Palladium alloy hydrogen sensor and temperature compensation method thereof

Abstract

The present invention discloses a palladium alloy hydrogen sensor and a temperature compensation method thereof, wherein the temperature compensation method comprises: introducing N different concentrations of hydrogen into the sensor at a reference temperature, fitting the obtained N groups of hydrogen-sensitive resistance values ​​and hydrogen concentrations, and generating a standard fitting equation; introducing nitrogen, lower concentration hydrogen, and higher concentration hydrogen into the sensor at M different temperatures, and calculating the difference between the hydrogen-sensitive resistance value when different concentrations of hydrogen are introduced at different temperatures and the hydrogen-sensitive resistance value at the reference temperature, generating the first, second, and third fitting equations; obtaining a dynamic compensation equation using the measured real-time temperature and the first, second, and third fitting equations, and then calculating the hydrogen-sensitive resistance compensation value; and calculating the final hydrogen concentration according to the hydrogen-sensitive resistance compensation value and the standard fitting equation. The present invention does not need to heat the sensor when measuring the hydrogen concentration, thereby reducing the power consumption of the sensor when it is used.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sensor production and calibration, and in particular relates to a palladium alloy hydrogen sensor and a temperature compensation method thereof. Background Art

[0002] The production calibration of traditional palladium-nickel alloy thin film hydrogen sensors and the measurement of hydrogen concentration require that the sensor be controlled in a heated constant temperature environment above 80°C to ensure its sensitive and rapid response to hydrogen and stable measurement value output. Without heating and temperature control, it is difficult to obtain the accuracy measurement requirements of the hydrogen sensor due to the discrete characteristics of the hydrogen sensitive core's response to different ambient temperatures and different hydrogen concentrations. The production calibration of hydrogen sensors will inevitably cause high power consumption as long as the heating unit is used. The current required to heat the palladium-nickel alloy thin film hydrogen sensor body to 80°C is as high as 50mA. Therefore, it is not suitable for ultra-low power consumption hydrogen detection, nor can it meet the specific requirements of the two-wire 4mA~20mA transmitter commonly used in industry, because this requires the total power consumption of the sensor to be much lower than 4mA. Summary of the invention

[0003] The object of the present invention is to provide a palladium alloy hydrogen sensor and a temperature compensation method thereof, so as to solve the problem that a conventional palladium-nickel alloy thin film hydrogen sensor consumes high power when measuring hydrogen concentration.

[0004] The present invention solves the above technical problems through the following technical solutions: A temperature compensation method for a palladium alloy hydrogen sensor includes a calibration phase and a measurement phase, wherein the calibration phase includes:

[0005] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to a reference temperature and maintained, and then N hydrogens of different concentrations are introduced into the palladium alloy hydrogen sensor in turn to obtain N groups of hydrogen sensitive resistance values ​​and hydrogen concentrations; the N groups of hydrogen sensitive resistance values ​​and hydrogen concentrations are fitted to generate a standard fitting equation for hydrogen sensitive resistance and hydrogen concentration;

[0006] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and nitrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain nitrogen and hydrogen sensitive resistance values ​​at M different temperatures; the first difference between the hydrogen sensitive resistance value when nitrogen is introduced at M different temperatures and the hydrogen sensitive resistance value when nitrogen is introduced at a reference temperature is calculated respectively, and the first difference at M different temperatures is fitted to generate a first fitting equation; wherein the M different temperatures include the reference temperature;

[0007] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and a relatively low concentration of hydrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the relatively low concentration of hydrogen and the hydrogen sensitive resistance values ​​at M different temperatures; the second difference between the hydrogen sensitive resistance value when the relatively low concentration of hydrogen is introduced at the M different temperatures and the hydrogen sensitive resistance value when the relatively low concentration of hydrogen is introduced at the reference temperature is calculated respectively, and the second difference at the M different temperatures is fitted to generate a second fitting equation; wherein the relatively low concentration of hydrogen is the relatively low concentration of hydrogen among the N different concentrations of hydrogen;

[0008] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and a higher concentration of hydrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the higher concentration of hydrogen and the hydrogen sensitive resistance values ​​at M different temperatures; the third difference between the hydrogen sensitive resistance value when the higher concentration of hydrogen is introduced at the M different temperatures and the hydrogen sensitive resistance value when the higher concentration of hydrogen is introduced at the reference temperature is calculated respectively, and the third difference at the M different temperatures is fitted to generate a third fitting equation; wherein the higher concentration of hydrogen is the higher concentration of hydrogen among the N different concentrations of hydrogen;

[0009] The measurement phase includes:

[0010] The real-time temperature of the hydrogen-sensitive core of the palladium alloy hydrogen sensor is collected, and the dynamic coordinate point at each real-time temperature is obtained according to the real-time temperature, the hydrogen-sensitive resistance value at different hydrogen concentrations at the reference temperature, the first fitting equation, the second fitting equation, and the third fitting equation;

[0011] Fit the dynamic coordinate points at different real-time temperatures to obtain the dynamic compensation equation;

[0012] The hydrogen sensitive resistor compensation value is calculated according to the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor and the dynamic compensation equation;

[0013] The final hydrogen concentration value is obtained according to the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor, the hydrogen sensitive resistor compensation value and the standard fitting equation.

[0014] Furthermore, the reference temperature is 70°C.

[0015] Furthermore, the N different concentrations of hydrogen are 100 ppm, 200 ppm, 400 ppm, 800 ppm, 2000 ppm, 4000 ppm, 8000 ppm, 10000 ppm, 20000 ppm, 40000 ppm, 60000 ppm and 100000 ppm respectively.

