Hydrogen detection circuit and automatic calibration method

Abstract

The invention discloses a hydrogen detection circuit and an automatic calibration method.The hydrogen detection circuit comprises a single-chip microcomputer, a hydrogen sensor, a temperature and humidity sensor, a power module, a data storage module and an output module, and the hydrogen sensor, the temperature and humidity sensor, the power module, the data storage module and the output module are all connected with the single-chip microcomputer; and a signal amplification circuit is connected between the hydrogen sensor and the single chip microcomputer, so that a signal output by the hydrogen sensor is amplified and then input into the single chip microcomputer. According to the hydrogen detection circuit and the automatic calibration method disclosed by the invention, the signal amplification circuit is arranged between the hydrogen sensor and the single chip microcomputer to amplify weak signals of the hydrogen sensor, so that low-concentration hydrogen is detected; and the accuracy of the finally output hydrogen concentration data can be ensured to be higher.

Description

Technical Field

[0001] The invention relates to a hydrogen detection device, and more particularly to a hydrogen detection circuit and an automatic calibration method. Background Art

[0002] At present, monitoring the release of H2 in lithium batteries during thermal runaway is of great significance for early warning of battery thermal runaway. Many domestic and foreign literatures have reported [1,2] that H2 is detected first in battery thermal runaway experiments (639s earlier than smoke and 769s earlier than flame), which strongly proves that introducing H2 gas sensors in battery systems is an effective strategy to prevent thermal runaway in the early stages.

[0003] Existing hydrogen detection circuits basically detect hydrogen gas in a battery system through a hydrogen sensor. Since the ambient temperature has a certain influence on the detection accuracy of the hydrogen sensor, there is an invention patent with a publication number of CN112557595A in the prior art, entitled A Hydrogen Sensor Module Output Automatic Calibration Circuit and Calibration Method. The invention patent discloses a method of improving the output accuracy of the hydrogen sensor by setting a single-chip microcomputer to receive a signal transmitted by the hydrogen sensor and then calibrating the signal for output. However, at present, when the hydrogen concentration is low, the signal output by the hydrogen sensor is relatively low in strength, so it is easily identified as an interference signal by the single-chip microcomputer and calibrated and filtered out. Therefore, the existing hydrogen sensor module and calibration method have the problem of being unable to detect hydrogen with a low concentration. Summary of the invention

[0004] In view of the deficiencies in the prior art, an object of the present invention is to provide a hydrogen detection circuit and an automatic calibration method that can effectively detect hydrogen with a low concentration.

[0005] To achieve the above object, the present invention provides the following technical solution: a hydrogen detection circuit, comprising a single-chip microcomputer, a hydrogen sensor, a temperature and humidity sensor, a power module, a data storage module and an output module, wherein the hydrogen sensor, the temperature and humidity sensor, the power module, the data storage module and the output module are all connected to the single-chip microcomputer, characterized in that a signal amplification circuit is connected between the hydrogen sensor and the single-chip microcomputer to amplify the signal output by the hydrogen sensor and input it into the single-chip microcomputer, and the single-chip microcomputer comprises:

[0006] A digital signal acquisition module, which is connected to the temperature and humidity sensor and is used to receive the temperature and humidity data output by the temperature and humidity sensor;

[0007] An analog signal acquisition module, connected to the signal amplification circuit, for receiving analog detection data output by the hydrogen sensor output by the signal amplification circuit;

[0008] The data processing module is connected to the digital signal acquisition module and the analog signal acquisition module, and is also connected to the output module, and is used to receive the temperature and humidity data output by the digital signal acquisition module and the analog detection data output by the analog signal acquisition module, and output them to the output module after automatic calibration;

[0009] The data calibration module is connected with the data storage module and the data processing module. The data storage module stores a calibration mathematical model, so that the data calibration module can retrieve the calibration mathematical model to the data processing module, so that the data processing model can perform automatic calibration operations.

[0010] As a further improvement of the present invention, the output module includes a CAN communication module, a PWM output module and an analog signal output module, which is used to output the calibrated hydrogen detection signal output by the single-chip microcomputer through CAN communication, PWM signal and analog signal.

