EP3977587A1

EP3977587A1 - Battery management system and operating an energy store for electrical energy

Info

Publication number: EP3977587A1
Application number: EP20727608.0A
Authority: EP
Inventors: Matthias Kloepfer; Simon KOLB; Eric Hartmann
Original assignee: Mercedes Benz Group AG
Current assignee: Mercedes Benz Group AG
Priority date: 2019-05-31
Filing date: 2020-05-20
Publication date: 2022-04-06
Also published as: CN113875117A; DE102019003823A1; WO2020239577A1

Abstract

The invention relates to a method for operating an energy store (2) with a charging status range (7). In addition, an operating range (8) is provided within the charging status range (7), and a respective one or more aging characteristic values (11, 12) accumulated over an operating duration of the energy store (2) are determined by means of a control unit (5) based on one or more predefined aging functions (9, 10). The operating range (8) is adjusted according to the aging characteristic values (11, 12), and a charging status of the energy store (2) is limited to the adjusted operating range (8', 8'').

Description

Battery management system and operation of an energy storage device for electrical energy

The present invention relates to a method for operating an energy store for electrical energy, the energy store having a state of charge range and an operating range being specified which lies within the state of charge range. The invention also relates to a corresponding battery management system as well as a motor vehicle and a computer program.

Accumulators or rechargeable batteries age due to different physical effects. For example, an electrolyte in lithium-ion batteries can age more intensely at high cell voltages, i.e. in particular at high states of charge, and at high temperatures, while, for example, a copper arrester at the anode can age more intensely at a lower cell voltage, i.e. at a lower state of charge. In known battery management systems, an operating range for the rechargeable battery is therefore permanently specified, so that specific partial areas of the state of charge range, in particular in an area of maximum and minimum charge, are left out in order to prevent excessive aging.

However, depending on user behavior, certain areas of the battery's state of charge are used more frequently and other areas less. Therefore, a fixed specification of the operating state range is necessarily not optimal, so that a compromise has to be made which at most takes into account different user behavior in each case, but not in an optimal way. If the user usually only discharges the battery to a small extent before fully charging it again, the battery is mainly in the upper part of the state of charge or

Operating range. Opposite user behavior could, for example, be such that a user only charges the battery for a short time in order to ensure a minimum necessary capacity, but usually charges the battery the lower part of the state of charge or operating range, which, depending on temperature zones or seasons, can have a negative impact on the service life.

Due to the not optimally tailored to the respective user behavior

In the operating state range, there is still increased aging.

With this in mind, it is an object of the present invention to provide a

to specify an improved concept for operating an energy store for electrical energy, by means of which an increased service life of the energy store is achieved.

According to the invention, this object is achieved by a method

Battery management system, a motor vehicle and a computer program according to the independent patent claims. Further advantageous embodiments and

Further developments are the subject of the dependent claims.

The improved concept is based on the idea of determining cumulative aging indicators and adapting the operating area, in particular a position of the operating area, as a function of the aging indicators in order to adapt the user behavior

To take into account

According to a first independent aspect of the improved concept, a

A method for operating an energy store for electrical energy, that is to say an accumulator, or a battery for short, is specified, the energy store having a state of charge range. According to the method, an operating range of the energy store is specified, in particular by means of a battery management system, the operating range within, in particular completely within, the

State of charge range. Using one or more specified

Aging functions are each determined by means of a control unit, in particular the battery management system, one or more aging indicators accumulated over an operating period of the energy store. An upper limit value and / or a lower limit value of the operating range is adapted as a function of the one or more accumulated aging indicators by means of the control unit in order to define an adapted operating range, that is to say to adapt the operating range. A state of charge of the energy store is indicated by means of the control unit adapted operating range limited, in particular during charging and / or discharging of the energy store.

The state of charge range is in particular a range of values that a state of charge (SOC) of the energy store can assume. It is therefore a range of values between complete discharge and complete charge of the energy store. For example, the state of charge can be specified as a percentage of the maximum possible charge of the energy store, so that the state of charge range by definition extends from 0% to 100%. Alternatively, the state of charge can also be specified in relation to the electrical charge stored in the energy store, for example in Ah, so that the state of charge range extends from 0 Ah to a maximum charge of the energy store in Ah. In other words, the state of charge of the energy store can be understood as that charge capacity of the energy store that is required for the respective

Time is available in relation to a nominal maximum charge value. A state of charge of X% therefore means that the energy store is still one

Has a remaining charge of X% based on a maximum charge of 100%.

