Energy Harvesting Mechanisms and Methods for Constellation Satellites Based on Non-Twilight Sun-Synchronous Orbits

Abstract

The present invention discloses a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit, which includes a sailboard, on which a solar cell is mounted, and the normal vector of the sailboard is maintained in the YOZ plane of the barycenter orbit coordinate system, and forms an angle with the Y axis of the barycenter orbit coordinate system. The solar cell of the mechanism is mounted in the orbital plane, which effectively ensures that the angle between the normal vector of the sailboard and the sun vector is small, thereby obtaining a good energy supply.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to a sailboard offset installation or rolling tracking strategy design for energy acquisition of a constellation satellite based on a non-dawn-dusk sun-synchronous orbit. Background Art

[0002] The solar array of a satellite usually includes a large number of solar cells attached to a certain surface of the satellite, and / or solar panels or solar wings attached to one or more unfoldable flat plates. The solar array is mainly used to receive sunlight and absorb solar energy to convert it into electrical energy required by the satellite.

[0003] Satellite solar arrays are the main way for satellites to obtain solar energy, and keeping sunlight vertically irradiating the surface of the solar array is undoubtedly the most efficient geometric angle for converting light into electricity. However, the relative angle between the satellite and the sunlight is mainly determined by the satellite's orbital inclination, the local time of the orbital descending node, and the seasonal changes of the sun. Not all satellites on orbit can easily achieve vertical solar arrays to receive energy. Therefore, in order to achieve high-efficiency vertical exposure to the sun for solar arrays, in-orbit satellites can usually adopt different technical solutions. For example, most large remote sensing satellites such as LandSat usually install solar arrays obliquely, while space stations generally install solar arrays on SADA or turntables for one-dimensional or two-dimensional maneuvers, and Beidou navigation satellites use one-dimensional rotation of the solar array and one-dimensional yaw maneuvers of the star attitude to achieve a relatively vertical exposure to the sun.

[0004] However, in aerospace applications, the cost-effectiveness of project implementation should be emphasized. For the two-dimensional maneuvers of the solar array driven by SADA and turntables, it will inevitably bring about a larger inertia impact on the entire satellite, and thus affect the attitude control of the satellite. For the solar orientation carried out by assisting the satellite's two-dimensional attitude maneuvers, for large satellites with large mass and inertia, it will undoubtedly bring design pressure to the attitude control system, and will affect the existing pointing requirements of payloads such as intersatellite communications. Summary of the invention

[0005] In response to some or all of the problems in the prior art, the present invention, on one hand, provides a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit, including a sailboard, on which solar cells are mounted, and the normal vector of the sailboard is maintained in the YOZ plane of the center-of-mass orbit coordinate system, and forms an angle with the -Y axis of the center-of-mass orbit coordinate system.

[0006] Furthermore, the angle is a fixed value.

[0007] Furthermore, the value of the angle is determined according to the maximum charging efficiency mean.

[0008] Furthermore, the sailboard is dynamically deflected around the X-axis of the center of mass orbit coordinate system.

[0009] Furthermore, the sailboard follows the projection of the sun vector on the YOZ plane of the barycenter orbital coordinate system and dynamically deflects around the X-axis of the barycenter orbital coordinate system.

[0010] Furthermore, the angle varies in the range of: [-(90°-β), (90°-β)], wherein β is the orbital solar angle.

[0011] Based on the above constellation satellite energy acquisition mechanism, the present invention further provides a constellation satellite energy acquisition method based on a non-dawn-dusk sun-synchronous orbit, comprising:

[0012] The solar cell sheet is mounted on the sailboard, wherein the normal vector of the sailboard is maintained in the YOZ plane of the center of mass orbit coordinate system and forms an angle with the -Y axis of the center of mass orbit coordinate system.

[0013] Furthermore, the constellation satellite energy acquisition method also includes:

[0014] The sailboard is controlled to follow the projection of the sun on the YOZ plane of the barycenter orbit coordinate system and dynamically deflect around the X-axis of the barycenter orbit coordinate system to reduce the angle between the normal vector of the sailboard and the sun.

