A flow control method for a mass flow controller

Abstract

The invention discloses a flow control method of a mass flow controller, relates to the technical field of flow control, and comprises obtaining historical adjustment data of the mass flow controller, including an initial opening degree, a terminal opening degree and a corresponding control duration; solves the technical problem that when the mass flow controller reaches a warning flow, there is a gap between the actual flow sent and the preset flow, resulting in inaccurate flow control; by obtaining the corresponding sending flow of a flow detector when the warning flow is reached, solves the problem that in actual application, when the flow detector reaches the warning flow, the mass flow controller sends data without considering the flow loss during the period when the flow detector data is sent to the controller and then the controller sends a control signal to the valve, resulting in a gap between the actual flow and the warning flow after the valve is adjusted; the invention is beneficial to the use of the mass flow controller and improves the accuracy of flow control.

Description

Technical Field

[0001] The present invention relates to the technical field of flow control, and in particular to a flow control method of a mass flow controller. Background Art

[0002] Mass flow controllers are core components in semiconductor process equipment and are widely used in semiconductors, photovoltaics, fuel cells, vacuum technology and other fields. Mass flow controllers usually include valves and flow detectors. In semiconductor processes, the flow rate of process fluids (such as process gases) is closely related to process effects. The most important requirement of semiconductor equipment for fluid mass flow controllers is high precision. When providing various gases for manufacturing semiconductors to semiconductor manufacturing equipment, mass flow controllers are required to be installed in the flow paths of various gases. The gas flows are adjusted separately by mass flow controllers. Mass flow controllers can only achieve high-precision flow detection.

[0003] However, in the actual application of mass flow controller, due to the existence of data transmission and processing time, the data sent by the flow detector may have a certain delay, and the control signal received by the valve may also have a certain delay. At the same time, the impact of the fluctuating flow during valve adjustment on the actual flow causes a gap between the actual sent flow and the preset flow when the warning flow is reached, resulting in inaccurate flow control. Based on this, a flow control method for a mass flow controller is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a flow control method for a mass flow controller, which solves the technical problem that when the mass flow controller reaches the warning flow, there is a gap between the actual flow sent and the preset flow, resulting in inaccurate flow control.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A flow control method for a mass flow controller comprises the following steps:

[0007] Step 1: Obtain historical adjustment data of the mass flow controller, including the initial opening degree, the final opening degree and the corresponding control time;

[0008] Step 2: Analyze the historical control data to obtain the valve's tension reduction rate and expansion rate;

[0009] Step 3: Analyze the time between the flow data sent by the flow detector and the time when the valve receives the control signal to obtain the signal delay time of the valve;

[0010] Step 4: Analyze the historical control data of the mass flow controller to obtain the tension reduction flow rate table and expansion flow rate table corresponding to the mass flow controller;

[0011] Step 5: Based on the valve's warning flow, real-time flow rate, pre-adjusted opening and real-time opening, combined with the valve's tension reduction rate, expansion rate, signal delay duration, tension reduction flow rate table and expansion flow rate table, calculate the flow detector's corresponding sending flow value.

[0012] As a further solution of the present invention: the specific method of obtaining the tension reduction rate corresponding to the valve is:

[0013] A1: Obtain the historical adjustment data of the mass flow controller for the past n times, n≥1;

[0014] A2: Calculate the difference Cn between the final opening degree and the initial opening degree in each historical adjustment data, and mark the negative value as Ca and the positive value as Cb, where a+b≤n, a≥1 and b≥1;

[0015] A3: Obtain the control duration corresponding to each negative value Ca, mark it as Ta, and mark the ratio between the absolute value of the negative value Ca and its corresponding control duration as the control rate Da;

[0016] A4: Obtain the value De in Da that meets the first preset condition, and compare and analyze e with the preset value Y1. When e≥Y1, the mean value D1p of Da is used as the valve corresponding tension reduction rate JS. When e<Y1, Da is arranged in order from small to large, and then the median is taken as the valve corresponding tension reduction rate JS.

[0017] As a further solution of the present invention: the specific method of obtaining the expansion rate corresponding to the valve is:

[0018] The control rate Eb corresponding to each positive value Cb is obtained by the same method as in step A3, and then the value Ef that meets the second preset condition is obtained. Ef is analyzed by the same method as in step A4 to obtain the corresponding expansion rate KS of the valve.

