Calibration method, system, and apparatus for split mass flow controllers

Abstract

This invention relates to the field of fluid control technology and discloses a calibration method, system, and device for a split-type mass flow controller. The method utilizes a split, modular design, connecting the control unit, valve unit, detection unit, and fluid passage unit via detachable interfaces, thus solving the problem of difficult calibration and maintenance in traditional integrated structures. A flow mapping model is established using temperature difference and pressure data, combined with dynamic correction using an ambient temperature compensation coefficient, significantly improving detection accuracy. Through coordinated control of flow closed-loop and valve core displacement closed-loop, precise adjustment of valve opening is achieved, effectively improving the stability and dynamic response performance of flow control. This system possesses advantages such as flexible structure, high calibration accuracy, and strong environmental adaptability, making it suitable for high-precision flow control fields such as semiconductors and biomedicine.

Description

Technical Field

[0001] This application relates to the field of fluid measurement and control technology, and more specifically, to a calibration method, system and device for a split-type mass flow controller. Background Technology

[0002] The integrated design of traditional mass flow controllers leads to difficulties in calibration and maintenance, and repeated disassembly and reassembly can easily introduce mechanical errors. Existing thermal flow detection technology relies on a single temperature difference to calculate flow rate, failing to consider the impact of fluid pressure fluctuations on thermal diffusion characteristics, and lacks accurate modeling of the coupling relationship between the flow rate of the branch and main channels, especially with insufficient accuracy in the low flow range. Valve control generally adopts single closed-loop regulation, which suffers from response lag and overshoot problems, and lacks real-time monitoring and control of valve core displacement. At the same time, the systems generally ignore the impact of ambient temperature changes on thermodynamic parameters and lack effective temperature compensation mechanisms, which restricts the accuracy and stability of the equipment under different operating conditions. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a calibration method, system and equipment for a split-type mass flow controller, which has the advantages of improving detection accuracy, enhancing anti-interference ability and ensuring long-term stability.

[0004] Firstly, a calibration method for a split-type mass flow controller includes the following steps:

[0005] S1: The control module, valve module, detection module and fluid passage module are set up separately to form a fluid control loop including several calibrated flow points. A temperature sensor is deployed in the fluid control loop to obtain the initial temperature parameters. The valve module is closed to make the loop in a zero flow state. The sensor data is collected synchronously through the detection module. After removing abnormal values, the average value of the valid data is taken. The reference temperature difference between the liquid inlet end and the liquid outlet end of the fluid control loop is calculated and the reference temperature difference is set as the zero reference.

[0006] S2: Based on the zero-point reference, the control module drives the standard flow source to output several calibration flow points. Under the steady-state condition of the calibration flow points, the temperature difference signal and the inlet pressure signal are collected synchronously. Based on the temperature difference signal and the inlet pressure signal, a mapping relationship model between the main road mass flow rate and the temperature difference and inlet pressure is established.

[0007] S3: Obtain the parameter changes in the mapping relationship model under several different ambient temperatures, fit the ambient temperature compensation coefficient through a multiple regression algorithm, construct a mass flow compensation model that integrates the ambient temperature compensation coefficient, and establish a linear control model between the flow setpoint and the control signal based on the calibration data.

[0008] S4: Set the target mass flow rate, call the linear control model and the mass flow compensation model to calculate the initial control parameters; based on the real-time acquired temperature difference signal and inlet pressure signal, calculate the real-time mass flow rate through the mapping relationship model and the mass flow compensation model.

[0009] Furthermore, it also includes: assembling the control module, valve module, detection module, and fluid passage module into a complete flow control loop through a preset detachable interface; sealing the output end of the standard flow source with the main passage inlet of the fluid passage module; the host computer sending an initialization command to the control module via a communication unit; the control module driving the valve module to remain normally closed; and simultaneously controlling the heating element in the detection module to be energized and heated to maintain a constant temperature; while recording the temperature data from the symmetrically arranged temperature sensors upstream and downstream of the heating element. Temperature sensor initial resistance value 0. Initial resistance value 0, calculate the initial temperature difference ΔT0.

