CN118130554A - Method and circuit for driving ammonia sensor - Google Patents

Abstract

The invention discloses a method for driving an ammonia sensor, which relates to the field of automobile electronic sensing detection, and comprises the following steps of: step 1, acquiring the actual temperature of an ammonia sensor; step 2, adjusting the actual temperature of the ammonia sensor to reach the set temperature of the ammonia sensor; step 3, acquiring voltage signals sent by gas sensitive materials for detecting the concentration of nitrogen oxides and oxygen on the ammonia sensor on the basis that the actual temperature of the ammonia sensor reaches the set temperature, and obtaining the concentration of the ammonia and the oxygen at present through operation treatment; the beneficial effects of the invention are as follows: according to the ammonia gas concentration detection method, the ammonia gas sensor is maintained at the set temperature, and ammonia gas concentration detection is performed, so that ammonia gas detection accuracy is ensured; the ammonia gas detector is relatively simple in structure, low in cost and capable of enhancing the possibility of wide application, simultaneously has sensitivity to ammonia gas with low concentration, and further improves the accuracy and practicability of ammonia gas detection.

Description

A method and circuit for driving an ammonia sensor

Technical Field

The present invention relates to the field of automotive electronic sensor detection, and in particular to a method and a circuit for driving an ammonia sensor.

Background technique

With the improvement of social living standards, the rapid increase in the number of cars has made people's travel more convenient, but it has also aggravated the problem of environmental pollution. Nitrogen oxides (NO _X ) are a harmful substance in automobile exhaust. At present, the most common method to eliminate nitrogen oxides is selective catalytic reduction (SCR). By spraying urea in the jet pipe, nitrogen oxides (NO _X ) can be converted into nitrogen and water. Usually, a nitrogen oxide sensor is installed at the outlet of SCR to detect the content of nitrogen oxides (NO _X ) after SCR, and the amount of urea sprayed is controlled and adjusted accordingly according to the test results. Although SCR can effectively solve the emission of harmful nitrogen oxides, if too much urea is sprayed, excess ammonia (NH ₃ ) will be produced. Ammonia is also a harmful gas, colorless, with a strong irritating odor and a toxic gas. Therefore, while eliminating nitrogen oxides, the emission problem of ammonia must also be solved. To solve this problem, the first thing to do is to detect the concentration of ammonia, so usually ammonia sensors are installed in vehicles equipped with SCR systems to detect the concentration of ammonia in real time.

The measurement principles of most existing ammonia sensors rely on components made of gas-sensitive materials to react with ammonia to detect the concentration of ammonia. These gas-sensitive materials generally have an optimum temperature that allows them to maintain their activity and sensitivity. When these gas-sensitive materials are at the optimum temperature, the detection accuracy is the highest. However, due to the influence of the environment or other factors, the temperature of the ammonia sensor may not always be maintained at the temperature that makes the gas-sensitive material most active, and the detection accuracy will be affected, which needs to be improved.

Summary of the invention

The object of the present invention is to provide a method and a circuit for driving an ammonia sensor to solve the problems raised in the above background technology.

To achieve the above object, the present invention provides the following technical solutions:

A method for driving an ammonia sensor comprises the following steps:

Step 1, obtaining the actual temperature of the ammonia sensor;

Step 2, adjusting the actual temperature of the ammonia sensor to reach the set temperature of the ammonia sensor;

Step 3, on the basis that the actual temperature of the ammonia sensor reaches the set temperature, the voltage signal emitted by the gas-sensitive material on the ammonia sensor for detecting the concentration of nitrogen oxides and oxygen is obtained, and the current concentration of ammonia and oxygen is obtained through calculation and processing.

As a further solution of the present invention: Step 1 specifically includes:

Step 11, collecting data of the internal resistance signal of the thermosensitive zirconium oxide on the ammonia sensor to obtain impedance data of the thermosensitive material;

Step 12: Based on the one-to-one correspondence between the impedance of the thermosensitive material and the temperature, the actual temperature of the ammonia sensor is obtained.

