JP2767595B2 - Position proportional control device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement in a position proportional control device for an automatic valve (hereinafter, referred to as a “motor valve”) driven to open and close by a motor.

<< Summary of the Invention >> The present invention limits the variation of the operation amount to an extent that the motor valve can follow, and corrects the integral value according to the limited operation amount to make the operation amount and the valve opening coincide. Thus, over-integration is prevented to prevent overshoot, and quick response is improved.

<< Conventional Technology and its Problems >> Conventionally, as a position proportional control device for a motor valve, a deviation value e between a target value R and a control amount Y is calculated by PID to obtain an operation amount U.
The operation amount U is used to drive an on / off (ON / OFF) servo mechanism to feed back the opening amount (valve opening amount) V of the valve that is controlled to open and close, and the valve opening amount V and the operation amount U The opening / closing control of the valve is performed so as to coincide with.

However, in the above-described conventional position proportional control device, the operation amount obtained by the calculation from the target value R and the control amount Y is immediately stopped, but it is not until the valve driven by the motor reaches a predetermined opening degree. There is a problem that it takes a predetermined time (for example, one minute depending on the type of the drive motor, but it takes one minute), so that the control amount Y deviates from the target value R, that is, a so-called overshoot occurs.

This overshoot phenomenon will be further described with reference to a time chart of the control amount Y, the operation amount U, and the valve opening V in FIG.

Now, assuming that the control operation is started at t ₀ , the manipulated variable U immediately reaches 100%, but the valve opening degree V usually requires a certain period of time (for example, one minute) from fully closed to fully opened. because, it does not become immediately to 100% (fully open), up to 100% in the last time point t _1. Further, similarly and the operating amount U and valve opening degree V at t ₃ time coincides with the beginning when the operation amount U at t ₂ begins to decrease.

Thus, at the time of _{t 0 ~t 1, t 2 ~t} 3, shown in spite of the operation amount U and the valve opening degree V do not match (the valve opening of the Figure 3 Figure (There is only a difference between the dotted line and the solid line.) The PID calculation unit does not consider this at all.

Therefore, the integral value is calculated more than necessary at the point of time t _{2 to} t ₃ , which results in over-integration and an overshoot in which the control amount Y deviates from the target value R.
As described above, in the conventional position proportional control device, since control is performed without considering valve characteristics at all, there is a problem that performance cannot be improved.

<< Object of the Invention >> The present invention has been made in order to solve the above problems, and has as its object the object of an effect of a position proportional control device that enables the operation amount and the valve opening to coincide with each other. And

<< Structure and Effect of the Invention >> In order to achieve the above-described object, the present invention provides an operation amount calculated based on a deviation between a target value and a control amount, and an automatic valve controlled to open and close based on the operation amount. In a position proportional control device that is controlled so that the valve opening coincides, based on the manipulated variable and the valve opening of the automatic valve, while outputting a valve opening and closing signal for controlling the opening and closing of the automatic valve,
Valve characteristic value output means for outputting a valve characteristic value of the automatic valve expressed based on a control time with respect to a time required from the fully opened to fully closed state of the automatic valve; and a valve characteristic outputted by the valve characteristic value output means. When the total value of the value and the control amount in the previous control period is equal to or less than the maximum operation amount saturation value, the total value is corrected again to the maximum operation amount saturation value, while the value is larger than the maximum operation amount saturation value. If the subtraction value obtained by subtracting the valve characteristic from the control amount in the previous control period is equal to or greater than the minimum operation amount saturation value, the subtraction value is again corrected to the minimum operation amount saturation value. On the other hand, if the operation amount is smaller than the minimum operation amount saturation value, the operation amount is not corrected, and the operation amount is output within the range between the maximum operation amount saturation value and the minimum operation amount saturation value. Output means; and It is.

According to such a configuration, the change width of the calculated manipulated variable is corrected to such an extent that the motor valve can follow, so that the manipulated variable always coincides with the valve opening, and overshoot is not performed because over-integration is not performed. Is prevented. Thereby, the control performance of the position proportional control device can be greatly improved.

<< Description of Examples >> Hereinafter, the present invention will be described based on the illustrated examples.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the apparatus of the present invention, and FIG. 2 is a flowchart showing the operation of the operation.

In FIG. 1, a target value R is input to a comparison unit 1 and a control amount Y of a flow rate of a motor valve to be described later is input, and these are compared to detect a difference (deviation) e. Is done. The PID calculation unit 2 calculates an operation amount U of the valve opening of the motor valve based on the deviation e, and sends the operation amount U to the ON / OFF servo unit 3.

The ON / OFF servo unit 3 is configured to send a valve opening or valve closing signal to the motor unit 4 and feed back a valve opening signal of the motor unit 4. The motor unit 4 is configured to operate the controlled object 5 in the opening direction when receiving the open signal, and to operate in the closing direction when receiving the closing signal.

The ON / OFF servo unit 3 includes a comparison unit 10 that compares the operation amount U from the PID calculation unit 2 with the valve opening degree V, and a valve opening signal based on a deviation e ′ obtained by the comparison of the comparison unit 10. Alternatively, it comprises an ON / OFF signal generating section 11 for generating a close signal and a switching section 12 operated based on the open or close signal.

