A solar direct radiation meter and its automatic tracking method

Abstract

The present invention relates to a solar direct irradiance meter and an automatic tracking method thereof. The device includes a stepper motor module, a main control module, a photoelectric detection module, and a radiation detection module. The stepper motor module includes an azimuth axis stepper motor and an altitude axis stepper motor. The main control module is respectively connected to the stepper motor module, the photoelectric detection module, and the radiation detection module. Information such as the current detection time, longitude, and latitude of the detection location is obtained through the main control module. The current solar altitude angle and azimuth angle are calculated through the apparent solar motion trajectory algorithm, and the solar direct irradiance meter is controlled to initially track the sun. The radiation intensities in four quadrants are obtained by using the photoelectric detection module, and the detection value of the radiation detection module is combined to perform fine adjustment of the solar trajectory. The present invention makes up for the respective defects of the photoelectric detection technology and the apparent solar motion trajectory technology, and improves the tracking and detection accuracy of the solar direct irradiance meter.

Description

Technical Field

[0001] The present invention relates to a solar direct irradiance meter and an automatic tracking method thereof, belonging to the field of detection technology. Background Art

[0002] At present, the design of solar direct radiation measurement in China is mainly fixed and single-axis tracking, and the method adopted is relatively single. The single-axis tracking method can only align with the sun in the azimuth axis direction, and the vertical direction needs to be manually adjusted every few days, and only semi-automatic detection can be carried out.

[0003] At the same time, in the existing full-automatic tracking methods, the tracking method of the apparent solar motion trajectory cannot eliminate the cumulative error by itself, and the single-photoelectric tracking method is easily affected by complex weather.

[0004] Therefore, there is an urgent need to design a new type of irradiance meter, and the tracking method based on it can solve the problem of inaccurate measurement caused by real-time tracking of the sun. Summary of the Invention

[0005] The present invention provides a solar direct irradiance meter and an automatic tracking method thereof, which improves the accuracy of tracking the sun for measurement.

[0006] The technical solution adopted by the present invention to solve its technical problems is:

[0007] A solar direct irradiance meter includes a stepper motor module, a main control module, a photoelectric detection module, and a radiation detection module. The stepper motor module includes an azimuth axis stepper motor and an altitude axis stepper motor. The azimuth axis stepper motor is fixed on the base, and the motor shaft of the azimuth axis stepper motor is vertically installed at the center of the base. Taking the center of the base as the origin, the coordinate plane formed by the X-axis and Y-axis passing through the origin is parallel to the base plane, and the axial direction of the motor shaft of the azimuth axis stepper motor is the Z-axis, constructing a three-dimensional coordinate system;

[0008] The altitude axis stepper motor is arranged at the top of the azimuth axis stepper motor in the Y-axis direction, and the motor shaft of the altitude axis stepper motor is arranged perpendicular to the Z-axis direction;

[0009] The photoelectric detection module and the radiation detection module are connected to form a detection component, and the motor shaft of the altitude axis stepper motor is connected to the detection component;

[0010] The main control module is simultaneously connected to the stepper motor module and the detection component. The main control module sends a start command to the azimuth axis stepper motor, and the detection component can move within the coordinate plane formed by the X-axis and Y-axis. The main control module sends a start command to the altitude axis stepper motor, and the detection component can move within the coordinate planes formed by the X-axis and Z-axis and the Y-axis and Z-axis;

[0011] As a further preference of the present invention, the detection component is installed inside a cylindrical light tube, and a radiation detection module is installed at one end of the cylindrical light tube. The radiation detection module includes a lens, a sensing surface, a thermopile, and a measurement base. The thermopile, the sensing surface, and the lens are sequentially stacked on the surface of the measurement base, and the lens covers the port at one end of the cylindrical light tube;

[0012] And the lens faces the sun direction;

[0013] As a further preference of the present invention, a light tube caster is sleeved on the outer wall of the cylindrical box body, and the light tube caster is fixed to the motor shaft of the height axis stepper motor;

[0014] As a further preference of the present invention, the photoelectric detection module is a photoelectric detection sensor, and a plurality of photoelectric detection sensors are evenly distributed along the circumference of the lens;

[0015] As a further preference of the present invention, four photoelectric detection sensors are provided and are evenly distributed in the four quadrants along the circumference of the lens;