A circuit for driving an ammonia sensor, comprising:

A wide linear amplification circuit is used to receive the voltage signal generated by the gas-sensitive material on the ammonia sensor, amplify the voltage signal within a wide linear range, obtain the amplified signal, and output it to the signal conversion module;

A signal conversion module is used to convert the input amplified signal into a discrete digital signal and output it to the data processing module;

The data processing module is used to receive the digital signal, calculate the nitrogen oxide concentration (NOX value) and oxygen concentration (O2 value) after filtering, and finally obtain the ammonia (NH ₃ value) concentration;

The DFT integrated interface circuit is used to receive the impedance analog signal output by the ammonia sensor and output it to the AC impedance calculation module;

The AC impedance calculation module is used to analyze the frequency response characteristics of the thermistor on the ammonia sensor, measure the voltage and current signals in the AC circuit, and use the impedance calculation formula (Z=R+jX) to calculate the impedance value of the circuit, obtain the impedance value of the thermistor on the ammonia sensor, and detect the temperature of the ammonia sensor at this time;

The temperature control module is used to receive the actual temperature information of the ammonia sensor detected by the AC impedance calculation module, and output a temperature control signal to the heating drive circuit according to the difference between the set temperature and the actual temperature;

A heating drive circuit is used to heat and drive the ammonia sensor according to the received temperature control signal so that the actual temperature of the ammonia sensor matches the set temperature;

Communication module, used to transmit and receive information;

CAN communication module, used to build communication modules and control equipment;

The wide linear amplification circuit is connected to the signal conversion module, the signal conversion module is connected to the data processing module and the communication module, the data processing module is connected to the communication module, the DFT integrated interface circuit is connected to the AC impedance calculation module, the AC impedance calculation module is connected to the temperature control module and the communication module, the temperature control module is connected to the communication module and the heating drive circuit, the communication module is connected to the CAN communication module, and the CAN communication module is connected to the control device.

As a further solution of the present invention: the circuit for driving the ammonia sensor also includes a power supply module, which is used to convert the input voltage into 3.3V and 5V direct current to supply each module and each circuit.

As a further solution of the present invention: the control device includes an engine control unit ECU, which is used to achieve comprehensive monitoring, control and optimization of the driving state of the vehicle by connecting various sensors and a data bus.

As a further solution of the present invention: the DFT integrated circuit also includes a compensation resistor Rcal, which is used to compensate the impedance value with a certain deviation to a standard impedance value.

As a further solution of the present invention: the output temperature control signal output by the temperature control module is a PWM signal.

Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention ensures the accuracy of ammonia detection by maintaining the temperature of the ammonia sensor at a set temperature (within the optimal detection temperature range) and then performing ammonia concentration detection; and the structure is relatively simple and has a low cost, which enhances the possibility of its wide application. At the same time, it has sensitivity to lower concentrations of ammonia, further improving the accuracy and practicality of ammonia detection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a circuit for driving an ammonia sensor.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

The existing independent ammonia sensor control system architecture has some obvious defects, and most ammonia detection systems are integrated into a composite multi-gas sensor control system. This multi-gas sensor system architecture itself is relatively complex, and its structural complexity increases the difficulty of operation and maintenance, and the cost of the system is relatively high. In addition, different gases may interfere with each other, and the detection result of one gas may be affected by other gases, further reducing the reliability of the system. For the detection of ammonia content in motor vehicle exhaust, such a multi-gas sensor control system is not the most ideal choice. The detection of ammonia content in motor vehicle exhaust is crucial for environmental monitoring and emission control, so a more accurate, simple and focused control system is needed. The current system structure makes ammonia detection interfered by multiple gases, reducing the accuracy of detection, and due to the complexity of the system, the difficulty of operation and maintenance also increases. Therefore, it is urgent to design a more focused and efficient independent ammonia sensor control system architecture to solve the problems existing in the existing multi-gas sensor system and improve the reliability and accuracy of ammonia detection.

In the existing technology, Cheng Junna (Cheng Junna, Yang Ling, Hao Xin, etc. Design of ammonia detection system based on STM32 [J]. Science and Technology Information, 2021, 19(07): 60-63. DOI: 10.16661/j.cnki.1672-3791.2103-5042-5972) et al. proposed a gas detection module based on TDLAS and designed an ammonia detection system. This ammonia detection system based on STM32 has a maximum response time of 32 s and can detect trace ammonia. Since it uses an optical principle sensor, the cost is relatively high and requires professional operation, installation and maintenance.

