Method and system for initiating and determining PEM fuel cell defects

Abstract

The present invention relates to a system (100) and a method for initiating and determining specific defects and / or damage to a PEM fuel cell (10). In addition to measuring an operating parameter, comparing a measurement signal with a reference signal, and determining whether a specific defect and / or damage exists, the operating parameter is controlled in particular in a test operation as a function of a provided stress factor pattern, in the stress factor pattern, a critical setting and / or a curve of operating parameters for inducing defects and / or damage to the fuel cell (10) to be tested is stored.

Description

Technical Field

[0001] The present invention relates to a method and a corresponding system for inducing and determining defects and / or damages in a PEM fuel cell. Background Art

[0002] The method and system according to the invention are suitable for studying functional failures and damage in low-temperature fuel cells with polymer electrolyte membranes (PEM fuel cells). The occurrence of defects can be identified and studied, thereby drawing conclusions about the possibility of avoiding defects or improving fuel cells.

[0003] There are many known measurement methods which carry out measurements in the system environment of a fuel cell or a fuel cell stack when it is running or stopped, in the system environment of a fuel cell as an energy source or also during its use. Usually, the measurements generate signals, by analyzing which the aging state or degradation of the fuel cell can be indirectly inferred.

[0004] A known measurement method for identifying degradation of a catalytic element in a fuel cell system can indirectly indicate degradation by measuring the temperature. The temperature measurements used are processed into a temperature data set for calculating the temperature gradient in the inlet region of the catalytic element. In a second step of the method, the temperature gradient is compared with a reference parameter. In a final step, the degradation state is evaluated based on the comparison result.

[0005] In another known measurement method, in order to detect defects and / or degradation in a fuel cell device, a power spectral density (PSD) analysis of the voltage signal output generated by the fuel cell device during a stable operation period is performed, and specific defects and / or degradation signs are identified by specific PSD patterns of the measured voltage signal.

[0006] There is another known measurement method for analyzing the performance degradation of a fuel cell, in which the AC impedance is measured and compared with a reference value. Based on the comparison result, the performance degradation of the fuel cell can be indirectly identified.

[0007] Although these measurement methods and their techniques can be partially integrated in the system environment of the application in order to monitor the aging state during the service life, the information obtained is often related to the specific use of a specific fuel cell model and the specific influences that the fuel cell or the corresponding fuel cell stack has experienced during its service life in its application and system environment. The integration of information from independent monitoring may involve considerable expenditure or be unavailable to the end user at the end of the service life and, depending on the length of the service life, involve a considerable time span. In addition, the measurement techniques or analyses need to be individually adapted and the information obtained can hardly be directly applied to other PEM fuel cell models or their applications.

[0008] Therefore, a technique is needed that can universally study specific structural defects or their resulting performance impact, make them comparable between any PEM fuel cell models, or conduct empirical studies on specific defects within an acceptable time frame. Summary of the invention

[0009] The task of the present invention is to provide a technique that allows for universal and reproducible investigation of defects or damage or degradation of PEM fuel cells. Another task of the present invention is to automate said investigation and to implement it within a reasonable time frame for product development.

[0010] The above object is achieved by a system having the features of claim 1 and a method having the features of claim 8. Further features and details of the invention are derived from the dependent claims, the description and the figures. Here, the features and details described with respect to the device according to the invention are obviously also applicable in connection with the method according to the invention and vice versa, so that the disclosures of the individual inventive aspects are always made or can be referred to one another.

[0011] The system according to the present invention is designed to induce and determine specific defects and / or damages of a PEM fuel cell. To this end, the system of the present invention has a variety of system components. A measurement module is used to measure at least one operating parameter of a fuel cell and output a fingerprint pattern containing a time signal curve of a measurement signal. The measurement module includes at least one sensor for detecting at least one operating parameter of the fuel cell. A comparison module is used to compare the signal curve of the measurement signal in the output fingerprint pattern with the signal curve of the reference signal in the reference pattern, wherein a plurality of reference patterns are provided in the comparison module, and the signal curves of the reference signals included therein characterize different specific defects and / or damages. A determination module is used to determine whether specific defects and / or damages are at least gradually occurring, which are characterized by the signal curve of the reference signal in the reference pattern included in the comparison process, wherein the determination module is set up to make a judgment based on the common intersection between the signal curves of the measurement signal of the fingerprint pattern and the reference signal of the reference pattern.

