A control method and control system for a space pump driven two-phase fluid circuit

Abstract

The application discloses a control method and a control system of a space pump-driven two-phase fluid loop, and belongs to the technical field of aerospace thermal control. The control of the loop is cooperatively completed by three layers of control logics, i.e. a supercooling safety monitoring layer, an orbit predictability feedforward layer and a fast-slow separation double-loop control layer. The supercooling safety monitoring layer, the orbit predictability feedforward layer and the fast-slow separation double-loop control layer are sequentially arranged according to the control logic priority from high to low. The fast-slow separation double-loop control layer comprises a flow control sub-loop and a temperature control sub-loop which are in parallel operation and bandwidth decoupling. Through the setting of the double-layer control architecture of fast-slow separation, the response speed and long-term stability are simultaneously ensured, a safety priority arbitration mechanism with supercooling degree as the core is established, the survival ability of the system under extreme working conditions is ensured, the orbit environment disturbance prediction ability is possessed, the temperature control precision is improved, the multivariable global coordinated optimization is realized, and the heat transfer potential of the pump-driven two-phase system is fully developed.

Description

Technical Field

[0001] This invention relates to the field of aerospace thermal control technology, specifically to a control method and control system for a space pump-driven two-phase fluid circuit. Background Technology

[0002] In spacecraft thermal control systems, pump-driven two-phase fluid loops have become the core heat dissipation solution for high-power satellites, space stations, and deep space probes due to their advantages such as high heat exchange efficiency, good isothermal properties, and long transmission distance.

[0003] Currently, the control methods for two-phase fluid loops in space mainly include: single-loop feedback control, which uses a single flow or temperature closed-loop feedback control; constant pressure control scheme, which maintains constant system pressure through a pressure regulating valve; and conventional subcooling protection scheme.

[0004] A comprehensive analysis of the existing technologies reveals the following prominent problems in current control methods for space pump-driven two-phase fluid loops: (1) Fast and slow coupling leads to system performance contradictions Existing control schemes typically combine flow regulation and temperature regulation in the same control loop, or use only a single parameter feedback. If the controller bandwidth is set too high to quickly track heat source fluctuations, overshoot and oscillations can easily be introduced, affecting temperature stability; if the bandwidth is set too low to ensure stability, the response is slow and unable to cope with sudden load changes.

[0005] (2) Lack of a priority arbitration mechanism for safety protection and performance control In existing solutions, normal operation control and abnormal state protection are often at the same logical level, lacking a systematic hierarchical handling strategy.

[0006] (3) Lack of foresight in responding to external environmental disturbances The Low Earth Orbit (LEO) environment is characterized by significant periodic thermal disturbances: an orbital cycle lasts approximately 90 minutes, with about 45 minutes in the high-temperature zone of sunlight and 45 minutes in the extremely cold zone of shadow. Existing feedback-based control schemes are essentially "post-hoc" control—adjustment is only initiated after the sensor detects a temperature deviation, resulting in inherent phase lag. For payloads extremely sensitive to thermal stability, such as high-resolution optical cameras (temperature control accuracy on the order of ±0.1K), this lag effect directly degrades payload performance.

[0007] (4) Lack of global coordination ability for multiple variables In pump-driven two-phase systems, complex coupling relationships exist between multiple variables such as pump speed, reservoir heating power, system pressure, and working fluid phase distribution. Existing decentralized control strategies independently adjust individual variables without establishing an effective multi-variable coordination mechanism, making it difficult to achieve global system optimization. Summary of the Invention

