JP2001265408A - Device and method for controlling temperature of heat system plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the temperature controller of a heat system plant capable of easily performing temperature control without depending on any intuition or experience of an expert and without generating any wind-up. SOLUTION: This temperature controller is provided with a PID control part 100, a manipulated variable adding part 110 for outputting a manipulated variable for operating an object P to be controlled, a norm model part 120 having a normal model Pm and a waste time removing means 120a for removing a waste time element eLs from the normal model Pm, and a first switching part 130 for switching a circuit between the side at which the manipulated variable is inputted from the manipulated variable adding part 110 to the object P to be controlled and the side at which the manipulated variable is inputted from the control part 100. The normal model part 120 measures the output of the normal model Pm from which the waste time element e-Ls is removed by the waste time removing means 120a, and when this measured result reaches a predetermined target value, the first switching part 130 is operated so that any manipulated variable from the manipulated variable adding part 110 can be prevented from being inputted to the object P to be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device and a temperature control method for stabilizing the temperature of a control target in a thermal plant to a preset target value.
It is an object of the present invention to provide a temperature control device for a thermal plant and a temperature control method thereof, which can settle to the target value in a short time without causing windup.

[0002]

2. Description of the Related Art Generally, in a thermal system plant such as a chemical reaction furnace, various electric furnaces, a molding machine, a refuse treatment plant, a heat treatment furnace, and a power generation plant, a temperature for controlling a control target to a predetermined target value is set. Control is being performed. For example, in a molding machine that supplies a material such as resin or metal melted and kneaded in a heating cylinder to a die and extrudes from the die or injects it into the die to form a product having a desired shape, In the course of the process up to the die, the temperature of the molten material is controlled.

FIG. 12 is a schematic view for explaining an example of an extruder for extruding a molten resin into a predetermined shape by extruding a molten resin. The extruder 1 includes a cylinder 10 for melting a resin, a die 20 having an extrusion opening 21 for extruding a product having a desired shape, and a cylinder 10.
Extrusion mechanism 30 that feeds molten resin from inside toward die 20
And the cylinder 1 to heat the cylinder 10 from the outside.
Band heater 4 which is a heating means provided on the outer periphery of
1, 42, and 43, and a hopper 50 that is a material supply unit that supplies a material (resin) into the cylinder 10.

The cylinder 10 has three cylindrical barrels 1.
1, 12, 13 are connected in series, and each barrel 11,
Band heaters 41 and 4 serving as heating means for each of 12 and 13
2,43 are wound. The heating cylinder comprises a cylinder 10 (barrels 11, 12, 13) and a band heater 4
1, 42, and 43.

The extruding mechanism 30 includes barrels 11, 12, 13
, A screw 32 that rotates the screw 31, and a gear box 33 that serves as a speed reducing means interposed between the screw 31 and the motor 32. The extruder 30 is of a twin screw type, in which two screws 31 (the other one is not shown in the drawing) are arranged in the cylinder 10, and each screw 31 is driven in the opposite direction or by the driving of a motor 32. It rotates in the forward direction. Then, the molten resin in the cylinder 10 is sent out to the die 20 by the rotation of the screw 31 driven by the motor 32, and is extruded from the extrusion port 21 of the die 20 in a predetermined sectional shape.

The above plurality (3 in the example shown in FIG. 12)
) Barrels 11, 12, 13, each barrel 11, 12,
13, band heaters 41, 42, 43 provided for each
Constitutes a temperature control system for controlling the temperature of the molten resin in the cylinder 10. In general, these are handled as independent ones having different temperature set values for each of the barrels 11, 12, and 13.
One loop control is performed for every three.

[0007] By the way, due to holidays, inspections and repairs,
When the operation of the extruder 1 is restarted after being stopped for a long time, it is desired that the temperature of the resin in the cylinder 10 be quickly controlled to a desired temperature and stabilized. Conventionally, PID control, which has a simple configuration and is easy to operate, has been generally used for such control. In the PID control, when the operation of the extruder 1 is started, the operation amount by the PID control is maximized, and the heater 4 of the cylinder 10 is heated.
1, 42, 43, the cylinder 10
When the temperature rises to a predetermined temperature, the operation amount by the PID control is gradually limited.

