Technique for operating an electrical energy store

Abstract

The invention relates to a method (1) for operating an electrical energy store (2), to an electrical energy store (2) for carrying out the method, and to a motor vehicle (3) comprising such an energy store (2). The electrical energy store (2) comprises a plurality of battery modules (4) and a temperature-control device (5) for controlling the temperature of the battery modules (4). The method comprises thermally preconditioning (S20) at least one first battery module (4a). The method (1) furthermore comprises cooling (S40) at least one second battery module (4b) by means of the thermally preconditioned at least one first battery module (4a) during an electrical charging or discharging operation of the at least one second battery module (4b). In the process, heat from the at least one second battery module (4b) is transferred to the at least one first battery module (4a) by means of the temperature-control daevice (5), preferably utilizing the thermal mass of the at least one first battery module (4a) and / or a temperature difference between the at least one first (4a) and second (4b) battery module. The temperature control of the energy store can be improved by means of the proposed technique.

Description

[0001] Technology for operating an electrical energy storage system

[0002] Description

[0003] The invention relates to a method for operating an electrical energy storage device, preferably an energy storage device for a motor vehicle. The invention further relates to an electrical energy storage device and a motor vehicle designed to implement the method.

[0004] With the growing demand for alternative drive systems, electric drive systems are becoming increasingly important. The electrical energy storage systems used in vehicles are usually composed of several battery modules, which in turn typically contain several battery cells. In practice, lithium-ion cells have proven particularly popular because they offer high energy density and can simultaneously deliver comparatively high power. Depending on the application, other battery types such as nickel-cadmium or nickel-metal hydride (NiMH) batteries are also used.

[0005] To achieve optimal performance, the storage cells should be operated within a specific temperature range, depending on the type of storage cell. For this purpose, it is known from the prior art to temperature-control the storage cells using a temperature control device, i.e., the storage cells can be heated or cooled depending on the situation.

[0006] During operation, i.e., during a charging or discharging process, the battery cells heat up. To keep the storage cells within the specified temperature range, they must be cooled using a temperature control device. The temperature control device absorbs heat generated by the battery cells and transports it away from them. For this purpose, the temperature control device typically comprises a fluid circuit with a temperature control fluid and one or more fans, which can be used, for example, to dissipate the heat into the environment, so that the battery cells remain within an optimal temperature range for use.

[0007] Problems can arise in this regard if the temperature control device is unable to dissipate the heat generated by the battery cells in sufficient quantities, e.g., because noise emission regulations limit the fans to reduced power. The invention is therefore based on the object of providing an improved technology for operating an electrical energy storage device that, if possible, also avoids the disadvantages of the previous solution. In particular, it is an object of the invention to provide a technology for operating an electrical energy storage device that enables improved temperature control of the energy storage device.

[0008] The problem is solved by the features of the independent claims. Advantageous further developments are specified in the dependent claims and the description.

[0009] According to a first general aspect of the present disclosure, a method for operating an electrical energy storage device is provided. The electrical energy storage device is preferably an energy storage device for a motor vehicle, e.g., a traction energy storage device. The electrical energy storage device comprises a plurality of battery modules and a temperature control device for controlling the temperature of the battery modules. The battery modules can each comprise one or more battery cells. The battery modules can be arranged individually or in groups in so-called battery packs. In this case, the method can be carried out for battery modules within the battery packs and analogously, for example, for at least a first and at least one second battery pack.

[0010] Temperature control devices for controlling the temperature of battery modules are available in a wide variety of designs in the prior art and are assumed to be known here. The temperature control device can, for example, comprise a device for absorbing and discharging thermal energy from or to the battery modules, a device for transporting the thermal energy, for example, fluid lines filled with a fluid temperature control medium, and a device for discharging thermal energy to the environment, e.g., ambient fans. The temperature control device can further comprise devices for additionally heating or cooling the temperature control medium, for example, an electric heater and a compressor.

[0011] The method comprises the step of thermally preconditioning (temperature control) at least one first battery module. Thermal preconditioning means bringing the first battery module to a predetermined temperature and / or bringing it to a desired temperature state, or changing the temperature of the first battery module in a predetermined direction, i.e., (optionally) increasing or decreasing the temperature. For example, the at least one first battery module can be cooled. The cooling can occur, for example, by a predetermined temperature difference or for a predetermined period of time. The thermal preconditioning can occur, for example, by means of the temperature control device.

[0012] The method further comprises the step of cooling at least one second battery module during an electrical charging or discharging process of the at least one second battery module by the thermally preconditioned at least one first battery module. Heat is transferred from the at least one second battery module to the at least one first battery module by means of the temperature control device. In other words, thermal energy is first absorbed by the at least one second battery module and then transferred to the at least one first battery module by the temperature control device.

[0013] Preferably, the heat is transferred using the thermal mass of the at least one first battery module and / or a temperature difference between the at least one first and second battery module. Thermal mass refers to the property of materials that describes their ability to absorb and store thermal energy. It depends on the specific heat capacity and the mass of the body. The greater the thermal mass of the at least one first battery module, the more heat can be absorbed by the at least one second battery module for a given temperature difference.

[0014] If cold (like heat) is considered as transportable “cold energy”, one can also say that the temperature control device absorbs cold from the at least one first battery module and releases it to the at least one second battery module, so that the at least one second battery module is cooled by means of this cold, which was previously stored in the at least one first battery module.

[0015] Advantageously, the second battery module can be cooled without (necessarily) dissipating heat to the environment. This can be advantageous, for example, if a part of the temperature control device intended to dissipate heat to the environment cannot or should not be operated temporarily, or only at reduced power, for example to avoid the use of a noisy fan or high speeds of a compressor of the temperature control device (e.g., in residential areas and / or at night). The method described above therefore makes it possible to control the temperature and operate the energy storage device even in such cases without disruptive or with reduced noise emissions and / or to achieve increased charging or discharging performance.In addition, this approach can be used to increase the maximum available effective cooling capacity during charging and / or ferry operation and can also be used to achieve a range gain, which will be explained in more detail below.