[0019] As a further solution of the present invention: the first preset condition is specifically: |Da-D1p|>Y2, Y2 is a preset value, and the second preset condition is specifically: |Eb-D2p|>Y3, wherein D1p and D2p are the averages of Da and Eb respectively, and Y2 and Y3 are both preset values.

[0020] As a further solution of the present invention: the specific method of obtaining the signal delay time corresponding to the valve is:

[0021] Get the time interval HTn between the flow detector transmitting flow data and the valve receiving the control signal for the past n times, calculate and obtain the variance value W corresponding to HTn, when the variance value W satisfies W≤Y4, use the mean HTp of HTn as the signal delay time K1 corresponding to the valve, otherwise, delete the values ​​with large differences in HTn and recalculate the variance until W≤Y4 is satisfied, and record the number h of deletions at the same time, when h<Y5 is satisfied, use HTp as the signal delay time K1 corresponding to the valve, otherwise, use the mean of the maximum and minimum values ​​of HTn as the signal delay time K1 corresponding to the valve.

[0022] As a further solution of the present invention, the method of deleting the values ​​with large differences in HTn is:

[0023] According to the value of |HTj-HTp|, the corresponding HTj value is deleted in descending order, and the variance of the remaining HTj is recalculated after each deletion, and the number of deletions is recorded until W≤Y4, n≥j≥1 is satisfied.

[0024] As a further solution of the present invention: the specific method of obtaining the tension reduction flow rate table and the expansion flow rate table corresponding to the mass flow controller is:

[0025] Obtain the terminal opening degrees in the historical adjustment data corresponding to each negative value Ca, and mark each terminal opening degree as a tension reduction node, and mark the area between each two adjacent tension reduction nodes as a tension reduction control interval; obtain the flow state values ​​corresponding to the valve in each tension reduction control interval and the maintenance time corresponding to each flow state value;

[0026] The ratio of the product of the flow state value corresponding to each tension reduction control interval and its corresponding maintenance time to the total value of the maintenance time is marked as the tension reduction interval flow rate corresponding to each tension reduction control interval, and then the tension reduction flow rate table corresponding to the mass flow controller is obtained. The expansion flow rate table can be obtained in the same way.

[0027] As a further solution of the present invention: the specific method of obtaining the transmission flow value of the flow detector is as follows;

[0028] The difference between the pre-adjusted opening and the real-time opening is marked as YK, the real-time flow rate is marked as L, and the warning flow is marked as YJ. The sending flow value X is obtained through the formula X+K1×L+BD=YJ, where BD is the fluctuating flow corresponding to the valve, and the specific value of BD depends on the positive or negative value of YK.

[0029] As a further solution of the present invention: the specific method of obtaining the fluctuating flow rate corresponding to the valve is:

[0030] A01: When YK is a positive value, the expansion control interval required for valve adjustment is obtained according to the pre-adjustment opening degree and real-time opening degree of the valve, and the interval path lengths Jv, Q1 and Q2 corresponding to the complete interval and the first and last intervals are obtained, where v refers to the number of complete intervals, v≥1;

[0031] A02: Calculate the control duration JAv corresponding to each complete interval using the formula Jv / KS=JAv; calculate the control durations QA1 and QA2 corresponding to the first and last intervals using the formulas Q1 / KS=QA1 and Q2 / KS=QA2;

[0032] By formula ; Calculate and obtain the fluctuating flow BD corresponding to the valve, where ZAr is the expansion interval flow rate corresponding to each complete interval, MA1 and MA2 are the expansion interval flow rates corresponding to the first and last intervals, respectively. ZAr, MA1 and MA2 are all obtained from the expansion flow rate table, v≥r≥1.

[0033] As a further solution of the present invention: when YK is a negative value, the tension-reduction control interval required for valve adjustment is obtained according to the pre-adjusted opening degree and real-time opening degree of the valve, and the corresponding interval path length of the complete interval and the interval path lengths corresponding to its first and last intervals are obtained. At the same time, the tension-reduction flow interval flow velocities corresponding to each complete interval and the first and last intervals are obtained from the tension-reduction flow rate table. Combined with the tension-reduction rate JS corresponding to the valve, the fluctuating flow BD corresponding to the valve is obtained in the same manner as steps A01-A02.

