Impedance difference evaluation method and device for fuel cell stack and membrane electrode, vehicle and equipment

Abstract

The invention relates to an impedance difference evaluation method and device for a fuel cell stack and a membrane electrode, a vehicle and equipment, which are used for improving the overall performance and durability of a fuel cell system. The method comprises the following steps: acquiring output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition moment; assigning a value to the stack equivalent circuit according to the output voltage and the output current of the fuel cell stack, and estimating the impedance of the fuel cell stack; assigning the equivalent circuit of each membrane electrode according to the output voltage and the output current of each membrane electrode of the fuel cell stack, and estimating the impedance of each membrane electrode; according to the impedance of each membrane electrode and the impedance of the fuel cell stack, respectively determining the impedance deviation degree of each membrane electrode relative to the fuel cell stack; and according to the impedance deviation degree of each membrane electrode relative to the fuel cell stack, determining the impedance dispersion degree of all the membrane electrodes relative to the fuel cell stack, and further evaluating the impedance difference between the fuel cell stack and the membrane electrodes.

Description

Technical Field

[0001] The present application relates to the field of fuel cells, and specifically to a method, device, vehicle and equipment for evaluating impedance differences between a fuel cell stack and a membrane electrode. Background Art

[0002] The vehicle fuel cell engine includes a fuel cell stack and other subsystem accessories, in which the stack is composed of multiple monomer membrane electrodes. In the actual working process, the gas supply and water discharge will lead to inconsistency in the mass transfer process, resulting in inconsistency in the physical properties between the membrane electrodes, such as inconsistency in the impedance of all membrane electrodes and fuel cell stacks, which ultimately manifests as inconsistent performance output.

[0003] However, there is no solution in the prior art for diagnosing the impedance inconsistency problem of membrane electrode and fuel cell stacks. For example, in: 202010068829.0, a model-based proton exchange membrane fuel cell impedance online estimation method is provided. This solution uses a genetic particle swarm hybrid optimization algorithm to perform parameter identification on the dynamic fuel cell lumped parameter model, and applies the high-frequency step current signal to the identified dynamic fuel cell lumped parameter model to obtain high-frequency voltage response data; the time domain data is processed by Hanning window, and the voltage and current of the fuel cell are converted from time domain to frequency domain using fast Fourier transform, and the fuel cell impedance at each frequency is calculated based on the transformed voltage and current; this solution is to establish a training model after collecting offline data sets through parameter identification, and then realize impedance estimation of the fuel cell stack. This method cannot diagnose all impedance inconsistencies of membrane electrodes and fuel cell stacks.

[0004] Therefore, a reasonable diagnosis can be made for the impedance inconsistency of all membrane electrode and fuel cell stacks. Summary of the invention

[0005] The present invention provides a method, device, vehicle and equipment for evaluating the impedance difference between a fuel cell stack and a membrane electrode, which are used to improve the overall performance and durability of the fuel cell system.

[0006] The technical solution of the present invention is:

[0007] The present application provides a method for evaluating the impedance difference between a fuel cell stack and a membrane electrode, comprising:

[0008] Obtaining the output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition moment;

[0009] Assigning a value to a pre-established fuel cell stack equivalent circuit according to the output voltage and output current of the fuel cell stack at the current acquisition moment, and estimating the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit;

[0010] According to the output voltage and output current of each membrane electrode of the fuel cell stack at the current acquisition time, a value is assigned to each pre-established membrane electrode equivalent circuit, and the impedance of each membrane electrode is estimated according to the assigned membrane electrode equivalent circuit;

[0011] Determining the impedance deviation of each membrane electrode relative to the fuel cell stack according to the impedance of each membrane electrode and the impedance of the fuel cell stack;

[0012] Determining the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack;

[0013] The impedance difference between the fuel cell stack and the membrane electrode is evaluated based on the impedance dispersion of all membrane electrodes relative to the fuel cell stack.

[0014] Preferably, the step of estimating the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit comprises:

[0015] According to the output current I of the fuel cell stack at the current acquisition time w，k s , capacitor C in the battery stack equivalent circuit s and the electrochemical impedance R in the battery stack equivalent circuit C s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s ;

[0016] According to the open circuit voltage E of the fuel cell stack at the current acquisition time ocv，k s , the output voltage U of the fuel cell stack at the current acquisition time in，k s , the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s and the output current I of the fuel cell stack at the current acquisition time w，k s , estimate the impedance R of the fuel cell stack m，k s .