[0016] Furthermore, the least square method is used to perform a three-stage fitting of N groups of hydrogen-sensitive resistance values ​​and hydrogen concentrations, and the expression of the standard fitting equation for hydrogen-sensitive resistance and hydrogen concentration is generated as follows:

[0017] Y1=A1x 2 +B1x+C1,Y2=A2x 2 +B2x+C2,Y3=A3x 2 +B3x+C3;

[0018] Among them, x represents the hydrogen sensitive resistor value, Y1, Y2, and Y3 represent the hydrogen concentrations in different fitting segments, and A1, B1, C1, A2, B2, C2, A3, B3, and C3 are the fitting coefficients in different fitting segments.

[0019] Furthermore, the M different temperatures are 30°C, 50°C, 70°C, 90°C, and 110°C respectively.

[0020] Furthermore, the first difference values ​​at M different temperatures are fitted using the least squares method, and the generated first fitting equation is:

[0021] Δx1=a1T s +b1;

[0022] Among them, a1 and b1 are the fitting coefficients of the first fitting equation, T s is the temperature of the hydrogen-sensitive core, Δx1 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when nitrogen is introduced;

[0023] The second difference values ​​at M different temperatures are fitted using the least squares method, and the generated second fitting equation is:

[0024] Δx2=a2T s +b2;

[0025] Wherein, a2 and b2 are the fitting coefficients of the second fitting equation, and Δx2 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when a relatively low concentration of hydrogen is introduced;

[0026] The third difference values ​​at M different temperatures are fitted using the least squares method, and the generated third fitting equation is:

[0027] Δx3=a3T s +b3;

[0028] Wherein, a3 and b3 are fitting coefficients of the third fitting equation, and Δx3 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when a higher concentration of hydrogen is introduced.

[0029] Furthermore, the dynamic coordinate points at each real-time temperature include three, and the three dynamic coordinate points are respectively:

[0030] (X 01 -Δx1,Δx1)、(X02 -Δx2,Δx2)、(X 03 -Δx3,Δx3)

[0031] Among them, X 01 is the hydrogen-sensitive resistance value of the palladium alloy hydrogen sensor when nitrogen is introduced at the reference temperature, Δx1 is the hydrogen-sensitive resistance value caused by the difference between the real-time temperature of the hydrogen-sensitive core and the reference temperature when nitrogen is introduced; X 02 is the hydrogen-sensitive resistance value of the palladium alloy hydrogen sensor when a relatively low concentration of hydrogen is introduced at the reference temperature; Δx2 is the hydrogen-sensitive resistance value caused by the difference between the real-time temperature of the hydrogen-sensitive core and the reference temperature when a relatively low concentration of hydrogen is introduced; X 03 is the hydrogen-sensitive resistance value of the palladium alloy hydrogen sensor when a higher concentration of hydrogen is introduced at the reference temperature, and Δx3 is the hydrogen-sensitive resistance value caused by the difference between the real-time temperature of the hydrogen-sensitive core and the reference temperature when a higher concentration of hydrogen is introduced.

[0032] Based on the same concept, the present invention also provides a palladium alloy hydrogen sensor, including a sensor module, wherein the sensor module includes an algorithm processor, a hydrogen-sensitive resistor, a heating resistor, and a temperature measuring resistor; the hydrogen-sensitive resistor is used to measure the hydrogen-sensitive resistance value when different concentrations of hydrogen are introduced, the heating resistor is used to heat the sensor module according to the instruction of the algorithm processor, and the temperature measuring resistor is used to measure the temperature of the sensor module;

[0033] The algorithm processor is used to calibrate the sensor module and measure the hydrogen concentration according to the temperature compensation method as described above.

[0034] Furthermore, the palladium alloy hydrogen sensor also includes a lithium battery, a functional processor and a wireless transceiver; the lithium battery is connected to the sensor module and the functional processor respectively, and the lithium battery is used to power the sensor; the functional processor is connected to the algorithm processor, and the functional processor is used to control the sensor module to be in working mode or sleep mode; the wireless transceiver module is used for data communication between the functional processor and the wireless data acquisition base station.

[0035] Beneficial Effects

[0036] Compared with the prior art, the advantages of the present invention are:

[0037] Before the palladium alloy hydrogen sensor is used to measure the hydrogen concentration, the present invention first calibrates the palladium alloy hydrogen sensor under reference temperature and different hydrogen concentrations, calibrates the palladium alloy hydrogen sensor under different temperatures and nitrogen (i.e., reference zero point), calibrates the palladium alloy hydrogen sensor under different temperatures and lower hydrogen concentrations, and calibrates the palladium alloy hydrogen sensor under different hydrogen concentrations and higher hydrogen concentrations; then, during measurement, the dynamic coordinate points of the sensor at different real-time temperatures are obtained by using the fitting equation obtained by the calibration, the hydrogen sensitive resistor compensation value is calculated by using the dynamic compensation equation obtained by fitting the dynamic coordinate points, and finally, the final hydrogen concentration is calculated by using the standard fitting equation and the compensated hydrogen sensitive resistor value (i.e., the sum of the measured hydrogen sensitive resistor value and the hydrogen sensitive resistor compensation value), so as to realize accurate measurement of the hydrogen concentration.

