High precision flow control device, method and apparatus therefor

Abstract

This invention discloses a high-precision flow control device, method, and apparatus, comprising: an execution module consisting of a stepper motor-driven electric needle valve and an EtherCAT bus-type stepper driver, wherein the bus-type stepper driver receives opening control commands and drives the electric needle valve; a detection module employing an EtherCAT bus protocol flow sensor for real-time acquisition of liquid flow data in the pipeline; and a control module using a PLC as an EtherCAT master station, communicating with the bus-type stepper driver and the bus protocol flow sensor via an EtherCAT bus; the PLC receives target flow commands and rapidly acquires real-time flow data fed back by the flow sensor, internally runs algorithms for the coarse adjustment stage, fine adjustment stage, and stable maintenance and differential pressure adaptive stage, and outputs synchronous opening control commands to the bus-type stepper driver.

Description

Technical Field

[0001] This invention belongs to the field of industrial automation control and fluid metering technology, and particularly relates to a high-precision flow control device, method and equipment. Background Technology

[0002] In advanced manufacturing fields such as precision chemical formulation, high-end fluid experiments, biopharmaceuticals, and semiconductor wet processes, the speed and high-precision closed-loop control of liquid flow are core elements for ensuring process consistency, product yield, and the repeatability of experimental results. As process technologies become increasingly complex, higher demands are placed on flow control systems: they must be able to switch between large target flow rates within seconds and maintain a high steady-state accuracy of 0.1% under external pressure disturbances. This poses a significant challenge to existing control technologies.

[0003] Currently, mainstream liquid flow control solutions in the industry fall into two categories. The first category is a control scheme using a pneumatic needle valve and a flow meter. This scheme uses a PLC to send signals to a pneumatic actuator to adjust the needle valve opening and utilizes a flow sensor for feedback to achieve closed-loop control. The second category is a control scheme using a standard electric needle valve and a single PID controller. This scheme uses a PLC to directly drive the electric needle valve to a fixed initial opening, and then continuously executes the PID algorithm, iteratively calculating and fine-tuning the valve position based on the deviation between the real-time flow rate and the target value until the flow rate converges to the allowable range.

[0004] However, pneumatic solutions are affected by gas compressibility and actuator hysteresis, resulting in response times typically exceeding 5 seconds. Ordinary electric solutions, lacking opening prediction and relying on repeated PID adjustments, also cannot achieve rapid adjustment within 2 seconds. Furthermore, pneumatic solutions suffer from dead zones and nonlinearities, with control accuracy often exceeding 1%. Ordinary electric solutions are prone to overshoot and oscillations near the target due to PID integral action, making it difficult to maintain steady-state accuracy below 0.1%. When the target flow rate changes drastically or pipeline pressure differentials suddenly change, the algorithm cannot predict the optimal initial opening and can only blindly probe, easily leading to significant flow overshoot and prolonged non-convergence. Especially in high-frequency, multi-level switching scenarios, the control performance degrades sharply, making it difficult to meet the stringent flow control requirements of advanced processes. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision flow control device, method, and apparatus to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a control method for a high-precision flow control device. The method is applied to a system including a stepper electric needle valve, a bus-type stepper driver, a bus protocol flow sensor, and a programmable logic controller (PLC). The PLC has a pre-stored offline calibration database of the needle valve's full-stroke opening and flow coefficient Cv. The method includes the following steps: Coarse adjustment stage: When the PLC receives the target flow command, it calculates the target Cv value in reverse using the liquid flow formula based on the preset rated operating pressure difference and the target flow, queries the offline calibration database to obtain the corresponding theoretical opening, and drives the stepper electric needle valve to position; it collects the real-time flow, calculates the actual pressure difference before and after the valve in reverse based on the real-time flow, the current opening and liquid property parameters, and then recalculates the optimal theoretical opening by combining the target flow and the actual pressure difference, and drives the stepper electric needle valve to position again; Fine-tuning stage: After the stepper electric needle valve completes the repositioning of the coarse-tuning stage, it enters the integral-derivative PID control mode; the deviation between the actual flow rate and the target flow rate is compared in real time. When the deviation value is greater than the preset threshold, the integral action is cut off, and only the proportional-derivative PD control is used; when the deviation value is less than or equal to the preset threshold, the integral action is engaged, and the complete PID control is executed. Once the fine-tuning stage is completed and the actual flow rate is stable within the allowable error range of the target flow rate, the real-time pressure difference across the valve is continuously calculated online in reverse, and pressure difference fluctuations are monitored. When the pressure difference fluctuation amplitude is less than a preset threshold, the opening is continuously fine-tuned through integral separation PID to maintain a constant flow rate. When the pressure difference fluctuation amplitude exceeds the preset threshold, the current PID fine-tuning is interrupted, and the steps of the coarse-tuning stage and the fine-tuning stage are re-executed.