[0008] The purpose of this invention is to provide a control method and control system for a space pump-driven two-phase fluid loop. By setting up a dual-layer control architecture with fast and slow separation, it ensures both response speed and long-term stability. At the same time, it establishes a safety priority arbitration mechanism with subcooling as the core to ensure the survivability of the system under extreme conditions. Moreover, it has the ability to predict orbital environmental disturbances, improves temperature control accuracy, realizes multi-variable global coordination optimization, and fully utilizes the heat transfer potential of the pump-driven two-phase system, thereby solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a control method for a space pump-driven two-phase fluid loop, wherein the loop regulation is completed by three layers of control logic: a supercooled safety monitoring layer, a track predictive feedforward layer, and a fast-slow separation dual-loop control layer. The supercooled safety monitoring layer, the track predictive feedforward layer, and the fast-slow separation dual-loop control layer are set in order of control logic priority from high to low. The fast-slow separation dual-loop control layer includes a flow control sub-loop and a temperature control sub-loop that operate in parallel and are decoupled by bandwidth: The flow control sub-loop is a fast loop, which collects the pump outlet flow and load heat source power signals in real time to calculate the flow deviation, adjusts the mechanical pump speed through the PI control algorithm, and applies a hard limit constraint on the pump speed change rate; the temperature control sub-loop is a slow loop, which collects the evaporator outlet temperature and liquid receiver temperature to calculate the temperature deviation, outputs the liquid receiver heating power command through the PI control algorithm, and changes the loop saturation pressure by heating the liquid receiver to anchor the evaporation temperature. The supercooling safety monitoring layer operates independently and has the highest execution priority. It collects pump inlet pressure and pump inlet temperature in real time to calculate the supercooling margin, and sets a first-level early warning threshold of 3K and a second-level safety recovery threshold of 5K. When the supercooling margin is ≤3K, it forcibly takes over control and simultaneously executes dual protection actions of pump speed derating and liquid receiver heating power increase, and separates the fast and slow freezing outputs into dual loops. When the supercooling margin is ≥5K and remains at that level for more than 60 seconds, it smoothly switches back to dual loop control after a 10~30s ramp transition. The orbital predictive feedforward layer uses orbital ephemeris data to adjust the system's operating status in advance before significant changes occur in the external thermal environment. Specifically, it includes orbital thermal environment prediction and feedforward pre-adjustment execution. Based on orbital ephemeris data, the timing of the transition between sunshine and shadow and external heat flow are predicted. Flow and temperature feedforward compensation biases are generated 3 to 7 minutes before the orbital hot-cold transition. These biases are then superimposed on the dual-loop control output in a trapezoidal slope gradual entry and exit manner to offset the orbital thermal disturbance in advance.

[0010] Preferably, in the PI control algorithm of the flow control sub-loop, the proportional gain K p The value ranges from 5 to 20, and the integration time constant T iThe value should be between 0.1 and 2; the pump speed change rate should be limited to no more than 500 rpm / s; the preferred bandwidth of the flow control sub-loop is 1 Hz, and the response time is in the second range.

[0011] Preferably, the PI controller of the temperature control sub-loop has a bandwidth of 0.02Hz; the evaporation temperature setpoint T set It supports on-orbit reprogramming and indirectly stabilizes the evaporator outlet evaporation temperature by adjusting the heating power of the liquid receiver to change the saturated temperature-pressure relationship of the loop.

[0012] Preferably, the dual protection action of the overcooling safety monitoring layer includes: Action 1: Force the mechanical pump speed to the minimum safe speed N. min N min Given the idle speed N idle With rated speed N rated between; Action 2: Increase the heating power of the liquid reservoir to the maximum allowable power P. max 80%~100%, preferably 90%; The optimal smooth transition time after protection is lifted is 20 seconds.

[0013] Preferably, the pre-adjustment lead time of the track predictive feedforward layer is 5 minutes; the feedforward slope application time t ramp The value should be between 60 and 180 seconds, with 120 seconds being preferred. When it is predicted that the system is about to enter the extremely cold shadow zone, the flow circuit is superimposed with a negative bias of -5% to -15% of the rated speed, and the temperature circuit is superimposed with a positive bias of +10% to +30% of the rated heating power. When the forecast indicates that the system is about to leave the shadow and enter the high-temperature zone under sunlight, the flow circuit is superimposed with a positive bias of +5% to +15% of the rated speed, and the temperature circuit is superimposed with a negative bias of -10% to -30% of the rated heating power; the flow feedforward bias is preferably ±10%, and the temperature feedforward bias is preferably ±20%.

[0014] Preferably, the execution priority arbitration rule for the three-layer control logic of the supercooled safety monitoring layer, the track predictive feedforward layer, and the fast / slow separation dual-loop control layer is as follows: Level 0, highest priority: Overcooling safety monitoring layer. When the overcooling margin is ≤3K, it will be forcibly covered and the control output of the other two layers will be interrupted. Level 1 (Second Highest Priority): Orbit Predictive Feedforward Layer, activated periodically based on orbital ephemeris, only modifies the control reference value of the fast and slow separation dual loops; Level 2 Normal Priority: Fast and slow separation dual-loop control layer, the system continues to execute basic closed-loop control when there is no safety warning.

