Feedback control system

Abstract

The utility model provides a feedback control system, which relates to the technical field of power electronics, and comprises a control center used for respectively converting a target flow value and a target pressure value in a control instruction into a first electric signal and a second electric signal; the flow control unit is connected with the control center, and the flow control unit comprises a flow sensing unit and a first proportional valve control unit; and the pressure control unit is connected with the control center. By means of the flow sensing unit and the pressure sensing unit, flow and pressure values of a gas circuit can be detected in real time and fed back to the proportional valve control unit, and the proportional valve control unit adjusts a proportional valve in time according to the difference between the real-time flow and the target flow and the difference between the real-time pressure value and the target pressure value. Therefore, accurate flow and pressure control is realized, and stability and high efficiency of the feedback control system under various working conditions are ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power electronics, specifically, a feedback control system. BACKGROUND

[0002] In the gas path arrangement process of the chromatograph, the traditional flow controller and pressure controller can only control the flow or pressure of the gas respectively, and cannot accurately and stably control the pressure and flow, therefore, a control device capable of monitoring and feeding back the flow and pressure of the gas is urgently needed to ensure that the system can coordinate the control of the flow and pressure according to the real-time demand, so as to improve the accuracy and stability of the chromatographic separation. SUMMARY

[0003] The utility model discloses a feedback control system to improve the above problems. In order to realize the above purpose, the technical scheme adopted by the utility model is as follows:

[0004] In the first aspect, the present application provides a feedback control system, comprising:

[0005] A control center is used to convert the target flow value and the target pressure value in the control instruction into a first electric signal and a second electric signal respectively.

[0006] A flow control unit is connected with the control center, and the flow control unit comprises a flow sensing unit and a first proportional valve control unit, the output end of the flow sensing unit is connected with the input end of the first proportional valve control unit, and the first proportional valve control unit is used to judge whether to carry out proportional valve adjustment.

[0007] A pressure control unit is connected with the control center, and the pressure control unit comprises a pressure sensing unit and a second proportional valve control unit, the output end of the pressure sensor is connected with the input end of the second proportional valve control unit, and the second proportional valve control unit is used to judge whether to carry out proportional valve adjustment.

[0008] Further, the flow control unit comprises a flow sensor U7 and a first voltage amplifier H3, the positive phase output end of the flow sensor U7 is connected with the positive phase input end of the first voltage amplifier H3, the negative phase output end of the flow sensor U7 is connected with the negative phase input end of the first pressure amplifier H3, and the output end of the first voltage amplifier H3 is connected with the input end of the first proportional valve control unit.

[0009] Further, the first proportional valve control unit comprises a first comparison unit, a first control unit and a first voltage stabilizing unit,

[0010] The reverse input end of the first comparison unit is connected with the output end of the first voltage amplifier H3, and the non-inverted input end of the first comparison unit is connected with the control center;

[0011] The first control unit comprises a first transistor Q1, a first diode D1 and a first proportional valve H1, the base of the first transistor Q1 is connected with the output end of the first comparison unit, the emitter of the first transistor Q1 is connected with the negative electrode of the first diode D1, the positive electrode of the first diode D1 is grounded, the positive electrode of the first proportional valve H1 is connected with the negative electrode of the first diode D1, and the negative electrode of the first proportional valve H1 is connected with the positive electrode of the first diode D1.

[0012] The input end of the first voltage stabilizing unit is connected with the output end of the first voltage amplifier H3.

[0013] Further, the first comparison unit comprises a first operational amplifier U1, a first resistor R1, a second resistor R2 and a third resistor R3, a fourth resistor R4 and a first capacitor C1,

[0014] The output end of the first voltage amplifier H3 is connected with the inverting input end of the first operational amplifier U1 through the first resistor R1, the non-inverted input end of the first operational amplifier U1 is grounded through the fourth resistor R4, and the output end of the first operational amplifier U1 is connected with the input end of the first control unit through the second resistor R2.

[0015] The inverting input end of the first operational amplifier U1 is connected with one end of the third resistor R3 and the first capacitor C1, and the other end of the third resistor R3 and the first capacitor C1 is connected with the output end of the first operational amplifier U1.

[0016] Further, the first voltage stabilizing unit comprises a second operational amplifier U2,

[0017] The non-inverted input end of the second operational amplifier U2 is connected with the output end of the first pressure sensor H3, and the output end of the second operational amplifier U2 is connected with the inverting input end of the second operational amplifier U2.

