Method and detection circuit for detecting concentration of multi-component gas

Abstract

The application provides a multi-component gas concentration detection method and detection circuit, belonging to the technical field of gas concentration detection, comprising: obtaining each calibration concentration value and its calibration electric signal corresponding to each heating voltage of any gas; performing linear fitting to determine each slope coefficient and each intercept coefficient; determining a first electric signal calculation formula of any gas; obtaining a corresponding background signal and excitation signal; determining a first electric signal superposition calculation formula of any gas; determining a first multi-component electric signal calculation formula based on the first electric signal calculation formula corresponding to at least two kinds of gases; determining a first multi-component electric signal superposition calculation formula corresponding to the first heating voltage, a second multi-component electric signal superposition calculation formula corresponding to the second heating voltage and a third multi-component electric signal superposition calculation formula corresponding to the third heating voltage; simultaneously solving to determine the concentration value of any gas; without introducing the thermal conductivity of any gas to obtain the gas concentration, the detection precision and efficiency are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas concentration detection, and particularly relates to a detection method and a detection circuit for multi-component gas concentration. BACKGROUND

[0002] Currently, mainstream gas concentration sensors on the market are of non-dispersive infrared optical principle, electrochemical principle or semiconductor principle. Among them, the gas concentration sensors of electrochemical principle or semiconductor principle need a long preheating process before they can work normally. The service life of the gas concentration sensor of electrochemical principle is reduced with the loss of chemical materials. Moreover, the detection accuracy of the current gas concentration sensor is affected by various factors, for example, the multi-component gas concentration solving accuracy is seriously disturbed by background gas, the component gas in the multi-component gas cannot be distinguished, the dynamic response characteristic is not coupled with the temperature excitation strategy, resulting in insufficient detection accuracy.

[0003] Therefore, the multi-component gas concentration detection accuracy in the prior art cannot meet the scene requirements. SUMMARY

[0004] The application aims to provide a detection method and a detection circuit for multi-component gas concentration, and aims to solve the problem that the multi-component gas concentration detection accuracy in the prior art cannot meet the scene requirements.

[0005] A first aspect of the application provides a detection method for multi-component gas concentration, applied to a gas concentration detection circuit, comprising:

[0006] obtaining a first calibration concentration value and a first electric signal corresponding to a first heating voltage of any gas, a second gas concentration value and a second electric signal corresponding to a second heating voltage, and a third gas concentration value and a third electric signal corresponding to a third heating voltage;

[0007] determining a first slope coefficient and a first intercept coefficient based on linear fitting of the first calibration concentration value and the first electric signal of any gas, determining a second slope coefficient and a second intercept coefficient based on linear fitting of the second gas concentration value and the second electric signal of any gas, and determining a third slope coefficient and a third intercept coefficient based on linear fitting of the third gas concentration value and the third electric signal of any gas;

[0008] determining a first electric signal calculation formula of any gas based on the first calibration concentration value, the first electric signal, the first slope coefficient and the first intercept coefficient of any gas;

[0009] obtaining a first background signal and a first excitation signal corresponding to the first heating voltage of any gas;

[0010] determining a first electric signal superposition calculation formula of any gas based on the first background signal, the first excitation signal and the first electric signal calculation formula;

[0011] determining a first multi-component electric signal calculation formula based on the first electric signal calculation formula corresponding to at least two gases respectively;

[0012] determining a first multi-component electric signal superposition calculation formula corresponding to the first heating voltage based on the first electric signal superposition calculation formula and the first multi-component electric signal calculation formula corresponding to at least two gases respectively;

[0013] determining a second multi-component electric signal superposition calculation formula corresponding to the second heating voltage and a third multi-component electric signal superposition calculation formula corresponding to the third heating voltage of at least two gases;

[0014] determining the gas concentration value of any gas in the multi-component gas based on the first multi-component electric signal superposition calculation formula, the second multi-component electric signal superposition calculation formula and the third multi-component electric signal superposition calculation formula.

[0015] The second aspect of the embodiment of the application provides a multi-component gas concentration detection circuit for realizing the multi-component gas concentration detection method in any of the first aspect.

[0016] The heating control circuit comprises a plurality of low-dropout linear voltage stabilizer circuits, and is used for sequentially controlling the low-dropout linear voltage stabilizer circuits to respectively output a plurality of heating voltages to the signal sensing circuit.

[0017] The signal sensing circuit comprises a gas concentration thermocouple chip, and is used for receiving the heating voltages and sensing the concentration change of the multi-component gas in the measured environment. When the multi-component gas concentration changes, the gas concentration thermocouple chip outputs a differential voltage signal corresponding to the multi-component gas concentration change to the signal processing circuit. The differential voltage signal comprises a background signal and an excitation signal. The gas concentration thermocouple chip comprises a sealed first single thermocouple chip and a second single thermocouple chip with a hole.

[0018] The signal processing circuit comprises a microcontroller chip, and is used for driving the heating control circuit to output the plurality of heating voltages, receiving the differential voltage signal of the signal sensing circuit and determining the gas concentration value of each component gas in the multi-component gas through signal processing. The signal processing circuit further comprises a communication interface, and is used for reading the output signal of the gas concentration thermocouple chip and controlling the gas concentration thermocouple chip.

[0019] Compared with the prior art, the embodiment of the application has the following beneficial effects:

[0020] The detection method of the multi-component gas concentration provided by the embodiment of the present application comprises the following steps: obtaining the gas concentration value corresponding to any gas and the first heating voltage and the first electric signal, the gas concentration value corresponding to any gas and the second heating voltage and the second electric signal, and the gas concentration value corresponding to any gas and the third heating voltage and the third electric signal; determining the first slope coefficient and the first intercept coefficient, the second slope coefficient and the second intercept coefficient, and the third slope coefficient and the third intercept coefficient based on the linear fitting of the gas concentration value and the first electric signal of any gas; determining the first electric signal calculation formula of any gas based on the gas concentration value, the first electric signal, the first slope coefficient and the first intercept coefficient of any gas; obtaining the first background signal and the first excitation signal corresponding to any gas and the first heating voltage; determining the first electric signal superposition calculation formula of any gas; determining the first multi-component electric signal calculation formula based on the first electric signal calculation formula corresponding to at least two gases; determining the first multi-component electric signal superposition calculation formula corresponding to the first heating voltage based on the first electric signal superposition calculation formula and the first multi-component electric signal calculation formula corresponding to at least two gases; determining the second multi-component electric signal superposition calculation formula corresponding to the second heating voltage and the third multi-component electric signal superposition calculation formula corresponding to the third heating voltage of at least two gases; and determining the concentration value of any gas in the multi-component gas based on the simultaneous solution of the first multi-component electric signal superposition calculation formula, the second multi-component electric signal superposition calculation formula and the third multi-component electric signal superposition calculation formula. Compared with the prior art, the multi-component gas is heated and calibrated by using multiple heating voltages, the difference in thermal conductivity of the multi-component gas at different temperatures is enhanced, the gas concentration of each component gas is obtained without introducing the thermal conductivity of any gas in the multi-component gas by simultaneously solving multiple multi-component electric signal superposition calculation formulas, the detection mechanism of the multi-temperature step excitation is realized, the gas concentration detection precision and efficiency of the multi-component gas are improved, and the detection cost of the concentration of each component gas in the multi-component gas is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart of the detection method of the multi-component gas concentration provided by the embodiment of the present application is shown in the figure.

[0022] Figure 2 The structural diagram of the detection circuit of the multi-component gas concentration provided by the embodiment of the present application is shown in the figure.

[0023] Figure 3 The example circuit principle diagram of the signal sensing circuit in the detection circuit of the multi-component gas concentration is shown in the figure.

[0024] Figure 4 The example circuit principle diagram of the signal processing circuit in the detection circuit of the multi-component gas concentration is shown in the figure.

[0025] Figure 5 The example circuit principle diagram of the signal processing circuit in the detection circuit of the multi-component gas concentration is shown in the figure. Figure 4An example circuit schematic diagram of a microcontroller chip in the signal processing circuit;

[0026] Figure 6 An example circuit schematic diagram of a first low dropout linear regulator circuit for the heating control circuit;

[0027] Figure 7 An example circuit schematic diagram of a second low dropout linear regulator circuit for the heating control circuit;

[0028] Figure 8 An example circuit schematic diagram of a third low dropout linear regulator circuit for the heating control circuit;

[0029] Figure 9 An example circuit schematic diagram of a fourth low dropout linear regulator circuit for the heating control circuit.

