CN111498146A - Thermal control system and method for detecting and verifying satellite by near-earth orbit gravitational wave - Google Patents

Abstract

The invention provides a thermal control system and a method for a near-earth orbit gravitational wave detection verification satellite.A primary thermal control module comprises a plurality of cabin plates, and a load is surrounded at the center and sealed to form a load cabin; arranging insulating gaskets and/or multi-layer insulating assemblies inside and/or outside the load compartment to insulate the load from other heat sources; the secondary thermal control module comprises an automatic temperature control unit, detects the temperature of the load cabin, sends the temperature of the load cabin to the thermal control main processor, and controls the automatic temperature control unit to adjust the temperature according to the temperature of the load cabin by adopting a PID algorithm so as to form a constant temperature cage type heating area when the load cabin works; the three-level thermal control module comprises a compensation module fixed on the load, a heat insulation assembly wrapping the load and the compensation module, and a temperature measurement unit, wherein the temperature measurement unit detects the temperature of the load and sends the temperature of the load to the thermal control main processor, and the temperature of the compensation module is controlled to be adjusted by adopting a PID algorithm according to the temperature of the load, so that the temperature of the load is kept uniform at all positions during working.

Description

Thermal control system and method for low-Earth orbit gravitational wave detection and verification satellite

technical field

The invention relates to the technical field of aerospace, in particular to a thermal control system and method for a low-earth orbit gravitational wave detection and verification satellite.

Background technique

The invention is applied to a gravitational wave detection satellite in a low-earth orbit. The detection and precise measurement of gravitational waves provide a brand-new observation and an important window for understanding the universe, which is different from electromagnetic waves. By accurately testing Einstein's general theory of relativity, it can reveal the nature of gravity and reveal many new mysteries in the structure and evolution of the universe. . my country's gravitational wave detection plan is divided into three steps, and the "Tai Chi Plan" has been formulated. Among them, "Tai Chi No. 1" is the Chinese space gravitational wave plan determined by the Chinese Academy of Sciences Space Science Strategic Pilot Science and Technology Project - Tai Chi's first technology verification star , the project aims to carry out space experimental verification of some key technologies in advance.

The high-precision and high-stability thermal control index of the payload system of "Taiji No. 1" is relatively high, and its payload subsystem is mainly composed of an inter-satellite laser interference ranging system and a drag-free system. The thermally induced deformation has high requirements, so the temperature stability index of the core load is proposed to be T±0.1K/1000s; the non-drag system relies on micro-thrust to control the attitude, and the pressure changes of the pipeline are very strict , and the pressure effect caused by temperature becomes an important constraint, the system proposes the requirement of target temperature T±3K/1000s. Therefore, in the "Tai Chi No. 1" project, the highest stability index is that during the working process of the load for 1000s, the temperature control temperature of the thermal control is at a certain temperature T, and the fluctuation should be better than 0.1K.

Therefore, it is necessary to design a high-precision and high-stability thermal control system for gravitational wave detection satellites.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a thermal control system and method for a low-earth orbit gravitational wave detection and verification satellite, so as to realize a high-precision and high-stability thermal control system required by a gravitational wave detection satellite.

In order to solve the above technical problems, the present invention provides a thermal control system for a low-Earth orbit gravitational wave detection and verification satellite, the gravitational wave detection satellite includes a load and a platform, and the load and the thermal control system are located on the platform. Internal; the thermal control system includes:

A primary thermal control module comprising a plurality of panels configured to enclose and enclose the load in the center, forming a load compartment; thermally insulating gaskets are arranged inside and/or outside the load compartment and/or multi-layer thermal insulation assemblies to isolate said loads from other heat sources;

a secondary thermal control module comprising an automatic temperature control unit configured to detect the temperature of the load compartment and send the temperature of the load compartment to the thermal control master processor; the The thermal control general processor is configured to use the PID algorithm to control the automatic temperature control unit to adjust the temperature according to the temperature of the load compartment, so that the load compartment forms a constant temperature cage heating area when the load is working;

A three-stage thermal control module includes a compensation module fixed on the load, a thermal insulation assembly wrapping the load and the compensation module, and a temperature measurement unit configured to detect the temperature of the load. temperature, and send the temperature of the load to the thermal master processor; and

The thermal control general processor is configured to use the PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, so that the temperature of the load is kept uniform throughout the operation.

