Method and device for determining state of electric energy store

Abstract

The invention relates to a device for determining state information relating to a state of an electrical energy store, said energy store comprising a first partial energy store and a second partial energy store, which can be arranged in a parallel circuit by means of a switching unit. The device is configured to cause the first partial energy store to have a first partial voltage and the second partial energy store to have a second partial voltage, the first partial voltage and the second partial voltage being different from each other. The device is further configured to ascertain equalization information about an equalization process between the first partial energy store and the second partial energy store when the first partial energy store and the second partial energy store are connected together in a parallel circuit; and ascertaining state information about the state of the energy store on the basis of the equalization information.

Description

Technical Field

[0001] This invention relates to a method and a corresponding apparatus for determining the state of an electric energy storage device in a vehicle-mounted power grid. Background Technology

[0002] Electric vehicles have an onboard electrical network that includes one or more electric storage devices for powering the vehicle's electric drive motors. The onboard electrical network may, in particular, have an electric storage device with two or more sub-storage devices that can be connected in series or parallel as needed, for example, to allow the storage device to be charged in a flexible manner with different charging voltages. Summary of the Invention

[0003] Individual energy storage units of an electric energy storage device can age during operation of the vehicle-mounted power grid, thereby impairing, for example, the storage capacity and / or performance responsiveness of the energy storage device. This document aims to determine the (aging) state of an electric energy storage device with multiple sub-energy storage units in an efficient and accurate manner. This objective is achieved by each of the independent claims. Furthermore, advantageous embodiments are described in the dependent claims.

[0004] It should be noted that additional features of a claim subordinate to an independent claim can form an invention independent of the combination of all features of the independent claim, even without the features of the independent claim or only in combination with a subset of the features of the independent claim. This invention can be the technical solution of the independent claim, a divisional application, or a subsequent application. The same applies to the technical teachings described in the specification, which can form an invention independent of the features of the independent claim.

[0005] According to one aspect, an apparatus for obtaining state information regarding the state of an electrical energy storage device, particularly an electrochemical energy storage device (e.g., a lithium-ion based energy storage device). The energy storage device includes a first sub-energy storage device and a second sub-energy storage device. Each sub-energy storage device may have a rated voltage, wherein the rated voltages of the sub-energy storage devices may be the same. The rated voltage may be 300V or greater, particularly 400V or greater.

[0006] Sub-accumulators can each have multiple individual accumulator cells. Sub-accumulators can, in particular, have series circuits of individual cell modules, wherein each individual cell module can have one or more accumulator cells connected in parallel. An individual cell module can have, for example, M accumulator cells connected in parallel, such as M≥2, M=3, M=4, or M=5. Furthermore, sub-accumulators can each have N individual cell modules connected in series, such as N≥2, N≥10, N≥50, or N≥100.

[0007] Each individual module can have a single-unit rated voltage (e.g., between 2V and 5V), and the rated voltage of the corresponding sub-accumulator can be N multiplied by the single-unit rated voltage.

[0008] The energy storage device may also include a switching unit, wherein the switching unit may include one or more switching elements (semiconductor-based and / or mechanical). The switching unit may be configured to arrange the sub-energy storage devices in different ways, such as in a series circuit, in a parallel circuit, and / or separately from each other. The device may be configured to utilize variations in the arrangement of the sub-energy storage devices to obtain state information about the state of the energy storage device in an efficient and accurate manner.

[0009] During changes in the arrangement of the sub-accumulators, equalization and / or relaxation information (as described below) can be detected to obtain state information based on the equalization and / or relaxation information. The equalization and / or relaxation information can be detected using one or more (internal) measurement units within the accumulator. These measurement units can be configured to detect the current flowing through the respective sub-accumulator and / or through each individual module and / or the voltage on the respective sub-accumulator and / or on each individual module.

[0010] The device is configured to cause: a first sub-accumulator to have a first sub-voltage and a second sub-accumulator to have a second sub-voltage, the first sub-voltage and the second sub-voltage being different from each other. This can cause a relatively small deviation in the sub-voltages (e.g., a deviation of 5% or less, or 2% or less, or 1% or less; and / or 0.1% or more, or 0.5% or more).

[0011] Sub-voltage deviations can be induced efficiently during the operation of the energy storage device (e.g., by placing the sub-energy storage device in a series circuit).

[0012] The device is further configured to, when the first sub-accumulator and the second sub-accumulator are connected together in a parallel circuit, obtain balance information regarding the balancing process (of the sub-voltages) between the first and second sub-accumulators (using one or more measuring units of the accumulators). In particular, balance information regarding the balancing current flowing between the first and second sub-accumulators due to the difference between the first and second sub-voltages can be obtained.

[0013] Equilibrium information may specifically include:

[0014] - Current information regarding the time curve of the balancing current between the first and second sub-accumulators, particularly current information regarding the (time) variation of the balancing current between the first and second sub-accumulators; and / or

[0015] - Voltage information regarding the time curves of the first sub-voltage and / or the second sub-voltage, particularly voltage information regarding the (time) changes of the first sub-voltage and / or the second sub-voltage; and / or

[0016] - Voltage information regarding the time curve of the individual cell voltage on the individual cell module of the first and / or second sub-energy storage unit, and voltage information regarding the (time) change of the individual cell voltage on the individual cell module of the first and / or second sub-energy storage unit.