[0007] In a second aspect, the present invention provides a high-precision flow control device, characterized in that it is used in the control method described above, the device comprising: The execution module consists of a stepper motor driven electric needle valve and an EtherCAT bus-type stepper driver. The bus-type stepper driver receives opening control commands and drives the electric needle valve. The detection module uses an EtherCAT bus protocol flow sensor to collect real-time liquid flow data in the pipeline. The control module uses a PLC as an EtherCAT master station and communicates with the bus-type stepper driver and the bus protocol flow sensor via the EtherCAT bus. The PLC receives the target flow command and acquires the real-time flow feedback from the flow sensor at high speed. It internally runs the algorithms for the coarse adjustment stage, fine adjustment stage, and stable maintenance and differential pressure adaptive stage, and outputs synchronous opening control commands to the bus-type stepper driver.

[0008] Thirdly, the present invention provides an electronic device, comprising: One or more processors; Memory; One or more programs, wherein the one or more programs are stored in the memory and configured to be executed by one or more processors, the one or more programs being configured to perform the steps in the control method of the high-precision flow control device described above.

[0009] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in the control method of the high-precision flow control device described above.

[0010] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the steps in the control method of the high-precision flow control device described above.

[0011] Compared with existing technologies, this invention achieves rapid positioning and repositioning of the stepper electric needle valve by pre-storing an offline calibration database of the needle valve's full stroke opening and flow coefficient Cv within the PLC. During the coarse adjustment phase, it first calculates the Cv value based on the target flow rate and rated differential pressure, then queries the database to obtain the theoretical opening, and finally recalculates the optimal theoretical opening based on the actual differential pressure calculated from the real-time flow rate. This avoids the lag problem of repeated trial-and-error adjustments. Furthermore, during the fine adjustment phase, it adaptively switches between integral-separated PID mode based on the deviation between the actual and target flow rates. For large deviations, integral adjustment is disabled, and only PD regulation is used to quickly eliminate the deviation and suppress overshoot. For small deviations, integral adjustment is applied to eliminate static errors, improving both response speed and steady-state accuracy. After the flow rate stabilizes, it continuously monitors the actual differential pressure fluctuations online. When the fluctuations are small, PID fine-tuning is used to maintain a constant pressure. When the fluctuations exceed a threshold, the entire coarse and fine adjustment process is restarted. This achieves rapid response, high-precision locking, and strong adaptability under complex differential pressure disturbance conditions. Attached Figure Description

[0012] To more clearly illustrate and understand the technical solutions in the embodiments of the present invention, the accompanying drawings used in the background technology and embodiment descriptions of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0013] Figure 1 The flowchart illustrates the operation of a control method for a high-precision flow control device provided by this invention. Figure 2 A hardware system block diagram of a high-precision flow control device provided by the present invention; Figure 3 This is a schematic diagram of the structure of a high-precision flow control device provided by the present invention; Figure 4 This is a schematic diagram of the structure of an electronic device provided by the present invention.