[0011] As a further improvement of the present invention, the signal amplification circuit comprises:

[0012] The operational amplifier has a non-inverting input terminal, an inverting input terminal and an output terminal, wherein the non-inverting input terminal is connected to the hydrogen sensor, the inverting input terminal is connected to a resistor R3 and then to ground, and is also connected to a resistor R1 and then to the output terminal, the output terminal is connected to a resistor R2 and then to a single-chip microcomputer, and a capacitor C is also connected between the resistor R2 and the single-chip microcomputer and then to ground.

[0013] Another aspect of the present invention provides a method for calibrating hydrogen concentration data, which specifically includes the following steps: Step 1, receiving temperature and humidity data output by a temperature and humidity sensor through a digital signal acquisition module as environmental data, and receiving analog detection data output by a hydrogen sensor after amplification by a signal amplification circuit through an analog signal acquisition module as hydrogen concentration data;

[0014] Step 2: The data calibration module retrieves the mathematical model stored in the data storage module based on the environmental data and hydrogen concentration data received in step 1 to achieve automatic calibration of the hydrogen concentration data, and then outputs the calibrated hydrogen concentration data through the output module;

[0015] The mathematical model includes baseline drift processing, humidity compensation processing, response function calculation and error correction processing.

[0016] As a further improvement of the above calibration method, the specific method of processing the baseline drift in the mathematical model is as follows: first, according to the baseline resistance change law measured for 10 weeks, the long-term deviation law is calculated:

[0017] y=0.3623x+2.2311

[0018] In the formula, X represents the number of weeks of operation, and y represents the baseline resistance;

[0019] After that, the microcontroller counts when running, and the count value is set to t;

[0020]

[0021] And the running time count in the storage module is increased by one every 1 running hour.

[0022] As a further improvement of the above calibration method, the baseline resistance of the hydrogen sensor under 10%-90% humidity is first measured, and then the function of baseline resistance changing with humidity is fitted:

[0023] y=(901,237)ln(x)+7,076,279

[0024] y=(801,839)ln(x)+6,556,941

[0025] Then get the function trend as:

[0026] Rz=a ln H+b

[0027] Finally, the most accurate baseline curve changing with humidity H is obtained by calibration with the least number of points.

[0028] As a further improvement of the above calibration method, the specific method of calculating the response function in the mathematical model is as follows: firstly, the response value X is calculated:

[0029]

[0030] Then list them according to the linear relationship:

[0031] Y=AX+B

[0032] Where Y is the hydrogen concentration, Rz is the baseline resistance, and Rs is the current sensor response resistance;

[0033] Then extract A and B of the response curve, and list the relationship between A and B and humidity H:

[0034] A=1.3789H+21.832

[0035] B=-15.15H-17.02

[0036] Finally, the mathematical model of the real-time response resistance Rs of hydrogen concentration Y and humidity H is established through the above data:

[0037]

[0038] Rz=a ln H+b

[0039] A=1.3789H+21.832

[0040] B = -15.15H -17.02.

[0041] The hydrogen concentration results are calculated based on the established mathematical model.

[0042] As a further improvement of the present invention, the specific method of the total error correction processing of the mathematical model is: take some key hydrogen concentration points at 50% humidity, 5ppm, 10ppm, and 20ppm, measure the hydrogen concentration results O1, O2, and O3 respectively, as the correction error, and calculate the correction coefficients a, b, and c:

[0043]

[0044] The three coefficients are applied to all humidity ranges to calibrate the correction coefficients. Specifically, take a = 1.25, and determine a correction coefficient line in the range of 0-5ppm through the two points (0,1) and (5,1.25) at two hydrogen concentrations of 0 and 5ppm:

[0045] k=0.05x+1

[0046] Where x represents the hydrogen concentration before correction, k represents the correction coefficient, and the straight line represents the correction value in the range of 0-5ppm. The hydrogen concentration after correction is Y:

[0047] The correction coefficient b when Y=k*x5-10ppm and the correction coefficient c when 10-20ppm are used to correct the hydrogen concentration Y in the same manner as above.