[0030] Reference signs:

[0031] 210, heating control circuit; 220, signal sensing circuit; 230, signal processing circuit;

[0032] U2, low dropout linear regulator chip; D1, first diode; Q2, first field effect transistor; R20, first resistor; R21, second resistor;

[0033] U7, gas concentration thermocouple chip; R1, third resistor; R2, fourth resistor; C6, first capacitor; C7, second capacitor; C8, third capacitor;

[0034] U8, microcontroller chip; C9, fourth capacitor; R3, fifth resistor; R4, sixth resistor; C5, fifth capacitor; J1, burner. DETAILED DESCRIPTION

[0035] The gas concentration sensor currently using electrochemical principle or semiconductor principle needs a long preheating process before it can work normally. The gas concentration sensor using electrochemical principle causes the service life to be reduced due to the loss of chemical materials. The multi-component gas concentration solving precision of the current gas concentration sensor is seriously disturbed by the background gas, cannot distinguish the component gas in the multi-component gas, and the dynamic response characteristic and the temperature excitation strategy are not coupled, causing insufficient detection precision.

[0036] To solve the above technical problems, the application provides a multi-component gas concentration detection method, applied to a gas concentration detection circuit, comprising: obtaining a first calibration concentration value and a first electric signal corresponding to any gas and a first heating voltage, a first calibration concentration value and a second electric signal corresponding to a second heating voltage, and a first calibration concentration value and a third electric signal corresponding to a third heating voltage. Linear fitting is performed based on the first calibration concentration value and the first electric signal of any gas to determine a first slope coefficient and a first intercept coefficient, linear fitting is performed based on the first calibration concentration value and the second electric signal of any gas to determine a second slope coefficient and a second intercept coefficient, and linear fitting is performed based on the first calibration concentration value and the third electric signal of any gas to determine a third slope coefficient and a third intercept coefficient. Based on the first calibration concentration value, the first electric signal, the first slope coefficient and the first intercept coefficient of any gas, a first electric signal calculation formula of any gas is determined. The first background signal and the first excitation signal corresponding to any gas and the first heating voltage are obtained. Based on the first background signal, the first excitation signal and the first electric signal calculation formula, a first electric signal superposition calculation formula of any gas is determined. Based on the first electric signal calculation formula corresponding to at least two gases, a first multi-component electric signal calculation formula is determined. Based on the first electric signal superposition calculation formula and the first multi-component electric signal calculation formula corresponding to at least two gases, a first multi-component electric signal superposition calculation formula corresponding to the first heating voltage is determined. The second multi-component electric signal superposition calculation formula corresponding to the second heating voltage and the third multi-component electric signal superposition calculation formula corresponding to the third heating voltage of at least two gases are determined. Based on the first multi-component electric signal superposition calculation formula, the second multi-component electric signal superposition calculation formula and the third multi-component electric signal superposition calculation formula, the gas concentration value of any gas in the multi-component gas is determined by simultaneous solution.

[0037] In the prior art, the thermal conductivity or electric signal characteristics of multi-component gases at a single temperature overlap, making it difficult to distinguish between components. In comparison with the prior art, the present embodiment enhances the thermal conductivity difference of multi-component gases at different temperatures by using multiple heating voltages (corresponding to multiple different temperatures) to heat and calibrate multi-component gases, thereby achieving the gas concentration of each component gas without introducing the thermal conductivity of any gas in the multi-component gas by simultaneously solving multiple multi-component electric signal superposition calculation formulas, implementing a multi-temperature step excitation detection mechanism, improving the multi-component gas concentration detection efficiency, and reducing the detection cost of the concentration of each component gas in the multi-component gas.

[0038] The technical solutions of the application will be described below through specific embodiments.

[0039] As shown in Figure 1 The first aspect of the application provides a multi-component gas concentration detection method, applied to a gas concentration detection circuit, comprising:

[0040] S100, obtaining a first calibration concentration value and a first electric signal corresponding to the first heating voltage, a first calibration concentration value and a second electric signal corresponding to the second heating voltage, and a first calibration concentration value and a third electric signal corresponding to the third heating voltage.

[0041] In one embodiment, any gas herein refers to a single target gas, which can be oxygen, nitrogen, carbon monoxide or water vapor, and can also be carbon dioxide, sulfur dioxide or any other gas required by the scene according to the actual scene requirements. The method calibrates a single gas in a multi-component gas respectively. The first heating voltage is applied at the first calibration concentration value of the single gas to obtain the first electric signal corresponding to the first heating voltage and the first calibration concentration value of the single gas. The second heating voltage is applied at the first calibration concentration value of the single gas to obtain the second electric signal corresponding to the second heating voltage and the first calibration concentration value of the single gas. The third heating voltage is applied at the first calibration concentration value of the single gas to obtain the third electric signal corresponding to the third heating voltage and the first calibration concentration value of the single gas. Thus, the linear relationship between the gas concentration value, the heating voltage and the electric signal of each single gas is obtained based on the three calibration data.

[0042] S110, determining the first slope coefficient and the first intercept coefficient based on the linear fitting of the first calibration concentration value and the first electric signal of any gas, determining the second slope coefficient and the second intercept coefficient based on the linear fitting of the first calibration concentration value and the second electric signal of any gas, and determining the third slope coefficient and the third intercept coefficient based on the linear fitting of the first calibration concentration value and the third electric signal of any gas.

[0043] In one embodiment, under the same heating voltage, i.e. at the same temperature, there is a corresponding linear relationship between the gas concentration value and the electric signal of any gas. The first slope coefficient and the first intercept coefficient can be determined by linear fitting of the first calibration concentration value and the first electric signal under the first heating voltage. The second slope coefficient and the second intercept coefficient can be determined by linear fitting of the first calibration concentration value and the second electric signal under the second heating voltage. The third slope coefficient and the third intercept coefficient can be determined by linear fitting of the first calibration concentration value and the third electric signal under the third heating voltage. Specifically, the first calibration concentration value has at least two value points, and the values are obtained according to the gas package label purchased, i.e. two calibration concentration values and the first electric signal can be obtained respectively, and a straight line can be determined according to the two points to obtain the first slope coefficient and the first intercept coefficient. In the method, the first calibration concentration value has exactly four value points, which eliminates the label error or measurement error of the purchased gas concentration value.

[0044] S120, determining the first electric signal calculation formula of any gas based on the gas concentration value, the first electric signal, the first slope coefficient and the first intercept coefficient of any gas.

[0045] In one embodiment, the first calibration signal calculation formula of any gas A is:

[0046] rawdata_A1=k_A1xPPM_A+d_A1;

[0047] Wherein, rawdata_A1 is the first electric signal of any gas A; PPM_A is the gas concentration value of any gas A; k_A1 is the first slope coefficient of any gas A; d_A1 is the first intercept coefficient of any gas A.

[0048] Similarly, the second calibration signal calculation formula of any gas A under the second heating voltage is obtained, rawdata_A2=k_A2xPPM_A+d_A2; wherein, rawdata_A2 is the second electric signal of any gas A, k_A2 is the second slope coefficient of any gas A, and d_A2 is the second intercept coefficient of any gas A.

[0049] Similarly, the third calibration signal calculation formula of any gas A under the third heating voltage is rawdata_A3=k_A3xPPM_A+d_A3; wherein, rawdata_A3 is the third electric signal of any gas A, k_A3 is the third slope coefficient of any gas A, and d_A3 is the third intercept coefficient of any gas A.

[0050] After calibration of any gas A in the embodiment, the gas concentration value corresponding to the electric signal can be determined by the electric signal under the known first slope coefficient and first intercept coefficient according to the electric signal calculation formula.

[0051] Similarly, in one embodiment, the multi-component gas includes two single gases, and then the first calibration signal calculation formula of any gas B under the first heating voltage, the second calibration signal calculation formula under the second heating voltage, and the third calibration signal calculation formula under the third heating voltage are obtained.

