JP2014174585A - Control device and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device and a control method which can achieve both the suppression of overshoot or undershoot and the improvement in responsiveness without applying a load to a mechanical structure part relating to the drive of a valve.SOLUTION: A control device which controls a valve for adjusting a flow rate of fluid includes: an opening acquirement section acquiring the opening of the valve or the predicted opening of the valve after a predetermined time; a determination section determining whether or not the opening or the predicted opening fulfills a breaking condition for breaking the control of the valve; and a correction section correcting the amount of operation for changing the opening by driving the valve, which is calculated from a predetermined control law, with a correction value calculated from a predetermined proportional control law, when it is determined that the opening or the predicted opening fulfills the breaking condition.

Description

  The present invention relates to a control device and a control method for controlling a valve for adjusting the flow rate of a fluid such as gas or liquid.

  A technique for electronically controlling a valve for adjusting the flow rate of a fluid such as gas or liquid by feedback control such as PID (Proportional Integral Derivative) control is known. An example of a valve to be controlled by this technique is a cooling water valve. Conventionally, in the control of the cooling water valve, there has been a problem that when the response is increased by adjusting the gain of the feedback control side rule, overshoot and undershoot gradually occur.

  In order to solve such a problem, in the control of the cooling water temperature of the internal combustion engine by the discharge amount of the electric water pump, the absolute value of the control deviation between the target water temperature and the measured water temperature is equal to or less than the threshold A, and the absolute change in the speed of the water temperature is absolute. When the value is greater than or equal to the threshold value B, a technique is known for controlling the flow rate of cooling water, calculating a corrected flow rate, and adding this corrected control flow rate to the flow rate calculated by the basic control law to suppress overshoot. (For example, refer to Patent Document 1).

  In addition, as a related technique, a technique is known in which driving is performed at high torque and braking is performed when a motor approaches a target position (see, for example, Patent Document 2).

JP 2010-190142 A JP 2000-333482 A

  However, when the techniques described in Patent Document 1 and Patent Document 2 described above are applied to control of the flow rate using a rotary valve, problems arise.

  For example, when controlling the cooling water temperature by control using a rotary valve, temperature control is performed based on the target temperature and measured temperature of the cooling water, and the opening of the rotary valve is controlled based on the target flow rate calculated in this temperature control. Calculate and perform valve control based on this opening. In such a control, for example, when the engine temperature is controlled by controlling the cooling water temperature, the sample period of the temperature control requires about 1 second, so the sample period of the valve control needs to be less than that. In response to such a requirement, the correction in the technique described in Patent Document 1 is a PI control in which a preceding differential control law is added in the vicinity of the target temperature, and therefore, the motor for driving the rotary valve in the valve control is corrected. There arises a problem that the responsiveness of the angle control is deteriorated.

  Further, when using a rotary valve having a large gear ratio compared to ETB (Electric Throttle Body) (for example, ETB is 1:21 and valve is 1: 120), the technique described in Patent Document 2 is used. When valve control is performed such that the valve is activated by a large current and brakes are applied, there is a problem that a load is applied to a mechanical structure part for driving a rotary valve such as a gear.

  The present invention has been made to solve the above-described problems, and achieves both suppression of overshoot or undershoot and improvement of responsiveness without imposing a burden on the mechanical structure part for driving the valve. An object of the present invention is to provide a control device and a control method capable of performing the above.

  In order to solve the above-described problem, one aspect of the present invention is a control device that controls a valve for adjusting the flow rate of a fluid, and the opening degree of the valve or a predicted opening degree after a predetermined time of the valve is determined. An opening degree acquisition unit to be acquired, a determination unit that determines whether or not the opening degree or the predicted opening degree satisfies a braking condition for braking the control of the valve; and the opening degree or the predicted opening degree Is determined to satisfy the braking condition, the operation amount for driving the valve and changing the opening calculated by a predetermined control law is corrected with a correction value calculated by a predetermined proportional control law. A correction unit.

  Another embodiment of the present invention is a control method performed by a control device that controls a valve for adjusting a flow rate of a fluid, wherein the control device predicts an opening degree of the valve or a predetermined time after the valve. An opening degree is acquired, and it is determined whether the opening degree or the predicted opening degree satisfies a braking condition for braking the control of the valve, and the opening degree or the predicted opening degree satisfies the braking condition. When it is determined that the value is satisfied, the operation amount for driving the valve calculated by a predetermined control law and changing the opening is corrected by a correction value calculated by a predetermined proportional control law.