[0017] Preferably, the step of estimating the impedance of each membrane electrode according to each membrane electrode equivalent circuit after the assignment includes:

[0018] According to the output current I of each membrane electrode at the current collection time w，k c , the capacitance C in each membrane electrode equivalent circuit c and the electrochemical impedance R in the membrane electrode equivalent circuit C c, determine the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c ;

[0019] According to the open circuit voltage E of each membrane electrode at the current acquisition time ocv，k c , the output voltage U of each membrane electrode at the current acquisition time in，k c , the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c and the output current I of each membrane electrode at the current acquisition time w，k c , respectively estimate the impedance R of each membrane electrode m，k c .

[0020] Preferably, the step of determining the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack comprises:

[0021] Determining the average value of the impedance deviations of all membrane electrodes relative to the fuel cell stack according to the impedance deviations of each membrane electrode relative to the fuel cell stack;

[0022] The impedance dispersion of all membrane electrodes relative to the fuel cell stack is determined according to the impedance deviation of each membrane electrode relative to the fuel cell stack and the average value of the impedance deviation of all membrane electrodes relative to the fuel cell stack.

[0023] Preferably, the step of evaluating the impedance difference between the fuel cell stack and the membrane electrode according to the impedance dispersion of all membrane electrodes relative to the fuel cell stack comprises:

[0024] Comparing the impedance dispersion of all membrane electrodes relative to the fuel cell stack with a preset impedance dispersion range;

[0025] If the impedance dispersion of all membrane electrodes relative to the fuel cell stack exceeds a preset impedance dispersion range, it is determined that the impedance difference between the fuel cell stack and the membrane electrode does not meet the requirement;

[0026] If the impedance dispersion of all membrane electrodes relative to the fuel cell stack is within a preset impedance dispersion range, it is determined that the impedance difference between the fuel cell stack and the membrane electrode meets the requirement.

[0027] Preferably, when the current collection time is the first collection time, according to the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C sand sampling interval Δt, determine the capacitor terminal voltage U of the stack equivalent circuit s at the current sampling moment D，k s ;

[0028] When the current collection time is the second or later collection time, according to the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s , sampling interval Δt and the capacitor terminal voltage U of the stack equivalent circuit s at the last sampling moment D，k-1 s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s .

[0029] Preferably, when the current acquisition moment is the first acquisition moment, according to the output current I of each membrane electrode at the current acquisition moment w，k c , the capacitance C in each membrane electrode equivalent circuit c c , the electrochemical impedance R in each membrane electrode equivalent circuit c C c and sampling interval Δt, determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current sampling moment D，k c ;

[0030] When the current acquisition time is the second or later acquisition time, according to the output current I of each membrane electrode at the current acquisition time w，k c , the capacitance C in each membrane electrode equivalent circuit c , the electrochemical impedance R in each membrane electrode equivalent circuit C c , sampling interval Δt and the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the last sampling moment D，k-1 c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current acquisition time D，k c .

[0031] On the other hand, the embodiment of the present application further provides a device for evaluating the impedance difference between a fuel cell stack and a membrane electrode, comprising:

[0032] An acquisition module, used to acquire the output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition moment;

[0033] A fuel cell stack impedance estimation module is used to assign a value to a pre-established fuel cell stack equivalent circuit according to the output voltage and output current of the fuel cell stack at the current acquisition moment, and to estimate the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit;

[0034] The membrane electrode impedance estimation module is used to assign values ​​to each pre-established membrane electrode equivalent circuit according to the output voltage and output current of each membrane electrode of the fuel cell stack at the current acquisition time, and estimate the impedance of each membrane electrode according to the assigned membrane electrode equivalent circuit;

[0035] An impedance deviation determination module, used to determine the impedance deviation of each membrane electrode relative to the fuel cell stack according to the impedance of each membrane electrode and the impedance of the fuel cell stack;

[0036] An impedance dispersion determination module, used to determine the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack;

[0037] The impedance difference evaluation module is used to evaluate the impedance difference between the fuel cell stack and the membrane electrode according to the impedance dispersion of all membrane electrodes relative to the fuel cell stack.

[0038] Preferably, the fuel cell stack impedance estimation module comprises:

[0039] The first capacitor terminal voltage determination unit is used to determine the output current I of the fuel cell stack at the current acquisition time. w，k s , capacitor C in the battery stack equivalent circuit s and the electrochemical impedance R in the battery stack equivalent circuit C s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s ;

[0040] The first impedance determination unit is used to determine the open circuit voltage E of the fuel cell stack at the current acquisition time. ocv，k s , the output voltage U of the fuel cell stack at the current acquisition time in，k s , the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s and the output current I of the fuel cell stack at the current acquisition time w，k s , estimate the impedance R of the fuel cell stack m，k s .