[0018] Further, the pressure sensing unit comprises a pressure sensor U8 and a second voltage amplifier H5, the non-inverted output end of the pressure sensor U8 is connected with the non-inverted input end of the second voltage amplifier H5, the inverting output end of the pressure sensor U8 is connected with the inverting input end of the second voltage amplifier H5, and the output end of the second pressure sensor H5 is connected with the input end of the second proportional valve control unit.

[0019] Further, the second proportional valve control unit comprises a second comparison unit, a second control unit and a second voltage stabilizing unit,

[0020] The inverting input end of the second comparison unit is connected with the output end of the second pressure sensor H5, and the non-inverting input end of the second comparison unit is connected with the control center;

[0021] The second control unit comprises a second transistor Q2, a second diode D2 and a second proportional valve H2, the base of the second transistor Q2 is connected with the output end of the second comparison unit, the emitter of the second transistor Q2 is connected with the negative electrode of the second diode D2, the positive electrode of the second diode D2 is grounded, the positive electrode of the second proportional valve H2 is connected with the negative electrode of the second diode D2, and the negative electrode of the second proportional valve H2 is connected with the positive electrode of the second diode D2;

[0022] The input end of the second voltage stabilizing unit is connected with the control center.

[0023] Further, the second comparison unit comprises a third operational amplifier U3, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a second capacitor C2,

[0024] The output end of the second pressure sensor H5 is connected with the inverting input end of the third operational amplifier U3 through the fifth resistor R5, the non-inverting input end of the third operational amplifier U3 is connected with the control center through the sixth resistor R6, and the output end of the third operational amplifier U3 is connected with the input end of the second control unit through the eighth resistor R8;

[0025] The non-inverting input end of the third operational amplifier U3 is connected with the seventh resistor R7 and one end of the second capacitor C2, and the other end of the seventh resistor R7 and the second capacitor C2 is connected with the output end of the third operational amplifier U3.

[0026] Further, the second voltage stabilizing unit comprises a fourth operational amplifier U4,

[0027] The non-inverting input end of the fourth operational amplifier U4 is connected with the control center, and the output end of the fourth operational amplifier U4 is connected with the inverting input end of the fourth operational amplifier U4.

[0028] Further, the feedback control system further comprises a gas path, the gas path is a closed pipeline, the gas path has a gas inlet and an emptying port at two ends respectively, and the gas path has a flow sensing unit, a first proportional valve control unit, a pressure sensing unit, a capillary column and a second proportional valve control unit arranged in sequence inside, and the flow sensing unit is arranged at one end close to the gas inlet.

[0029] The utility model discloses the beneficial effect is:

[0030] The utility model discloses the beneficial effect is:

[0031] The other features and advantages of the utility model will be set forth in the following description, and partly become obvious from the description, or be understood by implementing the utility model embodiments. The purpose and other advantages of the utility model can be realized and obtained through the structure that is specially pointed out in the written description, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical scheme of the utility model embodiment, the following will be briefly introduced to the drawing needed to be used in the embodiment, and should be understood, the following drawings only show some certain embodiments of the utility model, therefore should not be seen as the limitation to the scope, for the ordinary skilled person in the art, under the premise of not paying the creative labor, can also obtain other related drawings according to these drawings.

[0033] Figure 1 It is flow feedback control system circuit schematic diagram that the utility model discloses the flow feedback control system circuit schematic diagram of the utility model embodiment is shown in the figure;

[0034] Figure 2 It is feedback control system flow process schematic diagram that the utility model discloses the feedback control system flow process schematic diagram of the utility model embodiment is shown in the figure;

[0035] Figure 3 It is pressure feedback control system circuit schematic diagram that the utility model discloses the pressure feedback control system circuit schematic diagram of the utility model embodiment is shown in the figure;

[0036] Figure 4 It is gas path schematic diagram that the utility model discloses the gas path schematic diagram of the utility model embodiment is shown in the figure.

[0037] Mark in the figure:

[0038] 100, flow sensing unit;200, first proportional valve control unit;300, pressure sensing unit;400, second proportional valve control unit;10, first comparison unit;20, first control unit;30, first voltage stabilizing unit;40, second comparison unit;50, second control unit;60, second voltage stabilizing unit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme of the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. The components of the embodiments of the utility model described and shown in the drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the claimed utility model, but only represents selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0040] It should be noted that: similar signs and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Meanwhile, in the description of the utility model, the terms "first", "second" and the like are only used for distinguishing description, and cannot be understood as indicating or implying relative importance.

