Method and apparatus for charging a multi-cell battery

Abstract

The invention relates to a method for charging a multi-cell battery 20, in which a battery voltage U0 of the battery 20 is detected before charging begins, a charge-state-dependent charging voltage characteristic curve 10 is determined starting from the detected battery voltage U0, and a charging voltage UL is open-loop and / or closed-loop controlled in a charge-state-dependent manner on the basis of the determined charging voltage characteristic curve 10. Furthermore, the invention relates to a device 1 for charging a multi-cell battery 20.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for charging a multi-cell battery. [Background technology]

[0002] Lithium-ion cells can only accept a certain charging current, depending on their temperature, duration of operation, and state of charge (SOC). Furthermore, the limiting current varies with the state of health (SOH) of the lithium-ion cells. A further challenge is that battery systems typically contain multiple battery cells connected in series or parallel, each potentially having different temperatures, states of charge, and / or states of health. Therefore, it is typically necessary to know the state of charge and state of health of all battery cells in the system, as well as the coldest and hottest points of the battery, at any given time. This also involves knowing the temperature gradient within the battery cells to actually determine the coldest and hottest points in the entire battery system. These two points, along with the state of charge and state of health of each battery cell, determine the maximum possible charging current at any given time. Furthermore, because a fully discharged battery cell can briefly accept a current higher than the maximum possible steady-state current, the temporal response of the battery cells to the charging current must be known.

[0003] It is known that the maximum possible charge current for a lithium-ion cell can be determined using a three-electrode cell by adjusting the anode potential under load. This is only possible with a three-electrode cell equipped with a reference electrode. As degradation progresses, the system experiences a decrease in charge current characteristics proportional to the decrease in cell capacity or increase in internal resistance (see, for example, Non-Patent Document 1 and Patent Document 1).

[0004] It is further known that for a fully discharged battery cell, a maximum pulse current for each state of charge can be determined using a three-electrode cell. This is known, for example, from US Pat. No. 5,629,499, which describes a method for charging a battery. In this method, a number of starting states of charge and a number of ambient temperatures are provided. For each combination of one of the starting states of charge and one of the ambient temperatures, a reference charge current curve for charging the corresponding battery is recorded and saved as a reference charge current characteristic.

[0005] Furthermore, it is known that charging current characteristics that depend on temperature, state of charge, and pulse duration are repeatedly applied to the battery to test for adverse effects, and then the system is adapted accordingly. Rather than reacting to degradation of battery cells in the system, it is common to initially design a safety margin for the charging current.

[0006] Generally, in the initial state before charging, the state of charge (SOC), state of health (SOH) and temperature of the battery cells in a typical battery are either not known, cannot be accurately determined or must be determined by additional measures. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Publication No. 102016007479 [Patent Document 2] German Patent Publication No. 102019003465 [Non-patent literature]

[0008] [Non-Patent Document 1] Sieg et al., Journal of Power Sources 427 (2019) 260-270, doi: https: / / doi.org / 10.1016 / j.jpowsour.2019.04.047 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved method and apparatus for charging multi-cell batteries. [Means for solving the problem]

[0010] According to the invention, this problem is solved by a method having the features of claim 1 and by a device having the features of claim 7. Advantageous embodiments of the invention emerge from the dependent claims.

[0011] In particular, a method for charging a multi-cell battery is provided in which the battery voltage of the battery is detected before charging begins, a charging voltage characteristic curve that depends on the amount of charge is determined starting from the detected battery voltage, and the charging voltage is open-loop controlled and / or closed-loop controlled in a manner that depends on the amount of charge based on the determined charging voltage characteristic curve.

[0012] Furthermore, in particular, a device for charging a multi-cell battery is provided, which includes a control device configured to receive a battery voltage of the battery detected before the start of charging, determine a charge-level-dependent charge voltage characteristic curve starting from the detected battery voltage, and perform open-loop and / or closed-loop control of the charge voltage in a charge-level-dependent manner based on the determined charge voltage characteristic curve.

