A Gas Detection Method Based on Thermal Conductivity Sensor

Abstract

This application provides a gas detection method based on a thermal conductivity sensor. The method includes: outputting a first heating current to the thermal conductivity sensor; monitoring and converting the resistance value of a thermistor into a target voltage signal; outputting the target voltage signal; detecting the gas to be detected in the surrounding ambient gas by thermal conduction under the excitation of the first heating current; receiving the target voltage signal; determining the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during the thermal conduction process based on the target voltage signal; and obtaining the mixed thermal conductivity of the surrounding ambient gas based on the target temperature difference, ambient temperature, current value, and the initial resistance value of the thermistor; and determining the target concentration of the gas to be detected based on the mixed thermal conductivity. This application can reduce the computational complexity of gas detection and improve detection accuracy and stability.

Description

Technical Field

[0001] This application relates to the field of materials testing and analysis technology, and in particular to a gas detection method based on a thermal conductivity sensor. Background Technology

[0002] Thermal conductivity sensors detect gases based on the differences in thermal conductivity among different gas components. Hydrogen, with the highest known thermal conductivity (0.183 W / m·K at room temperature), is 7-10 times more conductive than nitrogen (0.026 W / m·K), oxygen (0.027 W / m·K), and air (0.026 W / m·K), making it an ideal target for thermal conductivity detection. The principle behind hydrogen detection using thermal conductivity sensors is based on the fact that hydrogen has the highest thermal conductivity among all known gas components. By using a chip device to measure the thermal conductivity of the mixed gases in the surrounding environment, the concentration of hydrogen can be calculated.

[0003] Existing thermal conductivity sensors employ algorithms such as constant temperature, constant temperature difference, constant voltage, and constant power. However, existing driving methods have the following limitations: constant temperature control requires a PID feedback loop (Proportional-Integral-Derivative Feedback Loop), which is complex and has limited response speed; constant power drive is prone to temperature fluctuations in the sensitive element, resulting in thermal inertia; constant temperature difference mode is highly dependent on ambient temperature and requires additional temperature compensation; existing solutions generally suffer from high power consumption and long response time. Summary of the Invention

[0004] This application provides a gas detection method based on a thermal conductivity sensor. By using a constant current or constant current pulse drive, combined with a MEMS (Micro-Electro-Mechanical Systems) sensor chip and digital signal processing, the system significantly reduces the processing complexity while ensuring detection accuracy. Compared with traditional methods, it has significant improvements in sensor response speed, power consumption, and temperature stability.

[0005] In a first aspect, this application provides a gas detection method based on a thermal conductivity sensor, applied to a gas detection system. The system includes a constant current driving circuit, a thermal conductivity sensor, and a control module. The thermal conductivity sensor includes a thermistor. The current output terminal of the constant current driving circuit is connected to the current input terminal of the thermal conductivity sensor. The voltage acquisition terminal of the constant current driving circuit is connected in parallel with both ends of the thermistor. The control module is connected to the constant current driving circuit.

[0006] The constant current driving circuit is used to output a first heating current to the thermal conductivity sensor, the first heating current including a constant current; and to monitor and convert the resistance value of the thermistor into a target voltage signal; and to output the target voltage signal.

[0007] The thermal conductivity sensor is used to detect the gas to be detected in the surrounding environment gas by means of thermal conduction under the excitation of the first heating current.

[0008] The control module is configured to receive the target voltage signal; and determine, based on the target voltage signal, the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during the heat conduction process; and obtain the mixed thermal conductivity of the surrounding ambient gas based on the target temperature difference, the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor; and determine the target concentration of the gas to be detected in the surrounding ambient gas based on the mixed thermal conductivity.

[0009] Secondly, embodiments of this application provide a gas detection system, including a constant current driving circuit, a thermal conductivity sensor, and a control module. The thermal conductivity sensor includes a thermistor. The current output terminal of the constant current driving circuit is connected to the current input terminal of the thermal conductivity sensor. The voltage acquisition terminal of the constant current driving circuit is connected in parallel with both ends of the thermistor. The control module is connected to the constant current driving circuit.

[0010] The system is used to perform the steps of implementing the method described in the first aspect above.

[0011] Thirdly, embodiments of this application provide an electronic device, including a processor, a memory, a communication interface, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the programs include instructions for performing steps in any method of the first aspect of this application.

[0012] Fourthly, embodiments of this application provide a computer-readable storage medium having a computer program / instructions stored thereon, which is executed by a processor to implement the steps of the method described in the first aspect above.

[0013] Fifthly, embodiments of this application provide a computer program product, wherein the computer program product includes a non-transitory computer-readable storage medium storing a computer program, the computer program being operable to cause a computer to perform some or all of the steps described in the first aspect of embodiments of this application.

[0014] As can be seen, in this embodiment, the constant current driving circuit is used to output a first heating current to the thermal conductivity sensor, the first heating current including a constant current; and to monitor and convert the resistance value of the thermistor into a target voltage signal; and to output the target voltage signal; the thermal conductivity sensor is used to detect the gas to be detected in the surrounding ambient gas by means of thermal conduction under the excitation of the first heating current; the control module is used to receive the target voltage signal; and to determine the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during the thermal conduction process according to the target voltage signal; and to obtain the mixed thermal conductivity of the surrounding ambient gas according to the target temperature difference, ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor; and to determine the target concentration of the gas to be detected in the surrounding ambient gas according to the mixed thermal conductivity. Thus, compared with the constant temperature, constant temperature difference, constant voltage, and constant power driving methods of existing thermal conductivity sensors, this application, through constant current or constant current pulse driving method, combined with MEMS sensor chip and digital signal processing, significantly reduces the system processing complexity while ensuring detection accuracy, and significantly improves the sensor response speed, power consumption, and temperature stability compared with traditional methods. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the system architecture of a gas detection system provided in an embodiment of this application;

[0017] Figure 2 This is a structural block diagram of an electronic device provided in an embodiment of this application;

[0018] Figure 3 This is a schematic flowchart of a gas detection method based on a thermal conductivity sensor provided in an embodiment of this application;

[0019] Figure 4 This is a schematic diagram of a process for establishing the correlation between the mixed thermal conductivity and temperature difference, provided in an embodiment of this application.

[0020] Figure 5 This is a schematic flowchart of another gas detection method based on a thermal conductivity sensor provided in an embodiment of this application;

[0021] Figure 6 This is a partial circuit structure diagram of a constant current drive circuit provided in an embodiment of this application;

[0022] Figure 7 This is a schematic diagram of the functional modules of a gas detection system provided in an embodiment of this application. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0024] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] In the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone; A and B exist simultaneously; B exists alone. Among them, A and B can be singular or plural.

[0027] In this embodiment, the symbol " / " can indicate that the preceding and following objects are in an "or" relationship. Alternatively, the symbol " / " can also represent a division sign, i.e., performing a division operation. For example, A / B can mean A divided by B.

[0028] In the embodiments of this application, "at least one item" or its similar expression refers to any combination of these items, including any combination of a single item or a plurality of items. "One or more" means one or more, while "multiple" means two or more. For example, "at least one item" of a, b, or c can represent the following seven cases: a, b, c; a and b; a and c; b and c; a, b, and c. Each of a, b, and c can be an element or a set containing one or more elements.

