Fuel cell system diagnosis method and device

Abstract

The invention provides a fuel cell system diagnosis method and device, and the method comprises the steps: collecting the in-stack pressure and out-stack pressure of a fuel cell stack anode in real time, and obtaining an actual anode pressure drop; a pressure drop deviation is obtained according to the actual anode pressure drop and a theoretical anode pressure drop obtained through pre-calculation; if the pressure drop deviation is greater than a preset threshold value, adjusting the hydrogen pressure and applying sine disturbance to obtain dynamic hydrogen in-pile pressure; obtaining pressure drop impedance according to the actual anode pressure drop and the dynamic hydrogen in-pile pressure; and diagnosing the fuel cell according to the pressure drop impedance and the pressure drop deviation, and judging the problems of the fuel cell. Membrane dryness and water logging are diagnosed through a method based on electrochemical pressure impedance spectroscopy and pressure drop deviation coupling, a current alternating current signal does not need to be applied to a fuel cell system, meanwhile, whether water logging and membrane dryness exist or not is judged in the mode of collecting actual anode pressure drop in real time and calculating pressure drop deviation, and the real-time performance and accuracy of diagnosis are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell system diagnosis method and device. Background Art

[0002] Fuel cells are clean energy devices that convert chemical energy directly into electrical energy. Proton exchange membrane fuel cells (PEMFCs) are widely used in automotive, power generation, and other fields due to their high efficiency and environmental friendliness. However, during fuel cell operation, complex physical and chemical processes, such as the wetness of the proton exchange membrane, the humidity of the gas diffusion layer, and the wettability of the catalyst layer, can affect the performance and stability of the fuel cell. Therefore, online diagnostics of fuel cell systems, particularly the wetness of the proton exchange membrane, are crucial for improving fuel cell performance and stability.

[0003] In the related art, diagnosis is mainly performed through electrochemical impedance spectroscopy (EIS). EIS is a method of obtaining internal state information of the fuel cell by applying a small AC signal to the fuel cell system and then measuring its response. When scanning a single frequency point to characterize the impedance, it can be used to reflect the impedance index of water flooding and membrane drying. However, the problem with this method is that the corresponding frequency point for the impedance index reflecting water flooding and membrane drying is difficult to select, especially the low-frequency impedance point that characterizes water flooding faults, and the calculation is complex and difficult to achieve online diagnosis. Summary of the Invention

[0004] The purpose of the present invention is to provide a fuel cell system diagnosis method and device, which solves the problem in the related art that the impedance index calculation of water flooding and membrane drying is complex and difficult to achieve online diagnosis.

[0005] To this end, in a first aspect, the present invention provides a fuel cell system diagnostic method, comprising collecting the inlet pressure and outlet pressure of the fuel cell stack anode in real time to obtain the actual anode pressure drop;

[0006] The pressure drop deviation is obtained according to the actual anode pressure drop and the theoretical anode pressure drop calculated in advance;

[0007] If the pressure drop deviation is greater than a preset threshold, the hydrogen pressure is adjusted to apply a sinusoidal disturbance to obtain the dynamic hydrogen inlet pressure;

[0008] The pressure drop impedance is obtained according to the actual anode pressure drop and the dynamic hydrogen inlet pressure;

[0009] The fuel cell is diagnosed based on the pressure drop impedance and pressure drop deviation to determine the problems existing in the fuel cell.

[0010] Optionally, the step of collecting the inlet pressure and outlet pressure of the fuel cell stack anode in real time to obtain the actual anode pressure drop includes:

[0011] The pressure sensor installed on the anode side of the fuel cell stack collects the anode inlet pressure and outlet pressure in real time, calculates the difference between the inlet pressure and the outlet pressure, and obtains the actual anode pressure drop.

[0012] Optionally, the step of obtaining the pressure drop deviation based on the actual anode pressure drop and the pre-calculated theoretical anode pressure drop includes: calculating the difference between the actual anode pressure drop and the pre-calculated theoretical anode pressure drop to obtain the pressure drop deviation.

[0013] Optionally, the theoretical anode pressure drop is the sum of the flow channel's longitudinal resistance, the gas diffusion layer pressure drop, the manifold distribution pressure drop, and the dynamic pressure drop caused by reaction consumption.