[0016] As a further preference of the present invention, the stepper motor module and the main control module are both placed inside a square box body, and the motor shaft of the azimuth axis stepper motor of the stepper motor module extends out of the square box body and is fixed to the base;

[0017] A motor tray is arranged at the bottom inside the square box body, and the azimuth axis stepper motor is placed on the motor tray;

[0018] As a further preference of the present invention, the main control module includes an STM32 microprocessor, a stepper motor drive module, a wireless communication module, and a peripheral circuit, and the four are connected;

[0019] The photoelectric detection module, the radiation detection module, and the stepper motor module are simultaneously connected to the main control module, and the stepper motor module is connected to the radiation detection module. There is also an upper computer module, which is also connected to the main control module;

[0020] As a further preference of the present invention, the wireless communication module uses ZigBee for data transmission.

[0021] An automatic tracking method based on the above solar direct radiation meter specifically includes the following steps:

[0022] Step S1: The upper computer sends a start command to the main control module through ZigBee wireless communication, and obtains the longitude, latitude, and time of the current detection location through the main control module, and calculates the solar hour angle ω. The calculation formula is:

[0023]

[0024] In formula (1), ω is the solar hour angle, N0 is the longitude of the current detection location, NST The standard longitude adopted for formulating the standard time, T0 is the time at the current detection location, and W is the longitude correction coefficient;

[0025] Step S2: Obtain the longitude, latitude, and time of the current detection location through the main control module, and calculate the solar declination angle δ. The calculation formula is:

[0026]

[0027] In formula (2), B is the angle of the sun relative to the earth, and N is the number of days, and the number of days is recorded starting from January 1 of each year;

[0028] Step S3: Calculate the solar altitude angle and the solar azimuth angle based on the solar hour angle and the solar declination angle obtained through Step S1 and Step S2. Among them, the solar altitude angle γ S The calculation formula is:

[0029]

[0030] In formula (3), δ is the solar declination angle, φ is the latitude angle of the detection location, and ω is the solar hour angle;

[0031] The calculation formula for the solar azimuth angle is:

[0032]

[0033] In formula (4), τ s Is the solar azimuth angle, δ is the solar declination angle, φ is the latitude angle of the detection location, γ S Is the solar altitude angle;

[0034] Step S4: According to Step S3, obtain the solar altitude angle and the solar azimuth angle, and adjust the initial position of the solar direct radiation meter to make it enter the initial state;

[0035] Step S5: If there is no cumulative error after tracking the initial state, directly obtain the solar direct radiation measurement value. If there is a cumulative error after tracking, proceed to the next step;

[0036] Step S6: Perform a diurnal motion trajectory tracking on the solar direct radiation. The sunlight forms a circular light spot in the four photodetectors. The parts of the light spot in the four quadrants are respectively assumed to be I, II, III, and IV. The electrical signals generated by the photoelectric effect are V Ⅰ , V Ⅱ , V Ⅲ , V Ⅳ , Set the deviation value of the center of the light spot and the detection component in the coordinate plane formed by the X-axis and the Y-axis to be G xy, the deviation values of the spot center in the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis with respect to the detection component are G h , and the calculation formulas for the deviation values are respectively:

[0037]

[0038] Meanwhile, the radiation measurement module obtains the current radiation measurement value and the previous radiation measurement value of the sun, and calculates the relative change value of the direct solar radiation:

[0039] S = (S1 - S0) / (S1 + S0) (6)

[0040] In formula (6), S1 is the current radiation measurement value, and S0 is the previous radiation measurement value of the sun;

[0041] Step S7: Calculate the movement directions of the current azimuth axis stepper motor and the elevation axis stepper motor based on the deviation value and the relative change value of the direct solar radiation obtained in step S6, that is

[0042] Dxy = aG xy + bS (7)

[0043] Dh = aG h + bS (8)

[0044] In formulas (7) and (8), a is the weight coefficient of the photoelectric detection sensor, which can be taken as 0.4, b is the weight coefficient of the solar radiation measurement value, which can be taken as 0.6, Dxy is the moving azimuth of the azimuth axis stepper motor in the coordinate plane formed by the X-axis and the Y-axis, and Dh is the moving azimuth of the elevation axis stepper motor in the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis;

