Multi-component gas concentration detection method and detection circuit

Abstract

The invention provides a multi-component gas concentration detection method and detection circuit, and belongs to the technical field of gas concentration detection, and the method comprises the following steps: obtaining each calibration concentration value of any gas corresponding to each heating voltage and a calibration electric signal thereof; performing linear fitting to determine each slope coefficient and each intercept coefficient; determining a first electric signal calculation formula of any gas; acquiring a corresponding background signal and an 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 formulas corresponding to the at least two gases respectively; determining a first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage, a second multi-component electrical signal superposition calculation formula corresponding to the second heating voltage and a third multi-component electrical signal superposition calculation formula corresponding to the third heating voltage; the concentration value of any gas is determined through simultaneous solution; the gas concentration can be obtained without introducing any gas thermal conductivity, and the detection precision and efficiency are improved.

Description

Technical Field

[0001] The present application belongs to the technical field of gas concentration detection, and in particular relates to a method and a detection circuit for detecting the concentration of a multi-component gas. Background Art

[0002] The mainstream gas concentration sensors currently on the market are based on non-dispersive infrared optical, electrochemical, or semiconductor principles. Gas concentration sensors using electrochemical or semiconductor principles require a lengthy warm-up period before they can function properly. The service life of electrochemical sensors decreases as the chemical materials degrade. Furthermore, the detection accuracy of current gas concentration sensors is affected by a variety of factors, such as severe interference from background gases in the accuracy of multi-component gas concentration calculations, the inability to distinguish between component gases within a multi-component gas, and the lack of coupling between dynamic response characteristics and temperature excitation strategies, resulting in insufficient detection accuracy.

[0003] Therefore, there is a problem in the existing technology that the accuracy of multi-component gas concentration detection cannot meet the scene requirements. Summary of the Invention

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

[0005] A first aspect of an embodiment of the present application provides a method for detecting the concentration of a multi-component gas, which is applied to a gas concentration detection circuit, comprising: Obtaining a first calibrated concentration value and a first electrical signal of any gas corresponding to a first heating voltage, a second gas concentration value and a second electrical signal corresponding to a second heating voltage, and a third gas concentration value and a third electrical signal corresponding to a third heating voltage; Performing linear fitting based on a first calibrated concentration value of any gas and a first electrical signal to determine a first slope coefficient and a first intercept coefficient, performing linear fitting based on a second gas concentration value of any gas and a second electrical signal to determine a second slope coefficient and a second intercept coefficient, and performing linear fitting based on a third gas concentration value of any gas and a third electrical signal to determine a third slope coefficient and a third intercept coefficient; Determine a calculation formula for a first electrical signal of any gas based on a first calibration concentration value of any gas, a first electrical signal, a first slope coefficient, and a first intercept coefficient; Acquire a first background signal and a first excitation signal corresponding to a first heating voltage for any gas; Determine a first electrical signal superposition calculation formula for any gas based on the first background signal, the first excitation signal and the first electrical signal calculation formula; Determining a first multi-component electrical signal calculation formula based on first electrical signal calculation formulas corresponding to at least two gases; Determine a first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage based on the first electrical signal superposition calculation formula and the first multi-component electrical signal calculation formula corresponding to the at least two gases respectively; Determining a second multi-component electrical signal superposition calculation formula corresponding to the second heating voltage and a third multi-component electrical signal superposition calculation formula corresponding to the third heating voltage for at least two gases; 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 simultaneous solution.

[0006] A second aspect of the embodiments of the present application provides a multi-component gas concentration detection circuit, which is used to implement the multi-component gas concentration detection method as described in any one of the first aspects. The detection circuit includes: A heating control circuit includes a plurality of low-voltage-difference linear voltage regulator circuits, which are used to sequentially control each of the low-voltage-difference linear voltage regulator circuits to output a plurality of heating voltages to the signal sensing circuit, wherein the number of the low-voltage-difference linear voltage regulator circuits is greater than or equal to the number of gas types in the multi-component gas; The signal sensing circuit includes a gas concentration thermocouple chip, which is used to receive each heating voltage and sense 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 multi-component gas concentration change of the heating voltage to the signal processing circuit. The differential voltage signal includes a background signal and an excitation signal. The gas concentration thermocouple chip includes a sealed first single thermocouple chip and a second single thermocouple chip with a hole. The signal processing circuit includes a microcontroller chip, which is used to drive the heating control circuit to output multiple heating voltages, receive the differential voltage signal from the signal sensing circuit, and determine the gas concentration value of each component gas in the multi-component gas through signal processing; it also includes a communication interface, which is used to read the output signal of the gas concentration thermocouple chip and control the gas concentration thermocouple chip.

[0007] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The above-mentioned method for detecting the concentration of multi-component gas is as follows: obtaining the gas concentration value and the first electrical signal corresponding to the first heating voltage, the gas concentration value and the second electrical signal corresponding to the second heating voltage, and the gas concentration value and the third electrical signal corresponding to the third heating voltage of any gas; performing linear fitting based on the gas concentration value and the first electrical signal of any gas to determine the first slope coefficient and the first intercept coefficient, determine the second slope coefficient and the second intercept coefficient, and determine the third slope coefficient and the third intercept coefficient; determining the first electrical signal calculation formula of any gas based on the gas concentration value, the first electrical signal, the first slope coefficient and the first intercept coefficient of any gas; then obtaining the first background signal and the first excitation signal corresponding to the first heating voltage of any gas; and determining the first electrical signal superposition calculation formula of any gas; determining the first multi-component electrical signal calculation formula based on the first electrical signal calculation formulas corresponding to at least two gases respectively; determining the first multi-component electrical signal calculation formula based on the first electrical signal superposition calculation formulas corresponding to at least two gases respectively and the first electrical signal superposition calculation formula A multi-component electrical signal calculation formula is provided to determine a first multi-component electrical signal superposition calculation formula corresponding to a first heating voltage; a second multi-component electrical signal superposition calculation formula corresponding to a second heating voltage and a third multi-component electrical signal superposition calculation formula corresponding to a third heating voltage of at least two gases are determined; 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 concentration value of any gas in the multi-component gas is determined by joint solution; compared with the existing technology, since multiple heating voltages are used to heat and calibrate the multi-component gas, the thermal conductivity difference of the multi-component gas at different temperatures is enhanced, thereby achieving the gas concentration of each component gas without introducing the thermal conductivity of any gas in the multi-component gas by jointly combining multiple multi-component electrical signal superposition calculation formulas, realizing a detection mechanism of multiple temperature step excitations, improving the gas concentration detection accuracy and detection efficiency of the multi-component gas, and reducing the detection cost of the gas concentration of each component gas in the multi-component gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic flow chart of a method for detecting the concentration of a multi-component gas provided in one embodiment of the present application; Figure 2 A schematic diagram of a multi-component gas concentration detection circuit according to an embodiment of the present application; Figure 3 This is an example circuit schematic diagram of a signal sensing circuit in a multi-component gas concentration detection circuit; Figure 4 This is an example circuit schematic diagram of a signal processing circuit in a multi-component gas concentration detection circuit; Figure 5 for Figure 4 Example circuit schematic of the microcontroller chip in; Figure 6An exemplary circuit schematic diagram of a first low voltage difference linear voltage regulator circuit of a heating control circuit; Figure 7 An exemplary circuit schematic diagram of a second low voltage difference linear voltage regulator circuit of a heating control circuit; Figure 8 An exemplary circuit schematic diagram of a third low voltage difference linear voltage regulator circuit of a heating control circuit; Figure 9 This is an example circuit schematic diagram of a fourth low voltage difference linear voltage regulator circuit of the heating control circuit.