[0014] Figure 3 and Figure 4 The following reference numerals are included: The high-precision flow control device 200 includes an execution module 210, a detection module 220, a control mechanism 230, an electronic device 300, a computing unit 301, a read-only memory (ROM) 302, a random access memory (RAM) 303, a bus 304, an input / output (I / O) interface 305, an input unit 306, an output unit 307, a storage unit 308, and a communication unit 309. Detailed Implementation

[0015] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figure 1 As shown, this invention provides a control method for a high-precision flow control device. The method is applied to a system including a stepper electric needle valve, a bus-type stepper driver, a bus protocol flow sensor, and a programmable logic controller (PLC). The PLC has a pre-stored offline calibration database of the needle valve's full-stroke opening and the flow coefficient Cv. Figure 1 As shown, the method specifically includes the following steps: S110, Coarse Adjustment Stage: When the PLC receives the target flow command, it calculates the target Cv value in reverse using the liquid flow formula based on the preset rated operating pressure difference and target flow, queries the offline calibration database to obtain the corresponding theoretical opening, and drives the stepper electric needle valve to position; it collects the real-time flow, calculates the actual pressure difference before and after the valve in reverse based on the real-time flow, current opening and liquid property parameters, and then recalculates the optimal theoretical opening by combining the target flow and actual pressure difference, and drives the stepper electric needle valve to position again.

[0017] The offline calibration database stores the correspondence between the full-stroke opening of the needle valve and the flow coefficient Cv. Specifically, it is obtained through offline calibration experiments and the correspondence between the full-stroke opening of the needle valve and the flow coefficient Cv is pre-stored in the PLC to provide a data basis for subsequent feedforward coarse adjustment.

[0018] It can be seen that the coarse adjustment stage includes two positioning steps. The first positioning step involves receiving the target flow command and, instead of using the traditional PID repetitive trial-and-error method, directly utilizing the inverse formula of liquid flow rate Cv. By combining the known target flow rate and the preset rated operating pressure difference, the required target Cv value is quickly calculated. Then, by querying the pre-stored offline calibration database, the corresponding theoretical opening degree is directly obtained, driving the needle valve to quickly reach that position. This achieves rapid positioning in one operation, significantly shortening the adjustment time.

[0019] The second positioning is performed after the first positioning, once the needle valve has reached the coarse adjustment position. At this point, real-time flow in the pipeline is collected, and combined with the current valve opening and liquid properties, the actual pressure difference across the valve (not the rated pressure difference) is calculated in reverse. This actual pressure difference replaces the original rated pressure difference, and the optimal theoretical opening is recalculated based on the target flow rate, driving the needle valve to reposition itself. This step corrects for potential deviations caused by the difference between the actual and rated pressure differences, making the needle valve opening closer to the final target value and further reducing flow deviation.

[0020] In some exemplary embodiments, the offline calibration database is constructed in the following way: by experimental measurement, the correspondence between the opening degree and the flow coefficient Cv of the stepper electric needle valve in the full stroke range of 0% to 100% is obtained, and the opening degree-Cv data pairs are stored in the PLC in the form of a two-dimensional array at equal intervals of 5%.

[0021] The coarse-tuning stage of this invention requires querying the Cv value corresponding to the opening degree; therefore, the accuracy of the database directly affects the accuracy of the feedforward calculation. For example, the offline calibration database uses experimental calibration with 0-100% full stroke and 5% equal intervals, which ensures sufficient data density (the Cv value of intermediate opening degrees can be accurately calculated through interpolation) while avoiding the increased workload caused by excessively dense calibration.

[0022] Step 120, Fine-tuning stage: After the stepper electric needle valve completes the repositioning of the coarse-tuning stage, it enters the integral-derivative PID control mode; the deviation between the actual flow rate and the target flow rate is compared in real time. When the deviation is greater than the preset threshold, the integral action is cut off, and only the proportional-derivative PD control is used; when the deviation is less than or equal to the preset threshold, the integral action is engaged, and the complete PID control is executed.