[0041] Embodiment 1:

[0042] As shown in the figure, the embodiment provides a feedback control system. Figure 1

[0043] The control center is used for converting the target flow value and the target pressure value in the control instruction into the first electric signal and the second electric signal respectively;

[0044] The flow control unit is connected with the control center, and the flow control unit comprises a flow sensing unit 100 and a first proportional valve control unit 200, the output end of the flow sensing unit 100 is connected with the input end of the first proportional valve control unit 200, and the first proportional valve control unit 200 is used for judging whether to carry out proportional valve adjustment;

[0045] The pressure control unit is connected with the control center, and the pressure control unit comprises a pressure sensing unit 300 and a second proportional valve control unit 400, the output end of the pressure sensor is connected with the input end of the second proportional valve control unit 400, and the second proportional valve control unit 400 is used for judging whether to carry out proportional valve adjustment;

[0046] As shown in the figure, the embodiment provides a feedback control system. Figure 2 ​As shown, the feedback control system in the present application further comprises a digital-to-analog conversion module. The flow sensing unit 100 is configured to collect the flow value in the current gas path, convert the flow value into a first real-time signal, and send the first real-time signal to the corresponding first proportional valve control unit 200. The control center can receive the control instruction through the communication module, send the target flow value carried in the control instruction to the digital-to-analog conversion module, convert the target flow value into a first electric signal Vot1 by the digital-to-analog conversion module, and send the first electric signal Vot1 to the first proportional valve control unit 200. The first proportional valve control unit 200 can adjust the opening and closing degree of the proportional valve according to the first real-time signal and the first electric signal Vot1, so that the difference between the actual flow value of the adjusted gas path and the target flow value is less than or equal to the preset threshold value.

[0047] Further, the pressure sensing unit 300 is configured to collect the pressure value in the current gas path, convert the pressure value into a second real-time signal, and send the second real-time signal to the corresponding second proportional valve control unit 400. The control center can receive the control instruction through the communication module, send the target pressure value carried in the control instruction to the digital-to-analog conversion module, convert the target pressure value into a second electric signal Vot2 by the digital-to-analog conversion module, and send the second electric signal Vot2 to the second proportional valve control unit 400. The second proportional valve control unit 400 can adjust the opening and closing degree of the proportional valve according to the second real-time signal and the second electric signal Vot2, so that the difference between the actual pressure value of the adjusted gas path and the target pressure value is less than or equal to the preset threshold value.

[0048] The flow control unit comprises a flow sensor U7 and a first voltage amplifier H3. The positive phase output end of the flow sensor U7 is connected with the positive phase input end of the first voltage amplifier H3, the negative phase output end of the flow sensor U7 is connected with the negative phase input end of the first pressure amplifier H3, and the output end of the first voltage amplifier H3 is connected with the input end of the first proportional valve control unit 200. The first voltage amplifier H3 can amplify and zero-point drift compensate the signal collected by the flow sensor U7, realize accurate, stable and anti-interference flow signal transmission, and thus improve the accuracy of subsequent proportional valve control.

[0049] The first proportional valve control unit 200 includes a first comparing unit 10, a first control unit 20, and a first voltage stabilizing unit 30. The inverting input terminal of the first comparing unit 10 is connected to the output terminal of the first voltage amplifier H3, and the non-inverting input terminal of the first comparing unit 10 is connected to the control center. The first control unit 20 includes a first transistor Q1, a first diode D1, and a first proportional valve H1. The base of the first transistor Q1 is connected to the output terminal of the first comparing unit 10, the emitter of the first transistor Q1 is connected to the cathode of the first diode D1, the anode of the first diode D1 is grounded, the anode of the first proportional valve H1 is connected to the cathode of the first diode D1, and the cathode of the first proportional valve H1 is connected to the anode of the first diode D1. The input terminal of the first voltage stabilizing unit 30 is connected to the output terminal of the first voltage amplifier H3.

[0050] The first comparison unit 10 achieves rapid detection of flow deviation by comparing the output signal of the first voltage amplifier H3 with the first electrical signal, so that the feedback control system can respond to changing needs in a timely manner; the first control unit 20 converts the comparison result into a precise adjustment signal of the proportional valve through the first transistor Q1 and the first diode D1, thereby effectively controlling the gas path flow; the introduction of the first voltage stabilizing unit 30 ensures the stability of the output signal of the first voltage amplifier H3, prevents control inaccuracy and system instability caused by voltage fluctuations, further improves control accuracy and reliability, and makes the flow control process more accurate, efficient and stable.

