Electric propulsion flow control method and system

Abstract

The invention belongs to a flow control method, and provides an electric propulsion flow control method and system aiming at the technical problems that a flow control unit in an existing electric propulsion system is long in reaction time, small in flow adjusting range, complex in structure and high in control method complexity. Wherein two branches serve as an anode and a cathode of the thruster, and each branch performs closed-loop control on the electric propulsion flow according to the real-time pressure detection results of the first pressure detection piece and the second pressure detection piece in combination with the pressure reduction degree of the propellant, the parameters of the first electromagnetic valve and the parameters of the second electromagnetic valve. The control accuracy is high, the flow adjusting range is wide, and light weight is achieved.

Description

Technical Field

[0001] The present application relates to a flow control method, and specifically to an electric propulsion flow control method and system. Background Art

[0002] The electric propulsion system is composed of multiple units, among which the flow control unit directly controls the conduction and cut-off of the propellant, and the accuracy of the flow control unit directly affects the thrust output accuracy and thrust stability of the electric thruster. Therefore, the flow control unit is one of the most important subsystems in the electric propulsion system.

[0003] At present, the overall structure of the flow control unit includes three parts: gas volume, pressure control module and flow control module. There are mainly the following problems: (1) The flow control module mainly adopts a fixed structure throttling method. The response time is long and the flow adjustment range is small. At the same time, since the throttling device is usually made of special materials and processes, the consistency of the throttling device is poor, which increases the overall complexity.

[0004] (2) An independent pressure control module is used, which requires the configuration of a gas container. In actual applications, multiple shut-off valves and solenoid valves are also required, which results in high overall complexity and large size.

[0005] (3) Open-loop control mode is often used, which requires ground analysis of telemetry data to evaluate the thrust size and issue corresponding commands for thrust control and adjustment. However, the procedures for sending space commands are often complicated. Summary of the invention

[0006] The present application aims to provide an electric propulsion flow control method and system to address the technical problems that the flow control unit in the current electric propulsion system has a long response time, a small flow adjustment range, a complex structure and a high degree of complexity in the control method.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions: In a first aspect, the present application proposes an electric propulsion flow control method, comprising: Depressurizing high pressure stored propellant; The decompressed propellant is transported along at least two branches, wherein the two branches serve as the anode and cathode of the thruster; a first solenoid valve and a second solenoid valve are arranged along the transport direction of each branch, and a first pressure detection member and a second pressure detection member are arranged at the front side and the rear side of the first solenoid valve, respectively; Each branch performs closed-loop control on the electric propulsion flow rate according to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, combined with the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve.

[0008] Furthermore, the method for performing closed-loop control of the electric propulsion flow rate by combining the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve comprises: Fixing the parameters of the first solenoid valve; According to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, a pressure conversion algorithm is used to obtain real-time flow data; According to the difference between the real-time flow data and the flow setting value, the parameters of the second solenoid valve are adjusted to perform closed-loop control.

[0009] Furthermore, the method for performing closed-loop control of the electric propulsion flow rate by combining the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve comprises: According to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, the fitting relationship between the pressure difference and the flow rate is determined in combination with the parameters of the first solenoid valve to obtain the corresponding flow rate index; According to the flow index, the parameters of the second solenoid valve are adjusted so that the pressure is at the pressure setting value, and closed-loop control is performed.

[0010] Furthermore, the method also includes changing the accuracy and adjustable range of flow regulation by adjusting the parameters of the first solenoid valve.

[0011] Furthermore, it also includes adjusting the degree of decompression of the propellant.

[0012] Furthermore, the method for performing closed-loop control comprises: Fix the parameters of the first solenoid valve, and establish a corresponding relationship table between the parameters of the second solenoid valve and the flow rate at the rear side of the second solenoid valve; According to the flow value required at the rear side of the second solenoid valve, the corresponding parameters of the second solenoid valve are queried in the flow correspondence table, and the parameters of the second solenoid valve are set; Comparing the real-time flow value at the rear side of the second solenoid valve with the required flow value at the rear side of the second solenoid valve to obtain a real-time deviation; The parameter adjustment amount of the second solenoid valve is obtained through the PID algorithm according to the real-time deviation, and the parameters of the second solenoid valve are adjusted.

