Fault detection device of dual-electrode electrochemical sensor

Abstract

The utility model discloses a fault detection device of a dual-electrode electrochemical sensor, which comprises a plurality of signal detection units connected with a control unit, and a power conversion unit supplies power to the control unit and the signal detection units. The signal detection unit comprises a sensor signal branch which is connected with the signal input end of the control unit and outputs a sensor detection signal; the self-checking control branch circuit is connected with the sensor signal branch circuit and is used for receiving a self-checking signal of the control unit to start sensor detection or closing; and the reference voltage branch provides reference voltage for the sensor signal branch. According to the utility model, the dual-electrode electrochemical sensor is connected into the fault detection device in a plugging manner, fault detection and rapid determination of one or more electrochemical sensors can be completed within several seconds, the number of detection channels can be freely increased or reduced, and simultaneous detection of different types of dual-electrode electrochemical sensors is supported.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrochemical sensor technical field especially is involved in a kind of fault detection device of double electrode electrochemical sensor. BACKGROUND

[0002] Electrochemical sensor is more and more widely used in environmental protection monitoring, industrial production safety, medical health, biochemical analysis and other fields due to its characteristics of portability, low cost, simple operation, good selectivity and high sensitivity. There are many types of electrochemical sensors on the market, such as formaldehyde sensors and carbon monoxide sensors. There is almost a corresponding detection sensor for each toxic and harmful gas. In the actual application environment, the detection sensor will be in contact with clean air most of the time, and the output signal value will be within the safe range and tend to be stable. When toxic and harmful gases are detected, there will be a large change. If the sensor fails during long-term operation, its function will be invalid, and the signal output by the sensor will still be maintained within the normal value, and there will be no change in the signal even if it is in contact with toxic and harmful gases, which leads to functional failure but cannot be discovered in time, and people's health and safety will be affected or threatened. Therefore, it is necessary to regularly detect the function of the sensor to detect whether it has a fault. In addition, single sensor may fail after long-term storage, so it is necessary to screen abnormal products in time and analyze the specific problem. However, in the existing detection technology, high-precision detection equipment is often used to measure the voltage, current and resistance of the electrochemical sensor, but the measured value is constantly changing, which is difficult to determine, and only one product can be measured at a time, which is low in efficiency.

[0003] A sensor fault detection circuit capable of self-detection is disclosed in Chinese patent document CN209894206U, published on January 3, 2020. The fault detection signal output end of the sensor is connected to a protection circuit and an isolation output circuit. The fault output signal collected by the isolation output circuit is transmitted to the single-chip microcomputer for monitoring and analysis. The protection circuit collects the fault output signal through the optocoupler switching circuit and the sampling comparison circuit, and drives the relay driving circuit to control the on-off of the power supply of the sensor detection circuit to realize automatic protection action for the fault signal. The self-detection circuit can detect whether the sensor fault detection circuit itself has a problem, and can perform self-detection on multiple different sensor fault detection circuits to avoid the problem that the sensor fault detection circuit itself cannot normally collect the fault output signal due to internal failure, resulting in failure to analyze the fault. This technology is for the sensor fault detection circuit, not the sensor itself. There is a lack of efficient, low-cost and strong expansion fault detection technology for double electrode electrochemical sensors. SUMMARY

[0004] This invention aims to overcome the problems in existing technologies that often use high-precision detection equipment to measure the voltage, current, and resistance of electrochemical sensors, but the measured values ​​are constantly changing and difficult to judge, and can only measure a single product at a time, resulting in low efficiency. This invention provides a fault detection device for a dual-electrode electrochemical sensor.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A fault detection device for a dual-electrode electrochemical sensor includes several signal detection units connected to a control unit, wherein the control unit and the signal detection units are powered by a power conversion unit; the signal detection units include:

[0007] The sensor signal branch is connected to the signal input terminal of the control unit and outputs the sensor detection signal.

[0008] The self-test control branch is connected to the sensor signal branch and receives the self-test signal from the control unit to start sensor detection or shut down; the reference voltage branch provides a reference voltage to the sensor signal branch.

[0009] This invention connects a dual-electrode electrochemical sensor to a fault detection device via a plug-in method, enabling fault detection of one or more electrochemical sensors within seconds. The detection results can be displayed intuitively via LEDs or similar displays, and can also be output and displayed. It is low-cost, has a simple circuit, high reliability, requires no soldering, does not affect the performance of the electrochemical sensor itself, and has low requirements for the controller. It is highly expandable and compatible, capable of single-channel detection, easy to carry, and allows for flexible addition or reduction of detection channels. It supports simultaneous detection of different types of dual-electrode electrochemical sensors, such as formaldehyde and carbon monoxide sensors.

