WO2017182497A1

WO2017182497A1 - Method and system for evaluating an electrochemical storage unit

Info

Publication number: WO2017182497A1
Application number: PCT/EP2017/059242
Authority: WO
Inventors: Alexander Kohs
Original assignee: CTC cartech company GmbH
Priority date: 2016-04-22
Filing date: 2017-04-19
Publication date: 2017-10-26
Also published as: EP3414582A1; DE102016107528A1

Abstract

The invention relates to a system and a method for evaluating a condition and/or a value (40) of an electrochemical storage unit (10), which is used in at least one storage-specific application (58). According to the invention, at least one parameter (30) of the ageing condition (32) of the storage unit (10) is detected at a first time (t1); the detected parameters (30) are aligned with a battery model (13) to deduce ageing factors (42), wherein the battery model (13) comprises an electrochemical model (14) and/or an empirical model (16); at least one electrical load profile (62) of one or more storage units (10) that is characteristic of the storage-specific application (58) is detected during operation in the application (58); the detected load profile (62) for the application (58) is weighted in order to analyse the mutual dependencies of the determinable parameters (30) of the storage unit (10); and the condition of the storage unit (10) for the application (58) is forecast based on the ageing factors (42) for a future time (t2), which ageing factors (42) are correlated with an operation (10) in the storage-specific application (58).

Description

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Description title

Method and system for evaluating an electrochemical storage unit Prior art

The invention relates to a method for evaluating a state, in particular an aging state and / or a value, of an electrochemical storage unit used in at least one memory-specific application and a system for carrying out such a method.

It is known that electrochemical storage units, such as lithium-ion batteries, as used today in the vehicle sector, are subject to aging behavior, which depends very much on the chemical-physical structure of the storage unit and the use profile of the storage unit. There are also stochastic processes in the chemical system of the storage unit, which depend on the specific individual case and influence the aging behavior of the storage unit. Not directly measurable battery state variables, such as the state of charge or the internal resistance, significantly affect the battery behavior and are therefore important parameters for a charge control and a discharge monitoring. A certain state of charge is also useful information for the user. So this can adjust its user behavior to the state of charge and extend in this way the life of the storage unit.

Increasingly, used batteries which have been used, for example, in a vehicle are also supplied to a different use after a minimum running time in the vehicle, for example in a stationary storage system. In order to estimate a remaining service life or a residual value of such a used storage unit, knowledge of the state, in particular of the state of aging and / or of a value, of the battery is of great importance. Disclosure of the invention

The object of the invention is to provide a method which allows the evaluation of a state, in particular an aging state and / or a value, of an electrochemical storage unit for at least one memory-specific application.

Another object is to provide a system for carrying out such a method.

The objects are achieved by the features of the independent claims. Favorable embodiments and advantages of the invention will become apparent from the other claims, the description and the drawings.

According to a first aspect of the invention, a method is proposed for evaluating a state, in particular an aging state and / or a value, of an electrochemical storage unit which is used in at least one memory-specific application. The method comprises (i) detecting at least one parameter of the aging state of the electrochemical storage unit at a first time; and (ii) aligning the detected parameters with a battery model of the electrochemical storage unit to derive aging factors, the battery model comprising an electrochemical model and / or an empirical model. The method further comprises (iii) detecting at least one electrical load profile of one or more electrochemical storage devices characteristic of the memory-specific application when operating in the memory-specific application; (iv) weighting the detected load profile for the specific application to analyze the interdependencies of the determinable parameters of the electrochemical storage unit; and (v) predicting the state of the storage-specific electrochemical storage unit based on the aging factors for a future time, which aging factors are correlated with operation of the electrochemical storage unit in the storage-specific application. The method according to the invention serves to evaluate a state, which is referred to below as "state of battery" or SOB and characterizes a general performance of the electrochemical storage unit, and in particular includes an aging state, which is also known as "state of health" or SOH , Which aging condition is still acceptable for which application may depend on the specific application. For example, a battery that only has 80% SOB in the automotive sector already lead to a retirement.

The method may serve as an alternative or in addition to the evaluation of a state which in particular identifies a value of the electrochemical storage unit, which is referred to below as "state of value" or SOV specific application n, while the state SOV (n) denotes the value of the electrochemical storage unit for a specific application of n applications, in particular a residual value of the electrochemical storage unit The SOV also serves to decide in which application the batteries are new Use have a maximum residual value.