[0023] Specifically, after coarse adjustment, the flow rate is close to the target value, at which point fine adjustment mode is switched in. Traditional PID control with full integral action is prone to overshoot and oscillation. This invention adopts an integral separation strategy: when the flow rate deviation is large (e.g., just after switching to the fine adjustment stage), the integral action is temporarily turned off, and only proportional and derivative control is used to quickly eliminate the deviation without causing overshoot; when the deviation shrinks to within a preset threshold, the integral action is then engaged to eliminate the last small deviation and achieve high-precision locking. This segmented processing can achieve both dynamic response speed and steady-state control accuracy.

[0024] Step 130: After the fine-tuning stage is completed and the actual flow rate is stable within the allowable error range of the target flow rate, continuously calculate the real-time pressure difference before and after the valve online and monitor the pressure difference fluctuation; when the pressure difference fluctuation amplitude is less than the preset threshold, continuously fine-tune the opening through integral separation PID to maintain a constant flow rate; when the pressure difference fluctuation amplitude exceeds the preset threshold, interrupt the current PID fine-tuning and re-execute the steps of the coarse-tuning stage and the fine-tuning stage.

[0025] Specifically, once the fine-tuning phase is completed and the actual flow rate stabilizes within the allowable error range of the target flow rate, the flow rate can be considered stable. After the flow rate stabilizes, the system does not stop working but continuously monitors the pressure difference. If the pressure difference fluctuates only slightly (such as during normal operating conditions), a minor correction is made using integral-separated PID control to maintain a constant flow rate. If the pressure difference changes drastically (such as during upstream pump disturbances or pipeline load switching), it indicates that the current PID fine-tuning is insufficient. The system immediately interrupts the current fine-tuning mode and automatically restarts the coarse-tuning and fine-tuning phases, thereby re-matching the optimal opening degree based on the new actual pressure difference. This adaptive mechanism ensures that the system can quickly recover stability under complex operating conditions, avoiding flow instability or prolonged overshoot.

[0026] In some exemplary embodiments, during the coarse adjustment stage, the theoretical opening degree for a single rapid positioning is calculated as follows: Theoretical opening degree = Rated opening degree × Coarse adjustment coefficient; the value range of the coarse adjustment coefficient is 0.1 to 1.0. Preferably, the value range of the coarse adjustment coefficient is 0.4 to 0.5.

[0027] The coarse adjustment coefficient ranges from 0.1 to 1.0, with a preferred value of 0.4 to 0.5 (i.e., less than half of the rated opening). This value is based on the following logic: reserving sufficient opening margin to prevent flow overshoot when the actual pressure difference exceeds the rated pressure difference; and simultaneously preserving sufficient adjustment stroke to meet the requirements of rapid response.

[0028] Figure 2This is a block diagram of the hardware system composition of the fast and high-precision flow control device of the present invention. The device uses a programmable logic controller (PLC) as the EtherCAT master station (i.e., the core unit of the control system) to construct a fully digital bus communication network. The PLC establishes high-speed real-time communication links with a bus-type stepper driver and a bus protocol flow sensor through the EtherCAT industrial Ethernet bus. Specifically, the PLC sends opening control commands (i.e., stepper electric needle valve drive commands) to the bus-type stepper driver, which drives the stepper motor-driven electric needle valve to perform opening adjustment actions, thereby realizing the control of the pipeline flow by the execution module. At the same time, the bus protocol flow sensor collects the liquid flow data in the pipeline in real time (i.e., real-time flow) and uploads the flow feedback signal to the PLC without loss and with low latency through the EtherCAT bus, forming a closed-loop control link composed of the PLC, the bus-type stepper driver, the stepper electric needle valve, and the bus protocol flow sensor. Figure 2 The directional arrows clearly indicate the downward direction of the control command and the upward direction of the flow feedback, intuitively demonstrating the fully digital flow control architecture of this invention, which features a full bus, low latency, and high synchronization.