The operating range of the energy store is, in particular, a range to which the state of charge is limited in an actual operation of the energy store by means of a battery management system. In particular, the operating range lies completely within the state of charge range. That is, the lower limit of the operating range is greater than or equal to a minimum value of the

State of charge range, that is greater than or equal to 0%, and the upper limit value of the operating range is less than or equal to a maximum value of the state of charge range, that is to say less than or equal to 100%. For example, if the state of charge reaches the lower limit of the operating range, the control unit ensures that the

Energy store no further charge is taken, further use of the energy store for supplying energy to an electrical consumer is then no longer possible. If the state of charge reaches the upper limit of the operating range by charging the energy store, the control unit ensures that no further charge can be introduced into the energy store, so that charging can no longer be continued.

For example, the lower limit value can have a first distance of 0% and the upper limit value a second distance of 100%. This will avoid that the state of charge is too close to the values 0% and 100%, which can be associated with particularly severe aging of the energy storage device.

Initially, i.e. before the operating range was adjusted for the first time, the

Operating range are, for example, symmetrically within the state of charge range, so that the first and the second distance are the same.

When the energy store is in operation, charging of the

Energy storage and the discharging of the energy storage, in particular by supplying an electrical consumer, are understood.

The fact that the state of charge of the energy store is limited to the adapted operating range can be understood to mean that the control unit does this

is set up, a charging of the energy store via the adapted upper

To prevent limit value and to prevent the energy store from being discharged, in particular by removing electrical charge by means of an electrical consumer, below the adjusted lower limit value of the operating range.

The energy store is in particular an accumulator or storage battery or a rechargeable battery. In particular, it can be a battery for driving an at least partially electrically operated motor vehicle or a battery for an electronic device, for example a computer or a mobile radio device, a smartphone, a notebook or the like.

The energy store can contain, for example, a lithium ion accumulator, for example a lithium polymer accumulator, a lithium cobalt dioxide accumulator, a lithium iron phosphate accumulator or another

Accumulator which shows increased aging at a state of charge close to 0% and / or a state of charge close to 100%, in particular in comparison to a state of charge of about 50%.

The aging index can be, for example, a relative aging rate of the energy store due to one or more specific aging mechanisms, which contributes to an overall aging rate of the energy store. The aging of the energy store can result, for example, in a reduced total charge capacity or in a reduced remaining service life of the energy store. The aging index can, for example, indicate how great the aging rate is Is compared to a reference aging rate. The reference aging rate can

for example correspond to an aging rate at a predetermined reference state of charge of the energy store, wherein the reference state of charge can for example be in a range from 30 to 60%.

The aging index indicates in particular how much the energy store ages in a given state, for example a given temperature and / or a given state of charge, due to the corresponding aging mechanisms. In particular, the aging index is not an actually given aging of the energy store.

An aging function is, in particular, a function which assigns a corresponding aging index to a charge state of the energy store. Each of the one or more aging functions can thereby

for example reflect one or more aging mechanisms.

For example, a first aging function can be used for relatively small values of the

The state of charge can be relatively large and decrease as the state of charge increases. The first aging function thus describes, for example, an aging mechanism that leads to severe aging in the case of relatively small states of charge and is less important in the case of larger states of charge. A second aging function can, for example, be relatively small in the case of low state of charge values and increase as the state of charge rises, and can assume a relatively large value itself in the case of relatively large states of charge. The second aging function can therefore describe, for example, one or more aging mechanisms that occur more intensely with high states of charge and are less important for smaller states of charge.

In particular, each aging function can be assigned to a sub-area of the state of charge area, that is to say a sub-area in which the energy store ages particularly strongly.

The operating time of the energy store is in particular a time that has elapsed since a reference point in time, with periods of time within which the energy store was neither charged nor discharged, for example from the

Operating time can be excluded.

For example, the charging status of the

Energy store repeatedly determined, in particular with a predetermined sampling rate and the associated function values of the one or more

Aging functions can be determined by means of the control unit. The function values determined in this way are, for example, added up over the operating period for each aging function and then represent the one or more accumulated aging indicators. In particular, each of the

Aging functions precisely determine a cumulative aging index over the operating life of the energy storage device.

