JP4611896B2 - Control method and control apparatus - Google Patents

Description

  The present invention relates to a process control technique, and more particularly, to a control method and a control apparatus that control a relative quantity such as a state quantity difference measured in a control system having at least two control loops.

  FIG. 5A shows the configuration of a temperature controller that is a conventional control device (see, for example, Patent Document 1). A heat treatment work 1016 is carried into the furnace 1001, and the heater 1011, detection means 1012 for detecting the control temperature TC 1, detection means 1013 for detecting the surface temperature TC 2 of the work 1016, and the deepest temperature TC 3 of the work 1016. Detection means 1014 for detecting is arranged. Reference numeral 1002 denotes a power regulator. The control unit 1003 includes a comparator 1031 that compares the control temperature TC1 and the execution program pattern set value 1033, a control calculation unit 1032 such as PID controlled by the output of the comparator 1031, and the surface temperature TC2 of the workpiece 1016 and the deepest surface temperature TC2. A temperature difference detector 1034 that detects a difference from the temperature TC3, a temperature difference setter 1035 that sets a predetermined temperature difference, and an output of the temperature difference detector 1034 and an output of the temperature difference setter 1035 are compared. The comparator 1036, the change rate detector 1038 for detecting the temperature change rate of the deepest temperature TC3, and the output of the change rate detector 1038 are compared with the output of the change rate setter 1039 for setting a predetermined temperature change rate. The comparator 1040 to perform, the inclination calculation based on the output of the comparator 1036 and the output of the comparator 1040, and the execution program pattern set value 103 And an inclined calculator 1037 for controlling.

The maximum allowable temperature difference is set in the temperature difference setting unit 1035, and the maximum allowable temperature change rate is set in the change rate setting unit 1039. With the configuration of FIG. 5A, the gradient in the execution program pattern set value 1033 is constantly corrected so that one or both of the temperature difference and the temperature change rate in the heat-treated workpiece 1016 are within the specified temperature tolerance. The
Focusing on the portion surrounded by the broken line in FIG. 5A, the state quantity for calculating the temperature difference (TC2-TC3) and the temperature change rate dTC3 / dt based on the measured temperatures TC1, TC2, TC3. You can see that the conversion is taking place. That is, the temperature controller of FIG. 5A includes the state quantity conversion unit 1041 that calculates the temperature difference (TC2−TC3) and the temperature change rate dTC3 / dt (FIG. 5B).

  FIG. 6 (a) shows a configuration of a temperature control device which is another conventional control device (see, for example, Patent Document 2). In the figure, reference numeral 2002 denotes a reaction tube of the vertical heat treatment apparatus 2020. Inside the reaction tube 2002, a temperature sensor A for detecting the temperature in the vicinity of the semiconductor wafer mounted on the wafer board 2021 is provided. A temperature sensor B that detects the temperature of the outer surface of the reaction tube 2002 is provided. The deviation circuit unit 2031 outputs a deviation obtained by subtracting a correction value described later from the target value of the temperature sensor A, that is, the target value of the temperature sensor B. The deviation circuit unit 2032 outputs a deviation obtained by subtracting the detection value of the temperature sensor B from the target value of the temperature sensor B to the PID adjustment unit 2004. The PID adjustment unit 2004 performs PID calculation based on the input deviation and outputs the calculation result to the power control unit 2005. The power control unit 2005 uses the vertical heat treatment apparatus based on the output value of the PID adjustment unit 2004. The power supply amount to the heater 2006, which is a heating source of 2020, is controlled. On the other hand, when the detected value of the temperature sensor B converges to the target value, the correction value output unit 2007 calculates the difference (A−B) between the detected value of the temperature sensor A and the detected value of the temperature sensor B at the time of convergence. As a correction value, the target value of the temperature sensor B is corrected by the correction value. With the configuration of FIG. 6A, the detection value of the temperature sensor A converges to the target value.

When attention is paid to a portion surrounded by a broken line in FIG. 6A, it is understood that state quantity conversion for calculating a temperature difference (A−B) based on a plurality of measured temperatures A and B is performed. it can. That is, the temperature adjustment device in FIG. 6A includes the state quantity conversion unit 2008 that calculates the temperature difference (A−B) (FIG. 6B).
As described above, efforts have been conventionally made to incorporate not only the actual state quantity itself but also the difference between a plurality of state quantities into the control system.

  Furthermore, the inventor of the present invention controls the state quantity while preferentially controlling the relative state quantity such as the state quantity difference in a form in which the controller operation amount and the actual actuator output correspond to each other on a one-to-one basis. A control method that can simultaneously control a reference absolute state quantity such as a quantity average value has been proposed (see Patent Document 3, Patent Document 4, and Patent Document 5). The principle of the control method disclosed in Patent Document 3, Patent Document 4, and Patent Document 5 (hereinafter referred to as the control method of the prior application) will be described.

  First, in the prior application and the present invention, the absolute state quantity serving as a reference, such as an average value of the state quantity, is a reference state quantity, and a relative quantity (for example, a state quantity difference) from the reference state quantity is maintained at a predetermined value. The state quantity controlled to do so is referred to as a follow-up state quantity. Also, the setting value for the reference state quantity is the reference state quantity setting value, the measurement value for the reference state quantity is the reference state quantity measurement value, the setting value for the tracking state quantity is the tracking state quantity setting value, and the tracking state quantity measurement value is the tracking state Measured value, set value for the relative amount of the reference state amount and the tracking state amount is the tracking state amount relative setting value, and the measured value of the relative amount of the reference state amount and the tracking state amount is the tracking state amount relative measured value, the reference state An internal set value set inside the controller with respect to the quantity is referred to as a reference state quantity internal set value, and an internal set value set inside the controller with respect to the follow-up state quantity is referred to as a follow-up state quantity internal set value. Examples of the state quantity include temperature, pressure, and flow rate.

  In the control method of the prior application, the manipulated variable MV is calculated using the state quantity internal set value SP ′ set inside the controller, separately from the state quantity set value SP given from the outside. At this time, the state quantity internal set value SP ′ is separated into an element SPm for the reference state quantity and an element ΔSP for the relative quantity of the reference state quantity and the follow-up state quantity (SP ′ = SPm + ΔSP). Further, in the control method of the prior application, when the set values SPm and ΔSP that are actually given are applied as they are by the interpolation / extrapolation calculation (SP ′ = ASP + (1−A) PV) with the state quantity measurement values. Focusing on the fact that the characteristics of the controller can be shifted to the low sensitivity side or the high sensitivity side, the sensitivity of the reference state quantity and the sensitivity of the relative quantity of the reference state quantity and the tracking state quantity. Are converted into state quantity internal set values SP ′ that can be individually shifted.

  As described above, in the control method of the prior application, the state quantity internal setting value SP ′ is separated into the element SPm with respect to the reference state quantity and the element ΔSP with respect to the relative quantity between the reference state quantity and the follow-up state quantity. The value SP ′ is obtained by interpolation / extrapolation between the state quantity set value SP and the state quantity measurement value PV, and is used to calculate the operation amount MV. Thus, in the control method of the prior application, the response characteristic of the reference state quantity such as the average value of the state quantity is shifted to the low sensitivity side, and the relative amount of the reference state quantity and the tracking state quantity such as the state quantity difference is changed. If the response characteristic is shifted to the high sensitivity side, the follow-up state quantity relative measurement value ΔPV becomes the follow-up state quantity relative set value ΔSP before the reference state quantity measurement value PVm follows the reference state quantity set value SPm. Therefore, it is possible to perform control to change the reference state quantity to a desired value while maintaining the relative amount between the reference state quantity and the following state quantity at a desired value.

