Method for improving detection accuracy of direct solar radiation and direct radiation meter

Abstract

This invention discloses a method and a direct radiation meter for improving the accuracy of direct solar radiation detection, belonging to the field of meteorological measurement equipment. The direct radiation meter reduces sudden temperature changes caused by direct heating of the meter body by solar radiation by adding a ventilated radiation shield, thereby reducing signal instability and measurement errors. The invention features two alignment holes, one coarse and one fine, above the lens of the direct radiation meter, and an alignment plate located at the rear end of the meter, beneath the ventilated radiation shield. During alignment, the coarse alignment hole is adjusted first, followed by fine adjustment of the fine alignment hole, simplifying the alignment process and increasing accuracy. Furthermore, the invention incorporates a gyroscope and electronic compass inside the direct radiation meter to monitor and automatically record the azimuth and elevation angles in real time. When an anomaly in the azimuth or elevation angle is detected, timely on-site repairs can be performed, and the data can be cleaned and quality controlled later for use.

Description

Technical Field

[0001] This invention belongs to the field of optical and meteorological measurement equipment technology, specifically a method for improving the accuracy of direct solar radiation detection and a direct radiation meter. Background Technology

[0002] Direct solar radiation refers to the radiant energy of sunlight reaching the Earth's surface directly in the form of parallel rays, without being scattered or absorbed by clouds, aerosols, or other particles in the atmosphere. It is a crucial component of the solar radiation received by the Earth's surface, and together with scattered radiation, constitutes the total solar radiation. Monitoring direct radiation is not only a core requirement of the solar energy industry but also a key element in understanding the interaction between the climate system, the ecological environment, and human activities. Its data supports multi-scale research from the microscopic (crop growth) to the macroscopic (global warming) levels, and has broad application value.

[0003] In the prior art, the invention patent with patent publication number CN105004418A discloses a multi-purpose high-precision direct radiation meter. This invention miniaturizes the direct radiation meter, adds a temperature compensation circuit and a heating defrosting function to improve the measurement accuracy, but there are still many problems that need to be improved.

[0004] (1) Temperature compensation is one of the important aspects of improving the detection accuracy of direct radiation meters. However, the method of automatically adjusting circuit parameters through temperature compensation circuit to offset the measurement error caused by temperature changes has many drawbacks, such as: its compensation accuracy is affected by the discreteness of component parameters, making it difficult to achieve high-precision compensation (such as nonlinear temperature drift); the compensation method is fixed, and adjustment requires replacing hardware (such as replacing resistors or thermistors), resulting in poor flexibility; some compensation components are only effective in specific temperature ranges, and the compensation temperature range is limited.

[0005] (2) Heating the direct radiation window area is one of the effective means to eliminate or reduce condensation, frost, ice and snow accumulation on the direct radiation window. Although continuous heating defrosting is a common solution, this method has many disadvantages: it increases operating costs, reduces system endurance, and is not suitable for battery-powered field equipment; in extremely cold and humid environments, 1~1.5W of window heating power is insufficient for complete defrosting; heating may cause temperature fluctuations in the sensor or optical window, affecting the stability of thermistor measurements; continuous heating may also reduce the service life of components, etc.

[0006] (3) None of the direct radiation meters on the market are equipped with a ventilated radiation shield. Under the interaction of sunlight and clouds, the temperature of the meter body will change suddenly in a short time. The thermopile detection unit of the direct radiation meter is based on the Seebeck effect. If the ambient temperature changes suddenly, the temperature difference between its hot end and cold end may fluctuate rapidly, resulting in unstable output signal. Alternatively, the thermal inertia of the thermopile may cause the temperature response of the hot end / cold end to be asynchronous, resulting in instantaneous measurement error.

[0007] (4) The validity of direct radiation meter measurements depends on whether the meter was aligned with the sun during the measurement process. Commercially available direct radiation meters do not include azimuth and elevation angle measurements. Direct radiation meters are typically fixed to a solar tracking device using a fixture, and the fixture is adjusted to ensure the meter is fully aligned with the sun. During long-term continuous use in the field, situations may arise where the fixture becomes loose or the solar tracking device malfunctions. In such cases, the direct radiation meter may not be aligned with the sun or may not be fully aligned, making it impossible to determine the validity of the observed data. This introduces significant uncertainty into the measurement conclusions.

