A distributed control system and method for valve groups

Abstract

The present invention discloses a distributed control system for valve groups and a method thereof, and belongs to the field of valve group control. The control system includes an MCU and a plurality of drive modules, wherein the MCU is powered by a weak voltage source, and the drive modules are powered by a strong voltage source. The MCU is only used to output a weak high-level signal or a weak low-level signal to each drive module as a control signal of each drive module, and a solenoid valve drive strategy is preset in each drive module. The present invention divides and simplifies the functions of the MCU, and separates the complex PWM modulation process from the MCU. When a new solenoid valve needs to be added, the addition of the new switch valve can be completed by cooperating with a drive module that also completes program control. The MCU only needs to output one more set of high and low-level weak current signals, and the MCU only needs to have enough I / O ports to realize this function, which is extremely beneficial for large-scale valve group control.

Description

Technical Field

[0001] The invention belongs to a solenoid valve group control system, and in particular relates to a valve group-oriented distributed control system and a method thereof. Background Art

[0002] With the development of digital switch valve technology, its basic properties such as linear operating frequency, dynamic characteristics, pressure characteristics and energy consumption characteristics have been improved to varying degrees. Among them, solenoid valves have attracted people's research and attention due to their many advantages such as low price, strong anti-pollution ability, simple structure, reliable operation and easy computer interface. The solenoid switch valve (solenoid valve) that modulates the input signal through PWM is much lower in cost than the servo valve, and is suitable for use in large-scale valve group control work occasions.

[0003] In the past, valve group control methods mostly directly controlled input and output through the system. The central processing unit or microcontroller unit (MCU) received the sensor detection signal and then performed PID modulation processing, and then directly output the control signal to control the solenoid valve in real time. However, for large-scale valve group control systems, the MCU will occupy more performance.

[0004] The integrated board of the traditional valve group control method must realize the simultaneous supply of weak power and strong power to the MCU and the signal method module, so the strong and weak power are on the same board. Such a strong and weak power layout will cause the strong power signal to interfere with the reception and transmission of the weak power signal, that is, there will be strong interference to the MCU output signal and the receiving sensor feedback signal, causing signal distortion, which greatly affects the actual control effect of the solenoid valve group.

[0005] In traditional valve group control technology, the MCU is responsible for receiving sensor signals, processing signals, and modulating and outputting PWM signals. PWM signal modulation requires calling counters in the MCU, which are already few in number and occupy computing resources. In the modulation process, each control signal modulation requires an independent counter. The equivalent cost of the number of counters in the MCU is relatively huge, and for large-scale valve group control, the MCU computing resources occupied by the complex modulation process are also relatively huge.

[0006] The traditional valve group control method needs to increase the output PWM modulation waveform when the number of controlled solenoid valves needs to be increased. Adding a new counter in the MCU is not cheap, and calculating more modulation waveforms will also occupy more computing resources. At the same time, if the number of MCUs is increased, it is not reasonable in terms of cost. Summary of the invention

[0007] In order to solve the problems in the prior art, the present invention proposes a distributed control system for valve groups and a method thereof. The method separates strong electricity from weak electricity, effectively solving the practical problem of MCU controlling large-scale valve groups. Compared with traditional methods, the control method has the characteristics of anti-interference, improved system control performance and strong scalability.

[0008] The technical solution of the present invention is as follows:

[0009] The present invention first provides a distributed control system for a valve group, which includes an MCU and multiple drive modules, wherein the MCU is powered by a weak voltage source, and the drive modules are powered by a strong voltage source;

[0010] The MCU is only used to output a weak high-level signal or a weak low-level signal to each drive module as a control signal of each drive module. The weak high-level signal represents the opening signal of the valve, and the weak low-level signal represents the closing signal of the valve.

[0011] Each driving module drives a valve; the driving module is preset with a valve opening stage driving strategy and a valve closing stage driving strategy; when the driving module receives a weak electric high level signal, the driving module outputs the opening stage driving strategy to control the valve, so that the valve switches or maintains the open state; when the driving module receives a weak electric low level signal, the driving module outputs the closing stage driving strategy to control the valve, so that the valve closes or maintains the closed state.

[0012] As a preferred embodiment of the present invention, the start-up phase driving strategy includes two phases: high-level start-up and start-up maintenance. When the driving module receives a weak-current high-level signal, it immediately enters the high-level start-up phase. After the high-level start-up phase continues for a set time, it enters the start-up maintenance phase. When the driving module receives a weak-current low-level signal, the start-up maintenance phase ends and the closing phase driving strategy is immediately output.

