Method, device, battery and vehicle for evaluating water content inside fuel cell stack

Abstract

The present invention relates to a method, device, battery and vehicle for evaluating the water content inside a fuel cell stack. The method obtains the operating parameters and impedance test values of the fuel cell stack, determines the current calibration value of the membrane water content based on the operating parameters, calculates the impedance calculation value of the fuel cell stack in combination with the operating parameters and the current calibration value of the membrane water content, jointly determines the initial membrane water content interval according to the impedance test value and the impedance calculation value, and performs iterative calculations on the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result; the present invention improves the accuracy of the evaluation of the water content inside the fuel cell stack and the efficiency of the evaluation of the water content inside the fuel cell stack, and can realize the quantitative evaluation of the water content of the proton exchange membrane of the fuel cell stack online, more intuitively reflecting the wet and dry state of the proton exchange membrane, and is applicable to various fuel cell systems.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and specifically to a method and device for evaluating the water content inside a fuel cell stack, as well as a battery and an automobile using the same. Background Art

[0002] A proton exchange membrane fuel cell is a power generation device that uses a polymer membrane capable of conducting protons as an electrolyte and directly converts the chemical energy existing in the fuel into electrical energy through an electrochemical reaction. It has characteristics such as high energy conversion efficiency, environmental friendliness, low noise, and high energy density, and has become an important development direction in the field of new energy vehicles.

[0003] The proton exchange membrane, as the core component of the membrane electrode in a fuel cell, its good proton conductivity is a necessary condition for the high output performance of the fuel cell. For a perfluorosulfonic acid membrane, the proton conductivity depends on the degree of hydration of the membrane. When the membrane is fully wetted, the battery has a high proton conductivity, small ohmic voltage drop loss, and high output voltage; conversely, when the membrane is in a dry state, the proton conductivity is low, the ohmic voltage drop loss is large, and the battery output voltage also decreases accordingly. In addition, if the battery is in a flooded or dry operating condition for a long time, the electrochemical performance and durability of the membrane electrode will be significantly reduced. Therefore, realizing the online evaluation function of the membrane water content during the actual application process of the fuel cell is crucial for its stable operation and extended service life.

[0004] For example, in a Chinese invention patent with the application number 202210016471.6 and the invention name "Method and System for Rapidly Controlling the Water Content Inside a Proton Exchange Membrane Fuel Cell Stack", this invention constructs a cathode unidirectional flow pressure drop model based on the cathode pressure drop value generated inside the proton exchange membrane fuel cell stack, and completes the parameter identification of the established pressure drop model and the coupling relationship between various water fault types and the pressure drop model through a hybrid algorithm of genetic and particle optimization, so as to judge the water state inside the proton exchange membrane.

[0005] The main technical problems of this patent document are as follows: (1) It mainly estimates the water state in the battery flow channel, and the phase state of water in the flow channel is liquid water, while the phase state of water in the proton exchange membrane is membrane water. There is a phase transformation process between the two. Therefore, simply estimating the water state in the battery flow channel cannot directly reflect the wet or dry state of the proton exchange membrane; (2) By analyzing the relevant information of the pressure drop and voltage drop changes in the flow channel to characterize the water state inside the battery, the gas pressure drop change may be affected by multiple factors such as the water content inside the battery, electrochemical characteristics, and various transport processes, and the voltage change is more a comprehensive manifestation of the influence of external operating conditions and internal physical property parameters on the battery output performance. Therefore, analyzing the relevant information of the pressure drop and voltage drop changes in the flow channel cannot accurately characterize the water state inside the battery, and it is even more difficult to reflect the wet or dry state of the membrane.

[0006] For another example, in the Chinese invention patent with the application number 202311210916.5 and the invention title "A Method, Device and Storage Medium for Detecting Flooding Faults in Fuel Cells", this invention discloses a method for detecting flooding faults in fuel cells. When the fuel cell stack is in a stable state, voltage information and voltage fluctuation information of each single cell are obtained to detect the flooding state of each single cell in the fuel cell.

[0007] The main technical problems of this patent document are as follows: By analyzing the voltage information and voltage fluctuation information of single cells to characterize the water state inside the battery, the change in gas pressure drop may be affected by multiple factors such as the water content inside the battery, electrochemical characteristics, and various transport processes. The voltage change is even more a comprehensive manifestation of the influence of external operating conditions and internal physical property parameters on the battery output performance. Therefore, analyzing the voltage information and voltage fluctuation information of single cells cannot accurately characterize the water state inside the battery, and it is even more difficult to reflect the wet or dry state of the membrane.

[0008] For another example, in the Chinese invention patent with the application number 202010000877.6 and the invention title "A Method for Diagnosing Flooding Faults in Proton Exchange Membrane Fuel Cells Based on Multi-Physical Fields", this invention establishes a three-dimensional geometric model of a proton exchange membrane fuel cell, establishes control equations, sets corresponding physical fields, thereby obtaining a fault diagnosis model, and finally determines the flooding fault state through the obtained cathode pressure drop curve, battery polarization curve, and cathode pressure drop change rate.

[0009] The main technical problems of this patent document are as follows: Due to the complexity of the three-dimensional geometric model of the proton exchange membrane fuel cell and the large amount of calculation, the time consumed for fault diagnosis is relatively long. Therefore, the real-time performance is poor and it is not suitable for scenarios with high real-time requirements such as fault detection.

[0010] Therefore, it is necessary to improve the method for evaluating the water content inside the fuel cell stack. Summary of the Invention

[0011] In view of the above-mentioned disadvantages of the prior art, the present application provides a method, device, battery and vehicle for evaluating the water content inside a fuel cell stack to solve the above technical problems.

[0012] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0013] According to one aspect of the embodiments of the present application, a method for evaluating the water content inside a fuel cell stack is provided. The method for evaluating the water content inside the fuel cell stack includes: obtaining the operating parameters and impedance test values of the fuel cell stack; determining the current membrane water content calibration value based on the operating parameters; calculating the impedance calculation value of the fuel cell stack in combination with the operating parameters and the current membrane water content calibration value; and jointly determining the initial membrane water content interval according to the impedance test value and the impedance calculation value, and performing iterative calculations on the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result.

[0014] In one embodiment of the present application, the process of jointly determining the initial membrane water content interval according to the impedance test value and the impedance calculation value includes: calculating the difference between the impedance test value and the impedance calculation value to obtain an impedance difference; comparing the impedance difference with a preset difference, and determining the initial membrane water content interval according to the comparison result.

[0015] In one embodiment of the present application, the process of comparing the impedance difference with a preset difference and determining the initial membrane water content interval according to the comparison result includes: if the impedance difference is equal to the preset difference, using the current membrane water content calibration value as the water content evaluation result; if the impedance difference is less than the preset difference, setting the upper limit value of the initial membrane water content interval to a first preset membrane water content value and setting the lower limit value of the initial membrane water content interval to the current membrane water content calibration value; if the impedance difference is greater than the preset difference, setting the upper limit value of the initial membrane water content interval to the current membrane water content calibration value and setting the lower limit value of the initial membrane water content interval to a second preset membrane water content value.

[0016] In one embodiment of the present application, the process of iteratively calculating the upper limit value and the lower limit value of the initial membrane water content range to obtain the water content evaluation result includes: calculating the upper limit value of the initial membrane water content range according to the upper limit value iteration formula to obtain the iterated upper limit value; and calculating the lower limit value of the initial membrane water content range according to the lower limit value iteration formula to obtain the iterated lower limit value; if the absolute difference between the iterated lower limit value and the iterated upper limit value is less than the preset absolute difference, then taking the average value of the iterated lower limit value and the iterated upper limit value as the water content evaluation result; if the absolute difference between the iterated lower limit value and the iterated upper limit value is greater than or equal to the preset absolute difference, then calculating the iterated upper limit value according to the upper limit value iteration formula to obtain the upper limit value after re-iteration, and calculating the iterated lower limit value according to the lower limit value iteration formula to obtain the lower limit value after re-iteration, until the absolute difference between the lower limit value after re-iteration and the upper limit value after re-iteration is less than the preset absolute difference; if the absolute difference between the lower limit value after re-iteration and the upper limit value after re-iteration is less than the preset absolute difference, then taking the average value of the lower limit value after re-iteration and the upper limit value after re-iteration as the water content evaluation result.

