Method for charging a battery, evaluation unit of a power grid and automobile

Abstract

Method for charging a battery (4) comprising the steps: - Determining (100) a constant target charging power based on a predefined reference (3a-3c) and depending on a current charging parameter of the battery (4); - Communicating (200) a request including the determined constant target charging power to an evaluation unit (11) of a power grid (6) connected to the battery (4); - Determining (400) a constant charging power to be provided by the power grid (6) as a function of the target charging power based on a predefined criterion by the evaluation unit (11) of the power grid (6), as a result of which - Receiving (500) a feedback from the power grid (6) representing the constant charging power to be provided to a battery management system (2) of the battery (4); and - Starting (600) a charging process of the battery (4) by the battery management system (2) with the constant charging power to be provided, characterized in that the predefined reference (3a-3c) includes a predefined stage profile with respect to the constant charging power for charging the battery (4).

Description

[0001] The invention relates to a method for charging a battery, an evaluation unit of a power grid and an automobile.

[0002] Vehicles with an electric drivetrain typically have an electrical energy storage system. In various vehicles used today, the electrical energy storage system is based on lithium-ion cells, for example. The electrical energy storage system (also referred to here as a battery) comprises, for example, several individual lithium-ion cells connected in series.

[0003] Charging the electrical energy storage system is achieved either via an energy converter integrated into the vehicle (e.g., an internal combustion engine or a fuel cell) or via a charging interface. If charging occurs via a charging interface, several options exist, such as wired single-phase AC charging, wired DC charging (e.g., using a three-phase grid connection), or wireless charging. All these options place different loads on the electrical power grid, ranging from less than 1 kW to several hundred kW. Depending on the charging power and the number of vehicles connected to the power grid via charging interfaces, the grid operator needs to implement load control to balance energy generation and consumption. Various concepts exist for this purpose in the current state of the art, such as "V2G" (vehicle-to-grid).Feeding energy from the vehicle into the grid is another possibility. However, this does not allow for selective charge management of the vehicles connected to the grid.

[0004] In the aforementioned systems, battery charging is carried out via a regulated charging process. The charging of the battery, or rather the adjustment of current and voltage, takes place either in the vehicle or at the charging station. The specified current and voltage setpoints are generally regulated by the battery's battery management system. Currently, charging often follows various methods, such as the CCCV charging method (CC = constant current; CV = constant voltage). Consumer demand shows a trend towards faster charging; that is, towards shorter charging times (i.e., higher charging power). A significant disadvantage of this type of charging, especially fast charging, is the accelerated aging of the battery or the reduction of its lifespan due to excessively high charging power. Another disadvantage is the irregular load on the power grid caused by the non-linear charging process.Nonlinear network loads represent a disturbance variable that is very difficult and costly to control in network management.

[0005] German patent DE 10 2012 012 765 A1 describes a current control system with superimposed voltage control for charging a battery system composed of many individual cells connected in series. Furthermore, German patent DE 10 2016 007 479 A1 discloses a method for considering the anode potential to prevent aging effects. These proposals each address, at best, one problem from the two primary problem areas identified: "battery aging" and "load on the power grid."

[0006] Furthermore, DE 10 2012 212 755 A1 proposes constant-power charging of a battery, whereby a user can, for example, vary their current draw from the grid depending on the time of day in order to reduce their electricity bill. However, this does not take into account the complex issue of battery aging.

[0007] DE 10 2015 219 202 A1 discloses a constant-power charging method for a battery, wherein different constant charging powers are determined and made available for charging within different time segments based on a predefined cost criterion, in particular based on current energy costs. However, the aging of the battery or its lifespan is not taken into account.

[0008] German patent DE 10 2009 016 624 A1 discloses a sealing film consisting of a stretched carrier film that contracts under the influence of heat, thus optimally adapting to differently shaped containers. The carrier film has a multi-layered coating with a colored layer that adheres to the container via an adhesive layer. In certain areas, an adhesive-setting layer in the form of graphic elements borders the colored layer, giving these areas varying degrees of adhesion to the carrier film. When the film is removed, these defined areas detach from the colored layer and remain either on the container or on the film. This creates a reliable tamper-evident seal, making any unauthorized opening visible.

[0009] German patent DE 10 2011 109 422 A1 relates to a method for charging the battery of a vehicle, in particular an electric vehicle. A time-segmented base load profile is calculated from the selected charging mode and the maximum charging power of the charging station. The system then determines an optimized charging profile that takes into account both vehicle-specific conditions and available charging power. The aim is to control the charging process, use the available energy efficiently, and charge the battery gently.