[0015] Preferably, the subcooling margin calculation step specifically includes: Real-time reading of pump inlet pressure P pump_inlet and pump inlet temperature T pump_inlet ; The saturation temperature Ts corresponding to the current pressure can be obtained by looking up the working fluid properties in a table or by real-time calculation. at (P pump_inlet ); Calculate the current subcooling margin: .

[0016] Preferably, the orbital thermal environment prediction includes the following steps: A1. Obtain the current orbital elements and ephemeris data, including: semi-major axis a, eccentricity e, orbital inclination i, right ascension of ascending node Ω, argument of perigee ω, and mean perigee M; A2. Based on the orbital dynamics model, predict the entry and exit times of the sunshine and shadow areas within the next orbital cycle; A3. Calculate the predicted external heat flow for future periods, including: solar direct heat flow q. sun Earth's infrared heat flow q IR Earth's albedo heat flow q albedo ; A4. Generate the feedforward compensation prediction curve.

[0017] Based on a control method for a space pump-driven two-phase fluid loop, the system for implementing the method is also included, comprising a sensor acquisition module, a controller module, an actuator module, and a human-machine interface module. The sensor acquisition module inputs measurement data to the controller module in one direction, and the controller module receives data from the sensor acquisition module and the human-machine interface module and sends control commands to the actuator module. The sensing and acquisition module includes a mechanical pump outlet flow sensor, a load heat source power sensor, an evaporator outlet temperature sensor, a liquid receiver temperature sensor, a pump inlet pressure sensor, and a pump inlet temperature sensor. The controller module integrates a flow PI controller, a temperature PI controller, an overcooling safety monitoring unit, a track prediction and feedforward generation unit, and an arbitration logic unit; The actuator module includes a motor-driven mechanical pump and an electric heater for a liquid reservoir. The human-machine interface module is used to configure the evaporation temperature setpoint T. set It can display the system's operating status in real time and receive on-orbit reprogramming commands.

[0018] Preferably, the controller module adopts an FPGA + microprocessor heterogeneous computing architecture; the FPGA is responsible for high-frequency data acquisition of 1~10ms and fast-loop control of flow rate; the microprocessor performs slow-loop temperature regulation, supercooled safety status monitoring, orbit ephemeris prediction and feedforward compensation calculation with a sampling period of 100ms~1s.

[0019] Compared with the prior art, the beneficial effects of the present invention are: (1) It fundamentally solves the contradiction between fast and slow coupling and achieves a balance between response speed and long-term stability: Through the dual-loop architecture design with fast and slow separation, the flow control sub-loop achieves second-level load tracking with a high bandwidth of about 1Hz, while the temperature control sub-loop ensures long-term temperature stability with a low bandwidth of about 0.02Hz. The bandwidth ratio of the two is 50:1, avoiding the fundamental contradiction of "fast is unstable, stable is not fast" in traditional single-loop design. This hierarchical decoupling design can increase the phase margin of the system from 30°~40° in typical single-loop design to more than 50°, significantly improving closed-loop stability.

[0020] (2) A high-priority safety arbitration mechanism based on supercooling was established to effectively prevent cavitation-induced destructive failures: the supercooling safety monitor was independently set as the Level 0 highest priority control layer, with a 3K supercooling margin as the early warning threshold and 5K as the recovery threshold. Combined with dual joint protection actions, a complete safety closed loop of "prevention-intervention-recovery" was constructed. This design concept is in line with the core principle of "fail-oriented safety" in the aerospace field.

[0021] (3) Temperature control accuracy is improved to ±0.1K level through orbital predictive feedforward: The orbital ephemeris data is directly introduced into the control loop, and pre-adjustment is started 5 minutes before the switching between sunlight and shadow, realizing a paradigm leap from "feedback correction" to "feedforward prediction". For the approximately 90-minute cycle of hot and cold alternation in the LEO orbit, feedforward compensation can effectively eliminate the equivalent error of feedback lag. The use of the feedforward strategy can significantly reduce the fluctuation range of evaporation temperature, meeting the stringent requirements of precision payloads such as high-resolution optical cameras for ±0.1K level temperature control accuracy.

