Artificial satellite and artificial satellite system

Abstract

To provide an artificial satellite and an artificial satellite system capable of improving power transmission / reception efficiency.SOLUTION: This artificial satellite comprises: an expansion-type solar panel that receives sunlight to generate power; a plurality of expansion-type power transmission antennas for transmitting the generated power to a power reception facility; and a plurality of expansion-type beam members that connect the expansion-type solar panel and the expansion-type power transmission antennas. The expansion-type beam members expanded from the state of being installed in the artificial satellite are arranged around a plurality of rotation symmetry axes of a virtual polyhedron composed with the rough center of the artificial satellite set as an original point at roughly equal distances in the rotation symmetry axes.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an artificial satellite and an artificial satellite system for constituting a space solar power generation and transmission system, and more particularly to an artificial satellite and an artificial satellite system having a three-dimensional structure suitable for light reception / power reception and power transmission. [Background technology]

[0002] In a Space Solar Power System (SSPS), energy generated by solar cells installed in geostationary orbit is transmitted to the ground via microwaves.

[0003] Currently, there are limited places to install structures, including artificial satellites, in geostationary orbit, and various countries are considering using orbits other than geostationary orbit. In particular, low orbit (2000 km or less above the ground) has been reported to have advantages in terms of launch costs. However, when using low orbit, there is a possibility that the efficiency of receiving or transmitting electricity will decrease with the conventional panel method.

[0004] In this regard, Patent Document 1, with the aim of providing a lightweight panel structure capable of maintaining a high degree of flatness for each panel, proposes that "the panel structure 1 comprises a panel array 10 having a plurality of triangular panels 11, a frame 20 to which the three corners of the panel 11 are fixed while tension is applied to the panel 11 in a direction expanding the spacing between the three corners of the panel 11, and a tension adjustment section 30 that adjusts the tension applied to the panel 11." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-95063 A Summary of the Invention [Problem to be solved by the invention]

[0006] When deploying a space solar power generation and transmission system in space, it is important to keep the large-area solar panels always pointed toward the sun in order to maintain a large overall power transmission capacity. For example, in the case of a low-earth orbit, it takes 1.5 to 2 hours to orbit the Earth, so the power receiving time at fixed power receiving equipment on the ground is only a few minutes to around 15 minutes.

[0007] In this regard, in the planar structure described in Patent Document 1, it is difficult to maximize both the amount of power received and the amount of power transmitted due to the positional relationship between the satellite, which is the space solar power generation and transmission system, the sun, and the power receiving equipment, and the overall efficiency of power reception and transmission decreases, which is an issue. For example, it is difficult to constantly point the satellite toward the sun, so it is difficult to constantly maximize the amount of power generated.

[0008] In view of the above, an object of the present invention is to provide an artificial satellite and an artificial satellite system that can improve the efficiency of power transmission and reception. [Means for solving the problem]

[0009] In view of the above, the present invention provides an artificial satellite for use in space solar power generation and transmission, the artificial satellite comprising: a deployable solar panel that receives sunlight and generates power; a plurality of deployable power transmission antennas that transmit the power generated by the deployable solar panel to a power receiving facility; and a plurality of deployable beam members that connect the deployable solar panel and the plurality of deployable power transmission antennas, the plurality of deployable beam members being deployed from a state in which they are provided on the artificial satellite; the beam members being arranged at approximately equal distances in the direction of a plurality of rotational symmetry axes of a virtual polyhedron formed with approximately the center of the artificial satellite as the origin; at least one of the light receiving surfaces of the deployable solar panel and at least one of the installation surfaces of the plurality of deployable power transmission antennas being approximately perpendicular to the solar panel rotational symmetry axis, which is the rotational symmetry axis that passes approximately the center of the deployable solar panel, when deployed from the artificial satellite, and being arranged on either side of a plane that passes approximately the center; and the installation surfaces of the plurality of deployable power transmission antennas being each facing in a different direction when deployed from the artificial satellite.

