Fuel cell safety performance evaluation method and system based on safety margin

Abstract

This application discloses a fuel cell safety performance assessment method and system based on a safety margin, relating to the technical field of fuel cell safety assessment. The method includes obtaining initial system parameters, constructing an initial fuel cell safety model based on the initial system parameters, and determining the initial safety interval volume; obtaining the current proton exchange membrane thickness and catalyst surface area based on a current operating parameter decay process model; correcting the initial fuel cell safety model based on the proton exchange membrane thickness and catalyst surface area, obtaining the current safety margin based on the corrected fuel cell safety model at the current moment, and then determining the safety radius; obtaining a comprehensive safety index value based on the initial safety interval volume, the current safety interval volume, and the safety radius; and evaluating safety performance using the comprehensive safety index value. This application improves the reliability, computational efficiency, and real-time performance of fuel cell safety performance assessment.

Description

Technical Field

[0001] The present application relates to the technical field of fuel cell safety assessment, and in particular to a fuel cell safety performance assessment method and system based on safety margins. Background Art

[0002] Hydrogen, one of the most promising energy sources to replace oil and natural gas, is renowned for its cleanliness and efficiency, and is hailed as the ultimate energy source of the 21st century. Fuel cell vehicles, as the primary application of hydrogen energy in transportation, have become the next big thing in the automotive industry and a vanguard of future green mobility. Fuel cell safety has always been a focal point in the industry. Proper operation requires the coordinated operation of multiple parameters, including gas, water, electricity, and heat. However, this multi-parameter coupling makes the safe operating boundaries of fuel cells unclear, making real-time safety assessment difficult. Particularly in the middle and later stages of a fuel cell's lifespan, the performance parameters of various components rapidly degrade, making it extremely easy for fuel cells to exceed safety limits, leading to premature end of life. The reliability of existing battery safety assessment methods needs to be improved. Furthermore, current methods for evaluating fuel cell safety mostly rely on machine learning and deep learning algorithms, which suffer from poor interpretability, high computing power requirements, and difficulty in real-time utilization.

[0003] Therefore, a safety assessment method that takes fuel cell degradation into account is urgently needed to solve the above problems. Summary of the Invention

[0004] The purpose of this application is to provide a fuel cell safety performance evaluation method and system based on safety margins, which improves the reliability, computational efficiency and real-time performance of fuel cell safety performance evaluation.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] In a first aspect, the present application provides a fuel cell safety performance evaluation method based on a safety margin, and the fuel cell safety performance evaluation method based on a safety margin includes the following steps.

[0007] Obtaining initial system parameters of the air compressor and the fuel cell in the fuel cell system; the initial system parameters are the system parameters at the time of leaving the factory;

[0008] Based on the initial system parameters of the air compressor and the initial system parameters of the fuel cell, an initial fuel cell safety model is constructed; the safety model includes: an intake safety model, a water safety model, a thermal safety model, and an electrical safety model;

[0009] Determine the safety boundary of the initial fuel cell based on the safety model of the initial fuel cell;

[0010] Based on the initial fuel cell safety margin, calculate the initial safety interval volume of the fuel cell;

[0011] After the fuel cell has been running for a period of time, the operating parameters of the fuel cell at the current moment are obtained, and based on the operating parameters of the fuel cell at the current moment and a fuel cell degradation process model, the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment are obtained; the fuel cell degradation process model is constructed based on the initial system parameters of the fuel cell and the operating parameters of the fuel cell at the previous moment; the operating parameters include: current density, cathode inlet pressure, and oxygen stoichiometric ratio;

[0012] Based on the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment, the initial fuel cell safety model is modified to obtain a modified fuel cell safety model at the current moment;

[0013] Based on the revised safety model of the fuel cell at the current moment, the safety boundary of the fuel cell at the current moment is obtained;

[0014] Based on the safety boundary of the fuel cell at the current moment, calculate the safety interval volume of the fuel cell at the current moment;

[0015] Determine the safety radius of the fuel cell at the current moment based on the operating parameters and safety margin of the fuel cell at the current moment;

[0016] Based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at the current moment, and the safety radius, a comprehensive safety index value of the fuel cell is obtained;

[0017] The safety performance of fuel cells is evaluated using the comprehensive safety index value of fuel cells.

