Three-reflection type space solar concentrator for supplying energy to dark area of moon night

Abstract

The invention provides a three-reflection type space solar concentrator for energy supply in a dark area of the moon night, and belongs to the technical field of moon energy supply. The problems that an existing condenser cannot effectively solve the problems that focal spot energy distribution is not uniform and the center is blocked due to spherical aberration, and a composite axis light beam tracking technology is lacked are solved. The device comprises a coaxial condenser, a parallel light conversion mirror, a fast reflecting mirror and a double-shaft tracker, the parallel light conversion mirror is installed above the coaxial condenser, the fast reflecting mirror is installed below the coaxial condenser, and the coaxial condenser is installed on the double-shaft tracker. The device is mainly used for moon energy supply.

Description

Technical Field

[0001] The invention belongs to the technical field of lunar energy supply, and in particular relates to a three-reflection space solar energy concentrator used for supplying energy in dark areas on moonlit nights. Background Art

[0002] The working principle of the parabolic dish concentrator system is to achieve solar orientation through a heliostat tracking device, and use a parabolic reflector to concentrate sunlight onto the absorber, which performs photothermal conversion or photoelectric conversion to drive the generator. The system is usually composed of a photoelectric photothermal conversion device, a concentrator, a supporting structure, a reflector, a column and a heliostat tracking device. Compared with the traditional trough concentrator, the parabolic dish concentrator has the advantages of compact structure, small footprint and high concentration ratio [7-9]. In order to further improve the concentration ratio and change the requirements of the optical path, it is possible to consider adding a secondary reflector to improve the focusing degree of the optical path. At present, the use of secondary reflectors has been relatively widespread. For example, Alex Goldstein has realized a comprehensive analysis of the parameter space of the dual-mirror system, and found the optimal position of the absorber with high-precision optical sensitivity, thereby achieving an improvement in the concentration ratio. Gong JH proposed a new secondary reflector design method. Through the adaptive optimization method, part of the light reflected by the primary mirror that is not absorbed is reflected back to the absorber, further improving the PTC light efficiency and thermal efficiency, and realizing the uniform distribution of energy flow on the absorber surface. The secondary reflector with the same focal diameter ratio is installed at the linear focusing position of the trough concentrator. The optical enhancement effect of the device in different seasons of the year is measured. It is found that the enhancement effect is more obvious in winter, but the irradiation in all months is similar. At present, most of the secondary reflectors are used in trough and dish coaxial concentrators, and are installed at the focusing position directly above the primary mirror, and the absorber is usually fixed in front of the absorber, which will block the primary mirror. In addition, the distance between the absorber and the secondary reflector is too close, which will also reduce the thermal efficiency. Therefore, there is an increasing need to develop innovative design methods to help solve these problems and form a more cost-effective and efficient solar energy utilization plan.

[0003] Mobile target tracking technology is the core technology of this research. The high-intensity light reflected by the concentrator is very destructive to the environmental resources in the shadow area of ​​the moon. In order to accurately project the reflected light beam to the lunar exploration facilities operating in the kilometer-level deep pit without damaging the local environmental resources, the ordinary two-axis beam pointing device cannot meet the mission accuracy requirements. Therefore, the system plans to use a fast-control reflector to achieve accurate tracking of the reflected light beam on the moving target. The fast-control reflector is referred to as a fast-reflector. It is a servo control device that can quickly and accurately adjust the direction of the light beam. The device has excellent characteristics such as fast response speed and strong anti-interference ability. It has been widely used in optoelectronic tracking and aiming systems. Considering the fast-reflector The effective control stroke is short, usually not exceeding. If the mission target needs to move over a large range, a two-axis turntable system that can turn at a large angle is also required as a coarse tracking device for beam pointing to form a composite axis tracking system. A new integrated design method for aiming system is proposed in the prior art, and the coarse and fine two-level subsystems are designed as a whole. The simulation results show that the design is far superior to the traditional control method in terms of tracking accuracy, anti-interference ability and control input peak value. Zhou JP introduced a normalized LMS algorithm to compensate for the position loop delay of the two-axis system, and used a fast reflection mirror to improve the high-line-of-sight pointing accuracy of the optoelectronic pod, which increased the azimuth and beam control accuracy by 15 times and 3 times respectively. Wu ZL integrates a large-stroke, large-aperture two-axis mirror for coarse tracking and a piezoelectric fast-reflection mirror for fine tracking adjustment. The neural network fitting method is used to analyze the coupling relationship between the mechanical motion stroke of the mirror and the optical angle change, and the scanning detection and image compensation technology are used to enhance the field of view of the system. At present, most of the research on compound-axis optoelectronic tracking systems is based on the improvement of the control system algorithm model. The coupled dynamics model of the compound-axis control system has not yet been established with a complete mathematical expression, which still leads to limitations in the optimization process of the control system. Summary of the invention

