Traction battery for a vehicle electrical system, corresponding vehicle electrical system, and method for operating a vehicle electrical system

Abstract

The invention relates to a traction battery (5) for the electrical system (1) of a motor vehicle, comprising a cell arrangement (16) with several battery cells (9) electrically connected to electrical battery terminals (6, 7, 8) of the traction battery (5). A first DC-DC converter (13) is electrically connected to a first part of the battery cells (9) providing a first electrical voltage, and a second DC-DC converter (14) is electrically connected to a second part of the battery cells (9) that differs from the first part. The first DC-DC converter (13) and the second DC-DC converter (14) are electrically connected in parallel to a first battery terminal (6) and / or a second battery terminal (7) of the battery terminals (6, 7, 8) of the traction battery (5).The invention further relates to an on-board electrical system (1) for a motor vehicle and a method for operating an on-board electrical system (1) for a motor vehicle.

Description

[0001] The invention relates to a traction battery for the electrical system of a motor vehicle, comprising a cell arrangement with several battery cells that are electrically connected to electrical battery terminals of the traction battery. The invention further relates to an electrical system for a motor vehicle and a method for operating such an electrical system.

[0002] For example, the prior art includes German patent application DE 10 2019 102 306 A1. This describes a method for a low-voltage power supply in vehicles with a modular battery, in which the modular battery has several battery modules arranged in strings, in which each battery module has at least two switches and at least one energy storage device, in which the respective strings are connected at their first two-wire end to a double neutral point and at their respective second end form a respective phase of a supply voltage in a high-voltage system, wherein an additional low-voltage power supply string is connected at the double neutral point, wherein at least one module with two connections, one on a neutral point side and one on a low-voltage supply side, is arranged in the low-voltage power supply string, wherein at least two switches are located within the at least one module.by which at least the two connections on the neutral point side are separable from the double neutral point and the two connections on the low-voltage supply side are connected in parallel to the double neutral point, and wherein a module storage device is arranged in the at least one module in parallel to the connections on a low-voltage supply side.

[0003] Furthermore, German patent application DE 10 2022 120 021 B3 discloses a method and a circuit for a DC-DC converter integrated into an AC battery. The AC battery is considered to be a modular multilevel converter comprising several strings of battery modules. The strings are connected at one end to a double star point and at the other end provide a multiphase high-voltage supply for a traction system. The battery modules are connected in a symmetrical module topology. A connection to each terminal, as well as a connection to all positive potentials and a connection to all negative potentials of the first battery module in each string, are used as auxiliary connections.These auxiliary connections are used to connect converters which can be resonantly controlled by means of switching control of the half-bridges directly adjacent to the double star point, thus forming DC voltage converters for an auxiliary power supply.

[0004] Furthermore, EP 3 945 657 A1 discloses a device comprising: active battery cell material; and an internal circuit coupled to the active battery cell material comprising: one or more switches connected to battery cell terminals of the device; and a processor that actuates the one or more switches to provide a defined value of electrical potential at the battery cell terminals.

[0005] The object of the invention is to propose a traction battery for an on-board electrical system of a motor vehicle which has advantages over known traction batteries, in particular a particularly flexible design of the on-board electrical system and preferably the elimination of a separate energy storage device in the on-board electrical system.

[0006] According to the invention, this is achieved with a traction battery for the electrical system of a motor vehicle with the features of claim 1. It is provided that a first DC-DC converter is electrically connected to a first part of the battery cells providing a first electrical voltage, and a second DC-DC converter is electrically connected to a second part of the battery cells that differs from the first part, in particular providing a second electrical voltage different from the first, wherein the first DC-DC converter and the second DC-DC converter are electrically connected in parallel to a first battery terminal and / or a second battery terminal of the traction battery.

[0007] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments described in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are possible.

[0008] The traction battery is preferably part of the vehicle's electrical system; however, it can, of course, also be separate from it, particularly until the traction battery is installed on or in the electrical system and / or the vehicle. Similarly, the vehicle preferably has the electrical system containing the traction battery, but the electrical system can also be located separately from the vehicle. The traction battery is designed and configured for the intermediate storage of electrical energy for the vehicle's drive system. The drive system serves to propel the vehicle, thus providing drive torque for propelling the vehicle.To provide the drive torque, the drive unit has at least one drive unit, which is designed as an electric traction machine that is electrically connected to the traction battery.

