A semiconductor gas sensor with constant heating power

Abstract

The application relates to the technical field of gas detection, in particular to a semiconductor gas sensor with constant heating power, which comprises a sensor module and a heating power control system; a heating power detection end of the sensor module is electrically connected with an input end of the heating power control system, and a control end of the heating power control system is electrically connected with a heating wire power supply end of the sensor module; the heating power control system is used for detecting the heating power of the heating wire of the sensor module, and reversely adjusting the power supply power of the heating wire of the sensor module according to the change of the heating power; the heating wire of the sensor is kept in constant-power heating, the service life, stability and precision of the sensor are improved, and the semiconductor gas sensor can be applied to more application scenes with severe environments.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a semiconductor gas sensor with constant heating power. Background Technology

[0002] Gas sensors mainly include semiconductor, contact combustion, chemical reaction, optical interference, thermal conduction, and infrared absorption diffusion types. Among these, semiconductor gas sensors are more widely used due to their inherent selectivity. A semiconductor gas sensor consists of a gas-sensitive element, a heating wire, and an explosion-proof mesh. It is a sensor in which sensitizers such as Pt and Pd are added to metal oxides such as SnO2, Fe2O2, and ZnO2 in the gas-sensitive element. The selectivity of the sensor is controlled by the amount of sensitizer added. For example, for ZnO2 series sensors, adding Pt results in higher sensitivity to propane and isobutane; adding Pd results in greater sensitivity to CO and H2.

[0003] The two key components of a semiconductor gas sensor are the heating wire and the gas-sensitive membrane (gas-sensitive part). It uses a ceramic tube as a frame, covered with a layer of sensitive membrane material, and measures are performed using gold-plated leads at both ends of the membrane. Common materials for the sensitive membrane include metal oxides, polymer materials, and colloidal sensitive membranes. The gold electrodes connect the two ends of the gas-sensitive material, making it equivalent to a resistor whose resistance changes with the concentration of the external gas to be measured. Because metal oxides have high thermal stability, and this type of sensor only undergoes a reversible redox reaction on the semiconductor surface layer while the internal chemical structure of the semiconductor remains unchanged, it can maintain high stability even with long-term use. The principle is briefly described as follows: When the metal oxide is heated by the heating wire, oxygen in the air will steal electrons from the donor levels of the metal oxide semiconductor crystal particles and adsorb negative electrons on the crystal surface, increasing the surface potential and thus hindering the movement of conductive electrons. Therefore, the sensor has a constant resistance value in air. At this time, a reducing gas reacts with the oxygen adsorbed on the semiconductor surface in an oxidation reaction. Due to the adsorption-removal effect of gas molecules, the surface potential changes, and therefore the resistance value of the sensor changes. For reducing gases, the resistance decreases; for oxidizing gases, the resistance increases. Thus, the concentration of a gas can be detected by observing changes in resistance.

[0004] Based on the aforementioned characteristics of semiconductor gas sensors, such as operation in high and low temperature and high and low humidity environments, the heating efficiency of the heating wire will be affected. That is, under a normal fixed voltage, the actual heating power will fluctuate in different ways. This causes the gas-sensitive part of the sensor to be easily heated by fluctuating temperature, resulting in performance degradation, which in turn leads to a decrease in the stability and accuracy of the sensor, reduces the lifespan of the sensor, and limits the application environment of the sensor. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to provide a semiconductor gas sensor with constant heating power, which maintains constant power heating of the sensor's heating wire, thereby improving the sensor's service life, stability, and accuracy, and enabling its application in more harsh environments.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A semiconductor gas sensor with constant heating power includes a sensor module and a heating power control system; the heating power detection terminal of the sensor module is electrically connected to the input terminal of the heating power control system, and the control terminal of the heating power control system is electrically connected to the heating wire power supply terminal of the sensor module.

[0008] The heating power control system is used to detect the heating power of the heating wire of the sensor module, and adjust the power supply of the heating wire of the sensor module in reverse according to the change of the heating power.

[0009] Furthermore, the heating power control system includes a controller module, a heating power detection module, and a constant power adjustment module; the input terminal of the heating power detection module is used as the input terminal of the heating power control system, and the output terminal of the constant power adjustment module is used as the control terminal of the heating power control system.