[0018] Optionally, the intake safety model is expressed as:

[0019] ;

[0020] in, is the lower limit of cathode inlet pressure; is the cathode inlet pressure; is the upper limit of cathode inlet pressure;

[0021] The expression of the water security model is:

[0022] ;

[0023] in, is the water content of the proton exchange membrane of the fuel cell; EW is the molar mass of the proton exchange membrane; is the dry film density; is the thickness of the proton exchange membrane; is the water concentration diffusion rate between the anode and the proton exchange membrane; Electroosmotic drag water transfer rate; is the water concentration diffusion rate between the cathode and the proton exchange membrane.

[0024] Optionally, the thermal safety model is expressed as:

[0025] ;

[0026] in, The maximum heat dissipation that the cooling system can provide; Producing heat for fuel cells; To dissipate heat for exhaust gases.

[0027] Optionally, the electrical safety model is expressed as:

[0028] ;

[0029] in, is the fuel cell cell voltage; is the Nernst voltage; is the activation polarization voltage; is the ohmic polarization voltage; is the concentration polarization voltage.

[0030] Optionally, based on the safety model of the initial fuel cell, determining the safety boundary of the initial fuel cell specifically includes:

[0031] The fuel cell state space is established with current density, cathode inlet pressure and oxygen stoichiometric ratio as variables;

[0032] Traversing all state points in the fuel cell state space, and determining the critical state point on the safety model of the initial fuel cell;

[0033] The critical state points are fitted using the least squares method to obtain multiple safety boundaries as the initial safety boundaries of the fuel cell.

[0034] Optionally, based on the initial fuel cell safety margin, calculating the initial safety interval volume of the fuel cell specifically includes:

[0035] The initial safety interval volume of the fuel cell is obtained by combining multiple safety boundaries and performing triple integration on the multiple safety boundaries.

[0036] Optionally, the fuel cell degradation process model is expressed as:

[0037]

[0038] ;

[0039] in, ; are the fitting parameters of the recession process model; is the Faraday constant; is the gas constant; is the fuel cell temperature; is the fuel cell cell voltage; is the current density; is the ohmic impedance; are the fitting parameters of the recession process model; is the partial pressure of oxygen; is the reference air pressure; is the initial film thickness; are the fitting parameters of the recession process model; is the activation energy of membrane degradation.

[0040] Optionally, based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at the current moment, and the safety radius, a comprehensive safety index value of the fuel cell is obtained, specifically including:

[0041] Obtaining a fuel cell degradation ratio based on the fuel cell's current safety interval volume and the fuel cell's initial safety interval volume;

[0042] Based on the fuel cell degradation ratio and the fuel cell safety radius at the current moment, a comprehensive safety index value of the fuel cell is obtained.

[0043] Optionally, the fuel cell degradation ratio is expressed as:

[0044] ;

[0045] in, is the fuel cell degradation ratio; is the safe range volume of the fuel cell at the current moment; is the initial safety interval volume of the fuel cell;

[0046] The expression of the comprehensive safety index value of the fuel cell is:

[0047] ;

[0048] in, is the comprehensive safety index value of the fuel cell; is the safety radius of the fuel cell at the current moment.

[0049] In the second aspect, the present application provides a fuel cell safety performance evaluation system based on a safety boundary, which is used to implement the fuel cell safety performance evaluation method based on a safety boundary, and the fuel cell safety performance evaluation system based on a safety boundary includes the following structure.

[0050] A parameter acquisition unit, used to acquire initial system parameters of the air compressor and the fuel cell in the fuel cell system; the initial system parameters are the system parameters at the time of leaving the factory;

[0051] An initial fuel cell safety model building unit is used to build an initial fuel cell safety model based on the initial system parameters of the air compressor and the initial system parameters of the fuel cell; the safety model includes: an intake safety model, a water safety model, a thermal safety model, and an electrical safety model;

[0052] an initial fuel cell safety boundary determination unit, configured to determine the safety boundary of the initial fuel cell based on a safety model of the initial fuel cell;

[0053] an initial safety interval volume determination unit, configured to calculate an initial safety interval volume of the fuel cell based on an initial safety margin of the fuel cell;

[0054] a proton exchange membrane thickness and catalyst surface area updating unit, configured to obtain the operating parameters of the fuel cell at the current moment after the fuel cell has been operating for a period of time, and to obtain the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment based on the operating parameters of the fuel cell at the current moment and a fuel cell degradation process model; the fuel cell degradation process model is constructed based on the initial system parameters of the fuel cell and the operating parameters of the fuel cell at the previous moment; the operating parameters include: current density, cathode inlet pressure, and oxygen stoichiometric ratio;