  Further, according to the configuration of the control method of the prior application, the only difference from the normal control system is that the state quantity set value SP is converted into the state quantity internal set value SP '. That is, a control that controls the reference state quantity at the same time while preferentially controlling the relative quantity between the reference state quantity and the follow-up state quantity in a form in which the operation amount of the controller and the actual actuator output have a one-to-one correspondence. A method can be provided.

Here, of the above two points of interest, calculation of the state amount internal set value SP ′ by interpolation / extrapolation between the state amount set value SP and the state amount measured value PV (hereinafter referred to as the first point of interest). ). With reference to the state quantity set value SP and the state quantity measurement value PV, it is considered to convert to a state quantity internal set value SP ′ set in the controller by the following formula using a specific coefficient A.
SP ′ = ASP + (1-A) PV (1)
However, the coefficient A is a real number larger than 0. At this time, if A = 1, SP ′ = SP, which means that the state quantity set value SP is not converted at all.

  If the value of the coefficient A is 0 <A <1 in the equation (1), the converted state quantity internal setting value SP ′ is a numerical value between the original state quantity setting value SP and the state quantity measurement value PV ( Interpolation). Therefore, for example, when the deviation is calculated by a PID controller or the like, the difference between the state quantity set value SP and the state quantity measurement value PV is larger than the deviation Er = SP−PV between the state quantity set value SP and the state quantity measurement value PV. Deviation Er ′ = SP′−PV has a smaller absolute value. As a result, the change in the operation amount is more gradual when the operation amount MV ′ is calculated based on the deviation Er ′ than when the controller calculates the operation amount MV based on the deviation Er. That is, if the value of the coefficient A is 0 <A <1, the response characteristic of the controller shifts to a characteristic in which stability is emphasized (low sensitivity).

  On the other hand, if the value of the coefficient A is A> 1, the converted state quantity internal setting value SP ′ is a numerical value that is further away from the state quantity measurement value PV than the original state quantity setting value SP (extrapolation relationship). become. Therefore, for example, when the deviation is calculated by a PID controller or the like, the difference between the state quantity set value SP and the state quantity measurement value PV is larger than the deviation Er = SP−PV between the state quantity set value SP and the state quantity measurement value PV. Deviation Er ′ = SP′−PV has a larger absolute value. As a result, the change in the operation amount becomes more severe when the operation amount MV ′ is calculated based on the deviation Er ′ than when the controller calculates the operation amount MV based on the deviation Er. In other words, if the value of the coefficient A is A> 1, the response characteristic of the controller shifts to a characteristic in which the responsiveness is emphasized (high sensitivity).

Next, of the above two points of interest, the state quantity internal set value SP ′ is separated into an element for the reference state quantity and an element for the relative quantity of the reference state quantity and the follow-up state quantity (hereinafter referred to as the second quantity). Will be described). When simultaneously controlling the reference state quantity and the relative quantity of the reference state quantity and the follow-up state quantity, the state quantity set value SP is expressed by the element SPm with respect to the reference state quantity, the reference state quantity, and the follow-up state as shown in the following equation. It can be separated into the element ΔSPm with respect to the relative amount to the amount.
SP = SPm + ΔSPm (2)

Further, according to the state quantity set value SP, the state quantity measurement value PV can also be separated into a reference state quantity measurement value PVm and a follow-up state quantity relative measurement value ΔPVm as in the following equation.
PV = PVm + ΔPVm (3)

Here, the first focus point and the second focus point are summarized as follows from the formulas (1) to (3).
SP ′ = A (SPm + ΔSPm) + (1-A) (PVm + ΔPVm)
= ASPm + (1-A) PVm + AΔSPm + (1-A) ΔPVm
... (4)

At this time, ASPm + (1-A) PVm in the equation (4) is an element relating to the reference state quantity, and AΔSPm + (1-A) ΔPVm is an element relating to the relative quantity between the reference state quantity and the follow-up state quantity. That is, since both are separated into linear combination equations that give an interpolating relationship and an extrapolating relationship, respectively, the interpolating relationship and the extrapolating relationship are given by individual coefficients A and B as follows. It becomes possible.
SP ′ = ASPm + (1-A) PVm + BΔSPm + (1-B) ΔPVm
... (5)

In Expression (5), A is a coefficient related to the reference state quantity, and B is a coefficient related to the relative quantity between the reference state quantity and the follow-up state quantity. When there are a plurality of control loops, the coefficient B relating to the relative amount of the reference state quantity and the follow-up state quantity is preferably given to each control loop individually. , 3,...) The following state quantity set value SPi may be converted for the following tracking state quantity.
SPi ′ = AmSPm + (1−Am) PVm + BiΔSPim
+ (1-Bi) ΔPVim (6)

  In Formula (6), SPi ′ is an internal set value for the i-th tracking state quantity, ΔSPim is a tracking state quantity relative setting value that is a relative value between the reference state quantity and the i-th tracking state quantity, and ΔPVim is A follow-up state quantity relative measurement value, which is a measurement value of a relative quantity between the reference state quantity and the i-th follow-up state quantity, Bi is a coefficient relating to a relative quantity between the reference state quantity and the i-th follow-up state quantity. The coefficient Am related to the reference state quantity may be given to each control loop or may be given to each control loop individually.

Further, in the equation (6), it is needless to say that ΔSPim = SPi−SPm and ΔPVim = PVi−PVm, and the following equivalent substitution can be easily performed.
SPi ′ = AmSPm + (1−Am) PVm + BiΔSPim
+ (1-Bi) (PVi-PVm) (7)
SPi '= AmSPm + (1-Am) PVm + Bi (SPi-SPm)
+ (1-Bi) (PVi-PVm) (8)

  According to the above principle, the state quantity internal set value SP ′ that can individually shift the sensitivity of the reference state quantity and the sensitivity of the relative quantity of the reference state quantity and the tracking state quantity is obtained. Next, the principle of preferentially controlling the relative amount between the reference state amount and the follow-up state amount will be described. In Expression (8), if the relationship between the coefficient Am related to the reference state quantity and the coefficient Bi related to the relative quantity between the reference state quantity and the follow-up state quantity is Am = Bi = 1, SPi ′ = SPi. At this time, the state quantity internal set value SPi 'is not changed from the state quantity set value SPi at all, and the sensitivity is not changed at all from the normal control. Here, what is particularly important is the coefficient Bi relating to the relative amount between the reference state amount and the follow-up state amount. By setting Bi> 1, the sensitivity is improved particularly with respect to the relative amount between the reference state amount and the follow-up state amount. The controller can be operated to preferentially control the amount.

JP-A-8-095647 JP-A-9-199491 JP 2005-309941 A JP 2005-309942 A JP 2005-309943 A

  In the control method of the prior application, the coefficient Bi relating to the relative amount is handled as a preset constant value. If the state quantity difference can be controlled within a desired range in the transient state of control and a stable behavior can be obtained in the settling state, there is no problem in handling the coefficient Bi as a constant value. However, when the state quantity difference is to be controlled in a desired range with high accuracy in the transient state, the coefficient Bi must be set to a sufficiently large value. However, if the coefficient Bi is excessively increased, the stability in the settling state is increased. However, depending on the situation, a large value of the coefficient Bi may cause the control to become unstable. Hereinafter, control instability due to an increase in the coefficient Bi will be described with reference to the drawings.

  FIG. 7 is a diagram illustrating a simulation result of step response by PID control when there are three temperature control loops. FIG. 8 and FIG. 9 show that in the control method of the prior application, the temperature control loop is three, the average value of the three control loops is adopted as the reference state quantity, and the three control loops are used as the follow-up state quantity. It is a figure which shows the simulation result at the time of employ | adopting each state quantity and aiming at making the temperature difference of each control loop small. 7A, FIG. 8A, and FIG. 9A are diagrams showing step responses of the control system when the temperature set values SP1, SP2, and SP3 are changed from 0 to 40. FIG. b), FIG. 8B, and FIG. 9B are enlarged views of FIG. 7A, FIG. 8A, and FIG. 9A, respectively. Detailed conditions for the simulation will be described later.

