Device and method for accurately controlling the flow of a variable pump

Abstract

The present invention relates to the field of engineering process control, and specifically to a device and method for accurately controlling the flow of a variable pump. The invention solves the technical problem that the flow control precision of the variable pump used in existing industrial production is not high, and when the direction of the increase or decrease of the control flow changes, there is a time gap, and the flow cannot be controlled during this period. A device for accurately controlling the flow of a variable pump includes a host computer, a board, a wiring board, a plurality of control switches, DC relays KM1, KM2, a DC power supply, a DC servo motor, a controlled device and a wiring terminal. The device can control the device to slowly and stably adjust the flow at a certain speed in a certain pulse time period. When the flow increase or decrease changes, it can switch quickly and flexibly to eliminate the waiting time and ensure that the flow is within the control range.

Description

Technical Field

[0001] The invention relates to the field of engineering process control, and in particular to a device and method for accurately controlling the flow of a variable pump. Background Art

[0002] Variable pumps are needed in the field of industrial production, and the flow of variable pumps needs to be accurately controlled. The current method of controlling flow cannot be accurately controlled and there is instability after adjustment. In addition, when the direction of the increase or decrease of the controlled flow changes, there is a time gap, and the flow cannot be controlled during this time. Therefore, it is necessary to design a device and method for accurately controlling the flow of variable pumps to accurately and stably control the flow of variable pumps. Summary of the invention

[0003] In order to solve the technical problems that the flow control precision of the existing variable pump for industrial production is not high and there is a time gap when the increase or decrease direction of the controlled flow changes, and the flow cannot be controlled during this period, the present invention proposes a device and method for accurately controlling the flow of a variable pump.

[0004] The device for accurately controlling the flow of a variable pump described in the present invention is implemented by adopting the following technical scheme: a device for accurately controlling the flow of a variable pump, comprising a host computer, a board, a wiring board, a plurality of control switches, DC relays KM1, KM2, a DC power supply, a DC servo motor, a controlled device and a wiring terminal; the host computer and the board communicate bidirectionally, the board is connected to the wiring board, and the plurality of control switches are connected in parallel with each other; one end of the plurality of control switches is connected to the positive electrode of the DC power supply, and the other end of the plurality of control switches is connected to the wiring board through the wiring terminal; the negative electrode of the DC power supply is connected to the wiring board through the wiring terminal; the DC servo motor is connected to the flow control end of the controlled device; the flow of the controlled device is fed back to the board through the flow meter;

[0005] The servo motor is connected between the positive and negative poles of the DC power supply through the normally open contact of the relay KM1, and the servo motor is connected between the positive and negative poles of the DC power supply through the normally open contact of the relay KM2; the main coils of the relays KM1 and KM2 are connected in parallel with one end connected to the positive pole of the DC power supply, and the other end connected to the wiring board through the wiring terminal;

[0006] The multiple control switches are divided into two groups: manual control mode switches and automatic control mode switches. There are two manual control mode switches, which respectively control the on and off of the main coils of relays KM1 and KM2 through the board card; there are multiple automatic control mode switches, each automatic control mode switch corresponds to a flow control mode, and the board card controls the on and off of relays KM1 and KM2 under different flow control modes; the manual control mode switch and the automatic control mode switch also send manual control mode signals and automatic control mode signals to the host computer through the board card; by controlling the power on and off of relays KM1 and KM2, the forward and reverse rotation of the servo motor is controlled to complete the flow regulation of the controlled equipment.

[0007] The device of the present invention can control the device to slowly and stably adjust the flow rate at a certain speed in a certain pulse time period. When the flow rate increases or decreases, it can switch quickly and flexibly, eliminating waiting time and ensuring that the flow rate is within the control range.