[0010] Furthermore, the steps for establishing the mapping relationship model include: the host computer sets N calibration flow points Q1, Q2, ..., Q6, covering the range from 0 to the maximum range, according to the mass flow controller's range. n The standard flow source is controlled to sequentially output the corresponding flow rate to the main channel of the fluid pathway module; for each calibrated flow rate point Q i The control module adjusts the duty cycle of the PWM signal output to the solenoid coil of the valve module through the PWM drive unit, so that the flow rate in the main passage is stabilized at Q. i Simultaneously, the detection module collects temperature data from the temperature sensor within the shunt channel. Temperature sensor Real-time resistance value Real-time resistance value Calculate the temperature difference Where R0 is a preset standard resistance value, and real-time pressure data collected by the fluid passage inlet pressure sensor is acquired. ;based on and Establish traffic splitting Coupling model between the two ,in The diversion coefficient is used to deduce the main flow rate based on the flow ratio between the diversion channel and the main channel. This forms a mapping table of main flow rate, temperature difference, and pressure, which is then stored in the main controller of the control module.

[0011] Furthermore, the process of establishing the mass flow compensation model includes: performing flow calibration under several different set ambient temperatures, and obtaining the temperature difference signal and the measured value of the main flow corresponding to each calibration flow point under each temperature condition;

[0012] Based on multiple sets of temperature difference signals and measured values ​​of main road flow, the ambient temperature compensation coefficient is calculated through multiple regression analysis.

[0013] Based on the ambient temperature compensation coefficient and the set reference ambient temperature, a flow compensation function is constructed;

[0014] For each target flow point after compensation, adjust the valve control signal until the actual flow rate stabilizes at the target flow point, and record the corresponding control signal parameters;

[0015] By fitting the compensated flow rate value with the corresponding control signal parameters, a linear control model characterizing the relationship between the flow rate setpoint and the control signal is established.

[0016] Furthermore, step S4 specifically includes:

[0017] The control module, based on the set target flow rate, calls the established mapping relationship model, flow compensation model, and linear control model to calculate and output the corresponding control signals to the valve module;

[0018] The detection module and the fluid pathway module acquire flow-related sensor signals in real time during the control process;

[0019] The control module calculates the real-time flow rate based on the sensor signal and the mass flow compensation model;

[0020] Determine whether the deviation between the real-time flow and the target flow exceeds the allowable error range. If it does, adjust the control signal through the flow closed-loop feedback loop.

[0021] The actual displacement feedback of the valve core in the valve module is obtained, and it is determined whether there is a deviation between the actual displacement and the theoretical displacement corresponding to the control signal. If there is a deviation, the control signal is collaboratively corrected through the displacement closed-loop feedback loop.

[0022] Secondly, the present invention also provides a split-type mass flow controller calibration system, comprising: a control module, a valve module, a detection module, and a fluid passage module;

[0023] The control module includes a main controller, a data acquisition unit for acquiring sensor signals, a drive unit for driving the valve module, and a communication unit for communicating with external devices.

[0024] The valve module is used to receive control signals from the drive unit and adjust the flow channel opening to control the fluid flow rate;

[0025] The detection module is used to detect the temperature difference signal generated by the flowing fluid;

[0026] The fluid flow path module is used to provide a fluid flow path and detect inlet pressure signals;

[0027] The control module, valve module, detection module and fluid passage module are connected by a detachable interface to form a fluid control loop including several calibrated flow points.

[0028] Furthermore, the fluid pathway module also includes a displacement sensor, and the acquisition unit includes several signal conditioning circuits for processing the signals output by the corresponding sensors; the storage unit, connected to the main controller, is used to store the reference data, mapping table, compensation coefficients and model parameters of the calibration process.

[0029] Furthermore, it also includes a magnetic valve core, which further includes a valve cavity. The surface of the magnetic valve core is covered with a wear-resistant layer, and the inner wall of the valve cavity is provided with a sealing ring. The displacement sensor is connected to the control module through an electrical interface.

[0030] Furthermore, the heating element of the detection module is a platinum resistance thermometer, and it is equipped with an overheat protection circuit; the temperature sensor can be an NTC thermistor.

