DE102020132625A1 - Method and control device for controlling an adjustment of states of charge, and motor vehicle - Google Patents

Abstract

The invention relates to a method for adjusting the state of charge of two battery units (16, 20) of a battery (12), with the first battery unit (16) being assigned a first voltage (U1) and the second battery unit (20) being assigned a second voltage (U2'). is, the adjustment of the states of charge being carried out in such a way that the first and second voltage (U1, U2') after the adjustment match at least within a specific first tolerance range, the first voltage (U1) assigned to the first battery unit (16) exceeding a measured value represents the first voltage (U1) that can be tapped from the first battery unit (16). A first characteristic diagram (26) is assigned to the first battery unit (16) and a second characteristic diagram (28) is assigned to the second battery unit (20), and the second voltage (U2') assigned to the second battery unit (20) represents a normalized second voltage (U2'), which is provided by providing a conversion rule (F) as a function of the first and second characteristics map (26, 28) and a measured second voltage (U2) that can be tapped across the second battery unit (20) in accordance with the provided conversion rule (F) is normalized.

Description

The invention relates to a method for adjusting the state of charge of at least two battery units of a battery for a motor vehicle, the at least two battery units comprising a first battery unit which has at least one first battery cell and a second battery unit which has at least one second battery cell. A first voltage is assigned to the first battery unit and a second voltage is assigned to the second battery unit, with the adjustment of the states of charge being carried out in such a way that the first and second voltage after the adjustment match at least within a specific first tolerance range, the first voltage assigned to the first battery unit represents a measured first voltage that can be tapped across the first battery unit. Furthermore, the invention also relates to a control device for controlling an adjustment of charging states, as well as a motor vehicle with such a control device.

The adjustment of charge states is also known under the term balancing. Numerous different balancing strategies are known from the prior art. For example, describes the EP 1 685 622 B3 an equilibrium charging method for cells, which is based on determining the amount of energy stored in each cell. The states of charge of the cells are adjusted in this way until the same state of charge is obtained. The adjustment does not affect the cells with the greatest charge lead or the greatest charge backlog.

Furthermore describes the EP 2 730 006 B1 a balancing method based on differential capacity curves. Such a curve is assigned to each cell module or each individual cell. These curves are used to determine the state of charge or state of charge differences of the respective cells.

The invention is located in particular in the field of voltage-based balancing methods. Voltage-based cell balancing usually ensures that all cells are kept at the same voltage level, for example by discharging cells with higher voltages to the level of the other cells. So far, however, this has only worked if the cells are of the same type, because this is the only way that the cells in the system all behave in the same way. For this reason, cells of the same type have always been installed when a cell or module is replaced. In other words, if cells or modules are exchanged, it must be ensured that cells of the same type are installed again in order to be able to carry out such voltage-based cell balancing. This can be problematic after a few years, especially in the case of repairs, because the cells are no longer available. If cells of a different type are installed during the exchange, the different characteristics can lead to the balancing increasing the charge differences in the cells instead of equalizing them. As a result, some cells would prematurely reach the lower end of the voltage range in the subsequent discharging process, and the energy that could be drawn would therefore drop.

There are also other balancing methods, such as charge-based balancing, which can be carried out independently of the cell type. However, charge-based balancing has the disadvantage that it is generally significantly less accurate than voltage-based balancing, so that charge-based balancing cannot be used in the long term.

The object of the present invention is therefore to provide a method, a control device and a motor vehicle which enable the most precise possible adjustment of the state of charge, even for battery cells of different cell types.

This object is achieved by a method, a control device and a motor vehicle with the features according to the respective independent patent claims. Advantageous configurations of the invention are the subject matter of the dependent patent claims, the description and the figures.

In a method according to the invention for adjusting the state of charge of at least two battery units of a battery for a motor vehicle, the at least two battery units comprising a first battery unit which has at least one first battery cell and a second battery unit which has at least one second battery cell, and wherein the a first voltage is assigned to the first battery unit and a second voltage is assigned to the second battery unit, the adjustment of the states of charge takes place in such a way that after the adjustment the first and second voltages match at least within a specific first tolerance range, the first voltage assigned to the first battery unit being a represents the first voltage that can be tapped off across the first battery unit. Furthermore, a first characteristic diagram is assigned to the first battery unit and a second characteristic diagram is assigned to the second battery unit, the second voltage assigned to the second battery unit representing a normalized second voltage that is provided is provided in that a conversion rule is provided as a function of the first and second characteristic diagrams and a measured second voltage that can be tapped across the second battery unit is normalized in accordance with the provided conversion rule.