[0015] The present invention provides a constellation satellite energy acquisition mechanism and method based on a non-dawn and dusk sun-synchronous orbit, which is suitable for small satellites whose satellite orbit is a descending node local time close to the dawn and dusk sun-synchronous orbit. The solar cell sheet is mounted in a direction parallel to the orbital plane to ensure that the angle between the normal vector of the sailboard and the sun vector is small, thereby obtaining a good energy supply. The solar sailboard of the structure adopts a one-dimensional offset mounting strategy or a one-dimensional sun tracking strategy to achieve sun tracking, which can save the cost of SADA or turntable, and is a cost-effective solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.

[0017] Figure 1 Schematic diagram showing the change of orbital solar angle in one year for different orbits;

[0018] Figure 2 A schematic diagram showing a mass center orbit coordinate system;

[0019] Figure 3a-3cA schematic diagram showing the relationship between the sailboard normal vector and the sun vector;

[0020] Figure 4a-4b A schematic diagram showing the deflection of a sailboard normal vector of a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit following the sun in one embodiment of the present invention;

[0021] Figure 5 A schematic flow chart showing a method for acquiring energy from a constellation satellite based on a non-dawn-dusk sun-synchronous orbit according to an embodiment of the present invention;

[0022] Figure 6a A schematic diagram showing a change in the mean value of the charging efficiency of a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit as the normal vector of the sailboard changes with the -Y axis angle of the center of mass orbit coordinate system according to an embodiment of the present invention;

[0023] Figure 6b A schematic diagram showing a change in the average value of the maximum charging efficiency of a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit as the normal vector of the sailboard and the -Y axis angle of the center of mass orbit coordinate system according to an embodiment of the present invention;

[0024] Figure 7a A schematic diagram showing a change in the mean value of the charging efficiency of a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit as the angle between the projection of the unit sun vector on the X1O1Z1 plane and the O1X1 axis according to an embodiment of the present invention; and

[0025] Figure 7b A schematic diagram showing how the average maximum charging efficiency of an energy acquisition mechanism of a constellation satellite based on a non-dawn-dusk sun-synchronous orbit varies with the orbital solar angle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that the various embodiments can be implemented without one or more specific details or with other replacement and / or additional methods or components. In other cases, well-known structures or operations are not shown or described in detail to avoid blurring the inventive point of the present invention. Similarly, for the purpose of explanation, specific numbers and configurations are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, the present invention is not limited to these specific details. In addition, it should be understood that the various embodiments shown in the drawings are illustrative representations and are not necessarily drawn in correct proportions.

[0027] In this specification, reference to "one embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing in various places in this specification does not necessarily all refer to the same embodiment.

[0028] It should be noted that the embodiments of the present invention describe the method steps in a specific order, but this is only for the purpose of illustrating the specific embodiment, rather than limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to actual needs.

[0029] In the existing solar tracking solutions, two-dimensional maneuvers are mostly achieved through SADA or turntables, or with the assistance of satellite attitude maneuvers, and the cost-effectiveness of engineering implementation is low. In order to achieve a cost-effective solar tracking solution, the inventor studied the influence of the orbital solar angle β on the charging efficiency of satellite solar panels. Among them, the orbital solar angle refers to the angle between the orbital plane of the satellite and the sun vector. If the sun vector and the orbital plane normal are on the same side of the orbital plane, it is positive, otherwise it is negative. Figure 1 Schematic diagram showing the change of orbital solar angle in one year for different orbits. Figure 1 As shown, the orbital solar angle of different satellite orbits has different changing patterns within one year. In order to obtain better charging efficiency, different satellite orbits have different requirements for the installation and maneuvering strategies of solar arrays, where the charging efficiency refers to the cosine of the angle between the normal vector of the sailboard and the solar vector. For example, when the solar array is parallel to the orbital plane, it is equivalent to the normal direction of the solar array being along the normal direction or negative normal direction of the orbital plane, and the charging efficiency can be calculated as cos(90°-β)=sin(β). Based on this, the inventors found that one-dimensional biased installation or one-dimensional dynamic tracking of the solar array can actually be used to improve the charging efficiency. Although one-dimensional biased installation or one-dimensional dynamic tracking of the solar array cannot obtain 100% of the solar energy like two-dimensional maneuvering, it is a cost-effective engineering implementation optional strategy under the premise of compromise between reliability, complexity and energy acquisition efficiency. Therefore, different orbital solar angles can be analyzed according to different orbit types, and then the one-dimensional maneuvering strategy of the solar array can be analyzed according to different orbital solar angles.