[0055] a unit for determining a revised safety model of the fuel cell at the current moment, configured to revise the initial safety model of the fuel cell based on the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment, thereby obtaining a revised safety model of the fuel cell at the current moment;

[0056] a current moment safety boundary determination unit, configured to obtain a current moment safety boundary of the fuel cell based on the revised current moment safety model of the fuel cell;

[0057] a safety interval volume determination unit at a current moment, configured to calculate the safety interval volume of the fuel cell at a current moment based on the safety boundary of the fuel cell at the current moment;

[0058] a safety radius determination unit at a current moment, configured to determine a safety radius of the fuel cell at a current moment based on the operating parameters and safety margin of the fuel cell at the current moment;

[0059] a comprehensive safety index value determination unit, configured to obtain a comprehensive safety index value of the fuel cell based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at a current moment, and the safety radius;

[0060] The safety performance evaluation unit is used to evaluate the safety performance of the fuel cell using the comprehensive safety index value of the fuel cell.

[0061] According to the specific embodiments provided in this application, this application has the following technical effects: This application discloses a fuel cell safety performance evaluation method and system based on safety boundaries. By establishing a safety model of the fuel cell, the comprehensive safety requirements of "gas-water-electricity-heat" are taken into consideration, and a fuel cell operation safety boundary is established. The degradation of key components in the fuel cell (i.e., catalyst and proton exchange membrane) and the safety level of the current state of the fuel cell are comprehensively considered to comprehensively determine the comprehensive safety index value of the fuel cell, thereby improving the reliability of the fuel cell safety evaluation. In addition, the safety boundary model and the degradation model of this application are simple, require low computing power, and have strong real-time performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0063] Figure 1 A schematic flow chart of a fuel cell safety performance assessment method based on a safety margin according to an embodiment of the present application.

[0064] Figure 2 A schematic diagram of the safety boundary and safety space of a fuel cell provided in one embodiment of the present application.

[0065] Figure 3 A schematic diagram of the functional modules of a fuel cell safety performance evaluation system based on safety margins provided in one embodiment of the present application.

[0066] Figure numerals.

[0067] Parameter acquisition unit-1, initial fuel cell safety model construction unit-2, initial fuel cell safety boundary determination unit-3, initial safety interval volume determination unit-4, proton exchange membrane thickness and catalyst surface area update unit-5, corrected fuel cell safety model determination unit-6 at the current moment, current moment safety boundary determination unit-7, current moment safety interval volume determination unit-8, current moment safety radius determination unit-9, comprehensive safety index value determination unit-10, safety performance evaluation unit-11. DETAILED DESCRIPTION

[0068] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. 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.

[0069] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0070] In an exemplary embodiment, Figure 1 As shown, a fuel cell safety performance evaluation method based on a safety margin is provided, including the following steps S1 to S11.

[0071] Step S1, obtaining initial system parameters of the air compressor and the fuel cell in the fuel cell system; the initial system parameters are the system parameters at the time of leaving the factory.

[0072] Step S2: constructing an initial fuel cell safety model based on the initial system parameters of the air compressor and the initial system parameters of the fuel cell; the safety model includes: an intake safety model, a water safety model, a thermal safety model, and an electrical safety model.

[0073] As an optional implementation, in step S2, the intake safety model is expressed as follows.

[0074] (1)

[0075] in, is the lower limit of cathode inlet pressure; is the cathode inlet pressure; is the upper limit of cathode inlet pressure.

[0076] Specifically, the derivation process of the intake safety model is as follows.

[0077] (1) Fuel cell intake involves intake mass flow , intake pressure There are two core parameters, among which the cathode air intake is mainly constrained by the air compressor. The centrifugal air compressor has a surge boundary (i.e., maximum pressure boundary) and a minimum pressure boundary. The specific expressions are as follows.

[0078] (2)

[0079] in, and They represent the upper and lower limits of the cathode inlet pressure that can be achieved at the current air molar flow rate determined by the air compressor, q represents the intake air mass flow rate, and are the characteristic parameters of the upper and lower boundaries, respectively, depending on the specific air compressor model, Indicates cathode inlet pressure.

[0080] (2) The intake pressure is also affected by the fuel cell itself. Different types of fuel cells have different upper and lower limits for intake pressure. Considering the pressure resistance of the fuel cell proton exchange membrane, there are also requirements for the intake pressure difference between the anode and cathode, which can be specifically expressed as follows.