[0017] The device is further configured to obtain state information regarding the state of the energy storage units (particularly the first sub-energy storage unit, the second sub-energy storage unit, and / or individual modules) based on balancing information. Specifically, state information regarding the state of the first sub-energy storage unit, the second sub-energy storage unit, and / or individual modules can be obtained based on the current information and the voltage information. For example, resistance information regarding the internal resistance of the first sub-energy storage unit and / or the second sub-energy storage unit and / or individual modules can be obtained as state information based on the current information and the voltage information. Here, the time variation of the corresponding voltage can be set to be proportional to the corresponding time variation of the balancing current in order to obtain the resistance information. Based on the resistance information, the performance and / or aging state of the corresponding sub-energy storage unit or the corresponding individual module can be obtained in a precise manner as state information.

[0018] Therefore, an apparatus is described, which is configured to detect, in an energy-efficient manner, balancing information regarding the balancing process among the sub-energy storage units of the energy storage unit during operation of the energy storage unit, so as to accurately determine the state (particularly internal resistance and / or performance and / or storage capacity) of the sub-energy storage units and / or individual modules of the energy storage unit.

[0019] The device can be configured to detect operating conditions during the operation of the energy storage unit, in which the first sub-energy storage unit and the second sub-energy storage unit (e.g., starting from a series circuit) are connected together in a parallel circuit. Then, balance information can be obtained, particularly detected, within the scope of the detected operating conditions in a particularly efficient manner to obtain state information about the energy storage unit's state. This enables particularly efficient determination of the energy storage unit's state.

[0020] The device can be configured to cause, within the scope of a charging process for charging the energy storage unit, a first sub-energy storage unit having a first sub-voltage and a second sub-energy storage unit having a second sub-voltage, the first and second sub-voltages being different from each other. For example, the sub-energy storage units can be arranged in a series circuit for the charging process (which may automatically result in a deviation between the sub-voltages). Alternatively or additionally, selective charging of the first or second sub-energy storage unit can be induced (via a DC-DC voltage converter) to thereby cause a deviation between the sub-voltages. Thus, the preconditions for the equalization process for detecting equalization information can be achieved in a particularly efficient manner.

[0021] The device can be configured to cause, in multiple different states of charge of the energy storage device, respectively: a first sub-energy storage device having a first sub-voltage and a second sub-energy storage device having a second sub-voltage, the first sub-voltage and the second sub-voltage being different from each other; and to obtain, in multiple different states of charge of the energy storage device, equalization information when the first sub-energy storage device and the second sub-energy storage device are connected together in a parallel circuit (e.g., starting from the series circuit of the first sub-energy storage device and the second sub-energy storage device, respectively).

[0022] The plurality of states of charge may have, for example, five or more, or ten or more different states of charge, which are set, for example (if necessary, uniformly distributed) between 5% and 95% or between 0% and 100% of the storage capacity of the energy storage unit. For example, current information and / or voltage information may be detected separately for different states of charge.

[0023] The state information regarding the energy storage device can be obtained with exceptional precision based on the equalization information for the multiple different states of charge of the energy storage device. For example, resistance information regarding the internal resistance of the (sub-energy storage device and / or individual module) can be obtained separately for each different state of charge. This allows for the characterization of the energy storage device's state in a highly accurate manner.

[0024] Another method for obtaining state information about the state of an electric energy storage device is described according to another aspect, wherein the energy storage device includes a first sub-energy storage device and a second sub-energy storage device. The switching unit may be configured to arrange the sub-energy storage devices in parallel circuits or to arrange them separately. The features described herein regarding the energy storage device and / or the method for obtaining state information may also be used individually or in combination in the device.

[0025] The device is configured to cause the first sub-accumulator and the second sub-accumulator to separate from each other from the parallel circuit. This is preferably done during the operation of the accumulator (e.g., when the sub-accumulators transition from the parallel circuit to the series circuit).

[0026] The device is further configured to obtain (in particular detect) relaxation information regarding the relaxation process of the first and / or second sub-accumulators (sub-voltages) caused by the separation of the first and second sub-accumulators. The relaxation information can be detected using one or more (internal) measurement units within the accumulators.

[0027] Relaxation information may include:

[0028] - Voltage information regarding the time curves of the first sub-voltage of the first sub-accumulator and / or the second sub-voltage of the second sub-accumulator; and / or

[0029] - Voltage information regarding the time curve of the individual cell voltage on at least one individual module of the first and / or second sub-accumulator.

[0030] Furthermore, the device is configured to obtain state information about the state of the energy storage device based on relaxation information. This state information can be obtained using pattern recognition algorithms—particularly those based on machine learning.

[0031] The status information may include: information about a reduction in the storage capacity of the accumulator and / or information about deposits on the electrodes of one or more storage cells in the accumulator, particularly information about lithium deposition in the accumulator.