[0008] (5) The accuracy of aligning the direct radiometer with the sun during installation is one of the most critical factors in ensuring the validity of the data. Commercially available direct radiometers typically have a set of alignment holes and an alignment plate. The alignment holes are located above the lens, and the alignment plate is located at the rear of the direct radiometer and has a small dot. When the direct radiometer is aligned with the sun, the sunlight shines through the front alignment holes onto the small dot on the alignment plate. Because the alignment holes are small and the alignment plate is exposed to sunlight, the sunlight dot is not significant, making it difficult to align the direct radiometer with the sun using the adjustment fixture.

[0009] (6) Commercially available direct radiation meters usually do not come with adjustment and alignment tools. These parts are provided by third parties and require repeated adjustments in both horizontal and vertical dimensions to align the direct radiation meter with the sun, which requires a high level of expertise from the operators. Summary of the Invention

[0010] The purpose of this invention is to provide a method and a direct radiation meter for improving the accuracy of direct solar radiation detection, thereby solving the problems of difficult installation and calibration and poor measurement accuracy of existing direct radiation meters.

[0011] The objective of this invention can be achieved through the following technical solutions:

[0012] A direct radiation meter for improving the accuracy of direct solar radiation detection includes a housing, the two ends of which are sealed by a front cover and a rear cover;

[0013] The housing contains a beam slant and a main control circuit. The main control circuit is equipped with a gyroscope and an electronic compass. The main control circuit is used to provide signal processing and control circuitry.

[0014] One end of the beam tube is fitted and fixed to the front cover, and the other end is fixed to the pressure plate by a pressure plate positioning pin. The side of the beam tube has four semi-circular slots for fixing the beam sheets. From the front cover to the rear cover, these four beam sheets have light-transmitting holes with progressively smaller diameters.

[0015] One end of the main control circuit is inserted into the long strip-shaped fixing groove of the fixing plate, and the other end is inserted into the long strip-shaped recessed groove on the back cover. The main control circuit is equipped with a gyroscope and an electronic compass.

[0016] A light collimator is fixed on the front cover; a light spot imaging component is fixed on the rear cover, and the light collimator and the light spot imaging component are respectively fixed to both ends of the ventilation radiation shield.

[0017] The light collimator is provided with an alignment hole, and the light spot imaging device is provided with an imaging hole corresponding to the alignment hole.

[0018] As a further embodiment of the present invention, a recessed hole is provided in the middle of the side of the front cover opposite to the rear cover. The recessed hole portion of the front cover is bonded to the transmissive glass with sealant. A heat-conducting sheet, a heating sheet, and foam cotton are squeezed between the front cover and the transmissive glass.

[0019] As a further embodiment of the present invention, the light collimator is provided with two alignment holes, and the diameters of the two alignment holes are different. The light spot imaging device is provided with two imaging holes, and the two imaging holes correspond to the two alignment holes on the light collimator respectively.

[0020] As a further embodiment of the present invention, the upper part of the ventilated radiation shield has a light spot observation port.

[0021] As a further embodiment of the present invention, a gimbal assembly is fixedly connected to the housing, and the gimbal assembly includes a gimbal fixing ring upper cover and a gimbal fixing ring bottom cover for clamping and fixing the housing.

[0022] The bottom of the gimbal fixing ring is fixedly connected to the upper part of the gimbal sliding protrusion. The bottom of the gimbal sliding protrusion is hemispherical. The raised spherical surface of the gimbal sliding protrusion and the concave surface of the gimbal sliding concave part are closely fitted and can slide against each other to achieve universal adjustment. The other side of the gimbal sliding concave part is fixedly connected to the gimbal locking part. The side of the gimbal locking part opposite to the gimbal sliding concave part is fixed to the gimbal fixing base. The gimbal locking part has a locking screw on its side, which can lock or loosen the gimbal sliding protrusion.

[0023] As a further embodiment of the present invention, the upper part of the bottom cover of the gimbal fixing ring is a semi-circle corresponding to the upper cover of the gimbal fixing ring, and a positioning pin mounting hole is provided on the inner side of the semi-circle of the bottom cover of the gimbal fixing ring. By limiting the position of the gimbal positioning pin, the bottom cover of the gimbal fixing ring is accurately assembled with the housing.

[0024] As a further embodiment of the present invention, a rubber gasket is fitted between the outer side of the housing and the inner side of the gimbal fixing ring upper cover and the gimbal fixing ring bottom cover ring.

[0025] As a further embodiment of the present invention, a recessed hole is provided on the back cover, and a temperature and humidity sensor is fixed in the recessed hole. The temperature and humidity sensor signal is connected to the main control circuit through a cable. A breathable membrane is also attached to the back cover with an adhesive such as silicone to shield the temperature and humidity sensor.