[0052] In one embodiment, the first calibration signal calculation formula of any gas B is:

[0053] rawdata_B1=k_B1xPPM_B+d_B1;

[0054] Wherein, rawdata_B1 is the first electric signal of any gas B; PPM_B is the gas concentration value of any gas B; k_B1 is the first slope coefficient of any gas B; d_B1 is the first intercept coefficient of any gas B.

[0055] In one embodiment, the second calibration signal calculation of any gas B at the second heating voltage is: rawdata_B2=k_B2xPPM_B+d_B2; wherein rawdata_B2 is the second electric signal of any gas B, k_B2 is the second slope coefficient of any gas B, and d_B2 is the second intercept coefficient of any gas B.

[0056] In one embodiment, the third calibration signal calculation of any gas B at the third heating voltage is: rawdata_B3=k_B3xPPM_B+d_B3; wherein rawdata_B3 is the third electric signal of any gas B, k_B3 is the third slope coefficient of any gas B, and d_B3 is the third intercept coefficient of any gas B.

[0057] Similarly, in another embodiment, three single gases are included in the multi-component gas, then the first calibration signal calculation of any gas B at the first heating voltage, the second calibration signal calculation at the second heating voltage, and the third calibration signal calculation at the third heating voltage are obtained; and the first calibration signal calculation of any gas C at the first heating voltage, the second calibration signal calculation at the second heating voltage, and the third calibration signal calculation at the third heating voltage are obtained.

[0058] In one embodiment, the first calibration signal calculation of any gas C is:

[0059] rawdata_C1=k_C1xPPM_C+d_C1;

[0060] wherein rawdata_C1 is the first electric signal of any gas C, PPM_C is the gas concentration value of any gas C, k_C1 is the first slope coefficient of any gas C, and d_C1 is the first intercept coefficient of any gas C.

[0061] In one embodiment, the second calibration signal calculation of any gas C at the second heating voltage is: rawdata_C2=k_C2xPPM_C+d_C2; wherein rawdata_C2 is the second electric signal of any gas C, k_C2 is the second slope coefficient of any gas C, and d_C2 is the second intercept coefficient of any gas C.

[0062] In one embodiment, the third calibration signal calculation of any gas C at the third heating voltage is: rawdata_C3=k_C3xPPM_C+d_C3; wherein rawdata_C3 is the third electric signal of any gas C, k_C3 is the third slope coefficient of any gas C, and d_C3 is the third intercept coefficient of any gas C.

[0063] It should be noted that, in the calibration step of the signal sensing circuit (specifically, the calibration of the gas concentration thermocouple chip) in the multi-component gas concentration detection circuit of this application, the single gas used is a single gas of any component used for dedicated calibration. Multiple values ​​of the first calibrated concentration of a single gas can be calibrated multiple times with the same heating voltage to obtain the electrical signal corresponding to the single heating voltage, thereby obtaining the slope coefficient and intercept coefficient corresponding to the single calibration with the same heating voltage. Furthermore, a single gas concentration value can be calibrated multiple times with different heating voltages to obtain the electrical signal corresponding to any heating voltage, thereby obtaining the slope coefficient and intercept coefficient corresponding to any heating voltage for a single gas. In addition, based on the above two calibration methods, each concentration value of a single gas can be calibrated multiple times with the same and / or different heating voltages to obtain the electrical signal corresponding to the single heating voltage for a single gas concentration value and / or the electrical signal corresponding to any heating voltage for each concentration value of a single gas, thereby obtaining the slope coefficient and intercept coefficient corresponding to the single heating voltage and / or the slope coefficient and intercept coefficient corresponding to any heating voltage.

[0064] S130, acquire the first background signal and the first excitation signal corresponding to any gas and the first heating voltage.

[0065] In one embodiment, under the same gas and heating voltage, the electrical signal responded by the gas concentration detection circuit is the superposition of the background signal and the gas excitation signal. Therefore, the sum of the first background signal and the first excitation signal for any gas under the first heating voltage can be obtained. Similarly, the sum of the second background signal and the second excitation signal for any gas under the second heating voltage, and the sum of the third background signal and the third excitation signal for any gas under the third heating voltage, can also be obtained. Since the hardware is identical, and the calibration and testing hardware environments are also identical, the first background signal, the second background signal, and the third background signal are all the same for different gas components. Furthermore, the first, second, and third background signals are obtained by obtaining different background signals under different heating voltages without introducing the gas being measured.

[0066] S140, based on the first background signal, the first excitation signal and the first electrical signal calculation formula, determine the first electrical signal superposition calculation formula for any gas.

[0067] In one embodiment, the formula for superimposing the first electrical signal of any gas A is:

[0068] rawdata_A1=base1+Δrawdata_A1;

[0069] wherein, rawdata_A1 is the first electric signal of any gas A; base1 is the first background signal corresponding to the first heating voltage; and Δrawdata_A1 is the first excitation signal of any gas A corresponding to the first heating voltage.

[0070] In one embodiment, the superposition calculation formula of the first electric signal of any gas B is:

[0071] rawdata_B1 = base1 + Δrawdata_B1

[0072] wherein, rawdata_B1 is the first electric signal of any gas B; base1 is the first background signal corresponding to the first heating voltage; and Δrawdata_B1 is the first excitation signal of any gas B corresponding to the first heating voltage.

[0073] In one embodiment, the superposition calculation formula of the first electric signal of any gas C is:

[0074] rawdata_C1 = base1 + Δrawdata_C1

[0075] wherein, rawdata_C1 is the first electric signal of any gas C; base1 is the first background signal corresponding to the first heating voltage; and Δrawdata_C1 is the first excitation signal of any gas C corresponding to the first heating voltage.

[0076] S150, determining the first multi-component electric signal calculation formula based on the first electric signal calculation formula corresponding to at least two gases respectively.

[0077] In one embodiment, the first calibration signal calculation formula of any gas A of the two gas components is added to the first calibration signal calculation formula of any gas B, to obtain the first multi-component electric signal calculation formula including the two gas components. The first multi-component electric signal calculation formula including the two gas components is:

[0078] rawdata_A1 + rawdata_B1 = k_A1 * PPM_A + k_B1 * PPM_B + (d_A1 + d_B1)

[0079] wherein, rawdata_A1 is the first electric signal of any gas A; rawdata_B1 is the first electric signal of any gas B; k_A1 is the first slope coefficient of any gas A; k_B1 is the first slope coefficient of any gas B; PPM_A is the gas concentration value of any gas A; PPM_B is the gas concentration value of any gas B; d_A1 is the first intercept coefficient of any gas A; and d_B1 is the first intercept coefficient of any gas B.

[0080] Based on this, only PPM_A and PPM_B in the above formula are unknown, and the second multi-component electric signal calculation formula can be obtained based on the second heating voltage, so that PPM_A and PPM_B are calculated.

[0081] In another embodiment, the first calibration signal calculation formula of any gas A of the three gas components is added to the first calibration signal calculation formula of any gas B and the first calibration signal calculation formula of any gas C to obtain the first multi-component electric signal calculation formula of the three gas components. The first multi-component electric signal calculation formula of the three gas components is:

[0082] rawdata_A1+rawdata_B1+rawdata_C1=k_A1×PPM_A+k_B1×PPM_B+k_C1×PPM_C+(d_A1+d_B1+d_C1);

[0083] Wherein, rawdata_A1 is the first electric signal of any gas A; rawdata_B1 is the first electric signal of any gas B; rawdata_C1 is the first electric signal of any gas C; k_A1 is the first slope coefficient of any gas A; k_B1 is the first slope coefficient of any gas B; k_C1 is the first slope coefficient of any gas C; PPM_A is the gas concentration value of any gas A; PPM_B is the gas concentration value of any gas B; PPM_C is the gas concentration value of any gas C; d_A1 is the first intercept coefficient of any gas A; d_B1 is the first intercept coefficient of any gas B; d_C1 is the first intercept coefficient of any gas C.

[0084] S160, based on the first electric signal superposition calculation formula and the first multi-component electric signal calculation formula corresponding to at least two gases respectively, determining the first multi-component electric signal superposition calculation formula corresponding to the first heating voltage.