[0010] In addition, the present invention defines the satellite system as "a satellite system formed by flying multiple satellites, the multiple satellites transmitting power to the same power receiving equipment." Effect of the Invention

[0011] According to the present invention, each component has a symmetrical structure, which makes it easy to deploy in space, and the power transmission antennas face in different directions, which makes it possible to improve the efficiency of power transmission and reception. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of a basic configuration of an artificial satellite according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a view of the artificial satellite 10 in FIG. 1 from direction A. [Diagram 3] 2 is a diagram showing an example of the cross-sectional structure of a thin film 8A on which a solar cell panel 3 is installed and a thin film 8B on which a power transmission antenna 5 is installed. FIG. [Figure 4] FIG. 2 shows an example in which the artificial satellite 10 is a tetrahedron. [Diagram 5] FIG. 2 shows an example in which the artificial satellite 10 is an octahedron. [Figure 6] FIG. 13 is a diagram showing the configuration during simulation of the panel system. [Figure 7] FIG. 2 is a diagram showing a configuration during a simulation of the present invention. [Figure 8] FIG. 13 shows the simulation results of the panel method. [Figure 9] FIG. 13 is a diagram showing a simulation result of the present invention. [Figure 10] FIG. 13 is a diagram showing the results of a comparison between the panel method and the present invention. [Figure 11A] FIG. 4 is a diagram for explaining the C3 rotation axis. [Figure 11B] FIG. 13 is a diagram for explaining a C4 rotation axis. [Figure 11C] FIG. 4 is a diagram for explaining the C2 rotation axis. [Figure 12]FIG. 1 is a diagram showing an example of the configuration of an artificial satellite system 20 in which a plurality of artificial satellites 10 are orbited. [Figure 13] A diagram showing an example of deformation of the thin film portion in addition to formation. [Figure 14] FIG. 1 illustrates operation to multiple terrestrial receiving points. [Figure 15] FIG. 13 shows an example in which a portion of the thin film 8 is thin film 8C in which a solar panel and a power transmission antenna are installed on the same surface, and a further portion is thin film 8D in which a solar panel is installed on one surface and a power transmission antenna on the opposite surface. [Figure 16] FIG. 13 shows an example of the configuration of a thin film 8C in which a solar panel 3 and a power transmission antenna 5 are installed on the same surface. [Figure 17] FIG. 13 shows an example of the configuration of a thin film 8D having a solar panel 3 on one side and a power transmission antenna 5 on the other side. [Figure 18] A diagram showing an example of a configuration in which a solar panel and a power transmission antenna are mounted on the same thin-film surface for omnidirectional wireless power transmission. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] In addition, Example 1 explains the application of a tensegrity structure to space solar power generation and transmission, Example 2 explains increasing the capacity of space solar power generation by forming a satellite system using multiple satellites, Example 3 explains operation at multiple terrestrial receiving points and multiple receiving points other than on the ground, Example 4 explains a thin film in which a solar panel and a power transmission antenna are installed on the same plane, and Example 5 explains the use of a rectenna as a power conversion device. EXAMPLES

[0015] In the first embodiment, the application of a tensegrity structure to space solar power generation and transmission will be described with reference to Figs. 1 to 11 (Figs. 11A, 11B, and 11C).

[0016] 1 shows an example of a basic configuration of a satellite according to the first embodiment of the present invention. The satellite 10 used for space solar power generation and transmission according to the first embodiment of the present invention includes, as main components, a housing 7 for housing a control device and the like, a solar panel 3 that is deployed around the housing 7 and receives sunlight on its light receiving surface 4 to generate electricity, a plurality of deployable power transmission antennas 5 that transmit the electricity generated by the deployable solar panel 3 to a power receiving facility on the ground or the like, a plurality of deployable beam members 2 that connect the deployable solar panel 3 to the plurality of deployable power transmission antennas 5, a tension member 1 that connects the end points of the beam members 2, and a thin film 8 installed in an area surrounded by the tension member 1.

[0017] Among these, the multiple deployable beam members 2 are deployed from a state in which they are attached to the housing 7 of the satellite 10, and are arranged at approximately equal distances in the direction of multiple rotational symmetry axes 13 of a virtual polyhedron formed with approximately the center 11 of the satellite 10 as the origin.

