Fuel cell system and fault judgment method and device thereof

Abstract

The invention provides a fuel cell system and a fault judgment method and device thereof.The fault judgment method of the fuel cell system comprises the steps that the average voltage of all single cells in an electric pile is obtained; when the obtained average voltage is smaller than a preset voltage threshold value under the current pile current density, timing the duration that the average voltage is continuously smaller than the preset voltage threshold value; and when the timing duration is greater than the first preset duration, determining that the fuel cell system is suspected to have a cathode gas shortage fault. According to the invention, when the fuel cell system has the fault of voltage reduction, the system can automatically judge the fault position, so that the fault judgment efficiency can be improved, and unnecessary time and manpower waste can be avoided.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for diagnosing faults in a fuel cell system. The invention also relates to a fuel cell system fault diagnosis device for implementing the above-described method, and a fuel cell system capable of implementing the above-described method. Background Technology

[0002] During operation, fuel cell systems sometimes inevitably experience malfunctions. Taking a cathode-side air intake failure as an example, a reduction in the amount of air entering the cathode can affect the stack's performance and, in severe cases, even lead to system shutdown. There are many reasons for a reduction in the amount of air entering the cathode, and these reasons are usually closely related to the components on the cathode side.

[0003] Currently, for intake faults on the cathode side of fuel cell systems, the general approach is to manually check each component step by step when the stack voltage drops. This involves investigating all possible locations on the cathode side, and sometimes even disassembling components to determine the final cause. This existing fault diagnosis method is clearly inefficient and inevitably wastes unnecessary time and manpower, hindering the proper handling of fuel cell system faults. Summary of the Invention

[0004] In view of this, the present invention aims to propose a method for fault diagnosis of fuel cell systems, which can improve the efficiency of fault diagnosis and avoid unnecessary waste of time and manpower.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for diagnosing faults in a fuel cell system, the method comprising:

[0007] Obtain the average voltage of all individual cells in the fuel cell stack;

[0008] When the average voltage is less than a preset voltage threshold under the current stack voltage density, the duration for which the average voltage remains less than the preset voltage threshold is timed.

[0009] If the timing duration exceeds the first preset duration, it is determined that the fuel cell system is suspected of having a cathode undergassing fault.

[0010] Furthermore, when it is determined that the fuel cell system is suspected of having a cathode undergassing fault, the method further includes:

[0011] The stack density is gradually reduced according to a preset density gradient, and after each reduction to the corresponding stack density, a second preset time is waited before the current average voltage of all individual cells is obtained.

[0012] Wherein, when the current average voltage is still less than the preset voltage threshold under the corresponding stack density, the stack density continues to be reduced according to the preset density gradient. When the stack density is reduced to the minimum density and the current average voltage is still less than the preset voltage threshold under the corresponding stack density, it is determined that the fuel cell system has a cathode undergassing fault.

[0013] Specifically, when the current average voltage is not less than the preset voltage threshold under the corresponding stack voltage density, the reduction of stack voltage density is stopped, and it is determined that there is no cathode undergassing fault in the fuel cell system.

[0014] Furthermore, when it is determined that there is a cathode undergassing fault in the fuel cell system, the method further includes:

[0015] Obtain the air intake flow rate on the inlet side of the air compressor;

[0016] When the obtained intake air flow rate is less than the preset flow rate threshold under the corresponding stack electrical density, it is determined that there is an intake air flow fault in the fuel cell system.

[0017] When the obtained air intake flow rate is equal to the preset flow rate threshold under the corresponding stack electrical density, it is determined that there is a gas leakage fault at the front end of the stack cathode inlet in the fuel cell system.

[0018] The air intake flow fault includes at least one fault in the air compressor, back pressure valve, and air filter; the fuel cell cathode inlet front-end leakage fault includes at least one fault in the humidifier and bypass valve.

[0019] Furthermore, when it is determined that there is an intake flow fault in the fuel cell system, the method includes:

[0020] Obtain the rotational speed fed back by the air compressor;

[0021] If the speed feedback from the air compressor is not equal to the preset speed threshold under the corresponding fuel cell density, it is determined that the air compressor has a fault.