[0034] Beneficial effects of the present invention:

[0035] (1) The present invention can more accurately evaluate the delay in the actual control process of the valve by calculating the signal delay time of the valve, reduce the error caused by the delay, improve the response speed and accuracy of the control system, and make the flow control more precise;

[0036] (2) The present invention calculates the valve tension reduction rate and expansion rate through historical data to provide an accurate reference basis for real-time control of the valve, thereby improving the accuracy of valve adjustment;

[0037] (3) The present invention solves the problem that when the mass flow controller in actual application sends data when the flow detector reaches the warning flow, the flow detector does not consider the flow loss during the period when the flow detector data is sent to the controller and then the controller sends the control signal to the valve, resulting in a gap between the actual flow and the warning flow after the valve is adjusted, by obtaining the sending flow corresponding to the flow detector when the warning flow is reached. This is conducive to the use of the mass flow controller and improves the accuracy of flow control. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below in conjunction with the accompanying drawings.

[0039] Figure 1 It is a schematic diagram of the framework structure of the method of the present invention;

[0040] Figure 2 It is a schematic diagram of the framework structure of the mass flow controller of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Embodiment 1

[0043] See also Figure 1-Figure 2 As shown, the present invention is a flow control method of a mass flow controller, comprising the following steps:

[0044] Step 1: Obtain historical control data of the mass flow controller, the historical control data including the initial opening degree, final opening degree and corresponding control duration of the valve;

[0045] It should be noted that the mass flow controller includes a controller, a valve and a flow detector;

[0046] Step 2: Analyze the historical control data of the mass flow controller to obtain the corresponding decompression rate and expansion rate of the valve. The specific method is as follows:

[0047] The specific method for obtaining the corresponding tension reduction rate of the valve is:

[0048] A1: Obtain the historical adjustment data of the mass flow controller for the past n times. The historical adjustment data includes the initial opening degree, the final opening degree and the corresponding control duration. n is a preset value. Here, n times refers to the preset number of 188 times from the moment the data is obtained, and 188≥n≥1.

[0049] A2: Obtain the difference between the final opening degree and the initial opening degree in each historical adjustment data, and mark it as Cn, mark the negative value as Ca, and mark the positive value as Cb, where a+b≤n, a≥1 and b≥1, where a represents the number of negative values ​​in Cn, and b represents the number of positive values ​​in Cn;

[0050] A3: Obtain the control duration corresponding to each negative value Ca, and mark it as Ta. Obtain the control rate Da corresponding to each negative value Ca through the formula |Ca| / Ta=Da.

[0051] A4: Obtain the values ​​in Da that meet the first preset condition and mark them as De, where e refers to the number of values ​​in Da that meet the first preset condition, satisfying n≥a≥e≥1;

[0052] Compare and analyze e with the preset value Y1. When e≥Y1 is satisfied, the mean value D1p of Da is used as the corresponding valve tension reduction rate JS. The specific calculation formula of D1p is: D1p=(D1+D2+……+Dd) / d, where n≥e≥d≥1. The specific value of the preset value Y1 is formulated by relevant personnel according to actual needs;

[0053] When e<Y1, Da is arranged in order from small to large, and then the median is taken as the corresponding valve tension reduction rate JS. The specific method of obtaining the median of Da is as follows: when a is an odd number, the corresponding valve tension reduction rate JS is obtained by the formula JS=D[(d+1) / 2]; when a is an even number, the corresponding valve tension reduction rate JS is obtained by the formula JS=[D(d / 2)+D(d / 2+1)] / 2;

[0054] The first preset condition is specifically: |Da-D1p|>Y2, where Y2 is a preset value, and the specific value is determined by relevant personnel based on actual needs and application scenarios;

[0055] The specific method for obtaining the corresponding expansion rate of the valve is:

[0056] The control rates Eb corresponding to the positive values ​​Cb are obtained by the same method as in step A3, and then the values ​​Ef satisfying the second preset condition are obtained, where n≥b≥f≥1, and then Ef is analyzed by the same method as in step A4 to obtain the corresponding expansion rate KS of the valve;

[0057] The second preset condition is specifically: |Eb-D2p|>Y3, where D2p is the average value of Eb, and Y2 is the preset value. The specific value is formulated by relevant personnel according to actual needs and application scenarios;

[0058] Using historical data, the valve's tension reduction rate JS and expansion rate KS are calculated respectively, providing an accurate reference for real-time control and improving the accuracy of valve adjustment.