[0010] The output terminal of the heating power detection module is electrically connected to the input terminal of the controller module, and the output terminal of the controller module is electrically connected to the input terminal of the constant power adjustment module.

[0011] The heating power detection module is used to detect the heating power of the heating wire of the sensor module;

[0012] The controller module is used to receive the heating power and generate an adjustment signal in reverse according to the change of the heating power;

[0013] The constant power adjustment module is used to receive and adjust the power supply of the heating wire of the sensor module according to the adjustment signal;

[0014] The adjustment signal is a PWM signal.

[0015] Furthermore, the controller module is used to receive the heating power and the built-in constant heating power, then derive the power control quantity according to the PID algorithm, and generate an adjustment signal according to the power control quantity.

[0016] Furthermore, the sensor module includes a semiconductor gas sensor chip U5; both the VH terminal and the GND terminal of the semiconductor gas sensor chip U5 are used as heating power detection terminals of the sensor module, and the VH terminal of the semiconductor gas sensor chip U5 is used as the heating wire power supply terminal of the sensor module.

[0017] Furthermore, the constant power adjustment module includes resistors R8 and R9, capacitors C9 and C10, an isolation operational amplifier chip U6, capacitor C11, resistors R13 and R14, and transistor Q2; one end of resistor R8 is used as the input terminal of the constant power adjustment module, and one end of resistor R13 is used as the output terminal of the constant power adjustment module.

[0018] The other end of resistor R8 and one end of capacitor C9 are both electrically connected to one end of resistor R9. The other end of resistor R9 and capacitor C10 are both electrically connected to the +IN terminal of isolation operational amplifier chip U6. The other end of capacitor C9 and the other end of capacitor C10 are grounded. One end of capacitor C11 is electrically connected to the +VS terminal of isolation operational amplifier chip U6. The other end of capacitor C11 is electrically connected to the -VS terminal of isolation operational amplifier chip U6. One end of capacitor C11 is connected to a +5V power supply. The other end of capacitor C11 is grounded. The OUT terminal of isolation operational amplifier chip U6 is electrically connected to the base of transistor Q2. The -IN terminal of isolation operational amplifier chip U6 and one end of resistor R14 are both electrically connected to the other end of resistor R13. The other end of resistor R14 is grounded. One end of resistor R13 is electrically connected to the emitter of transistor Q2. The collector of transistor Q2 is connected to a +5V power supply.

[0019] Furthermore, the heating power detection module includes a voltage detection circuit and a current detection circuit; the input terminal of the voltage detection circuit and the input terminal of the current detection circuit are both used as input terminals of the heating power detection module, and the output terminal of the voltage detection circuit and the output terminal of the current detection circuit are both used as output terminals of the heating power detection module.

[0020] The input terminal of the voltage detection circuit is electrically connected to the VH terminal of the semiconductor gas sensor chip U; the input terminal of the current detection circuit is electrically connected to the GND terminal of the semiconductor gas sensor chip U.

[0021] The voltage detection circuit is used to detect the heating voltage of the heating wire of the semiconductor gas sensor chip U;

[0022] The current detection circuit is used to detect the heating current of the heating wire of the semiconductor gas sensor chip U.

[0023] Furthermore, the voltage detection circuit includes resistors R11 and R12; one end of resistor R11 is used as the output terminal of the voltage detection circuit, and the other end of resistor R11 is used as the input terminal of the voltage detection circuit; one end of resistor R11 and one end of resistor R12 are electrically connected, and the other end of resistor R12 is grounded.

[0024] Furthermore, the current detection circuit includes a resistor R7; one end of the resistor R7 serves as the input or output terminal of the voltage detection circuit; the other end of the resistor R7 is grounded.

[0025] Furthermore, the heating power control system also includes an isolation operational amplifier module; the output terminal of the sensor module is electrically connected to the input terminal of the isolation operational amplifier module; the output terminal of the isolation operational amplifier module is electrically connected to the detection terminal of the controller module;

[0026] The isolation operational amplifier module is used to isolate, amplify, and transmit the gas detection signal detected by the sensor module to the controller module.

[0027] Furthermore, the sensor module also includes a resistor R4; the VS terminal of the semiconductor gas sensor chip U5 is used as the output terminal of the sensor module.

[0028] One end of the resistor R4 is electrically connected to the VS terminal of the semiconductor gas sensor chip U5, and the other end of the resistor R4 is connected to the VDD power supply.