Each of the aging functions can, for example, be defined and specified continuously or discretely, in particular uniformly, over the entire state of charge range.

Before the limit values of the operating range are adapted, in particular before they are adapted for the first time, the control unit restricts the state of charge of the energy store to the operating range, for example.

By defining the aging functions and the corresponding determination of the cumulative aging indicators followed by a corresponding adjustment of the operating range or the limit values of the operating range, a position of the operating range can advantageously be adjusted depending on user behavior, which is directly included in the determination of the accumulated aging indicators, that one or more critical parts of the

State of charge area can be specifically left out. In the critical sub-areas, the aging rate of the energy store can be particularly high, for example, so that the overall aging rate, in particular the average aging rate, is reduced and the service life of the

Energy storage can be enlarged accordingly.

In particular, the user behavior decides whether the state of charge is more frequently in an upper or in a lower sub-range of the state of charge range or the operating range. A symmetrical positioning of the operating area is therefore not necessarily optimal.

In particular, the cumulative aging indicators reflect how often

or how long the energy store has been in the respective critical state of charge subregions. The adjustment of the limit values of the

Operating range can then take place specifically in such a way that less severe aging, so less strongly increasing cumulative aging indicators are to be expected over the further operation of the energy storage device.

According to at least one embodiment of the method, when adapting the limit values, a time profile of the cumulative aging indicators can be taken into account. In particular, it can be taken into account whether past adjustments to the limit values of the operating range resulted in a slowing down of the increase in the cumulative aging indicators. If this is not the case, the direction of the adaptation of the limit values can be inverted when there is a renewed adaptation.

Such embodiments can be particularly advantageous if only one

Aging function is used. By including the time profile, a basis for comparison can be created for the single cumulative aging indicator.

According to at least one embodiment, one of the accumulated

Aging indicators dependent size with an associated predetermined

Maximum value compared. In order to define the adapted reference range, the lower limit value is increased by means of the control unit depending on a result of the comparison, the upper limit value not being changed, or the upper limit value being reduced, the lower limit value not being changed, or the lower and upper limit values in each case, that is to say in particular both, reduced or in each case, that is to say in particular both, increased.

The variable that is dependent on the cumulative aging index can be the corresponding cumulative aging index itself, in particular if only one accumulated aging index and only one associated aging function are used. If two aging functions are used and there are correspondingly two accumulated aging indicators, the size can in particular be a difference between the accumulated aging indicators.

By reducing or increasing the limit values as described, the operating range is adapted in such a way that it differs from a critical sub-range of the

State of charge area, in particular from a particularly relevant critical sub-area according to user behavior, is further removed. According to at least one embodiment, a first cumulative aging index of the cumulative aging index is determined by means of the control unit on the basis of a first aging function of the predefined aging functions. Using the

The control unit is specified using a second aging function

Aging functions a second cumulative aging indicator of the cumulative

Determined aging indicators. The control unit determines a difference between the first and the second cumulative aging index, and the difference is compared, in particular, with a predetermined maximum difference value. If the difference is greater than the predetermined maximum difference value, the lower and the upper limit value of the operating range are increased by means of the control unit or the lower and the upper limit value of the operating range are decreased.

Whether the two limit values are increased or decreased depends in particular on a sign of the difference.

According to at least one embodiment, the first aging function relates to a

Aging behavior of the energy store, in particular an aging rate of the

Energy store, in a first sub-area of the state of charge range, and the second aging function relates to an aging behavior, in particular an aging rate, of the energy store in a second sub-range of the state of charge range. The first sub-area lies below the second sub-area.

For example, if the sign of the difference is such that the first cumulative aging index is greater than the second cumulative aging index, both limit values can be increased so that the operating range is shifted overall to higher state of charge values. If, on the other hand, the sign of the difference is such that the first aging index is smaller than the second aging index, then, for example, the two limit values are reduced, that is, the operating range is shifted to smaller state of charge values.

By taking into account the difference between the two cumulative aging indicators, it is possible in particular to identify which of the two aging indicators is more critical, i.e. which critical sub-area of the state of charge area occurs more frequently according to specific user behavior and is therefore particularly relevant.