[0008] The method for accurately controlling the flow of a variable pump described in the present invention is implemented by the following technical solution: a method for accurately controlling the flow of a variable pump, the method is implemented by a device for accurately controlling the flow of a variable pump; the control mode is selected in the initial state, if a manual control mode switch is closed, the program set in the board card starts the manual control mode, if a certain automatic control mode switch is closed, the program set in the board card starts the automatic control mode;

[0009] After the program starts the manual control mode, the program first determines whether there is a DI input signal. If there is no signal, the manual start time is continuously recorded, the output DO signal is false, and the controlled device is not adjusted; once the DI signal is received, the program starts to output the DO signal and operate the controlled device, and judges the relationship between the value of the current time-manual start time and the pulse duration of the controlled device in real time. If the current time-manual start time is greater than the pulse duration of the controlled device, the DO signal is stopped and the operation of the controlled device is ended. If the current time-manual start time is not greater than the pulse duration of the controlled device, the program returns to the step of determining whether there is a DI input signal; finally, verify whether the value of the current time-manual start time exceeds a controlled device control cycle. If it exceeds the duration of the controlled device control cycle, reset the manual start time to prepare for the start of the next control cycle; if it does not exceed a controlled device control cycle, the program returns to the step of determining whether there is a DI input signal;

[0010] There are multiple flow control modes in the automatic control mode. When the user selects a certain flow control mode, the program starts the automatic control mode. First, it determines whether the flow of the controlled device is within the flow range specified by the flow control mode. If it is within the range, it means that the controlled device is within the effective range, and the controlled device is not adjusted. Once it exceeds or falls below the range, an automatic control cycle of the device is started to adjust the controlled device. According to the phase formula of the distribution plate of the controlled device, the automatic pulse duration is calculated, and at the same time, it is determined whether the flow of the controlled device is increased or decreased; at the beginning of an automatic control cycle of a device, the automatic start time is recorded in real time, the output DO signal is true, and the flow of the controlled device is controlled to increase or decrease, and the relationship between the current time-automatic start time value and the automatic pulse duration is determined in real time. If the current time-automatic start time value exceeds the automatic start time, the automatic pulse duration is calculated. When the automatic pulse duration is exceeded, stop outputting the DO signal, end the operation of the controlled device, and then return to the step of judging whether the flow of the controlled device is within the flow range specified by the flow control mode, until the flow of the controlled device is adjusted to the current flow mode range, and the automatic control ends; if the current time-automatic start time does not exceed the automatic pulse duration, the program returns to the device automatic control cycle; before the second and subsequent device automatic control cycles start, it is necessary to judge the relationship between the value of the current time-automatic start time and the control cycle of the controlled device. If the current time-automatic start time is greater than the control cycle of the controlled device, a new device automatic control cycle will be started. If the current time-automatic start time is not greater than the control cycle of the controlled device, the program will go to the step of judging the relationship between the value of the current time-automatic start time and the automatic pulse duration;

[0011] The automatic pulse duration formula:

[0012]

[0013] Where:

[0014] TntAuto—automatic pulse duration;

[0015] R—Current flow value of the controlled device;

[0016] S—flow value in selected flow control mode;

[0017] A—coefficient, which is the statistical data obtained from a large number of test processes;

[0018] C—Current phase of the distribution plate of the controlled device. This value is related to the hardware parameters of the controlled device and can be fine-tuned for specific tests.

[0019] The DO signal controls the on / off of the KM1 coil or the KM2 coil, thereby controlling the flow of the controlled device; the pulse duration of the controlled device and the control cycle of the controlled device are both pre-set values;

[0020] The above process is a realization process of adjusting the flow of the controlled device. The whole program is in a continuous loop state, and then the flow of the controlled device is adjusted to the target range.

[0021] The two manual mode switches are used as "fine adjustment +" or "fine adjustment -" buttons. In manual control mode, the operator clicks the "fine adjustment +" or "fine adjustment -" button on the host computer or operation panel, and the host computer displays the manual state. At this time, the host computer operates the hardware system and displays the flow status in real time. Click the button once, and the flow increases or decreases once.

[0022] In automatic control mode, the operator selects the current flow mode, the host computer displays the automatic state, and the program automatically determines whether the controlled device is within the current flow mode range. If it is within the current flow mode range, no adjustment is made. If it is not within the current flow mode range, and is smaller than the lower limit of the current flow mode, the servo motor speed is slowly increased. If it is larger than the upper limit of the current speed mode, the servo motor speed is gradually reduced until it is adjusted to the current flow mode range.

[0023] The entire program is in a continuous loop. The system can capture signals in real time and accurately, and automatically switch between manual control mode and automatic control mode. The system precisely calculates the required pulse time according to different scenarios, controls the time accurately to milliseconds, and strictly controls the flow. When the direction of flow increase or decrease changes, it can change quickly and flexibly to ensure that the controlled equipment is continuously and stably adjusted to the target range. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the schematic diagram of the flow precision control device.

