JPH07121245A - Parameter determining method for temperature control - Google Patents

Abstract

PURPOSE:To determine a high-precision parameter value in a short time at the time of cooling by calculating the temperature varying speed of an object of control as a parameter for cooling, and performing specific arithmetic by using this parameter and parameters of the deviation and varying speed of a secondary delay system at the time of heating. CONSTITUTION:At time cut when the temperature of the object of control reaches a temperature Ttuning, a heating manipulated variable is varied from 100% to 0% and if the temperature of the object of control falls after the time tcut, the cooling manipulated variable is varied from 0% to 100% and the varying speed of the temperature is calculated as a parameter DELTAEC in cooling. Further, EC=Ehx(DELTAEc/DELTAEh) is calculated from the parameter DELTAEC, the parameter Eh of the deviation in heating, and the parameter DELTAEh of the varying speed to calculate a parameter Ec indicating the deviation in cooling. Namely, the parameter is obtained from the relation of the parameter at the time of cooling to the parameter at the time of heating corresponding to the secondary delay system, so the high-precision value is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION In the present invention, a fuzzy rule composed of a deviation with respect to a target temperature and a change speed of the deviation is developed in advance on a deviation-change speed plane, and the developed data table is referred to. The present invention relates to a system for controlling the temperature of a dead-time + second-order lag control target, and more specifically to a method of determining a parameter indicating a correspondence relationship between a value related to the temperature of the control target and a data table.

[0002]

2. Description of the Related Art In temperature control, in order to refer to a data table in which fuzzy rules are developed, it is necessary to determine a parameter indicating a correspondence relationship between data relating to the temperature of a controlled object and the data table.

The prior art of this determination method is the heating operation amount.
At time t when 100% is changed to 0%_cutControl in
Target temperature T_tuningAnd change the heating operation amount to 0%
Peak temperature T reached by the controlled object after_peakBased on
T = T_peak-T_tuning, T _tuningAnd T_peakProportional to
The coefficient based on the value is A, the target temperature is SV,

[0004]

[ _Equation 2] Eh = (A + T _{tunig −SV} ) × T / (AT) is performed to calculate the parameter Eh of the deviation during heating. In addition, the change rate parameter ΔEh
For, regarding the heating operation amount as 100%, the temperature change rate when the temperature of the controlled object becomes T _tuning is used.

[0005]

However, when the above method is applied at the time of cooling, in order to generate the peak temperature, when the temperature of the controlled object becomes T _tuning , the controlled operation amount is set to 100% and the controlled object is set. After cooling for a certain period of time, the cooling operation amount is set to 0% and the heating operation amount is set to 10%.
When it is 0%, the peak temperature as an undershoot can be obtained after changing the manipulated variable. Therefore, it is possible to calculate the deviation parameter Ec during cooling from the peak temperature and the temperature T _tuning by the same method as described above.

However, since the above-mentioned peak temperature is forcedly generated by heating the controlled object,
It does not indicate the characteristic of the controlled object, and the value obtained by the above calculation does not indicate the value adapted to the characteristic of the controlled object.

Therefore, as for the parameters during cooling, there is no choice but to use a large number of parameters in the step response, the limit sensitivity method, the limit cycle method, etc., the approximation is frequently used, or the inaccurate first-order approximation is used. was there.

The present invention was devised to solve the above-mentioned problems, and its purpose is to show the relationship between the heating parameter of the secondary delay system and the cooling parameter, and the temperature change of the controlled object during cooling. It is to provide a temperature control parameter determination method capable of determining the parameter value with high accuracy during cooling in a short time.