[0029] The isolated operational amplifier module includes a capacitor C8 and an isolated operational amplifier chip U4; the +IN terminal of the isolated operational amplifier chip U4 is used as the input terminal of the isolated operational amplifier module, and the OUT terminal of the isolated operational amplifier chip U4 is used as the output terminal of the isolated operational amplifier module.

[0030] The OUT and -IN terminals of the isolation operational amplifier chip U4 are electrically connected. The +VS terminal of the isolation operational amplifier chip U4 is electrically connected to one end of the capacitor C8, and the -VS terminal of the isolation operational amplifier chip U4 is electrically connected to the other end of the capacitor C8. One end of the capacitor C8 is connected to the VDD power supply, and the other end of the capacitor C8 is grounded.

[0031] The technical solution provided by this invention can include the following beneficial effects: the heating power of the heating wire of the sensor module is detected in real time by the heating power control system, and the power supply of the heating wire of the sensor module is adjusted in reverse according to the change of heating power. That is, when the heating power of the heating wire increases, the heating power can be reduced by reducing the power supply of the heating wire, so that the heating power is reduced and kept at a constant power state. This ensures that the sensor performance will not be reduced due to the fluctuation of the actual heating power, improves the service life, stability and accuracy of the sensor, and can be applied to more harsh environmental application scenarios. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a semiconductor gas sensor with constant heating power, which is one embodiment of the present invention.

[0033] Figure 2 Is it like this? Figure 1 The diagram shows a partial circuit diagram of the controller module.

[0034] Figure 3 Is it like this? Figure 1 The circuit diagram of the heating power detection module and sensor module is shown.

[0035] Figure 4 Is it like this? Figure 1 The circuit diagram of the constant power regulation module is shown.

[0036] Figure 5 Is it like this? Figure 1 The circuit diagram of the isolated operational amplifier module is shown.

[0037] The components include: controller module 1, sensor module 2, heating power detection module 3, constant power adjustment module 4, heating power control system 6, semiconductor gas sensor chip U5, resistors R8 and R9, capacitors C9 and C10, isolation operational amplifier chip U6, capacitor C11, resistors R13 and R14, transistor Q2, voltage detection circuit 31, current detection circuit 32, resistors R11, R12, and R7, isolation operational amplifier module 5, resistor R4, capacitor C8, and isolation operational amplifier chip U4. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0039] In the description of embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0041] The following is combined with Figures 1 to 5 This describes a semiconductor gas sensor with constant heating power according to an embodiment of the present invention.

[0042] A semiconductor gas sensor with constant heating power includes a sensor module 2 and a heating power control system 6; the heating power detection terminal of the sensor module 2 is electrically connected to the input terminal of the heating power control system 6, and the control terminal of the heating power control system 6 is electrically connected to the heating wire power supply terminal of the sensor module 2.

[0043] The heating power control system 6 is used to detect the heating power of the heating wire of the sensor module 2, and adjust the power supply of the heating wire of the sensor module 2 in reverse according to the change of heating power.

[0044] In a preferred embodiment of the semiconductor gas sensor with constant heating power proposed in this invention, such as... Figures 1 to 5 As shown, the heating power control system 6 detects the heating power of the heating wire of the sensor module 2 in real time, and adjusts the power supply of the heating wire of the sensor module 2 in reverse according to the change of heating power. That is, when the heating power of the heating wire increases, the heating power can be reduced by reducing the power supply of the heating wire, so that the heating power is reduced and kept at a constant power state. This prevents the sensor performance from being reduced due to the fluctuation of the actual heating power, improves the service life, stability and accuracy of the sensor, and can be applied to more harsh environmental application scenarios.

[0045] Furthermore, the heating power control system 6 includes a controller module 1, a heating power detection module 3, and a constant power adjustment module 4; the input terminal of the heating power detection module 3 is used as the input terminal of the heating power control system 6, and the output terminal of the constant power adjustment module 4 is used as the control terminal of the heating power control system 6.

[0046] The output terminal of the heating power detection module 3 is electrically connected to the input terminal of the controller module 1, and the output terminal of the controller module 1 is electrically connected to the input terminal of the constant power adjustment module 4.

