A method and system for on-line fault diagnosis of hydrogen permeation current of a fuel cell system

Abstract

The present application relates to a kind of fuel cell system hydrogen permeation current on-line fault diagnosis method and its system, on-line fault diagnosis method includes the following steps: when fuel cell system executes hydrogen permeation current on-line fault diagnosis procedure, air from air compressor outlet flows out from the bypass pipeline into the cathode inlet of fuel cell stack;The mass flow of air into stack is gradually reduced, the current single piece voltage is monitored by single piece voltage patrol device CVM, corresponding operating time is recorded, and the variation diagram of single piece voltage with operating time is drawn;According to the variation diagram of single piece voltage with operating time, calculate hydrogen permeation current;Judge whether hydrogen permeation current exceeds safety value, determine whether fuel cell system needs to be shut down for maintenance.No need to rely on the detection of expensive electrochemical experimental equipment, also no need to utilize inert gas, detection cost is greatly reduced, can be realized in actual vehicle-mounted situation on-line detection, application is very convenient.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and specifically to an online fault diagnosis method and system for hydrogen permeation current in a fuel cell system. Background Technology

[0002] As an advanced energy conversion device, fuel cells are being widely promoted and applied due to their advantages such as high energy conversion efficiency, high reliability, cleanliness and environmental protection, and low noise. However, complex and varied on-board conditions and harsh environmental conditions often lead to failures in fuel cell stacks. In order to determine the cause of the failure, it is necessary to test its electrochemical parameters, one of the more commonly used parameters being hydrogen permeation current.

[0003] The hydrogen permeation current represents the amount of gas permeability of the proton exchange membrane. Generally speaking, the proton exchange membrane is not allowed to permeate with gas. During the continuous operation of the fuel cell system, the alternating humidity or temperature can cause mechanical damage to the proton exchange membrane, resulting in perforation of the proton exchange membrane. The perforated proton exchange membrane allows gas to permeate, which in turn leads to serious safety problems.

[0004] Currently, the detection of hydrogen permeation current requires expensive electrochemical experimental equipment, which has high requirements for the detection environment and correspondingly high detection costs. In addition, the gas involved in the detection is an inert gas, which cannot meet the above requirements under actual vehicle conditions.

[0005] Therefore, there is an urgent need to design an online fault diagnosis method and system for hydrogen permeation current of fuel cell systems suitable for vehicle-mounted applications, which can meet the requirements of being both convenient and practical, and solve the problems existing in the above-mentioned technologies. Summary of the Invention

[0006] In view of this, the present invention provides an online fault diagnosis method and system for hydrogen permeation current of a fuel cell system, the purpose of which is to realize the detection of hydrogen permeation current without the need for expensive electrochemical experimental equipment or the use of inert gas.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An online fault diagnosis method for hydrogen permeation current in a fuel cell system includes the following steps:

[0009] A bypass pipe is installed between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack.

[0010] When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe.

[0011] Gradually reduce the mass flow rate Q of the influent air air The current single-chip voltage V is monitored by the single-chip voltage detector (CVM), the corresponding running time t is recorded, and the change of single-chip voltage V with running time t is plotted.

[0012] Based on the graph of the single-cell voltage V versus operating time t, the operating time t corresponding to the hydrogen permeation current of the fuel cell system is determined, and the mass flow rate Q of the infeed air corresponding to this operating time t is calculated. air Calculate the hydrogen permeation current;

[0013] Determine whether the hydrogen permeation current exceeds a safe value to determine whether the fuel cell system needs to be shut down for maintenance.

[0014] Furthermore, when the fuel cell system performs the online fault diagnosis procedure for hydrogen permeation current, the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe, specifically as follows:

[0015] A first solenoid valve is installed on the main pipeline between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack.

[0016] A second solenoid valve is installed on the bypass pipe between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack.

[0017] When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the second solenoid valve is opened and the first solenoid valve is closed, and the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe.

[0018] Furthermore, when the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the air compressor speed is first reduced to the minimum speed N0.