Since normal PID control does not give interaction to the three control loops, the simulation results of PID control shown in FIGS. 7A and 7B show the temperature difference (temperature measurement value PV1 in the transient state). , PV2, PV3) is large.
The simulation results shown in FIGS. 8A and 8B show that the value of the coefficient Am is set to 1.0 and the values of the coefficients B1, B2, and B3 are set to 3.0 in the control method of the prior application. The temperature difference in the transient state is considerably smaller than those in FIGS. 7 (a) and 7 (b). However, when FIG. It turns out that it is insufficient.

  In the simulation results shown in FIGS. 9A and 9B, the value of the coefficient Am is set to 1.0 and the values of the coefficients B1, B2, and B3 are set to 6.7 in the control method of the prior application. Although the temperature difference in the transient state is further smaller than in the cases of FIGS. 8A and 8B, the temperature measurement value PV1, It can be seen that vertical movements occur in the temperature measurement values PV1, PV2, and PV3 in the vicinity of PV2 and PV3 reaching the temperature setting values SP1, SP2, and SP3, and the control characteristics are deteriorated.

  The present invention has been made in order to solve the above-described problem, and maintains an absolute amount such as an average value of a plurality of state quantities while maintaining a relative amount such as a state quantity difference between the plurality of state quantities at a desired value. It is an object of the present invention to provide a control method and a control apparatus that can achieve both controllability of a relative amount in a transient state and stability of control in a settling state in a control system that performs control to change to a desired value.

According to the present invention, in a control method of a control system having at least two parallel PID control loops, a state quantity serving as a specific reference is set as a reference state quantity, and a relative quantity with respect to the reference state quantity is set to a predetermined value. When the state quantity controlled so as to be maintained is set as the tracking state quantity, the tracking state quantity set value SPi among the plurality of control calculation input values input to the PID controller that controls the tracking state quantity is set as the tracking state quantity. A calculation procedure for converting the set value SPi ′ into the PID controller and converting the set value SPi ′ is provided. The calculation procedure includes a reference state quantity set value SPm set in advance as the control calculation input value and a measured reference state. When a quantity measurement value PVm, a preset follow-up state quantity set value SPi, and a measured follow-up state quantity measurement value PVi are input, the reference state of the follow-up state quantity measurement value PVi A first coefficient Bi that defines the degree of followability to the quantity measurement value PVm, and a second coefficient Am that defines the degree of responsiveness of the reference state quantity measurement value PVm to the reference state quantity set value SPm. Is used to calculate the tracking state quantity internal set value SPi ′ by SPi ′ = AmSPm + (1−Am) PVm + Bi (SPi−SPm) + (1−Bi) (PVi−PVm). The followability of the value PVm to the reference state quantity set value SPm, the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measured value PVi and the reference state quantity measured value PVm, and the reference state quantity set value The followability to the relative amount SPi-SPm, which is the difference of SPm, is controlled separately, and further, the first coefficient is based on the deviation between the follow-up state amount set value SPi and the follow-up state amount measured value PVi. Bi It includes a switching determination procedure changing Ri, the switching determination procedure, when the there is the follow-up state quantity measurement value PVi distant point than a specified range of follow-up state quantity set point SPi is given as the first coefficient Bi And when the tracking state quantity measurement value PVi is close to the specific range from the tracking state quantity setting value SPi, the degree of tracking ability is greater than the first value. Also, a weak predetermined second value is selected as the first coefficient Bi .
Further, according to the present invention, in a control method of a control system having at least two parallel PID control loops, a state quantity serving as a specific reference is set as a reference state quantity, and a relative quantity with respect to the reference state quantity is defined in advance. When the state quantity controlled so as to maintain the value is set as the follow-up state quantity, the follow-up state quantity measurement value PVi among the plurality of control calculation input values input to the PID controller that controls the follow-up state quantity is set as the follow-up state. A calculation procedure for converting the measured value into an internal measurement value PVi ′ and inputting the value to the PID controller is provided. The calculation procedure is performed by measuring a preset reference state quantity setting value SPm as the control calculation input value. When a reference state quantity measurement value PVm, a preset follow-up state quantity set value SPi, and a measured follow-up state quantity measurement value PVi are input, the base of the follow-up state quantity measurement value PVi A first coefficient Bi that defines the degree of followability to the quasi-state quantity measurement value PVm, and a second coefficient that defines the degree of responsiveness of the reference state quantity measurement value PVm to the reference state quantity set value SPm By using Am, the tracking state quantity internal measurement value PVi ′ is calculated by PVi ′ = (1−Am) SPm + AmPVm + (1−Bi) (SPi−SPm) + Bi (PVi−PVm). The followability of the measured value PVm to the reference state quantity set value SPm, the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measured value PVi and the reference state quantity measured value PVm, and the reference state quantity set The followability to the relative amount SPi−SPm, which is the difference between the values SPm, is controlled separately, and further, based on the deviation between the follow-up state amount set value SPi and the follow-up state amount measured value PVi, coefficient a switching determination procedure for switching i, and when the tracking state amount measurement value PVi is at a point farther than a specific range from the tracking state amount set value SPi, the switching determination procedure is performed as the first coefficient Bi. When a predetermined first value is selected and the follow-up state quantity measurement value PVi is near a point within the specific range from the follow-up state quantity set value SPi, the degree of follow-up is the first value. A weaker predetermined second value is selected as the first coefficient Bi.

Further, according to the present invention , in a control method of a control system having at least two parallel PID control loops, a state quantity serving as a specific reference is set as a reference state quantity, and a relative quantity with respect to the reference state quantity is defined in advance. When the state quantity controlled so as to maintain the value is the follow-up state quantity, the follow-up state quantity deviation Eri calculated based on a plurality of control calculation input values input to the PID controller that controls the follow-up state quantity Is converted into a follow-up state quantity internal deviation Eri ′ and input to the controller, and the calculation procedure includes a reference state quantity set value SPm set in advance as the control calculation input value, and a measurement When the measured reference state quantity measured value PVm, the preset follow-up state quantity set value SPi, and the measured follow-up state quantity measured value PVi are input, the follow-up state quantity measured value PVi A first coefficient Bi that defines the degree of followability to the reference state quantity measurement value PVm, and a second coefficient that defines the degree of responsiveness of the reference state quantity measurement value PVm to the reference state quantity set value SPm. By using the coefficient Am and calculating the tracking state quantity internal deviation Eri ′ by Eri ′ = Am (SPm−PVm) + Bi {(SPi−SPm) − (PVi−PVm)}, the reference state quantity measurement value The followability of PVm to the reference state quantity set value SPm and the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measured value PVi and the reference state quantity measured value PVm, and the reference state quantity set value SPm Are separately controlled in accordance with the relative amount SPi-SPm, and further, based on the deviation between the following state value setting value SPi and the following state value measured value PVi, the first coefficient Bi. Switch The switching determination procedure includes a predetermined value as the first coefficient Bi when the tracking state amount measurement value PVi is at a point far from a specific range from the tracking state amount set value SPi. When the first value is selected and the follow-up state quantity measured value PVi is close to the specific range from the follow-up state quantity set value SPi, the degree of follow-up is less than the first value. A weak predetermined second value is selected as the first coefficient Bi.
Further, in one configuration example of the control method of the present invention, the switching determination procedure is performed at a time when the follow-up state amount setting value SPi exceeds a predetermined determination index Cr. When a predetermined first value is selected as the coefficient Bi of the tracking state quantity set value SPi and the tracking state quantity measurement value PVi is smaller than a predetermined determination index Cs. After this time, a predetermined second value is selected as the first coefficient Bi .