[0013] Furthermore, flow calibration is also included: The opening degree or the switching frequency of the first solenoid valve is fixed, and the opening degree or the switching frequency of the second solenoid valve is gradually adjusted so that the flow rate at the rear side of the second solenoid valve reaches a plurality of preset flow rate values, and at each preset flow rate value, the detection results of the first pressure detection component and the second pressure detection component are synchronously recorded to obtain the corresponding pressure difference between the first pressure detection component and the second pressure detection component; According to multiple sets of preset flow values ​​and the corresponding pressure difference between the first pressure detection component and the second pressure detection component, the following flow correction formula is calculated: and :

[0014] in, is the flow value, is the flow coefficient, is the pressure difference between the first pressure detection member and the second pressure detection member, is the linear correction coefficient; According to the detection results of the first pressure detection component and the second pressure detection component, the corresponding flow value is calculated by the flow correction formula and compared with the real-time flow value on the rear side of the second solenoid valve. If the error requirements are met, the flow calibration is completed.

[0015] Furthermore, it also includes temperature calibration: The switching frequency of the first solenoid valve is fixed, the temperature is gradually adjusted to a plurality of preset temperature values, and the parameters of the second solenoid valve are adjusted at each preset temperature value so that the pressure difference between the first pressure detection element and the second pressure detection element remains unchanged; At each pressure difference and preset temperature value, record the corresponding flow rate at the rear side of the second solenoid valve; According to each pressure difference and preset temperature value, and the corresponding flow rate behind the second solenoid valve, calculate the following temperature correction formula: and :

[0016] in, is a function of temperature, is the temperature correction function; Different parameters and temperatures of the second solenoid valve are randomly selected, the corresponding flow value is calculated by the temperature correction formula, and compared with the real-time flow value on the rear side of the second solenoid valve. If the error requirements are met, the temperature calibration is completed.

[0017] In a second aspect, the present application proposes an electric propulsion flow control system for implementing the above-mentioned electric propulsion flow control method, comprising a flow control module, and an air source, a pressure reducing valve and at least two branches connected in sequence; The gas source is used to store propellant at high pressure; The pressure reducing valve is used to reduce the pressure of the propellant stored under high pressure; Each branch is provided with a first solenoid valve and a second solenoid valve along the conveying direction, and a first pressure detection member and a second pressure detection member are provided at the front and rear sides of the first solenoid valve, respectively; it is used to convey the decompressed propellant along at least two branches, wherein the two branches serve as the anode and cathode of the thruster; The flow control module is respectively connected to the first pressure detection component, the first solenoid valve, the second pressure detection component and the second solenoid valve, and performs closed-loop control of the electric propulsion flow based on the real-time pressure detection results of the first pressure detection component and the second pressure detection component, combined with the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve.

[0018] Further, it also includes a stop valve; The stop valve is connected between the gas source and the pressure reducing valve, and is used to control the conduction and cutoff of the electric propulsion flow control system.

[0019] Compared with the prior art, this application has the following beneficial effects: The present application proposes an electric propulsion flow control method, which decompresses the high-pressure stored propellant and then transports it along at least two branches, wherein the two branches serve as the anode and cathode of the thruster, and each branch performs closed-loop control on the electric propulsion flow according to the real-time pressure detection results of the first pressure detection member and the second pressure detection member, combined with the degree of decompression of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve. The present application only involves a device for decompressing the high-pressure stored propellant, a pressure detection member on each branch and two solenoid valves. The hardware structure is simple and lightweight, which is in line with the current development trend of electric propulsion flow control. The variable structure throttling based on the solenoid valve is adopted, which has high operating accuracy, fast response, and extremely wide flow adjustment range and high accuracy while being lightweight. When performing flow control, closed-loop control can be performed according to the real-time pressure detection results of the first pressure detection member and the second pressure detection member. Even if errors occur in each component due to long-term use, they can be corrected in time through closed-loop control to ensure the accuracy of control.