[0022] (4) Multivariable global coordination optimization was achieved. This invention incorporates key variables such as pump speed, reservoir heating power, and system pressure into a unified control framework through three-layer logic priority arbitration and multi-variable feedforward coordination. Compared to existing distributed control strategies, global coordination can reduce system overshoot by approximately 40% to 60% and shorten settling time by approximately 30% to 50% during varying operating conditions, significantly improving the system's transient response quality.

[0023] (5) Possesses on-orbit adaptive and reprogrammable capabilities The temperature control sub-loop of this invention uses the liquid reservoir as a thermodynamic "anchor point." By adjusting the heating power of the liquid reservoir, the system pressure and operating temperature can be changed. This means that the thermal control setpoint T_set has on-orbit reprogramming capability. When mission requirements change, there is no need to modify the hardware configuration; only the new temperature setpoint needs to be uploaded for adaptation. This greatly enhances the system's on-orbit flexibility and its reusability throughout its lifecycle. Attached Figure Description

[0024] Figure 1 This is a system block diagram of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a control method for a space pump-driven two-phase fluid loop, comprising the following three layers of control logic working in concert: First layer: Fast / slow separation dual-loop control layer The dual-loop control layer includes a flow control sub-loop and a temperature control sub-loop, with the two sub-loops operating in parallel and having separate bandwidths. S1: Flow control sub-loop (fast loop) The task of the flow control sub-loop is to adjust the mechanical pump speed in real time according to changes in load power, ensuring that the evaporator always receives sufficient working fluid replenishment. Specifically, it includes the following steps:

[0027] S1.1: Collect the pump outlet flow sensor signal and the load heat source power sensor signal, and calculate the flow deviation; S1.2: PI control algorithm is used for closed-loop flow regulation, with proportional gain K. p The typical value range for is 5~20, and the integration time constant T i The typical value range is 0.1 to 2; S1.3: Convert the PI controller output into mechanical pump control commands to adjust the mechanical pump operating parameters; S1.4: Apply a hard limit constraint to the rate of change of pump speed, for example, not exceeding 500 rpm / s; The control bandwidth of the flow control sub-loop is set to 0.5~2Hz, preferably 1Hz, and the response time reaches the second level.

[0028] S2: Temperature control sub-loop (slow loop) The task of the temperature control sub-loop is to anchor the evaporation temperature of the working fluid, enabling the system to maintain the evaporation temperature within a preset window. Specifically, it includes the following steps:

[0029] S2.1: Collect evaporator outlet temperature T evap and the temperature T inside the reservoir acc ; S2.2: Calculate temperature deviation T set It has a temperature setpoint and the ability to be reprogrammed in orbit. S2.3: The PI control algorithm is used to generate the liquid reservoir heating power command P. heat The controller bandwidth is set to 0.01~0.05Hz, preferably 0.02Hz; S2.4: By adjusting the power of the heater inside the liquid receiver to change the working fluid temperature, the system pressure of the entire loop is indirectly controlled by utilizing the saturated temperature-pressure relationship, thereby achieving the anchoring of the evaporation temperature.

[0030] The bandwidth ratio of the flow control sub-loop and the temperature control sub-loop is set to 25:1 to 100:1, preferably 50:1, to form a clear hierarchical relationship between speed and temperature.

[0031] Second layer: Overcooling safety monitor (highest priority arbitration layer) The overcooling safety monitor operates independently of the aforementioned dual-loop control layer and has the highest execution priority. When a safety condition is triggered, it can forcibly override the normal output of the flow loop and temperature loop. Specifically, it includes the following steps:

