WO2020082102A1

WO2020082102A1 - Method for providing an indicator

Info

Publication number: WO2020082102A1
Application number: PCT/AT2019/060354
Authority: WO
Inventors: Stefan POFAHL; Lukas WIELANDNER
Original assignee: Avl List Gmbh
Priority date: 2018-10-25
Filing date: 2019-10-25
Publication date: 2020-04-30
Also published as: DE112019005344A5; AT521864A2

Abstract

The present invention relates to a method (100) for providing an indicator (200) which is specific to at least one parameter (210) of a system (1) in the form of at least one electrochemical cell (1), wherein the following steps are carried out: providing at least one overall spectrum (230) which is specific in each case to a system response (214) to an excitation (212) of the system (1) in the case of a varied parameter (210) of the system (1), generating an indicator (200), wherein the indicator (200) is selectively determined taking into account the varied parameter (210) and the at least one overall spectrum (230), providing the generated indicator (200) on the basis of a quality criterion in comparison with the varied parameter (210).

Description

Procedure for providing an indicator

The present invention relates to a method for providing an indicator. The invention further relates to a device for providing an indicator.

It is known from the prior art that operating states at

electrochemical cells are monitored by means of an excitation. The effects of the excitation can be recorded for this monitoring, and certain characteristics of this effect can serve as an indicator of the operating state. For example, the excitation was carried out with a sinusoidal electrical signal which is impressed on the cell at a fixed frequency. The response signal can then be measured and evaluated at the same frequency or its harmonic frequency. In other words, only a few become

Frequencies of the response signal used as the basis for determining the indicator.

However, this procedure is frequently still disadvantageous with regard to the specificity of the indicator for the operating state and / or with regard to the signal strength and / or signal robustness.

Methods for monitoring systems are known from publications DE 10 2014 224 290 A1 and US 8 034 498 B2.

The object of the present invention is that described above

To take account of the problem at least in part. In particular, it is the object of the present invention to provide an improved indicator for monitoring the parameter.

The above object is solved by the claims. In particular, the above object is achieved by a method having the features of claim 1 and by an apparatus having the features of claim 11. Further features and details of the invention result from the respective subclaims, the description and the drawings. Features and details that are described in connection with the method according to the invention also apply, of course, in connection with the Apparatus according to the invention, and vice versa, so that with respect to the disclosure of the individual aspects of the invention, reference can always be made to one another.

The object is achieved in particular by a method for providing an indicator which is specific for at least one parameter of a system and / or is used for monitoring the parameter. The system can be an electrochemical system and / or a system in the form of at least one electrochemical cell and preferably at least one fuel cell.

Such an indicator can be used to monitor the parameter, preferably by evaluating overall harmonic distortion (also: total harmony distortion, or THD for short). The parameter is, for example, an operating state or a process in the system. The parameter can vary, i.e. change during the operation of the system. The change can be time-dependent (such as aging or the like of the system) or be caused by other influences (such as a temperature or the like of the system).

For monitoring purposes and preferably using a THD method used here, an electrical signal (an excitation signal such as a

AC) imprinted on the system and a resulting one

Response signal (such as a resonance voltage) are recorded as a system response in the system. Characteristics of the response signal can be used as an indicator for the parameter. For example, a sinusoidal alternating current in a limited frequency spectrum or a non-sinusoidal excitation, for example in the form of a sawtooth-shaped electrical signal, is used for the excitation. Signals present in the system, such as switching a valve or the like, can also be used as excitation. It is also possible that distorted sinusoidal or non-sinusoidal signals are used as excitation. The complexity of the resulting frequency spectrum of the

Response signal increased significantly, but it can also be improved

Signal strength and / or signal robustness can be achieved. However, due to the increased complexity, the evaluation of such a response signal is conventionally problematic. According to the invention, an indicator can be provided which can possibly also enable the use of such complex response signals. Within the scope of the method according to the invention, it is possible for the following steps to provide the indicator to be carried out, preferably in succession in the order specified or in any order, individual steps also being able to be carried out repeatedly:

Providing at least one overall spectrum, which is specific for a system response to an excitation of the system with a varied parameter of the system,

Generating an indicator, the indicator being determined taking into account the varied parameter and the at least one overall spectrum, in particular selectively,

Provision of the generated indicator based on a quality criterion in comparison with the varied parameter.