[0016] In an advantageous embodiment, the thermal preconditioning of the at least one first battery module further comprises thermally decoupling the at least one first battery module from the at least one second battery module and cooling the at least one first battery module by means of the temperature control device to generate a temperature difference between the at least one first battery module and the at least one second battery module. In other words, the at least one first and the at least one second battery module are first thermally decoupled from one another, for example by interrupting fluidic connections of a temperature control circuit between the first and the second battery modules. This allows the first battery modules to be temperature-controlled independently of the second battery modules.The first battery modules are then cooled to a temperature lower than the temperature of the second battery modules. In this way, cooling power for later cooling of the second battery modules can be stored in the first battery modules, e.g., by utilizing the thermal mass of the first battery modules. Preferably, the thermal decoupling is carried out by means of the temperature control device. For example, a first partial fluid circuit of the temperature control device for controlling the temperature of the at least one first battery module can be fluidically separated, e.g., by means of a switching valve, from a second partial fluid circuit of the temperature control device for controlling the temperature of the at least one second battery module.

[0017] In a further advantageous embodiment, the thermal preconditioning of the at least one first battery module further comprises electrically decoupling the at least one first battery module from the at least one second battery module. In an energy storage device, the individual battery modules are typically electrically interconnected and / or interconnectable, e.g., in series or parallel. By appropriately opening or disconnecting the interconnection, e.g., by means of electrical switches, the electrical connection can be severed, so that the electrical power input and power output of the decoupled battery modules can occur independently of one another. In this way, the first and second battery modules can be charged and / or discharged at different power levels.Additionally or alternatively, the thermal preconditioning of the at least one first battery module can comprise cooling the at least one first battery module to a temperature that is below a temperature range that specifies a permissible temperature range and / or target temperature range for a charging and / or discharging process. As mentioned above, battery modules have a target temperature range that depends on the battery cell type, in which they are ideally operated. Operation above or below the target temperature range can result in increased cell aging or even damage to the battery cells. In order to ensure efficient cooling, and thus operation within the target temperature range, of the second battery modules, for example under difficult cooling conditions, the temperature of the first battery modules can be below the target temperature range orof the permissible temperature range, as this allows the cooling capacity stored within the first battery modules to be increased for efficient cooling of the second battery modules. Cooling to a temperature below the target temperature range preferably only occurs for a limited period of time and / or if the at least one first battery module is not itself being charged or discharged.

[0018] In a further advantageous embodiment, the method for operating the electrical energy storage device further comprises the step of thermally preconditioning (tempering) the at least one second battery module to a temperature that is higher than a temperature of the thermally preconditioned at least one first battery module before the at least one second battery module is cooled by the at least one first battery module. The thermal preconditioning of the at least one second battery module can preferably be carried out by cooling or heating. Particularly preferably, the thermal preconditioning of the at least one second battery module is carried out to a temperature that corresponds to a target temperature for a charging and / or discharging process of the battery modules.In this way, increased cell aging and / or temperature-related damage to the battery modules, for example due to excessively high temperatures, can be counteracted and effective use of the second battery modules can be enabled.

[0019] According to a further embodiment, the cooling of the at least one second battery module is controlled or regulated by the thermally preconditioned at least one first battery module. A dedicated or existing control unit, such as a central battery controller, can be used for this purpose. Through the controlled or regulated cooling of the second battery modules, the amount of heat transferred from the second battery modules to the first battery modules can be specifically influenced and adjusted by appropriate control or regulation. In this way, the temperature of the second battery modules can be controlled particularly effectively.

[0020] In a further advantageous embodiment, the method for operating the electrical energy storage device further comprises cooling the at least one second battery module by means of the temperature control device during an electrical charging or discharging process of the at least one second battery module. The temperature control device provides further cooling power in addition to the cooling power provided by the thermally preconditioned at least one first battery module. This can be done, for example, by releasing thermal energy into the ambient air. Advantageously, this can provide a higher maximum available effective cooling power during charging and / or discharging, since the "normal" cooling power that can be generated by the temperature control device and the cooling power provided by the thermally preconditioned at least one first battery module are added together.Preferably, the additional cooling capacity is provided selectively by the temperature control device, for example, only in predetermined operating situations. In the image in which the cold is viewed as transportable cooling energy, this means that part of the cold used to cool the second battery modules is provided by the cooling capacity stored in the first battery modules, and an additional part is "generated" by the temperature control device. Cooling capacity can be generated, for example, by dissipating heat energy to other components or to the ambient air. This can be supported, for example, by the use of fans or a compressor chiller. In this way, particularly needs-based and efficient cooling of the second battery modules can be achieved.

[0021] According to a further embodiment, the method for operating the electrical energy storage device can further comprise the step of equalizing the electrical charge states of the battery modules of the energy storage device. The equalizing step takes place after the electrical charging or discharging process of the at least one second battery module has taken place while being cooled by the thermally preconditioned at least one first battery module. At the beginning of the step, the first battery modules can have a higher or lower charge state than the second battery modules. Depending on the situation, the charge states can be equalized by a charging or discharging process of the first and / or the second battery modules. By equalizing the charge states of the battery modules, the battery modules can subsequently be electrically interconnected again in a simplified manner.

[0022] In a further advantageous embodiment, the method for operating the electrical energy storage device further comprises selectively heating the at least one first battery module after the electrical charging or discharging process of the at least one second battery module has taken place while being cooled by the thermally preconditioned at least one first battery module. In this way, the thermally preconditioned at least one first battery module, after being used as a "cooling module," can be heated again to a target temperature that is prescribed and / or at least advantageous for the continued use of the first battery module in ("normal") charging and / or discharging operation.

[0023] According to a further embodiment, the thermal preconditioning of the at least one first battery module is carried out before an external charging process, preferably shortly or immediately before an external charging process, of the energy storage device and / or when the energy storage device is to be charged at a specific known time. The cooling of the at least one second battery module by the thermally preconditioned at least one first battery module is then carried out at the beginning and / or during a first phase of the charging process. The first phase of the charging process comprises, for example, a first third of the entire charging process. The cooling of the second battery modules by the first battery modules can therefore begin immediately at the beginning of the charging process or at a somewhat later time.The cooling of the second battery modules by the first battery modules can also extend beyond the first phase of the charging process, as long as the cooling process began within the first phase. An external charging process corresponds to charging at a power source external to the energy storage device, e.g., at a charging station.