[0009] Reference numerals: 210, heating control circuit; 220, signal sensing circuit; 230, signal processing circuit; U2, low voltage dropout linear regulator chip; D1, first diode; Q2, first field effect transistor; R20, first resistor; R21, second resistor; U7, gas concentration thermocouple chip; R1, third resistor; R2, fourth resistor; C6, first capacitor; C7, second capacitor; C8, third capacitor; U8, microcontroller chip; C9, fourth capacitor; R3, fifth resistor; R4, sixth resistor; C5, fifth capacitor; J1, programmer. DETAILED DESCRIPTION

[0010] Current gas concentration sensors based on electrochemical or semiconductor principles require a lengthy warm-up period before they can function properly. As the chemical materials of these sensors degrade, their service life decreases. Current gas concentration sensors' multi-component gas concentration accuracy is severely affected by background gas interference, making it impossible to distinguish between the individual gases within a multi-component gas. Furthermore, their dynamic response characteristics are uncoupled from their temperature excitation strategies, resulting in insufficient detection accuracy.

[0011] To address the above technical issues, the present application provides a multi-component gas concentration detection method, which is applied to a gas concentration detection circuit and includes: obtaining a first calibrated concentration value and a first electrical signal corresponding to a first heating voltage for any gas, a first calibrated concentration value and a second electrical signal corresponding to a second heating voltage, and a first calibrated concentration value and a third electrical signal corresponding to a third heating voltage. A linear fit is performed based on the first calibrated concentration value and the first electrical signal of any gas to determine a first slope coefficient and a first intercept coefficient; a linear fit is performed based on the first calibrated concentration value and the second electrical signal of any gas to determine a second slope coefficient and a second intercept coefficient; and a linear fit is performed based on the first calibrated concentration value and the third electrical signal of any gas to determine a third slope coefficient and a third intercept coefficient. A calculation formula for the first electrical signal of any gas is determined based on the first calibrated concentration value, the first electrical signal, the first slope coefficient, and the first intercept coefficient of any gas. A first background signal and a first excitation signal corresponding to the first heating voltage are obtained for any gas. A superposition calculation formula for the first electrical signal of any gas is determined based on the first background signal, the first excitation signal, and the calculation formula for the first electrical signal. A first multi-component electrical signal calculation formula is determined based on the calculation formulas for the first electrical signals corresponding to at least two gases. Based on the first electrical signal superposition calculation formula and the first multi-component electrical signal calculation formula corresponding to the first heating voltage, respectively, the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage is determined. The second multi-component electrical signal superposition calculation formula corresponding to the second heating voltage and the third multi-component electrical signal superposition calculation formula corresponding to the third heating voltage are determined for the at least two gases. 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 simultaneous solution.

[0012] In the prior art, the thermal conductivity or electrical signal characteristics of multi-component gases at a single temperature overlap, making it difficult to distinguish the components. In contrast, this embodiment utilizes multiple heating voltages (corresponding to multiple different temperatures) to heat and calibrate the multi-component gas, enhancing the differences in thermal conductivity of the multi-component gas at different temperatures. This allows the gas concentration of each component to be determined without requiring the thermal conductivity of any gas in the multi-component gas by combining multiple multi-component electrical signal superposition calculation formulas. This implements a detection mechanism using multiple temperature step excitations, improves the efficiency of gas concentration detection for multi-component gases, and reduces the cost of detecting the concentration of each component in the multi-component gas.

[0013] The technical solution of this application is described below through specific embodiments.

[0014] like Figure 1 As shown, the first aspect of the present application provides a method for detecting the concentration of a multi-component gas, which is applied to a gas concentration detection circuit, comprising: S100, obtaining a first calibrated concentration value and a first electrical signal corresponding to a first heating voltage, a first calibrated concentration value and a second electrical signal corresponding to a second heating voltage, and a first calibrated concentration value and a third electrical signal corresponding to a third heating voltage of any gas.

[0015] In one embodiment, any gas here refers to a single target gas, such as oxygen, nitrogen, carbon monoxide or water vapor. According to the needs of the actual scene, any gas can also be any gas required by the scene, such as carbon dioxide, sulfur dioxide, etc. This method calibrates each individual gas in the multi-component gas separately, applies a first heating voltage at a first calibration concentration value of the individual gas, and obtains a first electrical signal corresponding to the individual gas, the first heating voltage and the first calibration concentration value; applies a second heating voltage at the first calibration concentration value of the individual gas, and obtains a second electrical signal corresponding to the individual gas, the second heating voltage and the first calibration concentration value; applies a third heating voltage at the first calibration concentration value of the individual gas, and obtains a third electrical signal corresponding to the individual gas, the third heating voltage and the first calibration concentration value; thereby, based on the three calibration data, the corresponding linear relationship between the gas concentration value, heating voltage and electrical signal of each individual gas is obtained.

[0016] S110, performing linear fitting based on the first calibrated concentration value of any gas and the first electrical signal to determine the first slope coefficient and the first intercept coefficient, performing linear fitting based on the first calibrated concentration value of any gas and the second electrical signal to determine the second slope coefficient and the second intercept coefficient, and performing linear fitting based on the first calibrated concentration value of any gas and the third electrical signal to determine the third slope coefficient and the third intercept coefficient.