[0029] In the embodiments of this application, "equal to" can be used with "greater than" and is applicable to technical solutions used when "greater than" is used; it can also be used with "less than" and is applicable to technical solutions used when "less than" is used. When "equal to" is used with "greater than", it is not used with "less than"; when "equal to" is used with "less than", it is not used with "greater than".

[0030] Existing thermal conductivity sensors employ algorithms such as constant temperature, constant temperature difference, constant voltage, and constant power. However, existing driving methods have the following limitations: constant temperature control requires a PID feedback loop, resulting in complex circuitry and limited response speed; constant power drive is prone to temperature fluctuations in the sensitive element, generating thermal inertia; constant temperature difference mode is highly dependent on ambient temperature, requiring additional temperature compensation; and existing solutions generally suffer from high power consumption and long response times.

[0031] To address the aforementioned problems, this application provides a gas detection method based on a thermal conductivity sensor. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0032] Please see Figure 1 , Figure 1 This is a schematic diagram of the system architecture of a gas detection system provided in an embodiment of this application, such as... Figure 1 As shown, the gas detection system 100 includes a constant current drive circuit 110, a thermal conductivity sensor 120, an analog-to-digital conversion module 130, and a control module 140. The thermal conductivity sensor 120 includes a heater 121, a thermistor 122, and a temperature-sensitive resistor 123.

[0033] The constant current drive circuit 110 has its current output terminal directly connected to the current input terminal of the thermal conductivity sensor 120, outputting a first heating current to the thermal conductivity sensor 120. Simultaneously, it monitors the resistance changes of the thermistor 122 and the temperature-sensitive resistor 123, converting them into a target voltage signal and a temperature-compensated voltage signal, respectively. The voltage signal output terminal of the constant current drive circuit 110 is connected to the analog-to-digital converter module 130, transmitting the generated target voltage signal and temperature-compensated voltage signal to the analog-to-digital converter module 130. The analog-to-digital converter module 130 is connected to the control module 140, outputting the converted digital signal to the control module 140.

[0034] Specifically, the constant current drive circuit 110 is used to output a stable first heating current (constant current or periodic square wave pulse) to provide constant energy to the heater 121 of the thermal conductivity sensor 120 or the thermistor 122 which also has a heating function; at the same time, it monitors the resistance changes of the thermistor 122 and the temperature-sensitive resistor 123, converts the resistance changes into an acquireable voltage signal, and performs preliminary conditioning such as amplitude adjustment and filtering on the signal to adapt it to the processing requirements of subsequent modules.

[0035] Specifically, the thermal conductivity sensor 120 contains an independent heater 121 and a thermistor 122. The first heating current output by the constant current drive circuit 110 directly acts on the heater 121, causing it to heat up and form a basic temperature difference with the environment. Although the thermistor 122 is not directly connected to the first heating current, it is integrated near the heater 121 and shares the local thermal field. It can indirectly reflect the heat dissipation state of the heater 121 through the change of its resistance with temperature. For example, when the thermal conductivity of the gas changes (such as a change in the concentration of the gas to be detected), the heat dissipation rate of the heater 121 changes, causing its temperature to fluctuate. This temperature fluctuation is transferred to the nearby thermistor 122 through heat conduction, causing its temperature and resistance to change synchronously. However, although the thermistor 123 is also not heated, it is kept at a distance from the heater 121 or is isolated by structure, and only senses the actual temperature of the surrounding environment.

[0036] Specifically, the analog-to-digital conversion module 130 is used to receive the voltage signal output by the constant current drive circuit 110 and convert it into a digital signal that the control module 140 can process through sampling, quantization, encoding and other operations, so as to ensure the signal anti-interference and synchronization, and ensure that the control module 140 uses the signal data of the same detection cycle for calculation, avoiding errors caused by timing deviation.

[0037] Specifically, the control module 140 receives the digital signal output by the analog-to-digital converter 130, derives the target resistance value and target temperature difference of the thermistor 122, calculates the thermal conductivity of the mixed gas by combining known parameters (constant current value, initial resistance value, etc.), and finally determines the target concentration of the gas to be detected; and it is also used to analyze the real ambient temperature, execute a temperature compensation algorithm, correct the influence of ambient temperature drift on the resistance value of the thermistor 122 and the thermal conductivity of the gas, and output an accurate compensated concentration result. Ambient temperature drift refers to the unexpected and unavoidable changes in electronic devices, systems, or physical quantities caused by changes in ambient temperature.

[0038] As can be seen, in this embodiment, the constant current drive circuit 110 supplies power to the heater 121 in the thermal conductivity sensor 120 and converts the resistance changes of the thermistor 122 and the temperature-sensitive resistor 123 into a conditioned voltage signal. The analog-to-digital conversion module 130 digitizes the voltage signal to ensure anti-interference and synchronization. The control module 140 derives the temperature difference based on the digital signal, calculates the thermal conductivity and gas concentration of the mixed gas, and performs temperature compensation, ultimately achieving accurate and stable detection of gas concentration.

[0039] The following is combined with Figure 2 The electronic devices in the embodiments of this application will be described. Figure 2 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application, such as... Figure 2 As shown, the electronic device 200 includes one or more processors 210, a memory 220, a communication interface 230, and one or more programs 221. The processor 210 is communicatively connected to the memory 220 and the communication interface 230 via an internal communication bus. The processor 210 can be a central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logic blocks, units, and circuits described in conjunction with the disclosure of this application. The processor can also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc. The communication unit can be a communication interface, a transceiver, a transceiver circuit, etc., and the storage unit can be a memory.

[0040] The memory 220 can be volatile memory or non-volatile memory, or it can include both. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDRSDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0041] The one or more programs 221 are stored in the memory 220 and configured to be executed by the processor 210. The one or more programs 221 include instructions for performing any step in an embodiment of a gas detection method based on a thermal conductivity sensor. It is understood that the electronic device 200 may include more or fewer structural elements than shown in the block diagram above, such as a power module, physical buttons, a Wi-Fi module, a speaker, a Bluetooth module, a sensor, a display module, etc., without limitation herein. It is understood that the electronic device may be equipped with, for example... Figure 1 The system architecture of a gas detection system is described above.

[0042] After understanding the software and hardware architecture of this application, the following will be combined with... Figure 3 This application describes a gas detection method based on a thermal conductivity sensor. Figure 3 This is a flowchart illustrating the steps of a gas detection method based on a thermal conductivity sensor, provided in an embodiment of this application. Applied to a gas detection system 100, the method specifically includes the following steps:

[0043] Step S310: Output a first heating current to the thermal conductivity sensor, the first heating current including a constant current; monitor and convert the resistance value of the thermistor into a target voltage signal; and output the target voltage signal.

