CN116044841A - Pressure flow high-precision control method based on electromagnetic switch valve - Google Patents
Pressure flow high-precision control method based on electromagnetic switch valve Download PDFInfo
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- CN116044841A CN116044841A CN202211720825.1A CN202211720825A CN116044841A CN 116044841 A CN116044841 A CN 116044841A CN 202211720825 A CN202211720825 A CN 202211720825A CN 116044841 A CN116044841 A CN 116044841A
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- switch valve
- electromagnetic switch
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
- G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P.I., P.I.D.
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K31/00—Actuating devices; Operating means; Releasing devices
- F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
- F16K31/06—Actuating devices; Operating means; Releasing devices electric; magnetic using a magnet, e.g. diaphragm valves, cutting off by means of a liquid
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
Abstract
The invention discloses a high-precision control method for pressure flow based on an electromagnetic switch valve, and belongs to the field of electromagnetic switch valve control. The invention combines the advantages of two control strategies of high frequency and low frequency, when the difference between the measured value and the target value of the system is larger than delta, the PID controller controls the electromagnetic switch valve to work in a lower frequency range, and PID closed-loop control is carried out on the electromagnetic switch valve, so that the actual flow or pressure of the valve path can quickly approach the target value; when the difference between the measured value and the target value is smaller than delta for the first time, the working frequency of the electromagnetic switch valve is increased, PID closed-loop control is carried out on the electromagnetic switch valve, and finally high-precision control of pressure flow is realized. Under the method of the invention, the response time for the actual flow value to reach the target flow value is shorter, and the control precision is higher after the system is stable.
Description
Technical Field
The invention belongs to the field of high-precision control of electromagnetic switch valves, and particularly relates to a high-precision control method of pressure flow based on an electromagnetic switch valve.
Background
The rapid development of electronic technology and computer technology brings deep influence to hydraulic control technology, and electromechanical liquid integration is a necessary trend of the development of the mechanical hydraulic field in the future. Electro-hydraulic control valves and their digital control techniques are becoming increasingly popular. The electrohydraulic control valve can be divided into three types of servo valve, proportional valve and high-speed electromagnetic switch valve, wherein the high-speed electromagnetic switch valve is researched and paid attention to by virtue of low price, strong pollution resistance, simple structure, reliable operation, convenience for interfacing with a computer and the like. The combination of a high-speed electromagnetic switch valve electrohydraulic control system and computer digital control is a hot topic of the development of the current hydraulic control system.
In many schemes of utilizing high-speed electromagnetic switch valve to control pressure flow of oil system at present, the frequency of adopting PID controller to carry out closed-loop control is higher. The execution flow of the PID controller is very simple, i.e. the deviation signal is detected by means of feedback and the controlled variable is controlled by means of the deviation signal. The controller is the summation of three links of proportion, integral and differential. However, in the control of the oil system, besides the core PID controller, the design of the controllers for processing the input and output signals is particularly critical, and only the controllers of the two parts are designed at the same time, the accurate control of the oil can be realized.
In order to improve the control performance of the system, the existing electromagnetic switch valve control flow pressure model is innovated in a control structure or a control principle to achieve a better control effect. In addition, in the current example of controlling the pressure flow of the oil pressure system by using the control method designed by taking the PID controller as a core, the control result is difficult to ensure that two points of high response speed and high control precision are simultaneously met, and most of the control methods are that the response speed is higher under the control of a low-frequency strategy but the control precision is lower or the control precision is higher under the control of a high-frequency strategy but the response speed is lower.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a high-precision control method for pressure flow based on an electromagnetic switch valve.
The technical scheme of the invention is as follows:
the invention provides a pressure flow high-precision control method based on an electromagnetic switch valve, which is used for acquiring pressure or flow signals on a valve path of the electromagnetic switch valve in real time as measured values, comparing the measured values with preset pressure or flow target values, and performing closed-loop control on the pressure or flow of the electromagnetic switch valve by adopting a PID controller, wherein the pressure flow high-precision control method comprises the following steps:
s1, setting a target value T of pressure or flow control in a PID controller, and setting a pressure or flow difference delta; acquiring pressure or flow signals on a valve path of the electromagnetic switch valve in real time through a sensor to serve as measured values;
s2, when the difference value between the measured value and the target value T is larger than delta, the PID controller controls the electromagnetic switch valve to work in a first frequency range, and PID closed-loop control is carried out on the pressure or flow of the electromagnetic switch valve; under the first frequency range, the actual flow or pressure of the valve path can quickly approach the target value;
when the difference value between the measured value and the target value T is smaller than delta for the first time, the working frequency of the electromagnetic switch valve is increased to a second frequency range, PID closed-loop control is carried out on the pressure or flow of the electromagnetic switch valve, and the electromagnetic switch valve under the working of the second frequency range is used for finally realizing high-precision control of the pressure flow; the second frequency range has a frequency that is higher than the first frequency range.
