JP4361883B2 - Control device - Google Patents

Description

  The present invention relates to a process control technique, and more particularly to a control device that controls a state quantity difference measured in a control system having at least two control loops.

  FIG. 8A 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. 8A, 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 treatment workpiece 1016 fall within the specified temperature tolerance. The
Focusing on the portion surrounded by the broken line in FIG. 8A, the state quantity for calculating the temperature difference (TC2−TC3) and the temperature change rate dTC3 / dt based on the plurality of measured temperatures TC1, TC2, and TC3. You can see that the conversion is taking place. That is, the temperature controller of FIG. 8A includes the state quantity conversion unit 1041 that calculates the temperature difference (TC2−TC3) and the temperature change rate dTC3 / dt (FIG. 8B).

  FIG. 9 (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. 9A, the detection value of the temperature sensor A converges to the target value.

When attention is paid to the portion surrounded by the broken line in FIG. 9A, 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. 9A includes the state quantity conversion unit 2008 that calculates the temperature difference (A−B) (FIG. 9B).
As described above, efforts have been made in the past to incorporate not only the actual state quantity itself but also the state quantity difference into the control system. The state quantity conversion unit is provided.

  Here, let us consider that in the two control loops, the state quantity average value PV1 'and the state quantity difference PV2' are controlled, not the state quantities PV1 and PV2 themselves. The control device in this case is shown in FIG. 10 includes a subtractor 3001 that outputs a difference between the set value SP1 ′ and the state quantity average value PV1 ′ for the state quantity average value PV1 ′, and a set value SP2 ′ and the state quantity difference for the state quantity difference PV2 ′. Subtractor 3002 that outputs the difference from PV2 ′, controllers C1 and C2 that calculate operation amounts MV1 and MV2 based on the outputs of subtractors 3001 and 3002, and operation amounts for control target processes P1 and P2, respectively. Actuators A1 and A2 that perform operations according to MV1 and MV2 and a state quantity conversion unit 3003 are included.

The state quantity conversion unit 3003 multiplies multipliers 3004 and 3005 for multiplying the state quantities PV1 and PV2 of the control target processes P1 and P2 by 0.5 and −1 and 1 respectively for the state quantities PV1 and PV2. Multipliers 3006 and 3007 for multiplication, an adder 3008 for adding the outputs of the multipliers 3004 and 3005, and an adder 3009 for adding the outputs of the multipliers 3006 and 3007. By such a state quantity conversion unit 3003, the state quantity average value PV1 ′ and the state quantity difference PV2 ′ are expressed by the following equations.
PV1 ′ = 0.5PV1 + 0.5PV2 (1)
PV2 ′ = PV2-PV1 (2)
Further, the input / output relationship of the state quantity conversion unit 3003 is expressed as a matrix as follows.

  The controller C1 targets the state quantity average value PV1 ', and the controller C2 targets the state quantity difference PV2'. The controller C1 calculates the manipulated variable MV1 based on the deviation between the set value SP1 ′ and the state quantity average value PV1 ′, and the controller C2 calculates the manipulated variable MV2 based on the deviation between the set value SP2 ′ and the state quantity difference PV2 ′. calculate. At this time, since the state quantity average value PV1 ′ and the state quantity difference PV2 ′ are in a controllable state, the operation amount MV1 calculated by the controller C1 is sent to the actuator A1, and the operation calculated by the controller C2 is performed. The quantity MV2 is configured to be sent to the actuator A2. As a result, the actuator A1 operates to control the state quantity average value PV1 ', and the actuator A2 operates to control the state quantity difference PV2'. In this way, the controller C1 that directly controls the state quantity average value PV1 ′ and the state quantity difference PV2 simply by applying the state quantity conversion unit 3003 similar to that shown in FIGS. 8B and 9B. A multi-loop control system including a controller C2 that directly controls' can be configured, and the state quantity average value PV1 'and the state quantity difference PV2' can be controlled to desired values.

  However, when the state quantity PV1 is changed by the operation of the actuator A1, this change also affects the state quantity difference PV2 'by the action of the state quantity conversion unit 3003. Similarly, when the state quantity PV2 is changed by the operation of the actuator A2, this change also affects the state quantity average value PV1 'by the action of the state quantity conversion unit 3003. In other words, the control device shown in FIG. 10 has a configuration in which inter-loop interference is artificially generated by the state quantity conversion unit 3003.

  Since the coefficients multiplied by the state quantities PV1 and PV2 to calculate the state quantity average value PV1 ′ are both 0.5, the process gain Kp1 of the control target process P1 and the process gain Kp2 of the control target process P2 are approximately the same. Assuming that, the degree of influence on the state quantity average value PV1 ′ due to operation of the actuator A1 and the degree of influence on the state quantity average value PV1 ′ due to inter-loop interference when the actuator A2 operates (state due to the actuator A2) The degree of influence that disturbs the quantity average value PV1 ′) is about the same. Similarly, since the absolute values of the coefficients multiplied by the state quantities PV1 and PV2 in order to calculate the state quantity difference PV2 ′ are both 1, the degree of influence on the state quantity difference PV2 ′ due to the operation of the actuator A2; The degree of influence on the state quantity difference PV2 ′ due to interference between loops when the actuator A1 operates (the degree of influence that the state quantity difference PV2 ′ is disturbed by the actuator A1) is about the same. Therefore, simply applying the state quantity conversion unit inherently tends to increase the artificial inter-loop interference, which causes a problem that the controllability tends to deteriorate.

  Therefore, in order to realize non-interference between loops, it is easily conceivable to apply the cross controller disclosed in Non-Patent Document 1. The configuration of the control device disclosed in Non-Patent Document 1 is shown in FIG. 11 includes a subtractor 4001 that outputs a difference between the set value SP1 and the state quantity PV1, a subtractor 4002 that outputs a difference between the set value SP2 and the state quantity PV2, and outputs of the subtractors 4001 and 4002. Controller 4003 and 4004 for calculating the operation amounts MV1 and MV2, respectively, and a cross controller 4005 for outputting the operation amounts MV1 ′ and MV2 ′ obtained by converting the operation amounts MV1 and MV2, respectively.

The cross controller 4005 performs processing for previously canceling the influence due to the interference between the loops on the operation amounts MV1 and MV2, a multiplier 4007 that multiplies the operation amount MV1 by a coefficient M12, and a coefficient M21 on the operation amount MV2. Multiplier 4008 for multiplication, subtractor 4009 for outputting the difference between operation amount MV1 and the output of multiplier 4008 as operation amount MV1 ′, and the difference between operation amount MV2 and the output of multiplier 4007 as operation amount MV2 ′. And a subtractor 4010 for outputting. Here, for simplicity of explanation, dynamic characteristics such as process time constant and process dead time are ignored. Assuming that the process gains of the control target process 4006 for the manipulated variables MV1 ′ and MV2 ′ are Kp1 and Kp2, respectively, according to Non-Patent Document 1, the cross controller 4005 for non-interference can be designed as follows.
MV1 ′ = MV1 + (− 0.5Kp2 / 0.5Kp1) MV2 (4)
MV2 ′ = (Kp1 / Kp2) MV1 + MV2 (5)
Further, the input / output relationship of the cross controller 4005 is expressed in a matrix as follows.

  That is, the coefficient M12 is −Kp1 / Kp2, and the coefficient M21 is 0.5Kp2 / 0.5Kp1. The operation amount MV1 calculated by the controller 4003 is converted into the operation amount MV1 ′ by the cross controller 4005 and then sent to the control target process 4006 via an actuator (not shown). The operation amount MV2 calculated by the controller 4004 is After being converted into the operation amount MV2 ′ by the controller 4005, it is sent to the control target process 4006 via the actuator.

