Online fault diagnosis method and system for hydrogen permeation current of fuel cell system

Abstract

The invention relates to an online fault diagnosis method and system for hydrogen permeation current of a fuel cell system, and the online fault diagnosis method comprises the following steps: when the fuel cell system executes an online fault diagnosis program for hydrogen permeation current, air flowing out from an outlet of an air compressor enters a cathode inlet of a fuel cell stack from a bypass pipeline; the mass flow rate of air entering the reactor is gradually reduced, the current single-chip voltage is monitored through a single-chip voltage inspection device CVM, the corresponding operation time is recorded, and a change diagram of the single-chip voltage along with the operation time is drawn; calculating a hydrogen permeation current according to the change diagram of the single-chip voltage along with the operation time; and judging whether the hydrogen permeation current exceeds a safety value or not, and determining whether the fuel cell system needs to be subjected to shutdown maintenance or not. According to the method, expensive electrochemical experiment equipment is not needed for detection, inert gas is not needed, the detection cost is greatly reduced, online detection can be realized under the actual vehicle-mounted condition, and the method is very convenient to apply.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly relates to an online fault diagnosis method and system for the hydrogen permeation current of a fuel cell system. Background Art

[0002] As an advanced energy conversion device, fuel cells are being widely promoted and applied because of their advantages such as high energy conversion efficiency, high reliability, environmental friendliness, and low noise. However, the complex and changeable vehicle operating conditions and harsh environmental conditions often cause faults in the fuel cell stack. In order to determine the cause of the faults in the fuel cell stack, it is necessary to detect its electrochemical parameters. One of the commonly used parameters is the hydrogen permeation current.

[0003] The hydrogen permeation current represents the magnitude of the gas permeability of the proton exchange membrane. Generally speaking, the proton exchange membrane does not allow gas to permeate. During the continuous operation of the fuel cell system, due to humidity alternation or temperature alternation, mechanical damage will be caused to the proton exchange membrane, resulting in perforation of the proton exchange membrane. After perforation, the proton exchange membrane allows gas to permeate, which will bring serious safety problems.

[0004] Currently, for the detection of the hydrogen permeation current, on the one hand, it is necessary to detect with the help of expensive electrochemical experimental equipment, and the detection environment requirements are high and the corresponding detection costs are also high; on the other hand, the gas participating in the detection is an inert gas, and in the actual vehicle situation, the above requirements cannot be met.

[0005] Therefore, it is urgent to design an online fault diagnosis method and system for the hydrogen permeation current of a fuel cell system suitable for vehicle use, which meets the requirements of being both convenient and practical, and solves the problems existing in the above-mentioned prior art. Summary of the Invention

[0006] In view of this, the present invention provides an online fault diagnosis method and system for the hydrogen permeation current of a fuel cell system, aiming to realize the detection of the hydrogen permeation current without the need to detect with the help of expensive electrochemical experimental equipment and without using inert gas.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

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

[0009] A bypass pipeline is arranged 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 executes the online fault diagnosis program for the hydrogen permeation current, the air flowing out of the outlet of the air compressor all enters the cathode inlet of the fuel cell stack through the bypass pipeline;

[0011] Gradually reduce the mass flow rate Q of the incoming air air , monitor the current single-cell voltage V through the single-cell voltage inspection device CVM, record the corresponding running time t, and plot the change graph of the single-cell voltage V with respect to the running time t;

[0012] According to the change graph of the single-cell voltage V with respect to the running time t, determine the running time t corresponding to calculating the hydrogen permeation current of the fuel cell system, and based on the mass flow rate Q of the incoming air corresponding to this running time t air , calculate the hydrogen permeation current;

[0013] Judge whether the hydrogen permeation current exceeds the safety value to determine whether it is necessary to shut down the fuel cell system for maintenance.

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

[0015] Set a first solenoid valve on the main pipeline between the outlet of the fuel cell system air compressor and the cathode inlet of the fuel cell stack;

[0016] Set a second solenoid valve on the bypass pipeline between the outlet of the fuel cell system air compressor and the cathode inlet of the fuel cell stack;

[0017] When the fuel cell system executes the online fault diagnosis program for the hydrogen permeation current, open the second solenoid valve and close the first solenoid valve, and the air flowing out of the air compressor outlet all enters the cathode inlet of the fuel cell stack through the bypass pipeline.