This has the advantage that the entire spectrum is taken into account when generating the indicator, and not just a few frequencies. Even a complex system response, such as a non-sinusoidal one

In this way, stimulation can be taken into account.

In addition, more features in the system response can serve as an indicator than is traditionally the case. The indicator is advantageously determined selectively, preferably selectively with respect to the

Overall spectrum. In particular, this means that not all or certain frequencies of the entire spectrum are automatically used for the indicator, but rather selectively the frequencies of the parameter that are significant for the parameter

Total spectrum can be selected for the indicator. This can be done, for example, by an iterative optimization process, in which the frequencies of the entire spectrum are examined with regard to their specificity for the varied parameter. In contrast to conventional methods, the frequencies are not specified as an indicator from the outset, but are determined taking into account the entire spectrum. In this way, in principle all (or at least the predominant number) of the frequencies of the entire spectrum can potentially serve as an indicator.

The quality criterion is advantageously a suitability of the indicator and / or of frequencies of the entire spectrum, a reference to a value of the Deliver parameters. Thus, the quality criterion z. B. a monotone

Behavior of the frequencies (for example the sum of their amplitudes) via the monotonically varied parameter and / or a proportionality of the frequencies or the sum in relation to the varied parameter or the like. In other words, the more the quality criterion applies, the less the deviation of the monotony and / or the proportionality of the frequencies from the varied parameter. For this assessment, such as monotonous behavior and / or proportionality, e.g. B. the frequencies are recorded for different variations of the parameter, and in particular the sum of the amplitudes of the respective frequencies are formed for each of these acquisitions.

The system response can e.g. B. can be determined by measuring a response signal as an electrical signal in the system during the excitation. The suggestion is e.g. B. applying an electrical voltage as an excitation signal to the system. The total spectrum is, for example, the entire frequency spectrum of the response signal, which is determined, for example, by means of a (digital) Fourier transformation from the response signal. A frequency range of the entire spectrum can be in the range from 0.1 Flz to 10 kHz.

Advantageously, it can be provided within the scope of the invention that the provision of the at least one entire spectrum is carried out by performing a frequency analysis such as a Fourier analysis on an electrical signal measured on the system by a data processing system or the like. The measured signal can be advantageous for this

Design the response signal, which can be measured in the excitation on the system. In this advantageous embodiment, the response signal can be the time profile of an electrical voltage or a current at connections of the system. In this advantageous embodiment, the response signal can also be determined as a system response by known methods, for example as a step response when the system is excited by a step function. The excitation of the system can further z. B. by applying an excitation signal - such as an electrical voltage or a sinusoidal alternating current or some other influence on the system. If the total spectrum is determined from the response signal, it is advantageously specific for the system response to the excitation of the system and is therefore suitable for characterizing the system. It can also be a particular criterion in the provision of the overall spectrum that the broadest possible spectrum is determined as the overall spectrum in order to increase the information content for characterizing the system.

The respective overall spectra can advantageously for the varied

System specific parameters. This means in particular that the overall spectra for different variations (e.g. values) of the

Parameters are determined. In this advantageous embodiment, a change in the overall spectrum can occur with the change in the parameter

correlate. This is due to the fact that the entire spectrum on the

System response based, and is therefore suitable to characterize the system. To use this effect, the total spectra for

different variations of the parameters are determined, for example at different times. The parameter is, for example, an operating state or a process in the system which changes (for example over time). A simple example of the parameter is the age of the system. In this case, the parameter does not have to be actively set to be varied, but then changes automatically over time. If the parameter in this advantageous embodiment thus varies during the operation of the system, the overall spectra determined for the different variations of the parameters also change.