[0041] Preferably, the membrane electrode impedance estimation module comprises:

[0042] The second capacitor terminal voltage determination module is used to determine the output current I of each membrane electrode at the current acquisition time. w，k c , the capacitance C in each membrane electrode equivalent circuit c and the electrochemical impedance R in the membrane electrode equivalent circuit C c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c ;

[0043] The second impedance determination unit is used to determine the open circuit voltage E of each membrane electrode at the current acquisition time. ocv，k c , the output voltage U of each membrane electrode at the current acquisition time in，k c , the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c and the output current I of each membrane electrode at the current acquisition time w，k c , respectively estimate the impedance R of each membrane electrode m，k c .

[0044] Preferably, the impedance dispersion determination module includes:

[0045] An impedance deviation mean value determination unit, used to determine a mean value of impedance deviations of all membrane electrodes relative to the fuel cell stack according to the impedance deviations of each membrane electrode relative to the fuel cell stack;

[0046] The impedance dispersion determination unit is used to determine the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack and the average value of the impedance deviation of all membrane electrodes relative to the fuel cell stack.

[0047] Preferably, the impedance difference evaluation module includes:

[0048] A comparison unit, used for comparing the impedance dispersion of all membrane electrodes relative to the fuel cell stack with a preset impedance dispersion range;

[0049] A first impedance difference evaluation unit, configured to determine that the impedance difference between the fuel cell stack and the membrane electrode does not meet the requirement if the impedance dispersion of all membrane electrodes relative to the fuel cell stack exceeds a preset impedance dispersion range;

[0050] The second impedance difference evaluation unit is used to determine whether the impedance difference between the fuel cell stack and the membrane electrode meets the requirement if the impedance dispersion of all membrane electrodes relative to the fuel cell stack is within a preset impedance dispersion range.

[0051] Preferably, when the current collection time is the first collection time, according to the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s and sampling interval Δt, determine the capacitor terminal voltage U of the stack equivalent circuit s at the current sampling moment D，k s ;

[0052] When the current collection time is the second or later collection time, according to the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s , sampling interval Δt and the capacitor terminal voltage U of the stack equivalent circuit s at the last sampling moment D，k-1 s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s .

[0053] Preferably, when the current acquisition moment is the first acquisition moment, according to the output current I of each membrane electrode at the current acquisition moment w，k c , the capacitance C in each membrane electrode equivalent circuit c c , the electrochemical impedance R in each membrane electrode equivalent circuit c C c and sampling interval Δt, determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current sampling moment D，k c ;

[0054] When the current acquisition time is the second or later acquisition time, according to the output current I of each membrane electrode at the current acquisition time w，k c , the capacitance C in each membrane electrode equivalent circuit c , the electrochemical impedance R in each membrane electrode equivalent circuit C C , sampling interval Δt and the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the last sampling moment D，k-1 c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current acquisition time D，k c .

[0055] On the other hand, an embodiment of the present application further provides a vehicle, comprising the above-mentioned device for evaluating impedance differences between a fuel cell stack and a membrane electrode.

[0056] On the other hand, an embodiment of the present application also provides a control device, including a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein when the program or instruction is executed by the processor, the steps of the method for evaluating the impedance difference between a fuel cell stack and a membrane electrode are implemented as described above.

[0057] The beneficial effects of the present invention are:

[0058] According to the actual output current and output voltage of the fuel cell stack, the impedance of the fuel cell stack is estimated in combination with the equivalent circuit model of the fuel cell stack; according to the actual output current and output voltage of each membrane electrode, the impedance of each membrane electrode is estimated in combination with the equivalent circuit model of each membrane electrode; because the real-time data of the battery is used and no relevant model training is required, the impedance estimation method for the fuel cell stack and each membrane electrode is simple and the estimation result is accurate. According to the estimated impedance of the fuel cell stack and the impedance of each membrane electrode, the impedance dispersion of all membrane electrodes relative to the fuel cell stack is determined, and then the impedance difference of the fuel cell stack and the membrane electrode is evaluated; according to the evaluation results of the impedance difference of the fuel cell stack and the membrane electrode, the relevant control parameters of the fuel cell system can be adjusted, thereby improving the overall performance and durability of the fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of the flow of the method for evaluating the impedance difference between a fuel cell stack and a membrane electrode in an embodiment of the present application;

[0060] Figure 2 is a schematic diagram of a fuel cell system in an embodiment of the present application;

[0061] Figure 3 This is a schematic diagram of step S2 in an embodiment of the present application;

[0062] Figure 4 This is a schematic diagram of step S3 in an embodiment of the present application;

[0063] Figure 5 This is a schematic diagram of step S5 in an embodiment of the present application;