The ON / OFF servo unit 3 measures the valve characteristic ΔUlim, and sets this in the PID calculation unit 2. That is, the valve characteristic ΔUlim, which is the amount of opening (or closing) of the motor valve within one control period (sampling period), can be obtained by the lower paper container. , A closing signal and an opening signal are sent to determine the time required for the valve to fully open, and this time is required for one control period.

(Δt: control period, Topen: time required for the valve to be fully closed to fully open) The PID calculation unit 2 uses this valve characteristic ΔUlim to output the manipulated variable U according to the flow shown in FIG. It will be.

That is, prior to the control operation, the valve characteristic ΔUlim is set (step 100), and when the control operation is started, the PID calculation is performed based on the deviation e between the target value R and the control amount Y (step 102).

Next, correction is performed when the calculated manipulated variable is sent to the ON / OFF servo unit 12. This correction is made by the valve characteristic ΔUlim and the control amount Ukp in the previous control period, and is usually 100%
And the maximum and minimum manipulated variable saturation values Um set to 0%
ax and Umin are modified.

First, regarding the manipulated variable saturation value Umax, the previous manipulated variable Uk
It is determined whether the value obtained by adding the valve characteristic ΔUlim to p exceeds the operation saturation value Umax (step 104).

In this determination, if Ukp + ΔUlim is larger than Umax, the operation amount saturation value Umax ′ using Umax is corrected, and if Ukp + ΔUlim is smaller than Umax, the operation amount saturation value Umax ′ using Ukp + ΔUlim is corrected (steps 106 and 108). For example, if Ukp is 90%, ΔUl
When im is 20%, the sum is 110%, so at that time it is corrected to 100%, and Ukp is 70% and ΔUlim is 20%
In this case, since the sum is 90%, the sum becomes the corrected manipulated variable saturation value Umax 'at that time.

On the other hand, regarding the manipulated variable saturation value Umin, the previous manipulated variable Ukp
Then, it is determined whether or not the value obtained by subtracting the valve characteristic ΔUlim exceeds the operation amount saturation value Umin (step 110). In this judgment, if Ukp−ΔUlim is smaller than Umin, that Umin
Is used as the manipulated variable saturation value Umin ', and conversely, if it is large, Uk
Correction is made as the manipulated variable saturation value Umin 'using p-ΔUlim (steps 112 and 114).

In the PID calculation, integration is not performed when the manipulated variable exceeds the saturation value as in the conventional case (step 11).
6) In this case, as the saturation value, the saturation values Umax 'and Umin' corrected as described above are used.

From the PID calculation unit 2, as described above, Ukp + ΔUlim, Ukp−Δ
When Ulim is used and the operation amount U is larger than Ukp + ΔUlim or smaller than Ukp−ΔUlim, the operation amount U
To Ukp + ΔUlim, Ukp−ΔUlim and ON / OFF servo section 3
And the next control cycle, the process returns to step 100 again.

As described above, in this embodiment, even when the change width of the operation amount U calculated by the PID calculation is a magnitude that cannot be followed by the motor valve, the actually output operation amount U can follow the motor valve. Since it has been modified to a size of about
The manipulated variable U always coincides with the valve opening V. Also,
In this case, since the manipulated variable saturation value non-integration is executed for the corrected manipulated variable saturation values Umax 'and Umin', control performance is greatly improved without over-integration and overshoot. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram of a schematic configuration showing an embodiment of the apparatus of the present invention, FIG. 2 is a flowchart showing an operation of the operation, and FIG. 3 is an explanatory diagram showing a conventional control operation. 1 ... Comparator 2 ... PID calculation unit 3 ... ON / OFF servo unit 4 ... Motor unit 5 ... Control target

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05D 3/12 305 G05D 7/06

Claims (1)

(57) [Claims] An operation amount calculated based on a deviation between a target value and a control amount, and a position proportional control that is performed so that a valve opening of an automatic valve that is opened and closed based on the operation amount is equal to each other. The control device, based on the operation amount and the valve opening degree of the automatic valve, outputs a valve opening / closing signal for controlling the opening / closing of the automatic valve, and controls a time required from fully opening to fully closing of the automatic valve. Valve characteristic value output means for outputting a valve characteristic value of the automatic valve expressed based on time; and a sum of a valve characteristic value output by the valve characteristic value output means and a control amount in a previous control period. If the maximum operation amount is less than the maximum operation amount saturation value, the total value is corrected again to the maximum operation amount saturation value, while if the total value is larger than the maximum operation amount saturation value, the value is not corrected, and The subtracted value obtained by subtracting the valve characteristic from the control amount at If the minimum manipulated variable saturation value is equal to or greater than the minimum manipulated variable saturation value, the subtraction value is corrected again to the minimum manipulated variable saturation value. And a manipulated variable output means for outputting the manipulated variable within a range between the minimum manipulated variable saturation value and the minimum manipulated variable saturation value.