[0024] During the charging process of an energy storage device, a lot of heat can be generated, depending on the charging power. To prevent the energy storage device from overheating, this heat must be dissipated or compensated for. If it is known that the energy storage device is about to be charged and that cooling power is required to cool the energy storage device, cooling power can be generated by thermally preconditioning the first battery modules before the charging process begins and stored within the first battery modules. This pre-generated cooling power can then be used later to cool the second battery modules during the charging process. In this way, less, or even no, additional cooling power needs to be generated during the charging process. This can significantly reduce the noise emissions generated by the cooling device.Alternatively, if the cooling capacity of the thermally preconditioned at least one first battery module is used in addition to a (“normal”) cooling capacity generated by the temperature control device, a higher charging capacity can be achieved, e.g. while complying with noise emission limits.

[0025] Analogously, in a further advantageous embodiment, the thermal preconditioning of the at least one first battery module can be carried out after an external charging process of the energy storage device, preferably before the start of the journey, particularly preferably immediately before the start of the journey, or when a departure time is imminent. The cooling of the at least one second battery module by the thermally preconditioned at least one first battery module is then carried out at the start of the journey. The electrical drive energy can only be provided by the at least one second battery module, while the thermally preconditioned at least one first battery module is preferably only used for cooling. Analogous to the charging process, the start of the journey refers to a period of time that is located during a first phase of the journey. The start of the cooling process can accordingly occur immediately at the start of the journey or somewhat later.Similarly, when the vehicle is about to depart, cooling power can be pre-generated, which is then available later during the journey for particularly efficient cooling of the energy storage unit. This can advantageously enable particularly quiet ferry operation, for example, at night in a residential area, where cooling of the energy storage unit is generated solely by the thermally preconditioned at least one first battery module, eliminating the need for noisy fan operation in normal cooling mode.

[0026] According to a further embodiment, the thermal preconditioning of the at least one first battery module and / or the cooling of the at least one second battery module is carried out by the thermally preconditioned at least one first battery module when a monitored condition, hereinafter referred to as the activation condition, is met. In this way, particularly efficient use of the cooling capacity of the temperature control device can be ensured. Advantageously, different activation conditions can be defined in advance, each indicating operating situations in which the thermal preconditioning can be advantageously used and preferably automatically activated. This is explained below by way of example:

[0027] The monitored activation condition can be met, for example, if a charging or discharging process of the energy storage device is to be carried out at a point, i.e. at a location and / or at a time at which and / or when noise emissions from the temperature control device during the charging or discharging process are to be reduced and / or a predetermined limit value, e.g. a noise emission, is to not be exceeded. This can be done, for example, to comply with legal requirements, e.g. noise protection in residential areas, and / or to improve comfort for a vehicle driver, e.g. when a driver is resting in the cab of a commercial vehicle. By pre-generating cooling power by thermally preconditioning the first battery modules before the charging or discharging process, the cooling power required by the temperature control device to cool the second battery modules can be reduced or possibly avoided altogether.A check as to whether this activation condition is met can be carried out, for example, using map data from a navigation system to check whether the energy storage device or the vehicle with the energy storage device is located in a residential area.

[0028] The monitored activation condition can optionally also be met if the maximum cooling capacity is to be increased during an external charging process and / or a cooling operation of the energy storage device. For example, if it is known that the operation of the energy storage device produces more heat than can be dissipated by the temperature control device, the effectively available cooling capacity can be increased by additionally using the cooling capacity stored in the first battery modules. In this way, it can be avoided that the energy storage device's capacity has to be reduced in order to prevent permissible temperatures from being exceeded. A possible example of a situation where such an activation condition can be met is, for example,This is the case when the energy storage device is to be used as a traction energy storage device for a motor vehicle to provide energy for an upcoming long and / or steep uphill stretch, where it is foreseeable that more cooling capacity than usual will be needed or at least advantageous. Additionally or alternatively, this activation condition can be met if the ambient temperature exceeds a predetermined limit, for example, if it is very hot.

[0029] Furthermore, the monitored activation condition can be met, for example, if the range of the energy storage device is to be increased by thermally storing cooling power before departure, wherein the thermal preconditioning of the at least one first battery module before departure takes place using an external power supply. To operate the temperature control device, energy must be expended, which is typically taken from the energy storage device as long as the energy storage device is not connected to an external power supply. This reduces the range of the energy storage device. If, on the other hand, cooling power is stored in the first battery modules and the generation of the cooling power occurs while an external power supply is being used for this purpose, this cooling power does not need to be generated using energy from the energy storage device. Accordingly, the range of the energy storage device can be advantageously increased.

[0030] Overall, the method described above can, for example, provide a higher maximum available effective cooling capacity during charging and / or discharging (e.g., during ferry operation). Furthermore, effective cooling capacity with no or reduced noise emissions, higher charging capacity while complying with noise emission limits, and the provision of higher electrical power from the electrical energy storage system while complying with noise emission limits for a certain period of time can be enabled. A possible increase in the operating time of the energy storage system, e.g., in the form of a range increase of an electrically powered vehicle through thermal storage of cooling capacity before departure, as well as a possible range increase through additional optimization potential, are also possible.

[0031] According to a further general aspect of the present disclosure, an electrical energy store is provided, preferably for a motor vehicle. The electrical energy store comprises a plurality of battery modules, wherein the plurality of battery modules have at least a first battery module and at least one second battery module. Furthermore, the electrical energy store comprises a temperature control device for temperature control of the battery modules and a control device for controlling the battery modules and the temperature control device. The control device is designed to carry out the method according to one of the preceding claims. In other words, the features described in this document in connection with the method for operating an electrical energy store per se should also be disclosed and claimable in connection with the electrical energy store. Preferably, the term “control device” can refer to electronics (e.g.B. embodied as a driver circuit or with microprocessor(s) and data memory) and / or a mechanical, pneumatic, and / or hydraulic control system, which, depending on its design, can perform control tasks and / or regulation tasks and / or processing tasks. Even if the term "control" is used herein, it can also appropriately include or mean "regulation" or "control with feedback" and / or "processing."