[0064] Figure 6 Schematic diagram of step S6 in the embodiment of the present application. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0066] The embodiment of the present application provides a method for evaluating the impedance difference between a fuel cell stack and a membrane electrode. The method can be effectively applied to various types of fuel cell stacks and fuel cell systems that change over time, and is applied to the FCCU (Fuel Cell Control Unit) controller in the fuel cell system; the method has a wide range of applications and can be applied to online applications of various fuel cell systems. Figure 1 , the method comprising:

[0067] S1, obtaining the output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition time;

[0068] S2, assigning a value to a pre-established fuel cell stack equivalent circuit according to the output voltage and output current of the fuel cell stack at the current acquisition time, and estimating the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit;

[0069] S3, assigning values ​​to each pre-established membrane electrode equivalent circuit according to the output voltage and output current of each membrane electrode of the fuel cell stack at the current acquisition time, and estimating the impedance of each membrane electrode according to the assigned membrane electrode equivalent circuit;

[0070] S4, determining the impedance deviation of each membrane electrode relative to the fuel cell stack according to the impedance of each membrane electrode and the impedance of the fuel cell stack;

[0071] S5, determining the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack;

[0072] S6, evaluating the impedance difference between the fuel cell stack and the membrane electrode according to the impedance dispersion of all membrane electrodes relative to the fuel cell stack.

[0073] The output current of each membrane electrode of the fuel cell stack at the current collection time k is equal to the output current of the fuel cell stack at the current collection time k. The output current of the fuel cell stack at the current collection time k / the output voltage of the fuel cell stack at the current collection time k and the output voltage of each membrane electrode of the fuel cell stack at the current collection time k are obtained by the prior art; refer to Figure 2The FCCU controller determines the output voltage of each membrane electrode at the current collection time k from the voltage collected by the CVM inspection controller, and the FCCU controller obtains the output voltage of the fuel cell stack at the current collection time k from the DCDC transformer.

[0074] In the embodiment of the present application, the fuel cell stack equivalent circuit and the membrane electrode equivalent circuit are pre-installed in the FCCU controller. When evaluating the impedance difference, it is only necessary to assign the collected relevant real-time parameters to the corresponding equivalent circuit to calculate the corresponding impedance value.

[0075] Since real-time data of the battery is used and there is no need for relevant model training, the impedance estimation method for the fuel cell stack and each membrane electrode is simple and the estimation result is accurate.

[0076] In addition, according to the final evaluation results of the impedance difference between the fuel cell stack and the membrane electrode, the relevant control parameters of the fuel cell system can be adjusted to improve the overall performance and durability of the fuel cell system.

[0077] Reference Figure 3 In the embodiment of the present application, in step S2, the step of estimating the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit includes:

[0078] S21, based on the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s and the electrochemical impedance R in the battery stack equivalent circuit C s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s ;

[0079] S22, according to the open circuit voltage E of the fuel cell stack at the current acquisition time ocv，k s , the output voltage U of the fuel cell stack at the current acquisition time in，k s , the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s and the output current I of the fuel cell stack at the current acquisition time w，k s , estimate the impedance R of the fuel cell stack m，k s .

[0080] Specifically, in step S21, when the current acquisition time k is the first acquisition time (ie, k=1), according to the output current I of the fuel cell stack at the first acquisition timew，1 s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s and sampling interval Δt, determine the capacitor terminal voltage U of the stack equivalent circuit s at the first sampling moment D，k s .

[0081] That is, through the formula:

[0082]

[0083] Calculate the capacitor terminal voltage U of the stack equivalent circuit s at the first acquisition moment D，1 s .

[0084] When the current collection time k is the second or later collection time (i.e., k≥2), according to the output current I of the fuel cell stack at the current collection time k w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s , sampling interval Δt and the capacitor terminal voltage U of the stack equivalent circuit s at the last sampling time (k-1) D，k-1 s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s .

[0085] That is, through the formula:

[0086]

[0087] Calculate the capacitor terminal voltage U of the stack equivalent circuit s at the kth acquisition moment D，k s .

[0088] Among them, the capacitor C in the above-mentioned battery stack equivalent circuit s s , electrochemical impedance R in the battery stack equivalent circuit C s , the sampling interval Δt is a preset value.

[0089] Then, in step S22, by formula:

[0090]

[0091] Estimating the impedance R of the fuel cell stack m，k s .

[0092] Reference Figure 4 In the embodiment of the present application, in step S3, the step of estimating the impedance of each membrane electrode according to the assigned membrane electrode equivalent circuit includes:

[0093] S31, according to the output current I of each membrane electrode at the current collection time w，k c , the capacitance C in each membrane electrode equivalent circuit c and the electrochemical impedance R in the membrane electrode equivalent circuit C c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c ;

[0094] S32, according to the open circuit voltage E of each membrane electrode at the current acquisition time ocv，k c , the output voltage U of each membrane electrode at the current acquisition time in，k c , the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c and the output current I of each membrane electrode at the current acquisition time w，k c , respectively estimate the impedance R of each membrane electrode m，k c .

