JPS60205701A - Process quantity controller - Google Patents

Abstract

PURPOSE:To accelerate stabilization of a control system by discriminating whether the control system is in the hunting state or not and changing a constant of control operation where the deviation between a measured value and a set value is reduced to zero if the control system is in the hunting state. CONSTITUTION:It is discriminated whether the control system is in the stable state where the absolute value of the deviation between the measured value and the set value is held within a prescribed value for a certain period or in the unstable state where said absolute value is not held there; and if the control system is in the unstable state, it is discrimination whether the control system is in the hunting state or not. In the hunting discriminating operation, an initial value is set to a hunting counting counter at a time t2, when the polarity of a deviation signal is first inverted, after the start of the control operation, and simultaneously, a time T2 which is the period of the hunting discrimination operation is set to a discriminating timer. The value of the counting counter is decreased at each of times t3-t5 when the polarity of the deviation signal is inverted, and the hunting state is discriminated if the value of the counting counter becomes zero in the period T2, and a proportional operation constant is reduced. Hereafter, this detecting operation is repeated until the control system is in the stable state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a process amount control device that performs control system stability determination, hunting suppression, and control calculation in parallel.

[Prior art]

2. Description of the Related Art Conventionally, there has been a temperature control device shown in FIG. 1, for example, as a process amount control device. In the figure, the temperature control device is a circuit consisting of an operational amplifier 1, a resistor 2, etc., and receives a temperature signal from a temperature detection section 3 installed in a controlled object (not shown) and a setting signal from a setting section 4. an error amplifier 5 that inputs the signal, an arithmetic control unit 6 that inputs the signal from the error amplifier 5 and performs control calculations (proportional, integral, and differential calculations), and a calculation control unit 6 that inputs the signal from the error amplification unit 5 and performs control calculations (proportional, integral, and differential calculations); A pulse width modulator 7 that outputs a width-modulated signal, a triac 9 operated by the signal from the pulse width modulator 7 via a photocoupler 8, and a heater 11 whose connection to a power source 10 is controlled by the triac 9. It has an operating section 12 consisting of:

In the above configuration, the temperature control device turns on and off the heater 11 using a pulse width modulated signal to bring the temperature of the controlled object to a predetermined value.

However, in conventional temperature control devices, the proportional constants, etc. of control calculations are set to empirically determined values, so if the various conditions of the controlled object change, the operation of the control system will hunt and become unstable. In order to reduce the error, the error amplifier is composed of an operational amplifier with a small offset, a high-precision resistor, etc., which leads to an increase in cost.

[Purpose of the invention]

The present invention has been made in view of the above points, and its purpose is to provide a process control device that speeds up the stabilization of a control system.

[Structure of the Invention] A process quantity control device of the present invention that achieves the above object includes a control calculation unit that performs control calculation to zero the eccentricity between a measured value and a set value. However, when the absolute value of the deviation is within a predetermined value, a state in which the absolute value of the deviation remains within a predetermined value is determined to be a stable state, and a state in which it is not maintained is determined to be an unstable state. The structure is such that it can cooperate with a hunting prevention means that determines whether or not a hunting state exists, and when a hunting state occurs, changes the constant of the control calculation to suppress hunting money.

Examples of the invention] The present invention will be described below with reference to the drawings.

FIG. 2 is a configuration diagram showing an embodiment of the invention. The temperature control device includes a temperature detection unit 23 that detects the dialysate temperature in the dialysate circuit 22 of the dialyzer 21 of the artificial dialysis machine.
and 24, and the signals E1 and E2 from the temperature detection section 23 and keyboard 25 are input via the A/D Kamata device 26, and a computer (calculation control) that performs control calculations and outputs duty ratio setting No. 18 E5. Department) 27 and computer 27
The clock signal E4f is divided into a predetermined frequency and the duty ratio pulse signal E is based on the duty ratio setting number E3.
A programmable frequency divider 28 that outputs a signal E5 and an operation section 29 that is controlled by a signal E5 and the like are provided. The ROM of the computer 27 stores a control calculation program, a stability determination and hunting determination program, a rise time improvement program, and the like. Further, the temperature detection section 23 includes a temperature sensor 30 installed in the dialysate circuit 22 and a temperature sensor 30 installed in the dialysate circuit 22.
Further, the temperature detection unit 24 converts the signal from the temperature sensor 32 installed in parallel with the temperature sensor 30 into a nausea signal, and converts the signal (temperature ) exceeds a predetermined value, the signal conversion alarm circuit 33 outputs an alarm signal E6t which changes from '1#' to '0'. On the helmet, the operation section 29 includes a heater 34 installed in the dialysate circuit 22, a heater power supply section 37 consisting of a power supply 35 and a triac 36 (P-7 Vi. 11 of the voltage E7 is input through the photocoupler 38, and the voltage E
, a zero-crossing signal generator 39 that outputs a zero-crossing signal E9, and a signal E5.

g6, E, and the watchdog timer signal E, of the computer 27. and an AND gate 41 which inputs and energizes the LIAC 36 via the photocoupler 40 (output signal E, ., of the photocoupler 40).

Next, the operation of the temperature control device having the above configuration will be briefly explained with reference to the drawings.

The computer 27 executes a rise time improvement operation, a hunting suppression operation, and a control calculation operation in parallel.

As shown in FIG. 3, the start-up time correction operation is performed when the difference between the setting signal E21 and the temperature signal E is . , when it is larger than a predetermined value Eo (r; 2,, g,) Eo), the integral function is disabled and the input to the integrating means is made zero), E2, -B.