[0029] By pre-storing an offline calibration database of the needle valve's full-stroke opening and flow coefficient Cv within the PLC, and during the coarse adjustment phase, the theoretical opening is obtained by recalculating the Cv value based on the target flow rate and rated differential pressure, and then recalculating the optimal theoretical opening based on the actual differential pressure after recalculating the real-time flow rate, the stepper electric needle valve can be quickly positioned and repositioned, avoiding the lag problem of repeated trial and error adjustments. Then, during the fine adjustment phase, the integral-separated PID mode is adaptively switched according to the deviation between the actual flow rate and the target flow rate. When the deviation is large, the integral is cut off and only PD adjustment is used to quickly eliminate the deviation and suppress overshoot. When the deviation is small, the integral is applied to eliminate static error, which improves the response speed and ensures steady-state accuracy. After the flow rate stabilizes, the actual differential pressure fluctuation is continuously monitored online. When the fluctuation is small, it is maintained constant through PID fine adjustment. When the fluctuation exceeds the threshold, the entire coarse and fine adjustment process is restarted, thus achieving rapid response, high-precision locking and strong self-adaptive capability under complex differential pressure disturbance conditions.

[0030] Figure 3 This is a schematic diagram of a high-precision flow control device 200 provided by the present invention. This device is used to execute the above-mentioned control method, such as... Figure 3 As shown, the device includes: The execution module 210 consists of a stepper motor driven electric needle valve and an EtherCAT bus-type stepper driver. The bus-type stepper driver receives the opening control command and drives the electric needle valve. The detection module 220 uses an EtherCAT bus protocol flow sensor to collect liquid flow data in the pipeline in real time. The control mechanism 230 uses a PLC as an EtherCAT master station and communicates with a bus-type stepper driver and a bus protocol flow sensor via the EtherCAT bus. The PLC receives the target flow command and acquires the real-time flow feedback from the flow sensor at high speed. It internally runs algorithms for coarse adjustment, fine adjustment, and stable maintenance and differential pressure adaptive stages, and outputs synchronous opening control commands to the bus-type stepper driver.

[0031] As an example, the hardware configuration of this device has the following characteristics: it uses a stepper electric needle valve (not a pneumatic needle valve or a common electric valve); it uses an EtherCAT bus-type stepper driver (not a pulse-type common driver); it uses an EtherCAT bus protocol flow sensor (not an analog output sensor); and it uses a PLC as the EtherCAT master to build a full bus communication link. The advantages of this hardware configuration are: fully digital communication, no analog signal conversion delay; synchronization period down to the microsecond level, extremely low latency; strong resistance to electromagnetic interference; no accumulated step error; and no adjustment dead zone. These hardware features provide the underlying execution and detection guarantees for the aforementioned control algorithm.

[0032] Optionally, the stepper electric needle valve and the bus-type stepper driver together constitute a high-precision microstepping closed-loop drive architecture for the stepper motor. The bus-type stepper driver synchronously sends pulse and direction commands via the EtherCAT bus to achieve opening adjustment without cumulative step error or dead zone.

[0033] Traditional pneumatic needle valves suffer from dead zones and nonlinear errors; ordinary pulse-type stepper drivers may experience missed steps or accumulated errors. This invention employs an EtherCAT bus-type stepper driver, relying on the bus to synchronously issue pulse and direction commands, achieving high-precision microstepping closed-loop drive. This ensures excellent linearity of opening adjustment, no accumulated step errors, and no adjustment dead zones, providing hardware-level precision assurance for high-precision flow control.

[0034] Optionally, the flow sensor has a built-in standard EtherCAT fieldbus interface for hard real-time bus communication with the PLC acting as the master station. The data synchronization cycle is in the microsecond range, which is used to upload the flow feedback data in real time without loss and with low latency.

[0035] Specifically, this invention employs a bus-type flow sensor with a built-in EtherCAT interface for hard real-time communication with the PLC master station, achieving a synchronization cycle at the microsecond level. This results in lossless, low-latency, and interference-resistant feedback data. This provides a high-fidelity raw flow data source for high-precision closed-loop calculations and rapid differential pressure reverse calculations in the backend.