[0095] In step S31, when the current acquisition time k is the first acquisition time (ie, k=1), according to the output current I of each membrane electrode at the first acquisition time w，1 c , the capacitance C in each membrane electrode equivalent circuit c c , the electrochemical impedance R in each membrane electrode equivalent circuit c C c and sampling interval Δt, determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the first sampling moment D，1 c .

[0096] That is, through the formula:

[0097]

[0098] Calculate the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the first acquisition moment D，1 c .

[0099] When the current acquisition time is the second or later acquisition time (i.e., k ≥ 2), according to the output current I of each membrane electrode at the current acquisition time w，kc , the capacitance C in each membrane electrode equivalent circuit c , the electrochemical impedance R in each membrane electrode equivalent circuit C c , sampling interval Δt and the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the last sampling moment D，k-1 c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current acquisition time D，k c .

[0100] That is, for the i-th membrane electrode, by the formula:

[0101]

[0102] Calculate the capacitor voltage U of the equivalent circuit c of the i-th membrane electrode at the k-th acquisition time D，k ci , I w，k ci is the output current of the i-th membrane electrode at the current acquisition time k, U D，k-1 ci is the capacitor terminal voltage of the equivalent circuit c of the ith membrane electrode at the k-1th acquisition moment, R C ci is the electrochemical impedance in the equivalent circuit c of the i-th membrane electrode, C ci is the capacitance in the equivalent circuit of the i-th membrane electrode. ci and the electrochemical impedance R in the equivalent circuit of the i-th membrane electrode C ci The corresponding parameters are equal to those in other membrane electrode equivalent circuits.

[0103] Then, in step S32, by formula:

[0104]

[0105] Estimate the impedance R of each membrane electrode m，k c .

[0106] In the embodiment of the present application, in step S4, according to the impedance of each membrane electrode and the impedance of the fuel cell stack, the impedance deviation of each membrane electrode relative to the fuel cell stack is determined by respectively determining the corresponding impedance deviation by the ratio of the impedance of each membrane electrode to the impedance of the fuel cell stack. Specifically, the formula is:

[0107]

[0108] The calculated impedance deviation between the i-th membrane electrode and the fuel cell stack is

[0109] Reference Figure 5 In the embodiment of the present application, in step S5, the step of determining the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack includes:

[0110] S51, according to the impedance deviation of each membrane electrode relative to the fuel cell stack, determine the average value of the impedance deviation of all membrane electrodes relative to the fuel cell stack; that is, by the formula:

[0111]

[0112] Calculate the mean impedance deviation of all membrane electrode relative to the fuel cell stack

[0113] S52, according to the impedance deviation of each membrane electrode relative to the fuel cell stack and the average value of the impedance deviation of all membrane electrodes relative to the fuel cell stack, the impedance dispersion of all membrane electrodes relative to the fuel cell stack is determined, that is, by the formula:

[0114]

[0115] Calculate the impedance dispersion σ of all membrane electrode systems relative to the fuel cell stack.

[0116] Reference Figure 6 In the embodiment of the present application, step S6 of evaluating the impedance difference between the fuel cell stack and the membrane electrode according to the impedance dispersion of all membrane electrodes relative to the fuel cell stack includes:

[0117] S61, comparing the impedance dispersion of all membrane electrodes relative to the fuel cell stack with a preset impedance dispersion range;

[0118] S62, if the impedance dispersion of all membrane electrodes relative to the fuel cell stack exceeds a preset impedance dispersion range, it is determined that the impedance difference between the fuel cell stack and the membrane electrode does not meet the requirement;

[0119] S63: If the impedance dispersion of all membrane electrodes relative to the fuel cell stack is within a preset impedance dispersion range, it is determined that the impedance difference between the fuel cell stack and the membrane electrode meets the requirement.

[0120] The above method in the embodiment of the present application, the above impedance evaluation method can evaluate the single-chip impedance of the fuel cell stack. The equivalent circuit model can be embedded in the fuel cell controller. The voltage of the single chip is collected based on the CVM patrol controller. Under power load variation, the impedance calculation result has good tracking performance, and the impedance result error is less than 10% under dynamic load variation conditions. Based on this impedance, after obtaining each membrane electrode of the stack, the difference index can be calculated based on steps S4 and S5.