[0012] According to the present invention, the system includes a test bench module, which has a fuel gas test supply device for supplying fuel gas to the anode part of the fuel cell during the test operation, an oxidizing gas test supply device for supplying oxidizing gas to the cathode part of the fuel cell during the test operation, and an electrical test load for outputting electrical energy from the fuel cell during the test operation. In addition, in the control module for controlling the operating parameters of the fuel cell test operation at the test bench module, a stress factor mode is particularly provided, in which critical settings and / or critical change curves of operating parameters for inducing fuel cell defects and / or damage during the test operation are stored.

[0013] Similarly, the present invention provides a corresponding method for inducing and determining specific defects and / or damages of a PEM fuel cell, comprising the following steps: measuring at least one operating parameter of the fuel cell by acquiring at least one operating parameter of the fuel cell by at least one sensor, and outputting a fingerprint pattern comprising a time signal curve of the measurement signal; comparing the signal curve of the measurement signal in the output fingerprint pattern with the signal curve of the reference signal in the reference pattern by providing a plurality of reference patterns comprising signal curves of reference signals representing various specific defects and / or damages; determining whether the specific defects and / or damages represented by the signal curve of the reference signal in the reference pattern included in the comparison process at least gradually appear, wherein the determination is performed based on the common intersection between the signal curves of the measurement signal in the fingerprint pattern and the reference signal in the reference pattern.

[0014] The invention provides for the following steps: a test run is performed on a test bench, the test bench having a fuel gas test supply device for supplying fuel gas to the anode part of the fuel cell during the test run, an oxidizing gas test supply device for supplying oxidizing gas to the cathode part of the fuel cell during the test run, and an electrical test load for outputting electrical energy from the fuel cell during the test run. Here, the control of operating parameters of the fuel cell test run on the test bench is performed according to at least one stress factor pattern, in which critical settings and / or time curves of operating parameters for inducing defects and / or damage to the fuel cell during the test run are stored.

[0015] The present invention thus provides for the groundbreaking combination of measurement and analysis techniques with a common test environment, controlling the test run via a common model to achieve fuel cell aging or degradation in a controlled, preferably accelerated and reproducible manner.

[0016] An advantage of the present invention is that it provides a universal system and method for controlled, uniform inspection or testing of different PEM fuel cell models and allows for efficient shortening of long-duration testing based on fatigue stress factor models.

[0017] Therefore, the system or method is flexibly applicable to PEM fuel cells of various types, structures and sizes, and is particularly valuable for product development or experimental research.

[0018] Another advantage of the present invention is the automated identification of aging phenomena, such as minor or major impairments in performance, structure or integrity of a PEM fuel cell, to avoid complete functional failure due to known specific defects or damage.

[0019] Likewise, one advantage of the present invention is that the system or method is provided by a manufacturer or supplier with a series of universal reference patterns, including basic reference curves of reference signals, applicable to a variety of known defect patterns, thereby giving customers diagnostic capabilities.

[0020] In this article, the term "operating parameters" is defined as different controlled variables, such as gas quantity, power demand or consumption, reactant temperature, and the resulting values, such as the output voltage or no-load voltage of the fuel cell, product temperature, chemical concentrations of various substances in the product, etc., which can be actively adjusted or regulated during the test run, or can appear or be measured passively.

[0021] In this context, the term "measurement signal" defines a signal which directly reflects the value of a measurement parameter measured by a sensor or which can be derived indirectly from the measured measurement parameter.

[0022] In this article, the term "fingerprint pattern" is defined as the trend of the signal level curve of the measurement signal collected over a period of time.

