JP2002123302A - Controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life components including a potentiometer provided on a motor and to actualize a control corresponding to the characteristics of a controlled system. SOLUTION: This controller is equipped with an arithmetic unit 22 and a PID control means 23 for outputting a 1st manipulated variable according to both a controlled variable and a set value, a manipulated variable variation rate limiting means 29 which limits the variation rate of the 1st manipulated variable outputted from the PID control means 23 to smaller than a specific manipulated variable variation rate according to a manipulated variable variation rate limit value and outputs it as a 2nd manipulated variable, and a position proportional control means 34 which has a dead zone set and outputs an operation command according to the 2nd manipulated variable and a motor feedback quantity indicating the opening extent of a valve 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling, for example, the opening of a valve driven by a motor so that a control amount of a control target detected by a sensor is equal to a set value.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a configuration of a conventional control system. In the figure, 101 is a control device,
Reference numeral 102 denotes a control target. Reference numeral 103 denotes a motor driven by an operation command output from the control device 101, and reference numeral 104 denotes a valve arranged in a flow path of a fluid supplied to the control target 102, and the valve opening is adjusted by the motor.
The motor 103 is provided with a potentiometer that detects the degree of opening of the valve 104 as an electric signal and outputs it to the control device 101 as a motor feedback amount. 1
Reference numeral 05 denotes a sensor for detecting the state of the controlled object 102, for example, temperature, water level, and the like.
Output to 1.

FIG. 7 is a block diagram showing the configuration of the control device 101. Reference numeral 201 denotes a set amount setting means for setting the set amounts of the temperature, the water level, and the like. An arithmetic unit 202 calculates and amplifies the difference between the set amount set by the set amount setting unit 201 and the control amount input of the sensor 105, and outputs the calculation result. Numeral 203 denotes a PID control means, based on the result of the calculation, P (proportional) I (integral) D
(Differential) operation and outputs the manipulated variable. 20
Reference numeral 4 denotes position proportional control means for outputting an operation command based on a motor feedback amount, which is a valve opening of the valve 104 output from the potentiometer attached to the motor 103, and the operation amount. is there. A dead zone as shown in FIG. 8 is set in the position proportional control means 204 so as not to output an operation command when the motor feedback amount is within a certain range in relation to the operation amount. 205 is the position proportional control means 204
A dead zone setting means for setting the dead zone.

Next, the operation will be described. Control device 10
In 1, a control amount is input from the sensor 105 of the control target 102, and a difference between the control amount and the set amount set by the set amount setting unit 201 is calculated by the calculator 202. This calculation result is amplified and output to the PID control means 203. The PID control unit 203 performs a PID calculation to calculate an operation amount. Further, the position proportional control means 204 outputs an operation command of an opening command or a closing command from the motor feedback amount output from the potentiometer attached to the motor 103 and the calculated operation amount. Then, the motor 103 is driven by the operation command,
The valve opening of the valve 104 is controlled so that the control amount of the control target 102 matches the set amount set by the set amount setting means 201.

[0005]

Since the conventional control device is configured as described above, the amount of control output from the controlled object 102 slightly fluctuates due to the influence of environmental changes, noise, and the like on the controlled object 102. If a change that should not occur should occur, even if the change is slight, P
The ID control means 203 reflects this slight change in the control amount on the operation amount and outputs it as an operation command. As a result, the motor 103 is driven, and the sliding portion of the potentiometer provided on the motor 103 is worn each time. For this reason, by setting the dead zone, the output of the operation command is suppressed for the slight change in the control amount.However, if the dead zone is set to a large value, highly accurate control cannot be performed. A smaller dead zone increases the possibility of hunting and other phenomena, so that highly accurate control is possible depending on the range of the set dead zone, while outputting a potentiometer or an operation command provided to the motor. There is a problem of shortening the life of the relay contact for performing the operation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and aims to extend the life of components including a potentiometer provided in a motor and to perform control according to characteristics of a control target. It is an object to obtain a control device that can be realized.

[0007]

According to the present invention, there is provided a control device, comprising: an operation amount calculating means for outputting a first operation amount based on a control amount and a set value; An operation amount change rate limiting unit that limits the first operation amount change rate to a predetermined operation amount change rate or less based on the operation amount change rate limit value and outputs the second operation amount as a second operation amount; A dead zone for not outputting an operation command is set, and based on the second operation amount output from the operation amount change rate limiting unit and a feedback amount indicating a valve opening degree of a valve driven by the driving unit, And a position proportional control means for outputting an operation command.