[0047] The heating power detection module 3 is used to detect the heating power of the heating wire in the sensor module 2;

[0048] The controller module 1 is used to receive the heating power and generate an adjustment signal in reverse according to the change of the heating power;

[0049] The constant power adjustment module 4 is used to receive and adjust the power supply of the heating wire of the sensor module 2 according to the adjustment signal;

[0050] The adjustment signal is a PWM signal.

[0051] In this embodiment, the heating power control system 6 needs to achieve negative feedback regulation of the sensor module 2. A feedback loop is formed by the controller module 1, the heating power detection module 3, and the constant power adjustment module 4. The heating power detection module 3 detects the heating power of the heating wire in the sensor module 2 in real time and feeds it back to the controller module 1, causing the controller module 1 (e.g., ...) to adjust the heating power of the heating wire in the sensor module 2. Figure 2 The MCU can generate an adjustment signal in reverse according to the change in heating power, so that the constant power adjustment module 4 can adjust the power supply of the heating wire of the sensor module 2 in reverse through the adjustment signal. That is, when the heating power of the heating wire increases, the heating power can be reduced by reducing the power supply of the heating wire, so that the heating power is reduced and kept at a constant power state.

[0052] Specifically, since the adjustment signal is mainly used to reverse the heating power of the heating wire to keep it at a constant value, the adjustment signal can be a fixed value corresponding to the detected heating power. However, if a corresponding method is used to form the adjustment relationship, the adjustment process will not be continuous enough, and there will be jumps between the two corresponding values, which will also affect the performance of the sensor and the reverse adjustment accuracy will not be sufficient. Therefore, using a PWM signal for the adjustment signal can make the heating power reduction or reduction process continuous and smooth, and the accuracy is higher.

[0053] Furthermore, the controller module 1 is used to receive the heating power and the built-in constant heating power, then derive the power control quantity according to the PID algorithm, and generate an adjustment signal based on the power control quantity.

[0054] In this embodiment, during the process of generating the adjustment signal by the controller module 1 in reverse adjustment according to the change of heating power, in order to further improve the matching degree between heating power and power supply and avoid overshoot, it is preferable to use the PID algorithm to generate the power deviation value to adjust the duty cycle of the PWM signal, and finally form the adjustment signal.

[0055] Because the PID algorithm is a feedback control algorithm used to adjust the system output to approach the expected target value, when controlling the power supply, the PID control algorithm can calculate a power control quantity based on the difference between the real-time measured heating power value and the constant heating power (the target setting is to maintain a constant heating power). This control quantity can be mapped to the duty cycle of the PWM signal, thereby adjusting the power supply to the heating wire. If the actual heating power is lower than the target heating power, the power control quantity increases the duty cycle, increasing the power supply to the heating wire; conversely, if the actual power is higher than the target power, the power control quantity decreases the duty cycle, decreasing the power supply to the heating wire. By continuously measuring the actual power and adjusting the duty cycle of the PWM signal, the PID algorithm can keep the power supply to the heating wire near the constant heating power.

[0056] It should be noted that in the PID control algorithm: the proportional controller is used to adjust the PWM duty cycle according to the power deviation; the integral controller is used to eliminate static errors and improve stability; and the derivative controller is used to reduce system overshoot and improve response speed. Therefore, the performance of the PID algorithm largely depends on the selection and adjustment of the three gain parameters (Kp, Ki, and Kd). The selection of these parameters requires experimentation and debugging based on the specific system characteristics and control requirements.

[0057] Furthermore, the sensor module 2 includes a semiconductor gas sensor chip U5; both the VH terminal and the GND terminal of the semiconductor gas sensor chip U5 are used as heating power detection terminals of the sensor module 2, and the VH terminal of the semiconductor gas sensor chip U5 is used as the heating wire power supply terminal of the sensor module 2.

[0058] In this embodiment, the core of sensor module 2 is semiconductor gas sensor chip U5. Therefore, to detect the heating power of the heating wire in sensor module 2 in real time, the heating voltage and heating current of the heating wire can be measured from the VH terminal and GND terminal of semiconductor gas sensor chip U5, respectively. After being transmitted to controller module 1, controller module 1 can calculate the heating power. During feedback regulation, while keeping the heating wire current constant, the power supply of the heating wire can be regulated simply by adjusting the heating voltage of the heating wire. That is, the constant power regulation module 4 can adjust the voltage of the VH terminal of semiconductor gas sensor chip U5.