[0045] Step S8: The main control module performs step-by-step rotation fine-tuning on the azimuth axis stepper motor and the elevation axis stepper motor respectively according to Dxy and Dh. Meanwhile, the direct solar radiation value and the photoelectric sensor are detected again respectively, and Dxy and Dh are calculated. If the signs, that is, the directions of Dxy and Dh change, the adjustment is stopped respectively until the azimuth angle and the elevation angle are adjusted;

[0046] Step S9: Every 1 minute, repeat the attitude adjustment of the detection component according to steps S1 - S7 until an error-free direct solar radiation measurement value is obtained, and the result is transmitted to the host computer through ZigBee wireless communication to end the tracking;

[0047] As a further preference of the present invention, the specific steps for obtaining the direct solar radiation measurement value in step S9 are:

[0048] Step S91: The sunlight shines directly on the lens surface and is transmitted to the sensing surface through the lens. When the sensing surface receives sunlight radiation and reaches relative thermal equilibrium, the calculation formula is

[0049] I = K1*(t1 - t2) + (1 - ε)*I + K2*(t1 - t3) (9)

[0050] In formula (9), K1 is the thermal conductivity coefficient conducted to the bottom measurement base, K2 is the thermal conductivity coefficient between the air temperature and the sensing surface temperature, t1 is the temperature of the sensing surface, t2 is the temperature of the measurement base, ε is the absorptivity of the sensing surface, I is the detected incident radiation value, and t3 is the air temperature;

[0051] Step S92: By obtaining the temperature difference between the sensing surface and the measurement base, calculate the electromotive force generated by the thermopile. The formula is

[0052] V = I0*(t1 - t2) (10)

[0053] In formula (10), I0 is the thermoelectric end conversion coefficient, with the unit of μV / ℃, t1 is the temperature of the sensing surface, and t2 is the temperature of the measurement base;

[0054] Step S93: Combining formula (9) in step S91 and formula (10) in step S92, the calculation formula for the electromotive force signal is

[0055]

[0056] In formula (11), I0 is the thermoelectric end conversion coefficient, with the unit of μV / ℃, K1 is the thermal conductivity coefficient conducted to the bottom measurement base, K2 is the thermal conductivity coefficient between the air temperature and the sensing surface temperature, t1 is the temperature of the sensing surface, t2 is the temperature of the measurement base, ε is the absorptivity of the sensing surface, I is the detected incident radiation value, and t3 is the air temperature. The magnitude of the output electrical signal of the radiation detection module is obtained from formula (11), thereby calculating the intensity of the direct radiation.

[0057] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. The solar direct radiometer provided by the present invention, through the settings of the azimuth axis stepping motor and the elevation axis stepping motor, can move within the coordinate plane formed by the X-axis and the Y-axis as shown, and can also move within the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis. It solves the problem that the single-axis fixed detection cannot track in real time and accurately, improves the tracking accuracy of the instrument, and realizes more accurate direct radiation measurement; Figure 1 As shown, it can move within the coordinate plane formed by the X-axis and the Y-axis, and can also move within the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis. It solves the problem that the single-axis fixed detection cannot track in real time and accurately, improves the tracking accuracy of the instrument, and realizes more accurate direct radiation measurement;

[0059] 2. The solar direct radiometer provided by the present invention can automatically eliminate cumulative errors in the tracking mode of the apparent solar motion trajectory, solve the problems of photoelectric tracking being vulnerable to complex weather and the influence of cumulative errors in the tracking of the apparent solar motion trajectory, and improve the stability and accuracy of the tracking operation detection of the instrument and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The present invention will be further described below in conjunction with the drawings and embodiments.

[0061] Figure 1 It is a schematic block diagram of module connection provided by the present invention;

[0062] Figure 2 It is a schematic working process diagram of the solar direct radiometer provided by the present invention;

[0063] Figures 3a - 3b It is the left view and right view of the solar direct radiometer provided by the present invention;

[0064] Figures 4a - 4b It is the front view and top view of the solar direct radiometer provided by the present invention;

[0065] Figure 5 It is a cross-sectional view of the radiation detection device provided by the present invention;

[0066] Figure 6 Schematic diagram of the spot distribution when the photoelectric detection module provided by the present invention is operating.