[0031] Thirdly, the present invention also provides a split-type mass flow control device, including the split-type mass flow controller calibration system described in any one of the claims, and further including a housing with independent chambers and an adjustable fixing bracket. The interior of the housing is divided into multiple independent chambers by heat-insulating partitions for respectively accommodating the control module, valve module and detection module. The adjustable fixing bracket is fixed to the outer wall of the housing, and the fluid passage module is fixed to the fixing bracket by a snap-fit ​​structure. The front of the housing is provided with an operation panel, which is provided with a display screen, buttons and detachable electrical and fluid interfaces for each unit.

[0032] As can be seen from the above, the split-type mass flow controller calibration method, system and equipment provided in this application, through the split modular design combined with multi-parameter coupling calculation of temperature difference, pressure data and environmental compensation, and the use of flow closed-loop and valve core displacement closed-loop collaborative control, solves the problems of difficult disassembly and maintenance, insufficient detection accuracy and poor environmental adaptability of traditional equipment. It has the advantages of modular disassembly and assembly convenience, high accuracy of multi-parameter coupling compensation and strong stability of dual closed-loop collaborative control. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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 structures shown in these drawings without creative effort.

[0034] Figure 1 This is a flowchart illustrating the working steps of the calibration method for the split-type mass flow controller of the present invention.

[0035] Figure 2 This is a block diagram of the calibration system for the split-type mass flow controller of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of the split-type mass flow controller calibration device of the present invention.

[0037] Figure descriptions: 11. Housing; 12. Independent chamber; 13. Adjustable fixing bracket; 14. Display screen. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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.

[0039] The terms "first," "second," etc., used in this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or end that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or ends.

[0040] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] In existing technologies, mass flow controllers generally adopt an integrated design, combining the control board, valves, detection modules, and fluid passages into a single housing. This structure requires complete disassembly during calibration, resulting in complex procedures and susceptibility to mechanical errors. Thermal flow detection schemes rely on a single temperature difference to calculate flow rate, failing to consider the impact of fluid pressure changes on heat diffusion, leading to detection errors in low flow ranges. Valve control uses a single closed-loop regulation mode, lacking real-time monitoring of valve core displacement, making it prone to response lag and overshoot. The lack of effective compensation mechanisms for ambient temperature fluctuations exacerbates flow detection and control errors.

[0042] refer to Figure 1 The present invention provides an embodiment, in the first aspect, a calibration method for a split-type mass flow controller, comprising:

[0043] S1: The control module, valve module, detection module and fluid passage module are set up separately to form a fluid control loop including several calibrated flow points. A temperature sensor is deployed in the fluid control loop to obtain the initial temperature parameters. The valve module is closed to make the loop in a zero flow state. The sensor data is collected synchronously through the detection module. After removing abnormal values, the average value of the valid data is taken. The reference temperature difference between the liquid inlet end and the liquid outlet end is calculated and the reference temperature difference is set as the zero reference.

[0044] S2: Based on the zero-point reference, the control module drives the standard flow source to output multiple calibrated flow points. Under the steady-state conditions of each flow point, the temperature difference signal and inlet pressure signal generated by the fluid flowing through the detection module are collected synchronously. Based on the temperature difference signal and inlet pressure signal, a mapping relationship model between the main road mass flow rate and the temperature difference and inlet pressure is established.

[0045] S3: Obtain the parameter changes in the mapping relationship model under several different ambient temperatures, obtain the ambient temperature compensation coefficient by fitting through a multiple regression algorithm, and then construct a mass flow compensation model that integrates the ambient temperature compensation coefficient. Based on the calibration data, establish a linear control model between the flow setpoint and the control signal.

[0046] S4: Set the target mass flow rate, call the linear control model and the mass flow rate compensation model to calculate the initial control parameters, and output them to the valve module; during the control process, based on the real-time acquired temperature difference signal and inlet pressure signal, calculate the real-time mass flow rate through the mapping relationship model and the mass flow rate compensation model, and dynamically adjust the control parameters until the real-time mass flow rate stabilizes within the allowable error range corresponding to the target mass flow rate.