[0009] The traction battery comprises several battery cells, preferably prismatic or pouch cells. These battery cells are electrically connected to the traction battery's electrical terminals. During normal operation, the battery cells are at least temporarily connected to the vehicle's electrical system or other components of the system via these terminals. The electrical terminals are located, for example, on the traction battery's housing, in which the battery cells are arranged.

[0010] Preferably, each battery cell is electrically connected to the battery terminals and / or at least temporarily electrically connected to them. The multiple battery cells are part of the cell assembly. The battery cells can also be divided into one or more battery modules. In the case of a single battery module, all battery cells are part of that module. If multiple battery modules are present, each module contains at least one battery cell; conversely, each battery cell is part of exactly one battery module. Whenever this description refers to the battery module, the explanations preferably always apply to each of the multiple battery modules. Conversely, explanations relating to the multiple battery modules apply analogously to the battery module or each of the battery modules.The battery module, or each of the multiple battery modules, has at least one battery cell, for example exactly one of the battery cells or several of the battery cells.

[0011] Where this description refers to the battery cell or at least one battery cell, the statements are equivalent. Explanations concerning the battery cell are therefore applicable to the at least one battery cell, and vice versa. Likewise, statements concerning the battery cell or at least one battery cell are preferably applicable to each of the multiple battery cells, in particular to each of the battery cells of the respective battery module.

[0012] The battery module may be provided with end plates and / or a clamping device. The end plates are, for example, part of a battery module housing and accommodate the battery cell(s) of the respective battery module between them. The battery cell(s) are arranged between the end plates and clamped, for example, by means of the clamping device to form the battery module. In this respect, the end plates are arranged on opposite sides of the battery cell(s). Preferably, the battery module is cuboid or at least approximately cuboid. In the simplest case, it comprises one or more battery cells. Optionally, the battery module has the end plates and / or the clamping device.

[0013] If the battery module has several battery cells, these are preferably electrically interconnected. For this purpose, the battery cells are arranged, for example, such that their electrical connections are on the same side and / or facing each other. The connections are electrically connected to each other, for example, by one or more busbars, which are preferably also electrically connected to module terminals of the battery module and / or the battery terminals of the traction battery. In other words, the battery cells of the battery module are electrically connected to the terminals, in particular to the module terminals and / or the battery terminals, via the busbars. The battery cells are preferably connected electrically in series.

[0014] The traction battery preferably has a battery housing in which a battery module receptacle is provided and designed to receive the battery modules. During the manufacturing process of the traction battery, the battery cells, for example, grouped together to form a single battery module or several battery modules, are inserted into the battery module receptacle. Accordingly, the battery housing has a battery module receptacle which is provided and designed to receive the battery cells and, in particular, several battery modules.

[0015] In addition to the cell arrangement comprising multiple battery cells, the traction battery has several DC-DC converters, at least a first DC-DC converter and a second DC-DC converter. The first DC-DC converter is connected on one side (input side) to the first set of battery cells and on the other side (output side) to the first and / or second battery terminal of the traction battery. The second DC-DC converter is also connected on one side (input side) to the second set of battery cells and on the other side (output side) to the first and / or second battery terminal of the traction battery.

[0016] This means that the two DC-DC converters, the first and the second, are electrically connected on their input side to different parts of the cell array or the multiple battery cells. On their output side, they are at least partially connected in parallel and electrically connected to at least one or both of the battery terminals, more precisely, the first and second battery terminals. The first and second battery cells are characterized in particular by the fact that they provide different electrical voltages: the first cell provides the first voltage, and the second cell provides the second voltage. These two voltages are distinct from each other.For example, the first part comprises a first number of battery cells and the second part a second number of battery cells, where the first and second numbers are different from each other. However, it is also possible for both parts of the battery cells to provide identical voltages, so that the first voltage and the second voltage are the same.

[0017] It can be provided that the multiple battery cells are divided between the first part and the second part, such that the two parts contain different battery cells. This means that there is no overlap between the battery cells assigned to the first part and the battery cells assigned to the second part; each battery cell is therefore assigned to either the first part or the second part. Preferably, however, some of the battery cells are part of both the first part and the second part of the battery cell array.