A specific application is to be understood as an application for which the electrochemical storage unit is designed, for example as a traction battery for driving a vehicle, as a hybrid battery for driving a hybrid vehicle with at least a second drive source for the vehicle, as a stationary battery for supplying stationary consumers. Typically, the requirements for the electrochemical storage unit in various applications differ significantly, which goes into the design of the electrochemical storage unit. Use of the electrochemical storage unit in an application that is not specific to the electrochemical storage unit, ie, not provided, may be associated with performance degradation, and in particular loss of life, to destruction of the battery. The method according to the invention is based on several steps. In a first step, a battery model is developed, for example with the help of statistically planned aging tests in the laboratory. The model describes the aging of an electrochemical storage unit depending on the battery condition and external aging factors by operating the electrochemical storage unit in its specific application. In a second step, at least one test stand is connected to a central server with a database on which the battery model runs centrally. The database can advantageously be designed as a self-learning database. Measured values generated by the test bench from an electrochemical storage unit are loaded onto the server. The battery model is adapted by processing the measured values, for example by generating corresponding data in a self-learning database. In a third step, in this way with respect to the adapted battery model, a lifetime of the storage unit in a specific application can be predicted. Thus, in the first step, the battery model can be created with high accuracy, in which a balance of the desired accuracy against the time required is taken. By contrast, in the second step, the current aging state or value of the storage unit can be determined relatively quickly, for example in a rapid test. In the third step, the prognosis for further aging can then be used to make a long-term prediction about the development of the further aging state or the development of value. In this way, a reliable aging model of the electrochemical storage unit for operation in a specific application can be derived.

With the aid of the electrochemical model, battery parameters are determined by the method according to the invention. From the change of these parameters an aging state SOB is determined. The effects of external aging factors on these parameters are modeled by the empirical model. The SOB can then be represented as a function of time. An empirical-electrochemical model of the memory unit has the advantages that it has a relation to physics, is transferable to different battery types, is statistically verified, includes orthogonality of the parameters and requires little testing effort through statistical experimental design. Parameters of an aging state of the electrochemical storage unit may be, for example, an ohmic resistance, or an electrical residual capacity. Measurement data of a voltage profile in the case of a rectangular pulse or of an impedance spectrum can be matched with an electrochemical and / or empirical battery model and the aging parameters determined using electrochemical equivalent circuit diagrams, for example considering a Warburg impedance commonly used for electrochemical systems for improved description charge diffusion, a Butler-Volmer equation for a charge transfer reaction, a Nernst equation for the overvoltage at the electrodes, a second Fick's law for the spherical diffusion at the electrodes, as well as a Faraday impedance of the electrode surfaces. A measurement of electrochemical effects thus provides, for example, the effect of a Li ion concentration on the electrode potential, the capacitance distribution due to electrode porosity, and the like

Growth of a solid-electrolyte interlayer, also referred to as the "solid electrolyte interface" (SEI) layer, which can occur in Li-ion systems.

This makes it possible to calculate the specific SOB values for a parameter. The aging state SOB, due to an aging parameter A can namely

_SQB _ IA _j -A _iE0L | _ | AAj- AAj _E0L | _(G1) l ^A iSOL ^-A iEOL l Aj _E OL be determined. In this case, i denotes the index of an aging parameter A (for example, ohmic resistance) of the electrochemical storage unit. The size SOL (=

"Start of life"), an initial state and the size EOL (= "end of life") a criterion for the end of the life of the electrochemical storage unit for this parameter A. The symbol Δ indicates a difference to the initial state. The aging state is related to, for example, the ohmic resistance, the thickness of the SEI, the

Double-layer capacity of the anode of the storage unit. Electrochemical processes may depend on external aging factors of the storage unit, which may include, for example, the depth of discharge, maximum state of charge (SOC) charge state, charge rate, discharge rate, temperature, etc. Because of the variety of parameters, statistical planning may be used For the evaluation, an empirical aging model can be used for the evaluation.

For example, the change in a SOB parameter ΔΑ per unit time Δt can be determined as a function of the external aging factors

ΔΑί (Δΐ) = β ₁₀ ^Ei + β ₁₄ E ₂ + - (G2)

m

where the coefficients E _{m represent} external aging factors such as the depth of discharge (DOD) and β _m linear regression coefficients, using statistically planned aging cycles (variation of E,) in the laboratory and measurements in the field, eg from a battery management system (BMS) are determined in the vehicle.

Depending on the possibility of measuring the values, the time unit Δt can be chosen so that a precise analysis is possible.

At the time t = Σ Μ = the change of the SOB parameter is AA ^ t) =

ΔΑ-

Σ "^ ~ - l ^m borderline case for very small At goes beyond this sum into an integral.

The sum represents a linear combination of different functions depending on the aging factors and their interactions.

An influence of the battery state on the SOB parameters A can be established via the statistical experimental design, with which the change of a SOB parameter Aj per time unit Δt can be represented as follows, for example:

ΔΑί (Δί) = α ₁₀ + cinBi + ₁₂ B ² + a ₁₃ e ^Bl + a ₁₄ B ₂ + ··· (G3)

+ a ₁₅ B ₁ B ₂ wherein the coefficients Bi represent battery state parameters such as battery voltage or temperature and a _m linear regression coefficients, which are determined by statistically planned aging cycles (variation of E,) in the laboratory and measurements in the field (eg BMS in the vehicle).

