JPS6186803A - Switch circuit in case of fault of compensator - Google Patents

Abstract

PURPOSE:To prevent the fault and breakdown of a control subject by using a monitor circuit which always monitors the output of a compensator and a changeover switch which cuts the output of the compensator when the compensator has a fault. CONSTITUTION:The outputs of compensators 17, 18, 19 and 20 are synthesized by adders 21 and 22 in a normal operation mode and applied to the control deviations 9 and 10 by adders 11 and 12 via changeover switches 23 and 24 to be supplied to PID controllers 13 and 14 respectively. In this case, the threshold value circuits 25 and 28 monitor those synthetic outputs. Then the holding circuits 26 and 29 are set when the circuits 25 and 28 detect that the outputs delta1 and delta2 of the compensators given from the adders 11 and 12 exceed the threshold levels when a fault is produced. The switches 23 and 24 are actuated via switch driving circuits 27 and 30 respectively. Thus the compensators 17-20 are cut from a control system, and a control subject is protected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to detecting a failure of the compensator in a circuit provided with a compensator to bring the controlled variable of the controlled object closer to a target value to protect the controlled object. This invention relates to a switching circuit for compensator failure.

[Conventional technology]

FIG. 3 shows a block diagram of an example of a conventional compensator. Third
The field represents a two-variable system, and a disturbance W is applied to the controlled object 50.
In order to keep the deviations from the target values [l and r2 of the control quantities y1 and y2 small, the control quantities y1 and y2 are
．． y2 is compared with the target value rl + r2 using subtractors 53 and 54, and the control deviation ε1. Input ε2 to the compensator. For this reason, the compensators CIl, CI2, 021.

C22 is placed upstream of the PID regulators 51 and 52. Output of PID regulator 51.52' l +u
2 is a manipulated variable for controlling the controlled object.

[Problem that the invention seeks to solve]

In a control system in which a compensator is arranged as described above, if a signal exceeding a certain tolerance value enters the PID controller 51 or 52 when the compensator fails, the controlled object 50 moves abnormally, so the control This is not desirable in terms of protecting the subject. Therefore,
It is necessary to detect compensator failure early and protect the controlled object before it breaks down or is damaged. Therefore.

The present invention has been made for the purpose of quickly detecting such a failure of the compensator and protecting the controlled object.

[Failure to solve the problem]

The present invention has the following features as a means to solve the above problems.

(1) Early detection of compensator failure7. It has a switch that switches to a safe circuit to protect the controlled object.

(2) Separating the compensator circuit from the PID control system 1-1
゜The output of the compensator is constantly monitored, and the compensator is installed to control the controlled object once? In the compensator circuit that compares a control deviation of the 1jll with a target value and inputs the control deviation to a compensator, the compensator circuit includes a changeover switch that inputs the output of the compensator to the PID regulator, and Enter the output of 7. When the input signal is within the set tolerance value, the output (d zero.

A threshold circuit that outputs a constant output value when the input signal exceeds the allowable value; a holding circuit that maintains the ON state with the constant output of the seven threshold circuits until reset; The present invention provides a switching circuit at the time of a compensator failure, characterized by comprising a switch drive circuit that switches the changeover switch to disconnect the output of the compensator from the PID regulator.

[Effect]

The operation of the present invention is to compare the control amount from the controlled object with a target value and input the control deviation to the compensator. The output of the compensator is not input to the PID regulator via the changeover switch during normal operation, and is output from the PID regulator to the controlled object as a controlled variable. The output of the compensator is further input to a threshold circuit. When the input signal exceeds the allowable value, the threshold circuit outputs a constant output value to the holding circuit, and the holding circuit resets the ON state. Hold until

Drive the switch and drive circuit once. The switch 1 drive circuit switches the changeover switch to disconnect the output of the compensator from the PID controller, and protects the controlled object before a signal exceeding a certain level enters the PID controller and causes the object to fall on its side to move abnormally. become.

〔Example〕

FIG. 1 is a block diagram of a compensator failure switching circuit according to the present invention;
FIG. 2 is a diagram showing the relationship between the input and output of the threshold circuit. In Fig. 1, the controlled object 1 is defined as a two-variable system and l-7
■Variables and multivariable systems can also be treated in the same way. Controlled object 1 changes control amount 3 due to change in load 2 (w)
(y+).

4 (y2)i,j-varies, 3.4 is the target value S (r
+), 6 (rz) and subtractors 7 and 8, the control deviation is 9 (ε1).