[0019] When the air compressor reaches its minimum speed N0, the second solenoid valve opens and the first solenoid valve closes; the current single-chip voltage V is monitored by the single-chip voltage detector CVM. 0 Record the corresponding running time t 0 In a running time of t 0 At that time, the corresponding mass flow rate of the injected air was recorded as follows:

[0020] Furthermore, the gradual reduction of the mass flow rate Q of the influent air... air The details are as follows:

[0021] By adjusting the duty cycle signal of the second solenoid valve, the opening degree of the second solenoid valve is gradually reduced. Each adjustment is monitored by the single-chip voltage detector (CVM) to check the current single-chip voltage V.n Record the corresponding running time t n Plot the change of the single-chip voltage V with operating time t; when the operating time is t n At that time, the corresponding mass flow rate of the injected air was recorded as follows:

[0022] Furthermore, when the single-cell voltage V shows a sudden voltage drop in the graph of operating time t, and the single-cell voltage monitor (CVM) detects that the single-cell voltage value drops to around 0.1, the mass flow rate Q of the infeed air at this time is used as a reference. air The calculated operating current I of the fuel cell stack is the hydrogen permeation current.

[0023] Furthermore, the mass flow rate Q of the incoming air at this time... air The calculated operating current I of the fuel cell stack is as follows:

[0024] When hydrogen gas permeates through the proton exchange membrane to the air side, an electrochemical reaction occurs, which obeys Faraday's law:

[0025] I = 0.21 * 4F * Q air ;

[0026] In the formula, Q air The mass flow rate of the air entering the reactor is denoted as F; F is the Faraday constant; and I is the operating current.

[0027] A mass flow meter is installed on the bypass pipe, and the mass flow meter is located before the second solenoid valve; the mass flow meter is used to measure the mass flow rate Q of the incoming air. air .

[0028] Furthermore, the determination of whether the hydrogen permeation current exceeds a safe value, and whether the fuel cell system needs to be shut down for maintenance, is as follows:

[0029] The safe value of the hydrogen permeation current of a proton exchange membrane is I. lim When the calculated real-time hydrogen permeation current is less than or equal to I lim When the fuel cell system is operating normally, the real-time hydrogen permeation current is greater than I. lim At that time, the fuel cell system was shut down for maintenance.

[0030] Furthermore, when the real-time hydrogen permeation current is greater than I... lim At the same time, continue to gradually reduce the mass flow rate Q of the influent air. air If the single-cell voltage monitor (CVM) detects a sudden drop in the single-cell voltage of another cell to around 0.1, it calculates the hydrogen permeation current of the corresponding cell and compares it with the safe value of the hydrogen permeation current, I. lim Compare and determine whether the corresponding individual battery requires downtime for maintenance;

[0031] When the mass flow rate of the injected air is Q air The detection stops when the air mass flow rate is reduced to the minimum.

[0032] The present invention also provides an online fault diagnosis system for hydrogen permeation current of a fuel cell system, the online fault diagnosis system comprising:

[0033] Detection module: A bypass pipe is installed between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack; a first solenoid valve is installed on the main pipe between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack; a second solenoid valve is installed on the bypass pipe between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack.

[0034] Data acquisition module: Mass flow meter is used to measure the mass flow rate of air entering the reactor; Single-chip voltage monitor (CVM) is used to measure the single-chip voltage; Time recorder records the corresponding running time;

[0035] Calculation module: used to plot the change of single-chip voltage over running time based on the data obtained by the data acquisition module; and to calculate the hydrogen permeation current;

[0036] Judgment module: Used to determine whether the hydrogen permeation current exceeds the safe value and whether the fuel cell system needs to be shut down for maintenance.