[0013] The method and device enable open-loop and / or closed-loop controlled charging of a battery, starting from a battery voltage detected before charging. This is achieved by determining a charge-dependent charge voltage characteristic curve starting from the battery voltage detected before charging. Starting from the determined charge voltage characteristic curve, the charge voltage is controlled in an open loop and / or closed loop. In particular, the charge voltage characteristic curve is used to determine the value of the charge voltage characteristic curve starting from the charge amount, which determines the charge voltage. In this case, the charge amount is, in particular, the charge amount added to charge the battery. That is, before charging, the value of this charge amount is, in particular, equal to zero, and at the end of charging, a target charge amount is achieved. To this end, the control device receives, in particular, the already added charge amount as an input value, determines the value of the charge voltage characteristic curve starting from the already added charge amount, and uses this value as the current target value for the charge voltage. This process is repeated during charging, so that the target value for the charge voltage is continuously determined. Charging is terminated in particular when a given charge amount or the end value of the charging voltage characteristic curve is reached.

[0014] An advantage of the present method and apparatus is that only a single measurement of the battery voltage needs to be performed, and no further measures such as determining the battery cell voltage, battery cell temperature and current state of charge are required.

[0015] The device can be used in a battery system, for example, to charge the batteries of the battery system. In particular, the device can be arranged and used in a vehicle, in particular an automobile, for example an electric or hybrid automobile. However, the vehicle can also essentially be any other land, rail, water, air or space vehicle, for example a drone or an air taxi.

[0016] The battery cells are in particular lithium ion battery cells, and the battery is in particular made up of a plurality of such lithium ion battery cells.

[0017] Parts of the device, in particular the control device, may be configured individually or collectively as a combination of hardware and software, for example as program code running on a microcontroller or microprocessor, but it is also possible to provide that the parts are configured individually or collectively as application specific integrated circuits (ASICs) and / or field programmable gate arrays (FPGAs).

[0018] In one embodiment, the detected battery voltage is incorporated as a parameter into a stored charging voltage characteristic curve that can be parameterized using the battery voltage to determine the charging voltage characteristic curve. This minimizes the burden of determining the charging voltage characteristic curve, since it is not necessary to determine the complete charging voltage characteristic curve, but rather it is only necessary to parameterize the parameterizable charging voltage characteristic curve that has already been determined and stored. This parameterizable charging voltage characteristic curve can be stored, for example, in a memory of the control device and retrieved from this memory as needed. By incorporating the detected battery voltage, the charging voltage characteristic curve is then fully parameterized, so that the relationship between the charge amount and the charging voltage is known for each charge amount or can be determined using the parameterized charging voltage characteristic curve. These charging voltage characteristic curves and the parameterizable charging voltage characteristic curve are identical, differing in particular only in the parameter "battery voltage" (i.e., the battery voltage is already incorporated into the charging voltage characteristic curve).

[0019] In one embodiment, the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve are determined or pre-determined taking into account a given no-load voltage curve of the battery cells, a given limit voltage curve of the battery cells, and the battery cell topology. This ensures that the charging voltage characteristic curve does not assume a value that would lead to exceeding the limit voltage of the battery cells at any time during charging of the battery. In particular, the limit voltage is the voltage above which damage to the battery cells occurs, particularly due to the lithium plating process. On the other hand, the charging voltage determined using the charging voltage characteristic curve should be selected to be greater than the current no-load voltage of the battery cells. Furthermore, to obtain the battery voltage from the observation of the individual battery cells, the topology (series and / or parallel) of the individual battery cells is observed. These limit voltage curves and no-load voltage curves can be determined, for example, based on a series of empirical experiments and / or by simulation using methods known per se, and then applied to the battery cells accordingly.

[0020] In an improved embodiment, the determination of the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve is carried out by: For a given final state of charge, the difference between a given limit voltage curve and a given no-load voltage curve is or has been determined; Starting from a starting voltage determined for a given starting state of charge using the determined difference and the no-load voltage curve, a progression of the characteristic curve between a given starting state of charge and a given final state of charge is determined or has been determined; a charging voltage characteristic curve and / or a parameterizable charging voltage characteristic curve is determined or has been determined starting from the determined difference, the determined characteristic curve profile and the topology of the battery cells in the battery; It is stipulated that:

[0021] This particularly achieves that the voltage of the battery cell between a given starting charge state and a given final charge state of the battery cell does not exceed the limit voltage at any time during charging. These given starting charge states and given final charge states are particularly universally assigned values ​​for all battery cells. The given starting charge state can be, for example, 5% or 20% of the maximum charge capacity of the battery cell. The given final charge state can be, for example, 80% of the maximum charge capacity of the battery cell. In this case, the given starting charge state and given final charge state are values ​​used to determine the charge voltage characteristic curve and / or the parameterizable charge voltage characteristic curve, and these values ​​do not need to correspond to the real actual values ​​of each battery cell.