[0067] In the figure: 1 is the radiation detection module, 2 is the light tube, 3 is the light tube clamping wheel, 4 is the photoelectric detection sensor, 5 is the stepping motor bushing, 6 is the height axis stepping motor, 7 is the azimuth axis stepping motor, 8 is the STM32 microprocessor, 9 is the base, 10 is the instrument rear cover, 11 is the square box body, 12 is the motor tray, 13 is the dust-proof transparent glass cover, 14 is the lens, 15 is the induction surface, 16 is the thermopile, 17 is the measurement base, 18 is the radiation measurement housing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0068] Now, the present invention will be further described in detail in conjunction with the drawings. In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second", etc. do not represent the importance of the components, so they cannot be understood as limitations to the present invention. The specific dimensions adopted in this embodiment are only for illustrating the technical solution and do not limit the protection scope of the present invention.

[0069] As described in the background art, in the current fully automatic tracking method for domestic direct solar radiation measurement, firstly, it is a single-axis tracking method, so it can only align with the sun in the azimuth axis direction. Secondly, due to the influence of complex weather, errors are likely to occur, but the cumulative errors cannot be eliminated automatically. Therefore, based on the existing tracking method, this application has made improvements and experiments to provide a direct solar radiation meter. Figure 1 It can be seen that the module diagram on which this application is based mainly includes a stepping motor module, a main control module, a photoelectric detection module, and a radiation detection module 1. The main control module includes an STM32 microprocessor 8, a stepping motor drive module, a wireless communication module, and a peripheral circuit, and the four are connected; the photoelectric detection module, the radiation detection module, and the stepping motor module are all connected to the main control module, and the stepping motor module is connected to the radiation detection module. There is also an upper computer module, which is also connected to the main control module. In the preferred embodiment here, the stepping motor in the stepping motor module (i.e., the azimuth axis stepping motor 7 and the altitude axis stepping motor described below) uses a 57BYG250B-8 type stepping motor, and the stepping motor drive chip uses a TB67S1109AFTG to support a maximum of 32 stepping angle subdivisions. The wireless communication module is Zigbee with a CC2530 chip as the core.

[0070] In the system provided by this application, the stepping motor module includes an azimuth axis stepping motor and an altitude axis stepping motor 6. This structural setting can meet the automatic adjustment in both the azimuth axis and the vertical direction to improve the measurement accuracy. At the same time, the setting of the photoelectric detection module can automatically eliminate the cumulative errors in the tracking mode of the apparent solar motion trajectory, thereby further improving the detection accuracy.

[0071] Next, the above principle will be specifically described. Figures 3a - 4b As shown, the azimuth axis stepping motor is fixed on the base 9, and the motor shaft of the azimuth axis stepping motor is vertically installed at the center of the base. Since the azimuth problem needs to be utilized when describing the automatic tracking method later, for the convenience of description, this application takes the center of the base as the origin, and the coordinate plane formed by the X-axis and Y-axis passing through the origin is parallel to the base plane. The axial direction of the motor shaft of the azimuth axis stepping motor is the Z-axis, and a three-dimensional coordinate system is constructed.

[0072] The altitude axis stepping motor is arranged at the top of the azimuth axis stepping motor in the Y-axis direction, and the motor shaft of the altitude axis stepping motor is arranged perpendicular to the Z-axis direction; the photoelectric detection module and the radiation detection module are connected to form a detection component, and the motor shaft of the altitude axis stepping motor is connected to the detection component.

[0073] The main control module is connected to the stepper motor module and the detection component at the same time. The main control module sends a start command to the azimuth axis stepper motor, and the detection component can move within the coordinate plane formed by the X-axis and the Y-axis. The main control module sends a start command to the elevation axis stepper motor, and the detection component can move within the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis. The above movement modes satisfy the adjustment of the instrument in both the azimuth axis and the vertical direction, and fully realize the fully automatic tracking mode.

[0074] In this application, the stepper motor module and the main control module are both placed inside the square box 11. Here, the main control module is located on the left side of the inner wall of the square box (taking the Figure 3a viewpoint as an example). As shown in the Figure 3b angle, the back of the square box is a movable structure, which is the instrument rear cover 10, facilitating the disassembly and installation of the entire square box. The motor shaft of the azimuth axis stepper motor of the stepper motor module extends out of the square box and is fixed to the base; a motor tray 12 is arranged at the bottom inside the square box, and the azimuth axis stepper motor is placed on the motor tray; the azimuth axis stepper motor and the elevation axis stepper motor are fastened through a stepper motor retaining sleeve 5. The detection component is installed inside the cylindrical light tube 2, and a radiation detection module is installed at one end of the cylindrical light tube. Among them, Figure 5 as shown in the figure, the radiation detection module includes a lens 14, a sensing surface 15, a thermopile 16, and a measurement base 17. The thermopile, the sensing surface, and the lens are sequentially stacked on the surface of the measurement base, and the lens covers the port at one end of the cylindrical light tube; and the lens faces the sun direction, enabling the tracking mode of the sun's apparent motion trajectory.