[0037] The present invention also provides an electronic device, including a memory and a processor; the memory stores a computer program that can be run by the processor; when the processor runs the computer program, it executes the above-described online fault diagnosis method for hydrogen permeation current of a fuel cell system.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] (1) By setting a bypass pipe between the air compressor outlet and the cathode inlet of the fuel cell stack, when the fuel cell system performs an online fault diagnosis procedure based on hydrogen permeation current, the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe. Hydrogen permeates through the proton exchange membrane to the air side, where it is immediately consumed under oxygen-rich conditions. As the air flow gradually decreases until the oxygen flow just consumes the permeated hydrogen, the performance drops sharply, i.e., the voltage drops sharply. This characteristic allows for a gradual reduction in the mass flow rate of the air entering the stack, accurate calculation of the hydrogen permeation current, and determination of whether the fuel cell system needs to be shut down for maintenance based on the value of the hydrogen permeation current. This method eliminates the need for expensive electrochemical experimental equipment and inert gases, significantly reducing detection costs. It enables online detection under actual vehicle conditions, making the online fault diagnosis method based on hydrogen permeation current in this application very convenient to use.

[0040] (2) Due to the inconsistent operating states of each cell in the fuel cell system, the hydrogen permeation current varies for each cell. When the fuel cell system executes the online fault diagnosis procedure for hydrogen permeation current, if the single-cell voltage monitor (CVM) detects a sharp drop in the voltage of a single cell to 0.1V, the hydrogen permeation current of that single cell can be calculated based on the mass flow rate of the incoming air at that time. For other cells in the stack, the voltage remains at a relatively high level. In this case, the mass flow rate of the air can be gradually reduced. If the CVM detects a sudden drop in the single-cell voltage of another cell to around 0.1V, the hydrogen permeation current of the corresponding single cell is calculated and compared with the safe value of the hydrogen permeation current, I. lim By comparison, it can be determined whether a single cell needs to be shut down for maintenance; it can also perform simultaneous testing of multiple single cells.

[0041] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A schematic diagram of the bypass pipeline of a fuel cell system according to an embodiment of the present invention is shown;

[0044] Figure 2 The graph shows the variation of single-cell voltage V with operating time t when the fuel cell system of this embodiment of the invention executes the online fault diagnosis program for hydrogen permeation current.

[0045] In the diagram: 1. Air compressor; 2. First solenoid valve; 3. Fuel cell stack; 4. Mass flow meter; 5. First solenoid valve. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] As attached Figure 1 As shown in the figure, this invention proposes an online fault diagnosis method for hydrogen permeation current in a fuel cell system, comprising the following steps:

[0048] A bypass pipe is installed between the outlet of the air compressor 1 of the fuel cell system and the cathode inlet of the fuel cell stack 3.

[0049] When the fuel cell system performs the online fault diagnosis procedure for hydrogen permeation current, the air flowing out of the air compressor 1 outlet enters the cathode inlet of the fuel cell stack 3 through the bypass pipe.

[0050] Gradually reduce the mass flow rate Q of the influent air air The current single-chip voltage V is monitored by a single-chip voltage monitor (CVM), the corresponding running time t is recorded, and a graph showing the change of single-chip voltage V over running time t is plotted. Figure 2 As shown;

[0051] Based on the graph of the single-cell voltage V versus operating time t, the operating time t corresponding to the hydrogen permeation current of the fuel cell system is determined, and the mass flow rate Q of the infeed air corresponding to this operating time t is calculated. air Calculate the hydrogen permeation current;

[0052] Determine whether the hydrogen permeation current exceeds a safe value to determine whether the fuel cell system needs to be shut down for maintenance.

[0053] When the fuel cell system performs the online fault diagnosis procedure for hydrogen permeation current, the air flowing out of the air compressor 1 outlet enters the cathode inlet of the fuel cell stack 3 through the bypass pipe, as follows:

[0054] A first solenoid valve 2 is installed on the main pipeline between the outlet of the air compressor 1 of the fuel cell system and the cathode inlet of the fuel cell stack 3;

[0055] A second solenoid valve 5 is installed on the bypass pipe between the outlet of the air compressor 1 of the fuel cell system and the cathode inlet of the fuel cell stack 3;

[0056] When the fuel cell system is running under normal operating conditions, the first solenoid valve 2 is opened and the second solenoid valve 5 is closed. The air flowing out of the air compressor 1 enters the fuel cell stack 3 through the main pipeline to participate in the reaction.

[0057] When the fuel cell system performs the online fault diagnosis procedure for hydrogen permeation current, the second solenoid valve 5 is opened and the first solenoid valve 2 is closed. The air flowing out of the air compressor 1 outlet enters the cathode inlet of the fuel cell stack 3 through the bypass pipe.