[0018] When deployed from a state stored in the housing 7, the light receiving surface 4 of the deployable solar panel and the installation surface 6 of the multiple deployable power transmission antennas are approximately perpendicular to the solar panel axis of rotational symmetry 9, which is the axis of rotational symmetry 13 that passes approximately through the center of the deployable solar panel 3, and are arranged on either side of a plane that passes approximately through the center 11.

[0019] The installation surfaces 6 of the multiple deployable power transmitting antennas 5 face different directions (directions 12A, 12B, 12C of the installation surfaces of the power transmitting antennas) when deployed from the artificial satellite 10. The power transmitting antenna 5 may be, for example, a patch antenna array.

[0020] Fig. 2 shows the satellite 10 of Fig. 1 as seen from the direction A. A thin film 8 is installed in a region surrounded by three tension members 1 that connect the vertices of three beam members 2 to each other.

[0021] Fig. 3 is a diagram showing an example of the cross-sectional structure of a thin film 8A on which a solar cell panel 3 is installed or a thin film 8B on which a power transmission antenna is installed. In the thin film 8A on which a solar cell panel 3 is installed shown in the upper part of Fig. 3, the thin film 8A is installed as a lining toward the inside of the satellite (the housing 7 side), and the solar panel 3 and the solar panel light receiving surface 4 are installed on the outside of the satellite. In the thin film 8B on which a power transmission antenna 5 is installed shown in the lower part of Fig. 3, a power transmission antenna installation surface 6 and the power transmission antenna 5 are installed.

[0022] In the example of the artificial satellite shown in Figures 1 to 3, one solar panel 3 and four power transmission antennas 5 are arranged, but a configuration with four solar panels 3 and four power transmission antennas 5 is also possible. By deploying the solar panels 3 over a range of more than half or more than a hemisphere, it is expected that power can be generated for a long time even in low orbit. In addition, by deploying the power transmission antennas 5 over a range of more than a hemisphere, it is expected that power can be transmitted over a wide area for a long time even in low orbit.

[0023] In order to realize the configuration of Fig. 1, it is advisable to use, for example, a tensegrity structure as a structure that stably maintains the positional relationship between the tension member 1 and the beam member 2. The tensegrity structure is a coined word combining tension and integrity, and is known as a lightweight and shape-stable structure that is configured by self-balancing the tension of tension members (or chords, cables) and the compression force of compression members (or rods). In this embodiment, a configuration in which eight faces of an icosahedron consisting of 12 vertices are used as thin films has been described, but it can also be implemented with other polyhedrons.

[0024] Fig. 4 shows an example where the artificial satellite 10 is a tetrahedron, and Fig. 5 shows an example where the artificial satellite 10 is an octahedron. In either configuration, four or eight triangular thin films 8 surrounded only by the tension members 1 can be arranged, and these surfaces can be used as thin films 8A for mounting the solar cell panels 3 or thin films 8B for mounting the power transmission antennas.

[0025] Next, a simulation and the results of the simulation will be described regarding the improvement of the efficiency of power transmission and reception by the artificial satellite 10 having the configuration described in FIG. 1 to FIG.

[0026] Fig. 6 shows a configuration diagram during a simulation of the panel method. In Fig. 6, a solar panel 3 is installed on the sun side, and a power transmission antenna 5 is installed on the back side. Fig. 7 shows a configuration diagram during a simulation of the present invention. A thin film 8B for installing four power transmission antennas 5 is arranged in a different direction from the thin film 8A for installing the solar panel 3. In Fig. 7, of the thin films 8B for installing the power transmission antennas 3, the front side of one is visible, and the back side of the thin film 8B is visible for the other three.

[0027] In the simulation, the total power received by the present invention and the panel method in a space solar power system (SSPS) was compared. A low earth orbit (NOAA weather satellite) was selected as the orbit. The access time (the time spent transmitting and receiving power out of the path time [time visible from the ground station]) was assumed to be that of NOAA No. 1. The solar panel area was set to one surface of the same size under the two conditions, and the satellite's attitude was controlled to point the solar panel receiving surface toward the sun. For the panel method, the transmitting antenna was a one-surface array antenna (1m 2 ) and transmit power to the Earth from the back side of the sun-pointing attitude. In the present invention, the four-surface array antenna is switched to use the side that is most earth-pointing. (Each is 1m 2 The transmission frequency is set to 2.45GHz, and the receiving site is assumed to be near Tokyo Bay.