[0032] S3: Real-time monitoring of subcooling conditions S3.1: Real-time acquisition of pump inlet pressure P pump_inlet and pump inlet temperature T pump_inlet ; S3.2: Obtain the saturation temperature T corresponding to the current pressure by looking up the table or calculating in real time based on the working fluid properties. sat (P pump_inlet ); S3.3: Calculate the current subcooling margin: ; S4: Safety Status Assessment and Arbitration S4.1: Set the first-level warning threshold ΔT sc_warn =3K; when ΔT sc When the temperature is ≤3K, the system is determined to be in a state of insufficient supercooling margin; S4.2: Set the secondary safety threshold ΔT sc_safe =5K; when ΔT sc When the value is ≥5K, the system is determined to have recovered to a safe state; S4.3: When a Level 1 warning is triggered, the overcooling safety monitor immediately takes over control and simultaneously executes the following dual protection actions: Action 1, Pump speed derating protection: Forces the mechanical pump speed to the minimum safe speed N. min N min Determine using the following formula: , Where N idle The idle speed is N. rated This is the rated speed. This action aims to reduce the local pressure drop at the pump inlet and alleviate the tendency for flashing induced by low pressure;

[0033] Action 2: Rapid increase in reservoir heating: The reservoir heating power is rapidly increased to the maximum allowable power P. max The concentration is 80%~100%, preferably 90%; by increasing the temperature of the working fluid in the reservoir, the system pressure of the entire circuit is increased through the saturated temperature-pressure relationship; S4.4: During the overcooling protection activation period, the normal outputs of the flow control sub-loop and the temperature control sub-loop are frozen or bypassed, and the system is completely dominated by the overcooling safety monitor. S4.5: When the subcooling margin ΔT sc Restored to ≥5K and maintained for time t hold After ≥60 seconds, the system deactivates the protection mode and smoothly switches back to the normal dual-loop control mode. The switching process uses a ramp transition method, with a transition time set to 10~30 seconds, preferably 20 seconds.

[0034] Third layer: Orbit prediction feedforward layer The orbital predictive feedforward layer utilizes orbital ephemeris data to adjust the system's operating state in advance before significant changes occur in the external thermal environment. Specifically, it includes the following steps:

[0035] S5: Prediction of Orbital Thermal Environment S5.1: Obtain the current orbital elements and ephemeris data, including: semi-major axis a, eccentricity e, orbital inclination i, right ascension of ascending node Ω, argument of perigee ω, and mean perigee M; S5.2: Based on the orbital dynamics model, predict the entry / exit times of the sunshine zone and shadow zone within the next orbital cycle; S5.3: Calculate the predicted external heat flow for future periods, including: direct solar heat flow q sun Earth's infrared heat flow q IR Earth's albedo heat flow q albedo ; S5.4: Generate the feedforward compensation prediction curve.

[0036] S6: Feedforward pre-tuning execution S6.1: Set the pre-adjustment lead time Δt_pre, with a value range of 3 to 7 minutes, preferably 5 minutes; that is, the pre-adjustment action is executed 5 minutes before actually entering / leaving the shadow area; S6.2: When predicting an imminent entry into the extremely cold, shadowed zone: Flow loop feedforward component: A negative bias ΔN is superimposed on the original PI output. ff ΔN ff The range is -5% to -15% of the rated speed, preferably -10%, and the pump speed is gradually reduced to avoid excessive cooling. Temperature loop feedforward component: A positive bias ΔP is added to the original heating power. ff ΔP ff The range is +10% to +30% of the rated heating power, preferably +20%, to preheat the circuit in advance to offset the upcoming heat sink cooling impact; S6.3: When it is predicted that the area will soon leave the shaded zone and enter the high-temperature zone under sunlight: Flow loop feedforward component: superimposed positive bias ΔN ff ΔN ff The range is +5% to +15% of the rated speed, and the pump speed is gradually increased in advance to enhance the heat carrying capacity of the working fluid circulation. Temperature loop feedforward component: superimposed negative bias ΔP ff ΔP ff The range is -10% to -30% of the rated heating power, reducing heating to avoid overheating; S6.4: The feedforward component is applied using a trapezoidal slope with gradual entry and exit to avoid step impact. Slope time t ramp The value range is 60 to 180 seconds, with 120 seconds being preferred.