[0010] German patent application DE 10 2008 050 021 A1 discloses a method and system for load management and control of the charging process of an energy storage system in a plug-in vehicle (e.g., a plug-in hybrid). The vehicle sends a charging request to a remote control center, such as a telematics service. This center then transmits a charging command, which either enables or disables charging. The vehicle subsequently regulates the charging process according to this command. This allows for flexible, external, and situationally adaptable control of the charging process.

[0011] Based on the aforementioned prior art, it is therefore an object of the present invention to provide a method for charging a battery which alleviates the above-mentioned disadvantages and in particular enables optimal integration of batteries into the grid management as well as an ideal reduction of the charging time, i.e. with the least possible impact on the battery's service life. Disclosure of the invention

[0012] The aforementioned problem is solved according to the invention by the subject matter of claim 1. According to a first aspect, the present invention relates to a method for charging a battery. A battery within the scope of the present invention can, in particular, comprise batteries with lithium cell chemistry, such as nickel-manganese-cobalt (NMC) and / or nickel-cobalt-aluminum (NCA) and / or lithium iron phosphate (LFP) and / or lithium titanium dioxide (LTO). For example, a battery is understood to be a plurality of electrical cells connected in series. In particular, such a battery comprises 10 to 300 cells connected in series, preferably 48 to 120 cells connected in series and / or 140 to 230 cells connected in series.

[0013] In a first step of the method according to the invention, a constant target charging power is determined based on a predefined reference and as a function of a current battery charging parameter. This determination can be carried out via an evaluation unit of a battery management system. For example, a CPU and / or a microcontroller are suitable as the evaluation unit within the scope of the present invention.

[0014] Determining the constant target charging power can be divided into several steps. The first step involves determining a static charging power, i.e., a power based on static charging parameters (i.e., parameters that are essentially assumed to be constant when determining the constant target charging power). These parameters can be used as the battery's current charging parameters. Static charging parameters can include, for example, the battery temperature, the battery's open-circuit voltage, the charging time to a predefined state of charge, and / or the battery's nominal capacity. For this purpose, the battery management system determines battery measurements such as current (e.g., the total battery current), voltages (e.g., the total voltage or voltages of specific cells), and / or temperatures.This example illustrates how to determine the constant target charging power using the current or static charging parameter of temperature. Specifically, temperature sensors can be arranged to measure the temperature of each battery cell. Alternatively, one temperature sensor can be used per module of grouped cells. The temperature readings can then be processed by deriving a temperature model to determine which of the measured values ​​should be used for further calculations. This could be, for example, the coldest temperature for limiting the charging power, the average temperature for calculating the open-circuit voltage, or the warmest temperature for determining the need for cooling. The crucial criterion here is to ensure that the battery's lifespan is preserved during charging.

[0015] The constant target charging power is also determined using a predefined reference. This predefined reference can, for example, include empirically determined characteristic curves for constant charging power. The empirical determination of these characteristic curves can be carried out, for example, through laboratory characterization. Such laboratory characterizations result, for example, in optimized characteristic curves for life-saving constant charging, depending on the cell chemistry. These characteristic curves can, for example, contain life-saving-optimized step profiles (i.e., step diagrams) for constant charging power, with the charging power as the ordinate of, for example, a two-dimensional coordinate system. The abscissa of the characteristic curve can, for example, include the state of charge (SOC), the charging time, or the open-circuit voltage. From this, step profiles of constant charging power for life-saving charging can be derived.Based on the abscissa correlated with the measured value (e.g., voltage) or the derived value (e.g., state of charge) of the battery, the lifetime-optimized constant charging power can be determined as the ordinate (or stage of the diagram) from the characteristic curves. The lifetime-optimized constant charging power determined from the characteristic curves can be correlated with the aforementioned temperature to further reduce battery aging. Furthermore, a specific time can be defined during which the constant charging power determined from the characteristic curves should be used for charging (e.g., the width of a stage of the aforementioned stage profile). A temperature correction factor associated with the corresponding temperature for the constant charging power determined from the characteristic curves can be taken from the data stored in the battery management system. For example, a corresponding temperature correction factor may be stored for certain temperatures.This temperature correction factor can also be determined empirically and is preferably multiplied by the constant charging power derived from the characteristic curves. The temperature correction factor is typically less than one. The resulting static charging power can then be used directly as the target charging power.

[0016] Optionally, a dynamic charging parameter can be incorporated into the determination of the target charging power, either additionally or alternatively as a current charging parameter. Dynamic charging parameters are defined as variable parameters such as current gradients in the battery, voltage gradients in the battery, temperature gradients in the battery, changes in cell internal pressure, and / or changes in anode potential. These dynamic charging parameters can be determined using conventional sensors of the battery management system. The inclusion of dynamic charging parameters serves to further reduce the aging effects of the battery.

