Ozone concentration adjustment control system and method

Abstract

The present application belongs to the field of control technology, and relates to an ozone concentration adjusting control system and method. An ozone concentration adjusting control method comprises the following steps: measuring the actual ozone concentration, calculating the error value and error change rate of the target ozone concentration and the actual ozone concentration; dynamically adjusting the dead zone threshold; predicting the error at the next moment; substituting the predicted error into a control algorithm to calculate the control output; outputting the control signal to the ozone generator to generate ozone with a corresponding flow rate. The present application dynamically adjusts the size of the dead zone by using the error change rate to suppress the adjustment jitter; combines the concentration prediction error to correct the control output in advance, thereby reducing the response lag; can significantly improve the concentration stability, rapid response and anti-interference ability of the ozone backwash system, thereby improving the organic matter removal efficiency in the pipeline, reducing the energy consumption, and improving the system stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of control, and relates to an ozone concentration adjusting control system and method. BACKGROUND

[0002] Organic matter residues are an important source of errors and deviations in chemical analysis, and interference signals and false peaks are easily generated in the experimental process, which seriously affects the reliability, sensitivity and accuracy of analysis results. Especially in trace analysis and complex matrix analysis, organic matter residues must be strictly controlled.

[0003] Ozone (O3) has strong oxidizing ability and is widely used for organic matter oxidation, disinfection and sterilization. It is widely used in microfluid channel cleaning, medical instrument disinfection, high-precision experimental instrument cleaning and other scenes. By injecting ozone gas into the inside of the pipeline or container in reverse, the oxidation characteristics can be used to effectively remove the attached organic matter residues.

[0004] Dielectric barrier discharge method is a commonly used ozone generation technology, which uses dielectric to control discharge, generates high-energy electrons to crack oxygen molecules, and synthesizes ozone through collision. However, there are problems such as unstable concentration, sensor response lag, lack of real-time feedback and closed-loop control in the preparation and cleaning of chemical reaction pipelines, which cannot guarantee the stability of the ozone concentration and cannot ensure the complete oxidation of organic matter and easily cause safety hazards. SUMMARY

[0005] The application is aimed at the problem that ozone cannot be accurately, quickly and stably controlled in the chemical reaction pipeline, and provides an ozone concentration adjusting control system and a stable control method for realizing self-adaptive adjustment and rapid response.

[0006] The technical scheme provided by the application is an ozone concentration adjusting control method, comprising the following steps:

[0007] (1) measuring the actual concentration of ozone gas , calculating the error value between the target ozone concentration and the actual ozone concentration , and the error change rate;

[0008] (2) dynamically adjusting the dead zone threshold, specifically as follows:

[0009] ;

[0010] ;

[0011] wherein, is the minimum dead zone threshold; is the dead zone adjustment factor;

[0012] (3) When , it is considered that the error is in the dead zone, and the control output ; if , the error at the next moment is predicted:

[0013] ;

[0014] wherein, is a prediction coefficient; is a rate of change of error;

[0015] (4) The predicted error is substituted into the control algorithm to calculate the control output; the control signal is output to the ozone generator to generate ozone with a corresponding flow rate.

[0016] The application also provides an ozone concentration adjustment control system, comprising a microcontroller, a power module, an ozone generation module, a pump valve control module and a signal acquisition module; the power module, the ozone generation module, the pump valve control module and the signal acquisition module are connected with the microprocessor;

[0017] The power module comprises a protection circuit, a general power supply, a power supply, an analog power supply and a reference power supply, and the power supplies are isolated from each other by magnetic beads; the protection circuit selects a 5A self-recovery fuse and a transient suppression diode with a threshold of 18V to realize protection of ozone generation reliability; the general power supply supplies power to other elements of the system; the power supply supplies power to the pump valve control module; the analog power supply supplies power to the signal processing circuit; and the reference power supply provides a reference voltage for the signal processing circuit;

[0018] The ozone generation module adjusts the rate of ionization of oxygen molecules and generation of ozone by controlling the discharge power of the ozone generator, so as to generate ozone with different concentrations;