[0036] Optionally, the liquid flow rate formula follows the standard flow rate calculation formula for incompressible liquids, and its basic flow rate formula and inverse calculation formula for the flow coefficient Cv are as follows: Basic flow formula: ; Inverse formula for calculating the flow coefficient Cv: ; Where Q is the volumetric flow rate, Cv is the valve flow capacity, ΔP is the pressure difference across the valve, and SG is the density of the liquid relative to water. Furthermore, the control method or device has the following functions: based on the real-time flow rate, the current valve opening degree, and the relative density of the liquid, it reversely calculates the actual pressure difference across the valve, providing a basis for feedforward opening correction.

[0037] The high-precision flow control device 200 can achieve Figure 1 For details of the method implementation examples, please refer to [link / reference]. Figure 1 The control method of the high-precision flow control device in the illustrated embodiment will not be described in detail.

[0038] One embodiment of this application provides a computer-readable storage medium storing at least one instruction, which is loaded and executed by a processor to implement the control method of the high-precision flow control device as described above.

[0039] One embodiment of this application provides an electronic device, which includes a processor and a memory. The memory stores at least one instruction, which is loaded and executed by the processor to implement the control method of the high-precision flow control device as described above.

[0040] The collection, storage, use, processing, transmission, provision, and disclosure of user personal information involved in the technical solution of this application all comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0041] Figure 4 A schematic block diagram of an example electronic device 300 that can be used to implement embodiments of this application is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the application described and / or claimed herein.

[0042] like Figure 4As shown, the electronic device 300 includes a computing unit 301, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 302 or a computer program loaded from a storage unit 308 into a random access memory (RAM) 303. The RAM 303 may also store various programs and data required for the operation of the electronic device 300. The computing unit 301, the ROM 302, and the RAM 303 are interconnected via a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0043] Multiple components in electronic device 300 are connected to input / output (I / O) interface 305, including: input unit 306, such as keyboard, mouse, etc.; output unit 307, such as various types of monitors, speakers, etc.; storage unit 308, such as disk, optical disk, etc.; and communication unit 309, such as network card, modem, wireless transceiver, etc. Communication unit 309 allows electronic device 300 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0044] The computing unit 301 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 301 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 301 performs the various methods and processes described above, such as the control method of a high-precision flow control device. For example, in some embodiments, the control method of a high-precision flow control device may be implemented as a computer software program tangibly contained in a machine-readable medium, such as storage unit 308. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 300 via ROM 302 and / or communication unit 309. When the computer program is loaded into RAM 303 and executed by the computing unit 301, one or more steps of the control method of the high-precision flow control device described above may be performed. Alternatively, in other embodiments, the computing unit 301 may be configured by any other suitable means (e.g., by means of firmware) to perform the control method of the high-precision flow control device.

[0045] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations may include: implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transferring data and instructions to the storage system, at least one input device, and at least one output device.

[0046] The program code used to implement the methods of this application may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0047] In the context of this application, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0048] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0049] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as a data server), or computing systems that include middleware components (e.g., an application server), or computing systems that include frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., a communication network). Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0050] Computer systems can include clients and servers. Clients and servers are generally located far apart and typically interact via communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other. Servers can be cloud servers, servers in distributed systems, or servers incorporating blockchain technology.

[0051] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0052] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A control method for a high-precision flow control device, characterized in that, The method is applied to a system including a stepper electric needle valve, a bus-type stepper driver, a bus protocol flow sensor, and a programmable logic controller (PLC). The PLC has an internal offline calibration database of the needle valve's full stroke opening and flow coefficient Cv. The method includes the following steps: Coarse adjustment stage: When the PLC receives the target flow command, it calculates the target Cv value in reverse using the liquid flow formula based on the preset rated operating pressure difference and the target flow, queries the offline calibration database to obtain the corresponding theoretical opening, and drives the stepper electric needle valve to position; it collects the real-time flow, calculates the actual pressure difference before and after the valve in reverse based on the real-time flow, the current opening and liquid property parameters, and then recalculates the optimal theoretical opening by combining the target flow and the actual pressure difference, and drives the stepper electric needle valve to position again; Fine-tuning stage: After the stepper electric needle valve completes the repositioning of the coarse-tuning stage, it enters the integral-derivative PID control mode; the deviation between the actual flow rate and the target flow rate is compared in real time. When the deviation value is greater than the preset threshold, the integral action is cut off, and only the proportional-derivative PD control is used; when the deviation value is less than or equal to the preset threshold, the integral action is engaged, and the complete PID control is executed. Once the fine-tuning stage is completed and the actual flow rate is stable within the allowable error range of the target flow rate, the real-time pressure difference across the valve is continuously calculated online in reverse, and pressure difference fluctuations are monitored. When the pressure difference fluctuation amplitude is less than a preset threshold, the opening is continuously fine-tuned through integral separation PID to maintain a constant flow rate. When the pressure difference fluctuation amplitude exceeds the preset threshold, the current PID fine-tuning is interrupted, and the steps of the coarse-tuning stage and the fine-tuning stage are re-executed.