[0085] In one embodiment, based on the first electric signal superposition calculation formula and the first multi-component electric signal calculation formula corresponding to at least two gases respectively, determining the first multi-component electric signal superposition calculation formula corresponding to the first heating voltage, comprising:

[0086] Based on the first electric signal superposition calculation formula and the first multi-component electric signal calculation formula corresponding to at least two gases respectively, determining the first multi-component electric signal superposition transition calculation formula corresponding to the first heating voltage;

[0087] Transforming the first multi-component electric signal superposition transition calculation formula to determine the first multi-component electric signal superposition calculation formula corresponding to the first heating voltage.

[0088] The first multi-component electric signal superposition transition calculation formula of the two gas components is:

[0089] base1 + Δrawdata_A1 + Δrawdata_B1 = k_A1 x PPM_A + k_B1 x PPM_B + (d_A1 + d_B1 - base1);

[0090] wherein, Δrawdata_A1 is the first excitation signal corresponding to the first heating voltage of any gas A; Δrawdata_B1 is the first excitation signal corresponding to the first heating voltage of any gas B; k_A1 is the first slope coefficient of any gas A; k_B1 is the first slope coefficient of any gas B; PPM_A is the gas concentration value of any gas A; PPM_B is the gas concentration value of any gas B; d_A1 is the first intercept coefficient of any gas A; d_B1 is the first intercept coefficient of any gas B; base1 is the first background signal corresponding to the first heating voltage.

[0091] In one embodiment, the first multi-component electric signal superposition calculation formula including 2 gas components is:

[0092] rawdata1 = k_A1 x PPM_A + k_B1 x PPM_B + (d_A1 + d_B1 - base1);

[0093] wherein, rawdata1 is the first multi-component superposition electric signal corresponding to the first heating voltage of the multi-component gas; k_A1 is the first slope coefficient of any gas A; k_B1 is the first slope coefficient of any gas B; PPM_A is the gas concentration value of any gas A; PPM_B is the gas concentration value of any gas B; d_A1 is the first intercept coefficient of any gas A; d_B1 is the first intercept coefficient of any gas B; base1 is the background signal corresponding to the first heating voltage.

[0094] In another embodiment, the first multi-component electric signal superposition calculation formula including 3 gas components is:

[0095] rawdata1 = k_A1 x PPM_A + k_B1 x PPM_B + k_C1 x PPM_C + (d_A1 + d_B1 + d_C1 - 2 x base1);

[0096] wherein, rawdata1 is a first multi-component superimposed electrical signal corresponding to the multi-component gas and the first heating voltage; k_A1 is a first slope coefficient of any gas A; k_B1 is a first slope coefficient of any gas B; k_C1 is a first slope coefficient of any gas C; PPM_A is a gas concentration value of any gas A; PPM_B is a gas concentration value of any gas B; PPM_C is a gas concentration value of any gas C; d_A1 is a first intercept coefficient of any gas A; d_B1 is a first intercept coefficient of any gas B; d_C1 is a first intercept coefficient of any gas C; base1 is a background signal corresponding to the first heating voltage.

[0097] S170, determining a second multi-component electrical signal superposition calculation formula of the at least two gases corresponding to the second heating voltage and a third multi-component electrical signal superposition calculation formula corresponding to the third heating voltage.

[0098] In another embodiment, the second multi-component electrical signal superposition calculation formula including three gas components is:

[0099] Rawdata2=k_A2×PPM_A+k_B2×PPM_B+k_C2×PPM_C+(d_A2+d_B2+d_C2-2×base2);

[0100] wherein, rawdata2 is a second multi-component superimposed electrical signal corresponding to the multi-component gas and the second heating voltage; k_A2 is a second slope coefficient of any gas A; k_B2 is a second slope coefficient of any gas B; k_C2 is a second slope coefficient of any gas C; PPM_A is a gas concentration value of any gas A; PPM_B is a gas concentration value of any gas B; PPM_C is a gas concentration value of any gas C; d_A2 is a first intercept coefficient of any gas A; d_B2 is a first intercept coefficient of any gas B; d_C2 is a first intercept coefficient of any gas C; base2 is a second background signal corresponding to the first heating voltage.

[0101] In another embodiment, the third multi-component electrical signal superposition calculation formula including three gas components is:

[0102] Rawdata3=k_A3×PPM_A+k_B3×PPM_B+k_C3×PPM_C+(d_A3+d_B3+d_C3 - 2×base3);

[0103] Wherein, rawdata3 is the third multi-component superimposed electrical signal corresponding to the multi-component gas and the third heating voltage; k_A3 is the third slope coefficient of any gas A; k_B3 is the third slope coefficient of any gas B; k_C3 is the third slope coefficient of any gas C; PPM_A is the gas concentration value of any gas A; PPM_B is the gas concentration value of any gas B; PPM_C is the gas concentration value of any gas C; d_A3 is the third intercept coefficient of any gas A; d_B3 is the third intercept coefficient of any gas B; d_C3 is the third intercept coefficient of any gas C; base3 is the third background signal corresponding to the first heating voltage.

[0104] It should be noted that if the multi-component gas has multiple components, the first multi-component electrical signal superimposed calculation formula, the second multi-component electrical signal superimposed calculation formula, the third multi-component electrical signal superimposed calculation formula and the fourth multi-component electrical signal superimposed calculation formula, etc. need to be confirmed. The number of multi-component electrical signal superimposed calculation formula corresponds to the number of components.

[0105] S180, based on the first multi-component electrical signal superimposed calculation formula, the second multi-component electrical signal superimposed calculation formula, the third multi-component electrical signal superimposed calculation formula, and the fourth multi-component electrical signal superimposed calculation formula, simultaneously solve to determine the gas concentration value of any gas in the multi-component gas.

[0106] In another embodiment, in the first multi-component electrical signal superimposed calculation formula, the second multi-component electrical signal superimposed calculation formula, and the third multi-component electrical signal superimposed calculation formula, only PPM_A, PPM_B, and PPM_C are three unknowns, and the others are known, so the gas concentration values of each gas component can be obtained by simultaneous solution.

[0107] In another embodiment, if the multi-component gas has four components, the calibration at the fourth heating voltage needs to be added, and then the first multi-component electric signal superposition calculation formula, the second multi-component electric signal superposition calculation formula, the third multi-component electric signal superposition calculation formula and the fourth multi-component electric signal superposition calculation formula are obtained, and the gas concentration values of each gas component are obtained by simultaneous solution. By analogy, the concentrations of five components in the component gas can also be tested, and the first calibration concentration value corresponding to the first heating voltage and the first electric signal, the first calibration concentration value corresponding to the second heating voltage and the second electric signal, the first calibration concentration value corresponding to the third heating voltage and the third electric signal, the first calibration concentration value corresponding to the fourth heating voltage and the fourth electric signal, and the first calibration concentration value corresponding to the fifth heating voltage and the fifth electric signal are obtained; and then the first electric signal calculation formula, the second electric signal calculation formula, the third electric signal calculation formula, the fourth electric signal calculation formula and the fifth electric signal calculation formula of the five gases are determined; and then the first multi-component electric signal superposition calculation formula, the second multi-component electric signal superposition calculation formula, the third multi-component electric signal superposition calculation formula, the fourth multi-component electric signal superposition calculation formula and the fifth multi-component electric signal superposition calculation formula are determined, and the gas concentration values of the five gases of the component gas are obtained by simultaneous solution.

[0108] In some embodiments, steps S100-S120 are performed at a calibration ambient temperature, and step S130 can not be performed at the calibration ambient temperature, and there is a temperature error. In order to improve the gas concentration detection accuracy, step S130 further comprises the following steps:

[0109] S131: obtaining a current first background signal at a current ambient temperature and a first heating voltage, and a current first excitation signal corresponding to any gas;

[0110] S132: calculating a temperature compensation increment electric signal Sens_DltSRaw, Sens_DltSRaw=Tcomp_Coe0+Tcomp_Coe1*(Tmpr_DltTRaw)+Tcomp_Coe2*(Tmpr_DltTRaw)*(Tmpr_DltTRaw)+Tcomp_Coe3*(Tmpr_DltTRaw)*(Tmpr_DltTRaw)*(Tmpr_DltTRaw), wherein the current ambient temperature is Tmpr_TRaw, the calibration ambient temperature is TComp_TRawBase, the difference between the current ambient temperature Tmpr_TRaw and the calibration ambient temperature TComp_TRawBase is the temperature increment Tmpr_DltTRaw, and Tcomp_Coe0, Tcomp_Coe1, Tcomp_Coe2 and Tcomp_Coe3 are the zero-order temperature compensation coefficient, the first-order temperature compensation coefficient, the second-order temperature compensation coefficient and the third-order temperature compensation coefficient, respectively.