  FIG. 12 shows a configuration in which the cross controller 4005 shown in FIG. 11 is applied to the control device of FIG. By using the state quantity conversion unit 3003 and the cross controller 4005, only the first control loop centering on the controller C1 that exclusively controls the state quantity average value PV1 ′ and only the state quantity difference PV2 ′ are exclusively used. A multi-loop control system having a second control loop centered on the controller C2 to be controlled can be realized. The response characteristic of the controller C1 that exclusively controls the state quantity average value PV1 ′ is adjusted in the direction of emphasizing stability (low sensitivity), and the response characteristic of the controller C2 that exclusively controls the state quantity difference PV2 ′ is obtained. If adjustment is made in a direction that emphasizes responsiveness (high sensitivity), the state quantity difference PV2 ′ follows the set value SP2 ′ before the state quantity average value PV1 ′ follows the set value SP1 ′. Thus, it is possible to perform control such that the state quantity average value PV1 ′ is changed to a desired value while maintaining the state quantity difference PV2 ′ at a desired value.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP-A-8-095647 JP-A-9-199491 Kazuo Hiroi, “Basics and Applications of Digital Instrumentation Control System”, Industrial Technology Co., Ltd., October 1987, p. 152-156, ISBN4-905957-00-1

[First issue]
An actual actuator has upper and lower limits of output, and the controller must calculate an operation amount in consideration of the upper and lower limits. That is, in a state where the output of the actuator reaches the upper limit value or the lower limit value and the change in the state quantity is limited, the controller must not raise or lower the operation amount calculation result more than necessary. If a controller such as PID does not consider the physical upper and lower limits of the actuator, there is a problem of integral windup.

  Hereinafter, this integral windup will be specifically described. For example, when the state quantity is temperature and the actuator is a heater, the heater output is generally limited to a lower limit value of 0% and an upper limit value of 100%. When the operation amount MV calculated by the controller increases and reaches 100%, the heater output also reaches 100%. At this time, when the temperature measurement value PV is lower than the temperature set value SP, if the controller ignores the upper limit value 100% of the heater output, the controller calculates an operation amount MV larger than 100%. Become. However, since the heater output saturates at 100%, the increase in the temperature measurement value PV corresponding to the increase in the heater output reaches the limit, and as a result, the controller increases the manipulated variable MV to a larger value. .

  Then, it is assumed that the temperature set value SP is changed to a value lower than the temperature measurement value PV when the calculated value of the manipulated variable MV continues to increase and reaches, for example, 500%. By changing the temperature setting value SP, the controller lowers the operation amount MV from 500%, so that the operation amount MV lower than the upper limit value 100% of the heater output is output from the controller. It takes a long time. Therefore, although the temperature set value SP is changed to a value lower than the temperature measurement value PV, the controller outputs an operation amount of 100% for a long time, and as a result, the start of the temperature drop is greatly delayed. . As described above, the calculation result of the operation amount MV becomes higher than necessary, and the phenomenon that the decrease in the operation amount MV is delayed when the set value SP is changed to a small value is a phenomenon called integral windup. This is because the operation amount is not calculated in consideration of the physical upper and lower limits.

  In the control device shown in FIG. 12, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are converted into operation amounts MV1 'and MV2' by the cross controller 4005. In other words, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are calculated as composite operation amounts for the plurality of actuators A1 and A2, and the operation amounts MV1 and MV2 of the controllers C1 and C2 and the actuators A1 and A2 are calculated. There is no one-to-one correspondence with the output of A2. Therefore, even if the controllers C1 and C2 calculate the operation amounts MV1 and MV2 in consideration of the upper and lower limits of the outputs of the actuators A1 and A2, the operation amounts MV1 and MV2 are actually output to the actuators A1 and A2. Since the combined operation amounts MV1 ′ and MV2 ′ are generated, there is a possibility that an operation amount output that does not consider the upper and lower limits of the outputs of the actuators A1 and A2 is performed on the actuators A1 and A2. For this reason, the control device shown in FIG. 12 has a problem that the integral windup similar to that of the PID controller described above occurs.

[Second problem]
Moreover, in a normal controller, parameters must be adjusted according to the characteristics of the control target. An example of parameter adjustment is PID parameter adjustment in a PID controller. Conventionally, adjustment methods and automatic adjustment functions for realizing such parameter adjustment have been devised, but this adjustment method and automatic adjustment function basically consists of a controller, an actuator, a controlled object, and a measuring means physically. It is a necessary condition to support.

  Hereinafter, the conventional parameter adjustment will be specifically described. For example, consider a case where the state quantity is temperature, the actuator is a heater, the controlled object is a furnace, and the measuring means is a temperature sensor such as a thermocouple. At this time, as shown in FIG. 13, assuming two control loops, controllers 5003 and 5004, heaters 5005 and 5006 as actuators, furnaces 5007 and 5008 as control objects, and temperature sensors as measurement means 5009, 5010. In FIG. 13, reference numeral 5001 denotes a subtractor that outputs the difference between the temperature set value SP1 and the temperature measurement value PV1, and 5002 denotes a subtractor that outputs the difference between the temperature set value SP2 and the temperature measurement value PV2.

  In the configuration of FIG. 13, although some inter-loop interference is allowed, the controller 5003 outputs the operation amount MV1 to the heater 5005, the heater 5005 mainly heats the furnace 5007, and the temperature sensor 5009 is a temperature near the furnace 5007. And the controller 5003 must execute a control calculation so as to control the temperature measurement value PV1. Similarly, the controller 5004 outputs the operation amount MV2 to the heater 5006, the heater 5006 mainly heats the furnace 5008, the temperature sensor 5010 measures the temperature near the furnace 5008, and the controller 5004 controls the temperature measurement value PV2. The control operation must be executed as follows. In this way, the controller 5003, 5004, the heaters 5005, 5006, the furnace 5007, 5008, and the temperature sensors 5009, 5010 are physically compatible with each other, so that an adjustment method or an automatic adjustment function that has been devised in the past is applied. It becomes a necessary condition to do. In other words, the controller 5003 calculates the operation amounts MV1 and MV2 distributed at the same level between the heaters 5005 and 5006 as one combined operation amount, and the controller 5004 is also equivalent to the heaters 5005 and 5006. If the operation amounts MV1 and MV2 distributed at the level of 1 are calculated as one composite operation amount, it becomes impossible to apply a conventionally devised adjustment method or automatic adjustment function.

  In the control device shown in FIG. 12, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are converted into operation amounts MV1 'and MV2' by the cross controller 4005. In other words, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are calculated as composite operation amounts for the plurality of actuators A1 and A2, and the operation amounts MV1 and MV2 of the controllers C1 and C2 and the actuators A1 and A2 are calculated. There is no one-to-one correspondence with the output of A2. That is, the basic condition that the controller, the actuator, the controlled object, and the measuring means physically correspond to each other is not satisfied. Therefore, in the control device shown in FIG. 12, it is impossible to apply a conventionally devised adjustment method or automatic adjustment function, and controller parameter adjustment such as PID parameter adjustment becomes very difficult. was there.

  The present invention has been made to solve the above-described problem, and maintains an absolute amount such as an average value of a plurality of state quantities to a desired value while maintaining a relative state quantity between the plurality of state quantities at a desired value. It is an object of the present invention to provide a control device that can prevent integral windup in a control system that performs control to be changed, and that can be applied with a conventionally devised parameter adjustment method or automatic adjustment function.