[0010] Preferably, the control unit includes a chip U2, and the voltage input terminal of the chip U2 is connected to the voltage output terminal of the power conversion unit.

[0011] Several lighting control terminals of chip U2 are connected to an LED light branch, and each LED light branch contains one of three colors of LED lights; the three different colored LED light branches form a signal input terminal of a corresponding control unit.

[0012] Preferably, the sensor signal branch includes a sensor socket U4, the first pole of which is connected to the inverting input terminal of amplifier U3-A, and is connected to the output terminal of U3-A through a parallel branch of capacitor and resistor; the output terminal of U3-A is connected to the signal input terminal of the control unit.

[0013] The second terminal of U4 is connected to the non-inverting input terminal of U3-A through resistor R13; transistor Q2 is connected between the first and second terminals of U4, and the gate of Q2 is powered by the power output terminal of the power conversion unit.

[0014] Preferably, the self-test control branch includes a self-test signal terminal ST connected to the chip U2 of the control unit. The self-test signal terminal ST is connected to one end of resistor R15 and one end of resistor R14 respectively. The other end of resistor R15 is connected to the second pole of U4, and the other end of resistor R14 is connected to the gate of transistor Q1. Transistor Q1 is connected across resistor R13.

[0015] Preferably, the reference voltage branch includes amplifier U3-B, the output of which is connected to the inverting input of U3-B and the non-inverting input of U3-A respectively; the non-inverting input of U3-B is grounded through resistor R4 and connected to the power output of the power conversion unit through resistor R3.

[0016] Preferably, the output of the sensor signal branch is connected to the signal input of the control unit through a filter branch; the output of U3-A is connected to one end of resistor R17, and the other end of resistor R17 is grounded through capacitor C9 and connected to the signal input of the control unit.

[0017] Preferably, the power conversion unit includes an interface P1, the external power supply terminal of the interface P1 is connected to an external power supply, and is connected to the voltage input terminal of the conversion chip U1 through a switch branch. The ground terminal of U1 is connected to the ground terminal of the interface P1 and grounded. A diode TVS1 is connected between the external power supply terminal and the ground terminal of the interface P1. The voltage output terminal of U1 serves as the power output terminal of the power conversion unit.

[0018] Preferably, the interface P1 further includes a first signal terminal and a second signal terminal. The first signal terminal is connected to the data receiving terminal of the chip U2 in the control unit, and the second signal terminal is connected to the data transmitting terminal of the chip U2 in the control unit. A diode TVS2 is connected between the first signal terminal and the second signal terminal.

[0019] This invention has the following advantages: By plugging in the dual-electrode electrochemical sensor into the fault detection device, fault detection of one or more electrochemical sensors can be completed within seconds, allowing for rapid judgment. The detection results can be displayed intuitively and easily via LEDs, or the detection data can be output and displayed. It is low in cost, has a simple circuit, and high reliability. It does not require soldering, does not affect the performance of the electrochemical sensor itself, and has low requirements for the controller. It is highly expandable and compatible, can perform single-channel detection, is easy to carry, and can freely increase or decrease the number of detection channels. It supports simultaneous detection of different types of dual-electrode electrochemical sensors, i.e., it supports simultaneous detection of formaldehyde and carbon monoxide sensors. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the fault detection device for the dual-electrode electrochemical sensor of this utility model.

[0021] Figure 2 This is a circuit diagram of the first signal detection unit in an embodiment of this utility model.

[0022] Figure 3 This is a circuit diagram of another signal detection unit in an embodiment of this utility model.

[0023] Figure 4 This is the circuit diagram of the control unit in this utility model.

[0024] Figure 5 This is a circuit diagram of the power conversion unit in this utility model.

[0025] In the diagram: 1. Control unit; 2. Power conversion unit; 3. First signal detection unit; 4. Second signal detection unit; 5. nth signal detection unit; 31. Sensor signal branch; 32. Self-test control branch; 33. Reference voltage branch. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, a fault detection device for a dual-electrode electrochemical sensor includes several signal detection units connected to a control unit 1. The control unit 1 and the signal detection units are powered by a power conversion unit 2. Each signal detection unit includes a sensor signal branch 31, which is connected to the signal input terminal of the control unit 1 and outputs a sensor detection signal.

