Photosensitive sensor for space station solar cell test

Abstract

The invention relates to a photosensitive sensor for space station solar cell testing. The four photosensitive diodes have cosine characteristics, and the photosensitive diodes are installed on the base; the photosensitive diodes comprise a first photosensitive diode, a second photosensitive diode, a third photosensitive diode and a fourth photosensitive diode; the connecting line of the first photosensitive diode and the third photosensitive diode is perpendicular to the connecting line of the second photosensitive diode and the fourth photosensitive diode. And the illumination incident angle is calculated by using the output current of the photosensitive diode. The device is small and exquisite in structure and low in cost, the light incident angle and the light azimuth angle can be calculated only through the four photosensitive diodes with the cosine characteristic, and the photosensitive diodes in the photosensitive sensor can be placed at different positions according to application scenes.

Description

Technical Field

[0001] The invention relates to the technical field of photosensitive sensors, and in particular to a photosensitive sensor for testing solar cells in a space station. Background Art

[0002] A solar sensor is a common attitude sensor used in space missions. It is used to measure the incident angle of the sun relative to the solar sensor on the spacecraft. Almost all spacecraft need to be equipped with a solar sensor so that the attitude control tasks of the spacecraft at various stages can be completed according to the attitude feedback information provided by the solar sensor.

[0003] For example, during the calibration of solar cells in the space station, the solar cell sample box is exposed outside the space station cabin. The calibration result of the solar cell sample is related to the incident angle of the sunlight. Since the attitude of the space station will be adjusted from time to time, the sunlight will not directly shine on the solar cell sample device. This requires the calibration result to be corrected according to the angle of the incident sunlight.

[0004] At present, the most commonly used solar sensor probes in spacecraft are digital, analog and "0-1". Among them, the digital solar sensor probe is used to measure the position of the sun and the position of the satellite's coordinate system; the analog solar sensor probe provides the position information of the sun relative to the solar sail to achieve closed-loop control of the sail automatically tracking the sun; the "0-1" solar sensor probe is installed to form a 4π solid angle field of view, providing solar position information for capture and emergency status. The solar sensor circuit must process the signals output by the above three solar sensor probes and feed back the information of each sensor to the onboard computer.

[0005] With the rapid development of global microelectronics technology, micro-satellites with high integration, small size and light weight have broad application prospects. Existing solar sensors cannot meet the current satellite development requirements in terms of size, weight and power consumption. Therefore, solar sensors need to be developed with the characteristics of low power consumption, small size and high system integration.

[0006] The existing patents "A Photosensitive Sensor" (CN201721755075.6) and "Photovoltaic Tracking Light Angle Sensor" (CN200710177557.2) are related to the field of photosensitive sensor structure and installation technology. The patent mainly describes the structural design of the photosensitive sensor. The light-transmitting cover, circuit board, back shell, etc. of the photosensitive sensor are welded, and the installation nuts are installed to protect the photoresistor, so that the reliability is enhanced and the processability is better, but no theoretical analysis and design of the angle measurement formula is carried out. The "Photovoltaic Tracking Light Angle Sensor" patent detects the deviation between the sun and the photovoltaic array through internal photosensitive devices, but it requires more photosensitive devices, the structure is large, and it is not flexible. It cannot be easily applied to small structures and has certain limitations. Summary of the invention

[0007] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a photosensor for testing solar cells in a space station, which can calculate the light incident angle and azimuth angle by using only four photodiodes with cosine characteristics.

[0008] like Figures 1 to 6 As shown, in order to achieve the above-mentioned purpose, the present invention provides a photosensitive sensor for testing solar cells in a space station, comprising:

[0009] A base and four photosensitive diodes with cosine characteristics, wherein the photosensitive diodes are mounted on the base;

[0010] The photosensitive diodes are a first photosensitive diode, a second photosensitive diode, a third photosensitive diode, and a fourth photosensitive diode;

[0011] The connection line between the first photosensitive diode and the third photosensitive diode is perpendicular to the connection line between the second photosensitive diode and the fourth photosensitive diode;

[0012] The light incident angle is calculated using the output current of the photodiode.