  According to the present invention, it is possible to achieve both suppression of overshoot or undershoot and improvement of responsiveness without imposing a burden on a mechanical structure part related to driving of the valve.

It is a mimetic diagram showing an engine cooling system concerning this embodiment. It is a block diagram which shows the hardware constitutions of ECU. It is a functional block diagram which shows the function structure of ECU. It is a flowchart which shows the operation amount calculation process which concerns on this Embodiment. It is a schematic diagram for demonstrating a 1st calculation process and a 2nd calculation process. It is a schematic diagram for demonstrating a 1st calculation process and a 2nd calculation process. It is a flowchart which shows another form of the operation amount calculation process which concerns on this Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, the case where the present invention is applied to a control device that controls a cooling water control valve used in an engine cooling system that cools an engine of an automobile or the like with cooling water will be described as an example. However, the present invention is not limited to this, and the present invention can be applied to any system that electronically controls the flow rate of liquid or gas using a valve.

  First, the engine cooling system according to the present embodiment will be described. FIG. 1 is a schematic diagram showing an engine cooling system according to the present embodiment.

  As shown in FIG. 1, the engine cooling system 1 according to the present embodiment includes an engine 11, a water jacket 12, a water pump 13, a cooling water valve 21, a motor 22, a position sensor 23, water temperature sensors 24a and 24b, an ECU ( (Engine Control Unit) 31, a radiator 41, a heater 42, a throttle 43, a main passage pipe 91, a sub passage pipe 92, and a bypass passage pipe 93.

  The engine cooling system 1 circulates cooling water through the main flow path pipe 91, the sub flow path pipe 92, or the bypass flow path pipe 93, and controls the temperature of the engine 11 by the water jacket 12.

  The engine 11 is an internal combustion engine of a vehicle such as an automobile. The water jacket 12 is provided in the vicinity of the engine 11 and cools the engine 11 with cooling water therein. The main flow path pipe 91 allows cooling water to flow into the radiator 41. The sub passage pipe 92 allows cooling water to flow into the heater 42 and the throttle 43. The bypass flow path pipe 93 allows the cooling water flowing out from the water jacket 12 to flow into the water pump 13. The cooling water that has flowed into the radiator 41, the heater 42, and the throttle 43 flows into the water pump 13. The water pump 13 allows cooling water to flow into the water jacket 12. The radiator 41 cools the cooling water. The heater 42 warms the passenger compartment. The throttle 43 controls the amount of intake air flowing into the engine 11.

  The cooling water valve 21 is a rotary valve for adjusting the flow rate of the fluid (cooling water), and an opening is provided in a part of the outer peripheral surface. Cooling water is allowed to flow into the pipe 92. The motor 22 is a DC motor as an actuator that drives the cooling water valve 21. The position sensor 23 detects the opening degree of the cooling water valve 21 relative to the main flow path pipe 91 and the sub flow path pipe 92 by detecting the circumferential position of the cooling water valve 21. The water temperature sensors 24a and 24b detect the temperature of the cooling water. The ECU 31 is a microcontroller that controls various operations related to the engine 11. In the present embodiment, the ECU 31 will be described below as a valve controller that operates the operation of the motor 22.

  With the configuration as described above, the cooling water is cooled by the radiator 41 by being circulated through the main flow path pipe 91, and is circulated without being cooled when it is routed through the bypass flow path pipe 93. Further, the engine cooling system 1 controls the temperature of the engine 11 by switching the cooling water circulation path according to the opening degree of the cooling water valve 21 and controlling the amount of cooling water flowing into the main passage pipe 91. .

  Next, the hardware configuration of the ECU will be described. FIG. 2 is a block diagram illustrating a hardware configuration of the ECU.