[0032] The device can be configured to perform frequency analysis on equalization and / or relaxation information, particularly current and / or voltage information, to obtain state information about the energy storage device's state. For example, this can induce a transformation from the time domain to the frequency domain (e.g., one or more time curves of current and / or voltage). Resistance information can then be obtained in the frequency domain. For example, resistance information, particularly internal resistance, can be obtained for multiple different frequencies. By applying frequency analysis, the energy storage device's state can be determined in a particularly accurate manner.

[0033] According to another description, an on-board electrical network (for a vehicle) includes at least one device described herein.

[0034] According to another description, a (road) motor vehicle (particularly a car, truck, bus, or motorcycle) includes at least one device described herein and / or an onboard electrical network described herein.

[0035] According to another aspect, a method for obtaining state information about the state of an electric energy storage device is described, wherein the energy storage device includes a first sub-energy storage device and a second sub-energy storage device, the first sub-energy storage device and the second sub-energy storage device being disposed in a parallel circuit by means of a switching unit (e.g., starting from a series circuit) having one or more switching elements.

[0036] The method includes inducing: a first sub-accumulator having a first sub-voltage and a second sub-accumulator having a second sub-voltage, the first sub-voltage and the second sub-voltage being different from each other (e.g., deviating from each other by 0.1% or more, or 0.5% or more, or 1% or more). This can be induced, for example, by arranging the first and second sub-accumulators in a series circuit.

[0037] Furthermore, the method includes: obtaining balance information regarding the balancing process (for balancing the sub-voltages of each sub-energy storage unit) between the first and second sub-energy storage units when the first sub-energy storage unit and the second sub-energy storage unit (if necessary, starting from the series circuit of the sub-energy storage units) are connected together in a parallel circuit. Furthermore, the method also includes: obtaining state information regarding the state of the energy storage units based on the balance information.

[0038] According to another aspect, a method for obtaining state information about the state of an electric energy storage device is described, wherein the energy storage device includes a first sub-energy storage device and a second sub-energy storage device, the first sub-energy storage device and the second sub-energy storage device being arranged in a parallel circuit or being separated from each other by means of a switching unit.

[0039] The method includes causing the first and second sub-accumulators to separate from each other from a parallel circuit (so that no current can flow between and / or from each sub-accumulator). Furthermore, the method includes obtaining relaxation information regarding the relaxation process (of the sub-voltage) of the first and / or second sub-accumulators caused by the separation of the first and second sub-accumulators. The method also includes obtaining state information regarding the state of the accumulators based on the relaxation information.

[0040] According to another aspect, a software (SW) program is described. The software program may be configured to execute on a processor (e.g., on a vehicle control unit) and thereby perform at least one of the methods described herein.

[0041] According to another aspect, a storage medium is described. The storage medium may include a software program configured to execute on a processor, and thereby perform at least one of the methods described herein.

[0042] It should be noted that the methods, apparatuses, and systems described herein can be used not only individually but also in combination with other methods, apparatuses, and systems described herein. Furthermore, each aspect of the methods, apparatuses, and systems described herein can be combined with each other in various ways. In particular, the features of the claims can be combined with each other in various ways. Moreover, features listed in parentheses should be understood as optional features. Attached Figure Description

[0043] The invention is further described with reference to embodiments. In the figures:

[0044] Figure 1a Exemplary components of a vehicle having an electric drive motor are shown;

[0045] Figure 1b An exemplary onboard electrical network for a vehicle is shown;

[0046] Figure 1c An exemplary series circuit of a sub-energy storage unit of an electric energy storage unit is shown;

[0047] Figure 1d An exemplary parallel circuit of the sub-energy storage units of an electric energy storage unit is shown;

[0048] Figures 2a to 2d This illustrates an exemplary sequence of sub-accumulator arrangements in the case of transitioning from a series circuit to a parallel circuit for the sub-accumulators;

[0049] Figure 3a An exemplary time curve for balancing the current is shown when the sub-accumulators are connected in parallel;

[0050] Figure 3b This shows an exemplary time curve of the sub-voltage of one sub-accumulator in the case of sub-accumulator separation; and

[0051] Figure 4a and Figure 4b Flowcharts are shown for exemplary methods for obtaining state information about the state of an electric energy storage device. Detailed Implementation

[0052] As mentioned at the beginning, this paper focuses on determining the state of an electric energy storage device, such as part of a vehicle's onboard electrical network. In this regard, Figure 1a An exemplary vehicle 100 is shown, which includes at least one electric energy storage unit 105 for storing electrical energy for the operation of an electric drive motor 103 of the vehicle 100. The energy storage unit 105 may have a rated voltage of 300V or greater, particularly 800V or greater. The (control) device 101 of the vehicle 100 may be configured to control the operation of the electric drive motor 103 based on the electrical energy from the energy storage unit 105.

[0053] Figure 1b An exemplary on-board electrical network 110 for vehicle 100 is shown. On-board electrical network 110 may include an inverter 113 configured to generate an AC voltage for one or more phases of electric drive motor 103 based on a DC voltage provided by energy storage 105.