[0059] Step 3: Obtain the time between the flow detector sending flow data and the valve receiving the control signal, and analyze it to obtain the signal delay time corresponding to the valve. The specific method is as follows:

[0060] Obtain the time between the data sending time corresponding to the flow detector in the past n times and the time between the valve receiving the control signal, that is, the time interval between the flow detector sending the flow data and the valve receiving the control signal, and mark it as HTn;

[0061] By formula , calculate the variance value W corresponding to HTn, where HTp is the mean value of HTn, n≥j≥1;

[0062] When the variance value W satisfies W≤Y4, HTp is used as the signal delay time K1 corresponding to the valve; when W>Y4, the corresponding HTj value is deleted in descending order according to the value of |HTj-HTp|, and the variance of the remaining HTj is recalculated after each deletion, and the number h of deleted HTj is recorded until W≤Y4 is satisfied. The specific value of Y4 needs to be formulated by relevant personnel according to specific application scenarios and requirements;

[0063] When h<Y5 is satisfied, HTp is used as the signal delay time K1 corresponding to the valve; when h≥Y5 is satisfied, the average of the maximum and minimum values ​​in HTj is used as the signal delay time K1 corresponding to the valve, where Y5 is a preset value, and the specific value needs to be formulated by relevant personnel according to specific application scenarios and requirements;

[0064] In actual applications, after the controller receives the flow data from the flow detector, it takes a certain amount of time to respond and send a regulating signal to adjust the valve. There is a signal delay in this process, which causes a deviation between the actual flow and the expected flow. By analyzing historical data and calculating the valve signal delay time K1, the delay in the actual control process of the valve can be more accurately evaluated, the error caused by the delay can be reduced, the response speed and accuracy of the control system can be improved, and the flow control can be more precise.

[0065] Step 4: Analyze the historical control data of the mass flow controller to obtain the tension reduction flow rate table and expansion flow rate table corresponding to the mass flow controller. The specific method is as follows:

[0066] Obtain the terminal opening degrees in the historical adjustment data corresponding to each negative value Ca, and mark each terminal opening degree as a tension reduction node, and mark the area between each two adjacent tension reduction nodes as a tension reduction control interval;

[0067] Obtain the flow state values ​​corresponding to the valve in each tension reduction control interval and the corresponding maintenance time of each flow state value;

[0068] The ratio between the product of the flow state value corresponding to each tension reduction control interval and the corresponding maintenance time and the total value of the maintenance time is marked as the tension reduction interval flow rate corresponding to each tension reduction control interval, thereby obtaining the tension reduction flow rate table corresponding to the mass flow controller;

[0069] The expansion flow rate table corresponding to the mass flow controller can be obtained in the same way;

[0070] Step 5: Obtain the warning flow, real-time flow rate, pre-adjusted opening and real-time opening of the valve, analyze it in combination with the valve's tension reduction rate, expansion rate, signal delay duration, tension reduction flow rate table and expansion flow rate table, and then obtain the corresponding sending flow value of the flow detector. The specific method is as follows:

[0071] The difference between the pre-adjusted opening degree and the real-time opening degree is marked as YK, the real-time flow rate is marked as L, and the warning flow rate is marked as YJ;

[0072] The flow rate value X corresponding to the flow detector is obtained through the formula X+K1×L+BD=YJ, where BD is the fluctuating flow rate corresponding to the valve;

[0073] The sending flow rate corresponding to the flow detector when the warning flow rate is reached is obtained, which solves the problem that when the mass flow controller sends data when the flow detector reaches the warning flow rate in actual applications, the flow loss during the period when the flow detector data is sent to the controller and then the controller sends the control signal to the valve is not considered, resulting in a gap between the actual flow and the warning flow after the valve is adjusted. This is conducive to the use of mass flow controllers and improves the accuracy of flow control.

