CN116400750A - Fluid constant pressure control method and fluid constant pressure output system - Google Patents
Fluid constant pressure control method and fluid constant pressure output system Download PDFInfo
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- G05D16/20—Control of fluid pressure characterised by the use of electric means
- G05D16/2006—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means
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Abstract
The invention relates to the technical field of fluid control, in particular to a fluid constant pressure control method and a fluid constant pressure output system. A fluid constant pressure control method comprising: determining a preset output pressure of the air supply unit according to the fluid target output pressure; receiving a signal representative of an actual output pressure of fluid at a fluid outlet of the flow regulator valve; determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure; substituting the fluid pressure output error into a PID feedback regulation system and determining the corrected output pressure of the air supply unit under the condition that the fluid pressure output error is larger than a preset value; until the fluid pressure output error is less than a preset value. The fluid constant pressure control method can control the fluid output pressure of the fluid outlet of the flow regulating valve in real time, can realize constant pressure control capability, and can quickly adapt to the fluid pressure requirements of different processes.
Description
Technical Field
The invention relates to the technical field of fluid control, in particular to a fluid constant pressure control method and a fluid constant pressure output system.
Background
The existing fluid process control solutions in the coating industry mostly control the fluid flow directly by manually adjusting a pressure regulating valve, thereby controlling the fluid pressure. The common solution for controlling constant pressure of glaze or paint is to manually adjust the knob of the pressure regulating valve to make the outlet pressure reach the target value and then keep the opening of the valve unchanged. The fluid process regulating system used in the scheme has the characteristics of simple structure, simple installation and relatively low cost, but because the pressure of the fluid conveyed by the diaphragm pump at the inlet of the fluid control cabinet periodically fluctuates, the opening degree of the pressure regulating valve is kept to be certain and the pressure and the flow of the process fluid cannot be kept stable, so that the pressure and the flow of the process fluid cannot be accurately controlled in real time by using a single manual pressure regulating valve. Moreover, when the target flow or target pressure of the required process fluid changes, the existing scheme needs to manually adjust the pressure regulating valve knob, which is time-consuming and labor-consuming, and cannot meet the automatic spraying requirement of the automatic fluid conversion process. Therefore, there is a need for a more intelligent fluid control system in industries that require precise control of process fluids, and in conditions that require frequent changes in spray fluid processes.
Disclosure of Invention
The object of the present invention includes, for example, providing a fluid constant pressure control method and a fluid constant pressure output system that can make real-time adjustment of the gas input pressure to a flow regulating valve, and thus can make real-time control of the fluid output pressure to a fluid outlet of the flow regulating valve; the anti-interference capacity is provided for pressure fluctuation, and when the fluid output pressure changes, the fluid output pressure can be quickly adjusted to the target fluid output pressure, so that the constant pressure control capacity can be realized, and the fluid pressure requirements of different processes can be quickly met.
Embodiments of the invention may be implemented as follows:
in a first aspect, the present invention provides a fluid constant pressure control method, comprising:
determining a preset output pressure of the air supply unit according to the fluid target output pressure;
receiving a signal representative of an actual output pressure of fluid at a fluid outlet of the flow regulator valve;
determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure;
substituting the fluid pressure output error into the PID feedback regulation system and determining the corrected output pressure of the air supply unit under the condition that the fluid pressure output error is larger than a preset value;
until the fluid pressure output error is less than a preset value.
In an alternative embodiment, before the step of determining the preset output pressure of the air supply unit according to the target output pressure of the fluid, the fluid constant pressure control method further includes:
receiving a signal indicative of an operating output pressure of the air supply unit;
receiving a signal representative of an actual output flow rate of fluid at a fluid outlet of the flow regulating valve;
receiving a signal indicative of an actual output pressure of the fluid;
and determining a first preset rule according to the working output pressure and the actual fluid output flow rate, and determining a second preset rule according to the actual fluid output flow rate and the actual fluid output pressure.