[0030] In the embodiments of the present invention, the solar array facing method of the sun of the sun-synchronous orbit constellation networking satellite is mainly considered to solve the problem of stable energy acquisition of the sun-synchronous orbit constellation that is not dawn and dusk but close to dawn and dusk at the local time of the descending node. For the sun-synchronous orbit constellation satellite, due to the requirement of uniform distribution of the orbital plane, the change of its orbital solar angle will be different. In some periods, the sun shines from the side of the satellite, and in some periods, the sun shines on the satellite from the front, top, and back of the satellite in the orbital plane. In more periods, the sun runs on a conical surface. Based on the characteristics of the change of its orbital solar angle, the present invention proposes a constellation satellite energy acquisition mechanism and method, which adopts two solutions of offset-mounted sail panels carrying solar cells or attitude dynamic tracking to solve the problem of stable energy acquisition of constellation energy, so that the solar cells are mounted in the orbital plane, ensuring that the angle between the normal vector of the sail panel and the sun is small, thereby obtaining a good energy supply.

[0031] The scheme of the present invention is further described below in conjunction with the accompanying drawings of the embodiments.

[0032] First, in the embodiment of the present invention, the centroid orbit coordinate system O-XYZ is used to define the relationship between various angles and vectors involved. Figure 2 The schematic diagram of the mass-centre orbital coordinate system is shown in FIG. As shown in the figure, the full name of the mass-centre orbital coordinate system O-XYZ is the Velocity Local Horizontal Coordination System, VVLH. For a satellite, the origin of its coordinate system O is at the mass-centre of the satellite body, and the definitions of the three coordinate axes are as follows:

[0033] X-axis: points to the forward direction in the orbital plane. For a satellite, its orbit is defined in the geocentric inertial system. Therefore, although the X-axis is defined as along the flight direction, it does not necessarily coincide with the satellite's flight velocity vector, but is determined by the cross product of the Y-axis and the Z-axis. The X-axis coincides with the flight velocity vector only when the satellite's orbit is a circular orbit;

[0034] Y-axis: aligned with the negative normal direction of the orbital plane; and

[0035] Z axis: the line from O to the center of mass of the earth, pointing to the direction of the center of mass of the earth;

[0036] The center-of-mass orbit coordinate system is the relative reference coordinate system for the attitude motion of the three-axis stabilized aircraft relative to the earth. When the attitude angle is zero, the body coordinate system coincides with the orbit coordinate system.

[0037] Figure 3a-3c The figure shows the relationship between the sailboard normal vector and the sun vector. Figure 3b yes Figure 3a the projection seen in the +Y direction, and Figure 3cIt is a schematic diagram of the projection of the normal vector of the windsurfing board in the YOZ plane. Figure 3b The X1O1Z1 plane in is parallel to the XOZ plane, OA is the unit solar vector, O1A is the projection of the unit solar vector on the X1O1Z1 plane, the angle between O1A and the O1X1 axis is θ, which is positive when rotated around the Y axis according to the right-hand rule; OB is the sailboard normal vector, O1B is the projection of the sailboard normal vector on the X1O1Z1 plane, the angle between the sailboard normal vector OB and the -Y axis is γ, which is positive when rotated around the X axis according to the right-hand rule. It can be seen that the cosine of the angle ∠BOA between the sailboard normal vector OB and the unit solar vector OA, cos(∠BOA), is the charging efficiency.

[0038] As mentioned above, the present invention allows the solar cells to be mounted in the orbital plane, that is, the present invention provides a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit, which mounts the solar cells on the sailboard, and at the same time allows the normal vector of the sailboard to remain in the YOZ plane of the center of mass orbit coordinate system, and form an angle γ with the -Y axis of the center of mass orbit coordinate system.