[0017] If both static and dynamic charging parameters are used to determine the target state of charge, a weighting function can be employed to prioritize either the static or the dynamic charging parameters. For example, as the battery's lifespan increases (i.e., with increasing ampere-hour throughput), the static charging parameters are weighted less and the dynamic charging parameters more. This allows for efficient determination of the constant target charging power for battery-friendly charging. By considering the aforementioned influencing factors, an ideal charging speed can be achieved that minimizes battery damage. While rapid charging is possible without considering these factors, as is the case in the prior art, it reduces battery lifespan.Furthermore, the network load is then extremely high and therefore difficult to control.

[0018] Furthermore, a user can specify a constant charging power, which is included as a predefined reference in the determination of the constant target charging power, whereby this specified power must not exceed the charging power stored in the characteristic maps and thus preferably the lowest constant target charging power can be selected from the constant target charging power determined, for example, by the battery management system and the user's specification.

[0019] In summary, determining the constant target charging power allows for a charging process that extends the battery's lifespan. In other words, in a first step of the inventive method, an optimal and life-saving constant target charging power is determined by weighing a multitude of influencing factors.

[0020] In the next step, a comprehensive request is sent to an evaluation unit of a power grid connected to the battery, specifying the determined constant target charging power. This step preferably occurs in response to the previous step. Such a request might essentially say: "May the battery be charged with the determined constant target charging power?" Furthermore, the request can include a suggestion for how long the battery should be charged with the determined constant target charging power. Communication with the power grid can take place via the battery management system and / or the charger. Examples of such communication methods include Powerline Communication (PLC), WLAN, GSM, CAN, and / or Ethernet.

[0021] A further step of the method according to the invention comprises determining a constant charging power to be provided by the power grid, depending on the target charging power, based on a predefined criterion by the evaluation unit of the power grid. Here, the "constant charging power to be provided" is the power that is ultimately available for charging the battery. The aforementioned "predefined criterion" should not be confused with the predefined reference explained above. The predefined criterion can include consumption data from the power grid (e.g., in gigawatts for a specific period) and / or generation data from the power grid (e.g., in gigawatts for a specific period) and / or forecast data from the power grid (e.g., in gigawatts for a specific period) and / or an identification code of the battery. This means that the predefined criterion is preferably stored in a database of the power grid.The battery's unique identification code can be assigned to a tariff group of the grid operator or energy supplier, for example, as part of this determination process. If the identification code is assigned to a high-priced tariff with corresponding prioritization, then the constant charging power to be provided is equal to the determined constant target charging power. In other words, this example means that the user has opted for a premium tariff. This fact can be linked to their battery's identification code, and thus the user receives the desired target charging power. If this is not the case, the desired target charging power will always be lower.It should be noted that the life-saving charging method is always available, as the constant charging power to be provided can be at most equal to the determined constant target charging power. Furthermore, defined energy packages can be requested from or released from the power grid based on this determination, which makes grid discharge controllable and thus simplifies it. For example, in addition to the constant charging power to be provided, a time period can also be determined during which the constant charging power is made available or guaranteed.

[0022] A further step involves receiving feedback from the power grid representing the constant charging power to be provided to the battery management system. This feedback is therefore a response to the request. For example, the feedback contains authorization regarding the constant charging power with which the battery may be charged. The feedback can also include the time during which the constant charging power is available. The communication through which this feedback is transmitted can take place via the communication channels mentioned above.

[0023] In a further step, the battery charging process begins, initiated by the battery management system, with the required constant charging power. According to the invention, the predefined reference includes a predefined stage profile regarding the constant charging power for charging the battery. The charging process using a constant charging power is a self-regulating process of the battery. At lower voltages (low state of charge - SOC), a higher current is used for charging than at high voltages (high SOC). This also has a positive effect on the battery's lifespan.

[0024] Thus, the inventive method takes into account both the life-saving charging of the battery and a reduction in the load on the power grid.

[0025] The battery used in the method according to the invention is, in particular, a (traction) battery for a means of transportation. For the purposes of this invention, means of transportation include, for example, automobiles, especially cars and / or trucks, and / or aircraft, and / or ships, and / or motorcycles. Thus, means of transportation can also be efficiently integrated into the power supply network with a constant or predictable connection capacity.

[0026] The sub-claims include beneficial further training opportunities.