However, in the above-described PID control, it is necessary to control the operation amount for a long time while gradually reducing the decrease in the operation amount. During that time, the temperature of the cylinder 10 oscillates around the target temperature. While converging or causing overshoot. Therefore, at present, control for converging to the target set temperature while optimizing the operation amount depends on the intuition and experience of a skilled person.
Further, in PID control, when a disturbance or a model change caused by a place or a season in which a molding machine is installed, an operating condition, a system change, or the like has a great influence on the control performance, and such a factor acts, Even after a long time,
There is a problem that the temperature does not settle to the target value.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and allows a control target to be quickly set without causing windup, and without depending on the intuition and experience of a skilled person. To provide a temperature control device and a temperature control method for a thermal plant that can easily perform temperature control, and to suppress the influence of these factors even when factors causing disturbances and model variations act. It is an object of the present invention to provide a temperature control device for a thermal plant and a temperature control method thereof, which can settle to a target value in a short time.

[0010]

According to a first aspect of the present invention, there is provided a temperature control apparatus for a thermal plant for forming a molten material into a product having a predetermined shape. A PID control unit that outputs a predetermined amount of operation corresponding to a deviation from an output value output from a control target in the machine, and controls a temperature of the control target; and a PID control unit that is provided separately from the PID control unit, A reference value model unit having a reference value model and a dead time removing unit that removes a dead time element from the reference model; and A side for inputting the manipulated variable to the control object,
A first switching unit for selectively switching a circuit between a side for inputting an operation amount from the PID control unit and a dead time element in the reference model unit, the dead time component being removed by a dead time removing unit The output of the reference model is measured, and when the measurement result reaches a predetermined target value, the first
Is operated to interrupt the input of the operation amount from the operation amount adding unit to the control target.

According to this configuration, at the same time as the start of operation of the thermal plant, the first switching unit is operated to add an arbitrary operation amount from the operation amount adding unit to the control target. At the same time, the same operation amount is input to the reference model unit. Thus, the control target such as the heating temperature rapidly moves to the target value according to the operation amount. If a dead time is included in the control target, overshoot occurs due to excessive heat supply for the dead time. Therefore, in order to avoid this, the dead time is removed from the reference model, and the operation amount is switched at the time at which the dead time is removed. That is, the first switching means is switched at a time after the dead time is removed to disconnect the operation amount adding unit from the control system, and control is performed based on the PID control unit. In this way, the control target can be reached in a short time without causing windup.

According to a second aspect of the present invention, a reference model online identification means for identifying the reference model online when the identification of the reference model in the reference model unit is not completed is provided. According to this configuration, the parameter identification of the reference model and the parameter adjustment of the controller based on the parameter identification can be simultaneously performed online.

According to a third aspect of the present invention, a circuit is selectively provided between a side for inputting an operation amount from the operation amount adding section to the reference model section and a side for inputting a control result from the control section. And a disturbance observer for suppressing the influence of the disturbance when the disturbance acts.

According to a fourth aspect of the present invention, the disturbance observer unit includes the reference model unit and a regulator, and when a factor that causes a model change of the reference model acts in addition to the disturbance. Alternatively, the influence of this factor may be suppressed by the disturbance observer. According to this configuration, it is possible to suppress the influence of disturbance and model fluctuation, and to cause the control target to quickly follow the reference model. The disturbance observer unit, as claimed in claim 5, may contain H _∞ disturbance observer or μ design the disturbance observer.

According to a sixth aspect of the present invention, the operation amount input from the operation amount adding unit is a maximum value of the operation amount that can be input to the control target. The operation amount input from the operation amount adding unit is arbitrary, but by maximizing the operation amount that can be input to the control target, the control target value can be reached most quickly.