[0014] Optionally, if the pressure drop deviation is greater than a preset threshold, the step of adjusting the hydrogen pressure to apply a sinusoidal disturbance to obtain a dynamic hydrogen inlet pressure includes:

[0015] If the pressure drop deviation is greater than a preset threshold, the fuel cell controller applies a sinusoidal pressure disturbance through the hydrogen pressure regulating valve to detect the dynamic hydrogen inlet pressure under the sinusoidal disturbance.

[0016] Optionally, the frequency range of the sinusoidal disturbance is 1-100 Hz, and the amplitude range is 1-10 kPa.

[0017] Optionally, the step of obtaining the pressure drop impedance according to the actual anode pressure drop and the dynamic hydrogen inlet pressure includes:

[0018] The hydrogen flow rate is calculated from the dynamic hydrogen inlet pressure, and the actual anode pressure drop and hydrogen flow rate are Fourier transformed to obtain the pressure drop impedance.

[0019] Optionally, the step of diagnosing the fuel cell based on the pressure drop impedance and the pressure drop deviation and determining a problem with the fuel cell includes: determining whether the fuel cell is flooded or membrane-dried based on the values ​​of the pressure drop impedance and the pressure drop deviation.

[0020] Optionally, if the pressure drop deviation is positive and greater than a preset pressure drop deviation threshold, and the pressure drop impedance is less than a preset pressure drop impedance threshold, it is determined that the fuel cell is flooded;

[0021] If the pressure drop deviation is negative and smaller than a preset pressure drop deviation threshold, and the pressure drop impedance is larger than a preset pressure drop impedance threshold, it is determined that the fuel cell has membrane dryness.

[0022] In a second aspect, a fuel cell system diagnostic device is provided, comprising:

[0023] The data acquisition module is used to collect the inlet and outlet pressures of the fuel cell stack anode in real time to obtain the actual anode pressure drop;

[0024] A pressure drop deviation calculation module is used to obtain a pressure drop deviation based on an actual anode pressure drop and a pre-calculated theoretical anode pressure drop;

[0025] The sinusoidal perturbation module is used to adjust the hydrogen pressure by applying sinusoidal perturbations when the pressure drop deviation is greater than a preset threshold, thereby obtaining the dynamic hydrogen inlet pressure.

[0026] A pressure drop impedance calculation module is used to obtain the pressure drop impedance based on the actual anode pressure drop and the dynamic hydrogen inlet pressure;

[0027] The diagnostic module is used to diagnose the fuel cell based on the pressure drop impedance and pressure drop deviation to determine the problems existing in the fuel cell.

[0028] Beneficial effects:

[0029] The present disclosure provides a fuel cell system diagnosis method and device, which diagnoses membrane dryness and water flooding by a method based on the coupling of electrochemical pressure impedance spectroscopy and pressure drop deviation. There is no need to apply a current AC signal to the fuel cell system, avoiding the possibility that the current AC signal may interfere with the normal operation of the fuel cell. At the same time, by real-time acquisition of the actual anode pressure drop and calculating the pressure drop deviation, it is determined whether water flooding and membrane dryness exist, which reduces the complexity of the calculation, enables online diagnosis, and improves the real-time and accuracy of the diagnosis.

[0030] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A method flow chart of an embodiment of a fuel cell system diagnostic method disclosed herein;

[0033] Figure 2 This is a system structure diagram of an embodiment of a fuel cell system diagnostic device disclosed herein;

[0034] In the figure, 100 is a power generation unit, 101 is a first one-way valve, 102 is an air compressor, 103 is a fuel cell stack, 104 is a second one-way valve, 200 is a filter, and 300 is a muffler. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] In the specification and claims of this application, as well as in the accompanying drawings, the terms "first," "second," "third," "fourth," and the like are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that such terms are interchangeable where appropriate. For example, first information could be referred to as second information, and similarly, second information could be referred to as first information without departing from the scope of this disclosure.

[0037] The word "if" as used herein may be interpreted as "when" or "when" or "in response to determining," depending on the context.

