Electronic load self-calibration system and method

Abstract

The invention discloses an electronic load self-calibration system and method. The electronic load self-calibration system comprises an electronic load box, an electronic load, a main control board, an acquisition unit, a change-over switch and a reference source, wherein the electronic load, the main control board, the acquisition unit, the change-over switch and the reference source are installed in the electronic load box. The main control board is used for coordinating and controlling the operation of the whole system; the electronic load is used for simulating different load conditions; the acquisition unit is used for acquiring current and voltage signals corresponding to the electronic load in real time, converting the signals into digital signals and transmitting the digital signals to the upper computer; the reference source is used for generating standard current and voltage signals; the change-over switch is used for switching between a working mode and a self-calibration mode; in the working mode, the electronic load is electrically connected with the solar module through a test interface arranged on the electronic load box; and in the self-calibration mode, the electronic load is connected with the reference source, and self-calibration is realized by comparing a measured value of the acquisition unit with a standard value output by the reference source.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic modules, and particularly to an electronic load self-calibration system and method. Background Art

[0002] At present, with the booming development of the solar photovoltaic industry, the electrical performance test of solar cell modules is of crucial importance. As a highly professional instrument, the electronic load system is mainly used in conjunction with a solar simulator to accurately test the electrical performance of solar cell modules. Its working principle is to simulate different load conditions, precisely measure and analyze parameters such as the current and voltage output by the solar cell module, so as to obtain the performance data of the solar cell module under different working conditions, providing key basis for the research and development, quality inspection, etc. of photovoltaic products.

[0003] Currently, the electronic load systems in the industry are usually set to be calibrated once a year. The calibration work aims to ensure the accuracy of the instrument measurement, so that the measurement data can truly reflect the performance of the solar cell module. However, in the actual use process, many factors will affect the measurement accuracy of the electronic load system. For example, temperature is a key factor. When the ambient temperature changes significantly, the characteristics of the electronic components inside the electronic load system will change accordingly, which will cause the parameters of the measurement circuit to drift, and finally lead to deviations in the measurement results.

[0004] Therefore, if only following the traditional method of calibrating once a year, it is difficult to ensure the measurement accuracy of the electronic load system. It is necessary to design an electronic load self-calibration system and method. Summary of the Invention

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] An electronic load self-calibration system includes an electronic load box, and an electronic load, a main control board, a collection unit, a switching switch and a reference source installed in the electronic load box;

[0007] The whole electronic load box is used to test the electrical performance parameters of solar modules;

[0008] The main control board is used to coordinate and control the operation of the whole system;

[0009] The electronic load is used to simulate different load conditions;

[0010] The collection unit is used to collect the current and voltage signals corresponding to the electronic load in real time, and after converting the signals into digital signals, transmit them to the upper computer;

[0011] The reference source is used to generate standard current and voltage signals;

[0012] The switching switch is used to switch between the working mode and the self - calibration mode;

[0013] In the working mode, the electronic load is electrically connected to the solar module through the test interface provided on the electronic load box to obtain the electrical signal output by the solar module;

[0014] In the self - calibration mode, the electronic load is connected to the reference source, and self - calibration is achieved by comparing the measured value of the acquisition unit with the standard value output by the reference source.

[0015] In some embodiments, it further includes a sensor unit for collecting real - time data and transmitting it to the main control board;

[0016] The sensor unit includes:

[0017] An irradiance sensor, which is arranged outside the electronic load box and is used to detect the light intensity of the solar simulator used when testing the solar module;

[0018] An infrared temperature sensor, which is arranged outside the electronic load box and is used to measure the temperature of the back panel of the solar module;

[0019] A temperature and humidity sensor, which is arranged inside the electronic load box and is used to monitor the temperature and humidity inside the electronic load box;

[0020] A position sensor, which is arranged inside the electronic load box and is used to sense the position information of the electronic load box.

[0021] In some embodiments, it further includes a temperature control unit for adjusting the working temperature inside the electronic load box through refrigeration and heating devices according to the instructions sent by the main control board.