In the control device according to the present invention, the operation amount change rate limiting means sets the operation amount change rate limit value when the first operation amount is limited by determining whether the valve opening degree of the valve is between fully closed and fully open. A manipulated variable change rate calculating means for calculating and outputting based on the full opening time required for moving, and a dead zone of the position proportional control means based on the manipulated variable change rate limit value calculated by the manipulated variable change rate calculating means. And a dead zone calculation means for setting the range of

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of a control system according to the first embodiment, and FIG. 2 is a block diagram showing a configuration of a control device in the control system. In FIG. 1, reference numeral 1 denotes a control device, and 2 denotes a control target such as a boiler whose hot water temperature is controlled by the control device 1. Reference numeral 3 denotes a motor (driving means) driven by an operation command output from the control device 1, and 4 denotes a valve arranged in a flow path of, for example, fuel supplied to the control target 2. Is adjusted. The motor 3 is provided with a potentiometer that detects the valve opening of the valve 4 as an electric signal and outputs the electric signal to the control device 1 as a motor feedback amount. Reference numeral 5 denotes a sensor that detects the temperature of the control target 2, detects the temperature as an electric signal, and outputs the detected signal to the control device 1 as a control amount input.

In FIG. 2, reference numeral 21 denotes a set amount setting means for setting the set amount for the temperature. Numeral 22 denotes an arithmetic unit (operating amount calculating means) which calculates and amplifies the difference between the set amount set by the set amount setting means 21 and the control amount input of the sensor 5, and outputs the calculated result. 23
Is a PID control means (operating amount calculating means) which performs a P (proportional) I (integral) D (differential) calculation based on the calculation result and outputs a first manipulated variable.

Reference numeral 24 denotes a switching setting means for setting one of a controllability emphasis mode in which controllability is emphasized and a potentio life emphasis mode in which the life of the potentiometer is emphasized.

Reference numeral 25 denotes an operation amount change rate setting means for setting an operation amount change rate when the controllability mode is set by the switching setting means 24. The operation amount change rate is controlled by a control device. 1 is set by an operator using a key switch (not shown) provided in the apparatus.

Reference numeral 26 denotes a full-open time setting means for setting a full-open time from the fully-closed state to the fully-opened state of the valve 4 in units of seconds. It is input by the operator based on the full open time of the valve 4.

Reference numeral 27 denotes an operation amount change rate calculation means for calculating an operation amount change rate limit value when the potentiometer life emphasis mode is set by the switch setting means 24, which is set by the fully open time setting means 26. Full open time,
It is used as a parameter when calculating the manipulated variable change rate limit value. The arithmetic expression for calculating the manipulated variable change rate limit value is [1 / {full opening time × (1 / update cycle)}] × coefficient × 100
(%), The update cycle is, for example, 500 ms, and the coefficient is a fixed value as a safety coefficient, for example, 1.1. In this case, the manipulated variable change rate limit value is in the range of 0.5% to 5% of the full opening time. 2
Reference numeral 8 denotes switching means for switching the operation amount change rate. The operation amount change rate or the operation amount change rate set by the operation amount change rate setting means 25 in accordance with each mode set by the switch setting means 24. One of the operation amount change rate limit values calculated by the rate calculation means 27 is selected and switched.

Numeral 29 denotes an operation amount change rate limiting means. The operation amount change rate input from the operation amount change rate setting means 25 or the operation amount change rate input from the operation amount change rate calculation means 27 is provided for each update cycle. The rate of change of the first operation amount is limited by using the rate limit value as a limit, and is output as a second operation amount. For example, the input operation amount change rate is 10%.
Then, the rate of change of the first manipulated variable is from 0% to 100%.
%, The rate of change is limited for each update cycle as shown in FIG. 3, and is output as a second manipulated variable.

Reference numeral 31 denotes a dead zone setting means for setting a range of a dead zone when the control setting mode is set in the switching setting means 24. The dead zone range is provided in the control device 1. Is set by the operator using a key switch (not shown).

Numeral 32 denotes a dead zone calculating means for calculating the range of the dead zone when the potentio life priority mode is set by the switching setting means 24. The range of the dead zone is calculated using (limit value) × (coefficient) as an arithmetic expression. This coefficient is a fixed value, for example, 8. In this case, the range of the dead zone is in the range of 4.0% to 20% of the full opening time.

Reference numeral 33 denotes a switching means, which corresponds to each of the modes set by the switching setting means 24, the range of the dead zone set by the dead zone setting means 31 or the dead zone calculated by the dead zone calculating means 32. One of the ranges is selected and switched.