The present invention is a control system control device having n (n is a natural number equal to or greater than 2) parallel PID control loops, which is a state quantity difference with an absolute state quantity serving as a specific reference as a reference state quantity. When the relative state quantity is defined as a relative state quantity, each of the n state quantity measurement values input to the n PID control loops is represented by one reference state quantity measurement value and (n−1) pieces. A state quantity conversion unit that linearly combines with an n × n state quantity conversion matrix for conversion into a relative state quantity measurement value and converts the reference state quantity measurement value and the relative state quantity measurement value ; Either the control deviation between the measured reference state quantity and the corresponding reference state quantity set value or the control deviation between the converted relative state quantity measured value and the corresponding relative state quantity set value is converted. A control deviation calculation unit for calculating each state quantity measurement value, and the calculated A weighting factor setting unit that multiplies each of the n control deviations by a weighting factor that gives priority to control, n operation amounts calculated by the PID control calculation unit, and each of the n PID control loops. In order to correspond one-to-one with the output of the actuator, an inverse matrix reconversion unit that retransforms n control deviations multiplied by the weighting factor by an inverse matrix of the state quantity transformation matrix; A PID control calculation unit that calculates an operation amount of each PID control loop based on the n control deviations, and outputs the calculated n operation amounts to an actuator of the corresponding PID control loop; and the control deviation calculation unit by providing the state quantity filtering setting value calculation unit for performing the suppressing filtering sudden variation with respect to the reference state quantity setting value inputted and relative state quantity setting value, the reference state The relative state quantity and calculates the control deviation to control giving priority.
Further, the present invention provides a control system control apparatus having n (n is a natural number of 2 or more) parallel PID control loops, wherein an absolute state quantity serving as a specific reference is set as a reference state quantity, and a state quantity difference When the relative state quantity is a relative state quantity, the control deviation between each state quantity measurement value input to the n PID control loops and the corresponding state quantity set value is the state quantity measurement. a control deviation calculation unit that calculates for each value, the n control deviation the calculated, corresponding to the relative state quantities and one control deviation corresponding to the reference state quantity (n-1) pieces of control a control deviation conversion unit by the state quantity conversion matrix of n × n for converting the deviation by linear combination into a control deviation corresponding to the relative state quantity control deviation corresponding to the reference state amount, wherein Each of the converted n control deviations corresponds to the control In order to make a one-to-one correspondence between a weighting factor setting unit that multiplies a weighting factor that gives a priori, n operation amounts calculated by a PID control calculation unit, and outputs of each actuator of the n PID control loops An inverse matrix re-transformer for re-transforming the n control deviations multiplied by the weighting factor by an inverse matrix of the state quantity transformation matrix, and each PID control loop based on the n re-transformed control deviations A PID control calculation unit that calculates an operation amount and outputs the calculated n operation amounts to the actuators of the corresponding PID control loop, and abrupt fluctuation with respect to a state amount set value input to the control deviation calculation unit And a state quantity filtering set value calculation unit that performs filtering processing for suppressing the control state, thereby calculating a control deviation for giving priority to the reference state quantity and the relative state quantity for control. The

Further, in one configuration example of the control device of the present invention, the state quantity conversion matrix is a relative state quantity that gives the converted state quantity measurement value a relative relationship between the state quantity measurement values of different PID control loops. The weighting factor that is set in advance so as to include the measurement value and is multiplied by the control deviation corresponding to the relative state quantity measurement value is set in advance so that the control priority with respect to the relative state quantity measurement value becomes high. Is.
Further, in one configuration example of the control device of the present invention, the state quantity conversion matrix includes a relative control deviation that gives a relative relationship between state quantity measurement values of different PID control loops to the converted control deviation. The weighting factor that is preset so as to be multiplied by the relative control deviation is preset so that the priority of the control with respect to the relative control deviation becomes high.
Moreover, in one structural example of the control apparatus of the present invention, the state quantity filtering set value calculation unit performs the filtering process by time delay calculation .

  According to the present invention, the state quantity conversion unit that converts the state quantity measurement values of the n control loops into values obtained by linearly combining the state quantity measurement values by the n × n state quantity conversion matrix, and the converted state A control deviation calculation unit that calculates a control deviation between the measured quantity value and the corresponding state quantity set value for each converted state quantity measurement value, and a weight coefficient corresponding to each of the calculated n control deviations A state quantity difference between a plurality of state quantities by providing a weighting coefficient setting section for performing re-transformation of the n control deviations multiplied by the weighting coefficients with an inverse matrix of the state quantity transformation matrix Thus, it is possible to realize control for changing the reference state quantity to a desired value while maintaining the relative state quantity at a desired value. 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. Furthermore, in the present invention, by providing a state quantity filtering set value calculation unit that performs a filtering process for suppressing sudden fluctuations on the state quantity set value input to the control deviation calculation unit, a relative state quantity such as a state quantity difference is provided. When the control is performed so as to decrease the saturation of the manipulated variable, the saturation of the manipulated variable can be alleviated, and the original effect of reducing the state variable difference can be avoided.

  In addition, according to the present invention, the control deviation calculation unit that calculates the control deviation between each state quantity measurement value of the n control loops and each state quantity set value corresponding thereto is calculated for each state quantity measurement value. A control deviation conversion unit that converts the n control deviations into values obtained by linearly combining the control deviations by an n × n state quantity conversion matrix, and a weight coefficient corresponding to each of the converted n control deviations. By providing a weighting factor setting unit and an inverse matrix retransformation unit that retransforms n control deviations multiplied by the weighting factor with an inverse matrix of the state quantity transformation matrix, a state quantity difference between a plurality of state quantities, etc. It is possible to realize control for changing the reference state quantity to a desired value while maintaining the relative state quantity at a desired value. 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. Furthermore, in the present invention, by providing a state quantity filtering set value calculation unit that performs a filtering process for suppressing sudden fluctuations on the state quantity set value input to the control deviation calculation unit, a relative state quantity such as a state quantity difference is provided. When the control is performed so as to decrease the saturation of the manipulated variable, the saturation of the manipulated variable can be alleviated, and the original effect of reducing the state variable difference can be avoided.

  Further, in the present invention, the relative state quantity is preferentially set by setting in advance a weighting factor for multiplying the control deviation corresponding to the relative state quantity measurement value so that the priority of the control with respect to the relative state quantity becomes high. The reference state quantity can be controlled simultaneously.

  Further, in the present invention, the weighting factor for multiplying the relative control deviation is set in advance so that the priority of the control with respect to the relative state quantity becomes high, so that the relative state quantity is controlled preferentially, and the reference state The amount can also be controlled simultaneously.

[Principle of the Invention]
Hereinafter, in the present invention, an absolute state quantity serving as a reference, for example, a state quantity average value, is referred to as a reference state quantity, for example, a relative state quantity, such as a state quantity difference, is referred to as a relative state quantity. Also, the setting value for the reference state quantity is the reference state quantity setting value, the reference state quantity measurement value is the reference state quantity measurement value, the relative state quantity setting value is the relative state quantity setting value, and the relative state quantity measurement value is the relative state The difference between the quantity measurement value, the reference state quantity set value and the reference state quantity measurement value is referred to as a reference control deviation, and the difference between the relative state quantity set value and the relative state quantity measurement value is referred to as a relative control deviation. Examples of the state quantity include temperature, pressure, and flow rate.