[0017] In one embodiment of the present application, the upper limit value iteration formula includes: b k = a k-1 + 0.618(b k-1 - a k-1 ), where b k represents the upper limit value obtained after k iterations of the upper limit value of the initial membrane water content range, a k-1 represents the lower limit value obtained after k - 1 iterations of the lower limit value of the initial membrane water content range, b k-1 represents the upper limit value obtained after k - 1 iterations of the upper limit value of the initial membrane water content range; the lower limit value iteration formula includes: a k = a k-1 + 0.382(b k-1 - a k-1 ), where a k represents the lower limit value obtained after k iterations of the lower limit value of the initial membrane water content range, a k-1 represents the lower limit value obtained after k - 1 iterations of the lower limit value of the initial membrane water content range, b k-1 represents the upper limit value obtained after k - 1 iterations of the upper limit value of the initial membrane water content range.

[0018] In an embodiment of the present application, if the operating parameters include the current temperature value, the calculation formula of the impedance calculation value of the fuel cell stack includes: Z cal = Ω m + Ω por , where Z cal represents the impedance calculation value of the fuel cell stack, and Ω m represents the specific internal resistance of the proton exchange membrane per proton surface, in Ω por represents the specific internal resistance of the porous layer per unit area; the calculation formula of the specific internal resistance of the proton exchange membrane per proton surface includes: where, Ω m represents the specific internal resistance of the proton exchange membrane per proton surface, δ m represents the thickness of the material layer containing the electrolyte firmware, represents the effective conductivity of the proton exchange membrane; the calculation formula of the effective conductivity of the proton exchange membrane includes: where, represents the effective conductivity of the proton exchange membrane, σ m represents the conductivity of the proton exchange membrane, l m represents the volume fraction of the perfluorosulfonic acid-based polymer in the catalyst layer in the total volume of the catalyst layer; the calculation formula of the conductivity of the proton exchange membrane includes: where, σ m represents the conductivity of the proton exchange membrane, λ0 represents the calibration value of the current membrane water content, and T represents the current temperature value; the calculation formula of the specific internal resistance of the porous layer per unit area includes: where, Ω por represents the specific internal resistance of the porous layer per unit area, δ s represents the thickness of the material layer of the porous medium firmware, represents the effective conductivity of the porous medium layer; the calculation formula of the effective conductivity of the porous medium layer includes: where, represents the effective conductivity of the porous medium layer, σ s represents the inherent electron conductivity, and ε represents the porosity of the material layer.

[0019] In an embodiment of the present application, if the operating parameters include current operating parameters and historical operating parameters, the process of determining the current membrane water content calibration value based on the operating parameters includes: obtaining the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters, where the historical operating parameters include the operating parameters of different historical operating condition points; selecting one historical operating condition point from different historical operating condition points as the first historical operating condition point; if the operating parameters of the first historical operating condition point are not successfully compared with the current operating parameters, then selecting another historical operating condition point from different historical operating condition points as the second historical operating condition point until the operating parameters of the second historical operating condition point are successfully compared with the operating parameters, and the first historical operating condition point is different from the second historical operating condition point; if the operating parameters of the first historical operating condition point are successfully compared with the current operating parameters, then using the historical membrane water content calibration value corresponding to the operating parameters of the first historical operating condition point as the current membrane water content calibration value; or, if the operating parameters of the second historical operating condition point are successfully compared with the current operating parameters, then using the historical membrane water content calibration value corresponding to the operating parameters of the second historical operating condition point as the current membrane water content calibration value.

[0020] In an embodiment of the present application, before obtaining the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters, the method for evaluating the water content inside the fuel cell stack includes: controlling the fuel cell stack to operate according to the operating parameters of different historical operating condition points on the polarization curve, and during the process of the fuel cell stack operating according to the operating parameters of each historical operating condition point on the polarization curve, collecting the impedance data of the fuel cell stack to obtain the impedance data corresponding to the operating parameters of different historical operating condition points; respectively calibrating the membrane water content based on the impedance data corresponding to the operating parameters of each historical operating condition point to obtain the historical membrane water content calibration values corresponding to the operating parameters of different historical operating condition points.

[0021] In an embodiment of the present application, input a preset injection current into the alternating current / frequency injection module preset in the boost / buck converter, and after the boost / buck converter receives the preset injection current, control the fuel cell stack to respond, collect the impedance test value of the fuel cell stack, and adjust the preset injection current based on the response current, where the preset injection current has a preset frequency range; input the adjusted preset injection current into the alternating current / frequency injection module, and after the boost / buck converter receives the adjusted preset injection current, control the fuel cell stack to respond, collect the impedance test value of the fuel cell stack again, and adjust the adjusted preset injection current based on the response current obtained again to realize real-time collection of the impedance test value of the fuel cell stack.

[0022] In an embodiment of the present application, the process of adjusting the preset injection current based on the response current includes: if the response current is greater than or equal to a preset current value, multiplying the response current by a first preset ratio, and using the obtained current value after multiplication as the preset injection current; if the response current is less than the preset current value, multiplying the response current by a second preset ratio, and using the obtained current value after multiplication as the preset injection current, where the second preset ratio is greater than the first preset ratio.

[0023] According to one aspect of the embodiments of the present application, there is provided a device for evaluating the water content inside a fuel cell stack. The device for evaluating the water content inside a fuel cell stack includes: a parameter acquisition module, configured to acquire the operating parameters and impedance test values of the fuel cell stack; a calibration value determination module, configured to determine the current membrane water content calibration value based on the operating parameters; an impedance value calculation module, configured to calculate the impedance calculation value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value; a water content evaluation module, configured to jointly determine the initial membrane water content range according to the impedance test value and the impedance calculation value, and perform iterative calculations on the upper limit value and the lower limit value of the initial membrane water content range to obtain the water content evaluation result.

[0024] According to one aspect of the embodiments of the present application, there is provided a fuel cell, and the water content of the fuel cell is evaluated using the method for evaluating the water content inside a fuel cell stack as described above.

[0025] According to one aspect of the embodiments of the present application, there is provided an automobile, and the automobile includes the device for evaluating the water content inside a fuel cell stack as described above or the fuel cell as described above.

[0026] Advantages of the present invention: By acquiring the operating parameters and impedance test values of the fuel cell stack, determining the current membrane water content calibration value based on the operating parameters, calculating the impedance calculation value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value, jointly determining the initial membrane water content range according to the impedance test value and the impedance calculation value, and performing iterative calculations on the upper limit value and the lower limit value of the initial membrane water content range to obtain the water content evaluation result. Through the above process, the initial membrane water content range is jointly determined according to the impedance test value and the impedance calculation value, and iterative calculations are performed on the upper limit value and the lower limit value of the initial membrane water content range, which improves the accuracy and efficiency of the evaluation of the water content inside the fuel cell stack, and enables on-line quantitative evaluation of the water content of the proton exchange membrane of the fuel cell stack, more intuitively reflecting the dry-wet state of the proton exchange membrane, and being applicable to various fuel cell systems.