Optionally, in the thermal control system for the low-Earth orbit gravitational wave detection and verification satellite, the temperature of the load cabin requires a degree of stability of better than 0.1K/1000 seconds when the load is working, and the on-orbit load is actually obtained. The temperature stability during operation is better than 5mK/1000 seconds.

Optionally, in the thermal control system for a low-Earth orbit gravitational wave detection and verification satellite, the deck material of the load compartment adopts a honeycomb structure plate compounded with an enhanced heat exchange coating.

Optionally, in the thermal control system for the low-Earth orbit gravitational wave detection and verification satellite, the material of the thermal insulation gasket is FRP, the thermal insulation gasket is a square with a side length of 15 mm and a thickness of 15 mm. is a 3mm sheet, and the thermal conductivity of the thermal insulation gasket is 0.40w/(m·k);

The heat insulation component includes 10 layers of composite materials, each layer of composite material is formed by superimposing polyester mesh towel and aluminized film, and superimposing polyimide film on the upper and lower surfaces of the composite material. The thickness of the heat insulation component is less than 5mm. The equivalent thermal conductivity of the thermal insulation assembly is 0.001.

Optionally, in the thermal control system for a low-Earth orbit gravitational wave detection and verification satellite, the number of the decks is 6, and the decks form a hexahedron;

The thermal insulation gasket is pasted on the boundary coupling surface of the load compartment, and the multi-layer thermal insulation assembly covers the outer surface of the load compartment.

Optionally, in the thermal control system for a low-Earth orbit gravitational wave detection and verification satellite, the automatic temperature control unit includes a heating wire and a temperature measuring element, wherein:

The heating wires are fixed on the inner surface of the load compartment and are covered by a heat-enhancing coating, a plurality of heating wires on each cabin are distributed in parallel, and the distance between the heating wires is 2 cm;

The temperature measuring element is fixed at the space between the heating wires and covered by the enhanced heat exchange coating, and the temperature measuring element is evenly arranged on each deck;

The heating wire is configured to form a constant temperature cage heating area of the load compartment when the load is in operation, and the temperature measuring element is configured to detect the temperature of the load compartment.

Optionally, in the thermal control system for low-Earth orbit gravitational wave detection and verification satellites, the automatic temperature control unit further includes a temperature measurement signal processing circuit, the temperature measurement element is a temperature measurement resistor, and the temperature measurement element is a temperature measurement resistor. The temperature measurement signal processing circuit includes four lead wires, two of which provide a constant voltage at both ends of the temperature measurement resistor, and the other two lead wires provide the current flowing through the temperature measurement resistor to the temperature measurement signal processing circuit, Two pairs of four lead wires form twisted pairs, and shielding layers are used to cover the twisted pairs; the automatic temperature control unit further includes an active heating circuit, the active heating circuit adopts a four-wire system, and the active heating circuit includes a fuse loop.

Optionally, in the thermal control system for a low-Earth orbit gravitational wave detection and verification satellite, the thermal control general processor includes a data acquisition unit, and the data acquisition unit has 32 acquisition digits;

The temperature measurement signal processing circuit provides the current of the temperature measurement resistor to the data acquisition unit, and the data acquisition unit forms a temperature measurement value according to the current of the temperature measurement resistor and sends it to the thermal control processor .

Optionally, in the thermal control system for low-Earth orbit gravitational wave detection and verification satellites, the temperature measurement signal processing circuit is powered by an electrical connector, and the electrical connector is taken from the satellite platform. Electrically, the electrical connector is covered with copper foil.

The present invention also provides a thermal control method for a low-Earth orbit gravitational wave detection verification satellite, wherein the load and thermal control system of the gravitational wave detection satellite are installed inside the platform, characterized in that the method includes:

The load is surrounded and enclosed in the center by a plurality of panels of a primary thermal control module to form a load compartment; thermal insulation gaskets and/or multi-layer thermal insulation assemblies are arranged inside and/or outside the load compartment, isolating the load from other heat sources;

The temperature of the load compartment is detected by the automatic temperature control unit of the secondary thermal control module, and the temperature of the load compartment is sent to the thermal control general processor; the thermal control general processor adopts the PID algorithm according to the load compartment The temperature of the automatic temperature control unit is controlled to adjust the temperature, so that the load compartment forms a constant temperature cage heating area when the load is working; and

The compensation module of the three-stage thermal control module is fixed on the load, the load and the compensation module are wrapped by the multi-layer thermal insulation assembly of the three-stage thermal control module, and the temperature measurement unit of the three-stage thermal control module detects the the temperature of the load, and send the temperature of the load to the general thermal control processor; the general thermal control processor is configured to use a PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, In order to keep the temperature uniform throughout the load during operation.