[0059] Furthermore, the constant power adjustment module 4 includes resistors R8 and R9, capacitors C9 and C10, an isolation operational amplifier chip U6, capacitor C11, resistors R13 and R14, and transistor Q2; one end of resistor R8 is used as the input terminal of the constant power adjustment module 4, and one end of resistor R13 is used as the output terminal of the constant power adjustment module 4.

[0060] The other end of resistor R8 and one end of capacitor C9 are both electrically connected to one end of resistor R9. The other end of resistor R9 and capacitor C10 are both electrically connected to the +IN terminal of isolation operational amplifier chip U6. The other ends of capacitor C9 and capacitor C10 are grounded. One end of capacitor C11 is electrically connected to the +VS terminal of isolation operational amplifier chip U6. The other end of capacitor C11 is electrically connected to the -VS terminal of isolation operational amplifier chip U6. One end of capacitor C11 is connected to a +5V power supply. The other end of capacitor C11 is grounded. The OUT terminal of isolation operational amplifier chip U6 is electrically connected to the base of transistor Q2. The -IN terminal of isolation operational amplifier chip U6 and one end of resistor R14 are both electrically connected to the other end of resistor R13. The other end of resistor R14 is grounded. One end of resistor R13 is electrically connected to the emitter of transistor Q2. The collector of transistor Q2 is connected to a +5V power supply.

[0061] In this embodiment, a second-order RC low-pass filter circuit is formed by resistors R8 and R9, capacitors C9 and C10 to convert the adjustment signal (PWM signal) into a DC voltage. Then, the voltage is amplified by the isolation operational amplifier chip U6 while isolating the circuits on both sides to reduce interference. Next, the power is output by the transistor Q2 to the VH terminal of the semiconductor gas sensor chip U5, thereby adjusting the heating voltage of the heating wire and keeping the heating power constant.

[0062] Furthermore, the heating power detection module 3 includes a voltage detection circuit 31 and a current detection circuit 32; the input terminals of the voltage detection circuit 31 and the current detection circuit 32 are both used as input terminals of the heating power detection module 3, and the output terminals of the voltage detection circuit 31 and the current detection circuit 32 are both used as output terminals of the heating power detection module 3.

[0063] The input terminal of the voltage detection circuit 31 is electrically connected to the VH terminal of the semiconductor gas sensor chip U5; the input terminal of the current detection circuit 32 is electrically connected to the GND terminal of the semiconductor gas sensor chip U5.

[0064] The voltage detection circuit 31 is used to detect the heating voltage of the heating wire of the semiconductor gas sensor chip U5;

[0065] The current detection circuit 32 is used to detect the heating current of the heating wire of the semiconductor gas sensor chip U5.

[0066] In this embodiment, since the heating power of the heating wire is calculated by detecting the heating voltage and heating current of the semiconductor gas sensor chip U5, the controller module 1 needs to detect the heating voltage and heating current of the heating wire of the semiconductor gas sensor chip U5 through the voltage detection circuit 31 and the current detection circuit 32 respectively.

[0067] Furthermore, the voltage detection circuit 31 includes resistors R11 and R12; one end of resistor R11 is used as the output terminal of the voltage detection circuit 31, and the other end of resistor R11 is used as the input terminal of the voltage detection circuit 31; one end of resistor R11 and one end of resistor R12 are electrically connected, and the other end of resistor R12 is grounded.

[0068] In this embodiment, the voltage detection circuit 31 consists of a voltage divider circuit composed of resistors R11 and R12 to detect the VH terminal voltage (heating voltage) of the semiconductor gas sensor chip U5.

[0069] Furthermore, the current detection circuit 32 includes a resistor R7; one end of the resistor R7 is used as the input or output terminal of the voltage detection circuit 31; the other end of the resistor R7 is grounded.

[0070] In this embodiment, the current detection circuit 32 uses resistor R7 as the sampling resistor to detect the GND terminal current (heating current) of the semiconductor gas sensor chip U5.

[0071] Furthermore, the heating power control system 6 also includes an isolation operational amplifier module 5; the output terminal of the sensor module 2 is electrically connected to the input terminal of the isolation operational amplifier module 5; the output terminal of the isolation operational amplifier module 5 is electrically connected to the detection terminal of the controller module 1.