[0058] When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the speed of air compressor 1 is first reduced to the minimum speed N0;

[0059] When the air compressor 1 reaches its minimum speed N0, the second solenoid valve 5 is opened and the first solenoid valve 2 is closed; the current single-chip voltage V is monitored by the single-chip voltage detector CVM. 0 Record the corresponding running time t 0 In a running time of t 0 At that time, the corresponding mass flow rate of the injected air was recorded as follows:

[0060] The gradual reduction of the mass flow rate Q of the influent air air The details are as follows:

[0061] By adjusting the duty cycle signal of the second solenoid valve 5, the opening degree of the second solenoid valve 5 is gradually reduced. Each adjustment is monitored by the single-chip voltage detector (CVM) to check the current single-chip voltage V. n Record the corresponding running time t n Plot the change of the single-chip voltage V with operating time t; when the operating time is t n At that time, the corresponding mass flow rate of the injected air was recorded as follows:

[0062] In practical applications, hydrogen is introduced to the anode side of the fuel cell, and air is introduced to the cathode side. The hydrogen is electrolyzed into H₂ under the action of the anode catalyst. + And electrons, H +Hydrogen gas passes through the proton exchange membrane to the cathode and reacts with oxygen there. In the open-circuit state (no load current), the voltage of a single cell, monitored by a voltage monitor (CVM), is approximately 0.98V. When the proton exchange membrane has perforations, the pressure on the anode side is higher than on the cathode side during operation. Under this pressure difference, hydrogen gas directly passes through the proton exchange membrane to the cathode and reacts directly with oxygen, generating a short-circuit current inside. As the amount of hydrogen passing through increases and the amount of oxygen on the cathode side gradually decreases, the open-circuit voltage continues to drop until the hydrogen gas consumes all the oxygen. At this point, the voltage of a single cell drops sharply to approximately 0.1V.

[0063] When the graph of the single-cell voltage V versus operating time t shows a sudden voltage drop, and the single-cell voltage monitor (CVM) detects that the single-cell voltage value drops to around 0.1, the mass flow rate Q of the incoming air at this time is used as the basis for this reading. air The calculated operating current I of fuel cell stack 3 is the hydrogen permeation current.

[0064] The mass flow rate Q of the incoming air at this time air The calculated operating current I of fuel cell stack 3 is as follows:

[0065] When hydrogen gas permeates through the proton exchange membrane to the air side, an electrochemical reaction occurs, which obeys Faraday's law:

[0066] I = 0.21 * 4F * Q air ;

[0067] In the formula, Q air is the mass flow rate of the air entering the reactor; F is the Faraday constant, with a value of 96485; I is the operating current.

[0068] A mass flow meter 4 is installed on the bypass pipe, and the mass flow meter 4 is located before the second solenoid valve 5; the mass flow meter 4 is used to measure the mass flow rate Q of the air entering the reactor. air .

[0069] The determination of whether the hydrogen permeation current exceeds a safe value, and whether the fuel cell system needs to be shut down for maintenance, is as follows:

[0070] The safe value of the hydrogen permeation current of a proton exchange membrane is I. lim When the calculated real-time hydrogen permeation current is less than or equal to I lim When the fuel cell system is operating normally, the real-time hydrogen permeation current is greater than I. lim At that time, the fuel cell system was shut down for maintenance.

[0071] When the real-time hydrogen permeation current is greater than I lim At the same time, continue to gradually reduce the mass flow rate Q of the influent air.air If the single-cell voltage monitor (CVM) detects a sudden drop in the single-cell voltage of another cell to around 0.1, it calculates the hydrogen permeation current of the corresponding cell and compares it with the safe value of the hydrogen permeation current, I. lim Compare and determine whether the corresponding individual battery requires downtime for maintenance;

[0072] When the mass flow rate of the injected air is Q air The detection stops when the air mass flow rate is reduced to the minimum.

[0073] The initial membrane electrode has good hermeticity. In the initial state, the minimum limiting current of the membrane electrode is detected, and the minimum limiting current is substituted into the following formula:

[0074] I = 0.21 * 4F * Q air ;

[0075] Calculate the minimum air mass flow rate.