[0022] In some embodiments, the temperature control unit includes a thermoelectric cooler and a heating sheet for stabilizing the working temperature inside the electronic load box at 30°C ± 1°C.

[0023] In some embodiments, an indicator light and / or a buzzer are further installed outside the electronic load box.

[0024] On the other hand, the present invention provides an electronic load self - calibration method, which adopts the above - mentioned electronic load self - calibration system and includes the following steps:

[0025] S1. Store the trigger condition of the self - calibration mode in the main control board, so that when the condition is triggered, the switching switch automatically switches to the self - calibration mode;

[0026] S2. In the self - calibration mode, connect the electronic load to the reference source;

[0027] S3. Calculate the deviation values of current and voltage respectively according to the calculation formula \(X = (T_n - B_n) / (T_n + B_n)\times100\%\), where \(T_n\) is the measured value of the acquisition unit, \(B_n\) is the standard value output by the reference source, and \(X\) represents the deviation value.

[0028] S4. Compare the deviation values of current and voltage with a preset threshold. If the deviation values of current and voltage are both not greater than the preset first threshold, no processing is performed, the calibration is completed, and the self - calibration mode ends; otherwise, go to step S5.

[0029] S5. Start the preset calibration process. After completing one calibration process, return to step S3 to recalculate the deviation value until the calibration is completed and the self - calibration mode ends.

[0030] In some embodiments, in step S4, if at least one of the deviation values of current and voltage is greater than the preset second threshold, an alarm is triggered simultaneously, and the staff is prompted to process through the indicator light and / or buzzer installed outside the load box.

[0031] In some embodiments, in step S5, if the number of times of executing the calibration process in a loop reaches the preset value and the calibration is still not completed, an alarm is triggered to prompt the staff to process.

[0032] In some embodiments, in step S1, the triggering conditions of the self - calibration mode include:

[0033] When the electronic load box is powered on, it first automatically performs warm - up. The internal temperature of the electronic load box is adjusted by the temperature control unit. After the warm - up is completed, it automatically enters the self - calibration mode.

[0034] In the powered - on state, when the position sensor inside the electronic load box detects that the position of the electronic load box has changed, it automatically enters the self - calibration mode. After the calibration is completed, it automatically switches back to the working mode.

[0035] In the powered - on state, at every preset interval, it automatically enters the self - calibration mode. After the calibration is completed, it automatically switches back to the working mode.

[0036] In some embodiments, in step S5, after starting the calibration process, the principle of voltage calibration is as follows:

[0037] Express the range of the voltage value collected by the acquisition unit as \(V_{min}\sim V_{max}\), then select the standard values \(V_{ref1}\), \(V_{ref2}\), \(V_{ref3}\) of three calibration points through the following formula:

[0038] \(V_{ref1}=V_{min}+\frac{1}{8}(V_{max}-V_{min})\);

[0039] \(V_{ref2}=V_{min}+\frac{1}{2}(V_{max}-V_{min})\);

[0040] Vref3 = Vmin + 7 / 8(Vmax - Vmin);

[0041] The reference source inputs three standard values into the acquisition unit in sequence, and records the measured values Vmeas1, Vmeas2, and Vmeas3 of the acquisition unit under each standard value;

[0042] For convenience of representation, hereinafter, the three measured values Vmeas1, Vmeas2, and Vmeas3 are respectively represented as x 1 , x 2 , x 3 , and the three standard values Vref1, Vref2, and Vref3 are the corresponding calibrated target values, which are respectively represented as y 1 , y 2 , y 3 ;

[0043] The calibration model is represented by a linear function y = ax + b, where y represents the calibrated value, x represents the measured value of the acquisition unit before calibration, and a and b are coefficients to be solved. a and b are solved according to the least squares method. Specifically:

[0044] Let

[0045] Then there is a system of equations:

[0046] aX 1 + bX 2 = Y 1 ;

[0047] aX 2 + 3b = Y 2 ;

[0048] Thus, it can be solved that:

[0049]

[0050] According to the solved coefficients a and b, subsequently, the measured value of the acquisition system is corrected to the y value calculated by y = ax + b, that is, one calibration process is completed.

