Satellite computer remanence control system

Abstract

The application discloses a residual magnetism control system of a satellite-borne computer, and realizes basic functions of the satellite-borne computer by setting a power management module, a processor module, an analog switch switching module, a digital quantity output and analog quantity module, a communication module, a heating driving module, a remote control terminal module and a GNSS module. When all the modules are arranged on a PCB board, the loop area of an address bus and a data bus in a system bus is not more than 8 square centimeters during PCB wiring, the power supply lines and ground lines of all the modules are arranged on a plane layer, the residual magnetism and magnetic induction of the satellite-borne computer are reduced, and the magnetic change of the satellite-borne computer under various working conditions is reduced.

Description

Technical Field

[0001] This invention relates to the field of computer residual magnetism control technology, specifically to a spaceborne computer residual magnetism control system. Background Technology

[0002] With the development of high technology and the driving force of mission requirements, small satellites, with their advantages of small size, low power consumption, short development cycle, and ability to complete more complex space missions at a lower cost, are playing an important role in scientific research, national defense, and commercial applications. The onboard computer is the core of the satellite platform, and its main functions include managing various flight missions and processing data, managing onboard time and performing full satellite time calibration, controlling and managing autonomous operation modes, and acquiring and controlling satellite attitude and orbit data. The remanent magnetic moment of these small satellite onboard computers is ≤200 mA·m. 2 .

[0003] Space physics is a cutting-edge, interdisciplinary fundamental discipline that has emerged alongside the development of space technology. It primarily studies physical phenomena in the Sun-Earth space region, with the Sun-Earth coupling problem being one of the core issues in space science research worldwide. Due to the high precision of the magnetometers installed on satellites, stringent requirements are placed on the satellite's magnetic cleanliness to ensure that the acquired data effectively reflects changes in the space magnetic field. The onboard computer is the core of the satellite platform; therefore, strict requirements are imposed on its remanence, requiring that the remanence moment of the onboard computer be ≤15 mA·m without magnetic compensation. 2 .

[0004] This technology controls the remanence of the onboard computer from multiple aspects, ensuring that the remanence moment of the onboard computer does not exceed 15 mA·m. 2 Therefore, with the development of space application technology, there is an urgent need to develop better residual magnetism control technology to greatly improve the reliability of space products. Summary of the Invention

[0005] The purpose of this invention is to provide a remanent magnetization control system for spaceborne computers to overcome the problem that the magnetic cleanliness of existing technologies cannot meet current requirements.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A spaceborne computer residual magnetism control system includes two functionally identical computer systems. Each computer system includes a power management module, a processor module, an analog switch switching module, a digital output and analog quantity module, a communication module, a heating drive module, a remote control terminal module, and a GNSS module connected to a system bus. The power management module, processor module, analog switch switching module, digital output and analog quantity module, communication module, heating drive module, remote control terminal module, and GNSS module are all mounted on a PCB board. When routing the PCB, the loop area of ​​the address bus and data bus in the system bus does not exceed 8 square centimeters. The power lines and ground lines of all modules are placed on the plane layer.

[0008] Power management module: used for switching control between the two computer systems;

[0009] Processor module: Used for data processing in a computer;

[0010] Analog switch switching module: used for simulating switch selection and switching;

[0011] Digital output and analog output modules: used for outputting digital instructions and conditioning signals;

[0012] Communication module: Used for communication between modules;

[0013] Heating drive module: Used for power output in computer systems;

[0014] Remote control terminal module: used to control the start and stop of the computer system;

[0015] GNSS module: used for GPS positioning.

[0016] Preferably, the power management module includes a current-limiting resistor, a relay, a surge suppression circuit, a filter, and a power module connected in sequence.

[0017] Preferably, the relays are used in pairs and placed opposite each other, with a lateral distance between them greater than 3mm.

[0018] Preferably, the processor module includes a processor, an FPGA, a program memory, a data memory, a power-on reset circuit, and a clock circuit. The processor communicates with the FPGA, the program memory, and the data memory, respectively, and receives clock circuit signals and host reset circuit signals.