In the patent of a nitrogen oxide sensor control system (CN201510942731.2[P].2015.12.16), a control system architecture for a NOX sensor is provided. Since the structure of the NOX sensor is also made of thermosensitive materials, it needs to be at a specific temperature to achieve the highest detection accuracy. The NOX sensor sends a voltage signal value to the nitrogen oxide sensor control system, and detects the NOX concentration and controls the NOX sensor temperature through signal conversion and data processing as well as adding some control algorithms.

The STM32-based ammonia sensor control system proposed by Cheng Junna et al. focuses on the control architecture of the optical ammonia sensor. This system uses optical principles for detection and measures the attenuation of light after passing through the ammonia medium to infer the concentration of ammonia. In contrast, a nitrogen oxide sensor control system detects ammonia based on the physical temperature change of semiconductor materials. The advantage of the optical ammonia sensor control system lies in its highly accurate measurement principle, which enables accurate monitoring of ammonia concentration through optical components. However, this is accompanied by a higher cost because the system requires the use of precision optical components and professional optical measurement equipment. In contrast, a nitrogen oxide sensor control system uses relatively low-cost semiconductor materials and conventional electronic measurement equipment. Although its detection principle is based on the temperature change of semiconductor materials, its cost-effectiveness and easy maintenance make it more attractive in practical applications. Overall, there is a trade-off between cost and performance for these two ammonia sensor control systems. The optical ammonia sensor control system focuses on high-precision detection, while the nitrogen oxide sensor control system focuses on economy and ease of use. Both have corresponding defects, so a method and system for driving an ammonia sensor with high detection accuracy and low cost is needed.

Referring to FIG. 1 , a method for driving an ammonia sensor includes the following steps:

Step 1, obtaining the actual temperature of the ammonia sensor;

Step 2, adjusting the actual temperature of the ammonia sensor to reach the set temperature of the ammonia sensor;

Step 3, on the basis that the actual temperature of the ammonia sensor reaches the set temperature, the voltage signal emitted by the gas-sensitive material on the ammonia sensor for detecting the concentration of nitrogen oxides and oxygen is obtained, and the current concentration of ammonia and oxygen is obtained through calculation and processing.

In this embodiment: please refer to Figure 1, step 1 specifically includes:

Step 11, collecting data of the internal resistance signal of the thermosensitive zirconium oxide on the ammonia sensor to obtain impedance data of the thermosensitive material;

Step 12: Based on the one-to-one correspondence between the impedance of the thermosensitive material and the temperature, the actual temperature of the ammonia sensor is obtained.

The DFT integrated interface circuit 4 is connected to the ammonia sensor, and it will collect data on the internal resistance impedance signal of the thermistor zirconium oxide on the ammonia sensor, and transmit the collected impedance signals to the AC impedance calculation module 5 of the microprocessor MCU for corresponding impedance calculation. Since there is a one-to-one correspondence between the impedance and temperature of the thermosensitive material, the temperature of the sensor at this time can be determined by the impedance value, and then the digital signal is transmitted to the temperature control module 7. The temperature control module 7 adds a certain control algorithm to control the temperature of the sensor within the optimal detection temperature range, and uses the PWM principle to change the duty cycle of the high level output to achieve temperature control of the ammonia sensor, so that the sensor is kept in a state with the best sensitivity, thereby effectively ensuring the detection accuracy. At the same time, the ammonia sensor at the optimal temperature receives the voltage signal emitted by the gas-sensitive material on the ammonia sensor for detecting the concentration of nitrogen oxides and oxygen through the wide linear amplifier circuit 1, and then transfers the voltage signal to the signal conversion module 2 to convert the analog signal into a digital signal, and sends the digital signal to the data processing module 3. The current concentrations of ammonia and oxygen are obtained by calculation and processing using principles such as the Nernst equation, and the concentration information is then sent to the engine control unit ECU12 in the form of a digital signal using CAN communication, providing information for subsequent control of ammonia emissions.