  As shown in FIG. 2, the ECU 31 includes a CPU (Central Processing Unit) 311, a memory 312, and an input / output interface 313. The ECU 31 performs processing related to the control of the cooling water valve 21 in cooperation with the CPU 311, the memory 312, and the input / output interface 313. Specifically, information detected by various sensors such as the position sensor 23 and the water temperature sensors 24a and 24b is acquired via the input / output interface 313. Examples of the information to be acquired include the rotational speed of the engine 11, the manifold pressure, the cooling water temperature of the radiator 41, the target water temperature of the water jacket 12 as a target required from the host device, and the actual water temperature of the water jacket 12. Note that the rotational speed of the engine 11 and the manifold pressure may be stored in advance in the memory 312 or the like. Based on these acquisition results, a required amount of cooling water for obtaining the required target water temperature is calculated, and a target opening degree of the valve 21 that achieves this required amount of cooling water is calculated. In order to guide the opening degree of the cooling water valve 21 to the target opening degree, an operation amount of the motor 22 is calculated by an operation amount calculation process described later, and a signal corresponding to the operation amount of the motor 22 is input via the input / output interface 313. Is output to the drive circuit 25. The drive circuit 25 is a PWM circuit that controls the motor 22 by PWM (Pulse Width Modulation), and drives the motor 22 by changing the duty ratio of the pulse width according to the magnitude of the input signal.

  In the present embodiment, the movable range of the cooling water valve 21 is 190 °, and the resolution for driving the motor 22 is 240. Therefore, in the present embodiment, the opening degree of the cooling water valve 21 is controlled in units of 0.344 degrees. In addition, when the operation amount is increased in the positive direction, the cooling water valve 21 is controlled in the opening direction. In addition, the cooling water valve 21 is controlled at a predetermined sampling period.

  Next, in order to facilitate understanding of the present embodiment, an outline of the operation amount calculation process described above will be briefly described. In the manipulated variable calculation process according to the present embodiment, the predicted opening degree (for example, the opening degree of the cooling water valve 21 at the time of the next sample) that is the opening degree after a predetermined time of the cooling water valve 21 is determined to be close to the target opening degree. In this case, the configuration of the current control law for calculating the operation amount for changing the opening degree by driving the cooling water valve 21 by the motor 22 is switched from the position type to the speed type. This switching from the position type to the speed type adds a proportional control law (proportional control calculation) and a differential control law (differential control calculation) to the current control law, that is, controls the cooling water valve 21 by P gain + D gain. This is done by braking the More specifically, the operation amount calculated by the current control law is corrected by the correction value calculated by the proportional control law and the correction value calculated by the differential control law. In the present embodiment, the operation amount to be corrected will be described below as being input to the drive circuit 25. Such an operation amount calculation process is realized by each function of the ECU 31.

  Next, the functional configuration of the ECU 31 will be described. FIG. 3 is a functional block diagram showing a functional configuration of the ECU. As shown in FIG. 3, the ECU 31 includes an information acquisition unit 101, an angle calculation unit 102, a determination processing unit 103, and an operation amount correction unit 104 as functions. Note that these functions are realized by the cooperation of hardware resources such as the CPU 311 and the memory 312 described above.

  The information acquisition unit 101 acquires various types of information related to the operation amount calculation process. For example, the actual opening of the cooling water valve 21 of the current sample detected by the position sensor 23, the driving direction of the cooling water valve 21 ( Open direction or closed direction). The driving direction is determined by the change in the opening degree of the cooling water valve 21 and obtained. For example, the direction is calculated from the actual opening of the current sample and the actual opening of the previous sample. In addition, you may make it acquire what was detected by the sensor which is not shown in figure. In addition, the information acquisition unit 101 is a target opening degree set based on the above-described required cooling water amount and a coefficient for braking the drive control of the cooling water valve 21, and the actual opening degree with respect to the target opening degree Get the braking factor, which is a percentage. In the present embodiment, it is assumed that the braking coefficient is stored in a nonvolatile storage medium such as a ROM (Read Only Memory) (not shown).

  The angle calculation unit 102 calculates a braking start opening based on the actual opening, the target opening, and the braking coefficient acquired by the information acquisition unit 101. The braking start opening is a threshold value indicating an opening that serves as a guide for starting to apply braking to the drive control of the cooling water valve 21.

  The determination processing unit 103 performs various determinations related to the operation amount calculation process, calculation of the predicted opening, and creation of a braking condition based on the braking start opening and the driving direction. As various determinations, it is determined whether the actual opening or the predicted opening satisfies the braking condition or whether the target opening is changed. The predicted opening is calculated based on the actual opening. In addition, it may be calculated from the actual opening and the operation amount calculated by the current control law, or from the actual opening of the current sample and the actual opening of the previous sample according to the rate of increase / decrease, etc. It suffices if the actual opening at the time of sampling can be calculated. The braking condition to be created is a condition for braking the control of the cooling water valve 21. In the present embodiment, when the driving direction is the open direction, the predicted opening is equal to or greater than the braking start opening, and the target Less than the opening is the braking condition. On the other hand, when the drive direction is the closing direction, the predicted opening exceeds the target opening, and the braking start opening or less is the braking condition.