[0111] The cubic polynomial (including zeroth to third order terms) can flexibly fit this complex nonlinear relationship through the coefficients (Tcomp_Coe0 to Tcomp_Coe3), which can significantly reduce the compensation error in different temperature intervals compared with linear compensation (first order term) or quadratic compensation, so that the corrected signal is closer to the real concentration corresponding electrical signal, ensures that the alarm threshold is judged based on real and reliable signal, and improves the safety factor of the entire detection system.

[0112] Specifically, before step S132, the method further includes the following steps:

[0113] S1321: At the calibration ambient temperature, a first temperature calibration electrical signal corresponding to any gas PPM being 0 is obtained by using the gas concentration sensor.

[0114] S1322: At the first reference temperature, a second temperature calibration electrical signal corresponding to any gas PPM being 0 is obtained by using the gas concentration sensor.

[0115] S1323: At the second reference temperature, a third temperature calibration electrical signal corresponding to any gas PPM being 0 is obtained by using the gas concentration sensor.

[0116] S1324: At the third reference temperature, a fourth temperature calibration electrical signal corresponding to any gas PPM being 0 is obtained by using the gas concentration sensor.

[0117] S1325: Based on steps S1321 to S1324, the zeroth order temperature compensation coefficient Tcomp_Coe0, the first order temperature compensation coefficient Tcomp_Coe1, the second order temperature compensation coefficient Tcomp_Coe2, and the third order temperature compensation coefficient Tcomp_Coe3 are calculated.

[0118] Wherein, when any gas PPM is 0, the electrical signal drift of the sensor is only caused by temperature change (excluding the interference of gas concentration). Steps S1321 to S1324 can list four equations, which can be solved together to obtain four temperature compensation coefficients (Tcomp_Coe0 to Tcomp_Coe3).

[0119] S133: Based on the difference between the current first background signal and the temperature compensation incremental electrical signal, a temperature compensated first background signal is obtained, and based on the difference between the current first excitation signal and the temperature compensation incremental electrical signal, a temperature compensated first excitation signal is obtained. In step S140, the temperature compensated first background signal and the temperature compensated first excitation signal are used to determine the first electrical signal superposition calculation formula.

[0120] In some embodiments, steps S100-S120 are performed at a calibration humidity, and step S130 can not be performed at the calibration humidity, and there is a humidity error. In order to improve the gas concentration detection accuracy, after step S133, the method further comprises the following steps:

[0121] S134: obtaining a humidity increment by using a humidity sensor. The humidity increment refers to the difference between the current humidity and the calibration humidity. The calibration humidity can be selected as 0%.

[0122] S135: calculating a humidity compensation amount based on the humidity increment and the temperature increment. The influence of humidity on the thermal conductivity of gas is not a fixed value, but changes with temperature (for example, at the same humidity, the thermal conduction characteristics of water vapor in a high-temperature environment are different from those in a low-temperature environment). By introducing the temperature coefficient to calculate the humidity compensation amount, the humidity compensation weight at different temperatures can be dynamically adjusted, the compensation deficiency caused by ignoring the interaction between temperature and humidity is avoided, and the humidity correction is more in line with the actual physical law.

[0123] Specifically, before step S135, the humidity compensation amount H_comp is solved, H_comp = Hcomp_Coe0+Hcomp_Coe1×Tmpr_DltTRaw+Hcomp_Coe2×H_delta+Hcomp_Coe3×Tmpr_DltTRaw×H_delta.

[0124] The specific solving process is that, at a calibration ambient temperature (T0), calibration experiments are performed at different humidities (such as 0%, 10%, 30%, and 50%), and the humidity compensation zero-order coefficient Hcomp_Coe0 (constant term, correcting baseline deviation), the humidity compensation temperature coefficient Hcomp_Coe1 (weight related to temperature parameter), the humidity compensation humidity coefficient Hcomp_Coe2 (weight related to humidity increment), and the humidity compensation interaction coefficient Hcomp_Coe3 (cross influence related to temperature and humidity) are fitted. The current humidity (H_current) is read by using the humidity sensor; the humidity increment (H_delta) = current humidity H_current-calibration humidity H0 (since H0=0%, H_delta = H_current). The humidity compensation zero-order coefficient Hcomp_Coe0, the humidity compensation temperature coefficient Hcomp_Coe1, the humidity compensation humidity coefficient Hcomp_Coe2, and the humidity compensation interaction coefficient Hcomp_Coe3 are solved by using four equations.

[0125] S136: humidity compensation is performed on the temperature-compensated first background signal and the temperature-compensated first excitation signal by using a humidity compensation amount, to obtain a humidity-compensated first background signal and a humidity-compensated first excitation signal. The temperature compensation is performed first, and then the humidity compensation is performed, so that the correction logics of the two environmental factors are independent of each other. Such decoupling design facilitates optimization of the compensation parameters of the humidity and the temperature respectively, and reduces the debugging difficulty. Specifically, the humidity-compensated first background signal = the temperature-compensated first background signal - the humidity compensation amount, and the humidity-compensated first excitation signal = the temperature-compensated first excitation signal - the humidity compensation amount, and then step S140 is performed.

[0126] In some embodiments, after step S136, the method further includes the following steps:

[0127] S137: an air pressure increment is obtained by using an air pressure sensor.

[0128] S138: an air pressure parameter is obtained based on the air pressure increment. After correction by the air pressure parameter, the detection values in different air pressure environments are normalized to a standard air pressure reference, ensuring that the determination logic of the alarm threshold is unified, and avoiding safety risks caused by air pressure differences. Specifically, the air pressure parameter = 1 + k x air pressure increment, and k is an air pressure calibration coefficient.

[0129] Specifically, the air pressure calibration coefficient k is obtained through an air pressure calibration experiment. A corresponding relationship between the air pressure increment and the concentration deviation is established, and finally the air pressure calibration coefficient k is obtained through fitting calculation. Alternatively, under the calibration air pressure P0, the calibration temperature, and the calibration humidity, a calibration gas (such as nitrogen or carbon dioxide) is selected with a preset concentration, for example, 2000 PPM, and a sealed container with adjustable air pressure is used to simulate an environment with 0.5-1.2 times the calibration air pressure. First, the detection value C 测 of the gas concentration sensor under different air pressures P is collected 理 , second, the ideal concentration value C 理 caused by the change of air pressure is calculated as C 测 = C0 x (P / P0), third, k is obtained according to 1 + k x ΔP = C 理 / C 测 , and the least square method is used to fit the k values of multiple air pressure points, and the average or optimal fitting value is taken to obtain the air pressure calibration coefficient k.

[0130] S139: the humidity-compensated first background signal and the humidity-compensated first excitation signal are respectively divided by the air pressure parameter, to obtain an air pressure-compensated first background signal and an air pressure-compensated first excitation signal, and then step S140 is performed.

[0131] The gas concentration (PPM) is essentially the number of target gas molecules per unit volume, while the gas pressure directly affects the gas volume. When the gas pressure decreases (such as in high-altitude environments), the gas volume expands, and the same number of molecules corresponds to a lower "number of molecules per unit volume" (the actual concentration does not change, but the signal is displayed as lower). If not compensated for the gas pressure, the same actual concentration will be converted into different PPM values under different gas pressures. By correcting the gas pressure parameter (dividing the signal by the gas pressure parameter, which essentially normalizes the concentration to the standard pressure), the error caused by the fluctuation of the gas pressure can be eliminated, and the detection result is more consistent with the real molecular density of the gas.