[0076] By installing a bypass pipe between the air compressor outlet and the cathode inlet of the fuel cell stack, when the fuel cell system performs an online fault diagnosis procedure based on hydrogen permeation current, the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe. Hydrogen permeates through the proton exchange membrane to the air side, where it is immediately consumed under oxygen-rich conditions. As the air flow gradually decreases until the oxygen flow just begins to consume the permeated hydrogen, performance drops sharply, specifically the voltage. This characteristic allows for a gradual reduction in the mass flow rate of air entering the stack, accurate calculation of the hydrogen permeation current, and determination of whether the fuel cell system needs to be shut down for maintenance based on the value of the hydrogen permeation current. This method eliminates the need for expensive electrochemical experimental equipment and inert gases, significantly reducing detection costs. It enables online detection under actual vehicle conditions, making the online fault diagnosis method for hydrogen permeation current in this application extremely convenient.

[0077] Because the operating states of each cell in a fuel cell system are inconsistent, the hydrogen permeation current varies from cell to cell. When the fuel cell system executes an online fault diagnosis program for hydrogen permeation current, if the cell voltage monitor (CVM) detects a sharp drop in the voltage of a particular cell to 0.1V, the hydrogen permeation current of that cell can be calculated based on the mass flow rate of the incoming air at that moment. For other cells in the stack, the voltage remains at a relatively high level. In this case, the mass flow rate of the air can be gradually reduced. If the CVM detects a sudden drop in the voltage of another cell to around 0.1V, the hydrogen permeation current of the corresponding cell is calculated and compared with the safe value of the hydrogen permeation current, I. lim By comparison, it can be determined whether a single cell needs to be shut down for maintenance; it can also perform simultaneous testing of multiple single cells.

[0078] This application also provides an online fault diagnosis system for hydrogen permeation current of a fuel cell system, the online fault diagnosis system comprising:

[0079] Detection module: A bypass pipe is installed between the outlet of the air compressor 1 of the fuel cell system and the cathode inlet of the fuel cell stack 3; a first solenoid valve 2 is installed on the main pipe between the outlet of the air compressor 1 of the fuel cell system and the cathode inlet of the fuel cell stack 3; a second solenoid valve 5 is installed on the bypass pipe between the outlet of the air compressor 1 of the fuel cell system and the cathode inlet of the fuel cell stack 3.

[0080] Data acquisition module: Mass flow meter is used to measure the mass flow rate of air entering the reactor; Single-chip voltage monitor (CVM) is used to measure the single-chip voltage; Time recorder records the corresponding running time;

[0081] Calculation module: used to plot the change of single-chip voltage over running time based on the data obtained by the data acquisition module; and to calculate the hydrogen permeation current;

[0082] Judgment module: Used to determine whether the hydrogen permeation current exceeds the safe value and whether the fuel cell system needs to be shut down for maintenance.

[0083] This application also provides an electronic device, including a memory and a processor; the memory stores a computer program that can be run by the processor; when the processor runs the computer program, it performs the above-described online fault diagnosis method for hydrogen permeation current of a fuel cell system.

[0084] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An online fault diagnosis method for hydrogen permeation current in a fuel cell system, characterized in that, Includes the following steps: A bypass pipe is installed between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack. When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe. Gradually reduce the mass flow rate Q of the influent air air The current single-chip voltage V is monitored by the single-chip voltage detector (CVM), the corresponding running time t is recorded, and the change of single-chip voltage V with running time t is plotted. Based on the graph of the single-cell voltage V versus operating time t, the operating time t corresponding to the hydrogen permeation current of the fuel cell system is determined, and the mass flow rate Q of the infeed air corresponding to this operating time t is calculated. air Calculate the hydrogen permeation current; When the graph of the single-cell voltage V versus operating time t shows a sudden voltage drop, and the single-cell voltage monitor (CVM) detects that the single-cell voltage value drops to around 0.1, the mass flow rate Q of the incoming air at this time is used as the basis for this reading. air The calculated operating current I of the fuel cell stack is the hydrogen permeation current; the details are as follows: When hydrogen gas permeates through the proton exchange membrane to the air side, an electrochemical reaction occurs, which obeys Faraday's law: I=0.21*4F*Q air ; In the formula, Q air The mass flow rate of the air entering the reactor is denoted as F; F is the Faraday constant; and I is the operating current. A mass flow meter is installed on the bypass duct; the mass flow meter is used to measure the mass flow rate Q of the air entering the reactor. air ; Determine whether the hydrogen permeation current exceeds a safe value to determine whether the fuel cell system needs to be shut down for maintenance.