In order to make a possibly complex correlation between the overall spectrum and parameters easier to evaluate, an indicator can be used in particular according to the invention. The overall spectra are for the parameter z. B. created in the form of frequency spectra (such as transfer functions from the impulse or step response), in particular for different variations of the parameters, so z. B. at different times. The respective

Total spectrum can be in a frequency range from 0.1 Hz to 10 kHz,

preferably 1 Hz to 1 kHz, preferably 10 Hz to 100 Hz. In this advantageous embodiment, the parameters can be varied in such a way that the entire spectrum is determined at fixed time intervals, if necessary automatically by an electrical measuring device. For each of these investigations, the indicator can be generated and finally provided

preferably done by only some of the frequencies of the

The entire spectrum is selected - that is, selected. The provision of the respective overall spectrum and the generation of the indicator can

in particular, iteratively interlocked: In this advantageous embodiment, this is then repeated one after the other in time

Provided entire spectrum, and then the frequencies of the previously provided total spectrum are selected to generate the indicator. Which of the frequencies are selected in each of these iterations can preferably be determined randomly (for example by a random generator) and / or can be specified by an optimization algorithm. The optimization algorithm optimizes the selection of the frequencies, for example, which is the largest

Have specificity for the parameter. In the iterative used for this

In this advantageous embodiment, the optimization process can, if necessary, manually enter the specificity as a quality criterion. With this advantageous embodiment, the optimization algorithm can therefore be an iterative numerical one

Perform procedures for optimization problems. Such methods are, for example, in Göllmann L. et al. (2017) "Iterative numerical methods for optimization problems", in: "Mathematics for engineers", Springer Vieweg, Berlin, Fleidelberg disclosed.

Finally, in the last iteration step, the frequencies finally selected can preferably serve to provide the generated indicator. The indicator is, for example, the specification of which of the frequencies are selected, and thus comprises a (digital) list of frequencies from the entire spectrum.

The indicator can advantageously be determined, taking into account the varied parameter and the at least one overall spectrum, in particular selectively, that only specific frequencies are selected from the overall spectra determined (at fixed time intervals) for different variations of the parameters. With this advantageous embodiment, it is thus possible that the system and the parameters do not have to be characterized on the basis of the entire overall spectrum, but only on the basis of the indicator - that is to say a few frequencies. This has the advantage of being easier and faster

To be able to use data processing to evaluate the parameter based on the indicator. The number of frequencies used for this lies e.g. B. in the range of 1% up to 50%, preferably 5% to 25% of the available frequencies (sampling points) of the entire spectrum (if the entire spectrum is available with discrete frequencies).

The selective determination of the indicator from the entire spectrum can take place in particular under the criterion that only those frequencies are selected for the indicator that can describe the parameter with particularly high specificity. With this advantageous embodiment, it is thus possible for the generated indicator to be made available on the basis of the quality criterion in comparison with the varied parameter in that only those

Frequencies are selected which also show the variation of the parameter. In this advantageous embodiment, a comparison with the varied parameter z. B. in that the course of the parameter is compared in terms of value with the course of the selected frequencies. The

Quality criterion can e.g. B. in the case of aging, the parameter can be defined by selecting only the frequencies at which the amplitude also increases (or decreases) over time (as with the parameter). Generally speaking, the quality criterion can preferably match the course of the parameter with the course of the amplitudes of the selected ones

Frequency. The match can e.g. B. be evaluated by a threshold value, so that, for example, with at least 80% agreement, the quality criterion is considered fulfilled and thus the frequency is selected for the indicator. The indicator with the correspondingly selected frequencies (i.e. a frequency combination) can thus be used, for example, for the aging process

electrochemical cell. In the operation of the electrochemical cell, it is then not necessary to evaluate the entire entire spectrum in order to determine the aging, but only the indicator, ie the limited number of frequencies. In this way, different indicators can preferably also be determined for different parameters (aging, temperature, or the like).

In the context of the invention, a stochastic optimization method can in particular be understood to be a method which uses random variables in order to find the best solution. With this advantageous embodiment, such algorithms can also use mathematical models, such as the evolutionaries Algorithms. In the following, this can also be understood to mean the use of an “evolution strategy” or genetic algorithms. Such methods are disclosed for. B. in Schröder D., Buss M. (2017) "Stochastic Optimization Methods" in:

"Intelligent processes", Springer Vieweg, Berlin, Heidelberg.