In this way, voltage-based balancing can advantageously also be implemented for battery cells of different types, in particular battery cells with different voltage levels with the same state of charge or energy. Even if the cell voltages differ in a balanced battery, maximum energy that can be drawn is thus ensured. This can prevent the charge differences from being increased by cell balancing. With the method described, it is thus advantageously possible to also operate cells of different types in a mixed construction and still use cell balancing, in particular voltage-based balancing, for meaningful charge equalization. In this way it can be ensured that the entire capacity of the respective cells can be used.

For example, if old cells, such as the first battery cell, are fully charged at a voltage of 4,100 millivolts, but new cells, such as the second battery cell, at a voltage of 4,200 millivolts, it would be counterproductive to charge the new cells to 4,100 millivolts as well discharged, since they then reach the lower limit of the voltage range too early during the subsequent discharge and during operation of the battery, and the energy that can be drawn falls as a result. According to the method according to the invention, it is now advantageously possible not to use the actual voltage of 4,200 millivolts that can be tapped across these new cells for the voltage-based cell balancing, but instead a normalized voltage. For example, the 4,200 millivolts can be normalized to the voltage of the old cells for this state of charge range, in this case full charge, using the conversion rule, for example by multiplying by a factor. The balancing, in particular the described voltage-based balancing, then simply uses this normalized voltage instead of the actual one. The first actual voltage value and the normalized second voltage value can then be adjusted to one another, for example to the value 4100 millivolts. In fact, the new cell would then have a voltage of 4,200 millivolts, which corresponds to the voltage value when fully charged. This means that both the old and the new cells are fully charged and their state of charge is the same. Even if the actual cell voltages in the fully charged state deviate from one another, this advantageously ensures maximum energy that can be drawn for each of the cells.

The first and second battery units are preferably connected in series with one another. Each battery unit can in turn have one or more battery cells. In this case, the battery cells assigned to the same battery unit can also be arranged in a parallel connection to one another. A parallel connection of several battery cells behaves like a single battery cell with a larger capacity. Mathematically, such a parallel connection is treated like a single battery cell. The battery units can therefore be individual battery cells or several battery cells connected in parallel, which are mathematically treated as a single battery cell.

The voltages assigned to the respective battery units are therefore adjusted to one another, with the actual voltage that can be tapped via this second battery unit not being used for the second battery unit, but a normalized voltage calculated from this voltage. For the first battery unit, on the other hand, the actual voltage that can be tapped off via this first battery unit is used. Furthermore, the adjustment can be carried out, for example, in such a way that the higher of the two voltages is adjusted to the lower of the two voltages. In the case of more than two battery units, the corresponding voltages can be adjusted to the lowest voltage value. This can be done, for example, by selectively discharging the battery unit with the higher voltage, for example via a discharge resistor that can be temporarily connected in parallel. The fact that the first and second voltages also match at least within a specific first tolerance range after the adjustment is intended to mean that the first and second voltages are adjusted preferably within the scope of the measurement accuracy or a desired accuracy. For example, this tolerance range can be defined by a specific decimal place. For example, such a tolerance range in the range of +/- 0.1 volts or +/- 0.05 volts or +/- 0.01 volts or +/- 0.005 volts or generally in a deviation range from a maximum of 1 millivolt to 0. 1 volt, depending on the desired or achievable accuracy.

The state of charge or states of charge relate to the battery units or to the first and second battery cells. According to a further advantageous refinement of the invention, the first and the second characteristic map each provide a cell-type-specific assignment which determines different assigns corresponding first or second voltages that can be tapped to th state of charge areas via the first or second battery unit. In other words, such a characteristic map can represent the dependency between the current state of charge of a battery cell or a battery unit and the voltage that can be tapped via this battery cell. The voltages can in turn be either an open-circuit voltage, which is also referred to as an open-circuit voltage, or an operating voltage. In the second case, the characteristic diagrams can also include other parameters such as the internal resistance of the battery cells in question. In addition, another parameter of the characteristic diagrams described can also represent the temperature. In other words, the assignments mentioned can be provided for respective corresponding temperature ranges.