[0020] The present application also proposes an electric propulsion flow control system, which can implement the above-mentioned electric propulsion flow control method and has all the advantages of the above-mentioned electric propulsion flow control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of a flow chart of the electric propulsion flow control method of the present application; Figure 2 This is a first schematic diagram of the electric propulsion flow control system of the present application; Figure 3 This is a second schematic diagram of the electric propulsion flow control system of the present application; Figure 4 This is a schematic diagram of a calibration system of an electric propulsion flow control system in an embodiment of the present application; Figure 5 This is a schematic diagram of a practical use of the electric propulsion flow control method of the present application in an embodiment of the present application; Figure 6 This is a schematic diagram of the PID control algorithm of the electric propulsion flow control system in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0027] With the development and maturity of space electric propulsion technology, the application areas of space electric propulsion technology have expanded from geostationary orbit satellites to deep space probes, medium-orbit satellites, low-orbit satellites and their constellations, ultra-low-orbit spacecraft, manned spaceflight and in-orbit maintenance, etc., which have put forward increasingly higher requirements for the orbit prediction and control of modern satellite platforms.

[0028] The electric propulsion system is composed of multiple units, among which the flow control unit plays an important role, directly controlling the conduction and cut-off of the propellant. The accuracy of flow control directly affects the thrust output accuracy and thrust stability of the electric thruster. At present, the overall structure of the flow control unit mostly includes three parts: gas volume, pressure control module and flow control module. In practical applications, most flow control modules use tiny holes or flow channels to achieve throttling, adjust the flow rate by electric heating or changing the inlet pressure, and use valves to achieve the conduction and shutoff of the propellant. These throttling devices include porous materials, throttling orifices, capillaries, etc. Due to the use of electric heating, the reaction time is generally long and the flow adjustment range is small. At the same time, the throttling devices are mostly made of special materials and processes, with poor product consistency, which increases the complexity of the entire system control. Furthermore, many flow control systems use independent pressure control modules, which need to be matched with gas volume, multiple shut-off valves, solenoid valves and other components. These components increase the complexity and volume of the entire system, making the system larger and more difficult to manage. For small flow control units, the flow adjustment range is often also very small, which limits its application range. In addition, the flow control unit mostly adopts an open-loop control mode, which requires ground analysis of telemetry data to evaluate the thrust size and issue corresponding instructions for thrust control and adjustment. However, the space command sending procedure is complicated and has many influencing factors, which increases the complexity of the entire operation. Long-term operation of the system may also cause the performance of components such as pressure reducing valves and solenoid valves to deteriorate, resulting in problems such as the inability to maintain thrust for a long time, which not only affects the reliability of the system, but also increases the cost of maintenance and repair.

[0029] Based on the above situation, the present application proposes an electric propulsion flow control method and system, and the present application is described in detail below in conjunction with embodiments and drawings.

[0030] like Figure 1 As shown, it is a schematic diagram of a flow chart of the electric propulsion flow control method of the present application, which may include: S101, decompressing the propellant stored at high pressure.

[0031] In practical applications, propellants are usually stored in high-pressure containers to maintain liquid or high-density gas state for easy storage and transportation. Decompression can ensure stable and efficient supply of propellants in subsequent systems.

[0032] S102, conveying the decompressed propellant along at least two branches, wherein the two branches serve as the anode and cathode of the thruster; each branch is provided with a first solenoid valve and a second solenoid valve along the conveying direction, and a first pressure detection component and a second pressure detection component are respectively provided on the front and rear sides of the first solenoid valve.

[0033] The first pressure detection element is installed on the front side of the first solenoid valve to monitor the pressure of the propellant before entering the first solenoid valve. The second pressure detection element is installed on the rear side of the second solenoid valve to monitor the pressure of the propellant after passing through the second solenoid valve. The pressure data collected by the pressure detection element can be transmitted in real time for subsequent flow control calculations.

[0034] During the operation of the thruster, the anode and cathode work together to maintain the normal operation of the thruster. The electrons emitted by the anode enter the discharge channel under the action of the electric field and collide with the propellant gas, ionizing it into a mixture of ions and electrons (i.e., plasma). The ions gain energy under the action of the electric field and are ejected at high speed, thereby generating thrust. At the same time, the electrons emitted by the cathode are used to neutralize the ejected ion flow and maintain the electrical neutrality of the entire circuit. By precisely controlling the flow of the anode and cathode, the ionization process and ion acceleration effect of the thruster can be optimized, thereby improving the efficiency and stability of the thruster.

[0035] It should be noted that in other embodiments of the present application, three branches may be provided, and the third branch may be used as a neutralizer for the thruster. Alternatively, more branches may be provided for multiple thrusters or as backup branches, which may be adjusted according to actual use needs.

[0036] S103, each branch performs closed-loop control on the electric propulsion flow rate according to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, combined with the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve.