It can advantageously be provided in the invention that the indicator is determined from frequencies of the at least one overall spectrum, which are changed dynamically, and in particular randomly and / or iteratively, during generation. In this way, different frequencies of the

Total spectrum with regard to their specificity and / or suitability for the indicator. The suitability corresponds to that, for example

Quality criterion.

It is also conceivable that the following steps are provided before generation:

Initial selection of selection frequencies from frequencies of the at least one overall spectrum, in particular on the basis of a selection criterion,

Providing an initially selected frequency combination from the

Selection frequencies, especially random, and the following steps are carried out iteratively when generating:

Provision of several frequency combinations from the selection frequencies, for which purpose the respectively combined frequencies are selected partly from the previously selected frequency combination and partly deviating from it and in particular randomly,

Carrying out a selection of at least one of the frequency combinations on the basis of the quality criterion.

This has the advantage that different frequency combinations can be considered for the indicator. The frequency combinations can be a list of the different frequencies, the amplitudes of which are evaluated for the indicator or for monitoring the parameter. The initial selection can serve to reduce the initial frequency components of the entire spectrum to those frequencies which are above one of their own noise Detection of the measuring device used and / or additionally show monotonous behavior via the monotonically varying parameters. These frequency components of this reduced spectrum can then be combined randomly in order to obtain the initially selected frequency combination. It can also be provided that the amplitudes of the frequencies of this initially selected frequency combination are then added up for each spectrum of a parameter point. The background to this is that an overall spectrum can have been recorded for each variation of the parameter (ie each parameter point). These sums now behave proportionally or indirectly proportional to the

Parameter points, a quality criterion may be considered fulfilled and / or quality characteristics of this frequency combination can be buffered. This frequency combination can then be used as a starting point (or according to an evolution strategy as a "parent"). These parents are then possibly reproduced in order to provide the multiple frequency combinations from the selection frequencies in a first iteration when generating. The parents can pass their genes (i.e. the frequencies) at random to a number of predefined children, so that the combined frequencies of the children are partially selected from the previously selected frequency combination (of the parents). In order not to get stuck in any local optimum, the principle of mutation can also be used. Each frequency in the children's frequency spectrum is additionally pre-defined

Probability taken into account or not taken into account, even if it was inherited or not inherited. In this way, the combined frequencies of the frequency combinations may differ from those previously selected

Frequency combinations and especially randomly selected. The quality characteristic can now be determined and / or for each of these children

be cached. These new quality features can be compared with the quality feature of the parents in order to generate new parents from the children with a better quality feature with regard to the quality criterion. These processes can be repeated iteratively during generation, for example for a predefined number of iterations (generations) or until a convergence criterion is met. The best frequency combination (with regard to the quality criterion) can then be provided for the indicator. The advantage here can be that even previously unused signal components in the Development of the indicator can be taken into account, and thus a particularly robust indicator can be provided.

Advantageously, it may be possible to determine a quality characteristic of respective frequency combinations in order to assess the quality criterion. This quality feature depends, for example, on a signal strength of the amplitudes of the frequencies of the respective frequency combination and / or on a deviation of the frequency combination from the varying parameters with respect to one

Monotony and / or proportionality and / or sensitivity.

The respective frequency combination is preferably designed as a linear combination and / or as a weighted summation of the amplitudes of the combined frequencies of the respective frequency combination. An individual signal on a frequency can also be formed as a quotient. For example, a linear combination of impedances at different frequencies can be used to determine an indicator. The quotient can be formed from quantities of the same type, as is the case for the distortion factor (THD), or from quantities of different types, as is the case with impedance or power. If one speaks in the following of the summing up of the amplitudes, then - for reasons of simplification - is to be understood as the linear combination of amplitudes or quotients of measured variables at different frequencies.