[0051] The first comparison unit 10 includes a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a first capacitor C1. The output of the first voltage amplifier H3 is connected to the inverting input of the first operational amplifier U1 via the first resistor R1. The non-inverting input of the first operational amplifier U1 is grounded via the fourth resistor R4. The output of the first operational amplifier U1 is connected to the input of the first control unit 20 via the second resistor R2. The inverting input of the first operational amplifier U1 is connected to the third resistor R3 and one end of the first capacitor C1. The other ends of the third resistor R3 and the first capacitor C1 are connected to the output of the first operational amplifier U1.

[0052] The first operational amplifier U1 grounds its non-inverting input terminal via a fourth resistor R4, ensuring the stability of the first comparator 10. The first operational amplifier U1 transmits its output signal to the first control unit 20 via a second resistor R2, effectively controlling the flow rate signal. Furthermore, the third resistor R3 and the first capacitor C1 form a filtering network that effectively removes noise from the signal, improving the accuracy and response speed of the feedback control system.

[0053] The first voltage stabilizing unit 30 comprises a second operational amplifier U2, the non-inverting input terminal of the second operational amplifier U2 is connected with the output terminal of the first pressure sensor H3, and the output terminal of the second operational amplifier U2 is connected with the inverting input terminal of the second operational amplifier U2; the second operational amplifier U2 serves as a voltage stabilizer, so as to ensure the voltage stability of the output terminal of the first pressure sensor H3. Figure 1 As shown in the figure, the non-inverting input terminal of the second operational amplifier U2 is connected with the VP signal output by the output terminal of the voltage amplifier H3, and the second operational amplifier U2 adjusts its output according to the voltage change of the VP signal, so that the output voltage of its output terminal is equal to the voltage of the VP signal, thereby stabilizing the voltage of the VP signal, effectively reducing the influence of voltage fluctuation on the entire circuit, ensuring more accurate flow measurement and control in the circuit, reducing errors and improving the reliability of circuit feedback control.

[0054] The pressure sensing unit 300 comprises a pressure sensor U8 and a second voltage amplifier H5, the non-inverting output terminal of the pressure sensor U8 is connected with the non-inverting input terminal of the second voltage amplifier H5, the inverting output terminal of the pressure sensor U8 is connected with the inverting input terminal of the second voltage amplifier H5, and the output terminal of the second pressure sensor H5 is connected with the input terminal of the second proportional valve control unit 400; as shown in the figure, the second voltage amplifier H5 can amplify the signal collected by the voltage sensor U8 and compensate for zero drift, realizing accurate, stable and anti-interference flow signal transmission, thereby improving the accuracy of subsequent proportional valve control. Figure 3

[0055] The second proportional valve control unit 400 comprises a second comparison unit 40, a second control unit 50 and a second voltage stabilizing unit 60, the inverting input terminal of the second comparison unit 40 is connected with the output terminal of the second pressure sensor H5, and the non-inverting input terminal of the second comparison unit 40 is connected with the control center; the second control unit 50 comprises a second transistor Q2, a second diode D2 and a second proportional valve H2, the base of the second transistor Q2 is connected with the output terminal of the second comparison unit 40, the emitter of the second transistor Q2 is connected with the negative electrode of the second diode D2, the positive electrode of the second diode D2 is grounded, the positive electrode of the second proportional valve H2 is connected with the negative electrode of the second diode D2, and the negative electrode of the second proportional valve H2 is connected with the positive electrode of the second diode D2; the input terminal of the second voltage stabilizing unit 60 is connected with the control center;

[0056] ​The second comparison unit 40 detects the pressure deviation by comparing the output signal of the pressure sensor H5 with the second electric signal; the second diode D2 in the second control unit 50 prevents reverse connection and prevents the transient current at both ends of the second proportional valve H2 from being too large, thereby protecting the circuit; the second transistor Q2 is a Darlington tube, and the second proportional valve H2 is connected to the output terminal of the second transistor Q2; the second proportional valve H2 requires a high working voltage and current when working, and the Darlington diode can withstand a high voltage and current to drive the proportional valve to work; the second voltage stabilizing unit 60 stably controls the current to avoid control errors caused by current fluctuations, thereby improving the control accuracy and reliability of the entire circuit.