[0081] (3)

[0082] in, 、 They represent the upper and lower limits of the cathode inlet pressure determined by the fuel cell body respectively; is the anode inlet pressure; 、 They represent the upper and lower limits of the anode air inlet pressure determined by the fuel cell body, 、 are the upper and lower limits of the anode and cathode pressure difference, respectively.

[0083] (3) Combining the requirements of the air compressor and fuel cell, the pressure difference between the cathode and the cathode is averaged, and the intake safety constraint is constructed based on the fuel cell cathode pressure, resulting in the intake safety model shown in Equation (1).

[0084] In step S2, the expression of the water security model is as follows.

[0085] (4)

[0086] in, is the water content of the proton exchange membrane of the fuel cell; EW is the molar mass of the proton exchange membrane; is the dry film density; is the thickness of the proton exchange membrane; is the water concentration diffusion rate between the anode and the proton exchange membrane; Electroosmotic drag water transfer rate; is the diffusion rate of water concentration between the cathode and the proton exchange membrane.

[0087] Specifically, the water content of the fuel cell proton exchange membrane It can indicate a dry flooding failure of the fuel cell membrane, so the water content should be kept in a safe range.

[0088] (5)

[0089] Proton exchange membrane water content Determined by three water transport modes: electroosmotic drag, concentration diffusion and pressure difference diffusion, , so the water content of the proton exchange membrane It can be expressed as follows.

[0090] (6)

[0091] (7)

[0092] (8)

[0093] in, is the electroosmotic drag water transfer rate; is the electroosmotic drag coefficient; is the water diffusivity; is the water content gradient on both sides; is the water concentration diffusion rate between the anode and the proton exchange membrane, is the diffusion rate of water concentration between the cathode and the proton exchange membrane.

[0094] At a certain moment in the operation of a fuel cell, the current density can be considered as a variable, and the other parameters are constants.

[0095] As an optional implementation, in step S2, the expression of the thermal safety model is as follows.

[0096] (9)

[0097] in, The maximum heat dissipation that the cooling system can provide; Producing heat for fuel cells; To dissipate heat for exhaust gases.

[0098] Specifically, a fuel cell should maintain heat dissipation balance during operation so that its operating temperature remains within an appropriate operating range. The heat generated by a fuel cell comes from the chemical energy of the hydrogen-oxygen reaction, which is converted into electrical energy and thermodynamic energy as follows.

[0099] (10)

[0100] in, represents the chemical energy of the fuel cell reaction, is the output power, is the enthalpy of hydrogen reaction, N is the number of fuel cell cells, I is the current, F is the Faraday constant.

[0101] The thermal safety requirement of fuel cells is that the heat dissipation is greater than the heat generated. The heat dissipation methods of fuel cells include exhaust gas heat dissipation , heat dissipation of the fuel cell body and cooling system , which can be expressed as follows.

[0102] (11)

[0103] (12)

[0104] in, is the oxygen mass flow rate at the cathode inlet, is the specific heat capacity of oxygen, is the hydrogen mass flow rate at the anode inlet, is the specific heat capacity of hydrogen, is the mass flow rate of water produced by the reaction, is the specific heat of water, is the fuel cell gas inlet and outlet temperature difference, is the cooling water mass flow rate, is the specific heat capacity of cooling water, is the temperature difference between the inlet and outlet of the fuel cell cooling water.

[0105] Exhaust gas volume and fuel cell intake air mass flow rate q , inlet and outlet temperature difference and reaction current Therefore, the thermal safety of the fuel cell can be expressed as the thermal safety model shown in formula (9).

[0106] As an optional implementation, in step S2, the expression of the electrical safety model is as follows.

[0107] (13)

[0108] in, is the fuel cell cell voltage; is the Nernst voltage; is the activation polarization voltage; is the ohmic polarization voltage; is the concentration polarization voltage.

[0109] Specifically, when the fuel cell voltage is high, the proton exchange membrane and voltage decay rate are high. At low voltage, the gas distribution on the proton exchange membrane is uneven, which easily leads to local hot spots and causes membrane perforation. Therefore, the fuel cell cell voltage limit is as follows.

[0110] (14)

[0111] At the same time, the fuel cell voltage is also a function of current density, anode and cathode inlet pressure, and membrane water content as follows.

[0112] (15)

[0113] (16)

[0114] (17)

[0115] (18)

[0116] (19)

[0117] in, R is the gas constant, T is the fuel cell temperature, is the water partial pressure, and They are the hydrogen partial pressure and the oxygen partial pressure, both of which can be expressed by the anode and cathode inlet pressures; are the fitting parameters, , is the membrane area, is the limiting current density.