[0132] In combination Figure 3 The gas concentration thermocouple chip U7 of the signal sensing circuit 220 has two MEMS thermal conductivity chips. After the heating voltage is turned on, in the first MEMS thermal conductivity chip, the resistance between the first port MEA HTR1 and the eighth port MEA HTR2 generates a stable heat source, and the thermocouple between the second port MEA TH+ pin and the seventh port MEA TH- pin generates a small electrical signal according to the heat transferred by the gas molecules. Similarly, in the second MEMS thermal conductivity chip, the heat source generated by the resistance between the third port REF HTR1 and the sixth port REF HTR2, and the thermocouple between the fourth port REF TH+ pin and the fifth port REF TH- pin correspondingly generates an electrical signal. Among them, the second MEMS thermal conductivity chip is sealed in dry air, and the sealed dry air has a fixed volume concentration and a fixed thermal conductivity. Since the second MEMS thermal conductivity chip does not contact the external gas, it is used to obtain the first background signal and also serves as an analog for any gas PPM being 0. Therefore, in steps S1321~1324, the first to fourth thermometric electrical signals are obtained, respectively.

[0133] In some embodiments, S100~S120 are performed on the calibrated gas concentration thermocouple chip U7. Due to different processing errors of different gas concentration thermocouple chips U7, the resistance between the first port MEA HTR1 and the eighth port MEA HTR2 may have manufacturing deviations, and there may be resistance baseline drift after long-term use. Optionally, the method further includes the following steps:

[0134] S1311: Before step S131, obtain a calibration resistance R_ref under the first heating voltage. The calibration resistance R_ref refers to the resistance value between the first port MEA HTR1 and the eighth port MEA HTR2 in the calibrated gas concentration thermocouple chip U7.

[0135] S1312: Obtain a measured resistance at the first heating voltage. The measured resistance refers to the resistance value between the first port MEA HTR1 and the eighth port MEA HTR2 in the gas concentration thermocouple chip U7 currently used.

[0136] S1313: The resistance deviation is equal to the difference between the measured resistance and the calibration resistance R_ref. If the resistance deviation ΔR is greater than the calibration stage threshold, an alarm signal is output to replace the gas concentration thermocouple chip U7 due to resistance aging. If the resistance deviation ΔR is less than or equal to the calibration stage threshold, resistance compensation is performed. Optionally, the calibration stage threshold is 10% of the calibration resistance.

[0137] Specifically, based on the resistance temperature coefficient TCR, the resistance deviation ΔR is converted into a temperature deviation ΔT. According to the formula TCR=(R2-R1) / (R1*(T2-T1)), it is derived that ΔT=ΔR / (R_ref*TCR), and TCR is a material intrinsic value. Further, in step S132, the current ambient temperature Tmpr_TRaw is equal to the measured temperature Tmpr_TRaw of the temperature sensor + the temperature deviation ΔT. 测

[0138] It should be noted that when calibrating different concentrations of a single gas with different heating voltages corresponding to each concentration, the detection method of the present application can also be used to obtain the gas concentration values of each gas component. When using this calibration method, the accuracy of the multi-component gas concentration can be further increased.

[0139] It should be understood that the size of the serial number of each step in the above embodiments does not mean the order of execution. The execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0140] As shown in FIG. 2, the second aspect of the present application provides a multi-component gas concentration detection circuit for implementing the multi-component gas concentration detection method according to any one of the first aspect. The detection circuit 200 includes: Figure 2 A heating control circuit 210, including a plurality of low-dropout linear voltage stabilizer circuits, for sequentially controlling each low-dropout linear voltage stabilizer circuit to output a plurality of heating voltages to the signal sensing circuit, respectively. The number of low-dropout linear voltage stabilizer circuits is greater than or equal to the number of gas types in the multi-component gas.

[0141]

[0142] ​​The signal sensing circuit 220 includes a gas concentration thermocouple chip for receiving the heating voltages respectively and sensing the concentration change of the multi-component gas in the measured environment; when the concentration of the multi-component gas changes, the gas concentration thermocouple chip outputs a differential voltage signal corresponding to the concentration change of the multi-component gas to the signal processing circuit, the differential voltage signal including a background signal and an excitation signal, and the gas concentration thermocouple chip includes a first single thermocouple chip in a sealed manner and a second single thermocouple chip with a hole.

[0143] The signal processing circuit 230 includes a microcontroller chip for driving the heating control circuit to output the plurality of heating voltages, receiving the differential voltage signal of the signal sensing circuit, and determining the gas concentration value of each component gas in the multi-component gas through signal processing. Optionally, the signal processing circuit 230 further includes a communication interface for reading the output signal of the gas concentration thermocouple chip and controlling the gas concentration thermocouple chip.

[0144] In one embodiment, the heating control circuit includes at least 3 low-dropout linear regulator circuits; any low-dropout linear regulator circuit includes a low-dropout linear regulator chip, a first diode, a first field effect transistor, a first resistor and a second resistor; for example, when the number of components of the multi-component gas is 2, the heating control circuit includes 3 low-dropout linear regulator circuits; when the number of components of the multi-component gas is 3, the heating control circuit includes 4 low-dropout linear regulator circuits.

[0145] In one embodiment, in combination Figures 6 to 9 , when the number of components of the multi-component gas is 3, the heating control circuit 210 includes a first low-dropout linear regulator circuit (see Figure 6 ), a second low-dropout linear regulator circuit (see Figure 7 ), a third low-dropout linear regulator circuit (see Figure 8 ), and a fourth low-dropout linear regulator circuit (see Figure 9 ); as shown in Figure 6 , the first low-dropout linear regulator circuit includes a low-dropout linear regulator chip U2, a first diode D1, a first field effect transistor Q2, a first resistor R20 and a second resistor R21; the gate G of the first field effect transistor Q2, the anode of the first diode D1 and one end of the first resistor R20 are all connected to the VHT_EN1 input end for receiving the control signal sent by the signal processing circuit; the source S of the first field effect transistor Q2 and the other end of the first resistor R20 and one end of the second resistor R21 are connected in parallel to the ground; the drain D of the first field effect transistor Q2 is connected to the ground port GND of the low-dropout linear regulator chip U2; the enable port EN / NC of the low-dropout linear regulator chip U2 is connected to the cathode of the first diode D1 and the other end of the second resistor R21; the output port OUT of the low-dropout linear regulator chip U2 outputs the heating voltage to the signal sensing circuit 220, and the output heating voltage is connected to the signal sensing circuit 220 through the VHT port.

[0146] It should be noted that the multi-component gas includes 2 gas components, the heating control circuit includes at least 3 low dropout linear voltage stabilizers, the multi-component gas includes 3 gas components, the heating control circuit includes at least 4 low dropout linear voltage stabilizers, so as to stagger the heating voltages of different gas components, so that the gas concentration test is more accurate. The low dropout linear voltage stabilizer outputting the first heating voltage is referred to as the first low dropout linear voltage stabilizer, the low dropout linear voltage stabilizer outputting the second heating voltage is referred to as the second low dropout linear voltage stabilizer, the low dropout linear voltage stabilizer outputting the third heating voltage is referred to as the third low dropout linear voltage stabilizer, and the low dropout linear voltage stabilizer outputting the fourth heating voltage is referred to as the fourth low dropout linear voltage stabilizer; for example, the heating voltage output by the first low dropout linear voltage stabilizer is 4.5V, the heating voltage output by the second low dropout linear voltage stabilizer is 3.3V, the heating voltage output by the third low dropout linear voltage stabilizer is 1.8V, and the heating voltage output by the fourth low dropout linear voltage stabilizer is 1.2V.