In this case, the characteristic diagrams can represent characteristic curves and/or characteristic curve diagrams and/or assignment tables. Such characteristic diagrams can thus advantageously be used to determine how the respective cell voltages behave in a cell-type-specific manner for corresponding charge state ranges of the cells. By comparing these two characteristic diagrams, a suitable conversion rule can thus advantageously be determined, which allows the second voltage that can be tapped across the second battery unit to be suitably normalized in order to be able to carry out voltage-based cell balancing using this normalized second voltage.

It can also be advantageous if the conversion rule is determined as a function of a specific first state of charge range, in particular with the first state of charge range comprising a current state of charge of the first battery unit. The reason for this is that the two characteristic diagrams, that is to say the first and the second characteristic diagram, can under certain circumstances differ greatly from one another for different charge state ranges. By considering different charge state ranges separately, the conversion rule to be determined can be made much easier. This must then only apply to a specific charge state range. Furthermore, it is also conceivable that, as will be explained in more detail later, such a voltage-based balancing is only carried out in a specific state of charge range, for example only when the battery is fully charged, and is balanced in other areas, for example charge-based. Accordingly, it is then also sufficient, for example, to determine such a conversion rule only for this state of charge range, which corresponds to the fully charged battery. In this way, on the one hand, very precise balancing can be provided and, on the other hand, the computing effort can be minimized.

In a further advantageous embodiment of the invention, the conversion rule is provided at least for the first of the various specific state of charge ranges in such a way that the conversion rule is applied to the second voltage assigned to the specific first state of charge area according to the second characteristic map as a result of the second voltage assigned to the determined first state of charge range according to the first characteristic map delivers first tension. In other words, the conversion rule is designed in such a way that it maps the voltage values of the second characteristic diagram to the voltage values of the first characteristic diagram for a specific state of charge range. If the first voltage according to the first map for a fully charged battery cell is 4,100 millivolts, for example, and the second voltage according to the second map for a fully charged battery cell is 4,200 millivolts, for example, then the conversion rule for this state of charge range of the fully charged battery is such that it can be applied to this second voltage of 4,200 millivolts leads to a normalized second voltage of 4,100 millivolts, ie the value of the first voltage according to the first map for this state of charge range. Such a conversion rule can therefore advantageously be used to normalize the second voltages to the values of the first voltages. The voltage-based balancing is then carried out accordingly with the normalized values, so that this can be carried out in particular as if the battery cells were cells of the same cell type. The main advantage of providing such a conversion rule is that the individual voltage values do not have to be stored as fixed values in the software, which would not be expedient since the function, i.e. the balancing function, is normally also active at slightly lower cell voltages is, for example from 4,000 millivolts, i.e. if the battery is not yet fully charged. The conversion rule therefore makes it possible, instead of calculating with numerous corresponding different voltage values to which the individual cells would have to be balanced, to simply calculate with a factor or offset value, for example, which greatly simplifies the calculations, which are therefore also carried out much faster as a result be able.

It is also particularly advantageous if a factor is provided as a conversion rule that, for the specific first state of charge range, is the ratio of the first voltage assigned according to the first characteristic map to the represents the second voltage associated with the second characteristic diagram, in particular the measured second voltage being multiplied by the factor and the result being provided as the normalized second voltage. The provision of a factor enables the normalized second voltage to be calculated in a particularly simple manner. In addition, such a factor can be provided particularly easily by simply forming the ratio of the respective first and second voltage values for corresponding charge state ranges.

In a further advantageous embodiment of the invention, an offset value is provided as a conversion rule, which represents a difference between the first voltage assigned according to the first characteristic diagram and the second voltage assigned according to the second characteristic diagram for the specific state of charge range, in particular with the measured second voltage being Difference is added and the result is provided as a normalized second voltage. This also makes it possible to determine a conversion rule in a particularly simple manner, since this only requires the formation of a difference. If this difference is added to the second measured voltage, this includes the sign of the difference.

Depending on the requirement, however, the conversion rule can also be designed to be more complex. For example, this can also combine a factor with an offset value. This also makes it possible, for example, for the range of validity of the conversion rule to be extended to a larger range of state of charge.