[0032] In an advantageous embodiment, the temperature control device has at least one switching device, preferably at least one valve device, for a temperature control fluid. The switching device can be controlled by the control device such that the at least one first battery module can be selectively thermally and / or fluidically coupled and decoupled from the at least one second battery module. For example, switchable valves, e.g., solenoid valves, can selectively permit, reduce, or completely block the flow of the temperature control fluid between the first and second battery modules. Optional feed pumps can be used to increase the flow rate of the temperature control fluid and preferably to control or regulate it.

[0033] According to a further general aspect of the present disclosure, a motor vehicle comprising an electrical energy storage device as described above is provided. In other words, the features described in this document in connection with the electrical energy storage device per se are also intended to be disclosed and claimable in connection with the motor vehicle. The motor vehicle can, for example, be a purely electrically driven motor vehicle. The motor vehicle is preferably a commercial vehicle (e.g., a truck or bus). In this case, a commercial vehicle can generally be understood to mean a vehicle which, due to its design and equipment, is specifically designed for the transport of persons, the transport of goods, or the towing of trailers. Overall, this advantageously makes it possible to provide a vehicle whose energy storage device can be temperature-controlled particularly efficiently.In particular, the temperature control of the energy storage system can be particularly well adapted to different usage situations.

[0034] The previously described preferred embodiments and features of the invention can be combined with one another as desired. Further details and advantages of the invention are described below with reference to the accompanying drawings. They show: Figure 1 shows a schematic illustration of an electrical energy storage device with a temperature control device according to one embodiment;

[0035] Figure 2 is a schematic illustration of an electrical circuit of the electrical energy storage device from Figure 1;

[0036] Figure 3 is a schematic block diagram illustrating the method for operating an electrical energy storage device according to one embodiment; and

[0037] Figure 4 shows a motor vehicle with an electrical energy storage device according to a further embodiment of the invention.

[0038] The embodiments shown in the figures correspond at least partially, so that similar or identical parts are provided with the same reference numerals and for their explanation reference is also made to the description of the other embodiments or figures in order to avoid repetition.

[0039] Figure 1 shows an electrical energy storage device 2 that can be operated using a method for operating an energy storage device 2. The electrical energy storage device 2 can, for example, be the electrical energy storage device 2, e.g., a traction energy storage device, of a vehicle. The electrical energy storage device 2 comprises a plurality of battery modules 4, here merely three battery modules as an example, in each of which individual or multiple battery cells (not shown separately) are arranged. Optionally, the battery modules 4 can be arranged individually or in groups in battery packs.

[0040] Battery modules 4 and battery cells of electrical energy storage devices 2 must be maintained within a target temperature range dependent on the battery type during operation, i.e., during charging and discharging processes, to prevent premature cell aging or even damage or destruction of the battery cells. For this purpose, the electrical energy storage device 2 comprises a temperature control device 5 for controlling the temperature of the battery modules 4.

[0041] Electrical energy storage devices 2 and temperature control devices 5, which can cool or heat battery modules 4 depending on the situation, are available in many designs in the prior art and are assumed to be known here. By way of example, the temperature control device 5 comprises a device (not explicitly shown) for the absorption and discharge of thermal energy from or to the battery modules 4, a device for transporting thermal energy, for example designed as fluid lines 9 filled with a fluid temperature control medium, and a device (not shown) for dissipating thermal energy to the environment, for example an ambient fan. A switching device 7, for example designed as switchable valves, e.g. solenoid valves, can be arranged in or on the fluid lines, with which the flow of the temperature control medium through the fluid circuit can be controlled. In addition, it can optionally comprise devices for additional heating orCooling the temperature control medium below or above the ambient temperature can include, for example, an electric heating device 11 and a cooling device 10, e.g., designed as a cooling compressor. The heating device 11 can be used, for example, to bring the battery modules 4 to an ideal operating temperature if the battery modules 4 are too cold due to previous use or cold outside temperatures. Furthermore, the temperature control device 5 can include, for example, a feed pump 8, with which the temperature control medium can be conveyed through the fluid lines 9.

[0042] The electrical energy storage device 2 comprises a control device 6, which is in signal communication with the individual components of the temperature control device 5. The control device 6 can, for example, open and close the valves of the switching device 7, preferably switching them to a state of lower flow rate. Optionally, the control device 6 can be connected to the feed pump 8 in order to further influence the flow rate of the temperature control fluid through the fluid lines 9. Furthermore, it can preferably switch the cooling device 10 and the heating device 11 on or off in order to influence the temperature of the coolant and optionally to control it above or below the ambient temperature. The control device 6 can be a dedicated control unit, or an existing control device can be used, for example, a central battery control unit typically found in electrical energy storage devices.

[0043] If the battery modules 4 become warm during operation, the temperature control device 5 can absorb heat from the battery modules 4 according to a typical method from the prior art and release it to the ambient air, for example by means of ambient fans.

[0044] Figure 2 again shows the electrical energy storage device 2 from Figure 1, wherein in Figure 2, instead of the temperature control device and the fluidic connections, a purely exemplary electrical circuitry of the energy storage device 2 is shown schematically. This means that instead of the fluid lines, the electrical lines 15 are shown, which connect the individual battery modules 4, 4a, 4b both to one another and to at least one electrical consumer 14. The at least one electrical consumer 14 can, for example, be an electric traction machine of a vehicle and / or include other consumers, e.g., auxiliary units. Each of the battery modules 4, 4a, 4b comprises, among other things, a plurality of battery cells, as well as a switching device 16, e.g., contactors, in order to optionally electrically connect or disconnect the individual battery modules 4, 4a, 4b to one another and / or to the consumer 14.The battery modules 4, 4a, 4b may further comprise module controls (not shown).

[0045] The electrical energy storage device 2 further comprises a battery control unit 12, which is illustrated here as an example of a battery controller for a master battery module. The battery control unit, like the control device described in Figure 1, can be a separate component or part of an existing control device, e.g., a central battery control device. The battery control unit 12 can, in particular, be part of the control device 6 of Figure 1.

[0046] The battery control unit 12 of Figure 2 is connected, for example, to the battery modules 4, 4a, 4b by means of signal lines 13 and can electrically couple or decouple the individual battery modules 4, 4a, 4b from the other battery modules 4, 4a, 4b and from the electrical load 14 by means of an electrical switching device 16, which comprises, for example, contactors.