In an alternative embodiment, the step of determining the preset output pressure of the air supply unit from the fluid target output pressure comprises:
substituting the target fluid output pressure into a second preset rule, and determining a preset fluid output flow rate;
substituting the preset output flow rate of the fluid into a first preset rule and determining a preset output pressure.
In an alternative embodiment, before the step of determining the fluid pressure output error according to the fluid actual output pressure and the fluid target output pressure, the fluid constant pressure control method further includes:
collecting a target output pressure of fluid and an actual output pressure of fluid in a plurality of preset sampling periods;
determining a fluid pressure output error between a target fluid output pressure and an actual fluid output pressure in each preset sampling period;
determining three PID parameters according to the target output pressures of the fluids, the actual output pressures of the fluids and the output errors of the pressures of the fluids, and constructing a PID feedback regulation system;
the input of the PID feedback regulating system is fluid pressure output error, the output of the PID feedback regulating system is output pressure regulating value, and the expression is:
wherein n is the sampling frequency, t n For the iteration count of the nth sample, E is the fluid pressure output error, ts is the preset sampling period, and P, I and D are both PID parameters.
In an alternative embodiment, the step of substituting the fluid pressure output error into the PID feedback regulation system and determining the corrected output pressure of the air supply unit in case the fluid pressure output error is greater than a preset value comprises:
substituting the fluid pressure output error into the PID feedback regulation system and obtaining an output pressure regulation value if the fluid pressure output error is larger than a preset value in a preset sampling period;
the corrected output pressure of the air supply unit is determined according to the output pressure adjustment value and the preset output pressure, and the expression is as follows:
P(t n )＝P(t n-1 )+ΔP(t n )。
in a second aspect, the present invention provides a fluid constant pressure output system for performing the above-described fluid constant pressure control method, the fluid constant pressure output system including a gas supply unit, a fluid output unit, a first pressure detection unit, and a main controller;
the air supply unit is communicated with an air inlet pipeline of the flow regulating valve; the fluid supply unit is communicated with a fluid inlet pipeline of the flow regulating valve, and the fluid output unit is communicated with a fluid outlet pipeline of the flow regulating valve; the first pressure detection unit is arranged at the fluid outlet or on a pipeline for communicating the fluid output unit and the fluid outlet;
the main controller is electrically connected with the air supply unit and the first pressure detection unit; the main controller is used for determining the preset output pressure of the air supply unit according to the fluid target output pressure; the main controller is used for receiving signals representing the actual output pressure of the fluid at the fluid outlet of the flow regulating valve; the main controller is used for determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure; the main controller is also used for substituting the fluid pressure output error into the PID feedback regulation system and determining the corrected output pressure of the air supply unit under the condition that the fluid pressure output error is larger than a preset value.
In an alternative embodiment, the fluid constant pressure output system further comprises a PID controller, the PID controller being electrically connected to the main controller;
the PID controller is used for determining three PID parameters according to the target output pressures of the fluids, the actual output pressures of the fluids and the output errors of the pressures of the fluids, and constructing a PID feedback regulating system; the PID controller is also configured to determine a corrected output pressure of the air supply unit based on the fluid pressure output error.
In an alternative embodiment, the fluid constant pressure output system further comprises a proportional regulating valve, wherein the proportional regulating valve is arranged on a pipeline for communicating the air supply unit and the flow regulating valve, and the proportional regulating valve is electrically connected with the main controller.
In an alternative embodiment, the fluid constant pressure output system further comprises a second pressure detection unit;
the second pressure detection unit is arranged at the air outlet of the air supply unit or on a pipeline communicating the air supply unit and the flow regulating valve, and is electrically connected with the main controller.
In an alternative embodiment, the fluid constant pressure output system further comprises a flow detection unit; the flow detection unit is arranged at the fluid outlet of the flow regulating valve and is electrically connected with the main controller.
The beneficial effects of the embodiment of the invention include:
the fluid constant pressure control method comprises the following steps: determining a preset output pressure of the air supply unit according to the fluid target output pressure; receiving a signal representative of an actual output pressure of fluid at a fluid outlet of the flow regulator valve; determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure; substituting the fluid pressure output error into the PID feedback regulation system and determining the corrected output pressure of the air supply unit under the condition that the fluid pressure output error is larger than a preset value; until the fluid pressure output error is less than a preset value.