[0019] The pump valve control module uses a three-way selector valve to control the flow path of ozone gas; and controls the vacuum pump to realize negative pressure in the pipe;

[0020] The signal acquisition module acquires the ozone concentration in the pipe through an ozone concentration sensor arranged at a lower position in the pipeline; and detects whether the input air pressure is out of limit or lower than the minimum working pressure through pressure sensors installed at the gas inlet section and the terminal of the pipeline;

[0021] The signal acquisition module acquires the ozone concentration in the pipeline through an ozone concentration sensor; and detects whether the input air pressure is out of limit or lower than the minimum working pressure through a pressure sensor;

[0022] The microprocessor adopts the control method to realize accurate control of the ozone concentration.

[0023] Preferably, it also includes a human-machine interaction and communication module; the human-machine interaction and communication module adopts an industrial LCD serial port screen, and communicates with the microcontroller through an RS232 serial port to display concentration, pressure, working status, and alarm information in real time; it reserves communication interfaces such as RS485, Modbus, and Ethernet for remote data interaction and control with the host computer.

[0024] The beneficial effects of this invention are as follows: The ozone concentration regulation and control system disclosed in this invention uses a microprocessor for unified control and allocation, and utilizes a photoelectric ozone concentration sensor for feedback to achieve closed-loop regulation of ozone concentration. A pump and valve control module ensures smooth flow path switching, guaranteeing a safe and efficient pipeline backflushing process. A pressure detection module ensures system reliability.

[0025] The ozone concentration regulation and control method disclosed in this invention proposes to dynamically adjust the dead zone size based on the error change rate to suppress regulation jitter; and to combine this with pre-correction of the control output based on concentration prediction error to reduce response lag. This control method can significantly improve the concentration stability, rapid response, and anti-interference capability of the ozone backwashing system, thereby increasing the efficiency of organic matter removal in the pipeline, reducing energy consumption, and improving system stability. Attached Figure Description

[0026] Figure 1 This is an overall structural block diagram of the ozone concentration regulation and control system of the present invention;

[0027] Figure 2 This is a schematic diagram showing the composition and connection relationship of ozone preparation and flow path switching in the control system;

[0028] Figure 3 This is a flowchart of the ozone concentration regulation and control method of the present invention;

[0029] Figure 4 Simulation diagrams showing the ozone concentration response before and after the introduction of the control method of this invention. Detailed Implementation

[0030] The objectives, advantages, and specific implementations of the present invention are further illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0031] Example 1 Figure 1 As shown, this embodiment provides an ozone concentration regulation and control system for chemical reaction pipelines, including a microprocessor STM32F103VET6, a power supply module, an ozone generation module, a pump and valve control module, a signal acquisition module, and a human-machine interaction and communication module.

[0032] The power module provides 12V, 5V, 3.3V power supply, including protection circuit, general power supply, power supply, analog power supply, reference power supply, electrolytic capacitor group (charge and discharge). The rated voltage of the system is 12V; the protection circuit selects a 5A self-recovery fuse and a transient suppression diode with a threshold of 18V to realize the protection of ozone generation reliability; the 12V general power supply supplies power to other elements of the control system; the power supply supplies power to the pump valve control module, and the ±12V analog power supply supplies power to the signal processing circuit; the 5V reference power supply provides a reference voltage for the signal processing circuit.

[0033] The power module provides multi-stage voltage stabilization and isolation protection for accurate ozone concentration generation and closed-loop control: the power supply end is connected to a 12V switching voltage stabilization unit, with an overcurrent protection threshold of 5A and an overvoltage threshold of 18V, to ensure reliable action of the actuator; a 5V precision voltage stabilization unit is used to support the signal accuracy of the operational amplifier and AD conversion; a 3.3V low-noise voltage stabilization unit is used to supply the control core; a ±12V isolation power module is used to supply the operational amplifier and the photoelectric detector of the sensing unit, to suppress sensing interference and reduce concentration error; multi-stage magnetic bead isolation is used to separate different power modules, to reduce noise and improve ozone concentration detection accuracy.