2. The online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in claim 1, characterized in that, When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe, as follows: A first solenoid valve is installed on the main pipeline between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack. A second solenoid valve is installed on the bypass pipe between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack. When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the second solenoid valve is opened and the first solenoid valve is closed, and the air flowing out of the air compressor outlet enters the cathode inlet of the fuel cell stack through the bypass pipe.

3. The online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in claim 2, characterized in that, When the fuel cell system performs an online fault diagnosis procedure for hydrogen permeation current, the speed of the air compressor is first reduced to the minimum speed N0. When the air compressor reaches its minimum speed N0, the second solenoid valve opens and the first solenoid valve closes; the current single-chip voltage V is monitored by the single-chip voltage detector CVM. 0 Record the corresponding running time t 0 In a running time of t 0 At that time, the corresponding mass flow rate of the injected air was recorded as follows:

4. The online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in claim 3, characterized in that, The gradual reduction of the mass flow rate Q of the influent air air The details are as follows: By adjusting the duty cycle signal of the second solenoid valve, the opening degree of the second solenoid valve is gradually reduced. Each adjustment is monitored by the single-chip voltage detector (CVM) to check the current single-chip voltage V. n Record the corresponding running time t n Plot the change of the single-chip voltage V with operating time t; when the operating time is t n At that time, the corresponding mass flow rate of the injected air was recorded as follows:

5. The online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in claim 4, characterized in that, The determination of whether the hydrogen permeation current exceeds a safe value, and whether the fuel cell system needs to be shut down for maintenance, is as follows: The safe value of the hydrogen permeation current of a proton exchange membrane is I. lim When the calculated real-time hydrogen permeation current is less than or equal to I lim When the fuel cell system is operating normally, the real-time hydrogen permeation current is greater than I. lim At that time, the fuel cell system was shut down for maintenance.

6. The online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in claim 5, characterized in that, When the real-time hydrogen permeation current is greater than I lim At the same time, continue to gradually reduce the mass flow rate Q of the influent air. air If the single-cell voltage monitor (CVM) detects a sudden drop in the single-cell voltage of another cell to around 0.1, it calculates the hydrogen permeation current of the corresponding cell and compares it with the safe value of the hydrogen permeation current, I. lim Compare and determine whether the corresponding individual battery requires downtime for maintenance; When the mass flow rate of the injected air is Q air The detection stops when the air mass flow rate is reduced to the minimum.

7. An online fault diagnosis system for hydrogen permeation current of a fuel cell system, used to execute the online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in any one of claims 1-6, characterized in that, The online fault diagnosis system includes: Detection module: A bypass pipe is installed between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack; a first solenoid valve is installed on the main pipe between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack; a second solenoid valve is installed on the bypass pipe between the outlet of the air compressor of the fuel cell system and the cathode inlet of the fuel cell stack. Data acquisition module: Mass flow meter is used to measure the mass flow rate of air entering the reactor; Single-chip voltage monitor (CVM) is used to measure the single-chip voltage; Time recorder records the corresponding running time; Calculation module: used to plot the change of single-chip voltage over running time based on the data obtained by the data acquisition module; and to calculate the hydrogen permeation current; Judgment module: Used to determine whether the hydrogen permeation current exceeds the safe value and whether the fuel cell system needs to be shut down for maintenance.

8. An electronic device, characterized in that, It includes a memory and a processor; the memory stores a computer program that can be executed by the processor; when the processor runs the computer program, it performs the online fault diagnosis method for hydrogen permeation current of a fuel cell system as described in any one of claims 1-6.

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