[0037] The three-layer control logic—supercooled safety monitoring layer, track predictive feedforward layer, and fast / slow separation dual-loop control layer—is shown in the table below: Highest(Level0) Overcooling safety monitor Subcooling margin ≤ 3K Forced overwrite can interrupt the other two layers. Second highest (Level 1) Orbit Predictive Feedforward Orbital ephemeris drive, periodic activation Modify the reference value of the flow / temperature loop. Normal (Level 2) Fast and slow separation dual circuit Continuous operation Basic closed-loop control Based on a control method for a space pump-driven two-phase fluid loop, a control system for the space pump-driven two-phase fluid loop is also provided to implement the above control method, comprising: The sensor acquisition module includes: a mechanical pump outlet flow sensor, a load heat source power sensor, an evaporator outlet temperature sensor, a liquid receiver temperature sensor, a pump inlet pressure sensor, and a pump inlet temperature sensor. The controller module is configured to execute the above S1~S6 steps, including: a flow PI controller, a temperature PI controller, a supercooled safety monitoring unit, a track prediction and feedforward generation unit, and an arbitration logic unit; The actuator module includes: a motor-driven mechanical pump and an electric heater for the liquid receiver; The human-machine interface module is used to set the temperature setpoint T. set Check the system's operating status and receive on-orbit reprogramming instructions.

[0038] The controller module adopts a heterogeneous computing architecture of FPGA + microprocessor. The FPGA is responsible for high-frequency data acquisition and high-speed closed-loop control of the flow loop (sampling period 1~10ms), while the microprocessor is responsible for medium and low speed tasks such as temperature loop control, supercooling safety monitoring, and track prediction (sampling period 100ms~1s).

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A control method for a space pump-driven two-phase fluid circuit, characterized in that, The loop regulation is completed by the coordinated control logic of three layers: the supercooled safety monitoring layer, the track predictive feedforward layer, and the fast-slow separation dual-loop control layer. The supercooled safety monitoring layer, the track predictive feedforward layer, and the fast-slow separation dual-loop control layer are set in order of control logic priority from high to low. The fast-slow separation dual-loop control layer includes a flow control sub-loop and a temperature control sub-loop that operate in parallel and are decoupled by bandwidth: The flow control sub-loop is a fast loop, which collects the pump outlet flow and load heat source power signals in real time to calculate the flow deviation, adjusts the mechanical pump speed through the PI control algorithm, and applies a hard limit constraint on the pump speed change rate; the temperature control sub-loop is a slow loop, which collects the evaporator outlet temperature and liquid receiver temperature to calculate the temperature deviation, outputs the liquid receiver heating power command through the PI control algorithm, and changes the loop saturation pressure by heating the liquid receiver to anchor the evaporation temperature. The supercooling safety monitoring layer operates independently and has the highest execution priority. It collects pump inlet pressure and pump inlet temperature in real time to calculate the supercooling margin, and sets a first-level early warning threshold of 3K and a second-level safety recovery threshold of 5K. When the supercooling margin is ≤3K, it forcibly takes over control and simultaneously executes dual protection actions of pump speed derating and liquid receiver heating power increase, and separates the fast and slow freezing outputs into dual loops. When the supercooling margin is ≥5K and remains at that level for more than 60 seconds, it smoothly switches back to dual loop control after a 10~30s ramp transition. The orbital predictive feedforward layer uses orbital ephemeris data to adjust the system's operating status in advance before significant changes occur in the external thermal environment. Specifically, it includes orbital thermal environment prediction and feedforward pre-adjustment execution. Based on orbital ephemeris data, the timing of the transition between sunshine and shadow and external heat flow are predicted. Flow and temperature feedforward compensation biases are generated 3 to 7 minutes before the orbital hot-cold transition. These biases are then superimposed on the dual-loop control output in a trapezoidal slope gradual entry and exit manner to offset the orbital thermal disturbance in advance.

2. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: In the PI control algorithm of the flow control sub-loop, the proportional gain K p The value ranges from 5 to 20, and the integration time constant T i The value should be between 0.1 and 2; the pump speed change rate should be limited to no more than 500 rpm / s; the preferred bandwidth of the flow control sub-loop is 1 Hz, and the response time is in the second range.

3. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: The preferred bandwidth of the PI controller in the temperature control sub-loop is 0.02Hz; the evaporation temperature setpoint T set It supports on-orbit reprogramming and indirectly stabilizes the evaporator outlet evaporation temperature by adjusting the heating power of the liquid receiver to change the saturated temperature-pressure relationship of the loop.

4. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: The dual protection mechanisms of the overcooling safety monitoring layer include: Action 1: Force the mechanical pump speed to the minimum safe speed N. min N min Given the idle speed N jdle With rated speed N rated between; Action 2: Increase the heating power of the liquid reservoir to the maximum allowable power P. max 80%~100%, preferably 90%; The optimal smooth transition time after protection is lifted is 20 seconds.

5. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: The preferred lead time for the track predictive feedforward layer is 5 minutes; the feedforward slope application time t ramp The value should be between 60 and 180 seconds, with 120 seconds being preferred. When it is predicted that the system is about to enter the extremely cold shadow zone, the flow circuit is superimposed with a negative bias of -5% to -15% of the rated speed, and the temperature circuit is superimposed with a positive bias of +10% to +30% of the rated heating power. When the forecast indicates that the system is about to leave the shadow and enter the high-temperature zone under sunlight, the flow circuit is superimposed with a positive bias of +5% to +15% of the rated speed, and the temperature circuit is superimposed with a negative bias of -10% to -30% of the rated heating power; the flow feedforward bias is preferably ±10%, and the temperature feedforward bias is preferably ±20%.

6. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: The execution priority arbitration rule for the three-layer control logic—the supercooled safety monitoring layer, the track predictive feedforward layer, and the fast / slow separation dual-loop control layer—is as follows: Level 0, highest priority: Overcooling safety monitoring layer. When the overcooling margin is ≤3K, it will be forcibly covered and the control output of the other two layers will be interrupted. Level 1 (Second Highest Priority): Orbit Predictive Feedforward Layer, activated periodically based on orbital ephemeris, only modifies the control reference value of the fast and slow separation dual loops; Level 2 Normal Priority: Fast and slow separation dual-loop control layer, the system continues to execute basic closed-loop control when there is no safety warning.

7. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: The specific steps for calculating the subcooling margin are as follows: Real-time reading of pump inlet pressure P pump_inlet and pump inlet temperature T pump_inlet ; The saturation temperature Ts corresponding to the current pressure can be obtained by looking up the working fluid properties in a table or by real-time calculation. at (P pump_inlet ); Calculate the current subcooling margin.

8. The control method for a space pump-driven two-phase fluid circuit according to claim 1, characterized in that: The orbital thermal environment prediction includes the following steps: A1. Obtain the current orbital elements and ephemeris data, including: semi-major axis a, eccentricity e, orbital inclination i, right ascension of ascending node Ω, argument of perigee ω, and mean perigee M; A2. Based on the orbital dynamics model, predict the entry and exit times of the sunshine and shadow areas within the next orbital cycle; A3. Calculate the predicted external heat flow for future periods, including: solar direct heat flow q. sun Earth's infrared heat flow q IR Earth's albedo heat flow q albedo ; A4. Generate the feedforward compensation prediction curve.

9. A control system for a space pump-driven two-phase fluid circuit, used to implement the control method for a space pump-driven two-phase fluid circuit according to any one of claims 1-8, characterized in that, It includes a sensor acquisition module, a controller module, an actuator module, and a human-machine interface module; The sensor acquisition module inputs measurement data to the controller module in one direction, and the controller module receives data from the sensor acquisition module and the human-machine interface module and sends control commands to the actuator module. The sensing and acquisition module includes a mechanical pump outlet flow sensor, a load heat source power sensor, an evaporator outlet temperature sensor, a liquid receiver temperature sensor, a pump inlet pressure sensor, and a pump inlet temperature sensor. The controller module integrates a flow PI controller, a temperature PI controller, an overcooling safety monitoring unit, a track prediction and feedforward generation unit, and an arbitration logic unit; The actuator module includes a motor-driven mechanical pump and an electric heater for a liquid reservoir. The human-machine interface module is used to configure the evaporation temperature setpoint T. set It can display the system's operating status in real time and receive on-orbit reprogramming commands.

10. The control system for a space pump-driven two-phase fluid circuit according to claim 9, characterized in that: The controller module adopts a heterogeneous computing architecture of FPGA and microprocessor; the FPGA is responsible for high-frequency data acquisition of 1~10ms and fast loop control of flow rate; the microprocessor performs slow loop temperature regulation, supercooled safety status monitoring, orbit ephemeris prediction and feedforward compensation calculation with a sampling period of 100ms~1s.

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