[0054] The energy storage 105 of vehicle 100 may have multiple sub-energy storage units 111, 112, which can be connected in series if needed to increase the effective rated voltage of energy storage 105 (and thus increase the electrical power available to drive motor 103). Figure 1b The vehicle-mounted electrical network 110 shown includes a first (sub) energy storage unit 111 and a second (sub) energy storage unit 112, which may each have a sub-rated voltage, thereby generating an effective rated voltage through the series circuit of the two energy storage units 111, 112, which is twice the sub-rated voltage of each sub-energy storage unit 111, 112.

[0055] The series circuit of the two sub-accumulators 111 and 112 can be activated or deactivated by a series switching element 116 (e.g., a semiconductor-based switching element or a (mechanical) relay). By closing the series switching element 116, the effective rated voltage generated by the series circuit of the sub-accumulators 111 and 112 can be applied to the inverter 113 and ready for operation of the drive unit 103.

[0056] exist Figure 1b The vehicle-mounted electrical network 110 shown also includes a first DC-DC converter 114, which may be coupled to or has been coupled to a first sub-energy storage unit 111, and is configured to extract electrical energy from or (for charging) the first sub-energy storage unit 111. Furthermore, the vehicle-mounted electrical network 110 may have a corresponding second DC-DC converter 115, which may be coupled to or has been coupled to a second sub-energy storage unit 112, and is configured to extract electrical energy from or (for charging) the second sub-energy storage unit 112.

[0057] The vehicle-mounted electrical grid 110 can, as exemplarily, in Figure 1c and Figure 1d As shown, it includes a switching unit 120, which enables the sub-accumulators 111 and 112 to be connected in series (as shown in...). Figure 1c (as shown in) or connected in parallel (such as in) Figure 1d (as shown in) or separated from each other (as shown in) Figure 1b(As shown in the diagram). Switching unit 120 may include a first switching element S1 configured to couple or decouple the second terminal of the first sub-energy storage 111 to the second terminal of the second sub-energy storage 112 and / or to a reference point (e.g., ground and / or the negative terminal of the inverter 113). Switching unit 120 may include a second switching element S2 configured to connect or decouple the second terminal of the first sub-energy storage 111 to the first terminal of the second sub-energy storage 112. Switching unit 120 may include a third switching element S3 configured to connect or decouple the first terminal of the second sub-energy storage 112 to the first terminal of the first sub-energy storage 111 and / or to an operating point (e.g., the positive terminal of the inverter 113).

[0058] The first sub-accumulator 111 can have a first sub-voltage U1 and the second sub-accumulator 112 can have a second sub-voltage U2. If the two sub-accumulators 111 and 112 are connected in series (see...), Figure 1c Then the total voltage between the operating point and the reference point (i.e., the on-board grid voltage) is the sum of these two sub-voltages, U1 + U2. If the two sub-accumulators 111 and 112 are connected in parallel (see... Figure 1d Then, the total voltage between the operating point and the reference point corresponds to the sub-voltage U1=U2.

[0059] During the lifespan of the energy storage 105, it may be necessary and / or advantageous to determine the state of the energy storage 105, particularly regarding its available storage capacity. For this purpose, external measuring devices can be applied, configured to detect measurements related to the energy storage 105 and, based on these, determine state information regarding the energy storage 105's condition. The application of external measuring devices is associated with additional costs and is generally feasible only within the scope of vehicle 100 maintenance. Furthermore, the detection of measurements may require the extraction of charge from the energy storage 105, which is associated with energy loss.

[0060] The following measures are described herein, which enable the determination of state information about the state of the energy storage device 105 during operation of the on-board power grid 110 and / or in the absence of energy loss and / or without the application of external measuring equipment.

[0061] During the operation of the energy storage 105, it may be necessary to connect the sub-energy storage units 111 and 112 (e.g., starting from a series circuit) in parallel, for example, to enable a charging process with a reduced charging voltage. In another example, it may be necessary to separate the two sub-energy storage units 111 and 112 (e.g., starting from a parallel circuit) (e.g., so that the sub-energy storage units 111 and 112 can then be connected in series). The switching process to the parallel circuit and / or the switching process to separate the sub-energy storage units 111 and 112 can be used to obtain state information about the state of the energy storage 105.

[0062] exist Figures 2a to 2d The series circuit of slave energy storage devices 111 and 112 is illustrated in the figure. Figure 2a The parallel circuit from the sub-accumulators 111 and 112 ( Figure 2c and Figure 2d The transition can begin by separating sub-accumulators 111 and 112 from each other. Figure 2b This can be caused, for example, by disconnecting switching elements S1, S2, and S3. Sub-accumulators 111 and 112 can then be connected in parallel with each other. Figure 2c This can be caused, for example, by closing switching elements S1 and S2.

[0063] Since the first sub-voltage U1 and the second sub-voltage U2 are generally different in the series circuit of sub-energy storage devices 111 and 112, and therefore the first and second sub-voltages have Delta Δ = U1 - U2, a balancing current 201 flows from the moment the sub-energy storage devices 111 and 112 are connected in parallel (e.g., if Delta Δ > 0, then it flows from the first sub-energy storage device 111 to the second sub-energy storage device 112; or if Delta Δ < 0, then it flows from the second sub-energy storage device 112 to the first sub-energy storage device 111). The balancing current 201 flows until the two sub-voltages of the two sub-energy storage devices 111 and 112 are balanced (and therefore Delta Δ = 0).