[0075] In order to protect the lens, a dust-proof transparent glass cover 13 is covered on the surface of the lens; at the same time, the so-called radiation detection module is installed inside the radiation measurement housing 18, and the entire radiation measurement housing is embedded at one end of the cylindrical light tube.

[0076] In the embodiment, in order to connect the detection component to the stepper motor module, a light tube caster 3 is sleeved on the outer wall of the cylindrical box, and the light tube caster is fixed to the motor shaft of the elevation axis stepper motor.

[0077] After the embodiment provides the fully automatic tracking mode, the problem of automatically eliminating the accumulated error still needs to be solved. The structure for solving this problem in this application is the photoelectric detection module. The photoelectric detection module is a photoelectric detection sensor, and multiple photoelectric detection sensors are evenly distributed along the circumference of the lens. In the preferred embodiment, four photoelectric detection sensors are provided and evenly distributed in the four quadrants along the circumference of the lens, Figure 6 which is the spot distribution diagram of the photoelectric detection module when eliminating the error accumulation.

[0078] Next, as shown in Figure 2 the figure, an automatic tracking method based on the preferred embodiment of this application is provided, which specifically includes the following steps:

[0079] Step S1: The host computer sends a start command to the main control module through ZigBee wireless communication, obtains the longitude, latitude, and time of the current detection location through the main control module, and calculates the solar hour angle ω. The calculation formula is:

[0080]

[0081] In formula (1), ω is the solar hour angle, N0 is the longitude of the current detection location, N ST is the standard longitude adopted for formulating the standard time, T0 is the time of the current detection location, and W is the longitude correction coefficient;

[0082] Step S2: Obtain the longitude, latitude, and time of the current detection location through the main control module, and calculate the solar declination angle δ. The calculation formula is:

[0083]

[0084] In formula (2), B is the angle of the sun relative to the earth, and N is the number of days, and the number of days is recorded starting from January 1 of each year;

[0085] Step S3: Calculate the solar altitude angle and solar azimuth angle based on the solar hour angle and solar declination angle obtained in Step S1 and Step S2. Among them, the solar altitude angle γ S The calculation formula is:

[0086]

[0087] In formula (3), δ is the solar declination angle, φ is the latitude angle of the detection location, and ω is the solar hour angle;

[0088] The calculation formula for the solar azimuth angle is:

[0089]

[0090] In formula (4), τ s is the solar azimuth angle, δ is the solar declination angle, φ is the latitude angle of the detection location, γ S is the solar altitude angle;

[0091] Step S4: According to Step S3, obtain the solar altitude angle and solar azimuth angle, and adjust the initial position of the solar direct radiation meter to make it enter the initial state;

[0092] Step S5: If there is no cumulative error after the initial state tracking, directly obtain the solar direct radiation measurement value. If there is a cumulative error after the tracking, proceed to the next step;

[0093] Step S6: Perform apparent solar motion trajectory tracking on direct solar radiation. The photoelectric detection module detects the current light intensity. Four identical photoelectric detection sensors are evenly distributed in the four quadrants of the photoelectric detection module. The sunlight entering the photoelectric detection module forms a circular light spot inside the detection module. The parts of the light spot in the four quadrants are respectively assumed to be I, II, III, and IV. The electrical signals generated by the photoelectric effect are respectively V Ⅰ , V Ⅱ , V Ⅲ , V Ⅳ . Set the deviation value of the light spot center and the detection component in the coordinate plane formed by the X-axis and the Y-axis as G xy . Set the deviation values of the light spot center and the detection component in the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis as G h . The calculation formulas for the deviation values are respectively:

[0094]

[0095] Meanwhile, the radiation measurement module obtains the current radiation measurement value and the previous radiation measurement value of the sun, and calculates the relative change value of direct solar radiation:

[0096] S = (S1 - S0) / (S1 + S0) (6)

[0097] In formula (6), S1 is the current radiation measurement value, and S0 is the previous solar radiation measurement value;