If the coefficients are linearly independent, the influences are separable. The determination of the coefficients takes place at different battery states. With the definition of the aging state SOB, a refined aging state SOBi can be calculated as a function of battery state parameters Bi at an arbitrary time t between a time t1 = SOL and a time t2 = EOL. For example, this can be calculated using the formula:

By combining several functions, this results, for example, in shorthand:

I Σ _ΔΪ Σ _Ι «iif (Bi) - A _iEQL |

SOB, - = (G5)

| AA _{i E0L} | where f (Bi) is a general function of Bi representing a linear combination of different functions depending on the battery states and their interactions.

An extension of the model via a combination of the aging factors E _m and the Battenezustandparameter B _m may, for example, look like this: i (B ₁ , E _m ) = β _{in the} f (E _m ) +> otnfCBj) (G6)

wherein in the first term on the right side of the equals sign, the aging of the storage unit is taken into account via the aging factors E _m and in the second term the variation of the battery state via the battery state parameters Bi. The impact of a specific application can be considered through analysis of a load profile specific to the application. The aging parameters (depth of discharge, maximum SOC, charge rate, discharge rate, temperature) can have non-linear dependencies, so that the determination of the interactions is necessary. The analysis of the mutual dependencies and the comparison with the load profile can thus lead to an extension of the battery model. For example, this can be expressed as follows:

AAi (Bj, E _m (n)) = (G7)

wherein the coefficients γ, _{η are} application specific coefficients and Em (n) are weighted aging factors for the aging by the operation of the memory unit in the application n.

The application-specific coefficients γ, _η can be determined, for example, from an analysis of a load profile of the application n. For example, application n may be characterized by a number of aging parameters such as depth of discharge, maximum SOC, charge rate, rate of discharge, temperature. For accurate characterization, knowledge of nonlinear dependence and interactions of these parameters is important. For example, an average current strength is not meaningful when larger current fluctuations occur and a non-linear dependence of the current on the time is suspected. Thus, it may be advantageous to record a load profile in the form of a histogram of current intervals over time and thus to register a frequency distribution, or a distribution of the duration of current values in certain areas. Based on a present battery model, this frequency distribution can then be weighted via the current strengths in order to derive a weighted frequency distribution therefrom. Thus, individual regions of the weighted frequency distribution can be formed and an average value can be formed over these regions. An application-specific coefficient can then be determined from this mean value. For the example with the current distribution, the coefficient γ, _η results as the mean value in relation to the maximum current: loading (G8)

'n.laden.max

Thus, a weighted aging factor E _m , which depends on the application n, can be represented, for example, as follows: m (n) = y _n E _m (G9)

where E _{m represents} an external aging factor.

The characteristics of the battery model allow a measurement of SOB parameters at each battery condition as well as a determination of battery aging by a specific application.

The calculation of the SOB can be done over time. Each external aging factor causes a change in the SOB. SOBi is such a function of time in which the respective aging factor has loaded the battery. The aging parameter A and thus also the aging state SOB are thus dependent on the time t. This implies, for example:

SOBi = ' ^{Αί (ΐ)} ; ^Α _Α ^ίΕΟί Ί (G10) for an index i of the aging parameter A.

The development of the aging parameter A over time t depends on the application. For example, the influence of the current, the current integral over a duration t, of a first application may be different from that of a second application.

The determination of the change of the external aging factors ΔΑ can be expressed generally by equation G6 with: a "B ₁ (G11) where f (Bi) = Bi and f (E _m ) = E _{m is} assumed. This results in the refined aging state, for example:

Measurement and evaluation of the parameter A yield ΔΑ (t). A SOL represents the start value, accordingly ΔΑ SOL = 0. AA, EOL is defined in advance or taken from the data sheet of the battery, and ßim are determined by aging tests. Battery condition parameters Bi are set via a statistically determined measurement series.

For a specific application n, an application-specific aging state then applies, for example:

with the application-specific coefficients γ ,.

The calculation of the overall aging state SOB _tot results, for example, in:

SOB _ges (Bj, E _m ) (G14)

where N is the total number of parameters A considered. As an alternative to the representation and calculation as a function of time, the SOB can also be determined by cumulative aging. Each external aging factor causes a change in the SOB. SOBi is such a function of accumulated aging by the respective aging factor. Cumulative aging can thus be expressed as an integral over the aging factors E _m :

For example, the SOB parameter ohmic internal resistance changes due to the external aging factor temperature. Thus, the SOBRohm is a cumulative aging kiem function.