Accordingly, the method can regulate itself, in particular if it is carried out iteratively several times, so that after a certain time or a certain amount of time Number of adjustments of the operating range an optimal position of the

Operating range can be set, in particular without affecting the entire

Expansion of the operating area must be reduced. Also a manual one

Control or adjustment of the operating range is not required.

Furthermore, an automatic adjustment of the operating range can also take place in the event of changing user behavior, since, by taking into account the difference, the limit values of the operating range, for example, always take place in such a way that an increase in the difference in the aging indicators is counteracted.

The first sub-range of the state of charge range lies in particular in an area around the minimum value of the state of charge range, that is to say in an area of 0%, or the first sub-range is itself limited by the minimum value, that is, it begins at 0%.

The second sub-range of the state of charge range lies in particular in the vicinity of the maximum value of the state of charge range or the minimum value itself is limited, that is to say ends at 100%.

That the first sub-area lies below the second sub-area means

in particular that each state of charge value that lies in the first sub-range is smaller than each state of charge value that lies in the second sub-range.

According to at least one embodiment, the first aging function has an absolute maximum in the first partial range, in particular at the minimum value, for example at 0%.

The first aging function thus describes one or more aging mechanisms that lead to increased aging at low state of charge values. Such

Aging mechanisms can include anode corrosion, for example.

According to at least one embodiment, the second aging function has an absolute maximum in the second sub-range, in particular at the maximum value,

for example at 100%.

The second aging function describes in particular one or more

Aging mechanisms that lead to a high aging rate at relatively high Lead state of charge values. Such aging mechanisms can include electrolyte aging, for example.

The first and / or the second aging function can in particular be determined empirically or be determined by experimental measurements. This enables a particularly exact description of the aging of the energy store as a function of the state of charge.

The first and / or the second aging function can also be based on

Model assumptions or hypothetical assumptions are determined.

For example, the first aging function can decrease linearly or quadratically from the absolute maximum in the first partial area. The second aging function can, for example, increase linearly or quadratically up to the absolute maximum in the second partial range.

According to at least one embodiment, the upper and lower limit values of the operating range are increased or decreased by the same value in each case. The total extent of the operating area or the proportion of the

The state of charge range, which is allocated to the operating range, remains constant as a result of the adjustment.

This advantageously avoids a reduction in the total available charge capacity of the energy store by adapting it to user behavior.

According to at least one embodiment, the steps of determining the cumulative aging indicators, adapting the operating range and limiting the state of charge of the energy store are repeated iteratively.

According to at least one embodiment, a value of the charge state of the energy store is determined by means of the control unit for a plurality of repetitions, a function value for the value of the charge state is determined for each of the one or more aging functions, and each of the function values is added to a respective sum variable. The one or more cumulative aging indicators are determined by means of the control unit as a function of the sum variables. The sum variables can, for example, be equal to zero at the reference operating time and then be filled up over the operation of the energy store as described.

The function value for the value of the state of charge is in particular the respective function value of the aging function at the given value of the state of charge.

The respective cumulative aging index can therefore in particular be the respective sum variable after a certain number of repetitions. That is, the comparison of the difference with the maximum difference value is

for example performed after a certain number of repetitions.

Alternatively, the respective cumulative aging index of the sum variables can be made accordingly after each repetition, so that the comparison and the adjustment of the operating range can take place after each repetition.

In such an embodiment, the aging indicators are determined in particular by simply adding up aging-specific indicators, so that an actual analysis of the aging status of the energy store is not required.

According to at least one embodiment, a size is the adapted

Operating range equal to a size of the operating range.

The size of the operating range or the adapted operating range corresponds in particular to a difference between the upper limit value and the lower limit value or the upper adapted and the lower adapted limit value.

According to at least one embodiment, a first distance of the lower limit value from a minimum value of the state of charge range is determined by means of the control unit and / or a second distance of the upper limit value from a maximum value of the state of charge range is determined. The control unit does not reduce the lower limit value to define the adapted operating range if the first distance is smaller than a predefined first minimum distance and / or the upper limit value is not increased to define the adapted operating range if the second distance is greater than a predefined one second

Minimum distance. The minimum value and the maximum value of the state of charge range can in particular be the lower and the upper limit of the state of charge range. The minimum value is therefore in particular 0%, the maximum value in particular 100%.