Reference numeral 34 denotes position proportional control means, which is used to open or close based on the range of the dead zone selected by the switching means 24, the second operation amount, and the motor feedback amount output from the potentiometer. Outputs a command operation command.

Next, the operation will be described. In the control device 1, a control amount is input from the sensor 5 of the control target 2, and a difference between the control amount and the set amount set by the set amount setting unit 21 is calculated by the calculator 22. This calculation result is amplified and output to the PID control means 23. PID control means 2
In step 3, a PID calculation is performed to calculate a first manipulated variable. This first operation amount is output to the operation amount change rate limiting means 29.

Here, a case where the controllability emphasis mode is set by the switching setting means 24 will be described first.
When the controllability-oriented mode is set, the operation amount change rate set by the operation amount change rate setting means 25 is output to the operation amount change rate restriction means 29. The range of the dead zone set by the dead zone setting means 31 is output to the position proportional control means 34. The operation amount change rate and the range of the dead zone are set by an operator using key switches (not shown) provided on the control device 1. The operation amount change rate limiting means 29 limits the first operation amount based on the operation amount change rate set by the operator, and outputs the first operation amount to the position proportional control means 34 as a second operation amount. The position proportional control means 34 outputs an operation command by applying the range of the dead zone set by the dead zone setting means 31 based on the second operation amount and the motor feedback amount.

FIG. 4A shows the control characteristic of the position proportional control means 34 when the current value of the motor feedback amount is smaller than the second operation amount, and the motor feedback amount exceeds the dead zone. If it is smaller than the operation amount, the position proportional control means 34 outputs an operation command of an opening command, and adjusts the valve opening of the valve 4 by the motor 3 so that the motor feedback amount approaches the second operation amount. . FIG. 4B shows the control characteristics of the position proportional control means 34 when the current value of the motor feedback amount is larger than the second operation amount, and the motor feedback amount exceeds the dead zone. If the operation amount is larger than the operation amount, the position proportional control means 34 outputs an operation command of a close command, and adjusts the valve opening of the valve 4 by the motor 3 so that the motor feedback amount approaches the second operation amount. FIG. 4C shows the control characteristics of the position proportional control means 34 when the current value of the motor feedback amount matches the second operation amount. In this case, the position proportional control means 34 issues an open command. , Does not output any operation command.

Accordingly, when the controllability emphasis mode is set, the operation amount set by the operation amount change rate setting means 25 and the range of the dead zone set by the dead zone setting means 31 are controlled according to the situation. By setting each to a good value, control emphasizing controllability can be realized.

Next, a case in which the switch life setting mode is set by the switching setting means 24 will be described. When the potentio life emphasis mode is set, the manipulated variable change rate limit value calculated by the manipulated variable change rate calculation means 27 using the above-described arithmetic expression is used as the manipulated variable change rate limit means 29.
Output to Further, the range of the dead zone calculated by the above-mentioned equation by the dead zone calculating means 32 is equal to the position proportional control means 34.
Output to The operation amount change rate limit value is calculated by the full open time setting means 26 using the full open time and the update cycle set by an operator using a key switch (not shown) provided on the control device 1. At this time, since the adjustment result based on the calculation has an error, the adjustment result is multiplied by a safety coefficient which is a fixed value. The result is prevented from being reduced.

The limitation of the rate of change of the first manipulated variable by the manipulated variable rate-of-change limit value obtained by the above-mentioned equation is based on the following knowledge. That is, even if the first operation amount output from the PID control means 23 greatly changes, the operation from the fully closed state to the fully opened state of the motor 3 cannot follow the change in the first operation amount, and it takes time. Even if the first operation amount changes more than the opening / closing speed of the valve 4 due to the operation of the motor 3, the motor 3 cannot follow.
Therefore, the first operation amount may be changed and increased / decreased by an operation width per one update cycle of the motor 3. For this reason, the change of the first operation amount is changed per one update cycle of the motor 3. Limit the change to the movement width.

The manipulated variable rate-of-change limiting means 29 limits the rate of change of the first manipulated variable by the manipulated variable rate-of-change limit value calculated in this manner, and sends the second manipulated variable to the position proportional control means 34 as a second manipulated variable. Output. The position proportional control means 34 controls the operation based on the second operation amount and the motor feedback amount with the control characteristic in which the range of the dead zone calculated on the basis of the calculation expression by the dead zone calculation means 32 is set. A command is generated and output to the motor 3.