[0028] The self-test control branch 32 is connected to the sensor signal branch 31 and receives the self-test signal from the control unit 1 to start sensor detection or shut it down.

[0029] The reference voltage branch 33 provides a reference voltage to the sensor signal branch 31.

[0030] It should be noted that this utility model uses a plug-in method to connect the dual-electrode electrochemical sensor to the fault detection device, which can complete the fault detection of one or more electrochemical sensors within a few seconds, quickly determine the fault, and the detection results can be displayed through LEDs, etc., which are intuitive and easy to understand. The detection data results can also be output and displayed. It has low cost, simple circuit, and high reliability. It does not require soldering, does not affect the performance of the electrochemical sensor itself, and has low requirements for the controller. It has strong expandability and high compatibility. It can perform single-channel detection, is easy to carry, and can freely increase or decrease the number of detection channels. It supports the simultaneous detection of different types of dual-electrode electrochemical sensors, that is, it supports the simultaneous detection of formaldehyde sensors and carbon monoxide sensors.

[0031] It is worth noting that the control unit performs detection and control of the dual-electrode electrochemical sensor. After outputting a self-test signal to the signal detection unit, the signal detection unit detects the sensor and returns the received sensor detection signal to the control unit. The control unit determines the specific state of the dual-electrode electrochemical sensor by comparing a preset fluctuation signal with the received sensor detection signal. The sensor state is divided into three types: open circuit, short circuit, and no fault. Each state has its typical fluctuation signal. In this invention, the control unit simply compares the sensor detection signal with the fluctuation signals of the three typical sensor states to determine the sensor state. This can be achieved using existing technology and does not involve any improvement in the method.

[0032] Specifically, control unit 1 is powered by power conversion unit 2, and data transmission occurs between control unit 1 and power conversion unit 2. Detection data from control unit 1 is output to the outside through the signal terminal of power conversion unit 2. This invention supports simultaneous detection by multiple dual-electrode electrochemical sensors. Limited by the number of ADC channels in the control chip of control unit 1, for example, n ADC channels support the simultaneous detection of n sensors. Therefore, the first signal detection unit 3 is interconnected with control unit 1 and powered by power conversion unit 2, the second signal detection unit 4 is interconnected with control unit 1 and powered by power conversion unit 2, and so on, with the nth signal detection unit 5 interconnected with control unit 1 and powered by power conversion unit 2.

[0033] The specific structure of each signal detection unit is the same; therefore, the first signal detection unit will be used as an example for explanation. The first signal detection unit includes a sensor signal branch 31, a self-test control branch 32, and a reference voltage branch 33. The reference voltage branch 33 is powered by the power conversion unit 2 and forms a stable reference voltage to provide to the sensor signal branch 31. After receiving the self-test signal from the control unit 1, the self-test control branch 32 acts as a switch to control the sensor signal branch 31 to begin sensor detection. The sensor signal branch 31 is powered by the power conversion unit 2 and, after sensor detection, inputs the sensor detection signal to the control unit 1.

[0034] As a specific embodiment, the signal detection unit includes a sensor signal branch, a self-test control branch, and a reference voltage branch, as follows: Figure 2 The first signal detection unit shown is used as an example for explanation.

[0035] The sensor signal branch includes sensor socket U4. The first terminal of sensor socket U4 is connected to the inverting input terminal of amplifier U3-A, and is connected to the output terminal of amplifier U3-A through a parallel branch of capacitor C10 and resistor R6. The output terminal of amplifier U3-A is connected to the signal input terminal ADC0 of the control unit through the ADC0 terminal. The second terminal of sensor socket U4 is connected to the non-inverting input terminal of U3-A through resistor R13. Transistor Q2 is connected between the first and second terminals of sensor socket U4. The gate of transistor Q2 is powered by the power output terminal of the power conversion unit and is connected to +3V voltage through resistor R5.

[0036] It should be noted that this utility model is used for detecting a dual-electrode electrochemical sensor. In the sensor signal branch, a sensor socket U4 is used for plug-and-play connection with the sensor, allowing for rapid sensor status determination and subsequent updates to other sensors requiring detection, thus improving detection efficiency. The first and second terminals of the sensor socket U4 correspond to the two electrodes of the dual-electrode electrochemical sensor, respectively. Transistor Q2 is a P-channel JFET. The function of Q2 is to maintain the sensor in a short-circuit state when the circuit is not energized and the gate is not voltaged, preventing sensor polarization and reducing the sensor's power-on warm-up time.