In a further advantageous embodiment of the invention, it is provided that the adjustment of the states of charge in such a way that the first and second voltage after the adjustment match at least within the specific first tolerance range, takes place for a different from a specific second state of charge range first state of charge, and for the If the state of charge of the first and/or second battery unit is in the second state of charge range, an adjustment is made in such a way that a first energy content assigned to the first battery unit as a function of the current state of charge and the capacity of the first battery unit is assigned to one of the second battery unit as a function of the current State of charge and the capacity of the second battery unit associated second energy content corresponds at least within a predetermined second tolerance range. In other words, charge-based balancing can be carried out in a different state of charge range and the voltage-based balancing described, for example, only in the first state of charge range mentioned above. With charge-based balancing, the energy content of the battery cells or battery units is adjusted to one another. The respective energy contents can in turn be determined based on the respective states of charge and capacities of the battery cells or battery units. This means that charge-based balancing is independent of the cell type. However, charge-based balancing is not as accurate as voltage-based balancing. It is therefore particularly advantageous to combine these two balancing methods with one another, so that voltage-based balancing is carried out at least temporarily. For example, voltage-based balancing can be performed when the battery is fully charged and charge-based balancing can be performed in other state-of-charge ranges. It is particularly advantageous if the voltage-based balancing is carried out, for example, after the battery has been idle, since the first and second voltages can then be taken from the idle voltages of the respective battery cells or battery units, which simplifies the calculations and enables a particularly accurate determination of the state of charge allows.

In a further advantageous embodiment of the invention, the second battery unit of the battery was added to the battery during a unit exchange in which at least one third battery unit was removed from the battery, with the second characteristic map being stored in a control device for controlling the adjustment of the state of charge when the unit was exchanged, in particular wherein the at least one first battery cell is of a first cell type and the at least one second battery cell is of a second cell type different from the first. Different cell types can be characterized in particular by different cell characteristics, such as different voltages with the same charge states, different capacities and/or different cell chemistries. The invention and its embodiments advantageously make it possible to carry out voltage-based cell balancing even when the battery cells are of different cell types. In the event of a unit replacement, for example a battery module replacement, the corresponding characteristic curves can simply be supplied to the control device and stored there. For example, a diagnostic tester, which can be communicatively coupled to the control unit when a unit is exchanged, can be used to inform the control unit, ie the control device, that an exchange is taking place or has taken place and what the characteristics in the new cells look like. With this information, the Control device put the characteristics in relation to each other, for example with a factor by which the current cell voltage of the new battery cells is then multiplied in order to carry out a voltage-based cell balancing. Even if the cell voltages then deviate from one another in a balanced battery, maximum energy that can be drawn is thus ensured.

Furthermore, the invention also relates to a control device for controlling an adjustment of states of charge of at least two battery units of a battery for a motor vehicle, the at least two battery units being a first battery unit which has at least one first battery cell and a second battery unit which has at least one second battery cell , wherein the first battery pack is associated with a first voltage and the second battery pack is associated with a second voltage. Furthermore, the control device is designed to control the adjustment of the state of charge in such a way that the first and second voltage after the adjustment match at least within a specific first tolerance range, the first voltage assigned to the first battery unit representing a measured first voltage that can be tapped across the first battery unit . In addition, a first characteristic map assigned to the first battery unit and a second characteristic map assigned to the second battery unit are stored in the control device, with the control device being designed to provide a conversion rule as a function of the first and second characteristic diagrams and a measured second voltage that can be tapped across the second battery unit to standardize according to the provided conversion rule and to provide the second battery unit assigned second voltage as the second voltage normalized according to the conversion rule.

The advantages described for the method according to the invention and its embodiments apply in the same way to the control device according to the invention. In addition, the method steps mentioned in connection with the method according to the invention and its configurations enable further development of the control device according to the invention through further corresponding physical features.

A control device according to the invention can be designed to carry out a method according to the invention or one of its configurations. The control device can have a data processing device or a processor device that is set up to carry out an embodiment of the method according to the invention. For this purpose, the processor device can have at least one microprocessor and/or at least one microcontroller and/or at least one FPGA (Field Programmable Gate Array) and/or at least one DSP (Digital Signal Processor). Furthermore, the processor device can have program code which is set up to carry out the embodiment of the method according to the invention when executed by the processor device. The program code can be stored in a data memory of the processor device.