[0025] Figure 2 It is a program flow chart of the flow precision control device.

[0026] Figure 3 It is the circuit diagram of the flow precision control device. DETAILED DESCRIPTION

[0027] Example 1

[0028] A device for accurately controlling the flow of a variable pump comprises a host computer, a board, a wiring board, a plurality of control switches, DC relays KM1 and KM2, a DC power supply, a DC servo motor, a controlled device and a wiring terminal; the host computer and the board communicate bidirectionally, the board is connected to the wiring board, and the plurality of control switches are connected in parallel; one end of the plurality of control switches is connected to the positive electrode of the DC power supply, and the other end (negative electrode) of the plurality of control switches is connected to the wiring board through the wiring terminal; the negative electrode of the DC power supply is connected to the wiring board through the wiring terminal; the DC servo motor is connected to the flow control end of the controlled device; the flow of the controlled device is fed back to the board through a flow meter;

[0029] The servo motor is connected between the positive and negative poles of the DC power supply through the normally open contact of the relay KM1, and the servo motor is connected between the positive and negative poles of the DC power supply through the normally open contact of the relay KM2; the main coils of the relays KM1 and KM2 are connected in parallel with one end connected to the positive pole of the DC power supply, and the other end connected to the wiring board through the wiring terminal;

[0030] The multiple control switches are divided into two groups: manual control mode switches and automatic control mode switches. There are two manual control mode switches, which respectively control the on and off of the main coils of relays KM1 and KM2 through the board card; there are multiple automatic control mode switches, each automatic control mode switch corresponds to a flow control mode, and the board card controls the on and off of relays KM1 and KM2 under different flow control modes; the manual control mode switch and the automatic control mode switch also send manual control mode signals and automatic control mode signals to the host computer through the board card; by controlling the power on and off of relays KM1 and KM2, the forward and reverse rotation of the servo motor is controlled to complete the flow regulation of the controlled equipment.

[0031] Example 2

[0032] The board adopts PCI-1730U board, and the wiring board adopts ADAM-3937 wiring board; there are five control switches, namely SB1, SB2, SB3, SB4, and SB5; among them, SB1 and SB2 are manual control mode switches, SB1 controls the forward rotation of the servo motor, and SB2 controls the reverse rotation of the servo motor, and the remaining switches are automatic control mode switches and are divided into three flow control modes; one end of SB1, SB2, SB3, SB4, and SB5 is connected to the positive pole of the DC power supply, and the other end is respectively connected to the 1st, 20th, 2nd, 21st, and 3rd terminals of the wiring board; the positive pole of the DC power supply is divided into two paths, which are respectively connected to the 9th and 29th terminals of the wiring board; one end of the main coils of KM1 and KM2 is connected to the positive pole of the DC power supply, and the other end is respectively connected to the 11th and 30th terminals of the wiring board; the PCI-1730U board is installed with DAQNavi driver version 4.0 or above.

[0033] Example 3

[0034] The control switch is equipped with a corresponding operation panel or a corresponding button is provided on the host computer. For example, touch buttons corresponding to SB1, SB2, SB3, SB4, and SB5 are provided on the host computer. At the same time, there are display lights on the host computer to show whether the switches SB1, SB2, SB3, SB4, and SB5 are on or off.

[0035] The PCI-1730U board and the ADAM-3937 wiring board are connected by a PCL-10137-1E cable. The controlled device is a variable pump, and the servo motor controls the flow of the variable pump by controlling the angle of the variable pump swash plate. The DC power supply is a DC24V power supply. The host computer is generally an industrial computer.

[0036] The present invention will be described in detail below in conjunction with the above-mentioned accompanying drawings:

[0037] Figure 1 This is the schematic diagram of the flow precision control device:

[0038] 1) The control device hardware uses mature products, which are composed of Advantech PCI-1730U board, Advantech ADAM-3937 wiring board, PCL-10137-1E cable, switches SB1~SB5, DC24V DC relays KM1~KM2, DC24V power supply, DC24V DC servo motor, controlled equipment and wiring terminals. The specific connections are as follows: Figure 1 shown.