[0037] The self-test control branch includes a self-test signal terminal ST connected to the chip U2 of the control unit. The self-test signal terminal ST is connected to one end of resistor R15 and one end of resistor R14 respectively. The other end of resistor R15 is connected to the second terminal of U4, and the other end of resistor R14 is connected to the gate of transistor Q1. Transistor Q1 is connected across resistor R13 (that is, connected to the second terminal of sensor socket U4 and the non-inverting input terminal of amplifier U3-A).

[0038] It should be noted that transistor Q1 also uses a P-channel JFET. The self-test signal ST is high by default during normal sensor operation, at which point transistor Q1 is turned on, and resistor R13 is short-circuited. Under these conditions, the sensor operates normally without performing any detection. When detection is required, the level of the self-test signal ST is pulled low for a period of time, causing transistor Q1 to turn off. Resistor R13 is then connected in the circuit, enabling the entire sensor signal branch to operate and perform sensor detection, outputting a sensor detection signal.

[0039] The reference voltage branch includes amplifier U3-B. The output of amplifier U3-B is connected to the inverting input of amplifier U3-B and the non-inverting input of amplifier U3-A, respectively. The non-inverting input of amplifier U3-B is grounded through resistor R4 and connected to the +3V power output of the power conversion unit through resistor R3.

[0040] It should be noted that amplifier U3-B, resistor R3, and resistor R4 form a reference voltage follower, which outputs a stable reference voltage to the non-inverting input of amplifier U3-A. This can pull up the zero-point voltage of the sensor signal to the reference voltage, ensuring that the sensor can work normally, while avoiding excessive signal fluctuations in clean air or low concentration environments.

[0041] Furthermore, the output of the sensor signal branch is connected to the signal input of the control unit through a filter branch to filter out signal noise and interference. That is, the output of amplifier U3-A is connected to one end of resistor R17, the other end of resistor R17 is grounded through capacitor C9, and connected to the signal input of the control unit through ADC0.

[0042] As a specific embodiment, the control unit includes a chip U2, and the voltage input terminal of the chip U2 is connected to the voltage output terminal of the power conversion unit;

[0043] Several lighting control terminals of chip U2 are connected to an LED light branch, and each LED light branch contains one of three colors of LED lights; the three different colored LED light branches form a signal input terminal of a corresponding control unit.

[0044] It should be noted that this invention can use LEDs of different colors to display different sensor states. Since sensor states are mainly categorized into three types—open circuit, short circuit, and no fault—the LED colors also correspond to these states. In the control unit's chip U2, one signal input terminal corresponds to a set of three LED branches with different colors. Therefore, after the corresponding sensor detection signal is input, the sensor's state can be determined by the illumination of a specific color LED from one of the three branches.

[0045] Specifically, such as Figure 4The control unit shown is a circuit diagram that can simultaneously connect to two ADC channels. Its first channel is connected to the first signal detection unit via ADC0, and its second channel is connected to the second signal detection unit via ADC1 (the circuit diagram of the second signal detection unit is shown below). Figure 3 As shown, the circuit structures of the first signal detection unit and the second signal detection unit are the same, so they will not be described in detail.

[0046] The control unit includes a control chip U2, model CX32L003F8P6. The voltage input terminal VDD of chip U2 is connected to the +3V voltage output terminal from the power conversion unit, and is grounded through capacitor C7. The self-test signal terminal ST of chip U2 is simultaneously connected to the self-test signal terminals ST of two signal detection units. Therefore, the self-test signal emitted from chip U2 in the control unit can simultaneously detect sensors connected to multiple signal detection units. Additionally, the switching terminal of chip U2 is connected to switch S1; closing switch S1 controls chip U2 to emit the self-test signal.

[0047] In this embodiment, since chip U2 connects to two signal detection units, chip U2 will connect to two sets of six LED light branches, with two branches for each of the three different types of colored LEDs. Specifically, the first LED light branch is for the green LED D7, the second for the yellow LED D1, and the third for the red LED D2. These three branches form a group corresponding to the first signal input terminal ADC0, with each color corresponding to a different sensor state for display. Similarly, the fourth LED light branch is for the green LED D3, the fifth for the yellow LED D4, and the sixth for the red LED D5. These three branches form a group corresponding to the first signal input terminal ADC1.