FIG. 5 shows an example of the control characteristics of the position proportional control means 34 when the potentiometer life emphasis mode is set by the switch setting means 24. In FIG. 5, the dead zone set by the dead zone calculation means 32 is shown. The range is calculated from the manipulated variable change rate limit value calculated by the manipulated variable change rate calculating means 27, and the first manipulated variable continuously takes a value larger in one direction than the current value for four update cycles. In this case, the range in which the operation command is output, that is, eight times the operation amount change rate limit value calculated by the operation amount change rate calculation unit 27 is set as the dead zone. However, if the range of the dead zone is too wide, control becomes impossible.
It was defined in the range corresponding to 0%. Therefore, depending on the operation amount change rate limit value calculated by the operation amount change rate calculation means 27, an operation command is output to the motor 3 in two update cycles at the worst, and the motor 3 is driven.

FIG. 5A shows a state in which the first operation amount, the second operation amount, and the motor feedback amount match. In this case, the position proportional control means 34 does not output an operation command. .

FIG. 5B shows a state after one update cycle in which the first manipulated variable greatly changes in the state of FIG. 5A. In this case, the second manipulated variable output to the position proportional control means 34 does not follow the change of the first manipulated variable, and as shown as an example in FIG. The operation amount MV limited by the calculated operation amount change rate limit value
_1T . Further, the motor feedback amount at this time is shown as the motor feedback amount after the one update cycle when the driving of the motor 3 is started by the greatly changed first operation amount.

FIG. 5 (c) shows a state after one update cycle (second update cycle) from the state of FIG. 5 (b). In this case, as shown in FIG. 3, the second operation amount output to the position proportional control means 34 is the second update period limited by the operation amount change rate limit value calculated by the operation amount change rate calculation means 27. The manipulated _variable MV is _2T (2T). In addition, the motor feedback amount at this time indicates the motor feedback amount in the second update cycle when the driving of the motor 3 is started by the greatly changed first operation amount.

FIG. 5D shows the state after one update cycle (third update cycle) from the state of FIG. 5C. In this case, as shown in FIG. 3, the second operation amount output to the position proportional control means 34 is the third update period limited by the operation amount change rate limit value calculated by the operation amount change rate calculation means 27. The operation amount MV _3T is (3T). Further, the motor feedback amount at this time indicates the motor feedback amount in the third update cycle when the driving of the motor 3 is started by the greatly changed first operation amount.

FIG. 5E shows the state after one update cycle (fourth update cycle) from the state of FIG. 5D. In this case, the second manipulated variable output to the position proportional control means 34 is, as shown in FIG. 3, the fourth update period limited by the manipulated variable change rate limit value calculated by the manipulated variable change rate calculating means 27. The operation amount MV is _4T (4T). In addition, the motor feedback amount at this time indicates the motor feedback amount in the fourth update cycle when the driving of the motor 3 is started by the greatly changed first operation amount. At this time, as described above, the range of the dead zone set by the dead zone calculation means 32 depends on the operation amount change rate calculation means 2.
The operation command is output when the first operation amount continuously increases in one direction from the current value for four update cycles calculated from the operation amount change rate limit value calculated in step 7. Therefore, the operation amount MV _{4T in} the fourth update cycle (4T)> the threshold value of the operation command of the open command is satisfied, and the position proportional control means 34 outputs the operation command of the open command.

That is, 8 which defines the range of the dead zone
Even if the amount of operation temporarily fluctuates within the update cycle due to, for example, a change in environment or noise, no operation command is output from the position proportional control means 34, and the number of times the motor 3 is driven is suppressed. It is possible to extend the service life of the components including.

As described above, since the operation amount change rate is determined based on the actual full opening time of the valve 4, the change amount of the operation amount per one update cycle becomes clear, and the change of the second operation amount is determined. The change in the actual valve opening can be followed. In addition, the dead zone is also set based on the determined operation amount change rate, so that it can be set in a range corresponding to the actual change in the valve opening. As a result, the number of scans at which no operation command is output can be predicted, and the operation amount change rate and the dead zone corresponding to the change in the control amount output from the control target 2 due to environmental changes, noise, and the like in the control target 2 are respectively determined. It can be set to the optimal value corresponding to the actual valve and the motor that drives the valve at the site of
It is possible to extend the life of components including the potentiometer provided in the motor 3 and to obtain a control device capable of realizing control according to the characteristics of the control target 2.