[0047] Difficulties in operating the electrical energy storage device 2 can arise, for example, if the cooling capacity of the temperature control device is insufficient to keep the battery modules 4, 4a, 4b within the target temperature range. This can be the case, for example, if the cooling capacity of the temperature control device 5 is insufficient due to external conditions, such as very high outside temperatures. It is also possible that the temperature control device can or should only be operated at reduced power, for example, to avoid disruptive noise emissions from ambient fans, e.g., in residential areas.

[0048] If the cooling capacity of the temperature control device is insufficient to keep the battery modules 4, 4a, 4b within the target temperature range, the power consumption or power output of the electrical energy storage device 2 must be reduced or even completely stopped to prevent damage to or destruction of the electrical energy storage device 2. To avoid this problem, a method for operating an electrical energy storage device 2 is presented below.

[0049] Figure 3 schematically illustrates a method 1 for operating an electrical energy storage device using a block diagram.

[0050] First, in step S20, at least one first battery module is thermally preconditioned, for example, cooled using the previously described temperature control device. In other words, in step S20, cooling power is stored in the at least one first battery module for later use.

[0051] Subsequently, at least one second battery module is charged or discharged. Meanwhile, in step S40, the at least one second battery module is cooled by the thermally preconditioned at least one first battery module by transferring heat from the second battery module (to be cooled) to the (preconditioned) first battery module. This means that the cooling power previously stored in the at least one first battery module can be used in step S40 to cool the at least one second battery module.

[0052] Method 1 can be carried out, for example, with the electrical energy storage device presented in Figures 1 and 2. Therefore, the method and advantageous embodiments are explained below with reference to Figures 1 and 2.

[0053] In Figure 1, the energy storage device 2 comprises, by way of example, a first battery module 4a, which is thermally preconditioned according to step S20, and a second battery module 4b, which is cooled according to step S40 using the cooling power pre-stored in the first battery module 4a. Other numbers of first and second battery modules are of course also possible. To carry out the method, all battery modules 4 of the energy storage device 2 can be divided into first 4a and second 4b battery modules, or the method can be limited to a portion of the total battery modules 4. Accordingly, Figure 1 shows a battery module 4 that is marked as neither the first nor the second battery module.

[0054] To carry out the method, the first battery module 4a is thermally preconditioned in the first step. This means that the first battery module 4a is brought to a specific temperature or modified in a specific direction. For example, the first battery module 4a is cooled. Whenever a (first) or (second) battery module is mentioned here, multiple battery modules can also be meant.

[0055] The first battery module 4a is cooled by means of the temperature control device 5. In order to be able to cool the first battery module 4a independently of the other battery modules 4, the battery modules 4 can be selectively thermally (fluidically) coupled or decoupled by means of the switching device 7, i.e., the valves of the switching device 7 can be opened and closed such that cold temperature control fluid can flow through the fluid lines 9 to the first battery module 4a, thereby cooling it. The first battery module 4a can optionally be cooled to a temperature that is below the target temperature range or even below the permissible temperature range for a charging and / or discharging process of the first battery module 4a.The valves that direct the temperature control medium to the remaining battery modules 4 are preferably closed or at least set to a lower flow rate to prevent excessive cooling of the remaining battery modules 4. In this way, a temperature difference can arise between the first 4a and the second 4b battery module, so that cooling power is stored for later use within the first battery module 4a, e.g., by utilizing the thermal mass of the first battery module 4a. Switching times and target temperatures of the battery modules 4 can, for example, be fixed, for example, based on previously experimentally determined values.

[0056] The method can be carried out, for example, by the control device 6, which accordingly controls the valves of the switching device 7, as well as optionally the flow rate of the feed pump 8 and the behavior of the cooling and heating devices 10, 11. In this way, the cooling of the first battery module 4a can be controlled or regulated.

[0057] The method is preferably carried out when a previously defined, monitored activation condition is met. For this purpose, the control device 7 can preferably access further data relating to the energy storage device 2, environmental data, and / or possible vehicle data. The data can include, for example, data from sensors of the energy storage device 2 or the vehicle connected to the control device 6, internet data, or data from sensors in the vicinity of the energy storage device 2. The monitored activation condition can be met, for example, when a charging or discharging process of the energy storage device 2 is to be carried out at a point, i.e., at a location and / or at a time, at which and / or at which noise emissions from the temperature control device 5 during the charging or discharging process are to be reduced and / or are not to exceed a predetermined limit value.This can be done, for example, to comply with legal requirements and / or to improve comfort for a vehicle driver. Furthermore, the monitored activation condition can be met, for example, if a maximum cooling capacity is to be increased during an external charging process and / or ferry operation of the energy storage device 2, or if a range of the energy storage device 2 is to be increased by thermally storing cooling capacity before departure. In this case, the thermal preconditioning of the at least one first battery module 4a should be performed before departure and preferably using an external power supply.

[0058] In the next step (step S40 as described above), the cold previously stored in the thermally preconditioned first battery module 4a is used to cool the second battery module 4b. This pre-stored cooling capacity can be used, for example, if the cooling capacity of the remaining temperature control device 5 is insufficient to operate the second battery module 4b at the intended power, i.e., to charge or discharge it. The second battery module 4b is cooled by transferring heat from the second battery module to the first battery module 4b by means of the temperature control device 5. In other words, the cold pre-stored in the first battery module 4a is transferred to the second battery module 4b by means of the temperature control device 5. For this purpose, the valves of the switching device 7 are opened or closed such that a temperature control medium flow takes place between the (cold) first battery module 4a and the (warm) second battery module 4b.Additional cooling of the second battery module 4b using the remaining temperature control device 5 is optionally possible, for example, to further increase the maximum cooling capacity. It is also possible to temporarily cool the second battery module 4b exclusively using the cooling capacity of the preconditioned first battery module 4a, for example, if ambient fans need to be switched off to reduce noise.

