Multi-component gas concentration detection method and detection system based on alternating excitation

Abstract

The invention discloses a multi-component gas concentration detection method and detection system based on alternating excitation, based on the specificity of different gas components to different alternating excitation signals, different alternating excitation signals are utilized to excite a YSZ sensor, and rich multi-dimensional response information of the YSZ sensor under different alternating excitation signals is obtained. The problem of cross sensitivity existing in a single detection signal is effectively solved, meanwhile, when the concentration-response relation matrix is constructed based on multi-dimensional response information of the YSZ sensor, parameter calibration and calculation can be completed only by preparing at least three kinds of mixed gas with different concentrations, and then the concentration-response relation matrix is obtained; the dependence on massive sample data and the tedious calibration process are greatly reduced; in addition, the concentration detection can be completed without depending on an expensive large-scale analytical instrument or complex sensor array hardware; the method has the advantages that high-precision detection is guaranteed, the detection process is remarkably simplified, and hardware and time cost is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to multi-component gas concentration detection technology, and in particular to a multi-component gas concentration detection method and system based on alternating excitation. BACKGROUND

[0002] In many fields such as environmental monitoring and industrial process control, oxygen O2, water vapor H2O and carbon dioxide CO2 are the three most basic and important process parameters. Real-time and accurate measurement of the concentration of these three gases is crucial for assessing air quality, optimizing combustion efficiency or controlling chemical reaction progress.

[0003] Traditional gas concentration detection technology usually uses a single sensor to detect a single gas component. When multiple gas components need to be detected, a detection platform for each gas component needs to be established separately, and detection needs to be performed separately. The detection process is complex and the detection cost is high.

[0004] Document 1 "Jing Yuanjie. Research on multi-component gas concentration measurement method and development of detector [D]. Harbin, Heilongjiang: Harbin University of Technology, 2021." proposes a multi-component gas concentration detection method based on information fusion technology. This method is based on information fusion technology and builds a two-stage detection model composed of support vector machine (SVM) and BP neural network to realize single gas or multi-component gas detection. Support vector machine is used to identify gas type, and BP neural network is used to predict the concentration of the identified gas, so that the gas components are determined by the two-step method. Although this detection method can detect multiple components of gas concentration at the same time, it uses vector machine and BP neural network at the same time, and its detection accuracy is highly dependent on the training sample. A large number of (121 kinds of gas samples are used in the document) known gas samples must be used for pre-network training and calibration, and two sensors are required for detection. There are problems of high complexity and high cost. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a multi-component gas concentration detection method and system based on alternating excitation, which can realize high-precision detection of multi-component gas concentration, has a simple detection process, and has a low cost.