[0147] In one embodiment, as Figure 3As shown, the signal sensing circuit 220 includes a gas concentration thermocouple chip U7, a third resistor R1, a fourth resistor R2, a first capacitor C6, a second capacitor C7, and a third capacitor C8. The gas concentration thermocouple chip includes a first single thermocouple chip in a sealed state and a second single thermocouple chip with a hole. The first port MEA HTR1 of the gas concentration thermocouple chip U7 is connected to an AN2 input end and one end of the fourth resistor R2, and the third port REF HTR1 is connected to an AN3 input end and one end of the third resistor R1. The other end of the third resistor R1, the other end of the fourth resistor R2, one end of the first capacitor C6, and one end of the second capacitor C7 are all connected to a heating voltage signal input end VHT for receiving various heating voltages, wherein the AN2 input end and the AN3 input end are used to receive control signals of the body concentration thermocouple chip. The second port of the gas concentration thermocouple chip U7 outputs a differential voltage signal of a multi-component gas concentration change, the fourth port of the gas concentration thermocouple chip U7 outputs a differential voltage signal of a reference gas concentration change, the fifth port and the seventh port of the gas concentration thermocouple chip U7 are both connected to a boost voltage signal output end VCM, and the other end of the third capacitor C8 is grounded. The eighth port, the sixth port, the ninth port, and the tenth port of the gas concentration thermocouple chip U7 are all connected in parallel to the ground. The first port MEA HTR1 and the third port REF HTR1 of the gas concentration thermocouple chip U7 simultaneously receive the heating voltage VHT output by any low-dropout linear regulator. The second port of the gas concentration thermocouple chip U7 outputs a weak signal of the differential voltage of the multi-component gas concentration change, i.e., the second differential voltage signal AN1, and the seventh port outputs a compensation signal of the differential voltage of the multi-component gas concentration change. The fourth port of the gas concentration thermocouple chip U7 outputs a weak signal of the differential voltage of the reference gas concentration change, i.e., the first differential voltage signal AN0, and the fifth port outputs a compensation signal of the differential voltage of the reference gas concentration change. The weak signal of the differential voltage of the multi-component gas concentration change is output through the AN1 end, the weak signal of the differential voltage of the reference gas concentration change is output through the AN0 end, and the compensation signal of the differential voltage is output through the VCM end, i.e., the boost voltage signal. The third resistor R1 and the fourth resistor R2 are used for voltage division of the heating voltage, and the first capacitor C6, the second capacitor C7, and the third capacitor C8 are all used for filtering. For example, the weak signal of the differential voltage output by the AN0 and AN1 ends is 100 mV, the compensation signal of the differential voltage output by the VCM end is 12 V, and the signal output to the signal processing circuit 230 is 12.01 V, which amplifies the differential voltage signal of the gas concentration change.

[0148] In one embodiment, the first port MEA HTR1 and the third port REF HTR1 of the gas concentration thermocouple chip U7 simultaneously receive the heating voltage VHT output by any low-dropout linear regulator for heating for a first preset time length, and then stop heating for a second preset time length. The first preset time length is equal to or not equal to the second preset time length. For example, the first preset time length is 100 ms, and the second preset time length is 100 ms. For another example, the first preset time length is less than the second preset time length, so as to avoid the increase of error caused by too long heating time, and improve the accuracy of gas concentration change.

[0149] It should be noted that the gas concentration thermocouple chip includes a sealed first single thermocouple chip (U7 below) Figure 3 ) and a second single thermocouple chip (U7 above Figure 3 ) with holes. After a preset heating voltage is applied between MEA HTR1 and MEA HTR2 or between REF HTR1 and REF HTR2 (the preset voltage VHT may be different according to actual application scenarios), a stable heat source is generated between MEA HTR1 and MEA HTR2 or between REF HTR1 and REF HTR2. The heat of the heat source will be transmitted to other solid surfaces through gas molecules in the environment. MEA TH+ and MEA TH- or REF TH+ and REF TH- are a thermoelectric pile, which will generate a small change in electric signal according to the change in heat transmitted by the gas molecules. The higher the concentration of any gas component, the more heat it carries, and the greater the change in electric signal it causes. Therefore, the change in electric signal generated by the gas concentration thermocouple chip can be used to calculate the concentration of the target gas in the measured environment. The present application avoids the change in electric signal between MEA TH+ and MEA TH- or between REF TH+ and REF TH- caused by the change in heat of other media in the environment, thereby avoiding measurement deviation caused thereby. The sealed first single thermocouple chip is sealed in dry air, and the sealed dry air has a fixed volume concentration, and its heat conduction ability is fixed, and the transmitted heat is also fixed. Therefore, if the electric signal of the sealed first single thermocouple chip changes, it must be caused by the change in temperature of the external environment.

[0150] In one embodiment, as shown in Figure 4 , Figure 4 , C8 is a third capacitor in Figure 3 , and the signal processing circuit 230 includes a microcontroller chip U8 (see Figure 5), a fourth capacitor C9, a fifth resistor R3, a sixth resistor R4, a fifth capacitor C5, a burner J1; the eighth port AN0 of the microcontroller chip U8 is connected to one end of the fourth capacitor C9, and receives the first differential voltage signal of the reference gas concentration change output by the fourth port of the gas concentration thermocouple chip U7; the seventh port AN1 of the microcontroller chip U8 is connected to the other end of the fourth capacitor C9, and receives the second differential voltage signal of the multi-component gas concentration change output by the second port of the gas concentration thermocouple chip U7; the third port VCM of the microcontroller chip U8 is connected to one end of the fifth capacitor C5, and receives the raised voltage signal corresponding to the first differential voltage signal and the second differential voltage signal; the twenty-fifth port, the twenty-sixth port, the twenty-seventh port and the twenty-eighth port of the microcontroller chip U8 output control signals for driving the heating control circuit (in this embodiment, four ports are used for output because there are four low-dropout linear voltage stabilizers; if there are only three low-dropout linear voltage stabilizers, three ports are used for output); the thirty-second port of the microcontroller chip U8; the twenty-third port and the twenty-fourth port of the microcontroller chip U8 are used to output the gas concentration values of each component gas in the multi-component gas determined through signal processing.

[0151] It can be understood that the signal processing circuit collects the differential electrical signals of the signal sensing circuit for processing, and after the microcontroller (MCU) receives the differential electrical signals, the ADC inside the microcontroller can perform functions such as differential voltage input and small signal amplification, and distinguish and calculate the signal difference caused by the change of the gas concentration of any gas component from the difference caused by interference factors, and the processed data can have a reasonable corresponding relationship with the gas concentration of any gas component. Such a corresponding relationship is generally linear, and the higher the measured gas concentration, the larger the output value of the signal processing circuit, and vice versa, the lower the measured gas concentration, the smaller the output value of the signal processing circuit.

[0152] It should be noted that the data obtained by the MCU is the data converted by the ADC, which is referred to as raw data Rawdata, and the data Rawdata converted by the ADC corresponds to the voltage level of the ADC, which corresponds to the voltage signal mentioned above, and the voltage signal corresponds to the gas concentration value of any gas component, so the raw data Rawdata obtained by the MCU has a one-to-one corresponding relationship with the gas concentration. The Rawdata value and the gas concentration value may not be directly corresponding, but the flow rate information is already included in the Rawdata, and the Rawdata data can be processed later according to the specific situation of the user to make it more suitable for specific application scenarios. This process is "calibration".

[0153] It should be noted that, Figures 3 to 9Only parts related to the present embodiment are shown.

[0154] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or software. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the application. The specific working process of the units and modules in the system can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0155] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0156] In the embodiments provided in the present application, it should be understood that the disclosed apparatus / terminal device and method can be implemented in other ways. For example, the apparatus / terminal device embodiments described above are only schematic, and the division of the modules or units is only a logical function division, and there can be another division in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0157] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for detecting the concentration of a multi-component gas, characterized in that, A detection circuit for multi-component gas concentration includes: Acquire the first calibrated concentration value and first electrical signal corresponding to the first heating voltage, the first calibrated concentration value and second electrical signal corresponding to the second heating voltage, and the first calibrated concentration value and third electrical signal corresponding to the third heating voltage for any gas; A first slope coefficient and a first intercept coefficient are determined by linear fitting based on the first calibrated concentration value of any gas and the first electrical signal; a second slope coefficient and a second intercept coefficient are determined by linear fitting based on the first calibrated concentration value of any gas and the second electrical signal; and a third slope coefficient and a third intercept coefficient are determined by linear fitting based on the first calibrated concentration value of any gas and the third electrical signal. Based on the first calibrated concentration value of any gas, the first electrical signal, the first slope coefficient, and the first intercept coefficient, determine the calculation formula for the first electrical signal of any gas; Acquire the first background signal and the first excitation signal corresponding to any gas and the first heating voltage; Based on the first background signal, the first excitation signal, and the first electrical signal calculation formula, determine the first electrical signal superposition calculation formula for any gas. Based on the calculation formulas of the first electrical signals corresponding to at least two gases, a calculation formula for the first multi-component electrical signal is determined. Based on the first electrical signal superposition calculation formula and the first multi-component electrical signal calculation formula corresponding to at least two gases respectively, determine the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage; Determine the superposition calculation formulas for the second multi-component electrical signals of at least two gases corresponding to the second heating voltage and the third multi-component electrical signals corresponding to the third heating voltage; Based on the first multi-component electrical signal superposition calculation formula, the second multi-component electrical signal superposition calculation formula, and the third multi-component electrical signal superposition calculation formula, the gas concentration value of any gas in the multi-component gas is determined by solving them simultaneously. The step, based on the first electrical signal superposition calculation formula corresponding to at least two gases and the first multi-component electrical signal calculation formula respectively, determines the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage, including: Based on the transformation of the first electrical signal superposition calculation formula and the first multi-component electrical signal calculation formula corresponding to at least two gases respectively, the first multi-component electrical signal superposition transition calculation formula corresponding to the first heating voltage is determined. The first multi-component electrical signal superposition transition calculation formula is transformed to determine the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage.