[0044] Specifically, the thermal conductivity sensor includes a set of low-power heaters. A constant current drive circuit outputs a constant current to the heaters, causing them to heat up and establish a basic temperature difference with the environment. The thermistor is usually integrated near the heaters. By changing its resistance with temperature, it indirectly reflects the heat dissipation of the heaters. That is, when the hydrogen concentration changes, causing a change in the thermal conductivity of the mixed gas, the heat dissipation rate of the heater changes, the thermal equilibrium of the chip is broken, and the temperature and resistance of the thermistor change accordingly, thus converting the gas characteristics into an electrical signal.

[0045] Understandably, converting the resistance value of a thermistor into a target voltage signal requires hardware circuit design, which relies on Ohm's law, voltage divider principles, and constant current drive characteristics. Specifically, the voltage acquisition terminal of the constant current drive circuit is connected in parallel with the thermistor, directly acquiring the actual voltage drop across the resistor, providing the physical basis for the conversion. Under constant current excitation, the change in the thermistor's resistance due to the change in the thermal conductivity of the gas (caused by a change in the concentration of the gas to be detected) is directly converted into a synchronous change in the voltage across the thermistor, achieving the initial correlation between "resistance change and voltage change".

[0046] Furthermore, the constant current drive circuit conditions the original voltage by adjusting the signal amplitude through a voltage divider resistor network to match the range of subsequent modules (such as analog-to-digital converters), filtering out high-frequency interference through an RC low-pass filter circuit, and correcting resistor nonlinearity errors through an operational amplifier linearization circuit, thus processing it into a target voltage signal that meets the acquisition requirements. Finally, the conditioned target voltage signal is transmitted to the next stage through the signal output terminal of the constant current drive circuit. With its characteristics of being "acquisitionable, low-noise, and linearized," it provides a reliable electrical signal for the control module to analyze the thermistor resistance value changes and deduce the gas concentration.

[0047] It should be noted that this application is not limited to the voltage signal acquisition method of "constant current drive circuit voltage acquisition terminal connected in parallel with the thermistor terminals", but can also be achieved through other equivalent circuit structures, including but not limited to: series voltage divider acquisition, differential amplification acquisition, indirect current sampling derivation and other methods.

[0048] As can be seen, in this embodiment, a constant current is output by a constant current drive circuit to heat the thermistor and form the temperature difference required for detection. Based on the hardware design, the resistance value of the thermistor, which changes with the thermal conductivity of the gas, is converted into a voltage signal. After amplitude adjustment, noise filtering, and linearization compensation, a low-noise, suitable target voltage signal is obtained and transmitted to the subsequent modules. At the same time, it supports multiple equivalent acquisition methods such as series voltage division and differential amplification, which not only ensures the accuracy and reliability of signal conversion and provides high-quality data for subsequent gas concentration derivation, but also improves the flexibility of circuit design.

[0049] Step S320: Under the excitation of the first heating current, the gas to be detected in the surrounding ambient gas is detected by means of heat conduction.

[0050] In this process, under the excitation of the first heating current, the constant current drive circuit outputs a constant current to the low-power heater built into the thermal conductivity sensor. The heater converts electrical energy into heat energy through the Joule effect, raising the temperature and forming a stable local thermal field. This establishes a basic temperature difference with the surrounding gas, which is the energy basis for thermal conduction detection. At this time, the heat generated by the heater is dissipated to the surrounding gas mainly through thermal conduction (supplemented by thermal radiation and thermal convection). When the concentration of the gas to be detected in the environment (such as hydrogen) changes, the thermal conductivity of the mixed gas changes accordingly: when the concentration increases, the thermal conductivity increases, the rate of heat conduction from the heater to the gas accelerates, and the heat dissipation is more significant; when the concentration decreases, the thermal conductivity decreases, the rate of heat conduction slows down, and more heat accumulates.

[0051] Furthermore, since the thermistor is integrated near the heater, they share the same thermal field. Heat from the heater is transferred to the thermistor via thermal conduction, directly linking its temperature to the heater's heat dissipation state. That is, when the heater experiences a thermal equilibrium shift due to changes in the gas's thermal conductivity, the thermistor's temperature changes synchronously, leading to a change in its resistance. For example, the resistance of an NTC thermistor decreases as the temperature rises. The NTC thermistor (Negative Temperature Coefficient Thermistor) exhibits a significant negative correlation between its resistance and temperature.

[0052] Step S330: Receive target voltage signal; and determine the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during the heat conduction process based on the target voltage signal; and obtain the mixed thermal conductivity of the surrounding gas based on the target temperature difference, ambient temperature, current value of the constant current, and initial resistance value of the thermistor; and determine the target concentration of the gas to be detected in the surrounding gas based on the mixed thermal conductivity.

[0053] In one possible embodiment, determining the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during heat conduction based on the target voltage signal includes: determining the target resistance value of the thermistor based on the target voltage signal and a third preset relationship, wherein the third preset relationship characterizes the positive correlation between the resistance value of the thermistor and the output voltage of the constant current drive circuit; and determining the target temperature difference based on the target resistance value of the thermistor and a fourth preset relationship, wherein the fourth preset relationship characterizes the positive correlation between the temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature and the resistance value of the thermistor.

[0054] The target voltage signal is the output of the thermistor voltage conditioned by the constant current drive circuit. It has a "third preset relationship" with the thermistor's resistance value, which is a "positive correlation". Under constant current drive, the voltage and resistance are strictly proportional (I is constant). The control module uses this preset relationship (which can be expressed as a calibration curve or formula) to directly deduce the real-time resistance value of the thermistor from the target voltage signal, thus completing the conversion of the voltage signal into a resistance value.

[0055] The core characteristic of a thermistor is that its resistance changes with temperature. Therefore, its resistance value is clearly related to the temperature difference between the heating temperature and the ambient temperature, which is the "fourth preset relationship." This relationship is also a "positive correlation." The control module calls this preset relationship, such as a fitting formula based on calibration data, to convert the target resistance value into the actual temperature difference between the heater and the environment, completing the conversion from resistance value to temperature difference, so that the electrical signal ultimately corresponds to a thermophysical quantity.

[0056] Furthermore, after obtaining the target temperature difference, the control module further combines the ambient temperature, constant current value, and initial resistance value of the thermistor to establish a correlation with the thermal conductivity of the mixed gas. Finally, based on the "correspondence between the thermal conductivity of the mixture and the concentration of the gas to be detected", such as the higher the hydrogen concentration, the greater the thermal conductivity of the mixture, the target concentration is calculated.

[0057] In one possible embodiment, obtaining the mixed thermal conductivity of the ambient gas based on the target temperature difference, ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor includes: establishing a first correlation between the mixed thermal conductivity and the target temperature difference based on the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor, wherein the first correlation indicates a negative correlation between the mixed thermal conductivity and the target temperature difference; and determining the mixed thermal conductivity of the ambient gas based on the target temperature difference and the first correlation.

[0058] The thermal conductivity of the mixed gas is a key physical quantity reflecting the gas composition, but it cannot be directly measured and must be obtained indirectly through the derived thermophysical quantity of "target temperature difference." Meanwhile, "ambient temperature, constant current value, and initial resistance value of the thermistor" are known parameters that are preset or calibrated by the system. Therefore, based on these parameters, a primary correlation is established between "target temperature difference" and "mixture thermal conductivity," allowing the originally isolated temperature difference data to correspond to specific gas thermal conductivity characteristics.