[0006] The technical solution adopted by the present application to solve the above technical problems is: a multi-component gas concentration detection method based on alternating excitation, comprising the following steps: Step 1, preparing n kinds of mixed gases, each mixed gas being formed by mixing oxygen O2, water vapor H2O and carbon dioxide CO2, and the volume concentrations of oxygen O2, water vapor H2O and carbon dioxide CO2 in any two mixed gases being different, n being an integer greater than or equal to 3; Step 2, n kinds of mixed gas are numbered randomly according to 1-n, the mixed gas numbered k is called the kth mixed gas, k = 1, 2, …, n; in the kth mixed gas, the volume concentration of oxygen O2 is denoted as C k1 , the volume concentration of water vapor H2O is denoted as C k2 , and the volume concentration of carbon dioxide CO2 is denoted as C k3 ; Step 3, each kind of mixed gas is detected by using a YSZ sensor respectively, and the corresponding response signal is obtained, wherein the specific process of detecting the kth mixed gas is as follows: S3.1, place the YSZ sensor in the kth mixed gas; S3.2, apply a first alternating excitation signal E1 capable of driving the YSZ sensor to work to the YSZ sensor, obtain the current signal of the YSZ sensor, convert the current signal into a voltage signal, sample and integrate the voltage, obtain a sampled and integrated voltage signal, take the peak voltage of the last period of the sampled and integrated voltage signal as the response signal, and denote it as R k1 ; the first alternating excitation signal E1 is a periodic alternating voltage signal, the peak voltage of which is greater than or equal to the oxygen pumping voltage of the YSZ sensor and less than the high-temperature steam electrolysis voltage of the YSZ sensor; S3.3, apply a second alternating excitation signal E2 capable of driving the YSZ sensor to work to the YSZ sensor, obtain the current signal of the YSZ sensor, convert the current signal into a voltage signal, sample and integrate the voltage, obtain a sampled and integrated voltage signal, take the peak voltage of the last period of the sampled and integrated voltage signal as the response signal, and denote it as R k2 ; the second alternating excitation signal E2 is a periodic alternating voltage signal, the frequency of which is the same as that of the first alternating excitation signal E1, and the peak voltage of which is greater than or equal to the high-temperature steam electrolysis voltage of the YSZ sensor and less than the high-temperature carbon dioxide electrolysis voltage of the YSZ sensor; S3.4, apply a third alternating excitation signal E3 capable of driving the YSZ sensor to work to the YSZ sensor, obtain the current signal of the YSZ sensor, convert the current signal into a voltage signal, sample and integrate the voltage, obtain a sampled and integrated voltage signal, take the peak voltage of the last period of the sampled and integrated voltage signal as the response signal, and denote it as R k3 ; the third alternating excitation signal E3 is a periodic alternating voltage signal, the frequency of which is the same as that of the second alternating excitation signal E2, and the peak voltage of which is greater than or equal to the high-temperature carbon dioxide electrolysis voltage of the YSZ sensor; Step 4, construct the concentration matrix C matrix and the response matrix R matrix of the n kinds of mixed gas, C matrix and R matrix are respectively shown as formulas (1) and (2): (1) (2) Step 5: Calculate the concentration-response relationship matrix A using equation (3): (3) Where T represents the transpose of the matrix; Step 6: When detecting the concentration of a mixture of oxygen (O2), water vapor (H2O), and carbon dioxide (CO2), the specific detection process is as follows: S6.1 Place the YSZ sensor in the mixed gas; S6.2 Apply a first alternating excitation signal E1 to the YSZ sensor to drive its operation, and obtain the response signal using the same method as in step S3.2, which is denoted as R1. S6.3 Apply a second alternating excitation signal E2 to the YSZ sensor to drive its operation, and obtain the response signal using the same method as in step S3.3, which is denoted as R2; S6.4 Apply a third alternating excitation signal E3 to the YSZ sensor to drive its operation, and obtain the response signal using the same method as in step S3.4, which is denoted as R3. S6.5, Construct the concentration matrix C to be measured new and response matrix R new As shown in equations (4) and (5): (4) (5) Wherein, C1 represents the volume concentration of oxygen (O2) in the mixed gas, C2 represents the volume concentration of water vapor (H2O) in the mixed gas, and C3 represents the volume concentration of carbon dioxide (CO2) in the mixed gas. S6.6. C is calculated using the concentration matrix formula shown in equation (6). new : (6) S6.7, from C new The volume concentrations of oxygen (O2) (C1), water vapor (H2O) (C2), and carbon dioxide (CO2) (C3) were obtained, and the detection was completed.

[0007] Compared with existing technologies, the advantages of this invention are as follows: Based on the specificity of different gas components to different alternating excitation signals, by using different alternating excitation signals to excite the YSZ sensor, rich multidimensional response information of the YSZ sensor under different alternating excitation signals can be obtained, effectively overcoming the cross-sensitivity problem of a single detection signal, thereby enabling high-precision decoupled detection of multi-component gas concentrations; at the same time, when constructing the concentration-response relationship matrix based on the multidimensional response information of the YSZ sensor, only a minimum of three different concentrations of mixed gas are needed to complete parameter calibration and calculation, thereby obtaining the concentration-response relationship matrix, greatly reducing the dependence on massive sample data and the cumbersome calibration process; in addition, concentration detection can be completed without relying on expensive large-scale analytical instruments or complex sensor array hardware; thus, this invention significantly simplifies the detection process and effectively reduces hardware and time costs while ensuring high-precision detection.

[0008] Furthermore, in each cycle, the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 all first rise linearly from 0V to their peak voltage for a period of time, and after maintaining the peak voltage for a period of time, they then linearly decrease to 0V for a period of time. The peak voltage holding time, linear rise time, and linear fall time are all the same for all three.

[0009] Furthermore, in each cycle, the peak voltage of the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 is held for 0.5-1 seconds.

[0010] Furthermore, a multi-component gas concentration detection system based on alternating excitation is provided to implement the aforementioned multi-component gas concentration detection method based on alternating excitation. The system includes a YSZ sensor, an alternating excitation signal conditioning circuit, a signal acquisition circuit, a signal conversion circuit, a sampling integration circuit, and a signal processing circuit. The alternating excitation signal conditioning circuit receives a first voltage signal and a second voltage signal, and superimposes the first and second voltage signals to obtain a periodic alternating voltage signal, which is then output as an alternating excitation signal to the YSZ sensor. This excites the YSZ sensor to either pump oxygen only to generate a current signal, or pump oxygen only and electrolyze water vapor to generate a current signal, or pump oxygen, electrolyze water vapor, and electrolyze carbon dioxide simultaneously to generate a current signal. In each cycle, the first voltage signal is an alternating voltage that first linearly rises from 0V to its peak voltage for a period of time, maintains the peak voltage for a period of time, and then linearly decreases back to 0V for a period of time. The second voltage signal is a DC voltage signal. The acquisition circuit is used to acquire the current signal output by the YSZ sensor and output it to the signal conversion circuit; the signal conversion circuit is used to convert the current signal output by the signal acquisition circuit into a voltage signal and output it to the sampling integration circuit; the sampling integration circuit is used to sample and integrate the voltage signal output by the signal conversion circuit to generate a sampled integrated voltage signal, which is output to the signal processing circuit; the sampled integrated voltage signal is a periodic stepped voltage signal, which is an alternating voltage that rises to its peak voltage and then holds in each cycle, and the subsequent cycle starts to rise from the peak voltage of the previous cycle; the peak voltage of the last cycle of the stepped voltage signal is the response signal; the signal processing circuit is used to output the first voltage signal and the second voltage signal to the alternating excitation signal conditioning circuit, and to control the sampling integration frequency of the sampling integration circuit so that the sampling integration circuit generates a sampled integrated voltage signal output.