  When it is determined that the predicted opening degree satisfies the braking condition, the operation amount correcting unit 104 drives the cooling water valve 21 calculated by a predetermined control law to change the operation amount for changing the actual opening amount to a predetermined amount. The correction value calculated by the proportional control law and the correction value calculated by the predetermined differential control law are corrected by a correction value. Further, the operation amount correction unit 104 filters the correction value calculated by the proportional control law calculation using a predetermined first-order lag element.

  Next, details of the operation amount calculation processing by the ECU 31 will be described. FIG. 4 is a flowchart showing an operation amount calculation process according to the present embodiment. The manipulated variable calculation process in the present embodiment is executed for each sample until the cooling water valve 21 is fully closed after a learning time after an unillustrated ignition key switch is turned off (so-called Key Off). Continued execution. Further, the operation amount calculation process is executed with the target opening degree set as a trigger.

  First, as shown in FIG. 4, the information acquisition unit 101 acquires an actual opening, a target opening, a braking coefficient, and a driving direction (S101). After acquisition, the angle calculation unit 102 calculates the braking start opening based on the actual opening, the target opening, and the braking coefficient (S102). As a method of calculating the braking start opening, it is preferable to calculate by adding the actual opening to the multiplication result obtained by multiplying the control deviation between the target opening and the actual opening by a braking coefficient. The braking coefficient is preferably 90%. This calculated braking start opening is held until the target opening is changed.

  After the calculation, the determination processing unit 103 determines whether there is a change in the target opening degree (S103). When there is a change in the target opening (S103, YES), the angle calculation unit 102 updates the previously held braking start opening with the braking start opening calculated in step S102 (S104), and in step S105 The process proceeds to a process for creating a braking condition. Note that if there is no braking start opening held in advance at the time of the first sample or the like, the braking start opening calculated in step S102 is simply selected. On the other hand, when there is no change in the target opening degree (S103, NO), the held braking start opening degree is selected, and the process proceeds to the process of creating the braking condition in step S105.

  As described above, the function of maintaining the braking start opening degree is realized by inputting an output signal indicating the braking start opening degree into an element such as an enabled subsystem. When the braking start opening is held by an element such as the enabled subsystem, for example, when the enable signal input is other than 0, the output is the same as the input signal. That is, the calculated braking start opening is output. On the other hand, when the enable signal is 0, the input in a state other than 0 is held, and the held brake start opening is output, thereby realizing the above-described processing. Note that reset may be performed when the enable signal is 0.

  Next, the determination processing unit 103 calculates a predicted opening based on the actual opening, and creates a braking condition based on the braking start opening and the driving direction when the target opening is changed (S105). . For example, when the driving direction acquired by the information acquisition unit 101 is the open direction, the determination processing unit 103 sets the predicted opening degree to a braking condition that is greater than or equal to the braking start opening degree and less than the target opening degree. On the other hand, when the driving direction is the closing direction, the predicted opening exceeds the target opening, and the braking start opening or less is set as a braking condition.

  The braking condition is not limited to this, and the braking condition may include that the cooling water valve 21 is in a transient state. For example, when the driving direction is the open direction, the braking condition is that the predicted opening is equal to or greater than the braking start opening and is in a transient state. On the other hand, when the drive direction is the closing direction, the braking condition is that the predicted opening is equal to or less than the braking start opening and is in a transient state. Whether it is a transient state or a steady state is a process that can determine whether it is a steady state or a transient state, such as determination of whether or not the control deviation is 0, and the absolute value of the control deviation is within 3 LSB. Anything can be used.

  In this braking condition creation process, if the target opening is not changed, there is a braking condition created based on the past target opening, and this is selected. The braking condition may be created again based on the target opening that has not been changed.

  After creating the braking condition, the determination processing unit 103 determines whether or not the predicted opening degree satisfies the braking condition (S106). After the determination, the operation amount correction unit 104 performs a process for calculating a correction value (S107). This process is a process of performing so-called proportional control law calculation and differential control law calculation based on the deviation between the target opening and the actual opening, and adding these calculation results. After calculating the correction value, the determination processing unit 103 receives the determination result of the braking condition determination in step S106, and determines whether or not the predicted opening satisfies the braking condition (S108). When the braking condition is not satisfied (S108, NO), the operation amount correction unit 104 calculates the operation amount by performing the first calculation process, and gives it to the drive circuit 25 (S109). The first calculation process calculates an operation amount by the current control law. For example, the operation quantity is calculated by a general feedback control law calculation based on a deviation between the actual opening degree and the target opening degree.