[0026] This application also discloses a method for improving the accuracy of direct solar radiation detection, which is performed using the aforementioned direct radiation table, and includes:

[0027] The larger alignment hole on the collimator is used for coarse adjustment of the light spot during alignment, which quickly locates the position of the light spot. The smaller alignment hole is used for fine adjustment of the light spot, which makes more precise adjustments to the position of the light spot. After the direct radiometer is installed correctly, the two light spots transmitted through the two coarse and fine alignment holes on the collimator fall on the two imaging holes respectively. At this time, the direct radiometer is aligned with the sun.

[0028] Using a gyroscope and electronic compass, the azimuth and elevation angles of the direct radiation meter are monitored and recorded in real time. When an abnormality is found in the azimuth or elevation angle, on-site maintenance is carried out in a timely manner. The data is cleaned before it is used later.

[0029] The system acquires ambient temperature and humidity data through temperature and humidity sensors and calculates the dew point temperature of the air. When frost and dew conditions are present, the heating function is automatically turned on. When the ambient conditions no longer meet the frost and dew conditions, the heating function is automatically turned off or by receiving a command from the host.

[0030] When frosting conditions are detected, the heating power is adjusted according to the ambient temperature; that is, the lower the temperature, the greater the heating power.

[0031] The measurement data is corrected in real time by using embedded software algorithms to eliminate the influence of temperature.

[0032] The beneficial effects of this invention are:

[0033] 1. This invention adds a ventilated radiation shield above the direct radiation meter body, reducing the sudden temperature change caused by direct heating of the meter body by solar radiation, thereby reducing signal instability and measurement error.

[0034] 2. This invention features two alignment holes, one coarse and one fine, above the lens of the direct radiation meter. An alignment plate is located at the rear end of the direct radiation meter, beneath a ventilated radiation shield. During alignment, the coarse alignment hole is adjusted first, followed by fine adjustment of the fine alignment hole, simplifying the alignment process and increasing accuracy. Because the alignment plate is located beneath the radiation shield, it acts as a sunshade, significantly enhancing the light spot on the alignment plate and reducing the difficulty of adjustment.

[0035] 3. This invention adds a gyroscope and an electronic compass inside the direct radiation meter to monitor and automatically record the azimuth and elevation angles of the direct radiation meter in real time. When an abnormality is found in the azimuth or elevation angle, on-site maintenance can be carried out in a timely manner. The data can also be cleaned and quality controlled when used later.

[0036] 4. The direct radiation meter of this invention has a built-in universal adjustment fixture with high precision and good integration, which greatly improves the accuracy and efficiency of adjustment and alignment, and can be easily installed on various tracking systems or platforms.

[0037] 5. This invention uses embedded software algorithms (such as table lookup, polynomial fitting, and machine learning) to correct measurement data in real time, eliminating the influence of temperature. The advantages of this method include: high-precision compensation accuracy through high-calibration and complex algorithm fitting of nonlinear errors; online algorithm updates to adapt to different temperature curves, offering high flexibility; wider temperature compensation range coverage through multi-point calibration; reduced demand for compensation components, saving hardware costs, and suitability for mass production.

[0038] 6. This invention acquires ambient temperature and humidity data through the control unit integrated with the direct radiation meter and calculates the dew point temperature of the air. When frost or dew conditions are present, the heating function is automatically activated, or activated via a command sent from the host computer. When environmental conditions no longer allow for frost or dew formation, the heating function is automatically deactivated, or activated via a command received from the host computer. This intermittent heating function significantly reduces the equipment's energy consumption, making it more suitable for the low-power requirements of field observations.

[0039] 7. When frost conditions are detected, the present invention adjusts the heating power according to the ambient temperature. That is, the lower the temperature, the greater the heating power. This can better solve the problems of dew, frost, and snow removal in extremely cold environments, and can also effectively save the energy consumption of the equipment, making it more suitable for the low power consumption requirements of field observation. Attached Figure Description

[0040] The invention will now be further described with reference to the accompanying drawings.