[0037] In practical applications, the propellant flow rate can be precisely controlled by comprehensively analyzing the pressure detection results, the degree of decompression, and the parameters of the two solenoid valves. A feedback mechanism can also be set accordingly to make real-time adjustments based on the deviation between the actual flow rate at the rear of the second solenoid valve and the set flow rate to ensure the stability of the flow rate.

[0038] Correspondingly, such as Figure 2 As shown, it is a first schematic diagram of the electric propulsion flow control system of the present application, which can implement the above-mentioned electric propulsion flow control method and may include a flow control module, and an air source, a pressure reducing valve and at least two branches connected in sequence.

[0039] The gas source is used for storing propellant at high pressure; the pressure reducing valve is used for reducing the pressure of the propellant stored at high pressure; a first solenoid valve and a second solenoid valve are provided on the upper conveying direction of each branch, and a first pressure detecting component and a second pressure detecting component are provided on the front and rear sides of the first solenoid valve respectively; it is used for conveying the decompressed propellant along at least two branches, wherein the two branches serve as the anode and cathode of the thruster; the flow control module is respectively connected to the first pressure detecting component, the first solenoid valve, the second pressure detecting component and the second solenoid valve, and performs closed-loop control of the electric propulsion flow rate according to the real-time pressure detection results of the first pressure detecting component and the second pressure detecting component, in combination with the degree of decompression of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve. It should be noted that Figures 2 to 5 In the figure, P1 represents a first pressure detection component, and P2 represents a second pressure detection component.

[0040] Among them, the gas source uses a gas cylinder to store propellant at high pressure, with a pressure of 3-10Mpa. The first solenoid valve can be directly used to control the opening and closing of the propellant. The pressure reducing valve converts the high-pressure stored propellant gas into a low-pressure gas of 0.2±0.02Mpa for further flow control. The first pressure detection component and the second pressure detection component collect pressure information in real time and return it to the flow control module. The first solenoid valve and the second solenoid valve can adjust parameters according to the analog signal output by the flow control module.

[0041] In some embodiments of the present application, if the first solenoid valve and the second solenoid valve are bang-bang valves (a relay-type control valve), the switching frequency and the switching time of each switch can be adjusted. If the first solenoid valve and the second solenoid valve are proportional valves, the corresponding valve opening can be adjusted by adjusting the input current.

[0042] In this embodiment, other branches are also included, two of which serve as the anode and cathode of the thruster. Each branch is implemented in the same way, that is, it includes a first pressure detection member, a first electromagnetic valve, a second pressure detection member and a second electromagnetic valve connected in sequence.

[0043] In the actual control process, the following three control methods in the embodiments of the present application can be used: (1) The first solenoid valve is used as a flow calibration device, and the second solenoid valve is used as a flow control device. Specifically, the first solenoid valve uses fixed parameters to obtain data from the first pressure detection component and the second pressure detection component in real time, and feeds it back to the flow control module. The flow control module first obtains real-time flow data based on the pressure conversion algorithm and compares it with the current flow setting value. If there is a gap, the parameters of the second solenoid valve are changed according to the flow control algorithm until the flow is stable and meets the requirements, and waits for the next flow change instruction.

[0044] It should be noted that the pressure conversion algorithm is usually used to convert the physical quantity measured by the pressure detection device into a flow value. According to the specific configuration of the system and the properties of the fluid, a mathematical model of pressure and flow can be established for calculation.

[0045] (2) Use the first solenoid valve and the second solenoid valve for joint flow regulation. Specifically, the flow control module obtains the data of the first pressure detection component and the second pressure detection component in real time, and determines the fitting relationship between the pressure difference and the flow rate according to the parameters of the first solenoid valve. The pressure difference is the pressure difference measured by the first pressure detection component and the second pressure detection component. The specific flow index is obtained, and the parameters of the second solenoid valve are modified to change or maintain the pressure at the desired level. At the same time, by changing the parameters of the first solenoid valve, the accuracy and adjustment range of the flow regulation can also be changed to achieve more precise regulation.

[0046] (3) Use the first solenoid valve, the second solenoid valve and the pressure reducing valve to jointly adjust the flow. Specifically, based on the first two methods, the flow control module adds control over the front-stage pressure reducing valve, which can control the pressure at the pressure reducing valve outlet, and fit the relationship between the pressure difference and the flow at different pressure reducing valve outlet pressures, and integrate it into the closed-loop control system.