[0059] Specifically, ambient temperature is used to calibrate the thermal reference under different environments to avoid temperature drift caused by temperature difference reference deviation; constant current value is the core determining factor of heater heat generation power. Fixing this parameter can ensure stable energy input at the "heat generation end" so that temperature difference change is determined only by the "heat dissipation end" (i.e., gas thermal conductivity); the initial resistance value of the thermistor is the basic parameter for calculating heat generation power and calibrating the relationship between resistance and temperature, and is used to eliminate the influence of the initial error of the thermistor itself on the derivation.

[0060] Furthermore, the first correlation has already predefined how the temperature difference changes with the thermal conductivity. At this point, simply substituting the obtained target temperature difference into this correlation allows us to deduce the mixed thermal conductivity of the current ambient gas. This step does not require the introduction of any new parameters; the core is to rely on the established correlation logic to complete the conversion of thermophysical quantities (temperature difference) into gas characteristic parameters (thermal conductivity), providing a direct basis for subsequent calculations of the concentration of the gas to be detected.

[0061] As can be seen, this embodiment solves the problem of the inability to directly detect the thermal conductivity of mixed gases. By establishing a quantitative correlation between known parameters and a deducible temperature difference, the thermal conductivity of the gas can be calculated. By introducing parameters such as ambient temperature and initial resistance value, environmental interference and initial component errors are eliminated, ensuring that the correlation between temperature difference and thermal conductivity is a pure reflection of the gas properties. By integrating multiple parameters into a first correlation, the thermal conductivity can be obtained by simply substituting the temperature difference, avoiding repeated calculations of complex parameters, reducing system processing complexity, adapting to multiple scenarios, and providing reliable data support for the accurate calculation of the concentration of the gas to be detected, thus ensuring the final detection accuracy.

[0062] In one possible embodiment, the ambient temperature is a preset first reference temperature, the thermal conductivity sensor further includes a thermistor, the constant current driving circuit is connected to the thermistor, and the thermistor is used to sense the actual ambient temperature in the surrounding environment; the constant current driving circuit is also used to monitor and convert the resistance value of the thermistor into a temperature compensation voltage signal; and output the temperature compensation voltage signal; the control module is also used to determine the actual ambient temperature based on the temperature compensation voltage signal; and execute a temperature compensation algorithm based on the actual ambient temperature to compensate the ambient temperature and obtain the target concentration of the gas to be detected after temperature compensation.

[0063] Among them, thermistors focus on reflecting the temperature difference between the heater and the environment, reflecting changes in the thermal conductivity of the gas; while temperature-sensitive resistors are specifically used to sense the real temperature of the surrounding environment, independent of the heating system, ensuring the objectivity of the ambient temperature detection, breaking the limitation of setting the ambient temperature as the first reference temperature. For example, when the reference temperature is fixed, deviations from the actual environment will cause errors, thus realizing the dynamic capture of the real ambient temperature.

[0064] Specifically, the thermistor changes its resistance as the ambient temperature changes. For example, as the temperature rises, the resistance of the NTC thermistor decreases. The constant current drive circuit monitors the change in resistance and, through a circuit design similar to that of the thermistor (such as voltage acquisition and signal conditioning under constant current excitation), converts the change in resistance into a temperature-compensated voltage signal. This signal is output to the control module as the original electrical signal for analyzing the real ambient temperature.

[0065] For example, the temperature compensation algorithm includes: (1) Modeling the relationship between temperature and resistance: During the initialization phase, the control module establishes a model of the correspondence between temperature and resistance value based on the characteristics of the thermistor. For example, for most negative temperature coefficient (NTC) thermistors, the relationship between their resistance and temperature can be described by the Steinhart-Hart equation: , where T is the absolute temperature, R is the resistance of the thermistor, and A, B, and C are constants obtained through experimental calibration. Through this model, the control module can accurately calculate the ambient temperature based on the collected resistance of the thermistor; (2) Temperature compensation algorithm: When calculating the hydrogen concentration, the control module corrects the resistance of the thermistor based on the ambient temperature data. It is known that the resistance of the thermistor also follows a similar temperature-resistance relationship. The theoretical resistance of the thermistor at the current temperature is calculated based on the ambient temperature. Then, combined with the voltage signal across the thermistor collected by the constant current drive circuit, the true resistance value that is not affected by the ambient temperature is deduced. Then, based on the working principle of the thermal conductivity sensor, combined with the corrected resistance of the thermistor, the current value of the constant current, and other parameters, the hydrogen concentration after temperature compensation is calculated. Specifically, in constant current mode, based on the relationship between the thermal conductivity of the mixed gas and the temperature difference, the resistance of the thermistor, etc. (e.g. ,in Here, I represents the mixed thermal conductivity, I is the constant current value, and R is the real-time resistance value of the thermistor. For gas heat transfer geometric factor, (For the target temperature difference), the thermal conductivity of the mixed gas is recalculated using the corrected R value, thereby obtaining the accurate hydrogen concentration.

[0066] As can be seen, in this embodiment, the design of independently sensing the real ambient temperature by the thermistor, converting the compensation signal by the constant current drive circuit, and executing the algorithm correction by the control module breaks the limitation of the preset reference temperature. It dynamically captures the ambient temperature and corrects the temperature drift of the thermistor and the influence of temperature on the thermal conductivity of the gas. This not only eliminates the detection error caused by ambient temperature drift, but also ensures the calculation accuracy of the target concentration of the gas to be detected (such as hydrogen) in different temperature scenarios. At the same time, the reuse of mature circuit design reduces the system complexity.

[0067] In one possible embodiment, the system further includes an analog-to-digital conversion module connected to the voltage signal output terminal of the constant current drive circuit and the control module, respectively. The analog-to-digital conversion module receives the target voltage signal and the temperature compensation voltage signal output by the constant current drive circuit; performs analog-to-digital conversion on the target voltage signal and the temperature compensation voltage signal to obtain a first digital signal and a second digital signal; and outputs the first digital signal and the second digital signal to the control module. The control module receives the first digital signal to receive the target voltage signal and receives the second digital signal to execute the temperature compensation algorithm.

[0068] Among them, the analog-to-digital converter (ADC module) is a core electronic component. Its core function is to convert continuously changing analog signals (such as voltage and current) into discrete digital signals (such as binary code), realizing the key conversion from "analog quantity" to "digital quantity" and providing adaptation support for digital circuits (such as control modules and processors) to process signals.

[0069] As can be seen, in this embodiment, the gas detection method establishes a temperature difference by constant current driving heating, converts gas characteristics into electrical signals, and obtains a target voltage signal after processing; the target temperature difference is derived by combining preset relationships, and the mixed thermal conductivity is obtained by combining known parameters, thereby determining the concentration of the gas to be detected; a thermistor and compensation algorithm are introduced to eliminate the influence of environmental temperature drift, and the signal is digitized in conjunction with the analog-to-digital conversion module. The overall process ensures accurate detection of gas concentration in multiple scenarios, while also possessing circuit design flexibility and system stability.