[0022] In one embodiment, it is provided that the curve of the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve is linear and / or that the curve of this characteristic curve is determined or has been determined as a linear curve. This makes it possible to provide a particularly easily determined charging voltage characteristic curve. In particular, the charging voltage characteristic curve can have a curve of approximately the following shape: Charge voltage = f(charge amount) = detected battery voltage + determined difference + voltage gradient x charge amount

[0023] This voltage gradient can then be determined, in particular, by adding the determined difference to the respective no-load voltages at the starting state of charge (e.g., 5% or 20%) and at the final state of charge (e.g., 80%), and determining the gradient in terms of charge between the resulting values ​​and the amount of charge between the starting state of charge and the final state of charge.

[0024] In principle, the course of the charging voltage characteristic curve and / or the parameterized charging voltage characteristic curve can also be configured with other shapes, such as, for example, a quadratic function, a polynomial function, a power function, an exponential function, a logarithmic function, etc.

[0025] In one embodiment, when determining the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve, an offset related to the temperature difference between the battery cells connected in series, an offset related to the temperature difference between the battery cells connected in parallel, and an offset related to the difference in the state of charge between the battery cells connected in series are taken into account or are specified to have been taken into account. This allows for a safety margin related to the temperature difference and / or the difference in the state of charge. These offsets are taken into account, in particular, in the form of pre-exponential factors.

[0026] Further features of the device embodiment will become apparent from the description of the method embodiment, in which case the advantages of the device are the same as those of the method embodiment.

[0027] Furthermore, a battery system is provided that includes at least one device according to one of the implementations described herein.

[0028] The invention will be explained in more detail below on the basis of advantageous embodiments with reference to the drawings. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram of one embodiment of an apparatus for charging a multi-cell battery; [Figure 2] An example of a battery and a schematic diagram of the connection between the battery and a charging control unit realized using this device. [Figure 3] Schematic diagram to clarify the determination form of the charge voltage characteristic curve [Figure 4a] FIG. 1 is a graph showing electrical variables over time when a battery is being charged in a simulation to clarify the present invention. [Figure 4b] FIG. 1 is a graph showing electrical variables over time when a battery is being charged in a simulation to clarify the present invention. [Figure 4c]FIG. 1 is a graph showing electrical variables over time when a battery is being charged in a simulation to clarify the present invention. [Figure 4d] FIG. 1 is a graph showing electrical variables over time when a battery is being charged in a simulation to clarify the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] 1 shows a schematic diagram of one implementation of an apparatus 1 for charging a multi-cell battery 20. In particular, the apparatus 1 can be part of a battery system. The apparatus 1 implements the methods described in this disclosure.

[0031] The device 1 comprises a control device 2. The control device 2 comprises, for example, a computing device 3 and a memory 4.

[0032] The control device 2 is configured to receive a detected battery voltage U0 of the battery 20 before the start of charging. For this purpose, the battery voltage U0 is detected at the battery 20, for example, by means of a suitable sensor device 22, and sent to the control device 2 as a signal.

[0033] Starting from this detected battery voltage U0, the control device 2 determines a charge voltage characteristic curve 10 that depends on the charge level. For this purpose, for example, corresponding program code is executed on the computing device. The control device 2 determines the charge voltage U0 based on the determined charge voltage characteristic curve 10. L The charging voltage U is controlled by open loop or closed loop control depending on the charge amount. L The value of is, for example, the charging voltage U L To this end, in particular, the detected charging current I L It is defined that the additional charge amount Q is detected and / or determined by integrating the charging current I LFor example, a correspondingly configured current sensor (not shown) can be used in or at the inverter 15 to detect this.