[0013] According to a technical solution of the present invention, the base includes a main body and a supporting part, the main body is in the shape of an inverted quadrangular pyramid, and the angles θ between the four concave side surfaces and the bottom surface are all 30° or 45°.

[0014] According to a technical solution of the present invention, a slot hole for mounting the photodiode is provided on any of the side surfaces, and the slot hole is located at the geometric center of the side surface.

[0015] According to a technical solution of the present invention, the shape of the slot is adapted to the shape of the photodiode.

[0016] According to a technical solution of the present invention, the side length of the bottom surface of the base is 15cm-20cm.

[0017] According to a technical solution of the present invention, the photosensor calculates the incident angle and azimuth of sunlight according to the following formula:

[0018]

[0019] Wherein, I1 is the output current of the first photosensitive diode, I2 is the output current of the second photosensitive diode, I3 is the output current of the third photosensitive diode, I4 is the output current of the fourth photosensitive diode, and I 13 is the value of I1 minus I3, I 24is the value of I2 minus I4, β is the incident angle of the sunlight, α is the azimuth angle of the sunlight, and θ is the angle between the inner concave surface of the base and the bottom surface.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. A new type of photosensor structure design is proposed. It is compact and low-cost. It can calculate the light incident angle and azimuth angle by using only four photodiodes with cosine characteristics.

[0022] 2. Several photodiodes in the photosensitive sensor can also be placed in different positions according to the application scenario. According to the different structural design angles, the formula for calculating the light angle of the photosensitive sensor is also different, so as to realize the current characteristic test correction under different angles of sunlight. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram schematically showing the structure of the photosensor of the present invention;

[0025] Figure 2 A schematic diagram schematically showing the structure of the photosensitive sensor base after being disassembled according to the present invention;

[0026] Figure 3 A schematic diagram schematically showing the principle of differential angle measurement of a photodiode of the present invention;

[0027] Figure 4 A schematic diagram schematically showing the definition of Euler angles of the present invention;

[0028] Figure 5 A schematic diagram schematically showing the relationship between the incident light and the photodiode coordinate system of the present invention.

[0029] Figure 6 A schematic diagram showing the size and structure of a photosensor when θ is 30° according to the present invention;

[0030] Figure 7 Schematically showing the incident light schematic diagram of the photosensitive sensor when θ is 30° in the present invention;

[0031] Figure 8 A circuit diagram schematically showing a photosensitive diode connected to a transimpedance amplifier according to the present invention. DETAILED DESCRIPTION

[0032] The description of the embodiments of this specification should be combined with the corresponding drawings, which should be considered as part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated for simplification or convenience. Furthermore, the parts of each structure in the drawings will be described separately. It is worth noting that the elements not shown in the drawings or not described in words are in a form known to ordinary technicians in the relevant technical field.

[0033] The description of the embodiments herein and any reference to directions and orientations are only for the convenience of description and are not to be construed as any limitation on the scope of protection of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination, and the present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0034] like Figure 1 As shown, the present invention proposes a photosensitive sensor for testing solar cells in a space station, comprising:

[0035] A base and four photosensitive diodes with cosine characteristics, wherein the photosensitive diodes are mounted on the base;

[0036] The photosensitive diodes are a first photosensitive diode, a second photosensitive diode, a third photosensitive diode, and a fourth photosensitive diode;

[0037] The connection line between the first photosensitive diode and the third photosensitive diode is perpendicular to the connection line between the second photosensitive diode and the fourth photosensitive diode;

[0038] The light incident angle is calculated using the output current of the photodiode.

[0039] The base comprises a main body and a supporting part. The main body is in the shape of an inverted quadrangular pyramid. The supporting part is four supporting columns. The angles θ between the four concave side surfaces and the bottom surface are all 30° or 45°.