[0041] Figure 1 This is a schematic diagram of the direct radiation meter of the present invention;

[0042] Figure 2 This is a top view of the direct radiation table of the present invention;

[0043] Figure 3 This is a bottom view of the direct radiation meter of the present invention;

[0044] Figure 4 This is a front view of the direct radiation table of the present invention;

[0045] Figure 5 This is a rear view of the direct radiation table of the present invention;

[0046] Figure 6 This is a cross-sectional view of the direct radiation table of the present invention;

[0047] The diagram is labeled as follows: 1. Hand-tightening screw; 2. Ventilation and radiation shield; 3. Housing; 4. Front cover; 5. Rear cover; 6. Beam collimator; 7. Beam imaging component; 8. Transmitting glass; 9. Heat-conducting sheet; 10. Heating element; 11. Foam cotton; 12. Breathable membrane; 13. Temperature and humidity sensor; 14. Aviation plug; 15. Beam snoot; 16. First beam sheet; 17. Second beam sheet; 18. Third beam sheet; 19. Fourth beam sheet; 20. Pressure plate; 21. Fixing plate; 22. Detector; 23. Main control circuit; 24. Top cover of gimbal fixing ring; 25. Bottom cover of gimbal fixing ring; 26. Gimbal sliding protrusion; 27. Gimbal sliding recess; 28. Gimbal locking component; 29. ​​Gimbal fixing base; 30. Beam collimator fixing hole; 31. Beam imaging component fixing hole; 32. Pressure plate positioning pin; 33. Gimbal positioning pin; 34. Sealing ring; 35. Rubber pad; 36. Limiting groove. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] A direct radiation meter that improves the accuracy of direct solar radiation detection, such as Figures 1 to 6 As shown, it includes a housing 3, with both ends of the housing 3 sealed by a front cover 4 and a rear cover 5. The housing 3 provides stable support and protection for the optical path, detector 22, and main control circuit 23 enclosed by the internal components such as the beam tube 15, and also ensures the dryness and stability of its internal space.

[0050] One side of the front cover 4 is provided with a sealing groove. After the sealing ring 34 is placed in the sealing groove, it is fastened to the end face of the housing 3 by screws. The side of the front cover 4 with the sealing groove is also provided with a limiting protrusion. The limiting protrusion fits into the corresponding limiting groove 36 on the beam tube 15. The other side of the front cover 4 is provided with a recessed hole in the middle. The recessed hole part of the front cover 4 is bonded to the transmission glass 8 with sealant. The heat-conducting sheet 9, the heating sheet 10 and the foam cotton 11 are squeezed between the front cover 4 and the transmission glass 8.

[0051] The front cover 4 is provided with a light collimator fixing hole 30 for positioning the light collimator 6, and then the light collimator 6 is fixed by screws;

[0052] The front cover 4 is used to support the light collimator 6, fix the transmission glass 8 and heating plate, limit the position of the beam tube 15, and seal the housing 3.

[0053] A sealing groove is provided on one side of the rear cover 5. After the sealing ring 34 is placed in the sealing groove, it is fastened to the end face of the housing 3 by screws. A long strip-shaped recessed groove is provided on the other side of the rear cover 5. The long strip-shaped recessed groove is used to hold one end of the main control circuit 23.

[0054] The rear cover 5 is provided with a spot imaging component fixing hole 31 for positioning the spot imaging component 7, and then the spot imaging component 7 is fixed by screws.

[0055] The rear cover 5 is used to support the light spot imaging element 7, fix the main control circuit 23, and seal the housing 3.

[0056] The light collimator 6 is provided with two alignment holes, and the two alignment holes have different diameters. The larger alignment hole is used for coarse adjustment when aligning the light spot, so as to quickly locate the position of the light spot. The adjustment effect is most obvious when the installation angle deviation of the direct radiation meter is large and the sunlight is weak. The smaller alignment hole is used for fine adjustment of the light spot, so as to make more precise adjustment of the position of the light spot.

[0057] The light spot imaging element 7 is provided with two imaging holes, which correspond to the two alignment holes on the light collimator 6. After the direct radiometer is installed correctly, it can be seen that the two light spots transmitted through the two coarse and fine alignment holes on the light collimator 6 fall on the two imaging holes respectively. At this time, the direct radiometer is aligned with the sun.

[0058] The light collimator 6 and the light spot imaging element 7 are fixed at both ends of the ventilation and radiation shield 2 by passing through the through hole on the ventilation and radiation shield 2 with a hand screw 1.

[0059] The upper part of the ventilation and radiation shield 2 has a light spot observation port, which can be used to observe the position of the light spot falling on the light spot imaging element 7.

[0060] The transmission glass 8 is made of a light-transmitting material, such as glass, quartz, acrylic, or other transparent materials, and is used to transmit sunlight to the detector 22.