[0064] The balancing current 201 can be detected by a measuring unit inside the energy storage 105. Additionally, the first sub-voltage and the second sub-voltage and / or voltage Delta can be detected by one or more measuring units inside the energy storage 105. If necessary, the individual voltage of each module of the sub-energy storage 111, 112 can be detected by one or more measuring units inside the energy storage 105.

[0065] Figure 3aAn exemplary time curve 312 of the equalization current 201 is shown, that is, the current intensity 310 of the equalization current 201 as a function of time 300. The equalization current 201 flows from the switching moment 301, at which time the sub-accumulators 111, 112 are connected in parallel. The time curve 312 of the equalization current 201 can be analyzed to obtain state information about the state of the accumulator 105. In particular, the state information can be obtained based on one or more characteristics of the time curve 312 of the equalization current 201. Exemplary characteristics are: the maximum current intensity 311, the time gradient of the curve 312 of the equalization current 201, and / or the duration 302 of the equalization current pulse.

[0066] For example, the change in current intensity 310 of the equalization current 201 (i.e., ΔI) and the change in the first or second sub-voltages U1 and U2 (i.e., ΔU with respect to U1 or U2) can be determined at a specific time during the equalization current pulse. The internal resistance R of the first or second sub-accumulators 111 and 112 can then be obtained by the ratio R = ΔU / ΔI. The storage capacity of the first or second sub-accumulators 111 and 112 can be deduced from the internal resistance R.

[0067] State information regarding the state of each individual module of the first and / or second sub-accumulators 111, 112 can be obtained in a corresponding manner. For this purpose, the change in individual module voltage (i.e., ΔU) caused by the change in current intensity 310 of the equalization current 201 (i.e., ΔI) can be detected in the individual module to determine the internal resistance of that individual module.

[0068] As previously described, the energy storage unit 105 may have a switching matrix configuration or a switchable center tap. During a charging process on a 400V infrastructure, the energy storage unit 105 can be switched from an 800V configuration to a 400V configuration via a parallel circuit of the two energy storage units 111 and 112. Due to the inherent parameter fluctuations of the two energy storage units 111 and 112, an asymmetry typically exists in the voltages of the two energy storage units 111 and 112. By connecting the two energy storage units 111 and 112 together, an equalizing current pulse is generated, which can be used to characterize the characteristics of the logic units (i.e., parallel combinations or individual unit modules) of the two energy storage units 111 and 112. Alternatively or supplementing the inherent asymmetry, the asymmetry of the sub-voltages of each energy storage unit 111 and 112 can be intentionally modulated by DC / DC converters 114 and 115. Here, only one accumulator half 111, 112 can be charged for a relatively short period of time (e.g., a few seconds and / or minutes), and the equalization process can then be used to characterize the features of accumulator 105.

[0069] For example, only 11kW of charging power may be available in the wallbox, and the energy storage 105 can be charged, for example, via AC charging in diagnostic mode. This can serve as a trigger for using balancing current pulses to characterize the energy storage 105. During the preparation for the charging process, the energy storage 105 transitions its architecture from 800V to 400V. Due to the asymmetrical charging of the two energy storage halves 111, 112, a balancing current pulse (typically with relatively small power) is generated. The balancing process enables the characterization of the energy storage 105's characteristics. During the charging process, the internal resistance (e.g., for different states of charge of the energy storage 105) can be determined through targeted asymmetrical charging and subsequent balancing current pulses.

[0070] The internal resistance of the energy storage 105 and / or its various parallel combinations or individual modules can be determined using the measures described herein. The duration 302 of the equalization current pulse can be precisely controlled by power electronics. Asymmetric charging of the energy storage 105 allows for the characterization of its SOC-related properties during (AC) charging across the entire SOC range without loss of charge (i.e., no energy loss). External measuring equipment is not required, as the energy storage 105 generally provides the necessary measurement techniques and power. Characterization of the energy storage 105 can be performed directly in the vehicle 100 without factory visits, thereby saving time and cost. Furthermore, the frequency (ratio) of the charging and / or equalization process can be used as an excitation and / or as additional information for determining the state of the energy storage 105.

[0071] Figure 4a A flowchart illustrates an exemplary (computer-implemented) method 400 for obtaining state information regarding the state of an electric energy storage device 105, particularly an electrochemical energy storage device, such as a lithium-ion-based energy storage device. The energy storage device 105 includes a first sub-energy storage device 111 and a second sub-energy storage device 112, which can be arranged in a series or parallel circuit via a switching unit 120 (including one or more switching elements S1, S2, S3). Sub-energy storage devices 111 and 112 may each have multiple individual energy storage units, wherein the individual energy storage units can be grouped into unit modules, each unit module comprising one or more corresponding energy storage units arranged in parallel. Sub-energy storage devices 111 and 112 may each have a series circuit of unit modules. Sub-energy storage devices 111 and 112 may have the same rated voltage (e.g., 300V or greater, particularly 400V).