[0039] In one embodiment of the present invention, a one-dimensional offset solar array is used to achieve sun tracking. Therefore, in this embodiment, the angle γ formed by the normal vector of the sailboard and the -Y axis of the center of mass orbit coordinate system is a fixed value. The value of the angle γ can be determined according to the maximum charging efficiency mean. Figure 3a-3c As shown, the unit sun vector OA can be calculated as follows:

[0040] OA=[sin(90°-β)cosθ -cos(90°-β) sin(90°-β)sinθ]′=[cosβcosθ -sinβ cosβsinθ]′,

[0041] The sailboard normal vector OB can be calculated as:

[0042] OB=[0 -cosγ -sinγ]′,

[0043] Then the charging efficiency, i.e. the cosine of the angle ∠BOA between the normal vector OB of the sailboard and the unit sun vector OA, cos(∠BOA) is:

[0044]

[0045] Then the mean charging efficiency η can be calculated:

[0046]

[0047] Among them, θ2θ1 is the upper and lower limits of the angle between the projection O1A of the unit sun vector on the X1O1Z1 plane and the O1X1 axis. Considering that there is no light in the shadow area, the range of θ is: 16.6° to -196.6°, which is a decreasing change. Figure 6a and 6b The schematic diagrams of the change of the mean charging efficiency of a constellation satellite energy acquisition mechanism based on a non-dawn and dusk sun-synchronous orbit according to an embodiment of the present invention with the change of the normal vector of the sailboard and the -Y axis angle of the center of mass orbit coordinate system, and the change of the mean maximum charging efficiency of the constellation satellite energy acquisition mechanism with the change of the normal vector of the sailboard and the -Y axis angle of the center of mass orbit coordinate system are respectively shown. As shown in the figure, when β = 56°, γ = 19° is the maximum charging efficiency mean, and the maximum charging efficiency mean is 0.8776, and when β = 43°, γ = 29° is the maximum charging efficiency mean, and the maximum charging efficiency mean is 0.7791. It can be seen that under the premise that the sailboard is offset at a certain angle γ, as the orbital solar angle increases, the charging efficiency mean increases.

[0048] In another embodiment of the present invention, a one-dimensional dynamic tracking scheme of a solar array is adopted to realize sun tracking. In this embodiment, the sailboard dynamically deflects around the X-axis of the center of mass orbit coordinate system. Specifically, it dynamically deflects around the X-axis of the center of mass orbit coordinate system by following the projection of the sun on the YOZ plane of the center of mass orbit coordinate system.

[0049] Figure 4a-4b A schematic diagram showing a sailboard normal vector of a constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit according to an embodiment of the present invention follows the sun's deflection. Figure 4b for Figure 4a The projection viewed in the +Y direction. In this embodiment, the range of the angle γ is: [-(90°-β), (90°-β)], where β is the orbital solar angle.

[0050] like Figure 4a , 4b As shown, the unit sun vector OA is calculated as follows:

[0051] OA=[cosβcosθ-sinβ cosβsinθ]′,

[0052] The projection vector O1B of the windsurfing board normal vector OB on the X1O1Z1 plane is:

[0053] O1B=[0 0 cosβsinθ]′,

[0054] OO1=[0 -sinβ 0]′,

[0055] Therefore, the windsurfing board normal vector OB is calculated as:

[0056] OB=OO1+O1B=[0 -sinβ cosβsinθ]′

[0057] Then the charging efficiency, i.e. the cosine of the angle ∠BOA between the normal vector OB of the sailboard and the unit sun vector OA, cos(∠BOA) is:

[0058]

[0059] From this, the average efficiency of the solar panel can be obtained as:

[0060]

[0061] Figure 7a , 7b The schematic diagrams respectively show the change of the mean charging efficiency of a constellation satellite energy acquisition mechanism based on a non-dawn and dusk sun-synchronous orbit according to an embodiment of the present invention with the angle between the projection of the unit sun vector on the X1O1Z1 plane and the O1X1 axis, and the change of the mean maximum charging efficiency with the orbital sun angle. As shown in the figure, when β = 43°, the minimum mean charging efficiency is 0.8243, and when β = 56°, the maximum mean charging efficiency is 0.9037.