[0027] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit this application. Brief Description of the Drawings

[0028] The drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application. Obviously, the drawings in the following description are only some embodiments of this application, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. In the drawings:

[0029] Figure 1 is a schematic diagram of an exemplary system architecture shown in an exemplary embodiment of this application;

[0030] Figure 2 is a flowchart of a method for evaluating the water content inside a fuel cell stack shown in an exemplary embodiment of this application;

[0031] Figure 3 is a flowchart of a method for evaluating the water content inside a fuel cell stack shown in another exemplary embodiment of this application;

[0032] Figure 4 is a schematic diagram of the structure of a fuel cell impedance test system shown in an exemplary embodiment of this application;

[0033] Figure 5 is a flowchart of calculating the impedance calculated value of a fuel cell stack shown in an exemplary embodiment of this application;

[0034] Figure 6 is a flowchart of collecting the impedance test value of a fuel cell stack shown in an exemplary embodiment of this application;

[0035] Figure 7 is a flowchart of iteratively calculating the upper limit value and the lower limit value of an initial membrane water content interval shown in an exemplary embodiment of this application;

[0036] Figure 8 is a real-time change graph of the impedance calculated value obtained based on the current membrane water content calibration value and the impedance test value collected by hardware during the operation of a fuel cell stack shown in an exemplary embodiment of this application;

[0037] Figure 9 is a real-time change graph of the evaluation result of the proton exchange membrane water content of a fuel cell stack obtained based on iterative calculation shown in an exemplary embodiment of this application;

[0038] Figure 10It is a real-time change graph of the impedance calculation value calculated based on the evaluation result of the water content of the fuel cell electric propulsion proton exchange membrane after obtaining the evaluation result of the water content of the fuel cell electric propulsion proton exchange membrane through iterative calculation and the impedance test value collected by the hardware;

[0039] Figure 11 It is a real-time change graph of the error between the impedance calculation value calculated based on the evaluation result of the water content of the fuel cell electric propulsion proton exchange membrane after obtaining the evaluation result of the water content of the fuel cell electric propulsion proton exchange membrane through iterative calculation and the impedance test value collected by the hardware;

[0040] Figure 12 It is a block diagram of a device for evaluating the water content inside a fuel cell stack shown in an exemplary embodiment of the present application;

[0041] Figure 13 It shows a schematic structural diagram of a computer system of an electronic device suitable for implementing the embodiments of the present application. Detailed implementation manners

[0042] Figure 1 It is a schematic diagram of an exemplary system architecture shown in an exemplary embodiment of the present application.

[0043] Referring to Figure 1 As shown, the system architecture may include a collection device 101 and a controller 102. Related technicians can use the controller 102 to determine the current membrane water content calibration value based on the operating parameters, calculate the impedance calculation value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value, jointly determine the initial membrane water content interval according to the impedance test value and the impedance calculation value, and perform iterative calculation on the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result. The collection device 101 is used to collect the operating parameters and impedance test values of the fuel cell stack. In this embodiment, the collection device 101 uses sensors, etc. to collect the operating parameters and impedance test values of the fuel cell stack and provide them to the controller 102 for processing.

[0044] The present application jointly determines the initial membrane water content interval according to the impedance test value and the impedance calculation value, and performs iterative calculation on the upper limit value and the lower limit value of the initial membrane water content interval, improving the accuracy of the evaluation of the water content inside the fuel cell stack and the efficiency of the evaluation of the water content inside the fuel cell stack, and being able to realize the quantitative evaluation of the water content of the proton exchange membrane of the fuel cell stack online, more intuitively reflecting the dry and wet state of the proton exchange membrane, and being applicable to various fuel cell systems.

[0045] It should be noted that the method for evaluating the water content inside the fuel cell stack provided in the embodiments of the present application is generally executed by the controller 102. Correspondingly, the device for evaluating the water content inside the fuel cell stack is generally disposed in the controller 102.

[0046] The implementation details of the technical solutions in the embodiments of the present application are elaborated in detail as follows:

[0047] Figure 2 is a flowchart of the method for evaluating the water content inside the fuel cell stack shown in an exemplary embodiment of the present application. The method for evaluating the water content inside the fuel cell stack can be executed by a computing device, and the computing device can be Figure 1 the controller 102 shown in Figure 2 As shown, the method for evaluating the water content inside the fuel cell stack at least includes steps S210 to S240, which are introduced in detail as follows:

[0048] In step S210, the operating parameters and impedance test values of the fuel cell stack are acquired.

[0049] In an embodiment of the present application, the operating parameters include current operating parameters and operating parameters at different historical operating conditions. The current operating parameters include the current current value and the current temperature value, etc. The operating parameters at different historical operating conditions include the current values and temperature values at different historical operating conditions, etc.

[0050] In this embodiment, the impedance test value of the fuel cell stack can be collected by an Electrochemical Impedance Spectroscopy (EIS) device, or can be collected by a Fuel cell control unit (FCCU) device, etc. Here, no specific limitation is made.

[0051] In step S220, based on the operating parameters, the current membrane water content calibration value is determined.

[0052] In this embodiment, if the operating parameters include the current operating parameters and the historical operating parameters, the process of determining the current membrane water content calibration value based on the operating parameters includes: (1) obtaining the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters, where the historical operating parameters include the operating parameters of different historical operating condition points; (2) selecting one historical operating condition point from different historical operating condition points as the first historical operating condition point; (3) if the operating parameters of the first historical operating condition point are not successfully compared with the current operating parameters, then selecting another historical operating condition point from different historical operating condition points as the second historical operating condition point until the operating parameters of the second historical operating condition point are successfully compared with the operating parameters; (3) if the operating parameters of the first historical operating condition point are successfully compared with the current operating parameters, then using the historical membrane water content calibration value corresponding to the operating parameters of the first historical operating condition point as the current membrane water content calibration value; or, if the operating parameters of the second historical operating condition point are successfully compared with the current operating parameters, then using the historical membrane water content calibration value corresponding to the operating parameters of the second historical operating condition point as the current membrane water content calibration value.

[0053] In step S230, in combination with the operating parameters and the current membrane water content calibration value, the impedance calculation value of the fuel cell stack is calculated.

[0054] In this embodiment, after obtaining the current membrane water content calibration value, the operating parameters and the current membrane water content calibration value are input into the impedance mechanism model to calculate the impedance calculation value of the fuel cell stack. Calculating the impedance calculation value of the fuel cell stack through the impedance mechanism model improves the accuracy of the impedance calculation value of the fuel cell stack.

[0055] In this embodiment, if the operating parameters include the current temperature value, in the impedance mechanism model, the calculation formula for the impedance calculation value of the fuel cell stack includes:

[0056] Z cal =Ω m +Ω por Equation (1)

[0057] Where, Z cal represents the impedance calculation value of the fuel cell stack, Ω m represents the proton surface specific resistance of the proton exchange membrane, Ω por represents the porous layer specific resistance;

[0058] The calculation formula for the proton surface specific resistance of the proton exchange membrane includes:

[0059]

[0060] Where, Ω m represents the proton surface specific resistance of the proton exchange membrane, δ m represents the thickness of the material layer containing the electrolyte firmware, Represents the effective conductivity of the proton exchange membrane;

[0061] The calculation formula for the effective conductivity of the proton exchange membrane includes:

[0062]

[0063] Among them, Represents the effective conductivity of the proton exchange membrane, σ m Represents the conductivity of the proton exchange membrane, l m Represents the volume fraction of the perfluorosulfonic acid-based polymer in the catalyst layer in the total volume of the catalyst layer;

[0064] The calculation formula for the conductivity of the proton exchange membrane includes:

[0065]

[0066] Among them, σ m Represents the conductivity of the proton exchange membrane, λ0 represents the current membrane water content calibration value, and T represents the current temperature value;

[0067] The calculation formula for the specific internal resistance of the porous layer includes:

[0068]

[0069] Among them, Ω por Represents the specific internal resistance of the porous layer, δ s Represents the material layer thickness of the porous medium firmware, Represents the effective conductivity of the porous medium layer;

[0070] The calculation formula for the effective conductivity of the porous medium layer includes:

[0071]

[0072] Among them, Represents the effective conductivity of the porous medium layer, σ s Represents the intrinsic electron conductivity, and ε represents the porosity of the material layer.

[0073] In step S240, based on the impedance test value and the impedance calculation value, jointly determine the initial membrane water content interval, and perform iterative calculations on the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result.

[0074] In this embodiment, the algorithm for performing iterative calculations on the upper limit value and the lower limit value of the initial membrane water content interval can adopt the precise one-dimensional line search monotonic descent algorithm based on the golden section, or other iterative algorithms. Here, no specific limitation is made.

[0075] In this embodiment, the impedance test values collected are combined with the impedance calculation values obtained from the impedance mechanism model to jointly determine the initial membrane water content range, and iterative calculations are performed on the upper and lower limit values of the initial membrane water content range, improving the accuracy of the water content assessment inside the fuel cell stack and the efficiency of the water content assessment inside the fuel cell stack, and enabling quantitative assessment of the water content of the proton exchange membrane of the fuel cell stack online, more intuitively reflecting the wet and dry states of the proton exchange membrane, and being applicable to various fuel cell systems.

[0076] In an embodiment of the present application, the process of jointly determining the initial membrane water content range according to the impedance test values and the impedance calculation values includes:

[0077] Calculate the difference between the impedance test value and the impedance calculation value to obtain the impedance difference.