[0072] The isolation operational amplifier module 5 is used to isolate and amplify the gas detection signal detected by the sensor module 2 and transmit it to the controller module 1.

[0073] During normal operation, sensor module 2 will feed back the gas detection signal representing the gas concentration to controller module 1. In this embodiment, heating power control system 6 can use isolation operational amplifier module 5 to receive the gas detection signal from sensor module 2, amplify it and transmit it to controller module 1, while isolating the circuits on both sides to reduce interference. Controller module 1 can verify whether the heating wire is in a constant power heating state by the stability of the gas detection signal transmission.

[0074] Furthermore, sensor module 2 also includes resistor R4; the VS terminal of semiconductor gas sensor chip U5 is used as the output terminal of sensor module 2;

[0075] One end of resistor R4 is electrically connected to the VS terminal of semiconductor gas sensor chip U5, and the other end of resistor R4 is connected to the VDD power supply.

[0076] The isolated operational amplifier module 5 includes a capacitor C8 and an isolated operational amplifier chip U4; the +IN terminal of the isolated operational amplifier chip U4 is used as the input terminal of the isolated operational amplifier module 5, and the OUT terminal of the isolated operational amplifier chip U4 is used as the output terminal of the isolated operational amplifier module 5.

[0077] The OUT and -IN terminals of the isolation operational amplifier chip U4 are electrically connected. The +VS terminal of the isolation operational amplifier chip U4 is electrically connected to one end of the capacitor C8, and the -VS terminal of the isolation operational amplifier chip U4 is electrically connected to the other end of the capacitor C8. One end of the capacitor C8 is connected to the VDD power supply, and the other end of the capacitor C8 is grounded.

[0078] In this embodiment, the isolation between sensor module 2 and controller module 1, as well as the transmission of the gas detection signal, are both achieved by the isolation operational amplifier chip U4 and its peripheral circuitry. Specifically, since the gas concentration detected by the semiconductor gas sensor is actually a gas detection signal derived from the change in sensor resistance during detection, and the isolation operational amplifier chip U4 can measure the voltage from the VS terminal of the semiconductor gas sensor chip U5 by voltage division, the change in sensor resistance can be determined based on the voltage. Therefore, after the VS terminal of the semiconductor gas sensor chip U5 is matched with the operational amplifier impedance of the isolation operational amplifier chip U4, it can output a gas detection signal that the controller module 1 (such as an MCU) can recognize, thus achieving isolation between the input and output signals.

[0079] Other configurations and operations of a semiconductor gas sensor with constant heating power according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0080] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A semiconductor gas sensor with constant heating power, characterized in that: It includes a sensor module and a heating power control system; the heating power detection terminal of the sensor module is electrically connected to the input terminal of the heating power control system, and the control terminal of the heating power control system is electrically connected to the heating wire power supply terminal of the sensor module. The heating power control system is used to detect the heating power of the heating wire of the sensor module, and adjust the power supply of the heating wire of the sensor module in reverse according to the change of the heating power. The heating power control system includes a controller module, a heating power detection module, and a constant power adjustment module; the input terminal of the heating power detection module is used as the input terminal of the heating power control system, and the output terminal of the constant power adjustment module is used as the control terminal of the heating power control system. The output terminal of the heating power detection module is electrically connected to the input terminal of the controller module, and the output terminal of the controller module is electrically connected to the input terminal of the constant power adjustment module. The heating power detection module is used to detect the heating power of the heating wire of the sensor module; The controller module is used to receive the heating power and generate an adjustment signal in reverse according to the change of the heating power; The constant power adjustment module is used to receive and adjust the power supply of the heating wire of the sensor module according to the adjustment signal; The adjustment signal is a PWM signal; The constant power adjustment module includes resistors R8 and R9, capacitors C9 and C10, an isolation operational amplifier chip U6, capacitor C11, resistors R13 and R14, and transistor Q2; one end of resistor R8 is used as the input terminal of the constant power adjustment module, and one end of resistor R13 is used as the output terminal of the constant power adjustment module. The other end of resistor R8 and one end of capacitor C9 are both electrically connected to one end of resistor R9. The other end of resistor R9 and capacitor C10 are both electrically connected to the +IN terminal of isolation operational amplifier chip U6. The other end of capacitor C9 and the other end of capacitor C10 are grounded. One end of capacitor C11 is electrically connected to the +VS terminal of isolation operational amplifier chip U6. The other end of capacitor C11 is electrically connected to the -VS terminal of isolation operational amplifier chip U6. One end of capacitor C11 is connected to a +5V power supply. The other end of capacitor C11 is grounded. The OUT terminal of isolation operational amplifier chip U6 is electrically connected to the base of transistor Q2. The -IN terminal of isolation operational amplifier chip U6 and one end of resistor R14 are both electrically connected to the other end of resistor R13. The other end of resistor R14 is grounded. One end of resistor R13 is electrically connected to the emitter of transistor Q2. The collector of transistor Q2 is connected to a +5V power supply.