[0023] In this article, the term "reference signal" is defined as a signal of the same type and meaning as the measured signal, used for comparison.

[0024] In this article, the term "reference mode" is defined as the signal level curve trend of a reference signal stored over a period of time, wherein the curve trend particularly includes characterizing parts, such as inflection points, constants, upper and lower limits, etc., whose time relationships and deviations are different from the typical values ​​and variation curves of a new or intact fuel cell.

[0025] In this article, the term "common intersection" is defined as the common characterization features of the signal curve trend, such as the number of inflection points, amplitude, and time characteristics (such as width, frequency, etc.).

[0026] As used herein, the term "specific defects" is defined as typical types of damage to a fuel cell structure, such as thinning or damage to the membrane (eg, in the form of holes or cracks), or thickness or area deactivation in certain regions of a catalyst layer.

[0027] In this context, the term "damage" is defined as a reduction in the performance of a fuel cell (involving parameters such as output voltage or output current) relative to the reactant supply input parameters, or a degradation of the electrochemical or physical processes occurring in the fuel cell. Damage may occur or be determined in a progressive manner and may be a direct or indirect result of specific defects or damage to the fuel cell structure or other aging phenomena.

[0028] As used herein, the term "stress factor model" is defined as a family of static or dynamic characteristic curves of stored operating parameters associated with a control variable (e.g., gas quantity, power demand or consumption, reactant temperature), or a family of static or dynamic characteristic curves associated with a target value of a result parameter (e.g., the output voltage or no-load voltage of a fuel cell).

[0029] In this context, the term "critical setting or critical variation curve of an operating parameter" is defined as an absolute value, its average duration or its dynamic variation, for example, in particular a periodic high output voltage or no-load voltage selected to achieve reproducible test operation on the fuel cell to be tested, which, according to expert knowledge, leads to the rapid onset of extreme stress and aging effects.

[0030] According to an advantageous aspect of the invention, the at least one stress factor pattern has a periodic variation curve of an operating parameter for achieving a periodic variation of the fuel cell output voltage accompanied by a specified voltage peak. Thus, during the test operation, a stress test of the fuel cell can be achieved by a specified number of voltage peaks of the fuel cell output voltage or no-load voltage or an elevated voltage platform of a specified total duration, thereby inducing structural damage to the fuel cell in an adjustable and reproducible manner.

[0031] According to an advantageous aspect of the invention, the signal curves of the measurement signal and the reference signal can be normalized to a common zero point and / or a reference when comparing or determining a defect, and a common intersection is determined based on the overlap of the width and / or amplitude frequency of the normalized signal curves. In this way, the system or method is able to detect known defect patterns in any fuel cell model with different parameter values ​​and time characteristics based on a pre-stored universal reference pattern with preset parameter values ​​and time characteristics.

[0032] According to an advantageous aspect of the invention, once the presence of a specific defect or damage is determined, a diagnostic output signal can be output including a percentage probability of diagnosis of the specific defect and / or damage, said percentage being based on the intersection between the signal curves of the measurement signal and the reference signal.

[0033] According to an advantageous aspect of the invention, the provided reference pattern can be edited. This editing is based on a fuel cell-specific adjustment, i.e., the signal curve of the reference signal in the reference pattern is matched with the signal curve of the measurement signal of the following fingerprint pattern, according to which the specific defect and / or damage characterized by the signal curve of the reference signal in the reference pattern is determined to be at least gradually appearing. Therefore, in this general system or method, the general reference pattern can be personalized for a specific research model to improve the defect recognition of the specific model.

[0034] According to an advantageous aspect of the present invention, the system or method may also have a signal generator for applying an AC voltage-based excitation signal to the fuel cell, wherein the at least one sensor detects an AC voltage-based signal response, the signal response originating from the interaction of the excitation signal with the fuel cell. Through the technology, the measurement method can be extended to AC impedance measurement through active signal excitation and passive signal response for checking the fuel cell state.