[0051] Compared with the prior art, the electronic load self-calibration system and method provided by the present invention are conducive to ensuring the acquisition accuracy of current and voltage through the self-calibration of the electronic load, and significantly improving the measurement accuracy and reliability of the electronic load device. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a schematic diagram of the electronic load self-calibration system provided by the present invention.

[0053] Description of the reference numerals in the drawings:

[0054] 1. Electronic load; 2. Main control board; 3. Acquisition unit; 4. Switch; 5. Reference source; 6. Irradiance sensor; 7. Infrared temperature sensor; 8. Temperature and humidity sensor; 9. Position sensor; 10. Temperature control unit; 11. Test interface; 100. Electronic load box; 200. Solar module; 300. Host computer. Detailed implementation manners

[0055] To make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the following further elaborates how the present invention is implemented in combination with specific implementation manners.

[0056] Referring to Figure 1 As shown, the present invention provides an electronic load self-calibration system, including an electronic load box 100 and an electronic load 1, a main control board 2, an acquisition unit 3, a switch 4 and a reference source 5 installed in the electronic load box 100; the electronic load box 100 is used to test the electrical performance parameters of the solar module 200 as a whole; the main control board 2 is used to coordinate and control the operation of the entire system; the electronic load 1 is used to simulate different load conditions; the acquisition unit 3 is used to collect the current and voltage signals corresponding to the electronic load 1 in real time, and after converting the signals into digital signals, transmit them to the host computer 300; the reference source 5 is used to generate standard current and voltage signals; the switch 4 is used to switch between the working mode and the self-calibration mode; in the working mode, the electronic load 1 is electrically connected to the solar module 200 through the test interface 11 opened on the electronic load box 100 to obtain the electrical signals output by the solar module 200, so as to realize the electrical performance test of the solar cell module 200; in the self-calibration mode, the electronic load 1 is connected to the reference source 5, and by comparing the measured value of the acquisition unit 3 with the standard value of the reference source 5, self-calibration is realized.

[0057] Preferably, the electronic load self-calibration system further includes a sensor unit for collecting real-time data and transmitting it to the main control board 2. Specifically, the sensor unit includes:

[0058] An irradiance sensor 6, arranged outside the electronic load box 100, is used to detect the light intensity of the solar simulator used when testing the solar module 200. The irradiance sensor 6 works based on the photoelectric effect principle. The photosensitive element inside it can convert the received light radiation energy into an electrical signal, and through a specific conversion algorithm, convert this electrical signal into the corresponding light intensity value, so as to monitor the light intensity generated by the solar simulator and transmit the data to the main control board 2 in real time.

[0059] The infrared temperature sensor 7 is set outside the electronic load box 100 and is used to measure the temperature of the backplane of the solar module 200. The infrared temperature sensor 7 utilizes the characteristic that all objects radiate infrared rays, and the energy of the radiated infrared rays is related to the temperature of the object. It detects the infrared ray energy radiated from the surface of the solar module 200, obtains the temperature information of the surface of the solar module 200, and sends the data to the main control board 2.

[0060] The temperature and humidity sensor 8 is set inside the electronic load box 100 and is used to monitor the temperature and humidity inside the electronic load box 100. The humidity detection part usually uses a humidity-sensitive element, whose resistance or capacitance value changes with the change of the ambient humidity, and the humidity data is obtained by measuring this change amount; the temperature detection part generally uses components such as a thermistor, whose resistance value changes with the temperature and is converted into a temperature value through a circuit. The two are combined to monitor the temperature and humidity inside the electronic load box 100 in real time and transmit the data to the main control board 2.

[0061] The position sensor 9 is set inside the electronic load box 100 and is used to sense the position information of the electronic load box 100. The position sensor 9 senses the change of the surrounding magnetic field, and the magnetic-sensitive element captures the signal and converts and analyzes it; it can also sense the inclination angle and convert and analyze it by sensing the change of the gravity acceleration component through an accelerometer. Through the comprehensive induction and analysis of these physical quantities, it can accurately judge whether the position of the electronic load box 100 has changed.