[0072] Method 400 includes causing 401: a first sub-accumulator 111 has a first sub-voltage and a second sub-accumulator 112 has a second sub-voltage, the first and second sub-voltages being different from each other. This can be achieved, for example, by arranging the sub-accumulators 111 and 112 in a series circuit (e.g., during the charging process of the accumulator 105). Due to inherent fluctuations, different sub-voltages can be generated (even with the same rated voltage for the sub-accumulators 111 and 112). The sub-voltages can, for example, deviate from each other by 0.1% to 2%.

[0073] Method 400 further includes: determining 402 balancing information regarding the balancing process between the first sub-energy storage unit 111 and the second sub-energy storage unit 112 when the first sub-energy storage unit 111 and the second sub-energy storage unit 112 are connected together in a parallel circuit. The parallel circuit of the sub-energy storage units 111 and 112 causes a balancing current 201 between the sub-energy storage units 111 and 112 due to a (relatively small) voltage difference. The balancing information may include information about the balancing current 201 and / or about the balancing process of the sub-voltages of the sub-energy storage units 111 and 112.

[0074] The sub-accumulators 111 and 112 can preferably be connected together in a parallel circuit during the operation of the accumulator 105, for example, in preparation for the charging process at a relatively low charging voltage (which corresponds to the rated voltage of the sub-accumulators 111 and 112). Therefore, equalization information can be obtained efficiently (especially without causing energy loss).

[0075] Furthermore, the method 400 includes: obtaining 403 state information regarding the state of the energy storage unit 105 based on the equalization information. Based on the equalization information, the internal resistance of one or more individual modules of the first sub-energy storage unit 111, the second sub-energy storage unit 112, and / or the energy storage unit 105 can be obtained. Based on the internal resistance, the state of health (SOH), particularly the state-of-health resistance (SOHr), and / or the performance of the corresponding energy storage unit (sub-energy storage unit 111, 112, or individual module) can be inferred as additional information. Furthermore, based on the internal resistance, the storage capacity (particularly the capacity (SOHc) of the corresponding energy storage unit (sub-energy storage unit 111, 112, or individual module) can be inferred as additional information.

[0076] The equalization process, which is an alternative or supplement to the equalization process when sub-accumulators 111 and 112 are connected in parallel, and the relaxation process when sub-accumulators 111 and 112 are disconnected, can be used to obtain state information about the state of accumulator 105. Sub-accumulators 111 and 112 generally have the same sub-voltage U1 = U2 in a parallel circuit. If these two sub-accumulators 111 and 112 are decoupled from each other (e.g., by disconnecting switching elements S1, S2, and S3), changes in the individual sub-voltages of sub-accumulators 111 and 112 can occur due to the relaxation process (without current flowing through them).

[0077] For example, a relaxation process occurs in the energy storage unit (e.g., sub-energy storage units 111, 112, or individual modules) after conditions such as charging or grid connection where the energy storage unit's voltage is maintained at a defined voltage level. A relaxation process can occur after separation from the corresponding voltage, during which the energy storage unit's voltage approaches the energy storage resting voltage, i.e., the overvoltage gradually disappears. In the case of a purely parallel circuit with no current flowing through sub-energy storage units 111, 112, the two resting voltages of the energy storage units will be adjusted to the same value after a sufficient period of time (even if different states of charge of sub-energy storage units 111, 112 are involved). After separation from the parallel circuit, a relaxation process can occur (in the two sub-energy storage units 111, 112) (during which each sub-voltage approaches the corresponding resting voltage of the two sub-energy storage units 111, 112).

[0078] Figure 3b An exemplary time curve 322 (i.e., voltage value 320 as a function of time 300) shows the sub-voltage of one sub-accumulator 111, 112 starting from time 303, at which time the two sub-accumulators 111, 112 are decoupled. The sub-voltage can, for example, change from an initial value 321 to a final value 322. The time curve 322 of the sub-voltage, and in particular one or more characteristics of the time curve 322 (e.g., Delta between the final value 322 and the initial value 321, the duration 304 of the sub-voltage change, etc.), can be used to obtain state information about the state of the accumulator 105.

[0079] Self-diagnostic testing of the energy neutrality of the two energy storage halves 111 and 112 can be performed after an 800V charging process. In a fully charged state, energy storage 105 can be switched to 2×400V (i.e., switched to parallel connection) for self-excitation. Subsequently, the one or more switching elements S1, S2, and S3 can be disconnected again to detect the relaxation characteristics of energy storage halves 111 and 112. These characteristics of the respective energy storage halves 111 and 112 can be used to determine the energy storage asymmetry and / or resistance of each energy storage half 111 and 112 and / or to detect possible lithium deposition within the respective energy storage halves 111 and 112. Furthermore, this provides information about possible non-uniformities in the wiring of the individual modules of the respective energy storage halves 111 and 112. The method for identifying lithium deposition is described in S. Schindler et al., “Voltage relaxation and impedance spectrocopy as in-operando methods for the detection of lithium plating ongraphitic anodes in commercial lithium-ion cells, Journal of Power Sources 304 (February 2016) 170-180”. The contents of that paper are incorporated herein by reference in their entirety.