The value of the electrochemical storage unit depends on a guaranteed / predicted number of days No over which the storage unit is operated and on the total cost of the storage unit K. This results in an initial value W _z per day:

According to an advantageous embodiment, the residual value can be determined on the basis of storage-specific costs and a residual service life of the electrochemical storage unit predicted from the battery state (SOB).

By means of the combination with the SOB, a prediction of the number of (residual) cycles NRz (n) and the remaining lifetime in application n can be made from the battery state SOBi (Bi, Em (n)) for determining the application-specific aging the residual value SOV for the application n is determined as the value of the memory unit. For example, the product is formed for this purpose:

SOV (n) = W _z x N _RZ (s) (G17)

In this case, however, no expenses for a conversion of the battery for use in the application n are taken into account. In summary, the following relationships for the refined state of aging result for the determination of the state of the electrochemical storage unit

for the further refined state of aging:

for the application-specific state of aging:

and for the overall aging state:

According to an advantageous embodiment, the aging factors for the operation of the memory unit in the memory-specific application can be cumulated over a remaining time of the electrochemical storage unit. The remaining term can be referred to, for example, as expected remaining operating time. In this way, application-specific aging factors can be taken into greater consideration and, in addition, a general statement about the presumably still possible operation of the storage unit in the application can be made. According to an advantageous embodiment, at least one of the physical properties of the electrochemical storage unit may be used to determine the aging state of the storage unit: (i) ohmic resistance, (ii) electrical capacitance, (iii) pulsed discharge or charge waveform, or (iv) electrical impedance , From these

Measurements can be obtained using electrochemical models SOB parameters. These aging parameters can be determined by comparing the measured data with the battery model. The ohmic resistance of the electrochemical storage unit can be relatively easily measured with a favorable measurement technique, wherein the memory unit usually provides the values via a control unit. Such a control unit is often referred to in batteries as the battery management system (BMS). The ohmic resistance can be measured as a voltage drop directly after a change in the current, for example a current pulse. At a load resistance, the voltage drop can be determined with impressed current, resulting in, after successful

Measurement of the open circuit voltage, which determines the internal resistance of the storage unit. The electrical capacitance can also be determined in a simple manner indirectly via resistance and impedance or directly via current integration. Thus, the capacity can be determined as dependent on current and temperature size. A voltage curve with pulse-shaped discharge requires a more complex measuring technique, since high-resolution, for example in the microsecond range, voltage values and current values must be recorded. Thus, ohmic resistance, double-layer capacitance and diffusion values can be determined, whereby measurements of the diffusion values take place over a relatively long period of time, up to days.

Also for impedance measurements a time-fast measuring technique is required, which can determine inductive behavior, double-layer capacitances, resistances and diffusion. Impedance measurements are important because electrochemical processes in the electrochemical storage device are frequency dependent.

According to an advantageous embodiment, the detection of the parameters for matching with an electrochemical model of the electrochemical storage unit for determining external aging factors can be carried out by means of a statistical experimental design. An empirical-electrochemical model of the memory unit, which allows the correlation of electrochemical processes with the parameters, has the advantages that it has a reference to physics, is transferable to different types of batteries, is statistically protected, contains orthogonality of the parameters and low test cost required by statistical experimental design.

According to an advantageous embodiment, the matching of the acquired parameters with an empirical model of the electrochemical storage unit may include comparison with an empirical aging model. This avoids complex electrochemical modeling, the parameters of which could only be determined very inaccurately and with considerable effort.

According to an advantageous embodiment, the balancing of the determinable parameters of the electrochemical storage unit with the battery model can include a specific weighting of the parameters of the electrochemical storage unit detected in the load profile for the memory-specific application. The impact of a specific application can be considered through analysis of a load profile specific to the application. Load profiles can make very different demands on the operating parameters of the memory unit for different applications, so that a corresponding weighting is advantageous. The type of weighting depends favorably on the battery model. Thus, different areas of the aging parameters can be recorded as a histogram and then weighted according to the battery model.

According to an advantageous embodiment, the electrochemical model and / or the empirical model of the electrochemical storage unit can be adapted on the basis of measured aging conditions and / or accumulated aging factors of the electrochemical storage unit. In this way, flat-rate time effects of the aging of storage units can be statistically better detected and also the battery models are not overly expensive in the detailing. According to a further aspect of the invention, a system is proposed for evaluating a state, in particular an aging state and / or a value, in particular a residual value, of an electrochemical storage unit which is used in at least one memory-specific application, with at least one central database having at least one battery model which comprises an electrochemical model and / or an empirical model of the electrochemical storage unit. The system further comprises one or more of the components, (i) at least one test stand for receiving a plurality of aging state parameters of the electrochemical storage unit, (ii) at least one workshop tester, and (iii) at least one memory system for operating the electrochemical storage unit. In this case, the system is provided to carry out a method as described above, wherein the database is provided for storing parameters of the electrochemical storage unit acquired with the components.