[0035] Alternatively, according to one aspect of the present invention, the measurement technology used by the system or method may include: a voltage sensor for detecting the output voltage of the fuel cell, a hydrogen sensor for detecting the hydrogen concentration on the cathode side of the fuel cell, a conductivity sensor for detecting the conductivity of product water discharged from the fuel cell, and / or a virtual sensor, which is simulated based on the indirect measurement results of other physical sensors using the degradation model of the analysis software on the measurement module.

[0036] Furthermore, according to one aspect of the present invention, the method of the present invention is implemented by a computer program, and the computer program is combined with necessary hardware included in the system of the present invention to execute the steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Further advantages, features and details of the invention are derived from the following description of an embodiment of the invention described in detail with reference to the drawings, which schematically show:

[0038] Figure 1 A schematic block diagram showing system components in one embodiment of the system of the present invention,

[0039] Figure 2 A graph showing different curves for indicating the output voltage or no-load voltage of a fuel cell to be tested, which can be obtained by controlling the operating parameters according to different stress factor modes in a test run,

[0040] Figure 3A A graph of a measurement signal of a sensor detecting a fuel cell parameter is shown, the course of which serves as a fingerprint pattern to indirectly infer a first type of degradation,

[0041] Figure 3B A graph of a measurement signal of a sensor detecting a fuel cell parameter is shown, the course of which serves as a fingerprint pattern to indirectly infer a second type of degradation,

[0042] Figure 3C A graph showing a measurement signal curve of a sensor detecting a fuel cell parameter, the course of which serves as a fingerprint pattern to indirectly infer a third type of degradation, and

[0043] Figure 4Flowchart showing an exemplary chain of causes leading to specific defects in a fuel cell structure. DETAILED DESCRIPTION

[0044] Figure 1 A block diagram schematically shows an embodiment of the structure of a system 100 for inducing and determining specific defects and / or damages of a PEM fuel cell 10. The system 100 includes, in particular, the various modules described below as system components.

[0045] The fuel cell 10 or fuel cell stack to be inspected or tested may be any model or type of PEM fuel cell, which is investigated within the scope of scientific research, defect analysis, product development or similar activities.

[0046] The test bench module 50 provides a test environment that allows the fuel cell 10 to be tested to be operated under laboratory conditions. This includes, in particular, a fuel gas test supply 51, for example, including a (not shown) hydrogen tank, a regulating valve and an interface connected to the anode part of the fuel cell 10. It also includes an oxidizing gas test supply 52, for example, including a (not shown) compressor for supplying air oxygen, a regulating valve and / or a speed regulator of the compressor, and an interface connected to the cathode part of the fuel cell 10. In addition, the fuel cell 10 is also connected to a test load 53, whose power consumption or demand can be adjusted and can be provided by a heat sink or an electric power consumer. The adjustable actuators of the fuel gas test supply 51 and the oxidizing gas test supply 52 and the circuit device of the test load 53, in particular the power electronics, are connected to a control module 55, through which the operating parameters of the test operation of the fuel cell 10 are controlled and adjusted by means of signals.

[0047] A plurality of general stress factor patterns are stored in the control module 55, which can be selected by the user in order to reproducibly achieve different stress and aging scenarios on the fuel cell 10 to be tested. In this case, during the test operation, the operating parameters are controlled and adjusted according to the selected stress factor pattern, such as in combination with the subsequent Figure 2 As explained.

[0048] The system 100 also includes a measurement module 20, which represents various types of measurement techniques. The measurement module 20 therefore includes at least one sensor 21 for detecting operating parameters of the fuel cell 10. In order to study the performance and the delivered or discharged fluid, a plurality of different types of sensors 21 are preferably provided, such as voltage sensors, current sensors, temperature sensors, pressure sensors for gas pressure, concentration sensors for hydrogen (H2) or hydrogen fluoride (HF) concentrations, or conductivity sensors for liquid conductivity.