2. The method for detecting the concentration of a multi-component gas as described in claim 1, characterized in that, The formula for calculating the first calibration signal is: rawdata_A1=k_A1×PPM_A+d_A1; Wherein, rawdata_A1 is the first electrical signal of any gas A; PPM_A is the first calibrated concentration value of any gas A; k_A1 is the first slope coefficient for any gas A; d_A1 is the first intercept coefficient of any gas A.

3. The method for detecting the concentration of a multi-component gas as described in claim 1, characterized in that, The formula for calculating the superposition of the first electrical signal is: rawdata_A1=base1+Δrawdata_A1; Wherein, rawdata_A1 is the first electrical signal of any gas A; base1 is the first background signal corresponding to the first heating voltage; Δrawdata_A1 is the first excitation signal corresponding to any gas A and the first heating voltage.

4. The method for detecting the concentration of a multi-component gas as described in claim 1, characterized in that, The formula for calculating the first multi-component electrical signal is: rawdata_A1+rawdata_B1+rawdata_C1=k_A1×PPM_A+k_B1×PPM_B+k_C1×PPM_C+ (d_A1+d_B1+d_C1); Wherein, rawdata_A1 is the first electrical signal of any gas A; rawdata_B1 is the first electrical signal for any gas B; rawdata_C1 is the first electrical signal for any gas C; k_A1 is the first slope coefficient for any gas A; k_B1 is the first slope coefficient for any gas B; k_C1 is the first slope coefficient for any gas C; PPM_A represents the gas concentration value of any gas A; PPM_B is the gas concentration value of any gas B; PPM_C represents the gas concentration value of any gas C; d_A1 is the first intercept coefficient of any gas A; d_B1 is the first intercept coefficient of any gas B; d_C1 is the first intercept coefficient of any gas C.

5. The method for detecting the concentration of a multi-component gas as described in claim 1, characterized in that, The formula for calculating the superposition of the first multi-component electrical signals is: rawdata1=k_A1×PPM_A+k_B1×PPM_B+k_C1×PPM_C+(d_A1+d_B1+d_C1-2×base1); Wherein, rawdata1 is the first multi-component superimposed electrical signal corresponding to the multi-component gas and the first heating voltage; k_A1 is the first slope coefficient for any gas A; k_B1 is the first slope coefficient for any gas B; k_C1 is the first slope coefficient for any gas C; PPM_A1 is the gas concentration value of any gas A; PPM_B1 is the gas concentration value of any gas B; PPM_C1 is the gas concentration value of any gas C; d_A1 is the first intercept coefficient of any gas A; d_B1 is the first intercept coefficient of any gas B; d_C1 is the first intercept coefficient of any gas C; base1 is the first background signal corresponding to the first heating voltage.

6. A detection circuit for the concentration of a multi-component gas, characterized in that, The detection circuit for implementing the method for detecting the concentration of a multi-component gas as described in any one of claims 1 to 5 includes a heating control circuit, a signal sensing circuit, and a signal processing circuit. The heating control circuit includes multiple low-dropout linear regulator circuits, which are used to sequentially control each of the low-dropout linear regulator circuits to output multiple heating voltages to the signal sensing circuit. The number of the low-dropout linear regulator circuits is greater than or equal to the number of types of gases of the concentration to be measured in the multi-component gas. The signal sensing circuit includes a gas concentration thermocouple chip for receiving each of the heating voltages and sensing the concentration changes of the multi-component gases in the measured environment. When the concentration of the multi-component gases changes, the gas concentration thermocouple chip outputs a differential voltage signal corresponding to the heating voltage, which includes a background signal and an excitation signal. The gas concentration thermocouple chip includes a sealed first single thermocouple chip and a perforated second single thermocouple chip. The signal processing circuit includes a microcontroller chip for driving the heating control circuit to output multiple heating voltages, receiving the differential voltage signal from the signal sensing circuit, and determining the gas concentration value of each component gas in the multi-component gas through signal processing; it also includes a communication interface for reading the output signal of the gas concentration thermocouple chip and controlling the gas concentration thermocouple chip.

7. The multi-component gas concentration detection circuit as described in claim 6, characterized in that, The heating control circuit includes at least three of the low dropout linear regulator circuits; each of the low dropout linear regulator circuits includes a low dropout linear regulator chip, a first diode, a first field-effect transistor, a first resistor, and a second resistor. The gate of the first field-effect transistor, the anode of the first diode, and one end of the first resistor are all used to receive control signals sent by the signal processing circuit. The source of the first field-effect transistor is connected in parallel to the other end of the first resistor and one end of the second resistor to ground; The drain of the first field-effect transistor is connected to the ground port of the low-dropout linear regulator chip; The enable port of the low-dropout linear regulator chip is connected to the negative terminal of the first diode and the other end of the second resistor; The output port of the low-dropout linear regulator chip outputs the heating voltage to the signal sensing circuit.

8. The multi-component gas concentration detection circuit as described in claim 6, characterized in that, The signal sensing circuit includes the gas concentration thermocouple chip, a third resistor, a fourth resistor, a first capacitor, a second capacitor, and a third capacitor; the gas concentration thermocouple chip includes a sealed first single thermocouple chip and a perforated second single thermocouple chip. The first port of the gas concentration thermocouple chip is connected to one end of the fourth resistor, and the third port of the gas concentration thermocouple chip is connected to one end of the third resistor; the other end of the third resistor, the other end of the fourth resistor, one end of the first capacitor, and one end of the second capacitor are all connected to the heating voltage signal input terminal to receive the respective heating voltages; The second port of the gas concentration thermocouple chip outputs a first differential voltage signal of the multi-component gas concentration change, the fourth port of the gas concentration thermocouple chip outputs a second differential voltage signal of the reference gas concentration change, the fifth and seventh ports of the gas concentration thermocouple chip both output raised voltage signals and are connected to one end of the third capacitor, and the other end of the third capacitor is grounded. The eighth, sixth, ninth, and tenth ports of the gas concentration thermocouple chip are connected to ground in parallel.

9. The multi-component gas concentration detection circuit as described in claim 6, characterized in that, The signal processing circuit includes a microcontroller chip, a fourth capacitor, a fifth capacitor, a fifth resistor, a sixth resistor, and a programmer; The eighth port of the microcontroller chip is connected to one end of the fourth capacitor and receives the first differential voltage signal of the reference gas concentration change output by the fourth port of the gas concentration thermocouple chip. The seventh port of the microcontroller chip is connected to the other end of the fourth capacitor and receives the second differential voltage signal of the multi-component gas concentration change output by the second port of the gas concentration thermocouple chip. The third port of the microcontroller chip is connected to one end of the fifth capacitor and receives the boost voltage signal corresponding to the first differential voltage signal and the second differential voltage signal. The microcontroller chip outputs control signals from its 25th, 26th, 27th, and 28th ports to drive the heating control circuit. The microcontroller chip outputs the gas concentration values ​​of each component gas in the multi-component gas, which are determined by signal processing, through its 23rd and 24th ports.

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