[0038] Furthermore, as used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise.

[0039] It should be further understood that the terms “comprises” and “includes” indicate the existence of features, steps, operations, elements, components, items, types, and / or groups, but do not preclude the existence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, types, and / or groups.

[0040] The terms "or" and "and / or" as used herein are to be interpreted as inclusive, or mean any one or any combination. Thus, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C." An exception to this definition occurs only when a combination of elements, functions, steps, or operations are inherently mutually exclusive in some manner.

[0041] In a first aspect, the present disclosure provides Figure 1 A fuel cell system diagnostic method shown includes the following steps:

[0042] S100, collecting the inlet pressure and outlet pressure of the fuel cell stack anode in real time to obtain the actual anode pressure drop;

[0043] The pressure sensor installed on the anode side of the fuel cell stack collects the anode inlet pressure and outlet pressure in real time, calculates the difference between the inlet pressure and the outlet pressure, and obtains the actual anode pressure drop.

[0044] Actual anode pressure drop ΔP r The calculation formula is:

[0045] ΔP r =P 入 -P 出

[0046] Among them, P 入 is the pile pressure, P 出 The pressure of the pile.

[0047] By collecting the actual anode pressure drop of the anode in real time, it provides a basis for subsequent fuel cell diagnosis.

[0048] S200, obtaining a pressure drop deviation based on the actual anode pressure drop and a pre-calculated theoretical anode pressure drop;

[0049] The difference between the actual anode pressure drop and the pre-calculated theoretical anode pressure drop is calculated to obtain the pressure drop deviation. This pressure drop deviation can be used to preliminarily determine whether the fuel cell has flooding or membrane dryness issues.

[0050] The calculation formula for pressure drop deviation ΔP is:

[0051] ΔP=ΔP r -ΔP t

[0052] Where ΔP r is the actual anode pressure drop, ΔP t is the theoretical anode pressure drop.

[0053] The theoretical anode pressure drop is the sum of the flow channel resistance, the gas diffusion layer pressure drop, the manifold distribution pressure drop and the dynamic pressure drop caused by reaction consumption.

[0054] The calculation formula of theoretical anode pressure drop is:

[0055] ΔP t =ΔP flowchannel +ΔP GDL +ΔP manifold +ΔP reactantconsumption

[0056] Where ΔP flowchannel is the flow resistance along the channel, ΔP GDL is the gas diffusion layer pressure drop, ΔP manifold Assign pressure drop to the manifold, ΔP reactantconsumptionis the dynamic pressure drop caused by reaction consumption. ΔP flowchannel is calculated using the Darcy-Weisbach formula:

[0057] ΔP flowchannel =f×(L / D h )×(ρu 2 / 2)

[0058] Where f is the friction coefficient, L is the flow channel length, D h is the hydraulic diameter, ρ is the hydrogen density, and u is the flow velocity.

[0059] ΔP GDL Using the modified Darcy's law equation:

[0060]

[0061] Where μ is the hydrogen dynamic viscosity, k is the GDL permeability, L GDL is the length of the gas diffusion layer, u GDL is the apparent velocity in the GDL, β is the inertial drag coefficient, and ρ is the density of the gas.

[0062] ΔP manifold The calculation formula is:

[0063]

[0064] Among them, K in and K out is the inlet and outlet local resistance coefficient, u in and u out is the manifold inlet and outlet flow rate.

[0065] ΔP reactantconsumption Calculated based on the change in hydrogen molar flow rate along the flow channel.

[0066] S300: If the pressure drop deviation is greater than a preset threshold, adjust the hydrogen pressure and apply a sinusoidal disturbance to obtain a dynamic hydrogen inlet pressure;

[0067] If the pressure drop deviation is greater than a preset threshold, the fuel cell controller applies a sinusoidal pressure disturbance through the hydrogen pressure regulating valve to detect the dynamic hydrogen inlet pressure under the sinusoidal disturbance.

[0068] The frequency range of the sinusoidal disturbance is 1-100 Hz, and the amplitude range is 1-10 kPa.