[0028] Figure 8 shows the simulation results for the panel method. The horizontal axis shows time, and the vertical axis shows the amount of power received. The reason why the time during which power can be received (1:50-2:02) is shorter than the visibility time (1:38-2:02) is that there are times when power cannot be transmitted due to the angle of the power transmitting antenna installation surface 6 relative to the ground power receiving site.

[0029] FIG. 9 shows the simulation results of the present invention. As in FIG. 8, the horizontal axis shows time and the vertical axis shows the amount of power received. In the present invention, light can be received on four surfaces (21A-21D), and FIG. 9 shows the amount of power received on the four surfaces 21A-21D. In this example, for the same visibility time (1:38-2:02) as in FIG. 8, the light receiving surfaces 21C and 21D can receive power almost throughout the entire period, and the amount of power received is larger than that in FIG. 8. The power received on the light receiving surface 21A is the same as in FIG. 8, and the power received on the light receiving surface 21B is about the same as that of 21A in the first half of the visibility time. The reason why the time during which power can be received by 21A and 21B (1:38-1:50, 1:50-2:02, respectively) is short is that there are times when power cannot be transmitted due to the angle of the power transmitting antenna installation surface 6 relative to the ground power receiving site. The visibility time here may be defined as the time period during which the elevation angle looking up at the satellite 10 from a ground station or a ground receiving site is equal to or greater than a predetermined value, or may be defined as the time period during which communication is possible.

[0030] Fig. 10 is a diagram showing the results of a comparison between the panel method and the present invention. Fig. 10 shows the ratio of the amount of power received in a day when the panel method is set to 1, the ratio of power receiving time to visible time (pass time), and the ratio of the total power receiving time when the panel method is set to 1, all of which were obtained through a simulation.

[0031] According to this comparison, the present invention allows the use of various faces by switching between them, resulting in a daily average power reception per face (under the same conditions of area) of 1.1 times. In other words, in the simulation, four faces of the power transmitting antenna 5 were used, but a 4.4-fold power reception was obtained, indicating that the power reception per unit area of ​​the power transmitting antenna was increased. In addition, the power reception time was also 3.13 times longer, which is considered to be one of the factors that increased the power reception.

[0032] Next, consider the axis of rotational symmetry 13 for the cube assumed to be the shape of the housing 7. The axis of rotational symmetry 13 passes through the center of the cube. The types of axes of rotational symmetry that can be taken include the C2 rotational axis (13C2), the C3 rotational axis (13C3), and the C4 rotational axis (13C4).

[0033] As shown in FIG. 11C, the C2 rotation axis is a 360° / 2=180° rotation, which is a rotational symmetry axis that makes the cube have the same shape, and passes through the midpoints of the opposing sides. There are six types of rotational symmetry axes.

[0034] As shown in FIG. 11B, the C3 rotation axis is a rotationally symmetric axis that causes a cube to have the same shape when rotated 360 degrees / 3=120 degrees. It is a rotationally symmetric axis that passes through opposing vertices and can be of four types.

[0035] As shown in FIG. 11A, the C4 rotation axis is a rotationally symmetric axis along which a cube has the same shape when rotated 360 degrees / 4=90 degrees. It is a rotationally symmetric axis that passes through the centers of opposing faces and can be of three types.

[0036] In the above embodiment 1, the application of a three-dimensional structure such as a tensegrity structure to space solar power generation has been described. In embodiment 1, a three-dimensional structure such as a tensegrity structure is applied as a space power receiving / transmitting satellite for space solar power generation, which has one or more solar panels and one or more antenna surfaces for power transmission, and transmits power to a power receiving facility on the ground. For example, in the case of a tensegrity structure having eight surfaces, it can be implemented by a combination of one solar panel surface and seven power transmission antenna surfaces, or a combination of four solar panels and four power transmission antenna surfaces. The arrangement method of the solar panel 3 and the power transmission antenna 5 described in embodiment 1 is not limited to the tensegrity structure, and may be realized by an expandable truss structure or the like.

