Fuel cell system air pressure insufficiency fault diagnosis method and system

Abstract

The invention discloses a fuel cell system air pressure insufficiency fault diagnosis method and system, and the method comprises the steps: judging a fault position according to an electric pile inlet and outlet air pressure difference, a preset pressure error and a calibration pressure difference; when the fault is located at the front end of the galvanic pile, judging that the fault is located at the front end of an air compressor, an air compressor-galvanic pile end or a galvanic pile body according to the first air flow, the calibrated flow and a preset air flow error in a preset mode, and judging a fault reason according to a preset rule; when the fault is located at the rear end of the electric pile, according to the error between the actual opening degree of the back pressure valve and the instruction opening degree of the back pressure valve and the preset opening degree error range, it is judged that the fault reason is a back pressure valve control fault, electric pile-back pressure valve pipeline leakage or back pressure valve connector leakage. By structuring the fault diagnosis process, the direction of fault diagnosis is defined, the fault point can be accurately positioned, unnecessary inspection in the diagnosis process is reduced, the fault diagnosis time can be effectively shortened, and the diagnosis efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery management, in particular to a fuel cell system air pressure deficiency fault diagnosis method and system. BACKGROUND

[0002] The air subsystem in the fuel cell system is a core functional module, which mainly provides clean air with appropriate flow rate, temperature, pressure and humidity for the stack. The conventional air subsystem mainly includes several core components such as an air filter, an air compressor, an intercooler, a humidifier and a throttle valve, and the weight of the air subsystem accounts for about 20% of the total weight of the fuel cell system, and the power consumption accounts for 20-25% of the system output power. Among them, the air compressor, the humidifier and the valve are key components, which directly affect the power performance, economy and reliability of the fuel cell. The stability of the air pressure directly affects the performance of the stack: the air subsystem provides appropriate inlet pressure for the stack, and increasing the inlet pressure (i.e. the outlet pressure of the air compressor) will increase the oxygen partial pressure, especially when the fuel cell works in the high load range, which will also increase the cell voltage. After the system has been subjected to long-term durability conditions, if it is found that the air pressure cannot reach the appropriate pressure of the stack, the cell voltage will decrease, the stack output voltage will decrease, and the system power performance and system efficiency will be affected.

[0003] Since the air subsystem is a complex gas path system including multiple components, when the system has an insufficient inlet pressure fault after long-term operation, there are many possible causes for the fault, which makes it difficult to troubleshoot the fault cause, and it is difficult to quickly determine the specific fault point, thereby causing the fault diagnosis process to be time-consuming and inefficient. SUMMARY

[0004] The present application provides a fuel cell system air pressure deficiency fault diagnosis method and system, which can solve the technical problem of long time-consuming and low efficiency of fault diagnosis when the battery system has an insufficient inlet pressure fault.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a fuel cell system air pressure deficiency fault diagnosis method, the method comprising: According to the air pressure difference between the inlet and outlet of the stack, the preset pressure error and the calibrated pressure difference, the fault position is determined.

[0006] When the fault is located at the front end of the stack, according to the first air flow rate in the preset mode, the calibrated flow rate and the preset air flow rate error, the fault is determined to be located at the front end of the air compressor, the air compressor-stack end or the stack body, and the fault cause is determined according to the preset rule.

[0007] When the fault is located at the rear end of the stack, according to the error between the actual opening of the back pressure valve and the command opening of the back pressure valve, and the preset opening error range, the fault cause is determined as a back pressure valve control fault, a stack-back pressure valve pipeline leakage, or a leakage at the joint of the back pressure valve.

[0008] Further, in an embodiment, according to the air pressure difference between the stack inlet and outlet, the preset pressure error, and the calibrated pressure difference, the fault location is determined, including: When the sum of the air pressure difference between the stack inlet and outlet and the preset pressure error is less than the calibrated pressure difference, the fault is located at the front end of the stack.

[0009] When the sum of the air pressure difference between the stack inlet and outlet and the preset pressure error is greater than the calibrated pressure difference, the fault is located at the rear end of the stack.

[0010] The air pressure difference between the stack inlet and outlet is the difference between the first stack inlet air pressure and the stack outlet air pressure when the air pressure of the fuel cell system is less than the preset air pressure threshold.

