Diagnostic method and diagnostic system for diagnosing a fuel cell

Abstract

The present invention relates to a diagnostic method (100) for diagnosing at least one fuel cell of a fuel cell system, the diagnostic method (100) comprising the following steps: - providing (102) at least two different polarization models (1) for extracting a diagnostic fuel cell parameter set (3) from a polarization curve (2) of at least one fuel cell; - detecting (104) at least one polarization curve (2) from at least one measurement of at least one fuel cell; - applying (106) at least two of the different polarization models (1) previously detected to at least one polarization curve (2) of at least one fuel cell; - extracting (108) for each applied polarization model (1) a diagnostic fuel cell parameter set (3) from at least one polarization curve (2) of at least one fuel cell; Includes.

Description

[Technical Field]

[0001] The present invention relates to a diagnostic method and a diagnostic system for diagnosing at least one fuel cell of a fuel cell system, as well as a computer program product relating to the diagnostic method. [Background technology]

[0002] A polarization curve is the result of measurements that allow the evaluation of various properties of a fuel cell. The polarization curve is then a function of the fuel cell design (catalyst, membrane, etc.), the operating conditions (relative humidity, temperature, pressure, etc.), and the aging of the fuel cell components. Measurements are performed on a fuel cell test bench in a fuel cell system, usually at a constant temperature and under defined operating conditions.

[0003] To determine diagnostic parameters of a fuel cell from its associated polarization curve, polarization models are used in the prior art. Such polarization models are applied to the polarization curve, whereby desired diagnostic parameters are extracted from the polarization models. The extracted diagnostic parameters can be used to draw conclusions about the fuel cell, for example, about its degradation.

[0004] Known diagnostic methods have the problem that their results depend on the polarization model used, which may not extract all desired diagnostic parameters, or may provide inaccurate diagnostic parameters. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to at least partially overcome the above-mentioned problems, in particular to provide an improved diagnostic method for diagnosing fuel cells, which provides results that are as reliable as possible. [Means for solving the problem]

[0006] The above problem is solved by a diagnostic method having the features of claim 1, a computer program product having the features of claim 11, and a diagnostic system having the features of claim 12. Further features and details of the invention will become apparent from the dependent claims, the following description and the drawings, whereby features and details explained in the context of the diagnostic method according to the invention naturally also apply in the context of the diagnostic system according to the invention and the computer program product according to the invention and vice versa, respectively, whereby reference is or can always be made to one another in relation to the disclosure of the individual inventive aspects.

[0007] According to the present invention, there is provided a diagnostic method for diagnosing at least one fuel cell in a fuel cell system, the diagnostic method comprising the steps of: - providing at least two different polarization models for extracting a diagnostic fuel cell parameter set from a polarization curve of at least one fuel cell; - detecting at least one polarization curve from at least one measurement of at least one fuel cell; - applying at least two of the previously detected different polarization models to at least one polarization curve of at least one fuel cell; - extracting, for each of the applied polarization models, a diagnostic fuel cell parameter set from at least one polarization curve of at least one fuel cell. Includes.

[0008] Therefore, the diagnostic method according to the present invention uses at least two different polarization models. As mentioned above, these polarization models are used to extract a diagnostic fuel cell parameter set from the polarization curves of one or more fuel cells, respectively. Such a diagnostic fuel cell parameter set can also include polarization losses as fuel cell parameters. These can be, for example, losses due to membrane permeability, activity losses due to slow cathodic reactions (reaction kinetics), losses due to ohmic resistance (electrical resistance of the electrolyte, catalyst layer, gas diffusion layer, bipolar plates, interface contacts, and terminal connections), and concentration losses (product delivery to the reaction site, hydrodynamic limitations at the macro- and micro-levels (convection and diffusion)). Such polarization models can be given by one or more mathematical relationships, in particular functions. For example, the polarization model can be given by a function of the cell voltage depending on various input parameters, which can be, for example, operating parameters or operating conditions. Examples of possible polarization models are the Chamberline-Kim and Larminie-Dicks models.

[0009] By applying different polarization models to one or more polarization curves of one or more fuel cells, not only are diagnostic fuel cell parameter sets extracted, and thus obtained, but a diagnostic fuel cell parameter set is obtained for each of the applied polarization models. In this case, these diagnostic fuel cell parameter sets represent a diagnosis of at least one fuel cell, since they represent characteristic data that reveal the state or condition of the fuel cell, e.g., with respect to degradation. However, further diagnostic steps, e.g., estimation of degradation, may follow. Thus, according to the present invention, the presence of at least two diagnostic fuel cell parameter sets for different polarization models results in better diagnostic results, since the results do not depend on a single polarization model, which may provide an inaccurate diagnosis. In particular, more accurate diagnostic results can be achieved by comparing the diagnostic fuel cell parameter sets with each other, as will be explained in more detail below.