[0022] When the obtained rotational speed is equal to the preset rotational speed threshold under the corresponding fuel cell density, it is determined that the air compressor is not faulty.

[0023] Furthermore, when it is determined that the air compressor is not faulty, the method further includes:

[0024] Obtain the opening degree fed back by the back pressure valve;

[0025] If the opening degree fed back by the back pressure valve is not equal to the first preset opening degree threshold under the corresponding fuel cell density, it is determined that the back pressure valve is faulty.

[0026] When the opening degree of the back pressure valve feedback is equal to the first preset opening degree threshold under the corresponding fuel cell density, it is determined that the air filter is faulty.

[0027] Furthermore, when it is determined that there is a gas leakage fault at the front end of the stack cathode inlet in the fuel cell system, the method further includes:

[0028] Obtain the opening value fed back by the bypass valve;

[0029] When the opening degree fed back by the bypass valve is not equal to the second preset opening degree threshold under the corresponding fuel cell density, it is determined that the bypass valve has a control failure fault.

[0030] Furthermore, when the obtained opening degree of the bypass valve feedback is equal to the second preset opening degree threshold under the corresponding stack electrical density, the method further includes:

[0031] Open the bypass valve to its minimum opening degree;

[0032] Get the current average voltage of all individual cells;

[0033] When the acquired average voltage drops, the bypass valve is closed, and the acquisition of the current average voltage of all individual cells continues.

[0034] When the acquired average voltage rises, it is determined that the humidifier is faulty.

[0035] Furthermore, when the obtained opening degree of the bypass valve feedback is equal to the second preset opening degree threshold under the corresponding stack electrical density, the method further includes:

[0036] Open the bypass valve to its minimum opening degree;

[0037] Get the current average voltage of all individual cells;

[0038] While the average voltage remains unchanged, the bypass valve is closed, and the current average voltage of all individual cells is acquired.

[0039] If the average voltage remains unchanged, it is determined that the bypass valve has a leakage fault.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] The fuel cell system fault diagnosis method of the present invention obtains the parameters of the fuel cell system during operation and compares the obtained parameters with preset parameter thresholds to diagnose the fault. When a voltage drop fault occurs in the fuel cell system, the system can automatically determine the fault location, thereby improving the fault diagnosis efficiency and avoiding unnecessary waste of time and manpower, which is conducive to the development of fuel cell system fault handling work.

[0042] This invention also proposes a fault diagnosis device for a fuel cell system, which includes an acquisition unit, a comparison unit, a timing unit, and a determination unit;

[0043] The acquisition unit is used to acquire the average voltage of all individual cells in the stack;

[0044] The comparison unit is used to compare the acquired average voltage with a preset voltage threshold under the current stack voltage density.

[0045] The timing unit is used to time the duration for which the average voltage is continuously less than the preset voltage threshold when the acquired average voltage is less than the preset voltage threshold under the current stack voltage density.

[0046] The determining unit is used to determine that the fuel cell system is suspected of having a cathode undergassing fault when the timing duration is longer than a first preset duration.

[0047] In addition, the present invention also proposes a fuel cell system, wherein an intake flow detection unit is provided on the cathode intake pipe of the fuel cell system between the air filter and the air compressor, and the intake flow detection unit is connected to the fuel cell controller in the fuel cell system.

[0048] The fuel cell controller is capable of executing the fuel cell system fault diagnosis method described above.

[0049] The fuel cell system fault diagnosis device and fuel cell system described in this invention have the same beneficial effects as the aforementioned fuel cell system fault diagnosis method compared to the prior art, and will not be repeated here. Attached Figure Description

[0050] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0051] Figure 1 This is a simplified structural diagram of the fuel cell system described in an embodiment of the present invention;

[0052] Figure 2 This is a flowchart of the fuel cell system fault diagnosis method according to an embodiment of the present invention;

[0053] Figure 3 This is a logic diagram of the fuel cell system fault judgment method described in an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of the structure of the fuel cell system fault diagnosis device according to an embodiment of the present invention;

[0055] Explanation of reference numerals in the attached figures:

[0056] 1. Fuel cell stack; 2. Air compressor; 3. Air filter; 4. Intercooler; 5. Humidifier; 6. Bypass valve; 7. Back pressure valve; 8. Rear shut-off valve; 9. Front shut-off valve; 10. Temperature sensor; 11. Pressure sensor; 12. Temperature sensor; 13. Inlet air flow detection unit; 14. Circulation pump; 15. Regulating valve; 16. Pressure sensor; 17. Pressure sensor; 18. Nitrogen purging valve; 19. Drain valve;

[0057] 100. Acquisition unit; 200. Comparison unit; 300. Timing unit; 400. Determining unit. Detailed Implementation

[0058] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0059] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0060] In the description of this invention, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer," indicating orientation or positional relationship, is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first" and "second" is also for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0061] Furthermore, in the description of this invention, unless otherwise explicitly specified, the connecting structures between mating components can be conventional in the art. Moreover, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0062] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0063] Example 1

[0064] This embodiment relates to a method for diagnosing faults in a fuel cell system. It is applicable to the diagnosis and handling of cathode air intake faults in a fuel cell system, and can improve the efficiency of fault diagnosis while avoiding unnecessary waste of time and manpower.

[0065] Among them, combined Figure 1 As shown in the figure, before introducing the fault judgment method of the fuel cell system in this embodiment, a brief description of the fuel cell system involved in this embodiment will be given first.

[0066] An air filter 3, an air compressor 2, an intercooler 4, a humidifier 5, a bypass valve 6, and a back pressure valve 7 are typically installed on the cathode side of a fuel cell system.

[0067] Air filter 3, air compressor 2, intercooler 4, and humidifier 5 are connected in sequence and located on the cathode inlet side of fuel cell stack 1. Air filter 3 is used to filter dust and other impurities in the air, providing clean air to fuel cell stack 1. Air compressor 2 is used to compress the air filtered by air filter 3, making it a high-temperature and high-pressure gas. Intercooler 4 is used to cool the air compressed by air compressor 2, and humidifier 5 is used to humidify the air entering fuel cell stack 1. Intercooler 4 and humidifier 5 together meet the temperature and humidity requirements of fuel cell stack 1 for cathode inlet air.

[0068] A pre-shutdown valve 9 is typically installed between the humidifier 5 and the cathode inlet of the fuel cell stack 1. A temperature sensor 10 and a pressure sensor 11 are also usually installed on the cathode inlet side of the fuel cell stack 1. The pre-shutdown valve 9 controls the flow of air into the cathode inlet side of the fuel cell stack 1, while the temperature sensor 10 and pressure sensor 11 detect the air inlet temperature and pressure at the cathode inlet side of the fuel cell stack 1, respectively.

[0069] A back shut-off valve 8 and a temperature sensor 12 are generally installed on the cathode outlet side of fuel cell stack 1. The back shut-off valve 8 is used to control the on / off of air outlet on the cathode outlet side of fuel cell stack 1, and the temperature sensor 12 is used to detect the outlet air temperature on the cathode outlet side of fuel cell stack 1. A back pressure valve 7 is used to create back pressure to regulate the outlet pressure of air compressor 2, so that the cathode inlet of fuel cell stack 1 forms the required air pressure. A bypass valve 6 is used to bypass part of the incoming air to prevent surge of air compressor 2, and is also used for bypass purging to adjust the exhaust hydrogen concentration during start-up and shutdown. In addition, an intake flow detection unit 13 is also installed between air filter 3 and air compressor 2. This intake flow detection unit 13 is used to detect the intake flow of air compressor 2, and it is generally sufficient to use a gas flow sensor.

[0070] Still Figure 1 As shown, a circulation pump 14, a regulating valve 15, a nitrogen purging valve 18, and a drain valve 19 are typically installed on the anode side of the fuel cell system. The circulation pump 14 is used to circulate hydrogen, the regulating valve 15 is used to control the hydrogen inlet flow rate, the nitrogen purging valve 18 is used to purge nitrogen and water, and the drain valve 19 is mainly used for drainage. In addition, pressure sensors 16 and 17 are generally installed on the anode inlet and outlet sides of the fuel cell stack 1, respectively, to detect the pressure on the anode inlet side and the pressure on the anode outlet side, respectively.