[0034] It can be provided that, to determine the charging voltage characteristic curve 10, the detected battery voltage U0 is incorporated as a parameter into a stored charging voltage characteristic curve 11 that is parameterizable using the battery voltage U0. To this end, the computing device 3 retrieves the parameterizable charging voltage characteristic curve 11 from the memory 4 and incorporates the detected or received battery voltage U0 into the parameterizable charging voltage characteristic curve 11, thereby obtaining the charging voltage characteristic curve 10.

[0035] The charging voltage characteristic curve 10 and / or the parameterizable charging voltage characteristic curve 11 are determined based on a given no-load voltage curve OCV of the battery cell 23-x of the battery 20 and a given limit voltage curve U of the battery cell 23-x. max and the connection topology of the battery cells in the battery 20. This will be explained schematically and exemplarily with reference to FIGS.

[0036] 2 shows a schematic diagram of an example of a battery 20 and the connection of the battery 20 and the charge control unit 30 implemented using the device 1. The battery 20 includes six battery cells 23-x connected in parallel in pairs, with the parallel-connected battery cells 23-x connected in series. The charge states and temperatures of the individual battery cells 23-x may differ from each other.

[0037] Figure 3 shows a schematic diagram with voltage U on the vertical axis (Y axis) and state of charge SOC on the horizontal axis (X axis). In this case, we observe an individual battery cell. The no-load voltage curve OCV and limit voltage curve U max The charging voltage curve 10 and / or the parameterizable charging voltage curve 11 (FIG. 1) are then in particular shown to indicate that the course of the voltage of the individual battery cells falls within the limit voltage curve U at any point during charging. maxIn this case, in principle, different suitable curve shapes can be used, as already mentioned above.

[0038] Furthermore, in the improved configuration, in particular, a given limit voltage curve U is calculated for determining the charging voltage characteristic curve 10 (FIG. 1) and / or the parameterizable charging voltage characteristic curve 11 (FIG. 1) for a given final state of charge SOC2. max The difference ΔU between and a given no-load voltage curve OCV is determined or can be defined as having been determined as follows: ΔU=U max (SOC2)-OCV(SOC2)

[0039] SOC2 is selected to be, for example, 80% of the total charge of the battery cell. Furthermore, for a given initial state of charge SOC1, the progression of the characteristic curve between a given initial state of charge SOC1 and a given final state of charge SOC2 is determined, starting from the following starting voltage U1, determined using the determined difference ΔU and the no-load voltage curve OCV: U1 = OCV(SOC1) + ΔU This starting state of charge SOC1 is selected, for example, to be 5% or 20% of the total charge of the battery cell. In this case, it is particularly provided that the course of the characteristic curve is determined as a linear course or has been determined. For this purpose, in particular, the slope of the line X is determined as follows:

[0040]

number

[0041] The charging voltage characteristic curve 10 and / or the parameterizable charging voltage characteristic curve 11 are determined starting from the determined difference ΔU, the determined curve course of the characteristic curves and the topology of the battery cells in the battery.

[0042] Based on the example given above, it can be defined, for example, that the charging voltage characteristic curve 10 has the following shape:

[0043]

number

[0044] In this case, the following equation regarding the additional charge amount Q, particularly regarding the time t, holds true:

[0045]

number

[0046] If the term ΔU·s+s / p has already been determined, a parameterizable charging voltage characteristic curve 11 can be provided. The parameterizable charging voltage characteristic curve 11 can then be stored for retrieval in the memory 4 of the control device 2, retrieved therefrom when necessary, and parameterized with the detected battery voltage U0, so that the charging voltage characteristic curve 10 can be generated therefrom. However, it can also be provided that the charging voltage characteristic curve 10 is determined as early as before charging.

[0047] It should be noted that in this case the charging voltage characteristic curve 10 or the parameterizable charging voltage characteristic curve 11 is or can be defined only in the interval 0 to (SOC2-SOC1). In particular, if the charge quantity Q to be added reaches the value SOC2-SOC1, the charging process is stopped.