[0059] Figure 4 shows a schematic representation of a motor vehicle 3 with an electrical energy storage device 2 according to one embodiment of the invention. The electrical energy storage device, for example a traction energy storage device, of a motor vehicle 3 is particularly well suited for the method described above. It is understood that the techniques and features described with reference to Figure 4 can be combined with the techniques and features described with reference to Figures 1 to 3, individually or in any combination. The motor vehicle 3 can - as shown by way of example - be designed as a commercial vehicle (e.g., a tractor unit or a truck with a body). However, the motor vehicle 3 can also be a passenger car. Preferably, the motor vehicle 3 is an at least partially or purely electrically powered motor vehicle 3.The electrical energy storage device 2 can be arranged on a longitudinal outer side of the motor vehicle 3 or at another location.

[0060] In the following, further possible embodiments of the method 1 for operating an electrical energy storage device 2 of a motor vehicle 3 are explained using various example situations.

[0061] The proposed method involves thermally and electrically decoupled individual battery modules or individual battery packs as needed, in order to utilize the thermal mass—i.e., the thermal storage capacity of the individual battery modules (battery packs)—to cool other connected battery modules (battery packs). This cooling by a thermally preconditioned battery module can be carried out in parallel with "normal" cooling using a connected temperature control device (e.g., a refrigeration circuit with a compressor) or independently. The thermally decoupled battery modules can be thermally preconditioned independently, depending on the respective requirements; for example, they can be cooled below the target temperature range.

[0062] The thermal decoupling can be used, for example, before, during and after an electrical charging process, before the start of the journey of the motor vehicle 3 and during the journey of the motor vehicle 3.

[0063] The procedure is then explained using examples for the two use cases “before charging” and “before starting the journey”.

[0064] The first example case refers to the situation that before the charging process of the electrical energy storage device 2, it is known that the electrical energy storage device 2 is to be charged in the near future or at a specific time.

[0065] The first battery modules (or battery packs) are then thermally preconditioned (cooled). For this purpose, it may be advisable to disconnect the corresponding battery modules (battery packs) from the electrical grid in order to avoid negative effects, e.g., rapid aging of the corresponding battery modules. The first battery modules selected for thermal preconditioning and the second battery modules intended for subsequent cooling can, if necessary, be conditioned independently of one another, i.e., they can be brought to different temperatures. If vehicle 3 is in ferry operation, the second battery modules (battery packs) not selected for thermal preconditioning and connected to the electrical grid provide the energy for the remaining ferry operation until charging.This can mean that if battery modules (battery packs) are disconnected from the electrical grid, the SoCs (state of charge) of the first and second battery modules (battery packs) can diverge. The thermally preconditioned first battery modules (battery packs) now represent an energy storage unit that can be used to cool the remaining battery modules (battery packs) separately or in parallel with the "normal" cooling system of the second battery modules using the conventional temperature control system.

[0066] Next, the (not pre-cooled) second battery modules (battery packs) are optionally thermally conditioned, i.e. they can be brought to an ideal or suitable target temperature for the subsequent charging process.

[0067] At the beginning of the charging process, there are now "active" second battery modules (battery packs) that are within a temperature range suitable for charging, and the thermally preconditioned "passive" first battery modules (battery packs) that can be used to cool the active second battery modules. Depending on the temperature level, the "passive" first battery modules (battery packs) may not be able to be charged or may only be charged with a reduced charging current. The cooling input, with which the "active" second battery modules can be cooled by means of the thermally preconditioned "passive" first battery modules, can be designed to be controllable or adjustable.

[0068] In the first phase of the charging process, the "active" battery modules (battery packs), which are ready for charging, are charged to a defined SoC and / or until a defined temperature level is reached. The remaining "passive" battery modules (battery packs) can be used as needed to cool the charging "active" battery modules (battery packs). The thermally preconditioned first battery modules (battery packs), which are used for cooling, are heated by the waste heat from the charging process of the "active" second battery modules (battery packs).

[0069] When the first phase of the charging process is complete, the already charged battery modules (battery packs) and those used for cooling are at different SoCs. The following combinations are possible: a) The charged second battery modules (battery packs) have a higher SoC than the first battery modules; b) The charged "active" second and the "passive" first battery modules (battery packs) have the same SoC, because, for example, the energy consumption while driving (after the first battery modules have been uncoupled and before the charging process begins, i.e. while the "passive" first battery modules (battery packs) were not connected to the electrical grid) exactly corresponds to the charging energy with which the "active" second battery modules (battery packs) were charged in the first phase of the charging process; c) The charged second battery modules (battery packs) have a lower SoC than the first battery modules.

[0070] In order to subsequently reconnect the first and second battery modules (battery packs) to form a complete battery, the following steps can be carried out in case a):

[0071] “Passive” first battery modules (battery packs) that have not yet been charged have either been brought to a temperature level suitable for charging using the waste heat from the previous charging of the “active” second battery modules (battery packs) or are thermally conditioned for charging (e.g. using a heating device of the temperature control device, e.g. an HV heater). Next, the already charged (“active” second) battery modules (battery packs) are disconnected from the electrical grid and the corresponding battery modules (battery packs) that have not yet been charged are connected to the electrical grid. The battery modules (battery packs) are then charged to a common SoC level and can optionally also be thermally conditioned to a common temperature level. For this purpose, the thermal storage capacity of the not yet charged battery modules (battery packs) can be used, or alternatively, a thermal (if necessary)Battery-module-specific conditioning can be performed using the temperature control device. Finally, all battery modules (battery packs) can be reconnected to the electrical grid once the same SoC level has been reached.

[0072] In case b), the first and second battery modules (battery packs) already have an identical SoC level. This case can represent a particularly advantageous embodiment with particularly great benefit potential and can be achieved by appropriately selecting the timing of the thermal and electrical decoupling. In order to reconnect the battery modules to form an overall battery, the uncharged "passive" first battery modules (battery packs) can optionally be thermally conditioned to a target temperature for charging, for example, if they have not already reached a corresponding temperature level due to the waste heat of the charged "active" second battery modules (battery packs). All battery modules (battery packs) can then be connected and optionally further charged together to a defined SoC and / or temperature level.