According to a preferred embodiment of the invention, said difference Δ is 5% -10% of the target value.
According to a preferred embodiment of the present invention, the first frequency range is a frequency operating range of a normal design of the electromagnetic switch valve, which is smaller than a critical frequency of the electromagnetic switch valve.
According to a preferred embodiment of the invention, the second frequency range is larger than the critical frequency of the electromagnetic switch valve, but smaller than the limit frequency of the electromagnetic switch valve.
According to a preferred embodiment of the present invention, the electromagnetic switch valve is a two-position three-way electromagnetic switch valve.
According to a preferred embodiment of the present invention, the working medium on the valve path of the electromagnetic switch valve is hydraulic oil.
Compared with the prior art, the invention combines the advantages of the two control strategies of high frequency and low frequency, so that the electromagnetic high-speed switch valve works with the low frequency control strategy first, and the actual flow reaches the vicinity of the preset flow. When the difference between the actual flow and the target flow is smaller than delta for the first time, the working frequency of the electromagnetic switch valve is changed to be high frequency immediately, and the high-speed switch valve working at the high frequency is used for completing the accurate control of the flow. The invention gives consideration to the response speed of the switch valve and the accuracy of flow control, combines the control methods on the premise of not changing the basic control principle of each switch valve, and uses the control strategies with different control advantages in different control stages. Compared with the principle innovation, under the condition of reaching the ideal control requirement, the operability of the experiment is greatly improved, and the research cost is greatly saved.
Drawings
FIG. 1 is a schematic diagram of an exemplary oil system.
FIG. 2 is a schematic diagram of the actual response of the valve element due to mechanical viscous damping and other factors lagging behind the PWM control signal.
Fig. 3 is a schematic diagram of control accuracy at a fixed low frequency.
Fig. 4 is a schematic diagram of control accuracy at a fixed high frequency.
FIG. 5 is a graph showing the relationship between the displacement curve of the valve core and the PWM control signal at a fixed high frequency.
Fig. 6 is a schematic diagram of a control principle under the control method of the present invention.
FIG. 7 is a schematic diagram of control accuracy of the control method of the present invention.
Detailed Description
The invention is further illustrated and described below in connection with specific embodiments. The described embodiments are merely exemplary of the present disclosure and do not limit the scope. The technical features of the embodiments of the invention can be combined correspondingly on the premise of no mutual conflict.
Taking a typical oil system model as shown in fig. 1 as an example to illustrate the control strategy of the prior art and the invention, reference numerals 1 and 2 in fig. 1 are two identical two-position three-way type high-speed electromagnetic switch valves respectively; the input signal of the controller is a real-time data signal and a target value signal which are measured by a sensor, the output signal is a corresponding duty ratio signal which is processed by a PWM (pulse width modulation) part and is respectively transmitted to the high-speed electromagnetic switch valve 1 and the high-speed electromagnetic switch valve 2;4 is a sensor, such as a flow sensor or a pressure sensor, and has the functions of measuring the flow or the pressure of the oil inlet channel in real time and inputting a real-time signal into the main controller 3; and 5 is a hydraulic cylinder and is an actuating mechanism.
The implementation method for controlling the flow of the oil inlet of the high-speed electromagnetic switch valve in a closed loop manner of the oil system comprises the following steps: firstly, a target flow value is preset, and when the switch valve works, the pressure/flow sensor detects real-time data and inputs the real-time data to the master controller. The master controller compares the target value with the measured value, carries out PID negative feedback adjustment on the difference value between the target value and the measured value, then carries out PWM pulse width modulation part processing, and outputs a duty ratio signal for controlling the electromagnetic switch valve, thereby realizing the flow real-time control of the hydraulic cylinder.