[0038] In the actual measurement process, the present invention does not need to use a heating temperature control unit to heat the palladium alloy hydrogen sensor, does not need to consume high power, reduces the total power consumption of the palladium alloy hydrogen sensor during measurement, and can meet the specific requirements of the two-wire 4mA-20mA transmitter commonly used in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is a flow chart of a temperature compensation method for a palladium alloy hydrogen sensor according to an embodiment of the present invention;

[0041] Figure 2 is a flow chart of generating a standard fitting equation in an embodiment of the present invention;

[0042] Figure 3 : is a hardware block diagram of a temperature compensation system of a palladium alloy hydrogen sensor according to an embodiment of the present invention;

[0043] Figure 4 is a standard fitting curve or a reference curve of hydrogen sensitive resistance and hydrogen concentration in the embodiment of the present invention;

[0044] Figure 5 is a characteristic curve of the sensor in the embodiment of the present invention responding to the hydrogen concentration when the temperature is controlled at 50°C and 70°C;

[0045] Figure 6 is a flow chart of generating a first fitting equation in an embodiment of the present invention;

[0046] Figure 7 is a flow chart of generating a second fitting equation in an embodiment of the present invention;

[0047] Figure 8 is a flow chart of generating a third fitting equation in an embodiment of the present invention;

[0048] Fig. 9 is the real-time temperature measured by the temperature measuring resistor when the hydrogen sensor in the embodiment of the present invention is not heated;

[0049] Fig.10 is a hydrogen concentration response curve obtained by the hydrogen sensor in the embodiment of the present invention during the steady temperature drop after the compensation of the present invention;

[0050] Fig.11 1 is a hydrogen sensor response curve of the hydrogen sensor in the embodiment of the present invention when a hydrogen concentration of 4000ppm is introduced under a heating temperature control of 70°C;

[0051] Fig.12 : is the hydrogen sensor response curve of the hydrogen sensor in the embodiment of the present invention when the hydrogen concentration is 4000ppm without temperature control;

[0052] Fig.13 4 is a structural block diagram of a palladium alloy hydrogen sensor in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The following is a clear and complete description of the technical solutions in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The technical solution of the present application is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0055] like Figure 1 As shown, a temperature compensation method for a palladium alloy hydrogen sensor provided by an embodiment of the present invention comprises the following steps:

[0056] Step 1: During the calibration phase, the hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to a reference temperature and maintained, and then N different concentrations of hydrogen are introduced into the palladium alloy hydrogen sensor in turn to obtain N groups of hydrogen sensitive resistance values ​​and hydrogen concentrations; the N groups of hydrogen sensitive resistance values ​​and hydrogen concentrations are fitted to generate a standard fitting equation for hydrogen sensitive resistance and hydrogen concentration.

[0057] Step 2: In the calibration stage, the hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and nitrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the hydrogen sensitive resistance values ​​under nitrogen and M different temperatures; the first difference between the hydrogen sensitive resistance value when nitrogen is introduced at M different temperatures and the hydrogen sensitive resistance value when nitrogen is introduced at the reference temperature is calculated respectively, and the first difference at M different temperatures is fitted to generate a first fitting equation;

[0058] Step 3: In the calibration stage, the hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and a lower concentration of hydrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the lower concentration of hydrogen and the hydrogen sensitive resistance values ​​at M different temperatures; the second difference between the hydrogen sensitive resistance value when the lower concentration of hydrogen is introduced at the M different temperatures and the hydrogen sensitive resistance value when the lower concentration of hydrogen is introduced at the reference temperature is calculated respectively, and the second difference at the M different temperatures is fitted to generate a second fitting equation; wherein the lower concentration of hydrogen is the lower concentration of hydrogen among the N different concentrations of hydrogen;

[0059] Step 4: In the calibration stage, the hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and a higher concentration of hydrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the higher concentration of hydrogen and the hydrogen sensitive resistance values ​​at M different temperatures; the third difference between the hydrogen sensitive resistance value when the higher concentration of hydrogen is introduced at the M different temperatures and the hydrogen sensitive resistance value when the higher concentration of hydrogen is introduced at the reference temperature is calculated respectively, and the third difference at the M different temperatures is fitted to generate a third fitting equation; wherein the higher concentration of hydrogen is the higher concentration of hydrogen among the N different concentrations of hydrogen;

[0060] Step 5: During measurement, the real-time temperature of the hydrogen-sensitive core of the palladium alloy hydrogen sensor is collected, and the dynamic coordinate point at each real-time temperature is obtained according to the real-time temperature, the hydrogen-sensitive resistance value at different hydrogen concentrations at the reference temperature, the first fitting equation, the second fitting equation, and the third fitting equation;

[0061] Step 6: Fit the dynamic coordinate points at different real-time temperatures to obtain the dynamic compensation equation;

[0062] Step 7: Calculate the hydrogen sensitive resistor compensation value based on the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor and the dynamic compensation equation;

[0063] Step 8: Obtain the final hydrogen concentration value based on the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor, the hydrogen sensitive resistor compensation value and the standard fitting equation.

[0064] The compensation method of the present invention comprises a calibration stage and a measurement stage. In the calibration stage, the palladium alloy hydrogen sensor is calibrated to obtain a standard fitting equation, a first fitting equation, a second fitting equation and a third fitting equation. In the measurement stage, the first fitting equation, the second fitting equation and the third fitting equation obtained in the calibration stage are used to obtain a dynamic compensation equation, thereby obtaining a hydrogen-sensitive resistor compensation value, and then the final hydrogen concentration value is calculated using the compensated hydrogen-sensitive resistor value and the standard fitting equation obtained in the calibration stage.

[0065] The following takes a reference temperature of 70°C, N different concentrations of hydrogen of 100ppm, 200ppm, 400ppm, 800ppm, 2000ppm, 4000ppm, 8000ppm, 10000ppm, 20000ppm, 40000ppm, 60000ppm and 100000ppm, and M different temperatures of 30°C, 50°C, 70°C, 90°C and 110°C as an example to illustrate the specific implementation process of the temperature compensation method of the present invention.