It may also be possible that the provision of the at least one overall spectrum is carried out by acquiring different overall spectra and associated parameter points for different values of the parameter. For this purpose, the parameter can be varied in the operation of the system for test measurements, e.g. B. in the event of aging as a parameter, the system can be operated for a longer period of time, and repeated measurements can be carried out during this operation. Each of these measurements is then one

Assigned parameter point at the time of measurement, e.g. B. a time and / or value for aging. In other words, a course of measured values of the measurements can oppose a course of parameter points. The

Measurements themselves are e.g. B. each measurement of a response signal, so that the total spectra of the response signals are also assigned to the parameter points. Furthermore, the following steps can optionally be carried out before generation:

Performing at least one combination of a random selection from the selection frequencies around the initially selected frequency combination

to provide

Summing up the amplitudes of this selection from the selection frequencies for each of the total spectra, in particular total spectra for

different parameter points,

Comparing the summed amplitudes with the parameter points on the basis of the quality criterion, e.g. B. with regard to a deviation and / or

Monotony to the parameter points,

Determining a quality characteristic of the initially selected

Frequency combination on the basis of the comparison, for example as the value of the respective deviation, wherein the generation of the selection can comprise the following steps:

Compare the frequency combinations provided with the

Parameter points based on the quality criterion, e.g. B. with regard to a deviation and / or monotony to the parameter points, - determining a respective quality characteristic on the basis of the comparison, for example as a value of the respective deviation,

Select one of the frequency combinations as selected

Frequency combination based on a comparison of the quality characteristics with the quality characteristic of the previously selected frequency combination, preferably if one of the last quality characteristics determined is higher than the quality characteristic of the frequency combination previously selected (in the previous iteration), the selected frequency combination possibly after the last iteration

Providing the generated indicator can be used. This has the The advantage that an indicator specific to the parameter can be determined very reliably.

It can be advantageous if, in the context of the invention, the selection frequencies are formed in accordance with the selection criterion from frequencies which, in particular as the quality criterion, over a noise component of the

Total spectrum and / or its monotony with the monotony of

Correlated parameters. In this way, a specificity of the parameter can be examined.

Furthermore, it is conceivable that the generation comprises several optimization steps, in each of which the indicator is iteratively adapted and evaluated on the basis of different frequencies of the entire spectrum and selected for the subsequent optimization step on the basis of the evaluation. The evaluation is in particular an evaluation in which a course of the overall spectra is compared with a course of the parameter, preferably using the

Quality criterion. This enables a variety of potential

Frequencies for the indicator to select the most promising.

It can advantageously be provided within the scope of the invention that the indicator is at least partially stochastically determined, preferably by means of a locally stochastic optimization method, preferably by means of a

Evolution strategy and / or a genetic algorithm is carried out.

This makes it possible to add such frequencies to the entire spectrum

take into account which would be excluded according to conventional procedures.

Another advantage can be achieved within the scope of the invention if the

The overall spectrum is taken into account by taking a predominant part of the total spectrum for the indicator and / or using it for generation. The specificity of the indicator can be increased by using several frequencies of the entire spectrum.

It can advantageously be provided in the invention that the following step is provided: Detecting the system responses by performing the particularly non-sinusoidal excitation repeatedly while varying the

Parameters, so the parameter has different parameter values

(Parameter points), the variation parameter preferably being taken into account by comparing a course of the overall spectra from the recorded system responses with a course of the associated parameter values (parameter points). A particularly robust indicator can be determined in this way.

A further advantage can be achieved within the scope of the invention if the generated indicator is provided in order to monitor the parameter in the system or in a further system on the basis of the indicator, the parameter preferably being an operating state of the system, in particular a temperature, or a process of the system, in particular aging, is carried out. The indicator for evaluating the parameter can be designed using the system response, in particular as an electrical signal detected by the system during monitoring. In this way, the indicator can be used to monitor and / or determine the parameter in a system, without the need to carry out complex other measurements of the parameter.

It is preferably sufficient for the monitoring that an electrical signal is detected in the system for the indicator.

The invention also relates to a device for providing an indicator. The device can e.g. B. as a data processing system or as a computer program, in particular Com computer program product, or as an electronic device. Furthermore, the device can also be designed as a computer-readable medium, such as a data carrier, with the computer program.

It may be provided here that the indicator is specific for at least one parameter of a system, in particular in the form of at least one electrochemical cell. The device according to the invention can the following modules, for. B. in the form of software and / or hardware modules, have: a provisioning module for providing at least one

Total spectrum, which is specific for a system response to an excitation of the system with a varied parameter of the system, an indicator module for generating an indicator, which is designed to selectively determine the indicator taking into account the varied parameter and the at least one overall spectrum, a result module to provide the generated indicator based on a quality criterion in comparison with the varied parameter.