[0074] Embodiment 2

[0075] As the second embodiment of the present invention, when the present application is implemented, compared with the first embodiment, the technical solution of the present embodiment is different from that of the first embodiment only in the present embodiment;

[0076] The specific method of obtaining the fluctuating flow corresponding to the valve is:

[0077] A01: When YK is a positive value, the expansion control interval that the valve needs to pass through during adjustment is obtained according to the pre-adjustment opening degree and the real-time opening degree of the valve, and the corresponding interval path length of the complete interval is obtained, and it is marked as Jv, where v refers to the number of complete intervals, v≥1, and the interval path lengths corresponding to the first and last intervals are obtained, and they are marked as Q1 and Q2 respectively;

[0078] A02: Calculate the control duration JAv corresponding to each complete interval using the formula Jv / KS=JAv;

[0079] By using the formulas Q1 / KS=QA1 and Q2 / KS=QA2, the control durations QA1 and QA2 corresponding to the first and last intervals are calculated respectively;

[0080] By formula ; Calculate and obtain the fluctuating flow BD corresponding to the valve, where Zr is the expansion interval flow rate corresponding to each complete interval, MA1 and MA2 are the expansion interval flow rates corresponding to the first and last intervals, ZAr, MA1 and MA2 are all obtained from the expansion flow rate table, v≥r≥1; JAr is the different control duration corresponding to each complete interval, and JAr and ZAr are in a one-to-one correspondence;

[0081] When YK is a negative value, the tension reduction control interval required for valve adjustment is obtained according to the pre-adjusted opening degree and real-time opening degree of the valve, and the corresponding interval path length of the complete interval and the interval path lengths corresponding to the first and last intervals are obtained. At the same time, the tension reduction flow interval flow rates corresponding to each complete interval and the first and last intervals are obtained from the tension reduction flow rate table. Combined with the corresponding tension reduction rate JS of the valve, the corresponding fluctuating flow BD of the valve is obtained in the same way as steps A01-A02;

[0082] According to the different adjustment conditions of the valve, the fluctuating flow BD corresponding to the valve is obtained, which is convenient for accurately calculating the sending flow value X corresponding to the flow detector, is conducive to the use of the mass flow controller, and improves the accuracy of flow control.

[0083] Embodiment 3

[0084] As the third embodiment of the present invention, when the present application is specifically implemented, compared with the first and second embodiments, the technical solution of this embodiment is to combine the solutions of the first and second embodiments mentioned above for implementation.

[0085] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters and thresholds in the formula are set by technicians in this field according to actual conditions.