[0011] Furthermore, the alternating excitation signal conditioning circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second operational amplifier, and a third operational amplifier; the first operational amplifier, the second operational amplifier, and the third operational amplifier each have a non-inverting input terminal, an inverting input terminal, and an output terminal; one end of the first resistor is connected to the power supply voltage; the other end of the first resistor, one end of the second resistor, and one end of the fourth resistor are connected together, and the other end of the second resistor is grounded; the other end of the fourth resistor, one end of the fifth resistor, and the inverting input terminal of the first operational amplifier are connected together; one end of the third resistor is the first input terminal of the alternating excitation signal conditioning circuit, used to input the first voltage signal; the other end of the third resistor and... The non-inverting input of the first operational amplifier is connected; the other end of the fifth resistor, one end of the seventh resistor, and the output of the first operational amplifier are connected; one end of the sixth resistor is the second input of the alternating excitation signal conditioning circuit, used to input the second voltage signal; the other end of the sixth resistor, the other end of the seventh resistor, and the non-inverting input of the second operational amplifier are connected; one end of the eighth resistor is grounded, and the other end of the eighth resistor, one end of the ninth resistor, and the inverting input of the second operational amplifier are connected; the other end of the ninth resistor, the non-inverting input of the third operational amplifier, and the output of the second operational amplifier are connected; the output of the third operational amplifier and its inverting input are connected, and the connection point is the output of the alternating excitation signal conditioning circuit, used to output the alternating excitation signal.

[0012] Furthermore, the signal acquisition circuit includes a tenth resistor, one end of which is connected to the YSZ sensor and the other end of which is connected to the signal conversion circuit, outputting a current signal to the signal conversion circuit.

[0013] Furthermore, the signal conversion circuit is an IV conversion circuit, which converts the current signal output by the signal acquisition circuit into a voltage signal output.

[0014] Furthermore, the sampling integration circuit includes an eleventh resistor, a first electronic switch, a second electronic switch, a first capacitor, and a fourth operational amplifier. The fourth operational amplifier has a non-inverting input terminal, an inverting input terminal, and an output terminal. The first electronic switch and the second electronic switch each have a first terminal, a second terminal, and a control terminal. When the control terminal is connected to a high level, its first and second terminals are connected; when the control terminal is connected to a low level, its first and second terminals are disconnected. One end of the first electronic switch is the input terminal of the sampling integration circuit, used to receive the voltage signal output by the signal conversion circuit. The other end of the first electronic switch is connected to one end of the eleventh resistor. The other end of the eleventh resistor, one end of the first capacitor, one end of the second electronic switch, and the inverting input terminal of the fourth operational amplifier are connected, and the non-inverting input terminal of the fourth operational amplifier is grounded. The other end of the second electronic switch, the other end of the first capacitor, and the output terminal of the fourth operational amplifier are connected, used to output the sampled and integrated voltage signal to the signal processing circuit.

[0015] Furthermore, the signal processing circuit is implemented using a microcontroller chip and its peripheral circuits. Attached Figure Description

[0016] Figure 1 Here is an example waveform diagram of the first alternating excitation signal; Figure 2 Example waveform diagram of the second alternating excitation signal; Figure 3 Example waveform diagram of the third alternating excitation signal; Figure 4 This is a schematic diagram of the multi-component gas concentration detection system based on alternating excitation according to the present invention; Figure 5 This is a circuit diagram of the alternating excitation signal conditioning circuit of the multi-component gas concentration detection system based on alternating excitation of the present invention; Figure 6 This is a circuit diagram of the signal sampling circuit of the multi-component gas concentration detection system based on alternating excitation of the present invention; Figure 7 This is a circuit diagram of the sampling integration circuit of the multi-component gas concentration detection system based on alternating excitation according to the present invention. Detailed Implementation

[0017] This invention discloses a method for detecting the concentration of multi-component gases based on alternating excitation. The following describes the method for detecting the concentration of multi-component gases based on alternating excitation in further detail with reference to the accompanying drawings and embodiments.