[0010] The diagnostic method can in principle be used to diagnose one or more fuel cells, in particular one or more complete, in particular interconnected, fuel cell stacks or complete fuel cell systems, where one polarization curve can be determined for each fuel cell, fuel cell stack or fuel cell system.

[0011] The measurements from which the polarization curve is determined can be carried out, in particular on a test bench of at least one fuel cell of the fuel cell system, preferably at a constant temperature and under defined operating conditions. The measurement results can already be present when carrying out the diagnostic method, from which the polarization curve only needs to be determined. However, as will be explained in more detail below, the measurements can also be carried out within the scope of the diagnostic method.

[0012] It is not necessary to perform all method steps of the method according to the invention in the order indicated by their enumeration. Instead, individual method steps can be performed in a different order or simultaneously. In particular, individual or all method steps can be repeated, in particular performed continuously. In this way, diagnostic fuel cell parameter sets can be continuously extracted, in particular outputted. This allows live monitoring of the diagnostic method, in particular in the case of live measurements in which polarization curves are continuously detected and polarization models are applied, as will be explained in more detail below.

[0013] As mentioned above, it may be contemplated that at least one or all of the extracted diagnostic fuel cell parameter sets may be output as a further step in the diagnostic method. As will be described in more detail below by way of example, which of the extracted fuel cell diagnostic parameters are output may be determined, possibly by arbitrary selection, in particular based on discarding individual diagnostic fuel cell parameters.

[0014] The diagnostic method further comprises the steps of: - determining fuel cell parameters of the diagnostic fuel cell parameter set to be extracted; - selecting at least two of the provided polarization models based on the determined fuel cell parameters in the diagnostic fuel cell parameter set to be extracted, It may be contemplated that the selected polarization model is applied to at least one polarization curve. This ensures that only the provided polarization models that output previously determined fuel cell parameters are selected for application to the polarization curve. That is, polarization models that provide diagnostic fuel cell parameter sets that do not provide the determined, and therefore desired, fuel cell parameters are not considered. For example, if a degradation estimation of at least one fuel cell is to be performed, the fuel cell parameters required for this purpose may be determined in advance. In that case, polarization models that do not provide those parameters in the diagnostic fuel cell parameter set can be discarded. This allows for intelligent selection of a polarization model from a large number of polarization models provided, for example, in a database, which saves computational resources of the corresponding diagnostic system executing the diagnostic method and enables faster diagnosis.

[0015] The diagnostic method may further include matching the provided polarization model with available input data, and applying a selected polarization model that requires the available input data, and in particular no other input data, to the at least one polarization curve. The input data may be, for example, fuel cell voltage and / or current, as well as operating conditions such as pressure, temperature, relative humidity, and / or fuel cell data such as Pt loading, membrane thickness, etc. In this way, it can be ensured that only a polarization model that enables diagnosis based on the detected at least one polarization curve is applied to the at least one polarization curve.

[0016] Furthermore, the goodness of fit of each polarization model for at least one polarization curve can be determined, and extracted diagnostic fuel cell parameter sets that fall below a predetermined minimum goodness of fit can be discarded. Correspondingly, the minimum goodness of fit can be predetermined to increase the reliability of the diagnostic fuel cell parameter sets. In this way, it can be ensured that only sufficiently reliable diagnostic fuel cell parameter sets are provided for further use, in particular for estimating the power output and / or degradation of at least one fuel cell.

[0017] Furthermore, it is possible to envisage that the extracted diagnostic fuel cell parameter sets of different polarization models are compared with each other, which allows the diagnostic fuel cell parameter sets to be checked against each other and, to the extent that they substantially agree with each other, to support the diagnostic results, i.e., this also allows for increased reliability of the diagnostic method or the results obtained therefrom.

[0018] In this case, it may be envisaged that a common diagnostic fuel cell parameter set for at least one fuel cell is formed based on the comparison. In this way, the fuel cell parameters deemed most reliable may be obtained from each diagnostic fuel cell parameter set and combined into a common diagnostic fuel cell parameter set. However, it may also be possible to form, for example, common values of fuel cell parameters from different diagnostic fuel cell parameter sets, such as averages, weighted averages, medians, etc., and these common values then form the common diagnostic fuel cell parameter set.