  On the other hand, when the braking condition is satisfied (S108, YES), the operation amount correction unit 104 calculates the operation amount by performing the second calculation process, and provides the operation amount to the drive circuit 25 (S110). The second calculation process is a process of adding the calculation result of the correction value in step S108 to the calculation result based on the current control law. As a result, the operation amount calculated by the current control law can be corrected by the correction value calculated by the proportional control law and the correction value calculated by the differential control law, and the control of the cooling water valve 21 is braked. It becomes possible. After the first calculation process or the second calculation process, the target is shifted to the next sample (S111), the control information acquisition process in step S101 is performed again, and this flow is repeated for each sample.

  Here, the concept of processing executed in steps S108 to S110 will be described with reference to the drawings. 5 and 6 are schematic diagrams for explaining the first calculation process and the second calculation process. Note that eVOSD shown in FIG. 5 indicates a deviation between the target opening and the actual opening, and 51 indicates a proportional control law. Reference numeral 52 denotes a differential control law, 53 denotes a determination as to whether or not the braking condition is satisfied, and 54 denotes a current control law.

  As shown in FIG. 5, based on the deviation eVOSD, each calculation by the proportional control law 51 and the differential control law 52 is performed, and the respective results are added. After that, whether the added correction value is output or 0 is output (that is, the braking control is 0) is switched based on the result of whether or not the braking condition is satisfied. Here, gainC indicates that the target opening is (or is in a steady state), and getTarget indicates that the predicted opening is greater than or equal to the braking start opening or less than or equal to the braking start opening. That is, these are the results of the brake condition determination in step S107. The output switches according to these values. For example, if it is the target opening and the predicted opening is greater than or equal to the braking start opening (when the drive direction is the open direction), 1 is added to each AND element, and the switch is set so that a correction value is output. Switch. Note that the values such as gain shown in FIG. 5 are merely examples, and the present invention is not limited thereto.

  As shown in FIG. 6, the correction value calculated in this way is subjected to a feedback control law calculation based on the deviation between the target opening and the actual opening, and the result is corrected by the correction value. On the other hand, if the braking condition is not satisfied, the braking control 0 (stop signal) is output as a correction value as shown in FIG. 5, so that the operation amount is calculated only by the current control law. .

  Here, in FIG. 5, in the proportional control law calculation, the value calculated by the proportional control law calculation is filtered using a 1st Order Discrete Filter (first-order lag filter), but this element is excluded. Even if configured, the above-described effects can be achieved. Similarly, although the differential control law calculation is added, it may be added depending on the situation, and even if it is removed, the above-described effects can be obtained.

  According to the present embodiment, since P or PD control as braking is added to the control law, braking is applied even if the control gain is increased, so that overshoot and undershoot can be suppressed and response is improved (response time) Effect). Compared with so-called brake control in which a reverse current is applied to the motor, the burden on the mechanical structure can be reduced, and only a proportional gain (or proportional gain + derivative gain) is added. Can be realized. Furthermore, the learning time after Key Off and the tact time during setting / inspection during mass production can be shortened.

  Note that the order of processing executed at each step in the operation amount calculation processing shown in FIG. 4 is not limited to this, and may be changed as appropriate. For example, although it has been described that various determinations are performed after the calculation of the braking start opening degree and the correction value, these calculations may be performed after various determinations.

  FIG. 7 is a flowchart showing another form of the operation amount calculation process according to the present embodiment. As shown in FIG. 7, after the control information acquisition process in step S <b> 101, it is determined whether or not there is a change in the target opening degree in step S <b> 103. If there is a change in the target opening degree (S103, YES), the braking start opening degree calculation in step S102 and the braking start opening degree update in step S104 are performed, and the process proceeds to the brake condition creation process in step S105. On the other hand, if there is no change in the target opening degree (S103, NO), the held braking start opening degree is selected (S112), and the process proceeds to the braking condition creation process in step S105.

  After the creation, the braking condition is created in step S105, and the braking condition is judged in step S106. Next, it is determined whether or not the predicted opening degree satisfies the braking condition in step S108. If not satisfied (S108, NO), the first calculation process in step S109 is performed. On the other hand, if it is satisfied (S108, YES), calculation of the correction value in step S107 and second calculation processing in step S110 are performed. As described above, if the calculation of the braking start opening degree and the calculation of the correction value are performed before various determinations, the non-use of the calculation results caused by the determination results can be avoided, and the load on the ECU 31 can be reduced.