[0048] In principle, one or more of the charging voltage characteristic curve 10, the parameterizable charging voltage characteristic curve 11 and the progression of the characteristic curves can be configured non-linearly or can include functions such as, for example, quadratic, polynomial, power, exponential or logarithmic functions.

[0049] When determining the charging voltage characteristic curve 10 and / or the parameterizable charging voltage characteristic curve 11, an offset A related to the temperature difference of the battery cells connected in series is T,s , offset A related to the temperature difference of parallel-connected battery cells T,p and / or an offset A related to the difference in the state of charge of the battery cells connected in series. SOC,s It may be specified that one or more of the following are to be considered or have been considered.

[0050] The charging voltage characteristic curve 10 detailed above then has, in particular, the following shape:

[0051]

number

[0052] The charging voltage characteristic curve 10 represents the limit voltage U max so that the charging voltage U L The purpose of the method and the device 1 is to enable the charging of the battery 20 (FIGS. 1 and 2) in an open-loop and / or closed-loop controlled manner, depending solely on the amount of charge Q already added. The method and the device 1 allow the charging of the battery 20 to be significantly simplified, since it is no longer necessary to know the state of charge, state of health and / or temperature of the individual battery cells, thereby saving, among other things, costs and expenses.

[0053] 4a to 4d show schematic diagrams of example time progressions of electrical variables when charging a battery 20 having six battery cells 23-x in the topology shown in Fig. 2 in one example state, which has, for example, the following values: Battery cell 23-1: SOC=5%, T=25°C Battery cell 23-2: SOC=5%, T=35°C Battery cell 23-3: SOC=10%, T=35°C Battery cell 23-4: SOC=10%, T=40°C Battery cell 23-5: SOC=15%, T=25°C Battery cell 23-6: SOC=15%, T=40°C

[0054] Starting from this initial state, a simulation was performed using a battery cell model, in which charging was performed using the method described in this disclosure in the process of controlling the charging voltage depending on the charge amount. In this case, the charging voltage characteristic curve 10 described above, consisting of the following values, was used as the charging voltage characteristic curve 10.

[0055]

number

[0056] In this simulation, the battery voltage before charging is set as follows: U0=10.284V

[0057] The charge amount between 5% (=SOC1) and 80% (=SOC2) of the maximum charge amount is a characteristic of the battery cell or battery.

[0058] FIG. 4a shows the controlled charging voltage U (in volts) as a function of time t (in seconds). L The graph shows the progression of the battery voltage U0. At the beginning (approximately at t=0 seconds), it is clearly visible that the battery voltage U0 is controlled from below to the target value determined using the charging voltage characteristic curve. Subsequently, the voltage rises continuously over time as the additional charge increases.

[0059] 4b shows the progression of the state of charge SOC (in %) of each battery cell 23-x over time t (in seconds). Since these battery cells 23-x have different state of charge SOCs and temperatures at the start of charging (t=0), the progression of the state of charge SOC over time t is also different. Charging is stopped when one of the battery cells 23-x (battery cell 23-6 in the illustrated example) reaches a state of charge SOC of 80%. This is particularly relevant because the charging voltage characteristic curve used to control the charging voltage is determined based on a final state of charge of 80%.

[0060] 4c illustrates the progression of the instantaneous charging current I (in amperes) of an individual battery cell 23-x over time t (in seconds) and the halving of the charging current of the battery 20. In this simulation example, two battery cells 23-x are always connected in parallel (see FIG. 2), which results in the charging current of the battery 20 being halved, as the current is split approximately equally between the parallel-connected battery cells 23-x.

[0061] 4d illustrates the progression of the cell voltage (in volts) of an individual battery cell 23-x as a function of its state of charge (in % of the total charge or capacity of the battery cell 23-x). max The no-load voltage curves OCV are shown. It can be clearly seen that the curves of the individual battery cells 23-x start at time t=0 from different starting points (5%, 10% and 15% SOC) assumed in this example. Furthermore, none of these curves fall within the limit voltage curve U max As soon as one of the battery cells 23-x reaches a charge state of 80%, the charging process is terminated.