[0071] All components on the cathode side of the aforementioned fuel cell stack 1, as well as all components on the anode side of the fuel cell stack 1, are connected to the fuel cell controller (FCU) and operate under the control of the fuel cell controller to achieve the normal operation of the fuel cell system.

[0072] Based on the above description of the fuel cell system, in terms of overall design, combined with Figure 2 and Figure 3 As shown in the figure, the fault diagnosis method for the fuel cell system in this embodiment includes the following steps.

[0073] Step s1: Obtain the average voltage of all individual cells in stack 1.

[0074] In step s1, the average voltage of all individual cells in the stack 1 is obtained, for example, by summing the voltages of each individual cell measured by a CVM (Cell Voltage Monitor) and then dividing by the total number of individual cells.

[0075] Step s2: When the average voltage obtained is less than the preset voltage threshold under the current stack voltage density, the duration for which the average voltage is continuously less than the preset voltage threshold is timed.

[0076] In step s2, the preset voltage threshold under the current stack voltage density is different when the stack voltage density is different. Since the voltage of each cell in the stack is generally between 0.5V and 1.2V, in specific implementation, the preset voltage threshold under the current stack voltage density can be set based on the above voltage range, according to design needs, etc.

[0077] By obtaining the average voltage of all individual cells in fuel cell stack 1, if the obtained average voltage is less than the preset voltage threshold under the current stack voltage density, it indicates that a voltage drop fault in stack 1 may have occurred. However, since the cathode gas intake process in the fuel cell system requires a certain amount of time, and the gas intake also requires a certain amount of time to reach a stable state, it is necessary to time the duration for which the average voltage is continuously less than the preset voltage threshold to avoid misjudgment.

[0078] Step s3: When the timing duration exceeds the first preset duration, it is determined that the fuel cell system is suspected of having a cathode undergassing fault.

[0079] In step s3, if the duration for which the average voltage is continuously less than the preset voltage threshold is greater than the first preset duration, it indicates that when the voltage of the fuel cell stack 1 decreases, even if time is given to allow the cathode gas intake to stabilize, the voltage of the fuel cell stack 1 still decreases. At this time, it can be determined that the fuel cell system is suspected of having a cathode gas shortage fault.

[0080] The reason why it is said to be suspected of having a cathode gas shortage fault is that the voltage of fuel cell 1 has dropped. In addition to the cathode gas shortage (i.e., insufficient air intake on the cathode side of fuel cell 1), it may also be due to the performance degradation of fuel cell 1 and internal leakage of fuel cell 1. Therefore, before it is confirmed, it can be called suspected.

[0081] In practice, the first preset duration can be set based on the overall design of the fuel cell system, and it can be, for example, 10 seconds or other suitable time values.

[0082] Continue as Figure 3 As shown, when it is determined that the fuel cell system is suspected of having a cathode undergassing fault, the method of this embodiment further includes gradually reducing the stack density according to a preset density gradient, and after each reduction to the corresponding stack density, waiting for a second preset time period, and then obtaining the current average voltage of all individual cells.

[0083] The aforementioned preset electrical density gradient can be, for example, 0.1 electrical density. Of course, other electrical density values ​​can also be used depending on design requirements. In specific implementations, the aforementioned preset electrical density gradient can generally be selected between 0.1 and 0.5. When the current electrical density of fuel cell stack 1 is high and the method of this embodiment requires a faster judgment speed, a larger electrical density gradient value can be selected. Conversely, when the current electrical density of fuel cell stack 1 is low and a more accurate judgment is required, a smaller electrical density gradient value can be used.

[0084] The second preset duration mentioned above is generally 20 seconds. In addition to 20 seconds, other time values ​​can also be used depending on design requirements.

[0085] In this embodiment, the stack density is gradually reduced according to a preset density gradient as described above. After each reduction to the corresponding stack density, a second preset time is waited before acquiring the current average voltage of all individual cells. Specifically, during the reduction of the stack density according to the preset density gradient, if the acquired current average voltage is still lower than the preset voltage threshold for the corresponding stack density, the stack density is further reduced according to the preset density gradient. If the acquired current average voltage is not lower than the preset voltage threshold for the corresponding stack density, the reduction of the stack density is stopped, and it can be determined that the fuel cell system does not have a cathode undergassing fault; the voltage drop in stack 1 is due to performance degradation or internal leakage. However, if the stack density is reduced to the minimum density (typically 0.1), and the acquired average voltage is still lower than the preset voltage threshold for the corresponding stack density, meaning the voltage of stack 1 cannot recover, it can be determined that the fuel cell system has a cathode undergassing fault.