[0039] The control signal status of the controlled equipment at the test site is obtained in real time by the board card. The board card used in this device is Advantech PCI 1730u board card, and the driver must install Advantech board DAQNavi driver version 4.0 or above. PCI 1730u is a digital signal input and output card produced by Advantech, with 16 digital input (DI) channels and 16 digital output (DO) channels, which complete the acquisition of digital input signals and the output of digital output signals. The main function of the switch input / output module is to complete the control of the controlled equipment, receive external trigger signals and provide feedback to the on-site running equipment.

[0040] 2) Control system software

[0041] (a) Control conditions: When the gas source pressure is lower than aMPa and the control gas pressure is lower than bMPa, the test cannot be started (control channels can be added as needed and parameter values ​​can be set).

[0042] (b) Complete the power-on and start-up output control of the inverter, with computer control and external knob control functions, and can complete the flow adjustment output control of the set step value under computer control conditions. The performance test flow precision control device is divided into two control modes: manual control and automatic control.

[0043] Figure 2 It is a program flow chart of the flow precision control device. The control mode is selected in the initial state. If a manual control mode switch is closed, the program set in the board card starts the manual control mode. If a certain automatic control mode switch is closed, the program set in the board card starts the automatic control mode.

[0044] After the program starts the manual control mode, the program first determines whether there is a DI input signal. If there is no signal, the manual start time is continuously recorded, the output DO signal is false, and the variable pump is not adjusted; once the DI signal is received, the program starts to output the DO signal and operate the variable pump, and judges the relationship between the current time-manual start time value and the variable pump pulse duration in real time. If the current time-manual start time is greater than the variable pump pulse duration, the DO signal is stopped and the operation of the variable pump is ended. If the current time-manual start time is not greater than the variable pump pulse duration, the program returns to the step of determining whether there is a DI input signal; finally, verify whether the current time-manual start time value exceeds a variable pump control cycle. If it exceeds the variable pump control cycle, reset the manual start time to prepare for the start of the next control cycle; if it does not exceed a variable pump control cycle, the program returns to the step of determining whether there is a DI input signal;

[0045] There are multiple flow control modes in the automatic control mode. When the user selects a certain flow control mode, the program starts the automatic control mode. First, it determines whether the flow of the variable pump is within the flow range specified by the flow control mode. If it is within the range, it means that the variable pump is within the effective range, and the variable pump is not adjusted. Once it exceeds or falls below the range, an automatic control cycle of the equipment is started to adjust the variable pump. According to the phase formula of the variable pump distribution plate, the automatic pulse duration is calculated, and at the same time, it is determined whether the flow of the variable pump increases or decreases; at the beginning of an automatic control cycle of the equipment, the automatic start time is recorded in real time, the output DO signal is true, and the flow of the variable pump is controlled to increase or decrease, and the relationship between the current time-automatic start time value and the automatic pulse duration is determined in real time. If the current time-automatic start time value exceeds the automatic pulse duration, the automatic pulse duration will be increased or decreased. When the automatic pulse duration is exceeded, stop outputting the DO signal, end the operation of the variable pump, and then return to the step of judging whether the flow of the variable pump is within the flow range specified by the flow control mode, until the flow of the variable pump is adjusted to the current flow mode range, and the automatic control ends; if the current time-automatic start time does not exceed the automatic pulse duration, the program returns to the equipment automatic control cycle; before the second and subsequent equipment automatic control cycles start, it is necessary to judge the relationship between the value of the current time-automatic start time and the variable pump control cycle. If the current time-automatic start time is greater than the controlled equipment control cycle, a new equipment automatic control cycle will be started. If the current time-automatic start time is not greater than the controlled equipment control cycle, the program will go to the step of judging the relationship between the value of the current time-automatic start time and the automatic pulse duration;

[0046] The automatic pulse duration formula:

[0047]

[0048] Where:

[0049] TntAuto—automatic pulse duration;

[0050] R—current flow value of variable pump;

[0051] S—flow value in selected flow control mode;

[0052] A—coefficient, which is the statistical data obtained from a large number of test processes;

[0053] C—Current phase of the distribution plate of the controlled device. This value is related to the hardware parameters of the controlled device and can be fine-tuned for specific tests.

[0054] The DO signal controls the on / off of the KM1 coil or the KM2 coil, thereby controlling the flow rate of the variable pump; the controlled variable pulse duration and the controlled variable control cycle are both pre-set values;

[0055] The above process is the implementation process of a variable pump adjusting the flow rate. The whole program is in a continuous loop state. The system can capture signals in real time and accurately, and automatically switch between manual control mode and automatic control mode (after manually pressing the fine adjustment or flow mode button, the program automatically determines which mode to enter), and continuously and stably adjusts the variable pump to the target range.