[0017] In one embodiment, under the same heating voltage, that is, at the same temperature, there is a corresponding linear relationship between the gas concentration value and the electrical signal of any gas. Under the first heating voltage, the first calibrated concentration value and the first electrical signal are linearly fitted to determine the first slope coefficient and the first intercept coefficient. Under the second heating voltage, the first calibrated concentration value and the second electrical signal are linearly fitted to determine the second slope coefficient and the second intercept coefficient. Under the third heating voltage, the first calibrated concentration value and the third electrical signal are linearly fitted to determine the third slope coefficient and the third intercept coefficient. Specifically, the first calibrated concentration value has at least two value points, and the values ​​are obtained according to the purchased gas packaging label, that is, two calibrated concentration values ​​and the first electrical signal can be obtained respectively, and a straight line can be determined based on the two points to obtain the first slope coefficient and the first intercept coefficient. In this method, there are exactly four value points for the first calibrated concentration value, which eliminates the identification error or measurement error of the purchased gas concentration value.

[0018] S120 , determining a calculation formula for the first electrical signal of any gas based on the gas concentration value of any gas, the first electrical signal, the first slope coefficient, and the first intercept coefficient.

[0019] In one embodiment, the calculation formula for the first calibration signal of any gas A is: rawdata_A1=k_A1×PPM_A+d_A1; Among them, rawdata_A1 is the first electrical 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.

[0020] Similarly, the calculation formula for the second calibration signal of any gas A under the second heating voltage is obtained, rawdata_A2=k_A2×PPM_A+d_A2; where rawdata_A2 is the second electrical 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.

[0021] Similarly, the third calibration signal calculation formula for any gas A under the third heating voltage is rawdata_A3=k_A3×PPM_A+d_A3; where rawdata_A3 is the third electrical 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.

[0022] In this embodiment, after any gas A is calibrated, the gas concentration value corresponding to the electrical signal can be determined through the electrical signal according to the electrical signal calculation formula when the first slope coefficient and the first intercept coefficient are known.

[0023] 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.

[0024] In one embodiment, the calculation formula for the first calibration signal of any gas B is: rawdata_B1=k_B1×PPM_B+d_B1; Among them, rawdata_B1 is the first electrical 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.

[0025] In one embodiment, the calculation formula for the second calibration signal of any gas B under the second heating voltage is: rawdata_B2=k_B2×PPM_B+d_B2; wherein rawdata_B2 is the second electrical 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.

[0026] In one embodiment, the calculation formula for the third calibration signal of any gas B under the third heating voltage is: rawdata_B3=k_B3×PPM_B+d_B3; wherein rawdata_B3 is the third electrical 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.

[0027] Similarly, in another embodiment, the multi-component gas includes three 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; and the first calibration signal calculation formula of any gas C 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.

[0028] In one embodiment, the calculation formula for the first calibration signal of any gas C is: rawdata_C1=k_C1×PPM_C+d_C1; Wherein, rawdata_C is the first electrical 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; d_C1 is the first intercept coefficient of any gas C.

[0029] In one embodiment, the calculation formula for the second calibration signal of any gas C under the second heating voltage is: rawdata_C2=k_C2×PPM_C+d_C2; wherein rawdata_C2 is the second electrical signal of any gas C; k_C2 is the second slope coefficient of any gas C; d_C2 is the second intercept coefficient of any gas C.

[0030] In one embodiment, the calculation formula for the third calibration signal of any gas C under the third heating voltage is: rawdata_C3=k_C3×PPM_C+d_C3; wherein rawdata_C3 is the third electrical signal of any gas C; k_C3 is the third slope coefficient of any gas C; d_C3 is the third intercept coefficient of any gas C.

[0031] It should be noted that the single gases used in the calibration step of the signal sensing circuit in the multi-component gas concentration detection circuit (specifically, the calibration of the gas concentration thermocouple chip) in the present application are all single gases of any component used for special calibration. The multiple values ​​of the first calibration concentration of the single gas can be calibrated multiple times with the same heating voltage to obtain the electrical signal corresponding to the single same heating voltage, and then the slope coefficient and intercept coefficient corresponding to the single calibration of the same heating voltage are obtained; the certain concentration value of the single gas can also be calibrated multiple times with different heating voltages to obtain the electrical signal corresponding to a single arbitrary heating voltage, and then the slope coefficient and intercept coefficient corresponding to a single arbitrary heating voltage of the single gas are obtained; in addition, based on the above two calibration methods, each of the different concentration values ​​of the single gas can be calibrated multiple times with the same and / or different heating voltages to obtain the electrical signal corresponding to the single same heating voltage of a certain concentration value of the single gas and / or the electrical signal corresponding to the single arbitrary heating voltage of each concentration value of the single gas, and then the slope coefficient and intercept coefficient corresponding to the single same heating voltage and / or the slope coefficient and intercept coefficient corresponding to the single arbitrary heating voltage are obtained.

[0032] S130 , obtaining a first background signal and a first excitation signal corresponding to a first heating voltage of any gas.

[0033] In one embodiment, under the same gas and the same heating voltage, the electrical signal responded by the gas concentration detection circuit is the superposition of the background signal and the gas excitation signal, so the sum of the first background signal and the first excitation signal of any gas under the first heating voltage can be obtained. The sum of the second background signal and the second excitation signal of any gas under the second heating voltage can also be obtained, and the sum of the third background signal and the third excitation signal of any gas under the third heating voltage can also be obtained. Since the hardware is the same, the hardware environment for calibration and the hardware environment for testing are also the same, so the first background signals between gases of different components are all the same, the second background signals between gases of different components are all the same, and the third background signals between gases of different components are also all the same. In addition, the first background signal, the second background signal, and the third background signal are obtained by obtaining different background signals under different heating voltages without introducing the gas to be measured.

[0034] S140 , determining a first electrical signal superposition calculation formula for any gas based on the first background signal, the first excitation signal, and the first electrical signal calculation formula.

[0035] In one embodiment, the superposition calculation formula of the first electrical signal of any gas A 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 of any gas A corresponding to the first heating voltage.

[0036] In one embodiment, the superposition calculation formula of the first electrical signal of any gas B is: rawdata_B1=base1+Δrawdata_B1; Wherein, rawdata_B1 is the first electrical signal of any gas B; base1 is the first background signal corresponding to the first heating voltage; Δrawdata_B1 is the first excitation signal of any gas B corresponding to the first heating voltage.