[0018] Example 1: A method for detecting the concentration of a multi-component gas based on alternating excitation, comprising the following steps: Step 1: Prepare n kinds of mixed gases. Each mixed gas is formed by mixing oxygen O2, water vapor H2O and carbon dioxide CO2. The volume concentrations of oxygen O2, water vapor H2O and carbon dioxide CO2 are different in any two mixed gases. n is an integer greater than or equal to 3. Step 2: Randomly number the n mixed gases from 1 to n. The mixed gas numbered k is called the k-th mixed gas, where k = 1, 2, ..., n. The volume concentration of oxygen (O2) in the k-th mixed gas is denoted as C. k1 The volume concentration of water vapor (H2O) is denoted as C. k2 The volume concentration of carbon dioxide (CO2) is denoted as C. k3 ; Step 3: Use a YSZ sensor to detect each type of gas mixture and obtain the corresponding response signal. The specific process for detecting the k-th gas mixture is as follows: S3.1 Place the YSZ sensor in the k-th gas mixture; S3.2. Apply a first alternating excitation signal E1 to the YSZ sensor to drive its operation, acquire the current signal of the YSZ sensor, convert the current signal into a voltage signal, sample and integrate the voltage to obtain the sampled integrated voltage signal, and take the peak voltage of the last cycle of the sampled integrated voltage signal as the response signal, denoted as R. k1 The first alternating excitation signal E1 is a periodic alternating voltage signal, whose peak voltage is greater than or equal to the oxygen pumping voltage of the YSZ sensor and less than the high-temperature steam electrolysis voltage of the YSZ sensor. S3.3. Apply a second alternating excitation signal E2 to the YSZ sensor to drive its operation, acquire the current signal of the YSZ sensor, convert the current signal into a voltage signal, sample and integrate the voltage to obtain the sampled integrated voltage signal, and take the peak voltage of the last cycle of the sampled integrated voltage signal as the response signal, denoted as R. k2 The second alternating excitation signal E2 is a periodic alternating voltage signal with the same frequency as the first alternating excitation signal E1. Its peak voltage is greater than or equal to the high-temperature steam electrolysis voltage of the YSZ sensor and less than the high-temperature carbon dioxide electrolysis voltage of the YSZ sensor. S3.4. Apply a third alternating excitation signal E3 to the YSZ sensor to drive its operation, obtain the current signal of the YSZ sensor, convert the current signal into a voltage signal, sample and integrate the voltage to obtain the sampled integrated voltage signal, and take the peak voltage of the last cycle of the sampled integrated voltage signal as the response signal, denoted as R. k3 The third alternating excitation signal E3 is a periodic alternating voltage signal with the same frequency as the second alternating excitation signal E2, and its peak voltage is greater than or equal to the high-temperature carbon dioxide electrolysis voltage of the YSZ sensor. Step 4: Construct the concentration matrix C of n mixed gases. matrix and response matrix R matrix C matrix and R matrix As shown in equations (1) and (2) respectively: (1) (2) Step 5: Calculate the concentration-response relationship matrix A using equation (3): (3) Where T represents the transpose of a matrix, and ﹒ represents matrix multiplication; Step 6: When detecting the concentration of a mixture of oxygen (O2), water vapor (H2O), and carbon dioxide (CO2), the specific detection process is as follows: S6.1 Place the YSZ sensor in the mixed gas; S6.2 Apply a first alternating excitation signal E1 to the YSZ sensor to drive its operation, and obtain the response signal using the same method as in step S3.2, which is denoted as R1. S6.3 Apply a second alternating excitation signal E2 to the YSZ sensor to drive its operation, and obtain the response signal using the same method as in step S3.3, which is denoted as R2; S6.4 Apply a third alternating excitation signal E3 to the YSZ sensor to drive its operation, and obtain the response signal using the same method as in step S3.4, which is denoted as R3. S6.5, Construct the concentration matrix C to be measured new and response matrix R new As shown in equations (4) and (5): (4) (5) Wherein, C1 represents the volume concentration of oxygen (O2) in the mixed gas, C2 represents the volume concentration of water vapor (H2O) in the mixed gas, and C3 represents the volume concentration of carbon dioxide (CO2) in the mixed gas. S6.6. C is calculated using the concentration matrix formula shown in equation (6). new : (6) S6.7, from C new The volume concentrations of oxygen (O2) (C1), water vapor (H2O) (C2), and carbon dioxide (CO2) (C3) were obtained, and the detection was completed.