[0080] Figure 4b A flowchart is shown of an exemplary (computer-implemented if necessary) method 410 for obtaining state information about the state of the electric energy storage device 105. It should be noted that the features of the two methods 400, 410 can be combined with each other in any way.

[0081] As already described, the energy storage device 105 includes a first sub-energy storage device 111 and a second sub-energy storage device 112. The first and second sub-energy storage devices can be arranged in parallel circuits or separated from each other by means of a switching unit 120 (the switching unit has one or more switching elements S1, S2, S3) (so that no current can flow between the two sub-energy storage devices 111, 112). Method 410 can be performed during the operation of the energy storage device 105.

[0082] Method 410 includes causing 411 the first sub-accumulator 111 and the second sub-accumulator 112 to separate from each other from a parallel connection. This can be done, for example, due to the charging process of the sub-accumulators 111, 112, wherein the charging process is carried out at a relatively low charging voltage (within the range of the rated voltage of the sub-accumulators 111, 112). The separation can be caused, for example, as an intermediate step, so that the sub-accumulators 111, 112 are switched from a parallel circuit to a series circuit.

[0083] Method 410 further includes obtaining 412 relaxation information regarding the (voltage) relaxation process of the first sub-energy storage unit 111 and / or the second sub-energy storage unit 112 caused by the separation of the first sub-energy storage unit 111 and the second sub-energy storage unit 112. If the sub-energy storage units 111 and 112 are arranged in a parallel circuit, the sub-energy storage units 111 and 112 generally have the same sub-voltage. After the separation of the sub-energy storage units 111 and 112, changes in the sub-voltages of the first and / or second sub-energy storage units 111 and 112 may occur due to the relaxation process (without current flowing through them). The relaxation information may show the time curves of the sub-voltages of the first and / or second sub-energy storage units 111 and 112 and / or the time curves of the individual module voltages.

[0084] Method 410 further includes obtaining 413 state information regarding the state of the energy storage device 105 based on relaxation information. For this purpose, a pattern recognition algorithm can be used, which is constructed to identify patterns for specific states (e.g., for specific degradation states, such as lithium deposition) of the respective sub-energy storage devices 111, 112 and / or the respective individual modules based on relaxation information (particularly based on the time curves of the sub-voltages of the sub-energy storage devices 111, 112 and / or the individual voltages of the individual modules).

[0085] The measures described herein allow for the efficient and accurate determination of the SOHr, performance, and / or SOHc of the sub-accumulators 111, 112, and / or individual modules of the energy storage 105. Where necessary, a reduction in the storage capacity of the sub-accumulators 111, 112, and / or individual modules can be inferred from the identified increase in the internal resistance of the sub-accumulators 111, 112, and / or individual modules.

[0086] This invention is not limited to the embodiments shown. In particular, it should be noted that the specification and drawings are intended to illustrate the principles of the proposed methods, apparatus, and systems only by way of example.

Claims

1. A device (101) for obtaining state information about the state of an electric energy storage device (105); wherein, The energy storage device (105) includes a first sub-energy storage device (111) and a second sub-energy storage device (112), the first sub-energy storage device and the second sub-energy storage device being configured in a parallel circuit by means of a switching unit (120); the device (101) is configured to, -Cause: The first sub-accumulator (111) has a first sub-voltage and the second sub-accumulator (112) has a second sub-voltage, the first sub-voltage and the second sub-voltage are different from each other; - Obtain balance information about the balancing process between the first sub-energy storage unit (111) and the second sub-energy storage unit (112) when the first sub-energy storage unit (111) and the second sub-energy storage unit (112) are connected together in a parallel circuit; as well as - Based on the equilibrium information, obtain the state information about the state of the energy storage device (105).

2. The apparatus (101) according to claim 1, wherein, The device (101) is configured to obtain balance information about a balance current (201) that flows between a first sub-energy storage unit (111) and a second sub-energy storage unit (112) due to the difference between the first sub-voltage and the second sub-voltage.

3. The apparatus (101) according to any one of the preceding claims, wherein, The balance information includes: - Current information regarding the time curve (321) of the balancing current (201) between the first sub-accumulator (111) and the second sub-accumulator (112), particularly current information regarding the change in the balancing current between the first sub-accumulator and the second sub-accumulator; and / or - Voltage information regarding the time curves of the first sub-voltage and / or the second sub-voltage, particularly voltage information regarding the changes in the first sub-voltage and / or the second sub-voltage.

4. The apparatus (101) according to claim 3, wherein, The device (101) is configured to obtain resistance information about the internal resistance of the first sub-energy storage unit (111) and / or the second sub-energy storage unit (112) as state information based on the current information and the voltage information.

5. The apparatus (101) according to any one of the preceding claims, wherein, - The first sub-energy storage unit (111) and / or the second sub-energy storage unit (112) each comprise a series circuit of individual modules, each individual module having one or more energy storage units; and -The device (101) is configured to, -- Obtain current information from the time curve (321) of the equalization current (201) between the first sub-accumulator (111) and the second sub-accumulator (112), especially current information about the change of the equalization current between the first sub-accumulator and the second sub-accumulator, as part of the equalization information; -- Obtain voltage information from the time curves of the individual cell voltages on the individual modules of the first and / or second sub-accumulators (111, 112), especially voltage information regarding the changes in the individual cell voltages on the individual modules of the first and / or second sub-accumulators, as equalization information; and --Based on the current information and the voltage information, obtain state information about the state of the individual module.