A test stand can in particular serve to capture the essential information for evaluating an aging state of a memory unit by recording not only electrical parameters such as impedances or charge / discharge cycles of the memory unit with great accuracy, but also, for example, the memory unit under certain thermal boundary conditions is examined and / or electrical load profiles are recorded. Therefore, a test bench usually also includes at least one heat chamber and / or electrical load components in addition to the necessary electrical measuring devices. In particular, parameters of models can be determined and / or verified with a test bench.

By contrast, with the aid of a workshop test device, electrical parameters such as impedance and / or current / voltage curve of the memory unit can be detected in a fast and effective manner via interfaces to the control unit of the memory unit, in particular in the installed state of the memory unit, for example in a vehicle, and / or ongoing operation of a particular operating condition, be determined. ""

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According to an advantageous embodiment, the database can be provided as a self-learning database. This allows measurement data from storage units to be continuously fed into the system and further refine the models with the recorded measurement data. Due to a large number of storage units aged under different conditions, outliers of individual storage units can be filtered out and general statements made for the modeling. The models of the storage units thus gain ever greater significance.

According to an advantageous embodiment, the electrochemical model and / or the empirical model for adaptation can be provided by the detected parameters of the electrochemical storage unit. Measurement data of the memory unit serve to continuously improve the informative value of the battery models, which run in the database of the system.

According to an advantageous embodiment, the database may be provided for generating test plans and for evaluating parameters of an operation of the electrochemical storage unit, in particular a field operation. Due to the ongoing improvement of the models in the database, it can make a continuously improved statement about suitable test plans for recording parameters of the memory unit as well as for the evaluation of the parameters. In particular, information from storage units which are operated in the field under real conditions can contribute to this. It is particularly advantageous if this information about the operation in the field over longer periods of time to the database of the system to be fed back.

According to an advantageous embodiment, the test stand can at least for determining an impedance of the electrochemical storage unit, and / or a thermal conditioning of the electrochemical storage unit and / or a determination of electrical load profiles of the electrochemical

Storage unit be provided. These parameters provide the essential information for evaluating a state of aging of a memory device, especially when acquired with great accuracy, as is possible with a test bench. According to an advantageous embodiment, the workshop testing device may include diagnostic tools with interfaces to an electronic control unit of the electrochemical storage unit, wherein the workshop testing device is provided for determining an impedance and / or for determining a current / voltage curve of the electrochemical storage unit.

With the help of the workshop testing device, the essential parameters required for the evaluation of a storage unit can be procured in a relatively simple manner and in a short time. According to an advantageous embodiment, the storage system can be provided for operating a pre-aged electrochemical storage unit. With the storage system, a pre-aged storage unit can be operated, wherein the storage system can be connected to the database of the system so as to be able to select favorable operating parameters for operating the storage unit in order to ensure a favorable residual maturity of the storage unit.

On the other hand, information from the operation of the pre-aged storage unit can be fed back into the database of the system in order to constantly improve the battery models running there. drawing

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

By way of example: FIG. 1 shows a system for evaluating a state, in particular one

Aging state and / or a value, an electrochemical storage unit according to an embodiment of the invention;

2 shows a method sequence according to an embodiment of the

Invention for a specific application showing the essential process steps; 3 shows the method sequence of FIG. 2 for the specific application with representation of the model approaches; 4 shows a histogram of a weighted load profile 62 using the example

Current measurement for an application;

5 shows a method sequence according to an embodiment of the

Invention with an assignment of specific sizes;

6 shows a schematic representation of a first step of the method according to the invention;

7 shows a schematic representation of a further step of the method according to the invention;

8 shows a schematic representation of a further step of the method according to the invention; 9 is a flowchart of the method according to the invention for

Evaluating a condition, in particular an aging condition and / or a value, of an electrochemical storage unit according to an embodiment of the invention; and

Fig. 10 shows a system according to an embodiment of the invention with a test stand with climatic chambers and impedance meter.

Embodiments of the invention

In the figures, the same or similar components are numbered with the same reference numerals. The figures are merely examples and are not intended to be limiting.

FIG. 1 shows a system 20 according to an exemplary embodiment of the invention for evaluating a state, in particular an aging state and / or a value, of an electrochemical storage unit 10 that is present in at least one of the embodiments memory-specific application 58 is used. The system 20 comprises at least one central database 22 with at least one battery model 13, which comprises an electrochemical model 14 and / or an empirical model 16 of the electrochemical storage unit 10. The system 20 further includes a test bench 24 for receiving a plurality of parameters 30 of a

Aging state 32 of the electrochemical storage unit 10, a workshop tester 26, a memory system 12 for operating an electrochemical storage unit 10. The database 22 is provided for storing component 30 detected parameters of the electrochemical storage unit 30.