[0118] Step S3: determining the safety margin of the initial fuel cell based on the safety model of the initial fuel cell.

[0119] As an optional implementation, step S3 specifically includes the following steps.

[0120] In step S31 , a fuel cell state space is established with current density, cathode air intake pressure, and oxygen stoichiometric ratio as variables.

[0121] Among them, the mass flow rate The conversion to oxygen stoichiometry is as follows.

[0122] (20)

[0123] in, is the oxygen stoichiometric ratio, which is expressed as the ratio of the cathode intake mass to the reaction consumption mass. is the molar mass of water vapor, is the mass fraction of oxygen in the air.

[0124] Step S32: Traverse all state points in the fuel cell state space to identify critical state points on the initial fuel cell safety model. Traverse all state points and mark critical state points on the fuel cell's intake safety model, water safety model, thermal safety model, and electrical safety model.

[0125] Step S33, using the least square method, fit each critical state point to obtain multiple safety boundaries as the safety boundaries of the initial fuel cell. The safety boundary diagram of the initial fuel cell is as follows: Figure 2 As shown, Represents the safety boundary, which is represented as follows.

[0126] (twenty one)

[0127] in, ( n=1,2.. ) represent different security boundaries.

[0128] Step S4, based on the initial fuel cell safety margin, calculate the initial fuel cell safety interval volume. Combine multiple safety margins and perform triple integration on the multiple safety margins to obtain the initial fuel cell safety interval volume. Figure 2 The safety interval of the fuel cell is shown.

[0129] Step S5, after the fuel cell has been running for a period of time, the operating parameters of the fuel cell at the current moment are obtained, and based on the operating parameters of the fuel cell at the current moment and the fuel cell degradation process model, the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment are obtained; the fuel cell degradation process model is constructed based on the initial system parameters of the fuel cell and the operating parameters of the fuel cell at the previous moment; the operating parameters include: current density, cathode intake pressure and oxygen stoichiometric ratio.

[0130] Specifically, during fuel cell operation, platinum catalyst particles dissolve and agglomerate, reducing the catalyst surface area. Fluoride ions are released from the proton exchange membrane, reducing the membrane thickness. Throughout the fuel cell's lifecycle, as the catalyst surface area and membrane thickness change, the safety limits of the "gas-water-electricity-heat" system also change accordingly, shrinking the safety margin and reducing the volume of the safe zone. Therefore, it is necessary to use a fuel cell degradation process model to determine the proton exchange membrane thickness and catalyst surface area after degradation, thereby obtaining the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment.

[0131] As an optional implementation, in step S5, the fuel cell degradation process model is expressed as follows.

[0132] (twenty two)

[0133] (twenty three)

[0134] (twenty four)

[0135] in, represents the initial surface area of ​​the catalyst, represents the peak area, u represents the scanning speed, Indicates the mass of platinum. is the surface area of ​​the catalyst at the current moment; are the fitting parameters of the recession process model; are the fitting parameters of the recession process model; is the reference air pressure; is the initial film thickness; are the fitting parameters of the recession process model; is the activation energy of membrane degradation.

[0136] Step S6: Based on the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment, the initial fuel cell safety model is corrected to obtain a corrected fuel cell safety model at the current moment.

[0137] Specifically, the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment are used to update the initial proton exchange membrane thickness and initial catalyst surface area when constructing the initial fuel cell safety model, and the initial fuel cell safety model is corrected.

[0138] Step S7: Based on the revised fuel cell safety model at the current moment, the safety margin of the fuel cell at the current moment is obtained. The method for determining the safety margin of the fuel cell at the current moment is the same as the method for calculating the initial safety margin of the fuel cell.

[0139] Step S8: Calculate the safe interval volume of the fuel cell at the current moment based on the safe margin of the fuel cell at the current moment. The method for determining the safe interval volume of the fuel cell at the current moment is the same as the method for calculating the initial safe interval volume of the fuel cell.

[0140] Step S9: determining the safety radius of the fuel cell at the current moment based on the operating parameters and safety margin of the fuel cell at the current moment.

[0141] Specifically, the fuel cell state is a point within the safety range of the fuel cell. The minimum distance between the fuel cell state at the current moment and the safety boundary is calculated and defined as the safety radius. The operating parameters of the fuel cell at the current moment are marked in the safety boundary model, and the safety radius is calculated. The formula for determining the safety radius is as follows.