[0018] For example, all battery cells assigned to the first part are also assigned to the second part, whereas at least some of the battery cells assigned to the second part are not part of the first part of the battery cells. For instance, it is provided that the first part of the battery cells comprises only a portion of the multiple battery cells, and the second part comprises all of the multiple battery cells. This provides the preferred, different voltages for the DC-DC converters; in particular, the second voltage is higher than the first voltage.

[0019] In summary, the two DC-DC converters are supplied with electrical energy on the input side by the battery cells from different parts of the battery cells, for example, with different input voltages. On the output side, the two DC-DC converters are at least partially connected in parallel. This means that both DC-DC converters are electrically connected either to the first battery terminal but not the second, or to the second battery terminal but not the first, or to both battery terminals, i.e., both the first and the second battery terminal.

[0020] It is possible to connect the two DC-DC converters in parallel to the first battery terminal. The first DC-DC converter is, for example, additionally connected to the second battery terminal, and the second DC-DC converter to a third battery terminal. The first battery terminal has a first electrical potential, the second battery terminal a second electrical potential, and the third battery terminal a third electrical potential. Thus, there is, for example, a first potential difference, corresponding to a first electrical voltage, between the first and second battery terminals, and a second potential difference, corresponding to a second electrical voltage, between the first and third battery terminals. The first and second electrical voltages can be identical or different.For example, the first battery terminal is a negative terminal, and the second and third battery terminals are positive terminals.

[0021] The two DC-DC converters are connected electrically in parallel to the first and second battery terminals. They are preferably operated in such a way that their output voltages are identical, so that, for example, a common output voltage of both DC-DC converters is present between the first and second battery terminals. The two DC-DC converters reliably supply the vehicle's electrical system, or at least a sub-system of it, with electrical energy.

[0022] The subnetwork is preferably a low-voltage subnetwork. The output voltage of the two DC-DC converters is less than 100 V, preferably at most 60 V, and particularly preferably at most 48 V, at most 24 V, or at most 12 V. For example, the first voltage provided by the battery cells is also less than 100 V, preferably at most 60 V, and particularly preferably at most 48 V, at most 24 V, or at most 12 V.

[0023] The first DC-DC converter is preferably designed to provide electrical energy at the battery terminals with a particularly high efficiency. For example, the first DC-DC converter has a first rated power and the second DC-DC converter has a second rated power, the second rated power being different from, and in particular higher than, the first rated power. Preferably, the first rated power is at most 240 W, at most 160 W, or at most 100 W, particularly at an output voltage of 12 V.

[0024] This provides a quiescent current supply to the vehicle's electrical system when the vehicle is stationary. Accordingly, electrical consumers in the vehicle's electrical system can be reliably supplied with power using the first DC-DC converter, for example, the vehicle's door locks. The second rated power is preferably higher than the first rated power, in particular more than 240 W, and most preferably at least 400 W, at least 600 W, or at least 800 W. Therefore, consumers with higher current requirements can also be operated using the second DC-DC converter.

[0025] A further development of the invention provides that the first DC-DC converter is electrically connected to a first electrical pole of the cell arrangement having a first electrical potential and to a second electrical pole of the cell arrangement having a second electrical potential, and the second DC-DC converter is electrically connected to the first electrical pole or the second electrical pole of the cell arrangement and to a third electrical pole of the cell arrangement having a third electrical potential. The first electrical voltage is present between the first electrical pole and the second electrical pole and corresponds to the difference between the second electrical potential and the first electrical potential.

[0026] The second electrical potential lies between the first and third electrical terminals. It corresponds to the difference between the third electrical potential and the first electrical potential. The first terminal is, for example, a negative terminal, while the second and third terminals are positive terminals. The first part of the battery cells is located between the first and second electrical terminals. The second part of the battery cells is located between the first and third electrical terminals. It follows that the battery cells of the first part are also part of the second part of the battery cells. With this configuration, the aforementioned advantages can be achieved particularly easily.

[0027] The first DC-DC converter is designed to be connected to the first and second electrical terminals. The second DC-DC converter is preferably connected either to the first and third electrical terminals or to the second and third electrical terminals. In each case, the DC-DC converters are electrically connected on their input side to a common terminal of the cell array and on their output side to a common battery terminal. This ensures a high degree of flexibility in operating the traction battery and the vehicle electrical system.