[0027] According to an advantageous embodiment of the method according to the invention, the current charging parameter comprises a battery state of charge and / or a charging time until a predefined battery state of charge is reached and / or a battery nominal capacity and / or a battery internal resistance and / or a battery temperature, which is determined in particular as described above. The aforementioned charging parameters are also referred to as static charging parameters, since their value is essentially constant when determining the constant target charging power. Furthermore, the current charging parameters include a current gradient in the battery and / or a voltage gradient in the battery and / or a temperature gradient in the battery and / or a change in the battery anode potential and / or a change in the internal cell pressure of a battery cell. These charging parameters are referred to as dynamic charging parameters because they are subject to change.The gradients can be calculated as derivatives with respect to time and / or charge direction (e.g., in the charging direction) and / or voltage and / or temperature and / or other variables. One option is to determine the constant target charging power based on a predefined reference using either static or dynamic charging parameters. Alternatively, static and dynamic charging parameters can be combined to determine the constant target charging power. In this case, a weighting function can be used to find an optimum from the static and dynamic charging parameters, ensuring the battery is charged in a way that protects its age without charging more slowly than necessary. The weighting function can, for example, assign different weights or priorities to the static and dynamic charging parameters. This can, for example,The charging parameters are adjusted depending on the battery's lifespan, particularly its cycle count and / or ampere-hour throughput. The more advanced the battery's lifespan, the greater the weighting of dynamic charging parameters. Conversely, the less advanced the battery's lifespan, the greater the weighting of static charging parameters. This is due, without being tied to a specific theory, to the fact that static characteristic curves become less valid after advanced battery aging. Alternatively, the weighting can be performed using neural networks. Single-layer feedforward networks, multi-layer feedforward networks, and / or recurrent networks are particularly suitable for this purpose. All current charging parameters can be determined using known technical methods.

[0028] According to a further advantageous embodiment of the method according to the invention, the predefined criterion comprises an identification code for the battery and / or generation data from the power grid and / or consumption data from the power grid and / or forecast data from the power grid. The identification code can include an identification number and / or an IP address and / or a pictogram, such as a barcode and / or a QR code. For example, the identification code can be provided by an energy supplier or the grid operator. Preferably, the identification code is unique and unambiguously assignable. For example, a tariff group can be created for the identification code with regard to the constant charging power to be provided. The tariff groups can, for example,The terms "Premium User" (with prioritization), "Extra User" (with limited prioritization), and / or "Basic User" (without prioritization) are used. In other words, Premium User comprises the highest price category, Extra User the middle price category, and Basic User the lowest price category. If the battery's identification code is assigned to a "Premium User" tariff group, the constant charging power to be provided is always equal to the determined constant target charging power. If the battery's identification code is assigned to a "Extra User" group, a lower constant target charging power than the "desired" one may be provided, depending on the energy supply. For example, battery charging may also be prevented during peak electricity generation times for the "Basic User" tariff group.Furthermore, it is possible to prioritize between the aforementioned predefined criteria. This means, for example, that even a premium user can receive a lower constant charging power than the calculated target charging power if the electricity grid generation is low and high grid utilization would be undesirable.

[0029] The same prioritization is also possible with regard to consumption data of the electricity grid or forecast data of the electricity grid.

[0030] In a preferred embodiment of the aforementioned method according to the invention, the step of transmitting the battery's identification code to the power grid is included. The identification code ensures that the power grid's evaluation unit directly recognizes the battery's request and allows and, if necessary, authorizes it. Thus, the transmission of the identification code functions like a password. The transmission of the identification code therefore ensures the secure assignment of the corresponding battery. This drastically reduces the susceptibility to errors in grid management and the risk of incorrect battery charging due to misassignment. The transmission can also be carried out via the aforementioned communication channels.

[0031] In a preferred further development of the two aforementioned further developments, determining the constant charging power to be provided includes recalculating the determined constant charging power and a period over which provision from the grid is guaranteed if the identification coding does not show a prioritization. The constant charging power to be provided is lower than the constant target charging power determined by the battery management system, and in particular, it covers a longer period. The period is extended specifically so that, even with a lower constant charging power, the same amount of energy required for the corresponding battery state of charge can still be provided. This is illustrated by way of example, based on the scenario above. If a request with a constant target charging power, determined by, for example,If the battery management system determines the required charging power for a specific period and sends it to the grid's evaluation unit for the "Basic User" tariff group associated with the identification code, the identification code does not have a prioritization. Accordingly, a lower constant charging power is output over a longer period. This efficiently regulates the grid load and also extends the battery's lifespan. Alternatively, if the identification code has a prioritization, the determination of the required constant charging power will result in a confirmation of the request. In the case of confirmation, the battery can then be charged with the determined constant target charging power. This is the case, for example, in the scenario described above, if the "Premium User" tariff group is assigned to the identification code.