[0019] Furthermore, a validity check can be performed on the extracted diagnostic fuel cell parameter sets, for example to check whether the fuel cell parameters of the diagnostic fuel cell parameter sets are inconsistent with other diagnostic fuel cell parameter sets or outside predefined value ranges, from which it can be concluded that these extracted diagnostic fuel cell parameter sets can be discarded as invalid, which also increases the reliability of the diagnostic method.

[0020] The fuel cell parameters of the extracted fuel cell parameter set can also be compared with degradation and / or defect parameters from a database. The database can be equipped, for example, with values from previous diagnostic results and / or values from one or more simulation models. This allows the fuel cell parameters to be matched with a database of defect and / or degradation fingerprints in order to estimate the occurrence of defects, damage, and / or degradation of at least one fuel cell. It is also advantageous, in principle, if the fuel cell parameters themselves evolve via the same process, for example, via a polarization curve according to a first data set, followed by a polarization curve according to a second data set, and then again using a polarization curve according to the second data set. Therefore, in that case, the parameters evolve, particularly over time.

[0021] In particular, based on the fuel cell parameters of the extracted fuel cell parameter sets, degradation of the at least one fuel cell can be estimated. This use of extracted fuel cell parameter sets is particularly advantageous because multiple extracted fuel cell parameter sets are provided and / or only those that have not previously been discarded are used. The large number of parameter information allows for a very accurate and reliable estimation of degradation of the at least one fuel cell.

[0022] Furthermore, measurements of the at least one fuel cell can be performed as part of the diagnostic method. In particular, the measurements can be performed, at least temporarily, in parallel with the application and / or extraction steps of the diagnostic method. In this way, a live diagnostic method is provided in which polarization curves can be continuously updated, detected, and applied based on the measurements, and in which the at least one fuel cell can be integrated into a test bench.

[0023] In this case, the measurement of the at least one fuel cell is actively influenced, whenever possible, by at least one of the extracted diagnostic fuel cell parameter sets, i.e., feedback to the measurement method is provided based on at least one of the extracted diagnostic fuel cell parameter sets, and by changing measurement parameters in the measurement method, in particular on the test bench of the at least one fuel cell, the diagnostic result can be influenced accordingly.

[0024] Advantageously, it is also possible to actively influence the extracted diagnostic fuel cell parameter set of at least one fuel cell by the goodness of fit of each polarization model, i.e., it is possible to actively influence the fuel cell by the extracted diagnostic fuel cell parameter set.

[0025] A subject of the invention is also a computer program product comprising instructions that cause a computer to carry out the method according to the invention when the program is executed by a computer.

[0026] The computer program product according to the invention therefore offers the same advantages as those detailed in connection with the diagnostic method according to the invention.

[0027] In that case, the computer program product may be the computer program itself or a product such as a computer readable data memory capable of storing a computer program for performing the method according to the invention. Within the scope of the present invention, analog boards and screens, for example of an oscilloscope, may also be advantageous as computer program products.

[0028] The subject of the present invention is also a diagnostic system for diagnosing at least one fuel cell of a fuel cell system, the diagnostic system comprising the following modules: a providing module for providing at least two different polarization models for extracting a diagnostic parameter set from a polarization curve of a fuel cell; a detection module for detecting at least one polarization curve from at least one measurement of at least one fuel cell; an application module that applies at least two of the previously detected different polarization models to at least one polarization curve of at least one fuel cell; and - an extraction module for extracting, for each applied polarization model, a diagnostic fuel cell parameter set from at least one polarization curve of at least one fuel cell;

[0029] The diagnostic system according to the invention therefore offers the same advantages as those detailed in connection with the diagnostic method according to the invention.

[0030] In particular, the diagnostic system may be configured or designed to carry out the diagnostic method according to the invention.

[0031] In that case, the modules of the diagnostic system can, for example, each be implemented by separate computer program code or together by a common computer program code and / or by separate or common functional units of a computer. It is also possible for the individual modules to be implemented in a common module. The diagnostic system can in particular comprise one or more computers or be formed by one or more computers which can have individual modules.

[0032] The above-mentioned modules may also be configured to perform other steps of the diagnostic methods described herein, but each individual step may also be provided with its own additional modules, each distinguishable from the other by a name corresponding to the respective step. [Brief explanation of the drawings]

[0033] [Figure 1] 1 shows a schematic diagram of an exemplary embodiment of a diagnostic method and system according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0034] Other advantages, features and details of the invention will become apparent from the following description in which an embodiment is explained in detail with reference to the drawings.