[0066] The main characteristics of the palladium-nickel alloy thin film hydrogen sensor: the higher the heating temperature of the main body, the faster the response speed of hydrogen. The hydrogen sensitive resistance value of the main body response is nonlinearly related to the heating temperature. The main body has discrete responses at different temperature points and different hydrogen concentration points. In order to effectively solve the high-precision response measurement needs, the hydrogen sensor needs to be placed at a relative reference temperature. At 70°C, the speed at which the sensor body responds to hydrogen during the calibration stage is appropriate and the temperature drift caused by heating is controllable. Therefore, this embodiment uses 70°C as the reference temperature. Figure 2 As shown, the specific steps to generate the standard fitting equation are:

[0067] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to 70°C and maintained at 70°C, and then 12 kinds (i.e., N=12) of hydrogen with different concentrations are introduced into the palladium alloy hydrogen sensor in turn to obtain 12 sets of hydrogen sensitive resistance values ​​and hydrogen concentrations; the 12 sets of hydrogen sensitive resistance values ​​and hydrogen concentrations are fitted to generate a standard fitting equation for hydrogen sensitive resistance and hydrogen concentration.

[0068] like Figure 3As shown, the main body of the palladium alloy hydrogen sensor includes a hydrogen-sensitive resistor, a temperature-measuring resistor (for measuring the temperature of the hydrogen-sensitive core), and a heating resistor (for heating the hydrogen-sensitive core). Using the constant current source excitation method, the single-chip microcomputer obtains the specific values ​​of the hydrogen-sensitive resistor, the temperature-measuring resistor and the heating resistor, thereby obtaining the hydrogen-sensitive resistor value and the temperature of the hydrogen-sensitive core. The single-chip microcomputer issues a heating or non-heating instruction according to the temperature of the hydrogen-sensitive core and the target temperature (such as the reference temperature), so that the sensor is at different temperatures (including constant temperature and room temperature). The constant temperature is used for sensor production calibration, and the room temperature is used when the sensor is in normal acquisition working mode. Because the sensor does not need to be heated in normal acquisition working mode, the power consumption of the hydrogen sensor is greatly reduced in the same technology industry, and it can be designed as an ultra-low power consumption hydrogen sensor.

[0069] When generating the standard fitting equation, due to the nonlinearity of the hydrogen sensitive resistance value and the hydrogen concentration, the least square method was used to perform multi-segment fitting on 12 sets of hydrogen sensitive resistance values ​​and hydrogen concentrations (as shown in Table 1) (the fitting curve is shown in Figure 4 As shown), the expression of the standard fitting equation for hydrogen sensitive resistance and hydrogen concentration is:

[0070] Y1=A1x 2 +B1x+C1 (1)

[0071] Y2=A2x 2 +B2x+C2 (2)

[0072] Y3=A3x 2 +B3x+C3 (3)

[0073] Wherein, x represents the hydrogen sensitive resistance value, Y1, Y2, and Y3 represent the hydrogen concentration of different fitting segments, and A1, B1, C1, A2, B2, C2, A3, B3, and C3 are the fitting coefficients of different fitting segments. In order to balance the measurement accuracy and calculation amount of hydrogen concentration, this embodiment adopts three-stage fitting.

[0074] Table 112 Hydrogen Sensitive Resistance Values ​​at Hydrogen Concentrations and Reference Temperatures

[0075] Hydrogen concentration (ppm) 70℃ Hydrogen sensitive resistor (Ω) 100 714.35 200 714.55 400 714.89 800 715.53 2000 716.24 4000 717.19 8000 719.04 10000 721.07 20000 723.93 40000 727.98 60000 731.16 100000 736.19

[0076] According to the measured data in Table 1, we can obtain A1=0.015864696, B1=-22.646653205, C1=8,081.951962166; A2=0.021145476, B2=-30.206292115, C2=10,787.430802428; A3=0.019729287, B3=-28.155258842, C3=10,044.825149661. Figure 4The segmentation points of the fitting curve are P0=0.01%, P1=0.08%, P2=1.0%, P3=10.0%, and P0, P1, P2, and P3 are all volume percentages converted from hydrogen concentration points.

[0077] Figure 5 The characteristic curves of the sensor responding to hydrogen concentration at constant temperatures of 50°C and 70°C are shown. From the characteristic curves, it can be seen that the resolution of the hydrogen concentration responded by the sensor at different temperatures is different. The higher the temperature control temperature of the sensor, the lower the resolution of the response to hydrogen concentration. Therefore, for the same hydrogen concentration, the hydrogen-sensitive resistance at different temperatures and the zero point hydrogen-sensitive resistance of the sensor (that is, when nitrogen is introduced) are not of equal difference. From the characteristic curves of the sensor at different temperatures, it can be seen that the higher the temperature, the greater the difference in hydrogen-sensitive resistance. Figure 5 ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, and ΔR6 show increasing differences in turn. Using this rule, it can be concluded that the difference between hydrogen-sensitive resistors at different hydrogen concentrations and temperatures presents a quadratic function rule. Fitting the difference of this rule to generate a quadratic polynomial can obtain the hydrogen-sensitive resistor value that needs to be compensated at different hydrogen concentrations at a known body temperature; then using N2 and two hydrogen concentrations (10000ppm, 100000ppm) as reference points, it is possible to deduce hydrogen concentration values ​​with extremely high output accuracy at different temperatures.