[0011] Further, in an embodiment, the preset mode is: The air compressor is controlled to operate at a preset speed, the bypass valve is opened, and the shut-off valve is closed.

[0012] Further, in an embodiment, according to the first air flow, the calibrated flow, and the preset air flow error in the preset mode, the fault is determined to be located at the front end of the air compressor, the air compressor-stack end, or the stack body, including: When the sum of the first air flow and the preset air flow error is less than the calibrated flow, the fault is located at the front end of the air compressor.

[0013] When the difference between the first air flow and the preset air flow error is greater than the calibrated flow, the fault is located at the air compressor-stack end.

[0014] When the difference between the first air flow and the preset air flow error is less than the calibrated flow, and the sum of the first air flow and the preset air flow error is greater than the calibrated flow, the fault is located at the stack body.

[0015] Further, in an embodiment, the fault cause is determined according to the preset rule, including: When the fault is located at the front end of the air compressor, the second stack inlet air pressure after the air filter is removed is obtained, and when it is less than the calibrated inlet air pressure, the fault cause is an air filter blockage.

[0016] The air compressor speed and the second air flow after the air inlet stack pipeline is removed are obtained, a calibrated air compressor speed-air flow corresponding relationship table is searched, the corresponding air flow is found, and if the error between the air flow and the second air flow is within the preset flow error range, the fault cause is a humidifier internal leakage.

[0017] If the absolute value of the difference between the first air flow rate obtained after replacement and the calibrated flow rate is less than the preset air flow rate error, the cause of the fault is that the air flow meter is faulty.

[0018] Furthermore, in one embodiment, determining the cause of the fault according to preset rules includes: When the fault is located at the air compressor-fuel stack end, close all valves in the air circuit, control the air compressor to run at the preset speed, and obtain the third air flow at this time. When it is greater than the surge flow corresponding to the preset speed, the fault is caused by a leak in the air circuit.

[0019] Disconnect the air outlet pipe and control the air compressor to run at the preset speed. When gas flow is detected in the outlet pipe, the cause of the fault is internal leakage of the humidifier.

[0020] Disconnect the bypass valve outlet line, close the bypass valve, and control the air compressor to run at the preset speed. When gas flow is detected in the outlet line, the cause of the fault is leakage in the bypass valve.

[0021] Furthermore, in one embodiment, the surge flow rate corresponding to the preset rotational speed is obtained by looking up a correspondence table of rotational speed and surge flow rate, which is obtained through a surge flow rate test experiment.

[0022] Furthermore, in one embodiment, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, and a preset opening degree error range, the cause of the fault is determined to be a back pressure valve control fault, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint, including: When the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve is outside the preset opening degree error range, the cause of the fault is a back pressure valve control fault.

[0023] When the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve is within the preset opening degree error range and is greater than 0, the cause of the fault is leakage in the fuel cell stack-back pressure valve pipeline or leakage at the back pressure valve joint.

[0024] Furthermore, in one embodiment, the cause of leakage in the fuel cell stack-back pressure valve pipeline is determined as follows: the clamp connection of the pipeline is loose, or the pipeline body is damaged.

[0025] The cause of the leakage at the back pressure valve joint is determined to be: the sealing ring at the joint has fallen off.

[0026] Secondly, based on the above-mentioned method for diagnosing insufficient air pressure in a fuel cell system, this application provides a diagnostic system for diagnosing insufficient air pressure in a fuel cell system, the system comprising: The fault location module is used to determine the fault location based on the air pressure difference between the fuel cell stack inlet and outlet, the preset pressure error, and the calibrated pressure difference.

[0027] The fuel cell stack front-end fault module is used to determine whether the fault is located at the front end of the air compressor, the air compressor-fuel cell stack end, or the fuel cell stack body when the fault is located at the front end of the fuel cell stack, based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error in the preset mode, and to determine the cause of the fault according to preset rules.

[0028] The fuel cell stack back-end fault module is used to determine the cause of the fault when the fault is located at the back end of the fuel cell stack, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range. The fault could be a back pressure valve control fault, fuel cell stack-back pressure valve pipeline leakage, or back pressure valve joint leakage.