[0086] After confirming a cathode undergassing fault in the fuel cell system, it is necessary to further determine which specific component on the cathode side is malfunctioning. This process continues as follows: Figure 3 As shown, the method in this embodiment also includes obtaining the intake flow rate at the inlet side of the air compressor 2, and the intake flow rate can be obtained by the intake airflow detection unit 13 set as described above. At the same time, when the obtained intake flow rate is less than the preset flow rate threshold under the corresponding stack electrical density, it can be determined that there is an intake flow fault in the fuel cell system. When the obtained intake flow rate is equal to the preset flow rate threshold under the corresponding stack electrical density, it can be determined that there is a leakage fault at the front end of the stack cathode inlet in the fuel cell system.

[0087] Among them, the above-mentioned air intake flow failure generally includes at least one of the air compressor 1, back pressure valve 7 and air filter 3 being faulty, and the above-mentioned fuel cell cathode inlet front-end leakage failure generally includes at least one of the humidifier 5 and bypass valve 6 being faulty.

[0088] In practice, the aforementioned preset flow threshold can be set according to the system design of the fuel cell system.

[0089] Furthermore, the reason for using the intake flow rate in this embodiment is that the cathode intake pressure of fuel cell stack 1 is difficult to determine. Factors affecting the intake pressure are not limited to insufficient air. If water blockage occurs inside fuel cell stack 1 or if the tailpipe is blocked, the intake pressure will be affected. Therefore, in order to ensure the effectiveness of fault diagnosis, it is appropriate to use the intake flow rate for judgment.

[0090] Continue asFigure 3 As shown, when the intake flow rate of the fuel cell system is determined to be faulty, the method of this embodiment includes obtaining the rotational speed fed back by the air compressor 2, and determining that the air compressor 2 is faulty when the obtained rotational speed fed back by the air compressor 2 is not equal to the preset rotational speed threshold under the corresponding stack electrical density, and determining that the air compressor 2 is not faulty when the obtained rotational speed is equal to the preset rotational speed threshold under the corresponding stack electrical density.

[0091] In the fuel cell system, the speed of the air compressor 2 is set at each electrical density point of the stack 1. Therefore, if the speed fed back by the air compressor 2 is different from the speed that should be present at the corresponding electrical density of the stack (i.e., the preset speed threshold), it can be said that the air compressor 2 is faulty.

[0092] In practice, the aforementioned preset speed threshold is also based on the system design settings of the fuel cell system.

[0093] When it is determined that air compressor 2 is not faulty, such as Figure 3 As shown, the method in this embodiment further includes obtaining the opening degree fed back by the back pressure valve 7. When the obtained opening degree fed back by the back pressure valve 7 is not equal to the first preset opening degree threshold under the corresponding electric stack density, it can be determined that the back pressure valve 7 is faulty. When the obtained opening degree fed back by the back pressure valve 7 is equal to the first preset opening degree threshold under the corresponding electric stack density, it can be determined that the air filter 3 is faulty.

[0094] At this point, it is worth noting that, based on the fact that the air compressor 2 has a set speed at each electrical density point of the fuel cell stack 1, and the fuel cell system also controls the flow and pressure on the cathode side by controlling the back pressure valve 7 under this set value. If, after the air compressor 2 reaches the set speed, adjusting the back pressure valve 7 fails to adjust the cathode side flow, that is, the opening degree fed back by the back pressure valve 7 differs from the opening degree that the back pressure valve 7 should be at at this time (i.e., the first preset opening threshold), it indicates that the back pressure valve 7 is faulty.

[0095] Of course, if there is no fault in air compressor 2 and back pressure valve 7, it means that air filter 3 is faulty, and specifically, the filter element of air filter 3 is damaged, which causes abnormal air intake flow of air compressor 2.