Further, according to the present invention, in a control system apparatus having at least two parallel PID control loops, a specific reference state quantity is set as a reference state quantity, and a relative quantity with respect to the reference state quantity is a predetermined value. When the state quantity controlled to maintain the tracking state quantity is a tracking state quantity, an operation amount for controlling the tracking state quantity is calculated, and the calculated operation quantity is output to the control target of the corresponding PID control loop. Calculation of an internal input value to be input to the PID controller after converting the tracking state quantity set value SPi of the PID controller and a plurality of control calculation input values input to the PID controller into the tracking state quantity internal setting value SPi ′ The internal input value calculation unit includes, as the control calculation input value, a preset reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, When the follow-up state quantity set value SPi and the measured follow-up state quantity measurement value PVi are input, the degree of followability of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm is determined. Using the first coefficient Bi to be defined and the second coefficient Am to define the degree of responsiveness of the reference state quantity measurement value PVm to the reference state quantity set value SPm, the tracking state quantity internal set value By calculating SPi ′ by SPi ′ = AmSPm + (1−Am) PVm + Bi (SPi−SPm) + (1−Bi) (PVi−PVm), the reference state quantity measurement value PVm is changed to the reference state quantity set value SPm. Followability and the relative amount SPi-SPm that is the difference between the tracking state amount setting value SPi of the relative amount PVi-PVm that is the difference between the tracking state amount measurement value PVi and the reference state amount measurement value PVm and the reference state amount setting value SPm. And a coefficient switching determination unit that switches the first coefficient Bi based on a deviation between the following state value set value SPi and the following state value measured value PVi, The coefficient switching determination unit selects a predetermined first value as the first coefficient Bi when the tracking state quantity measured value PVi is at a point far from a specific range from the tracking state quantity set value SPi. When the follow-up state quantity measurement value PVi is near a point within the specific range from the follow-up state quantity set value SPi, a predetermined second value whose degree of follow-up is weaker than the first value. Is selected as the first coefficient Bi .

  According to the present invention, in a control system having at least two control loops, a state quantity serving as a specific reference is set as a reference state quantity, and a relative quantity with the reference state quantity is maintained at a predetermined value. A calculation procedure in which one of a plurality of control calculation input values input to the controller that controls the tracking state quantity is converted into an internal input value and input to the controller when the controlled state quantity is a tracking state quantity In this calculation procedure, the internal input value is calculated as the sum of the first element with respect to the reference state quantity and the second element with respect to the relative quantity, thereby obtaining a state quantity difference between the reference state quantity and the follow-up state quantity, etc. It is possible to realize control for changing the reference state quantity such as the average value of the state quantity to a desired value while maintaining the relative quantity of the desired quantity. Further, in the present invention, since a control system in which the operation amount of the controller and the actual actuator output correspond one-to-one can be configured, integral wind-up can be prevented, and parameters conventionally devised. The controller can be adjusted by applying an adjustment method or automatic adjustment function. Further, by using a value obtained by multiplying the element of the input value for control calculation with respect to the relative quantity by the first coefficient as the second element of the internal input value, the reference state quantity is controlled while preferentially controlling the relative quantity. Can also be controlled simultaneously. Further, in the present invention, when the follow-up state quantity measurement value PVi is at a point far from the specific range from the follow-up state quantity set value SPi, a predetermined first value is selected as the first coefficient, and the follow-up state quantity When the follow-up state quantity measurement value PVi is near a point within a specific range from the set value SPi, the degree of followability of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm is weaker than the first value. By selecting the predetermined second value as the first coefficient, the effect that the relative amount follows the desired value can be strongly obtained in the transient state, and the relative amount is controlled when the set value is approached. Since the effect can be weakened and the vertical movement of the follow-up state quantity measurement value can be suppressed, both the controllability of the relative amount in the transient state and the stability of the control in the settling state can be achieved.

  Further, in the present invention, the tracking state quantity measured value PVi is measured at a point farther than the specific range from the tracking state quantity setting value SPi by comparing a predetermined determination index Cr with a change in the tracking state quantity setting value SPi. By comparing a value representative of the deviation for each follow-up state quantity with a preset determination index Cs, a close point within a specific range from the follow-up state quantity set value SPi can be determined. It can be determined whether or not there is a follow-up state quantity measurement value PVi.

[Principle of the Invention]
In the transient state, when the follow-up state quantity measurement value PVi is at a relatively distant point from the follow-up state quantity set value SPi, it is preferable that the effect of reducing the state quantity difference works more strongly. Since the value PVi and the follow-up state quantity set value SPi are separated from each other, the vertical movement of the follow-up state quantity measured value PVi is not substantially noticeable. On the other hand, when the follow-up state quantity measurement value PVi is at a relatively close point from the follow-up state quantity set value SPi, the need for a stronger effect of reducing the state quantity difference becomes smaller, and at the same time, the follow-up state quantity measurement value The vertical movement of PVi becomes noticeable. The present invention focuses on this point. That is, with regard to the step response, in the first half of the response in which the follow-up state quantity measurement value PVi is relatively far from the follow-up state quantity set value SPi, the movements as shown in FIGS. 9A and 9B are preferable. In the second half of the response in which the follow-up state quantity measurement value PVi is relatively close to the quantity setting value SPi, the movements as shown in FIGS.

  The present invention selects a predetermined first value as the coefficient Bi when the follow-up state quantity measurement value PVi is at a point far from a specific range from the follow-up state quantity set value SPi on the basis of the above point of interest. When the follow-up state quantity measurement value PVi is near a point within a specific range from the state quantity set value SPi, the degree of followability of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm is higher than the first value. The above-mentioned problem is solved by switching to select a predetermined second value that is also weak as the coefficient Bi.

  Specifically, when there is a change in the follow-up state amount setting value SPi exceeding the preset determination index Cr, switching is performed so that the first value is selected as the coefficient Bi after this point. When the value representative of the deviation becomes smaller than the preset determination index Cs, the second value is selected as the coefficient Bi after this point. As a value representative of the deviation for each follow-up state quantity, for example, there is an average value of absolute values of deviations between the follow-up state quantity set value SPi and the follow-up state quantity measurement value PVi. Note that the coefficient Bi is not limited to the first value and the second value, but three or more are prepared, and the degree of followability of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm is further detailed. You may make it switch.

  In the present invention, for the n control loops, control for maintaining the relative amount at a desired value, more specifically, control for reducing the state quantity difference is assumed. In the transient state at the time of step response, the state quantity change speed is large, so the probability that the state quantity difference deviates from the target level (or allowable level) is naturally high. That is, for example, when there are two state quantities, and there is exactly the same state quantity value (following state quantity measurement value) in a certain control period (measurement period), two state quantity changes observed in the next control period When the width ratio is 4: 3, the larger the state quantity change speed, the larger the difference in the ratio appears as a state quantity difference. On the other hand, even when the ratio of the two state quantity change widths is 4: 3 when the state is almost in a settling state, the speed of the state quantity change is small. Even if it appears, there is only a small difference in the state quantity. Therefore, it is necessary to increase the effect of reducing the state quantity difference in the transient state where the state quantity change speed is large.

  On the other hand, in the state where the settling state or follow-up state quantity measurement value PVi converges within a specific range from the follow-up state quantity set value SPi, the state quantity difference itself basically converges within a desired allowable range. Therefore, the necessity to reduce the state quantity difference is small, and it is rather preferable not to move the manipulated variable MVi in order to reduce the state quantity difference. Therefore, in the settling state or a state corresponding thereto, it is not necessary to act strongly to reduce the state quantity difference.

[Embodiment]
FIG. 1 is a block diagram showing a configuration of a control apparatus according to an embodiment of the present invention. In this embodiment, there are three control loops, an average value of the three control loops is used as the reference state quantity, and each of the three control loops is used as the follow-up state quantity. However, if two or more control loops are used, a similar control system can be configured based on the same principle.