  In the present embodiment, the predicted opening is described as the target of the braking condition, but the present invention is not limited to this, and the actual opening may be the target. In such a case, correction (for example, 80%) is performed to reduce the braking coefficient, and if the driving direction is the open direction, the braking start opening is lowered, and if the driving direction is the closing direction, the braking start opening is increased.

  The present invention can be implemented in various other forms without departing from the gist or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is shown by the scope of claims, and is not restricted by the text of the specification. Moreover, all modifications, various improvements, substitutions and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

  Note that the control device described in the claims corresponds to, for example, the ECU 31 in the above-described embodiment. Further, the opening degree acquisition unit and the direction acquisition unit correspond to, for example, the information acquisition unit 101, and the calculation unit corresponds to, for example, the angle calculation unit 102. The determination unit corresponds to, for example, the condition determination unit 103, and the correction unit corresponds to, for example, the operation amount correction unit 104. The primary delay element corresponds to, for example, a primary delay filter, and the start opening corresponds to, for example, a braking start opening.

  DESCRIPTION OF SYMBOLS 1 Engine cooling system, 11 Engine, 12 Water jacket, 13 Water pump, 21 Cooling water valve, 22 Motor, 23 Position sensor, 24a, 24c Water temperature sensor, 31 ECU, 41 Radiator, 42 Heater, 43 Throttle, 51 Proportional control law , 52 differential control law, 53 determination whether or not the braking condition is satisfied, 91 main flow pipe, 92 sub flow pipe, 93 bypass flow pipe, 101 information acquisition unit, 102 angle acquisition unit, 103 determination processing unit, 104 Operation amount calculation unit, 311 CPU, 312 memory, 313 input / output interface.

Claims (7)

A control device for controlling a valve for adjusting a flow rate of fluid,
An opening degree obtaining unit for obtaining an opening degree of the valve or a predicted opening degree after a predetermined time of the valve;
A determination unit that determines whether the opening degree or the predicted opening degree satisfies a braking condition for braking the control of the valve;
When it is determined that the opening degree or the predicted opening degree satisfies the braking condition, an operation amount for driving the valve and changing the opening degree calculated by a predetermined control law is set to a predetermined proportional control law. And a correction unit that corrects with the correction value calculated by the control unit. The correction unit, when it is determined that the opening degree or the predicted opening degree satisfies the braking condition, a correction value calculated by the proportional control law and a correction value calculated by a predetermined differential control law. The control device according to claim 1, wherein the operation amount is corrected with a combined correction value. 3. The correction unit according to claim 1, wherein the correction unit filters the correction value calculated by the proportional control law using a predetermined first-order lag element, and corrects the operation amount with a value obtained by the filtering. Control device. Based on the opening, a preset target opening, and a ratio of the opening to the target opening, a calculation unit that calculates a starting opening for starting braking the control of the valve;
A direction acquisition unit for acquiring a driving direction of the valve;
The determination unit creates the braking condition based on the start opening and the drive direction, the drive direction is an open direction, and the opening or the predicted opening is equal to or greater than the start opening, and the target When the opening is less than the opening, or when the driving direction is the closing direction and the opening or the predicted opening exceeds the target opening and is equal to or less than the start opening, the opening is the braking condition. The control device according to any one of claims 1 to 3, wherein the control device is determined to satisfy. The control device according to claim 4, wherein the start opening is a value obtained by multiplying a difference between the target opening and the opening by the ratio, and adding the opening to a result of the multiplication. The start opening is held in the storage unit until the target opening is changed,
The said calculation part updates the start opening degree hold | maintained at the said memory | storage part by the start opening degree calculated based on this target opening degree when the said target opening degree is changed. Control device. A control method performed by a control device that controls a valve for adjusting a flow rate of a fluid,
The control device is
Obtain the opening degree of the valve or the predicted opening degree after a predetermined time of the valve,
Determining whether or not the opening or the predicted opening satisfies a braking condition for braking the control of the valve;
When it is determined that the opening degree or the predicted opening degree satisfies the braking condition, an operation amount for driving the valve and changing the opening degree calculated by a predetermined control law is set to a predetermined proportional control law. A control method that corrects with the correction value calculated by.

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