[0047] like Figure 3 FIG. 1 is a second schematic diagram of the electric propulsion flow control system of the present application, which can further include a stop valve based on the above-mentioned embodiment. The entire system can be turned on and off by the stop valve.

[0048] It has been verified that the flow rate adjustment range that this application can provide is 2-80sccm, and the error is less than 5%.

[0049] In practical applications, in order to improve the accuracy of measurement and flow control, the relationship between the pressure difference between the first pressure detection element and the second pressure detection element and the actual flow rate can be calibrated. Usually, there is a certain nonlinear relationship between the flow rate and the pressure difference, so it is necessary to calibrate through experimental data and introduce a suitable flow calculation model.

[0050] In general engineering systems, the relationship between the pressure difference and flow rate generated when the fluid passes through the pipeline can be described by the following pressure difference flow equation:

[0051] in, Indicates the flow value, represents the flow coefficient, Indicates the pressure difference between the first pressure sensing element and the second pressure sensing element.

[0052] The above equation is usually applicable to the stable, incompressible flow of liquids, gases, etc. in pipelines. The essence of this equation is to derive the flow rate of the fluid by measuring the pressure difference and flow rate generated by the fluid in the pipeline, thereby providing the basic data required for pipeline design and flow monitoring. In practical applications, the above equation has been proven to be highly feasible with an error range of less than 3%.

[0053] In practical applications, since different pressure detection components have certain manufacturing tolerances and measurement errors, the measurement results of different pressure detection components may deviate. Therefore, the pressure detection components can be calibrated before use. In order to correct the errors that may be caused by calibration and ensure the accuracy of flow calculation, some embodiments of this application introduce a linear correction coefficient. , the aforementioned pressure difference flow equation is corrected to obtain the flow correction formula:

[0054] The use of flow correction formula fitting can eliminate the phenomenon that there is an error between the numerical values ​​of different pressure detection components and the actual pressure.

[0055] like Figure 4 The figure is a schematic diagram of the calibration system of the electric propulsion flow control system of the present application. In order to further improve the accuracy of flow control, in some embodiments of the present application, flow calibration and temperature calibration can also be performed. Figure 4 The calibration system shown (except the temperature control box), the pressure reducing valve, the first pressure detection component, the second pressure detection component, the first solenoid valve and the second solenoid valve in the calibration system are all consistent with the electric propulsion flow control system. A flow meter is added at the end of the calibration system to measure the real-time flow value on the rear side of the second solenoid valve, and the data detected by the flow meter and the pressure data detected by the first pressure detection component and the second pressure detection component are returned to the host computer for specific data analysis and fitting.

[0056] As an example, set the initial pressure of the gas cylinder as the gas source to 12 MPa to ensure that the system operates under standard working conditions. Then connect the output gas path on the rear side of the second solenoid valve to the flow meter and connect it to the vacuum tank through a flange. Specific calibration methods may include: (1) Fixing the parameters of the first solenoid valve: operating the first solenoid valve at a fixed switching frequency and recording the pressure detection component data in the system stable state.

[0057] (2) Adjusting the parameters of the second solenoid valve: gradually adjusting the opening or switching frequency of the second solenoid valve so that the flow rate displayed by the flow meter reaches multiple preset flow rates ranging from 2 sccm to 80 sccm.

[0058] (3) Record the pressure data of the first pressure detection device and the second pressure detection device: At each preset flow value, synchronously record the stable readings of the first pressure detection device and the second pressure detection device, and calculate the pressure difference between the first pressure detection device and the second pressure detection device. . Ensure the accuracy and repeatability of data collection to reduce measurement errors.

[0059] (4) Calculate the flow coefficient and linear correction coefficient: Use the collected experimental data to fit the data according to the flow correction formula to determine the flow coefficient. and linear correction factor Specifically, the data with the best fit can be obtained by performing the least squares fitting on the data of each preset flow value. and The above fitting process ensures that the measurement differences between different pressure detection components are effectively corrected, thereby improving the accuracy of flow measurement.

[0060] (5) Verify the fitting results: obtained by calculation and , recalculate the flow rate at each experimental point and compare it with the real-time flow rate value displayed by the flow meter.

[0061] The parameters of the second solenoid valve are randomly set, and the values ​​of the first pressure detection component and the second pressure detection component are substituted into the fitted flow correction formula. If the deviation between the calculated flow and the real-time flow value is less than a predetermined error range (such as 5%), the calibration result is considered valid.