Furthermore, the invention also relates to a motor vehicle with a control device according to the invention or one of its embodiments. The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

The battery can be a high-voltage battery, for example. The motor vehicle can be designed as an electric and/or hybrid vehicle, for example. The battery can also have multiple battery modules, which in turn include multiple individual battery cells. The battery cells can also be connected in parallel with one another, in which case only battery cells of the same type are connected in parallel with one another. Such a parallel connection is referred to as a battery unit. However, a battery unit can also consist of just a single battery cell.

The invention also includes the combinations of features of the described embodiments. The invention also includes implementations that each have a combination of the features of several of the described embodiments, unless the embodiments were described as mutually exclusive.

• 1 eine schematische Darstellung eines Kraftfahrzeugs mit einer Steuereinrichtung zum Steuern eines Balancing-Vorgangs gemäß einem Ausführungsbeispiel der Erfindung; und
• 2 ein Ablaufdiagramm zur Veranschaulichung eines Verfahrens zum Balancing einer Batterie gemäß einem Ausführungsbeispiel der Erfindung.

Exemplary embodiments of the invention are described below. It shows:

• 1 a schematic representation of a motor vehicle with a control device for controlling a balancing process according to an embodiment of the invention; and
• 2 a flowchart to illustrate a method for balancing a battery according to an embodiment of the invention.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features that are to be considered independently of one another Invention is, which each develop the invention independently. Therefore, the disclosure is also intended to encompass combinations of the features of the embodiments other than those illustrated. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.

In the figures, the same reference symbols designate elements with the same function.

1 shows a schematic representation of a motor vehicle 10 with a battery 12, in particular a high-voltage battery 12, and a control device 14 for controlling a balancing method according to an embodiment of the invention. In this example, the battery has a first battery unit 16 which, in this example, comprises only one battery cell 18 . Furthermore, the battery 12 has a second battery unit 20 which, for example, also includes only a single battery cell 22 . The battery 12 also has numerous other battery cells that are not explicitly shown here. The balancing method within the scope of the invention is explained below by way of example using these two battery cells 18, 22, but can also be carried out in a completely analogous manner for a number of battery cells. The control device 14 represents a control unit for controlling the balancing process. This control unit 14 has a memory 24 in which characteristic curves 26, 28 for the respective battery cells 18, 22 are stored. These characteristic curves can generally be provided as characteristic diagrams and can also be present in tabular form, for example. A first characteristic curve 26 is now assigned to the first battery cell 18 and the second characteristic curve 28 to the second battery cell 22. These characteristic curves 26, 28 are cell-type-specific and assign a corresponding cell voltage to the respective temperature ranges, for example respective charge state ranges. These assigned cell voltages according to the characteristic curves 26, 28 represent the voltages U1, U2 that can be tapped across the respective battery cells 18, 22.

For battery cells of the same cell type with the same cell characteristics, i.e. the same capacity and the same characteristics, voltage-based cell balancing can be provided simply by adjusting all cells to the same voltage level, for example by balancing cells with higher voltages to the level of the others cells are discharged. Also in 1 such discharge circuits 29, 30 are shown in simplified form by way of example. A first discharge circuit 29 is assigned to the first battery cell 18 and the second discharge circuit 30 to the second battery cell 22. Such a discharge circuit 29, 30 comprises a respective discharge resistor R1, R2, via which the respectively assigned battery cell is discharged by closing the assigned switch S1, S2 18, 22 can be discharged at least in part.

If other cell types were to be installed when cells were exchanged, the different characteristic curves 26, 28 according to previous balancing methods could result in the balancing increasing the charge differences in the cells instead of equalizing them. As a result, some cells would prematurely reach the lower end of the voltage range in the subsequent discharging process, and the energy that could be drawn would therefore drop. This problem can now be advantageously avoided by the invention and its embodiments. This will now be explained in more detail with reference to 2 explained.