[0037] In one embodiment, the superposition calculation formula of the first electrical signal of any gas C is: rawdata_C1=base1+Δrawdata_C1; Wherein, rawdata_C1 is the first electrical signal of any gas C; base1 is the first background signal corresponding to the first heating voltage; Δrawdata_C1 is the first excitation signal of any gas C corresponding to the first heating voltage.

[0038] S150: Determine a first multi-component electrical signal calculation formula based on first electrical signal calculation formulas corresponding to at least two gases.

[0039] 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 a first multi-component electrical signal calculation formula including the two gas components. The first multi-component electrical signal calculation formula including the two gas components is: rawdata_A1+rawdata_B1=k_A1×PPM_A+k_B1×PPM_B+(d_A1+d_B1); Among them, rawdata_A1 is the first electrical signal of any gas A; rawdata_B1 is the first electrical 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; d_B1 is the first intercept coefficient of any gas B.

[0040] Based on this, there are only two unknowns, PPM_A and PPM_B, in the above formula. The second multi-component electrical signal calculation formula can be obtained based on the second heating voltage, and the two unknowns, PPM_A and PPM_B, can be calculated.

[0041] In another embodiment, the first calibration signal calculation formula of any gas A among 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 a first multi-component electrical signal calculation formula including the three gas components. The first multi-component electrical signal calculation formula including the three gas components 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); Among them, rawdata_A1 is the first electrical signal of any gas A; rawdata_B1 is the first electrical signal of any gas B; rawdata_C1 is the first electrical 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.

[0042] S160 , determining a first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage 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.

[0043] In one embodiment, determining the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage 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 includes: Based on the first electrical signal superposition calculation formula and the first multi-component electrical signal calculation formula corresponding to the at least two gases, a transformation is performed to determine a first multi-component electrical signal superposition transition calculation formula corresponding to the first heating voltage; 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.

[0044] The calculation formula for the superposition transition of the first multi-component electrical signal including two gas components is: base1+Δrawdata_A1+Δrawdata_B1=k_A1×PPM_A+k_B1×PPM_B+(d_A1+d_B1-base1); Among them, 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.

[0045] In one embodiment, the first multi-component electrical signal superposition calculation formula including two gas components is: rawdata1=k_A1×PPM_A+k_B1×PPM_B+(d_A1+d_B1-base1); Among them, 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 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.

[0046] In another embodiment, the first multi-component electrical signal superposition calculation formula including three gas components is: rawdata1=k_A1×PPM_A+k_B1×PPM_B+k_C1×PPM_C+(d_A1+d_B1+d_C1-2×base1); Among them, 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 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; base1 is the background signal corresponding to the first heating voltage.

[0047] S170, determining a second multi-component electrical signal superposition calculation formula corresponding to the second heating voltage and a third multi-component electrical signal superposition calculation formula corresponding to the third heating voltage of at least two gases.

[0048] In another embodiment, the second multi-component electrical signal superposition calculation formula including three gas components is: Rawdata2=k_A2×PPM_A+k_B2×PPM_B+k_C2×PPM_C+(d_A2+d_B2+d_C2-2×base2); Among them, rawdata2 is the second multi-component superposition electrical signal corresponding to the multi-component gas and the second heating voltage; k_A2 is the second slope coefficient of any gas A; k_B2 is the second slope coefficient of any gas B; k_C2 is the second 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_A2 is the first intercept coefficient of any gas A; d_B2 is the first intercept coefficient of any gas B; d_C2 is the first intercept coefficient of any gas C; base2 is the second background signal corresponding to the first heating voltage.

[0049] In another embodiment, the third multi-component electrical signal superposition calculation formula including three gas components is: Rawdata3=k_A3×PPM_A+k_B3×PPM_B+k_C3×PPM_C+(d_A3+d_B3+d_C3 - 2×base3); Among them, rawdata3 is the third multi-component superposition 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.

[0050] It should be noted that if the multi-component gas has multiple components, it is necessary to confirm the first multi-component electrical signal superposition calculation formula, the second multi-component electrical signal superposition calculation formula, the third multi-component electrical signal superposition calculation formula and the fourth multi-component electrical signal superposition calculation formula, etc. The number of multi-component electrical signal superposition calculation formulas corresponds to the number of components.

[0051] S180, 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, jointly solve and determine the gas concentration value of any gas in the multi-component gas.

[0052] In another embodiment, in 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, there are only three unknowns, namely PPM_A, PPM_B, and PPM_C, and the others are known, so the gas concentration values ​​of each gas component can be obtained by solving them jointly.

[0053] In another embodiment, if the multi-component gas has four components, it is necessary to add calibration under the fourth heating voltage to obtain the first multi-component electrical signal superposition calculation formula, the second multi-component electrical signal superposition calculation formula, the third multi-component electrical signal superposition calculation formula and the fourth multi-component electrical signal superposition calculation formula, and then solve them jointly to obtain the gas concentration value of each gas component. By analogy, the concentrations of the five gases in the component gas can also be tested to obtain the first calibrated concentration value and the first electrical signal corresponding to the first heating voltage, the first calibrated concentration value and the second electrical signal corresponding to the second heating voltage, the first calibrated concentration value and the third electrical signal corresponding to the third heating voltage, the first calibrated concentration value and the fourth electrical signal corresponding to the fourth heating voltage, and the first calibrated concentration value and the fifth electrical signal corresponding to the fifth heating voltage; and then determine the first electrical signal calculation formula, the second electrical signal calculation formula, the third electrical signal calculation formula, the fourth electrical signal calculation formula, and the fifth electrical signal calculation formula of the five gases; and then determine the first multi-component electrical signal superposition calculation formula, the second multi-component electrical signal superposition calculation formula, the third multi-component electrical signal superposition calculation formula, the fourth multi-component electrical signal superposition calculation formula, and the fifth multi-component electrical signal superposition calculation formula, and then solve them jointly to obtain the gas concentration values ​​of the five gases in the component gas.