  The control device of FIG. 1 includes a tracking state quantity set value SP1 input unit 1-1, a tracking state quantity measured value PV1 input unit 2-1, and an operation as a configuration of a first control system related to the first tracking state quantity. The amount MV1 output unit 3-1, the PID control calculation unit (PID controller) 4-1, and the coefficient B1 that defines the degree of followability of the follow-up state quantity measurement value PV1 to the reference state quantity measurement value PVm is the first coefficient B1. And a coefficient B1 storage unit 5-1 for storing a second value whose followability is weaker than the first value, and a tracking state amount internal set value SP1 ′ calculation unit 6-1. In addition, the control device of FIG. 1 includes, as the configuration of the second control system related to the second follow-up state quantity, a follow-up state quantity set value SP2 input unit 1-2, a follow-up state quantity measured value PV2 input unit 2-2, As a coefficient B2 that regulates the degree of follow-up of the follow-up state quantity measurement value PV2 to the reference state quantity measurement value PVm, the operation amount MV2 output part 3-2, the PID control calculation part (PID controller) 4-2, A coefficient B2 storage unit 5-2 that stores a first value and a second value whose followability is weaker than the first value and a tracking state amount internal set value SP2 ′ calculation unit 6-2 are provided. . In addition, the control device of FIG. 1 includes, as the configuration of the third control system related to the third follow-up state quantity, a follow-up state quantity set value SP3 input unit 1-3, a follow-up state quantity measured value PV3 input unit 2-3, As a coefficient B3 that defines the degree of follow-up of the follow-up state quantity measurement value PV3 to the reference state quantity measurement value PVm, the operation amount MV3 output section 3-3, the PID control calculation section (PID controller) 4-3, A coefficient B3 storage unit 5-3 that stores a first value and a second value whose followability is weaker than the first value, and a tracking state amount internal set value SP3 ′ calculation unit 6-3 are provided. .

  In addition, the control device of FIG. 1 has a reference state quantity setting value SPm calculation unit 7 that calculates an average value of the following state quantity setting values SP1, SP2, and SP3 as the reference state quantity setting value SPm as a configuration related to the reference state quantity. A reference state quantity measurement value PVm calculation unit 8 that calculates an average value of the following state quantity measurement values PV1, PV2, and PV3 as a reference state quantity measurement value PVm, and a coefficient Am storage unit 9 are provided.

  Further, the control device of FIG. 1 has a configuration related to switching of the coefficient Bi (i is the number of tracking state quantities, i = 1, 2, 3 in the present embodiment), and the tracking state quantity set value SPi and the tracking state quantity. A reference deviation Erm, which is a value representing the deviation for each follow-up state quantity, is calculated from the absolute value of the deviation from the measured value PVi, and exceeds a judgment index Cr set in advance in at least one of the follow-up state quantity set values SPi. When the change occurs, the coefficient B1 storage unit 5-1, the coefficient B2 storage unit 5-2, and the coefficient B3 storage unit 5-3 are instructed to output the first value as the coefficient Bi after this point, and the reference When the deviation Erm becomes smaller than the preset determination index Cs, the coefficient B1 storage unit 5-1, the coefficient B2 storage unit 5-2, and the coefficient are output so that the second value is output as the coefficient Bi after this point. Coefficient to instruct B3 storage unit 5-3 Comprises i switching judgment unit 10. The coefficient Bi switching determination unit 10 includes a reference deviation calculation unit (not shown) that calculates the reference deviation Erm.

  FIG. 2 is a block diagram of the control system in the present embodiment. In FIG. 2, Er1 ′ is a deviation between the internal set value SP1 ′ of the first follow-up state quantity and the measured value PV1 of the first follow-up state quantity, and Er2 ′ is an internal set value SP2 ′ of the second follow-up state quantity. The deviation of the second follow-up state quantity from the measured value PV2, Er3 ′ is the deviation between the third follow-up state quantity internal set value SP3 ′ and the third follow-up state quantity measured value PV3, and Am is the reference state quantity. A coefficient, B1 is a coefficient relating to a state quantity difference between the first following state quantity and the reference state quantity, B2 is a coefficient relating to a state quantity difference between the second following state quantity and the reference state quantity, and B3 is a third following state quantity. Is a coefficient relating to the difference between the state quantity and the reference state quantity, A1 is an actuator for controlling the first following state quantity, A2 is an actuator for controlling the second following state quantity, and A3 is an actuator for controlling the third following state quantity. , P1 is a control pair related to the first follow-up state quantity. Process, P2 is a control target process related to the second follow-up state quantity, P3 is a control target process related to the third follow-up state quantity, Gp1 is a transfer function of a block including the actuator A1 and the process P1, and Gp2 is an actuator A2 A transfer function Gp3 of the block including the process P2 is a transfer function of a block including the actuator A3 and the process P3.

  Tracking state quantity set value SP1 input unit 1-1, tracking state quantity measured value PV1 input unit 2-1, operation amount MV1 output unit 3-1, PID control calculation unit 4-1, and tracking state quantity internal setting The value SP1 ′ calculation unit 6-1, the actuator A1, and the process P1 constitute a first control system (first control loop). Follow-up state quantity set value SP2 input section 1-2, follow-up state quantity measured value PV2 input section 2-2, manipulated variable MV2 output section 3-2, PID control calculation section 4-2, and follow-up state quantity internal setting The value SP2 ′ calculating unit 6-2, the actuator A2, and the process P2 constitute a second control system (second control loop). The follow-up state quantity set value SP3 input unit 1-3, the follow-up state quantity measured value PV3 input unit 2-3, the operation amount MV3 output unit 3-3, the PID control calculation unit 4-3, the follow-up state quantity The internal set value SP3 ′ calculating unit 6-3, the actuator A3, and the process P3 constitute a third control system (third control loop).

  Next, the operation of the control device of the present embodiment will be described with reference to FIG. First, the follow-up state quantity set value SP1 is set by the operator of the control device, and the follow-up state quantity set value SP1 ′ calculating unit 6-1 and the reference state quantity setting are set via the follow-up state quantity set value SP1 input unit 1-1. The values are input to the value SPm calculation unit 7 and the coefficient Bi switching determination unit 10 (step S101 in FIG. 3). The follow-up state quantity set value SP2 is set by the operator, and follows the follow-up state quantity set value SP2 ′ calculating unit 6-2 and the reference state quantity set value SPm calculating unit 7 via the follow-up state quantity set value SP2 input unit 1-2. And the coefficient Bi switching determination unit 10 (step S102). The follow-up state quantity set value SP3 is set by the operator, and follows the follow-up state quantity set value SP3 ′ calculator 6-3 and the reference state quantity set value SPm calculator 7 via the follow-up state quantity set value SP3 input unit 1-3. And the coefficient Bi switching judgment unit 10 (step S103).

  The follow-up state quantity measurement value PV1 is detected by first detection means (not shown), and the PID control calculation unit 4-1 and the follow-up state quantity internal set value SP1 ′ are calculated via the follow-up state quantity measurement value PV1 input unit 2-1. The data is input to the unit 6-1, the reference state measured value PVm calculation unit 8, and the coefficient Bi switching determination unit 10 (step S104). The follow-up state quantity measurement value PV2 is detected by a second detection unit (not shown), and the PID control calculation unit 4-2 and the follow-up state quantity internal set value SP2 ′ are calculated via the follow-up state quantity measurement value PV2 input unit 2-2. The data is input to the unit 6-2, the reference state quantity measurement value PVm calculation unit 8, and the coefficient Bi switching determination unit 10 (step S105). The follow-up state quantity measurement value PV3 is detected by a third detection unit (not shown), and the PID control calculation unit 4-3 and the follow-up state quantity internal set value SP3 ′ are calculated via the follow-up state quantity measurement value PV3 input unit 2-3. The data is input to the unit 6-3, the reference state quantity measurement value PVm calculation unit 8, and the coefficient Bi switching determination unit 10 (step S106).