In this embodiment: please refer to FIG. 1 , a circuit for driving an ammonia sensor includes:

The wide linear amplifier circuit 1 is used to receive the voltage signal generated by the gas-sensitive material on the ammonia sensor, amplify the voltage signal within a wide linear range, obtain the amplified signal, and output it to the signal conversion module 2; the wide linear amplifier circuit 1 is an amplifier circuit with a large linear working range (i.e., margin). In the ammonia sensor control system, its main function is to receive the voltage signal generated by the gas-sensitive material on the ammonia sensor and amplify it within a wide linear range. Since the voltage signal generated by the gas-sensitive material may have different amplitudes under different working conditions, the use of the wide linear amplifier circuit 1 helps to ensure that accurate and reliable amplification results can be obtained under various working conditions without distortion or saturation. Such a circuit design helps to improve the system's adaptability to different ammonia concentration changes, thereby enhancing the stability and reliability of the ammonia sensor control system. The key role of the wide linear amplifier circuit 1 in this scenario is to receive two key voltage signals from the ammonia sensor: one is a voltage signal about the nitrogen concentration, and the other is a voltage signal about the oxygen concentration. Through this module, the two voltage signals are amplified, thereby solving the problem that the output signal of the ammonia sensor is weak and it is difficult to directly meet the input requirements of the single-chip microcomputer MCU.

The signal conversion module 2 is used to convert the input amplified signal into a discrete digital signal and output it to the data processing module 3; the main task of the signal conversion module 2 is to realize the conversion of analog signals to digital signals. In the ammonia sensor control system, the input of this module is the Nernst voltage signal of the gas-sensitive material detecting nitrogen and oxygen, and the output is to convert the continuous analog signal into a discrete digital signal through an analog-to-digital converter (ADC). This conversion process is critical because digital signals are easier to process and transmit, and are suitable for subsequent data analysis and processing steps. The converted digital signal is then transmitted to the data processing module 3, which uses the Nernst equation and other principles for calculation and processing to obtain the concentration information of ammonia and oxygen. The design and performance of the signal conversion module 2 directly affect the sensitivity and accuracy of the system to changes in gas concentration. Therefore, a reasonable and efficient signal conversion module 2 is a key component in the ammonia sensor control system.

The data processing module 3 is used to receive digital signals, calculate the nitrogen oxide concentration (NOX value) and oxygen concentration (O2 value) after filtering, and finally obtain the ammonia (NH ₃ value) concentration; its primary task is to receive and process the digital signals converted by the signal conversion module. This module has many key functions, including accurate data acquisition and conversion of the digital signals output by the ammonia sensor to ensure the reliability of the signal. During the data processing process, the system will apply filtering technology to filter the collected signals to eliminate potential noise and interference, thereby improving the accuracy of the data and the stability of the system. In addition, the data processing module 3 also transmits data with other devices through the communication interface to realize information sharing with external systems, or store data locally. When analyzing the received data, the module can calculate the nitrogen oxide concentration and oxygen concentration, and finally obtain the ammonia concentration. The processed data is properly stored in the memory for subsequent retrieval, analysis or historical record. In addition, the data processing module 3 also has the ability to receive and process external data, making it more comprehensive. With this complete set of functions, the data processing module 3 plays a core role in the entire system, ensuring that the ammonia sensor control system can provide highly accurate and stable gas concentration information, thus providing a reliable basis for environmental monitoring and control.

The DFT integrated interface circuit 4 is used to receive the impedance analog signal output by the ammonia sensor and output it to the AC impedance calculation module 5; the DFT integrated interface circuit 4 is used to process the AC signal, and its main task is to receive the impedance analog signal output by the ammonia sensor and process it using the corresponding relationship between AC impedance and temperature. Through this processing process, the DFT integrated interface circuit 4 can accurately detect the current temperature information of the ammonia sensor. In operation, the module is connected to the ammonia sensor, receives the impedance analog signal, and performs a discrete Fourier transform (DFT) through a specific circuit design to convert the signal into a frequency domain representation. By analyzing the frequency domain information, the relationship between the impedance signal and the temperature can be obtained, thereby deducing the current temperature of the ammonia sensor. Finally, the DFT integrated interface circuit 4 sends the processed temperature information to the AC impedance calculation module 5 to provide accurate input for subsequent impedance calculations. Through this process, the system can obtain the temperature information of the ammonia sensor in real time, providing key basic data for temperature control and gas concentration calculation.

The AC impedance calculation module 5 is used to analyze the frequency response characteristics of the thermistor (specifically, the internal resistance of zirconium oxide in the thermistor) on the ammonia sensor, measure the voltage and current signals in the AC circuit, and use the impedance calculation formula (Z=R+jX) to calculate the impedance value of the circuit, obtain the impedance value of the thermistor on the ammonia sensor, and detect the temperature of the ammonia sensor at this time; wherein R is resistance, X is reactance, and j is an imaginary unit.