[0013] As a preferred solution of the present invention, in the high-level start-up stage, the driving module modulates the output voltage of the strong voltage source with a duty cycle of 100% and uses it as the driving voltage of the valve. At this time, the equivalent voltage value of the driving voltage of the valve is the voltage value V of the strong voltage source, and the positive driving voltage drives the valve to open quickly;

[0014] In the opening and maintaining stage, the driving module modulates the output voltage of the strong voltage source with a PWM signal with a set duty cycle α so that it outputs a maintaining driving voltage with a duty cycle of α. The equivalent voltage value of the maintaining driving voltage is α·V. Under the action of the maintaining driving voltage, the coil current drops to a current value equal to %105-%110 of the closing current and is maintained; since the coil current is still greater than the closing current at this time, the valve will still maintain an open state in this stage.

[0015] As a preferred embodiment of the present invention, the driving strategy in the closing phase includes at least two phases: reverse high-level closing and closing maintenance. When the driving module receives a weak low-level signal, it immediately enters the reverse high-level closing phase, and the reverse high-level closing phase continues until the coil current is 0 and then enters the closing maintenance phase.

[0016] As a preferred embodiment of the present invention, in the reverse high-level closing stage, the driving module modulates the output voltage of the strong voltage source with a duty cycle of -100% and uses it as the driving voltage of the valve. At this time, the equivalent voltage value of the driving voltage of the valve is -V, wherein V is the voltage value of the strong voltage source. The driving voltage drives the valve to close quickly. Under the action of the driving voltage, the coil current drops to 0 and enters the closing maintenance stage. In the closing maintenance stage, the output duty cycle of the driving module is 0, and the driving voltage of the coil is 0.

[0017] As a preferred embodiment of the present invention, the closing phase driving strategy also includes a preloading phase. After the closing maintenance phase lasts for a set time, the driving module modulates the output voltage of the strong voltage source with a PWM signal with a set duty cycle β so that it outputs a preloading driving voltage with a duty cycle of β, and maintains the equivalent voltage value of the driving voltage to β·V. Under the action of the preloading driving voltage, the coil current rises to a current value of 90%-95% of the opening current and is maintained; since the coil current is still less than the opening current at this time, the valve will still maintain a closed state at this stage.

[0018] As a preferred solution of the present invention, the output voltage value of the weak voltage source is 5V, and the output voltage value of the strong voltage source is 24V; the weak current high level signal is 5V level, and the weak current low level signal is 0 level.

[0019] The present invention also provides a valve group-oriented distributed control method of the system, which comprises the following steps:

[0020] S1: According to the flow requirements of each valve, a driving strategy is preset in each driving module in advance; the driving strategy of each driving module is only for the valve it drives;

[0021] S2: MCU outputs a weak current control signal to each drive module. The weak current control signal is a periodic signal, which is composed of a weak current high level signal and a weak current low level signal. The weak current high level signal represents the valve opening signal, and the weak current low level signal represents the valve closing signal. Among them, the weak current control signal output by MCU to each drive module can be the same or different.

[0022] S3: After receiving the weak current control signal, each drive module drives the valve according to the preset drive strategy

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In the method of the present invention, the separation of strong and weak electricity is separated by MCU function, and the conversion of simple high and low level electromagnetic valve switch signals into complex preload voltage control waveform output functions is implemented by a drive module that is not in direct contact with the MCU. Therefore, the MCU and the drive module are both powered by independent weak power supplies and strong power supplies, and there is no crossover between strong and weak electricity, so the interference of weak current signals can be greatly reduced.

[0025] The present invention receives weak current signals from a driving module and then converts them into strong current control signals for electromagnetic valves to realize distributed system control of valve groups. In this method, the opening and closing signals are relatively simple, and the complex preload voltage signals are realized by an amplifier circuit that has completed program control. The MCU only outputs high and low level weak current signals, which can make better use of its performance compared to the MCU directly outputting strong current control signals.