[0062] At the end of the charging process (approximately 72-80% SOC, depending on the curve), these curves and the limit voltage curve U max The remaining interval between the offset A T,s ,A T,p ,A SOC,sIf smaller values ​​for these offsets are selected, these curves can be used to max can be brought closer to The present application relates to the invention described in the claims, but may also include the following configurations as other aspects. 1. A method of charging a multi-cell battery (20), comprising: Before charging begins, the battery voltage (U 0 ) is detected, Detected battery voltage (U 0 ) as a starting point, the charge voltage characteristic curve (10) depending on the charge amount is determined, Based on the determined charging voltage characteristic curve (10), the charging voltage (U L ) is open-loop controlled and / or closed-loop controlled in a manner dependent on the charge amount. 2. In the method according to item 1 above, To determine the charging voltage characteristic curve (10), the detected battery voltage (U 0 ) is stored in this battery voltage (U 0 ) the method is parameterized by a charging voltage characteristic curve (11) which can be parameterized using the 3. In the method according to 1 or 2 above, The charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) are determined based on a given no-load voltage curve (OCV) of the battery cell (23-x), a given limit voltage curve (U) of the battery cell (23-x), max The method is determined or has been determined taking into consideration the connection topology of the battery cells (23-x) and the power supply voltage. 4. In the method according to the above item 3, To determine the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), For a given final state of charge (SOC2), a given limit voltage curve (U max the difference (ΔU) between the voltage curve (V) and a given no-load voltage curve (OCV) is determined or has been determined; At a given initial state of charge (SOC1), starting from the determined difference (ΔU) and the charge start voltage (U1) determined using the no-load voltage curve (OCV), a transition of the characteristic curve between the given initial state of charge (SOC1) and a given final state of charge (SOC2) is determined or has been determined; The method, wherein the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) are determined or have been determined based on the determined difference (ΔU), the determined characteristic curve course and the topology of the battery cells (23-x) in the battery (20). 5. In the method according to any one of 1 to 4 above, the course of the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) is linear; the progression of said characteristic curve is or has been determined as a linear progression. 6. In any one of the methods described in 1 to 5 above, When determining the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), an offset (A) related to the temperature difference of the battery cells (23-x) connected in series is used. T,s ), offset (A) related to the temperature difference of the parallel-connected battery cells (23-x) T,p ) and an offset (A) related to the difference in the state of charge of the battery cells (23-x) connected in series. SOC,s ) is or has been taken into consideration. 7. An apparatus (1) for charging a multi-cell battery (20) comprising a control device (2), This control device (2) detects the battery voltage (U 0 ) and receives this detected battery voltage (U 0 ) as a starting point, a charging voltage characteristic curve (10) depending on the charge amount is determined, and based on this determined charging voltage characteristic curve (10), the charging voltage (U L ) in an open-loop and / or closed-loop manner depending on the charge amount. 8. In the device (1) described in 7 above, The control device (2) further uses the stored battery voltage (U) to determine the charging voltage characteristic curve (10). 0 ) is added to the charging voltage characteristic curve (11), which can be parameterized using the detected battery voltage (U 0 ) as a parameter. 9. In the device (1) described in 8 above, The control device (2) further determines a given no-load voltage curve (OCV) of the battery cell (23-x), a given limit voltage curve (U max ) and the topology of the battery cells (23-x), the device is configured to perform the determination of the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11). 10. In the device (1) described in 9 above, The control device (2) further comprises, in order to determine the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), For a given final state of charge (SOC2), a given limit voltage curve (U ma Determine the difference (ΔU) between x) and the given no-load voltage curve (OCV), Starting from a starting voltage (U1) determined using the determined difference (ΔU) and the no-load voltage curve (OCV) at a given starting state of charge (SOC1), determine the progression of the characteristic curve between a given starting state of charge (SOC1) and a given final state of charge (SOC2); The device is configured to determine a charging voltage characteristic curve (10) and / or a parameterizable charging voltage characteristic curve (11) based on the determined difference (ΔU), the determined characteristic curve course and the connection topology of the battery cells (23-x) in the battery (20). [Explanation of symbols]