In the thermal control system and method for low-Earth orbit gravitational wave detection and verification satellites provided by the present invention, the load is enclosed in the center and sealed by the deck of the first-level thermal control module to form a load cabin. / or externally arrange thermal insulation gaskets and / or multi-layer thermal insulation components to isolate the load from other heat sources, the automatic temperature control unit of the secondary thermal control module detects the temperature of the load compartment, and the thermal control general processor adopts PID algorithm according to the load. The temperature of the cabin is controlled by the automatic temperature control unit to adjust the temperature, so that the load cabin forms a constant temperature cage heating area when the load is working. According to the temperature of the load, the compensation module is controlled to adjust the temperature, so that the temperature of the load is kept uniform throughout the work, and the index requirements of the "Taiji-1" satellite load subsystem are realized. An effective thermal control scheme is designed. The method of temperature control achieves a high-precision control index of temperature stability index ±0.005K, which provides a reference for the subsequent high-precision and high-stability thermal control technology.

Description of drawings

1 is a schematic diagram of a thermal control method for a low-Earth orbit gravitational wave detection satellite in an embodiment of the present invention;

2 is a schematic view of a load compartment of a thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to an embodiment of the present invention;

3 is a schematic diagram of an automatic temperature control unit of a thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of the structural design of a "thermostatic cage" thermal control product in an embodiment of the present invention;

5 is a schematic diagram of an on-orbit stability temperature index in an embodiment of the present invention;

As shown in the picture: 10-load cabin; 20-heating wire; 30-temperature measuring element; 40-enhanced heat exchange coating (load cabin); 41-enhanced heat exchange coating (load); 50- deck plate; 60 - Insulation assembly (load compartment); 61 - Insulation assembly (load); 62 - Insulation gasket; 63 - Heater.

Detailed ways

The thermal control system and method for a low-Earth orbit gravitational wave detection and verification satellite proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become apparent from the following description and claims. It should be noted that, the accompanying drawings are all in a very simplified form and in inaccurate scales, and are only used to facilitate and clearly assist the purpose of explaining the embodiments of the present invention.

The core idea of the present invention is to provide a thermal control system and method for a low-Earth orbit gravitational wave detection and verification satellite, so as to realize a high-precision and high-stability thermal control system required by a gravitational wave detection satellite.

In order to realize the above idea, the present invention provides a thermal control system and method for a low-Earth orbit gravitational wave detection and verification satellite, the gravitational wave detection satellite includes a load and a platform, and the load and the thermal control system are located in the inside the platform; the thermal control system includes a first-level thermal control module, a second-level thermal control module, a third-level thermal control module and a thermal control general processor, wherein: the first-level thermal control module includes a plurality of The deck is configured to enclose and enclose the load in the center, forming a load compartment; insulating gaskets and/or multi-layer insulation assemblies are arranged inside and/or outside the load compartment to allow the load to be separated from the load. Other heat sources are isolated; the secondary thermal control module includes an automatic temperature control unit configured to detect the temperature of the load compartment and send the temperature of the load compartment to the thermal control master process The thermal control general processor is configured to use the PID algorithm to control the automatic temperature control unit to adjust the temperature according to the temperature of the load compartment, so that the load compartment forms a constant temperature cage heating area when the load is working ; the three-stage thermal control module includes a compensation module fixed on the load, a thermal insulation assembly wrapping the load and the compensation module, and a temperature measurement unit configured to detect the load the temperature of the load, and send the temperature of the load to the general thermal control processor; the general thermal control processor is configured to use the PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, so as to The temperature of the load is kept uniform throughout the operation.