[0019] Preferably, the clock circuit is located away from the input and output terminals.

[0020] Preferably, the area of ​​the current loop formed by the control circuit does not exceed 2 square centimeters.

[0021] Preferably, the power cords of all modules are placed close to the ground wire.

[0022] Preferably, the computer system further includes structural components and mechanical components, wherein the structural components and mechanical components are made of non-magnetic materials.

[0023] Preferably, a chassis is installed on the outside of the computer system, and the power cord of the chassis is a twisted pair cable. The chassis cannot be connected to the power ground wire.

[0024] Preferably, the signal lines led out from each module in the computer system are connected to the electrical connectors using cables, and the distance between the cable harness binding point and the soldering surface of the electrical connector is less than or equal to more than 20mm.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a residual magnetism control system for a spaceborne computer. By setting up a power management module, a processor module, an analog switch switching module, a digital output and analog output module, a communication module, a heating drive module, a remote control terminal module, and a GNSS module, the basic functions of the spaceborne computer are realized. By setting all modules on a PCB board, the loop area of ​​the address bus and data bus in the system bus does not exceed 8 square centimeters when routing the PCB. The power lines and ground lines of all modules are placed on the plane layer, which reduces the residual magnetism and magnetic induction of the spaceborne computer and reduces the magnetic changes of the spaceborne computer under various operating conditions.

[0026] Furthermore, the relays are used in pairs and placed opposite each other with a lateral distance of more than 3mm between them. The opposite placement cancels out most of the magnetic field, thus achieving mutual cancellation of the magnetic field.

[0027] Furthermore, the clock circuit is located far from the input and output terminals, further reducing the residual magnetism of the onboard computer.

[0028] Furthermore, the current loop area formed by the control circuit does not exceed 2 square centimeters, which facilitates residual magnetism control.

[0029] Furthermore, the power lines of all modules are placed close to the ground wire to minimize the area of ​​the current loop and reduce the influence of the magnetic field.

[0030] Furthermore, the structural and mechanical components of the computer system are made of non-magnetic materials to further reduce the influence of magnetic fields.

[0031] Furthermore, the power supply cable of the chassis is a twisted pair, and the chassis cannot be connected to the power ground wire, which allows for better control of residual magnetism.

[0032] Furthermore, the signal lines led out from each module in the computer system are connected to the electrical connectors using cables. The distance between the cable harness binding point and the welding surface of the electrical connector is less than or equal to more than 20mm. This reduces the loop area formed by the opening of the electrical connector cable, thereby reducing the influence of magnetic fields. Attached Figure Description

[0033] Figure 1 This is a block diagram of the onboard computer system of the present invention;

[0034] Figure 2 This is a structural diagram of the onboard computer chassis of this invention;

[0035] Figure 3 This is a block diagram of the POW module of the present invention;

[0036] Figure 4 This is a block diagram of the CPU module of the present invention;

[0037] Figure 5 This is the layout of the relay of the present invention;

[0038] Figure 6 This is the PCB routing design requirement of this invention;

[0039] Figure 7 This invention relates to the power cord and return line routing design;

[0040] Figure 8 This is a schematic diagram of the terminal connections of the present invention;

[0041] Figure 9 This is a schematic diagram of the wiring at the cable opening of the electrical connector of the present invention. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0043] This invention provides a remanent magnetization control system for a spaceborne computer, which has been applied to the spaceborne computers of the Zhang Heng satellite, the two probe satellites, the Sino-French satellite, and the Tianhui satellite. It has the following advantages:

[0044] Controlling Residual Magnetism from Magnetic Materials: The materials used in spaceborne computers fall into three main categories: raw materials, electronic components, and chassis electrical connectors. ① To reduce the magnetism of the spaceborne computer itself, the first step should be material selection. Structural and mechanical components should be manufactured using non-magnetic materials, and other parts should also be made from non-magnetic materials as much as possible. Common non-magnetic materials include duralumin, rust-resistant aluminum, brass, copper, solder, and titanium. ② Although the components are small and lightweight, their large quantity can significantly impact the magnetic field of the spaceborne computer. The selection of materials and manufacturing processes for components can lead to components having a large magnetic field. Furthermore, the magnetic field value can vary significantly between different batches of the same model. Therefore, low-magnetic components should be selected whenever possible. For components with large magnetic field values, measures should be taken in their layout to cancel out the magnetic fields and reduce the surrounding magnetic field distribution. ③ Generally, the chassis electrical connectors of spaceborne computers use J14A or J36A series connectors. These connectors have stainless steel shells and high remanent magnetic moments. For spaceborne computers with strict requirements for remanent magnetization control, low-magnetic connectors are used, such as the J14W or J36W series connectors from Factory 693. These connectors are made of low-magnetic materials with a remanent magnetic moment <0.2 mA·m. 2 .

[0045] Stray magnetic field control caused by current: Stray magnetic fields are magnetic fields caused by current loops, and the strength of the magnetic field is related to the magnitude of the current and the area of ​​the current loop. The main methods to reduce stray magnetic fields are to minimize current loops through careful placement of PCB components and optimized routing design; and to twist the power supply and return lines in the chassis cables to ensure that the current loops are minimized.

[0046] This invention discloses a residual magnetism control system for a spaceborne computer. By optimizing the selection of raw materials and components, the layout of components, and the design of wiring, the residual magnetism and magnetic induction of the spaceborne computer are eliminated or reduced, thereby greatly reducing the magnetic changes of the spaceborne computer under various operating conditions.

[0047] This residual magnetism control technology greatly reduces the residual magnetism of the onboard computer, further improving the reliability and service life of small satellites. Currently, the residual magnetism control in small satellite onboard computers performs well and meets the application requirements of small satellites.

[0048] The onboard computer consists of two functionally identical and completely independent units, A and B, forming a fully cold-standby dual-machine system. Each unit functionally includes a power management module (POW), a processor module (CPU), an analog switch module (ASW), a digital output and analog input module (APU), a communication module (TCU), a heating drive module (HDC), a remote control terminal module (RCT), and a GNSS module (GPS positioning). A block diagram of the onboard computer is shown below. Figure 1The system includes: a power management module for switching between the two computer systems; a processor module for data processing; an analog switch switching module for analog switch selection; a digital output and analog output module for digital instruction output and signal conditioning; a communication module for communication between modules; a heating drive module for power output of the computer system; a remote control terminal module for controlling the start and stop of the computer system; and a GNSS module for GPS positioning.

[0049] The spaceborne computer adopts a plug-in modular structure. The chassis is assembled from front and rear panels, left and right side panels, and top and bottom covers made of high-strength hard aluminum alloy. Printed component guide rails are machined on the left and right side panels. The plug-in boards are pressed into the guide rails by a wedge-shaped locking mechanism. A motherboard mounted at the bottom of the chassis provides bus connections and interconnections for the various plug-in boards. A schematic diagram of the chassis structure is shown below. Figure 2 As shown, the processing logic of all the signal lines brought out to the outside is distributed on different functional modules. They are sorted and classified by the computer motherboard and then connected to the external electrical connectors through cables.

[0050] The POW power management module primarily provides power to the onboard computer and controls the switching between A and B units. This module mainly consists of current-limiting resistors, relays, surge suppression circuits, filters, and a power supply module. The relays are controlled primarily by the power-on / off commands from the direct remote control unit and the switching circuit. The POW module's block diagram is shown below. Figure 3 As shown.

[0051] The CPU module is the data processing core of the spaceborne computer, mainly composed of a processor, FPGA, program memory, data memory, power-on reset circuit, driver circuit, clock circuit, and other external interface circuits. The CPU module functional block diagram is shown below. Figure 4 As shown.