The fluid constant pressure control method can be used for adjusting the gas input pressure of the flow control valve in real time through error feedback, so that the fluid output pressure of the fluid outlet of the flow control valve can be controlled in real time; the anti-interference capacity is provided for pressure fluctuation, and when the fluid output pressure changes, the fluid output pressure can be quickly adjusted to the target fluid output pressure, so that the constant pressure control capacity can be realized, and the fluid pressure requirements of different processes can be quickly met.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a step diagram of a method for controlling constant pressure of a fluid in an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a constant-pressure fluid output system according to an embodiment of the present invention.
Icon: 100-a fluid constant pressure output system; 110-an air supply unit; 120-a fluid supply unit; 130-a fluid output unit; 140-a first pressure detection unit; 150-proportional control valve.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.
It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.
Referring to fig. 1 and 2, the present embodiment provides a fluid constant pressure control method, which includes:
s1: determining a preset output pressure of the air supply unit 110 according to the fluid target output pressure;
s2: receiving a signal representative of an actual output pressure of fluid at a fluid outlet of the flow regulator valve;
s3: determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure;
s4: substituting the fluid pressure output error into the PID feedback adjustment system and determining a corrected output pressure of the air supply unit 110 in case the fluid pressure output error is greater than a preset value;
s5: until the fluid pressure output error is less than a preset value.
Referring to fig. 1 and 2, the working principle of the fluid constant pressure control method is as follows:
the fluid constant pressure control method can determine the preset output pressure of the air supply unit 110 according to the fluid target output pressure, and can detect the actual output pressure of the fluid at the fluid outlet of the flow control valve when the preset output pressure is used as the output pressure of the air supply unit 110 to control the output pressure of the air supply unit 110 through the PID feedback control system when the fluid pressure output error occurs between the actual output pressure of the fluid and the fluid target output pressure, so that the working state of the flow control valve is adjusted, the fluid pressure output error can be reduced or eliminated, and the control accuracy of the fluid output pressure can be improved;
in summary, the fluid constant pressure control method can be used for adjusting the gas input pressure of the flow control valve in real time through error feedback, so that the fluid output pressure of the fluid outlet of the flow control valve can be controlled in real time; the anti-interference capability is provided for pressure fluctuation, and when the fluid output pressure changes, the fluid output pressure can be quickly regulated to the target fluid output pressure, so that the constant pressure control capability can be realized;
in addition, when the fluid constant pressure control method is operated, each time the target output pressure of the fluid changes, the fluid constant pressure control method firstly determines the preset output pressure of the air supply unit 110 and uses the preset output pressure as the target gas pressure value for controlling the flow regulating valve, and then starts the PID feedback regulating system to carry out subsequent regulation, so that the fluid constant pressure control method can quickly adapt to the fluid pressure requirements of different processes.
It should be noted that, first, in the present embodiment, the fluid constant pressure control method is used to solve the problem that the real-time accurate adjustment of the fluid delivered by the paint supply system cannot be performed in the traditional coating fluid process field, and in other embodiments of the present invention, the present invention can also be applied to the fluid output pressure control in other fields.
Next, in the present embodiment, in the process of adjusting the actual output pressure of the fluid at the fluid outlet of the flow rate adjusting valve, a manner of controlling the pressure of the gas introduced into the flow rate adjusting valve by the gas supply unit 110 is adopted, so that the flow rate adjusting valve is a pneumatic element having a cone structure therein capable of controlling the size of the flow passage opening, and the axial height of the cone and thus the size of the flow passage opening can be controlled by controlling the pressure of the gas introduced into the upper portion of the flow rate adjusting valve.
In addition, the PID feedback regulation system is a closed loop feedback regulation system formed by a PID controller, and can regulate the magnitude of control quantity output according to errors generated by the actual value and the target value of the target object; in general, the control object and the target object are not the same object, in the invention, the control object is the gas pressure which is introduced into the flow regulating valve, and the target object is the fluid pressure output error; the essence of the PID algorithm is to put the PID controller into the proportion, differentiation and integration to calculate according to the error between the actual value and the target value of the target object, and output the change amount of the control object to achieve the effect of reducing or even eliminating the error.