When both limit values of the operating range are shifted, the aging behavior is related to one of the critical sub-ranges of the

State of charge area improved, but worsened with regard to the further critical sub-area. Although the latter sub-area is less relevant according to the specific user behavior, in individual cases this cannot be completely avoided either. To prevent excessive aging in such exceptional cases, the intervals between the limit values of the

Operating range can be limited to the minimum distances.

According to a further independent aspect of the improved concept, a battery management system for an energy store for electrical energy is specified, the energy store having a state of charge range. The battery management system includes a state of charge sensor and a

Control unit. The state of charge sensor is set up to determine a state of charge of the energy store and to generate a sensor signal based thereon, that is to say on the determined state of charge. The control unit is set up to limit operation of the energy store as a function of the sensor signal to a predetermined operating range, the predetermined operating range being within the state of charge range. The control unit is designed to use one or more aging functions to determine one or more cumulative aging indicators, in particular as a function of the sensor signal. The control unit is set up to set an upper limit value or a lower limit value

Adjust the limit value of the operating range as a function of the one or more cumulative aging indicators in order to define an adapted operating range and to adjust the state of charge as a function of the sensor signal

Restrict operating range.

According to at least one embodiment, the state of charge sensor contains a voltage sensor which is set up and arranged to determine an output voltage or a counting voltage of the energy store and to generate the sensor signal based thereon. According to at least one embodiment, it is the

Battery management system to a battery management system for a fully or partially electrically driven motor vehicle or an electronic device, for example a smartphone, a tablet computer or a notebook.

Further embodiments of the battery management system follow directly from the various embodiments of the method for operating a

Energy storage according to the improved concept and vice versa. In particular, the battery management system can be set up or programmed to carry out a method according to the improved concept, or the battery management system carries out such a method.

According to a further independent aspect of the improved concept, a motor vehicle is specified which has an energy store for at least partially electrically driving the motor vehicle, the motor vehicle having a battery management system for the energy store according to the improved concept.

According to a further independent aspect of the improved concept, a computer program is specified with commands which, when the

Computer program by means of a computer system, in particular by means of a control unit of a battery management system according to the improved concept, cause the computer system to carry out a method for operating an energy store according to the improved concept.

According to a further independent aspect of the improved concept, a computer-readable storage medium is specified on which a computer program according to the improved concept is stored.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and with reference to the drawings. The features mentioned above in the description and

Combinations of features and the features and combinations of features mentioned below in the description of the figures and / or shown on their own in the figures are not only in the respectively specified combination, but also in others

Combinations or can be used alone without departing from the scope of the invention. Show:

Fig. 1 shows an exemplary embodiment of a motor vehicle according to the

improved concept;

2 shows a schematic flow diagram of an exemplary embodiment of a method according to the improved concept; and

3 shows various aspects of a further exemplary embodiment

a method according to the improved concept.

1 shows an exemplary embodiment of a motor vehicle 1 according to the improved concept. In particular, the motor vehicle 1 has a

Energy store 2, which can be designed, for example, as a lithium ion battery, and a battery management system 3 based on the improved concept in order to control operation of the energy store 2.

The battery management system 3 has a state of charge sensor 4 which is set up, for example, to determine a cell voltage of the energy store 2. The battery management system 3 also has a control unit 5 which is connected to the charge state sensor 4 in order to receive a sensor signal generated by the charge state sensor 4 as a function of the determined cell voltage. The control unit 5 can depending on the sensor signal

Determine the state of charge of the energy store 2, for example by comparison with a predetermined charge characteristic of the energy store 2. The charge characteristic can, for example, be stored in an optional storage medium 6 of the

Battery management system 3 be stored.

The storage medium 6 can for example also contain a computer program according to the improved concept. The control unit 5 can, in particular, have read access to the storage medium 6 in order to carry out a method according to the improved concept.

For further details of the function of the battery management system 3, reference is made to the explanations relating to FIGS. 2 and 3. FIG. 2 shows a flow chart of an exemplary embodiment of a method according to the improved concept, as it is, for example, from a

Battery management system 3, as shown in FIG. 1, can be executed.

A state of charge area 7 of the energy store 2 is shown by way of example as a bar. The state of charge range 7 has a minimum value 7a and a

Maximum value 7b, the minimum value 7a, for example, corresponding to 0% and the maximum value 7b, for example, corresponding to 100% of the maximum available charging capacity of the energy store 2.