As shown in the following equation, the coefficient Bi switching determination unit 10 has an absolute value | Er1 | of a deviation between the follow-up state amount set value SP1 and the follow-up state amount measured value PV1, and the follow-up state amount set value SP2 and the follow-up state amount measured value PV2. And the absolute value | Er3 | of the deviation between the follow-up state quantity set value SP3 and the follow-up state quantity measured value PV3, and the absolute values of the deviations | Er1 | and | Er2 | The average value of | Er3 | is calculated as the standard deviation Erm (step S107).
| Er1 | = | SP1-PV1 | (9)
| Er2 | = | SP2-PV2 | (10)
| Er3 | = | SP3-PV3 | (11)
Erm = (| Er1 | + | Er2 | + | Er3 |) / 3 (12)

  Then, the coefficient Bi switching determination unit 10 at the time when the change amount per control cycle is larger than the predetermined determination index Cr in at least one of the follow-up state amount setting values SP1, SP2, SP3. Then, it is determined that the follow-up state quantity measurement value PVi is at a point far from the specific range from the follow-up state quantity set value SPi, and after this time, a predetermined first value is output as the coefficients B1, B2, and B3. The coefficient B1 storage unit 5-1, the coefficient B2 storage unit 5-2, and the coefficient B3 storage unit 5-3 are instructed (step S108). Further, the coefficient Bi switching determination unit 10 detects the tracking state quantity measured value PVi from a tracking state quantity set value SPi to a point within a specific range when the reference deviation Erm becomes smaller than a preset determination index Cs. After this time, the coefficient B1 storage unit 5-1, the coefficient B2 storage unit 5-2, and the coefficient B3 storage unit 5- are output so as to output predetermined second values as the coefficients B1, B2, and B3. 3 is instructed (step S108).

Next, the reference state quantity set value SPm calculation unit 7 calculates an average value of the tracking state quantity set value SP1, the tracking state quantity set value SP2, and the tracking state quantity set value SP3 as a reference state quantity set value as shown in the following equation. SPm is calculated, and this reference state quantity set value SPm is calculated as a follow-up state quantity internal set value SP1 ′ calculation section 6-1, a follow-up state quantity internal set value SP2 ′ calculation section 6-2, and a follow-up state quantity internal set value SP3 ′. To the unit 6-3 (step S109).
SPm = (SP1 + SP2 + SP3) / 3 (13)

The reference state quantity measurement value PVm calculation unit 8 calculates an average value of the tracking state quantity measurement value PV1, the tracking state quantity measurement value PV2, and the tracking state quantity measurement value PV3 as the reference state quantity measurement value PVm as in the following equation. Then, the reference state quantity measurement value PVm is used as the tracking state quantity internal set value SP1 ′ calculation section 6-1, the tracking state quantity internal setting value SP2 ′ calculation section 6-2, and the tracking state quantity internal setting value SP3 ′ calculation section 6-6. 3 (step S110).
PVm = (PV1 + PV2 + PV3) / 3 (14)

The coefficient Am storage unit 9 stores a coefficient Am related to the reference state quantity in advance. The coefficient B1 storage unit 5-1 stores the first value and the second value as the coefficient B1 related to the state quantity difference between the first following state quantity and the reference state quantity. Of the two values, the value instructed by the coefficient Bi switching determination unit 10 is output to the tracking state amount internal set value SP1 ′ calculation unit 6-1. The tracking state quantity internal set value SP1 ′ calculation unit 6-1 is based on the coefficients Am, B1, the reference state quantity setting value SPm, the reference state quantity measurement value PVm, the tracking state quantity setting value SP1, and the tracking state quantity measurement value PV1. Then, the tracking state quantity internal set value SP1 ′ is calculated as shown in the following equation (step S111).
SP1 ′ = AmSPm + (1-Am) PVm + B1 (SP1-SPm)
+ (1-B1) (PV1-PVm) (15)

The coefficient B2 storage unit 5-2 stores the first value and the second value as the coefficient B2 related to the state quantity difference between the second follow-up state quantity and the reference state quantity. Of the two values, the value instructed by the coefficient Bi switching determination unit 10 is output to the tracking state amount internal set value SP2 ′ calculation unit 6-2. The tracking state quantity internal set value SP2 ′ calculation unit 6-2 is based on the coefficients Am, B2, the reference state quantity setting value SPm, the reference state quantity measurement value PVm, the tracking state quantity setting value SP2, and the tracking state quantity measurement value PV2. Then, the tracking state quantity internal set value SP2 ′ is calculated as shown in the following equation (step S112).
SP2 ′ = AmSPm + (1-Am) PVm + B2 (SP2-SPm)
+ (1-B2) (PV2-PVm) (16)

The coefficient B3 storage unit 5-3 stores the first value and the second value as the coefficient B3 related to the state quantity difference between the third follow-up state quantity and the reference state quantity. Of the two values, the value instructed by the coefficient Bi switching determination unit 10 is output to the tracking state amount internal set value SP3 ′ calculation unit 6-3. The tracking state quantity internal set value SP3 ′ calculating section 6-3 is based on the coefficients Am, B3, the reference state quantity setting value SPm, the reference state quantity measurement value PVm, the tracking state quantity setting value SP3, and the tracking state quantity measurement value PV3. Then, the follow-up state quantity internal set value SP3 ′ is calculated as follows (step S113).
SP3 ′ = AmSPm + (1-Am) PVm + B3 (SP3-SPm)
+ (1-B3) (PV3-PVm) (17)

Next, the PID control calculation unit 4-1 performs the PID control calculation as in the following transfer function equation to calculate the manipulated variable MV1 (step S114).
MV1 = (100 / Pb1) {1+ (1 / Ti1s) + Td1s} (SP1 ′
-PV1) (18)
In Expression (18), Pb1 is a proportional band, Ti1 is an integration time, Td1 is a differentiation time, and s is a Laplace operator. When the calculated operation amount MV1 is smaller than the lower limit value OL1 of the output of the actuator A1, the PID control calculation unit 4-1 sets the operation amount MV1 = OL1 and the calculated operation amount MV1 is the upper limit value OH1 of the output of the actuator A1. If larger, an operation amount upper / lower limit process for setting the operation amount MV1 = OH1 is performed as a measure for integral windup.

  Integral windup is a value where the set value SP is small because the controller ignores the upper limit value of the actuator output and calculates an operation amount MV that is larger than necessary when the state quantity measured value PV is lower than the set value SP. This is a phenomenon in which the drop in the operation amount MV is delayed when it is changed to, and this is because the controller does not calculate the operation amount in consideration of the physical upper and lower limits of the actuator.

The PID control calculation unit 4-2 calculates a manipulated variable MV2 by performing a PID control calculation such as the following transfer function equation (step S115).
MV2 = (100 / Pb2) {1+ (1 / Ti2s) + Td2s} (SP2 ′
-PV2) (19)
In Expression (19), Pb2 is a proportional band, Ti2 is an integration time, and Td2 is a differentiation time. When the calculated operation amount MV2 is smaller than the lower limit value OL2 of the output of the actuator A2, the PID control calculation unit 4-2 sets the operation amount MV2 = OL2, and the calculated operation amount MV2 is the upper limit value OH2 of the output of the actuator A2. If larger, an operation amount upper / lower limit process for setting the operation amount MV2 = OH2 is performed as a measure for integral windup.