[0054] In some embodiments, steps S100 to S120 are performed at a calibrated ambient temperature, but step S130 may not be performed at a calibrated ambient temperature, resulting in a temperature error. To improve the accuracy of gas concentration detection, step S130 further includes the following steps: S131: Acquire a current first background signal under a current ambient temperature and a first heating voltage, and a current first excitation signal corresponding to any gas; S132: Calculate the temperature compensation incremental electrical signal as Sens_DltSRaw, Sens_DltSRaw=Tcomp_Coe0+Tcomp_Coe1*(Tmpr_DltTRaw)+Tcomp_Coe2*(Tmpr_DltTRaw)*(Tmpr_DltTRaw)+Tcomp_Coe3*(Tmpr_DltTRaw)*(Tmpr_DltTRaw)*(Tmpr_DltTRaw), where the current ambient temperature is Tmpr_TRaw, the calibrated ambient temperature is TComp_TRawBase, the difference between the current ambient temperature Tmpr_TRaw and the calibrated 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.

[0055] The cubic polynomial (including terms from zero to three orders) can flexibly fit this complex nonlinear relationship through coefficients (Tcomp_Coe0 to Tcomp_Coe3). Compared with using only linear compensation (first-order terms) or quadratic compensation, it can significantly reduce the compensation error in different temperature ranges, making the corrected signal closer to the electrical signal corresponding to the actual concentration, ensuring that the alarm threshold is based on a real and reliable signal, and improving the safety factor of the entire detection system.

[0056] Specifically, before step S132, the method further includes the following steps: S1321: Under the calibration ambient temperature, a gas concentration sensor is used to obtain a first temperature scale electrical signal corresponding to a PPM of any gas being 0.

[0057] S1322: At the first reference temperature, a gas concentration sensor is used to obtain a second temperature scale electrical signal corresponding to a PPM of any gas being 0.

[0058] S1323: At the second reference temperature, a gas concentration sensor is used to obtain a third temperature scale electrical signal corresponding to a PPM of any gas being 0.

[0059] S1324: At the third reference temperature, a gas concentration sensor is used to obtain a fourth temperature scale electrical signal corresponding to when the PPM of any gas is 0.

[0060] S1325: Based on steps S1321 to S1324, the zero-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.

[0061] When the PPM of any gas is 0, the sensor's electrical signal drift is caused solely by temperature changes (excluding interference from gas concentration). Steps S1321 through S1324 list four equations, which can be solved simultaneously to yield four temperature compensation coefficients (Tcomp_Coe0 through Tcomp_Coe3).

[0062] S133: A temperature-compensated first background signal is obtained based on the difference between the current first background signal and the temperature-compensated incremental electrical signal. A temperature-compensated first excitation signal is obtained based on the difference between the current first excitation signal and the temperature-compensated incremental electrical signal. In step S140, a superposition formula for the first electrical signal is determined using the temperature-compensated first background signal and the temperature-compensated first excitation signal.

[0063] In some embodiments, steps S100 to S120 are performed at a calibrated humidity, but step S130 may not be performed at a calibrated humidity, resulting in humidity errors. To improve the accuracy of gas concentration detection, after step S133, the method further includes the following steps: S134: Use the humidity sensor to obtain humidity increment. The humidity increment is the difference between the current humidity and the calibrated humidity. The calibrated humidity can be set to 0%.

[0064] S135: Calculate the humidity compensation based on the humidity increment and temperature increment. The effect of humidity on gas thermal conductivity is not fixed but varies with temperature (for example, at the same humidity, the thermal conductivity of water vapor in a high-temperature environment differs from that in a low-temperature environment). By incorporating a temperature coefficient into the calculation of the humidity compensation, the humidity compensation weight can be dynamically adjusted at different temperatures, avoiding undercompensation caused by ignoring the interaction between temperature and humidity, and ensuring that humidity correction is more consistent with actual physical laws.

[0065] Specifically, before step S135 , the humidity compensation amount H_comp is first solved, H_comp=Hcomp_Coe0+Hcomp_Coe1×Tmpr_DltTRaw+Hcomp_Coe2×H_delta+Hcomp_Coe3×Tmpr_DltTRaw×H_delta.

[0066] The specific solution process involves calibration experiments at different humidity levels (e.g., 0%, 10%, 30%, and 50%) at a calibrated ambient temperature (T0). The resulting zero-order humidity compensation coefficient Hcomp_Coe0 (a constant term used to correct baseline deviation), the temperature compensation coefficient Hcomp_Coe1 (weight associated with the temperature parameter), the humidity compensation coefficient Hcomp_Coe2 (weight associated with the humidity delta), and the interaction coefficient Hcomp_Coe3 (related to the cross-effect between temperature and humidity) are fitted. The current humidity (H_current) is read using a humidity sensor; the humidity delta (H_delta) is calculated as: current humidity H_current - calibrated humidity H0 (since H0 = 0%, H_delta = H_current). Solving these four equations yields the zero-order humidity compensation coefficient Hcomp_Coe0, the temperature compensation coefficient Hcomp_Coe1, the humidity compensation coefficient Hcomp_Coe2, and the interaction coefficient Hcomp_Coe3.

[0067] S136: Humidity compensation is performed on the temperature-compensated first background signal and the temperature-compensated first excitation signal using the humidity compensation amount, resulting in the wet-compensated first background signal and the wet-compensated first excitation signal. Temperature compensation is performed first, followed by humidity compensation, making the correction logic for the two environmental factors independent of each other. This decoupling design facilitates the separate optimization of the humidity and temperature compensation parameters, reducing debugging difficulty. Specifically, the wet-compensated first background signal = the temperature-compensated first background signal - the humidity compensation amount, and the wet-compensated first excitation signal = the temperature-compensated first excitation signal - the humidity compensation amount, and then proceeds to step S140.

[0068] In some embodiments, after step S136, the method further includes the following steps: S137: Use the air pressure sensor to obtain the air pressure increment.

[0069] S138: Based on the pressure increment, a pressure parameter is obtained. After correction using the pressure parameter, the detection values ​​under different pressure environments are normalized to the standard pressure reference, ensuring a consistent logic for determining the alarm threshold and avoiding safety risks caused by pressure differences. Specifically, the pressure parameter = 1 + k × pressure increment, where k is the pressure calibration factor.

[0070] Specifically, the pressure calibration coefficient k is obtained through a pressure calibration experiment. The corresponding relationship between the pressure increment and the concentration deviation is established, and finally the pressure calibration coefficient k is obtained by fitting calculation. Optionally, under the calibration pressure P0, calibration temperature, and calibration humidity, the calibration gas (such as nitrogen or carbon dioxide) uses a preset concentration, such as 2000 PPM, and a closed container with adjustable pressure is used to simulate an environment of 0.5 to 1.2 times the calibration pressure. First, the detection value C of the gas concentration sensor under different pressures P is collected. 测, second, calculate the ideal concentration value C caused by the pressure change 理 =C0×(P / P0), third, according to 1+k×ΔP=C 理 / C 测 , obtain k, and use the least squares method to fit the k values ​​of multiple pressure points, take the average or best fitting value to obtain the pressure calibration coefficient k.