[0061] The heat-conducting sheet 9 is made of a material with good thermal conductivity, such as metal, and is shaped like a sheet ring. It is tightly attached to the transmission glass 8 by the compression of foam 11, with the heating element 10 sandwiched between the foam 11 and the heat-conducting sheet 9. The heat-conducting sheet 9 is used to transfer the heat of the heating element 10 to the transmission glass 8, and also to shield the heating element 10 from sunlight, preventing direct sunlight from shining on the heating element 10 and extending the service life of the heating element 10.

[0062] During operation, the system acquires ambient temperature and humidity data through the control unit integrated with the direct radiation meter and calculates the dew point temperature of the air. When frost or dew conditions are present, the heating function is automatically activated, or activated via a command sent from the main unit. When environmental conditions no longer allow for frost or dew formation, the heating function is automatically deactivated, or activated via a command received from the main unit. This intermittent heating function significantly reduces the equipment's energy consumption, making it more suitable for the low-power requirements of field observations.

[0063] When frost conditions are detected, this invention adjusts the heating power according to the ambient temperature; that is, the lower the temperature, the greater the heating power. This can better solve the problems of dew, frost, and snow removal in extremely cold environments, and can also effectively save the energy consumption of the equipment, making it more suitable for the low power consumption requirements of field observation.

[0064] The heating element 10 is a PI, PTC, PET, or silicone heating film. The heating element 10 is tightly attached to the heat-conducting sheet 9 by the compression of the foam 11, and the heating element 10 conducts heat to the transmission glass 8 through the heat-conducting sheet 9. The heating element 10 is used to heat the transmission glass 8 and prevent ice, frost, or snow from affecting the light transmission of the transmission glass 8.

[0065] The foam 11 is made of EVA or similar material and is ring-shaped. The foam 11 is bonded to the heating element 10 with adhesive or silicone. The foam 11 is used to compress the heating element 10 so that it adheres tightly to the heat-conducting plate 9 and to separate the heating element 10 from the housing 3, thereby reducing heat loss from the heating element.

[0066] The back cover 5 is provided with a recessed hole, and a temperature and humidity sensor 13 is fixed in the recessed hole. The signal of the temperature and humidity sensor 13 is connected to the main control circuit 23 through a cable. A breathable membrane 12 is also attached to the back cover with adhesives such as silicone to provide waterproof and breathable protection for the temperature and humidity sensor 13.

[0067] The temperature and humidity sensor 13 is used to collect the temperature and humidity in the air and transmit it to the main control circuit 23, so that the main control can perform fine control of heating.

[0068] One end of the beam slant 15 is fixed to the front cover 4 by the limiting groove 36, and the other end of the beam slant 15 is fixed to the pressure plate 20 by the pressure plate positioning pin 32. The side of the beam slant 15 has four semi-circular slots. From the front cover 4 to the rear cover 5, these four semi-circular slots are used to fix the first beam sheet 16, the second beam sheet 17, the third beam sheet 18, and the fourth beam sheet 19, respectively.

[0069] After the beam snoot 15 is tightly fixed to these beams, it is further secured with silicone or other adhesives at the junction of its cylindrical outer surface and the beams to prevent the beams from moving. The beam snoot 15 is used to fix the beams, the pressure plate 20, and the detector 22, keeping the internal components stable and ensuring the collimation of the transmitted light path.

[0070] The first light sheet 16, the second light sheet 17, the third light sheet 18 and the fourth light sheet 19 all have light-transmitting holes in the middle, and the diameter of the light-transmitting holes in the middle gradually decreases from the first light sheet 16 to the fourth light sheet 19.

[0071] Its function is to constrain the angle of light according to the characteristics of detector 22, so that detector 22 receives light within a suitable range of angles.

[0072] The pressure plate 20 is in the shape of a boss. The pressure plate 20 and the fixing plate 21 are fixed by screws. The detector 22 is fixed on the concave surface of the pressure plate 20. The cylindrical sidewall of the concave surface of the pressure plate 20 and the outer surface of the detector 22 are closely fitted to achieve the purpose of initial fixation. The pressure plate 20 is used to fix the detector 22.

[0073] The fixing plate 21 has multiple through holes to facilitate the soldering of the pins of the detector 22. On the other hand, it has a long strip-shaped fixing groove for the main control circuit 23, one end of which can be inserted into the groove to fix the circuit board.

[0074] The detector 22 is a photodetector such as a silicon photodiode or a thermopile, or an array of these components; the detector 22 is fixed by compression or adhesion through a pressure plate 20 and a fixing plate 21. The detector 22 is used to receive direct sunlight and convert it into an electrical signal.