[0004] In view of this, the present invention aims to propose a three-reflection space solar concentrator for providing energy in dark areas on moonlit nights, so as to solve the problems that existing concentrators cannot effectively solve the uneven focal spot energy distribution and central occlusion caused by spherical aberration, and lack of composite axis beam tracking technology.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A three-reflection space solar concentrator for providing energy in dark areas on moonlit nights, characterized in that it includes a coaxial concentrator, a parallel light conversion mirror, a fast reflection mirror and a dual-axis tracker, the parallel light conversion mirror is installed above the coaxial concentrator, the fast reflection mirror is installed below the coaxial concentrator, and the coaxial concentrator is installed on the dual-axis tracker.

[0007] Furthermore, the dual-axis tracker is mounted on a connecting bracket.

[0008] Furthermore, the coaxial concentrator is made of carbon fiber composite material, has a focal length of 400m, and is coated with a high reflectivity film layer on the surface.

[0009] Furthermore, the fast reflection mirror is driven by piezoelectric ceramics, with a deflection accuracy of ±0.001° and a response time of ≤10ms.

[0010] Furthermore, the parallel light conversion mirror adopts a hyperbolic design.

[0011] Furthermore, the fast reflection mirror and the dual-axis tracker form a composite axis control system with a control accuracy of ≤0.005°.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The present invention significantly improves the focusing efficiency and energy transmission accuracy through a three-level reflection structure of a coaxial condenser, a parallel light conversion mirror and a fast reflection mirror, combined with spherical aberration optimization and composite axis tracking technology.

[0014] 2. After optimization, the effective energy ratio of the present invention is increased from 5% to 15%, and the focal spot uniformity is improved by 40%.

[0015] 3. The composite axis control system of the present invention can still maintain stable tracking in the extreme environment of the lunar surface.

[0016] 4. The present invention is applicable to complex terrain scenes such as permanent shadow areas on the moon and deep crater detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 The schematic diagram of the structure of a three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to the present invention Figure 1 ;

[0019] Figure 2 The schematic diagram of the structure of a three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to the present invention Figure 2 ;

[0020] Figure 3 is a schematic diagram of two reflected light trajectories;

[0021] Figure 4 is the focus spot irradiance cloud map of the two reflected light paths;

[0022] Figure 5 Schematic diagram of irradiance distribution on the receiving surface of two reflected light paths;

[0023] Figure 6 It is the light trajectory diagram of three reflected light paths;

[0024] Figure 7 It is the focus spot irradiance cloud map of three reflection light paths;

[0025] Figure 8 Schematic diagram of irradiance distribution on the receiving surface of three reflection light paths;

[0026] Fig. 9 Power calibration cloud map for actual solar irradiance;

[0027] Fig.10 This is the focal spot irradiance cloud map of the optical path after spherical aberration optimization;

[0028] Fig.11 Schematic diagram of irradiance distribution on the receiving surface after spherical aberration optimization;

[0029] Fig.12 This is a schematic diagram of the light trail simulation process;

[0030] Fig.13 To optimize the trajectory distribution change curve of the front and rear receiving surfaces;

[0031] Fig.14 The effect of secondary mirror shielding on ordinary coaxial condenser, and the irradiance cloud map after parallel light optimization;

[0032] Fig.15 Schematic diagram of the trajectory distribution effect after optimizing the surface shape of the coaxial condenser, and the irradiation cloud map after parallel light conversion.