According to a seventh aspect of the present invention, a state feedback unit for applying decoupling to the controlled object is provided. According to this configuration, it is possible to eliminate the problem of, for example, thermal interference in the control target, and to perform decoupling.

According to an eighth aspect of the present invention, there is provided a temperature control method of a thermal plant for stabilizing a temperature of a control target to a target value, wherein a target value and an output value output from the control target in the molding machine are compared. The predetermined operation amount corresponding to the deviation
Output by D control to control the temperature of the control object,
The amount of operation for operating the control target is added to the identified reference model and the control target, dead time is removed from the reference model, and the output of the reference model from which dead time is removed is measured. When the result reaches a predetermined target value, the input of the operation amount to the control target is cut off, and the control target is controlled based on the PID control.

According to this method, the control target can be quickly reached without winding up. The operation amount may be a maximum operation amount that can be operated, as described in claim 9.

As described in claim 10, when a disturbance or a factor causing a model variation of the reference model occurs in the control system, a disturbance observer may suppress the influence of the factor. As a result, even if factors such as disturbances and model variations act, it is possible to reach the target value in a short time by removing the effects of these factors.

It should be noted that the above-described PID control of the invention
Any of a two-degree-of-freedom system and a two-degree-of-freedom system may be used. One of the one-degree-of-freedom system and the two-degree-of-freedom system may be appropriately selected according to the control target or the like.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a control block diagram of the temperature control device according to the first embodiment of the present invention. In the following embodiment, the temperature control of the cylinder 10 of the extruder shown in FIG. 12 will be described as an example of the temperature control of the thermal system plant. However, the present invention is not limited to this, and can be applied to any field that requires temperature control.

The control device of the present invention is based on PID control (proportional differential integration control) and has a PID control unit 100 as shown in FIG. The PID control unit 100 outputs an operation amount (U) according to a deviation (control signal) between a target value (Ref) and an output value (y) output from the control target P,
The temperatures of the barrels 11, 12, 13 are controlled. It is preferable that the PID parameter can be changed at any time during operation by using, for example, a return switch or a control panel. The PID control unit 100 may be provided with an automatic tuning mechanism for PID parameters or a self-tuning mechanism. Further, as shown by a virtual line in the figure, a feedforward control unit 105 that predicts a deviation with respect to a measurable disturbance and a change in the operation amount and determines the operation amount is replaced by the PID control unit 100
And the PID control unit may be a two-degree-of-freedom system. The feed forward control unit 105 uses this PID
When added to the control unit 100, the feed forward K _FF can be determined by the following formula in consideration of the target value followability.

[0023]

(Equation 1)

Here, H _zr is a transfer function from the target value to the manipulated variable, and it is preferable to set this transfer function H _zr to 1 in a frequency band as wide as possible.

The cylinder 10 in this embodiment has three barrels 11, 1 having different control temperatures as described above.
It consists of 2,13. These barrels 11, 12, 1
If the three control temperatures are different, thermal interference occurs between the adjacent barrels 11 and 12 and between the barrel 12 and the barrel 13.

Therefore, in this case, the output result of the control target P is input to the cross controller 150 into which the state feedback H is introduced, and the barrels 11 to 13 are made non-interfering.

On the other hand, when the cylinders 10 do not form an interference system, such as when the control temperatures of the barrels 11, 12, and 13 are the same, the output of the control target P is input to the cross controller 150. There is no need to apply decoupling. Therefore, a switch that enables the output of the control target P to be input to the cross controller 150 automatically by determining whether the control target is an interference system or a non-interference system, or manually by an operator, is referred to as a control target P. Non-interference part 15
It is good to provide between 0.

A reference model unit 120 is provided between the PID control unit 100 and the control target P, and the reference model unit 120 and the control target P have the maximum operation amount that can be input to the control target P. An operation amount adding unit 110 for inputting a value (saturation value: Umax) is provided. A switch 130 as a first switching unit is provided between the operation amount adding unit 110 and the control target P, and can switch an input circuit between the PID control unit 100 and the operation amount adding unit 110. I can do it.