[0096] In practice, the aforementioned first preset opening threshold can be set based on the system design of the fuel cell system.

[0097] In this embodiment, if it is determined that there is no intake flow fault in the fuel cell system, that is, no fault in the air compressor 2, air filter 3, and back pressure valve 7, it indicates that there is an air leakage fault at the front end of the cathode inlet of the fuel cell stack, resulting in insufficient inlet flow on the cathode side of the fuel cell stack 1. The relevant components are the humidifier 5 and the bypass valve 6. The intercooler 4, because it uses heat exchange plates internally and is usually sealed by brazing or other methods, generally does not leak and therefore does not need to be assessed.

[0098] Continue as Figure 3 As shown, when it is determined that there is a gas leakage fault at the front end of the cathode inlet of the fuel cell system, the method of this embodiment includes obtaining the opening value fed back by the bypass valve 6. When the opening value fed back by the bypass valve 6 is not equal to the second preset opening threshold under the corresponding stack electrical density, it is determined that there is a control failure fault in the bypass valve 6.

[0099] The aforementioned control failure of bypass valve 6 means that when an opening control signal is given to bypass valve 6, bypass valve 6 cannot adjust its own opening according to the opening control signal, so that the opening fed back by bypass valve 6 will be different from the required opening (i.e., the second preset opening threshold).

[0100] In practice, the aforementioned second preset opening threshold can be set based on the system design of the fuel cell system.

[0101] And continue as Figure 3 As shown, when the opening degree of the bypass valve 6 is equal to the second preset opening degree threshold under the corresponding stack voltage, the method of this embodiment further includes opening the bypass valve 6 to the minimum opening degree, obtaining the current average voltage of all single cells, and then closing the bypass valve 6 when the obtained average voltage drops, and continuing to obtain the current average voltage of all single cells. When the obtained average voltage rises, it can be determined that the humidifier 5 has a fault.

[0102] It is worth noting that since there is a membrane inside the humidifier 5, it is prone to air leakage. Therefore, the faults of the humidifier 5 mentioned above are generally due to air leakage inside the humidifier 5, which causes the air intake on the cathode side of the fuel cell stack 1 to leak into the tailpipe at the humidifier 5.

[0103] In addition, the minimum opening degree of the bypass valve 6 mentioned above will vary depending on the type of bypass valve 6 selected, and it is generally within 10%.

[0104] Still Figure 3As shown, when the opening degree fed back by the bypass valve 6 is equal to the second preset opening degree threshold under the corresponding stack voltage, the method of this embodiment further includes opening the bypass valve 6 to the minimum opening degree, obtaining the current average voltage of all single cells, and then closing the bypass valve 6 when the obtained average voltage remains unchanged, and continuing to obtain the current average voltage of all single cells. When the obtained average voltage remains unchanged, it is determined that there is a leakage fault in the bypass valve 6.

[0105] At this time, since bypass valve 6 is used to bypass part of the incoming air, opening bypass valve 6 will inevitably reduce the air intake on the cathode side of fuel cell stack 1, resulting in a drop in the voltage of fuel cell stack 1. Therefore, if the voltage of fuel cell stack 1 does not change significantly when bypass valve 6 is switched, it indicates that there is a leakage fault at bypass valve 6, causing bypass valve 6 to lose its bypass regulation function.

[0106] The fuel cell system fault diagnosis method of this embodiment adopts the above design. By acquiring the parameters of the fuel cell system during operation and comparing the acquired parameters with preset parameter thresholds, fault diagnosis is performed. When a voltage drop fault occurs in the fuel cell system, the system can automatically determine the fault location, thereby improving the fault diagnosis efficiency and avoiding unnecessary waste of time and manpower, which is conducive to the handling of cathode air intake faults in the fuel cell system.

[0107] Example 2

[0108] This embodiment relates to a fuel cell system fault diagnosis device, which is used to implement the fuel cell system fault diagnosis method in Embodiment 1, and in its overall structure, it combines... Figure 4 As shown in the figure, the fuel cell system fault determination device of this embodiment includes an acquisition unit 100, a comparison unit 200, a timing unit 300, and a determination unit 400.