[0035] In that regard, FIG. 1 shows a schematic diagram of an exemplary embodiment of a diagnostic method 100 and a diagnostic system 200 according to the present invention.

[0036] In a first method step, purely by way of example, three different polarization models 1 are provided 102. These may be given, for example, by one or more mathematical relations, in particular functions, that differ from one another. The provision 102 is performed by a provision module 202 of the diagnostic system 200.

[0037] In a next method step, a polarization curve 2 is determined 104 from (operational) measurements of one or more fuel cells on a corresponding test bench of the fuel cell system. Here, by way of example, a fuel cell stack is taken as the starting point, which may have been measured previously or can be measured within the scope of the diagnostic method 100. The polarization curve 2 determined from the measurements indicates various properties of the fuel cell stack. The determination 104 can be performed by a determination module 204 of the diagnostic system 200.

[0038] In another method step, application module 206 of diagnostic system 200 applies 106 different polarization models 1 to the polarization curve of the fuel cell stack, whereby in a next method step, extraction module 208 extracts 108 diagnostic fuel cell parameter sets 3 from the polarization curve 2 of the fuel cell stack for each applied polarization model 1.

[0039] This then results in three extracted diagnostic fuel cell parameter sets 3, each based on a different initially provided polarization model 1. These diagnostic fuel cell parameter sets 3 can then be output directly by the diagnostic method 100 and diagnostic system 200 and / or can undergo further method steps, not shown.

[0040] 1 exemplarily shows how in a subsequent method step a comparison 110 is performed by a comparison module 210 of diagnostic fuel cell parameter sets 3. Furthermore, FIG. 1 exemplarily shows how in a subsequent method step a formation 112 of a common diagnostic fuel cell parameter set 4 based on the previous comparisons is performed by a formation module 212. That is, for all individual diagnostic fuel cell parameter sets 3 a common diagnostic fuel cell parameter set 4 is formed which shows as accurate as possible fuel cell parameters characterizing the fuel cell stack. These fuel cell parameters can be output or used in other method steps not shown to estimate the degradation of the fuel cell stack.

[0041] Additionally or alternatively, the diagnostic method 100 may include other method steps not shown here, such as determining the fuel cell parameters to be extracted, matching with input data, determining goodness of fit, validation, etc. (Other possible items) (Item 1) A diagnostic method (100) for diagnosing at least one fuel cell of a fuel cell system, said diagnostic method (100) comprising the following steps: - providing (102) at least two different polarization models (1) for extracting a diagnostic fuel cell parameter set (3) from a polarization curve (2) of at least one fuel cell; - detecting (104) at least one polarization curve (2) from at least one measurement of at least one fuel cell; - applying (106) at least two of the different previously detected polarization models (1) to said at least one polarization curve (2) of said at least one fuel cell; - extracting (108) for each of the applied polarization models (1) a diagnostic fuel cell parameter set (3) from the at least one polarization curve (2) of the at least one fuel cell. (Item 2) The diagnostic method (100) further comprises the steps of: - determining (3) the fuel cell parameters of the diagnostic fuel cell parameter set (3) to be extracted; - selecting at least two of the provided polarization models (1) based on the determined fuel cell parameters in the diagnostic fuel cell parameter set (3) to be extracted, Item 1. The diagnostic method (100) according to item 1, wherein the selected polarization model (1) is applied to the at least one polarization curve (2). (Item 3) The diagnostic method (100) according to item 1 or 2 further comprises: matching the provided polarization model (1) with available input data; and applying a selected polarization model (1) that does not require input data other than the available input data to at least one polarization curve (2). (Item 4) a goodness of fit of each polarization model (1) to the at least one polarization curve (2) is determined, and extracted diagnostic fuel cell parameter sets (3) that fall below a predetermined minimum goodness of fit are discarded; 4. The diagnostic method (100) according to any one of items 1 to 3. (Item 5) the extracted diagnostic fuel cell parameter sets (3) of different polarization models (1) are compared with each other; 5. The diagnostic method (100) according to any one of items 1 to 4. (Item 6) Item 6. A diagnostic method (100) according to item 5, wherein a common diagnostic fuel cell parameter set (4) for the at least one fuel cell is formed based on the comparison. (Item 7) 7. A diagnostic method (100) according to any one of items 1 to 6, wherein a validation check of the extracted diagnostic fuel cell parameter set (3) is performed. (Item 8) 8. A diagnostic method (100) according to any one of items 1 to 7, wherein the fuel cell parameters of the extracted fuel cell parameter set (3) are compared with degradation and / or defect parameters from a database. (Item 9) 9. A diagnostic method (100) according to any one of items 1 to 8, wherein the degradation of the at least one fuel cell is estimated based on fuel cell parameters of the extracted fuel cell parameter set (3). (Item 10) 10. The diagnostic method (100) according to any one of items 1 to 9, wherein the measurement of the at least one fuel cell is performed as part of the diagnostic method (100). (Item 11) 11. A computer program comprising instructions that, when the program is executed by a computer, cause the computer to carry out the diagnostic method according to any one of items 1 to 10. (Item 12) A diagnostic system (200) for diagnosing at least one fuel cell of a fuel cell system, said diagnostic system (200) comprising the following modules: a providing module (202) for providing at least two different polarization models (1) for extracting a diagnostic parameter set (3) from a polarization curve (2) of a fuel cell; a detection module (204) for detecting at least one polarization curve (2) from at least one measurement of said at least one fuel cell; an application module (206) for applying at least two of the different previously detected polarization models (1) to the at least one polarization curve (2) of the at least one fuel cell; and - an extraction module (208) for extracting, for each of the applied polarization models (1), a diagnostic fuel cell parameter set (3) from the at least one polarization curve (2) of the at least one fuel cell.

