JPS638962Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an intermittent integral control device. More specifically, the present invention relates to an intermittent integral control device that performs quick recovery operations against disturbances.

[Conventional technology]

Intermittent integral control devices are used to control processes with large dead times. In that case, the intermittent integral control device intermittently performs integral calculations on the deviation between the measured value and the set value of the process at regular intervals not less than the dead time, and updates the control output accordingly. In this way, when the control device performs the integral calculation, more time than the dead time has elapsed since the last output update, so the process measurement value reflects the previous control result. By performing integral calculations based on process measurement values, processes with dead time can be appropriately controlled.

[Problem that the invention attempts to solve]

However, this is true only when the measured values of the process change relatively slowly, and if the measured values of the process include sudden disturbances, satisfactory control cannot be achieved. This is because the control device performs integral operations intermittently at fixed timings that are unrelated to the occurrence of disturbances, so for example,
If a disturbance occurs immediately after the output is updated by the integral calculation, the control output corresponding to this disturbance will not be updated until the next integration period, and even if the output is updated at the next integration period, the effect will be does not reach the process measurement value until further dead time has elapsed.

Also, if the timing of the integral operation is not appropriate after updating the control output to correspond to the disturbance,
The control output will deviate greatly from the appropriate value.

An object of the present invention is to provide an intermittent integral control device that quickly restores a disturbance to a disturbance, performs an integral operation at an appropriate timing even after the restoring operation, and reduces deviation of the control output from an appropriate value.

[Means for solving problems]

The present invention consists of an integral controller that performs integral calculations intermittently to determine the deviation between the process measurement value and the set value according to a timing signal, and an alarm when the deviation between the process measurement value and the set value exceeds a predetermined reference value. A deviation monitoring circuit that generates a signal, and timing for generating a timing signal to the integral controller at a constant cycle based on the reset time until the next notification signal is reset by the notification signal of this deviation monitoring circuit. This is an intermittent integral control device equipped with a circuit.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a conceptual block diagram of an embodiment of the present invention. In Figure 1, 1 is an integral controller that performs integral calculations on the deviation between the process measurement value E _M applied to the measurement input terminal and the set value E _S applied to the setting input terminal, and produces a control output E _O. . 2 is a timing circuit that intermittently generates a pulse signal of an appropriate pulse width at a constant cycle not less than the dead time of the process, and supplies this pulse signal to the integral controller 1 for a time corresponding to the pulse width. Performs integral calculation. 3 is a deviation monitoring circuit, and the measured value
The deviation between E _M and the set value E _S is monitored, and when it exceeds the reference value, the notification signal is sent to the timing circuit 2.
give to In response to this notification signal, the timing circuit 2 resets the timing and starts generating intermittent pulses again.

The operation of the device configured in this way is as follows. FIG. 2 shows an explanatory diagram of the operation. When there is no disturbance in the process, the integral controller 1 operates at a constant cycle according to regular timing pulses from the timing circuit 2 (dotted line waveform in FIG. 2).
When a disturbance occurs in the process and the deviation signal exceeds the reference value of the deviation monitoring circuit 3, the timing circuit 2 is reset by a notification signal from the deviation monitoring circuit 3 and generates the timing signal again. As a result, the integral calculation of the integral controller 1 starts at the same time as the occurrence of the disturbance, and the control output is updated. For this reason,
Even if the disturbance occurs immediately after the previous integral calculation, the control output corresponding to the disturbance is updated immediately. The next integral calculation is performed according to the timing pulse generated by the timing circuit 2 after a certain period, but at this time, since more than the dead time has elapsed since the update of the control output based on the disturbance, the process measurement value reflects the effect of the control output corresponding to the disturbance, and the integral calculation at this time is
This can be done based on such process measurements. Therefore, the time required for process restoration when a disturbance occurs is reduced to at least 1/2 of that in the conventional case.

Further, after the reset, the timing circuit 2 generates a timing signal to the integral controller 1 at a constant cycle based on the time of reset until the next notification signal arrives, so that the integral operation is performed at appropriate timing. The deviation of the control output from the appropriate value can be reduced. The reason for this will be explained below.

Figure 3 is a time chart of the control output _EO .

In the figure, the straight line l shows the appropriate value of the control output E _O , and the step-like waveform shown by the solid line is the actual control output. T ₁ to _{T 4} are integration periods, and T is an integration period.

When there is no disturbance in the process, the control output changes stepwise as shown by the solid line. When a disturbance occurs in the process at time _t1 , the timing circuit 2 is reset at this time and the integral calculation begins. Thereafter, until the timing circuit 2 is reset, integral calculations are performed at a constant period T with reference to time _t1 . As a result, the control output changes stepwise as shown by the broken line. The deviation of the control output from the proper value is d ₁ .

If integration is performed at the same timing as the previous integral operation after reset, the control output will change in a stepwise manner as shown by the dashed line, and the deviation of the control output from the appropriate value will be
d becomes ₂ .

For this reason, the deviation of the control output from the appropriate value can be reduced by performing integration at a constant period with reference to the reset time until the next notification signal arrives after the reset.

〔effect〕

In the present invention, once reset is performed, subsequent timing is determined based on the time of reset.
Therefore, appropriate operation timing is guaranteed not only at the time of reset but also after reset, and the deviation of the control output from the proper value can be reduced.

[Brief explanation of the drawing]

Figure 1 is a conceptual configuration diagram of an embodiment of the present invention;
3 and 3 are explanatory diagrams of the operation of the apparatus shown in FIG. 1. 1... Integral controller, 2... Timing circuit, 3
...Deviation monitoring circuit.

Claims (1)

[Scope of utility model registration request] An integral controller that performs integral calculations intermittently regarding the deviation between the process measurement value and the set value according to a timing signal, and a deviation that generates a notification signal when the deviation between the process measurement value and the set value exceeds a predetermined reference value. A monitoring circuit, and a timing circuit that is reset by the notification signal of the deviation monitoring circuit and generates a timing signal to the integral controller at a constant cycle based on the reset time until the next notification signal arrives. Intermittent integral control device.