[0078] In this embodiment, the calculation formula of the impedance difference is as follows:

[0079] φ = Z mea -Z cal Equation (7)

[0080] Wherein, φ represents the impedance difference, Z mea represents the impedance test value, and Z cal represents the impedance calculation value.

[0081] Compare the impedance difference with a preset difference, and determine the initial membrane water content range according to the comparison result.

[0082] In this embodiment, the process of comparing the impedance difference with the preset difference and determining the initial membrane water content range according to the comparison result includes: if the impedance difference is equal to the preset difference, use the current membrane water content calibration value as the water content assessment result; if the impedance difference is less than the preset difference, set the upper limit value of the initial membrane water content range to the first preset membrane water content value, and set the lower limit value of the initial membrane water content range to the current membrane water content calibration value; if the impedance difference is greater than the preset difference, set the upper limit value of the initial membrane water content range to the current membrane water content calibration value, and set the lower limit value of the initial membrane water content range to the second preset membrane water content value.

[0083] In this embodiment, when the impedance difference is less than the preset difference, through iterative calculations on the first preset membrane water content value and the current membrane water content calibration value, the water content assessment result shrinks between the first preset membrane water content value and the current membrane water content calibration value; when the impedance difference is greater than the preset difference, through iterative calculations on the current membrane water content calibration value and the second preset membrane water content value, the water content assessment result shrinks between the current membrane water content calibration value and the second preset membrane water content value.

[0084] In an embodiment of the present application, the process of comparing the impedance difference with a preset difference and determining the initial membrane water content range according to the comparison result includes:

[0085] If the impedance difference is equal to the preset difference, the current membrane water content calibration value is used as the water content evaluation result.

[0086] In this embodiment, the preset difference can be zero or other values, and no specific limitation is made here.

[0087] If the impedance difference is less than the preset difference, the upper limit value of the initial membrane water content range is set to the first preset membrane water content value, and the lower limit value of the initial membrane water content range is set to the current membrane water content calibration value.

[0088] In this embodiment, the first preset membrane water content value is greater than the current membrane water content calibration value, and the first preset membrane water content value can be set according to actual needs, which will not be elaborated here.

[0089] If the impedance difference is greater than the preset difference, the upper limit value of the initial membrane water content range is set to the current membrane water content calibration value, and the lower limit value of the initial membrane water content range is set to the second preset membrane water content value.

[0090] In this embodiment, the second preset membrane water content value is less than the current membrane water content calibration value, and the second preset membrane water content value can be set according to the actual situation, which will not be elaborated here.

[0091] In an embodiment of the present application, the process of performing iterative calculations on the upper limit value and the lower limit value of the initial membrane water content range to obtain the water content evaluation result includes:

[0092] According to the upper limit value iteration formula, the upper limit value of the initial membrane water content range is calculated to obtain the iterated upper limit value; and according to the lower limit value iteration formula, the lower limit value of the initial membrane water content range is calculated to obtain the iterated lower limit value.

[0093] In this embodiment, the upper limit value iteration formula includes:

[0094] b k = a k-1 + 0.618(b k-1 - a k-1 ) Equation (8)

[0095] Wherein, b k represents the upper limit value obtained after k iterations of the upper limit value of the initial membrane water content range, and a k-1 represents the lower limit value obtained after k - 1 iterations of the lower limit value of the initial membrane water content range, b k-1It represents the upper limit value obtained after (k - 1) iterations of the upper limit value of the initial membrane water content range.

[0096] The lower limit value iteration formula includes:

[0097] a k = a k-1 + 0.382(b k-1 - a k-1 ) Equation (9)

[0098] Among them, a k represents the lower limit value obtained after k iterations of the lower limit value of the initial membrane water content range, and a k-1 represents the lower limit value obtained after (k - 1) iterations of the lower limit value of the initial membrane water content range, and b k-1 represents the upper limit value obtained after (k - 1) iterations of the upper limit value of the initial membrane water content range.

[0099] In this embodiment, when k = 1, a0 represents the lower limit value of the initial membrane water content range, and b0 represents the upper limit value of the initial membrane water content range.

[0100] If the absolute difference between the iterated lower limit value and the iterated upper limit value is less than the preset absolute difference, then the average value of the iterated lower limit value and the iterated upper limit value is used as the water content evaluation result.

[0101] If the absolute difference between the iterated lower limit value and the iterated upper limit value is greater than or equal to the preset absolute difference, then according to the upper limit value iteration formula, the iterated upper limit value is calculated to obtain the re-iterated upper limit value, and according to the lower limit value iteration formula, the iterated lower limit value is calculated to obtain the re-iterated lower limit value, until the absolute difference between the re-iterated lower limit value and the re-iterated upper limit value is less than the preset absolute difference.

[0102] In this embodiment, the preset absolute difference can be set to 0.5, or it can be set to other values, and specific limitations are not provided here.

[0103] In this embodiment, the calculation formula for the absolute difference is as follows:

[0104] c = |a k - b k | Equation (10)

[0105] Among them, c represents the absolute difference, a k represents the lower limit value obtained after k iterations of the lower limit value of the initial membrane water content range, and b k represents the upper limit value obtained after k iterations of the upper limit value of the initial membrane water content range.

[0106] If the absolute difference between the lower limit value after the next iteration and the upper limit value after the next iteration is less than the preset absolute difference, the average value of the lower limit value after the next iteration and the upper limit value after the next iteration is taken as the water content evaluation result.

[0107] In this embodiment, the calculation formula of the water content evaluation result is as follows:

[0108]

[0109] where λ represents the water quantity evaluation result, and a k represents the lower limit value obtained after k iterations of the lower limit value of the initial membrane water content interval, and b k represents the upper limit value obtained after k iterations of the upper limit value of the initial membrane water content interval.

[0110] In an embodiment of the present application, if the operating parameters include the current operating parameters and the historical operating parameters, the process of determining the current membrane water content calibration value based on the operating parameters includes:

[0111] Obtain the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters.

[0112] In this embodiment, the historical operating parameters include the operating parameters of different historical operating condition points, and the operating parameters of different historical operating condition points include temperature values and current values of different historical operating condition points, etc.

[0113] Select a historical operating condition point from different historical operating condition points as the first historical operating condition point.

[0114] In this embodiment, the method of selecting a historical operating condition point from different historical operating condition points can be a random selection method, or different historical operating condition points can be sorted in chronological order, and the historical operating condition points can be selected in chronological order.

[0115] If the operating parameters of the first historical operating condition point are not successfully compared with the current operating parameters, then select another historical operating condition point from different historical operating condition points as the second historical operating condition point until the operating parameters of the second historical operating condition point are successfully compared with the operating parameters.

[0116] In this embodiment, the first historical operating condition point is different from the second historical operating condition point, and the current operating parameters include the current temperature value and the current current value, etc.

[0117] In this embodiment, the process of comparing the operating parameters of the first historical operating condition point with the current operating parameters includes: if the current temperature value is not successfully compared with the temperature value of the first historical operating condition point, and / or, the current current value is not successfully compared with the current value of the first historical operating condition point, it is determined that the operating parameters of the first historical operating condition point are not successfully compared with the current operating parameters.

[0118] If the operating parameters of the first historical operating point are successfully compared with the current operating parameters, the calibrated value of the historical membrane water content corresponding to the operating parameters of the first historical operating point is used as the current calibrated value of the membrane water content; or, if the operating parameters of the second historical operating point are successfully compared with the current operating parameters, the calibrated value of the historical membrane water content corresponding to the operating parameters of the second historical operating point is used as the current calibrated value of the membrane water content.

[0119] In this embodiment, the process of comparing the operating parameters of the first historical operating point with the current operating parameters includes: if the current temperature value is successfully compared with the temperature value of the first historical operating point, and the current current value is successfully compared with the current value of the first historical operating point, it is determined that the operating parameters of the first historical operating point are successfully compared with the current operating parameters.