<Example 1>

This embodiment provides a thermal control system for a low-Earth orbit gravitational wave detection and verification satellite. As shown in FIG. 1 , the gravitational wave detection satellite includes a payload and a platform, and the payload and the thermal control system are located in the Inside the platform; the thermal control system includes a first-level thermal control module, a second-level thermal control module, a third-level thermal control module and a thermal control general processor, wherein: as shown in Figure 2, the first-level thermal control module includes multiple a deck 50 configured to enclose and enclose the load in the center, forming the load bay 10; thermal pads are arranged inside and/or outside of the load bay 10 as shown in Figure 4 Sheet and/or multi-layer thermal insulation assembly 60 to isolate the load from other heat sources; the secondary thermal control module includes an automatic temperature control unit configured to detect the temperature of the load compartment 10 , and send the temperature of the load compartment 10 to the thermal control master processor; the thermal control master processor is configured to use a PID algorithm to control the automatic temperature control unit to perform The temperature is adjusted so that the load compartment 10 forms a constant temperature cage heating area when the load is working; the three-stage thermal control module includes a compensation module fixed on the load, and a spacer wrapping the load and the compensation module. Thermal assembly 60, and a temperature measurement unit configured to detect the temperature of the load and send the temperature of the load to the thermal control master processor; the thermal control master processor is configured In order to use the PID algorithm to control the temperature of the load according to the temperature of the load, the compensation module is controlled to adjust the temperature, so that the temperature of the load is kept uniform everywhere during operation.

Specifically, in the thermal control system for the low-Earth orbit gravitational wave detection and verification satellite, the temperature of the load cabin 10 requires a degree of stability of better than 0.1K/1000 seconds when the load is working, and the on-orbit load is actually obtained. The temperature stability during operation is better than 5mK/1000 seconds. The material of the deck board 50 of the load compartment 10 is a honeycomb structure board compounded with an enhanced heat exchange coating. The material of the thermal insulation gasket is FRP, the thermal insulation gasket is a square sheet with a side length of 15 mm and a thickness of 3 mm, and the thermal conductivity of the thermal insulation gasket is 0.40w/(m·k); The heat insulation component includes 10 layers of composite materials, each layer of composite material is formed by superimposing polyester net towel and aluminized film, and superimposing polyimide film on the upper and lower surfaces thereof, the thickness of the heat insulation component is less than 5mm, and the insulation The thermal component has an equivalent thermal conductivity of 0.001. The number of the cabin panels 50 is 6, and the cabin panels 50 form a hexahedron; the thermal insulation gasket is pasted on the boundary coupling surface of the load compartment 10 , and the multi-layer thermal insulation assembly 60 covers the The outer surface of the load bay 10 .

As shown in FIG. 3 , in the thermal control system for the low-Earth orbit gravitational wave detection and verification satellite, the automatic temperature control unit includes a heating wire 20 and a temperature measuring element 30 , wherein: the heating wire 20 is fixed On the inner surface of the load compartment 10 and covered by an enhanced heat exchange coating 40 (eg black paint), a plurality of heating wires 20 on each cabin panel 50 are distributed in parallel, and the distance between each heating wire 20 is 2 cm ; The temperature measuring element 30 is fixed in the space between the heating wires 20 and is covered by the enhanced heat exchange coating 40, and the temperature measuring element 30 is evenly arranged on each cabin plate 50; the heating wire 20 is configured to make the load compartment 10 form a constant temperature cage heating area when the load is in operation, and the temperature measuring element 30 is configured to detect the temperature of the load compartment 10 . The automatic temperature control unit also includes a temperature measurement signal processing circuit, the temperature measurement element 30 is a temperature measurement resistor, and the temperature measurement signal processing circuit includes four lead wires, two of which are provided at both ends of the temperature measurement resistor. constant voltage, and the other two lead wires provide the current flowing through the temperature measuring resistor to the temperature measurement signal processing circuit; the four lead wires form twisted pairs, and the twisted pair is covered with a shielding layer; the The automatic temperature control unit further includes an active heating circuit, the active heating circuit adopts a four-wire system, and the active heating circuit includes a fuse circuit.

In addition, in the thermal control system for the low-Earth orbit gravitational wave detection and verification satellite, the thermal control general processor includes a data acquisition unit, and the number of acquisition bits of the data acquisition unit is 32; The temperature signal processing circuit provides the current of the temperature measuring resistor to the data acquisition unit, and the data acquisition unit forms a temperature measurement value according to the current of the temperature measuring resistor and sends it to the thermal control processor. The temperature measurement signal processing circuit is powered by an electrical connector, and the electrical connector takes power from the satellite platform, and the electrical connector is covered with copper foil.