For various control systems similar to the two-position three-way valve oil flow control model, ideally, the displacement response waveform of the valve core should be consistent with the waveform of the input PWM signal in one PWM pulse width modulation period, namely, the valve core should be kept in an open state in a high level stage of the PWM signal, and the valve core should be kept in a closed state in a low level stage. However, due to physical response characteristics of the oil, hysteresis of electromagnetic response, mechanical viscous damping among control system hardware and other realistic influence factors, the actual response situation of the valve core always lags behind the PWM control signal, as shown in FIG. 2.
Therefore, the invention carries out a series of researches on the motion relation between the PWM control signal and the valve core displacement. The invention finds that the experimental results obtained when the high-speed electromagnetic switch valve carries out the pressure/flow of the hydraulic cylinder at different frequencies are different.
When the pressure/flow of the oil system is controlled at a low frequency (e.g., 50 Hz) fixed by the switching valve, the control results shown in fig. 3 may occur: because the PWM signal control frequency is low, the valve core of the high-speed electromagnetic switch valve is necessarily completely opened and closed. The on-off valve oil output flow in a single control cycle will be relatively large. Although the system response time is fast, after the system is stable, the difference between the actual flow rate and the target flow rate does not meet the expected requirement due to poor control accuracy, as shown in fig. 3.
When the pressure/flow of the oil system is controlled at a high frequency (e.g., 130 Hz) fixed by the switching valve, the control results shown in fig. 4 may occur: although the actual flow rate will reach a range close to the target flow rate with a slower response speed, after the system is stabilized, the steady-state error between the actual flow rate and the target flow rate in the high frequency control strategy will be smaller than in the low frequency control strategy.
This is because the control frequency of the PWM control strategy is too high, the opening and closing movement of the switching valve in one movement period is not completed after the opening signal is received, and the valve port cannot be completely opened and closed, as shown in fig. 5. Therefore, the oil flow in a single period is smaller, and the control is more accurate. However, due to the failure to fully open and close, the oil volume output by the high-frequency control strategy in unit time is smaller than that output by the low-frequency control strategy under the same duty ratio, which is why the response speed of the high-frequency control strategy is slower.
Based on the respective control advantages of the two control strategies, the invention provides a high-precision control method for the pressure flow of the high-speed electromagnetic switch valve. The invention acquires the pressure or flow signal on the valve path of the electromagnetic switch valve in real time as a measured value, compares the measured value with a preset pressure or flow target value, adopts a PID controller to carry out closed-loop control on the pressure or flow of the electromagnetic switch valve, and the pressure and flow high-precision control method comprises the following steps:
s1, firstly, the critical frequency and the limiting frequency of the two-position three-way type high-speed electromagnetic switch valve are measured through a traditional experimental method, and the normal working frequency of the valve is generally determined to be slightly smaller than the critical frequency; the critical frequency of the two-position three-way type high-speed electromagnetic switch valve selected in the embodiment is 125Hz, the limiting frequency is 200Hz, and the normal working frequency is 50Hz. Setting a target value T of pressure or flow control in a PID controller, and setting a difference delta of the pressure or the flow, wherein the delta is 5-10% of the target flow; acquiring pressure or flow signals on a valve path of the electromagnetic switch valve in real time through a sensor to serve as measured values;
s2, when the difference value between the measured value and the target value T is larger than delta, the PID controller controls the electromagnetic switch valve to work in a first frequency range (the first frequency range is 50-70Hz and is called a low frequency state), and PID closed-loop control is carried out on the pressure or flow of the electromagnetic switch valve; under the first frequency range, the actual flow or pressure of the valve path can quickly approach the target value;
when the difference between the measured value and the target value T is smaller than delta for the first time, the working frequency of the electromagnetic switch valve is increased to a second frequency range (130-150 Hz in the second frequency range is called a high-frequency state), PID closed-loop control is carried out on the pressure or flow of the electromagnetic switch valve, and the electromagnetic switch valve under the working condition of the second frequency range is used for finally realizing high-precision control on the pressure flow, and the result is shown in figure 6; the second frequency range has a frequency that is higher than the first frequency range.
The actual control effect of the control method is as follows: the response time for the actual flow value to reach the target flow value is shorter, and the control accuracy is also high after the system is stabilized, as shown in fig. 7.