[0037] In the above-described first embodiment, each component has a symmetrical structure, which makes it easy to deploy in space, and the power transmission antennas face in different directions, which makes it possible to improve the efficiency of power transmission and reception. EXAMPLES

[0038] In the second embodiment, an attempt to increase the capacity of space solar power generation by using a plurality of artificial satellites will be described with reference to Figs.

[0039] Here, a satellite system is formed by flying multiple satellites, and the capacity of space solar power generation is increased. The capacity of the space solar power generation satellite system is increased by expanding the area of ​​the solar panel 3 and the power transmission antenna 5.

[0040] 12 shows an example of the configuration of a satellite system 20 in which multiple satellites 10 are flying. By forming the satellites 10 into a formation, the total area of ​​the solar panels 3 can be increased, and each satellite 10 can transmit microwaves 23 to a power receiving facility 22 on the ground, thereby increasing the capacity of the space solar power generation satellite.

[0041] FIG. 13 shows an example in which the thin film portion is deformed in addition to the formation. A tension controller 25 for the tension member 1 is provided to control the tension of the tension member 1. A structure controller 26 for the beam member 2 is also provided to control the contraction of the beam member 2. In FIG. 13, only a part of the tension controller 25 for the tension member 1 and the structure controller 26 for the beam member 2 are shown. By lengthening the length of some of the beam members 2 and shortening the length of some of the beam members 2, the attitude of each thin film 8 with respect to the housing 7 can be changed. In this way, the thin film 8 can be used as a posture-changeable thin film 24. By installing the solar panel 3 and the power transmission antenna 5 on the posture-changeable thin film 24, their directional angles can be changed.

[0042] For example, by controlling the expansion and contraction and deformation of the beam member 2 and the tension of the tension member 1, it becomes possible to arrange all the membranes 8 on substantially the same plane and change the membrane attitude of each satellite 10 over time. This makes it possible to temporarily increase the power generation efficiency or the power transmission efficiency, and is expected to improve the overall power transmission efficiency. Also, the change in the membrane attitude shown in FIG. 13 can be performed for each satellite 10 without forming a formation.

[0043] In this way, in the second embodiment, the capacity of space solar power generation is increased by using multiple satellites, and by flying multiple satellites, the capacity of space solar power generation can be increased. EXAMPLES

[0044] In the third embodiment, power transmission and operation to a plurality of receiving points will be described with reference to FIG.

[0045] In Fig. 14, the satellite 10 rotates around the center of the solar panel 3 as an axis, thereby increasing the selection of receiving points and accurately transmitting power. In addition, multiple power transmitting antennas 5 transmit microwaves 23 toward different power receiving equipment. This makes it possible to transmit power to power receiving equipment distributed over a wide area. Power receiving equipment can include mobile objects such as satellites and aircraft, as well as those installed on the ground. EXAMPLES

[0046] In the fourth embodiment, a solar panel and a power transmission antenna are provided on the same surface as a thin film, which will be described with reference to Figs. 15 to 17.

[0047] Figure 15 shows an example in which a portion of the thin films 8 installed on the artificial satellite 10 is a thin film 8C in which a solar panel and a power transmission antenna are installed on the same surface, and another portion is a thin film 8D in which a solar panel is installed on one surface and a power transmission antenna is installed on the opposite surface.

[0048] Fig. 16 shows a configuration example of a thin film 8C in which a solar panel 3 and a power transmission antenna 5 are installed on the same surface. Fig. 17 shows a configuration example of a thin film 8D in which a solar panel 3 is installed on one surface and a power transmission antenna 5 is installed on the opposite surface.

[0049] This configuration can increase the number of power generation directions and power transmission directions. This configuration also makes it possible to increase the power generation time and power transmission time even in low orbit. The configurations in Figs. 16 and 17 may be implemented regardless of the area ratio between the power transmission antenna 5 and the solar panel 3, since they may be implemented in cases where a power transmission antenna 5 is additionally provided on a plane originally intended for installation of a solar panel 3, or in cases where a solar panel 3 is additionally provided on a plane originally intended for installation of a power transmission antenna 5. EXAMPLES

[0050] In the fifth embodiment, we will explain omnidirectional wireless power transmission by mounting a solar panel and a power transmission antenna on the same thin film surface, using Fig. 18. This enables omnidirectional wireless power transmission, and allows constant power generation and transmission even in low earth orbit.