[0018] Furthermore, when the fuel cell system executes the online fault diagnosis program for the hydrogen permeation current, first reduce the speed of the air compressor to the lowest speed N 0 ;

[0019] When the speed of the air compressor reaches the lowest speed N 0 , open the second solenoid valve and close the first solenoid valve; monitor the current single-cell voltage V through the single-cell voltage inspection device CVM 0 , record the corresponding running time t 0 , at the running time of t 0 , record the corresponding mass flow rate of the incoming air as

[0020] Furthermore, the gradual reduction of the mass flow rate Q of the incoming air air , specifically as follows:

[0021] By adjusting the duty cycle signal of the second solenoid valve, gradually reduce the opening degree of the second solenoid valve. Each time it is adjusted, monitor the current single-chip voltage V through the single-chip voltage inspection device CVM n , record the corresponding running time t n , draw a graph of the change of the single-chip voltage V with the running time t; at the running time of t n , record the corresponding mass flow rate of the incoming air as

[0022] Furthermore, when there is a sudden drop in voltage in the graph of the change of the single-chip voltage V with the running time t, and the single-chip voltage inspection device CVM monitors that the single-chip voltage value suddenly drops to about 0.1, according to the mass flow rate Q of the incoming air at this time air The corresponding working current I of the fuel cell stack calculated is the hydrogen permeation current.

[0023] Furthermore, the corresponding working current I of the fuel cell stack calculated according to the mass flow rate Q of the incoming air at this time air is specifically as follows:

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

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

[0026] In the formula, Q air is the mass flow rate of the incoming air; F is the Faraday constant; I is the working current;

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

[0028] Furthermore, the method for judging whether the hydrogen permeation current exceeds the safety value and determining whether the fuel cell system needs to be shut down for maintenance is specifically as follows:

[0029] The safety value of the hydrogen permeation current of the proton exchange membrane is I lim , when the calculated real-time hydrogen permeation current is less than or equal to I lim , the fuel cell system operates normally; when the real-time hydrogen permeation current is greater than I lim , the fuel cell system shuts down for maintenance.

[0030] Furthermore, when the real-time hydrogen permeation current is greater than I lim , continue to gradually reduce the mass flow rate Q of the incoming air airIf the single-cell voltage monitor CVM detects that the single-cell voltage value of other single cells suddenly drops to about 0.1, the hydrogen permeation current of the corresponding single cell is calculated and compared with the safety value of the hydrogen permeation current I lim to determine whether the corresponding single cell needs to be shut down for maintenance;

[0031] When the mass flow rate Q of the incoming stack air air decreases to the minimum mass flow rate of air, the detection is stopped.

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

[0033] Detection module: A bypass pipeline is provided 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 provided 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 provided on the bypass pipeline 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: A mass flow meter is used to measure the mass flow rate of the incoming stack air; a single-cell voltage monitor CVM is used to measure the single-cell voltage; a time recorder records the corresponding operating time;

[0035] Calculation module: It is used to draw a graph of the change of the single-cell voltage with the operating time according to the data obtained by the data acquisition module; and calculate the hydrogen permeation current;

[0036] Judgment module: It is used to judge whether the hydrogen permeation current exceeds the safety value and determine whether it is necessary to shut down the fuel cell system for maintenance.

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

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

[0039] (1) By providing a bypass pipeline between the outlet of the air compressor in the fuel cell system and the cathode inlet of the fuel cell stack, when the fuel cell system executes the online fault diagnosis program for the hydrogen permeation current, the air flowing out of the outlet of the air compressor enters the cathode inlet of the fuel cell stack through the bypass pipeline. Utilizing the fact that hydrogen permeates through the proton exchange membrane to reach the air side and will be immediately consumed under oxygen-rich conditions, as the air flow gradually decreases, until the oxygen flow just consumes the permeated hydrogen, the performance will decline sharply, that is, the voltage drops sharply. Based on this characteristic, gradually reduce the mass flow rate of the incoming air, accurately calculate the hydrogen permeation current, and determine whether the fuel cell system needs to be shut down for maintenance according to the value of the hydrogen permeation current. There is no need to detect with expensive electrochemical experimental equipment, nor to use inert gas, and the detection cost is greatly reduced. It can achieve online detection under actual vehicle conditions, and the online fault diagnosis method for the hydrogen permeation current of the fuel cell system of this application is very convenient to apply.

[0040] (2) Since the operating states of each single cell in the fuel cell system are inconsistent, resulting in different magnitudes of hydrogen permeation current for each cell. When the fuel cell system executes the online fault diagnosis program for the hydrogen permeation current, when the single-cell voltage monitor CVM monitors that the voltage of a certain single cell drops sharply to 0.1 V, the hydrogen permeation current of this single cell can be calculated based on the mass flow rate of the incoming air at this time; for other single cells in the stack, the voltage still remains at a relatively high level. In this case, the air quality flow rate can continue to be gradually reduced. If the single-cell voltage monitor CVM monitors that the single-cell voltage value of other single cells suddenly drops to about 0.1, then calculate the hydrogen permeation current of the corresponding single cell and compare it with the safety value of the hydrogen permeation current I lim to determine whether the corresponding single cell needs to be shut down for maintenance; simultaneous detection of multiple single cells can be achieved.