[0098] Step S7: Calculate the movement directions of the current azimuth axis stepping motor and the elevation axis stepping motor based on the deviation values and the relative change value of direct solar radiation obtained in Step S6, that is

[0099] Dxy = aG xy + bS (7)

[0100] Dh = aG h + bS (8)

[0101] In formulas (7) and (8), a is the weight coefficient of the photoelectric detection sensor 4, which can be taken as 0.4, b is the weight coefficient of the solar radiation measurement value, which can be taken as 0.6, Dxy is the moving azimuth of the azimuth axis stepping motor in the coordinate plane formed by the X-axis and the Y-axis, and Dh is the moving azimuth of the elevation axis stepping motor in the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis;

[0102] Step S8: The main control module performs fine stepping rotation adjustments on the azimuth axis stepper motor and the elevation axis stepper motor respectively based on Dxy and Dh. Meanwhile, it detects and calculates Dxy and Dh again for the direct solar radiation value and the photoelectric sensor respectively. When the signs (i.e., directions) of Dxy and Dh change, the adjustments are stopped respectively until the azimuth angle and elevation angle are adjusted completely;

[0103] Step S9: Every 1 minute, repeat the attitude adjustment of the detection component according to Steps S1 - S7 until a direct solar radiation measurement value without error is obtained. The microprocessor transmits the result to the host computer through ZigBee wireless communication. The server stores the data, and the host computer displays the radiation detection data and information such as the current solar elevation angle and azimuth angle, and the tracking ends.

[0104] The specific steps to obtain the direct solar radiation measurement value in Step S9 are as follows:

[0105] Step S91: The sunlight shines directly on the lens surface and is transmitted to the sensing surface through the lens. When the sensing surface receives sunlight radiation and reaches relative thermal equilibrium, the calculation formula is

[0106] I = K1 * (t1 - t2) + (1 - ε) * I + K2 * (t1 - t3) (9)

[0107] In formula (9), K1 is the heat conduction coefficient conducted to the bottom measurement base, K2 is the heat conduction coefficient between the air temperature and the sensing surface temperature, t1 is the temperature of the sensing surface, t2 is the temperature of the measurement base, ε is the absorptivity of the sensing surface, I is the detected incident radiation value, and t3 is the air temperature;

[0108] Step S92: By obtaining the temperature difference between the sensing surface and the measurement base, calculate the electromotive force generated by the thermopile. The formula is

[0109] V = I0 * (t1 - t2) (10)

[0110] In formula (10), I0 is the thermoelectric end conversion coefficient, with the unit of μV / ℃, t1 is the temperature of the sensing surface, and t2 is the temperature of the measurement base;

[0111] Step S93: Combining formula (9) in Step S91 and formula (10) in Step S92, the calculation formula for the electromotive force signal is

[0112]

[0113] In formula (11), I0 is the thermoelectric end conversion coefficient with the unit of μV / ℃, K1 is the heat conduction coefficient conducted to the bottom measurement base, K2 is the heat conduction coefficient between the air temperature and the induction surface temperature, t1 is the temperature of the induction surface, t2 is the temperature of the measurement base, ε is the absorptivity of the induction surface, I is the detected incident radiation value, t3 is the air temperature, the magnitude of the output electrical signal of the radiation detection module is obtained from formula (11), and thus the intensity of the direct irradiance is calculated.

[0114] As can be seen from the above description, the present application adopts a two-axis tracking method, which solves the problem that the single-axis fixed detection cannot track in real time and accurately, improves the tracking accuracy of the instrument, realizes more accurate direct radiation measurement, combines the two common tracking methods, solves the influence of photoelectric tracking being susceptible to complex weather and the influence of accumulated errors in the tracking of the apparent solar motion trajectory, and improves the stability and accuracy of the tracking operation detection of the instrument and equipment.

[0115] Those skilled in the art of this technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the art in the field to which this application belongs. It should also be understood that terms defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as here.

[0116] The meaning of "and / or" described in this application refers to the situation where each exists alone or both exist simultaneously.

[0117] The meaning of "connection" described in this application can be a direct connection between components or an indirect connection between components through other components.