[0086] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A flow control method for a mass flow controller, characterized in that: The following steps are involved: Step 1: Obtain historical adjustment data of the mass flow controller, including the initial opening degree, the final opening degree and the corresponding control time; Step 2: Analyze the historical control data to obtain the valve's tension reduction rate and expansion rate; Step 3: Analyze the time between the flow data sent by the flow detector and the time when the valve receives the control signal to obtain the signal delay time of the valve; Step 4: Analyze the historical control data of the mass flow controller to obtain the tension reduction flow rate table and expansion flow rate table corresponding to the mass flow controller; Step 5: According to the warning flow, real-time flow rate, pre-adjusted opening and real-time opening of the valve, combined with the valve's tension reduction rate, expansion rate, signal delay time, tension reduction flow rate table and expansion flow rate table, calculate the corresponding sending flow value of the flow detector; The specific method for obtaining the corresponding tension reduction rate of the valve is: A1: Obtain the historical adjustment data of the mass flow controller for the past n times, n≥1; A2: Calculate the difference Cn between the final opening degree and the initial opening degree in each historical adjustment data, and mark the negative value as Ca and the positive value as Cb, where a+b≤n, a≥1 and b≥1, a represents the number of negative values ​​in Cn, and b represents the number of positive values ​​in Cn; A3: Obtain the control duration corresponding to each negative value Ca, mark it as Ta, and mark the ratio between the absolute value of the negative value Ca and the corresponding control duration as the control rate Da; A4: Obtain the value De in Da that meets the first preset condition, compare and analyze e with the preset value Y1, and when e≥Y1 is satisfied, use the mean value D1p of Da as the corresponding valve tension reduction rate JS, and when e<Y1, arrange Da in ascending order, and then take the median as the corresponding valve tension reduction rate JS; where e refers to the number of values ​​in Da that meet the first preset condition; The specific method for obtaining the expansion rate corresponding to the valve is: The control rates Eb corresponding to the positive values ​​Cb are obtained by the same method as in step A3, and then the values ​​Ef satisfying the second preset condition are obtained. Ef is analyzed by the same method as in step A4, and the corresponding expansion rate KS of the valve is obtained. The first preset condition is specifically: |Da-D1p|>Y2, Y2 is a preset value, and the second preset condition is specifically: |Eb-D2p|>Y3, where D1p and D2p are the averages of Da and Eb respectively, and Y2 and Y3 are both preset values; The specific method to obtain the signal delay time corresponding to the valve is: Obtain the time interval HTn between the flow detector transmitting the flow data out of the flow detector and the valve receiving the control signal for the past n times, calculate and obtain the variance value W corresponding to HTn, when the variance value W satisfies W≤Y4, use the mean value HTp of HTn as the signal delay time K1 corresponding to the valve, otherwise, delete the values ​​with large differences in HTn and recalculate the variance until W≤Y4 is satisfied, and record the number h of deletions at the same time, when h<Y5 is satisfied, use HTp as the signal delay time K1 corresponding to the valve, otherwise, use the mean of the maximum and minimum values ​​of HTn as the signal delay time K1 corresponding to the valve; Y4 and Y5 are both preset values; The specific method for obtaining the tension reduction flow rate table and expansion flow rate table corresponding to the mass flow controller is: Obtain the terminal opening degrees in the historical adjustment data corresponding to each negative value Ca, and mark each terminal opening degree as a tension reduction node, and mark the area between each two adjacent tension reduction nodes as a tension reduction control interval; Obtain the flow state values ​​corresponding to the valve in each tension reduction control interval and the corresponding maintenance time of each flow state value; The ratio between the product of the flow state value corresponding to each tension reduction control interval and its corresponding maintenance time and the total value of the maintenance time is marked as the tension reduction interval flow rate corresponding to each tension reduction control interval, and then the tension reduction flow rate table corresponding to the mass flow controller is obtained. The expansion flow rate table can be obtained in the same way; The specific method for obtaining the sending flow value of the flow detector is as follows; The difference between the pre-adjusted opening and the real-time opening is marked as YK, the real-time flow rate is marked as L, and the warning flow is marked as YJ. The sending flow value X is obtained through the formula X+K1×L+BD=YJ, where BD is the fluctuating flow corresponding to the valve. The specific value of BD depends on the positive or negative value of YK. The specific method of obtaining the fluctuating flow corresponding to the valve is: A01: When YK is a positive value, the expansion control interval required for valve adjustment is obtained according to the pre-adjustment opening degree and real-time opening degree of the valve, and the interval path lengths Jv, Q1 and Q2 corresponding to the complete interval and the first and last intervals are obtained, where v refers to the number of complete intervals, v≥1; A02: Calculate the control duration JAv corresponding to each complete interval using the formula Jv / KS=JAv; calculate the control durations QA1 and QA2 corresponding to the first and last intervals using the formulas Q1 / KS=QA1 and Q2 / KS=QA2; By formula ; Calculate and obtain the fluctuating flow BD corresponding to the valve, where ZAr is the expansion interval flow rate corresponding to each complete interval, MA1 and MA2 are the expansion interval flow rates corresponding to the first and last intervals, ZAr, MA1 and MA2 are all obtained from the expansion flow rate table, v≥r≥1; JAr is the different control duration corresponding to each complete interval, and JAr and ZAr are in a one-to-one correspondence; When YK is a negative value, the tension reduction control interval required for valve adjustment is obtained based on the pre-adjusted opening and real-time opening of the valve, and the corresponding interval path length of the complete interval and the interval path lengths corresponding to its first and last intervals are obtained. At the same time, the tension reduction flow interval flow velocities corresponding to each complete interval and the first and last intervals are obtained from the tension reduction flow rate table. Combined with the corresponding tension reduction rate JS of the valve, the corresponding fluctuating flow BD of the valve is obtained in the same way as steps A01-A02.

2. The flow control method of a mass flow controller according to claim 1, characterized in that: The way to delete the values ​​with large differences in HTn is: According to the value of |HTj-HTp|, the corresponding HTj value is deleted in descending order, and the variance of the remaining HTj is recalculated after each deletion, and the number of deletions is recorded until W≤Y4, n≥j≥1 is satisfied.

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