The electrochemical model 14 and / or the empirical model 16 are provided for adaptation by the detected parameters 30 of the electrochemical storage unit 10. The database 22 is provided as a self-learning database 22 so as to be able to continuously improve the electrochemical and / or empirical battery models 14, 16 implemented thereon with the recorded measurement data from memory units 10. The database 22 is further provided for generating test plans and for evaluating parameters 30 of an operation of the electrochemical storage unit 10, in particular a field operation.

The test stand 24 is at least for determining an impedance of the electrochemical storage unit 10, and / or a thermal conditioning of the electrochemical storage unit 10 and / or a determination of electrical load profiles 62 of the electrochemical

Memory unit 10 is provided.

The workshop testing device 26 includes diagnostic tools with interfaces to an electronic control unit of the electrochemical storage unit 10, wherein the workshop testing device 26 is provided in particular for determining an impedance and / or for determining a current / voltage curve of the electrochemical storage unit 10.

The storage system 12 is provided in particular for operating a pre-aged electrochemical storage unit 10. FIG. 2 shows a method sequence according to an exemplary embodiment of the invention for a specific application 58 with the representation of the essential method steps. One or more specific applications 58, indicated by the subscript n, may be considered.

Measured values 30 for a parameter A of the memory unit 10, such as ohmic resistance or impedance, are determined by a suitable measuring method 50, which may be, for example, an impedance measurement. With the index i, the parameters A are numbered consecutively.

To determine the aging state 32, SOB ,, the storage unit 10, for example, characterized by aging parameters such as ohmic resistance R ₀ hm, or electrical capacitance, in this case be at least one of the physical properties of the electrochemical storage unit 10 voltage waveform in pulse-shaped discharge or charge, electrical

Impedance, or the characteristics determined from the modeling of the measurement results of the voltage measurement according to pulse-shaped charge and discharge as well as the impedance measurement. For the measured values 30 of each of the parameters A, an initial is set in the analysis 52

Aging condition 32, SOB ,, determined according to equation G10. By means of a statistical experimental design 54, external, in particular accumulated, aging factors 42 (see FIG. 6) are detected and, starting from the initial aging state 32, a refined aging state 34, SOBi (Bi), which can be determined according to equation G18, is described in detail. About the influence of

From this, a further refined aging state 36, SOBi (Bi, E _m ), is calculated according to equation G19 in order to determine the aging state 38, SOB, (Bi, E _{m.) Associated} with the specific application 58 for a specific application 58, n (n)), according to equation G20. The influence of the cost 60 for this application 58, n, leads to the value 40, SOV (n), of the memory unit 10 according to equation G17. The value 40, SOV, is determined on the basis of storage-specific costs and a residual life of the electrochemical storage unit 10 predicted from the initial aging state 32, SOBi.

FIG. 3 shows the method sequence of FIG. 2 for the specific application 58, n, with representation of the model approaches. After taking the measured values 30 in the Measuring method 50 is determined by means of an electrochemical model 14 of the initial aging state 32, SOB ,, and then subsequently using an empirical model 16 of the refined aging state 34, SOBi (Bi), thus further detailed. Matching the measured values 30 with an electrochemical model 14 of the electrochemical storage unit 10 recorded by means of a statistical experimental design involves correlating electrochemical processes with external, in particular accumulated, aging factors 42 (FIG. 6). Furthermore, with the aid of the empirical model 16, the further refined aging state 36, SOBi (Bi, E _m ), is calculated taking into account the battery state 56. Matching the acquired measurements 30 with an empirical model 16 of the electrochemical storage unit 10 involves matching with an empirical aging model 18. The electrochemical model 14 and / or the empirical model 16 of the electrochemical storage unit 10 is calculated on the basis of measured accumulated aging factors 42 (FIG 6) of the electrochemical storage unit 10 again adapted. With the help of the electrochemical model 14 battery parameters are determined. From the change of these parameters, a SOB 32 is calculated. The effects of external aging factors 42 on these parameters are modeled by the empirical model 16. The refined aging state 34, SOBi (Bi), as well as the further aging state 36, SOBi (Bi, E _m ), can then be represented as a function of time.

By means of an analysis of the recorded load profile 62 for the application 58, n, the aging state 38, SOBi (Bi, E _m (n)), which relates to the specific application 58 can then be determined. The comparison of determinable measured values

30 of the electrochemical storage unit 10 with the battery model 13 in this case comprises a specific for the memory-specific application 58 weights measured in the load profile 62 parameter 30 of the electrochemical storage unit 10, as shown in the following Figure 4. The specific residual value 64 for the specific application 58, n, can thus be over the value

40, SOV (n).