[0048] The beneficial effect of the present invention is that by connecting a signal amplification circuit between the hydrogen sensor and the single-chip microcomputer, the signal amplification circuit can be used to amplify the hydrogen concentration signal output by the hydrogen sensor, so that the single-chip microcomputer is not easy to identify the hydrogen concentration signal as an interference signal, thereby realizing the detection of hydrogen with a low concentration. In addition, by setting a data calibration module in the single-chip microcomputer, the information data in the data storage module can be called as calibration data, further facilitating the data processing module to realize the calibration operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a module block diagram of the hydrogen detection circuit of the present invention;

[0050] Figure 2 A schematic diagram of the process of calibrating the mathematical model;

[0051] Figure 3 Schematic diagram of baseline drift change;

[0052] Figure 4 is a circuit diagram of a signal amplifying circuit;

[0053] Figure 5 is a schematic diagram of the change of baseline resistance with humidity;

[0054] Figure 6 Schematic diagram of 10 and 90% humidity baseline;

[0055] Figure 7 Schematic diagram of 30 and 60% humidity baseline;

[0056] Figure 8 Schematic diagram of 10 and 70% humidity baseline;

[0057] Fig. 9 Schematic diagram of the relationship between hydrogen concentration and response value under different humidity;

[0058] Fig.10 is a schematic diagram of the A value;

[0059] Fig.11 is a schematic diagram of B value;

[0060] Fig.12 Schematic diagram of the correction coefficient results. DETAILED DESCRIPTION

[0061] The present invention will be further described below in detail with reference to the embodiments shown in the accompanying drawings.

[0062] Reference Figure 1 As shown, a hydrogen detection circuit of the present embodiment includes a single chip microcomputer 1, a hydrogen sensor 2, a temperature and humidity sensor 6, a power module 3, a data storage module 4 and an output module 5, wherein the hydrogen sensor 2, the temperature and humidity sensor 6, the power module 3, the data storage module 4 and the output module 5 are all connected to the single chip microcomputer 1, and is characterized in that: a signal amplifying circuit 7 is connected between the hydrogen sensor 2 and the single chip microcomputer 1 to amplify the signal output by the hydrogen sensor 2 and input it into the single chip microcomputer 1, and the single chip microcomputer 1 includes: a digital signal acquisition module 11, which is connected to the temperature and humidity sensor 6 and is used to receive the temperature and humidity data output by the temperature and humidity sensor 6;

[0063] The analog signal acquisition module 12 is connected to the signal amplifying circuit 7 and is used to receive the analog detection data output by the hydrogen sensor 2 output by the signal amplifying circuit 7;

[0064] The data processing module 13 is connected to the digital signal acquisition module 11 and the analog signal acquisition module 12, and is also connected to the output module 5, and is used to receive the temperature and humidity data output by the digital signal acquisition module 11 and the analog detection data output by the analog signal acquisition module 12, and output them to the output module 5 after automatic calibration;

[0065] The data calibration module 8 is connected to the data storage module 4 and the data processing module 13. The data storage module 4 stores a calibration mathematical model, so that the data calibration module 8 can retrieve the calibration mathematical model to the data processing module 13, so that the data processing module 13 can perform automatic calibration operations. The output module 5 includes a CAN communication module 51, a PWM output module 52 and an analog signal output module 53, so as to output the hydrogen concentration in three ways. In actual use, the temperature and humidity sensor 6 obtains environmental parameters, and calculates the impact of the environment on the sensor through the data processing module 13. The signal amplification circuit 7 processes the weak signal on the hydrogen sensor, and amplifies the signal and collects and processes it by the single-chip microcomputer 1. , in order to avoid the problem that the final hydrogen concentration data is inaccurate due to the weak signal causing the data processing module 13 to judge the weak signal on the hydrogen sensor as an interference signal and filter it out. The power module 3 mainly processes the vehicle power system, reduces the power supply voltage to the voltage required for the operation of the single-chip computer 1 and the sensor, and can convert the 12-36V voltage to 3V. The data storage module 4 mainly stores the production information of the sensor module, including the production date, model, and serial number; in addition, it stores the calibration data of the sensor, including sensor operation time, baseline calibration data, humidity processing data, response function, correction coefficient, CAN communication module, PWM output, analog signal output and vehicle-to-vehicle communication, and outputs the current environmental hydrogen concentration in real time.

[0066] Furthermore, this embodiment provides the following calibration process of the data calibration module 8:

[0067] Build the sensor module, power on the sensor module including the hydrogen sensor 2 and the temperature and humidity sensor 6, and make sure the communication is normal;

[0068] The long-term baseline curve of the sensor is recorded in the data storage module. When the sensor module is running, the baseline resistance is corrected in real time according to the running time to obtain the baseline resistance value Z1;

[0069] According to the baseline function measured under 10%-90% humidity, calibrate the relevant parameters of the current sensor baseline function and calculate the current sensor baseline function. Calculate the baseline resistance Z2 according to the current humidity;

[0070] Determine the sensor response function. Determine the sensor response function by measuring the sensor response values ​​at 9 points, 5ppm, 10ppm, and 20ppm, at three humidity levels of 30%, 50%, and 70%.