[0062] Preferably, the electronic load self-calibration system further includes a temperature control unit 10, which is used to adjust the working temperature inside the electronic load box 100 through refrigeration and heating devices according to the instructions sent by the main control board 2.

[0063] Specifically, the temperature control unit 10 includes a thermoelectric cooler and a heating sheet, which are used to keep the working temperature inside the electronic load box 100 stable at 30°C ± 1°C. Thereby ensuring that parts such as the reference source 5, the electronic load 1, the acquisition system 3, and the main control board 2 are tested under suitable and stable temperature conditions, and reducing the influence of temperature factors on the test results.

[0064] In addition, an indicator light and / or a buzzer are installed outside the electronic load box 100, which are used to indicate the current working state or send out alarm information.

[0065] In this application, the main control board 2 is the core control unit of the system. It receives real-time data from each sensor, coordinates and controls the operation of the entire system according to the preset algorithm and control logic. At the same time, it sends instructions to the temperature control unit 10 to maintain the stability of the test environment temperature.

[0066] The reference source 5 can select precision devices that have been strictly calibrated by the metrology institute to ensure its accuracy. It is used to generate high-precision and stable current and voltage reference signals, providing a standard reference for current and voltage measurements to ensure the accuracy and reliability of the measurement results.

[0067] The host computer 300 can receive data from the acquisition unit 3, and information transmission between the acquisition unit 3 and the host computer 300 can be achieved through wired or wireless means. In the host computer 300, a large amount of acquired data can be stored, processed, and analyzed using professional data analysis software, and finally, various electrical performance parameters of the solar module 300 are presented in the form of intuitive charts, reports, etc., providing a basis for research and evaluation.

[0068] On the other hand, the present invention provides an electronic load self-calibration method, which uses the above-mentioned electronic load self-calibration system and includes the following steps:

[0069] S1. Store the trigger conditions of the self-calibration mode in the main control board 2, so that when the conditions are triggered, the switching switch 4 automatically switches to the self-calibration mode;

[0070] S2. In the self-calibration mode, connect the electronic load 1 to the reference source 5;

[0071] S3. According to the calculation formula X = (Tn - Bn) / (Tn + Bn)*100%, where Tn is the measured value of the acquisition unit 3, Bn is the standard value of the reference source 5, and X represents the deviation value, calculate the deviation values of current and voltage respectively;

[0072] S4. Compare the deviation values of current and voltage with a preset threshold. If the deviation values of current and voltage are both not greater than the preset first threshold (such as 0.01%), no processing is performed, the calibration is completed, and the self-calibration mode ends. Otherwise, go to step S5;

[0073] S5. Start the preset calibration process. After completing one calibration process, return to step S3 to recalculate the deviation value until the calibration is completed and the self-calibration mode ends.

[0074] Preferably, in step S4, if at least one of the deviation values of current and voltage is greater than the preset second threshold (such as 1%), an alarm is triggered simultaneously, and the staff is prompted to handle it through the indicator light and / or buzzer installed outside the load box.

[0075] In addition, in step S5, if the number of times of executing the calibration process in a loop reaches the preset value (such as 5 times) and the calibration is still not completed, an alarm is triggered to prompt the staff to handle it.

[0076] In a specific embodiment, in step S1, the trigger conditions of the self-calibration mode include:

[0077] When the electronic load box 100 is powered on, it first automatically performs warm-up. The temperature control unit 10 adjusts the internal temperature of the electronic load box 100 so that the operating temperature inside the electronic load box 100 is stabilized at 30°C ± 1°C. After the warm-up is completed, it automatically enters the self-calibration mode.

[0078] In the powered-on state, when the position sensor inside the electronic load box 100 detects a change in the position of the electronic load box 100, it automatically enters the self-calibration mode. After the calibration is completed, it automatically switches back to the working mode.

[0079] In the powered-on state, at every preset time interval (such as 1 hour), it automatically enters the self-calibration mode. After the calibration is completed, it automatically switches back to the working mode.