2 FIG. 12 schematically shows a flowchart to illustrate a balancing method according to an embodiment of the invention. The method described can be carried out, for example, by the control device 14 . In this case, in step S10, an arrangement is first provided, as is the case, for example, with 1 was described. In particular, a battery 12 can be provided, as is the case, for example, after a module has been replaced. In the course of such a module exchange, for example, a battery cell previously contained in the battery 12 may have been replaced by the second battery cell 22 now present in the battery. The new battery cell 22 can be of a different cell type and can therefore differ from the first battery cell 18 in terms of its cell type. In the course of this module exchange, the control unit 14 may have been informed that such an exchange has taken place and the correspondingly new characteristic curve 28, which is assigned to the new battery cells 22, can be stored in the control unit 14, for example via a diagnostic tester. In other words, when a cell or module is replaced, the appropriate characteristic curves 28 for the new cells 22 are also written into the control unit 14 via the diagnostic tester, for example. Furthermore, a situation is now assumed in which balancing is to be carried out. This can be a state, for example, in which the battery 12 is fully charged or is almost fully charged. The aim of voltage-based balancing is to minimize the differences in cell voltages at a specific operating point, for example when fully charged, at least in the case of cells of the same cell type. However, since the voltage levels of the new and old cells do not match here, since these are cells of a different cell type, A conversion is advantageously carried out here with the aid of the new characteristic curves 28 .

Before the balancing, a conversion rule F is first determined in step S12 as a function of the first and second characteristic curves 26, 28. For example, control unit 14 can relate the two characteristic curves 26, 28 to one another, for example for a predetermined state of charge range, and use this to determine, for example, a factor as an example of such a conversion rule F, by which the current cell voltage of the new cells can then be multiplied. For this purpose, the current first cell voltage U1 of the first battery cell 18 is first measured in step S14 in the course of balancing, as well as the current second cell voltage U2, which drops across the second battery cell 22 . Furthermore, in step S16, a normalized second voltage U2′ is now determined from this measured second voltage U2 by applying the previously determined conversion rule F to the measured voltage U2. For example, the measured second voltage U2 can be multiplied by the factor mentioned, which results in the normalized voltage U2′. The voltage-based cell balancing, according to which the individual cell voltages are matched to one another, is then carried out based on this second normalized voltage U2′ and not on the basis of the voltage U2 actually dropping across the second battery cell 22. For this purpose, a comparison can now first be made in step S18 as to which of the two voltages is greater. If the first voltage U1 is greater than the normalized second voltage U2′, then there is a transition to step S20 and the first battery cell 28 is partially discharged, so that its first voltage U1 is adjusted to the second normalized voltage U2′. If, instead, it is determined in step S18 that the second normalized voltage U2' is greater than the first voltage U1, the system moves to step S22 and the second battery cell 22 is partially discharged, so that the second normalized voltage U2' changes to the value of the first Voltage U1 adjusted. In the event that it is determined in step S18 that the two voltages U1, U2' are the same, balancing does not have to be carried out.

By providing the conversion rule F, which can be provided not only as a factor but, for example, also as an offset, it is advantageously possible for the balancing algorithm, which is executed by the control unit 14, to always ensure that the values U1, U2' are equal as well. can check. A pre-processing of the new cell voltages is therefore conceivable, which results in normalized voltages U2' being available as input variables for the balancing function. In other words, the balancing function can also be carried out as before, only a normalized second voltage value U2′ for the new battery cells 22 is provided in advance, which then takes the place of the actual voltages U2. This method also works if the voltage-based balancing is only carried out when the battery is fully charged and is charged-based balancing in other charge state ranges, for example. In this case, the charge-based balancing does not differ at all, regardless of whether all the cells are of the same type or whether there is a mixed installation. However, since charge-based balancing is less precise, it is all the more advantageous that voltage-based balancing can now be carried out all the more precisely by providing the conversion rule F.

Overall, the examples show how the invention can provide a balancing strategy for lithium-ion batteries with different cell types, which makes it possible for cells of different types to be operated in mixed installation and still use cell balancing for meaningful charge equalization can be. This ensures that the entire capacity of the cells can be used.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1685622 B3 [0002]
• EP 2730006 B1 [0003]

Claims (10)