[0118] Taking the above ideal embodiments of the present invention as inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A solar direct radiation meter, characterized in that: It includes a stepper motor module, a main control module, a photoelectric detection module, and a radiation detection module (1). The stepper motor module includes an azimuth axis stepper motor (7) and an elevation axis stepper motor (6). The azimuth axis stepper motor (7) is fixed on the base (9), and the motor shaft of the azimuth axis stepper motor (7) is vertically installed at the center of the base (9). Taking the center of the base (9) as the origin, the coordinate plane formed by the X-axis and Y-axis passing through the origin is parallel to the plane of the base (9). The axial direction of the motor shaft of the azimuth axis stepper motor (7) is the Z-axis, thus constructing a three-dimensional coordinate system. The elevation axis stepper motor (6) is arranged at the top of the azimuth axis stepper motor (7) in the Y-axis direction, and the motor shaft of the elevation axis stepper motor (6) is arranged perpendicular to the Z-axis direction. The photoelectric detection module and the radiation detection module (1) are connected to form a detection component, and the motor shaft of the elevation axis stepper motor (6) is connected to the detection component. The main control module is simultaneously connected to the stepper motor module and the detection component. The main control module sends a start command to the azimuth axis stepper motor (7), and the detection component can move within the coordinate plane formed by the X-axis and Y-axis. The main control module sends a start command to the elevation axis stepper motor (6), and the detection component can move within the coordinate planes formed by the X-axis and Z-axis and the Y-axis and Z-axis. The detection component is installed in a cylindrical light tube (2). One end of the cylindrical light tube (2) is installed with the radiation detection module (1). Among them, the radiation detection module (1) includes a lens (14), a sensing surface (15), a thermopile (16), and a measurement base (17). The thermopile (16), the sensing surface (15), and the lens (14) are sequentially stacked on the surface of the measurement base (17), and the lens (14) covers the port at one end of the cylindrical light tube (2). And the lens (14) faces the sun direction. A light tube caster (3) is sleeved on the outer wall of the box body of the cylindrical light tube, and the light tube caster (3) is fixed to the motor shaft of the elevation axis stepper motor (6).

2. The pyrheliometer according to claim 1, characterized in that: The photoelectric detection module is a photoelectric detection sensor, and multiple photoelectric detection sensors are evenly distributed along the circumference of the lens (14).

3. The pyrheliometer according to claim 2, wherein: Four photoelectric detection sensors are set and evenly distributed in the four quadrants along the circumference of the lens (14).

4. The pyrheliometer according to claim 2, characterized in that: The stepper motor module and the main control module are both placed in a square box body (11). The motor shaft of the azimuth axis stepper motor (7) of the stepper motor module extends out of the square box body (11) and is fixed to the base (9). A motor tray (12) is arranged at the bottom inside the square box body (11), and the azimuth axis stepper motor (7) is placed on the motor tray (12).

5. The pyrheliometer according to claim 2, characterized in that: The main control module includes an STM32 microprocessor (8), a stepper motor drive module, a wireless communication module, and a peripheral circuit, and the four are connected. The photoelectric detection module, the radiation detection module (1), and the stepper motor module are simultaneously connected to the main control module, and the stepper motor module is connected to the radiation detection module (1). It also includes a host computer module, which is also connected to the main control module.

6. The pyrheliometer according to claim 5, characterized in that: The wireless communication module selects ZigBee for data transmission.