[0009]

In order to solve the above problems, the temperature control parameter determination method of the present invention uses a fuzzy rule composed of a deviation from a target temperature and a change speed of the deviation as a deviation-change speed plane. Is applied in advance to the system for controlling the temperature of the dead time + second-order lag system controlled object by referring to this expanded data table, and the above-mentioned controlled object is controlled by a heating operation amount of 100%. At the time t _{cut when} heating is performed and the temperature of the controlled object reaches the preset temperature T _tuning , the heating operation amount is changed from 100% to 0%, and after the time t _cut , the temperature of the controlled object decreases. In this state, the rate of change of the temperature of the controlled object obtained by setting the cooling operation amount for cooling the controlled object from 0% to 100% is a parameter in cooling. Calculated as data .DELTA.Ec, and this parameter .DELTA.Ec, parameter deviation parameters Eh and rate of change of the time was calculated heating as a secondary delay system Δ
From Eh,

[0010]

[Equation 3] Ec = Eh × (ΔEc / ΔEh) The configuration is such that the parameter Ec indicating the deviation during cooling is calculated.

[0011]

The parameters Eh, ΔEh during heating and the parameters Ec, ΔEc during cooling are calculated from the mutual correlation between the control during heating and the control during cooling.

[0012]

[Equation 4] Eh / ΔEh = Ec / ΔEc (4) It is necessary to satisfy the relationship. In addition, the rate of change during cooling corresponding to the heating parameter ΔEh is 1
It is the maximum value of the changing speed when it is set to 00%.

Therefore, when the temperature of the controlled object falls after time _tcut and the cooling operation amount is changed from 0% to 100%, the maximum value of the rate of change of the temperature of the controlled object obtained at this time is obtained. Is a parameter ΔEc that corresponds to the parameter ΔEh during heating and is applicable to cooling.

Substituting the parameter ΔEc into the equation (4),

[0015]

[Equation 5] Parameter Ec obtained by performing the operation of Ec = Eh × (ΔEc / ΔEh)
Is a parameter indicating the deviation during cooling of the secondary delay system.

[0016]

An embodiment of the present invention will be described below with reference to the drawings.

In the present embodiment, the control target to which the present invention is applied is an extruder for forming a pipe, as shown in FIG.
[Fig. 3] is a block diagram showing an electrical configuration of an apparatus for carrying out the present embodiment.

Since the resin generates heat during molding, the extruder die 14, which requires both heating and cooling, is a control target of dead time + secondary delay system. Then, if necessary, it is heated by the heater 15 or cooled by water whose inflow is controlled by the electromagnetic valve 16. The temperature of the extruder die 14 is detected by the thermocouple 11, amplified by the amplifier 12, and then converted into a digital signal by the A / D converter 13.

The control unit 17 to which this digital signal is guided
Is a block that controls the heater 15 or the solenoid valve 16 in accordance with the output of the A / D converter 13 to maintain the temperature of the extruder die 14 at the target temperature. The present embodiment is executed by this control unit 17.

The control unit 17 stores a data table in which a fuzzy rule composed of a deviation with respect to a target temperature and a changing speed of the deviation is developed in advance on a deviation-changing speed plane. Then, the temperature of the extruder die 14 is controlled by referring to this data table via the heating parameters Eh and ΔEh and the cooling parameters Ec and ΔEc.

FIG. 1 shows parameters Eh and ΔEh during heating.
And a flow chart showing the detection operation of the parameters Ec and ΔEc during cooling, and FIG. 2 is an explanatory diagram showing the temperature change of the extruder die 14 corresponding to heating and cooling. The present invention will be described in detail below with reference to FIG.

In the automatic tuning, the tuning temperature T _tuning is set in consideration of the temperature increase after the heating is stopped due to the overshoot (step S).
11). After completion of this setting, heating by the heater 15 is started with a heating operation amount of 100%. When the temperature of the extruder die 14 reaches T _tuning (time t _cut ), the heating by the heater 15 is stopped.

The change rate parameter ΔEh during heating is
It is necessary to set the maximum value of the rate of change near the target temperature. Therefore, as the change rate parameter ΔEh, the temperature increase rate immediately before the heating is stopped is detected, and the detected value is used as the change rate parameter ΔEh in heating.

After that, the temperature T _peak of the overshoot generated in the extruder die 14 is detected, and based on the temperature T _tuning and the temperature T _peak ,

[0025]

[ _Equation 6] Eh = (A + T _{tunig −SV} ) × T / (AT) is performed to calculate the deviation parameter Eh during heating (step S12). However, T is T
A value of _peak- T _tuning , A is a coefficient based on a proportional value between T _tuning and T _peak, and SV is a target temperature.