[0070] Please see Figure 4 , Figure 4 This application provides a schematic flowchart for establishing a correlation between a mixed thermal conductivity and a temperature difference. The process for establishing a first correlation between the mixed thermal conductivity and the target temperature difference based on the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor includes the following steps:

[0071] Step S410: Establish a second correlation between the heating power of the first heating current and the heat dissipation of gas heat convection, gas heat conduction, solid heat conduction, and heat dissipation of energy by thermal radiation.

[0072] Understandably, when the first heating current drives the heater to generate heat, the system reaches a dynamic thermal equilibrium state where heat generation equals heat dissipation. Heating power (P) is the total energy input of the system, and heat is dissipated through four paths: gas convection, gas conduction, solid conduction, and radiation. The sum of the heat dissipation through these four paths equals the heating power. The second correlation transforms the abstract "thermal equilibrium" into a calculable mathematical expression, clarifying the energy proportion of each heat dissipation path. This allows for the "stripping away of non-target interference items" (such as solid conduction and radiation) in subsequent detection, focusing on the core "heat dissipation through gas conduction," which directly reflects the gas's thermal conductivity and is strongly correlated with the concentration of the gas being detected.

[0073] Specifically, the relational expression corresponding to the second association is as follows:

[0074] P= + + + ;

[0075] Where P represents the heating power of the first heating current, Indicates heat loss due to gas convection, Indicates the amount of heat dissipated through gas heat conduction. Indicates the heat dissipation due to solid heat conduction. This indicates the energy dissipated by thermal radiation.

[0076] Among them, the heat loss due to gas heat conduction ( This is a core detection correlation item. Heat is dissipated through the gas via "molecular thermal motion transfer," and its value is directly related to the gas's thermal conductivity.

[0077] Among them, the heat loss due to gas heat convection ( This is an environmental interference item. Heat is carried away by the "macroscopic flow" of the gas, such as by ambient airflow, and is unrelated to the gas's own thermal conductivity. Calibration is required to eliminate its interference with the detection.

[0078] Among them, the heat dissipation due to solid heat conduction ( This is a fixed loss item. Heat is transferred to the outside through solid structures such as the sensor housing and pins. Its value is determined by the sensor hardware structure (such as material and size). It is an inherent loss of the system and can be determined as a fixed value through factory calibration. It is deducted as a "constant" in subsequent calculations.

[0079] Among them, energy dissipated by thermal radiation ( The heat is a low-proportion interference term. Heat is radiated outward in the form of electromagnetic waves, and its proportion is extremely small in the scenario of "low heating power and small temperature difference". It can be ignored by simplifying the model or included in a fixed correction term.

[0080] Step S420: Simplify the second correlation to obtain the third correlation between the heating power of the first heating current and the heat dissipation of the gas through heat conduction.

[0081] It is understandable that, when the gas flow rate is very low, the energy dissipation generated by gas thermal convection is significant. It can be ignored; thermal radiation is proportional to the fourth power of temperature, and can be ignored at low temperatures (below 200℃). Therefore, it can be derived from the formula corresponding to the second correlation: "P= + + + Remove gas heat convection loss and heat dissipation from the list. and energy dissipation through thermal radiation The following formula is obtained:

[0082] P= + .

[0083] Furthermore, since the thermal conductivity of solids is generally higher than that of gases, in order to greatly reduce the interference signal from solid thermal conduction, a cantilever structure can usually be used for thermal conductivity sensors, making its thickness only a few hundred nanometers to a few micrometers. Solid thermal conduction can be ignored, thus further eliminating the heat loss due to solid thermal conduction. This allows us to obtain a third association.

[0084] Specifically, the relational expression corresponding to the third association is as follows:

[0085] P= .

[0086] Step S430: Determine the fourth correlation between the heating power of the first heating current and the thermal conductivity of the gas based on the third correlation.

[0087] Furthermore, it can be seen that the heat loss due to gas heat conduction is... The following relationship exists between the thermal conductivity of gases:

[0088] = ;

[0089] in, Represents the gas heat transfer geometric factor, Indicates the thermal conductivity of a gas. This indicates the temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature.

[0090] Furthermore, based on the third correlation, and the heat dissipation due to gas heat conduction... The relationship between the thermal conductivity of gases and the gas conductivity can be used to derive a fourth relationship, as shown in the following formula:

[0091] P= ;

[0092] Where P represents the heating power of the first heating current, Represents the gas heat transfer geometric factor, Indicates the thermal conductivity of a gas. This indicates the temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature.

[0093] Step S440: The heating power of the first heating current in the fourth correlation is characterized by the target temperature difference, ambient temperature, current value of constant current, and initial resistance value of the thermistor, so as to obtain the first correlation between the mixed thermal conductivity and the target temperature difference.

[0094] Specifically, the heating power of the first heating current in the fourth correlation is characterized by the target temperature difference, ambient temperature, constant current value, and initial resistance value of the thermistor, as shown in the following formula:

[0095] P= ;

[0096] Where P represents the heating power of the first heating current. This represents the current value of the first heating current. Indicates the resistance value. This indicates the initial resistance value of the thermistor. Indicates ambient temperature, This indicates the temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature. It represents the temperature coefficient of resistance and is dimensionless.

[0097] Furthermore, based on the above formula and the fourth correlation, it can be determined that " Then, by transforming the equation, we can obtain the first correlation between the mixed thermal conductivity and the target temperature difference.

[0098] Specifically, the relational expression corresponding to the first association is as follows:

[0099] ;

[0100] in, Indicates the thermal conductivity of a gas, Represents the gas heat transfer geometric factor, This indicates the temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature. The current value representing the first heating current. This indicates the initial resistance value of the thermistor. Indicates ambient temperature, It represents the temperature coefficient of resistance and is dimensionless.

[0101] Given a fixed structure and material for a thermal conductivity sensor chip, It is a definite value.

[0102] Understandably, based on the first correlation, it can be seen that when the ambient temperature remains constant, the thermal conductivity of the gas can be calculated based on the temperature change of the thermal conductivity sensor (chip) under constant current drive.

[0103] As can be seen, in this embodiment, the balance between heating power and four types of heat dissipation energy is first clarified using the second correlation. Then, by simplifying interference terms based on the application scenario and sensor structure, a third correlation is obtained between heating power and heat dissipation through gas thermal conduction. Subsequently, a fourth correlation is formed by relating the gas thermal conductivity. Finally, the heating power is characterized using known parameters, and the quantitative relationship between the mixed thermal conductivity and the target temperature difference is derived. The entire process ensures accuracy based on physical laws while simplifying and eliminating interference and reducing computational complexity, providing a reliable theoretical foundation for accurately calculating gas thermal conductivity and concentration, thus balancing practicality and efficiency.

[0104] In one possible embodiment, the control module is further configured to send a first control signal to the constant current drive circuit, the first control signal being configured to instruct the constant current drive circuit to output the constant current to the thermal conductivity sensor, or to output the periodic square wave current pulse.