When the preset value is set, the preset value can be the absolute value of the difference value between the actual output pressure of the fluid and the target output pressure of the fluid, and the aim is to perform the closed-loop feedback adjustment under the condition that the actual output pressure of the fluid is larger or smaller than the target output pressure of the fluid, so that the effect of reducing or even eliminating errors is achieved; and when the preset value is set, it may be adjusted according to the actual situation, and in this embodiment, the preset value may be set to 5% of the target output pressure of the fluid.
Further, in the present embodiment, before the step of determining the preset output pressure of the air supply unit 110 according to the fluid target output pressure, the fluid constant pressure control method further includes:
receiving a signal indicative of an operating output pressure of the air supply unit 110;
receiving a signal representative of an actual output flow rate of fluid at a fluid outlet of the flow regulating valve;
receiving a signal indicative of an actual output pressure of the fluid;
and determining a first preset rule according to the working output pressure and the actual fluid output flow rate, and determining a second preset rule according to the actual fluid output flow rate and the actual fluid output pressure.
Thus, the step of determining the preset output pressure of the air supply unit 110 according to the fluid target output pressure includes:
substituting the target fluid output pressure into a second preset rule, and determining a preset fluid output flow rate;
substituting the preset output flow rate of the fluid into a first preset rule and determining a preset output pressure.
As can be seen from the foregoing, the present embodiment adopts the method for real-time adjustment of the gas input pressure of the flow control valve through error feedback, so that the fluid output pressure of the fluid outlet of the flow control valve can be controlled in real time, so that before the step of determining the fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure, the fluid constant pressure control method further includes:
collecting a target output pressure of fluid and an actual output pressure of fluid in a plurality of preset sampling periods;
determining a fluid pressure output error between a target fluid output pressure and an actual fluid output pressure in each preset sampling period;
determining three PID parameters according to the target output pressures of the fluids, the actual output pressures of the fluids and the output errors of the pressures of the fluids, and constructing a PID feedback regulation system;
the input of the PID feedback regulating system is fluid pressure output error, the output of the PID feedback regulating system is output pressure regulating value, and the expression is:
wherein n is the sampling frequency, t n For the iteration count of the nth sample, E is the fluid pressure output error, ts is the preset sampling period, and P, I and D are both PID parameters.
On the basis of the constructed PID feedback regulation system, in the case that the fluid pressure output error is greater than the preset value, the step of substituting the fluid pressure output error into the PID feedback regulation system and determining the corrected output pressure of the air supply unit 110 includes:
substituting the fluid pressure output error into the PID feedback regulation system and obtaining an output pressure regulation value if the fluid pressure output error is larger than a preset value in a preset sampling period;
the corrected output pressure of the air supply unit 110 is determined according to the output pressure adjustment value and the preset output pressure, and the expression is:
P(t n )＝P(t n-1 )+ΔP(t n )。
based on the above, please refer to fig. 1 and 2, the present invention further provides a fluid constant pressure output system 100 for executing the above-mentioned fluid constant pressure control method, wherein the fluid constant pressure output system 100 includes a gas supply unit 110, a fluid supply unit 120, a fluid output unit 130, a first pressure detection unit 140, and a main controller;
the air supply unit 110 is communicated with an air inlet pipeline of the flow regulating valve; the fluid supply unit 120 is communicated with a fluid inlet pipeline of the flow regulating valve, and the fluid output unit 130 is communicated with a fluid outlet pipeline of the flow regulating valve; the first pressure detecting unit 140 is disposed at the fluid outlet, or disposed on a pipeline connecting the fluid output unit 130 and the fluid outlet;
the main controller is electrically connected with the air supply unit 110 and the first pressure detection unit 140; the main controller is used for determining the preset output pressure of the air supply unit 110 according to the fluid target output pressure; the main controller is used for receiving signals representing the actual output pressure of the fluid at the fluid outlet of the flow regulating valve; the main controller is used for determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure; the main controller is further configured to, in the event that the fluid pressure output error is greater than a preset value, substitute the fluid pressure output error into the PID feedback regulation system and determine a corrected output pressure of the air supply unit 110.