[0034] The ozone generation module is a sine wave output driving circuit with adjustable amplitude and frequency, which generates ozone through a dielectric barrier discharge ozone generator. The ozone generation module monitors the concentration in real time through an ozone gas sensor and generates a target deviation, dynamically adjusts the PWM modulation to generate a duty cycle that changes with the concentration deviation, removes high-order harmonics through a low-pass filter, extracts the fundamental component, and then converts it into a high-voltage sine driving signal through a full-bridge inverter circuit, cooperatively controls the voltage effective value of the signal, adjusts the discharge power to control the ozone generation rate, and realizes accurate generation of ozone concentration. In addition, the voltage level of the ozone generation module is high, to avoid electromagnetic interference and excessive temperature, the control part and the power part are reasonably arranged and insulated, and heat sinks and fans are added to enhance heat dissipation.

[0035] The pump valve control module uses a microcontroller as the control core to calculate the deviation and operate the pump valve when the flow path is switched. The vacuum pump ensures that the negative pressure in the pipe is quickly corrected, and the opening and closing of the vacuum pump are realized by a relay driving unit, and the parallel reverse electromotive force suppression module ensures the reliability of pressure regulation. The electromagnetic valve controls the flow direction of ozone to ensure consistent ozone concentration in the pipe, and the MOSFET tube switching circuit and freewheeling protection circuit control the opening and closing of the electromagnetic valve to realize accurate control of ozone flow in the pipe and stable pressure in the pipe.

[0036] The signal acquisition module is used for photoelectric ozone concentration signal acquisition and pressure signal acquisition. The ultraviolet light absorbance reaction of ozone concentration detection is relatively weak, so the electric signal generated by the photoelectric detector is very small. In order to ensure the ozone concentration detection accuracy, it needs to be converted into a digital signal output after multi-stage amplification, band pass filtering and AD conversion. First, the ozone concentration signal is collected in real time by the photoelectric detector, and then the signal-to-noise ratio is improved by a low-noise preamplifier, the ozone concentration range is dynamically adapted by a two-stage programmable gain amplifier, the interference is filtered by a band pass filter, and the concentration digital signal is generated by a 16-bit high-precision AD converter. Finally, the microcontroller is provided to calculate the deviation of the target ozone concentration. The pressure sensor converts the pressure signal into an electric signal, which is amplified by an operational amplifier, filtered, and finally sent to the microprocessor for analog-to-digital conversion to realize the acquisition of the pressure signal and ensure the safe operation of the ozone backwashing pipeline.

[0037] The human-computer interaction and communication module adopts the RS232 serial port protocol, and full-duplex communication can send and receive data at the same time, improve the communication efficiency, and has strong anti-interference ability. The microcontroller communicates with the intelligent serial port screen through the RS232 serial port to realize information interaction and instruction control. The intelligent serial port screen displays the ozone concentration value, pressure value, working state and the like, so that the running state of the equipment can be intuitively understood. The instruction is input through the touch intelligent serial port screen and converted into serial port data to be sent to the microcontroller. After receiving and analyzing the data, the microcontroller executes the operations of starting and stopping the ozone generator, opening and closing the pump valve and the like.

[0038] BEEP is a buzzer, which sounds an alarm when the system is in an abnormal condition (e.g., insufficient oxygen supply, abnormal pipeline pressure, high temperature alarm, etc.).

[0039] As shown in Figure 2 , the present embodiment provides a schematic diagram of the composition and connection relationship of ozone preparation and flow path switching in a control system. The inlet pressure switch PS1 signal acquisition monitors whether the oxygen inlet pressure is normal. The oxygen inlet is controlled by the electromagnetic valve V7. The ozone generation chamber is driven, and the ozone generation chamber preparation control is performed according to the set and actually measured ozone concentration to ensure that the output ozone concentration is within the specified range. The pressure transmitter PT1 monitors the gas pressure at the back end of the ozone concentration detector. The electromagnetic valve V6 cooperates with the vacuum pump to realize vacuum suction. The three-way electromagnetic valve V1 realizes left outlet switching (gas port 1). The three-way electromagnetic valve V4 realizes middle outlet switching (gas port 2). The electromagnetic valve V2 realizes right outlet switching (gas port 3). The electromagnetic valve V3 and the three-way electromagnetic valve V5 realize self-checking ozone tail gas discharge control and gas port 2 outlet switching. The pressure transmitter PT2 realizes the outlet gas and negative pressure value monitoring of each electromagnetic valve. The pressure switch PS2 provides overpressure protection at the outlet end. The vacuum pump cooperates with the electromagnetic valve V6 to realize vacuum suction.