[0049] In the illustrated embodiment, the system 100 also includes a signal generator 22, which is used as a measurement technique for impedance spectroscopy by applying an excitation signal (e.g., an AC signal with frequency modulation) to the electrodes of the fuel cell 10 and combining it with the voltage sensor 21 to detect the signal response obtained by interacting with the structural state of the fuel cell 10.

[0050] The measuring module 20 converts the measured values ​​measured by the sensor 21 into digital measuring signals, which can be subjected to further data processing for analysis. For this purpose, a comparison module 30 and a determination module 40 are used, which can be implemented as software tools of the method or subroutines of a computer program.

[0051] In the comparison module 30, a general reference pattern is stored, which contains characteristic variation curves of relevant operating parameters, which directly or indirectly characterize the typical behavior of the fuel cell 10 under a specific defect or damage. The comparison module 30 or, alternatively, the determination module 40 normalizes the signal curves of the measurement signal and the reference signal related to the same operating parameter measurement value to a common zero point and / or a common reference, so that even in the case of fuel cells 10 of different types and sizes, the common points of the absolute or qualitative variation curves have better and universal comparability. Based on the degree of consistency of the characteristic features selected as being relevant to the indirect fault inference in the characteristic variation curves, that is, based on the value of the common intersection of such common points (number of inflection points, absolute value, average value, etc.), the determination module 40 determines whether a specific defect has occurred. Here, the determination module 40 also finds out the diagnostic probability of the occurrence of a defect based on the intersection value. Alternatively or additionally, the determination module 40 finds out the degree of progression of a specific defect in the structure or performance of the fuel cell 10 or the damage caused thereby based on the value in the intersection.

[0052] Figure 2 Various superimposed stress factor patterns are shown for a test run of a fuel cell 10 to be tested. Specifically, the graph shows various changes in the electric field between the electrodes in the fuel cell 10 that are induced by an exemplary type of periodic control of operating parameters according to different stress factor patterns during the test run, which changes can be measured by means of an applied voltage.

[0053] Thus, for example, there are triangular modulations, rectangular wave modulations, triangular wave modulations with a constant potential level or triangular wave modulations with decreasing potential peaks which, based on empirical studies, lead to different, reproducible aging or damage rates of fuel cell structures in long-term tests.

[0054] Figure 3A , 3B 3C show graphs for an exemplary fingerprint pattern, which differs from the typical behavior or signal curve of a new or intact battery, taking into account predetermined changes in operating parameters in a test run. Figure 3A , 3B 3C exemplarily show various measurement signals related to relevant operating parameters, which are generated by the measurement values ​​measured by different types of sensors 21. These signals are related to certain defect modes of specific defects (such as membrane thinning or damage, or reduction of active catalyst material), and these failure modes will show characteristic deviations in behavior.

[0055] Figure 4 In order to understand the damage process of the fuel cell structure, an exemplary cause chain of a specific defect leading to membrane damage is shown.

[0056] Here, in the test operation, the level and holding time of the no-load voltage (OCV) or high output voltage (HV) periodically determined according to the stress factor pattern are triggered, for example by limiting the power consumption of the test load 53, when the fuel cell 10 is supplied with reaction gases by the fuel gas test supply device 51 and the oxidizing gas test supply device 52. The high voltage in the fuel cell 10 intensifies harmful electrochemical processes, such as the formation of hydrogen peroxide or free radical species that gradually corrode the polymer electrolyte membrane material. In further operation, the membrane becomes thinner, so that its integrity is threatened. Subsequently, small holes appear and eventually cracks, whereby the gas exchange between the anode and the cathode is no longer prevented. The gas exchange leads to local exothermic reactions (such as hot spots), which cause further indirect damage to the membrane and other structures (such as catalytic materials).