[0057] The second comparison unit 40 includes a third operational amplifier U3, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a second capacitor C2; the output terminal of the second pressure sensor H5 is connected to the inverting input terminal of the third operational amplifier U3 through the fifth resistor R5; the non-inverting input terminal of the third operational amplifier U3 is connected to the control center through the sixth resistor R6; the output terminal of the third operational amplifier U3 is connected to the input terminal of the second control unit 50 through the eighth resistor R8; the non-inverting input terminal of the third operational amplifier U3 is connected to the seventh resistor R7 and one end of the second capacitor C2; the other end of the seventh resistor R7 and the second capacitor C2 is connected to the output terminal of the third operational amplifier U3.

[0058] The third operational amplifier U3 receives the second electric signal from the control center and the actual output signal of the pressure sensor H5 through the fifth resistor R5 and the sixth resistor R6, respectively, thereby detecting the voltage deviation; the combination of the seventh resistor R7 and the second capacitor C2 constitutes a feedback network to form a low-pass filter circuit, which effectively filters out high-frequency noise and improves the stability and anti-interference ability of the signal.

[0059] The second voltage stabilizing unit 60 includes a fourth operational amplifier U4; the non-inverting input terminal of the fourth operational amplifier U4 is connected to the control center; the output terminal of the fourth operational amplifier U4 is connected to the inverting input terminal of the fourth operational amplifier U4.

[0060] The second voltage stabilizing unit 60 realizes stable pressure signal output through the self-stabilizing loop of the fourth operational amplifier U4; the non-inverting input terminal of the fourth operational amplifier U4 is connected to the control center, so that it receives and stabilizes the electric signal from the control center; the output terminal of the fourth operational amplifier U4 is connected to the inverting input terminal, thereby constituting a voltage follower structure that can effectively reduce signal fluctuations and provide low output impedance; the pressure signal remains stable during transmission, avoiding precision loss caused by external interference or signal attenuation; the voltage stabilizing unit provides a reliable signal basis for subsequent pressure control, thereby improving the control accuracy and response consistency of the feedback control system.

[0061] The feedback control system further comprises a gas path, which is a closed pipeline, and the gas path has a gas inlet and an emptying outlet at two ends, and the gas path is sequentially provided with a flow sensing unit 100, a first proportional valve control unit 200, a pressure sensing unit 300, a capillary column and a second proportional valve control unit 400, and the flow sensing unit 100 is arranged at one end close to the gas inlet. Figure 4 As shown in the figure, the flow sensor 100, the pressure sensor 300 and the first proportional valve control unit 200 are all arranged before the capillary column, which is more convenient for controlling the flow and pressure of the liquid inlet end of the capillary column through the emptying outlet, thereby improving the control precision and stability of the feedback and ensuring the separation effect and analysis precision of the capillary column.

[0062] The above is only the preferred embodiment of the present application and is not used to limit the present application, and the present application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

[0063] The above is only the preferred embodiment of the present application and is not used to limit the present application, and the present application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application. The protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A feedback control system, characterized in that: include: a control center, configured to convert a target flow value and a target pressure value in a control instruction into a first electrical signal and a second electrical signal, respectively; A flow control unit, the flow control unit being connected to the control center, the flow control unit comprising a flow sensing unit (100) and a first proportional valve control unit (200), the output end of the flow sensing unit (100) being connected to the input end of the first proportional valve control unit (200), and the first proportional valve control unit (200) being used to determine whether to perform proportional valve adjustment; A pressure control unit is connected to the control center, the pressure control unit comprises a pressure sensing unit (300) and a second proportional valve control unit (400), the output end of the pressure sensing unit (300) is connected to the input end of the second proportional valve control unit (400), and the second proportional valve control unit (400) is used to determine whether to perform proportional valve adjustment.

2. The feedback control system according to claim 1, characterized in that The flow sensing unit (100) includes a flow sensor U7 and a first voltage amplifier H3, wherein the positive phase output terminal of the flow sensor U7 is connected to the positive phase input terminal of the first voltage amplifier H3, the negative phase output terminal of the flow sensor U7 is connected to the negative phase input terminal of the first voltage amplifier H3, and the output terminal of the first voltage amplifier H3 is connected to the input terminal of the first proportional valve control unit (200).