To sum up, the above embodiments describe in detail the different configurations of the thermal control system used for the low-Earth orbit gravitational wave detection and verification satellite. Of course, the present invention includes but is not limited to the configurations listed in the above implementation. The contents transformed on the basis of the configurations provided in the above-mentioned embodiments all belong to the protection scope of the present invention. Those skilled in the art can draw inferences from the contents of the foregoing embodiments.

<Example 2>

This embodiment provides a thermal control method for a low-Earth orbit gravitational wave detection verification satellite, wherein the payload of the gravitational wave detection satellite and the thermal control system are installed inside the platform; A deck 50 encloses and encloses the load in the center, forming the load compartment 10; insulating gaskets and/or multilayer insulation assemblies 60 are arranged inside and/or outside of the load compartment 10 so that the load and Other heat sources are isolated; the automatic temperature control unit of the secondary thermal control module detects the temperature of the load compartment 10 and sends the temperature of the load compartment 10 to the thermal control general processor; the thermal control general processor adopts the PID algorithm According to the temperature of the load compartment 10, the automatic temperature control unit is controlled to adjust the temperature, so that the load compartment 10 forms a constant temperature cage heating area when the load is working; the compensation module of the three-stage thermal control module is fixed on the On the load, the multi-layer thermal insulation assembly 60 of the three-stage thermal control module is used to wrap the load and the compensation module, and the temperature measurement unit of the three-stage thermal control module detects the temperature of the load, and calculates the temperature of the load. sent to the thermal control master processor; the thermal control master processor is configured to use the PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, so that the temperature of the load is everywhere during operation. Keep it even.

In the thermal control system and method for a low-Earth orbit gravitational wave detection and verification satellite provided by the present invention, the load (ie, the load body) is surrounded and sealed in the center by the deck 50 of the primary thermal control module to form the load cabin 10 , Arrange thermal insulation gaskets and/or multi-layer thermal insulation components 60 inside and/or outside the load compartment 10 to isolate the load from other heat sources, and the automatic temperature control unit of the secondary thermal control module detects the temperature of the load compartment 10, The thermal control general processor uses the PID algorithm to control the automatic temperature control unit to adjust the temperature according to the temperature of the load compartment 10, so that the load compartment 10 forms a constant temperature cage heating area when the load is working, and the temperature measurement unit of the three-stage thermal control module detects The temperature of the load, the thermal control processor uses the PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, so that the temperature of the load is kept uniform throughout the work, and the index requirements of the "Taiji No. 1" satellite load subsystem are realized. , designed an effective thermal control scheme, and achieved a high-precision control index of ±0.005K temperature stability index by means of three-level temperature control, which provided a reference for the follow-up high-precision and high-stability thermal control technology.

In response to the high index requirements of the load, the thermal control is based on the design concept of "constant temperature cage", and adopts a three-level temperature control method to control the load temperature within the high stability index range of mk level.

Due to the large heat capacity of the load and the high temperature index, the thermal control adopts a multi-level temperature control method, as shown in Figure 1, the "three-level temperature control" method of one separation, two compensation, and three control. Considering that the payload is the core single machine for the completion of the satellite mission, the "first-level temperature control" method adopted for thermal control is to arrange the single payload machine inside the satellite at the initial stage of the satellite layout, and use 6 decks 50 to seal the single payload machine. And through effective thermal insulation (multi-layer thermal insulation assembly 60) means to minimize external thermal disturbances. In order to ensure that the load works at a certain T temperature value, the thermal control adopts the "secondary temperature control" active heating compensation temperature control.

Active PID closed-loop temperature control is performed on the 6 cabin panels 50 during the orbital operation. As shown in Figure 2, the closed cabin is formed into a "constant temperature cage" heating area when the load is working, so as to realize the space environment control of the single load machine within the In the environment of 0.1K; the last is "three-level temperature control", that is, the passive and autonomous temperature control of the load itself. On the one hand, the thermal control is designed to actively heat and compensate the load body, and on the other hand, the multi-layer thermal insulation component 60 is wrapped. , in order to reduce the influence of the external environment on the load body, and through two temperature control methods to ensure the stability of the load's working temperature within 0.1K. Figure 1 is the technical orientation diagram of the three-level temperature control of the thermal control scheme.