[0033] In the figure:

[0034] 1- coaxial condenser, 2- parallel light conversion mirror, 3- fast emission mirror, 4- dual-axis tracker, 5- connecting bracket. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0036] Specific implementation 1: See Figure 1-2The present embodiment is described as a three-reflection space solar energy concentrator for providing energy in dark areas on moonlit nights, comprising a coaxial concentrator (1), a parallel light conversion mirror (2), a fast reflection mirror (3) and a dual-axis tracker (4), wherein the parallel light conversion mirror (2) is mounted above the coaxial concentrator (1), the fast reflection mirror (3) is mounted below the coaxial concentrator (1), the coaxial concentrator (1) is mounted on the dual-axis tracker (4), and the dual-axis tracker (4) is mounted on a connecting bracket (5).

[0037] The dual-axis tracker 4 drives the coaxial concentrator (1) to orient toward the sun, and the fast reflector 3 adjusts its direction according to the position of the concentrator and the position of the detection device on the lunar surface. The coaxial concentrator (1) converges the sunlight onto the surface of the parallel light conversion mirror (2) and optimizes the central occlusion. The parallel light conversion mirror (2) converts the converged sunlight into parallel light and compensates for the aberration generated by the coaxial concentrator (1). The fast reflector 3 adjusts its direction according to the position of the concentrator and the position of the lunar detection device and transmits the light energy to the solar receiving panel or other target position of the detection device, thereby solving the problems that the existing concentrator cannot effectively solve the uneven distribution of focal spot energy and central occlusion caused by spherical aberration and lacks composite axis beam tracking technology.

[0038] Specific implementation method 2: See Figure 3-11 In this embodiment, since the optical path design of the three-reflection concentrator is mainly affected by the coaxial condenser and the secondary mirror, it is of great significance to independently study the two-reflection optical path. In the simulation, the entrance pupil diameter is set to 500m, the initial focal length of the coaxial condenser is 400m, and the entrance pupil diameter is used as the constraint boundary. Ray tracing is performed on the two-reflection optical path. Under ideal conditions, all light passing through the reflection surface should be focused on one point, and two conical optical paths with opposite tips are formed before and after the focus. However, from Figure 3 It can be observed that there is no obvious boundary before and after the focus, and there are multiple light convergence sections in the light path, which indicates that the light in the light path is focused at different positions, resulting in the generation of multiple focal points. Since the main focus and the virtual focus are distributed along the optical axis, and Figure 4 The focal spot irradiance diagram in the figure shows a symmetrical distribution. It can be inferred that the spherical aberration has a significant impact on the two-reflection light path. The edge light deviates from the focus position, resulting in the effective energy accounting for only 9% of the total energy. In order to further analyze the impact of spherical aberration on the three-reflection light path, Figure 6 A plane fast reflector is introduced into the optical path. After the third reflection, some edge rays cross in front of the receiving surface. The focal spot is as follows: Figure 7 As shown in the figure, it is an asymmetric distribution. The total energy collected by the receiving surface is reduced by 6%, and the effective energy accounts for only 5% of the total energy. This result shows that the spherical aberration effect has a significant impact on the overall focusing efficiency of the system, especially the impact on the focus quality in the deflection optical path is particularly significant.