Referring to fig. 1 and 2, the fluid constant pressure output system 100 operates as follows:
the fluid constant pressure output system 100 can detect the actual output pressure of the fluid through the first pressure detection unit 140, and further can determine the fluid pressure output error according to the actual output pressure of the fluid and the target output pressure of the fluid, so that the fluid pressure output error can be substituted into the PID feedback adjustment system, and the corrected output pressure of the air supply unit 110 can be determined;
thus, the fluid constant pressure output system 100 can adjust the gas input pressure of the gas supply unit 110 introduced into the flow regulating valve in real time through the error feedback of the fluid pressure output error, and further can control the fluid output pressure of the fluid outlet of the flow regulating valve in real time; the anti-interference capacity is provided for pressure fluctuation, and when the fluid output pressure changes, the fluid output pressure can be quickly adjusted to the target fluid output pressure, so that the constant pressure control capacity can be realized, and the fluid pressure requirements of different processes can be quickly met.
In addition, in order to adjust the gas input pressure of the flow regulating valve introduced into the gas supply unit 110 in real time based on the error feedback, a PID feedback regulating system needs to be formed, so the fluid constant pressure output system 100 further includes a PID controller, and the PID controller is electrically connected with the main controller;
the PID controller is used for determining three PID parameters according to the target output pressures of the fluids, the actual output pressures of the fluids and the output errors of the pressures of the fluids, and constructing a PID feedback regulating system; the PID controller is also used to determine a corrected output pressure of the air supply unit 110 based on the fluid pressure output error.
In addition, in the process of adjusting the gas input pressure of the gas supply unit 110 for introducing the flow rate adjusting valve, the mode of adjusting the working state of the gas supply unit 110 may be adopted, or the mode of adjusting the proportional adjusting valve 150 may be adopted, the gas input pressure of the gas supply unit 110 for introducing the flow rate adjusting valve is adjusted through the proportional adjusting valve 150, specifically, the fluid constant pressure output system 100 further comprises the proportional adjusting valve 150, the proportional adjusting valve 150 is arranged on a pipeline for communicating the gas supply unit 110 and the flow rate adjusting valve, and the proportional adjusting valve 150 is electrically connected with the main controller.
Further, when the gas supply unit 110 is provided, as is known from the above, when the gas input pressure of the flow rate adjustment valve introduced into the gas supply unit 110 is adjusted, the operation state of the gas supply unit 110 may be adjusted, or the operation state of the proportional adjustment valve 150 may be adjusted, so that the fluid constant pressure output system 100 further includes a second pressure detection unit for detecting the gas input pressure of the flow rate adjustment valve introduced into the gas supply unit 110; the second pressure detecting unit is disposed at the air outlet of the air supply unit 110, or disposed on a pipeline communicating the air supply unit 110 and the flow regulating valve, and is electrically connected with the main controller.
To detect the fluid flow rate at the fluid outlet of the flow regulating valve, the fluid constant pressure output system 100 further includes a flow detecting unit; the flow detection unit is arranged at the fluid outlet of the flow regulating valve and is electrically connected with the main controller.