The device according to the invention thus brings with it the same advantages as have been described in detail with reference to a method according to the invention. In addition, the device can be suitable for carrying out a method according to the invention.

According to a further possibility it can be provided that the device has at least one processing means which is designed to cause the device to carry out the steps of a method according to the invention. The processing agent may e.g. B. a

Act computer program or electronics or the like. To the

The processing means (as a computer program) can, for example, cause the steps to be carried out. B. loaded and executed by a processor of the device.

Further advantages, features and details of the invention emerge from the following description, in which reference is made to the drawings

Embodiments of the invention are described in detail. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. Show it:

Figure 1 is a schematic representation for the visualization of a

method according to the invention,

FIG. 2 shows a schematic illustration of a device according to the invention,

Figure 3 is a schematic representation for the visualization of a

inventive method. In the following figures, the same reference numerals are used for the same technical features of different exemplary embodiments.

A system 1 for visualizing a method 100 according to the invention is shown schematically in FIG. It is shown here that first an excitation 212 can be carried out in the system 1 in order to determine a system response 214. A total spectrum 230 can then be calculated from this system response 214, such as an electrical signal. In addition, a response signal during the excitation 212 in the system 1 can be determined by a measuring device and, for example, converted into a digital signal by an analog-digital converter. The entire spectrum 230 can then be formed from this digital signal by means of a digital Fourier transformation, such as, for example, a Fast Fourier transformation. Furthermore, it is possible in a further step that

Selection frequencies 232 can be selected from the total spectrum 230, which thus correspond to a subset of the total spectrum 230. These

Selection frequencies 232 need not necessarily be adjacent frequencies, so that a list of different frequencies from the entire spectrum 230 can also be considered as selection frequencies 232. An indicator 200 can then be determined on the basis of different frequency combinations 234, taking into account the varied parameter 210 of the system 1 and the overall spectrum 230. For this purpose, parameter 210 is varied in order to determine different system responses 214 for different suggestions 212.

To provide the indicator 200, a device 10 according to the invention can be used, for example. This is shown schematically in FIG. 2 and, in addition to a preparation module 20, also includes an indicator module 30 and a result module 40. A processing means 11 is also optionally provided.

A method 100 according to the invention for providing an indicator 200 is schematically visualized in FIG. 3, the indicator 200 being specific for at least one parameter 210 of a system 1 in the form of at least one electrochemical cell 1. According to a first method step 101, at least one total spectrum 230 is prepared, each for one

System response 214 of a suggestion 212 of system 1 for a varied one

System 210 parameter 210 is specific. According to a second Method step 102 generates an indicator 200, the indicator 200 being selectively determined taking into account the varied parameter 210 and the at least one overall spectrum 230. As a third method step 103, the generated indicator 200 is made available on the basis of a quality criterion in comparison with the varied parameter 210.

The above explanation of the embodiments describes the present invention exclusively in the context of examples. Of course, individual features of the embodiments, if technically meaningful, are free

can be combined with one another without departing from the scope of the present invention.

Reference list

I system, cell

10 device

I I processing equipment

20 Provisioning module

30 indicator module 40 result module

100 procedures

101 first process step

102 second process step

103 third process step

200 indicator

210 parameters

212 suggestion

214 system response

230 total spectrum

232 selection frequencies 234 frequency combination

Claims

1. A method (100) for providing an indicator (200) which is specific for at least one parameter (210) of a system (1) in the form of at least one electrochemical cell (1),

performing the following steps:

- Providing at least one overall spectrum (230), which is specific for a system response (214) of an excitation (212) of the system (1) with a varied parameter (210) of the system (1),

- Generating an indicator (200), the indicator (200) being selectively determined taking into account the varied parameter (210) and the at least one overall spectrum (230),

- Providing the generated indicator (200) based on a quality criterion in comparison with the varied parameter (210).

2. The method (100) according to claim 1,

characterized in that

the indicator (200) is determined from frequencies of the at least one overall spectrum (230), which are changed dynamically, and in particular randomly and / or iteratively, during generation.