[0032] According to a preferred embodiment of the aforementioned preferred further development, the method according to the invention is carried out again after the guaranteed period has elapsed. A guaranteed period serves the efficiency of grid management and also the gentle charging of the battery. On the one hand, criteria such as generation data from the power grid and / or forecast data from the power grid and / or consumption data from the power grid may necessitate a time limit on a specific constant charging power to be provided. Furthermore, an increase in the constant charging power, i.e., by recalculating it, could also be advantageous, for example, due to low consumption times on the power grid. On the other hand, the battery may also be designed to reduce the charging power after a certain period to conserve its lifespan.An increase up to the maximum charging power is also conceivable if this is sensible in correlation with the predefined reference. This allows the charging time to be optimized without losing sight of the battery's aging condition. Furthermore, it is also conceivable that a prioritization guaranteed to the identification number could be temporarily set, thus ensuring that the determined target charging power is available to the battery for a specified period.

[0033] In a further embodiment of the method according to the invention, the predefined reference comprises a specification from the network operator and / or a specification from the user. The step profile is, for example, designed as a diagram in a two-dimensional coordinate system, with the ordinate representing the charging power. The step profile can, for example, include empirically determined characteristic maps of the constant charging power. The empirical determination can, for example, be carried out via laboratory characterization. Such laboratory characterizations have, for example, resulted in optimized characteristic maps with regard to life-saving constant power charging as a function of the cell chemistry. The abscissa of the characteristic map can, for example, represent the state of charge, the charging time, or the open-circuit voltage. From this, step profiles with regard to life-saving charging can be derived. According to the actual value (e.g.,The service life-optimized constant charging power is determined as a step on the characteristic curves, using the abscissa correlated with the open-circuit voltage. Furthermore, the predefined reference can include a specification from a grid operator. In this case, the energy supplier, i.e., the grid operator, can control the grid load via this specification. The specification can, for example, be derived from forecast calculations of grid consumption and / or grid generation. The specification can be updated regularly via the communication channels mentioned above. Additionally, the predefined reference can include a user specification. This allows user requirements for service life-saving charging to be taken into account. This specification, like the grid operator's specification, is used with the current charging parameters to determine the service life-saving constant target charging power.If the predefined reference includes at least one of the specifications discussed above and the stage profile, or two specifications, then the minimum value of the resulting constant target charging power, which was calculated using these predefined references, is preferably selected for communicating the request in order to charge the battery in the most life-saving way possible in any case.

[0034] In a further advantageous embodiment of the method according to the invention, the profile of the constant charging power to be provided is recorded, and this profile is taken into account when determining the constant charging power. The recording can be performed, for example, by the evaluation unit of the battery management system. The recording can be stored in a memory of the battery management system. Furthermore, the recording can document the day, month, and / or year. In addition, it is also possible to record the generation data and / or consumption data of the power grid at the time of recording. The inclusion of the profile is possible in many variations.The user can, for example, specify that the inclusion of data only occurs on the respective day, month, and / or season when determining the constant target charging power, which is identical or similar to that of the recorded trend. The same applies to the concurrently recorded consumption and / or generation data of the electricity grid. Furthermore, the recorded trends and the associated documented data can be used to determine the target charging power for third-party batteries. This is possible, for example, if the third party's battery is the same type. Additionally, the recorded and documented trend can be used to determine the constant target charging power for batteries with a similar priority (e.g., premium users). Thus, this type of peer-to-peer (P2P) usage allows for...Including recorded data patterns saves computing capacity in the power grid's evaluation unit. Overall, recording and incorporating this data enables faster and more efficient grid management.

[0035] The following aspects of the invention encompass the advantageous embodiments and further developments as well as the general advantages of the device according to the invention and the associated technical effects.

[0036] According to a second aspect, the present invention relates to an evaluation unit of a power grid. This evaluation unit is essentially configured to perform the steps of the evaluation unit according to the first aspect of the invention. The evaluation unit is configured to receive a request from a battery management system, comprising a determined constant target charging power, via the aforementioned communication options. Furthermore, the evaluation unit is configured to determine a constant charging power to be provided based on a predefined criterion, depending on the target charging power, and to send feedback representing the constant charging power to be provided to the battery management system.