[0071] S139: Divide the first background signal after moisture replenishment and the first excitation signal after moisture replenishment by the air pressure parameter respectively to obtain the first background signal and the first excitation signal after air pressure compensation, and then proceed to step S140.

[0072] Gas concentration (PPM) is essentially the number of target gas molecules per unit volume, and air pressure directly affects gas volume. When air pressure decreases (such as at high altitude), the gas volume expands, and the "number of molecules per unit volume" for the same number of molecules will be falsely lower (the actual concentration remains unchanged, but the signal is displayed as lower). Without pressure compensation, the same actual concentration will be converted to different PPM values ​​at different air pressures. Using pressure parameter correction (dividing the signal by the pressure parameter, essentially normalizing it to the concentration at standard pressure) can eliminate this error caused by air pressure fluctuations, making the test results more accurate to the gas's true molecular density.

[0073] Combine Figure 3 The gas concentration thermocouple chip U7 of the signal sensing circuit 220 has two MEMS thermal conductivity chips. When the heating voltage is turned on, in the first MEMS thermal conductivity chip, the resistor 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 tiny electrical signal based on the heat transferred from the gas molecules. Similarly, in the second MEMS thermal conductivity chip, the resistor between the third port REF_HTR1 and the sixth port REF_HTR2 generates a heat source, and the thermocouple between the fourth port REF_TH+ pin and the fifth port REF_TH- pin generates an electrical signal accordingly. The second MEMS thermal conductivity chip is sealed in dry air. 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 is also used to simulate any gas PPM being 0. Therefore, in steps S1321 to S1324 , the first temperature-scale electrical signal to the fourth temperature-scale electrical signal are acquired respectively.

[0074] In some embodiments, S100-S120 are performed on a calibrated gas concentration thermocouple chip U7. Due to the varying manufacturing tolerances 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 resistance baseline drift after long-term use. Optionally, the method further includes the following steps: S1311: Before step S131, obtain a calibration resistance R_ref at 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.

[0075] S1312: Under the first heating voltage, obtain a measured resistance. The measured resistance refers to the resistance value between the first port MEA_HTR1 and the eighth port MEA_HTR2 of the currently used gas concentration thermocouple chip U7.

[0076] 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 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 threshold, resistance compensation is performed. Optionally, the calibration threshold is 10% of the calibration resistance.

[0077] Specifically, based on the temperature coefficient of resistance TCR, the resistance deviation ΔR is converted to the temperature deviation ΔT. According to the formula TCR=(R2-R1) / (R1*(T2-T1)), it is derived that ΔT=ΔR / (R_ref*TCR), where TCR is the inherent value of the material. Further, in step S132, the current ambient temperature Tmpr_TRaw is equal to the measured temperature T of the temperature sensor. 测 +Temperature deviation ΔT.

[0078] It should be noted that when a single gas is calibrated with different concentrations, each concentration corresponding to a different heating voltage, the detection method of the present application can also be used to obtain the gas concentration value of each gas component. When this calibration method is used, the accuracy of the multi-component gas concentration can be further increased.

[0079] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0080] like Figure 2 As shown, the second aspect of the present application provides a multi-component gas concentration detection circuit, which is used to implement the multi-component gas concentration detection method as described in any one of the first aspects. The detection circuit 200 includes: The heating control circuit 210 includes multiple low-voltage difference linear voltage regulator circuits, which are used to control each low-voltage difference linear voltage regulator circuit in turn to output multiple heating voltages to the signal sensing circuit. The number of low-voltage difference linear voltage regulator circuits is greater than or equal to the number of gas types in the multi-component gas.

[0081] The signal sensing circuit 220 includes a gas concentration thermocouple chip, which is used to receive each heating voltage respectively and sense the concentration changes of the multi-component gas in the measured environment; when the concentration of the multi-component gas changes, the gas concentration thermocouple chip will output a differential voltage signal of the multi-component gas concentration change corresponding to the heating voltage to the signal processing circuit. The differential voltage signal includes a background signal and an excitation signal. The gas concentration thermocouple chip includes a sealed first single thermocouple chip and a second single thermocouple chip with a hole.

[0082] Signal processing circuit 230 includes a microcontroller chip, which is used to drive the heating control circuit to output multiple heating voltages, receive differential voltage signals from the signal sensing circuit, and determine the gas concentration value of each gas component in the multi-component gas through signal processing. Optionally, signal processing circuit 230 also includes a communication interface for reading the output signal of the gas concentration thermocouple chip and controlling the gas concentration thermocouple chip.

[0083] In one embodiment, the heating control circuit includes at least three low-voltage difference linear voltage regulator circuits; any low-voltage difference linear voltage regulator circuit includes a low-voltage difference linear voltage 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 three low-voltage difference linear voltage regulator circuits; when the number of components of the multi-component gas is 3, the heating control circuit includes four low-voltage difference linear voltage regulator circuits.

[0084] In one embodiment, combined Figures 6 to 9 The number of components of the multi-component gas is 3, and the heating control circuit 210 includes a first low-voltage difference linear voltage regulator circuit (see Figure 6 ), the second low voltage difference linear voltage regulator circuit (see Figure 7 ), the third low voltage difference linear voltage regulator circuit (see Figure 8 ), the fourth low voltage difference linear voltage regulator circuit (see Figure 9 );like Figure 6As shown, the first low-voltage difference linear voltage regulator circuit includes a low-voltage difference linear voltage 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 to the ground in parallel; the drain D of the first field-effect transistor Q2 is connected to the ground port GND of the low-voltage difference linear voltage regulator chip U2; the enable port EN / NC of the low-voltage difference linear voltage 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-voltage difference linear voltage 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.