The PID control calculation unit 4-3 calculates a manipulated variable MV3 by performing a PID control calculation such as the following transfer function equation (step S116).
MV3 = (100 / Pb3) {1+ (1 / Ti3s) + Td3s} (SP3 ′
-PV3) (20)
In Expression (20), Pb3 is a proportional band, Ti3 is an integration time, and Td3 is a differentiation time. When the calculated operation amount MV3 is smaller than the lower limit value OL3 of the output of the actuator A3, the PID control calculation unit 4-3 sets the operation amount MV3 = OL3, and the calculated operation amount MV3 is the upper limit value OH3 of the output of the actuator A3. If larger, an operation amount upper / lower limit process for setting the operation amount MV3 = OH3 is performed as a measure for integral windup.

The operation amount MV1 output unit 3-1 outputs the operation amount MV1 calculated by the PID control operation unit 4-1 to the actuator A1 (step S117). The actuator A1 operates to control the first follow-up state amount based on the operation amount MV1.
The operation amount MV2 output unit 3-2 outputs the operation amount MV2 calculated by the PID control calculation unit 4-2 to the actuator A2 (step S118). The actuator A2 operates to control the second follow-up state quantity based on the operation quantity MV2.
The operation amount MV3 output unit 3-3 outputs the operation amount MV3 calculated by the PID control calculation unit 4-3 to the actuator A3 (step S119). The actuator A3 operates to control the third follow-up state quantity based on the operation quantity MV3.

  The processes in steps S101 to S119 as described above are repeatedly executed for each control cycle until the end of control is instructed by the operator (YES in step S120), for example.

  FIG. 4 shows a simulation result of the operation of the control device of the present embodiment. FIG. 4A is a diagram showing a step response of the control system when the follow-up state quantity setting values SP1, SP2, and SP3 are changed from 0 to 40, and FIG. 4B is an enlarged view of FIG. 4A. FIG. The simulation conditions are as follows.

First, the transfer function Gp1 of the block including the actuator A1 and the process P1, the transfer function Gp2 of the block including the actuator A2 and the process P2, and the transfer function Gp3 of the block including the actuator A3 and the process P3 are set as follows: To do. Here, it is assumed that there is no interference between control loops.
Gp1 = 3.6exp (−2.0 s) / {(1 + 70.0 s) (1 + 10.0 s)}
... (21)
Gp2 = 4.8exp (−2.0s) / {(1 + 60.0s) (1 + 10.0s)}
(22)
Gp3 = 6.0exp (−2.0 s) / {(1 + 50.0 s) (1 + 10.0 s)}
(23)

The operation amount lower limit value OL1 of the PID control calculation unit 4-1 is 0%, the upper limit value OH1 is 100%, the operation amount lower limit value OL2 of the PID control calculation unit 4-2 is 0%, and the upper limit value OH2 is 100%. The operation amount lower limit value OL3 of the PID control calculation unit 4-3 is set to 0%, and the upper limit value OH3 is set to 100%.
The follow-up state quantity measurement values PV1, PV2, and PV3 are determined as follows according to the operation amounts MV1, MV2, and MV3.
PV1 = Gp1MV1 (24)
PV2 = Gp2MV2 (25)
PV3 = Gp3MV3 (26)

  The proportional band Pb1, which is the PID parameter of the PID control calculation unit 4-1, is 150.0, the integration time Ti1 is 35.0, the differential time Td1 is 20.0, and the proportionality is the PID parameter of the PID control calculation unit 4-2. The band Pb2 is 200.0, the integration time Ti2 is 35.0, the differential time Td2 is 20.0, the proportional band Pb3 that is the PID parameter of the PID control calculation unit 4-3 is 300.0, and the integration time Ti3 is 35. 0, the differential time Td3 is 20.0. 7 to 9 are also simulated under the above conditions.

  In the simulation results shown in FIGS. 4A and 4B, Am = 1.0 is set in this embodiment, and the first value of the coefficient Bi is set as B1 = B2 = B3 = 6.7. This is obtained by setting the second value of the coefficient Bi as B1 = B2 = B3 = 3.0 and setting the determination index as Cr = Cs = 4.0. In the examples of FIGS. 4A and 4B, the first value is switched to the second value at around PVi = 36 (Erm = 4.0). As can be seen from FIGS. 4 (a) and 4 (b), the state quantity difference is small until PVi = 37, as in FIGS. 9 (a) and 9 (b), and it has passed near PVi = 37. Thereafter, the vertical movement of PVi decreases, and the large disturbance of the state quantity difference as shown in FIGS. 9A and 9B is reduced. Therefore, in this Embodiment, it turns out that the controllability of the state quantity difference in a transient state and the stability of the control in a settling state are compatible.

  Note that the control device described in this embodiment can be realized by a computer including an arithmetic device, a storage device, and an interface, and a program that controls these hardware resources.

  Further, in the present embodiment, based on the configuration disclosed in Patent Document 3, the tracking state amount setting value SPi among the plurality of control calculation input values input to the PID control calculation unit is a tracking value that is an internal input value. Although it is converted to the state quantity internal set value SPi ′ and then input to the PID control calculation unit, the principle of the present invention can be applied even when other control calculation input values are converted to internal input values. The same effect as this embodiment can be obtained. Other control calculation input values include the follow-up state quantity measurement value PVi used in Patent Document 4 and the follow-up state quantity deviation Eri used in Patent Document 5.

In order to convert the i-th follow-up state quantity measurement value PVi into the follow-up state quantity internal measurement value PVi ′, which is an internal input value, conversion may be performed according to the following equation.
PVi ′ = (1−Am) SPm + AmPVm + (1−Bi) (SPi−SPm)
+ Bi (PVi-PVm) (27)
Then, the tracking state quantity internal measurement value PVi ′ may be input to the i-th PID control calculation unit, and the tracking state quantity set value SPi may be input as it is without being converted. At this time, the PID control calculation unit calculates the operation amount MVi by the following equation.
MVi = (100 / Pbi) {1+ (1 / Tiis) + Tdis} (SPi
−PVi ′) (28)
In Equation (28), Pbi is a proportional band, Tii is an integration time, and Tdi is a differentiation time.

On the other hand, in order to convert the i-th tracking state quantity deviation Eri into the tracking state quantity internal deviation Eri ′, which is an internal input value, the conversion may be performed by the following equation.
Eri '= Am (SPm-PVm)
+ Bi {(SPi-SPm)-(PVi-PVm)} (29)
Then, the follow-up state quantity internal deviation Eri ′ may be input to the i-th PID control calculation unit. At this time, the PID control calculation unit calculates the operation amount MVi by the following equation.
MVi = (100 / Pbi) {1+ (1 / Tiis) + Tdis} Eri ′
... (30)

  The present invention can be applied to a process control technique.

It is a block diagram which shows the structure of the control apparatus used as embodiment of this invention. It is a block diagram of the control system in the embodiment of the present invention. It is a flowchart which shows operation | movement of the control apparatus of FIG. It is a figure which shows the simulation result of the step response by the control apparatus of FIG. It is a block diagram which shows the structure of the conventional control apparatus. It is a block diagram which shows the structure of the other conventional control apparatus. It is a figure which shows the simulation result of the step response by the conventional PID control. It is a figure which shows the simulation result of the step response by the control method of a prior application. It is a figure which shows the simulation result of the step response by the control method of a prior application.

Explanation of symbols

  4-1, 4-2, 4-3 ... PID control operation unit, 5-1 ... coefficient B1 storage unit, 5-2 ... coefficient B2 storage unit, 5-2 ... coefficient B3 storage unit, 6-1 ... following state Quantity internal set value SP1 ′ calculating section, 6-2... Tracking state quantity internal setting value SP2 ′ calculating section, 6-3... Tracking state quantity internal setting value SP3 ′ calculating section, 7. 8: Reference state quantity measurement value PVm calculation unit, 9 ... Coefficient Am storage unit, 10 ... Coefficient Bi switching judgment unit.