[0109] The acquisition unit 100 is used to acquire the average voltage of all individual cells in the fuel cell stack. The comparison unit 200 is used to compare the acquired average voltage with a preset voltage threshold under the current fuel cell stack voltage density. The timing unit 300 is used to time the duration for which the average voltage remains below the preset voltage threshold when the acquired average voltage is lower than the preset voltage threshold under the current fuel cell stack voltage density. The determination unit 400 is used to determine that the fuel cell system is suspected of having a cathode undergassing fault when the timing duration exceeds a first preset duration.

[0110] Specifically, the units described above in this embodiment can be circuit module units installed in the fuel cell controller and having corresponding data processing functions. In addition to the units mentioned above, in actual implementation, the device in this embodiment will typically also include storage units and other necessary unit modules. The storage unit can store the control commands involved in the device of this embodiment, while other necessary units typically include input / output modules, timing modules, and calculation modules, etc., which will not be described in detail here.

[0111] The specific working process of the fuel cell system fault diagnosis device in this embodiment, that is, its judgment of the fault on the cathode side of the fuel cell system when the voltage of stack 1 drops, can be found in the relevant description in Embodiment 1.

[0112] Moreover, the fuel cell system fault diagnosis device of this embodiment, through the setting of the above-mentioned units and by implementing the method in Embodiment 1, is based on acquiring the parameters of the fuel cell system during operation and comparing the acquired parameters with preset parameter thresholds to diagnose the fault. When a voltage drop fault occurs in the fuel cell system, the system can automatically determine the fault location, thereby improving the fault diagnosis efficiency and avoiding unnecessary waste of time and manpower, which is beneficial to the handling of cathode air intake faults in the fuel cell system.

[0113] Example 3

[0114] This embodiment relates to a fuel cell system, still in conjunction with... Figure 1 As shown, an intake air flow detection unit 13 is installed on the cathode intake pipe of the fuel cell system, located between the air filter 3 and the air compressor 2, and this intake air flow detection unit 13 is connected to the fuel cell controller in the fuel cell system. Simultaneously, the fuel cell controller in this embodiment can execute the fuel cell system fault diagnosis method in Embodiment 1.

[0115] The aforementioned fuel cell controller typically consists of a memory and actuators. Both the memory and actuators can be existing conventional modules. The memory stores a computer program, which the actuator executes to implement the fuel cell system fault diagnosis method described in Example 1.

[0116] The fuel cell system in this embodiment, by executing the fuel cell system fault method in Embodiment 1, can determine the fault by comparing the obtained parameters with preset parameter thresholds based on the obtained operating parameters of the fuel cell system. In this way, when a voltage drop fault occurs in the fuel cell system, the system can automatically determine the fault location, which can improve the fault determination efficiency and avoid unnecessary waste of time and manpower, thus facilitating the handling of cathode air intake faults in the fuel cell system.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for diagnosing faults in a fuel cell system, characterized in that, The method includes: Obtain the average voltage of all individual cells in the stack (1); When the average voltage is less than a preset voltage threshold under the current stack voltage density, the duration for which the average voltage remains less than the preset voltage threshold is timed. If the timing duration exceeds the first preset duration, it is determined that the fuel cell system is suspected of having a cathode undergassing fault.

2. The method for diagnosing fuel cell system faults according to claim 1, characterized in that, When determining that a suspected cathode undergassing fault exists in a fuel cell system, the method further includes: The stack density is gradually reduced according to a preset density gradient, and after each reduction to the corresponding stack density, a second preset time is waited before the current average voltage of all individual cells is obtained. Wherein, when the current average voltage is still less than the preset voltage threshold under the corresponding stack density, the stack density continues to be reduced according to the preset density gradient. When the stack density is reduced to the minimum density and the current average voltage is still less than the preset voltage threshold under the corresponding stack density, it is determined that the fuel cell system has a cathode undergassing fault. Specifically, when the current average voltage is not less than the preset voltage threshold under the corresponding stack voltage density, the reduction of stack voltage density is stopped, and it is determined that there is no cathode undergassing fault in the fuel cell system.