[0047] Preferably, the initialization calibration specifically includes: assembling the control module, valve module, detection module, and fluid passage module into a complete flow control loop through a preset detachable interface; sealing the output end of the standard flow source with the main passage inlet of the fluid passage module; sending an initialization command to the control module via a communication unit; the control module driving the valve module to remain normally closed; and simultaneously controlling the heating element in the detection module to be energized and heated to maintain a constant temperature. At this time, the temperature sensors symmetrically arranged upstream and downstream of the heating element are recorded. Temperature sensor initial resistance value 0. Initial resistance value 0, calculate the initial temperature difference ΔT0.

[0048] Preferably, the steps for establishing the mapping relationship model include: the host computer setting N calibration flow points Q1, Q2, ..., Q3 covering the range from 0 to the maximum range according to the mass flow controller's range. n The standard flow source is controlled to sequentially output the corresponding flow rate to the main channel of the fluid pathway module; for each calibrated flow rate point Q i The control module adjusts the duty cycle of the PWM signal output to the solenoid coil of the valve module through the PWM drive unit, so that the flow rate in the main passage is stabilized at Q. i Simultaneously, the detection module collects temperature data from the temperature sensor within the shunt channel. Temperature sensor Real-time resistance value Real-time resistance Calculate the temperature difference R0 is a preset standard resistance value, and real-time pressure data collected by the inlet pressure sensor of the fluid passage module is acquired. ;based on and Establish traffic splitting Coupling model between the two ,in The diversion coefficient is used to deduce the main flow rate based on the flow ratio between the diversion channel and the main channel. This forms a mapping table of main flow rate, temperature difference, and pressure, which is then stored in the main controller of the control module.

[0049] In some embodiments, a constant flow point refers to multiple discrete flow values ​​covering the range of the mass flow controller. Specifically, this can be achieved by the host computer automatically generating equally spaced points based on the range, used to establish the correspondence between flow rate and sensor data during calibration. The PWM drive unit refers to a circuit module that outputs a pulse width modulation signal. Specifically, it can be implemented using an integrated circuit with frequency and duty cycle adjustment functions, used to control the magnetic field strength of the electromagnetic coil by changing the duty cycle, thereby adjusting the valve core displacement. The temperature difference refers to the resistance difference measured by the two temperature sensors upstream and downstream of the heating element in the diversion channel. Specifically, it can be calculated by dividing the resistance difference by a preset standard resistance value, used to reflect the thermal diffusion effect when the fluid flows through the diversion channel. The coupling relationship model refers to the mathematical correlation between the diversion flow rate and the temperature difference and pressure. Specifically, it can be implemented using a linear expression including the product of the square root of the temperature difference and the pressure, used to convert sensor data into the flow rate value of the diversion channel. The flow rate ratio relationship refers to the fixed percentage of the diversion channel flow rate to the main channel flow rate. Specifically, it can be implemented using a pre-calibrated proportional coefficient, used to derive the main channel flow rate from the diversion flow rate.

[0050] Preferably, the process of establishing the mass flow compensation model includes: performing flow calibration under several different set ambient temperatures, and obtaining the temperature difference signal and the measured value of the main flow corresponding to each calibration flow point under each temperature condition;

[0051] Based on multiple sets of temperature difference signals and measured values ​​of main road flow, the ambient temperature compensation coefficient is calculated through multiple regression analysis.

[0052] Based on the ambient temperature compensation coefficient and the set reference ambient temperature, a flow compensation function is constructed;

[0053] For each target flow point after compensation, adjust the valve control signal until the actual flow rate stabilizes at the target flow point, and record the corresponding control signal parameters;

[0054] By fitting the compensated flow rate value with the corresponding control signal parameters, a linear control model characterizing the relationship between the flow rate setpoint and the control signal is established.

[0055] Preferably, step S4 specifically includes:

[0056] The control module, based on the set target flow rate, calls the established mapping relationship model, flow compensation model, and linear control model to calculate and output the corresponding control signals to the valve module;

[0057] The detection module and the fluid pathway module acquire flow-related sensor signals in real time during the control process;

[0058] The control module calculates the real-time flow rate based on the sensor signal and the mass flow compensation model;

[0059] Determine whether the deviation between the real-time flow and the target flow exceeds the allowable error range. If it does, adjust the control signal through the flow closed-loop feedback loop.