[0085] It should be noted that if the multi-component gas includes two gas components, the heating control circuit includes at least three low-voltage differential linear voltage regulator circuits; if the multi-component gas includes three gas components, the heating control circuit includes at least four low-voltage differential linear voltage regulator circuits, so that the heating voltages of different gas components can be staggered, making the gas concentration test more accurate. The low-voltage differential linear voltage regulator circuit that outputs the first heating voltage is called the first low-voltage differential linear voltage regulator circuit, the low-voltage differential linear voltage regulator circuit that outputs the second heating voltage is called the second low-voltage differential linear voltage regulator circuit, the low-voltage differential linear voltage regulator circuit that outputs the third heating voltage is called the third low-voltage differential linear voltage regulator circuit, and the low-voltage differential linear voltage regulator circuit that outputs the fourth heating voltage is called the fourth low-voltage differential linear voltage regulator circuit; for example, the heating voltage output by the first low-voltage differential linear voltage regulator circuit is 4.5V, the heating voltage output by the second low-voltage differential linear voltage regulator circuit is 3.3V, the heating voltage output by the third low-voltage differential linear voltage regulator circuit is 1.8V, and the heating voltage output by the fourth low-voltage differential linear voltage regulator circuit is 1.2V.

[0086] In one embodiment, 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 sealed first single thermocouple chip and a second single thermocouple chip with a hole; the first port MEA_HTR1 of the gas concentration thermocouple chip U7 is connected to the AN2 input end and one end of the fourth resistor R2, the third port REF_HTR1 is connected to the 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 the heating voltage signal input end VHT for receiving Receive each heating voltage, where the AN2 input terminal and the AN3 input terminal are used to receive the control signal of the body concentration thermocouple chip; the second port of the gas concentration thermocouple chip U7 outputs a differential voltage signal of the change of the multi-component gas concentration, and the fourth port of the gas concentration thermocouple chip U7 outputs a differential voltage signal of the change of the reference gas concentration. The fifth port and the seventh port of the gas concentration thermocouple chip U7 are connected to the raised voltage signal output terminal VCM and one end of the third capacitor C8 to output a raised voltage signal (equivalent to introducing a DC component), 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 connected to the ground in parallel. The first and third ports MEA_HTR1 and REF_HTR1 of the gas concentration thermocouple chip U7 simultaneously receive the heating voltage VHT output by any low-voltage differential linear regulator circuit. The second port of the gas concentration thermocouple chip U7 outputs a weak differential voltage signal corresponding to the change in multi-component gas concentration, namely, a second differential voltage signal AN1, and the seventh port outputs a compensation signal for the differential voltage corresponding to the change in multi-component gas concentration. The fourth port of the gas concentration thermocouple chip U7 outputs a weak differential voltage signal corresponding to the change in reference gas concentration, namely, a first differential voltage signal AN0, and the fifth port outputs a compensation signal for the differential voltage corresponding to the change in reference gas concentration. The weak differential voltage signal corresponding to the change in multi-component gas concentration is output through the AN1 terminal, the weak differential voltage signal corresponding to the change in reference gas concentration is output through the AN0 terminal, and the VCM terminal outputs the compensation signal for the differential voltage, namely, a raised voltage signal. The third and fourth resistors R1 and R2 are used to divide the heating voltage. The first, second, and third capacitors C6, C7, and C8 all function as filters. For example, if the weak signal of the differential voltage output from the AN0 and AN1 terminals is 100 mV and the compensation signal of the differential voltage output from the VCM terminal is 12 V, the signal output to the signal processing circuit 230 is 12.01 V, which amplifies the differential voltage signal of the gas concentration change.

[0087] 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 voltage difference linear voltage regulator circuit to heat for a first preset time, and then stop heating for a second preset time. The first preset time is equal to or not equal to the second preset time. For example, the first preset time is 100ms and the second preset time is 100ms; for another example, the first preset time is less than the second preset time, so as to avoid the increase of error caused by excessive heating time, thereby improving the accuracy of gas concentration changes.

[0088] It should be noted that the gas concentration thermocouple chip includes a sealed first single thermocouple chip ( Figure 3 The chip below U7) and the second single thermocouple chip with a hole ( Figure 3 (The chip above U7 in the figure) When a preset heating voltage is applied between MEA_HTR1 and MEA_HTR2, or REF_HTR1 and REF_HTR2, of these two gas concentration thermocouple chips (the preset voltage is the VHT terminal and may vary depending on the actual application scenario), a stable heat source is generated between MEA_HTR1 and MEA_HTR2, or REF_HTR1 and REF_HTR2. Heat from this heat source is transferred to other solid surfaces through gas molecules in the environment. A thermopile is located between MEA_TH+ and MEA_TH-, or REF_TH+ and REF_TH-. The thermopile generates a small electrical signal based on the changes in heat transferred from the gas molecules. The higher the concentration of any gas component, the more heat it carries, resulting in a larger change in the electrical signal. Therefore, the changes in the electrical signal generated by this gas concentration thermocouple chip can be used to calculate the concentration of the target gas in the measured environment. This application avoids changes in the electrical signals between MEA_TH+ and MEA_TH- or REF_TH+ and REF_TH- caused by heat changes caused by other media in the environment, thereby avoiding measurement deviations caused thereby. The sealed first single thermocouple chip is sealed in dry air. The sealed dry air has a fixed volume concentration, its thermal conductivity is fixed, and the amount of heat transferred is also fixed. Therefore, if the electrical signal of the sealed first single thermocouple chip changes, it must be caused by temperature changes in the external environment.

[0089] In one embodiment, Figure 4 As shown, Figure 4 C8 Figure 3 The third capacitor in the signal processing circuit 230 includes a microcontroller chip U8 (see Figure 5), fourth capacitor C9, fifth resistor R3, sixth resistor R4, fifth capacitor C5, 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 second differential voltage signal of the multi-component gas concentration change output by the second port of the gas concentration thermocouple chip U7; 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 the control signal for driving the heating control circuit (in this embodiment, since there are 4 low-voltage difference linear voltage regulator circuits, 4 ports are used for output; when there are only 3 low-voltage difference linear voltage regulator circuits, 3 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 value of each component gas in the multi-component gas determined after signal processing.

[0090] It can be understood that the signal processing circuit collects the differential electrical signal from the signal sensing circuit for processing. After the microcontroller (MCU) receives the differential electrical signal, the MCU includes advanced analog-to-digital conversion (ADC) functions. The ADC inside the microcontroller can perform differential voltage input, small signal amplification, and other functions. It can distinguish and calculate the signal differences caused by the change in gas concentration of any gas component and the differences caused by interference factors. The processed data can have a reasonable correspondence with the gas concentration of any gas component. This correspondence is generally linear: the higher the measured gas concentration, the greater the output value of the signal processing circuit. Conversely, the lower the measured gas concentration, the smaller the output value of the signal processing circuit.