[0080] In step S5, after starting the calibration process, the principle of voltage calibration is as follows:

[0081] If the range of the voltage value collected by the acquisition unit 3 is expressed as Vmin~Vmax, then the standard values Vref1, Vref2, and Vref3 of the three calibration points are selected through the following formula:

[0082] Vref1 = Vmin + 1 / 8(Vmax - Vmin);

[0083] Vref2 = Vmin + 1 / 2(Vmax - Vmin);

[0084] Vref3 = Vmin + 7 / 8(Vmax - Vmin);

[0085] The reference source 5 sequentially inputs the three standard values into the acquisition unit 3, and records the measured values Vmeas1, Vmeas2, and Vmeas3 of the acquisition unit 3 under each standard value.

[0086] For the convenience of representation, the following will represent the three measured values Vmeas1, Vmeas2, and Vmeas3 as x 1 、x 2 、x 3 , and the three standard values Vref1, Vref2, and Vref3 are the corresponding calibrated target values, which are represented as y 1 、y 2 、y 3 ;

[0087] The calibration model is represented by a linear function y = ax + b, where y represents the calibrated value, x represents the measured value of the acquisition unit 3 before calibration, and a and b are coefficients to be solved. Solve a and b according to the least squares method. Specifically:

[0088] Let

[0089] Then there is a system of equations:

[0090] aX 1 +bX 2 =Y 1 ;

[0091] aX 2 +3b=Y 2 ;

[0092] Thus, it can be solved that:

[0093]

[0094] According to the solved coefficients a and b, the measured values of the acquisition system will be corrected to the y values calculated by y = ax + b subsequently, that is, a calibration process is completed.

[0095] It can be understood that the principle of current calibration is similar to that of voltage calibration, which will not be elaborated here.

[0096] The present invention selects three different standard values using 1 / 8, 1 / 2, and 7 / 8 in the range, which can comprehensively cover the range of the acquisition system, thereby calibrating the acquisition system more accurately.

[0097] Through the above method, the current and voltage acquisition deviation of the electronic load system can always be less than 0.01%, significantly improving the accuracy and reliability of the test.

[0098] In summary, the electronic load self - calibration system and method provided by the present invention, through the self - calibration of the electronic load, is beneficial to ensuring the acquisition accuracy of current and voltage, and significantly improving the accuracy and reliability of the measurement of the electronic load device.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An electronic load self-calibration system, characterized in that: It comprises an electronic load box (100), an electronic load (1), a main control board (2), a collection unit (3), a switch (4) and a reference source (5) installed in the electronic load box (100); The electronic load box (100) is used as a whole to test the electrical performance parameters of the solar energy component (200); The main control board (2) is used to coordinate and control the operation of the entire system; The electronic load (1) is used to simulate different load conditions; The acquisition unit (3) is used to acquire the current and voltage signals corresponding to the electronic load (1) in real time, convert the signals into digital signals, and transmit them to the host computer (300); The reference source (5) is used to generate standard current and voltage signals; The switch (4) is used to switch between the working mode and the self-calibration mode; In the working mode, the electronic load (1) is electrically connected to the solar energy component (200) via a test interface (11) provided on the electronic load box (100) to obtain an electrical signal output by the solar energy component (200); In the self-calibration mode, the electronic load (1) is connected to the reference source (5), and self-calibration is achieved by comparing the measured value of the acquisition unit (3) with the standard value of the reference source (5).

2. The electronic load self-calibration system according to claim 1, characterized in that: It also includes a sensor unit for collecting real-time data and transmitting it to the main control board (2); The sensor unit comprises: An irradiance sensor (6), arranged outside the electronic load box (100), for detecting the light intensity of a solar simulator used when testing a solar energy component (200); An infrared temperature sensor (7), arranged outside the electronic load box (100), and used to measure the temperature of the back plate of the solar module (200); A temperature and humidity sensor (8), arranged in the electronic load box (100) and used to monitor the temperature and humidity in the electronic load box (100); The position sensor (9) is arranged in the electronic load box (100) and is used to sense the position information of the electronic load box (100).

3. The electronic load self-calibration system according to claim 2, characterized in that: It also includes a temperature control unit (10) for adjusting the working temperature inside the electronic load box (100) through cooling and heating equipment according to instructions sent by the main control board (2).