[0073] In case c), in which the charged second battery modules (battery packs) have a lower SoC than the first battery modules, the not yet charged "passive" first battery modules (battery packs) can be thermally conditioned to a target temperature for charging, analogous to case a), provided they have not already reached a corresponding temperature level, for example, due to the waste heat from the charged "active" second battery modules (battery packs). The previously "active" second battery modules (battery packs) can then be disconnected from the electrical grid, and the previously "passive" first battery modules (battery packs) are connected to the electrical grid. The previously "passive" first battery modules (battery packs) can now be used "actively." Newly "passive" battery modules (battery packs) can possibly be used as thermal storage devices, analogous to the previously "passive" first battery modules (battery packs).

[0074] The second use case refers to the situation in which the ferry service of motor vehicle 3 is to commence in the near future or in which a departure time is known.

[0075] Analogous to the previous application, the first step is to thermally precondition (cool) the "passive" first battery modules (or battery packs). Optionally, the corresponding battery modules (battery packs) are disconnected from the electrical grid to prevent negative effects, such as accelerated aging of the corresponding battery modules. As before, the first battery modules selected for thermal preconditioning and the second battery modules intended for subsequent cooling can be conditioned independently of each other, if necessary.

[0076] If vehicle 3 requires additional electrical energy, this can be fed in from a charging station or taken from the non-decoupled battery modules (battery packs). This can mean that if battery modules (battery packs) have been disconnected from the electrical grid, the SOCs of the battery modules (battery packs) can diverge. The "passive" first battery packs now represent an energy cooling storage device that can be used to cool the remaining battery modules (battery packs), optionally in parallel with the "conventional" cooling using the temperature control device. The cooling input transferred from the "passive" first battery modules (battery packs) to the second battery modules (battery packs) can preferably be designed to be controllable or adjustable.

[0077] Next, as in the previous example, the (not pre-cooled) second battery modules (battery packs) are optionally thermally conditioned, i.e. they can be brought to an ideal or suitable target temperature for subsequent ferry operation.

[0078] At the start of ferry operation, there are battery modules (battery packs) that are within a temperature range suitable for electrical use, and thermally preconditioned first battery modules (battery packs) that can be used for cooling. Depending on the temperature level, however, the "passive" first battery modules (battery packs) may not be able to supply any or only a reduced current if their temperature is below a target temperature range suitable for discharging due to thermal preconditioning.

[0079] The “active” second battery modules (battery packs) supply the energy for the ferry operation (e.g. at the beginning or during the first phase of the journey) of the motor vehicle 3. The thermally preconditioned “passive” first battery modules (battery packs) are heated by the waste heat of the “active” second battery modules (battery packs).

[0080] Due to the electrical use of the "active" battery modules (battery packs), while the thermally preconditioned "passive" first battery modules (battery packs) used for cooling may be used less or not at all, the SoCs of the "passive" first and "active" second battery modules (battery packs) may diverge.This can result in the following cases: a) The “active” second battery modules (battery packs) have a lower SoC than the “passive” first battery modules (battery packs); b) The “passive” first battery modules (battery packs) and the “active” second battery modules (battery packs) have the same SoC, for example because the energy consumption from the “active” second battery modules (battery packs) just corresponded to the start SoC offset between the first and second battery modules (battery packs); c) The “active” second battery modules (battery packs) have a higher SoC than the “passive” first battery modules (battery packs), for example because they started with a higher SoC level.

[0081] In case a), the "passive" first battery modules (battery packs) can be brought to a temperature level suitable for ferry operation, if they have not already reached this level by cooling the "active" second battery modules (battery packs). Next, the "active" second battery modules (battery packs) can be disconnected from the electrical grid, and the previously "passive" first battery modules (battery packs) can be connected to the electrical grid, where they can now be actively used. Once the first and second battery modules (battery packs) reach the same SoC, all battery modules (battery packs) can be connected to form a single battery.

[0082] In case b), the first and second battery modules (battery packs) already have an identical SoC level. The "passive" first battery modules (battery packs) have either been heated to a temperature level suitable for ferry operation using the waste heat from the "active" second battery modules (battery packs) or can be heated to a target temperature level suitable for the discharge process using the temperature control device, e.g., using the (electrical) heating device. The previously "passive" first battery modules (battery packs) can then be connected to the electrical grid and used together with the already "actively" used second battery modules (battery packs).

[0083] In case c), the "passive" first battery modules (battery packs) were either brought to a temperature level suitable for ferry operation by the waste heat of the "active" second battery modules (battery packs) or can be brought to a temperature level suitable for the discharge process using the temperature control device, e.g., an HV heater. Subsequently, the previously "active" second battery modules (battery packs) are disconnected from the electrical grid, and the previously "passive" first battery modules (battery packs) are connected to the electrical grid. The previously "passive" first battery modules (battery packs) can now be actively used. The remaining battery modules (battery packs) can optionally be used as thermal mass to cool the electrical energy storage unit 2. The scenarios described as examples for charging and starting the journey can be combined with one another.If available, recuperation of an energy-regenerating braking system can also be used to align SOCs of “active” and “passive” battery modules (battery packs) or to specifically shift SoCs and temperature levels.

[0084] Overall, the process creates a multitude of degrees of freedom that can be used for specific operating strategies and objectives. In particular, the number and selection of the first and second battery modules (battery packs), the timing of thermal and electrical coupling and decoupling, as well as the target temperatures and / or target SoC levels can be defined, for example, through an offline application, through tuning, or through optimization for specific use cases and deployment scenarios, or optimized online.

[0085] In ferry operation, the scenario described as an example for the start of the journey can be used analogously to provide additional cooling capacity, for example in zones where only low noise emissions are permitted and cooling by means of ambient fans, for example, is limited, in order to possibly provide higher electrical power.

[0086] The described process is conceivable not only for battery-electric commercial vehicles, but also for any type of battery system in which different battery modules can be conditioned to different temperature levels. In particular, the process would also be conceivable for battery-electric passenger cars.

