JP2000003205A - State quantity controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade the careless artificial mistakes or the operating troubles and to perform an optimum tuning operation by detecting the operated variable of an actuator when a self-tuning start condition is satisfied and calculating a control parameter to decide a controlled variable based on the current state quantity and its set value when the operated variable of the actuator is kept in a proper operation range. SOLUTION: A self-tuning operation is started when a prescribed self-tuning condition is satisfied. Then the operated variable of a heater 2 needed for an actuator, e.g. an electric furnace 1 is detected. That is, the CT(current trans) value showing the heater current value that is detected by a current transformer 6 is inputted. It is decided that the heater 2 is normal when the detected CT value is not 0, and a PID parameter is calculated. If the CT value is 0, it is decided that the heater 2 has a trouble. Then a self-tuning function is stopped and a display part is blinked to show the stop of the self-tuning function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a state quantity control device for controlling a state quantity such as temperature, humidity or pressure of an electric furnace, a refrigerator or a gas burner.

[0002]

2. Description of the Related Art As a state variable control device for adjusting a physical state variable to a predetermined state, for example, there is a temperature control device for controlling the internal temperature of an electric furnace as a state variable.

FIG. 8 is a configuration diagram showing the configuration of a conventional temperature control device. In FIG. 8, reference numeral 1 denotes an electric furnace for heating a workpiece S such as a ceramic material, and 2 denotes an electric furnace which is energized and supplied with electricity. A heater for heating the inside of the furnace 1, a thyristor 3 for adjusting electric power supplied to the heater 2, a temperature controller 4 for inputting a temperature set value and controlling the temperature, and a temperature controller having a self-tuning function. Reference numerals 5 and 5 denote temperature sensors including a thermocouple for detecting the temperature in the electric furnace 1.

Next, the operation will be described. The internal temperature of the electric furnace 1 is set as a target temperature by inputting a predetermined temperature to the temperature controller 4. The electric furnace 1 is heated by the heater 2, the internal temperature of the electric furnace 1 is detected by a temperature sensor 5, and a detection signal is input to a temperature controller 4. In the temperature controller 4, when a deviation occurs between the internal temperature of the electric furnace 1 detected by the temperature sensor 5 and the target temperature input to the temperature controller 4, the thyristor 3 is controlled using a predetermined control parameter. A control signal to be output is set, and the firing angle of the thyristor 3 is controlled by the control signal to control a heater current supplied to the heater 2. Thereby, control is performed so that the internal temperature of the electric furnace 1 becomes the set target temperature.

The above control parameters generally include P
PID parameters based on (proportional), I (integral), and D (differential) operations are used. Also, in order to perform optimal control,
Control parameters are updated as needed. Methods for automatically determining the control parameters include an auto-tuning method and a self-tuning method.

The former auto-tuning method is started manually, forcibly oscillating an operation amount (heater current), and measuring a response characteristic of a controlled object (inner temperature of the electric furnace 1) at that time, and measuring the response characteristic. This is a method of setting control parameters based on characteristics. The latter self-tuning method sets a predetermined value when a predetermined self-tuning start condition is satisfied, for example, when an SP value (set value) is changed, or when a disturbance occurs. When the control deviation between the control value and the control value is equal to or greater than a predetermined value, when the power is turned on again, or when the READY
It is automatically started when the RUN (operating state) changes from the (prepared state) to the RUN (operating state), and the control parameters are set by taking in the temperature detection value detected by the temperature sensor 5 while continuing the normal control. is there.

In the former auto-tuning method, the control is disturbed during the tuning and the operation amount changes or the PV (Proces
s Value) values can fluctuate significantly,
In the latter self-tuning method, the tuning is performed while the normal control is continued, so that the control parameters are determined without being conscious of the tuning, and by using the control parameters, the operation amount and the PV value can be adjusted. This is advantageous in that extreme fluctuations are eliminated and a very continuous and natural PV operation can be performed. It should be noted that the state variables include humidity, pressure, etc., in addition to temperature, and can be similarly applied to a device for controlling these.

[0008]

Since the conventional state variable control device is configured as described above, when the self-tuning start condition is satisfied, the self-tuning operation is performed even if a trouble occurs in the heater 2. Will be done.

For example, as shown in FIG. 9, when the control is started at time t0, if normal, the internal temperature of the electric furnace 1 is indicated by a broken line from time t1 to time t3 when the control ends. However, when the power of the heater 2 is turned off for some reason at time t1 and the heater 2 is restored at time t2, the internal temperature of the electric furnace 1 rises as shown by a solid line, and data during this time is also taken in. Control parameters are determined. For this reason, especially in the I operation, since the calculation is performed based on the detected value which is not the original data, an appropriate PID parameter cannot be obtained, and the optimal tuning cannot be performed.

As shown in FIG. 10, when the heater 2 is turned on at time t5 after the control is started at time t4, the dead time is from time t5 to t6.
The time from t4 to t6 is measured as a dead time, and the dead time becomes longer. In this case, too, an appropriate control parameter cannot be obtained, and similarly, it is impossible to perform the optimal tuning.