6. The apparatus (101) according to any one of the preceding claims, wherein, The device (101) is configured to, - During the operation of the energy storage unit (105), the following operating condition is detected, in which the first sub-energy storage unit (111) and the second sub-energy storage unit (112) are connected together in a parallel circuit; and - Obtain the equilibrium information within the scope of the detected operating conditions to obtain the state information.

7. The apparatus (101) according to any one of the preceding claims, wherein, The device (101) is configured to cause, within the scope of a charging process for charging the energy storage device (105), the first sub-energy storage device (111) having a first sub-voltage and the second sub-energy storage device (112) having a second sub-voltage, wherein the first sub-voltage and the second sub-voltage are different from each other.

8. The apparatus (101) according to any one of the preceding claims, wherein, The device (101) is configured to, -In multiple different states of charge of the energy storage device (105), the first sub-energy storage device (111) has a first sub-voltage and the second sub-energy storage device (112) has a second sub-voltage, the first sub-voltage and the second sub-voltage being different from each other; and -Equalization information is obtained for the first sub-energy storage unit (111) and the second sub-energy storage unit (112) connected together in parallel circuits under multiple different charging states of the energy storage unit (105); and - The state information is obtained based on the equalization information of the multiple different states of charge for the energy storage device (105).

9. The apparatus (101) according to any one of the preceding claims, wherein, The device (101) is configured to cause the first sub-energy storage unit (111) and the second sub-energy storage unit (112) to switch from a series circuit to a parallel circuit, so as to cause the first sub-energy storage unit (111) to have a first sub-voltage and the second sub-energy storage unit (112) to have a second sub-voltage, wherein the first sub-voltage and the second sub-voltage are different from each other when the first sub-energy storage unit (111) and the second sub-energy storage unit (112) are connected together in a parallel circuit.

10. A device (101) for obtaining state information about the state of an electric energy storage device (105); wherein, The energy storage device (105) includes a first sub-energy storage device (111) and a second sub-energy storage device (112), the first sub-energy storage device and the second sub-energy storage device can be arranged in parallel circuit or can be separated from each other by means of a switching unit (120); the device (101) is configured to, -Cause: The first sub-accumulator (111) and the second sub-accumulator (112) are separated from each other from the parallel circuit; - Obtain relaxation information regarding the relaxation process of the first sub-accumulator (111) and / or the second sub-accumulator (112) caused by the separation of the first sub-accumulator (111) and the second sub-accumulator (112); and - Based on the relaxation information, obtain the state information about the state of the energy storage device (105).

11. The apparatus (101) according to claim 10, wherein, The relaxation information includes: - Voltage information regarding the time curve (322) of the first sub-voltage of the first sub-accumulator (111) and / or the second sub-voltage of the second sub-accumulator (112); and / or - Voltage information regarding the time curve of the individual cell voltage on at least one individual module of the first and / or second sub-accumulators (111, 112).

12. The apparatus (101) according to any one of claims 10 to 11, wherein, The status information includes: information about a reduction in the storage capacity of the accumulator (105) and / or information about deposits on the electrodes of one or more storage cells in the accumulator (105), particularly information about lithium deposition in the accumulator (105).

13. The apparatus (101) according to any one of claims 10 to 12, wherein, The device (101) is configured to obtain state information based on the relaxation information when using a pattern recognition algorithm—particularly based on machine learning.

14. A method (400) for obtaining state information about the state of an electric energy storage device (105); wherein, The energy storage device (105) includes a first sub-energy storage device (111) and a second sub-energy storage device (112), the first sub-energy storage device and the second sub-energy storage device being disposed in a parallel circuit by means of a switching unit (120); the method (400) includes: - Cause (401): The first sub-accumulator (111) has a first sub-voltage and the second sub-accumulator (112) has a second sub-voltage, the first sub-voltage and the second sub-voltage are different from each other; - Calculate (402) the balance information regarding the balance process between the first sub-energy storage unit (111) and the second sub-energy storage unit (112) in the case where the first sub-energy storage unit (111) and the second sub-energy storage unit (112) are connected together in a parallel circuit; and - Based on the equilibrium information, obtain (403) the state information of the energy storage device (105) regarding its state.

15. A method (410) for obtaining state information about the state of an electric energy storage device (105), wherein, The energy storage device (105) includes a first sub-energy storage device (111) and a second sub-energy storage device (112), which can be arranged in a parallel circuit or separated from each other by means of a switching unit (120); the method (410) includes: - Caused (411): The first sub-accumulator (111) and the second sub-accumulator (112) are separated from each other from the parallel circuit; - Obtain (412) relaxation information regarding the relaxation process of the first sub-accumulator (111) and / or the second sub-accumulator (112) caused by the separation of the first sub-accumulator (111) and the second sub-accumulator (112); and - Based on the relaxation information, obtain (413) the state information of the energy storage device (105) regarding its state.

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