In the scheme design of the present invention, the temperature control object is the three-level temperature control and the last level of temperature control. Figure 4 is a sectional view of the designed on-orbit working state of the temperature control object in the satellite layout. The contact boundary of the core load is the thermal insulation gasket 61, the load body (ie the load) is a small compartment surrounding the core load, the visible interface between the core load and the load body is heat radiation, and the inner surface of the load body is enhanced heat exchange. The outer surface of the coating layer 41 is a multi-layer thermal insulation assembly 61, and a thermal insulation gasket 62 is used between the load bodies, and the heat exchange with other parts of the satellite is thermal radiation.

According to the thermal model state of the core load, the steady-state energy conservation equilibrium equation is established as shown below.

Q ₀ =cmΔT(1)

Q ₀ =Q ₁ +Q ₂ +Q ₃ (2)

In formula (1), Q0 represents the energy change of the core load; c represents the specific heat capacity of the controlled object. In this project, the change of the thermal properties of the load material in the working temperature range is basically negligible and considered as a constant; m represents the controlled object. The mass of the object is an inherent property of the material, which is consistent with the temperature characteristics of the heat capacity and can be ignored and considered as a constant; ΔT represents the temperature change. The change in temperature therefore depends on the change in energy absorbed by the core load body.

In formula (2), Q1 represents the internal heat source of the core load; Q2 represents the heat conduction exchange between the core load and the load body; Q3 represents the radiation exchange between the core load and the load body. It can be seen from the equation that if the change of Q0 is required to be the smallest, only the sum of the changes of Q1, Q2 and Q3 is required to be the smallest.

In the thermal control method of the gravitational wave detection satellite of the present invention, Q1 is 0, Q2 is an adjustable design item, and Q3 is a variable item. In order to minimize the change of Q2, the present invention adopts a low thermal conductivity thermal insulation gasket to reduce the effect of heat leakage due to "thermal conduction". Q3 is the maximum heat flow fluctuation term of the core load, and its source of fluctuation is the load fluctuation generated by the active heater during temperature control, which affects the thermal fluctuation of the core load in the form of infrared radiation. In order to reduce the fluctuation of this part, the means of thermal control is to arrange the load fluctuation of the heater 63 on the outer surface of the load body, and then transfer it through the secondary thermal resistance of the longitudinal resistance, so as to ensure the small fluctuation of the load body under a certain temperature. On the other hand, the inside of the load body is covered by an enhanced heat exchange coating 41 (black paint or high-emission coating) to achieve the homogenization of the temperature field in the load body, so as to minimize the fluctuation of the core load as a whole by infrared radiation.

It can be seen from the analysis that when the temperature field inside the load body is more uniform, the temperature stability of the core load is better. When the temperature fluctuation of the load body is smaller, the temperature stability of the core load is better. Therefore, the above two stabilities are well controlled. , you can achieve high-precision temperature control.

In order to achieve high-precision and high-stable temperature indicators, the present invention evaluates the principle and technical level of the thermal control scheme. On the one hand, the thermal implementation of the thermal control product is strictly constrained, and at the same time, the temperature controller is used to collect and control the temperature data of the thermal control product. Three key technologies (temperature measurement, thermal implementation of multi-stage temperature control scheme, and temperature control) are introduced below.

The first is the temperature measurement technology. The temperature measurement resistor is the core temperature measurement element 30, which characterizes the accuracy and stability of the temperature index. In this project, PT1000 is used for thermal control. The temperature accuracy of this product can reach one thousandth of a degree. Before using this product, a strict secondary screening and calibration is carried out to ensure the high precision and high stability of the star-mounted product. . When assembling the product, the four-wire system is adopted, and the external electromagnetic interference is reduced by shielding twisted pairs, and the analog signal is transmitted. During the assembly process, the electrical connector is shielded with copper foil to increase the ability to resist electromagnetic interference; the data acquisition system has a 32-bit acquisition number to achieve high-resolution indicators.

Secondly, the three-level temperature control scheme is one of the key technologies for the realization of high-precision temperature control. The control strategy of thermal control is three-level temperature control, and the object of the first-level temperature control is "load cabin 10". The control method of this part is a combination of passive means and active means. First, through thermal insulation gaskets and multi-layer thermal insulation The component 60 product isolates the thermal fluctuation of the star from multiple layers, and then controls the load compartment 10 plate to fluctuate within T±0.1k through active heating; the object of secondary temperature control is also "load compartment 10". The control method is a purely passive method. On the one hand, the load compartment 10 is insulated from the core load, and on the other hand, the black paint enhances heat exchange to make the temperature in the load compartment 10 uniform, so as to achieve a uniform heat flow obtained by the core load. , stabilized; the object of the three-level temperature control is the core load, which adopts a combination of passive means and active means, and conducts thermal isolation through the multi-layer thermal insulation component 61 to further weaken the small infrared heat flow fluctuations generated by the load body. The change of heat flow to the core load body is minimized, and active PID thermal control is adopted, so that the temperature control stability index is better than ±0.1k.