3. The feedback control system according to claim 2, characterized in that The first proportional valve control unit (200) includes a first comparison unit (10), a first control unit (20) and a first voltage stabilization unit (30). The inverting input terminal of the first comparison unit (10) is connected to the output terminal of the first voltage amplifier H3, and the non-inverting input terminal of the first comparison unit (10) is connected to the control center; The first control unit (20) includes a first transistor Q1, a first diode D1, and a first proportional valve H1, wherein the base of the first transistor Q1 is connected to the output end of the first comparison unit (10), the emitter of the first transistor Q1 is connected to the cathode of the first diode D1, the anode of the first diode D1 is grounded, the anode of the first proportional valve H1 is connected to the cathode of the first diode D1, and the cathode of the first proportional valve H1 is connected to the anode of the first diode D1; The input end of the first voltage stabilizing unit (30) is connected to the output end of the first voltage amplifier H3.

4. The feedback control system according to claim 3, characterized in that The first comparison unit (10) includes a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first capacitor C1. The output end of the first voltage amplifier H3 is connected to the inverting input end of the first operational amplifier U1 through the first resistor R1, the non-inverting input end of the first operational amplifier U1 is grounded through the fourth resistor R4, and the output end of the first operational amplifier U1 is connected to the input end of the first control unit (20) through the second resistor R2; An inverting input terminal of the first operational amplifier U1 is connected to one end of the third resistor R3 and the first capacitor C1 , and the other ends of the third resistor R3 and the first capacitor C1 are connected to an output terminal of the first operational amplifier U1 .

5. The feedback control system according to claim 3, characterized in that The first voltage stabilizing unit (30) includes a second operational amplifier U2, The non-inverting input terminal of the second operational amplifier U2 is connected to the output terminal of the first voltage amplifier H3 , and the output terminal of the second operational amplifier U2 is connected to the inverting input terminal of the second operational amplifier U2 .

6. The feedback control system according to claim 1, characterized in that The pressure sensing unit (300) includes a pressure sensor U8 and a second voltage amplifier H5, the positive phase output terminal of the pressure sensor U8 is connected to the positive phase input terminal of the second voltage amplifier H5, the negative phase output terminal of the pressure sensor U8 is connected to the negative phase input terminal of the second voltage amplifier H5, and the output terminal of the second voltage amplifier H5 is connected to the input terminal of the second proportional valve control unit (400).

7. The feedback control system according to claim 6, characterized in that The second proportional valve control unit (400) includes a second comparison unit (40), a second control unit (50) and a second voltage stabilization unit (60). The inverting input terminal of the second comparison unit (40) is connected to the output terminal of the second voltage amplifier H5, and the non-inverting input terminal of the second comparison unit (40) is connected to the control center; The second control unit (50) includes a second transistor Q2, a second diode D2, and a second proportional valve H2, wherein the base of the second transistor Q2 is connected to the output end of the second comparison unit (40), the emitter of the second transistor Q2 is connected to the cathode of the second diode D2, the anode of the second diode D2 is grounded, the anode of the second proportional valve H2 is connected to the cathode of the second diode D2, and the cathode of the second proportional valve H2 is connected to the anode of the second diode D2; An input end of the second voltage stabilizing unit (60) is connected to the control center.

8. The feedback control system according to claim 7, characterized in that The second comparison unit (40) includes a third operational amplifier U3, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a second capacitor C2. The output end of the second voltage amplifier H5 is connected to the inverting input end of the third operational amplifier U3 via the fifth resistor R5, the non-inverting input end of the third operational amplifier U3 is connected to the control center via the sixth resistor R6, and the output end of the third operational amplifier U3 is connected to the input end of the second control unit (50) via the eighth resistor R8; A non-inverting input terminal of the third operational amplifier U3 is connected to one end of the seventh resistor R7 and the second capacitor C2, and the other ends of the seventh resistor R7 and the second capacitor C2 are connected to the output terminal of the third operational amplifier U3.

9. The feedback control system according to claim 7, characterized in that The second voltage stabilizing unit (60) includes a fourth operational amplifier U4, The non-inverting input terminal of the fourth operational amplifier U4 is connected to the control center, and the output terminal of the fourth operational amplifier U4 is connected to the inverting input terminal of the fourth operational amplifier U4.

10. The feedback control system according to claim 1, characterized in that The feedback control system further comprises an air circuit, which is a closed pipeline, with a gas inlet and an exhaust port at both ends of the air circuit respectively. A flow sensor unit (100), a first proportional valve control unit (200), a pressure sensor unit (300), a capillary column and a second proportional valve control unit (400) are sequentially arranged inside the air circuit, and the flow sensor unit (100) is arranged at one end close to the gas inlet.

Images