In the present invention, a state quantity given from the outside is converted into a reference state quantity such as a state quantity average value and a relative state quantity such as a state quantity difference by the state quantity conversion unit in the above-described prior art. When the input / output relationship of the state quantity conversion unit is expressed in a matrix, a matrix that converts a state quantity given from the outside into a reference state quantity and a relative state quantity is referred to as a state quantity conversion matrix.
Next, in the present invention, a control deviation of the converted state quantity from the state quantity set value is calculated. If the calculated control deviation is input to the controller as it is, the controller operation amount and the actual actuator output do not correspond one-to-one, so the control deviation is reconverted by the inverse matrix of the state quantity conversion matrix, Think about typing.

  If the control deviation is simply reconverted by the inverse matrix of the state quantity transformation matrix, it will only return to the equivalent of a normal control system that controls each state quantity independently. Give a weighting factor. As a result, after the re-conversion, the deviation component relating to the reference state quantity and the deviation component relating to the relative state quantity remain biased according to the weight. Therefore, while the controller operation amount and the actual actuator output have a one-to-one correspondence, the deviation from the reference state amount and the relative state amount is reflected as the priority.

  Thus, in the present invention, the state quantity given from the outside is converted by the state quantity conversion matrix, the control deviation between the converted state quantity and the set value is obtained, the control deviation is multiplied by the weighting factor, and the multiplication result Is reconverted by the inverse of the state quantity conversion matrix, and the reconverted control deviation is used to calculate the manipulated variable MV. As a result, in the present invention, if the weight is given to the reference state quantity and the weight is given to the relative state quantity, the reference state quantity measurement value PVm will follow before the reference state quantity set value SPm. Since the relative state quantity measurement value ΔPV follows the relative state quantity set value ΔSP, it is possible to control the reference state quantity to be changed to a desired value while maintaining the relative state quantity at a desired value. Become. That is, a reference state quantity such as an average value of the state quantity while preferentially controlling a relative state quantity such as a state quantity difference in a format in which the controller operation amount and the actual actuator output have a one-to-one correspondence. In addition, it is possible to provide a control device that performs simultaneous control.

  Here, the point (hereinafter referred to as the first point of interest) where the control deviation is retransformed by the inverse matrix of the state quantity transformation matrix among the above two points of interest will be described. In the control device shown in FIG. 12, artificial inter-loop interference generated by applying the state quantity conversion unit 3003 is made non-interfering by the cross controller 4005. The state quantity conversion by the state quantity conversion unit 3003 is a kind of signal crossing or signal mixing processing. Therefore, it can be said that the cross controller 4005 is a signal distribution or signal separation process for returning the signal crossing process to the original before the operation amount is sent to the actuators A1 and A2. However, in the configuration of the control device shown in FIG. 12, the controllers C1 and C2 are positioned between the state quantity conversion unit 3003 that performs signal crossing processing and the cross controller 4005 that performs signal distribution processing. C1 and C2 and actuators A1 and A2 do not correspond one to one. Therefore, in the present invention, as signal distribution processing, means for performing reconversion using an inverse matrix of the state quantity conversion matrix is arranged immediately before the controller. That is, the control deviation is reconverted by the inverse matrix of the state quantity conversion matrix.

  Next, of the above two points of interest, a point (hereinafter referred to as a second point of interest) where the control deviation is multiplied by a weighting factor before retransforming the control deviation using the inverse matrix of the state quantity conversion matrix. explain. When the control deviation between the converted state quantity and the set value is calculated after the state quantity conversion, this control deviation substantially gives the control deviation converted by the state quantity conversion matrix. Therefore, if this control deviation is simply reconverted by the inverse of the state quantity conversion matrix, the signal crossing process and the signal distribution process are directly connected, and each state quantity without conversion is independently connected. It becomes equivalent to a normal control system to control. In other words, if a meaningful signal conversion is arranged between the signal crossing process and the signal distribution process, it is reflected on the controller side in the subsequent stage. In the present invention, means for multiplying the control deviation by a weighting factor is arranged between the signal crossing process and the signal distribution process. Then, by adjusting this weighting factor, it is possible to give priority to control with respect to the state quantity in the converted state. In other words, it is possible to simultaneously control the reference state quantity such as the state quantity average value while preferentially controlling the relative state quantity such as the state quantity difference.

Here, when the first focus point and the second focus point are put together, a control system as shown in FIG. 1 is obtained. The control system of FIG. 1 is a case where the number of control loops is n (n is a natural number of 2 or more), and 1 is a state quantity conversion unit that converts the state quantity measurement values PV1 to PVn by a state quantity conversion matrix T, 2-1. ˜2-n are converted state quantity measurement values (reference state quantity measurement values or relative state quantity measurement values) PV1 ′ to PVn ′ and corresponding state quantity setting values (reference state quantity setting values or relative state quantity settings). Value) A control deviation calculation unit for calculating control deviations Er1 ′ to Ern ′ with SP1 ′ to SPn ′, 3 is a weighting factor setting unit for multiplying control deviations Er1 ′ to Ern ′ by a weighting factor, and 4 is a weighting factor. Inverse matrix reconversion unit for reconverting the multiplied control deviations Er1 ′ to Ern ′ into control deviations Er1 to Ern by the inverse matrix T ⁻¹ of the state quantity conversion matrix, MV1 to MVn are manipulated variables, A1 to An are actuators, P1 to Pn are processes to be controlled, Gp1 to Gp n is a transfer function of a block including actuators A1 to An and processes P1 to Pn.

A typical example of the controllers C1 to Cn that execute control calculations based on the control deviations Er1 to Ern is a PID controller. In addition, the state quantity conversion matrix T is an n × n square matrix when the number of control loops is n, and an inverse matrix T ⁻¹ needs to exist. FIG. 1 is a diagram illustrating the principle of the present invention, and it is not necessary to execute processing for automatically calculating an inverse matrix in each control cycle. The inverse matrix T ^-1 may be calculated manually by the operator and set in advance before the control is executed.

In the control system of FIG. 1, the average value PVm of the state quantities of all the loops is adopted as the reference state quantity, and the state quantity differences PV1-PV2, PV2-PV3, PV3-PV4,... PV (n− 2) When adopting -PV (n-1), PV (n-1) -PVn, when the input / output relationship of the state quantity conversion unit 1 is expressed in a matrix, Equation (7) is obtained. The general formula is formula (8). Further, when the input / output relationship of the inverse matrix retransformation unit 4 is expressed in a matrix, the equation (9) is obtained, and the general equation of the inverse matrix T ⁻¹ of the state quantity transformation matrix T is the equation (10).

  In the equations (7) to (10), the reference state quantity measurement value PVm is PVm = PV1 ′, and the relative state quantity measurement values PV1-PV2, PV2-PV3,..., PV (n−1) ) -PVn is PV1-PV2 = PV2 ', PV2-PV3 = PV3', ..., PV (n-1) -PVn = PVn '. W1, W2,..., Wn are weighting factors. Eri 'is a control deviation between the state quantity set value SPi' and the state quantity measurement value PVi '. However, when i = 1, the state quantity setting value SPi ′ is the reference state quantity setting value SPm = SP1 ′, and the state quantity measurement value PVi ′ is the reference state quantity measurement value PVm = PV1 ′. When i = 2 to n, the state quantity set value SPi ′ is the relative state quantity set value ΔSPi = SPi ′, and the state quantity measurement value PVi ′ is the relative state quantity measurement value PV (i−1) −PVi =. PVi ′.