[0105] After understanding the calculation method of thermal conductivity under constant current excitation in this application, the following is combined with... Figure 5 The method for calculating the thermal conductivity under pulsed constant current excitation in the embodiments of this application will be explained. Figure 5 This is a flowchart illustrating the steps of another gas detection method based on a thermal conductivity sensor provided in this application embodiment, as shown below. Figure 5 As shown, the method includes:

[0106] Step S510: When the first heating current is a periodic square wave current pulse, receive multiple target voltage signals output by the constant current drive circuit at multiple moments.

[0107] Understandably, unlike the previous "constant current continuous heating", the first heating current in this step adopts "periodic square wave current pulse", that is, the current is not continuously output, but works in a periodic pattern of heating when powered on (pulse high level) and cooling when powered off (pulse low level) (for example, a period of 100ms, of which 20ms is powered on and 80ms is powered off).

[0108] The core characteristic of this pulse heating mode is that the heater temperature dynamically changes with the cycle of power on and off, such as rising when power is on and falling when power is off, rather than maintaining a stable temperature difference. Therefore, simply collecting the voltage signal at a single moment cannot reflect the dynamic change pattern of the temperature; it is necessary to capture the temperature fluctuation characteristics within the complete cycle through "multi-moment acquisition".

[0109] The "target voltage signal" here is essentially the same as the target voltage signal in the constant current continuous heating mode. Both are output after being conditioned by the constant current drive circuit monitoring the resistance change of the thermistor, and their numerical change corresponds to the "temperature difference change between the heater and the environment". However, the difference is that this step needs to collect signals at "multiple moments". These moments need to cover the complete cycle of the periodic square wave pulse. For example, within one pulse cycle, voltage signals are collected at 1ms, 5ms, and 10ms when the power is on (heating process) and 1ms, 5ms, and 10ms when the power is off (cooling process), forming multiple sets of data. This allows for a complete record of the dynamic change curve of the temperature difference during the heating and cooling cycle, providing a data basis for subsequently inferring the gas thermal conductivity from the rate of temperature change.

[0110] Specifically, while the constant current drive circuit outputs square wave current pulses, it simultaneously records the pulse timing. Signal acquisition must be based on this timing and triggered at a preset "critical moment" to ensure that each acquired voltage signal can accurately correspond to a specific heating / heat dissipation stage within the pulse cycle.

[0111] Step S520: Determine multiple target temperature differences between the heating temperature of the thermal conductivity sensor and the ambient temperature during the thermal conduction process at multiple times based on multiple target voltage signals.

[0112] Specifically, similar to the derivation method in the aforementioned constant current mode, the target voltage signal at each moment is first converted into the real-time resistance value of the thermistor based on the third preset relationship between voltage and resistance; then, the real-time resistance value is converted into the target temperature difference between the heater and the environment at that moment through the fourth preset relationship between resistance and temperature difference. However, in the pulse constant current mode, multiple sets of temperature difference data covering the pulse heating and heat dissipation cycles can be obtained.

[0113] Step S530: Obtain the mixed thermal conductivity of the surrounding gas based on multiple target temperature differences, multiple time points, a first preset relationship, and a second preset relationship.

[0114] The first preset relationship characterizes the correlation between the thermal conductivity response time constant of the thermal conductivity sensor and the target temperature difference and the multiple time points.

[0115] The second preset relationship characterizes the correlation between the thermal conductivity response time constant and the mixed thermal conductivity, specifically a negative correlation.

[0116] In one possible embodiment, obtaining the mixed thermal conductivity of the ambient gas based on multiple target temperature differences, multiple time points, a first preset relationship, and a second preset relationship includes: determining the thermal conductivity response time constant of the thermal conductivity sensor based on the multiple target temperature differences, the multiple time points, and the first preset relationship; determining the mixed thermal conductivity of the ambient gas based on the thermal conductivity response time constant of the thermal conductivity sensor and the second preset relationship, wherein the second preset relationship indicates a negative correlation between the thermal conductivity response time constant and the mixed thermal conductivity.

[0117] The first preset relation corresponds to the following formula:

[0118] (t) = ;

[0119] Where t represents time. (t) represents the target temperature difference at time t. This represents the theoretical maximum temperature difference, that is, as time t approaches infinity, the temperature difference approaches... , This represents the thermal conductivity response time constant.

[0120] The thermal conductivity response time constant is related to factors such as the mixed thermal conductivity of the surrounding gas; the higher the mixed thermal conductivity, the faster the heat transfer. Generally, the smaller the difference, the closer the temperature difference tends to be. The faster the speed, the better.

[0121] Specifically, determining the thermal conductivity response time constant of the thermal conductivity sensor based on the multiple target temperature differences, the multiple time points, and the first preset relationship includes: substituting the multiple temperature differences and their corresponding multiple time points into the expression corresponding to the first preset relationship, fitting the data using a curve fitting algorithm, and then deriving the thermal conductivity response time constant.

[0122] Furthermore, as can be seen from the second preset relationship, there is a negative correlation between the thermal conductivity response time constant and the mixed thermal conductivity. Based on the thermal conductivity response time constant and this negative correlation, such as a linear relationship, the mixed thermal conductivity can be calculated.

[0123] As can be seen, in this embodiment, the thermal conductivity response time constant is derived by fitting the target temperature difference data at multiple time points using the first preset relationship, and then converted into a mixed thermal conductivity coefficient based on the second preset relationship (the time constant is negatively correlated with the thermal conductivity). The entire process relies on dynamic data fitting to eliminate single-point errors, and achieves quantitative conversion from temperature response to thermophysical parameters through a clear preset relationship. This fully leverages the advantages of dynamic characteristics under pulse drive, improves the accuracy and reliability of the mixed thermal conductivity coefficient calculation, and lays a key parameter foundation for the subsequent detection of the gas concentration.

[0124] Step S540: Determine the target concentration of the gas to be detected in the surrounding ambient gas based on the mixed thermal conductivity.

[0125] For example, the concentration is determined by a preset "correspondence between the mixed thermal conductivity and the concentration of the gas to be detected": based on the inherent difference in thermal conductivity between the gas to be detected (such as hydrogen) and other gases, a quantitative correlation model (such as a linear or nonlinear function relationship) between the mixed thermal conductivity and the concentration of the gas to be detected is established by experimental calibration. The obtained mixed thermal conductivity is substituted into the model to directly calculate the target concentration of the gas to be detected.

[0126] It should be noted that this application does not limit the specific implementation methods for determining gas concentration based on thermal conductivity.

[0127] As can be seen, in this embodiment, a constant current or pulsed constant current excitation is output to the thermal conductivity sensor to drive the heater to establish a temperature difference. Then, relying on a thermistor to sense the temperature difference change and convert it into an electrical signal, the dynamic temperature difference is derived by combining multi-moment data (in pulse mode). Based on a preset relationship, the thermal conductivity of the mixed gas in the surrounding environment is inferred from the temperature difference. Finally, the concentration value is determined by the correlation between the thermal conductivity and the concentration of the gas to be detected. This solution adapts to different heating requirements, improves the accuracy of thermal conductivity and concentration calculation, and the pulse mode balances energy saving and sensor lifespan, achieving accuracy and reliability of gas detection in multiple scenarios, effectively improving system adaptability and detection performance.