[0040] Example 2 as Figure 3As shown, the embodiment provides an ozone concentration adjustment control method, the present application introduces an adaptive dead zone adjustment mechanism, the precision and response speed of the control system, introduces a concentration trend prediction adjustment mechanism, reduces the system response delay, improves the dynamic performance. The dead zone threshold is dynamically adjusted, as follows:

[0041] ;

[0042] ;

[0043] Among them, The minimum dead zone threshold is The dead zone adjustment factor is. When , it is considered that the error is in the dead zone, and the control output , that is, the current power is kept unchanged; if , the normal calculation is entered.

[0044] In a nonlinear control system, the dead zone is used to avoid the sensor noise and the system disturbance being too sensitive, thereby reducing unnecessary adjustment actions and preventing system oscillation. The traditional fixed dead zone threshold is difficult to adapt to the dynamic process. The present application determines the dead zone adjustment factor based on Lyapunov stability theory, and dynamically adjusts the dead zone size according to the error change rate. When the error change is large, the system is in a fast changing state, and the dead zone is appropriately increased to avoid the controller being too sensitive to the fast changing error and reduce control oscillation; when the error change is small, the system is close to steady state, and the dead zone is reduced to improve the control precision.

[0045] The ozone concentration control process has a lag characteristic, in order to improve the response ability of the system to the lag and sudden change, the present application combines the model predictive control method, introduces a concentration trend prediction mechanism, and constructs a short-term error first-order linear prediction model. As the basis for the controller to adjust in advance, the controller can act in advance to improve the response ability of the system. The prediction coefficient determines the step of the prediction. The larger the prediction coefficient is, the larger the prediction step is, the more sensitive the controller is to the future error change, and the stronger the advance control effect is; The smaller the prediction coefficient is, the smaller the prediction step is, and the closer the control effect is to the current error.

[0046] The ozone concentration adjustment control method of the embodiment has the following specific steps:

[0047] D1. Before the ozone preparation starts, the system is initialized and set, the relationship between the PID controller and the ozone concentration change is determined, and the parameters including the proportional gain, the integral time constant and the differential time constant are set; according to Lyapunov stability theory and experimental data, the adaptive dead zone control parameters are set, the minimum dead zone threshold , and the dead zone adjustment factor ; combined with the model predictive control method and the system response time and response speed determined by experiments, set the concentration trend prediction adjustment parameters and the sampling period , the prediction coefficient .

[0048] 1. Adaptive setting of dead zone control parameters, the specific method is as follows:

[0049] (1) Construct Lyapunov function:

[0050] ;

[0051] In the formula, reflects the function of the error size of the ozone concentration in the system; is the error value of the ozone concentration; : error change rate per unit time; is a positive weight coefficient for adjusting the proportion of error and error change rate in the system;

[0052] , take the time derivative of

[0053] .

[0054] (2) Introduce dynamic dead zone:

[0055] ;

[0056] , take the time derivative of

[0057] ;

[0058] In the formula, is a function used to represent the positive and negative of variables in mathematics, defined as:

[0059] .

[0060] (3) Establish stability condition:

[0061] In the dead zone, ; combined with steps (1) and (2), we get:

[0062] ;

[0063] In the formula, is the system damping coefficient, and ; is the control gain, .

[0064] (4) From the stability critical condition​​ Push:

[0065] ;

[0066] , reserve 20% margin, take .

[0067] 2. Concentration trend prediction adjustment parameter settings, the specific method as follows:

[0068] Experimental determination, ozone generator fixed time lag , set the sampling period .