[0041] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the structures pointed out in the specification and the drawings. Brief Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0043] Figure 1 Shows a schematic structural diagram of the bypass pipeline of the fuel cell system in the embodiment of the present invention;

[0044] Figure 2 It shows the variation diagram of the single - cell voltage V with the operation time t when the fuel cell system according to the embodiment of the present invention executes the online fault diagnosis program for the hydrogen - permeating current.

[0045] In the figure: 1. Air compressor; 2. First solenoid valve; 3. Fuel cell stack; 4. Mass flowmeter; 5. First solenoid valve. Specific embodiments

[0046] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] As shown in the Figure 1 accompanying drawings, the embodiment of the present invention provides an online fault diagnosis method for the hydrogen - permeating current of a fuel cell system, including the following steps:

[0048] A bypass pipeline is provided 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 executes the online fault diagnosis program for the hydrogen - permeating current, the air flowing out of the outlet of the air compressor 1 all enters the cathode inlet of the fuel cell stack 3 through the bypass pipeline;

[0050] Gradually reduce the mass flow rate Q of the air entering the stack air , monitor the current single - cell voltage V through the single - cell voltage inspection device CVM, record the corresponding operation time t, and draw the variation diagram of the single - cell voltage V with the operation time t, as Figure 2 shown;

[0051] According to the variation diagram of the single - cell voltage V with the operation time t, determine the operation time t corresponding to calculating the hydrogen - permeating current of the fuel cell system, and according to the mass flow rate Q of the air entering the stack corresponding to this operation time t air , calculate the hydrogen - permeating current;

[0052] Judge whether the hydrogen - permeating current exceeds the safety value to determine whether it is necessary to stop the fuel cell system for maintenance.

[0053] When the fuel cell system executes the online fault diagnosis program for the hydrogen - permeating current, the air flowing out of the outlet of the air compressor 1 all enters the cathode inlet of the fuel cell stack 3 through the bypass pipeline, specifically as follows:

[0054] A first solenoid valve 2 is provided 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 provided on the bypass pipeline 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 operates under normal conditions, the first solenoid valve 2 is opened and the second solenoid valve 5 is closed, and the air flowing out of the outlet of the air compressor 1 enters the stack 3 through the main pipeline to participate in the reaction;

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

[0058] When the fuel cell system executes the online fault diagnosis program of the hydrogen permeation current, first reduce the speed of the air compressor 1 to the lowest speed N 0 ;

[0059] When the speed of the air compressor 1 reaches the lowest speed N 0 At this time, open the second solenoid valve 5 and close the first solenoid valve 2; monitor the current single-cell voltage V through the single-cell voltage inspection device CVM 0 and record the corresponding running time t 0 At the running time of t 0 record the corresponding mass flow rate of the air entering the stack as

[0060] The gradually decreasing mass flow rate Q of the air entering the stack air is as follows:

[0061] By adjusting the duty cycle signal of the second solenoid valve 5, gradually reduce the opening degree of the second solenoid valve 5. Each time it is adjusted, monitor the current single-cell voltage V through the single-cell voltage inspection device CVM n and record the corresponding running time t n and draw a graph of the change of the single-cell voltage V with the running time t; at the running time of t n record the corresponding mass flow rate of the air entering the stack as

[0062] In practical applications, hydrogen is introduced into the anode side of the fuel cell and air is introduced into the cathode side. Hydrogen is electrolyzed into H + and electrons under the action of the anode catalyst, and H +It reaches the cathode through the proton exchange membrane and reacts with the oxygen at the cathode. In the open-circuit state without load current, the voltage of a single cell monitored by the voltage inspection device CVM is about 0.98V at this time. When there is a perforation in the proton exchange membrane, since the pressure on the anode side is higher than that on the cathode side during operation, under the action of the pressure difference, hydrogen will directly pass through the proton exchange membrane to reach the cathode and directly react with oxygen, thus 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 will continue to drop until the hydrogen passing through consumes all the oxygen. At this time, the voltage of a single cell will drop sharply to about 0.1V.

[0063] When there is a sudden drop in voltage in the graph of the change of the single-cell voltage V with the operating time t, and the single-cell voltage value monitored by the single-cell voltage inspection device CVM suddenly drops to about 0.1, according to the mass flow rate Q of the incoming air at this time air The corresponding working current I of the fuel cell stack 3 calculated is the hydrogen permeation current.