[0040] Figure 6 Specifically, a schematic diagram of the size structure of a photosensor with a θ of 30° is provided. When θ is 30°, the following can be prevented: Figure 7 Interreflection of opposite inclined surfaces shown.

[0041] A slot hole for mounting a photodiode is arranged on any side surface, and the slot hole is located at the geometric center of the side surface.

[0042] The shape of the slot is adapted to the shape of the photodiode.

[0043] The bottom side length of the base is 15cm-20cm.

[0044] The photosensor calculates the incident angle and azimuth of sunlight according to the following formula:

[0045]

[0046] Wherein, I1 is the output current of the first photosensitive diode, I2 is the output current of the second photosensitive diode, I3 is the output current of the third photosensitive diode, I4 is the output current of the fourth photosensitive diode, and I 13 is the value of I1 minus I3, I 24 is the value of I2 minus I4, β is the incident angle of sunlight, α is the azimuth angle of the sunlight, and θ is the angle between the inner concave surface of the base and the bottom surface.

[0047] In addition, in order to output the current of the photodiode, each of the four photodiodes in the present application is equipped with a transimpedance amplifier. The input of the transimpedance amplifier is the current of the corresponding photodiode. When the photodiode is illuminated by light, it generates current, which is converted into voltage output by the operational amplifier. Figure 8 As shown, the circuit diagram of the photodiode connected to the transimpedance amplifier, V0 is the converted voltage, which is detected by the corresponding measuring device to obtain the output current of the corresponding photodiode. The photosensitive sensor structure design of the present invention is compact and low-cost. Only four photosensitive diodes with cosine characteristics can be used to calculate the light incident angle and azimuth. Several photosensitive diodes in the photosensitive sensor can also be placed in different positions according to the application scenario. According to different structural design angles, the formula for calculating the light angle of the photosensitive sensor is also different, so that the current characteristic test correction under different angles of sunlight can be realized.

[0048] The theoretical derivation process of the above formula for calculating the incident angle and azimuth of sunlight is as follows:

[0049] Through a series of coordinate transformations, after determining the installation angle of the photodiode, the relationship between the output current of the photodiode and the incident light is found.

[0050] like Figure 3 As shown, the four photodiodes with cosine characteristics are not on the same plane. Each photodiode receives a different light angle. The apparent light angle of each pair of photodiodes changes differentially. The lines connecting the two pairs of photodiodes are perpendicular to each other. The light incident angle and azimuth are calculated through the output current of the photodiodes.

[0051] The photodiode has a cosine characteristic, that is, when the angle between the incident light and its normal is λ, the output current

[0052] I=I0cosλ

[0053] Where: I-output current; λ-the angle between the incident light and the normal of the photodiode; I0-the output current when the λ angle is zero.

[0054] The photodiode rotates on the mounting plane and is insensitive to the direction of rotation.

[0055] The first and third photodiodes form a differential pair, the second and fourth photodiodes form another differential pair, and the lines connecting the two pairs are perpendicular to each other. The light incident angle β and azimuth angle α of the O-XYZ coordinate system are converted to the coordinate system of each photodiode, and then the angle between the incident light and its normal is obtained. The direction cosine can be obtained by rotating the coordinate system through the Euler angle, and the azimuth and incident angle of the incident sunlight are calculated based on the direction cosine and the cosine characteristics of the photodiode.

[0056] First, the definition of Euler angle rotation is explained. The parameters in the following process are only applicable to the definition of Euler angle rotation: Figure 4 As shown, the original coordinate system O-xyz is transformed into the new coordinate system O-x'y'z' after three rotations. The first rotation is a rotation of ψ angle around the Oz axis. Looking from z to O, the counterclockwise rotation angle from Ox to Ox' is positive, and the clockwise angle is negative. The second rotation is around Ox', and the intersection of the xOy plane and the x'-O-y' plane is called the nodal line ON. The angle between the Oz axis and the Oz' axis is θ. Looking from N to O, the counterclockwise rotation angle from Oz to Oz' is positive, and the clockwise angle is negative. The third rotation is around the Oz' axis, and the Ox' axis rotates away from ON. Angle, from z' to O, the counterclockwise rotation angle from ON to Ox' is positive, and the clockwise angle is negative. ψ is called the precession angle, θ is called the precession angle, and is the rotation angle, the first rotation transformation matrix is ​​Z(ψ), the second rotation transformation matrix is ​​N(θ), and the third rotation transformation matrix is All rotation transformation matrices is the direction cosine matrix. Direction cosines are the cosines of the angles between the coordinate axes.