Referring to fig. 1 and 2, based on the above-mentioned fluid constant pressure control method, the working process of the fluid constant pressure output system 100 is as follows:
firstly, calibrating fluid, and finding out the relation between the gas pressure and the fluid flow of the proportional regulating valve 150 which are introduced into the flow regulating valve and the relation between the fluid flow and the fluid pressure, wherein the relation is a primary function; that is, the working output pressure of the air supply unit 110, the fluid actual output flow rate of the fluid outlet of the flow rate regulating valve, and the fluid actual output pressure are determined, and a first preset rule is determined according to the working output pressure and the fluid actual output flow rate, and a second preset rule is determined according to the fluid actual output flow rate and the fluid actual output pressure; then substituting the fluid target output pressure into a second preset rule, determining the fluid preset output flow rate, substituting the fluid preset output flow rate into the first preset rule, and determining the preset output pressure, thereby determining the calibrated fluid target output pressure;
after the target output pressure of the fluid is determined, controlling the gas pressure introduced into the flow regulating valve by the proportional regulating valve 150 so that the gas pressure introduced into the flow regulating valve is the target output pressure;
it should be noted that, in the subsequent working process of the constant-pressure fluid output system 100, each time the target fluid output pressure changes, the above steps are required to determine the target fluid output pressure, and the control is performed on the control valve 150, so that the gas pressure introduced into the flow control valve is the adjusted target output pressure;
after the above adjustment is completed, the PID feedback adjustment is started and continuously operated until the target fluid output pressure is changed or the operation of the fluid constant pressure output system 100 is stopped; specifically, the actual output pressure of fluid is collected once every sampling period Ts and is recorded as P r (t n ) Reading the fluid target output pressure set by the user as P t (t n ) At this time, the fluid pressure output error of the fluid target output pressure and the fluid actual output pressure is:
E(t n )＝P r (t n )-P t (t n )
the error integral is the error integral calculated at the previous time plus the error at this time:
E sum (t n )＝E sum (t n-1 )+E(t n )
will E sum (t n ) And E (t) n ) Substituting into PID feedback regulation system:
the input of the PID feedback regulation system is fluid pressure output error; the output of the PID feedback regulation system is an output pressure regulation value; n is the sampling times; t is t n Counting iterations for the nth sample; e is the fluid pressure output error; ts is a preset sampling period, which is a known constant; p, I and D are PID parameters, are obtained by data simulation and parameter adjustment in advance, and are known constants; e (t) n-1 ) The fluid pressure output error at the previous moment is a known constant; so far, the right and left variable values of the equation are already obtained, and the output pressure adjustment value of the flow regulating valve at the left side of the equation can be obtained;
thus, the corrected output pressure is assigned as the sum of the gas pressure flowing into the flow rate regulating valve at the previous moment and the output pressure regulating value, as follows:
P(t n )＝P(t n-1 )+ΔP(t n )
it should be noted that, the gas pressure introduced into the flow rate regulating valve at the previous moment may be the corrected output pressure at the previous moment or the preset output pressure at the previous moment, where the corrected output pressure at the previous moment refers to the pressure of the gas introduced into the flow rate regulating valve at the previous moment after feedback regulation, and the preset output pressure at the previous moment refers to the pressure of the gas introduced into the flow rate regulating valve at the previous moment after no feedback regulation;
taking the determined corrected output pressure as the gas pressure entering the flow regulating valve;
after the preset sampling period is completed, the above steps are repeated until the fluid target output pressure is changed or the operation of the fluid constant pressure output system 100 is stopped after the next preset sampling period Ts is entered.
The present invention is not limited to the above embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. A fluid constant pressure control method, comprising:
determining a preset output pressure of the air supply unit according to the fluid target output pressure;
receiving a signal representative of an actual output pressure of fluid at a fluid outlet of the flow regulator valve;
determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure;
substituting the fluid pressure output error into a PID feedback regulation system and determining the corrected output pressure of the air supply unit under the condition that the fluid pressure output error is larger than a preset value;
until the fluid pressure output error is less than the preset value.
2. The fluid constant pressure control method according to claim 1, characterized in that:
before the step of determining the preset output pressure of the air supply unit according to the target output pressure of the fluid, the fluid constant pressure control method further includes:
receiving a signal representative of an operating output pressure of the air supply unit;
receiving a signal representative of an actual output flow rate of fluid at a fluid outlet of the flow regulating valve;
receiving a signal indicative of an actual output pressure of the fluid;
and determining a first preset rule according to the working output pressure and the fluid actual output flow rate, and determining a second preset rule according to the fluid actual output flow rate and the fluid actual output pressure.