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

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

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

[0067] In the formula, Q air is the mass flow rate of the incoming air; F is the Faraday constant, and its value is 96485; I is the working current.

[0068] A mass flowmeter 4 is provided on the bypass pipeline, and the mass flowmeter 4 is located before the second solenoid valve 5; the mass flowmeter 4 is used to measure the mass flow rate Q of the incoming air air .

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

[0070] The safety value of the hydrogen permeation current of the proton exchange membrane is I lim , when the calculated real-time hydrogen permeation current is less than or equal to I lim , the fuel cell system operates normally; when the real-time hydrogen permeation current is greater than I lim , the fuel cell system shuts down for maintenance.

[0071] When the real-time hydrogen permeation current is greater than I lim , continue to gradually reduce the mass flow rate Q of the incoming airair When the single-cell voltage inspection device CVM detects that the single-cell voltage value of other single cells suddenly drops to about 0.1, the hydrogen permeation current of the corresponding single cell is calculated and compared with the safety value of the hydrogen permeation current, which is I lim to determine whether the corresponding single cell needs to be shut down for maintenance;

[0072] When the mass flow rate Q of the incoming stack air air decreases to the minimum air mass flow rate, the detection is stopped.

[0073] The initial membrane electrode will have relatively good airtightness. 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] The minimum air mass flow rate is calculated.

[0076] By setting a bypass pipeline 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 executes the online fault diagnosis program of the hydrogen permeation current, the air flowing out of the outlet of the air compressor enters the cathode inlet of the fuel cell stack from the bypass pipeline. Utilizing the fact that hydrogen permeates through the proton exchange membrane to reach the air side and will be immediately consumed under oxygen-rich conditions. As the air flow rate gradually decreases, until the oxygen flow rate just consumes the permeated hydrogen, the performance will drop sharply, that is, the voltage drops sharply. Based on this characteristic, the mass flow rate of the incoming stack air is gradually reduced, the hydrogen permeation current is accurately calculated, and the fuel cell system is judged to be shut down for maintenance according to the value of the hydrogen permeation current. There is no need to use expensive electrochemical experimental equipment for detection, nor to use inert gases, and the detection cost is greatly reduced. It can achieve online detection under actual vehicle-mounted conditions, and the online fault diagnosis method of the hydrogen permeation current executed by the fuel cell system of the present application is very convenient to apply.

[0077] Since the operating states of each single cell of the fuel cell system are inconsistent, resulting in different hydrogen permeation currents for each cell. When the fuel cell system executes the online fault diagnosis program of the hydrogen permeation current, when the single-cell voltage inspection device CVM detects that the voltage of a certain single cell drops sharply to 0.1V, the hydrogen permeation current of this single cell can be calculated according to the mass flow rate of the incoming stack air at this time; for other single cells in the stack, the voltage still remains at a relatively high level. In this case, the air mass flow rate can continue to be gradually reduced. When the single-cell voltage inspection device CVM detects that the single-cell voltage value of other single cells suddenly drops to about 0.1, the hydrogen permeation current of the corresponding single cell is calculated and compared with the safety value of the hydrogen permeation current, which is I lim to determine whether the corresponding single cell needs to be shut down for maintenance; simultaneous detection of multiple single cells can be achieved.

[0078] The present application also provides an on-line fault diagnosis system for the hydrogen permeation current of a fuel cell system. The on-line fault diagnosis system includes:

[0079] Detection module: A bypass pipeline is arranged 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 arranged 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; a second solenoid valve 5 is arranged on the bypass pipeline 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: A mass flowmeter is used to measure the mass flow rate of the air entering the stack; a single-cell voltage inspection device CVM is used to measure the single-cell voltage; a time recorder records the corresponding running time;

[0081] Calculation module: It is used to draw a graph of the change of the single-cell voltage with the running time according to the data obtained by the data acquisition module; and calculate the hydrogen permeation current;

[0082] Judgment module: It is used to judge whether the hydrogen permeation current exceeds the safety value and determine whether it is necessary to stop the fuel cell system for maintenance.

[0083] The present application also provides an electronic device, including a memory and a processor; a computer program that can be run by the processor is stored on the memory; when the processor runs the computer program, it executes the above-mentioned on-line fault diagnosis method for the hydrogen permeation current of the fuel cell system.