[0142] (25)

[0143] in, Indicates the distance between the fuel cell's current state and each safety boundary. X Status point. If X The state point is in the safe range The fuel cell safety radius is , otherwise 0.

[0144] Step S10 , obtaining a comprehensive safety index value of the fuel cell based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at the current moment, and the safety radius.

[0145] As an optional implementation, step S10 specifically includes the following steps.

[0146] Step S101, based on the fuel cell's current safety interval volume and the fuel cell's initial safety interval volume, obtain the fuel cell degradation ratio. During the operation of the fuel cell, due to the degradation of fuel cell performance parameters, the fuel cell safety margin shrinks. The evaluation method of fuel cell degradation characterized by a single variable proton exchange membrane thickness, catalyst surface area or voltage degradation is obviously not comprehensive. This application uses the fuel cell degradation ratio to calculate the fuel cell degradation ratio. Defined as the current safe zone volume and the volume of the initial safety interval The ratio of the fuel cell degradation degree ratio is obtained as follows.

[0147] (26)

[0148] in, is the fuel cell degradation ratio; is the safe range volume of the fuel cell at the current moment; is the initial safety interval volume of the fuel cell.

[0149] In step S102, a comprehensive fuel cell safety index is calculated based on the fuel cell degradation ratio and the fuel cell's current safety radius. The greater the fuel cell's performance degradation, the weaker its risk tolerance. Therefore, the comprehensive safety of a fuel cell must be determined by combining the degradation level with the current safety level. The expression for defining the comprehensive fuel cell safety index is as follows.

[0150] (27)

[0151] in, is the comprehensive safety index value of the fuel cell; is the safety radius of the fuel cell at the current moment.

[0152] Step S11 : evaluating the safety performance of the fuel cell using the comprehensive safety index value of the fuel cell.

[0153] Calculate the comprehensive safety index value of fuel cells , and output to the electronic control unit ECU, Make a judgment, if , the fuel cell safety is too low, so it stops running; if , then repeat steps S5 to S11.

[0154] The beneficial effects of this application are: 1) This application comprehensively considers the comprehensive safety requirements of fuel cells "gas-water-electricity-heat", establishes the safety boundary of fuel cell operation, and takes into account the degradation of key components in the fuel cell (i.e., catalyst and proton exchange membrane) and the safety level of the current state of the fuel cell, and jointly determines the comprehensive safety index value of the fuel cell, thereby improving the reliability of the fuel cell safety assessment.

[0155] 2) Compared with fuel cell safety evaluation methods based on deep learning and other algorithms, the safety boundary model and decay model of this application are simple, require less computing power, and have strong real-time performance.

[0156] Based on the same inventive concept, embodiments of the present application also provide a safety-boundary-based fuel cell safety performance assessment system for implementing the aforementioned safety-boundary-based fuel cell safety performance assessment method. The solution provided by this system is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more of the following embodiments of the safety-boundary-based fuel cell safety performance assessment system can be found in the limitations of the safety-boundary-based fuel cell safety performance assessment method described above and will not be repeated here.

[0157] In an exemplary embodiment, Figure 3As shown, a fuel cell safety performance evaluation system based on safety boundaries is provided, which includes the following modules.

[0158] The parameter acquisition unit 1 is used to acquire the initial system parameters of the air compressor and the initial system parameters of the fuel cell system. The initial system parameters are the system parameters at the time of leaving the factory.

[0159] The initial fuel cell safety model building unit 2 is used to build an initial fuel cell safety model based on the initial system parameters of the air compressor and the initial system parameters of the fuel cell. The safety model includes: an intake safety model, a water safety model, a thermal safety model, and an electrical safety model.

[0160] The initial fuel cell safety margin determination unit 3 is configured to determine the safety margin of the initial fuel cell based on the safety model of the initial fuel cell.

[0161] The initial safety interval volume determination unit 4 is configured to calculate the initial safety interval volume of the fuel cell based on the initial safety margin of the fuel cell.

[0162] The proton exchange membrane thickness and catalyst surface area updating unit 5 is configured to obtain the current operating parameters of the fuel cell after the fuel cell has been operating for a period of time, and to obtain the current proton exchange membrane thickness and catalyst surface area of ​​the fuel cell based on the current operating parameters and a fuel cell degradation process model. The fuel cell degradation process model is constructed based on the initial system parameters of the fuel cell and the operating parameters of the fuel cell at the previous moment. The operating parameters include current density, cathode inlet pressure, and oxygen stoichiometric ratio.