In step 13 of the method, in particular by means of the control unit 5, a

Operating range 8 of the energy store 2 specified. The given

Operating range 8 corresponds, for example, to a part, in particular to one

coherent part, of the state of charge area 7, which is arranged, for example, centrally within the state of charge area 7. Accordingly, an upper limit value 8b of the operating range from the maximum value 7b of the

State of charge range 7, for example, the same distance as a lower limit value 8a of the operating range 8 from a minimum value 7a of the state of charge range 7. It should be noted that the initial position of the operating range is not relevant for the improved concept and is only assumed to be typically symmetrical.

The recess in the areas between the state of charge values 7b and 8b

or 7a and 8a when specifying the operating range 8 is based in particular on the fact that the lithium-ion battery of the energy store 2 can show increased aging in the case of particularly small and particularly large states of charge.

This is also reflected by a first aging function 9 and a second aging function 10, which can be stored, for example, on the storage medium 6 and are shown schematically in Figure a) of FIG. 2. The aging functions 9, 10 assign a respective aging index to a state of charge value SOC in percent. The aging functions 9, 10 can be determined empirically, for example. The first aging function 9 is in particular at a maximum at a state of charge of 0%, then drops and is then approximately negligibly small at values of 40% or greater. In contrast, the second aging function 10 is at very low state of charge values negligible, increases at values from approx. 30 to 40% and finally reaches its absolute maximum at 100%.

The first aging function 9 can, for example, describe corrosion of a copper conductor on an anode of the energy store 2, which can lead to increased aging at low cell voltages, that is to say in particular at a low state of charge. The second aging function 10, on the other hand, can, for example, be a

Describe electrolyte aging of the energy store 2, which occurs at higher

Cell voltages and correspondingly higher states of charge lead to increased aging of the energy storage device.

In step 14, the control unit 5 can, for example, determine a first and a second cumulative aging index 11, 12 based on the aging functions 9, 10 and an actual usage behavior of the energy store 2. In figure b) of FIG. 2, a time profile of the cumulative aging indicators 11, 12 is shown as an example. The time course of the cumulative aging indicators 11, 12 can be determined, for example, in such a way that the state of charge of the energy store 2 is determined by means of the state of charge sensor 4 and the control unit 5 in accordance with a sampling scheme, in particular in accordance with a predetermined sampling rate, and respective functional values in accordance with the aging functions 9, 10 be calculated. The function values are summed up over an operating period of the energy store 2, for example, and rise accordingly, the rise in the different accumulated aging indicators over time depending on the specific user behavior. In particular, in the example shown, the first cumulative aging index increases more strongly the more often or the longer the energy store 2 is in a low state of charge, that is to say in particular in the vicinity of the lower limit value 8a. The second cumulative aging index 12 then rises all the more the more often or the longer the energy store 2 is in a relatively high state of charge, that is to say in particular in the vicinity of the upper limit value 8b.

In the example shown, there is, in particular, user behavior in which the energy store 2 is more frequently in high charge state ranges than in low charge state ranges. This can be the case with motor vehicle 1, for example, when it regularly only covers relatively short distances before energy store 2 is recharged. Correspondingly, the second cumulative aging index rises more strongly over time than the first cumulative aging index 11. The difference between the two aging indexes also increases over time, the difference being calculated from the second cumulative aging index minus the first cumulative aging index 11, for example positive.

In step 15 of the method, the difference between the cumulative aging indicators 11, 12 is determined by means of the control unit 5.

In step 16 of the method, the determined difference is compared with a predetermined maximum difference value. The maximum difference value can correspond, for example, to a maximum tolerated difference between the cumulative aging indicators 11, 12, up to which there is still no reaction by means of an adaptation of the limit values 8a, 8b. This can be advantageous because the difference between the two cumulative aging indicators 11, 12 does not necessarily increase continuously and, in particular, can also decrease depending on user behavior.

If it is determined in step 16 that the difference between the accumulated

Aging indicators 11, 12 is greater than the maximum difference value, the position of the operating range 8 is shifted, for example, in such a way that a smaller increase in the difference is to be expected in the future. The direction of the shift depends on whether the difference is positive or negative, i.e. whether the second cumulative aging index is greater or less than the second cumulative aging index 11.