[0084] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions 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 of a fuel cell system, characterized in that: The following steps are involved: A bypass pipeline is provided 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 executes the online fault diagnosis procedure of hydrogen permeation current, the air flowing out through 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 air entering the reactor air , monitor the current single-chip voltage V through the single-chip voltage patroller CVM, record the corresponding running time t, and draw a graph of the change of the single-chip voltage V with the running time t; According to the graph of the change of the single-chip voltage V with the running time t, the running time t corresponding to the hydrogen permeation current of the fuel cell system is determined, and the mass flow rate Q of the air entering the stack corresponding to the running time t is calculated. air , calculate the hydrogen permeation current; Determine whether the hydrogen permeation current exceeds the safe value and whether the fuel cell system needs to be shut down for maintenance.

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

3. The method for online fault diagnosis of hydrogen permeation current of a fuel cell system according to claim 2, characterized in that: When the fuel cell system performs the online fault diagnosis procedure of hydrogen permeation current, first reduce the speed of the air compressor to the minimum speed N0; When the speed of the air compressor reaches the minimum speed N0, the second solenoid valve is opened and the first solenoid valve is closed; the current single-chip voltage V is monitored by the single-chip voltage patrol device CVM. 0 , record the corresponding running time t 0 , at running time t 0 When the mass flow rate of air entering the stack is recorded as 4. The method for online fault diagnosis of hydrogen permeation current of a fuel cell system according to claim 3, characterized in that: The mass flow rate Q of the air entering the stack is gradually reduced. air , as follows: By adjusting the duty cycle signal of the second solenoid valve, the opening of the second solenoid valve is gradually reduced. Each time the adjustment is made, the current single-chip voltage V is monitored by the single-chip voltage monitor CVM. n , record the corresponding running time t n , plot the change of single chip voltage V with running time t; when the running time is t n When the mass flow rate of air entering the stack is recorded as 5. The method for online fault diagnosis of hydrogen permeation current of a fuel cell system according to claim 4, characterized in that: When the voltage V of the single chip shows a sudden drop in the graph of the change of the running time t, and the single chip voltage monitor CVM detects that the single chip voltage value drops to about 0.1, according to the mass flow rate Q of the air entering the stack at this time air The calculated corresponding working current I of the fuel cell stack is the hydrogen permeation current.

6. The method for online fault diagnosis of hydrogen permeation current of a fuel cell system according to claim 5, characterized in that: The mass flow rate Q of the air entering the stack at this time air The calculated working current I of the fuel cell stack is as follows: When hydrogen permeates through the proton exchange membrane to the air side, an electrochemical reaction occurs, satisfying Faraday's law: I=0.21*4F*Q air ; In the formula, Q air is the mass flow rate of air entering the reactor; F is the Faraday constant; I is the working current; A mass flow meter is arranged on the bypass pipe; the mass flow meter is used to measure the mass flow rate Q of the air entering the stack. air .

7. The method for online fault diagnosis of hydrogen permeation current of a fuel cell system according to claim 6, characterized in that: The determination of whether the hydrogen permeation current exceeds the safety value and whether the fuel cell system needs to be shut down for maintenance are as follows: The safe value of hydrogen permeation current of proton exchange membrane is I lim , when the calculated real-time hydrogen permeation current is less than or equal to I lim When the real-time hydrogen permeation current is greater than I lim The fuel cell system is shut down for maintenance.

8. The method for online fault diagnosis of hydrogen permeation current of a fuel cell system according to claim 7, characterized in that: When the real-time hydrogen permeation current is greater than I lim When the mass flow rate Q of air entering the reactor is gradually reduced, air If the single-chip voltage monitor CVM detects that the single-chip voltage value of other single-chip batteries drops suddenly to about 0.1, the hydrogen permeation current of the corresponding single-chip battery is calculated and compared with the safety value of the hydrogen permeation current I lim Compare and determine whether the corresponding single-chip battery needs to be shut down for maintenance; When the mass flow rate of air entering the reactor is Q air When the air mass flow rate is reduced to the minimum, the detection is stopped.

9. An online fault diagnosis system for hydrogen permeation current of a fuel cell system, characterized in that: The online fault diagnosis system comprises: Detection module: a bypass pipe is provided 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 provided 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 provided 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: The mass flow meter is used to measure the mass flow of air entering the stack; the single-chip voltage monitor CVM is used to measure the single-chip voltage; the time recorder records the corresponding operating time; Calculation module: used to draw a graph of the change of the single chip voltage over the running time according to the data obtained by the data acquisition module; and calculate the hydrogen permeation current; Judgment module: used to judge whether the hydrogen permeation current exceeds the safety value and determine whether the fuel cell system needs to be shut down for maintenance.

10. An electronic device, characterized in that: It comprises 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 online fault diagnosis method of the hydrogen permeation current of the fuel cell system as described in any one of claims 1 to 8.

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