[0069] By applying a controllable sinusoidal pressure disturbance, the dynamic response of the fuel cell system is stimulated, providing key data for the subsequent electrochemical pressure impedance spectrum analysis. When the pressure drop deviation exceeds the preset threshold, it indicates that the system may be in an abnormal state (such as flooding or membrane drying). At this time, a sinusoidal pressure disturbance is applied, and by changing the hydrogen pressure, dynamic pressure changes are introduced to stimulate the dynamic response of the water distribution, gas flow and other states inside the system. The characteristics of the sinusoidal disturbance (fixed frequency and amplitude) give it a clear resolution in frequency domain analysis. By subsequently performing a fast Fourier transform (FFT), the impedance amplitude and phase information can be extracted. The traditional method requires the application of an AC current signal, which may interfere with the normal operation of the fuel cell. In this embodiment, the current disturbance is replaced by a pressure disturbance, which not only reduces interference but also maintains the stability of the system operation.

[0070] S400, obtaining a pressure drop impedance according to an actual anode pressure drop and a dynamic hydrogen inlet pressure;

[0071] The hydrogen flow rate is calculated from the dynamic hydrogen inlet pressure, and the actual anode pressure drop and hydrogen flow rate are Fourier transformed to obtain the pressure drop impedance.

[0072] First, the flow rate is calculated by pressure. Assuming that hydrogen is an ideal gas and the flow is laminar, the system model is simplified to:

[0073]

[0074] Where V is the known volume of the hydrogen cavity, γ is the specific heat ratio of hydrogen, R is the gas constant, T is the temperature, and P in is the dynamic hydrogen inlet pressure.

[0075] Then the actual anode pressure drop and hydrogen flow rate are Fourier transformed.

[0076]

[0077] Obtain the impedance:

[0078]

[0079] The amplitude is:

[0080]

[0081] The phase is:

[0082]

[0083] Frequency domain analysis converts the complex relationship between pressure and flow into quantifiable impedance parameters, providing data support for fault diagnosis. The impedance response at different frequencies can distinguish between low-frequency flooding and high-frequency membrane drying, reducing misdiagnosis.

[0084] S500: Diagnose the fuel cell based on the pressure drop impedance and the pressure drop deviation to determine problems with the fuel cell.

[0085] The pressure drop impedance and pressure drop deviation values ​​are used to determine if the fuel cell is flooded or the membrane is dry. The pressure drop impedance is used to characterize the dynamic changes in the water content inside the fuel cell.

[0086] If the pressure drop deviation is positive and greater than a preset pressure drop deviation threshold, and the pressure drop impedance is less than a preset pressure drop impedance threshold, it is determined that the fuel cell is flooded;

[0087] If the pressure drop deviation is negative and smaller than a preset pressure drop deviation threshold, and the pressure drop impedance is larger than a preset pressure drop impedance threshold, it is determined that the fuel cell has membrane dryness.

[0088] In a second aspect, a fuel cell system diagnostic device is provided, comprising:

[0089] The data acquisition module 101 is used to collect the inlet pressure and outlet pressure of the fuel cell stack anode in real time to obtain the actual anode pressure drop;

[0090] A pressure drop deviation calculation module 102 is configured to obtain a pressure drop deviation based on the actual anode pressure drop and a pre-calculated theoretical anode pressure drop;

[0091] The sinusoidal perturbation module 103 is used to adjust the hydrogen pressure and apply sinusoidal perturbation to obtain the dynamic hydrogen inlet pressure when the pressure drop deviation is greater than a preset threshold;

[0092] A pressure drop impedance calculation module 104 is configured to obtain the pressure drop impedance based on the actual anode pressure drop and the dynamic hydrogen inlet pressure;

[0093] The diagnosis module 105 is used to diagnose the fuel cell based on the pressure drop impedance and the pressure drop deviation, and determine the problems existing in the fuel cell.

[0094] The method of using the fuel cell system diagnostic device in this embodiment is the same as described above and will not be repeated here.