[0057] The specific formula is as follows:

[0058]

[0059] Suppose the coordinates (x, y, z) of a point A in the original coordinate system O-xyz are transformed to the new coordinate system O-x'y'z', then (x'y'z')T = R·(x, y, z)T is expanded to:

[0060] x'=xcos(x',x)+ycos(x',y)+zcos(x',z)

[0061] y'=xcos(y',x)+ycos(y',y)+zcos(y',z)

[0062] z'=xcos(z',x)+ycos(z',y)+zcos(z',z)

[0063] The inverse transformation is to swap the coordinates of the same name:

[0064] x=x'cos(x,x')+y'cos(x,y')+z'cos(x,z')

[0065] y=x'cos(y,x')+y'cos(y,y')+z'cos(y,z')

[0066] z=x'cos(z,x')+y'cos(z,y')+z'cos(z,z')

[0067] Euler angle rotation is defined as above.

[0068] The derivation process of the angle calculation formula of the incident sunlight in this embodiment is as follows:

[0069] O-XYZ coordinate system Figure 3 As shown, assuming that the light incident through point A, point A is on the unit sphere of radius r = 1 of the reference coordinate system O-XYZ, let the coordinates A (x, y, z), then x = sinβcosα, y = sinβsinα, z = cosβ, the angle of incidence β = cos - 1 z, azimuth α = tan -1 (y / x). After rotating the coordinate system of each photodiode by Euler angles, the coordinates of A in each coordinate system are calculated, and the direction cosines of the incident ray can be obtained.

[0070] The Euler angle rotation process is as follows:

[0071] (1) The first photodiode is initially at the origin of O-xyz, with the normal coinciding with the z-axis. After the first rotation "rotate ψ=90° around Oz, ON coincides with Oy", Z(ψ) is obtained. After the second rotation "rotate θ1 around ON, when looking from N to O, Oz' moves away from Oz clockwise, which is a negative angle", the angle θ1 between the Oz' axis and the Oz axis of the new coordinate system O-x'y'z' is a negative angle, and N(θ) is obtained. After the third rotation "rotate around Oz' That is, the photodiode rotates around its normal line on the mounting surface to zero. Transformation matrix:

[0072]

[0073] Calculate the coordinates of point A in the new coordinate system O-x'y'z'. The cosine of the angle between the OA ray and the three coordinate axes O-x'y'z' is the direction cosine of point A in the new coordinate system O-x'y'z', where the angle between OA and Oz' is γ1, cosγ1=Oz' / r=z'

[0074] (4) Using the same transformation as above, the rotation parameter of the second photodiode is R(0°, -θ1, 0°), and the angle γ2 is calculated;

[0075] (5) With the same transformation as above, the rotation parameter of the third photodiode is R (90°, θ1, 0°), and the angle γ3 is calculated;

[0076] (6) With the same transformation as above, the rotation parameter of the fourth photodiode R (0°, θ1, 0°) is calculated to obtain the angle γ4;

[0077] When the azimuth angle α=0:

[0078] For the first photosensitive diode: γ1 = β - θ; output current I1 = I0cos(β - θ).

[0079] For the third photosensitive diode: γ3=β+θ; output current I3=I0cos(β+θ).

[0080] Output current difference I 13 =I1–I3=I0[cos(β-θ)-cos(β+θ)]=2I0sinβsinθ

[0081] When the azimuth angle α=90°:

[0082] For the second photosensitive diode: γ2 = β - θ; output current I2 = I0cos(β - θ).