[0042] The above description of the embodiments merely illustrates the present invention to the extent that it is an example. [Explanation of symbols]

[0043] 100 Diagnostic Methods 102 offers 104 detection 106 Application 108 Extracts 110 Comparison 112 Formation 200 Diagnostic System 202 Provided Modules 204 Detection Module 206 Application Module 208 Extraction Module 210 Comparison Module 212 Formation Module

Claims

1. 1. A diagnostic method for diagnosing at least one fuel cell in a fuel cell system, said diagnostic method comprising the steps of: - providing at least two different polarization models for extracting a diagnostic fuel cell parameter set from a polarization curve of at least one fuel cell; - detecting at least one polarization curve from at least one measurement of at least one fuel cell; - applying at least two of the different previously detected polarization models to said at least one polarization curve of said at least one fuel cell; - extracting, for each of said applied polarization models, a set of diagnostic fuel cell parameters from said at least one polarization curve of said at least one fuel cell.

2. The diagnostic method further comprises the steps of: - determining the fuel cell parameters of the diagnostic fuel cell parameter set to be extracted; - selecting at least two of the provided polarization models based on the determined fuel cell parameters in the diagnostic fuel cell parameter set to be extracted, The diagnostic method of claim 1 , wherein the selected polarization model is applied to the at least one polarization curve.

3. 2. The diagnostic method of claim 1, further comprising: matching the provided polarization model with available input data; and applying a selected polarization model, which does not require input data other than the available input data, to at least one polarization curve.

4. a goodness of fit of each polarization model to the at least one polarization curve is determined, and extracted diagnostic fuel cell parameter sets that fall below a predetermined minimum goodness of fit are discarded; The diagnostic method according to claim 1.

5. the extracted diagnostic fuel cell parameter sets of different polarization models are compared with each other; The diagnostic method according to claim 1.

6. The diagnostic method of claim 5 , wherein a common diagnostic fuel cell parameter set for the at least one fuel cell is formed based on the comparison.

7. The diagnostic method of claim 1 , wherein a validation check is performed on the extracted diagnostic fuel cell parameter set.

8. 2. The diagnostic method of claim 1, wherein fuel cell parameters of the extracted fuel cell parameter set are compared with degradation and / or defect parameters from a database.

9. The diagnostic method of claim 1 , wherein the degradation of the at least one fuel cell is estimated based on fuel cell parameters of the extracted fuel cell parameter set.

10. The diagnostic method of claim 1 , wherein said measuring of said at least one fuel cell is performed as part of said diagnostic method.

11. A computer program comprising instructions that, when the program is executed by a computer, cause the computer to carry out the diagnostic method of any one of claims 1 to 10.

12. A diagnostic system for diagnosing at least one fuel cell of a fuel cell system, said diagnostic system comprising the following modules: a providing module for providing at least two different polarization models for extracting a set of diagnostic parameters from a polarization curve of a fuel cell; a detection module for detecting at least one polarization curve from at least one measurement of said at least one fuel cell; an application module for applying at least two of the different previously detected polarization models to the at least one polarization curve of the at least one fuel cell; and a diagnostic system characterized by an extraction module for extracting, for each of said applied polarization models, a set of diagnostic fuel cell parameters from said at least one polarization curve of said at least one fuel cell;

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