After the temperature T _peak is detected, the solenoid valve 16 is controlled after a lapse of a certain period of time to perform cooling (100% cooling) only for a period corresponding to one control period (step S13). ). After that, when the cooling cycle is completed, the cooling is stopped (step S14) and 100
Reheat with the heating operation amount of%.

Then, in the period (t1) until the minimum value of the temperature of the extruder die 14 is detected, the rate of temperature change is sequentially detected, and the rate of the fastest change is the parameter ΔEc of the rate of change in cooling. (Step S1
5). This parameter ΔEc is the parameter Δ during heating.
It becomes a value corresponding to Eh.

As a result of the above, the parameter E during heating is
Parameters corresponding to three kinds of second-order lag systems, i.e., h, ΔEh, and the cooling parameter ΔEc are obtained.

On the other hand, the parameters Eh and ΔEh during heating and the parameters Ec and ΔEc during cooling are calculated from the mutual correlation between the control during heating and the control during cooling.

[0030]

[Equation 7] Eh / ΔEh = Ec / ΔEc (7). Therefore, by substituting the above three types of parameters into equation (7),

[0031]

[Equation 8] Ec = Eh × (ΔEc / ΔEh) The parameter Ec indicating the deviation during cooling in the second-order lag system is calculated by performing the following calculation. (Step S16).

Thereafter, the controller 17 controls the temperature of the extruder die 14 while referring to the data table by using these parameters Eh, ΔEh, Ec, and ΔEc.

[0033]

The temperature control parameter determining method according to the present invention heats a controlled object with a heating operation amount of 100%, and the temperature of the controlled object is set to a preset temperature T _tuning.
At time t _cut , the heating operation amount is changed from 100% to 0%. When the temperature of the controlled object falls after time _tcut , the rate of change of the temperature of the controlled object obtained by setting the cooling operation amount for cooling the controlled object from 0% to 100% is a parameter in the cooling. It is calculated as ΔEc. In addition, the parameter ΔE
From c and the deviation parameter Eh at the time of heating and the change rate parameter ΔEh,

[0034]

[Equation 9] Ec = Eh × (ΔEc / ΔEh) The parameter Ec indicating the deviation at the time of cooling is calculated by performing the calculation. In other words, since the cooling parameters are obtained by paying attention to the relationship between the heating parameters corresponding to the secondary delay system and the cooling parameters, and the temperature change during cooling, the values of the parameters with good cooling accuracy are obtained. Can be determined in a short time.

[Brief description of drawings]

FIG. 1 is a flowchart showing a detection operation of parameters Eh and ΔEh during heating and parameters Ec and ΔEc during cooling according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a temperature change of an extruder die corresponding to heating and cooling.

FIG. 3 is a block diagram showing an electrical configuration of an apparatus that executes this embodiment.

[Explanation of symbols]

 14 Extruder die to be controlled 15 Heater 16 for heating 16 Solenoid valve for controlling cooling Step S15 Step for calculating parameter ΔEc Step S16 Step for calculating parameter Ec

Claims (1)

[Claims] 1. A fuzzy rule composed of a deviation with respect to a target temperature and a change speed of the deviation is pre-developed on a deviation-change speed plane, and by referring to the expanded data table, dead time + secondary time In a system for controlling the temperature of a delayed controlled object, the controlled object is heated with a heating operation amount of 100%, and the temperature of the controlled object is set to a preset temperature T _tuning.
At time t _cut , the heating operation amount is 100%.
From 0% to 100% when the temperature of the controlled object is lowered after time _tcut after the time _tcut is changed to 0% to 100%. The temperature change rate of is calculated as a parameter ΔEc in cooling, and from this parameter ΔEc and the heating deviation parameter Eh and the change rate parameter ΔEh calculated as a second-order lag system, Ec = Eh A parameter determining method for temperature control, characterized in that a parameter Ec indicating a deviation during cooling is calculated by performing a calculation of × (ΔEc / ΔEh).