[0120] In an embodiment of the present application, before obtaining the calibrated value of the historical membrane water content of the fuel cell stack under historical operating parameters, the method for evaluating the water content inside the fuel cell stack includes:

[0121] Controlling the fuel cell stack to operate according to the operating parameters of different historical operating points on the polarization curve, and during the process of the fuel cell stack operating according to the operating parameters of each historical operating point on the polarization curve, collecting the impedance data of the fuel cell stack to obtain the impedance data corresponding to the operating parameters of different historical operating points. The impedance data of the fuel cell stack is collected in real time through an EIS device or an FCCU device, etc.

[0122] Based on the impedance data corresponding to the operating parameters of each historical operating point respectively, calibrate the membrane water content to obtain the calibrated values of the historical membrane water content corresponding to the operating parameters of different historical operating points.

[0123] In this embodiment, the method of calibrating the membrane water content based on the impedance data corresponding to the operating parameters of each historical operating point respectively to obtain the calibrated values of the historical membrane water content corresponding to the operating parameters of different historical operating points can be implemented by referring to the calibration methods in relevant technical literature, and will not be specifically limited here.

[0124] In this embodiment, the calibrated values of the historical membrane water content corresponding to the operating parameters of different historical operating points can be stored or displayed in matrix form. The size of the matrix is N*N, where N is the number of historical operating points, or can be stored in other ways, and will not be specifically limited here.

[0125] In an embodiment of the present application, before obtaining the impedance test value of the fuel cell stack, the method for evaluating the water content inside the fuel cell stack includes:

[0126] Input a preset injection current into the alternating current / frequency injection module pre-set in the boost / buck converter. After the boost / buck converter receives the preset injection current, control the fuel cell stack to respond, collect the impedance test value of the fuel cell stack, and adjust the preset injection current based on the response current. The preset injection current has a preset frequency range.

[0127] In this embodiment, taking the acquisition device of the impedance test value of the fuel cell stack as the FCCU device as an example, the alternating current / frequency injection module is pre-set in the boost / buck converter. The boost / buck converter is connected in parallel with the fuel cell. The FCCU device obtains the impedance test value of the fuel cell stack by collecting the output current and output voltage of the fuel cell stack in real time and calculating based on the output current and output voltage of the fuel cell stack.

[0128] In this embodiment, the impedance test value of the fuel cell stack can be collected by an EIS device or an FCCU device, etc. The preset frequency range can be 500 Hz to 1000 Hz, or it can be other frequency ranges. Here, no specific limitation is made.

[0129] Input the adjusted preset injection current into the alternating current / frequency injection module. After the boost / buck converter receives the adjusted preset injection current, control the fuel cell stack to respond, collect the impedance test value of the fuel cell stack again, and adjust the adjusted preset injection current based on the response current obtained again to achieve real-time collection of the impedance test value of the fuel cell stack.

[0130] In this embodiment, the process of collecting the impedance test value of the fuel cell stack again includes: collecting the output current and output voltage after the fuel cell stack responds again, and calculating based on the output current and output voltage after the response again to obtain the impedance test value of the fuel cell stack again.

[0131] In an embodiment of the present application, the process of adjusting the preset injection current based on the response current includes:

[0132] If the response current is greater than or equal to the preset current value, multiply the response current by a first preset ratio, and use the current value obtained after multiplication as the preset injection current.

[0133] In this embodiment, the preset current value can be 200 A, or it can be other current values. Here, no specific limitation is made. The first preset ratio can be 2%, or it can be other values. Here, no specific limitation is made.

[0134] If the response current is less than the preset current value, multiply the response current by a second preset ratio, and use the current value obtained after multiplication as the preset injection current.

[0135] In this embodiment, the second preset ratio is greater than the first preset ratio. The second preset ratio can be 5% or other values, and specific limitations are not provided here.

[0136] In this embodiment, the response current is compared with the preset current value. According to the comparison result, the response current is multiplied by the second preset ratio or the response current is multiplied by the first preset ratio, so as to adjust the preset injection current.

[0137] Figure 3 is a flowchart of a method for evaluating the water content inside a fuel cell stack shown in another exemplary embodiment of the present application. As Figure 3 shown, the method for evaluating the water content inside the fuel cell stack includes: (1) An impedance steady-state calculation unit uses an impedance mechanism model established based on the internal electrochemical mechanism of the fuel cell, takes parameters such as the current membrane water content calibration value, the current current value, and the current temperature value as inputs to the impedance mechanism model, and calculates the impedance calculation value of the fuel cell stack; (2) An impedance online acquisition unit uses an EIS device or an FCCU device to collect the impedance test value of the fuel cell stack in real time; (3) A membrane water content iterative solution unit iteratively calculates the upper and lower limit values of the initial membrane water content interval based on the difference between the impedance test value of the fuel cell stack and the impedance calculation value of the fuel cell stack to obtain the water content evaluation result.

[0138] In this embodiment, the impedance mechanism model includes a battery ohmic voltage drop loss model, and the formula of the battery ohmic voltage drop loss model is as follows:

[0139] V cell =V Nernst -V act -V ohm -V conc Equation (12)

[0140] Among them, V cell represents the battery output voltage, V Nernst represents the Nernst voltage, V act represents the activation voltage, V ohm represents the ohmic voltage, V conc represents the concentration difference voltage.

[0141] In this embodiment, the calculation formula of the ohmic voltage is as follows:

[0142] V ohm =V ohm,m +V ohm,por =Ω m *I+Ω por *I Equation (13)

[0143] Among them, V ohmRepresents the Ohmic voltage, V ohm,m Represents the voltage loss of the proton exchange membrane, V ohm,por Represents the voltage loss caused by the porous layer hindering electron transfer, Ω m Represents the specific surface resistance of the proton exchange membrane to protons, I represents the current value, Ω por Represents the specific surface resistance of the porous layer.

[0144] In this embodiment, the specific surface resistance of the proton exchange membrane to protons Ω m The product of and the current value I is the voltage loss V of the proton exchange membrane ohm,m , the specific surface resistance of the porous layer Ω por The product of and the current value I is the voltage loss V caused by the porous layer hindering electron transfer ohm,por , and through the derivation of formula (12) and formula (13), it can be known that the impedance calculated value Z of the fuel cell stack cal Is the specific surface resistance of the proton exchange membrane to protons Ω m And the specific surface resistance of the porous layer Ω por The sum of, as shown in formula (1), and based on formula (1) - formula (6), as well as the current membrane water content calibration value and the current temperature value, the impedance calculated value of the fuel cell stack is calculated.

[0145] In this embodiment, the upper and lower limit values of the initial membrane water content interval are iteratively recursively solved using the precise one-dimensional line search monotonic descent algorithm based on the golden section to obtain the water content evaluation result.

[0146] Figure 4 Is a schematic structural diagram of the fuel cell impedance test system shown in an exemplary embodiment of the present application, as Figure 4 Shown, the fuel cell impedance test system includes: an alternating current / frequency injection module, a boost / buck converter, a fuel cell, an FCCU device or an EIS device, etc. The alternating current / frequency injection module is preset in the boost / buck converter, and the boost / buck converter is connected in parallel with the fuel cell.

[0147] In this embodiment, a preset injection current is input into the alternating current / frequency injection module, and after the boost / buck converter controls the fuel cell stack to respond, the output current and output voltage of the fuel cell stack are collected in real time through the FCCU device or the EIS device, and the impedance test value of the fuel cell stack is calculated in real time based on the output current and output voltage of the fuel cell stack.

[0148] Figure 5 Is a flowchart for calculating the impedance calculated value of the fuel cell stack shown in an exemplary embodiment of the present application, as Figure 5As shown, the process of calculating the impedance calculation value of the fuel cell stack includes: (1) obtaining the current calibrated value of the membrane water content, the current temperature value, and the current current value; (2) inputting the current calibrated value of the membrane water content, the current temperature value, and the current current value into the impedance mechanism model; (3) obtaining the impedance calculation value of the fuel cell stack through calculation.

[0149] In this embodiment, the process of determining the current calibrated value of the membrane water content includes: (1) controlling the fuel cell stack to operate according to each current and temperature operating point on the polarization curve, and during the operation, the impedance data obtained by real-time collection through an impedance collection device (such as an EIS device or an FCCU device, etc.); (3) calibrating the membrane water content through the impedance data obtained by real-time collection to obtain the historical calibrated value of the membrane water content at each current and temperature operating point; (4) comparing the current temperature value and the current current value with the temperature value and current value of each current and temperature operating point respectively; (5) if the current temperature value is successfully compared with the temperature value of a certain operating point, and the current current value is successfully compared with the current value of this operating point, then use the historical calibrated value of the membrane water content corresponding to this operating point as the current calibrated value of the membrane water content.