[0078] In order to calculate the change of hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature, according to the ambient temperature requirements of the sensor, the zero point (N2) resistance value, the lower concentration (10000ppm) resistance value and the higher concentration (100000ppm) resistance value of the hydrogen-sensitive resistor of the hydrogen sensor from low temperature to high temperature (30℃, 50℃, 70℃, 90℃, 110℃) are obtained respectively, thereby generating three one-dimensional linear fitting equations (i.e., equations (4) to (6)). Figure 6 As shown, the specific steps for generating the first fitting equation are:

[0079] The hydrogen sensitive core of the palladium alloy hydrogen sensor was heated to 30°C, 50°C, 70°C, 90°C, and 110°C (i.e., M=5), and nitrogen was introduced into the palladium alloy hydrogen sensor at each temperature to obtain the hydrogen sensitive resistance values ​​under nitrogen and 5 different temperatures (as shown in Table 2); the first differences between the hydrogen sensitive resistance values ​​of the palladium alloy hydrogen sensor when nitrogen was introduced at 5 different temperatures and the hydrogen sensitive resistance values ​​of the palladium alloy hydrogen sensor when nitrogen was introduced at 70°C were calculated, and the first differences at 5 different temperatures were fitted by the least squares method, that is, the 5 different temperatures were used as the abscissa and the first difference at each temperature was used as the ordinate to generate the first fitting equation, and the specific expression is:

[0080] Δx1=a1T s+b1 (4)

[0081] Among them, a1 and b1 are the fitting coefficients of the first fitting equation, T s is the temperature of the hydrogen-sensitive core, and Δx1 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when nitrogen is introduced.

[0082] Table 2 Hydrogen sensitive resistance values ​​at 5 different temperatures when nitrogen is introduced

[0083] Sensor body temperature (℃) Hydrogen sensitive resistor (Ω) 110 760.85 90 736.99 70 714.05 50 690.55 30 666.85

[0084] According to the measured data in Table 2, we can obtain: a1 = -1.114801959, b1 = 79.388018523.

[0085] like Figure 7 As shown, the specific steps of generating the second fitting equation are:

[0086] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to 30°C, 50°C, 70°C, 90°C, and 110°C (i.e., M=5), and a relatively low concentration of hydrogen (e.g., 10000ppm) is introduced into the palladium alloy hydrogen sensor at each temperature to obtain 10000ppm hydrogen and hydrogen sensitive resistance values ​​at 5 different temperatures (as shown in Table 3); the second differences between the hydrogen sensitive resistance values ​​when 10000ppm hydrogen is introduced at 5 different temperatures and the hydrogen sensitive resistance values ​​when 10000ppm hydrogen is introduced at 70°C are calculated, and the second differences at 5 different temperatures are fitted by the least squares method, that is, the 5 different temperatures are used as the abscissa and the second difference at each temperature is used as the ordinate to generate a second fitting equation, and the specific expression is:

[0087] Δx2=a2T s +b2 (5)

[0088] Wherein, a2 and b2 are fitting coefficients of the second fitting equation, and Δx2 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when 10000 ppm hydrogen is introduced.

[0089] Table 3 Hydrogen sensitive resistance values ​​at 5 different temperatures when 10000ppm hydrogen is introduced

[0090] Sensor body temperature (℃) Hydrogen sensitive resistor (Ω) 110 788.02 90 742.76 70 721.07 50 699.51 30 678.22

[0091] According to the measured data in Table 3, we can obtain: a2 = -1.025569953, b2 = 72.726982136.

[0092] like Figure 8 As shown, the specific steps of generating the third fitting equation are:

[0093] The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to 30°C, 50°C, 70°C, 90°C, and 110°C (i.e., M=5), and a relatively high concentration of hydrogen (e.g., 100,000 ppm) is introduced into the palladium alloy hydrogen sensor at each temperature to obtain 100,000 ppm hydrogen and hydrogen sensitive resistance values ​​at 5 different temperatures (as shown in Table 4); the third differences between the hydrogen sensitive resistance values ​​when 100,000 ppm hydrogen is introduced at 5 different temperatures and the hydrogen sensitive resistance values ​​when 100,000 ppm hydrogen is introduced at 70°C are calculated, and the third differences at 5 different temperatures are fitted by the least squares method, that is, the 5 different temperatures are used as the abscissa and the third difference at each temperature is used as the ordinate to generate a third fitting equation, and the specific expression is:

[0094] Δx3=a3T s +b3 (6)

[0095] Wherein, a3 and b3 are fitting coefficients of the third fitting equation, and Δx3 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when 100,000 ppm hydrogen is introduced.

[0096] Table 4 Hydrogen sensitive resistance values ​​at 5 different temperatures when 100000ppm hydrogen is introduced

[0097] Sensor body temperature (℃) Hydrogen sensitive resistor (Ω) 110 803.24 90 757.98 70 736.19 50 714.53 30 693.24

[0098] According to the measured data in Table 4, we can obtain: a3 = -1.028918339, b3 = 72.954559530.

[0099] In the actual measurement stage, the dynamic compensation equation is obtained using equations (4) to (6), and the hydrogen sensitive resistor compensation value is calculated using the dynamic compensation equation. The hydrogen sensitive resistor compensation value is then used to compensate the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor to obtain the compensated hydrogen sensitive resistor value. The compensated hydrogen sensitive resistor value is substituted into equations (1) to (3) to calculate the final hydrogen concentration value.