The invention combines the advantages of the high-frequency control strategy and the low-frequency control strategy, thereby the electromagnetic high-speed switch valve works with the low-frequency control strategy first and the actual flow reaches the vicinity of the preset flow. When the difference between the actual flow and the target flow is smaller than delta for the first time, the working frequency of the electromagnetic switch valve is changed to be high frequency immediately, and the high-speed switch valve working at the high frequency is used for completing the accurate control of the flow. The response speed of the switch valve and the accuracy of flow control are both considered. The invention realizes the high-speed response and accurate control of the flow of the hydraulic cylinder by controlling the frequency switching strategy in the field of the high-speed switching valve control hydraulic cylinder, and has innovation. The invention finds the respective defects and advantages of the two control strategies in principle, performs the combined use of the control methods on the premise of not changing the respective basic control principles, and uses the control strategies with different control advantages in different control stages. Compared with the principle innovation, under the condition of reaching the ideal control requirement, the operability of the experiment is greatly improved, and the research cost is greatly saved.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit of the invention.
Claims (6)
1. The pressure flow high-precision control method based on the electromagnetic switch valve is characterized by comprising the following steps of obtaining a pressure or flow signal on a valve path of the electromagnetic switch valve in real time as a measured value, comparing the measured value with a preset pressure or flow target value, and performing closed-loop control on the pressure or flow of the electromagnetic switch valve by adopting a PID controller, wherein the pressure flow high-precision control method comprises the following steps:
s1, setting a target value T of pressure or flow control in a PID controller, and setting a pressure or flow difference delta; acquiring pressure or flow signals on a valve path of the electromagnetic switch valve in real time through a sensor to serve as measured values;
s2, when the difference value between the measured value and the target value T is larger than delta, the PID controller controls the electromagnetic switch valve to work in a first frequency range, and PID closed-loop control is carried out on the pressure or flow of the electromagnetic switch valve; under the first frequency range, the actual flow or pressure of the valve path can quickly approach the target value;
when the difference value between the measured value and the target value T is smaller than delta for the first time, the working frequency of the electromagnetic switch valve is increased to a second frequency range, PID closed-loop control is carried out on the pressure or flow of the electromagnetic switch valve, and the electromagnetic switch valve under the working of the second frequency range is used for finally realizing high-precision control of the pressure flow; the second frequency range has a frequency that is higher than the first frequency range.
2. The electromagnetic valve-based high-precision control method of pressure flow according to claim 1, wherein the difference Δ is 5% -10% of a target value.
3. The method for controlling the pressure flow rate with high precision based on the electromagnetic switch valve according to claim 1, wherein the first frequency range is a frequency operating range of normal design of the electromagnetic switch valve, and the frequency operating range is smaller than a critical frequency of the electromagnetic switch valve.
4. The method for high-precision control of pressure flow based on an electromagnetic switch valve according to claim 1, wherein the second frequency range is greater than a critical frequency of the electromagnetic switch valve but less than a limiting frequency of the electromagnetic switch valve.
5. The high-precision control method of pressure flow based on an electromagnetic switch valve according to claim 1, wherein the electromagnetic switch valve is a two-position three-way electromagnetic switch valve.
6. The high-precision control method of pressure flow based on an electromagnetic switch valve according to claim 1, wherein the working medium on the valve path of the electromagnetic switch valve is hydraulic oil.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211720825.1A CN116044841A (en) | 2022-12-30 | 2022-12-30 | Pressure flow high-precision control method based on electromagnetic switch valve |
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| CN202211720825.1A CN116044841A (en) | 2022-12-30 | 2022-12-30 | Pressure flow high-precision control method based on electromagnetic switch valve |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117006310A (en) * | 2023-10-07 | 2023-11-07 | 深圳市恒永达科技股份有限公司 | Switching valve switching compensation method and device for analysis equipment and analysis equipment |
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2022
- 2022-12-30 CN CN202211720825.1A patent/CN116044841A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117006310A (en) * | 2023-10-07 | 2023-11-07 | 深圳市恒永达科技股份有限公司 | Switching valve switching compensation method and device for analysis equipment and analysis equipment |
| CN117006310B (en) * | 2023-10-07 | 2024-01-19 | 深圳市恒永达科技股份有限公司 | Switching valve switching compensation method and device for analysis equipment and analysis equipment |
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