[0075] One end of the main control circuit 23 is inserted into the elongated fixing groove of the fixing plate 21 through a protrusion thereon, and the other end is inserted into the elongated recessed groove on the rear cover 5. The main control circuit 23 is equipped with sensors such as a gyroscope and an electronic compass. The main control circuit 23 is used to provide signal processing and control for sensors such as solar radiation.

[0076] A gimbal assembly is also fixedly installed on the housing 3. The gimbal assembly includes a gimbal fixing ring upper cover 24 and a gimbal fixing ring bottom cover 25 for clamping and fixing the housing 3. The gimbal fixing ring upper cover 24 is semi-circular and has four fixing recessed holes. It is connected to the gimbal fixing ring bottom cover 25 through fixing screw holes for fastening the housing 3.

[0077] The upper part of the gimbal fixing ring bottom cover 25 is a semi-circle corresponding to the gimbal fixing ring upper cover 24. A positioning pin mounting hole is provided on the inner side of the semi-circle of the gimbal fixing ring bottom cover 25. Through the limiting action of the gimbal positioning pin 33, the gimbal fixing ring bottom cover 25 is accurately assembled with the housing 3. Furthermore, the bottom of the gimbal fixing ring bottom cover 25 is connected to the upper part of the gimbal sliding protrusion 26 by screws.

[0078] The upper part of the gimbal sliding protrusion 26 has a nested groove. The gimbal sliding protrusion 26 cooperates with the corresponding nested protrusion on the lower part of the gimbal fixing ring bottom cover 25 through the nested groove and is fixedly connected by screws. The bottom of the gimbal sliding protrusion 26 is a hemispherical surface.

[0079] The gimbal sliding protrusion 26 is connected to the gimbal locking member 28 by screws after it is engaged with the middle protrusion through the through hole in the middle of the bottom. After connection, the convex spherical surface of the gimbal sliding protrusion 26 and the concave surface of the gimbal sliding concave part 27 are closely fitted and can slide against each other to achieve the purpose of universal adjustment.

[0080] One concave surface of the gimbal sliding recess 27 engages with the gimbal sliding protrusion 26 to achieve sliding rotation, while the other surface is a flat, inclined, or other irregularly shaped surface, allowing it to be fastened to the gimbal locking member 28 by means of tapered head screws or sliders, or by means of screw tightening. The gimbal sliding recess 27 supports the rotation of the gimbal sliding protrusion 26, providing a stable fulcrum for the gimbal sliding protrusion 26.

[0081] The gimbal locking member 28 and the gimbal sliding recess 27 are opposite to each other and fixed to the gimbal fixing base 29 by screws. There are hand-tightening screws on its side. By turning the screws, the gimbal sliding recess 27 can be directly squeezed and loosened or the gimbal sliding recess 27 can be squeezed and loosened by the slider, so that the gimbal sliding recess 27 moves slightly up and down, thereby increasing or decreasing the squeezing force on the gimbal sliding protrusion 26. This can lock or loosen the gimbal sliding protrusion 26, so as to realize the angle adjustment and position fixation of the direct radiation body.

[0082] The gimbal locking member 28 is fixedly locked to the gimbal mounting base 29 by screws. The side of the gimbal mounting base 29 opposite to the gimbal locking member 28 is fixed to the observation platform, such as a solar tracker. Its function is to serve as an adapter for fixing the direct radiation meter to the observation platform.

[0083] The pressure plate positioning pin 32 is a machined or commercially available pin, and its dimensions are adapted to the pre-reserved positioning hole of the pressure plate 20 and the limiting groove 36 of the beam slant tube 15, respectively. Its function is to limit the installation angle of the pressure plate 20, thereby controlling the installation angle of the detector 22 and the main control circuit 23.

[0084] The gimbal positioning pin 33 is a machined or commercially available pin with a threaded hole at one end, which can be fixed to the bottom cover 25 of the gimbal fixing ring by screws, serving as an assembly limiting component when the bottom cover 25 of the gimbal fixing ring is connected to the housing 3.

[0085] A silicone or rubber pad 35 is fitted between the outer side of the housing 3 and the inner side of the gimbal fixing ring upper cover 24 and gimbal fixing ring bottom cover 25. The function of the pad is to distribute the large stress generated on the housing 3 when the gimbal fixing ring upper cover 24 and gimbal fixing ring bottom cover 25 are tightened, and to reduce the wear of the gimbal fixing ring upper cover 24 and gimbal fixing ring bottom cover 25 on the surface of the housing 3.

