this figure comprises a subtracting circuit 10, a PID operating circuit 11 and other operating circuits 12, and sets a set value SV set in a setter or the like and a process 13 The control value MV is obtained based on the output process value PV and is supplied to the process 13 so that the relationship between the process value PV and the set value SV satisfies the preset condition. Control 13.

The subtraction circuit 10 calculates the difference (deviation) between the set value SV set in the setter or the like and the process value PV output from the process 13, and the signal obtained by this operation is PID. It is supplied to the operating circuit 11.

The PID operating circuit 11 gives the PID characteristic shown in the following equation to the deviation output from the subtracting circuit 10, and the signal obtained by this gives the other operating circuit 12
Supply to.

[0053]

[Equation 14]

The other operating circuit 12 gives the characteristic output from the PID operating circuit 11 to the characteristic shown in the following equation, and supplies the signal obtained by this to the process 13 as the control value MV. Control.

[0055]

[Equation 15]

As described above, in the present embodiment, the characteristic of the simulated transfer function on the controller side is determined by the PID characteristic of the PID operating circuit 11 and the characteristic of the other operating circuit 12, so that the characteristic of the process 13 is obtained. The characteristic of the simulated transfer function on the controller side can be easily changed according to the change, and thus the best complementary feedback control can be performed even when the characteristic on the process 13 side changes.

Further, in this embodiment, since the calculation is performed using the equation (14), the calculation load can be lightened as compared with the case where the equation (5) is directly calculated.

[0058]

As described above, according to the present invention, the characteristic of the simulated transfer function on the controller side can be easily changed according to the characteristic change of the process, and when the characteristic on the process side is changed by this. However, the best complementary feedback control can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a complementary feedback controller according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the complementary feedback controller according to the present invention.

FIG. 3 is a block diagram showing an example of a conventionally known complementary feedback type controller.

FIG. 4 is a table diagram for explaining a problem of the complementary feedback type controller shown in FIG.

5 is a block diagram showing a modified example of the complementary feedback controller shown in FIG.

[Explanation of symbols]

 1 Subtraction circuit 2 PID operation circuit 3 Other operation circuit 4 Process

Claims (1)

Claim: What is claimed is: 1. A complementary feedback controller for controlling a process to be controlled by using a simulated transfer function according to a static characteristic and a dynamic characteristic of the process to be controlled. Complementary feedback type controller characterized in that PID calculation and other calculation are separately performed with respect to the difference of (1) and the content of the PID is changed according to the change of the process.