Optionally, in step 16, the two current limit values 8a, 8b with the corresponding minimum and maximum values 7a, 7b of the

State of charge area 7 are compared. For example, a distance between the upper limit value 8b and the maximum value 7b can be calculated and compared with an associated minimum distance. Correspondingly, a distance between the lower limit value 8a and the minimum value 7a can be determined and compared with a further associated minimum distance.

Different situations are shown in FIG. In figure a) of FIG. 3, the second aging function 10 and the operating range 8 are shown. In Figure b) of FIG. 3, the first aging function 9 and also the operating range 8 are shown.

In figure c) of FIG. 3, the same situation is based on the cumulative

Aging indicators 11, 12 are shown, as they are also shown in Figure b) of FIG. 2 is shown, that is, the second aging index 12 is greater than the first cumulative aging index 11, so that the difference is positive. This suggests a user behavior that tends to assume rather high states of charge. Correspondingly, the operating range 8 is adapted in step 17 of the method, for example, in such a way that an adapted operating range 8 'results in that the two limit values 8a, 8b of the operating range 8 are each reduced by the same value to match the adapted limit values 8a', 8b '

Operating range 8 ‘to get. However, the adaptation can optionally be omitted if it is determined in step 16 that the associated minimum distance between the lower limit value 8a and the minimum value 7a of the state of charge range has already been reached.

By shifting the operating range 8 to smaller values of the state of charge, the specific usage behavior at hand, as shown in Figure c) of FIG.

3 is outlined, increased aging due to the aging function 10

underlying mechanism is reduced, so that less severe aging of the energy store 2 is to be expected.

Figure d) of FIG. 3 shows the opposite situation in which the first cumulative aging index 11 is greater than the second cumulative aging index 12, so that the difference that was formed in step 15 of the method is negative. This suggests a user behavior which is opposite to that shown in Figure c) of FIG. 3, according to which therefore rather low states of charge of the energy store 2 prevail. Correspondingly, as shown in Figures a), b) of Fig. 3, the operating range 8 can be shifted upwards, i.e. to larger values of the state of charge, by the adapted operating range 8 "with associated upper and lower limit values 8a", 8b " to obtain. Here, too, the adaptation can optionally be omitted if the associated minimum distance between the upper limit value 8b and the maximum value 7b of the state of charge range 7 has already been reached.

By shifting the operating range 8 upwards, the specific user behavior is also taken into account in this case and a future rate of aging of the energy store 2 is reduced.

After the adjustment of the operating range 8 in step 17, steps 14, 15 and 16 can be carried out again, so that a continuous adjustment of the Operating area 8 takes place, for example, in order to gradually achieve an optimal position of operating area 8 in accordance with the current user situation or current user behavior.

According to the improved concept, the aging of the energy store can thus be achieved by adapting the position of the operating range, for example using a

Software function of the control unit. By the accumulated

Aging key figures are determined, the software function determines, for example, the optimal position of the operating range with regard to aging by adding two

Damage sizes are determined and compared. If faster aging is identified at the upper limit of the operating range than at the lower limit, the position of the operating range is shifted downwards, otherwise it is shifted upwards.

The aging of energy stores, for example lithium-ion batteries, is reduced according to the improved concept by a position of the operating area that is adapted to the actual conditions of use. As a result, the battery life can be increased even with very different user behavior. This increase in service life is advantageous, for example, for various electronic devices, for example computers or smartphones, and in particular for fully electric motor vehicles or plug-in hybrids. The improved concept can, however, be used to advantage for all corresponding aging mechanisms

Apply subject to storage batteries for electrical energy.

Reference number

1 motor vehicle

2 energy storage

3 battery management system

4 charge level sensor

5 control unit

6 storage medium

7 State of charge area

7a minimum value

7b maximum value

8 operating range

8 ‘, 8“ adapted operating range

8a lower limit value

8b upper limit

8a ‘, 8a“ adjusted lower limit value 8b ‘, 8b“ adjusted upper limit value 9, 10 aging functions

1 1, 12 cumulative aging indicators 13 to 17 process steps

Claims

1. A method for operating an energy store (2) for electrical energy, wherein the energy store (2) has a state of charge area (7) and a

Operating range (8) is specified, which is within the state of charge range (7);

characterized in that

one or more aging indicators (11, 12) accumulated over an operating period of the energy store (2) are determined by means of a control unit based on one or more predetermined aging functions (9, 10);

an upper limit value (8b) and / or a lower limit value (8a) des

The operating range (8) is adapted by means of the control unit as a function of the one or more cumulative aging indicators (11, 12) in order to define an adapted operating range (8, 8 ″); and

a state of charge of the energy store (2) is limited to the adapted operating range (8 ‘, 8“) by means of the control unit.