Claims (5)

In a control method of a control system having at least two parallel PID control loops,
When a state quantity that is a specific reference is a reference state quantity, and a state quantity that is controlled so as to maintain a predetermined value relative to the reference state quantity is a tracking state quantity,
Calculation procedure for converting the follow-up state quantity set value SPi out of a plurality of control calculation input values inputted to the PID controller for controlling the follow-up state quantity into the follow-up state quantity internal set value SPi ′ and then inputting it into the PID controller With
In the calculation procedure , a preset reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi are measured as the input values for control calculation. When the follow-up state quantity measurement value PVi is input, a first coefficient Bi that defines the degree of follow-up of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm, and the reference state quantity measurement The tracking state quantity internal set value SPi ′ is set to SPi ′ = AmSPm + (1−Am) PVm + Bi () using the second coefficient Am that defines the degree of responsiveness of the value PVm to the reference state quantity set value SPm. SPi−SPm) + (1−Bi) (PVi−PVm) to calculate the reference state quantity measurement value PVm to the reference state quantity set value SPm, the following state quantity measurement value PVi, and the reference state quantity Total Controls to separate the conformability to a difference which is a difference value PVm relative amounts PVi-PVm of follow-up state quantity set point SPi and the reference state quantity set value SPm relative amounts SPi-SPm,
And a switching determination procedure for switching the first coefficient Bi based on a deviation between the follow-up state quantity set value SPi and the follow-up state quantity measured value PVi.
The switching determination procedure selects a predetermined first value as the first coefficient Bi when the follow-up state quantity measurement value PVi is at a point far from a specific range from the follow-up state quantity set value SPi. When the follow-up state quantity measurement value PVi is near a point within the specific range from the follow-up state quantity set value SPi, a predetermined second value whose degree of follow-up is weaker than the first value. Is selected as the first coefficient Bi . In a control method of a control system having at least two parallel PID control loops,
When a state quantity that is a specific reference is a reference state quantity, and a state quantity that is controlled so as to maintain a predetermined value relative to the reference state quantity is a tracking state quantity,
Calculation procedure for converting the follow-up state quantity measured value PVi out of a plurality of control calculation input values inputted to the PID controller for controlling the follow-up state quantity into the follow-up state quantity internal measurement value PVi ′ and then inputting it into the PID controller With
In the calculation procedure, a predetermined reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi are measured as the control calculation input values. When the follow-up state quantity measurement value PVi is input, a first coefficient Bi that defines the degree of follow-up of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm, and the reference state quantity measurement Using the second coefficient Am that defines the degree of responsiveness of the value PVm to the reference state quantity setting value SPm, the following state quantity internal measurement value PVi ′ is expressed as PVi ′ = (1−Am) SPm + AmPVm + (1 -Bi) By calculating by (SPi-SPm) + Bi (PVi-PVm), the followability of the reference state quantity measurement value PVm to the reference state quantity set value SPm, the follow-up state quantity measurement value PVi, and the reference state quantity meter Controls to separate the conformability to a difference which is a difference value PVm relative amounts PVi-PVm of follow-up state quantity set point SPi and the reference state quantity set value SPm relative amounts SPi-SPm,
And a switching determination procedure for switching the first coefficient Bi based on a deviation between the follow-up state quantity set value SPi and the follow-up state quantity measured value PVi.
The switching determination procedure selects a predetermined first value as the first coefficient Bi when the follow-up state quantity measurement value PVi is at a point far from a specific range from the follow-up state quantity set value SPi. When the follow-up state quantity measurement value PVi is near a point within the specific range from the follow-up state quantity set value SPi, a predetermined second value whose degree of follow-up is weaker than the first value. Is selected as the first coefficient Bi . In a control method of a control system having at least two parallel PID control loops,
When a state quantity that is a specific reference is a reference state quantity, and a state quantity that is controlled so as to maintain a predetermined value relative to the reference state quantity is a tracking state quantity,
A follow-up state quantity deviation Eri calculated based on a plurality of control calculation input values inputted to the PID controller that controls the follow-up state quantity is converted into a follow-up state quantity internal deviation Eri 'and then inputted to the controller. With a calculation procedure,
In the calculation procedure, a preset reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi are measured as the input values for control calculation. When the follow-up state quantity measurement value PVi is input, a first coefficient Bi that defines the degree of follow-up of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm, and the reference state quantity measurement Using the second coefficient Am that defines the degree of responsiveness of the value PVm to the reference state quantity set value SPm, the following state quantity internal deviation Eri ′ is set to Eri ′ = Am (SPm−PVm) + Bi {( SPi-SPm)-(PVi-PVm)}, the followability of the reference state quantity measurement value PVm to the reference state quantity set value SPm, and the follow-up state quantity measurement value PVi and the reference state quantity measurement value PVm With the difference The relative amounts PVi-PVm of follow-up state quantity set point SPi and the reference state quantity set value which is the difference between SPm separates the conformability to the relative amounts SPi-SPm controls that,
And a switching determination procedure for switching the first coefficient Bi based on a deviation between the follow-up state quantity set value SPi and the follow-up state quantity measured value PVi.
The switching determination procedure selects a predetermined first value as the first coefficient Bi when the follow-up state quantity measurement value PVi is at a point far from a specific range from the follow-up state quantity set value SPi. When the follow-up state quantity measurement value PVi is near a point within the specific range from the follow-up state quantity set value SPi, a predetermined second value whose degree of follow-up is weaker than the first value. Is selected as the first coefficient Bi . The control method according to any one of claims 1 to 3 ,
In the switching determination procedure, when the follow-up state amount setting value SPi changes beyond a predetermined determination index Cr, a predetermined first value is selected as the first coefficient Bi after this point. When the deviation between the follow-up state quantity set value SPi and the follow-up state quantity measured value PVi becomes smaller than a predetermined determination index Cs, the first coefficient Bi is determined as the first coefficient Bi. A control method characterized by selecting the second value . In a control system device having at least two parallel PID control loops,
When a state quantity that is a specific reference is a reference state quantity, and a state quantity that is controlled so as to maintain a predetermined value relative to the reference state quantity is a tracking state quantity,
A PID controller that calculates an operation amount for controlling the follow-up state amount and outputs the calculated operation amount to a control target of a corresponding PID control loop;
An internal input value calculation unit that converts the tracking state quantity set value SPi out of a plurality of control calculation input values input to the PID controller into a tracking state quantity internal setting value SPi ′ and inputs the converted value to the PID controller. ,
The internal input value calculation unit includes a preset reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi as the control calculation input values. When the measured follow-up state quantity measurement value PVi is input, the first coefficient Bi that defines the degree of follow-up of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm, and the reference The tracking state quantity internal setting value SPi ′ is set to SPi ′ = AmSPm + (1−Am) using the second coefficient Am that defines the degree of responsiveness of the state quantity measurement value PVm to the reference state quantity setting value SPm. ) By calculating PVm + Bi (SPi−SPm) + (1−Bi) (PVi−PVm), the followability of the reference state quantity measurement value PVm to the reference state quantity set value SPm and the following state quantity measurement value PVi Base Controls to separate the conformability to a difference between the state quantity measurement value which is a difference PVm relative amounts PVi-PVm of follow-up state quantity set point SPi and the reference state quantity set value SPm relative amounts SPi-SPm,
Further, a coefficient switching determination unit that switches the first coefficient Bi based on a deviation between the follow-up state quantity setting value SPi and the follow-up state quantity measured value PVi,
The coefficient switching determination unit selects a predetermined first value as the first coefficient Bi when the follow-up state quantity measurement value PVi is at a point far from a specific range from the follow-up state quantity set value SPi. When the follow-up state quantity measurement value PVi is near a point within the specific range from the follow-up state quantity set value SPi, a predetermined second value whose degree of follow-up is weaker than the first value. A control device that selects a value as the first coefficient Bi.

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