[0071] Each sensor has a different error. According to the three concentrations of 50%, 5ppm, 10ppm and 20ppm, the error is corrected again, and the correction coefficients a, b and c are calculated. The three coefficients are applied to all humidity ranges respectively.

[0072] Furthermore, this embodiment provides the following circuit structure of the signal amplifying circuit 7: comprising:

[0073] An operational amplifier having a non-inverting input terminal, an inverting input terminal and an output terminal, wherein the non-inverting input terminal is connected to the hydrogen sensor 2, the inverting input terminal is connected to a resistor R3 and then to ground, and is also connected to a resistor R1 and then to the output terminal, the output terminal is connected to a resistor R2 and then to the single-chip computer 1, and a capacitor C1 is also connected between the resistor R2 and the single-chip computer 1 and then to ground, such as Figure 4 As shown, the hydrogen sensor 2 in this embodiment is the same as that in the prior art, and has a load resistor of a response resistor. Figure 4 RHeat is the built-in heating wire of the hydrogen sensor, which is powered by a 3V voltage. Rs is the response resistor, and Rl is the load resistor, which is 5.1kΩ. The operational amplifier uses TI's OPA333AIDBVR precision operational amplifier:

[0074] Based on the circuit structure, the operational amplifier constructs a same-direction signal amplification circuit. The amplification factor β is:

[0075]

[0076] R1 is 10kΩ, R3 is 100Ω, and the calculated result is β=101.

[0077] Amplification factor A:

[0078] A=20×logβ

[0079] A≈40

[0080] Amplified voltage Vout:

[0081] Vout=Vi·β

[0082] The baseline resistance Rz is taken as 4MΩ at 30% humidity, R1 is the load resistance, which is 5.1kΩ, and the circuit voltage is 3V.

[0083]

[0084] Calculate Vi≈1.27×10 -3 V

[0085] Vout≈0.127V, and the 0.127V voltage can be accurately collected in the 12-bit analog-to-digital converter of the microcontroller.

[0086] Therefore, the 12-bit minimum acquisition voltage Vin(min) is:

[0087]

[0088] The minimum acquisition response resistance Rz(min) is:

[0089]

[0090] Vi is 0.03V, β=101

[0091] Rz(min)≈1.5MΩ

[0092] The response resistance is 1.5MΩ. According to the response resistance measured by the actual sensor sample, the upper limit of the collected hydrogen concentration is about 50ppm.

[0093]

[0094] Furthermore, Figure 2 The mathematical model in the data processing module 13 is shown: including baseline drift processing, humidity compensation processing, response function calculation and error correction processing, specifically:

[0095] Baseline drift processing: After the sensor has been running for a long time, without hydrogen response, its resistance value will change according to the running time, such as Figure 3 As shown. After the sensor has been running for a long time, it is necessary to automatically correct the baseline drift. According to the baseline resistance change law measured in 10 weeks, the long-term deviation law is calculated:

[0096] y=0.3623x+2.2311

[0097] x represents the number of weeks of operation, and y represents the baseline resistance.

[0098] The microcontroller counts when it is running, and the count value is set to t;

[0099]

[0100] The running time count in the storage module increases by 1 for every running hour.

[0101] Humidity compensation processing: The baseline resistance of the hydrogen sensor will change regularly under different humidity. By measuring the baseline resistance of the hydrogen sensor under 10%-90% humidity, Figure 5 As shown, the function of baseline resistance changing with humidity is fitted. Figure 5 The fitted curves for the two sensors are shown in:

[0102] y=(901,237)ln(x)+7,076,279

[0103] y=(801,839)ln(x)+6,556,941

[0104] By observing R 2It can be seen that the overall fitting error is small, and the function trend is:

[0105] Rz=a ln H+b

[0106] To obtain the most accurate baseline curve with humidity H by calibrating with the least number of points. Figure 6 , calibrate at 10% humidity and 90% humidity, and record the baseline resistance; Figure 7 , 30% humidity and 60% humidity calibration, record the baseline resistance; Figure 8 , 10% humidity and 70% humidity calibration, record the baseline resistance. It can be concluded that 10% humidity and 70% humidity calibration baseline is the most accurate.