2. The method according to claim 1,

characterized in that by means of the control unit (5)

a variable that is dependent on the accumulated aging indicators (11, 12) is compared with an associated predetermined maximum value; and

depending on a result of the comparison to the adjusted

Define the operating range (8 ‘, 8"),

- The lower and the upper limit value (8a, 8b) are each reduced or increased; or - the lower limit value (8a) is increased and the upper limit value (8b) is not changed; or

- the upper limit value (8b) is reduced and the lower limit value (8a) is not changed.

3. The method according to claim 1,

characterized in that by means of the control unit (5)

using a first aging function (9) of the predetermined aging functions

(9, 10) a first cumulative aging index (11) is determined;

using a second aging function (10) of the specified

Aging functions (9, 10) a second cumulative aging index (12) is determined;

a difference between the first and the second cumulative aging index (11, 12) is determined; and

if the difference is greater than a specified maximum difference value in order to define the adapted operating range (8 ‘, 8"),

- The lower and the upper limit value (8a, 8b) of the operating range (8) are increased; or

- The lower and the upper limit value (8a, 8b) of the operating range (8) are reduced.

4. The method according to claim 3,

characterized in that

the first aging function (9) relates to an aging behavior of the energy store (2) in a first partial area of the state of charge area (7);

the second aging function (10) relates to an aging behavior of the energy store (2) in a second sub-area of the state of charge area (7); and the first sub-area lies below the second sub-area.

5. The method according to any one of claims 1 to 4,

characterized in that by means of the control unit (5)

for a variety of repetitions each

- A value of the state of charge of the energy store (2) is determined; - for each of the one or more aging functions (9, 10)

Function value is determined for the value of the state of charge;

- each of the function values is added to a respective sum variable; and the one or more cumulative aging indicators (11, 12) are determined as a function of the sum variables.

6. The method according to any one of claims 1 to 5,

characterized in that

a size of the adapted operating range (8 ‘, 8“) is equal to a size of the operating range (8).

7. The method according to any one of claims 1 to 6,

characterized in that by means of the control unit (5)

a first distance of the lower limit value (8a) from a minimum value (7a) of the state of charge range (7) is determined and / or a second distance of the upper limit value (8b) is determined from a maximum value (7b) of the state of charge range (7);

the lower limit value (8a) is not reduced to define the adapted operating range (8 ', 8 ") if the first distance is smaller than a specified first minimum distance and / or the upper limit value (8b) is not reduced to define the adapted operating range (8 ', 8 ") is increased if the second distance is greater than a specified second minimum distance.

8. Battery management system for an energy store (2) for electrical energy, the energy store (2) having a state of charge area (7), including the battery management system (3)

a state of charge sensor (4), set up to measure a state of charge of the

To determine energy store (2) and to generate a sensor signal based thereon; and

a control unit (5) set up to limit operation of the energy store (2) as a function of the sensor signal to a predetermined operating range (8) which is within the state of charge range (7);

characterized in that the control unit (5) is set up to using one or more predetermined aging functions (9, 10) to determine one or more cumulative aging indicators (11, 12);

an upper limit value (8b) and / or a lower limit value (8a) of the

Adapt the operating range (8) as a function of the one or more cumulative aging indicators (11, 12) in order to define an adapted operating range (8 ‘, 8 ″); and

the state of charge depending on the sensor signal on the adapted

Restrict the operating range (8 ‘, 8“).

9. Motor vehicle, having an energy store (2) for at least partially electrical driving of the motor vehicle (1),

characterized in that

the motor vehicle (1) has a battery management system (3) for the energy store (2) according to claim 8.

10. Computer program with commands which are used when executing the

Computer program by means of a computer system, in particular by means of a control unit (5) of a battery management system (3) according to claim 8, causing the computer system to carry out a method according to one of claims 1 to 7.