[0026] The present invention is more expansive in practical applications. Because the driving module shares the complex control process of the MCU in the traditional solution and has modular characteristics, when a new solenoid valve needs to be added, it only needs to cooperate with the driving module that also completes the program control to complete the addition of the new solenoid valve. The MCU only needs to output one more set of high and low level weak current signals, and the MCU only needs to have enough I / O ports to realize this function, which is extremely beneficial for large-scale valve group control. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the integrated version used for traditional MCU valve group control technology;

[0028] Figure 2 This is a schematic diagram of a distributed control system for valve groups of the present invention;

[0029] Figure 3 It is a schematic diagram of MCU output and driver module output of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0031] like Figure 1 As shown in the figure, the traditional MCU valve group control technology uses an integrated board for control. The integrated board includes an MCU and a signal amplification module. At the same time, the board has a strong voltage source and a weak voltage source to power the signal amplification module and the MCU respectively. After the MCU analyzes the strong electric control signal required by the solenoid valve, it first modulates and outputs a preloaded PWM signal, which is amplified and converted into the strong electric control signal required by the solenoid valve by the signal amplification module.

[0032] The solenoid valve control system implemented by this traditional method has high requirements for the MCU. Because the MCU directly outputs the modulated PWM control signal, and the modulated output of the single signal requires the mobilization of a counter on the MCU to achieve it. The counters on the MCU are limited, and the cost of the MCU will increase significantly with each additional counter. Therefore, for large-scale valve group control, the traditional integrated control method has corresponding difficulties in terms of feasibility, convenience and cost considerations in the actual control process.

[0033] Based on the current status of valve group distributed control system, such as Figure 2 As shown, this embodiment proposes a distributed control system for valve groups, which includes: an MCU and multiple drive modules. Among them, the MCU is only used to output simple high-level voltages and low-level voltages to each drive module. The high-level voltage represents the valve opening signal, and the low-level voltage represents the valve closing signal. Both the high-level voltage and the low-level voltage are weak-current signals. After the weak-current signal is input to the drive module, the drive module will convert it into a preloaded strong-current control signal according to the pre-adjusted driver program. In this way, the MCU can control large-scale valve groups with relatively simple information output, Figure 2 The simultaneous control of three solenoid valves is only an example, and more solenoid valves can be controlled in practice. The drive module of the present invention is powered by a strong voltage source.

[0034] Each driving module of the present invention drives a valve; the driving module is preset with a valve opening phase driving strategy and a valve closing phase driving strategy; when the driving module receives a weak current high level signal, the driving module outputs the opening phase driving strategy to control the valve, so that the valve switches or maintains an open state; when the driving module receives a weak current low level signal, the driving module outputs the closing phase driving strategy to control the valve, so that the valve closes or maintains a closed state.

[0035] The start-up phase driving strategy of the present invention includes two phases: high-level start-up and start-up maintenance. When the driving module receives a weak-current high-level signal, it immediately enters the high-level start-up phase. After the high-level start-up phase lasts for a set time, it enters the start-up maintenance phase. When the driving module receives a weak-current low-level signal, the start-up maintenance phase ends and the closing phase driving strategy is immediately output.

[0036] Furthermore, in the high-level start-up stage, the driving module modulates the output voltage of the strong voltage source with a duty cycle of 100% and uses it as the driving voltage of the valve. At this time, the equivalent voltage value of the driving voltage of the valve is the voltage value V of the strong voltage source, and the positive driving voltage drives the valve to open quickly;

[0037] In the opening and maintaining stage, the driving module modulates the output voltage of the strong voltage source with a PWM signal with a set duty cycle α so that it outputs a maintaining driving voltage with a duty cycle of α. The equivalent voltage value of the maintaining driving voltage is α·V. Under the action of the maintaining driving voltage, the coil current drops to a current value equal to %105-%110 of the closing current and is maintained; since the coil current is still greater than the closing current at this time, the valve will still maintain an open state in this stage.

[0038] The driving strategy in the closing phase of the present invention includes reverse high-level closing, closing maintenance and preloading phases; when the driving module receives a weak low-level signal, it immediately enters the reverse high-level closing phase, and the reverse high-level closing phase continues until the coil current is 0 and enters the closing maintenance phase. In the reverse high-level closing phase, the driving module modulates the output voltage of the strong voltage source with a duty cycle of -100% and uses it as the driving voltage of the valve. At this time, the equivalent voltage value of the driving voltage of the valve is -V, where V is the voltage value of the strong voltage source. The driving voltage drives the valve to close quickly. Under the action of the driving voltage, the coil current drops to 0 and enters the closing maintenance phase. In the closing maintenance phase, the output duty cycle of the driving module is 0, and the driving voltage of the coil is 0 at this time. After the closed maintenance stage lasts for a set time, the drive module modulates the output voltage of the strong voltage source with a PWM signal with a set duty cycle β to make it output a preloaded drive voltage with a duty cycle of β, and maintains the equivalent voltage value of the drive voltage to β·V. Under the action of the preloaded drive voltage, the coil current rises to a current value of 90%-95% of the opening current and maintains it; since the coil current is still less than the opening current at this time, the valve will still remain in a closed state during this stage.