[0121] On the other hand, the embodiment of the present application further provides a device for evaluating the impedance difference between a fuel cell stack and a membrane electrode, comprising:

[0122] An acquisition module, used to acquire the output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition moment;

[0123] A fuel cell stack impedance estimation module is used to assign a value to a pre-established fuel cell stack equivalent circuit according to the output voltage and output current of the fuel cell stack at the current acquisition moment, and to estimate the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit;

[0124] The membrane electrode impedance estimation module is used to assign values ​​to each pre-established membrane electrode equivalent circuit according to the output voltage and output current of each membrane electrode of the fuel cell stack at the current acquisition time, and estimate the impedance of each membrane electrode according to the assigned membrane electrode equivalent circuit;

[0125] An impedance deviation determination module, used to determine the impedance deviation of each membrane electrode relative to the fuel cell stack according to the impedance of each membrane electrode and the impedance of the fuel cell stack;

[0126] An impedance dispersion determination module, used to determine the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack;

[0127] The impedance difference evaluation module is used to evaluate the impedance difference between the fuel cell stack and the membrane electrode according to the impedance dispersion of all membrane electrodes relative to the fuel cell stack.

[0128] Preferably, the fuel cell stack impedance estimation module comprises:

[0129] The first capacitor terminal voltage determination unit is used to determine the output current I of the fuel cell stack at the current acquisition time. w，k s , capacitor C in the battery stack equivalent circuit s and the electrochemical impedance R in the battery stack equivalent circuit C s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s ;

[0130] The first impedance determination unit is used to determine the open circuit voltage E of the fuel cell stack at the current acquisition time. ocv，k s , the output voltage U of the fuel cell stack at the current acquisition time in，k s , the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，ks and the output current I of the fuel cell stack at the current acquisition time w，k s , estimate the impedance R of the fuel cell stack m，k s .

[0131] Preferably, the membrane electrode impedance estimation module comprises:

[0132] The second capacitor terminal voltage determination module is used to determine the output current I of each membrane electrode at the current acquisition time. w，k c , the capacitance C in each membrane electrode equivalent circuit c and the electrochemical impedance R in the membrane electrode equivalent circuit C c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c ;

[0133] The second impedance determination unit is used to determine the open circuit voltage E of each membrane electrode at the current acquisition time. ocv，k c , the output voltage U of each membrane electrode at the current acquisition time in，k c , the capacitor terminal voltage U of each membrane electrode equivalent circuit at the current acquisition time D，k c and the output current I of each membrane electrode at the current acquisition time w，k c , respectively estimate the impedance R of each membrane electrode m，k c .

[0134] Preferably, the impedance dispersion determination module includes:

[0135] An impedance deviation mean value determination unit, used to determine a mean value of impedance deviations of all membrane electrodes relative to the fuel cell stack according to the impedance deviations of each membrane electrode relative to the fuel cell stack;

[0136] The impedance dispersion determination unit is used to determine the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack and the average value of the impedance deviation of all membrane electrodes relative to the fuel cell stack.

[0137] Preferably, the impedance difference evaluation module includes:

[0138] A comparison unit, used for comparing the impedance dispersion of all membrane electrodes relative to the fuel cell stack with a preset impedance dispersion range;

[0139] A first impedance difference evaluation unit, configured to determine that the impedance difference between the fuel cell stack and the membrane electrode does not meet the requirement if the impedance dispersion of all membrane electrodes relative to the fuel cell stack exceeds a preset impedance dispersion range;

[0140] The second impedance difference evaluation unit is used to determine whether the impedance difference between the fuel cell stack and the membrane electrode meets the requirement if the impedance dispersion of all membrane electrodes relative to the fuel cell stack is within a preset impedance dispersion range.

[0141] Preferably, when the current collection time is the first collection time, according to the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s and sampling interval Δt, determine the capacitor terminal voltage U of the stack equivalent circuit s at the current sampling moment D，k s ;

[0142] When the current collection time is the second or later collection time, according to the output current I of the fuel cell stack at the current collection time w，k s , capacitor C in the battery stack equivalent circuit s , electrochemical impedance R in the battery stack equivalent circuit C s , sampling interval Δt and the capacitor terminal voltage U of the stack equivalent circuit s at the last sampling moment D，k-1 s , determine the capacitor terminal voltage U of the stack equivalent circuit s at the current acquisition time D，k s .

[0143] Preferably, when the current acquisition moment is the first acquisition moment, according to the output current I of each membrane electrode at the current acquisition moment w，k c , the capacitance C in each membrane electrode equivalent circuit c c , the electrochemical impedance R in each membrane electrode equivalent circuit c C c and sampling interval Δt, determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current sampling moment D，k c ;

[0144] When the current acquisition time is the second or later acquisition time, according to the output current I of each membrane electrode at the current acquisition time w，k c , the capacitance C in each membrane electrode equivalent circuit c, the electrochemical impedance R in each membrane electrode equivalent circuit C c , sampling interval Δt and the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the last sampling moment D，k-1 c , determine the capacitor terminal voltage U of each membrane electrode equivalent circuit c at the current acquisition time D，k c .