[0029] The beneficial effects of the technical solutions provided in this application include: This application addresses the issue of insufficient air pressure in fuel cell systems by using the fuel cell stack as a fault demarcation point. It breaks down the fault diagnosis into two parts: front-end fault diagnosis and back-end fault diagnosis. When the fault is located at the front end of the stack, it further categorizes it into air compressor front-end faults, air compressor-stack end faults, and stack body faults, analyzing the causes of these corresponding fault locations. Specifically, it determines whether the fault is due to a back pressure valve control malfunction, leakage in the stack-back pressure valve pipeline, or leakage at the back pressure valve connector. By structuring the fault diagnosis process, the direction of fault diagnosis is clarified, avoiding blind troubleshooting in complex fuel cell systems. This allows for precise fault location, reduces unnecessary checks during diagnosis, and effectively shortens diagnosis time and improves diagnostic efficiency. Attached Figure Description

[0030] Figure 1 This is a flowchart of a method for diagnosing insufficient air pressure in a fuel cell system according to an embodiment of this application.

[0031] Figure 2 This is a block diagram of a fault diagnosis system for insufficient air pressure in a fuel cell system according to an embodiment of this application.

[0032] Figure 3 This is a schematic diagram showing the connection relationship between the air subsystem and the fuel cell stack in this application. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0034] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0035] (1) Air Subsystem: The air subsystem primarily provides the air required for the fuel cell to operate, ensuring adequate airflow and pressure. A typical air subsystem generally includes an air filter, air flow meter, air compressor, intercooler, humidifier, back pressure valve, bypass valve, and shut-off valve. The air subsystem connects to the fuel cell stack, providing a stable gas supply, thermal management, and energy management to ensure stable and normal operation of the fuel cell. See details... Figure 3 As shown, Figure 3 This is a schematic diagram showing the connection between the air subsystem and the fuel cell stack.

[0036] The system includes a humidifier connected to the fuel cell stack via two shut-off valves to humidify the incoming dry air and improve gas utilization efficiency; an intercooler connected to the humidifier to lower the temperature of the incoming air, preventing damage to the membrane electrode assembly (MEA) from high-temperature air, while also providing cooling and humidification; an air compressor connected to the intercooler to provide suitable compressed air for the fuel cell, making it the core component of the air circuit system; an air filter connected to the air compressor with a flow meter between them, used to remove dust and harmful substances from the air; a back pressure valve installed at the fuel cell stack outlet, connected to the humidifier, and working with the air compressor to regulate the airflow and pressure within the fuel cell stack; and a bypass valve connected between the branch outlet of the intercooler and the branch outlet of the back pressure valve to assist in regulating the airflow and humidity of the main circuit.

[0037] (2) BOP: Balance of Plant, refers to all components other than the fuel cell stack, including hydrogen storage tank, oxygen storage tank, hydrogen and oxygen supply system, battery control system, cooling system, battery heating system, battery emission system, etc. The role of BOP is to ensure the normal operation of fuel cell vehicles, guarantee the supply of hydrogen and oxygen, battery temperature control, battery protection, etc.

[0038] Since low air pressure can be caused by various factors, such as a malfunctioning air compressor, leaks in the humidifier or back pressure valve, problems with the sensors and flow meters, sealing failures in the fuel cell stack itself, or sealing failures in the piping or assembly, the causes of the problem are numerous and difficult to diagnose. Therefore, this application proposes a method for diagnosing insufficient air pressure in a fuel cell system, which decomposes the problem into two parts: a problem at the front end or the back end of the fuel cell stack. The front end is further divided into the air compressor front end, the air compressor-fuel cell stack end, and the fuel cell stack itself.

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0040] In a first aspect, embodiments of this application provide a method for diagnosing insufficient air pressure in a fuel cell system, the method comprising: The location of the fault is determined based on the air pressure difference between the inlet and outlet of the fuel cell stack, the preset pressure error, and the calibrated pressure difference.

[0041] When the fault is located at the front end of the fuel cell stack, the fault is determined to be located at the front end of the air compressor, the air compressor-fuel cell stack end, or the fuel cell stack body based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error in the preset mode, and the cause of the fault is determined according to the preset rules.