[0086] The direct radiation meter also includes an air plug 14, which is a commercially available air plug that is fixed to a reserved hole in the housing 3 by means of screwing or other methods, or is fixed by pre-embedding in the manufacturing process of the housing 3 or by integral molding with the housing 3.

[0087] This invention adds a gyroscope and an electronic compass inside the direct radiation meter to monitor and automatically record the azimuth and elevation angles of the direct radiation meter in real time. When an abnormality is detected in the azimuth or elevation angle, on-site maintenance can be carried out in a timely manner. The data can also be cleaned and quality controlled when used later.

[0088] The direct radiation meter described in this invention also uses embedded software algorithms (such as table lookup, polynomial fitting, and machine learning) to correct the measurement data in real time, eliminating the influence of temperature. Specifically:

[0089] Before the equipment leaves the factory, multiple correction relationships are established for the radiation detection value (R), detector temperature (T), and correction value (Rc) to eliminate errors caused by temperature changes. These correction relationships can be input into the embedded program before leaving the factory, allowing users to call and adjust them via commands. During equipment observation, the user-defined formulas will be retrieved in real time for error correction. Several common correction relationships are given below:

[0090] 1. Linear Correction Method (Linear Fitting). The relationship between the temperature drift of a thermopile sensor and temperature can be approximated as linear within a certain temperature range. Users can use Formula 1 to correct the device; simply sending a command to the device to modify the k value and Tref will complete the temperature compensation correction.

[0091] Formula 1:

[0092] Where k represents the revision factor, T represents the detector temperature, and Tref represents the reference temperature (a constant, such as 25℃).

[0093] 2. The temperature drift of a thermopile can be considered linear over a small range, but nonlinearity needs to be considered in wide temperature ranges or high-precision scenarios. In this case, a piecewise compensation method (piecewise fitting) can be considered, such as the piecewise temperature drift coefficient of the following detector:

[0094] T = -40℃ ~ 0℃: k = 0.03 ~ 0.04 mV / ℃ (sensitivity decreases in the low-temperature region, and the thermoelectric effect of the material weakens);

[0095] T=0℃~50℃: k=0.05 mV / ℃ (linear optimal range);

[0096] T>50℃: k=0.06~0.07 mV / ℃ (nonlinear changes increase in the high-temperature region);

[0097] The compensation formula at this time is:

[0098] Formula 2:

[0099] Where, k T This represents the revision factor within the corresponding temperature range. For example, k 80℃ =0.07 mV / ℃, Tref=25℃

[0100] This segment k value can be entered into the device before it leaves the factory, or it can be modified by the user by sending a command to the device. More segments can also be added by sending a command.

[0101] 3. Piecewise fitting can easily lead to discontinuities at the points where the data segments connect. To ensure the continuity between data points, polynomial fitting can be used for temperature compensation. Examples of quadratic fitting (Formula 3) and cubic fitting (Formula 4) are given below:

[0102] Formula 3:

[0103] Formula 4:

[0104] Where A1, A2, and A3 are revision coefficients, with A1 corresponding to the linear part and A2 and A3 corresponding to the nonlinear part. In practical use, users can set A1, A2, A3, and Tref via commands, or set higher-value fitting formulas.

[0105] 4. The embedded program of this invention also allows users to send commands to perform common fitting methods such as exponential, logarithmic, and power methods to correct observation errors.

[0106] 5. Lookup table method. For correction relationships that cannot be accurately expressed by fitting formulas, a pre-made lookup table can be input into the embedded program for the observation equipment to retrieve in real time.

[0107] 6. Machine Learning Method. Using machine learning methods to correct the temperature drift of thermopile can significantly improve its measurement accuracy over a wide temperature range, especially when there is a complex nonlinear relationship between temperature drift and temperature. Models such as neural networks and random forests can be selected. The trained model can be deployed to the device's microcontroller before shipment. An example running process is as follows:

[0108] Real-time reading of R and T;

[0109] Call the model to predict the compensation value ΔR;

[0110] Output correction value: Rc = R - ΔR.

[0111] In actual use, users can invoke the model or set the model parameters through commands.

[0112] Without changing the hardware, these algorithms can be updated at any time via firmware, greatly improving the flexibility and environmental adaptability of temperature compensation and enhancing the accuracy of device measurements. These are things that temperature compensation circuits cannot do.