Finally, another technology to achieve precise thermal control is to use a single temperature controller to collect and control thermal control products. The use of a single temperature controller is mainly to solve the influence of the load fluctuation of the whole satellite on the thermal control acquisition and control. In the product development and control of the temperature controller stand-alone, the acquisition accuracy (0.001k), the system stability index (±0.1k), and the temperature control frequency (2s/60 channels). The temperature measurement circuit of the single temperature controller adopts a four-wire constant current source temperature collection method, which is more stable and accurate than the conventional two-wire system. Because the PID control method is simple and easy to operate, has good stability and high reliability, as long as the control parameters are properly selected, static deviation can be eliminated with less overshoot, and high-precision and high-stability temperature control can be realized. The control method adopts PID control, and the control algorithm adopts the position type, the effect is more stable than the incremental control algorithm, and tends to the target value.

The "Taiji-1" satellite was launched on August 31, 2019. The payloads were turned on one after another, and the temperature field of the whole satellite gradually entered a stable state. According to the planning of the experimental task, the thermal control mode gradually entered the fine control mode. During the mode, the thermal control is controlled by the temperature field. Table 1 shows the results of the on-orbit temperature control stability index.

Table 1 On-orbit temperature control stability index results

According to the statistics obtained in Table 1, it can be seen that:

1) Since the temperature field in all directions is greatly affected by the fluctuation of the internal heat source of the satellite, the stability index of the Y-direction (towards the sun and the back of the sun) with no heat source and stable heat flow can reach ±0.05 under the condition of active temperature control. K.

2) When the stability index of the load body is better than 0.3K, the index requirement of high precision control of the core load of 0.1K can be met.

3) During the on-orbit test, only passive radiation and thermal insulation are used to control the temperature of the load, and it is found that a high stability index of ±0.005K can be achieved. Figure 5 shows the highly stable temperature control results obtained on-orbit.

Although the current "Tai Chi No. 1" high-precision temperature control technology can achieve a stability index of ±0.005K, there is still a lot of room for improvement from the uK level index of "Tai Chi No. 2". According to the review of the index of the thermal control product in the development process and the research on the single machine performance of the temperature controller, the present invention finds that the following aspects should be considered in tackling the key requirements of the precise control with higher index: to find a temperature measuring resistance with excellent stability; Improve the resolution of the temperature controller stand-alone and reduce the impact of noise on components; optimize the temperature measurement circuit, consider using a better bridge circuit for acquisition; improve the simulation calculation and simulation technology, and accurately identify PID parameters.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes and modifications made by those of ordinary skill in the field of the present invention based on the above disclosure all belong to the protection scope of the claims.

Claims (10)