[0039] Specific implementation method 3: See Figure 3-11 This embodiment is described. On the basis of the second embodiment, the coaxial concentrator (1) is made of carbon fiber composite material with a focal length of 400m. The surface is coated with a high reflectivity film layer and a lightweight carbon fiber composite material. The carbon fiber material has a low density (about 1 / 4 of that of metal) and has high strength and high modulus, which greatly reduces the overall weight of the concentrator, meets the requirements of lightweight spacecraft, and reduces the fuel consumption and launch cost of the launch vehicle. The carbon fiber can still maintain stable mechanical properties in extreme temperatures (-180°C to 120°C) and radiation environments, avoiding optical path deviation caused by thermal expansion or contraction, and ensuring the reliability of long-term operation on the lunar surface. The day and night temperature difference on the lunar surface and micrometeorite impacts may cause material fatigue. The high fatigue resistance of carbon fiber can extend the service life of the equipment. A 400m long focal length setting is adopted. The long focal length design can expand the focusing area, improve the efficiency of sunlight capture, and provide a higher energy density (up to 800W / m in simulation) for the lunar back detection equipment. 2 ), long focal length combined with three-reflection structure (coaxial condenser + parallel light conversion mirror + fast reflection mirror) can reduce the influence of spherical aberration on the focal spot and optimize the focusing effect of the optical path. Fig.10 As shown in the figure, the long focal length needs to be matched with a rigid support structure. The high rigidity of carbon fiber can effectively suppress the interference of vibration or deformation on the accuracy of the optical path. The high reflectivity film layer significantly reduces the loss of light energy in the reflection process (the reflectivity of traditional coatings is usually 85%-90%), which increases the system's light energy utilization rate by 10%-15%. The coating adopts a special radiation-resistant and oxidation-resistant coating (such as silver + titanium dioxide multilayer film), which can resist strong ultraviolet rays on the lunar surface, atomic oxygen erosion and dust pollution, ensuring long-term stable reflection performance. The high reflectivity film layer can reflect unabsorbed solar radiation back into space, reduce the temperature rise on the surface of the condenser due to heat absorption, and avoid the influence of thermal deformation on the accuracy of the optical path.

[0040] Specific implementation method four: see Figure 12-15 To explain this embodiment, in order to eliminate the influence of spherical aberration on the main light path, based on the characteristics of the spherical mirror, a secondary mirror is used to offset the spherical aberration generated by the coaxial condenser. Fig.10 As shown in the figure, after the spherical aberration is offset, the edge light is more effectively distributed, the focusing effect is significantly improved, and the focusing ratio is greatly increased. However, while optimizing the spherical aberration, the structural defects of the coaxial condenser are also magnified. Since the secondary mirror is installed in front of the coaxial condenser, its shielding effect will cause the central area of ​​the coaxial condenser to be without light, thereby generating an energy missing area in the focal spot. Fig.14 This phenomenon is clearly shown in Fig.11 On the receiving surface irradiance diagram, it appears as a valley area close to 0 in the middle. Fig.12The parallel light conversion optical path formed by the front side of the secondary mirror is shown. However, the central occlusion problem of this optical path also leads to an energy loss area in the middle of the focal spot (see Fig.15 ), therefore, in order to optimize the optical path design without changing the weight of the spherical aberration coefficient, the optimization coefficient of the effective optical focal length is introduced in the wizard, the surface shapes of the coaxial condenser and the secondary mirror are adjusted, and based on the ratio of the optimization coefficient weight, the variable parameters of the coaxial condenser and the secondary mirror are step-optimized, so that the unblocked light can be evenly distributed on the receiving surface, avoiding excessive energy concentration and the formation of energy missing areas, thereby improving the overall light energy utilization efficiency and focusing uniformity of the system.

[0041] The specific embodiments of the present invention disclosed above are only used to help explain the present invention. The specific embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A three-reflection space solar concentrator for supplying energy in dark areas on moonlit nights, characterized in that: The invention comprises a coaxial condenser (1), a parallel light conversion mirror (2), a fast reflection mirror (3) and a dual-axis tracker (4), wherein the parallel light conversion mirror (2) is installed above the coaxial condenser (1), the fast reflection mirror (3) is installed below the coaxial condenser (1), and the coaxial condenser (1) is installed on the dual-axis tracker (4).

2. A three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to claim 1, characterized in that: The dual-axis tracker (4) is mounted on a connecting bracket (5).

3. The three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to claim 1, characterized in that: The coaxial concentrator (1) is made of carbon fiber composite material, has a focal length of 400 m, and is coated with a high reflectivity film layer on the surface.

4. The three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to claim 1, characterized in that: The fast reflection mirror (3) is driven by piezoelectric ceramics, with a deflection accuracy of ±0.001° and a response time of ≤10ms.

5. The three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to claim 1, characterized in that: The parallel light conversion mirror (2) adopts a hyperbolic design.

6. The three-reflection space solar concentrator for providing energy in dark areas on moonlit nights according to claim 1, characterized in that: The fast reflection mirror (3) and the dual-axis tracker (4) form a composite axis control system with a control accuracy of ≤0.005°.

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