[0163] The corrected fuel cell safety model determination unit 6 is used to correct the initial fuel cell safety model based on the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment to obtain the corrected fuel cell safety model at the current moment.

[0164] The current moment safety margin determination unit 7 is configured to obtain the current moment safety margin of the fuel cell based on the revised current moment safety model of the fuel cell.

[0165] The safety interval volume determination unit 8 at the current moment is used to calculate the safety interval volume of the fuel cell at the current moment based on the safety margin of the fuel cell at the current moment.

[0166] The safety radius determination unit 9 at the current moment is used to determine the safety radius of the fuel cell at the current moment based on the operating parameters and safety margin of the fuel cell at the current moment.

[0167] The comprehensive safety index value determining unit 10 is used to obtain the comprehensive safety index value of the fuel cell based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at a current moment, and the safety radius.

[0168] The safety performance evaluation unit 11 is used to evaluate the safety performance of the fuel cell using the comprehensive safety index value of the fuel cell.

[0169] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0170] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above-mentioned embodiments. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0171] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[0172] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0173] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A fuel cell safety performance evaluation method based on safety margin, characterized in that: The fuel cell safety performance evaluation method based on safety margin includes: Obtaining initial system parameters of the air compressor and the fuel cell in the fuel cell system; the initial system parameters are the system parameters at the time of leaving the factory; Based on the initial system parameters of the air compressor and the initial system parameters of the fuel cell, an initial fuel cell safety model is constructed; the safety model includes: an intake safety model, a water safety model, a thermal safety model, and an electrical safety model; Determine the safety boundary of the initial fuel cell based on the safety model of the initial fuel cell; Based on the initial fuel cell safety margin, calculate the initial safety interval volume of the fuel cell; After the fuel cell has been running for a period of time, the operating parameters of the fuel cell at the current moment are obtained, and based on the operating parameters of the fuel cell at the current moment and a fuel cell degradation process model, the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment are obtained; the fuel cell degradation process model is constructed based on the initial system parameters of the fuel cell and the operating parameters of the fuel cell at the previous moment; the operating parameters include: current density, cathode inlet pressure, and oxygen stoichiometric ratio; Based on the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment, the initial fuel cell safety model is modified to obtain a modified fuel cell safety model at the current moment; Based on the revised safety model of the fuel cell at the current moment, the safety boundary of the fuel cell at the current moment is obtained; Based on the safety boundary of the fuel cell at the current moment, calculate the safety interval volume of the fuel cell at the current moment; Determine the safety radius of the fuel cell at the current moment based on the operating parameters and safety margin of the fuel cell at the current moment; Based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at the current moment, and the safety radius, a comprehensive safety index value of the fuel cell is obtained; Use the comprehensive safety index value of fuel cells to evaluate the safety performance of fuel cells; Based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at the current moment, and the safety radius, the comprehensive safety index value of the fuel cell is obtained, specifically including: Obtaining a fuel cell degradation ratio based on the fuel cell's current safety interval volume and the fuel cell's initial safety interval volume; Based on the fuel cell degradation ratio and the fuel cell safety radius at the current moment, a comprehensive safety index value of the fuel cell is obtained.

2. The fuel cell safety performance evaluation method based on safety margin according to claim 1, characterized in that: The expression of the intake safety model is: ； in, is the lower limit of cathode inlet pressure; is the cathode inlet pressure; is the upper limit of cathode inlet pressure; The expression of the water security model is: ； in, is the water content of the proton exchange membrane of the fuel cell; EW is the molar mass of the proton exchange membrane; is the dry film density; is the thickness of the proton exchange membrane; is the water concentration diffusion rate between the anode and the proton exchange membrane; Electroosmotic drag water transfer rate; is the water concentration diffusion rate between the cathode and the proton exchange membrane.

3. The fuel cell safety performance evaluation method based on safety margin according to claim 2, characterized in that: The expression of thermal safety model is: ； in, The maximum heat dissipation that the cooling system can provide; Producing heat for fuel cells; To dissipate heat for exhaust gases.

4. The fuel cell safety performance evaluation method based on safety margin according to claim 3, characterized in that: The expression of the electrical safety model is: in, is the fuel cell cell voltage; is the Nernst voltage; is the activation polarization voltage; is the ohmic polarization voltage; is the concentration polarization voltage.