[0042] When the fault is located at the rear end of the fuel cell stack, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range, the cause of the fault is determined to be a back pressure valve control fault, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint.

[0043] All calibrations in this application are pre-set based on fault diagnosis experience.

[0044] This application addresses the issue of insufficient air pressure in fuel cell systems by dividing the fault diagnosis into two parts: a front-end and a back-end, with the fuel cell stack as the boundary. The front-end uses parameters such as differential pressure and flow rate to precisely pinpoint the fault to the air compressor front end, the air compressor-fuel cell stack end, or the fuel cell stack itself, directly linking the cause of the fault. The back-end quickly distinguishes between control faults, pipeline leaks, or joint leaks based on the back pressure valve opening error. This structured approach narrows the scope of investigation, avoids blind inspections, significantly shortens diagnostic time, and improves fault diagnosis efficiency.

[0045] In one embodiment, see Figure 1 As shown, a specific embodiment of the above-mentioned fault diagnosis method is provided. In this embodiment, the fault diagnosis method includes the following steps: S1. Determine the fault location based on the air pressure difference between the inlet and outlet of the fuel cell stack, the preset pressure error, and the calibrated pressure difference. If the fault is located at the front end of the fuel cell stack, proceed to step S2. If the fault is located at the rear end of the fuel cell stack, proceed to step S3.

[0046] S2. Based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error in the preset mode, determine whether the fault is located at the front end of the air compressor, the air compressor-fuel stack end, or the fuel stack body, and determine the cause of the fault according to the preset rules.

[0047] S3. Based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range, determine the cause of the fault as a back pressure valve control fault, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint.

[0048] Furthermore, in one embodiment, in step S1 above, the fault location is determined based on the air pressure difference between the fuel cell stack inlet and outlet, the preset pressure error, and the calibrated pressure difference. The specific determination method is as follows: Calculate the sum of the air pressure difference between the fuel cell stack inlet and outlet and the preset pressure error. By comparing the sum of the air pressure difference between the fuel cell stack inlet and outlet and the preset pressure error with the calibrated pressure difference, determine whether the fault is located at the front or rear of the fuel cell stack, as follows: When the sum of the air pressure difference between the inlet and outlet of the fuel cell stack and the preset pressure error is less than the calibrated pressure difference, the fault is located at the front of the fuel cell stack; when the sum of the air pressure difference between the inlet and outlet of the fuel cell stack and the preset pressure error is greater than the calibrated pressure difference, the fault is located at the rear of the fuel cell stack.

[0049] The air pressure difference between the inlet and outlet of the fuel cell stack is the difference between the air pressure at the inlet of the first fuel cell stack and the air pressure at the outlet of the fuel cell stack when the air pressure of the fuel cell system is less than a preset air pressure threshold.

[0050] In this embodiment, by quantitatively comparing the sum of the air pressure difference between the inlet and outlet of the fuel cell stack and the preset pressure error with the calibrated pressure difference, a simple and unique boundary criterion is formed. This enables accurate determination of whether the fault is located at the front or rear end of the fuel cell stack with only one calculation, avoiding complex multi-parameter coupling judgments. This significantly improves the real-time performance and accuracy of fault location, laying a reliable foundation for subsequent detailed diagnosis by modules.

[0051] Furthermore, in one embodiment, in step S2 above, based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error under the preset mode, it is determined whether the fault is located at the front end of the air compressor, the air compressor-fuel stack end, or the fuel stack body. The specific determination method is as follows: Calculate the sum of the errors between the first air flow rate and the preset air flow rate, and the difference between the first air flow rate and the preset air flow rate error. By comparing the sum of the air pressure difference between the fuel cell inlet and outlet and the preset pressure error with the calibrated flow rate, and the difference between the first air flow rate and the preset air flow rate error with the calibrated flow rate, determine whether the fault is located at the air compressor front end, the air compressor-fuel cell end, or the fuel cell body, as follows: When the sum of the errors between the first air flow rate and the preset air flow rate is less than the calibrated flow rate, the fault is located at the front end of the air compressor; when the difference between the errors between the first air flow rate and the preset air flow rate is greater than the calibrated flow rate, the fault is located at the air compressor-fuel stack end; when the difference between the errors between the first air flow rate and the preset air flow rate is less than the calibrated flow rate, and the sum of the errors between the first air flow rate and the preset air flow rate is greater than the calibrated flow rate, the fault is located in the fuel stack body.