1. A thermal control system for a low-Earth orbit gravitational wave detection verification satellite, the gravitational wave detection satellite comprises a load and a platform, and the load and the thermal control system are located inside the platform, characterized in that the The thermal control system includes: A primary thermal control module comprising a plurality of panels configured to enclose and enclose the load in the center, forming a load compartment; thermally insulating gaskets are arranged inside and/or outside the load compartment and/or multi-layer thermal insulation assemblies to isolate said loads from other heat sources; a secondary thermal control module comprising an automatic temperature control unit configured to detect the temperature of the load compartment and send the temperature of the load compartment to the thermal control master processor; the The thermal control general processor is configured to use the PID algorithm to control the automatic temperature control unit to adjust the temperature according to the temperature of the load compartment, so that the load compartment forms a constant temperature cage heating area when the load is working; A three-stage thermal control module includes a compensation module fixed on the load, a thermal insulation assembly wrapping the load and the compensation module, and a temperature measurement unit configured to detect the temperature of the load. temperature of the load, and send the temperature of the load to the thermal control master processor; and a thermal control master processor, which is configured to use a PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, so as to The temperature of the load is kept uniform throughout the operation. 2. The thermal control system for low-Earth orbit gravitational wave detection and verification satellites according to claim 1, wherein the temperature of the load cabin requires a degree of stability better than 0.1K/1000 seconds when the load is working. The temperature stability is better than 5mK/1000s when working with on-orbit load. 3 . The thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to claim 1 , wherein the deck material of the load compartment adopts a honeycomb structure plate compounded with an enhanced heat exchange coating. 4 . 4. The thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to claim 1, wherein the material of the thermal insulation gasket is glass fiber reinforced plastic, and the thermal insulation gasket is a side length of 15mm A square sheet with a thickness of 3mm, the thermal conductivity of the thermal insulation gasket is 0.40w/(m·k); The heat insulation component includes 10 layers of composite materials, each layer of composite material is formed by superimposing polyester mesh towel and aluminized film, and superimposing polyimide film on the upper and lower surfaces of the composite material. The thickness of the heat insulation component is less than 5mm. The equivalent thermal conductivity of the thermal insulation assembly is 0.001. 5. The thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to claim 1, wherein the number of the decks is 6, and the decks form a hexahedron; The thermal insulation gasket is pasted on the boundary coupling surface of the load compartment, and the multi-layer thermal insulation assembly covers the outer surface of the load compartment. 6. The thermal control system for a low-Earth orbit gravitational wave detection verification satellite according to claim 5, wherein the automatic temperature control unit comprises a heating wire and a temperature measuring element, wherein: The heating wires are fixed on the inner surface of the load compartment and are covered by a heat-enhancing coating, a plurality of heating wires on each cabin are distributed in parallel, and the distance between the heating wires is 2 cm; The temperature measuring element is fixed at the space between the heating wires and covered by the enhanced heat exchange coating, and the temperature measuring element is evenly arranged on each deck; The heating wire is configured to form a constant temperature cage heating area of the load compartment when the load is in operation, and the temperature measuring element is configured to detect the temperature of the load compartment. 7. The thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to claim 6, wherein the automatic temperature control unit further comprises a temperature measurement signal processing circuit, and the temperature measurement element is a temperature measurement element. The temperature measurement signal processing circuit includes four lead wires, two of which provide a constant voltage at both ends of the temperature measuring resistor, and the other two lead wires provide the current flowing through the temperature measuring resistor to the temperature measuring resistor. Signal processing circuit, two pairs of four lead wires form a twisted pair, and a shielding layer is used to cover the twisted pair; the automatic temperature control unit also includes an active heating loop, the active heating loop adopts a four-wire system, and the active heating loop adopts a four-wire system. The heating circuit includes a fuse circuit. 8. The thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to claim 7, wherein the thermal control total processor comprises a data acquisition unit, and the number of acquisition digits of the data acquisition unit is: 32 bits; The temperature measurement signal processing circuit provides the current of the temperature measurement resistor to the data acquisition unit, and the data acquisition unit forms a temperature measurement value according to the current of the temperature measurement resistor and sends it to the thermal control processor . 9. The thermal control system for a low-Earth orbit gravitational wave detection and verification satellite according to claim 7, wherein the temperature measurement signal processing circuit is powered by an electrical connector, and the electrical connector is powered from the Power is taken from the satellite platform, and the electrical connector is covered with copper foil. 10. A thermal control method for a low-Earth orbit gravitational wave detection verification satellite, wherein the load and thermal control system of the gravitational wave detection satellite are installed inside the platform, wherein the method comprises: The load is surrounded and enclosed in the center by a plurality of panels of a primary thermal control module to form a load compartment; thermal insulation gaskets and/or multi-layer thermal insulation assemblies are arranged inside and/or outside the load compartment, isolating the load from other heat sources; The temperature of the load compartment is detected by the automatic temperature control unit of the secondary thermal control module, and the temperature of the load compartment is sent to the thermal control general processor; the thermal control general processor adopts the PID algorithm according to the load compartment The temperature of the automatic temperature control unit is controlled to adjust the temperature, so that the load compartment forms a constant temperature cage heating area when the load is working; and The compensation module of the three-stage thermal control module is fixed on the load, the load and the compensation module are wrapped by the multi-layer thermal insulation assembly of the three-stage thermal control module, and the temperature measurement unit of the three-stage thermal control module detects the the temperature of the load, and send the temperature of the load to the general thermal control processor; the general thermal control processor is configured to use a PID algorithm to control the compensation module to adjust the temperature according to the temperature of the load, In order to keep the temperature uniform throughout the load during operation.

Images