  In the above description, the state quantity measurement value PVi given from the outside is converted into the state quantity measurement value PVi ′ by the state quantity conversion matrix T. However, the state quantity set value SPi is given to each state quantity, and the state quantity After calculating the control deviation Eri0 = SPi−PVi between the set value SPi and the state quantity measurement value PVi, the control deviation Eri0 may be converted into the control deviation Eri ′ by the state quantity conversion matrix T. A control system for converting the control deviation Eri0 is shown in FIG. In FIG. 2, 5-1 to 5-n are control deviation calculation units for calculating control deviations Er10 to Ern0 between the state quantity set values SP1 to SPn and the state quantity measurement values PV1 to PVn, and 6 is a control deviation Er10 to Ern0. It is a control deviation converter for converting into control deviations Er1 ′ to Ern ′. When the input / output relationship of the control deviation conversion unit 6 is expressed in a matrix, Expression (11) is obtained.

  Using the principle described above, the inventor preferentially controls a relative state quantity such as a state quantity difference in a form in which the controller operation amount and the actual actuator output correspond one-to-one. A control device that can simultaneously control a reference state quantity such as a quantity average value has been proposed (Japanese Patent Application No. 2004-128246). In the control method of the prior application, the reference state quantity is an average value of the state quantities of each control loop or a specific one state quantity. In either case, if the amount of operation can be moved up and down within a range where there is no restriction, the state quantity difference can be controlled as required.

  However, when the operation amount saturation occurs, a situation in which the control cannot be performed as requested may occur. Hereinafter, problems of the control method of the prior application will be described with reference to FIGS. 3 (a) and 3 (b). Here, there are three control loops I, II, and III, and the object of the control is to reduce the state quantity difference between the control loops. Further, the control algorithm of the controller of each control loop at this time is assumed to be PID. FIG. 3A shows a control response when a step input of the set value SP = 30% is added to the controllers of the control loops I, II, and III, and FIG. 3B shows each control at the time of this step input. The manipulated variable MV output from the controllers of the loops I, II, and III is shown.

  When step input of the set value SP is applied, the manipulated variable output MV changes greatly in normal PID calculation, and the state quantity PV changes in a direction to follow the set value SP. In order to control the state quantity difference as required in the transient state at this time, it is necessary that the manipulated variable MV is in the range of 0 to 100% and can be freely increased or decreased. However, when the operation amount MV calculated by the controller greatly exceeds 100%, the operation amount MV actually output from the controller is 100% even though the operation amount MV can be increased or decreased in calculation. It becomes the situation that does not change while being saturated. Therefore, the effect of reducing the state quantity difference cannot be obtained. As described above, the control method of the prior application has a problem that the original effect is impaired due to the occurrence of the manipulated variable saturation.

  On the other hand, in the present invention, attention is paid to the fact that the cause of this problem is a differential kick peculiar to the PID control calculation that occurs when the set value SP is stepped. For example, when a sudden change in the set value SP acts on the differential operation of the PID, the manipulated variable MV also suddenly changes in a direction to follow the sudden change in the set value SP, and the manipulated variable saturation occurs.

  In order to solve the problems of the prior application, it is only necessary to maintain the manipulated variable MV as much as possible within a range that is not subject to the restriction of the manipulated variable upper and lower limit processing based on the cause of the aforementioned problem. In particular, it is important that the differential kick is relaxed, and it is only necessary that the sudden change of the set value SP does not affect the PID control calculation or is sufficiently relaxed. Therefore, in the present invention, a filter that applies a damping effect to the change in the set value SP is applied. As this filter, a time delay filter having a simple structure such as a first-order delay and a second-order delay is suitable.

  As a filter setting method, there is a method in which the degree of occurrence of the manipulated variable saturation is examined in advance and, for example, the time constant of the first-order lag filter is appropriately set. However, this method is applicable only when the control operation occurs only in a pattern that can be seen in advance. More preferably, it should be possible to automatically correct the time constant of the first-order lag filter in response to the occurrence of operation amount saturation. If the cause of the manipulated variable saturation is a sudden change in the set value SP, the time constant of the first-order lag filter may be automatically corrected in conjunction with the change range of the set value SP, and the change range of the set value SP is large. Is a way to increase the time constant. More specifically, the time constant should be automatically corrected with reference to the manipulated variable MV value before changing the set value SP, the set PID parameter, and the like.

[Embodiment]
FIG. 4 is a block diagram showing the configuration of the control device according to the embodiment of the present invention. The present embodiment is based on the principle described with reference to FIG. 2, and has three control loops, adopts an average value of the three control loop state quantities as the reference state quantity, and each state quantity as the relative 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. 4 has a state quantity set value SP1 input unit 21-1, a state quantity measurement value PV1 input unit 22-1 and a control deviation Er10 as the configuration of the first control system related to the first state quantity. 4 includes a unit 23-1, an operation amount MV1 output unit 24-1, a PID control calculation unit (PID controller) 25-1, and a state amount filtering set value SP1 ″ calculation unit 29-1. As a configuration of the second control system related to the second state quantity, the control device includes a state quantity set value SP2 input unit 21-2, a state quantity measurement value PV2 input unit 22-2, and a control deviation Er20 calculation unit 23-. 2, an operation amount MV2 output unit 24-2, a PID control calculation unit (PID controller) 25-2, and a state amount filtering set value SP 2 ″ calculation unit 29-2. In addition, the control device of FIG. 4 includes a state quantity set value SP3 input unit 21-3, a state quantity measured value PV3 input unit 22-3, a control deviation as a third control system configuration relating to the third state quantity. An Er30 calculation unit 23-3, an operation amount MV3 output unit 24-3, a PID control calculation unit (PID controller) 25-3, and a state amount filtering set value SP3 ″ calculation unit 29-3 are provided.

4 includes a control deviation conversion unit 26 that executes control deviation conversion by the state quantity conversion matrix T, and a weighting factor W1 setting unit that multiplies the relative control deviation ΔEr1 by the weighting factor W1. 27-1, a weighting factor W2 setting unit 27-2 that multiplies the relative control deviation ΔEr2 by a weighting factor W2, a weighting factor W3 setting unit 27-3 that multiplies the reference control deviation Erm by a weighting factor W3, and a state quantity conversion matrix T. And an inverse matrix retransformation unit 28 for performing an inverse matrix retransformation with an inverse matrix T ⁻¹ of

  Further, the control device of FIG. 4 has a configuration related to the filter time constant adaptive correction, and when at least one of the state quantity set values SP1, SP2 and SP3 is changed, the set value of the control loop j in which the set value is changed. An operation amount detection unit 30 at the time of setting value change that acquires the operation amount MVj immediately before the change, and an operation amount upper limit margin RHj that is a difference between the predetermined operation amount upper limit value and the operation amount MVj when the setting value change is detected. Or an operation amount upper / lower limit margin calculating unit 31 for calculating an operation amount lower limit margin RLj which is a difference between a predetermined operation amount lower limit value and the operation amount MVj, and a setting in the control loop j when a change in the set value is detected. A manipulated variable change estimation unit 32 that estimates a manipulated variable change ΔMVj that occurs when a PID control calculation is performed without performing filtering on values, and an manipulated variable upper limit margin RHj A filtering time constant Tf is determined on the basis of the operation amount lower limit margin RLj, the operation amount change ΔMVj, and a preset ratio αj, and this filtering time constant Tf and the state amount filtering set value SP1 ″ calculating unit 29-1 and the state are determined. A filtering time constant determining unit 33 that is set in the amount filtering setting value SP2 "calculating unit 29-2 and the state amount filtering setting value SP3" calculating unit 29-3. The setting value changing operation amount detecting unit 30 and the operation amount are provided. The upper and lower limit margin calculating unit 31, the operation amount change estimating unit 32, and the filtering time constant determining unit 33 constitute correcting means for adaptively correcting the filtering time constant Tf.