The temperature control module 7 is used to receive the actual temperature information of the ammonia sensor detected by the AC impedance calculation module 5, and output a temperature control signal to the heating drive circuit 10 according to the difference between the set temperature and the actual temperature; the temperature control module 7 is composed of a temperature sensor (obtained by AC impedance calculation), a controller (with a temperature control algorithm) and an actuator (heating drive circuit 10). The AC impedance module detects the temperature, and the controller controls the actuator to work according to the difference between the set temperature and the actual temperature to control the heating drive circuit 10 to adjust the temperature. The main function of this module is to know that there is a certain correspondence between the impedance value and temperature of the ammonia sensor, input the ammonia sensor impedance signal to the data processing module 3 for calculation and processing, and obtain a temperature deviation signal value, add the control algorithm of Active Disturbance Rejective Control to the module, control its temperature, and correct the deviation. And here, the PWM principle can be used, because the digital signal transmitted to the temperature control module 7 is sent in the form of high and low levels, and the duty cycle of each cycle of the voltage signal can be adjusted to achieve the control of its output voltage and temperature.

The heating drive circuit 10 is used to heat and drive the ammonia sensor according to the received temperature control signal so that the actual temperature of the ammonia sensor matches the set temperature; the heating drive circuit 10 plays a vital role in the ammonia sensor system. Its working principle mainly includes receiving the temperature control signal sent by the temperature control module 7 and heating and driving the ammonia sensor through actual physical control means. First, the circuit receives a precise temperature control signal from the temperature control module 7. This signal is generated according to the system's demand for the sensor temperature, taking into account the preset temperature range and control algorithm. Secondly, once the temperature control signal is received, the heating drive circuit 10 implements heating of the ammonia sensor through physical control means. This may include controlling the heating element or adjusting the current to ensure that the sensor always remains within the most suitable operating temperature range. This process helps to improve the sensitivity and performance of the sensor. At the same time, the heating drive circuit 10 is usually equipped with a temperature sensor or other feedback mechanism for monitoring the temperature state of the actual sensor. This temperature feedback mechanism realizes closed-loop control, ensuring that the sensor can maintain the optimal operating temperature under different environmental conditions, thereby improving the accuracy and reliability of detection. In summary, the heating drive circuit 10 provides effective temperature management for the ammonia sensor system through its controllable heating mechanism, ensuring that the sensor can maintain an optimal state under various working conditions, thereby improving the performance and stability of the entire system.

The communication module 6 is used to transmit and receive information. This is the internal communication module of the entire ammonia sensor detection system and the module connected to the outside. It is mainly used for communication between various internal modules, such as transmitting the impedance information of the ammonia sensor to the temperature control module 7 and transmitting the digital signal obtained by the data processing module 3, such as ammonia, oxygen concentration and other information, to the engine control unit (ECU12) by means of the CAN communication module 8, and then jointly adjusting the emission of ammonia with other modules.

The CAN communication module 8 is used to establish the communication between the communication module 6 and the control device; it adopts the Controller Area Network (CAN) protocol to provide the system with an efficient and reliable information transmission and communication mechanism. Its main tasks include key functions such as data transmission, control instruction transmission, network communication and fault diagnosis. The main function of this module is to transmit the concentration of nitrogen oxides, _O2 and _NH3 to other system components, such as the engine electronic control unit (ECU12) through the CAN bus.

The wide linear amplifier circuit 1 is connected to the signal conversion module 2, the signal conversion module 2 is connected to the data processing module 3 and the communication module 6, the data processing module 3 is connected to the communication module 6, the DFT integrated interface circuit 4 is connected to the AC impedance calculation module 5, the AC impedance calculation module 5 is connected to the temperature control module 7 and the communication module 6, the temperature control module 7 is connected to the communication module 6 and the heating drive circuit 10, the communication module 6 is connected to the CAN communication module 8, and the CAN communication module 8 is connected to the control device.

In this embodiment: please refer to FIG. 1 , the circuit for driving the ammonia sensor further includes a power supply module 9 for converting the input voltage into 3.3V and 5V direct current to supply each module and each circuit.