[0052] The design of residual magnetism control for spaceborne computers mainly involves several aspects, including raw material and component selection, PCB design of each plug-in board, chassis current-carrying wire design, and wire harness binding process. Its main technical specifications are as follows:

[0053] For raw material selection, the structural and mechanical components of the onboard computer are manufactured using non-magnetic materials, and other parts are also made from non-magnetic materials as much as possible. Common non-magnetic materials include duralumin, rust-resistant aluminum, brass, copper, solder, and titanium, while common soft magnetic materials include pure iron and permalloy. The magnetic susceptibility test results of commonly used satellite materials are shown in Table 1. Materials with a magnetic susceptibility less than 1×10⁻⁶ should be selected whenever possible. -5 Materials. For soft magnetic materials, their use should be avoided as much as possible during the design process. If hard and soft magnetic materials must be used in the design, they should be kept as far apart as possible. The magnetic susceptibility test results of commonly used satellite materials are shown in Table 1.

[0054] Table 1

[0055]

[0056]

[0057] For the selection of chassis electrical connectors, the chassis electrical connectors of general spaceborne computers use J14A or J36A series connectors. For spaceborne computers with strict requirements for residual magnetism control, the chassis electrical connectors should be made of low magnetic materials, such as the J14W or J36W series connectors from Factory 693.

[0058] The selection of electronic components is crucial. While small and lightweight, the sheer number of these components can significantly impact the magnetic field of the onboard computer. The materials and manufacturing processes of components can contribute to their inherent magnetic fields, and even components of the same model can exhibit significant differences in magnetic field values ​​between different batches. Therefore, low-magnetic components should be selected whenever possible. For components with high magnetic field values, measures should be taken in their placement to cancel out the magnetic fields and reduce the surrounding magnetic field distribution. Generally, the higher the rated parameters of most components, the stronger their magnetism; therefore, derating beyond the standard is not recommended. Component usage methods should aim to reduce the magnetism of the equipment. Here are some recommended usage methods: ① DC / DC Residual Magnetism Control: Use identical DC / DC converters to control the operating frequency of each DC / DC converter; the DC / DC converter should have a phase-shifting circuit to consider mutual compensation of operating points. ① Through proper layout, the magnetic moments of the DC / DC modules cancel each other out; ② Capacitor residual magnetism control: Capacitor leads should be as short as possible because when capacitors are mounted on the printed circuit board, the traces on the printed circuit board objectively lengthen the capacitor leads, thereby increasing the equivalent series inductance of the capacitor. The spaceborne computer uses surface-mount capacitors to ensure the shortest possible capacitor leads; ③ Relay residual magnetism control: If relays are used, they must be used in pairs and placed opposite each other to cancel out most of the magnetic field. If paired use is not possible, permanent magnetic compensation must be provided. The relays used in the spaceborne computer are all used in pairs and placed opposite each other (see relay layout for details). Figure 5 ④ Residual magnetism control of device leads / pins: Device leads / pins should be as short as possible to avoid generating additional magnetic fields. The resistors, capacitors, crystal oscillators, fuses, etc., selected for spaceborne computers are all surface-mount devices, and integrated circuits are also selected from surface-mount packages as much as possible to ensure the shortest possible device leads. The pin length of through-hole devices is less than 1mm.

[0059] Component placement should adhere to the following requirements: ① The placement of DC / DC converters within the chassis should consider magnetic cancellation; ② Relays should be used in pairs and placed opposite each other to cancel out most of the magnetic field (see relay placement section). Figure 5 );③ The clock circuit is placed far away from the input and output terminals.

[0060] PCB routing design for spaceborne computers primarily involves residual magnetism control from the following five aspects: ① The current loop area formed by the control system clock circuit should not exceed 2 square centimeters; ② The loop area of ​​the address bus and data bus should not exceed 8 square centimeters; ③ Component leads / pins should be as short as possible to avoid generating additional magnetic fields. Proper PCB routing design includes... Figure 6 As shown; ④ Power and ground lines should be placed on the plane layer as much as possible, and each power network should have a corresponding return (ground) layer in the same position on the PCB to ensure that there are no "floating" current paths, so as to minimize the area of ​​the current loop; ⑤ For power and ground lines running on printed traces, the power lines should be placed as close to the ground lines as possible to minimize the loop area formed by the power lines and ground lines. Figure 7 As shown, the loop area formed by the power line and the ground line is reduced after the routing is adjusted.