[0037] According to a third aspect, the present invention relates to an automobile which includes a battery management system which is configured to participate in the method according to the first aspect of the invention. Brief description of the drawings

[0038] Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings show: Fig. 1 a flowchart illustrating an embodiment of the method according to the invention; Fig. 2 a possible embodiment of an environment of the battery in the charging method according to the invention; Fig. 3 an embodiment of an automobile according to the invention; Fig. 4 the relationship between current and voltage during charging with a power specification in relation to a charger 8; Fig. 5 a possible embodiment of the battery according to the invention as a series connection of cells; Fig. 6 an illustration of an embodiment of the method according to the invention; Fig. 7 another embodiment of a battery environment within the method according to the invention; Fig. 8a and Fig. 8b possible arrangement of the components of an embodiment of the method according to the invention; Fig. 9 an illustration of an embodiment of the method according to the invention in cyclic representation; Fig. 10 an illustration of an embodiment of the step of determining the constant target charging power; Fig. 11a an embodiment of an empirically determined characteristic map with the state of charge as the abscissa; Fig. 11b an embodiment of an empirically determined characteristic map with the charging time up to a predefined state of charge as the abscissa; Fig. 11c an embodiment of an empirically determined characteristic map with the open-circuit voltage as the abscissa; Fig. 12 a capacity curve for different charging methods; Fig. 13 a diagram of a temperature correction curve for certain battery types; Fig. 14 a diagram of a stress gradient; and Fig. 15 a graph of the course of a weighting function for certain battery types.

[0039] One embodiment of the method according to the invention is described in Fig. Figure 1 shows the process. In a first step, a constant target charging power is determined by the evaluation unit 1 (e.g., a CPU and / or a microcontroller) of the battery management system 2. For this purpose, an experimentally determined characteristic map 3a is used. This characteristic map 3a is designed as a two-dimensional Cartesian coordinate system and has the charging power as its ordinate. The abscissa represents the state of charge of the battery 4. The constant static charging powers determined by laboratory characterization are stored as a step profile, i.e., as a step-like graph, in the Cartesian coordinate system. The static charging power is determined based on the current state of charge of the battery 4. Furthermore, a period is determined over which this charging power should be applied. Finally, the temperature of the coldest cell of the battery 4 is determined as a static charging parameter via the evaluation unit 1.The evaluation unit 1 of the battery management system 2 multiplies a temperature correction factor stored in a memory 5 of the battery management system by the determined static charging power. The temperature correction factor can also be determined experimentally. The constant target charging power determined from the multiplication over the determined period is the result of the first step 100.

[0040] In a second step 200, the determined constant target charging power and the determined period are communicated as a request to an evaluation unit 11 (e.g., a CPU and / or a microcontroller) of the power grid 6 connected to the battery 4. Communication takes place via Powerline Communication (PLC) and / or WLAN and / or GSM and / or CAN and / or Ethernet, preferably via Powerline Communication.

[0041] In a third step 300, the identification code 7 of the battery 4 with the assigned prioritization “premium user” is also transmitted to the evaluation unit 11 of the power grid 6.

[0042] In a fourth step 400, the evaluation unit 11 of the power grid 6 determines the constant charging power to be provided based on the identification code 7 over the guaranteed period. Since the identification code 7 has the assigned prioritization "Premium User", the constant charging power to be provided is equal to the constant target charging power determined in the first step 100 over the requested charging time.

[0043] In a fifth step (500), the battery management system 2 receives feedback from the power grid 6 authorizing that the battery 4 may be charged with the requested constant target charging power over the requested period. This communication also takes place via the communication methods mentioned in step 200.

[0044] In a sixth step, the charging process of battery 4 begins via the evaluation unit 1 of the battery management system 2 with the constant charging power to be provided. As explained above, this is, in this case, the determined constant target charging power.

[0045] Fig. Figure 2 shows a possible environment for the battery 4 in the charging method according to the invention. Here, the battery 4 is connected to the mains power supply 6 via a charger 8. The battery management system 2 controls the charging process. The charger 8 adjusts the current and voltage during constant-power charging using the evaluation unit 1 of the battery management system 2.

[0046] Fig. Figure 3 shows an embodiment of an automobile 9 according to the invention, which is connected to the power grid 6 via a charging station as a charger 8 for charging its battery 4. The automobile 9 according to the invention comprises a battery management system 4, which is configured to participate in the method according to the invention.

[0047] Fig. Figure 4 shows the relationship between current and voltage during charging with a power specification in relation to a charger 8. Here, P defines the power, U the voltage, R iThe internal resistance, I the current, and OCV (open-circuit voltage) are used. This is intended to express that, in the present method according to the invention, the battery 4 is not charged with a set current value, but rather with a set charging power value. Accordingly, the charger 8 sets a charging power via the battery management system 2, which results from the current state (e.g., open-circuit voltage and internal resistance) of the battery 4. With constant-power charging, current and voltage adjust themselves almost harmoniously to the battery's state of charge. This is a self-regulating process of the battery 4. At lower voltages (low states of charge), a higher current is used for charging than at high voltages (high states of charge).