[0060] The actual displacement feedback of the valve core in the valve module is obtained, and it is determined whether there is a deviation between the actual displacement and the theoretical displacement corresponding to the control signal. If there is a deviation, the control signal is collaboratively corrected through the displacement closed-loop feedback loop.

[0061] When establishing the shunt-mainstream flow coupling model, the host computer first sets multiple calibration flow points, and a standard flow source inputs the corresponding flow into the mainstream path. The control module stabilizes the mainstream flow at the target value by adjusting the PWM duty cycle, while the detection module collects the resistance value of the temperature sensor and calculates the temperature difference, and the pressure sensor simultaneously collects the inlet pressure data. Based on the product relationship between temperature difference and pressure, a shunt flow calculation model is established. Then, combined with the fixed proportion of the shunt flow to the mainstream flow, the actual flow value of the mainstream path is derived. The final mapping table associates and stores the mainstream flow with the corresponding temperature difference and pressure data, providing a data foundation for subsequent calibration.

[0062] In some implementations, establishing the flow compensation model specifically includes: under three different ambient temperatures of 25℃, 35℃, and 45℃, collecting the ΔTᵢ and ΔTᵢ corresponding to each calibration flow point at each ambient temperature. The ambient temperature compensation coefficient was calculated using a linear regression algorithm. ;based on Establish a traffic compensation model ,in To control the ambient temperature collected in real time by the module, The reference ambient temperature is 25°C; for each calibration flow point Q i Gradually adjust the duty cycle of the PWM signal of the valve module and record the main flow rate to stabilize at a certain level. Duty cycle corresponding to time Established by least squares fitting and linear relationship model ,in This is the proportionality coefficient. The minimum duty cycle for opening the valve module.

[0063] In some implementations, the calibration verification specifically includes: the host computer setting the target flow rate according to the calibration requirements. The main controller of the control module calls the stored main flow-temperature difference-pressure mapping table, flow compensation model, and linear relationship model to calculate the target duty cycle of the drive valve module. The corresponding PWM signal is output to the electromagnetic coil of the valve module through the PWM drive unit; the detection module collects the ΔT in the diversion channel and the P at the inlet of the fluid passage module in real time, and the main controller calculates the real-time flow rate according to the coupling relationship model and the compensation model. ,like If the error exceeds the preset error threshold of 0.5%FS, then flow closed-loop adjustment will be implemented. The value; simultaneously, the displacement sensor built into the valve module collects the actual displacement of the valve core in real time. If the actual displacement is consistent with... If the corresponding theoretical displacement deviation exceeds 0.01mm, the duty cycle of the PWM signal is corrected through a displacement closed-loop adjustment until... Stable at Within ±0.5%FS, complete the current target flow point. Calibration and verification.

[0064] refer to Figure 2 Secondly, the present invention also provides an embodiment of a split-type mass flow controller calibration system for performing any of the split-type mass flow controller calibration methods described in the present invention, comprising a control module, a valve module, a detection module, and a fluid passage module.

[0065] The control module includes a main controller, a data acquisition unit for acquiring sensor signals, a drive unit for driving the valve module, and a communication unit for communicating with external devices.

[0066] The valve module is used to receive control signals from the drive unit and adjust the flow channel opening to control the fluid flow rate;

[0067] The detection module is used to detect the temperature difference signal generated by the flowing fluid;

[0068] The fluid flow path module is used to provide a fluid flow path and detect inlet pressure signals;

[0069] The control module, valve module, detection module and fluid passage module are connected by a detachable interface to form an assemblable fluid control loop.

[0070] Preferably, the acquisition unit has a signal conditioning circuit for processing the signals output by the corresponding sensors; the storage unit is connected to the main controller and is used to store the reference data, mapping table, compensation coefficients and model parameters of the calibration process.

[0071] Preferably, the surface of the magnetic valve core is covered with a wear-resistant layer, and the inner wall of the valve cavity is provided with a sealing ring; the displacement sensor is connected to the control module through the electrical interface.

[0072] Preferably, the heating element of the detection module is a platinum resistance thermometer, and it is equipped with an overheat protection circuit; the temperature sensor can be an NTC thermistor.