  FIG. 5 is a block diagram of the control system in the present embodiment. A11 is an actuator that controls the first state quantity, A12 is an actuator that controls the second state quantity, A13 is an actuator that controls the third state quantity, P11 is a process to be controlled related to the first state quantity, P12 Is a control target process related to the second state quantity, P13 is a control target process related to the third state quantity, Gp11 is a transfer function of a block including the actuator A11 and the process P11, and Gp12 includes the actuator A12 and the process P12. A block transfer function, Gp13, is a block transfer function including the actuator A13 and the process P13.

  State quantity set value SP1 input section 21-1, state quantity measured value PV1 input section 22-1, control deviation Er10 calculation section 23-1, manipulated variable MV1 output section 24-1, and PID control calculation section 25- 1, the control deviation conversion unit 26, the inverse matrix re-conversion unit 28, the state quantity filtering set value SP1 ″ calculation unit 29-1, the actuator A 11, and the process P 11 include a first control system (first Control amount SP2 input unit 21-2, state quantity measured value PV2 input unit 22-2, control deviation Er20 calculation unit 23-2, and manipulated variable MV2 output unit 24- 2, PID control calculation unit 25-2, control deviation conversion unit 26, inverse matrix re-conversion unit 28, state quantity filtering set value SP 2 ″ calculation unit 29-2, actuator A 12, and process P 12 are: Second control Constitute a (second control loop). Then, the state quantity set value SP3 input unit 21-3, the state quantity measured value PV3 input unit 22-3, the control deviation Er30 calculation unit 23-3, the operation amount MV3 output unit 24-3, and the PID control calculation unit 25-3, the control deviation conversion unit 26, the inverse matrix re-conversion unit 28, the state quantity filtering set value SP3 ″ calculation unit 29-3, the actuator A13, and the process P13 include a third control system (first 3 control loop).

  Next, the operation of the control device of the present embodiment will be described with reference to FIG. First, the state quantity measurement value PV1 is detected by a first detection unit (not shown) and input to the control deviation Er10 calculation unit 23-1 via the state quantity measurement value PV1 input unit 22-1 (step S101 in FIG. 6). ). The state quantity measurement value PV2 is detected by a second detection unit (not shown), and is input to the control deviation Er20 calculation unit 23-2 via the state quantity measurement value PV2 input unit 22-2 (step S102). The state quantity measurement value PV3 is detected by a third detection unit (not shown), and is input to the control deviation Er30 calculation unit 23-3 via the state quantity measurement value PV3 input unit 22-3 (step S103).

  The state quantity set value SP1 is set by an operator of the control device, and the state quantity filtering set value SP1 "calculating unit 29-1 and the set value changing operation quantity detecting unit 30 via the state quantity set value SP1 input unit 21-1. (Step S104) The state quantity set value SP2 is set by the operator, and the state quantity filtering set value SP2 "calculating unit 29-2 and the set value are set via the state quantity set value SP2 input unit 21-2. This is input to the change operation amount detection unit 30 (step S105). The state quantity set value SP3 is set by the operator, and is input to the state quantity filtering set value SP3 "calculating unit 29-3 and the set value change manipulated variable detecting unit 30 via the state quantity set value SP3 input unit 21-3. (Step S106).

Next, when at least one of the state quantity set values SP1, SP2, SP3 is changed, the set value change operation amount detection unit 30 performs an operation immediately before the set value change of the control loop j in which the set value is changed. The amount MVj is acquired (step S107).
The operation amount upper / lower limit allowance calculating unit 31 operates when the set value change operation amount detection unit 30 detects a change in the set value, which is a difference between a predetermined operation amount upper limit value and the operation amount MVj. Alternatively, an operation amount lower limit margin RLj that is the difference between the predetermined operation amount lower limit value and the operation amount MVj is calculated (step S108).

When the manipulated variable MVj has to be changed to a large value (when the changed state quantity set value is larger than the pre-changed state quantity set value), the manipulated variable upper / lower limit margin calculating unit 31 sets the manipulated variable upper / lower limit margin RHj. Calculated by the following formula.
RHj = OHj-MVj (12)
In Expression (12), OHj is the operation amount upper limit value of the control loop j.

Further, the operation amount upper / lower limit margin calculating unit 31 operates when the operation amount MVj has to be changed to a small value (when the state quantity setting value after change is smaller than the state quantity setting value before change). RLj is calculated by the following equation.
RLj = OLj-MVj (13)
In Expression (13), OLj is the operation amount lower limit value of the control loop j.

The manipulated variable change estimation unit 32 occurs when a set value change is detected by the manipulated variable detection unit 30 when a set value is changed, and when a PID control calculation is executed without performing a filtering process on the set value in the control loop j. The manipulated variable change ΔMVj per control cycle is estimated by the following equation (step S109).
ΔMVj = (100 / Pbj) {1+ (1 / Tijs) + Tdjs} (SPj
−PVj) −MVj (14)
The transfer function equation (100 / Pbj) {1+ (1 / Tijs) + Tdjs} (SPj−PVj) in the equation (14) is a PID control arithmetic expression of the control loop j, Pbj is a proportional band, Tij is an integration time, Tdj is a differential time, and s is a Laplace operator.

  The filtering time constant determination unit 33 determines the filtering time constant Tf when the setting value change is detected by the setting value change operation amount detection unit 30, and the filtering time constant Tf is calculated as the state amount filtering setting value SP1 ″ calculation unit. 29-1 and state quantity filtering set value SP2 "calculating section 29-2 and state quantity filtering setting value SP3" calculating section 29-3 are set (step S110).

When the manipulated variable MVj must be changed to a large value, the filtering time constant determination unit 33 calculates a filtering time constant candidate value Tfj by the following equation.
Tfj = αjΔMVj / RHj (15)
Further, when the manipulated variable MVj needs to be changed to a small value, the filtering time constant determination unit 33 calculates the filtering time constant candidate value Tfj by the following equation.
Tfj = αjΔMVj / RLj (16)

  Note that the number of control loops j in which the state quantity set value is changed is not limited to one. Therefore, the processing of steps S107 to S109 and the calculation of equations (15) and (16) are performed individually for each of the control loops j whose set values have been changed.

  The ratio αj used in Expression (15) and Expression (16) is determined by control simulation, and is preset in the filtering time constant determination unit 33. In this control simulation, the response of the control loop j when the set value SP is changed from the initial state where the operation amount MV = 0 is obtained without performing the operation amount upper / lower limit processing. When the maximum value of the manipulated variable that appears when the filtering process is not performed is MVa, and the maximum value of the manipulated variable when the filtering process is performed with the filtering time constant as an arbitrary value Tfx is MVb, αj = Tfx (MVb / MVa) You just have to decide. Further, when it is desired to finely correct the grain, case division is made according to the value of ΔMVj / (OHj−MVj) or ΔMVj / (OLj−MVj), and the ratio αj may be set for each case. Since the value of the manipulated variable MV changes depending on the value of the PID parameter set in the PID control calculation unit, and as described above, the number of control loops j in which the state quantity set value is changed is not limited to one. The ratio αj needs to be prepared in advance for each of the first to third control loops.