[0061] The design of current-carrying conductors and spaceborne computer cables mainly focuses on residual magnetism control from the following four aspects: ① The power supply leads of the chassis use twisted-pair cables to ensure the minimum current loop area; ② Internal cables are twisted together as much as possible; ③ Ensure that the power ground wire is not connected to the chassis itself to avoid forming a conductive loop and adding an interfering magnetic field; ④ For equipment where the positive and negative terminals are not together, to reduce the current loop area, a... Figure 8 The optimal routing method for method 3.

[0062] The wire harness binding process should minimize the loop area formed by the cable opening of the electrical connector. The distance between the wire harness binding point and the soldering surface of the electrical connector should not exceed 20mm. A wiring diagram of the cable opening of the electrical connector is shown below. Figure 9 As shown.

[0063] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A spaceborne computer residual magnetism control system, characterized in that, It includes two identical computer systems. Each computer system includes a power management module, a processor module, an analog switch switching module, a digital output and analog output module, a communication module, a heating drive module, a remote control terminal module, and a GNSS module connected to the system bus. The power management module, processor module, analog switch switching module, digital output and analog output module, communication module, heating drive module, remote control terminal module, and GNSS module are all mounted on a PCB board. When routing the PCB, the loop area of ​​the address bus and data bus in the system bus does not exceed 8 square centimeters. The power lines and ground lines of all modules are placed on the plane layer. Power management module: used for switching control between the two computer systems; Processor module: Used for data processing in a computer; Analog switch switching module: used for simulating switch selection and switching; Digital output and analog output modules: used for outputting digital instructions and conditioning signals; Communication module: Used for communication between modules; Heating drive module: Used for power output in computer systems; Remote control terminal module: used to control the start and stop of the computer system; GNSS module: used for GPS positioning.

2. The remanent magnetization control system for a spaceborne computer according to claim 1, characterized in that, The power management module includes a current-limiting resistor, a relay, a surge suppression circuit, a filter, and a power module connected in sequence.

3. The remanent magnetization control system for a spaceborne computer according to claim 2, characterized in that, The relays are used in pairs and placed opposite each other, with a lateral distance between them greater than 3mm.

4. The remanent magnetization control system for a spaceborne computer according to claim 1, characterized in that, The processor module includes a processor, an FPGA, a program memory, a data memory, a power-on reset circuit, and a clock circuit. The processor communicates with the FPGA, the program memory, and the data memory, respectively, and receives clock circuit signals and upper-level reset circuit signals.

5. A remanent magnetization control system for a spaceborne computer according to claim 4, characterized in that, The clock circuit is located away from the input and output terminals.

6. The remanent magnetization control system for a spaceborne computer according to claim 4, characterized in that, The area of ​​the current loop formed by the control circuit shall not exceed 2 square centimeters.

7. The remanent magnetization control system for a spaceborne computer according to claim 1, characterized in that, The power cables for all modules are placed close to the ground wire.

8. The remanent magnetization control system for a spaceborne computer according to claim 1, characterized in that, The computer system also includes structural and mechanical components, which are made of non-magnetic materials.

9. A remanent magnetization control system for a spaceborne computer according to claim 1, characterized in that, The computer system is equipped with a chassis on its exterior. The power cord of the chassis is a twisted pair cable, and the chassis must not be connected to the power ground wire.

10. A remanent magnetization control system for a spaceborne computer according to claim 1, characterized in that, The signal lines led out from each module in the computer system are connected to electrical connectors via cables. The distance between the cable harness binding point and the soldering surface of the electrical connector is less than or equal to more than 20 mm.

Images