In this embodiment, the reference model unit 1
A switch 140 as a second switching unit is provided between the control unit 20 and the operation amount adding unit 110. This switch 14
In the case of 0, switching is performed at a timing synchronized with the switching timing of the switch 130 by the operation of the switching operation means of the reference model unit 120 described later. And, by this switching, the switch 1
Numeral 40 enables the operation amount adding unit 110 to be separated from the reference model unit 120.

It is preferable that the switches 130 and 140 can be manually operated so that the operator can arbitrarily switch the switches. By doing so, it is possible to separate the operation amount adding unit 110 and the reference model unit 120 from the control system and perform control by normal PID control.

The reference model unit 120 has a reference model Pm consisting of parameters identified online or a reference model Pm consisting of nominal values for which system identification has been performed in advance. This reference model Pm has a dead time element e ^-Ls
Is included. Gm is the remaining part ^obtained by removing the dead time element e- ^Ls from the reference model Pm. Normative model part 12
0, a dead time removing means 120a for removing the dead time element e- ^Ls from the reference model Pm, and a switching operation means (not shown) for performing the switching operation of the first switching unit 13 at a predetermined time tsw at which the dead time is removed. Are provided. Hereinafter, the time tsw
Will be described.

The control object P includes a large dead time L. Therefore, if the operation amount is switched when the control target P reaches the target value, an overshoot occurs. The input heat amount U _in required by the control target P including the dead time L up to the target value is expressed by the following equation.

[0033]

(Equation 2)

Here, t1 represents the time when the controlled object P without the dead time L reaches the target value. In order to avoid overshoot due to excessive heat supply for the dead time L, it is preferable to switch the operation amount at time tsw before time t1. However, the time tsw cannot be predicted from the response of the actual control target. Therefore, using the dead time removing means 120a of the reference model unit 120,
Separate the dead time element e ^-Ls on the block diagram. In this way, it is possible to obtain the output yg of the reference model that does not include the dead time element e ^{- Ls,} and from the time when the output yg reaches the target value, the optimum time for switching the first switching unit 13 tsw can be obtained.

Now, the control target P _{0 of the} first-order lag + dead time system
(S) = K ₀ / (T _0S +1) · e ^(−L0s) is considered. The step response at this time is

[0036]

(Equation 3)

Where 0 <L ₀ <T ₀ , target input ref = y ₀
= K ₀ u ₀ . Here, 0 <ya <yb and 0 <L ₀ <
When t _ya is established, when a step input Ub (a saturation value Umax of the operation amount) for ref = yb is applied at t = 0 and y = 0,

[0038]

(Equation 4)

There is only one time t _ya . This time t
_When you calculate _ya ,

[0040]

(Equation 5)

Is obtained. In consideration of the above, as shown in the third equation, the switch is switched, so that the switching timing tsw is

[0042]

(Equation 6)

Is determined. Therefore, by switching to the step input Ua at this timing, it is possible to quickly settle to the target value ya. The time of this timing is the time tsw at which the first switching unit 13 should be switched. The reference model P mentioned above
m needs to be identified in advance, but if it has not been identified, it can be identified online.

FIG. 2 is a flowchart showing a control procedure of the control device in this embodiment. At the same time as the start of the operation of the extruder 1 (step S1), the control device determines whether or not each input relationship needs to be made non-interfering (step S2). When it is determined that the control target is an interference system, such as when the control temperatures of the barrels 11, 12, and 13 of the cylinder 10 are different, the output of the control target P is output to the non-interference unit 15
Input 0 to apply decoupling (step S3).

Next, it is determined whether or not the control according to the present invention is to be applied. If not, the switch 130 and the switch 140 are both switched so that the operation amount adding section 11
0 and the reference model unit 120 are disconnected from the control system (step S4). As a result, control using only the PID control becomes possible (step S11).