[0048] Chip U2 also includes a reset terminal NRST, which is connected to the +3V voltage output terminal of the power conversion unit via resistor R1 and grounded via capacitor C6. Simultaneously, chip U2's data receiving terminal RX is connected to the data transmitting terminal (the first signal terminal of interface P1) of the power conversion unit, and its data transmitting terminal TX is connected to the data receiving terminal (the second signal terminal of interface P1) of the power conversion unit. Sensor detection result data is output through RX and TX.

[0049] As a specific example, such as Figure 5As shown, the power conversion unit includes interface P1. The external power supply terminal of interface P1 is connected to an external power supply +VIN, and is connected to the voltage input terminal of conversion chip U1 through a switch branch. The ground terminal of conversion chip U1 is connected to and grounded through the ground terminal of interface P1. A diode TVS1 is connected between the external power supply terminal and the ground terminal of interface P1. Capacitors C3 and C4 are connected in parallel across the two ends of diode TVS1. The voltage output terminal VOUT of U1 serves as the power output terminal of the power conversion unit, providing a +3V voltage, and is grounded through parallel capacitors C1 and C2. The switch branch includes a series-connected switch S2 and a fuse F1.

[0050] Furthermore, interface P1 also includes a first signal terminal and a second signal terminal. The first signal terminal is connected to the data receiving terminal RX of chip U2 in the control unit, and the second signal terminal is connected to the data transmitting terminal TX of chip U2 in the control unit. A diode TVS2 is connected between the first signal terminal and the second signal terminal. Interface P1 serves as an interface for connecting external power and external signals, and the diode TVS2 acts as an electrostatic discharge suppressor to prevent the control unit from being damaged by electrostatic discharge.

[0051] In this embodiment of the invention, the sensor detection is described using the first signal detection unit as an example. The dual-electrode electrochemical sensor fault detection device includes a control unit, one or more signal detection units, and a power conversion unit that supports connection to one or more signal detection units.

[0052] When using the first signal detection unit for detection with a dual-electrode electrochemical sensor, the sensor is first inserted into the sensor socket U4. The specific detection circuit consists of a sensor socket U4, an amplifier U3-A, an amplifier U3-B, two P-channel JFET transistors, and external capacitors and resistors. Amplifier U3-B, resistor R3, and resistor R4 form a reference voltage follower, outputting a stable reference voltage to the non-inverting input of amplifier U3-A. This pulls the zero-point voltage of the sensor signal to this reference voltage, ensuring the sensor can operate normally and preventing excessive signal fluctuations in clean air or low concentrations. Transistors Q1 and Q2 are both P-channel JFETs. When the power is off, they are in the conducting state, short-circuiting the circuit connected to the DS terminals (source and drain) (the order of source and drain does not need to be considered in this invention); when the power is on, their DS terminals are disconnected, without affecting the normal operation of the circuit. The function of transistor Q2 is to keep the sensor in a short-circuit state when the circuit is not powered, preventing sensor polarization and reducing the sensor's preheating time. Resistor R17 and capacitor C9 form a low-pass filter to filter out signal noise and interference. Transistor Q1, resistors R13, R15, and R14 form a self-test control branch, which is connected to chip U2 of the control unit for self-test control. The self-test signal terminal ST is high by default under normal operating conditions. At this time, transistor Q1 is turned on, resistor R13 is short-circuited, and the sensor works normally. When switch S1 connected to chip U2 is pressed, the self-test is initiated, and the level of the self-test signal terminal ST is pulled low for 3 seconds before returning to its initial state.

[0053] The actual sensor state can be determined based on the sensor detection signal after the voltage level is pulled low for 3 seconds, and the time before and after that. This includes three possibilities:

[0054] In the first scenario, the sensor detection signal received by chip U2 in the control unit from ADC0 remains unchanged throughout the entire process, which is consistent with the preset open-circuit state fluctuation signal. This indicates that the sensor is in an open-circuit state, LED D7 lights up, and LEDs D1 and D2 do not light up, to indicate the open-circuit state of the sensor.

[0055] The second method involves chip U2 in the control unit receiving a sensor detection signal from ADC0. After switch S1 is pressed, the voltage of the sensor detection signal jumps from a stable initial voltage to 0V, and then jumps back to the initial voltage after 3 seconds, which matches the preset short-circuit state fluctuation signal. This indicates that the sensor is in a short-circuit state, LED D1 lights up, and LEDs D7 and D2 do not light up, indicating the short-circuit state of the sensor.