Embodiment 2 In the first embodiment, the first operation amount output from the PID control means 23 is limited by the operation amount change rate limit value calculated by the operation amount change rate calculation means 27. Although the range of the dead zone of the position proportional control means 34 is set based on the value, the operation result of the operation command output to the motor 3 is not calculated every update cycle, but only at a constant cycle longer than the update cycle. A configuration in which output is not performed may be adopted. Further, a configuration may be employed in which the PID operation amount passed to the calculation result of the output driver portion of the time proportional output that outputs the operation command to the motor 3 in the position proportional control means 34 is not updated for a certain period. Further, the PID operation amount passed to the calculation result of the output driver portion of the time proportional output for outputting the operation command to the motor 3 in the position proportional control means 34 may be filtered. Further, in the case where the same command in the opening direction or the closing direction is continuously output as the operation command a certain number of times in the position proportional control means 34, the opening command and the closing command are used, and the stop command may be immediately executed. . Alternatively, two or more of the above configurations may be combined, and similar effects can be expected.

[0036]

As described above, according to the present invention, the manipulated variable calculating means for outputting the first manipulated variable based on the control variable and the set value, and the second control output from the manipulated variable calculating means. The operation amount change rate limiting means for limiting the change rate of the first operation amount to a predetermined operation amount change rate or less based on the operation amount change rate limit value and outputting the second operation amount as a second operation amount; A dead zone in which no command is output is set, and the operation is performed based on the second operation amount output from the operation amount change rate limiting unit and a feedback amount indicating a valve opening of a valve driven by the driving unit. Since the apparatus is provided with the position proportional control means for outputting a command, the rate of change of the second manipulated variable can be suppressed to a value equal to or less than the rate of change of the first manipulated variable. Output from the controlled object due to the influence of The frequency of the output of the operation command can be suppressed with respect to the fluctuations that occur in the device, and the life of components including a detection device for extracting the feedback amount attached to the drive unit and a relay for outputting the operation command can be extended. In addition, there is an effect that control according to the characteristics of the control target can be realized.

According to the present invention, the operation amount change rate limiting means shifts the operation amount change rate limit value when the first operation amount is limited between the fully closed state and the fully opened state of the valve. Operating amount change rate calculating means for calculating and outputting based on the full opening time required for the operation, and a range of a dead zone of the position proportional control means based on the operating amount change rate limit value calculated by the operating amount change rate calculating means. And the dead zone calculation means for setting the second operation amount can be made to follow the change in the actual valve opening degree. It can be set to a corresponding width, which allows the prediction of the number of update cycles at which the operation command is not output, so that the actual valve opening degree can be controlled against fluctuations in the control amount output from the control target due to environmental changes and noise. Optimal for changes The sensing zone can be set, the frequency at which the operation command is output can be suppressed, and the life of components including a detection device for extracting a feedback amount attached to the drive unit and a relay for outputting the operation command can be extended. In addition, there is an effect that control according to the characteristics of the control target can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control device in the control system according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of a relationship between a first operation amount and a second operation amount in the control system according to the first embodiment of the present invention;

FIG. 4 is a control characteristic diagram of the position proportional control means when a controllability-oriented mode is selected in the control system according to the first embodiment of the present invention;

FIG. 5 is a control characteristic diagram of the position proportional control means when the potentio life emphasis mode is selected in the control system according to the first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional control system.

FIG. 7 is a block diagram showing a configuration of a control device in a conventional control system.

FIG. 8 is a control characteristic diagram of a position proportional control means of a control device in a conventional control system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control apparatus 2 Control object 3 Motor (drive means) 4 Valve 22 Computing device (Operation amount operation means) 23 PID control means (Operation amount operation means) 27 Operation amount change rate operation means 29 Operation amount change rate restriction means 32 Dead zone operation Means 34 Position proportional control means

Claims (2)

[Claims] 1. A control device that outputs an operation command to a driving unit so that a control amount of a control target coincides with a set value, and controls a valve opening of a valve driven by the driving unit. An operation amount calculation unit that outputs a first operation amount based on the set value, and a change rate of the first operation amount output from the operation amount calculation unit based on the operation amount change rate limit value. An operation amount change rate limiting unit that limits the operation amount to a predetermined amount or less and outputs the second operation amount, and a dead zone that does not output an operation command to the driving unit is set. Position proportional control means for outputting the operation command based on the output second operation amount and a feedback amount indicating a valve opening of the valve driven by the driving means. Control device. 2. An operation amount change rate limiting value when the operation amount change rate limiting means limits the first operation amount is set to a full opening required for the valve opening degree of the valve to move between fully closed and fully open. An operation amount change rate calculating means for calculating and outputting based on time; and a dead zone for setting a range of a dead zone of the position proportional control means based on the operation amount change rate limit value calculated by the operation amount change rate calculation means. The control device according to claim 1, further comprising a calculation unit.