When the control of the present invention is applied, the switches 130 and 140 are operated to operate the operation amount adding unit 110, the control object P, the operation amount adding unit 110, and the reference model unit 120.
Is connected, and the saturation operation amount Umax is applied to the control target P and the reference model unit 120 (step S5). At this time, it is determined whether or not the reference model Pm of the reference model unit 120 has been identified (step S6). If the identification has not been completed, the reference model Pm is identified using online (step S7).

Next, the output of the reference model Pm from which the dead time element e- ^LS has been removed is measured online (step S8), and it is determined whether or not the measured value has reached a predetermined target value (step S8). S9). If the target value has not been reached, the operation amount Umax is continuously input to the reference model unit 120 and the control target P (step S5), and the procedure of steps S6 to S9 is repeated.

When the target value is reached, the reference model unit 120
Outputs the switching command to the switch 130 and the switch 140, and the operation amount adding unit 110 and the reference model unit 120 are disconnected from the control system (step S1).
0). Thereby, the control target P is thereafter controlled by the PID control (step S11).

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, when a factor that causes disturbance and model variation acts, a disturbance observer unit 260 is provided to suppress the influence of these factors. Other parts such as the PID control unit 100 and the operation amount adding unit 110 are the same as those in the first embodiment, and therefore, are denoted by the same reference numerals, and detailed description is omitted. Disturbance observer unit 260 is composed of a reference model Pm and the regulator _{K OB.} This disturbance observer 260 is a known H
_∞ Preferably based on control theory or μ design method. As in the first embodiment, the dead time element e- ^Ls is removed from the reference model Pm.

[0050] In this embodiment, the deviation is determined between the output of the output and the control target P of the reference model Pm, the deviation regulator K _OB is corrected. When the switch 130 is switched to the step input Ua at the timing of the time tsw (Equation 6) obtained in the same procedure as in the first embodiment, the target value ya can be settled quickly.
Reaches the target value earlier than the actual control target.

[0051] Therefore, the output difference of the reference model Pm and the control object P by K _OB is corrected, can be made to follow the actual controlled object P to the reference model Pm. After causing the control target P to follow the reference model Pm, the regulator K _OB plays the role of a _H∞ disturbance observer.

Next, the control procedure of the control device according to the second embodiment will be described with reference to the flowchart of FIG. Note that the same steps as those in the flowchart of FIG. 2 are denoted by the same reference numerals, and detailed description is omitted. In the control device of this embodiment, the reference model Pm reaches the target value, and the switches 130 and 140 are switched.
The operation amount adding unit 110 is disconnected from the control system, and the output of the PID control unit 100 is input to the reference model Pm. As a result, the disturbance observer 260
The integral term of the compensator of the D control unit 100 and the difference between the output of the reference model Pm and the output of the control target P are corrected, and the target value setting is completed (step S10 '). Thereafter, the control is performed with the disturbance observer added to the PID control (Step S).
11 ').

[Experimental Results] The inventors of the present invention examined the target setting ability of the control device of the present invention in comparison with the target setting ability of the control device of the anti-windup decoupling PID control system. Hereinafter, the results of the study will be described.
First, the features of the anti-windup control will be briefly described. Anti-windup control is a control theory for solving the windup phenomenon problem.
In the case where the configuration is simple such as I or PID and only the integral term can be separated from other terms, the windup phenomenon can be suppressed by directly operating only the state of the integral term. are doing.

Non-interference PI for anti-windup control
FIG. 5A shows a block diagram applied to the D control device.
In this control system, a saturation characteristic (limiter limit) 320 is provided between the control target P and the PID controller 300, and the input (operation amount) Ur exceeding the saturation amount is suppressed by the saturation characteristic 320 by the limiter. Windup is suppressed by directly feeding back the difference of the input U to the integral term (1 / S) of the PID controller 300. A cross controller 350 is connected to the control target P, and decoupling by state feedback is applied. In the control of a plant such as an extruder, the proportional operation of the compensator is determined by adjusting a proportional band determined by a field engineer. The inventors first obtained an appropriate limit of the proportional band in the anti-windup control described above.