[0128] Please see Figure 6 , Figure 6 This is a partial circuit structure diagram of a constant current drive circuit provided in an embodiment of this application, such as... Figure 6 As shown, the constant current drive circuit includes a reference voltage module, a follower module, a first inverting proportional amplifier, and a second inverting proportional amplifier.

[0129] The reference voltage module provides a stable and high-precision reference voltage, serving as a voltage reference for subsequent circuits and ensuring the stability of the voltage reference throughout the constant current drive, which is fundamental to the accuracy of the constant current. Specifically, in the reference voltage module, the iSL21010 is the reference voltage source chip, the core component, which outputs a high-precision reference voltage; U6 is the stable voltage output; Vin is the power input pin, connected to the power supply; Vout and Vref are the reference voltage output pins, providing reference voltage to external circuits; GND is the ground pin, providing zero potential; C10 and C11 are the filter capacitor and decoupling capacitor, respectively, used to filter noise and stabilize the power supply; R10 is the current limiting or voltage dividing resistor, and R14 is the feedback resistor, which helps maintain the stability of the output voltage.

[0130] The voltage follower module acts as a voltage follower and isolation buffer, transmitting the voltage signal output from the reference voltage module to the subsequent circuitry without attenuation or distortion. Simultaneously, it blocks interference from the subsequent circuitry to the reference voltage module, improving the circuit's anti-interference capability and signal transmission quality. Specifically, in the voltage follower module, U7A is the A channel of the operational amplifier, forming the core of the voltage follower. This is the non-inverting input terminal of the operating amplifier, which receives the input signal; , For signal input interfaces (positive and negative terminals); C34 and C35 are the output terminals of the operational amplifier, which outputs a signal that follows the input signal. C34 and C35 are compensation capacitors used to stabilize the operation of the operational amplifier, prevent self-oscillation, and ensure the stability and accuracy of signal following.

[0131] The first inverting proportional amplifier is used to amplify the input voltage in reverse proportion. It also integrates with the "gas-sensitive bridge arm (thermal conductivity sensor)" to achieve the core logic of constant current control. Specifically, by incorporating the thermal conductivity sensor as part of the bridge arm, the characteristics of the inverting proportional amplifier are utilized to stabilize the current flowing through the sensor, unaffected by changes in sensor resistance, thus achieving constant current drive. Specifically, in the first inverting proportional amplifier, U7B is the B channel of the operational amplifier, the core component constituting the inverting proportional operation; R11 is the input resistor, receiving the signal to be processed (such as the sensor or pre-amplifier output); R12 is the feedback resistor, working with R11 to determine the amplification factor; R16 is the balancing resistor, used to eliminate the influence of the operational amplifier's input bias current; and Rm is the thermistor, specifically the thermistor in the thermal conductivity sensor circled in the upper right corner of the diagram. As the output terminal of the arithmetic unit, it outputs the inverted and amplified signal to adjust the signal amplitude to meet the requirements of subsequent circuits.

[0132] The second inverting amplifier is used to further invert the signal, which can be used for secondary signal amplification, level adjustment, or preparation for subsequent signal acquisition (such as AD conversion). It amplifies the weak voltage signal generated by the thermal conductivity sensor due to gas thermal conductivity changes to a suitable range for subsequent detection and processing. Specifically, in the second inverting amplifier, U7C is the C channel of the operational amplifier; Rt is the thermistor, which is the thermistor in the thermal conductivity sensor circled in the upper right corner of the figure; R9, R13, and R17 are configuration resistors; C12 is a compensation or filter capacitor; and U0 is the output terminal, which outputs the signal after inverting the amplifier, realizing accurate amplification and processing of temperature-related signals.

[0133] As can be seen, in this embodiment, the constant current drive circuit includes a reference voltage module, a follower module, a first inverse proportional amplifier module, and a second inverse proportional amplifier module. The reference voltage module provides a stable and high-precision reference voltage; the follower module implements voltage following and isolation buffering to ensure stable signal transmission; the first inverse proportional amplifier module, combined with the thermal conductivity sensor, utilizes the inverse proportional characteristic to achieve constant current drive; the second inverse proportional amplifier module performs secondary signal processing, amplifying the weak voltage to a suitable range for subsequent detection. All modules work together to provide stable current excitation and signal processing support for thermal conductivity gas detection.

[0134] Please see Figure 7 , Figure 7 This is a functional module diagram of a gas detection system provided in an embodiment of this application, as shown below. Figure 7 As shown, taking the detection of hydrogen concentration in a mixed gas in the surrounding environment as an example, the gas detection system 100 includes an initialization module 710, a hydrogen concentration calculation module 720, and a main circulation module 730.

[0135] The initialization module 710 includes peripheral hardware initialization, parameter initialization, and task queue initialization. Peripheral hardware initialization configures hardware such as the constant current drive circuit, temperature and gas resistor acquisition circuit, and analog-to-digital conversion module to ensure stable operation of each piece of hardware. Parameter initialization sets key parameters such as reference voltage, operational amplifier amplification factor, temperature compensation coefficient, and sensor response model parameters to provide a basis for subsequent calculations. Task queue initialization plans the execution order and priority of tasks such as "controlling constant current drive current," "starting analog-to-digital conversion," and "data output" to ensure the orderly progress of the detection process.

[0136] The hydrogen concentration calculation module 720 first calculates the ambient temperature using a thermistor, specifically converting the temperature signal into an electrical signal and combining the temperature and resistance characteristics of the thermistor to calculate the ambient temperature. Then, after temperature compensation, it calculates the hydrogen concentration, specifically using a temperature compensation coefficient to correct the gas thermal conductivity calculated based on the thermal response of the gas thermistor, and then calculating the hydrogen concentration value based on the thermal conductivity.

[0137] The main loop module 730 includes a control start constant current drive circuit to provide a stable constant current excitation for the thermistor of the thermal conductivity sensor, so that the thermistor generates an electrical signal related to the hydrogen concentration due to heat exchange with the hydrogen-containing gas; then the analog-to-digital conversion module is started to sample the relevant analog electrical signal and convert it into a digital quantity for subsequent calculation; finally, the calculated hydrogen concentration value is output as data in an appropriate form, completing the closed loop from detection to result presentation.

[0138] As can be seen, in this embodiment, by using constant current or constant current pulse driving, combined with MEMS sensing chip and digital signal processing, the system processing complexity is significantly reduced while ensuring detection accuracy. Compared with traditional methods, it has significant improvements in sensor response speed, power consumption and temperature stability.

[0139] The above primarily describes the solutions of the embodiments of this application from the perspective of the method execution process. It is understood that, in order to achieve the above functions, mobile electronic devices include corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments provided herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art 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.

[0140] This application embodiment can divide the electronic device into functional units according to the above method example. For example, each function can be divided into a separate functional unit, or two or more functions can be integrated into one processing unit. The integrated unit can be implemented in hardware or as a software functional unit. It should be noted that the unit division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0141] Furthermore, this application embodiment also provides a computer storage medium that stores a computer program capable of being loaded by a processor and executed as described above for the gas detection method based on a thermal conductivity sensor. The computer-readable storage medium includes, for example, various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0142] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0143] In the several embodiments provided in this application, it should be understood that the disclosed methods, apparatuses, and systems can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for example, the division of units is merely a logical functional division, and other division methods may exist in actual implementation; for example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0144] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can be physically comprised separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or in a combination of hardware and software functional units.