[0052] In this embodiment, the aforementioned preset mode is as follows: when step S1 determines that the fault is located at the front end of the motor, the air compressor is controlled to run at a preset speed, the bypass valve is opened, and the shut-off valve is closed. This embodiment locks the air compressor's operating point to a known operating condition, eliminating interference from downstream components such as the throttle valve and back pressure valve, so that the first air flow is only related to the resistance of the front end and the fuel cell stack body. Subsequently, by using a triple comparison of the flow rate-error window and the calibrated flow rate, faults at the air compressor front end, the air compressor-fuel cell stack end, and the fuel cell stack body can be distinguished in one operation with only one calculation. The diagnostic logic is clear, the calculation load is small, and the front-end fault location time is significantly shortened and the accuracy is improved. In addition, in this application, all preset speeds are preset based on the maximum speed of the air compressor, and the preset speeds are the same.

[0053] Furthermore, in one embodiment, in step S2 above, the cause of the fault is determined according to preset rules, and the cause of the fault is determined for two cases: the fault is located at the front end of the air compressor and the fault is located at the air compressor-fuel stack end. The specific determination method is as follows: (1) When the fault is located at the front end of the air compressor: Obtain the inlet air pressure of the second fuel cell stack after the air filter is removed. If it is lower than the calibrated inlet air pressure, the cause of the fault is air filter blockage.

[0054] Obtain the compressor speed and second air flow rate after disconnecting the air inlet pipe. Consult the calibrated compressor speed-air flow rate correspondence table to find the corresponding air flow rate. If the error between this air flow rate and the second air flow rate is within the preset flow rate error range, the fault is internal leakage in the humidifier.

[0055] If the absolute value of the difference between the first air flow rate obtained after replacement and the calibrated flow rate is less than the preset air flow rate error, the cause of the fault is that the air flow meter is faulty.

[0056] (2) When the fault is located at the air compressor-fuel stack end: With all valves in the air circuit closed, the air compressor is operated at a preset speed. The third air flow rate is then measured. If this third air flow rate exceeds the surge flow rate corresponding to the preset speed, the fault is a leak in the air circuit. The surge flow rate corresponding to the preset speed is obtained by consulting a speed-surge flow rate correspondence table, which can be obtained through surge flow rate testing experiments.

[0057] Disconnect the air outlet pipe and control the air compressor to run at the preset speed. When gas flow is detected in the outlet pipe, the cause of the fault is internal leakage of the humidifier.

[0058] Disconnect the bypass valve outlet line, close the bypass valve, and control the air compressor to run at the preset speed. When gas flow is detected in the outlet line, the cause of the fault is leakage in the bypass valve.

[0059] In this embodiment, the air filter blockage is quickly identified by comparing the pressure after removal; then, the internal leakage of the humidifier is accurately identified by comparing the compressor speed-flow calibration table with the measured values; finally, sensor drift is ruled out by replacing the air flow meter with an absolute error test. Simultaneously, a "valve-closed pressure holding + flow threshold" strategy is adopted at the compressor-fuel stack end, allowing for the determination of overall circuit leakage in a single run, and confirming single-point leakage in the humidifier or bypass valve by segmented pipe disassembly. The entire diagnostic method requires only conventional tools and preset calibration data, without the need for additional sensors. The diagnostic steps are logically clear and quick to operate, significantly reducing misjudgments and repeated disassembly / reassembly, and greatly improving the efficiency of troubleshooting complex air circuit faults after long-term operation.

[0060] Furthermore, in one embodiment, in step S3 above, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range, the cause of the fault is determined to be a back pressure valve control fault, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint. The specific determination method is as follows: Calculate the error between the actual opening degree of the back pressure valve and the commanded opening degree. By comparing this error with the preset opening degree error range, determine the cause of the fault: back pressure valve control failure, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint. Details are as follows: When the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve is outside the preset opening degree error range, the cause of the fault is a back pressure valve control fault.