First, general PID control without anti-windup and decoupling PID control will be discussed. In this case, the simulation shows that the proportional band is 17%
Could be narrowed down. However, if the proportional band was narrowed further, the system became unstable. The narrower the proportional band from 17%, the greater the overshoot and the longer the target value settling time.

FIG. 5 (b) shows the case where the proportional band is 17%.
The ID control and the decoupling PID control simulation result are shown. As can be seen from the table, when the proportional band is 17%, the adjustment limit of the proportional band is indicated, and no overshoot occurs and the system is stable. The settling time within ± 1 ° C. of the target value is 45 minutes in the case of non-interacting PID control. On the other hand, in the case of PID control, barrels 11 to 11
Because of the presence of thermal interference between the two, the target value could not be settled even after 8 hours. In the following, the study will be limited to only the decoupling PID control which has been decoupling in order to solve the thermal interference problem.

Anti-windup control is decoupling PI
A simulation was performed to find out how narrow the adjustment limit of the proportional band can be applied to D control. FIG. 6 shows a simulation result when anti-windup is applied. In the case of the decoupling PID control of FIG. 5, the proportional band is 17%.
I couldn't narrow it down to nothing. This is because the operation amount becomes saturated and the integral term of the PID controller 300 excessively accumulates error information, thereby causing overshoot. By applying anti-windup control, the proportional band could be reduced to 5%. At this time, the barrels 11, 12, and 13 complete the target value setting within 17 minutes, 19 minutes, and 22 minutes, respectively, within ± 1 ° C. of the target value.

FIG. 7 shows a simulation result by the control of the present invention. Referring to FIG. 7, barrels 11, 12, 1
3 is 22.18.20 minutes, ± 1 ° C of target value
Complete the target value setting within. From this, it can be seen that with regard to the target value setting, the anti-windup control and the control method of the present invention obtain similar rise times.

[Examination of the effects of model variation] For example, in a thermal system plant, the location where the equipment is installed, the season, the operating conditions,
Model changes occur due to system changes, etc., which greatly affect control performance. Therefore, the inventors created a maximum value plant / minimum value plant representing the maximum variation of the model using the maximum value / minimum value of each parameter variation obtained from the system identification, and were affected by the model variation. The response results of each control system in the case were analyzed.

FIGS. 8 and 9 show simulation results of time response in the anti-windup control for each parameter variation and the control method of the present invention. In the case of anti-windup decoupling PID control, there are cases where the target value cannot be settled due to the influence of the model fluctuation. In particular, the time response of the maximum value plant, as shown in FIG.
A steady-state error of 5 ° C. or more remains. On the other hand, in the case of the present invention, as shown in FIG.
In 3, the temperature is set within ± 1 ° C. of the target value. From this, the present invention, compared to the anti-windup control,
There is an advantage that a target value setting can always be obtained even if model fluctuation occurs.

Also, according to the present invention, the rise time is short,
At the same time, it can be seen that a robust control system is configured. Accordingly, it is considered that the control apparatus and the control method of the present invention having a robust system are more suitable for a thermal system plant that is easily affected by external factors and model fluctuations are likely to occur.

Narrowing the proportional band (increase of the proportional gain) imposes a heavy burden on the hardware (machine) itself. At the same time, if the gain is high, the sensitivity of the control system increases, and it is likely to affect various noises and disturbances. For this reason, the proportional operation actually used in the field uses an appropriate proportional bandwidth. In a typical example, when an industrial robot hand is operated with a high gain set, the hand operates with vibration. It is not preferable to operate at the limit of the specification with respect to the specification (specification) of the machine itself. It can be said that there is a trade-off between the narrowing of the proportional band to improve the quick response and the burden on the hardware fair.

The anti-windup control and the control method of the present invention both rise to the target value in a similar short time. However, the proportional band is 5% in the anti-windup control, and 50% in the control method of the present invention. Since the control method of the present invention allows the device itself a margin,
The advantage that a desired quick target value setting can be obtained without imposing a burden on the device is obtained.