[0145] The impedance difference evaluation device of the fuel cell stack and the membrane electrode in the embodiment of the present application is a device corresponding to the above method, and has the same technical effect as the above method, namely: according to the output current and output voltage of the fuel cell stack actually collected, the impedance of the fuel cell stack is estimated in combination with the equivalent circuit model of the fuel cell stack; according to the output current and output voltage of each membrane electrode actually collected, the impedance of each membrane electrode is estimated in combination with the equivalent circuit model of each membrane electrode; because the real-time data of the battery is used, and there is no need to perform relevant model training, the impedance estimation method for the fuel cell stack and each membrane electrode is simple and the estimation result is accurate. According to the estimated impedance of the fuel cell stack and the impedance of each membrane electrode, the impedance dispersion of all membrane electrodes relative to the fuel cell stack is determined, and then the impedance difference evaluation of the fuel cell stack and the membrane electrode is realized; according to the evaluation results of the impedance difference of the fuel cell stack and the membrane electrode, the relevant control parameters of the fuel cell system can be adjusted, thereby improving the overall performance and durability of the fuel cell system.

[0146] On the other hand, an embodiment of the present application further provides a vehicle, comprising the above-mentioned device for evaluating impedance differences between a fuel cell stack and a membrane electrode.

[0147] On the other hand, an embodiment of the present application also provides a control device, including a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein when the program or instruction is executed by the processor, the steps of the method for evaluating the impedance difference between a fuel cell stack and a membrane electrode are implemented as described above.

[0148] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0149] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0150] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, relational terms such as "first" and "second" are used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements does not include those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0151] The technical solution provided by the present invention is described in detail above. The principle and implementation mode of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the present invention, and the content of this specification should not be understood as limiting the present invention. At the same time, for those skilled in the art, according to the present invention, there will be different forms of changes in the specific implementation mode and application scope. It is not necessary and impossible to list all the implementation modes here, and the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for evaluating the impedance difference between a fuel cell stack and a membrane electrode, characterized in that: include: Obtaining the output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition moment; Assigning a value to a pre-established fuel cell stack equivalent circuit according to the output voltage and output current of the fuel cell stack at the current acquisition moment, and estimating the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit; According to the output voltage and output current of each membrane electrode of the fuel cell stack at the current acquisition time, a value is assigned to each pre-established membrane electrode equivalent circuit, and the impedance of each membrane electrode is estimated according to the assigned membrane electrode equivalent circuit; Determining the impedance deviation of each membrane electrode relative to the fuel cell stack according to the impedance of each membrane electrode and the impedance of the fuel cell stack; Determining the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack; The impedance difference between the fuel cell stack and the membrane electrode is evaluated based on the impedance dispersion of all membrane electrodes relative to the fuel cell stack.

2. The method for evaluating the impedance difference between a fuel cell stack and a membrane electrode according to claim 1, characterized in that: The steps of estimating the impedance of the fuel cell stack according to the assigned stack equivalent circuit include: Determine the capacitor terminal voltage of the fuel cell stack equivalent circuit at the current collection time according to the output current of the fuel cell stack at the current collection time, the capacitance in the fuel cell stack equivalent circuit, and the electrochemical impedance in the fuel cell stack equivalent circuit; The impedance of the fuel cell stack is estimated based on the open circuit voltage of the fuel cell stack at the current collection time, the output voltage of the fuel cell stack at the current collection time, the capacitor terminal voltage of the fuel cell equivalent circuit at the current collection time, and the output current of the fuel cell stack at the current collection time.

3. The method for evaluating the impedance difference between a fuel cell stack and a membrane electrode according to claim 1, characterized in that: The steps of estimating the impedance of each membrane electrode according to the assigned membrane electrode equivalent circuits include: Determine the capacitor terminal voltage of each membrane electrode equivalent circuit at the current collection time according to the output current of each membrane electrode at the current collection time, the capacitance in each membrane electrode equivalent circuit and the electrochemical impedance in the membrane electrode equivalent circuit; The impedance of each membrane electrode is estimated according to the open circuit voltage of each membrane electrode at the current collection time, the output voltage of each membrane electrode at the current collection time, the capacitor terminal voltage of each membrane electrode equivalent circuit at the current collection time and the output current of each membrane electrode at the current collection time.