[0107] Response function calculation: The hydrogen sensor will have different response values ​​to hydrogen at different concentrations. The response function determines the relationship between hydrogen at different concentrations and the response value. Fig. 9 It can be seen that when the humidity is fixed, in the range of 0-20ppm, the response value X and the hydrogen concentration are linearly related. 2 It can be seen that the linear error is small. The response value X is:

[0108]

[0109] Listed according to the linear relationship:

[0110] Y=AX+BY is the hydrogen concentration, Rz is the baseline resistance, and Rs is the current sensor response resistance. A and B also change according to a certain rule. Fig. 9 Under different humidity, the A and B of the response curve are extracted and the relationship with humidity is listed. Fig.10 , the relationship between A and humidity H; Fig.11 , the relationship between B and humidity H.

[0111] A=1.3789H+21.832

[0112] B=-15.15H-1 7.02

[0113] The above data can be used to establish the following mathematical model of hydrogen concentration Y and humidity H real-time response resistance Rs:

[0114] Rz=a ln H+b

[0115] A=1.3789H+21.832

[0116] B=-15.15H-1 7.02

[0117] It can be seen from Table 1 that the mathematical model of the above steps has basically accurately calculated the hydrogen concentration result.

[0118] Table 1

[0119]

[0120]

[0121] Due to circuit errors, sensor individual errors, etc., the calculated hydrogen concentration needs to be corrected. Take some key hydrogen concentration points at 50% humidity, 5ppm, 10ppm, and 20ppm, and the measurement results are O1, O2, and O3 respectively, as the correction error, and calculate the correction coefficients a, b, and c:

[0122]

[0123] The three coefficients are applied separately to all humidity ranges to calibrate the correction factors.

[0124] Fig.12 The three points shown in the figure are a, b, and c, which represent the correction coefficients. Take a=1.25, and determine a correction coefficient line in the range of 0-5ppm through the two points (0,1) and (5,1.25) at two hydrogen concentrations of 0 and 5ppm:

[0125] k=0.05x+1

[0126] Where x represents the hydrogen concentration before correction, k represents the correction coefficient, and the straight line represents the correction value in the range of 0-5ppm. The hydrogen concentration after correction is Y:

[0127] Y=k*x

[0128] Similarly, 5-10ppm and 10-20ppm also follow this rule. The correction results are shown in Table 2.

[0129] Table 2

[0130]

[0131] In summary, the hydrogen detection circuit and automatic calibration method of this embodiment can effectively amplify the weak signal output by the hydrogen sensor 2 through the setting of the signal amplification circuit 7, so as to avoid the problem that the data processing module 13 in the single-chip computer 1 identifies the weak signal as an interference signal, resulting in difficulty in detecting low-concentration hydrogen. In this way, quantitative measurement can be achieved under low-concentration hydrogen of 1-20ppm, and battery thermal runaway can be predicted earlier. The novel sensor calibration method avoids environmental interference with the sensor.

[0132] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A hydrogen detection circuit, comprising a single chip microcomputer (1), a hydrogen sensor (2), a temperature and humidity sensor (6), a power module (3), a data storage module (4) and an output module (5), wherein the hydrogen sensor (2), the temperature and humidity sensor (6), the power module (3), the data storage module (4) and the output module (5) are all connected to the single chip microcomputer (1), characterized in that: A signal amplification circuit (7) is connected between the hydrogen sensor (2) and the single-chip computer (1) to amplify the signal output by the hydrogen sensor (2) and then input it into the single-chip computer (1). The single-chip computer (1) comprises: A digital signal acquisition module (11), the digital signal acquisition module (11) being connected to the temperature and humidity sensor (6) and being used to receive temperature and humidity data output by the temperature and humidity sensor (6); An analog signal acquisition module (12) connected to the signal amplification circuit (7) for receiving analog detection data output by the hydrogen sensor (2) output by the signal amplification circuit (7); A data processing module (13) is connected to the digital signal acquisition module (11) and the analog signal acquisition module (12), and is also connected to the output module (5), and is used to receive the temperature and humidity data output by the digital signal acquisition module (11) and the analog detection data output by the analog signal acquisition module (12), and output the data to the output module (5) after automatic calibration; A data calibration module (8) is connected to the data storage module (4) and the data processing module (13); the data storage module (4) stores a calibration mathematical model, so that the data calibration module (8) can retrieve the calibration mathematical model to the data processing module (13), so that the data processing model (13) can perform an automatic calibration operation.