[0019] In this embodiment, based on the specificity of different gas components to different alternating excitation signals, the YSZ sensor is excited by different alternating excitation signals. This allows for the acquisition of rich multidimensional response information of the YSZ sensor under different alternating excitation signals, effectively overcoming the cross-sensitivity problem of a single detection signal. This enables high-precision decoupled detection of multi-component gas concentrations. Furthermore, when constructing the concentration-response matrix based on the multidimensional response information of the YSZ sensor, only a minimum of three mixed gases of different concentrations are needed to complete parameter calibration and calculation, thereby obtaining the concentration-response matrix. This significantly reduces the dependence on massive sample data and the cumbersome calibration process. In addition, concentration detection can be completed without relying on expensive large-scale analytical instruments or complex sensor array hardware, simplifying the detection process and effectively reducing hardware and time costs.

[0020] Example 2: This example is basically the same as Example 1, except that: in this example, as Figures 1 to 3 As shown, in each cycle, the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 all first linearly rise from 0V to their peak voltage for a period of time, hold the peak voltage for a period of time, and then linearly decrease to 0V for a period of time. The peak voltage holding time, linear rise time, and linear fall time are all the same for all three signals. In each cycle, the peak voltage holding time for the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 is 0.5-1s. Figures 1 to 3 In the diagram, the horizontal axis represents time, and the vertical axis represents voltage.

[0021] The present invention also discloses a multi-component gas concentration detection system based on alternating excitation that can realize the above-mentioned multi-component gas concentration detection method based on alternating excitation. The following describes the multi-component gas concentration detection system based on alternating excitation of the present invention in further detail with reference to the accompanying drawings and embodiments.

[0022] Example 1: As Figure 4As shown, a multi-component gas concentration detection system based on alternating excitation includes a YSZ sensor, an alternating excitation signal conditioning circuit, a signal acquisition circuit, a signal conversion circuit, a sampling integration circuit, and a signal processing circuit. The alternating excitation signal conditioning circuit receives a first voltage signal AN1 and a second voltage signal AN2, and superimposes the first voltage signal AN1 and the second voltage signal AN2 to obtain a periodic alternating voltage signal, which is output as an alternating excitation signal to the YSZ sensor. This excites the YSZ sensor to either pump oxygen only to generate a current signal, or pump oxygen only and electrolyze water vapor to generate a current signal, or pump oxygen, electrolyze water vapor, and electrolyze carbon dioxide simultaneously to generate a current signal. In each cycle, the first voltage signal AN1 is an alternating voltage that first linearly rises from 0V to its peak voltage for a period of time, maintains the peak voltage for a period of time, and then linearly decreases to 0V for a period of time. The second voltage signal AN2 is a DC voltage signal. The signal acquisition circuit is used to acquire the current signal output by the YSZ sensor and output it to the signal conversion circuit. The signal conversion circuit is used to convert the current signal output by the signal acquisition circuit into a voltage signal and output it to the sampling integration circuit. The sampling integration circuit is used to sample and integrate the voltage signal output by the signal conversion circuit to generate a sampled integrated voltage signal, which is output to the signal processing circuit. The sampled integrated voltage signal is a periodic stepped voltage signal, which is an alternating voltage that rises to its peak voltage and then holds in each cycle, and the next cycle starts to rise from the peak voltage of the previous cycle. The peak voltage of the last cycle of this stepped voltage signal is the response signal. The signal processing circuit is used to output the first voltage signal AN1 and the second voltage signal AN2 to the alternating excitation signal conditioning circuit on the one hand, and to control the sampling integration frequency of the sampling integration circuit on the other hand, so that the sampling integration circuit generates a sampled integrated voltage signal output.

[0023] In this embodiment, the signal processing circuit is implemented using a microcontroller chip and its peripheral circuits.

[0024] Before using the multi-component gas concentration detection system based on alternating excitation in this embodiment, n mixed gases, consisting of oxygen (O2), water vapor (H2O), and carbon dioxide (CO2), are prepared in advance. The concentrations of oxygen (O2), water vapor (H2O), and carbon dioxide (CO2) in each mixed gas are pre-stored in the signal processing circuit. The signal processing circuit controls the alternating excitation signal conditioning circuit to sequentially generate a first alternating excitation signal E1, a second alternating excitation signal E2, and a third alternating excitation signal E3. This causes the YSZ sensor to output current signals corresponding to the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 in each mixed gas environment. Then, the signal is sampled and converted by the signal acquisition circuit, the signal conversion circuit, and the sampling integration circuit to obtain the response signals corresponding to the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 in each mixed gas environment. Based on these data, the signal processing circuit constructs a concentration matrix C of the n mixed gases. matrix and response matrix R matrix C matrix and R matrix This leads to the concentration-response relationship matrix A. In this embodiment, when the multi-component gas concentration detection system based on alternating excitation detects a mixed gas formed by oxygen (O2), water vapor (H2O), and carbon dioxide (CO2), the response signals corresponding to the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 under this mixed gas are obtained using the same method as before. Then, the system employs... The concentrations of each component were calculated.