[0100] During the actual measurement phase, the real-time temperature of the hydrogen sensitive core of the palladium alloy hydrogen sensor (such as Fig. 9 As shown in the figure, the real-time temperature measured by the temperature measuring resistor of the hydrogen sensor when the temperature of the body of the hydrogen sensor is steadily decreasing without heating), each real-time temperature is substituted into equations (4) to (6), and the vertical coordinates Δx1, Δx2, and Δx3 of the three dynamic coordinate points at the real-time temperature are obtained. The horizontal coordinates of the dynamic coordinate points are the difference between the hydrogen sensitive resistor value at the reference temperature and the hydrogen sensitive resistor value at the real-time temperature, that is, the horizontal coordinates of the three dynamic coordinate points are X, 01 -Δx1,X 02 -Δx2,X 03 -Δx3, where X 01is the hydrogen sensitive resistance value of the palladium alloy hydrogen sensor when nitrogen is introduced at 70°C (obtained from Table 2); X 02 is the hydrogen sensitive resistance value of the palladium alloy hydrogen sensor when 10000ppm hydrogen is introduced at 70℃ (obtained from Table 3); X 03 is the hydrogen sensitive resistance value of the palladium alloy hydrogen sensor when 100000ppm hydrogen is introduced at 70℃ (obtained from Table 4). Therefore, the three dynamic coordinate points at each real-time temperature are (X 01 -Δx1,Δx1)、(X 02 -Δx2,Δx2)、(X 03 -Δx3,Δx3).

[0101] Taking the hydrogen sensitive resistance value at zero point (N2) under the temperature control of the sensor body at 70℃, the hydrogen sensitive resistance value at a lower concentration (10000ppm), and the hydrogen sensitive resistance value at a higher concentration (100000ppm) as the benchmark hydrogen concentration reference points, the difference between the hydrogen sensitive resistance value of the hydrogen sensor at the current temperature and the hydrogen sensitive resistance value at different hydrogen concentration points under the temperature control of the sensor at 70℃ can be calculated.

[0102] The real-time temperature of each hydrogen-sensitive core corresponds to three dynamic coordinate points. As the real-time temperature of the hydrogen-sensitive core changes, the dynamic coordinate points change. The dynamic relationship between the hydrogen-sensitive resistance value of the hydrogen sensor at a certain temperature point and the hydrogen-sensitive resistance value at different hydrogen concentration points is obtained by using the dynamic coordinate points at different real-time temperatures. The dynamic compensation equation is obtained by fitting the dynamic coordinate points at different real-time temperatures, which is:

[0103] X0=a4x 2 +b4x+c4 (7)

[0104] Wherein, X0 is the hydrogen-sensitive resistor compensation value, x is the measured hydrogen-sensitive resistor value, and a4, b4, and c4 are the fitting coefficients of the dynamic compensation equation. Substitute the hydrogen-sensitive resistor value measured by the hydrogen sensor at the current real-time temperature and hydrogen concentration into formula (7) to obtain the corresponding hydrogen-sensitive resistor compensation value X0; use the hydrogen-sensitive resistor compensation value X0 to compensate the hydrogen-sensitive resistor value measured by the hydrogen sensor at the current real-time temperature and hydrogen concentration to obtain the compensated hydrogen-sensitive resistor value (equal to X0+x), that is, the hydrogen-sensitive resistor value after a series of temperature compensation has been calculated to the standard fitting curve of the sensor at the reference temperature. In this embodiment, the hydrogen-sensitive resistor value x measured at a real-time temperature of 30°C is 674.34.

[0105] Since the compensated hydrogen-sensitive resistance value falls within the segment point P2, the compensated hydrogen-sensitive resistance value (equal to X0+x) is substituted into formula (2), according to Y2=A2(X0+x) 2+B2(X0+x)+C2 calculates the final hydrogen concentration value. The final hydrogen concentration value does not need to be obtained in a temperature-controlled and heated test environment, so the hydrogen concentration can be accurately measured without heating and temperature control of the hydrogen sensor, which greatly reduces power consumption.

[0106] The nonlinear relationship curve of the hydrogen-sensitive resistor in response to different concentrations of hydrogen at a constant temperature is used as a benchmark, and the difference between the hydrogen-sensitive resistor value responding to a certain constant hydrogen concentration at different temperatures and the hydrogen-sensitive resistor value responding to the constant hydrogen concentration at a constant temperature of 70°C is used as a benchmark to calculate the difference between the hydrogen-sensitive resistor value at the current temperature and the hydrogen-sensitive resistor value at 70°C. Because the hydrogen sensor responds to different concentrations of hydrogen at a constant temperature, the difference between the hydrogen-sensitive resistor value at the current temperature and the hydrogen-sensitive resistor value at 70°C is calculated. It is also nonlinear, so it is necessary to use the difference between the hydrogen-sensitive resistor at a constant temperature in response to different hydrogen concentrations, the hydrogen-sensitive resistor value at a constant hydrogen concentration in response to different temperatures, and the hydrogen-sensitive resistor value at a constant temperature of 70°C as a reference, and extrapolate the hydrogen-sensitive resistor value at the current ambient temperature to the curve point of the standard fitting equation at a constant temperature of 70°C; when not calibrated in production, the hydrogen sensor in actual use is in a low-power state, the hydrogen sensor is not temperature-controlled, and the temperature of the sensor body is always changing, so the hydrogen-sensitive resistor value compensation value is to dynamically adjust the dynamic compensation equation in real time according to the change of the sensor body temperature. When the sensor body temperature and hydrogen concentration are both variables, the hydrogen-sensitive resistor response characteristics of the isothermal difference are used to dynamically, real-time, and automatically generate the dynamic compensation equation, and the hydrogen-sensitive resistor value at the real-time temperature is extrapolated to the standard fitting equation after compensation to obtain the current hydrogen concentration measurement value.