2. The control method of the high-precision flow control device as described in claim 1, characterized in that, The offline calibration database is constructed in the following way: through experimental measurement, the correspondence between the opening degree and the flow coefficient Cv of the stepper electric needle valve in the full stroke range of 0% to 100% is obtained, and the opening degree-Cv data pairs are stored in the PLC in the form of a two-dimensional array at equal intervals of 5%.

3. The control method of the high-precision flow control device as described in claim 1, characterized in that, In the coarse adjustment stage, the theoretical opening of a single rapid positioning is calculated as follows: theoretical opening = rated opening × coarse adjustment coefficient; the value of the coarse adjustment coefficient ranges from 0.1 to 1.

0.

4. A high-precision flow control device, characterized in that, The apparatus for performing the control method according to any one of claims 1 to 3, comprising: The execution module consists of a stepper motor driven electric needle valve and an EtherCAT bus-type stepper driver. The bus-type stepper driver receives opening control commands and drives the electric needle valve. The detection module uses an EtherCAT bus protocol flow sensor to collect real-time liquid flow data in the pipeline. The control module uses a PLC as an EtherCAT master station and communicates with the bus-type stepper driver and the bus protocol flow sensor via the EtherCAT bus. The PLC receives the target flow command and acquires the real-time flow feedback from the flow sensor at high speed. It internally runs the algorithms for the coarse adjustment stage, fine adjustment stage, and stable maintenance and differential pressure adaptive stage, and outputs synchronous opening control commands to the bus-type stepper driver.

5. The high-precision flow control device as described in claim 4, characterized in that, The stepper electric needle valve and the bus-type stepper driver together constitute a high-precision microstepping closed-loop drive architecture for the stepper motor. The bus-type stepper driver synchronously sends pulse and direction commands via the EtherCAT bus.

6. The high-precision flow control device as described in claim 4, characterized in that, The flow sensor has a built-in standard EtherCAT fieldbus interface, which communicates with the PLC, which acts as the master station, via a hard real-time bus. The data synchronization cycle is in the microsecond range, which is used to upload the flow feedback data in real time without loss and with low latency.

7. The high-precision flow control device as described in claim 4, characterized in that, The liquid flow rate formula follows the standard flow rate calculation formula for incompressible liquids, and its basic flow rate formula and the inverse solution formula for the flow coefficient Cv are as follows: Basic flow formula: ; Inverse formula for calculating the flow coefficient Cv: ; Where Q is the volumetric flow rate, Cv is the valve flow capacity, ΔP is the pressure difference across the valve, and SG is the density of the liquid relative to water. Furthermore, the control method or device has the following function: based on the real-time flow rate, the current valve opening degree, and the relative density of the liquid, it reversely calculates the actual pressure difference across the valve, providing a basis for feedforward opening correction.

8. An electronic device, comprising: One or more processors; Memory; One or more programs, wherein the one or more programs are stored in the memory and configured to be executed by one or more processors, the one or more programs being configured to perform the steps of the method of any of claims 1-3 above.

9. A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of any one of the methods of claims 1-3.

10. A computer program product comprising a computer program that, when executed by a processor, implements the steps of the method described in any one of claims 1-3.

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