[0056] Figure 3 This is the circuit diagram of the flow precision control device: digital input includes: SB1 switch (fine adjustment +), SB2 switch (fine adjustment -), SB3 switch (Ⅰ flow system), SB4 switch (Ⅱ flow system), SB5 switch (Ⅲ flow system). The negative pole of the DC24V power supply is connected to the No. 9 and No. 29 ports of the Advantech ADAM-3937 terminal board through the terminal block. When the switch SB1 is pressed, the DC24V power supply transmits the power signal to the Advantech ADAM-3937 terminal board through the terminal block, and then transmits it to the Advantech PCI-1730U through the PCL-10137-1E cable. The DI0 of the Advantech PCI-1730U terminal board is in a high-level effective state. After receiving the DI0 signal, the host computer determines that the SB1 switch is in a closed state.

[0057] Digital output includes: KM1 relay control (forward), KM2 relay control (reverse). After receiving the DI signal, the host computer determines if the SB1 switch and SB2 switch are closed, and starts the manual mode control; if the SB3 switch, SB4 switch, and SB5 switch are closed, the automatic mode control is turned on. Figure 2 After the flow chart logic calculates the pulse time of this control, the controlled device is adjusted. The host computer software issues a control command to control the DO digital signal output terminal of Advantech PCI-1730U board. When the DO0 terminal outputs, the DC24V power supply at both ends of the relay KM1 control pin is turned on, the normally open pin of the relay KM1 is closed, the DO1 terminal is in an open circuit state, the relay KM2 control pin is not powered on, the normally open end of the relay KM2 is not attracted, the DC24V power supply is connected to the servo motor terminal of the controlled device, and the servo motor of the controlled device works forward after power on. When the DO1 terminal outputs, the DC24V power supply at both ends of the relay KM2 control pin is turned on, the normally open pin of the relay KM2 is closed, the DO0 terminal is in an open circuit state, the relay KM1 control pin is not powered on, the normally open end of the relay KM1 is not attracted, the DC24V power supply is connected to the servo motor terminal of the controlled device, and the servo motor of the controlled device works reversely after power on. After the pulse time of this control, stop the motor from rotating.