5. The fuel cell safety performance evaluation method based on safety margin according to claim 4, characterized in that: Based on the initial fuel cell safety model, determine the safety boundary of the initial fuel cell, including: The fuel cell state space is established with current density, cathode inlet pressure and oxygen stoichiometric ratio as variables; Traversing all state points in the fuel cell state space, and determining the critical state point on the safety model of the initial fuel cell; The critical state points are fitted using the least squares method to obtain multiple safety boundaries as the initial safety boundaries of the fuel cell.

6. The fuel cell safety performance evaluation method based on safety margin according to claim 5, characterized in that: Based on the initial fuel cell safety margin, calculate the initial safety interval volume of the fuel cell, including: The initial safety interval volume of the fuel cell is obtained by combining multiple safety boundaries and performing triple integration on the multiple safety boundaries.

7. The fuel cell safety performance evaluation method based on safety margin according to claim 6, characterized in that: The expression of the fuel cell degradation process model is: ； in, ; are the fitting parameters of the recession process model; is the Faraday constant; is the gas constant; is the fuel cell temperature; is the fuel cell cell voltage; is the current density; is the ohmic impedance; are the fitting parameters of the recession process model; is the partial pressure of oxygen; is the reference air pressure; is the initial film thickness; are the fitting parameters of the recession process model; is the activation energy of membrane degradation.

8. The fuel cell safety performance evaluation method based on safety margin according to claim 7, characterized in that: The expression of the fuel cell degradation ratio is: ； in, is the fuel cell degradation ratio; is the safe range volume of the fuel cell at the current moment; is the initial safety interval volume of the fuel cell; The expression of the comprehensive safety index value of the fuel cell is: ； in, is the comprehensive safety index value of the fuel cell; is the safety radius of the fuel cell at the current moment.

9. A fuel cell safety performance evaluation system based on safety margin, characterized in that: The fuel cell safety performance evaluation system based on safety margin is used to implement the fuel cell safety performance evaluation method based on safety margin according to any one of claims 1 to 8, and the fuel cell safety performance evaluation system based on safety margin includes: A parameter acquisition unit, used to acquire initial system parameters of the air compressor and the fuel cell in the fuel cell system; the initial system parameters are the system parameters at the time of leaving the factory; An initial fuel cell safety model building unit is used to build an initial fuel cell safety model based on the initial system parameters of the air compressor and the initial system parameters of the fuel cell; the safety model includes: an intake safety model, a water safety model, a thermal safety model, and an electrical safety model; an initial fuel cell safety boundary determination unit, configured to determine the safety boundary of the initial fuel cell based on a safety model of the initial fuel cell; an initial safety interval volume determination unit, configured to calculate an initial safety interval volume of the fuel cell based on an initial safety margin of the fuel cell; a proton exchange membrane thickness and catalyst surface area updating unit, configured to obtain the operating parameters of the fuel cell at the current moment after the fuel cell has been operating for a period of time, and to obtain the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment based on the operating parameters of the fuel cell at the current moment and a fuel cell degradation process model; the fuel cell degradation process model is constructed based on the initial system parameters of the fuel cell and the operating parameters of the fuel cell at the previous moment; the operating parameters include: current density, cathode inlet pressure, and oxygen stoichiometric ratio; a unit for determining a revised safety model of the fuel cell at the current moment, configured to revise the initial safety model of the fuel cell based on the proton exchange membrane thickness and catalyst surface area of ​​the fuel cell at the current moment, thereby obtaining a revised safety model of the fuel cell at the current moment; a current moment safety boundary determination unit, configured to obtain a current moment safety boundary of the fuel cell based on the revised current moment safety model of the fuel cell; a safety interval volume determination unit at a current moment, configured to calculate the safety interval volume of the fuel cell at a current moment based on the safety boundary of the fuel cell at the current moment; a safety radius determination unit at a current moment, configured to determine a safety radius of the fuel cell at a current moment based on the operating parameters and safety margin of the fuel cell at the current moment; The comprehensive safety index value determination unit is used to obtain the comprehensive safety index value of the fuel cell based on the initial safety interval volume of the fuel cell, the safety interval volume of the fuel cell at the current moment, and the safety radius; specifically, it includes: Obtaining a fuel cell degradation ratio based on the fuel cell's current safety interval volume and the fuel cell's initial safety interval volume; Based on the fuel cell degradation ratio and the fuel cell safety radius at the current moment, a comprehensive safety index value of the fuel cell is obtained; The safety performance evaluation unit is used to evaluate the safety performance of the fuel cell using the comprehensive safety index value of the fuel cell.

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