  The filtering time constant determination unit 33 determines the maximum value of the filtering time constant candidate values Tfj calculated for each of the control loops j as the filtering time constant Tf, and uses this filtering time constant Tf as the state quantity filtering setting value SP1 ″. The calculation unit 29-1, the state quantity filtering setting value SP2 "calculation unit 29-2, and the state quantity filtering setting value SP3" calculation unit 29-3 are set. The process of step S110 is thus completed.

Next, the state quantity filtering setting value SP1 ″ calculating unit 29-1 performs a first-order lag filtering process such as the following transfer function expression on the state quantity setting value SP1 to obtain the state quantity filtering setting value SP1 ″. Is calculated (step S111).
SP1 ″ = SP1 / (1 + Tfs) (17)

The state quantity filtering set value SP2 "calculating unit 29-2 performs a first-order lag filtering process such as the following transfer function expression on the state quantity set value SP2 to calculate the state quantity filtering set value SP2". (Step S112).
SP2 ″ = SP2 / (1 + Tfs) (18)

The state quantity filtering setting value SP3 ″ calculating unit 29-3 performs a first-order lag filtering process such as the following transfer function expression on the state quantity setting value SP3 to calculate the state quantity filtering setting value SP3 ″. (Step S113).
SP3 ″ = SP3 / (1 + Tfs) (19)

Subsequently, the control deviation Er10 calculation unit 23-1 calculates the control deviation Er10 between the state quantity filtering set value SP1 "and the state quantity measurement value PV1 as shown in the following equation and outputs the control deviation Er10 to the control deviation conversion unit 26 ( Step S114).
Er10 = SP1 ″ −PV1 (20)

The control deviation Er20 calculation unit 23-2 calculates the control deviation Er20 between the state quantity filtering set value SP2 "and the state quantity measurement value PV2 as shown in the following equation, and outputs it to the control deviation conversion unit 26 (step S115). .
Er20 = SP2 ″ −PV2 (21)

The control deviation Er30 calculation unit 23-3 calculates the control deviation Er30 between the state quantity filtering setting value SP3 ″ and the state quantity measurement value PV3 as shown in the following equation, and outputs it to the control deviation conversion unit 26 (step S116). .
Er30 = SP3 ″ −PV3 (22)

  The control deviation conversion unit 26 executes the control deviation conversion by the state quantity conversion matrix T as shown in the equation (23), calculates the relative control deviations ΔEr1, ΔEr2, and the reference control deviation Erm, and the relative control deviations ΔEr1, ΔEr2 Are output to the weighting factor W1 setting unit 27-1 and the weighting factor W2 setting unit 27-2, respectively, and the reference control deviation Erm is output to the weighting factor W3 setting unit 27-3 (step S117). The preset state quantity conversion matrix T is as shown in Expression (24).

  The weighting factor W1 setting unit 27-1 multiplies the preset weighting factor W1 by the relative control deviation ΔEr1, and outputs the multiplication result to the inverse matrix reconversion unit 28 (step S118). The weighting factor W2 setting unit 27-2 multiplies the relative weighting factor W2 by a preset weighting factor W2 and outputs the multiplication result to the inverse matrix reconversion unit 28 (step S119). The weighting factor W3 setting unit 27-3 multiplies the preset weighting factor W3 by the reference control deviation Erm, and outputs the multiplication result to the inverse matrix reconversion unit 28 (step S120).

The inverse matrix retransformation unit 28 performs inverse matrix retransformation using the inverse matrix T ⁻¹ of the state quantity transformation matrix T as shown in Expression (25), calculates control deviations Er1, Er2, Er3, and calculates a PID control operation unit Output to 25-1, 25-2, 25-3 (step S121). The preset inverse matrix T ⁻¹ is as shown in Expression (26).

Next, the PID control calculation unit 25-1 calculates a manipulated variable MV1 by performing a PID control calculation like the following transfer function equation (step S122).
MV1 = (100 / Pb1) {1+ (1 / Ti1s) + Td1s} Er1
... (27)
In Expression (27), 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 A11, the PID control calculation unit 25-1 sets the operation amount MV1 = OL1 and the calculated operation amount MV1 is the upper limit value OH1 of the output of the actuator A11. If larger, an operation amount upper / lower limit process for setting the operation amount MV1 = OH1 is performed as a measure for integral windup.

The PID control calculation unit 25-2 performs a PID control calculation like the following transfer function equation to calculate the operation amount MV2 (step S123).
MV2 = (100 / Pb2) {1+ (1 / Ti2s) + Td2s} Er2
... (28)
In Expression (28), 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 A12, the PID control calculation unit 25-2 sets the operation amount MV2 = OL2 and the calculated operation amount MV2 is larger than the upper limit value OH2 of the output of the actuator A12. In this case, the operation amount upper / lower limit process for setting the operation amount MV2 = OH2 is performed as a measure against the integral windup.

The PID control calculation unit 25-3 calculates a manipulated variable MV3 by performing a PID control calculation such as the following transfer function equation (step S124).
MV3 = (100 / Pb3) {1+ (1 / Ti3s) + Td3s} Er3
... (29)
In Expression (29), 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 A13, the PID control calculation unit 25-3 sets the operation amount MV3 = OL3, and the calculated operation amount MV3 is larger than the upper limit value OH3 of the output of the actuator A13. In this case, the operation amount upper / lower limit process for setting the operation amount MV3 = OH3 is performed as a measure against the integral windup.

The operation amount MV1 output unit 24-1 outputs the operation amount MV1 calculated by the PID control calculation unit 25-1 to the actuator A11 (step S125). The actuator A11 operates to control the first state quantity based on the operation quantity MV1.
The operation amount MV2 output unit 24-2 outputs the operation amount MV2 calculated by the PID control calculation unit 25-2 to the actuator A12 (step S126). The actuator A12 operates to control the second state quantity based on the operation quantity MV2.
The operation amount MV3 output unit 24-3 outputs the operation amount MV3 calculated by the PID control calculation unit 25-3 to the actuator A13 (step S127). The actuator A13 operates to control the third state quantity based on the operation quantity MV3.

  The processes in steps S101 to S127 as described above are repeatedly executed for each control cycle until the operator instructs the end of the control (YES in step S128).

  FIG. 7 is a diagram illustrating a simulation result of the control device according to the present embodiment. FIG. 7 (a) shows a control response when a step input of SP1 = SP2 = SP3 = 30% is added to the control device of FIG. 1, and FIG. 7 (b) is output from the control device at the time of this step input. The manipulated variables MV1, MV2, and MV3 are shown. The simulation conditions are as follows.