4. The electronic load self-calibration system according to claim 3, characterized in that: The temperature control unit (10) comprises a semiconductor cooling plate and a heating plate, and is used to stabilize the working temperature inside the electronic load box (100) at 30°C±1°C.

5. The electronic load self-calibration system according to claim 1, characterized in that: An indicator light and / or a buzzer are also installed outside the electronic load box (100).

6. An electronic load self-calibration method, characterized in that: The electronic load self-calibration system according to any one of claims 1 to 5 is adopted, and comprises the following steps: S1, storing the triggering condition of the self-calibration mode in the main control board (2), so that when the condition is triggered, the switch (4) automatically switches to the self-calibration mode; S2, in a self-calibration mode, connecting the electronic load (1) to the reference source (5); S3, according to the calculation formula X = (Tn-Bn) / (Tn+Bn) * 100%, where Tn is the measured value of the acquisition unit (3), Bn is the standard value of the reference source (5), and X represents the deviation value, the deviation values ​​of the current and voltage are calculated respectively; S4, comparing the deviation value of the current and voltage with the preset threshold value, if the deviation value of the current and voltage is not greater than the preset first threshold value, no processing is performed, the calibration is completed, and the self-calibration mode ends, otherwise, entering step S5; S5, start the preset calibration process, and after completing the calibration process, return to step S3 to recalculate the deviation value until the calibration is completed, and end the self-calibration mode.

7. The electronic load self-calibration method according to claim 6, characterized in that: In step S4, if at least one of the deviation values ​​of the current and the voltage is greater than a preset second threshold, an alarm is triggered at the same time, and the indicator light and / or buzzer installed outside the load box are used to prompt the staff to handle the problem.

8. The electronic load self-calibration method according to claim 7, characterized in that: In step S5, if the calibration process is executed repeatedly for a preset number of times and the calibration is still not completed, an alarm is triggered to prompt the staff to handle it.

9. The electronic load self-calibration method according to claim 6, characterized in that: In step S1, the triggering conditions of the self-calibration mode include: When the electronic load box (100) is turned on, it first automatically heats up, adjusts the internal temperature of the electronic load box (100) through the temperature control unit (10), and automatically enters a self-calibration mode after the heat-up is completed; In the powered-on state, when the position sensor in the electronic load box (100) detects that the position of the electronic load box (100) has changed, it automatically enters a self-calibration mode, and automatically switches back to a working mode after the calibration is completed; When the power is on, it automatically enters the self-calibration mode at preset intervals and automatically switches back to the working mode after the calibration is completed.

10. The electronic load self-calibration method according to claim 6, characterized in that: In step S5, after the calibration process is started, the principle of voltage calibration is as follows: The range of the voltage value collected by the collection unit (3) is expressed as Vmin to Vmax, and the standard values ​​Vref1, Vref2, and Vref3 of the three calibration points are selected by the following formula: Vref1=Vmin+1 / 8(Vmax-Vmin); Vref2=Vmin+1 / 2(Vmax-Vmin); Vref3=Vmin+7 / 8(Vmax-Vmin); The reference source (5) inputs the three standard values ​​into the acquisition unit (3) in sequence, and records the measurement values ​​Vmeas1, Vmeas2, and Vmeas3 of the acquisition unit (3) under each standard value; For the convenience of representation, the three measured values ​​Vmeas1, Vmeas2, and Vmeas3 are represented as x1, x2, and x3 respectively, and the three standard values ​​Vref1, Vref2, and Vref3 are the corresponding calibrated target values, which are represented as y1, y2, and y3 respectively; The calibration model is represented by a linear function y=ax+b, where y represents the value after calibration, x represents the measurement value of the acquisition unit (3) before calibration, and a and b are coefficients to be solved. A and b are solved according to the least squares method, specifically: set up Then we have the system of equations: aX1+bX2=Y1; aX2+3b=Y2; So we can solve: According to the solved coefficients a and b, the measurement value of the acquisition system is subsequently corrected to the y value after the calculation of y=ax+b, thus completing a calibration process.

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