[0069] According to the Smith predictor discretization requirements formula:

[0070] ;

[0071] In the formula, the empirical value ; calculated , take .

[0072] D2. In the process of ozone preparation, get the set ozone concentration target value , and through the photoelectric ozone concentration sensor to detect the actual ozone concentration , calculate the error value and error rate ;

[0073] ;

[0074] Where, is the sampling period.

[0075] D3. In the ozone concentration adjustment, if , it is considered that the ozone concentration has reached the satisfactory range, at this time the PID controller output , keep the current power unchanged, to avoid excessive control caused by system shock. If , enter the predicted short error:

[0076] ;

[0077] Where, is the prediction coefficient.

[0078] The predicted error is substituted into the control algorithm to form the "advance", to improve the system's ability to react in advance to lag and mutation. That is, if , execute the control algorithm:

[0079] ;

[0080] wherein, , , are proportional, integral, and derivative coefficients, respectively.

[0081] D4. Output control signals, output control signals to the ozone generator, the ozone generator according to the signal to produce a certain flow of ozone output.

[0082] D5. System adjustment and feedback. After the ozone generator adjusts the ozone concentration according to the control signal, the system will measure the actual ozone concentration again and repeat the above process to ensure that the ozone concentration is stable around the set target value. As shown in Figure 4 , after the control method of the present application is introduced, the ozone concentration and the target value are dynamically stable, which can significantly improve the concentration stability of the ozone backwashing system, and further improve the backwashing effect of the pipeline.

[0083] The above examples are only exemplary embodiments of the present application and are not intended to limit the present application. The scope of protection of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present application within the spirit and protection scope of the present application, and such modifications or equivalent replacements shall also be considered to fall within the protection scope of the present application.​

Claims

1. An ozone concentration adjustment control method characterized by: The method comprises the following steps: (1) measuring an actual concentration of ozone gas , calculating an error value of the target ozone concentration from the actual ozone concentration , and a change rate of the error ; (2) dynamically adjusting the dead zone threshold, specifically as follows: ； ； wherein, is a minimum deadband threshold; is a deadband adjustment factor: ； is a system damping coefficient; is a control gain; (3) When error is in the dead zone, the control output ; if the next time error is predicted: ； wherein, is the error rate of change; is the prediction coefficient: ； T is the ozone generator fixed time lag, ; is the sampling period; (4) substituting the predicted error into the control algorithm to calculate the control output advance: ; final control signal output to the ozone generator, ozone is generated in the corresponding flow rate.

2. An ozone concentration adjustment control system characterized by: The microprocessor, power module, ozone generation module, pump valve control module, and signal acquisition module are connected to the microprocessor. The power module includes a protection circuit, a general power supply, a power supply, an analog power supply, and a reference power supply. The protection circuit uses a 5A self-recovery fuse and a transient suppression diode with a threshold of 18V to protect the ozone generation reliability. The general power supply powers other elements of the system. The power supply powers the pump valve control module. The analog power supply powers the signal processing circuit.

3. The ozone concentration adjustment control system according to claim 2, characterized by: The reference power supply provides a reference voltage for the signal processing circuit. The ozone generation module controls the discharge power of the ozone generator to adjust the rate of oxygen molecule ionization and ozone generation, thereby producing ozone of different concentrations. The pump valve control module uses a three-way selector valve to control the flow path of ozone gas and controls the vacuum pump to achieve negative pressure in the tube. The signal acquisition module collects the ozone concentration in the pipeline through an ozone concentration sensor and detects whether the input air pressure is out of limits or below the minimum working pressure through a pressure sensor. The microprocessor uses the control method of claim 1 to achieve precise control of the ozone concentration. The system also includes a human-machine interaction and communication module. The human-machine interaction and communication module uses an industrial liquid crystal serial screen to interact with the microcontroller through an RS232 serial port for real-time display of concentration, pressure, working status, and alarm information. RS485, Modbus, and Ethernet communication interfaces are reserved for remote data interaction and control with the upper computer.

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