[0062] like Figure 4 As shown, the above calibration method is further carried out in a constant temperature box based on a stable temperature environment. In space platforms such as satellites, temperature changes in the external environment will directly affect the working state of the system. Satellites may experience different temperature conditions in different orbital positions and operating stages, which may cause temperature fluctuations in the entire satellite platform or flow control system. In practical applications, the temperature correction coefficient can be taken into consideration, that is, fitting can be performed according to the following temperature correction formula:

[0063] in, and They are all functions related to temperature. By considering the impact of different temperatures on flow, the robustness of the entire system can be enhanced. The specific calibration method for temperature can be: (1) System integration and initial setup: Ensure that the entire calibration system is integrated, including the pressure reducing valve, the first pressure detection component, the second pressure detection component, the first solenoid valve, the second solenoid valve, and the flow meter behind the second solenoid valve. Connect the flow meter data and the pressure data of the two pressure detection components to the host computer for data analysis and fitting.

[0064] As an example, set the initial pressure of the gas cylinder as the gas source to 12 MPa to ensure that the system operates under standard working conditions. Connect the output gas line on the rear side of the second solenoid valve to the flow meter and connect it to the vacuum tank through a flange.

[0065] (2) Fixing the parameters of the first solenoid valve: operating the first solenoid valve at a fixed switching frequency, and recording the pressure detection component data under the system stable state.

[0066] (3) Adjust the system temperature and the parameters of the second solenoid valve: Actively adjust the system temperature so that it varies within the preset temperature range, for example, from -20°C to 80°C. At each temperature point, adjust the parameters of the second solenoid valve to maintain a specific pressure difference (referring to the pressure difference between the test results of the first pressure detection component and the second pressure detection component). Ensure that at each temperature point, the system reaches thermal equilibrium before subsequent measurements.

[0067] (4) Record and fit data: Under each specific pressure difference and temperature condition, record the flow data corresponding to the flow meter.

[0068] Then change the pressure difference and repeat the above steps to obtain a series of temperatures and corresponding flow data under different pressure differences. Use the collected data to fit and analyze the temperature correction formula to determine and Use appropriate mathematical methods, such as polynomial fitting and linear regression, to describe and The law of change with temperature.

[0069] (5) Verify the fitting results: and , randomly select different parameters and temperature conditions of the second solenoid valve. Substitute the test results of the first pressure detection component and the second pressure detection component, as well as the actual temperature, into the fitted temperature correction formula to calculate the flow rate. Compare the calculated flow rate with the real-time flow value displayed by the flowmeter. If the deviation between the two is less than the predetermined error range (such as 5%), the calibration result can be considered valid.

[0070] In some embodiments of the present application, the above calibration results and PID (Proportional-Integral-Derivative) control can be combined to perform closed-loop flow control to achieve more accurate control results. Specifically, the following methods can be used: (1) Flow calibration and initial setting.

[0071] The first solenoid valve is fixed with the same parameters as those used during calibration. Then the parameters of the second solenoid valve are calibrated, and a one-to-one correspondence table between the control parameters of the second solenoid valve (including switching frequency, each opening and closing time, etc.) and the flow rate at the rear of the second solenoid valve is established on the ground. Calibration ensures that the system can quickly approach the target flow rate.

[0072] (2) PID control adjustment.

[0073] According to the required flow value at the rear side of the second solenoid valve, the control parameters of the second solenoid valve in the corresponding relationship table are queried, and the parameters of the second solenoid valve are set, that is, the parameters of the second solenoid valve are adjusted to the calibration values.

[0074] like Figure 5 As shown, it is a schematic diagram of an actual use of the electric propulsion flow control method of the present application. A schematic diagram of an actual use. Taking the application in the satellite platform as an example, the satellite computer, the power processing unit (Power Processing Control Unit, PPCU) and the flow control module are bidirectionally connected in sequence, and the satellite computer issues a flow control instruction, which is sent to the flow control module via the power processing unit. Conversely, the real-time pressure detection results of the first pressure detection component and the second pressure detection component received by the flow control module, as well as the degree of decompression of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve can also be fed back to the satellite computer via the power processing unit. Figure 5 In the figure, the electromagnetic valves in the second branch are recorded as the third electromagnetic valve and the fourth electromagnetic valve. The two branches are used as thruster anode and thruster cathode respectively, and the thruster anode and thruster cathode are then sent to the space environment.