[0048] Fig. Figure 5 shows an embodiment of the battery 4 according to the invention as a participant in the inventive method. Here, the battery 4 is depicted as a series connection of cells. The battery management system 2 is connected to it. Using the current and voltage values ​​(static charging parameters) of the battery 4, the battery management system 2 can determine a constant target charging power via the inventive method described above.

[0049] Fig. Figure 6 shows an illustration of an embodiment of the method according to the invention. Here, the battery management system is connected to the battery 4, the charger 8, and the evaluation unit 11 of the power grid 6, or the energy supply company. Furthermore, the charger 8 is connected to the power grid 6. Using the method described above, the battery management system 2, or its evaluation unit 1, can communicate the constant target charging power to the evaluation unit 11 of the power grid 6, whereby the evaluation unit 11 of the power grid 6 provides a constant charging power to charge the battery 4. In addition, a user 10 can also send a desired constant charging power over a period of time as a predefined reference in the form of a specification to the battery management system 2.The determination of the constant target charging power is then carried out based on this specification and depending on a current charging parameter.

[0050] Fig. Figure 7 shows a possible embodiment of the battery 4 environment within the method according to the invention. Here, the battery is connected to a charger 8 which includes an AC / DC converter. Furthermore, the charger 8 is connected to a mains connection 12. The mains connection 12 and the charger 8 together form the charging interface 13.

[0051] Fig. 8a and Fig. Figure 8b shows further possible arrangements of the components within an embodiment of the method according to the invention. In these figures, the battery 4 is that of an automobile 9 according to the invention. Here, the user's specifications 10 can be driver data 14, i.e., data which he can transmit via the automobile according to the invention to the evaluation unit 11 of the battery management system 2 for determining the constant target charging power 100.

[0052] Fig. Figure 9 shows a cyclic representation of an embodiment of the method according to the invention. Within step 100 of determining the constant target charging power, a static charging parameter (e.g., temperature and / or voltage and / or current), which is used as the current charging parameter, is first determined in sub-step 100a via the evaluation unit 1 of the battery management system 2 of the battery 4. In a further sub-step, a static characteristic map 3a, where the ordinate is the charging power and the abscissa is the state of charge (SOC) of the battery 4, is used, for example, via a neural network and / or a weighting function 15, to determine the constant target charging power. The constant target charging power is communicated to the evaluation unit 11 of the power grid 6, and the method continues as described above until charging process 600. Once this is complete, the process starts in Fig. Cycle 9 shown again.

[0053] Fig. Figure 10 shows an embodiment of the first step 100 of determining the constant target charging power of the method according to the invention. After the end of the step, the determined constant target charging power is communicated to the evaluation unit 11 of the power grid via the battery management system 2. The battery management system 2 always considers the minimum constant target charging power for the following three input variables: the weighting function 15, the user's specification 14, and the grid-side specification 18. First, driver data 14 can be used as a predefined reference. This can be requested by the user 9 depending on a required constant charging power. Furthermore, the predefined reference can include a grid specification 18 regarding consumption data and / or generation data and / or forecast data of the power grid 6.In any case, measured values ​​such as temperature, current, and / or voltage of the battery are determined by sensors 17 in order to ascertain static charging parameters, such as the temperature of the smallest cell and / or the state of charge. Furthermore, dynamic charging parameters such as voltage changes can be determined. The static charging parameters are converted to a corrected target charging power using empirically determined characteristic maps 3a, 3b, 3c. Additionally, the dynamic and static charging parameters are weighted 15, for example, by the evaluation unit 1. This weighting is performed depending on the battery's ampere-hour throughput. As long as the weighting function 15 is positive, the weighting factor a of the static charging parameter is weighted more heavily. However, if the weighting function, as shown in... Fig. If 10 becomes noticeably negative, the weighting factor b of the variable, i.e., the dynamic, loading parameters will be weighted more heavily.

[0054] Fig. Figures 11a to 11c show empirically determined characteristic curves 3a, 3b, 3c for battery 4, determined, for example, through laboratory characterization of the cell chemistry with regard to service life, with step profiles, i.e., diagrams with the charging power as the ordinate. Since the charging power is constant for a specific abscissa range, the diagrams are called step profiles. Different charging phases are indicated on the ordinate. The characteristic curves 3a, 3b, 3c can, for example, be displayed on a storage device 5 of the battery management system 5.

[0055] Fig. Figure 12 shows a capacity curve for different charging methods. Compared to conventional charging with constant current (triangles), charging with constant power (squares) offers a lifespan advantage under the same conditions.

[0056] Fig. Figure 13 shows a diagram for determining a temperature correction factor (ordinate) as a function of temperature. These temperature correction factors are determined for different cell chemistries, with different temperature profiles for different NMC (nickel-manganese-cobalt), NCA (nickel-cobalt-aluminum), LFP (iron phosphate), or LTO (titanate). The temperature correction factors are multiplied by the determined charging power from the characteristic maps discussed above.