[0091] It should be noted that the data obtained by the MCU is the data converted by the ADC, which is called raw data. The data converted by the ADC corresponds to the voltage level of the ADC, which corresponds to the voltage signal mentioned above. This voltage signal corresponds to the gas concentration value of any gas component. Therefore, the raw data obtained by the MCU and the gas concentration are in a one-to-one correspondence. This Rawdata value and gas concentration value may not be intuitive or directly corresponding, but the flow rate information is already included in the Rawdata. Afterwards, according to the specific situation of the user, the Rawdata data can be subsequently processed to make it more suitable for specific application scenarios. This process is called "calibration."

[0092] It should be noted that Figures 3 to 9Only the parts related to this embodiment are shown.

[0093] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0094] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0095] In the embodiments provided in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0096] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for detecting the concentration of a multi-component gas, characterized in that: The detection circuit used for multi-component gas concentration includes: Obtaining a first calibrated concentration value and a first electrical signal corresponding to a first heating voltage, the first calibrated concentration value and a second electrical signal corresponding to a second heating voltage, and the first calibrated concentration value and a third electrical signal corresponding to a third heating voltage for any gas; Performing a linear fit based on the first calibrated concentration value of any gas and the first electrical signal to determine a first slope coefficient and a first intercept coefficient, performing a linear fit based on the first calibrated concentration value of any gas and the second electrical signal to determine a second slope coefficient and a second intercept coefficient, and performing a linear fit based on the first calibrated concentration value of any gas and the third electrical signal to determine a third slope coefficient and a third intercept coefficient; Determine a calculation formula for a first electrical signal of any gas based on the first calibration concentration value of any gas, the first electrical signal, the first slope coefficient, and the first intercept coefficient; Acquire a first background signal and a first excitation signal corresponding to the first heating voltage for any gas; Determine a first electrical signal superposition calculation formula for any gas based on the first background signal, the first excitation signal, and the first electrical signal calculation formula; Determining a first multi-component electrical signal calculation formula based on the first electrical signal calculation formulas corresponding to at least two gases respectively; Determining the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage 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; Determining a second multi-component electrical signal superposition calculation formula corresponding to the second heating voltage and a third multi-component electrical signal superposition calculation formula corresponding to the third heating voltage for at least two gases; 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 simultaneous solution.

2. The method for detecting the concentration of a multi-component gas according to claim 1, wherein: The calculation formula of 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 calibration 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.

3. The method for detecting the concentration of a multi-component gas according to claim 1, wherein: The first electrical signal superposition calculation formula is: rawdata_A1=base1+Δrawdata_A1; Wherein, rawdata_A1 is the first electrical signal of any gas A; base1 is a first background signal corresponding to the first heating voltage; Δrawdata_A1 is a 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 according to claim 1, wherein: The calculation formula of 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 of any gas B; rawdata_C1 is the first electrical 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.

5. The method for detecting the concentration of a multi-component gas according to claim 1, wherein: The step of determining the first multi-component electrical signal superposition calculation formula corresponding to the first heating voltage 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 includes: Determine a first multi-component electrical signal superposition transition calculation formula corresponding to the first heating voltage by performing a transformation 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; 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.

6. The method for detecting the concentration of a multi-component gas according to claim 1, wherein: The calculation formula for 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); Among them, 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 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_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 a first background signal corresponding to the first heating voltage.

7. A multi-component gas concentration detection circuit, characterized in that: Used to implement the method for detecting the concentration of a multi-component gas according to any one of claims 1 to 6, the detection circuit includes a heating control circuit, a signal sensing circuit and a signal processing circuit; The heating control circuit includes a plurality of low-pressure-difference linear voltage regulator circuits, which are used to sequentially control each of the low-pressure-difference linear voltage regulator circuits to output a plurality of heating voltages to the signal sensing circuit, wherein the number of the low-pressure-difference linear voltage regulator circuits is greater than or equal to the number of types of gases to be measured in the multi-component gas; The signal sensing circuit includes a gas concentration thermocouple chip, which is used to receive each of the heating voltages and sense the concentration changes 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 multi-component gas concentration change of the heating voltage, and the differential voltage signal includes a background signal and an excitation signal. The gas concentration thermocouple chip includes a sealed first single thermocouple chip and a second single thermocouple chip with a hole; The signal processing circuit includes a microcontroller chip, which is used to drive the heating control circuit to output multiple heating voltages, receive the differential voltage signal of the signal sensing circuit, and determine the gas concentration value of each component gas in the multi-component gas through signal processing; and also includes a communication interface for reading the output signal of the gas concentration thermocouple chip and controlling the gas concentration thermocouple chip.

8. The multi-component gas concentration detection circuit according to claim 7, characterized in that: The heating control circuit includes at least three of the low voltage difference linear voltage regulator circuits; any of the low voltage difference linear voltage regulator circuits includes a low voltage difference linear voltage 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 the control signal sent by the signal processing circuit; The source of the first field effect transistor, the other end of the first resistor, and one end of the second resistor are connected to the ground in parallel; The drain of the first field effect transistor is connected to the ground port of the low voltage difference linear voltage regulator chip; The enable port of the low voltage difference linear voltage regulator chip is connected to the cathode of the first diode and the other end of the second resistor; The output port of the low voltage difference linear voltage regulator chip outputs the heating voltage to the signal sensing circuit.

9. The multi-component gas concentration detection circuit according to claim 7, 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 second single thermocouple chip with a hole; 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 end for receiving each of the heating voltages; The second port of the gas concentration thermocouple chip outputs a first differential voltage signal indicating a change in the concentration of the multi-component gas, the fourth port of the gas concentration thermocouple chip outputs a second differential voltage signal indicating a change in the concentration of the reference gas, the fifth port and the seventh port 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 port, the sixth port, the ninth port, and the tenth port of the gas concentration thermocouple chip are connected to the ground in parallel.

10. The multi-component gas concentration detection circuit according to claim 7, 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 burner; The eighth port of the microcontroller chip is connected to one end of the fourth capacitor and receives a first differential voltage signal of a 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 a 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 output control signals for driving the heating control circuit; The twenty-third port and the twenty-fourth port of the microcontroller chip output the gas concentration value of each component gas in the multi-component gas determined through signal processing.

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