[0061] When the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve is within the preset opening degree error range and is greater than 0, the cause of the fault is leakage in the fuel cell stack-back pressure valve pipeline or leakage at the back pressure valve joint.

[0062] In this embodiment, a single comparison of opening errors can quickly separate back pressure valve control faults from downstream leakage faults, thus shortening the time for locating downstream faults. The causes of leakage faults in the fuel cell stack-back pressure valve pipeline include: loosening of the pipeline clamp connection or damage to the pipeline body; the causes of leakage at the back pressure valve joint include: the sealing ring at the joint falling off.

[0063] Secondly, based on the embodiments of the above-mentioned fuel cell system insufficient air pressure fault diagnosis method, an embodiment of a fuel cell system insufficient air pressure fault diagnosis system is provided, see [link to embodiment]. Figure 2 As shown, the diagnostic system includes a fault location module, a fuel cell front-end fault module, and a fuel cell back-end fault module, specifically: The fault location module is used to determine the fault location based on the air pressure difference between the fuel cell stack inlet and outlet, the preset pressure error, and the calibrated pressure difference.

[0064] The fuel cell stack front-end fault module is used to determine whether the fault is located at the front end of the air compressor, the air compressor-fuel cell stack end, or the fuel cell stack body when the fault is located at the front end of the fuel cell stack, based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error in the preset mode, and to determine the cause of the fault according to preset rules.

[0065] The fuel cell stack back-end fault module is used to determine the cause of the fault when the fault is located at the back end of the fuel cell stack, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range. The fault could be a back pressure valve control fault, fuel cell stack-back pressure valve pipeline leakage, or back pressure valve joint leakage.

[0066] This application uses the fuel cell stack as the physical and logical boundary, dividing complex gas path faults into two independent diagnostic domains: the front end and the back end. Then, by utilizing triple threshold comparisons of differential pressure-error criteria, flow rate-error window, and back pressure valve opening error, it achieves one-time, unambiguous localization of typical faults such as compressor front-end blockage, compressor-fuel cell stack leakage, fuel cell stack blockage, back pressure valve control failure, and downstream leakage. The entire method requires only existing onboard sensors and conventional disassembly tools, requiring no additional hardware investment to complete diagnosis in a short time. Compared to traditional traversal troubleshooting, it significantly reduces localization time, lowers after-sales maintenance costs and downtime losses, and can be directly embedded into existing fuel cell controllers for mass deployment via software updates, demonstrating strong engineering feasibility and promotional value.

[0067] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0068] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0069] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0070] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0071] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0072] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0073] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for diagnosing insufficient air pressure in a fuel cell system, characterized in that, The method includes: Determine the location of the fault based on the air pressure difference between the fuel cell stack inlet and outlet, the preset pressure error, and the calibrated pressure difference; When the fault is located at the front end of the fuel cell stack, the first air flow, the calibrated flow, and the preset air flow error in the preset mode are used to determine whether the fault is located at the front end of the air compressor, the air compressor-fuel cell stack end, or the fuel cell stack body, and the cause of the fault is determined according to the preset rules. When the fault is located at the rear end of the fuel cell stack, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range, the cause of the fault is determined to be a back pressure valve control fault, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint.

2. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 1, characterized in that, Based on the air pressure difference between the fuel cell stack inlet and outlet, the preset pressure error, and the calibrated pressure difference, the location of the fault is determined, including: When the sum of the air pressure difference between the fuel cell stack inlet and outlet and the preset pressure error is less than the calibrated pressure difference, the fault is located at the front end of the fuel cell stack. When the sum of the air pressure difference between the fuel cell stack inlet and outlet and the preset pressure error is greater than the calibrated pressure difference, the fault is located at the rear end of the fuel cell stack. The air pressure difference between the inlet and outlet of the fuel cell stack is the difference between the air pressure at the inlet of the first fuel cell stack and the air pressure at the outlet of the fuel cell stack when the air pressure of the fuel cell system is less than a preset air pressure threshold.

3. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 1, characterized in that, The preset mode is: Control the air compressor to run at a preset speed, open the bypass valve and close the shut-off valve.

4. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 3, characterized in that, Based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error in the preset mode, the fault is determined to be located at the front end of the air compressor, the air compressor-fuel stack end, or the fuel stack itself, including: When the sum of the errors between the first air flow rate and the preset air flow rate is less than the calibrated flow rate, the fault is located at the front end of the air compressor. When the difference between the first air flow rate and the preset air flow rate is greater than the calibrated flow rate, the fault is located at the air compressor-fuel stack end; When the difference between the first air flow rate and the preset air flow rate is less than the rated flow rate, and the sum of the errors between the first air flow rate and the preset air flow rate is greater than the rated flow rate, the fault is located in the fuel cell stack body.

5. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 1, characterized in that, The step of determining the cause of the fault according to preset rules includes: When the fault is located at the front end of the air compressor, obtain the inlet air pressure of the second fuel cell after removing the air filter. If it is less than the rated inlet air pressure, the cause of the fault is air filter blockage. Obtain the compressor speed and second air flow rate after disconnecting the air inlet pipe. Look up the calibrated compressor speed-air flow rate correspondence table to find the corresponding air flow rate. If the error between the air flow rate and the second air flow rate is within the preset flow rate error range, the cause of the fault is internal leakage of the humidifier. If the absolute value of the difference between the first air flow rate obtained after replacement and the calibrated flow rate is less than the preset air flow rate error, the cause of the fault is that the air flow meter is faulty.

6. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 1, characterized in that, The cause of the fault is determined according to preset rules, including: When the fault is located at the air compressor-fuel stack end, close all valves in the air circuit, control the air compressor to run at the preset speed, and obtain the third air flow at this time. When it is greater than the surge flow corresponding to the preset speed, the cause of the fault is that there is a leak in the air circuit. Disconnect the air outlet pipeline and control the air compressor to run at the preset speed. When gas flow is detected in the outlet pipeline, the cause of the fault is internal leakage of the humidifier. Disconnect the bypass valve outlet line, close the bypass valve, and control the air compressor to run at the preset speed. When gas flow is detected in the outlet line, the cause of the fault is leakage in the bypass valve.

7. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 6, characterized in that, The surge flow rate corresponding to the preset rotational speed is obtained by looking up the correspondence table between rotational speed and surge flow rate, which is obtained through surge flow rate test experiments.

8. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 1, characterized in that, Based on the error between the actual opening degree of the back pressure valve and the commanded opening degree, as well as the preset opening degree error range, the cause of the fault is determined to be a back pressure valve control malfunction, leakage in the fuel cell stack-back pressure valve pipeline, or leakage at the back pressure valve joint, including: When the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve is outside the preset opening degree error range, the cause of the fault is a back pressure valve control fault. When the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve is within the preset opening degree error range and is greater than 0, the cause of the fault is leakage in the fuel cell stack-back pressure valve pipeline or leakage at the back pressure valve joint.

9. The method for diagnosing insufficient air pressure in a fuel cell system as described in claim 8, characterized in that, The cause of leakage in the fuel cell stack-back pressure valve pipeline is determined to be: loose clamp connections or damage to the pipeline itself. The cause of the leakage at the back pressure valve joint is determined to be: the sealing ring at the joint has fallen off.

10. A diagnostic system based on the method for diagnosing insufficient air pressure in a fuel cell system according to any one of claims 1-9, characterized in that, The system includes: The fault location module is used to determine the fault location based on the air pressure difference between the fuel cell stack inlet and outlet, the preset pressure error, and the calibrated pressure difference. The fuel cell stack front-end fault module is used to determine whether the fault is located at the front end of the air compressor, the air compressor-fuel cell stack end, or the fuel cell stack body when the fault is located at the front end of the fuel cell stack, based on the first air flow rate, the calibrated flow rate, and the preset air flow rate error in the preset mode, and to determine the cause of the fault according to preset rules. The fuel cell stack back-end fault module is used to determine the cause of the fault when the fault is located at the back end of the fuel cell stack, based on the error between the actual opening degree of the back pressure valve and the commanded opening degree of the back pressure valve, as well as the preset opening degree error range. The fault could be a back pressure valve control fault, fuel cell stack-back pressure valve pipeline leakage, or back pressure valve joint leakage.

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