The power module 9 is a key component in the ammonia sensor system. Its input voltage is +12V, and its output provides the +3.3V and +5V voltages required inside the system to meet the power requirements of each component. The main functions include voltage conversion, power distribution, stability and reliability guarantee, and efficiency optimization. First, the power module 9 converts the input +12V voltage into the +3.3V and +5V voltages required inside the system through precise circuit design and voltage conversion technology. This conversion ensures that each component in the system can operate normally within the appropriate voltage range and ensures the stability of the system. Secondly, the power module 9 is responsible for effectively distributing the generated +3.3V and +5V voltages to various components in the ammonia sensor system, including the DFT integrated interface circuit 4, the AC impedance calculation module 5, the CAN communication module 8, the data processing module 3, etc. This power distribution mechanism ensures that each component can obtain stable and reliable power support. To ensure the robustness of the system, the power module 9 adopts designs such as voltage stabilizers and overload protection circuits to prevent the output voltage fluctuations from having adverse effects on the system, and cuts off the power supply when the current is abnormal, thereby protecting the system from damage. Finally, the power module 9 improves the energy efficiency of the entire system and reduces energy waste through efficiency optimization technology during the power conversion process. This provides basic support for the reliability and long-term stable operation of the ammonia sensor system. In summary, the power module 9 provides stable and reliable power support for the entire ammonia sensor system through its sophisticated design and versatility.

In this embodiment: please refer to FIG. 1 , the control device includes an engine control unit ECU 12, which is used to achieve comprehensive monitoring, control and optimization of the vehicle's driving state by connecting various sensors and data buses.

The engine control unit ECU12, by connecting various sensors and data buses, realizes comprehensive monitoring, control and optimization of the vehicle's driving status, and is also responsible for realizing various functions. ECU12 first collects the vehicle's operating status and environmental data in real time by connecting to various sensors on the vehicle, such as ammonia sensors, speed sensors, temperature sensors, etc. Subsequently, ECU12 processes and analyzes these data in real time, using advanced algorithms and logical reasoning to accurately grasp the vehicle status and identify the driver's operating intentions. Based on the processed information, ECU12 makes intelligent decisions to determine the optimal engine operating parameters, vehicle control strategies, etc., to meet the requirements of performance, fuel efficiency, emissions, etc. By connecting to actuators, such as engine actuators, brake actuators, etc., ECU12 converts the formulated control strategies into specific actions to achieve precise control of various systems of the vehicle.

In this embodiment: please refer to FIG. 1 , the DFT integrated circuit further includes a compensation resistor Rcal11 for compensating an impedance value with a certain deviation to a standard impedance value.

As a compensation resistor of the DFT integrated interface circuit, for the gas-sensitive material in the ammonia sensor, there is an optimum temperature corresponding to a standard impedance value. However, due to the differences between the core materials and some other physical influences, the impedance value corresponding to the optimum temperature may not be the standard impedance value, and there is a positive or negative deviation. Therefore, we add a function to the system that can compensate the impedance value with a certain deviation to the standard impedance value by adding an Rcal11 compensation resistor. After completing the temperature calibration, the subsequent impedance measurement will correspond to a correct temperature value.

In this embodiment: please refer to FIG. 1 , the output temperature control signal output by the temperature control module 7 is a PWM signal.

Because the digital signal transmitted to the temperature control module 7 is sent in the form of high and low levels, the duty cycle of each cycle of the voltage signal can be adjusted to achieve control of its output voltage and temperature.

The working principle of the present invention is as follows: the wide linear amplifier circuit 1 is used to receive the voltage signal generated by the gas-sensitive material on the ammonia sensor, and amplify the voltage signal within a wide linear range to obtain the amplified signal, and output it to the signal conversion module 2; the signal conversion module 2 is used to convert the input amplified signal into a discrete digital signal, and output it to the data processing module 3; the data processing module 3 is used to receive the digital signal, calculate the nitrogen oxide concentration (NOX value) and the oxygen concentration (O2 value) after filtering, and finally obtain the ammonia (NH ₃ value) concentration; the DFT integrated interface circuit 4 is used to receive the impedance analog signal output by the ammonia sensor, and output it to the AC impedance calculation module 5; the AC impedance calculation module 5 is used to analyze the frequency response characteristics of the thermistor on the ammonia sensor, measure the voltage and current signals in the AC circuit, and use the impedance calculation formula (Z=R+jX) to calculate the impedance value of the circuit, obtain the impedance value of the thermistor on the ammonia sensor, and detect the temperature of the ammonia sensor at this time; the temperature control module 7 is used to receive the actual temperature information of the ammonia sensor detected by the AC impedance calculation module 5, and output a temperature control signal to the heating drive circuit 10 according to the difference between the set temperature and the actual temperature; the heating drive circuit 10 is used to heat and drive the ammonia sensor according to the received temperature control signal, so that the actual temperature of the ammonia sensor matches the set temperature; the communication module 6 is used to transmit and receive information; the CAN communication module 8 is used to establish communication between the communication module 6 and the control device.