10 (ε2).

The control deviations 9 and 10 are added to the signal coming from the supplementary 1 award device in an adder 11.12, and are input to a PID controller 13.14. The respective outputs of the PID controllers 13 and 14 are manipulated variables 15 (old) and 16 (u2).

Next, the compensator inputs the control deviation 9 and compensators 17.
If the compensator 18 is a compensator 1, the control deviation 10 is input.
9. It consists of a compensator 20, and the outputs of the compensators 17 and 19 are added together in an adder 21.

The output lane G is sent to the changeover switch 23 and the threshold value circuit 25. (\ indicates the input signal of the threshold circuit 25) Still,
The output of the threshold circuit 25 becomes the input of the holding circuit 26 which holds the value “1” until it is reset once the value “1” is input. , is input to the switch drive circuit 27 that drives the switch. Note that the switch/switch driver 2 circuit 27 connects the contact C of the selector switch 23 with 1] when a value of "1" is input, and when a value of zero is input.

contact. and a are tangent. Similarly, compensator 18
and the outputs of the compensator 20 are added by an adder 22 and output to a changeover switch 24 and a threshold circuit 28 (see FIG. 3, 8L). (\ indicates the input signal of the threshold circuit 28) Well, the output of the threshold circuit 28 is the holding circuit 2
9, and the output of the holding circuit 29 is the input to the selector switch 2.
The signal is input to the switch drive circuit 30 that drives the switch 4.

The use of this embodiment will be explained in 1.'I:l::.

ff,'l!  Deviation 9. IO directly (adder 11.1
Since the system input to the PID controller 13 and the compensator are separated by a changeover switch 23 and 24, the compensator can be monitored by looking at the outputs of the adders 21 and 22. , depending on whether these values exceed the preset values, selector switch 28. 2
4 from the control system and protect the target. Specifically, as shown at 8° in FIG. 2, when the output of the adder 21 is within ±α, the output of the threshold circuit 25 is zero.

The holding circuit 25 is left as is, and the switch driving circuit 27
do not drive. Therefore, C and a of the changeover switch 23 are connected, and the compensator is activated.

The mycelia operate, but when the output \ exceeds ±α, the selector switch 23 is activated by the signal from the threshold circuit 25 to switch to the holding circuit 26.
maintains the state of "1", drives the switch 1 drive circuit 27, contacts C and b become connected, and the compensator is removed from the control system. Therefore, if you set ±α to a value as small as possible when the compensator is normal and there is no increase in 11 stores, if the compensator fails and a large jump occurs, you can control it with a changeover switch. The compensator can be cut from the system. In addition, the changeover switch 24 operates in the same manner as described above, and when the compensator fails due to the holding circuit 29 and the switch drive circuit 30 by the output of the threshold suppressing circuit 28, the changeover switch 24 can cut the compensator from the control system. [Effects of the Invention] According to the compensator failure switching circuit according to the present invention as described above, when the output of the compensator is compared in the threshold circuit and the output from the compensator is determined to be on a certain path, Since the compensator circuit is separated, a failure of the compensator can be identified and the compensator is separated from the control system, so that the controlled object can be reliably protected.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the compensator failure switching circuit of the present invention, Fig. 2 is a relationship diagram between the threshold whistle circuit input and output, which is a part of the present invention, and the third factor is the conventional compensation A block diagram of the device circuit is shown. 1. Controlled object, 3, 4: Control amount, 5, 6: Eye fermentation '6 page,
9, 10: Bacteriostatic deviation, 11, 12: Adder, 13°14
: PID controller, 15, 16: Operation amount, 1
7,18゜19.20: Compensator, 23,24: Changeover switch, 25゜28 threshold circuit, 26,29
:Holding circuit, 27,30゛nuinoch drive circuit. (Futo) Figure 2

Claims (1)

[Claims] In a compensator circuit in which a compensator is provided upstream of a PID controller to control a controlled object, the control amount from the controlled object is compared with a target value, and the control deviation is input to the compensator, the output of the compensator is is input into the PID controller, and the output of the compensator is input. When the input signal is within the set tolerance value, the output is zero, and when the input signal exceeds the tolerance value, the output is constant. A threshold circuit that outputs a value, a holding circuit that maintains the ON state with a constant output of the threshold circuit until it is reset, and PID adjustment of the output of the compensator by switching the changeover switch based on the output of the holding circuit. A switch drive circuit that disconnects the compensator from the compensator when the compensator fails.