4. The method for evaluating the impedance difference between a fuel cell stack and a membrane electrode according to claim 1, characterized in that: The step of determining the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack comprises: Determining the average value of the impedance deviations of all membrane electrodes relative to the fuel cell stack according to the impedance deviations of each membrane electrode relative to the fuel cell stack; The impedance dispersion of all membrane electrodes relative to the fuel cell stack is determined according to the impedance deviation of each membrane electrode relative to the fuel cell stack and the average value of the impedance deviation of all membrane electrodes relative to the fuel cell stack.

5. The method for evaluating the impedance difference between a fuel cell stack and a membrane electrode according to claim 1, characterized in that: According to the impedance dispersion of all membrane electrodes relative to the fuel cell stack, the steps of evaluating the impedance difference between the fuel cell stack and the membrane electrode include: Comparing the impedance dispersion of all membrane electrodes relative to the fuel cell stack with a preset impedance dispersion range; If the impedance dispersion of all membrane electrodes relative to the fuel cell stack exceeds a preset impedance dispersion range, it is determined that the impedance difference between the fuel cell stack and the membrane electrode does not meet the requirement; If the impedance dispersion of all membrane electrodes relative to the fuel cell stack is within a preset impedance dispersion range, it is determined that the impedance difference between the fuel cell stack and the membrane electrode meets the requirement.

6. The method for evaluating the impedance difference between a fuel cell stack and a membrane electrode according to claim 2, characterized in that: When the current collection time is the first collection time, the capacitor terminal voltage of the stack equivalent circuit at the current collection time is determined according to the output current of the fuel cell stack at the current collection time, the capacitance in the stack equivalent circuit, the electrochemical impedance in the stack equivalent circuit and the sampling interval; When the current collection moment is the second or subsequent collection moment, the capacitor terminal voltage of the fuel cell stack equivalent circuit at the current collection moment is determined based on the output current of the fuel cell stack at the current collection moment, the capacitance in the fuel cell stack equivalent circuit, the electrochemical impedance in the fuel cell stack equivalent circuit, the sampling interval, and the capacitor terminal voltage of the fuel cell stack equivalent circuit at the previous collection moment.

7. The method for evaluating the impedance difference between a fuel cell stack and a membrane electrode according to claim 3, characterized in that: When the current acquisition moment is the first acquisition moment, the capacitor terminal voltage of each membrane electrode equivalent circuit at the current acquisition moment is determined according to the output current of each membrane electrode at the current acquisition moment, the capacitance in each membrane electrode equivalent circuit, the electrochemical impedance in each membrane electrode equivalent circuit and the sampling interval; When the current collection moment is the second or subsequent collection moment, the capacitor terminal voltage of each membrane electrode equivalent circuit at the current collection moment is determined according to the output current of each membrane electrode at the current collection moment, the capacitance in each membrane electrode equivalent circuit, the electrochemical impedance in each membrane electrode equivalent circuit, the sampling interval, and the capacitor terminal voltage of each membrane electrode equivalent circuit at the previous collection moment.

8. A device for evaluating the impedance difference between a fuel cell stack and a membrane electrode, characterized in that: include: An acquisition module, used to acquire the output voltage and output current of the fuel cell stack and each membrane electrode of the fuel cell stack at the current acquisition moment; A fuel cell stack impedance estimation module is used to assign a value to a pre-established fuel cell stack equivalent circuit according to the output voltage and output current of the fuel cell stack at the current acquisition moment, and to estimate the impedance of the fuel cell stack according to the assigned fuel cell stack equivalent circuit; The membrane electrode impedance estimation module is used to assign values ​​to each pre-established membrane electrode equivalent circuit according to the output voltage and output current of each membrane electrode of the fuel cell stack at the current acquisition time, and estimate the impedance of each membrane electrode according to the assigned membrane electrode equivalent circuit; An impedance deviation determination module, used to determine the impedance deviation of each membrane electrode relative to the fuel cell stack according to the impedance of each membrane electrode and the impedance of the fuel cell stack; An impedance dispersion determination module, used to determine the impedance dispersion of all membrane electrodes relative to the fuel cell stack according to the impedance deviation of each membrane electrode relative to the fuel cell stack; The impedance difference evaluation module is used to evaluate the impedance difference between the fuel cell stack and the membrane electrode according to the impedance dispersion of all membrane electrodes relative to the fuel cell stack.

9. A vehicle, characterized in that: It includes the impedance difference evaluation device of the fuel cell stack and the membrane electrode as described in claim 8.

10. A control device, characterized in that: It includes a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction, when executed by the processor, implements the steps of the method for evaluating the impedance difference between a fuel cell stack and a membrane electrode as described in any one of claims 1 to 7.

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