[0150] Figure 6 is a flowchart showing the acquisition of the impedance test value of the fuel cell stack shown in an exemplary embodiment of the present application, as Figure 6 As shown, the process of acquiring the impedance test value of the fuel cell stack includes: (1) inputting a preset injection current into the alternating current / frequency injection module, and after the boost / buck converter controls the fuel cell stack to respond, adjusting the preset injection current based on the response current; (2) inputting the response current into the EIS device; (3) acquiring the impedance test value of the fuel cell stack.

[0151] In this embodiment, the response current includes the current after the preset injection current is first input into the alternating current / frequency injection module and the fuel cell stack responds under the control of the boost / buck converter, and the response current after the preset injection current is adjusted multiple times and then input into the alternating current / frequency injection module multiple times and the fuel cell stack responds multiple times under the control of the boost / buck converter.

[0152] Figure 7 is a flowchart showing the iterative calculation of the upper limit value and the lower limit value of the initial membrane water content interval shown in an exemplary embodiment of the present application, as Figure 7As shown in the figure, the process of iteratively calculating the upper limit value and the lower limit value of the initial membrane water content range includes: (1) performing iterative calculations on the lower limit value of the initial membrane water content range and the upper limit value of the initial membrane water content range based on the precise one-dimensional line search monotonic descent algorithm of the golden section; (2) determining whether the absolute difference between the lower limit value after the iterative calculation and the upper limit value after the iteration is less than the preset absolute difference; (3) if the absolute difference between the lower limit value after the iterative calculation and the upper limit value after the iteration is greater than or equal to the preset absolute difference, continue to perform iterative calculations on the lower limit value after the iterative calculation and the upper limit value after the iteration based on the precise one-dimensional line search monotonic descent algorithm of the golden section until the absolute difference between the lower limit value after the iterative calculation and the upper limit value after the iteration is less than the preset absolute difference; if the absolute difference between the lower limit value after the iteration and the upper limit value after the iteration is less than the preset absolute difference, take the average value of the lower limit value after the iteration and the upper limit value after the iteration as the water content evaluation result.

[0153] Figure 8 FIG. is a real-time change diagram of the impedance calculation value calculated based on the current membrane water content calibration value and the impedance test value collected by the hardware during the operation of the fuel cell stack shown in an exemplary embodiment of the present application. As Figure 8 shown, the abscissa represents time, the unit is second, and the ordinate is the impedance calculation value Z calculated based on the current membrane water content calibration value cal0 and the impedance test value Z collected by the hardware mea . At the same time, the error between the impedance calculation value Z cal0 and the impedance test value Z mea is relatively large, and the degree of coincidence between the impedance calculation value Z cal0 and the impedance test value Z mea is relatively low.

[0154] Figure 9 FIG. is a real-time change diagram of the evaluation result of the proton exchange membrane water content of the fuel cell stack obtained based on iterative calculation shown in an exemplary embodiment of the present application. As Figure 9 shown, the abscissa represents time, the unit is second, and the ordinate is the evaluation result of the proton exchange membrane water content of the fuel cell stack obtained by iterative calculation. In the time period of 0 - 300 seconds, the evaluation result of the proton exchange membrane water content of the fuel cell stack changes within [12, 23.5].

[0155] Figure 10 FIG. is a real-time change diagram of the impedance calculation value calculated based on the evaluation result of the proton exchange membrane water content of the fuel cell stack and the impedance test value collected by the hardware after obtaining the evaluation result of the proton exchange membrane water content of the fuel cell stack based on iterative calculation shown in an exemplary embodiment of the present application. As Figure 10As shown, the abscissa represents time in seconds, and the ordinate is the calculated impedance value Z obtained by calculating the evaluation result of the water content of the proton exchange membrane based on the fuel cell electric propulsion cal1 and the impedance test value Z collected by the hardware mea . At the same time, the calculated impedance value Z cal1 and the impedance test value Z mea have a small error. Thus, it can be seen that the calculated impedance value Z cal1 and the impedance test value Z mea have a good degree of agreement

[0156] Figure 11 is a real-time change graph of the error between the calculated impedance value obtained based on the evaluation result of the water content of the proton exchange membrane of the fuel cell electric propulsion obtained by iterative calculation and the impedance test value collected by the hardware shown in an exemplary embodiment of the present application. In Figure 11 , the abscissa represents time in seconds, and the ordinate is the error between the calculated impedance value obtained based on the evaluation result of the water content of the proton exchange membrane of the fuel cell electric propulsion and the impedance test value collected by the hardware. At the same time, the calculated impedance value Z cal1 and the impedance test value Z mea are basically within the preset range, and within the time period of 0 - 300 seconds, the proportion of the number of errors within the preset range in the total number of errors is more than 90%. Thus, it can be seen that the calculated impedance value Z cal1 and the impedance test value Z mea have a good degree of agreement

[0157] The present application obtains the operating parameters and impedance test values of the fuel cell stack, determines the current membrane water content calibration value based on the operating parameters, calculates the calculated impedance value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value, jointly determines the initial membrane water content interval according to the impedance test value and the calculated impedance value, and performs iterative calculation on the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result, which can realize the online quantitative evaluation of the water content of the proton exchange membrane, more intuitively reflect the dry and wet state of the proton exchange membrane, and adopt the method of collecting the impedance test value by using an EIS device or an FCCU device and combining the mechanism model simulation to calculate the calculated impedance value, effectively improving the accuracy of the water content evaluation result of the proton exchange membrane and the solution rate of the water content evaluation result of the proton exchange membrane, and can be applicable to a variety of fuel cell systems, having the characteristics of a wide application range

[0158] The following introduces the device embodiments of the present application, which can be used to execute the method for evaluating the water content inside the fuel cell stack in the above embodiments of the present application. For the details not disclosed in the device embodiments of the present application, please refer to the embodiments of the method for evaluating the water content inside the fuel cell stack above in the present application.

[0159] Figure 12 It is a block diagram of a device for evaluating the water content inside a fuel cell stack shown in an exemplary embodiment of the present application. This device can be applied to Figure 1 the implementation environment shown, and is specifically configured in the controller 102. This device can also be applicable to other exemplary implementation environments and is specifically configured in other devices. The implementation environment applicable to this device is not limited in this embodiment.

[0160] As Figure 12 shown, this exemplary device for evaluating the water content inside a fuel cell stack includes:

[0161] The parameter acquisition module 1201 is used to acquire the operating parameters and impedance test values of the fuel cell stack.

[0162] The calibration value determination module 1202 is used to determine the current membrane water content calibration value based on the operating parameters.

[0163] The impedance value calculation module 1203 is used to calculate the impedance calculation value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value.

[0164] The water content evaluation module 1204 is used to jointly determine the initial membrane water content interval according to the impedance test value and the impedance calculation value, and perform iterative calculations on the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result.

[0165] In an embodiment of the present application, the operating parameters include the current operating parameters and the operating parameters at different historical operating conditions. The current operating parameters include the current current value and the current temperature value, etc. The operating parameters at different historical operating conditions include the current values and temperature values at different historical operating conditions, etc.

[0166] In this embodiment, the impedance test value of the fuel cell stack can be collected by an Electrochemical Impedance Spectroscopy (EIS) device, or can be collected by devices such as a Fuel cell control unit (FCCU). Here, no specific limitation is made.

[0167] In this embodiment, if the operating parameters include the current operating parameters and historical operating parameters, the process of determining the current membrane water content calibration value based on the operating parameters includes: (1) obtaining the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters, where the historical operating parameters include the operating parameters at different historical operating condition points; (2) selecting one historical operating condition point from different historical operating condition points as the first historical operating condition point; (3) if the operating parameters of the first historical operating condition point are not successfully compared with the current operating parameters, then selecting another historical operating condition point from different historical operating condition points as the second historical operating condition point until the operating parameters of the second historical operating condition point are successfully compared with the operating parameters; (3) if the operating parameters of the first historical operating condition point are successfully compared with the current operating parameters, then using the historical membrane water content calibration value corresponding to the operating parameters of the first historical operating condition point as the current membrane water content calibration value; or, if the operating parameters of the second historical operating condition point are successfully compared with the current operating parameters, then using the historical membrane water content calibration value corresponding to the operating parameters of the second historical operating condition point as the current membrane water content calibration value.