2. The hydrogen detection circuit according to claim 1, characterized in that: The output module (5) comprises a CAN communication module (51), a PWM output module (52) and an analog signal output module (53), and is used to output the calibrated hydrogen detection signal output by the single-chip computer (1) in the form of CAN communication, PWM signal and analog signal.

3. The hydrogen detection circuit according to claim 2, characterized in that: The signal amplifying circuit (7) comprises: An operational amplifier having a non-inverting input terminal, an inverting input terminal and an output terminal, wherein the non-inverting input terminal is connected to a hydrogen sensor (2), the inverting input terminal is connected to a resistor R3 and then to ground, and is also connected to a resistor R1 and then to the output terminal, the output terminal is connected to a resistor R2 and then to a single-chip computer (1), and a capacitor C1 is also connected between the resistor R2 and the single-chip computer (1) and then to ground.

4. An automatic calibration method for automatically calibrating the hydrogen concentration data output by the detection circuit according to any one of claims 1 to 3, the method being built into a signal processing module (13), characterized in that: The specific steps are as follows: Step 1: The temperature and humidity data output by the temperature and humidity sensor (6) is received by the digital signal acquisition module (11) as environmental data, and the analog detection data output by the hydrogen sensor (2) is received by the analog signal acquisition module (12) after being amplified by the signal amplification circuit (7) as hydrogen concentration data; Step 2: The data calibration module (8) retrieves the mathematical model stored in the data storage module (4) based on the environmental data and hydrogen concentration data received in step 1, so as to realize automatic calibration of the hydrogen concentration data, and then outputs the calibrated hydrogen concentration data through the output module (5); The mathematical model includes baseline drift processing, humidity compensation processing, response function calculation and error correction processing.

5. The automatic calibration method according to claim 4, characterized in that: The specific method of processing the baseline drift in the mathematical model is as follows: first, according to the baseline resistance change law measured over 10 weeks, the long-term deviation law is calculated: y=0.3623x+2.2311 In the formula, X represents the number of weeks of operation, and y represents the baseline resistance; After that, the microcontroller counts when running, and the count value is set to t; And the running time count in the storage module is increased by one every 1 running hour.

6. The automatic calibration method according to claim 5, characterized in that: The specific method of humidity compensation processing in the mathematical model is: firstly, the baseline resistance of the hydrogen sensor under 10%-90% humidity is measured, and then the function of the baseline resistance changing with humidity is simulated: y=(901,237)ln(x)+7,076,279 y=(801,839)ln(x)+6,556,941 Then get the function trend as: Rz=aln H+b Finally, the most accurate baseline curve changing with humidity is obtained by calibrating with the least number of points.

7. The automatic calibration method according to claim 6, characterized in that: The specific method of calculating the response function in the mathematical model is as follows: first, calculate the response value X: Then list them according to the linear relationship: Y=AX+B Where Y is the hydrogen concentration, Rz is the baseline resistance, and Rs is the current sensor response resistance; Then extract A and B of the response curve, and list the relationship between A and B and humidity H: A=1.3789H+21.832 B=-15.15H-17.02 Finally, the mathematical model of the real-time response resistance Rs of hydrogen concentration Y and humidity H is established through the above data: Rz=a ln H+b A=1.3789H+21.832 B = -15.15H -17.

02. The hydrogen concentration results are calculated based on the established mathematical model.

8. The automatic calibration method according to claim 7, characterized in that: The specific method of error correction processing in the mathematical model is: take some key hydrogen concentration points at 50% humidity, 5ppm, 10ppm, 20ppm, and the measurement results are O1, O2, O3 respectively, as the correction error, and calculate the correction coefficients a, b, c: The three coefficients are applied to all humidity ranges to calibrate the correction coefficients. Specifically, take a = 1.25, and determine a correction coefficient line in the range of 0-5ppm through the two points (0,1) and (5,1.25) at two hydrogen concentrations of 0 and 5ppm: k=0.05x+1 Where x represents the hydrogen concentration before correction, k represents the correction coefficient, and the straight line represents the correction value in the range of 0-5ppm. The hydrogen concentration after correction is Y: Y=k*x The correction coefficient b at 5-10 ppm and the correction coefficient c at 10-20 ppm are used to correct the hydrogen concentration Y in the same manner as above.

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