2. A semiconductor gas sensor with constant heating power according to claim 1, characterized in that: The controller module is used to receive the heating power and the built-in constant heating power, then derive the power control quantity according to the PID algorithm, and generate an adjustment signal according to the power control quantity.

3. A semiconductor gas sensor with constant heating power according to claim 1, characterized in that: The sensor module includes a semiconductor gas sensor chip U5; both the VH terminal and the GND terminal of the semiconductor gas sensor chip U5 are used as heating power detection terminals of the sensor module, and the VH terminal of the semiconductor gas sensor chip U5 is used as the heating wire power supply terminal of the sensor module.

4. A semiconductor gas sensor with constant heating power according to claim 3, characterized in that: The heating power detection module includes a voltage detection circuit and a current detection circuit; the input terminal of the voltage detection circuit and the input terminal of the current detection circuit are both used as input terminals of the heating power detection module, and the output terminal of the voltage detection circuit and the output terminal of the current detection circuit are both used as output terminals of the heating power detection module. The input terminal of the voltage detection circuit is electrically connected to the VH terminal of the semiconductor gas sensor chip U; the input terminal of the current detection circuit is electrically connected to the GND terminal of the semiconductor gas sensor chip U. The voltage detection circuit is used to detect the heating voltage of the heating wire of the semiconductor gas sensor chip U; The current detection circuit is used to detect the heating current of the heating wire of the semiconductor gas sensor chip U.

5. A semiconductor gas sensor with constant heating power according to claim 4, characterized in that: The voltage detection circuit includes resistors R11 and R12; one end of resistor R11 is used as the output terminal of the voltage detection circuit, and the other end of resistor R11 is used as the input terminal of the voltage detection circuit; one end of resistor R11 and one end of resistor R12 are electrically connected, and the other end of resistor R12 is grounded.

6. A semiconductor gas sensor with constant heating power according to claim 4, characterized in that: The current detection circuit includes a resistor R7; one end of the resistor R7 is used as the input or output of the voltage detection circuit; the other end of the resistor R7 is grounded.

7. A semiconductor gas sensor with constant heating power according to claim 3, characterized in that: The heating power control system further includes an isolation operational amplifier module; the output terminal of the sensor module is electrically connected to the input terminal of the isolation operational amplifier module; the output terminal of the isolation operational amplifier module is electrically connected to the detection terminal of the controller module; The isolation operational amplifier module is used to isolate, amplify, and transmit the gas detection signal detected by the sensor module to the controller module.

8. A semiconductor gas sensor with constant heating power according to claim 7, characterized in that: The sensor module also includes a resistor R4; the VS terminal of the semiconductor gas sensor chip U5 is used as the output terminal of the sensor module. One end of the resistor R4 is electrically connected to the VS terminal of the semiconductor gas sensor chip U5, and the other end of the resistor R4 is connected to the VDD power supply. The isolated operational amplifier module includes a capacitor C8 and an isolated operational amplifier chip U4; the +IN terminal of the isolated operational amplifier chip U4 is used as the input terminal of the isolated operational amplifier module, and the OUT terminal of the isolated operational amplifier chip U4 is used as the output terminal of the isolated operational amplifier module. The OUT and -IN terminals of the isolation operational amplifier chip U4 are electrically connected. The +VS terminal of the isolation operational amplifier chip U4 is electrically connected to one end of the capacitor C8, and the -VS terminal of the isolation operational amplifier chip U4 is electrically connected to the other end of the capacitor C8. One end of the capacitor C8 is connected to the VDD power supply, and the other end of the capacitor C8 is grounded.

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