[0063] 1 This device 2. Control equipment 3 Computing equipment 4. Memory 10 Charging voltage characteristic curve 11 Parameterizable charging voltage characteristic curves 15 Inverter 20 Battery 22 Sensor Equipment 23-x battery cells 30 Charging control unit A T,s Offset (temperature difference, series) A T,p Offset (temperature difference, parallel) A SOC,s Offset (state of charge difference, series) Q Charge amount I current I L charging current m Slope of the current-voltage curve OCV No-load voltage curve SOC State of Charge SOC1 Starting state of charge SOC2 Final State of Charge U Voltage U0 Detected battery voltage U L Charging voltage U1 Starting Voltage U max Limiting Voltage Curve ΔU difference X straight line

Claims

1. A method of charging a multi-cell battery (20), comprising: Before the start of charging, the battery voltage (U ０ ) is detected, Detected battery voltage (U ０ ) is used as a starting point to determine the charge voltage characteristic curve (10) depending on the charge amount, Based on the determined charging voltage characteristic curve (10), the charging voltage (U Ｌ ) is open-loop controlled and / or closed-loop controlled in a manner dependent on the charge amount.

2. 10. The method of claim 1, To determine the charging voltage characteristic curve (10), the detected battery voltage (U ０ ) is stored, this battery voltage (U ０ ) is incorporated as a parameter into a charging voltage characteristic curve (11) which can be parameterized using the

3. 3. The method of claim 2, The charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) are determined based on a given no-load voltage curve (OCV) of the battery cell (23-x), a given limit voltage curve (U ｍａｘ ) and the connection topology of the battery cells (23-x).

4. 4. The method of claim 3, To determine the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), For a given final state of charge (SOC), a given limit voltage curve (U ｍａｘ ) and a given no-load voltage curve (OCV) is determined or has been determined; At a given initial state of charge (SOC1), starting from the determined difference (ΔU) and the charge start voltage (U1) determined using the no-load voltage curve (OCV), a transition of the characteristic curve between the given initial state of charge (SOC1) and a given final state of charge (SOC2) is determined or has been determined; The method is characterized in that the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) are determined or have been determined based on the determined difference (ΔU), the determined characteristic curve course and the topology of the battery cells (23-x) in the battery (20).

5. The method according to any one of claims 1 to 4, the course of the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) is linear; the progression of said characteristic curve is or has been determined as a linear progression.

6. The method according to any one of claims 1 to 4, When determining the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), an offset (A) related to the temperature difference of the battery cells (23-x) connected in series is used. Ｔ，ｓ ), an offset (A) related to the temperature difference of the battery cells (23-x) connected in parallel Ｔ，ｐ ) and an offset (A ＳＯＣ，ｓ ) is or has been taken into consideration.

7. A device (1) for charging a multi-cell battery (20) comprising a control device (2), This control device (2) detects the battery voltage (U ０ ) and receives the detected battery voltage (U ０ ) as a starting point, a charging voltage characteristic curve (10) depending on the charge amount is determined, and based on this determined charging voltage characteristic curve (10), the charging voltage (U Ｌ ) in an open-loop and / or closed-loop manner depending on the charge amount.

8. 8. The device (1) according to claim 7, The control device (2) further uses the stored battery voltage (U) to determine the charging voltage characteristic curve (10). ０ ) is used to calculate the detected battery voltage (U ０ ) as a parameter.

9. 9. The device (1) according to claim 8, The control device (2) further determines a given no-load voltage curve (OCV) of the battery cell (23-x), a given limit voltage curve (U ｍａｘ ) and the topology of the battery cells (23-x) is taken into account to determine a charging voltage characteristic curve (10) and / or a parameterizable charging voltage characteristic curve (11).

10. 10. The device (1) according to claim 9, The control device (2) further comprises, in order to determine the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), For a given final state of charge (SOC), a given limit voltage curve (U ｍａ x) and the given no-load voltage curve (OCV), Starting from a starting voltage (U1) determined using the determined difference (ΔU) and the no-load voltage curve (OCV) at a given starting state of charge (SOC1), determine the progression of the characteristic curve between a given starting state of charge (SOC1) and a given final state of charge (SOC2); The device is configured to determine a charging voltage characteristic curve (10) and / or a parameterizable charging voltage characteristic curve (11) starting from the determined difference (ΔU), the determined characteristic curve course and the topology of the battery cells (23-x) in the battery (20).

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