[0025] Example 2: This example is basically the same as Example 1, except that: in this example, as Figure 5As shown, the alternating excitation signal conditioning circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a first operational amplifier A1, a second operational amplifier A2, and a third operational amplifier A3. Each of the first operational amplifier A1, second operational amplifier A2, and third operational amplifier A3 has a non-inverting input terminal, an inverting input terminal, and an output terminal. One end of the first resistor R1 is connected to the power supply voltage VCC. The other end of the first resistor R1, one end of the second resistor R2, and one end of the fourth resistor R4 are connected together, and the other end of the second resistor R2 is grounded. The other end of the fourth resistor R4, one end of the fifth resistor R5, and the inverting input terminal of the first operational amplifier A1 are connected together. One end of the third resistor R3 is the first input terminal of the alternating excitation signal conditioning circuit, used to input the first voltage signal A. N1; the other end of the third resistor R3 is connected to the non-inverting input of the first operational amplifier A1; the other end of the fifth resistor R5 and one end of the seventh resistor R7 are connected to the output of the first operational amplifier A1; one end of the sixth resistor R6 is the second input of the alternating excitation signal conditioning circuit, used to input the second voltage signal AN2; the other end of the sixth resistor R6 and the other end of the seventh resistor R7 are connected to the non-inverting input of the second operational amplifier A2; one end of the eighth resistor R8 is grounded, and the other end of the eighth resistor R8 and one end of the ninth resistor R9 are connected to the inverting input of the second operational amplifier A2; the other end of the ninth resistor R9 is connected to the non-inverting input of the third operational amplifier A3 and the output of the second operational amplifier A2; the output of the third operational amplifier A3 is connected to its inverting input, and its connection point is the output of the alternating excitation signal conditioning circuit, used to output the alternating excitation signal.

[0026] In this alternating excitation signal conditioning circuit, the first operational amplifier A1, the third resistor R3, the fourth resistor R4, and the fifth resistor R5 constitute the first adder circuit; the seventh resistor R7, the sixth resistor R6, the eighth resistor R8, the ninth resistor R9, and the second operational amplifier A2 constitute the second adder circuit; the first resistor R1 and the second resistor R2 constitute a voltage divider circuit; and the third operational amplifier A3 constitutes a voltage follower circuit. When the first voltage signal AN1 is input to the first input terminal of the alternating excitation signal conditioning circuit, the second voltage signal AN2 is input to the second input terminal, and one end of the first resistor R1 is connected to the power supply voltage VCC (DC voltage), the voltage divider circuit divides the power supply voltage VCC. Then, the divided DC voltage V1 is output to the first adder circuit; the first adder circuit superimposes the divided DC voltage V1 with the first voltage signal AN1 it is connected to, and obtains an alternating voltage signal V2 with the offset of the divided DC voltage V1, and outputs it to the second adder circuit; the second adder circuit superimposes the alternating voltage signal V2 with the offset of the divided DC voltage V1 with the second voltage signal AN2, and obtains an alternating voltage signal V3 with the offset of the second voltage signal AN2, and outputs it to the voltage follower circuit. After the voltage follower circuit enhances the driving capability of the alternating voltage signal V3, it forms an alternating excitation signal output to excite the YSZ sensor to work.

[0027] Example 3: This example is basically the same as Example 2, except that: in this example, as Figure 6 As shown, the signal acquisition circuit includes a tenth resistor R10. One end of the tenth resistor R10 is connected to the YSZ sensor, and the other end is connected to the signal conversion circuit, outputting a current signal to the signal conversion circuit. The signal conversion circuit is an IV conversion circuit, which converts the current signal output by the signal acquisition circuit into a voltage signal output.

[0028] Example 4: This example is basically the same as Example 3, except that: in this example, as Figure 7As shown, the sampling integration circuit includes an eleventh resistor R11, a first electronic switch K1, a second electronic switch K2, a first capacitor C1, and a fourth operational amplifier A4. The fourth operational amplifier A4 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The first electronic switch K1 and the second electronic switch K2 each have a first terminal, a second terminal, and a control terminal. When the control terminal is connected to a high level, its first and second terminals are connected; when the control terminal is connected to a low level, its first and second terminals are disconnected. One end of the first electronic switch K1 is the input terminal of the sampling integration circuit, used to input the voltage signal output by the signal conversion circuit. The other end of the first electronic switch K1 is connected to one end of the eleventh resistor R11. The other end of the eleventh resistor R11, one end of the first capacitor C1, one end of the second electronic switch K2, and the inverting input terminal of the fourth operational amplifier A4 are connected, and the non-inverting input terminal of the fourth operational amplifier A4 is grounded. The other end of the second electronic switch K2, the other end of the first capacitor C1, and the output terminal of the fourth operational amplifier A4 are connected, used to output the sampled and integrated voltage signal to the signal processing circuit.