[0113] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A direct radiation meter for improving the accuracy of direct solar radiation detection, comprising a housing, the two ends of which are sealed by a front cover and a rear cover, characterized in that: The housing contains a beam slant and a main control circuit. The main control circuit is equipped with a gyroscope and an electronic compass. The main control circuit is used to provide signal processing and control circuitry. One end of the beam tube is fitted and fixed to the front cover, and the other end is fixed to the pressure plate by a pressure plate positioning pin. The side of the beam tube has four semi-circular slots for fixing the beam sheets. From the front cover to the rear cover, these four beam sheets have light-transmitting holes with progressively smaller diameters. One end of the main control circuit is inserted into the long strip-shaped fixing groove of the fixing plate, and the other end is inserted into the long strip-shaped recessed groove on the back cover. The main control circuit is equipped with a gyroscope and an electronic compass. A light collimator is fixed on the front cover; a light spot imaging component is fixed on the rear cover, and the light collimator and the light spot imaging component are respectively fixed to both ends of the ventilation and radiation shield. The light collimator is provided with an alignment hole, and the light spot imaging device is provided with an imaging hole corresponding to the alignment hole.

2. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 1, characterized in that, A recessed hole is provided in the middle of the side of the front cover opposite to the rear cover. The recessed hole part of the front cover is glued to the transmissive glass with sealant. A heat-conducting sheet, a heating sheet and foam cotton are squeezed between the front cover and the transmissive glass.

3. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 2, characterized in that, The light collimator has two alignment holes with different diameters, and the light spot imaging device has two imaging holes, which correspond to the two alignment holes on the light collimator.

4. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 1, characterized in that, The upper part of the ventilation and radiation shield has a light spot observation port.

5. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 1, characterized in that, A gimbal assembly is fixedly connected to the housing. The gimbal assembly includes a gimbal fixing ring upper cover and a gimbal fixing ring bottom cover for clamping and fixing the housing. The bottom of the gimbal fixing ring is fixedly connected to the upper part of the gimbal sliding protrusion. The bottom of the gimbal sliding protrusion is hemispherical. The raised spherical surface of the gimbal sliding protrusion and the concave surface of the gimbal sliding concave part are closely fitted and can slide against each other to achieve universal adjustment. The other side of the gimbal sliding concave part is fixedly connected to the gimbal locking part. The side of the gimbal locking part opposite to the gimbal sliding concave part is fixed to the gimbal fixing base. The gimbal locking part has a locking screw on its side, which can lock or loosen the gimbal sliding protrusion.

6. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 5, characterized in that, The upper part of the bottom cover of the gimbal fixing ring is a semi-circle corresponding to the upper cover of the gimbal fixing ring. The inner side of the semi-circle of the bottom cover of the gimbal fixing ring is provided with a positioning pin mounting hole. The bottom cover of the gimbal fixing ring is accurately assembled with the housing by the limiting of the gimbal positioning pin.

7. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 5, characterized in that, A rubber gasket is fitted between the outer side of the housing and the inner side of the gimbal fixing ring upper cover and gimbal fixing ring bottom cover ring.

8. A direct radiation meter for improving the accuracy of direct solar radiation detection according to claim 3, characterized in that, The back cover has a recessed hole, in which a temperature and humidity sensor is fixed. The temperature and humidity sensor signal is connected to the main control circuit via a cable. A breathable membrane is also attached to the back cover with adhesives such as silicone to shield the temperature and humidity sensor.

9. A method for improving the accuracy of direct solar radiation detection, characterized in that, The method is performed using a direct radiation table as described in any one of claims 1 to 8, the method comprising: The larger alignment hole on the collimator is used for coarse adjustment of the light spot during alignment, which quickly locates the position of the light spot. The smaller alignment hole is used for fine adjustment of the light spot, which makes more precise adjustments to the position of the light spot. After the direct radiometer is installed correctly, the two light spots transmitted through the two coarse and fine alignment holes on the collimator fall on the two imaging holes respectively. At this time, the direct radiometer is aligned with the sun. Using a gyroscope and electronic compass, the azimuth and elevation angles of the direct radiation meter are monitored and recorded in real time. When an abnormality is found in the azimuth or elevation angle, on-site maintenance is carried out in a timely manner. The data is cleaned before it is used later. The system acquires ambient temperature and humidity data through temperature and humidity sensors and calculates the dew point temperature of the air. When frost and dew conditions are present, the heating function is automatically turned on. When the ambient conditions no longer meet the frost and dew conditions, the heating function is automatically turned off or by receiving a command from the host. When frosting conditions are detected, the heating power is adjusted according to the ambient temperature; that is, the lower the temperature, the greater the heating power. The measurement data is corrected in real time by using embedded software algorithms to eliminate the influence of temperature.

Images