[0039] In a specific embodiment of the present invention, the MCU outputs Figure 3 The weak current information signal shown in the figure. According to the preset program, the driving module converts the high level stage (i.e., stage T2-T4) in the weak current information signal into the opening voltage signal in the preload control strategy; and converts the low level stage (i.e., stage T4-T7) into the closing voltage signal in the preload control strategy. And the converted signal is converted into a strong current control signal to achieve precise control of each electromagnetic high-speed switch valve.

[0040] The voltage in the preload control strategy of the high-speed electromagnetic switch valve is as follows Figure 2As shown, T2-T4 is the opening stage, which consists of a high-level opening voltage and a PWM maintenance voltage; T4-T7 is the closing stage, which consists of a reverse closing high voltage, 0 voltage and an opening preloading stage. The T1-T2 stage is the opening preloading stage. The purpose of voltage loading in this stage is to increase the coil current to the range of %90-%95 of the opening current, so as to shorten the opening lag time of the solenoid valve; the T2-T3 stage is the high-level opening stage. The purpose of voltage loading in this stage is to enable the solenoid valve to open quickly; the T3-T4 stage is the PWM maintenance stage. The purpose of voltage loading in this stage is to reduce the coil current to the range of %105-%110 of the closing current, so as to shorten the closing lag time of the solenoid valve; since the current in this stage is still greater than the closing current, the solenoid valve will still maintain the open state in this stage. The T4-T5 stage is the reverse high voltage loading stage. The purpose of voltage loading in this stage is to quickly lower the coil current and close the solenoid valve quickly; the T5-T6 stage is the 0 voltage loading stage. The purpose of voltage loading in this stage is the same as the reverse high voltage. Since the reverse high voltage cannot be loaded for a long time, the reverse high voltage is used in combination with the 0 voltage to realize the rapid closing function of the solenoid valve. The opening and closing stages of the solenoid valve both start with the arrival of the opening / closing signal, as shown below Figure 1 Taking a cycle as an example, T2 is the starting point of the turn-on signal of this cycle, and T4 is the starting point of the turn-off signal.

[0041] When a weak current high level signal is received, the driving module outputs a preloaded start voltage signal starting from time T2, and maintains the voltage after the high voltage start signal ends; when a weak current low level signal is received, the amplifier circuit outputs a preloaded close voltage signal starting from time T4, and maintains 0 voltage after the reverse high voltage close signal ends. Thus, a control method for a strong and weak current separated electromagnetic high-speed switch valve (solenoid valve) is realized, which includes outputting a weak current information signal - processing a control signal by an amplifier circuit - outputting a strong current control signal by an amplifier circuit.

[0042] The control system of the present invention separates the functions of the integrated circuit, and further proposes a distributed control method for valve groups with separation of strong and weak electricity. The method divides and simplifies the functions of the MCU, and separates the complex PWM modulation process from the MCU. The MCU and the drive module are both powered by independent weak power supplies and strong power supplies, and there is no crossover between strong and weak electricity, so the interference of weak current signals can be greatly reduced. When a new solenoid valve needs to be added, the addition of the new solenoid valve can be completed by cooperating with a drive module that also completes program control. The MCU only needs to output one more set of high and low level weak current signals, and the MCU only needs to have enough I / O ports to realize this function, which is extremely beneficial for large-scale valve group control.

[0043] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A distributed control system for valve groups, characterized in that: It includes an MCU and a plurality of drive modules, wherein the MCU is powered by a weak voltage source and the drive modules are powered by a strong voltage source; The MCU is only used to output a weak high-level signal or a weak low-level signal to each drive module as a control signal of each drive module. The weak high-level signal represents the opening signal of the valve, and the weak low-level signal represents the closing signal of the valve. Each driving module drives a valve; the driving module is preset with a valve opening stage driving strategy and a valve closing stage driving strategy; when the driving module receives a weak electric high level signal, the driving module outputs the opening stage driving strategy to control the valve, so that the valve is opened or maintained in an open state; when the driving module receives a weak electric low level signal, the driving module outputs the closing stage driving strategy to control the valve, so that the valve is closed or maintained in a closed state.