[0145] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute some steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, volatile memory, or non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DRRAM), etc., which are various media capable of storing program code.

[0146] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0147] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0148] While this application discloses the above information, it is not limited thereto. Any person skilled in the art can easily conceive of variations or substitutions without departing from the spirit and scope of this application, and can make various alterations and modifications, including combinations of the different functions and implementation steps described above, as well as software and hardware implementation methods, all of which are within the protection scope of this application.

Claims

1. A gas detection method based on a thermal conductivity sensor, characterized in that, This invention is applied to a gas detection system, which includes a constant current drive circuit, a thermal conductivity sensor, and a control module. The thermal conductivity sensor includes a thermistor. The current output terminal of the constant current drive circuit is connected to the current input terminal of the thermal conductivity sensor. The voltage acquisition terminal of the constant current drive circuit is connected in parallel with both ends of the thermistor. The control module is connected to the constant current drive circuit. The constant current driving circuit is used to output a first heating current to the thermal conductivity sensor, the first heating current including a constant current; and to monitor and convert the resistance value of the thermistor into a target voltage signal; and to output the target voltage signal. The thermal conductivity sensor is used to detect the gas to be detected in the surrounding environment gas by means of thermal conduction under the excitation of the first heating current. The control module is configured to receive the target voltage signal; and determine, based on the target voltage signal, the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during the heat conduction process; and obtain the mixed thermal conductivity of the surrounding ambient gas based on the target temperature difference, the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor; and determine the target concentration of the gas to be detected in the surrounding ambient gas based on the mixed thermal conductivity. The method of obtaining the mixed thermal conductivity of the surrounding gas based on the target temperature difference, the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor includes: A first correlation is established between the mixed thermal conductivity and the target temperature difference based on the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor. The first correlation indicates that there is a negative correlation between the mixed thermal conductivity and the target temperature difference. The mixed thermal conductivity of the surrounding gas is determined based on the target temperature difference and the first correlation.

2. The method according to claim 1, characterized in that, The first heating current also includes periodic square wave current pulses; The control module is further configured to receive multiple target voltage signals output by the constant current drive circuit at multiple times when the first heating current is the periodic square wave current pulse; and, Based on the multiple target voltage signals, determine multiple target temperature differences between the heating temperature of the thermal conductivity sensor and the ambient temperature during the heat conduction process at the multiple times; The mixed thermal conductivity of the surrounding gas is obtained based on the multiple target temperature differences, the multiple time points, the first preset relationship, and the second preset relationship. The first preset relationship characterizes the correlation between the thermal conductivity response time constant of the thermal conductivity sensor and the target temperature differences and the multiple time points. The second preset relationship characterizes the correlation between the thermal conductivity response time constant and the mixed thermal conductivity. The target concentration of the gas to be detected in the surrounding environment gas is determined based on the mixed thermal conductivity.

3. The method according to claim 2, characterized in that, The step of obtaining the mixed thermal conductivity of the surrounding gas based on the multiple target temperature differences, the multiple time points, the first preset relationship, and the second preset relationship includes: The thermal conductivity response time constant of the thermal conductivity sensor is determined based on the plurality of target temperature differences, the plurality of time points, and the first preset relationship. The mixed thermal conductivity of the surrounding gas is determined based on the thermal conductivity response time constant of the thermal conductivity sensor and the second preset relationship, wherein the second preset relationship indicates that there is a negative correlation between the thermal conductivity response time constant and the mixed thermal conductivity.

4. The method according to claim 1, characterized in that, The step of establishing a first correlation between the mixed thermal conductivity and the target temperature difference based on the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor includes: Establish a second correlation between the heating power of the first heating current and the heat dissipation of gas heat convection, gas heat conduction, solid heat conduction, and heat dissipation of energy by thermal radiation. The second correlation is simplified to obtain a third correlation between the heating power of the first heating current and the heat dissipation through gas heat conduction. A fourth correlation is determined between the heating power of the first heating current and the gas thermal conductivity based on the third correlation. The heating power of the first heating current in the fourth correlation is characterized by the target temperature difference, the ambient temperature, the current value of the constant current, and the initial resistance value of the thermistor, thereby obtaining the first correlation between the mixed thermal conductivity and the target temperature difference.

5. The method according to claim 1, characterized in that, Determining the target temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature during the heat conduction process based on the target voltage signal includes: The target resistance value of the thermistor is determined based on the target voltage signal and the third preset relationship, wherein the third preset relationship characterizes the positive correlation between the resistance value of the thermistor and the output voltage of the constant current drive circuit. The target temperature difference is determined based on the target resistance value of the thermistor and a fourth preset relationship, wherein the fourth preset relationship characterizes the positive correlation between the temperature difference between the heating temperature of the thermal conductivity sensor and the ambient temperature and the resistance value of the thermistor.

6. The method according to claim 5, characterized in that, The ambient temperature is a preset first reference temperature. The thermal conductivity sensor also includes a thermistor. The constant current drive circuit is connected to the thermistor. The thermistor is used to sense the real ambient temperature in the surrounding environment. The constant current driving circuit is also used to monitor and convert the resistance value of the thermistor into a temperature compensation voltage signal; and to output the temperature compensation voltage signal. The control module is also used to determine the actual ambient temperature based on the temperature compensation voltage signal; Furthermore, a temperature compensation algorithm is executed based on the actual ambient temperature to compensate the ambient temperature and obtain the target concentration of the gas to be detected after temperature compensation.

7. The method according to claim 6, characterized in that, The system also includes an analog-to-digital converter module, which is connected to the voltage signal output terminal of the constant current drive circuit and the control module, respectively. The analog-to-digital conversion module is used to receive the target voltage signal and the temperature compensation voltage signal output by the constant current drive circuit; and to perform analog-to-digital conversion operations on the target voltage signal and the temperature compensation voltage signal respectively to obtain a first digital signal and a second digital signal. And, output the first digital signal and the second digital signal to the control module; The control module is configured to receive the first digital signal to receive the target voltage signal; and to receive the second digital signal to execute the temperature compensation algorithm.

8. The method according to claim 2, characterized in that, The control module is also used to send a first control signal to the constant current drive circuit, the first control signal being used to instruct the constant current drive circuit to output the constant current to the thermal conductivity sensor, or to output the periodic square wave current pulse.

9. A gas detection system, characterized in that, The system includes a constant current drive circuit, a thermal conductivity sensor, and a control module. The thermal conductivity sensor includes a thermistor. The current output terminal of the constant current drive circuit is connected to the current input terminal of the thermal conductivity sensor. The voltage acquisition terminal of the constant current drive circuit is connected in parallel with both ends of the thermistor. The control module is connected to the constant current drive circuit. The system is used to perform the steps in the method as described in any one of claims 1-8.

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