[0168] In this embodiment, after obtaining the current membrane water content calibration value, the operating parameters and the current membrane water content calibration value are input into the impedance mechanism model to calculate the impedance calculation value of the fuel cell stack. By calculating the impedance calculation value of the fuel cell stack through the impedance mechanism model, the accuracy of the impedance calculation value of the fuel cell stack is improved.

[0169] In this embodiment, if the operating parameters include the current temperature value, in the impedance mechanism model, the calculation formula for the impedance calculation value of the fuel cell stack is shown in Equation (1), the calculation formula for the specific resistance per proton area of the proton exchange membrane is shown in Equation (2), the calculation formula for the effective conductivity of the proton exchange membrane is shown in Equation (3), the calculation formula for the conductivity of the proton exchange membrane is shown in Equation (4), the calculation formula for the specific resistance per porous layer area is shown in Equation (5), and the calculation formula for the effective conductivity of the porous medium layer is shown in Equation (6). Here, no further elaboration is provided.

[0170] In this embodiment, the algorithm for iteratively calculating the upper limit value and the lower limit value of the initial membrane water content interval can adopt the precise one-dimensional line search monotonic descent algorithm based on the golden section, or other iterative algorithms. Here, no specific limitation is provided.

[0171] In this embodiment, by combining the collected impedance test value with the impedance calculation value obtained from the impedance mechanism model, the initial membrane water content interval is jointly determined, and the upper limit value and the lower limit value of the initial membrane water content interval are iteratively calculated, which improves the accuracy and efficiency of the internal water content evaluation of the fuel cell stack, and enables online quantitative evaluation of the membrane water content, more intuitively reflecting the wet and dry state of the proton exchange membrane, and is applicable to various fuel cell systems.

[0172] It should be noted that the device for evaluating the water content inside the fuel cell stack provided in the above embodiments and the method for evaluating the water content inside the fuel cell stack provided in the above embodiments belong to the same concept. The specific ways in which each module and unit perform operations have been described in detail in the method embodiments, and will not be elaborated here. In actual application, the device for evaluating the water content inside the fuel cell stack provided in the above embodiments can, as needed, allocate the above functions to different functional modules, that is, divide the internal structure of the device into different functional modules to complete all or part of the functions described above. No limitation is imposed here either.

[0173] The embodiments of the present application also provide a fuel cell, and the fuel cell uses the method for evaluating the water content inside the fuel cell stack provided in the above embodiments to evaluate the water content.

[0174] The embodiments of the present application also provide a vehicle, and the vehicle includes the device for evaluating the water content inside the fuel cell stack provided in the above embodiments or the fuel cell provided in the above embodiments.

[0175] The embodiments of the present application also provide an electronic device, including: one or more processors; a storage device for storing one or more programs, and when the one or more programs are executed by the one or more processors, the electronic device implements the method for evaluating the water content inside the fuel cell stack provided in the above embodiments.

[0176] Figure 13 The structural schematic diagram of a computer system of an electronic device suitable for implementing the embodiments of the present application is shown. It should be noted that Figure 13 The computer system of the electronic device shown is only an example and should not impose any limitation on the functions and usage scope of the embodiments of the present application.

[0177] As Figure 13 shown, the computer system 1300 includes a central processing unit (CPU) 1301, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 1302 or the program loaded from the storage section 1308 into the random access memory (RAM) 1303, such as executing the method in the above embodiments. In the RAM 1303, various programs and data required for system operation are also stored. The CPU 1301, ROM 1302, and RAM 1303 are connected to each other through a bus 1304. The input / output (I / O) interface 1305 is also connected to the bus 1304.

[0178] The following components are connected to the I / O interface 1305: an input section 1306 including a keyboard, a mouse, etc.; an output section 1307 including, for example, a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1308 including a hard disk, etc.; and a communication section 1309 including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication section 1309 performs communication processing via a network such as the Internet. A drive 1310 is also connected to the I / O interface 1305 as needed. A removable medium 1311, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 1310 as needed so that a computer program read from it can be installed into the storage section 1308 as needed.

[0179] Specifically, according to an embodiment of the present application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, an embodiment of the present application includes a computer program product that includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through the communication section 1309, and / or installed from the removable medium 1311. When the computer program is executed by a central processing unit (CPU) 1301, various functions defined in the system of the present application are executed.

[0180] It should be noted that the computer-readable medium shown in the embodiments of the present application can be a computer-readable signal medium, a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable signal medium can include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable computer program. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The computer program contained on a computer-readable medium can be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0181] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present application. Among them, each block in the flowchart or block diagram can represent a module, a program segment, or a part of code, and the above module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order from that marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram or flowchart, and the combination of blocks in the block diagram or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0182] The units involved in the embodiments described in this application can be implemented in software or in hardware, and the described units can also be provided in a processor. Among them, the names of these units do not constitute a limitation to the unit itself in some cases.

[0183] On the other hand, this application also provides a computer-readable storage medium, on which computer-readable instructions are stored. When the computer-readable instructions are executed by a processor of a computer, the computer is enabled to execute the method for evaluating the water content inside a fuel cell stack provided in each of the above embodiments. The computer-readable storage medium may be included in the electronic device described in the above embodiments, or may exist alone without being assembled into the electronic device.

[0184] It should be noted that although several modules or units of a device for action execution are mentioned in the above detailed description, such a division is not mandatory. In fact, according to the embodiments of this application, the features and functions of the two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0185] Through the description of the above embodiments, those skilled in the art can easily understand that the example embodiments described herein can be implemented in software or in the form of software combined with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, including several instructions to enable a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) to execute the method according to the embodiments of this application.

[0186] After considering the specification and practicing the embodiments disclosed herein, those skilled in the art will readily conceive of other embodiments of this application. This application is intended to cover any variations, uses, or adaptations of this application, which follow the general principles of this application and include common general knowledge or conventional technical means in the technical field not disclosed in this application.

[0187] It should be understood that the above content is only a preferred exemplary embodiment of this application and is not used to limit the implementation of this application. Those of ordinary skill in the art can easily make corresponding adaptations or modifications according to the main concept and spirit of this application. Therefore, the protection scope of this application should be subject to the protection scope required by the claims.

Claims

1. A method for evaluating the water content inside a fuel cell stack, characterized in that, The method for evaluating the water content inside the fuel cell stack includes: Obtaining the operating parameters and impedance test values of the fuel cell stack; Determining the current membrane water content calibration value based on the operating parameters; Combining the operating parameters and the current membrane water content calibration value to calculate the impedance calculation value of the fuel cell stack; wherein, the process of combining the operating parameters and the current membrane water content calibration value to calculate the impedance calculation value of the fuel cell stack includes: inputting the operating parameters and the current membrane water content calibration value into an impedance mechanism model to obtain the impedance calculation value; the impedance mechanism model is constructed based on the structural parameters of the fuel cell stack; the structural parameters include: material layer thickness, porosity; Based on the impedance test value and the impedance calculation value, jointly determining the initial membrane water content interval, and using a precise one-dimensional line search monotonic descent algorithm based on the golden section to iteratively calculate the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result; Among them, the process of jointly determining the initial membrane water content interval based on the impedance test value and the impedance calculation value includes: Calculating the difference between the impedance test value and the impedance calculation value to obtain an impedance difference; Comparing the impedance difference with a preset difference, and determining the initial membrane water content interval according to the comparison result.

2. The method for evaluating the water content inside a fuel cell stack according to claim 1, wherein The process of comparing the impedance difference with a preset difference and determining the initial membrane water content interval according to the comparison result includes: If the impedance difference is equal to the preset difference, then using the current membrane water content calibration value as the water content evaluation result; If the impedance difference is less than the preset difference, then setting the upper limit value of the initial membrane water content interval to a first preset membrane water content value, and setting the lower limit value of the initial membrane water content interval to the current membrane water content calibration value; If the impedance difference is greater than the preset difference, then setting the upper limit value of the initial membrane water content interval to the current membrane water content calibration value, and setting the lower limit value of the initial membrane water content interval to a second preset membrane water content value.