[0029] The sampling and integration circuit operates periodically under the control of the signal processing circuit. First, the signal processing circuit outputs a low level to open the first electronic switch K1 and a high level to close the second electronic switch K2, resetting the fourth operational amplifier A4, which then outputs a low level. Subsequently, the signal processing circuit outputs a low level to open the second electronic switch K2, initiating the sampling and integration phase. When the alternating excitation signal output from the alternating excitation signal conditioning circuit reaches its peak voltage, the signal processing circuit outputs a high level to close the first electronic switch K1. At this time, the fourth operational amplifier A4 acts as an integrator, performing sampling and integration on the DC voltage signal output from the signal conversion circuit. The output voltage of the fourth operational amplifier A4 rises linearly. During the rising or falling edge of the alternating excitation signal output from the alternating excitation signal conditioning circuit, the signal processing circuit outputs a low level to open the first electronic switch K1, pausing the integration process. The output of the fourth operational amplifier A4 remains at the sampled value from the previous moment, achieving a voltage holding function. The signal processing circuit controls the sampling and integration circuit in this cyclical manner to achieve the sampling and integration operation.

[0030] In summary, this invention leverages the specificity of different gas components to different alternating excitation signals. By exciting the YSZ sensor with different alternating excitation signals, it can acquire rich, multi-dimensional response information of the YSZ sensor under various alternating excitation signals, thereby establishing a concentration-response relationship matrix. Based on this matrix, the concentration of each component can be obtained. This invention effectively overcomes the cross-sensitivity problem inherent in single detection signals, achieving high-precision decoupled detection of multi-component gas concentrations. It also significantly reduces the reliance on massive sample data and cumbersome calibration procedures. Concentration detection can be completed without relying on expensive large-scale analytical instruments or complex sensor array hardware, simplifying the detection process and effectively reducing hardware and time costs, thus possessing broad application prospects.

Claims

1. A method for detecting the concentration of a multi-component gas based on alternating excitation, characterized in that, Includes the following steps: Step 1: Prepare n kinds of mixed gases. Each mixed gas is formed by mixing oxygen O2, water vapor H2O and carbon dioxide CO2. The volume concentrations of oxygen O2, water vapor H2O and carbon dioxide CO2 are different in any two mixed gases. n is an integer greater than or equal to 3. Step 2: Randomly number the n mixed gases from 1 to n, and denot the volume concentration of oxygen (O2) in the k-th mixed gas as C. k1 The volume concentration of water vapor (H2O) is denoted as C. k2 The volume concentration of carbon dioxide (CO2) is denoted as C. k3 k = 1, 2, ..., n; Step 3: Place the YSZ sensor in each gas mixture and sequentially excite it with the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3. Obtain the current signal output by the YSZ sensor, and then convert the current signal to obtain the corresponding response signal. The response signals corresponding to the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 for the k-th gas mixture are denoted as R. k1 R k2 and R k3 ; Step 4: Calculate the concentration-response relationship matrix A using equation (1): （1） Where T denotes the transpose of the matrix; C matrix and R matrix Let the concentration matrix and response matrix of the n mixed gases be represented, as shown in equations (2) and (3), respectively: （2） （3） Step 5: When detecting the concentration of a mixture of oxygen (O2), water vapor (H2O), and carbon dioxide (CO2), the specific detection process is as follows: S5.1 Using the same method as in step 3, obtain the response signals R1, R2 and R3 corresponding to the first alternating excitation signal E1, the second alternating excitation signal E2 and the third alternating excitation signal E3 in the mixed gas. S5.2 The concentration matrix C of the mixed gas is calculated using equation (4). new : （4） in, ; S5.3, Calculated C new for Wherein, C1 is the volume concentration of oxygen (O2) in the mixed gas, C2 is the volume concentration of water vapor (H2O) in the mixed gas, and C3 is the volume concentration of carbon dioxide (CO2) in the mixed gas.

2. The method for detecting the concentration of a multi-component gas based on alternating excitation according to claim 1, characterized in that, The specific method for converting the current signal to obtain the response signal in step 3 is as follows: first, the current signal is converted into a voltage signal, then the voltage signal is sampled and integrated to obtain a sampled and integrated voltage signal, and the peak voltage of the last cycle of the sampled and integrated voltage signal is used as the response signal.

3. The method for detecting the concentration of a multi-component gas based on alternating excitation according to claim 2, characterized in that, The first alternating excitation signal E1 is a periodic alternating voltage signal with a peak voltage greater than or equal to the oxygen pumping voltage of the YSZ sensor and less than the high-temperature steam electrolysis voltage of the YSZ sensor. The second alternating excitation signal E2 is a periodic alternating voltage signal with the same frequency as the first alternating excitation signal E1, but its peak voltage is greater than or equal to the high-temperature steam electrolysis voltage of the YSZ sensor and less than the high-temperature carbon dioxide electrolysis voltage of the YSZ sensor. The third alternating excitation signal E3 is a periodic alternating voltage signal with the same frequency as the second alternating excitation signal E2, but its peak voltage is greater than or equal to the high-temperature carbon dioxide electrolysis voltage of the YSZ sensor. In each cycle, the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 all first rise linearly from 0V to their peak voltage for a period of time, hold the peak voltage for a period of time, and then linearly decrease to 0V for a period of time. The peak voltage holding time, linear rise time, and linear fall time are all the same for all three signals.