[0056] The third method involves the chip U2 in the control unit receiving a sensor detection signal from ADC0. After the switch S1 is pressed, the voltage of the sensor detection signal jumps from a stable initial voltage to 0V. After 3 seconds, the voltage climbs back to the initial voltage value and generates a significant overshoot. Then, it slowly falls back to the initial voltage, which matches the preset fault-free state fluctuation signal. This indicates that the sensor is in a fault-free state. LED D2 lights up, while LEDs D7 and D1 do not light up, indicating that the sensor is in a fault-free state.

[0057] The above embodiments are further elaborations and descriptions of the present utility model to facilitate understanding, and are not intended to limit the present utility model in any way. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A fault detection device for a dual-electrode electrochemical sensor, characterized in that, It includes several signal detection units connected to the control unit, and the control unit and signal detection units are powered by a power conversion unit; the signal detection units include: The sensor signal branch is connected to the signal input terminal of the control unit and outputs the sensor detection signal. The self-test control branch is connected to the sensor signal branch and receives the self-test signal from the control unit to start sensor detection or shut it down. The reference voltage branch provides a reference voltage to the sensor signal branch.

2. The fault detection device for a dual-electrode electrochemical sensor according to claim 1, characterized in that, The control unit includes a chip U2, and the voltage input terminal of the chip U2 is connected to the voltage output terminal of the power conversion unit. Several lighting control terminals of chip U2 are connected to an LED light branch, and each LED light branch contains one of three colors of LED lights; the three different colored LED light branches form a signal input terminal of a corresponding control unit.

3. A fault detection device for a dual-electrode electrochemical sensor according to claim 1 or 2, characterized in that, The sensor signal branch includes a sensor socket U4. The first terminal of U4 is connected to the inverting input terminal of amplifier U3-A and is connected to the output terminal of U3-A through a parallel branch of capacitor and resistor. The output terminal of U3-A is connected to the signal input terminal of the control unit. The second terminal of U4 is connected to the non-inverting input terminal of U3-A through resistor R13. A transistor Q2 is connected between the first and second terminals of U4. The gate of Q2 is powered by the power output terminal of the power conversion unit.

4. The fault detection device for a dual-electrode electrochemical sensor according to claim 3, characterized in that, The self-test control branch includes a self-test signal terminal ST connected to the chip U2 of the control unit. The self-test signal terminal ST is connected to one end of resistor R15 and one end of resistor R14 respectively. The other end of resistor R15 is connected to the second pole of U4, and the other end of resistor R14 is connected to the gate of transistor Q1. Transistor Q1 is connected across resistor R13.

5. The fault detection device for a dual-electrode electrochemical sensor according to claim 3, characterized in that, The reference voltage branch includes amplifier U3-B, the output of which is connected to the inverting input of U3-B and the non-inverting input of U3-A respectively; the non-inverting input of U3-B is grounded through resistor R4 and connected to the power output of the power conversion unit through resistor R3.

6. The fault detection device for a dual-electrode electrochemical sensor according to claim 3, characterized in that, The output of the sensor signal branch is connected to the signal input of the control unit through a filter branch. The output terminal of U3-A is connected to one end of resistor R17, and the other end of resistor R17 is grounded through capacitor C9 and connected to the signal input terminal of the control unit.

7. A fault detection device for a dual-electrode electrochemical sensor according to claim 1, 2, 4, 5, or 6, characterized in that, The power conversion unit includes an interface P1. The external power supply terminal of the interface P1 is connected to an external power source and is connected to the voltage input terminal of the conversion chip U1 through a switch branch. The ground terminal of U1 is connected to and grounded with the ground terminal of the interface P1. A diode TVS1 is connected between the external power supply terminal and the ground terminal of the interface P1. The voltage output terminal of U1 serves as the power output terminal of the power conversion unit.

8. The fault detection device for a dual-electrode electrochemical sensor according to claim 7, characterized in that, The interface P1 also includes a first signal terminal and a second signal terminal. The first signal terminal is connected to the data receiving terminal of the chip U2 in the control unit, and the second signal terminal is connected to the data transmitting terminal of the chip U2 in the control unit. A diode TVS2 is connected between the first signal terminal and the second signal terminal.

Images