In order to avoid such a problem, in the operation manual, in the column of "Precautions for self-tuning", when the power of the operation end such as the heater 2 is inputted before the self-tuning is started, the operation end is stopped. Describes that the temperature controller 4 is in the READY state, and that the power of the operation terminal is turned on at the time of restart, but does not easily penetrate the operator, resulting in an erroneous operation. The conventional state quantity control device has such a problem to be solved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to avoid an inadvertent human error or an inconsistency in operation and to obtain a state quantity capable of always performing optimal control and tuning. The aim is to obtain a control device.

[0013]

According to the present invention, there is provided a state quantity control device comprising: an operation amount detection means for detecting an operation amount of an actuator when a predetermined self-tuning start condition is satisfied; Calculating means for calculating a control parameter for determining a control amount based on a current state amount detected when the operation amount of the selected actuator is within an appropriate operation range and a set value thereof.

According to the state quantity control device of the present invention, when the self-tuning start condition is satisfied and the calculation of the control parameter for determining the control amount cannot be executed,
It is provided with a notifying means for notifying that it could not be executed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1. In FIG. 1, reference numeral 1 denotes an electric furnace for heating a workpiece S such as a ceramic material, 2 denotes a heater (actuator) for heating the inside of the electric furnace 1 when energized, and 3 denotes a heater. 2 is a thyristor (control means) for adjusting the power supplied to 2; 4 is a temperature controller for inputting a temperature set value and controlling the temperature; 5 is a temperature controller having a self-tuning function; Temperature sensor (state quantity detection means) composed of a thermocouple or the like that detects
Reference numeral 6 denotes a current transformer (operating amount detecting means) for detecting a heater current supplied to the heater 2, and a lead wire for supplying power from the thyristor 3 to the heater 2 is passed through the current transformer 6.

FIG. 2 is a block diagram showing the structure of the temperature controller 4. In FIG. 2, reference numeral 11 denotes an input unit for inputting a temperature detection signal from the temperature sensor 5 and performing a predetermined signal conversion process, and 12 denotes an operation of calculating a PID parameter as a control parameter based on the target temperature and the current measured temperature. A control operation unit 13 for performing a predetermined signal conversion process based on the result calculated by the control operation unit 12 and outputting a control signal or an alarm signal to an operation unit (not shown); 14 a display unit 15; It is a panel unit having a setting unit 16.

The control calculation unit 12 performs various calculation processes and controls each unit of the configuration (CPU, calculation means, notification means).
21 and a ROM in which processing procedures and various data used when the CPU 21 performs arithmetic processing such as PID arithmetic are stored.
22 and a non-volatile RAM for storing PID parameters
23.

FIG. 3 is a terminal diagram of the temperature controller 4, and FIG.
Are the terminal numbers of the respective terminals. The temperature sensor 5 is connected between the terminals 4 and 5, and the current transformer 6
Is connected to terminals 11 and 12. Other terminals are used for the application shown in FIG.

FIG. 4 is a front view showing the display unit 15 of the temperature controller 4. In FIG. 4, reference numeral 31 denotes an upper display for displaying a measured current temperature and the like, 32 denotes a lower display for displaying a set target temperature and the like, and 33 denotes an LED which blinks during self-tuning.

Next, the operation of the CPU 21 will be described with reference to the flowcharts of FIGS. Step ST
In step 1, it is determined whether a self-tuning start condition has been satisfied. The self-tuning start conditions are as follows: when the SP value is changed, when a disturbance occurs and the control deviation between the SP value and the PV value exceeds a predetermined value, when the power is turned on again,
Alternatively, it is established when the state shifts from the REDY state to the RUN state.

In step ST2, one of the upper display units 31
The LED 33 at the lower right of the digit blinks to indicate that self-tuning is being performed.

In step ST3, self-tuning based on the flowchart of FIG. 6 is started. That is, in step ST11, a CT (Current Trans) value indicating the value of the heater current detected by the current transformer 6 is input.

In step ST12, it is determined whether or not the detected CT value is 0. If the CT value is not 0, it is determined that the heater 2 is normal, and the process proceeds to step ST13 to fetch data and calculate a PID parameter. In step ST14, the calculated PID parameter is
Write to M23.

In step ST15, it is determined whether or not to continue the self-tuning. To continue the self-tuning, the process returns to step ST11.

On the other hand, when the CT value is 0, it is determined that a trouble has occurred in the heater 2, and the process proceeds from step ST12 to step ST16 to stop the self-tuning function. At this time, the process proceeds to step ST17 without writing the PID parameter to the RAM 23. In step ST17, for example, the upper display unit 31 and the lower display unit 32 are blinked as an alarm code to notify a result indicating that the self-tuning function is stopped.

If the self-tuning is to be continued even when the CT value is 0, the process returns to step ST11. Therefore, as shown in FIG. 8, when the power of the heater 2 is turned off for some reason during the control and then the heater 2 is restored, no data is taken in while the CT value is 0, which affects the calculation of the PID parameter. Without affecting
Such an operation can be performed. When the self-tuning is completed, the process proceeds to step ST4 in FIG. 5, and the LED 33 is turned off.