4. The method for detecting the concentration of a multi-component gas based on alternating excitation according to claim 3, characterized in that, In each cycle, the peak voltage of the first alternating excitation signal E1, the second alternating excitation signal E2, and the third alternating excitation signal E3 is held for 0.5-1 seconds.

5. A multi-component gas concentration detection system based on alternating excitation, used to implement the multi-component gas concentration detection method based on alternating excitation as described in any one of claims 1 to 4, characterized in that, It includes a YSZ sensor, an alternating excitation signal conditioning circuit, a signal acquisition circuit, a signal conversion circuit, a sampling integration circuit, and a signal processing circuit. The signal acquisition circuit is used to acquire the current signal of the YSZ sensor and output it to the signal conversion circuit. The signal conversion circuit is used to convert the current signal into a voltage signal and output it to the sampling integration circuit. The sampling integration circuit is used to sample and integrate the voltage signal to generate a sampled integrated voltage signal, which is then output to the signal processing circuit. The signal processing circuit is used to provide alternating excitation signals for the YSZ sensor on the one hand, and to control the sampling and integration frequency of the sampling and integration circuit on the other hand, so that the sampling and integration circuit can generate a sampling and integration voltage signal output.

6. The multi-component gas concentration detection system based on alternating excitation according to claim 5, characterized in that, The alternating excitation signal conditioning circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second operational amplifier, and a third operational amplifier. Each of the first, second, and third operational amplifiers has a non-inverting input terminal, an inverting input terminal, and an output terminal. One end of the first resistor is connected to the power supply voltage. The other end of the first resistor, one end of the second resistor, and one end of the fourth resistor are connected together, and the other end of the second resistor is grounded. The other end of the fourth resistor and one end of the fifth resistor are connected to the inverting input terminal of the first operational amplifier. One end of the third resistor is the first input terminal of the alternating excitation signal conditioning circuit. The other end of the third resistor is connected to the non-inverting input terminal of the first operational amplifier. The other end of the fifth resistor and one end of the seventh resistor are connected to the output terminal of the first operational amplifier. One end of the sixth resistor is the second input terminal of the alternating excitation signal conditioning circuit. The other ends of the sixth resistor, the other end of the seventh resistor, and the non-inverting input terminal of the second operational amplifier are connected together. One end of the eighth resistor is grounded, and the other end of the eighth resistor, one end of the ninth resistor, and the inverting input of the second operational amplifier are connected. The other end of the ninth resistor, the non-inverting input of the third operational amplifier, and the output of the second operational amplifier are connected. The output of the third operational amplifier and its inverting input are connected, and the connection point is the output of the alternating excitation signal conditioning circuit, which is used to output the alternating excitation signal.

7. The multi-component gas concentration detection system based on alternating excitation according to claim 5, characterized in that, The signal acquisition circuit includes a tenth resistor, one end of which is connected to the YSZ sensor and the other end is connected to the signal conversion circuit, outputting a current signal to the signal conversion circuit.

8. The multi-component gas concentration detection system based on alternating excitation according to claim 5, characterized in that, The signal conversion circuit is an IV conversion circuit, which converts the current signal output by the signal acquisition circuit into a voltage signal output.

9. The multi-component gas concentration detection system based on alternating excitation according to claim 5, characterized in that, The sampling and integration circuit includes an eleventh resistor, a first electronic switch, a second electronic switch, a first capacitor, and a fourth operational amplifier. The fourth operational amplifier has a non-inverting input, an inverting input, and an output. Both the first and second electronic switches have a first terminal, a second terminal, and a control terminal. When the control terminal is connected to a high level, its first and second terminals are connected; when the control terminal is connected to a low level, its first and second terminals are disconnected. One end of the first electronic switch is the input terminal of the sampling and integration circuit, used to receive the voltage signal output by the signal conversion circuit. The other end of the first electronic switch is connected to one end of the eleventh resistor. The other end of the eleventh resistor, one end of the first capacitor, one end of the second electronic switch, and the inverting input terminal of the fourth operational amplifier are connected, while the non-inverting input terminal of the fourth operational amplifier is grounded. The other end of the second electronic switch, the other end of the first capacitor, and the output terminal of the fourth operational amplifier are connected, used to output the sampled and integrated voltage signal to the signal processing circuit.

10. The multi-component gas concentration detection system based on alternating excitation according to claim 5, characterized in that, The signal processing circuit is implemented using a microcontroller chip and its peripheral circuits.

Images