[0095] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. A fuel cell system diagnostic method, characterized in that: The steps include: Real-time acquisition of fuel cell stack anode inlet and outlet pressures to obtain actual anode pressure drop; The pressure drop deviation is obtained according to the actual anode pressure drop and the theoretical anode pressure drop calculated in advance; If the pressure drop deviation is greater than a preset threshold, the hydrogen pressure is adjusted to apply a sinusoidal disturbance to obtain the dynamic hydrogen inlet pressure; The pressure drop impedance is obtained according to the actual anode pressure drop and the dynamic hydrogen inlet pressure; The fuel cell is diagnosed based on the pressure drop impedance and pressure drop deviation to determine the problems existing in the fuel cell.

2. A fuel cell system diagnostic method according to claim 1, characterized in that: The step of collecting the inlet pressure and outlet pressure of the fuel cell stack anode in real time to obtain the actual anode pressure drop includes: The pressure sensor installed on the anode side of the fuel cell stack collects the anode inlet pressure and outlet pressure in real time, calculates the difference between the inlet pressure and the outlet pressure, and obtains the actual anode pressure drop.

3. A fuel cell system diagnostic method according to claim 1, characterized in that: The step of obtaining the pressure drop deviation based on the actual anode pressure drop and the pre-calculated theoretical anode pressure drop includes: calculating the difference between the actual anode pressure drop and the pre-calculated theoretical anode pressure drop to obtain the pressure drop deviation.

4. A fuel cell system diagnostic method according to claim 3, characterized in that: The theoretical anode pressure drop is the sum of the flow channel resistance, the gas diffusion layer pressure drop, the manifold distribution pressure drop and the dynamic pressure drop caused by reaction consumption.

5. A fuel cell system diagnostic method according to claim 1, characterized in that: If the pressure drop deviation is greater than a preset threshold, the step of adjusting the hydrogen pressure to apply a sinusoidal disturbance to obtain a dynamic hydrogen inlet pressure includes: If the pressure drop deviation is greater than a preset threshold, the fuel cell controller applies a sinusoidal pressure disturbance through the hydrogen pressure regulating valve to detect the dynamic hydrogen inlet pressure under the sinusoidal disturbance.

6. A fuel cell system diagnostic method according to claim 5, characterized in that: The frequency range of the sinusoidal disturbance is 1-100 Hz, and the amplitude range is 1-10 kPa.

7. A fuel cell system diagnostic method according to claim 1, characterized in that: The step of obtaining the pressure drop impedance according to the actual anode pressure drop and the dynamic hydrogen inlet pressure comprises: The hydrogen flow rate is calculated from the dynamic hydrogen inlet pressure, and the actual anode pressure drop and hydrogen flow rate are Fourier transformed to obtain the pressure drop impedance.

8. A fuel cell system diagnostic method according to claim 1, characterized in that: The step of diagnosing the fuel cell based on the pressure drop impedance and the pressure drop deviation and determining the problem of the fuel cell includes: determining whether the fuel cell is flooded or membrane dried out based on the values ​​of the pressure drop impedance and the pressure drop deviation.

9. A fuel cell system diagnostic method according to claim 8, characterized in that: If the pressure drop deviation is positive and greater than a preset pressure drop deviation threshold, and the pressure drop impedance is less than a preset pressure drop impedance threshold, it is determined that the fuel cell is flooded; If the pressure drop deviation is negative and smaller than a preset pressure drop deviation threshold, and the pressure drop impedance is larger than a preset pressure drop impedance threshold, it is determined that the fuel cell has membrane dryness.

10. A fuel cell system diagnostic device, characterized in that: include: The data acquisition module is used to collect the inlet and outlet pressures of the fuel cell stack anode in real time to obtain the actual anode pressure drop; A pressure drop deviation calculation module is used to obtain a pressure drop deviation based on an actual anode pressure drop and a pre-calculated theoretical anode pressure drop; The sinusoidal perturbation module is used to adjust the hydrogen pressure by applying sinusoidal perturbations when the pressure drop deviation is greater than a preset threshold, thereby obtaining the dynamic hydrogen inlet pressure. A pressure drop impedance calculation module is used to obtain the pressure drop impedance based on the actual anode pressure drop and the dynamic hydrogen inlet pressure; The diagnostic module is used to diagnose the fuel cell based on the pressure drop impedance and pressure drop deviation to determine the problems existing in the fuel cell.

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