If there is no change in the control method, step S
Returning to T1, in step ST5, the determined PI
Optimal control is performed based on the D parameter. That is,
When a deviation occurs between the current temperature in the electric furnace 1 detected by the temperature sensor 5 and the set value of the temperature, RA
A control signal based on the PID parameter stored in M23 is transmitted from the output unit 13 to the thyristor 3, the firing angle control is performed by the thyristor 3, and the controlled heater current is supplied to the heater 2 so that the optimum state is obtained. , The internal temperature of the electric furnace 1 is controlled to the target temperature. Step ST7 corresponds to the notifying means, and step ST13 corresponds to the calculating means.

As described above, according to the first embodiment, the CT value of the current transformer 6 is taken into the temperature controller 4, and if the CT value is 0, it is determined that there is some problem in the heater power supply or the like. Since the PID parameters are not changed, it is possible to avoid human inadvertent mistakes or driving inconsistencies, always determine the optimal PID parameters, and perform optimal tuning.

Further, since the result indicating that the self-tuning function has been stopped is notified by an alarm code or the like, when the calculation of the PID parameter cannot be executed, the effect can be confirmed. .

In the first embodiment, the heater 2 is used as an actuator for controlling the internal temperature of the electric furnace 1, but the present invention is not limited to this, and a refrigerator or a gas burner may be used. However, in this case, the operation detecting means used also corresponds to the actuator.

Further, in the first embodiment, the temperature control device for controlling the temperature as the state variable has been described. However, the present invention is not limited to this. Can be applied to

Further, step ST12 of the first embodiment
Then, when a trouble occurs in the heater 2, the CT value becomes 0.
It is determined whether or not the CT value is 0 on the assumption that the CT value becomes zero. However, when the CT value is compared with a predetermined threshold value, it is determined that a trouble has occurred when the CT value is equal to or less than the predetermined value. Is also good. Further, when a trouble occurs, the operation amount is not always reduced, and the heater current may be excessive. In such a case, as shown in FIG. 7, in step ST21, it may be determined that a trouble has occurred when the CT value exceeds the predetermined threshold value X, or a predetermined amount may be determined according to the actuator according to the actuator. An appropriate area can also be set.

[0033]

According to the present invention, when a predetermined self-tuning start condition is satisfied, the operation amount detection means for detecting the operation amount of the actuator, and the operation amount of the actuator detected by the operation amount detection means are appropriately adjusted. Calculation means for calculating a control parameter for determining a control amount based on a current state amount detected when the operation amount is within a proper operating range and a set value thereof. It is possible to avoid the above inconsistency, always determine the optimal control parameters, and perform the optimal tuning.

According to the present invention, when the self-tuning start condition is satisfied, if the calculation of the control parameter for determining the control amount cannot be executed, the notifying means is provided for notifying that the calculation could not be executed. Because we configured
When the calculation of the control parameter cannot be executed, a notification to that effect is given, and there is an effect that the confirmation can be made.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of a first embodiment of a state quantity control device (temperature control device) of the present invention.

FIG. 2 is a configuration diagram showing a configuration of the temperature controller of FIG. 1;

FIG. 3 is a terminal diagram of the temperature controller of FIG. 1;

FIG. 4 is a front view of the display unit of FIG. 2;

FIG. 5 is a flowchart showing the operation of the CPU of FIG. 2;

FIG. 6 is a flowchart showing a self-tuning operation of the CPU of FIG. 2;

FIG. 7 is a flowchart showing a self-tuning operation of another CPU of FIG. 2;

FIG. 8 is a configuration diagram showing a configuration of a conventional temperature control device.

FIG. 9 is an explanatory diagram for explaining a problem when the heater power is turned off during the self-tuning of FIG. 8;

FIG. 10 is an explanatory diagram for explaining a problem when the power of the heater is turned on after the self-tuning of FIG. 8 is started.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric furnace 2 Heater (actuator) 3 Thyristor (control means) 4 Temperature controller 5 Temperature sensor (state quantity detection means) 6 Current transformer (operation quantity detection means) 21 CPU (calculation means, notification means)

Claims (2)

[Claims] 1. A state quantity detecting means for detecting a current state quantity to be controlled, an actuator for changing the state quantity, and a current state quantity detected by the state quantity detecting means being set to a predetermined value. And a control means for controlling the actuator using a predetermined control parameter for determining a control amount such that the operation amount of the actuator is detected when a predetermined self-tuning start condition is satisfied. Operation amount detection means, and a control parameter for determining the control amount based on a current state amount detected when the operation amount of the actuator detected by the operation amount detection means is within an appropriate operation range and a set value thereof. And a calculating means for calculating the following. 2. When the self-tuning start condition is satisfied, when a calculation of a control parameter for determining a control amount cannot be executed, a notifying unit is provided for notifying that the calculation cannot be executed. The state quantity control device according to claim 1.