[0075] like Figure 6 As shown, it is a schematic diagram of the PID control algorithm of the electric propulsion flow control system of the present application. Figure 6 In the process, the required set flow value is determined before flow control is performed, and the real-time output flow is collected at the rear side of the second solenoid valve simultaneously, wherein the output flow is combined with the detection data of the first pressure detection component and the second pressure detection component ( Figure 6 The pressure gauge data in the calculation and fitting are then converted to digital form ( Figure 6The A / D conversion in the flowmeter is converted into a digital signal and then input into the FPGA (Field Programmable Gate Array) control unit. The difference between the flow rate and the set flow value is calculated to obtain the corresponding deviation. If the deviation exceeds the threshold value, it is corrected by the PID algorithm and the digital signal is output after correction. Figure 6 The D / A conversion in the circuit is converted into an analog signal or a PWM (Pulse Width Modulation) signal, thereby adjusting the parameters of the second solenoid valve.

[0076] In practical applications, if the second solenoid valve is a bang-bang valve, the output of the PID algorithm is the switching frequency of the second solenoid valve. If the second solenoid valve is a proportional valve, the output of the PID algorithm is the input current value of the second solenoid valve. By continuously adjusting the deviation between the output flow and the set flow value, it is ensured that the output flow is always stable near the set flow value to meet the control requirements.

[0077] The use of PID algorithm can effectively compensate for the hysteresis effect and poor repeatability of the second solenoid valve, reducing the difficulty of parameter control.

[0078] (3) Real-time monitoring and dynamic adjustment.

[0079] After the output flow is basically stable, the system will regularly collect real-time pressure data through the first pressure detection device and the second pressure detection device, calculate the real-time output flow, and compare it with the set flow value. If deviation occurs, the parameters will be adjusted in time to ensure the accuracy and stability of the flow under long-term operation of the system.

[0080] The electric propulsion flow control system of the present application only involves a pressure reducing valve, two pressure detection components and two solenoid valves, which achieves lightweight and conforms to the development trend of the current electric propulsion flow control system. In addition, in terms of control methods, the present application does not require thermal control in the traditional fixed throttling method, and uses a variable structure throttling based entirely on solenoid valves. Compared with the current control method, the entire electric propulsion flow control system has a very wide flow adjustment range (2-80sccm) and a high control accuracy (less than 5%) while being lightweight. In practical applications, only the satellite platform needs to maintain a basically constant temperature in the entire environment, and even if it is not constant temperature, it can be calibrated for temperature, which greatly simplifies the complexity of the entire system. In the context that most current flow control systems require the ground to evaluate the flow size through telemetry data and continuously correct parameters, the present application adopts closed-loop control to greatly simplify the complexity of flow control and improve the accuracy of control. With the long-term use of solenoid valves and pressure reducing valves, the performance will be affected, resulting in the flow not meeting expectations. At the same time, there are problems such as long-term use leading to unstable flow or the flow error gradually increasing over time, which can be self-corrected by the closed-loop control method in the present application.

[0081] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electric propulsion flow control method, characterized in that: include: Depressurizing high-pressure stored propellant; The decompressed propellant is transported along at least two branches, wherein the two branches serve as the anode and cathode of the thruster; a first solenoid valve and a second solenoid valve are arranged along the transport direction of each branch, and a first pressure detection member and a second pressure detection member are arranged at the front side and the rear side of the first solenoid valve, respectively; Each branch performs closed-loop control on the electric propulsion flow rate according to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, combined with the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve.

2. The electric propulsion flow control method according to claim 1, characterized in that: The method for closed-loop control of electric propulsion flow rate by combining the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve comprises: Fixing the parameters of the first solenoid valve; According to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, a pressure conversion algorithm is used to obtain real-time flow data; According to the difference between the real-time flow data and the flow setting value, the parameters of the second solenoid valve are adjusted to perform closed-loop control.

3. The electric propulsion flow control method according to claim 1, characterized in that: The method for closed-loop control of electric propulsion flow rate by combining the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve comprises: According to the real-time pressure detection results of the first pressure detection component and the second pressure detection component, the fitting relationship between the pressure difference and the flow rate is determined in combination with the parameters of the first solenoid valve to obtain the corresponding flow rate index; According to the flow index, the parameters of the second solenoid valve are adjusted so that the pressure is at the pressure setting value, and closed-loop control is performed.