[0073] refer to Figure 3 The present invention also provides a split-type mass flow control device, including any of the split-type mass flow controller calibration systems described above, and further including a housing with independent chambers and an adjustable fixing bracket. The interior of the housing is divided into multiple independent chambers by heat-insulating partitions, which are respectively used to accommodate the control module, valve module and detection module. The adjustable fixing bracket is fixed to the outer wall of the housing, and the fluid passage module is fixed to the fixing bracket by a snap-fit ​​structure. The front of the housing is provided with an operation panel, which is provided with a display screen, buttons and detachable electrical and fluid interfaces of each unit.

[0074] As can be seen from the above, the split-type mass flow controller calibration method, system and equipment provided in this application, through the split modular design combined with multi-parameter coupling calculation of temperature difference, pressure data and environmental compensation, and the use of flow closed-loop and valve core displacement closed-loop collaborative control, solves the problems of difficult disassembly and maintenance, insufficient detection accuracy and poor environmental adaptability of traditional equipment. It has the advantages of modular disassembly and assembly convenience, high accuracy of multi-parameter coupling compensation and strong stability of dual closed-loop collaborative control.

[0075] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0076] Finally, it should be noted that the split-type mass flow controller device disclosed in the embodiments of the present invention is only a preferred embodiment of the present invention and is only used to illustrate the technical solutions of the present invention, not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A calibration method for a split-type mass flow controller, characterized in that, Includes the following steps: S1: The control module, valve module, detection module and fluid passage module are set up separately to form a fluid control loop including several calibrated flow points. A temperature sensor is deployed in the fluid control loop to obtain the initial temperature parameters. The valve module is closed to make the loop in a zero flow state. The sensor data is collected synchronously through the detection module. After removing abnormal values, the average value of the valid data is taken. The reference temperature difference between the liquid inlet end and the liquid outlet end of the fluid control loop is calculated and the reference temperature difference is set as the zero reference. S2: Based on the zero-point reference, the control module drives the standard flow source to output several calibration flow points. Under the steady-state condition of the calibration flow points, the temperature difference signal and the inlet pressure signal are collected synchronously. Based on the temperature difference signal and the inlet pressure signal, a mapping relationship model between the main road mass flow rate and the temperature difference and inlet pressure is established. S3: Obtain the parameter changes in the mapping relationship model under several different ambient temperatures, fit the ambient temperature compensation coefficient through a multiple regression algorithm, construct a mass flow compensation model that integrates the ambient temperature compensation coefficient, and establish a linear control model between the flow setpoint and the control signal based on the calibration data. S4: Set the target mass flow rate, and call the linear control model and the mass flow rate compensation model to calculate the initial control parameters; Based on the real-time acquired temperature difference signal and inlet pressure signal, the real-time mass flow rate is calculated through the mapping relationship model and the mass flow rate compensation model.

2. The calibration method for a split-type mass flow controller according to claim 1, characterized in that, Also includes: The control module, valve module, detection module, and fluid passage module are assembled into a complete flow control loop through a preset detachable interface. The output end of the standard flow source is sealed and connected to the main passage inlet of the fluid passage module. The host computer sends an initialization command to the control module through the communication unit. The control module drives the valve module to remain in a normally closed state, and at the same time controls the heating element in the detection module to be energized to raise the temperature and maintain a constant temperature. At this time, the temperature sensors symmetrically arranged upstream and downstream of the heating element are recorded. Temperature sensor initial resistance value 0. Initial resistance value 0, calculate the initial temperature difference ΔT0.

3. The calibration method for a split-type mass flow controller according to claim 1, characterized in that, The steps for establishing the mapping relationship model include: the host computer sets N calibration flow points Q1, Q2, ..., Q6, covering the range from 0 to the maximum range, according to the range of the mass flow controller. n The standard flow source is controlled to sequentially output the corresponding flow rate to the main channel of the fluid pathway module; for each calibrated flow rate point Q i The control module adjusts the duty cycle of the PWM signal output to the solenoid coil of the valve module through the PWM drive unit, so that the flow rate in the main passage is stabilized at Q. i Simultaneously, the detection module collects temperature data from the temperature sensor within the diversion channel. Temperature sensor Real-time resistance value Real-time resistance value Calculate the temperature difference Where R0 is a preset standard resistance value, and real-time pressure data collected by the fluid passage inlet pressure sensor is acquired. ;based on and Establish traffic splitting Coupling model between the two ,in The diversion coefficient is used to deduce the main flow rate based on the flow ratio between the diversion channel and the main channel. This forms a mapping table of main flow rate, temperature difference, and pressure, which is then stored in the main controller of the control module.