[0057] Depending on the different measuring techniques used by the measuring module 20, different stages of damage or specific defects (such as thinning of the membrane) can be detected in advance by suitable sensor devices. For example, potential damage to the membrane can be manifested by the release of hydrogen fluoride (HF) in the product water or, at a later stage, by the release of hydrogen (H2), which can be detected by suitable concentration measurements or conductivity measurements in the product water. Comparison of the fingerprint pattern of the corresponding measurement signal with a reference pattern containing characteristic values ​​and / or curves related to the HF concentration or the hydrogen concentration or indirectly the product water conductivity allows an automated determination of the defect state during the test run. At a later stage, the same measuring method can also be used for identification based on voltage loss.

[0058] The above explanations of the embodiments describe the present invention only within the scope of examples.

[0059] Reference numerals list

[0060] 10. Fuel Cells

[0061] 20 Measurement modules

[0062] 21 Sensors

[0063] 22 Signal Generator

[0064] 30 Comparison module

[0065] 40 Determine module

[0066] 50 test bench modules

[0067] 51 Fuel gas supply device

[0068] 52 Oxidizing gas supply device

[0069] 53 Test Load

[0070] 55 Control Module

[0071] 100 Systems

Claims

1. A system (100) for initiating and determining specific defects and / or damages of a PEM fuel cell (10), comprising: A measuring module (20) for measuring at least one operating parameter of the fuel cell (10) and outputting a fingerprint pattern including a time signal curve of the measurement signal, the measuring module comprising at least one sensor (21) for detecting at least one operating parameter of the fuel cell (10); A comparison module (30) is used to compare the signal curve of the measurement signal in the output fingerprint pattern with the signal curve of the reference signal in the reference pattern, wherein: Providing a plurality of reference modes in the comparison module (30), the reference modes comprising signal curves of reference signals characterizing different specific defects and / or damages; a determination module (40) for determining whether a specific defect and / or damage represented by a signal curve of a reference signal in a reference pattern used for the comparison has at least gradually appeared, wherein the determination module (40) is configured to make the determination based on a common intersection between the signal curves of the measurement signal of the fingerprint pattern and the reference signal of the reference pattern; It is characterized in that the system (100) further comprises: A test bench module (50) having a fuel gas test supply (51) for supplying fuel gas to the anode portion of the fuel cell (10) during a test operation, an oxidizing gas test supply (52) for supplying oxidizing gas to the cathode portion of the fuel cell (10) during a test operation, and an electrical test load (53) for drawing power from the fuel cell (10) during a test operation; A control module (55) is used to control the operating parameters of the fuel cell (10) test operation in the test bench module (50), Therein, at least one stress factor model is provided in the control module (55), in which operating parameter settings and / or critical variation curves for inducing defects and / or damage to the fuel cell (10) during the test operation are stored.

2. The system (100) according to claim 1, wherein: At least one stress factor pattern provided in the control module (55) includes a periodic variation curve of an operating parameter, so as to achieve a periodic variation of an output voltage of the fuel cell (10) having a specified voltage peak.

3. The system (100) according to claim 1 or 2, wherein: The comparison module (30) and / or the determination module (40) are configured to normalize the signal curves of both the measurement signal and the reference signal to a common zero point and / or a reference, and determine the common intersection based on the overlap of the width and / or amplitude frequency of the normalized signal curves.

4. The system (100) according to one of the preceding claims also has a diagnostic output module for outputting a diagnostic output signal, wherein the diagnostic output signal includes a percentage of the diagnosis probability of the specific defect and / or damage, which percentage is based on the intersection between the signal curves of the measurement signal and the reference signal.

5. The system (100) according to one of the preceding claims also has an editing module for editing a provided reference pattern, wherein the editing is based on a specific adjustment of the fuel cell (10), i.e., the signal curve of the reference signal in the reference pattern is matched to the signal curve of the measurement signal of the following fingerprint pattern, for which specific defects and / or damages characterized by the signal curve of the reference signal in the reference pattern have been determined to appear at least gradually.

6. The system (100) according to any of the preceding claims, wherein: The measuring module (20) also has a signal generator (22) for applying an excitation signal based on an AC voltage to the fuel cell (10), wherein the at least one sensor (21) detects a signal response based on the AC voltage, the signal response originating from the interaction between the excitation signal and the fuel cell (10).