Claims

1. A method for accurately controlling the flow of a variable pump, the method is implemented by a device for accurately controlling the flow of a variable pump, the device comprising a host computer, a board, a wiring board, a plurality of control switches, DC relays KM1, KM2, a DC power supply, a DC servo motor, a controlled device and a wiring terminal; the host computer and the board communicate bidirectionally, the board is connected to the wiring board, and the plurality of control switches are connected in parallel; one end of the plurality of control switches is connected to the positive electrode of the DC power supply, and the other end of the plurality of control switches is connected to the wiring board through the wiring terminal; the negative electrode of the DC power supply is connected to the wiring board through the wiring terminal; the DC servo motor is connected to the flow control end of the controlled device; the flow of the controlled device is fed back to the board through the flow meter; The servo motor is connected between the positive and negative poles of the DC power supply through the normally open contact of the relay KM1, and the servo motor is connected between the positive and negative poles of the DC power supply through the normally open contact of the relay KM2; the main coils of the relays KM1 and KM2 are connected in parallel with one end connected to the positive pole of the DC power supply, and the other end connected to the wiring board through the wiring terminal; The multiple control switches are divided into two groups, namely, manual control mode switches and automatic control mode switches. There are two manual control mode switches, which respectively control the on and off of the main coils of relays KM1 and KM2 through the board card; there are multiple automatic control mode switches, each of which corresponds to a flow control mode, and the board card controls the on and off of relays KM1 and KM2 under different flow control modes; the manual control mode switches and the automatic control mode switches also send manual control mode signals and automatic control mode signals to the upper computer through the board card; by controlling the power on and off of relays KM1 and KM2, the forward and reverse rotation of the servo motor is controlled to complete the flow regulation of the controlled equipment; the board card adopts the PCI-1730U board card, and the wiring board adopts the ADAM-3937 wiring board; there are five control switches, namely SB1, SB2, SB3, SB4, and SB5; among them, SB1 and SB2 are manual control mode switches, SB1 controls the forward rotation of the servo motor, and SB2 controls the reverse rotation of the servo motor. The remaining switches are automatic control mode switches and are divided into three flow control modes; one end of SB1, SB2, SB3, SB4, and SB5 is connected to the positive pole of the DC power supply, and the other end is connected to the 1st, 20th, 2nd, 21st, and 3rd terminals of the wiring board respectively; the positive pole of the DC power supply is divided into two paths, which are respectively connected to the 9th and 29th terminals of the wiring board; one end of the main coils of KM1 and KM2 is connected to the positive pole of the DC power supply, and the other end is respectively connected to the 11th and 30th terminals of the wiring board; the PCI-1730U board is installed with DAQNavi driver version 4.0 or above; the control switch is equipped with a corresponding operation panel or a corresponding button is provided on the host computer; the PCI-1730U board and the ADAM-3937 wiring board are connected with a PCL-10137-1E cable; the controlled device is a variable pump, and the servo motor controls the flow of the variable pump by controlling the angle of the variable pump swash plate; the DC power supply is a DC24V power supply; It is characterized in that The control mode is selected in the initial state. If a manual control mode switch is closed, the program in the board card starts the manual control mode. If a certain automatic control mode switch is closed, the program in the board card starts the automatic control mode. After the program starts the manual control mode, the program first determines whether there is a DI input signal. If there is no signal, the manual start time is continuously recorded, the output DO signal is false, and the controlled device is not adjusted; once the DI signal is received, the program starts to output the DO signal and operate the controlled device, and judges the relationship between the value of the current time-manual start time and the pulse duration of the controlled device in real time. If the current time-manual start time is greater than the pulse duration of the controlled device, the DO signal is stopped and the operation of the controlled device is ended. If the current time-manual start time is not greater than the pulse duration of the controlled device, the program returns to the step of determining whether there is a DI input signal; finally, verify whether the value of the current time-manual start time exceeds a controlled device control cycle. If it exceeds the duration of the controlled device control cycle, reset the manual start time to prepare for the start of the next control cycle; if it does not exceed a controlled device control cycle, the program returns to the step of determining whether there is a DI input signal; There are multiple flow control modes in the automatic control mode. When the user selects a flow control mode, the program starts the automatic control mode. First, it determines whether the flow of the controlled device is within the flow range specified by the flow control mode. If it is within the range, it means that the controlled device is within the effective range, and the controlled device is not adjusted. Once it exceeds or falls below the range, an automatic control cycle of the device is started to adjust the controlled device. According to the phase formula of the distribution plate of the controlled device, the automatic pulse duration is calculated, and at the same time, it is determined whether the flow of the controlled device is increased or decreased; At the beginning of an automatic control cycle of a device, the automatic start time is recorded in real time, the output DO signal is true, the flow of the controlled device is controlled to increase or decrease, and the relationship between the value of the current time-automatic start time and the automatic pulse duration is judged in real time. If the value of the current time-automatic start time exceeds the automatic pulse duration, the output DO signal is stopped, the operation of the controlled device is ended, and then the step of judging whether the flow of the controlled device is within the flow range specified by the flow control mode is returned until the flow of the controlled device is adjusted to the current flow mode range, and the automatic control ends; If the current time-automatic start time does not exceed the automatic pulse duration, the program returns to the device automatic control cycle; before the second and subsequent device automatic control cycles start, it is necessary to determine the relationship between the current time-automatic start time value and the controlled device control cycle. If the current time-automatic start time is greater than the controlled device control cycle, a new device automatic control cycle begins. If the current time-automatic start time is not greater than the controlled device control cycle, the program goes to the step of determining the relationship between the current time-automatic start time value and the automatic pulse duration. The automatic pulse duration formula: ； Where: TntAuto—automatic pulse duration; R—current flow value of the controlled device; S—flow value in selected flow control mode; A—coefficient; C—current distribution plate phase of the controlled equipment; The DO signal controls the on / off of the KM1 coil or the KM2 coil, thereby controlling the flow of the controlled device; the pulse duration of the controlled device and the control cycle of the controlled device are both pre-set values; The above process is a realization process of adjusting the flow of the controlled device. The whole program is in a continuous loop state, and then the flow of the controlled device is adjusted to the target range.

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