[0057] Fig. Figure 14 shows a plot of the voltage derivative after charging against the battery's state of charge. This is a dynamic charging parameter (Figure 16). The gradient can also be plotted as the derivative of time, voltage, and other quantities. If the gradient exceeds predefined thresholds, the dynamic charging power setting is changed. If the gradient shown here exceeds the threshold, the charging power is reduced. Conversely, if the gradient falls below the threshold, the charging power is increased.

[0058] Fig. Figure 15 shows the weighting function as a function of the cycles. The weighting is calculated using the following formulas. PLoading=a⋅Pstatic+b⋅Pdynamic a = weighting; b = 1 - weighting

[0059] Here, P Laden the constant charging power while P statisch the constant static charging power is and P dynamischThe dynamic constant charging power is given. a and b are weighting factors. Applicability to cell chemistries

[0060] The method is preferably used with batteries with lithium-ion cell chemistry, such as NMC (nickel-manganese-cobalt), NCA (nickel-cobalt-aluminum), LFP (iron phosphate), or LTO (titanate). However, the constant charging power can also be applied to other batteries or energy storage devices, offering the advantages for the energy supplier described above. Reference symbol list 1 battery evaluation unit 2 Battery management system 3a-3c map 4 batteries 5 storage 6 Power grid 7 Identification coding 8 charger 9 Automobil 10 users 11 Evaluation unit of the power grid 12 Network connection 13 Charging interface 14 Driver data 15 Weighting function 16 Dynamic charging parameters 17 sensors 18 Network specification 100 to 600 process steps

Claims

Method for charging a battery (4) comprising the steps: - Determining (100) a constant target charging power based on a predefined reference (3a-3c) and depending on a current charging parameter of the battery (4); - Communicating (200) a request comprising the determined constant target charging power to an evaluation unit (11) of a power grid (6) connected to the battery (4); - Determining (400) a constant charging power to be provided by the power grid (6) depending on the target charging power based on a predefined criterion by the evaluation unit (11) of the power grid (6), as a result of which - Receiving (500) a response from the power grid (6) representing the constant charging power to be provided to a battery management system (2) of the battery (4);and- initiation (600) of a charging process of the battery (4) by the battery management system (2) with the constant charging power to be provided, characterized in that the predefined reference (3a-3c) comprises a predefined stage profile with respect to the constant charging power for charging the battery (4). The method according to claim 1, wherein the current charging parameter comprises: a state of charge of the battery (4); and / or: a charging time up to a predefined state of charge of the battery (4); and / or: an open-circuit voltage of the battery (4); and / or: a nominal capacity of the battery (4); and / or: an internal resistance of the battery (4); and / or: a temperature of the battery (4); and / or: a current gradient in the battery (4); and / or: a voltage gradient in the battery (4); and / or: a temperature gradient in the battery (4); and / or: a change in the anode potential of the battery (4); and / or: a change in the cell internal pressure of the battery (4). Method according to claim 1 or 2, wherein the predefined criterion comprises an identification code (7) of the battery (4); and / or generation data of the power grid (6); and / or consumption data of the power grid (6); and / or forecast data of the power grid (6). The method according to claim 3 further comprises the step of transmitting (300) the identification coding (7) of the battery (4) to the power grid (6). A method according to one of claims 3 or 4, wherein determining (400) the constant charging power to be provided comprises a re-determination of the determined constant charging power and a period over which the provision of the charging power from the power grid (6) is assured, if the identification coding (7) does not have a prioritization, wherein the constant charging power to be provided comprises a lower constant charging power than the constant target charging power determined by the battery management system (2), and in particular a longer period; or determining (400) the constant charging power to be provided comprises a confirmation of the request if the identification coding (7) has a prioritization. The method according to claim 5, wherein the method is carried out again after the expiry of the assured period. Method according to one of the preceding claims, wherein the predefined reference (3a-3c) comprises a specification of the network operator (18) and / or a specification (14) of the user (10). A method according to one of the preceding claims further comprising the steps of recording a curve of the constant charging power to be provided and taking the curve into account for determining (100) the constant charging power. Evaluation unit of a power grid (11) which is configured to receive a request from a battery management system (2) comprising a constant target charging power determined by a method according to claim 1, wherein the evaluation unit is further configured to determine a constant charging power to be provided depending on the target charging power based on a predefined criterion (7) and to send feedback representing the constant charging power to be provided to the battery management system (2). Automobile (9) comprising a battery management system (2) configured to participate in the method according to any one of claims 1 to 8.

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