An experiment was performed on a test machine to confirm the simulation. First, FIG. 10 shows the results of the anti-windup control experiment. To take into account the saturation characteristics of the manipulated variable, the proportional band was set to 5%. As a result of the non-interfering PID anti-windup control, the time for keeping the target values of the barrels 11, 12, and 13 within ± 1% is about 26.27, respectively.
・ It is 25 minutes, and fast target value setting is obtained.

However, the proportional band is 5%, which imposes a load on the machine itself, and the target value may not be set when the model changes as obtained from the simulation. Since this experiment cannot assume a large model variation due to the basic heating experiment, the result is close to the result for the nominal value plant in FIG. It can be seen that when applied to an actual machine, careful attention is required to the operation method for the safety of the system.

FIG. 11 shows an experimental result of the control method of the present invention in a test machine. The proportional band was set to 50%. In the control method of the present invention, the settling time within ± 1 ° C. of the target value in the barrels 11, 12, and 13 is about 32.3 times, respectively.
8.45 minutes. It is also stable in a steady state. For comparison, a proportional band 5 with a margin for the device itself was used.
A similar experiment was performed for non-interfering PID control at 0%. This is indicated by the dotted line in the graph of FIG. Even after all of the barrels 11, 12, and 13 after 2 hours, the set value is not set within ± 1 ° C. of the target value. As a result, it has been found that a settling time of 2 hours is required for a control system including only the PID compensator currently used.

Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments. For example, the above embodiment has been described by taking as an example the extrusion molding of a molten resin as a thermal plant, but the present invention is applicable not only to extrusion molding but also to injection molding. And injection molding.
Further, the present invention can be applied to other thermal plants that need to set the temperature of the control target to the target value. Furthermore, the temperature control of the cylinder has been described as an example, but the present invention can be applied to other parts that require temperature control.

[0068]

According to the present invention, it is possible to obtain a control device and a control method that can quickly reach a control target without causing windup when the molding machine starts operating. Further, since the PID control is basically used, it is possible to easily perform the operation even if the operator is not a skilled worker, or even if the worker has no specialized knowledge about the control. Furthermore, the present invention can be applied by simply adding a simple improvement to the conventional PID control system, and can be implemented at low cost. Further, even if there is a change in the system, it is possible to easily cope with the change. In addition, a fast target value setting with a mechanical margin can be obtained, and at the same time, stable control performance in a steady state can be obtained. Further, the present invention can obtain more robustness than anti-windup control, and can perform stable temperature control even if model fluctuation occurs.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a control procedure of a temperature control device according to the first embodiment of the present invention.

FIG. 3 is a control block diagram of a temperature control device according to a second embodiment of the present invention.

FIG. 4 is a flowchart illustrating a control procedure of a temperature control device according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation of the method of the present invention.
(A) is a block diagram of an anti-windup decoupling PID control system which is a control, and (b) is a graph showing simulation results of PID control and decoupling PID control.

FIG. 6 is a graph showing a simulation result in which anti-windup control is applied to decoupling PID control.

FIG. 7 is a graph showing a simulation result by the method of the present invention.

FIG. 8 is a graph showing a simulation result of an anti-windup decoupling PID control system when a model variation occurs.

FIG. 9 is a simulation result of the control device of the present invention in the same case as in FIG. 8;

FIG. 10 is a graph showing experimental results of an anti-windup decoupling PID control system.

FIG. 11 is a graph showing experimental results of the present invention.