FIG. 4 shows a histogram of a weighted load profile 62 using the example of a current measurement. Application-specific coefficients γ, _η for a memory-specific application 58, n can be determined, for example, from the analysis of a load profile 62 of the application 58, n. The application 58, n, may for example be characterized by a series of Aging parameters such as depth of discharge, maximum SOC, charge rate, discharge rate, temperature. For accurate characterization, knowledge of nonlinear dependence and interactions of these parameters is important. For example, an average current strength is not meaningful when larger current fluctuations occur and a non-linear dependence of the current on the time is suspected. Thus, it may be advantageous to record a load profile 62 in the form of a histogram at current intervals over time and thus to register a frequency distribution 80 of measured values 30, such as current values. On the basis of a present battery model, this frequency distribution 80 can then be weighted via the current strengths in order to derive therefrom a weighted frequency distribution 82. Thus, individual regions 86 of the weighted frequency distribution 82 may be formed and averages over these regions 86 may be formed. Application-specific coefficients can then be determined from these mean values. For the example with the current distribution, the result is a coefficient γ, _η as the mean value of the current in relation to the maximum current:

In Figure 4, frequency values 80 of current values are plotted at intervals. These frequency values 80 are weighted with a weighting function 84 which is specific to the application 58 under consideration. This weighting results in weighted frequency values 82. These weighted frequency values 82 have then been subdivided into individual averaging areas 86, such as an area 86, T _n , iaden, for charging a battery, and an area 86, T _n , for which Discharging the battery over which averaging areas 86, the weighted frequency values 82 are averaged, to derive the

To determine coefficients γ, _η as the mean value of the charging or discharging current in relation to the maximum current.

FIG. 5 shows an assignment of the variables determined in the method sequence according to an exemplary embodiment of the invention. Measured values 30 for the parameter A of the memory unit 10, the aging state 32, SOB, determined therefrom for the measured value 30 of the parameter A, and the aging state 34, SOBi (Bi) determined with the aid of the empirical model 16, are specific to the memory unit 10 and therefore assigned to this memory unit 10. For the application 58, n, specific quantities, on the other hand, are the quantities derived therefrom, such as the further refined state of aging 36, SOBi (Bi, E _m ) "the aging state 38 SOBi (Bi, E _m (n)) 38 related to the specific application 58 and the value 40, SOV (n),.

FIG. 6 shows a schematic representation of a first step of the method according to the invention. In a targeted aging process 66, external, in particular accumulated, aging factors 42 can act on the memory unit 10, so that after the aging process 66, the findings 52 provide the battery state-dependent aging state 32, SOB. The aging factors 42 for the operation of the memory unit 10 in the memory-specific application 58 are weighted, such as in FIG

4 and / or accumulated over a remaining time and / or expected operating time of the electrochemical storage unit 10.

In this case, as shown in FIG. 7, in a further step of the method, an empirical aging model 18 for the influence of the external aging factors 42 can be created for the aging process 66 and thus the further refined age state 36 can be calculated using the empirical electrochemical model 14, 16. SOBi (Bi, E _m ). Further, as shown in FIG. 8, from the analysis of the memory-specific application 58, n, an application-specific aging state 38, SOBi (Bi, E _m (n)), and a value 40, can be derived therefrom.

SOV (n).

FIG. 9 shows a flow diagram of the method according to the invention for evaluating a state, in particular an aging state and / or a value, of an electrochemical storage unit 10 used in at least one memory-specific application 58. In step S100, at least one parameter 30 of an aging state 32 is displayed the electrochemical storage unit 10 is detected at a first time t1, followed by step S102, in which the detected parameter 30 is compared with a battery model 13 of the electrochemical storage unit 10 for deriving, in particular accumulated aging factors 42, the battery model 13 an electrochemical model 14 and / or an empirical model 16. Thereafter, in step S104, at least one electrical load profile 62 characteristic of the memory-specific application 58 of one or more electrochemical storage units 10 during operation in the memory-specific

Application 58 recorded. In step S106, the detected load profile 62 for the specific application 58 for analyzing the interdependencies the determinable parameter 30 of the electrochemical storage unit 10. In step S108, the state of the electrochemical storage unit 10 for the storage-specific application 58 on the basis of the aging factors 42 for a future time t2 is predicted. The aging factors 42 are correlated with an operation of the electrochemical storage unit 10 in the memory-specific application 58.

FIG. 10 shows a system 20 according to an exemplary embodiment of the invention having a test stand 24 with climatic chambers 74 and impedance measuring device 70, which records, via a multiplexer 72, the impedances of storage units 10 which are held in the climatic chambers 74 at a defined temperature and to the database 22 of the system 20 supplies. The impedance measuring device 70 is connected via the multiplexer 72 to the various storage units 10 in the climatic chambers 74. The test stand 24 drives the memory units 10 and receives further measured values over a plurality of channels Ci to C _n and also supplies this information to the database 22, where they are further processed in the electrochemical or empirical models 14, 16.