[0062] Table 1 shows the comparison of the average and maximum charging efficiency of the three schemes of non-deflection of the solar panel and one-dimensional deflection and one-dimensional dynamic tracking:

[0063]

[0064] Table 1

[0065] As shown in Table 1, the average charging efficiency is the highest in the one-dimensional dynamic tracking scheme, which is 20.9% higher at β = 43° and 9.0% higher at β = 56° than the non-deflection scheme. The efficiency average of the one-dimensional biased mounting scheme is also improved compared with the non-deflection scheme. Specifically, it is 14.2% higher at β = 43° and 5.9% higher at β = 56° than the non-deflection scheme. Compared with the non-deflection scheme, the efficiency average of the one-dimensional dynamic tracking scheme is 6.7% higher at β = 43° and 3.1% higher at β = 56° than the one-dimensional biased mounting scheme. However, the one-dimensional dynamic tracking scheme needs to keep rolling and maneuvering to follow the sun, which puts a lot of pressure on the attitude control system. Therefore, the one-dimensional dynamic tracking scheme or the one-dimensional biased mounting scheme can be selected according to actual needs.

[0066] Figure 5 A schematic flow chart of a method for acquiring energy from a constellation satellite based on a non-dawn-dusk sun-synchronous orbit according to an embodiment of the present invention is shown. Figure 5 As shown, a method for acquiring energy from a constellation satellite based on a non-dawn-dusk sun-synchronous orbit comprises:

[0067] First, in step 501, the offset angle is determined. According to the orbital solar angle and the average value of the maximum charging efficiency, the angle γ between the sailboard and the -Y axis of the center of mass orbital coordinate system is determined;

[0068] Next, in step 502, the sailboard is installed. The solar cell sheet is mounted on the sailboard, and the normal vector of the sailboard is kept in the YOZ plane of the mass orbit coordinate system, and forms an angle γ with the -Y axis of the mass orbit coordinate system; and

[0069] Finally, in step 503, the sailboard is controlled to follow the projection of the sun on the YOZ plane of the barycenter orbit coordinate system and dynamically deflect around the X-axis of the barycenter orbit coordinate system to reduce the angle between the normal vector of the sailboard and the sun vector.

[0070] Although various embodiments of the present invention are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the attached claims and their equivalents.

Claims

1. A constellation satellite energy acquisition mechanism based on a non-dawn-dusk sun-synchronous orbit, characterized in that: The invention comprises a sailboard, on which a solar cell sheet is mounted, and a normal vector of the sailboard is maintained in the YOZ plane of the center of mass orbit coordinate system, and forms an angle with the -Y axis of the center of mass orbit coordinate system, and the sailboard is dynamically deflected around the X axis of the center of mass orbit coordinate system.

2. The constellation satellite energy acquisition mechanism as claimed in claim 1, characterized in that: The angle is a fixed value.

3. The constellation satellite energy acquisition mechanism according to claim 1, characterized in that: The value of the angle is determined according to the maximum charging efficiency mean.

4. The constellation satellite energy acquisition mechanism according to claim 1, characterized in that: The sailboard follows the projection of the sun vector on the YOZ plane of the barycenter orbital coordinate system and dynamically deflects around the X-axis of the barycenter orbital coordinate system.

5. The constellation satellite energy acquisition mechanism as claimed in claim 1, characterized in that: The range of variation of the angle is: [-(90°-β), (90°-β)], where β is the orbital solar angle.

6. A method for obtaining energy from a constellation satellite based on a non-dawn-dusk sun-synchronous orbit, characterized in that: Includes steps: Mounting the solar cell sheet to the sailboard, wherein the normal vector of the sailboard is maintained in the YOZ plane of the mass-centre orbital coordinate system and forms an angle with the -Y axis of the mass-centre orbital coordinate system; and The sailboard is controlled to follow the projection of the sun on the YOZ plane of the barycenter orbit coordinate system and dynamically deflect around the X-axis of the barycenter orbit coordinate system to reduce the angle between the normal vector of the sailboard and the sun vector.

7. The constellation satellite energy acquisition method according to claim 6, characterized in that: The value of the angle is determined according to the maximum charging efficiency mean.

8. A constellation satellite in a non-dawn-dusk sun-synchronous orbit, characterized in that: It comprises a constellation satellite energy acquisition mechanism as described in any one of claims 1 to 5.

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