3. The method for diagnosing fuel cell system faults according to claim 2, characterized in that, When a cathode undergassing fault is determined in the fuel cell system, the method further includes: Obtain the intake air flow rate on the inlet side of the air compressor (2); When the obtained intake air flow rate is less than the preset flow rate threshold under the corresponding stack electrical density, it is determined that there is an intake air flow fault in the fuel cell system. When the obtained air intake flow rate is equal to the preset flow rate threshold under the corresponding stack electrical density, it is determined that there is a gas leakage fault at the front end of the stack cathode inlet in the fuel cell system. The air intake flow fault includes at least one of the air compressor (1), back pressure valve (7) and air filter (3) being faulty, and the fuel cell cathode inlet front-end leakage fault includes at least one of the humidifier (5) and bypass valve (6) being faulty.

4. The method for diagnosing fuel cell system faults according to claim 3, characterized in that, When it is determined that there is an intake flow fault in the fuel cell system, the method includes: Obtain the rotational speed fed back by the air compressor (2); When the speed feedback from the air compressor (2) is not equal to the preset speed threshold under the corresponding fuel cell density, it is determined that the air compressor (2) has a fault. When the obtained rotational speed is equal to the preset rotational speed threshold under the corresponding fuel cell density, it is determined that the air compressor (2) has no fault.

5. The method for diagnosing faults in a fuel cell system according to claim 4, characterized in that, When it is determined that the air compressor (2) is not faulty, the method further includes: Obtain the opening degree fed back by the back pressure valve (7); When the opening degree fed back by the back pressure valve (7) is not equal to the first preset opening degree threshold under the corresponding stack electrical density, it is determined that the back pressure valve (7) is faulty; When the opening degree of the back pressure valve (7) is equal to the first preset opening degree threshold under the corresponding electric stack density, it is determined that the air filter (3) is faulty.

6. The method for diagnosing faults in a fuel cell system according to claim 3, characterized in that, When it is determined that there is a gas leakage fault at the front end of the stack cathode inlet in the fuel cell system, the method further includes: Obtain the opening value fed back by the bypass valve (6); When the opening degree fed back by the bypass valve (6) is not equal to the second preset opening degree threshold under the corresponding stack electrical density, it is determined that the bypass valve (6) has a control failure fault.

7. The method for diagnosing faults in a fuel cell system according to claim 6, characterized in that, When the opening degree fed back by the bypass valve (6) is equal to the second preset opening degree threshold under the corresponding stack electrical density, the method further includes: Open the bypass valve (6) to its minimum opening degree; Get the current average voltage of all individual cells; When the acquired average voltage drops, the bypass valve (6) is closed, and the current average voltage of all individual cells is acquired again. When the average voltage obtained increases, it is determined that the humidifier (5) is faulty.

8. The method for diagnosing faults in a fuel cell system according to claim 6, characterized in that, When the opening degree fed back by the bypass valve (6) is equal to the second preset opening degree threshold under the corresponding stack electrical density, the method further includes: Open the bypass valve (6) to its minimum opening degree; Get the current average voltage of all individual cells; While the average voltage remains unchanged, the bypass valve (6) is closed, and the current average voltage of all individual cells is acquired. If the average voltage obtained remains unchanged, it is determined that the bypass valve (6) has a leakage fault.

9. A fault diagnosis device for a fuel cell system, characterized in that: It includes an acquisition unit (100), a comparison unit (200), a timing unit (300), and a determination unit (400); The acquisition unit (100) is used to acquire the average voltage of all individual cells in the stack; The comparison unit (200) is used to compare the acquired average voltage with a preset voltage threshold under the current stack density; The timing unit (300) is used to time the duration for which the average voltage is continuously less than the preset voltage threshold when the acquired average voltage is less than the preset voltage threshold under the current stack voltage density. The determining unit (400) is used to determine that the fuel cell system is suspected of having a cathode undergassing fault when the timing duration is longer than a first preset duration.

10. A fuel cell system, characterized in that: The cathode inlet pipe of the fuel cell system is provided with an intake flow detection unit (13) located between the air filter (3) and the air compressor (2), and the intake flow detection unit (13) is connected to the fuel cell controller in the fuel cell system. The fuel cell controller is capable of executing the fuel cell system fault diagnosis method according to any one of claims 1 to 8.

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