Method for adjusting the charge states of at least two battery units (16, 20) of a battery (12) for a motor vehicle (10), the at least two battery units (16, 20) having a first battery unit (16), the at least one first battery cell (18) and a second battery unit (20) which has at least one second battery cell (22), wherein the first battery unit (16) is assigned a first voltage (U1) and the second battery unit (20) has a second voltage (U2 ') is assigned, wherein the adjustment of the states of charge takes place in such a way that the first and second voltage (U1, U2') after the adjustment match at least within a specific first tolerance range, the first voltage (U1) assigned to the first battery unit (16) represents a first voltage (U1) that can be measured across the first battery unit (16), characterized in that the first battery unit (16) is assigned a first characteristic diagram (26) and nd the second battery unit (20) is assigned a second characteristic map (28), and the second battery unit (20) assigned second voltage (U2') represents a normalized second voltage (U2'), which is provided by depending on the first and a conversion rule (F) is provided for the second characteristic map (26, 28) and a measured second voltage (U2) which can be tapped across the second battery unit (20) is normalized in accordance with the conversion rule (F) provided. procedure after claim 1 , characterized in that the first and second characteristics map (26, 28) each provide a cell-type-specific assignment, which assigns corresponding first or second voltages (U1, U2) that can be tapped to different specific charge state ranges. Method according to one of the preceding claims, characterized in that the conversion rule (F) is determined as a function of a specific first state of charge range, in particular the first state of charge range comprising a current state of charge of the first battery unit (16). Method according to one of the preceding claims, characterized in that the conversion rule (F) is provided at least for the first of the different specific state of charge ranges in such a way that the conversion rule (F) is applied to the second characteristic map (28) assigned to the specific first state of charge range Voltage (U2) delivers the first voltage (U1) assigned to the specific first state of charge area according to the first characteristics map (26). Method according to one of the preceding claims, characterized in that a factor is provided as the conversion rule (F) which, for the specific first state of charge range, is the ratio of the first voltage (U1) allocated according to the first characteristic diagram (26) to the second characteristic diagram ( 28) associated second voltage (U2), in particular wherein the measured second voltage (U2) is multiplied by the factor (F) and the result is provided as the normalized second voltage (U2'). Method according to one of the preceding claims, characterized in that an offset value (F) is provided as the conversion rule (F) which, for the specific state of charge range, is a difference between the first voltage (U1) assigned according to the first characteristics map (26) and represents the second voltage (U2) assigned according to the second characteristics map (28), in particular the difference being added to the measured second voltage (U2) and the result being provided as the normalized second voltage (U2'). Method according to one of the preceding claims, characterized in that the adjustment of the state of charge such that the first voltage (U1) and the normalized second voltage (U2') after the adjustment match at least within the specific first tolerance range, for one of a specific second State of charge range different first state of charge range, and in the event that a state of charge of the first and / or second battery unit (20) is in the second state of charge range, an adjustment takes place such that one of the first battery unit (16) depending on the current state of charge and the capacity the first energy content assigned to the first battery unit (16) corresponds to a second energy content assigned to the second battery unit (20) depending on the current state of charge of the capacity of the second battery unit (20), at least within a predeterminable second tolerance range. Method according to one of the preceding claims, characterized in that the second battery unit (20) of the battery (12) was added to the battery (12) in a unit exchange in which the battery (12) at least a third battery unit was removed, wherein when Unit exchange, the second characteristic map (28) was stored in a control device (14) for controlling the adjustment of the state of charge, in particular wherein the at least one first battery cell (18) is of a first cell type and the at least one second battery cell (22) is of a second cell type different from the first. Control device (14) for controlling an adjustment of the charge states of at least two battery units (16, 20) of a battery (12) for a motor vehicle (10), wherein the at least two battery units (16, 20) have a first battery unit (16), the at least one first battery cell (18), and a second battery unit (20) which has at least one second battery cell (22), wherein the first battery unit (16) is assigned a first voltage (U1), and the second battery unit (20) a second voltage (U2') is assigned, the control device (14) is designed to control the adjustment of the state of charge in such a way that the first and second voltage (U1, U2') after the adjustment match at least within a specific first tolerance range, wherein the first voltage (U1) assigned to the first battery unit (16) represents a measured first voltage (U1) that can be tapped across the first battery unit (16), characterized in that a first characteristic map (26) assigned to the first battery unit (16) is stored in the control device (14) and a second characteristic diagram (28) assigned to the second battery unit (20) is stored, the control device (14) being designed to depend on providing a conversion rule (F) from the first and second characteristics map (26, 28) and normalizing a measured second voltage (U2) that can be tapped across the second battery unit (20) according to the conversion rule (F) provided and the voltage assigned to the second battery unit (20). provide the second voltage (U2') as the second voltage (U2') normalized according to the conversion rule (F). Motor vehicle (10) with a control device (14). claim 9 .

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