When ≦Eo, the operation takes advantage of the integral function. For this reason, the computer 27 outputs a control signal based on proportional calculation when the player is a songwriter, and outputs a control signal based on proportional/integral calculation when the latter is the case. At this time, if the proportionality constant, integral constant, etc. are set to optimal values, the temperature signal E, as shown in Fig. 6 ((
), it matches the set value E21 without oversheeting (FIG. 6 will be described later).

As shown in Fig. 4, the hunting suppression operation is to determine whether the control system is in a stable state or not, and when the stability determination operation is in a stable state, control calculations are performed based on the proportional constant and integral constant that have been set previously. . The stable state here means the deviation I El
"21 + is a predetermined value Δe (within +, that is, +E,
g2. A state in which the state of +<Δe0 continues for a certain period of time (T,) l! i! 1 is 1, and anything else is considered an unstable state.

Then, in this unstable state, it is further determined whether or not the control system is in a hunting state.

The hunting discrimination operation will be explained with reference to FIGS. 4 and 5. FIG. 5 is a diagram showing that when the apparatus starts (time 1), the temperature signal E is in a hunting state with the set value "21" as the boundary.

Control operation starts. First, at time t2 when the polarity of the deviation number Ibi is reversed, the hunting counter is set to the initial value 1.
-ru. At the same time, a time T2 (which becomes the period of the hunting discrimination operation) is set in the discrimination timer.

After that, when the polarity of the deviation signal is reversed (ts + ta, ts
), the value of the counting counter is decremented every time. When the counter becomes zero during the period T2, it is determined that hunting is occurring, and the proportional calculation constant is reduced. Thereafter, the above detection operation is repeated until the control system becomes stable. If the counting counter does not reach zero during the period T2 of the hunting discrimination operation, it is determined that the setting value has been changed during the process and the conditions of the control system have changed, and the counting counter is set to zero and the operation is performed again.
Execute hunting determination operation from the beginning.

By setting the optimum proportionality constant in the hunting discrimination operation described above, hunting can be suppressed and stable control can be performed.

Next, the control calculation operation will be explained with reference to FIGS. 6 and 7.

Now, as shown in FIG. 6(a), the set value E is set at time t.
A case will be described in which the control is started at 2+ and the set value is changed to E22 at time t2. During times t to t2, the computer 27 performs control calculations to match the temperature quantity E with the set value E21, outputs a duty ratio setting signal E3 based on the calculation, and outputs the output signal of the programmable frequency divider 28. Determine the duty ratio at . The programmable frequency divider 28 divides the clock No. 8 E4 from the computer 27 to obtain the period T shown in FIGS. 6(b) and 6(c). Then, (outputs the pulse signal E5 with the duty ratio determined by the M number E3.

Further, even after time t2 when the set value is changed to E22, the computer 27 and the programmable frequency divider 28
performs the same operation as described above, and generates the signal E5 shown in FIG. 6(b).
(pulse signal after time t2), the operating section 29 is operated to bring the dialysate circuit 22 to a predetermined temperature.

On the other hand, the voltage E7 of the power supply 35 and the output signal E9 of the zero cross I generator 39 during operation are as shown in FIGS. 7(a) and 7(c). The signal E, as shown in FIG. 7 (G), is No. 48 E5. E6 and E. Only when both are '1' (when the output of the programmable frequency divider 28 is on, the temperature of the dialysate circuit 22 is below the set value, and the computer 27 is operating normally), the output signal of the AND gate 41 is '11'. This turns the triac 36 on and off.As a result, the voltage E applied to the heater 34
8 becomes Fig. 7 (b). That is, as long as the computer 27 does not malfunction and the temperature of the dialysate circuit 22 does not become abnormally high, the heater 34 will be replaced by the programmable frequency divider 28.
The current is applied in accordance with the duty ratio. As a result, the temperature of the dialysate circuit 2't reaches a predetermined value.

Note that the present invention is not limited to the above embodiment, that is, a temperature control device, and may be a device that controls other process quantities (physical changes), such as flow rate, liquid level, weight, etc. .

〔Effect of the invention〕

As described above, according to the process lid control device of the present invention, the stability determination of the control system, hunting suppression, and control calculation are executed in parallel, so that the control system can be stabilized quickly. Furthermore, by configuring the control calculation section with a computer and a programmable frequency divider to determine the duty ratio, cost reduction can be realized without increasing errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 5 to 7 are operation diagrams of an embodiment of the present invention. 23.24... Temperature detection unit, 25... Keyboard,
27... Computer, 28... Programmable frequency divider, 29... Operating unit, 34... Heater, 39...
・Zero cross signal generator. Figure 2 Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) In a control device equipped with a control calculation unit that performs control calculation to zero the deviation between a measured value and a set value, the control calculation unit is configured to maintain the absolute value of the deviation within a predetermined value for a certain period of time. stability determining means for determining whether the control system is in a hunting state when the control system is in a hunting state; 1. A process amount control device comprising: a non-hunting suppressing means for suppressing hunting by changing a constant of a control calculation. (2) The control calculation unit includes a computer that outputs a duty ratio setting signal based on the control calculation, and a frequency divider that divides the clock signal of the computer into a predetermined frequency, and the control calculation unit outputs a duty ratio setting signal based on the duty ratio setting signal. 2. The process amount control device according to claim 1, further comprising a programmable frequency divider that operates an operating section with a pulse signal having a duty ratio.