[0107] Fig.10 The hydrogen concentration response curve obtained by the hydrogen sensor after compensation by the present invention during the steady temperature drop is shown. Fig.10 It can be seen that during the hydrogen concentration response process, the curve is smooth, the measured hydrogen concentration is 5000ppm, and the sensor can respond to equilibrium in a short time. Fig.11 The hydrogen sensor response curve is shown when the hydrogen concentration is 4000ppm and the hydrogen sensor is heated and controlled at 70℃. Fig.11 It can be seen that after a brief fluctuation in hydrogen concentration, the hydrogen concentration output gradually stabilizes, and the response accuracy meets the accuracy requirements of the hydrogen sensor industry (0.3% + 1% of the indication). Fig.12 The hydrogen sensor response curve is shown when the hydrogen concentration is 4000ppm without temperature control (i.e., the hydrogen sensor is not heated and temperature controlled when in use). Fig.12It can be seen that after a brief fluctuation of hydrogen concentration (due to temperature fluctuation), the hydrogen concentration output gradually stabilizes, and the response accuracy meets the accuracy requirements of the hydrogen sensor industry (0.3% + 1% of the reading). It can be seen that the hydrogen sensitive resistance value of the hydrogen sensor is compensated by the method of the present invention, so that the hydrogen sensor can operate in an ultra-low power consumption mode without temperature control. Through the invention of the present invention, the normal acquisition output of the hydrogen sensor can meet the measurement accuracy required in the industry.

[0108] The method of the present invention is used to compensate the hydrogen-sensitive resistor value, and then the final hydrogen concentration value can be calculated using the compensated hydrogen-sensitive resistor value and the standard fitting equation. The accurate measurement of the hydrogen concentration can be achieved without heating, and the original average power consumption of 2.4W is reduced to 10mW, which greatly reduces the power consumption of the hydrogen sensor when measuring the hydrogen concentration. The hydrogen sensor can be powered by a battery, and combined with a sleep mode when not in use, the battery with a capacity of 1200mAH can be used for more than 3 years.

[0109] like Fig.13 As shown, a palladium alloy hydrogen sensor provided by an embodiment of the present invention includes a lithium battery, an MCU functional processor, a wireless transceiver and a sensor module; formulas (1) to (6) and steps 5 to 8 of the method of the present invention are encapsulated in the MCU functional processor, the sensor module has been calibrated, and the sensor can be in normal measurement mode and sleep mode in conjunction with the I / O pin control of the microprocessor. The sensor module outputs a UART communication interface and is powered by a 3.7V lithium battery. The use of the sensor module to implement the "ultra-low power consumption wireless hydrogen sensor" only requires the addition of a simple peripheral circuit to collect and control the sleep state of the hydrogen sensor module.

[0110] What is disclosed above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, which should be covered within the protection scope of the present invention.

Claims

1. A temperature compensation method for a palladium alloy hydrogen sensor, characterized in that: The temperature compensation method includes a calibration phase and a measurement phase, wherein the calibration phase includes: The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to a reference temperature and maintained, and then N hydrogens of different concentrations are introduced into the palladium alloy hydrogen sensor in turn to obtain N groups of hydrogen sensitive resistance values ​​and hydrogen concentrations; the N groups of hydrogen sensitive resistance values ​​and hydrogen concentrations are fitted to generate a standard fitting equation for hydrogen sensitive resistance and hydrogen concentration; The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and nitrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain nitrogen and hydrogen sensitive resistance values ​​at M different temperatures; the first difference between the hydrogen sensitive resistance value when nitrogen is introduced at M different temperatures and the hydrogen sensitive resistance value when nitrogen is introduced at a reference temperature is calculated respectively, and the first difference at M different temperatures is fitted to generate a first fitting equation; wherein the M different temperatures include the reference temperature; The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and a relatively low concentration of hydrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the relatively low concentration of hydrogen and the hydrogen sensitive resistance values ​​at M different temperatures; the second difference between the hydrogen sensitive resistance value when the relatively low concentration of hydrogen is introduced at the M different temperatures and the hydrogen sensitive resistance value when the relatively low concentration of hydrogen is introduced at the reference temperature is calculated respectively, and the second difference at the M different temperatures is fitted to generate a second fitting equation; The hydrogen sensitive core of the palladium alloy hydrogen sensor is heated to M different temperatures respectively, and a high concentration of hydrogen is introduced into the palladium alloy hydrogen sensor at each temperature to obtain the high concentration of hydrogen and the hydrogen sensitive resistance values ​​at M different temperatures; the third difference between the hydrogen sensitive resistance value when the high concentration of hydrogen is introduced at the M different temperatures and the hydrogen sensitive resistance value when the high concentration of hydrogen is introduced at the reference temperature is calculated respectively, and the third difference at the M different temperatures is fitted to generate a third fitting equation; Wherein, the N different concentrations are 100ppm, 200ppm, 400ppm, 800ppm, 2000ppm, 4000ppm, 8000ppm, 10000ppm, 20000ppm, 40000ppm, 60000ppm and 100000ppm respectively; the higher concentration hydrogen and the lower concentration hydrogen are two concentrations of hydrogen among the N different concentrations, and the concentration of the higher concentration hydrogen is higher than the concentration of the lower concentration hydrogen; The measurement phase includes: The real-time temperature of the hydrogen-sensitive core of the palladium alloy hydrogen sensor is collected, and the dynamic coordinate point at each real-time temperature is obtained according to the real-time temperature, the hydrogen-sensitive resistance value at different hydrogen concentrations at the reference temperature, the first fitting equation, the second fitting equation, and the third fitting equation; Fit the dynamic coordinate points at different real-time temperatures to obtain the dynamic compensation equation; The hydrogen sensitive resistor compensation value is calculated according to the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor and the dynamic compensation equation; The final hydrogen concentration value is obtained according to the hydrogen sensitive resistor value measured by the palladium alloy hydrogen sensor, the hydrogen sensitive resistor compensation value and the standard fitting equation.