2. The valve group-oriented distributed control system according to claim 1, characterized in that: The start-up phase driving strategy includes two phases: high-level start-up and start-up maintenance. When the driving module receives a weak-current high-level signal, it immediately enters the high-level start-up phase. After the high-level start-up phase lasts for a set time, it enters the start-up maintenance phase. When the driving module receives a weak-current low-level signal, the start-up maintenance phase ends and the closing phase driving strategy is immediately output.

3. The valve group-oriented distributed control system according to claim 2, characterized in that: In the high-level opening stage, the driving module modulates the output voltage of the strong voltage source with a duty cycle of 100% and uses it as the driving voltage of the valve. At this time, the equivalent voltage value of the driving voltage of the valve is the voltage value V of the strong voltage source, and the positive driving voltage drives the valve to open quickly; In the opening and maintaining stage, the driving module modulates the output voltage of the strong voltage source with a PWM signal with a set duty cycle α so that it outputs a maintaining driving voltage with a duty cycle of α. The equivalent voltage value of the maintaining driving voltage is α·V. Under the action of the maintaining driving voltage, the coil current drops to a current value equal to 105%-110% of the closing current and is maintained; because the coil current is still greater than the closing current at this time, the valve will still maintain an open state in this stage.

4. The distributed control system for valve groups according to claim 1, characterized in that: The driving strategy in the closing phase includes at least two phases: reverse high-level closing and closing maintenance. When the driving module receives a weak low-level signal, it immediately enters the reverse high-level closing phase, and the reverse high-level closing phase continues until the coil current is 0 and then enters the closing maintenance phase.

5. The valve group-oriented distributed control system according to claim 4, characterized in that: In the reverse high-level closing stage, the driving module modulates the output voltage of the strong voltage source with a duty cycle of -100% and uses it as the driving voltage of the valve. At this time, the equivalent voltage value of the driving voltage of the valve is -V, where V is the voltage value of the strong voltage source. The driving voltage drives the valve to close quickly. Under the action of the driving voltage, the coil current drops to 0 and enters the closing maintenance stage. In the closing maintenance stage, the output duty cycle of the driving module is 0, and the driving voltage of the coil is 0.

6. The valve group-oriented distributed control system according to claim 4, characterized in that: The closing phase driving strategy also includes a preloading phase. After the closing maintenance phase lasts for a set time, the driving module modulates the output voltage of the strong voltage source with a PWM signal with a set duty cycle β so that it outputs a preloading driving voltage with a duty cycle of β, and maintains the equivalent voltage value of the driving voltage to β·V. Under the action of the preloading driving voltage, the coil current rises to a current value of 90%-95% of the opening current and is maintained; since the coil current is still less than the opening current at this time, the valve will still maintain a closed state in this stage.

7. The valve group-oriented distributed control system according to claim 4, characterized in that: The output voltage value of the weak voltage source is 5V, and the output voltage value of the strong voltage source is 24V; the weak current high level signal is 5V level, and the weak current low level signal is 0 level.

8. A valve group-oriented distributed control method for the system of claim 1, characterized in that The steps include: S1: The driving strategy needs to be preset in each driving module according to the flow rate of each valve; the driving strategy of each driving module is only for the valve it drives; S2: MCU outputs a weak current control signal to each drive module. The weak current control signal is a periodic signal, which is composed of a weak current high level signal and a weak current low level signal. The weak current high level signal represents the valve opening signal, and the weak current low level signal represents the valve closing signal. Among them, the weak current control signal output by MCU to each drive module can be the same or different. S3: After receiving the weak current control signal, each driving module drives the valve according to the preset driving strategy; the driving module has preset valve opening stage driving strategy and closing stage driving strategy; when the driving module receives the weak current high level signal, the driving module outputs the opening stage driving strategy to control the valve, so that the valve switches or maintains the open state; when the driving module receives the weak current low level signal, the driving module outputs the closing stage driving strategy to control the valve, so that the valve closes or maintains the closed state.

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