[0087] Although the invention has been described with reference to specific embodiments, it will be apparent to one skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. Consequently, the invention is not intended to be limited to the disclosed embodiments, but is intended to include all embodiments falling within the scope of the appended claims. In particular, the invention also claims protection for the subject matter and features of the dependent claims, independent of the referenced claims. List of Reference Symbols

[0088] 1 Method for operating an electrical energy storage device

[0089] 2 Electrical energy storage

[0090] 3 Motor vehicle

[0091] 4 Battery module

[0092] 4a First battery module

[0093] 4b Second battery module

[0094] 5 Tempering device

[0095] 6 Control device

[0096] 7 Switching device

[0097] 8 Pump

[0098] 9 Fluid line

[0099] 10 Cooling device

[0100] 11 Heating device

[0101] 12 Battery control

[0102] 13 Signal line

[0103] 14 Electrical consumer

[0104] 15 Electrical cable

[0105] 16 Electrical switching device

Claims

Patent claims 1. Method (1) for operating an electrical energy storage device (2), preferably an energy storage device (2) for a motor vehicle (3), wherein the electrical energy storage device (2) comprises a plurality of battery modules (4) and a temperature control device (5) for temperature control of the battery modules (4), wherein the method comprises: thermal preconditioning (S20) of at least one first battery module (4a);and during an electrical charging or discharging process of at least one second battery module (4b), cooling (S40) the at least one second battery module (4b) by the thermally preconditioned at least one first battery module (4a), wherein heat is transferred from the at least one second battery module (4b) to the at least one first battery module (4a) by means of the temperature control device (5), preferably by utilizing the thermal mass of the at least one first battery module (4a) and / or a temperature difference between the at least one first (4a) and second (4b) battery module.; 2. Method (1) according to claim 1, wherein the thermal preconditioning (S20) of the at least one first battery module (4a) comprises: thermal decoupling of the at least one first battery module (4a) from the at least one second battery module (4b), preferably by means of the temperature control device (5); and Cooling the at least one first battery module (4a) by means of the temperature control device (5) to generate a temperature difference between the at least one first battery module (4a) and the at least one second battery module (4b).

3. The method (1) according to claim 1 or 2, wherein the thermal preconditioning (S20) of the at least one first battery module (4a) comprises: electrically decoupling the at least one first battery module (4a) from the at least one second battery module (4b); and / or cooling the at least one first battery module to a temperature that is below a temperature range that specifies a permissible temperature range and / or target temperature range for a charging and / or discharging process.

4. Method (1) according to one of the preceding claims, further comprising: before the cooling (S40) of the at least one second battery module (4b) by the at least one first battery module (4a), thermally preconditioning, preferably by cooling or heating, the at least one second battery module (4b) to a temperature which is higher than a temperature of the thermally preconditioned at least one first battery module (4a) and which preferably corresponds to a target temperature for a charging and / or discharging process of the battery modules (4).

5. Method (1) according to one of the preceding claims, wherein the cooling (S40) of the at least one second battery module (4b) is controlled or regulated by the thermally preconditioned at least one first battery module (4a).

6. Method (1) according to one of the preceding claims, further comprising: Cooling the at least one second battery module (4b) by means of the temperature control device (5) during an electrical charging or discharging process of the at least one second battery module (4b), wherein in addition to the cooling power provided by the thermally preconditioned at least one first battery module (4a), the temperature control device (5) provides, preferably selectively, a further cooling power.

7. Method (1) according to one of the preceding claims, further comprising: Equalizing electrical charge states of the battery modules (4) of the energy storage device (2) after the electrical charging or discharging process of the at least one second battery module (4b) has taken place while being cooled by the thermally preconditioned at least one first battery module (4a).

8. Method (1) according to one of the preceding claims, further comprising: selectively heating the at least one first battery module (4a) after the electrical charging or discharging process of the at least one second battery module (4b) is carried out with cooling by the thermally preconditioned, at least one first battery module (4a).

9. Method (1) according to one of the preceding claims, wherein the thermal preconditioning of the at least one first battery module (4a) is carried out before an external charging process, preferably immediately before an external charging process, of the energy storage device (2), or when the energy storage device (2) is to be charged at a specific known time, and wherein the cooling (S40) of the at least one second battery module (4b) is carried out by the thermally preconditioned, at least one first battery module (4a) at the beginning and / or during a first phase of the charging process.

10. Method (1) according to one of the preceding claims, wherein the thermal preconditioning of the at least one first battery module (4a) is carried out after an external charging process of the energy storage device (5), preferably before the start of the journey, particularly preferably immediately before the start of the journey, or when a departure time is imminent, and wherein the cooling (S40) of the at least one second battery module (4b) by the thermally preconditioned, at least one first battery module (4a) is carried out at the start of the journey.

11. Method (1) according to one of the preceding claims, wherein the thermal preconditioning (S20) of the at least one first battery module (4a) and / or the cooling (S40) of the at least one second battery module (4b) is carried out by the thermally preconditioned, at least one first battery module (4a) when a monitored activation condition therefor is fulfilled.

12. Method (1) according to claim 11, wherein the monitored activation condition is met if at least one of the following conditions is met: a) a charging or discharging process of the energy storage device (2) is to be carried out at a location and / or which is carried out at a time at which and / or at which a noise emission of the temperature control device (5) during the charging or discharging process is to be reduced and / or not to exceed a predetermined limit, for example to comply with legal requirements and / or to improve comfort for a driver of a vehicle; b) a maximum cooling capacity during an external charging process and / or a ferry operation of the energy storage device (2) is to be increased; and c) a range of the energy storage device (2) is to be increased by thermally storing cooling capacity before departure, wherein the thermal preconditioning (S20) of the at least one first battery module (4a) is carried out before departure using an external power supply.

13. Electrical energy storage device (2), preferably for a motor vehicle (3), comprising a plurality of battery modules (4), wherein the plurality of battery modules (4) have at least a first battery module (4a) and at least one second battery module (4b); a temperature control device (5) for temperature control of the battery modules (4); and a control device (6) for controlling the battery modules (4) and the temperature control device (5), wherein the control device (6) is designed to carry out the method (1) according to one of the preceding claims.

14. Electrical energy storage device (2) according to claim 13, wherein the temperature control device (5) has at least one switching device (7), preferably at least one valve device, for a temperature control fluid, which can be controlled by the control device (6) such that the at least one first battery module (4a) can be selectively thermally coupled and decoupled from the at least one second battery module (4b).

15. Motor vehicle (3), preferably a commercial vehicle, comprising an electrical energy storage device (2) according to claim 13 or 14.

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