3. The method (100) according to claim 1 or 2,

characterized in that

The following steps are provided before generation:

- initial selection of selection frequencies (232) from frequencies of the at least one overall spectrum (230), in particular on the basis of a selection criterion,

- Providing an initially selected frequency combination (234) from the selection frequencies (232), in particular randomly,

and the following steps are carried out iteratively during generation:

Provision of a plurality of frequency combinations (234) from the selection frequencies (232), the frequencies combined in each case being selected partly from the previously selected frequency combination (234) and partly deviating therefrom and in particular at random, - Carrying out a selection of at least one of the frequency combinations (234) on the basis of the quality criterion.

4. The method (100) according to claim 3,

characterized in that

the provision of the at least one overall spectrum (230) is carried out by acquiring different overall spectra (230) and respectively associated parameter points for different values of the parameter (210), the following steps being carried out before generation:

- performing at least one combination of a random selection from the selection frequencies (232) to the initially selected one

Provide frequency combination (234),

- Sum up the amplitudes of this selection from the

Selection frequencies (232) for each of the total spectra (230),

- comparing the summed amplitudes with the parameter points on the basis of the quality criterion,

- Determine a quality characteristic of the initially selected

Frequency combination (234) based on the comparison,

where the generation of the selection comprises the following steps:

Comparing the frequency combinations (234) provided with the parameter points on the basis of the quality criterion,

- Determining a respective quality characteristic based on the comparison,

- Select one of the frequency combinations (234) as selected

Frequency combination (234) based on a comparison of the

Quality features with the quality feature of the previously selected frequency combination (234),

wherein the selected frequency combination (234) is used after the last iteration to provide the generated indicator (200).

5. The method (100) according to claim 3 or 4,

characterized in that

the selection frequencies (232) according to the selection criterion from such Frequencies are formed which, in particular as the quality criterion, lie above a noise component of the overall spectrum (230) and / or whose monotony correlates with the monotony of the parameter (210).

6. The method (100) according to any one of the preceding claims,

characterized in that

the generation comprises several optimization steps, in each of which the indicator (200) is iteratively adapted and evaluated on the basis of different frequencies of the overall spectrum (230) and selected for the subsequent optimization step on the basis of the evaluation.

7. The method (100) according to one of the preceding claims,

characterized in that

the indicator (200) is determined at least partially stochastically, preferably using a locally stochastic optimization method, preferably using an evolution strategy and / or a genetic algorithm.

8. The method (100) according to any one of the preceding claims,

characterized in that

the total spectrum (230) is taken into account by taking a predominant part of the total spectrum (230) into account for the indicator (200) and / or using it for generation.

9. The method (100) according to any one of the preceding claims,

characterized in that

the following step is provided:

Detecting the system responses (214) by performing the particularly non-sinusoidal excitation (212) repeatedly while varying the parameter (210) so that the parameter (210) assumes different parameter values,

the varied parameter (210) is taken into account by comparing a course of the overall spectra (230) from the recorded system responses (214) with a course of the associated parameter values.

10. The method (100) according to any one of the preceding claims,

characterized in that

the generated indicator (200) is provided in order to use the indicator (200) to monitor the parameter (210) in the system (1) or in another system (1), the parameter (210) being an operating state of the system ( 1), in particular a temperature, or as a process of the system (1), in particular aging, the indicator (200) for evaluating the parameter (210) on the basis of the system response (214), in particular as a system ( 1) electrical signal detected during monitoring is executed.

11. Device (10) for providing an indicator (200) which is specific for at least one parameter (210) of a system (1) in the form of at least one electrochemical cell (1),

showing:

a supply module (20) for providing at least one overall spectrum (230), which is specific for a system response (214) of an excitation (212) of the system (1) with a varied parameter (210) of the system (1),

an indicator module (30) for generating an indicator (200), which is designed to selectively determine the indicator (200) taking into account the varied parameter (210) and the at least one overall spectrum (230),

- A result module (40) for providing the generated indicator (200) based on a quality criterion in comparison with the varied parameter (210).

12. The device (10) according to claim 11,

characterized in that

the device (10) has at least one processing means (11) which is designed to cause the device (10) to carry out the steps of a method according to one of claims 1 to 10.