7. An automatic tracking method for the solar direct irradiance meter according to claim 6, characterized in that: Specifically, it includes the following steps: Step S1: The host computer sends a start command to the main control module via ZigBee wireless communication, obtains the longitude, latitude, and time of the current detection location through the main control module, and calculates the solar hour angle ω. The calculation formula is: ， In formula (1), ω is the solar hour angle, N 0 is the longitude of the current detection location, N ST is the standard longitude adopted for setting the standard time, T 0 is the time of the current detection location, W is the longitude correction coefficient; Step S2: Obtain the longitude, latitude, and time of the current detection location through the main control module, and calculate the solar declination angle δ. The calculation formula is: ， In formula (2), B is the angle of the sun relative to the earth, and , N is the number of days, and the number of days is recorded starting from January 1 of each year; Step S3: Calculate the solar altitude angle and solar azimuth angle based on the solar hour angle and solar declination angle obtained through Step S1 and Step S2, where the formula for the solar altitude angle is as follows: ， In formula (3), δ is the solar declination angle, φ is the latitude angle of the detection location, ω is the solar hour angle; The calculation formula for the solar azimuth angle is: ， In formula (4), is the solar azimuth angle, δ is the solar declination angle, φ is the latitude angle of the detection location, is the solar altitude angle; Step S4: According to Step S3, obtain the solar altitude angle and the solar azimuth angle, and adjust the initial position of the solar direct radiation meter to make it enter the initial state; Step S5: If there is no cumulative error after the initial state tracking, directly obtain the solar direct radiation measurement value. If there is a cumulative error after tracking, proceed to the next step; Step S6: Perform apparent diurnal motion trajectory tracking on direct solar radiation. The sunlight forms a circular light spot within the four photodetectors. The parts of the light spot in the four quadrants are respectively assumed to be I, II, III, and IV, and the electrical signals generated by the photoelectric effect are respectively V Ⅰ , V Ⅱ , V Ⅲ , V Ⅳ . Set the deviation value of the light spot center and the detection component in the coordinate plane formed by the X-axis and the Y-axis to be G xy . The deviation value of the light spot center and the detection component in the coordinate planes formed by the X-axis and the Z-axis, and the Y-axis and the Z-axis is G h . The calculation formulas for the deviation values are respectively: ， Meanwhile, the radiation measurement module obtains the current radiation measurement value and the previous solar radiation measurement value, and calculates the relative change value of the solar direct radiation: ， In formula (6), S1 is the current radiation measurement value, and S0 is the previous solar radiation measurement value; Step S7: Calculate the movement directions of the current azimuth axis stepping motor (7) and the altitude axis stepping motor (6) based on the deviation value obtained in Step S6 and the relative change value of the solar direct radiation, that is ， ， In Formula (7) and Formula (8), a is the weight coefficient of the photoelectric detection sensor (4), taking 0.4, b is the weight coefficient of the solar radiation measurement value, taking 0.6, Dxy is the moving azimuth of the azimuth axis stepping motor (7) in the coordinate plane formed by the X-axis and the Y-axis, Dh is the moving azimuth of the elevation axis stepping motor (6) in the coordinate plane formed by the X-axis and the Z-axis and the coordinate plane formed by the Y-axis and the Z-axis; Step S8: The main control module, according to Dxy and Dh respectively performs a fine step rotation adjustment on the azimuth axis stepper motor (7) and the elevation axis stepper motor (6), and at the same time, respectively performs the detection and calculation of the direct solar radiation value and the photoelectric sensor again Dxy and Dh . If Dxy and Dh change in sign, i.e., direction, the adjustment is stopped respectively until the azimuth angle and the elevation angle are adjusted completely; Step S9: Every 1 minute, repeat the attitude adjustment of the detection component according to Steps S1 - S7 until a solar direct radiation measurement value without error is obtained, and transmit the result to the host computer via ZigBee wireless communication to end the tracking.

8. The automatic tracking method of the pyrheliometer according to claim 7, characterized in that: The specific steps to obtain the solar direct radiation measurement value in Step S9 are: Step S91: The sunlight directly shines on the surface of the lens (14) and is transmitted to the sensing surface (15) through the lens (14). When the sensing surface (15) receives sunlight radiation and reaches relative thermal equilibrium, the calculation formula is ， In Equation (9), K1 is the thermal conductivity conducted to the bottom measurement base (17), and K2 is the thermal conductivity between the air temperature and the induction surface temperature. t 1 is the temperature of the induction surface (15). t 2 is the temperature of the measurement base (17), ε is the absorptivity of the induction surface (15). I is the detected incident radiation value. t 3 is the air temperature. Step S92: Calculate the electromotive force generated by the thermopile (16) by obtaining the temperature difference between the sensing surface (15) and the measurement base (17). The formula is ， In formula (10), I 0 is the thermoelectric end conversion coefficient, with the unit of , t 1 is the temperature of the induction surface (15), t 2 is the temperature of the measurement base (17); Step S93: Combine formula (9) in Step S91 and formula (10) in Step S92 to obtain the calculation formula for the electromotive force signal ， In formula (11), I 0 is the thermoelectric end conversion coefficient, with the unit of , K 1 is the thermal conductivity coefficient conducted to the bottom measurement base (17), K2 is the thermal conductivity coefficient between the air temperature and the induction surface temperature, t 1 is the temperature of the induction surface (15), t 2 is the temperature of the measurement base (17), ε is the absorptivity of the induction surface (15), I is the detected incident radiation value, t 3 is the air temperature. The magnitude of the output electrical signal of the radiation detection module (1) is obtained from formula (11), thereby calculating the intensity of the direct radiance.

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