3. The method for evaluating the water content inside a fuel cell stack according to claim 1 or 2, characterized in that The process of iteratively calculating the upper limit value and the lower limit value of the initial membrane water content interval to obtain the water content evaluation result includes: Calculating the upper limit value of the initial membrane water content interval according to the upper limit value iteration formula to obtain the iterated upper limit value; and calculating the lower limit value of the initial membrane water content interval according to the lower limit value iteration formula to obtain the iterated lower limit value; If the absolute difference between the iterated lower limit value and the iterated upper limit value is less than a preset absolute difference, then using the average value of the iterated lower limit value and the iterated upper limit value as the water content evaluation result; If the absolute difference between the iterated lower limit value and the iterated upper limit value is greater than or equal to the preset absolute difference, then according to the upper limit value iteration formula, calculate the iterated upper limit value to obtain the upper limit value after re-iteration, and according to the lower limit value iteration formula, calculate the iterated lower limit value to obtain the lower limit value after re-iteration, until the absolute difference between the lower limit value after re-iteration and the upper limit value after re-iteration is less than the preset absolute difference; If the absolute difference between the lower limit value after re-iteration and the upper limit value after re-iteration is less than the preset absolute difference, then take the average value of the lower limit value after re-iteration and the upper limit value after re-iteration as the water content evaluation result.

4. The method for evaluating the water content inside a fuel cell stack according to claim 3, wherein The upper limit value iteration formula includes: ， Among them, represents the upper limit value obtained after k iterations of the upper limit value of the initial membrane water content range, represents the lower limit value obtained after k - 1 iterations of the lower limit value of the initial membrane water content range, represents the upper limit value obtained after k - 1 iterations of the upper limit value of the initial membrane water content range; The lower limit value iteration formula includes: ， Among them, represents the lower limit value obtained after k iterations of the lower limit value of the initial film water content range, represents the lower limit value obtained after k - 1 iterations of the lower limit value of the initial film water content range, represents the upper limit value obtained after k - 1 iterations of the upper limit value of the initial film water content range.

5. The method for evaluating the water content inside a fuel cell stack according to claim 1 or 2, characterized in that, If the operating parameters include the current temperature value, the calculation formula of the impedance calculation value of the fuel cell stack includes: ， Among them, represents the calculated impedance value of the fuel cell stack, represents the specific internal resistance of the proton exchange membrane per proton surface, represents the specific internal resistance of the porous layer; The calculation formula of the proton surface specific internal resistance of the proton exchange membrane includes: ， Among them, represents the specific resistance of the proton side of the proton exchange membrane, represents the thickness of the material layer containing the electrolyte firmware, represents the effective conductivity of the proton exchange membrane; The calculation formula of the effective conductivity of the proton exchange membrane includes: ， Among them, represents the effective conductivity of the proton exchange membrane, represents the conductivity of the proton exchange membrane, represents the volume fraction of the perfluorosulfonic acid-based polymer in the catalyst layer in the total volume of the catalyst layer; The calculation formula of the conductivity of the proton exchange membrane includes: ， Among them, represents the conductivity of the proton exchange membrane, represents the calibrated value of the current membrane water content, represents the current temperature value; The calculation formula of the porous layer specific internal resistance includes: ， Among them, represents the specific internal resistance of the porous layer, represents the material layer thickness of the porous medium fixture, represents the effective conductivity of the porous medium layer; The calculation formula of the effective conductivity of the porous medium layer includes: ， wherein, represents the effective conductivity of the porous medium layer, represents the intrinsic conductivity of electrons, represents the porosity of the material layer.

6. The method for evaluating the water content inside a fuel cell stack according to claim 1 or 2, characterized in that, If the operating parameters include the current operating parameters and historical operating parameters, then the process of determining the current membrane water content calibration value based on the operating parameters includes: Obtain the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters, where the historical operating parameters include the operating parameters of different historical operating condition points; Select one historical operating condition point from different historical operating condition points as the first historical operating condition point; If the operating parameters of the first historical operating condition point are not successfully compared with the current operating parameters, then select one historical operating condition point from different historical operating condition points again as the second historical operating condition point until the operating parameters of the second historical operating condition point are successfully compared with the operating parameters, and the first historical operating condition point is different from the second historical operating condition point; If the operating parameters of the first historical operating condition point are successfully compared with the current operating parameters, then take the historical membrane water content calibration value corresponding to the operating parameters of the first historical operating condition point as the current membrane water content calibration value; or, if the operating parameters of the second historical operating condition point are successfully compared with the current operating parameters, then take the historical membrane water content calibration value corresponding to the operating parameters of the second historical operating condition point as the current membrane water content calibration value.

7. The method for evaluating the water content inside a fuel cell stack according to claim 6, characterized in that, Before obtaining the historical membrane water content calibration value of the fuel cell stack under the historical operating parameters, the method for evaluating the water content inside the fuel cell stack includes: Control the fuel cell stack to operate according to the operating parameters of different historical operating condition points on the polarization curve, and during the process of the fuel cell stack operating according to the operating parameters of each historical operating condition point on the polarization curve, collect the impedance data of the fuel cell stack to obtain the impedance data corresponding to the operating parameters of different historical operating condition points; Based on the impedance data corresponding to the operating parameters of each historical operating condition point, calibrate the membrane water content to obtain the historical membrane water content calibration values corresponding to the operating parameters of different historical operating condition points.

8. The method for evaluating the water content inside a fuel cell stack according to claim 1 or 2, characterized in that, Before obtaining the impedance test value of the fuel cell stack, the method for evaluating the internal water content of the fuel cell stack includes: Input a preset injection current into the alternating current / frequency injection module preset in the boost / buck converter, and after the boost / buck converter receives the preset injection current, control the fuel cell stack to respond, collect the impedance test value of the fuel cell stack, and adjust the preset injection current based on the response current. The preset injection current has a preset frequency range; Input the adjusted preset injection current into the alternating current / frequency injection module, and after the boost / buck converter receives the adjusted preset injection current, control the fuel cell stack to respond, collect the impedance test value of the fuel cell stack again, and adjust the adjusted preset injection current based on the response current obtained again to achieve real-time collection of the impedance test value of the fuel cell stack.

9. The method for evaluating the water content inside a fuel cell stack according to claim 8, characterized in that, The process of adjusting the preset injection current based on the response current includes: If the response current is greater than or equal to the preset current value, multiply the response current by a first preset ratio, and use the current value obtained after multiplication as the preset injection current; If the response current is less than the preset current value, multiply the response current by a second preset ratio, and use the current value obtained after multiplication as the preset injection current. The second preset ratio is greater than the first preset ratio.

10. An evaluation device for the water content inside a fuel cell stack, characterized in that, The device for evaluating the internal water content of the fuel cell stack includes: A parameter acquisition module for acquiring the operating parameters and impedance test values of the fuel cell stack; A calibration value determination module for determining the current membrane water content calibration value based on the operating parameters; An impedance value calculation module for calculating the impedance calculation value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value; wherein, the process of calculating the impedance calculation value of the fuel cell stack by combining the operating parameters and the current membrane water content calibration value includes: inputting the operating parameters and the current membrane water content calibration value into an impedance mechanism model to obtain the impedance calculation value; the impedance mechanism model is constructed based on the structural parameters of the fuel cell stack; the structural parameters include: material layer thickness, porosity; A water content evaluation module for jointly determining an initial membrane water content interval based on the impedance test value and the impedance calculation value, and using a precise one-dimensional line search monotonic descent algorithm based on the golden section to iteratively calculate the upper limit value and the lower limit value of the initial membrane water content interval to obtain a water content evaluation result; Among them, the process of jointly determining the initial membrane water content interval based on the impedance test value and the impedance calculation value includes: Calculating the difference between the impedance test value and the impedance calculation value to obtain an impedance difference; Comparing the impedance difference with a preset difference, and determining the initial membrane water content interval according to the comparison result.

11. A fuel cell, characterized in that, The fuel cell includes a device for evaluating the water content inside the fuel cell stack as described in claim 10.

12. An automobile, characterized in that, The vehicle includes a device for evaluating the water content inside the fuel cell stack as described in claim 10.

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