Claims

claims

Method for evaluating a state, in particular an aging state (32) and / or a value (40), of an electrochemical storage unit (10) used in at least one memory-specific application (58),

full

(i) detecting at least one parameter (30) of the aging state (32) of the electrochemical storage unit (10) at a first time (t1);

(ii) matching the detected parameters (30) to a battery model (13) of the electrochemical storage unit (10) for deriving aging factors (42), the battery model (13) comprising an electrochemical model (14) and / or an empirical model (16 );

(iii) detecting at least one electrical load profile (62) characteristic of the memory-specific application (58) of one or more electrochemical storage units (10) when operating in the memory-specific application (58);

(iv) weighting the detected load profile (62) for the specific application (58) to analyze the interdependencies of the determinable parameters (30) of the electrochemical storage unit (10); and

(v) predicting the state of the electrochemical storage unit (10) for the storage-specific application (58) based on the aging factors (42) for a future time (t2) showing aging factors (42) with operation of the electrochemical storage unit (10) in FIG the memory-specific application (58) are correlated.

The method of claim 1, wherein the value (40) is determined based on storage specific cost and a residual life of the electrochemical storage unit (10) predicted from the aging condition (32).

Method according to claim 1 or 2, wherein the aging factors (42) for the operation of the memory unit (10) in the memory-specific application are cumulated over a remaining running time / expected operating time of the electrochemical storage unit (10).

Method according to one of the preceding claims, wherein for determining the aging state (32) of the memory unit (10) at least one of the physical properties of the electrochemical storage unit (10).

(i) ohmic resistance (Rohm),

(ii) electrical capacity,

(iii) Voltage profile with pulse-shaped discharge or charge of the electrochemical storage unit (10),

(iv) electrical impedance,

be used.

Method according to one of the preceding claims, wherein the detection of parameters (30) for matching with an electrochemical model (14) of the electrochemical storage unit (10) for determining external aging factors (42) takes place by means of a statistical experimental design.

The method of any one of the preceding claims, wherein matching the sensed parameters (30) to an empirical model (16) of the electrochemical storage unit (10) comprises balancing with an empirical aging model (18).

Method according to one of the preceding claims, wherein the balancing of the determinable parameters (30) of the electrochemical storage unit (10) with the battery model (13) for the memory - specific application (58) specific weighting of the parameters (30) of the load profile (62) electrochemical storage unit (10).

Method according to one of the preceding claims, wherein the electrochemical model (14) and / or the empirical model (16) of the electrochemical storage unit (10) on the basis of measured aging conditions (32) and / or accumulated aging factors (42) of the electrochemical storage unit (10 ) is adjusted.

System (20) for evaluating a state, in particular an aging state (32) and / or a value (40), of an electrochemical storage unit (10) used in at least one memory-specific application (58), having at least one central database (22 ) having at least one battery model (13) which comprises an electrochemical model (14) and / or an empirical model (16) of the electrochemical storage unit (10),

comprising one or more of the components

(i) at least one test stand (24) for receiving a plurality of parameters (30) of an aging state (32) of the electrochemical storage unit (10),

(ii) at least one workshop testing device (26),

(iii) at least one storage system (12) for operating the electrochemical storage unit (10),

the system being intended to carry out a method in particular according to one of the preceding claims,

wherein the database (22) is provided for storing parameters (30) of the electrochemical storage unit (10) acquired with the components.

The system of claim 9, wherein the database (22) is provided as a self-learning database (22).

A system according to claim 9 or 10, wherein the electrochemical model (14) and / or the empirical model (16) is provided for adaptation by the detected parameters (30) of the electrochemical storage unit (10).

12. System according to any one of claims 9 to 1 1, wherein the database (22) for generating test plans and for the evaluation of parameters (30) of an operation of the electrochemical storage unit (10), in particular a field operation, is provided.

13. System according to one of claims 9 to 12, wherein the test stand (24) at least for determining an impedance of the electrochemical storage unit (10), and / or a thermal conditioning of the electrochemical storage unit (10) and / or a determination of electrical load profiles ( 62) of the electrochemical storage unit (10) is provided.

14. System according to any one of claims 9 to 13, wherein the workshop testing device (26) comprises diagnostic tools with interfaces to an electronic control unit of the electrochemical storage unit (10), wherein the workshop testing device (26) for determining an impedance and / or Determining a current / voltage curve of the electrochemical storage unit (10) is provided.

A system according to any one of claims 9 to 14, wherein the memory system (12) is for operating a pre-aged electrochemical storage unit (10).