7. The system (100) according to any of the preceding claims, wherein: At least one sensor (21) of the measuring module (20) is: a voltage sensor for detecting an output voltage of the fuel cell (10), Hydrogen sensor for detecting hydrogen concentration on the cathode side, Conductivity sensor for measuring product water conductivity, and / or A virtual sensor is simulated by means of a degradation model of the analysis software on the measuring module (20).

8. A method for inducing and determining specific defects and / or damages of a PEM fuel cell (10), comprising the following steps: Measuring at least one operating parameter of the fuel cell (10) by detecting at least one operating parameter of the fuel cell (10) by at least one sensor (21), and outputting a fingerprint pattern including a time signal curve of the measurement signal; By providing different reference patterns with signal curves of reference signals characterizing a plurality of specific defects and / or damages, the signal curve of the measured signal in the output fingerprint pattern is compared with the signal curve of the reference signal in the reference pattern; determining whether a specific defect and / or damage characterized by the signal curve of the reference signal in the reference pattern used for the comparison occurs at least gradually, wherein: The determination is performed based on a common intersection between signal curves of the measurement signal of the fingerprint pattern and the reference signal of the reference pattern; The method is characterized in that the method comprises the following steps: performing a test run on a test bench having a fuel gas test supply device (51) for supplying fuel gas to an anode portion of the fuel cell (10) during the test run, an oxidizing gas test supply device (52) for supplying oxidizing gas to a cathode portion of the fuel cell (10) during the test run, and an electrical test load (53) for drawing power from the fuel cell (10) during the test run; and According to at least one stress factor pattern, operating parameters of a test operation of the fuel cell (10) in the test bench (50) are controlled, wherein settings and / or time curves of operating parameters for inducing defects and / or damage to the fuel cell (10) during the test operation are stored in the stress factor pattern.

9. The method (100) according to claim 8, wherein: At least one stress factor pattern includes a periodic variation curve of an operating parameter, which is used to achieve a periodic variation of an output voltage of the fuel cell (10) having a specified voltage peak.

10. The method according to claim 8 or 9, wherein: The comparing and / or determining step also includes the following intermediate steps: normalizing the signal curves of both the measurement signal and the reference signal to a common zero point and / or reference; and The common intersection is determined based on the overlap of the amplitude and / or amplitude frequency of the normalized signal curves.

11. The method according to any one of claims 8 to 10, further comprising the following steps: A diagnostic output signal is outputted, the diagnostic output signal comprising a diagnostic probability percentage for the specific defect and / or damage, the percentage being based on the intersection between the normalized signal curves of both the measurement signal and the reference signal.

12. The method according to any one of claims 8 to 11, further comprising the following steps: Editing a provided reference pattern, the editing being based on a specific adjustment of the fuel cell (10), i.e. matching the signal curve of a reference signal in the reference pattern to the signal curve of a measurement signal of a fingerprint pattern for which specific defects and / or damages characterized by the at least gradual appearance of the signal curve of the reference signal in the reference pattern have been determined.

13. The method according to any one of claims 8 to 12, wherein: The measuring step also has the following intermediate steps: Using a signal generator (22) to apply an AC voltage-based excitation signal to the fuel cell (10); and At least one sensor (21) is used to detect an AC voltage-based signal response resulting from an interaction between the excitation signal and the fuel cell (10).

14. The method according to any one of claims 8 to 13, wherein: The measuring step also has at least one of the following intermediate steps: detecting the output voltage of the fuel cell (10) using a voltage sensor, A hydrogen sensor is used to detect the hydrogen concentration on the cathode side. Use a conductivity sensor to measure the conductivity of the product water, and / or The simulation is performed using a virtual sensor with the aid of a degradation model of the analysis software on the measurement module (20).

15. A computer program comprising instructions which, when the computer program is run by a computer, cause the computer to execute the steps of the method according to any one of claims 8 to 14.

Images