3. The fluid constant pressure control method according to claim 2, characterized in that:
the step of determining a preset output pressure of the air supply unit according to the fluid target output pressure includes:
substituting the fluid target output pressure into the second preset rule, and determining a fluid preset output flow rate;
substituting the preset output flow rate of the fluid into the first preset rule and determining the preset output pressure.
4. The fluid constant pressure control method according to claim 1, characterized in that:
before the step of determining a fluid pressure output error according to the fluid actual output pressure and the fluid target output pressure, the fluid constant pressure control method further includes:
collecting the target fluid output pressure and the actual fluid output pressure in a plurality of preset sampling periods;
determining the fluid pressure output error between the fluid target output pressure and the fluid actual output pressure in each preset sampling period;
determining three PID parameters according to the target fluid output pressures, the actual fluid output pressures and the fluid pressure output errors, and constructing the PID feedback regulation system;
the input of the PID feedback regulating system is the fluid pressure output error, the output of the PID feedback regulating system is an output pressure regulating value, and the expression is as follows:
wherein n is the sampling frequency, t n For the iteration count of the nth sample, E is the fluid pressure output error, ts is the preset sampling period, and P, I and D are PID parameters.
5. The fluid constant pressure control method according to claim 4, wherein:
the step of substituting the fluid pressure output error into a PID feedback regulation system and determining a corrected output pressure of the air supply unit in case the fluid pressure output error is greater than a preset value comprises:
substituting the fluid pressure output error into the PID feedback regulation system and obtaining the output pressure regulation value if the fluid pressure output error is larger than a preset value in the preset sampling period;
determining the corrected output pressure of the air supply unit according to the output pressure adjustment value and the preset output pressure, wherein the expression is as follows:
P(t n )＝P(t n-1 )+ΔP(t n )。
6. a fluid constant pressure output system for performing the fluid constant pressure control method according to any one of claims 1 to 5, characterized in that:
the fluid constant pressure output system comprises a gas supply unit, a fluid output unit, a first pressure detection unit and a main controller;
the air supply unit is communicated with an air inlet pipeline of the flow regulating valve; the fluid supply unit is communicated with a fluid inlet pipeline of the flow regulating valve, and the fluid output unit is communicated with a fluid outlet pipeline of the flow regulating valve; the first pressure detection unit is arranged at the fluid outlet or on a pipeline which is communicated with the fluid output unit and the fluid outlet;
the main controller is electrically connected with the air supply unit and the first pressure detection unit; the main controller is used for determining preset output pressure of the air supply unit according to the fluid target output pressure; the main controller is used for receiving a signal representing the actual output pressure of the fluid at the fluid outlet of the flow regulating valve; the main controller is used for determining a fluid pressure output error according to the actual fluid output pressure and the target fluid output pressure; the main controller is also used for substituting the fluid pressure output error into a PID feedback regulation system and determining the corrected output pressure of the air supply unit under the condition that the fluid pressure output error is larger than a preset value.
7. The fluid constant pressure output system according to claim 6, wherein:
the fluid constant pressure output system further comprises a PID controller, and the PID controller is electrically connected with the main controller;
the PID controller is used for determining three PID parameters according to the fluid target output pressures, the fluid actual output pressures and the fluid pressure output errors, and constructing the PID feedback regulation system; the PID controller is also configured to determine a corrected output pressure of the air supply unit based on the fluid pressure output error.
8. The fluid constant pressure output system according to claim 6, wherein:
the fluid constant pressure output system further comprises a proportional regulating valve, wherein the proportional regulating valve is arranged on a pipeline which is communicated with the air supply unit and the flow regulating valve, and the proportional regulating valve is electrically connected with the main controller.
9. The fluid constant pressure output system according to claim 8, wherein:
the fluid constant pressure output system also comprises a second pressure detection unit;
the second pressure detection unit is arranged at the air outlet of the air supply unit or on a pipeline which is communicated with the air supply unit and the flow regulating valve, and the second pressure detection unit is electrically connected with the main controller.
10. The fluid constant pressure output system according to claim 6, wherein:
the fluid constant pressure output system further comprises a flow detection unit; the flow detection unit is arranged at the fluid outlet of the flow regulating valve and is electrically connected with the main controller.
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