FIG. 12 is a schematic view illustrating an example of a molding machine and illustrating a configuration of an extrusion molding machine.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 Extrusion molding machine (molding machine) 10 Cylinder 11 to 13 Barrel 20 Die 21 Extrusion port 30 Extrusion mechanism 41 to 43 Heater belt 50 Hopper 100 PID control unit 110 Operation amount addition unit 120 Reference model unit 130 Switch (first switching means) 140 switch (second switching means) 50 non-interference controller 260 disturbance observer 320 saturation characteristic Pm reference model e- ^Ls dead time element L dead time K _OB regulator U operation amount Umax Maximum value of operation amount (saturation value)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G05B 13/02 G05B 13/02 C G05D 23/19 G05D 23/19 J (72) Inventor Hitoshi Onogaki Tokyo 2-53 Yotsuya, Fuchu-shi, 1-1 Fujimi-so 1-1 (72) Inventor Eiji Wakabayashi 1-80 Shinmei-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Ikekainai Co., Ltd. 1-chome No. 80 Ikegai Corporation F-term (reference) 4F207 AR06 KM01 5H004 GA02 GA03 GA17 GB02 HA01 HB01 JB22 KA52 KA66 KA71 KA72 KB02 KB04 KB06 KB13 KB32 KC18 KC34 KC46 LA01 LA03 LB05 5H323 AA01 BB04 CB04 KK04 CB04 CB04 9A001 BB02 BB06 GG03 HH32 HH34 JJ48 KK54 LL09

Claims (11)

[Claims] 1. A temperature control device for a thermal plant for stabilizing a temperature of a control target to a target value, wherein a predetermined value corresponding to a deviation between the target value and an output value output from the control target in the thermal plant. A PID control unit that outputs an operation amount and controls the temperature of the control object; an operation amount addition unit that is provided separately from the PID control and that outputs an operation amount for operating the control object; A reference model unit having a dead time removing unit for removing a dead time element from the reference model; a side for inputting the operation amount output from the operation amount adding unit to the control target; A first switching section for selectively switching a circuit between the circuit and the input side of the operation amount, wherein the reference model section has the dead time component removed by the dead time removing means. The output of the reference model is measured, and when the measurement result reaches a predetermined target value, the first switching unit is operated to control the operation amount from the operation amount adding unit to the control target. Shutting off the input; a temperature control device for a thermal plant. 2. The reference model on-line identification unit according to claim 1, further comprising a reference model online identification unit that identifies the reference model online when identification of the reference model in the reference model unit is not completed. Temperature control equipment for thermal plants. 3. A circuit for selectively switching a circuit between a side for inputting an operation amount from the operation amount adding section to the reference model section and a side for inputting a control result from the PID control section. The temperature control device for a thermal plant according to claim 1 or 2, further comprising a switching unit, and a disturbance observer unit that suppresses the influence of the disturbance when the disturbance acts. 4. The disturbance observer unit comprises the reference model unit and a regulator, and when a factor that causes a model variation of the reference model acts in addition to the disturbance, the influence of this factor is reduced by the regulator. 4. The temperature control device for a thermal plant according to claim 3, wherein the temperature control is corrected. 5. The temperature control device according to claim 4, wherein the disturbance observer is based on _H∞ control theory or μ control theory. 6. The thermal system according to claim 1, wherein the operation amount input from the operation amount adding unit is a maximum operation amount that can be input to the control target. Plant temperature control device. 7. The temperature of a thermal plant according to claim 1, wherein a decoupling unit is provided on the control target in order to apply decoupling to the control target. Control device. 8. A method for controlling a temperature of a thermal plant for stabilizing a temperature of a control target to a target value, wherein the predetermined value corresponding to a deviation between the target value and an output value output from the control target in the thermal plant. An operation amount is output by PID control, a temperature of the control object is controlled, an operation amount for operating the control object is added to the identified reference model and the control object, and a dead time is removed from the reference model. Measuring the output of the reference model with dead time removed,
When the measurement result reaches a predetermined target value, the input of the operation amount to the control target is cut off, and the control target is controlled based on the PID control. Plant temperature control method. 9. The temperature control method for a thermal plant according to claim 8, wherein the operation amount is a maximum value of an operation amount that can be input to the control target. 10. The heat according to claim 8, wherein when a disturbance or a factor causing a model variation of the reference model occurs in the control system, a disturbance observer suppresses the influence of the factor. System plant temperature control method. Wherein said disturbance observer, the temperature control method of the thermal system plant according to claim 10, characterized in that is based on the H _∞ control theory or μ control theory.