4. The electric propulsion flow control method according to claim 3, characterized in that: The method also includes changing the accuracy and adjustable range of flow regulation by adjusting the parameters of the first solenoid valve.

5. The electric propulsion flow control method according to claim 3, characterized in that: It also includes adjusting the degree of decompression of the propellant.

6. The electric propulsion flow control method according to any one of claims 1 to 5, characterized in that: The method for performing closed-loop control comprises: Fix the parameters of the first solenoid valve, and establish a corresponding relationship table between the parameters of the second solenoid valve and the flow rate at the rear side of the second solenoid valve; According to the flow value required at the rear side of the second solenoid valve, the corresponding parameters of the second solenoid valve are queried in the flow correspondence table, and the parameters of the second solenoid valve are set; Comparing the real-time flow value at the rear side of the second solenoid valve with the required flow value at the rear side of the second solenoid valve to obtain a real-time deviation; The parameter adjustment amount of the second solenoid valve is obtained through the PID algorithm according to the real-time deviation, and the parameters of the second solenoid valve are adjusted.

7. The electric propulsion flow control method according to claim 1, characterized in that: Also includes flow calibration: The opening degree or the switching frequency of the first solenoid valve is fixed, and the opening degree or the switching frequency of the second solenoid valve is gradually adjusted so that the flow rate at the rear side of the second solenoid valve reaches a plurality of preset flow rate values, and at each preset flow rate value, the detection results of the first pressure detection component and the second pressure detection component are synchronously recorded to obtain the corresponding pressure difference between the first pressure detection component and the second pressure detection component; According to multiple sets of preset flow values ​​and the corresponding pressure difference between the first pressure detection component and the second pressure detection component, the following flow correction formula is calculated: and : in, is the flow value, is the flow coefficient, is the pressure difference between the first pressure detection member and the second pressure detection member, is the linear correction coefficient; According to the detection results of the first pressure detection component and the second pressure detection component, the corresponding flow value is calculated by the flow correction formula and compared with the real-time flow value on the rear side of the second solenoid valve. If the error requirements are met, the flow calibration is completed.

8. The electric propulsion flow control method according to claim 1, characterized in that: Also includes temperature calibration: The switching frequency of the first solenoid valve is fixed, the temperature is gradually adjusted to a plurality of preset temperature values, and the parameters of the second solenoid valve are adjusted at each preset temperature value so that the pressure difference between the first pressure detection element and the second pressure detection element remains unchanged; At each pressure difference and preset temperature value, record the corresponding flow rate at the rear side of the second solenoid valve; According to each pressure difference and preset temperature value, and the corresponding flow rate behind the second solenoid valve, calculate the following temperature correction formula: and : in, is a function of temperature, is the temperature correction function; Different parameters and temperatures of the second solenoid valve are randomly selected, the corresponding flow value is calculated by the temperature correction formula, and compared with the real-time flow value on the rear side of the second solenoid valve. If the error requirements are met, the temperature calibration is completed.

9. An electric propulsion flow control system, used to implement an electric propulsion flow control method according to any one of claims 1 to 8, characterized in that: It includes a flow control module, and a gas source, a pressure reducing valve and at least two branches connected in sequence; The gas source is used to store propellant at high pressure; The pressure reducing valve is used to reduce the pressure of the propellant stored under high pressure; Each branch is provided with a first solenoid valve and a second solenoid valve along the conveying direction, and a first pressure detection member and a second pressure detection member are provided at the front and rear sides of the first solenoid valve, respectively; it is used to convey the decompressed propellant along at least two branches, wherein the two branches serve as the anode and cathode of the thruster; The flow control module is respectively connected to the first pressure detection component, the first solenoid valve, the second pressure detection component and the second solenoid valve, and performs closed-loop control of the electric propulsion flow based on the real-time pressure detection results of the first pressure detection component and the second pressure detection component, combined with the decompression degree of the propellant, the parameters of the first solenoid valve and the parameters of the second solenoid valve.

10. An electric propulsion flow control system according to claim 9, characterized in that: Also includes a stop valve; The stop valve is connected between the gas source and the pressure reducing valve, and is used to control the conduction and cutoff of the electric propulsion flow control system.

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