First, the transfer function Gp11 of the block including the actuator A11 and the process P11, the transfer function Gp12 of the block including the actuator A12 and the process P12, and the transfer function Gp13 of the block including the actuator A13 and the process P13 are set as follows: To do. Here, it is assumed that there is no interference between control loops.
Gp11 = 0.343exp (−2.0 s)
/{(1+70.0s)(1+10.0s)} (30)
Gp12 = 0.800exp (−2.0 s)
/{(1+60.0s)(1+10.0s)} (31)
Gp13 = 0.308exp (−2.0 s)
/{(1+50.0s)(1+10.0s)} (32)

The operation amount lower limit value OL1 of the PID control calculation unit 25-1 is 0%, the upper limit value OH1 is 100%, the operation amount lower limit value OL2 of the PID control calculation unit 25-2 is 0%, and the upper limit value OH2 is 100%. The operation amount lower limit value OL3 of the PID control calculation unit 25-3 is set to 0%, and the upper limit value OH3 is set to 100%. The state quantity measurement values PV1, PV2, and PV3 are determined as follows according to the operation amounts MV1, MV2, and MV3.
PV1 = Gp11MV1 (33)
PV2 = Gp12MV2 (34)
PV3 = Gp13MV3 (35)

  The proportional band Pb1 which is the PID parameter of the PID control calculation unit 25-1 is 14.3, the integration time Ti1 is 35.0, the differential time Td1 is 20.0, and the proportionality which is the PID parameter of the PID control calculation unit 25-2 The band Pb2 is 13.3, 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 25-3 is 15.4, and the integration time Ti3 is 35. 0, the differential time Td3 is 20.0. Further, the weighting factors W1 and W2 are set to 4.0, the weighting factor W3 is set to 0.7, and the ratio αj is set to 10.0. As a result, the filtering time constant Tf calculated by the filtering time constant determining unit 33 is about 75 seconds.

  As can be seen from FIG. 7B, according to the present embodiment, there is no situation in which the manipulated variables MV1, MV2, and MV3 greatly exceed the upper limit value of 100%, and it can be seen that manipulated variable saturation can be alleviated. . As a result, in this embodiment, as shown in FIG. 7A, it is possible to avoid the effect of reducing the state quantity difference between the control loops from being lost, and the state quantity as shown in FIG. 7A. The measured values PV1, PV2, and PV3 can be substantially matched.

  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.

  In the present embodiment, the control device based on the configuration of FIG. 2 has been described. However, as described above, the present invention can also be applied to the configuration of FIG. In this case, the control device includes a state quantity conversion unit 1, control deviation calculation units 2-1 to 2-n, a weight coefficient setting unit 3, an inverse matrix reconversion unit 4, and n reconverted controls. A control operation unit that calculates the operation amount of each control loop based on the deviation and outputs the calculated n operation amounts to the control target of the corresponding control loop. Thereby, the same effect as this embodiment can be obtained.

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

It is a block diagram of a control system showing the principle of the present invention. It is a block diagram of another control system showing the principle of the present invention. It is a figure for demonstrating the problem of the control apparatus of a prior application. 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 in embodiment of this invention. It is a figure which shows the simulation result of operation | movement of the control apparatus in embodiment of this invention. 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 block diagram which shows the structure of the conventional control apparatus which makes a control object the state quantity average value and a state quantity difference. It is a block diagram which shows the structure of the conventional control apparatus using a cross controller. It is a block diagram which shows the structure which applied the cross controller of FIG. 11 to the control apparatus of FIG. It is a figure for demonstrating the conventional parameter adjustment.

Explanation of symbols

23-1 ... control deviation Er10 calculation unit, 23-2 ... control deviation Er20 calculation unit, 23-3 ... control deviation Er30 calculation unit, 25-1, 25-2, 25-3 ... PID control calculation unit, 26 ... control Deviation conversion unit, 27-1 ... weighting factor W1 setting unit, 27-2 ... weighting factor W2 setting unit, 27-3 ... weighting factor W3 setting unit, 28 ... inverse matrix reconversion unit, 29-1 ... state quantity filtering setting Value SP1 "calculation unit, 29-2 ... state quantity filtering set value SP2" calculation unit, 29-3 ... state quantity filtering set value SP3 "calculation unit, 30 ... setting value change operation amount detection unit, 31 ... on operation amount Lower limit margin calculation unit, 32 ... operation amount change estimation unit, 33 ... filtering time constant determination unit.

Claims (5)

In a control system controller having n (n is a natural number of 2 or more) parallel PID control loops,
When a certain reference absolute state quantity is a reference state quantity, and a relative state quantity that is a state quantity difference is a relative state quantity,
N × for converting the n PID control each of the n state quantity measurement values loop is input to, on one reference state quantity measurement value and the (n-1) and the relative state quantity measurement value a state quantity conversion unit linear combination to convert the said reference state quantity measurement value and the relative state quantity measurement value by n state quantity conversion matrix,
Either the control deviation between the converted reference state quantity measured value and the corresponding reference state quantity set value or the control deviation between the converted relative state quantity measured value and the corresponding relative state quantity set value A control deviation calculation unit for calculating for each converted state quantity measurement value,
A weighting factor setting unit that multiplies each of the calculated n control deviations by a weighting factor that gives priority to control;
In order to make one-to-one correspondence between the n operation amounts calculated by the PID control calculation unit and the outputs of the actuators of the n PID control loops, the n control deviations multiplied by the weighting coefficient are An inverse matrix retransformation unit that retransforms the inverse of the state quantity transformation matrix;
A PID control calculation unit that calculates an operation amount of each PID control loop based on the reconverted n control deviations, and outputs the calculated n operation amounts to an actuator of the corresponding PID control loop;
A state quantity filtering setting value calculation unit that performs filtering processing for suppressing sudden fluctuations with respect to the reference state quantity setting value and the relative state quantity setting value input to the control deviation calculation unit,
A control apparatus for calculating a control deviation for performing control by giving priority to a reference state quantity and a relative state quantity. In a control system controller having n (n is a natural number of 2 or more) parallel PID control loops,
When a certain reference absolute state quantity is a reference state quantity, and a relative state quantity that is a state quantity difference is a relative state quantity,
A control deviation calculation unit that calculates a control deviation between each state quantity measurement value input to the n PID control loops and each state quantity set value corresponding thereto, for each state quantity measurement value;
The n control deviation the calculated, corresponding to the relative state quantities and one control deviation corresponding to the reference state quantity (n-1) of the n × n for converting the number of the control deviation a control deviation conversion unit linear combination to the state quantity conversion matrix to convert a control deviation corresponding to the relative state quantity control deviation corresponding to the reference state amount,
A weighting factor setting unit that multiplies each of the converted n control deviations by a weighting factor that gives priority to control;
In order to make one-to-one correspondence between the n operation amounts calculated by the PID control calculation unit and the outputs of the actuators of the n PID control loops, the n control deviations multiplied by the weighting coefficient are An inverse matrix retransformation unit that retransforms the inverse of the state quantity transformation matrix;
A PID control calculation unit that calculates an operation amount of each PID control loop based on the reconverted n control deviations, and outputs the calculated n operation amounts to an actuator of the corresponding PID control loop;
By providing a state quantity filtering setting value calculation unit that performs a filtering process for suppressing sudden fluctuations with respect to the state quantity setting value input to the control deviation calculation unit,
A control apparatus for calculating a control deviation for performing control by giving priority to a reference state quantity and a relative state quantity. The control device according to claim 1,
The state quantity conversion matrix is preset so that the converted state quantity measurement value includes a relative state quantity measurement value that gives a relative relationship between the state quantity measurement values of different PID control loops,
The control apparatus is characterized in that the weighting factor multiplied by the control deviation corresponding to the relative state quantity measurement value is set in advance so that the priority of control with respect to the relative state quantity measurement value becomes high. The control device according to claim 2,
The state quantity conversion matrix is preset so that the converted control deviation includes a relative control deviation that gives a relative relationship between state quantity measurement values of different PID control loops,
The control apparatus is characterized in that the weighting factor multiplied by the relative control deviation is set in advance so that a priority of control with respect to the relative control deviation is increased. The control device according to any one of claims 1 to 4,
The state quantity filtering set value calculation unit performs the filtering process by time delay calculation .

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