It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims (7)

1. A method for driving an ammonia sensor, characterized in that the method for driving an ammonia sensor comprises the steps of:

Step 1, acquiring the actual temperature of an ammonia sensor;

Step 2, adjusting the actual temperature of the ammonia sensor to reach the set temperature of the ammonia sensor;

And step 3, acquiring voltage signals sent by gas sensitive materials for detecting the concentration of nitrogen oxides and oxygen on the ammonia sensor on the basis that the actual temperature of the ammonia sensor reaches the set temperature, and obtaining the concentration of the ammonia and the oxygen at present through operation treatment.

2. The method for driving an ammonia gas sensor according to claim 1, wherein step 1 specifically comprises:

Step 11, acquiring data of a thermosensitive zirconia internal resistance signal on an ammonia sensor to obtain resistance data of a thermosensitive material;

And step 12, acquiring the actual temperature of the ammonia sensor based on the one-to-one correspondence between the impedance of the thermosensitive material and the temperature.

3. A circuit for driving an ammonia sensor, the circuit for driving an ammonia sensor comprising:

the wide linear amplifying circuit is used for receiving the voltage signal generated by the gas sensitive material on the ammonia sensor, amplifying the voltage signal in a wide linear range, obtaining an amplified signal and outputting the amplified signal to the signal conversion module;

The signal conversion module is used for converting the input amplified signal into a discrete digital signal and outputting the discrete digital signal to the data processing module;

The data processing module is used for receiving the digital signals, calculating the concentration of nitrogen oxides and the concentration of oxygen after filtering treatment, and finally obtaining the concentration of ammonia;

The DFT integrated interface circuit is used for receiving the impedance analog signal output by the ammonia sensor and outputting the impedance analog signal to the alternating current impedance calculation module;

The alternating current impedance calculation module is used for analyzing the frequency response characteristic of the thermistor on the ammonia sensor, measuring voltage and current signals in the alternating current circuit, calculating the impedance value of the circuit by utilizing an impedance calculation formula, obtaining the impedance value of the thermistor on the ammonia sensor, and detecting the temperature of the ammonia sensor at the moment;

the temperature control module is used for receiving the actual temperature information of the ammonia sensor detected by the alternating current impedance calculation module and outputting a temperature control signal to the heating drive circuit according to the difference between the set temperature and the actual temperature;

The heating driving circuit is used for heating and driving the ammonia sensor according to the received temperature control signal so as to enable the actual temperature of the ammonia sensor to be matched with the set temperature;

the communication module is used for transmitting and receiving information;

The CAN communication module is used for constructing communication between the communication module and the control equipment;

The wide linear amplifying circuit is connected with the signal conversion module, the signal conversion module is connected with the data processing module and the communication module, the data processing module is connected with the communication module, the DFT integrated interface circuit is connected with the alternating current impedance calculation module, the alternating current impedance calculation module is connected with the temperature control module and the communication module, the temperature control module is connected with the communication module and the heating driving circuit, the communication module is connected with the CAN communication module, and the CAN communication module is connected with the control equipment.

4. A circuit for driving an ammonia gas sensor as defined in claim 3 further comprising a power module for converting the input voltage into 3.3V and 5V direct current, and supplying each module and each circuit.

5. A circuit for driving an ammonia gas sensor according to claim 3 wherein the control device comprises an engine control unit ECU for effecting comprehensive monitoring, control and optimization of the vehicle driving conditions by connecting various sensors and data buses.

6. A circuit for driving an ammonia gas sensor as defined in claim 3 wherein the DFT integrated circuit further comprises a compensation resistor Rcal for compensating the deviated impedance value to a standard impedance value.

7. A circuit for driving an ammonia gas sensor as defined in claim 3 wherein the output temperature control signal output by the temperature control module is a PWM signal.