4. The calibration method for a split-type mass flow controller according to claim 1, characterized in that, The process of establishing the mass flow compensation model includes: performing flow calibration under several different set ambient temperatures, and obtaining the temperature difference signal and the measured value of the main flow at each calibration flow point under each temperature condition; Based on multiple sets of temperature difference signals and measured values ​​of main road flow, the ambient temperature compensation coefficient is calculated through multiple regression analysis. Based on the ambient temperature compensation coefficient and the set reference ambient temperature, a flow compensation function is constructed; For each target flow point after compensation, adjust the valve control signal until the actual flow rate stabilizes at the target flow point, and record the corresponding control signal parameters; By fitting the compensated flow rate value with the corresponding control signal parameters, a linear control model characterizing the relationship between the flow rate setpoint and the control signal is established.

5. The calibration method for a split-type mass flow controller according to claim 1, characterized in that, Step S4 includes: The control module, based on the set target flow rate, calls the established mapping relationship model, flow compensation model, and linear control model to calculate and output the corresponding control signals to the valve module; The detection module and the fluid pathway module collect flow-related sensor signals in real time during the control process; The control module calculates the real-time flow rate based on the sensor signal and the mass flow compensation model; Determine whether the deviation between the real-time flow and the target flow exceeds the allowable error range. If it does, adjust the control signal through the flow closed-loop feedback loop. The actual displacement feedback of the valve core in the valve module is obtained, and it is determined whether there is a deviation between the actual displacement and the theoretical displacement corresponding to the control signal. If there is a deviation, the control signal is collaboratively corrected through the displacement closed-loop feedback loop.

6. A split-type mass flow controller calibration system, used in the split-type mass flow controller calibration method as described in any one of claims 1-5, characterized in that, include: It includes a control module, a valve module, a detection module, and a fluid pathway module. The control module includes a main controller, a data acquisition unit for acquiring sensor signals, a drive unit for driving the valve module, and a communication unit for communicating with external devices. The valve module is used to receive control signals from the drive unit and adjust the flow channel opening to control the fluid flow rate; The detection module is used to detect the temperature difference signal generated by the flowing fluid; The fluid flow path module is used to provide a fluid flow path and detect inlet pressure signals; The control module, valve module, detection module and fluid passage module are connected by a detachable interface to form a fluid control loop including several calibrated flow points.

7. The split-type mass flow controller calibration system according to claim 6, characterized in that, The fluid pathway module also includes a displacement sensor, and the acquisition unit includes several signal conditioning circuits for processing the signals output by the corresponding sensors. The control module also includes a storage unit connected to the main controller for storing reference data, mapping tables, compensation coefficients, and model parameters of the calibration process.

8. The split-type mass flow controller calibration system according to claim 7, characterized in that, It also includes a magnetic valve core, which further includes a valve cavity. The surface of the magnetic valve core is covered with a wear-resistant layer, and the inner wall of the valve cavity is provided with a sealing ring. The displacement sensor is connected to the control module through an electrical interface.

9. The split-type mass flow controller calibration system according to claim 6, characterized in that, The heating element of the detection module is a platinum resistance thermometer, and it is equipped with an overheat protection circuit; the temperature sensor is an NTC thermistor.

10. A split-type mass flow control device, characterized in that, The system includes the split-type mass flow controller calibration system according to any one of claims 6-9, and further includes a housing with independent chambers and an adjustable fixing bracket. The interior of the housing is divided into multiple independent chambers by heat-insulating partitions for accommodating the control module, valve module and detection module respectively. The adjustable fixing bracket is fixed to the outer wall of the housing, and the fluid passage module is fixed to the fixing bracket by a snap-fit ​​structure. The front of the housing is provided with an operation panel, which includes a display screen, buttons and detachable electrical and fluid interfaces for each unit.

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