[0051] FIG. 18 shows a configuration in which the satellite 10 further includes a rectenna 24 as a power conversion device. Rectenna is an abbreviation for rectifying antenna, and is an antenna and circuit that rectifies and converts microwave power 23 into direct current. By further including the rectenna 24, the satellite 10 is able to receive power transmitted by other satellites 10. This allows the satellites 10 to fly in formation and exchange power with each other. Furthermore, even when the satellite 10 is not illuminated by sunlight and cannot generate power using the solar panels 3, it is possible for the satellite 10 to receive power from other satellites 10.

[0052] In the sixth embodiment, the power transmitting antenna 5 and rectenna 24 are mounted to enable power transfer between satellites, and the satellite 10 is provided with one or more power transmitting array patch antennas and one or more rectenna arrays. Since power can be exchanged, it becomes possible to supply power via the satellite 10 to another satellite 10 that is not illuminated by sunlight. [Explanation of symbols]

[0053] 1: Tensile member 2: Beam member 3: Solar panels 4: Solar panel receiving surface 5: Power transmission antenna 6: Power transmission antenna installation surface 7: Housing 8: Thin film 9: Solar panel rotational symmetry axis 10:Artificial satellite 11:About center 12A, 12B, 12C: Direction of the installation surface of the power transmitting antenna 13: Axis of rotational symmetry of a polyhedron 8A: Thin film for mounting solar panels 8B: Thin film for installing the power transmission antenna 8C: Thin film for mounting solar panels and power transmission antennas on the same surface 8D: A thin film with a solar panel on one side and a power transmission antenna on the other side 23: Microwave 24: Rectenna

Claims

1. An artificial satellite used for space solar power generation and transmission, the satellite includes a deployable solar panel that receives sunlight and generates power, a plurality of deployable power transmission antennas that transmit the power generated by the deployable solar panel to a power receiving facility, and a plurality of deployable beam members that connect the deployable solar panel and the plurality of deployable power transmission antennas, The plurality of deployable beam members are deployed from a state in which they are mounted on the satellite, and are arranged at substantially equal distances in a direction of a plurality of rotationally symmetric axes of a virtual polyhedron formed with an origin substantially at the center of the satellite; at least one of the light receiving surfaces of the deployable solar panel and at least one of the installation surfaces of the plurality of deployable power transmitting antennas are approximately perpendicular to a solar panel axis of rotational symmetry that passes through an approximate center of the deployable solar panel when deployed from the satellite, and are disposed on either side of a plane that passes through the approximate center; The installation surfaces of the plurality of deployable power transmission antennas are each oriented in a different direction when deployed from the satellite.

2. 2. The satellite according to claim 1, A satellite having a rotation control unit that controls the rotation of the satellite, and transmits power to the power receiving facility while rotating.

3. 13. A satellite system comprising a plurality of satellites according to claim 1 in flight, the plurality of satellites transmitting power to the same power receiving facility.

4. 2. The satellite according to claim 1, An artificial satellite characterized in that the artificial satellite is rotated around an axis at the center of a solar panel, thereby selectively transmitting power to a predetermined one of a plurality of predetermined power receiving facilities.

5. 2. The satellite according to claim 1, The satellite, wherein each of the plurality of deployable power transmitting antennas transmits power to a plurality of power receiving devices each installed in a different direction.

6. 2. The satellite according to claim 1, A satellite comprising a power transmission antenna on the same installation surface as said deployable solar panel of said satellite.

7. 2. The satellite according to claim 1, 2. The satellite according to claim 1, further comprising a solar panel on the same installation surface as said deployable power transmission antenna of said satellite.

8. 2. The satellite according to claim 1, An artificial satellite comprising a power conversion device.

9. 2. The satellite according to claim 1, An artificial satellite comprising a tension controller for a tension member and a structural controller for a beam member, and configured to change the attitude of said solar panel and said power transmission antenna.

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