[0083] For the fourth photosensitive diode: γ4=β+θ; output current I4=I0cos(β+θ).

[0084] Output current difference I 24 =I2–I4=I0[cos(β-θ)-cos(β+θ)]=2I0sinβsinθ

[0085] For a pair of differential photodiodes, when β≠0, the output of a single photodiode changes during the rotation of the azimuth angle α, but when one output increases, the other output decreases, and the total energy remains unchanged. The RMS value of the differential in the orthogonal direction is only related to β, that is, the following relationship exists: (The following formula only

[0086] The angle θ between the four concave sides of the base and the bottom is 30°, and other inclination angles require adjustment coefficients):

[0087] The differential energy formula is expressed as:

[0088] I 13 2 +I 24 2 =2I0 2 sin 2 βsin 2 θ;

[0089]

[0090] When θ is equal to 30 degrees:

[0091] or

[0092] When θ is equal to 45 degrees:

[0093] or

[0094]

[0095] or

[0096] Among them, the calculation of I0 can be considered that at the incident angle β, the total incident energy is E0, and the energy received by the four sensors is E i =E0cosβ

[0097] in:

[0098]

[0099] Special case: The inclination angle of the θ slope is 30 degrees.

[0100] For the first photosensitive diode: γ1 = β - θ; output current I1 = I0cos(β - θ).

[0101] For the third photosensitive diode: γ3=β+θ; output current I3=I0cos(β+θ).

[0102] For the second and fourth photosensitive diodes: output current I2 = I4 = I0cosβcosθ.

[0103] Comprehensive above formula:

[0104] I1=I0cos(β+θ)

[0105] I3=I0 cos(β-θ)

[0106] I1+I3=I0[cos(β+θ)+cos(β-θ)]

[0107] =2I0 cosβcosθ

[0108]

[0109] Substituting the above I0 into the differential energy formula (1), we have:

[0110]

[0111] When θ=30°, sin30°=0.5, cos30°=0.866,

[0112]

[0113]

[0114] or:

[0115]

[0116] Finally, the relationship between the light incident angle and the output current of the four photodiodes is obtained:

[0117]

[0118] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A photosensitive sensor for testing solar cells in a space station, characterized in that: include; A base and four photosensitive diodes with cosine characteristics, wherein the photosensitive diodes are mounted on the base; The photosensitive diodes are a first photosensitive diode, a second photosensitive diode, a third photosensitive diode, and a fourth photosensitive diode; The connection line between the first photosensitive diode and the third photosensitive diode is perpendicular to the connection line between the second photosensitive diode and the fourth photosensitive diode; The light incident angle is calculated using the output current of the photodiode.

2. The photosensor according to claim 1, characterized in that: The base comprises a main body and a supporting part. The main body is in the shape of an inverted quadrangular pyramid. The angles θ between the four concave side surfaces and the bottom surface are all 30° or 45°.

3. The photosensor according to claim 2, characterized in that: A slot hole for mounting the photodiode is provided on any of the side surfaces, and the slot hole is located at the geometric center of the side surface.

4. The photosensor according to claim 3, characterized in that: The shape of the slot is adapted to the shape of the photodiode.

5. The photosensor according to claim 2, characterized in that: The side length of the bottom surface of the base is 15cm-20cm.

6. The photosensor according to claim 2 or 3, characterized in that: The photosensitive sensor calculates the incident angle and azimuth of sunlight according to the following formula: Wherein, I1 is the output current of the first photosensitive diode, I2 is the output current of the second photosensitive diode, I3 is the output current of the third photosensitive diode, I4 is the output current of the fourth photosensitive diode, and I 13 is the value of I1 minus I3, I 24 is the value of I2 minus I4, β is the incident angle of the sunlight, α is the azimuth angle of the sunlight, and θ is the angle between the inner concave surface of the base and the bottom surface.

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