2. The temperature compensation method of the palladium alloy hydrogen sensor according to claim 1, characterized in that: The reference temperature is 70°C.

3. The temperature compensation method of the palladium alloy hydrogen sensor according to claim 1, characterized in that: The concentration of the higher concentration hydrogen is 100000 ppm, and the concentration of the lower concentration hydrogen is 10000 ppm.

4. The temperature compensation method of the palladium alloy hydrogen sensor according to claim 1, characterized in that: The least square method is used to perform a three-stage fitting of N groups of hydrogen-sensitive resistor values ​​and hydrogen concentrations. The expression of the standard fitting equation for hydrogen-sensitive resistor and hydrogen concentration is: Y1=A1x 2 +B1x+C1,Y2=A2x 2 +B2x+C2,Y3=A3x 2 +B3x+C3; Among them, x represents the hydrogen sensitive resistor value, Y1, Y2, and Y3 represent the hydrogen concentrations in different fitting segments, and A1, B1, C1, A2, B2, C2, A3, B3, and C3 are the fitting coefficients in different fitting segments.

5. The temperature compensation method of the palladium alloy hydrogen sensor according to claim 1, characterized in that: The M different temperatures are 30°C, 50°C, 70°C, 90°C, and 110°C respectively.

6. The temperature compensation method for a palladium alloy hydrogen sensor according to any one of claims 1 to 5, characterized in that: The first difference values ​​at M different temperatures are fitted using the least squares method, and the generated first fitting equation is: Δx1=a1T s +b1; Among them, a1 and b1 are the fitting coefficients of the first fitting equation, T s is the temperature of the hydrogen-sensitive core, Δx1 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when nitrogen is introduced; The second difference values ​​at M different temperatures are fitted using the least squares method, and the generated second fitting equation is: <h2 style=";text-align:left;direction:ltr">Δx2 = a2T<h2 style=";text-align:left;direction:ltr"> s <h2 style=";text-align:left;direction:ltr"> +b2; Wherein, a2 and b2 are the fitting coefficients of the second fitting equation, and Δx2 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when a relatively low concentration of hydrogen is introduced; The third difference values ​​at M different temperatures are fitted using the least squares method, and the generated third fitting equation is: <h2 style=";text-align:left;direction:ltr">Δx3 = a3T<h2 style=";text-align:left;direction:ltr"> s <h2 style=";text-align:left;direction:ltr"> +b3; Wherein, a3 and b3 are fitting coefficients of the third fitting equation, and Δx3 is the hydrogen-sensitive resistance value caused by the difference between the temperature of the hydrogen-sensitive core and the reference temperature when a higher concentration of hydrogen is introduced.

7. The temperature compensation method of the palladium alloy hydrogen sensor according to claim 6, characterized in that: The dynamic coordinate points at each real-time temperature include three, and the three dynamic coordinate points are respectively: (X 01 -Δx1,Δx1)、(X 02 -Δx2,Δx2)、(X 03 -Δx3,Δx3) Among them, X 01 is the hydrogen-sensitive resistance value of the palladium alloy hydrogen sensor when nitrogen is introduced at the reference temperature, Δx1 is the hydrogen-sensitive resistance value caused by the difference between the real-time temperature of the hydrogen-sensitive core and the reference temperature when nitrogen is introduced; X 02 is the hydrogen-sensitive resistance value of the palladium alloy hydrogen sensor when a relatively low concentration of hydrogen is introduced at the reference temperature; Δx2 is the hydrogen-sensitive resistance value caused by the difference between the real-time temperature of the hydrogen-sensitive core and the reference temperature when a relatively low concentration of hydrogen is introduced; X 03 is the hydrogen-sensitive resistance value of the palladium alloy hydrogen sensor when a higher concentration of hydrogen is introduced at the reference temperature, and Δx3 is the hydrogen-sensitive resistance value caused by the difference between the real-time temperature of the hydrogen-sensitive core and the reference temperature when a higher concentration of hydrogen is introduced.

8. A palladium alloy hydrogen sensor, comprising a sensor module, characterized in that: The sensor module includes an algorithm processor, a hydrogen-sensitive resistor, a heating resistor and a temperature-measuring resistor; the hydrogen-sensitive resistor is used to measure the hydrogen-sensitive resistance value when different concentrations of hydrogen are introduced, the heating resistor is used to heat the sensor module according to the instruction of the algorithm processor, and the temperature-measuring resistor is used to measure the temperature of the sensor module; The algorithm processor is used to calibrate the sensor module and measure the hydrogen concentration according to the temperature compensation method according to any one of claims 1 to 7.

9. The palladium alloy hydrogen sensor according to claim 8, characterized in that: It also includes a lithium battery, a functional processor and a wireless transceiver; the lithium battery is connected to the sensor module and the functional processor respectively, and the lithium battery is used to power the sensor; the functional processor is connected to the algorithm processor, and the functional processor is used to control the sensor module to be in working mode or sleep mode; the wireless transceiver is used for data communication between the functional processor and the wireless data acquisition base station.

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