[0028] A further development of the invention provides that the first part of the battery cells is electrically connected on one side to the first electrical pole and on the other side to the second electrical pole, and the second part of the battery cells is electrically connected on the one side to the first electrical pole and on the other side to the third electrical pole. Such a configuration of the traction battery has already been mentioned. It also serves to achieve the advantages described above.

[0029] A further development of the invention provides that the battery cells are components of battery modules, wherein a first part of the battery modules is electrically connected on one side to the first electrical pole and on the other side to the second electrical pole, and a second part of the battery modules is electrically connected on one side to the second electrical pole and on the other side to the third electrical pole, each of the battery modules comprising at least one of the battery cells and a switch arrangement. The presence of the battery modules has already been mentioned. The battery cells are distributed among the battery modules, for example, evenly.

[0030] Preferably, the traction battery has several battery modules, for example, a number of battery modules corresponding to the number of battery cells in the traction battery divided by an integer divisor. The divisor is, for example, equal to one or alternatively greater than one, for example, at least two, at least five, or at least ten. Preferably, each of the battery modules has a specific number of battery cells, the number being preferably identical for all battery modules. The battery cells are thus distributed evenly among the battery modules.

[0031] The battery modules are divided into a first and a second part, with the first part comprising a first number of battery modules and the second part a second number of battery modules. The first part of the battery modules is electrically connected in series between the first and second electrical terminals; the second part of the battery modules is electrically connected in series between the second and third electrical terminals. In addition to at least one battery cell, each battery module has at least one switch assembly. The switch assembly comprises at least one switch and serves to bypass the battery cell(s) of the respective battery module. This allows each battery module to be selectively activated or deactivated. This ensures flexible operation of the traction battery.

[0032] A further development of the invention provides that each of the battery modules has a first module connection and a second module connection, wherein at least one of the battery cells is electrically connected to the first module connection and the second module connection via a first switch of the switch arrangement and a second switch of the switch arrangement in parallel to the at least one battery cell and the first switch. The two module connections, i.e., the first module connection and the second module connection, are located, for example, on a battery module housing of the battery module in which the battery cell or battery cells of the battery module are accommodated. Additionally, the switch arrangement, which includes at least the first switch and the second switch, is located in the battery module housing.

[0033] The first switch is electrically arranged between the at least one battery cell and the module terminals, specifically between the battery cell and the first module terminal or between the battery cell and the second module terminal. Using the first switch, the battery cell can be selectively electrically connected to or disconnected from the first or second module terminal. In a first switching position of the first switch, the battery cell is electrically connected to both the first and second module terminals, and in a second switching position, it is electrically disconnected from at least one of them. The first switch thus enables the battery cell to be switched off, preventing it from supplying electrical energy to the module terminals.

[0034] The second switch is also electrically connected between the first and second module terminals. It is wired in parallel with the battery cell and the first switch. In the first switching position of the second switch, the first and second module terminals are directly connected, bypassing the battery cell. In the second switching position of the second switch, they are electrically isolated or, depending on the switching position of the first switch, connected only via the battery cell.

[0035] Preferably, in a connection setting of the battery module, the third switch is in its first switching position and the second switch is in its second switching position, whereas in a bypass setting of the battery module, the first switch is in its second switching position and the second switch is in its second switching position. In the connection setting, the battery cell is electrically connected to the module terminals; in the bypass setting, it is disconnected from the module terminals. Such a configuration of the battery module or traction battery enables the targeted activation or deactivation of individual or multiple battery modules of the traction battery.

[0036] A further development of the invention provides that a third DC-DC converter is electrically connected in parallel to the second DC-DC converter to the second electrical terminal and / or the third electrical terminal and / or the second part of the battery cells, in particular to the first electrical terminal and the third electrical terminal, wherein the third DC-DC converter is electrically connected to the first battery terminal and a third battery terminal. The third DC-DC converter is provided in addition to the first DC-DC converter and the second DC-DC converter. Its input is electrically connected in parallel to the second DC-DC converter to one or both of the aforementioned electrical terminals and / or the second part of the battery cells.In the latter case, the input voltage of the third DC-DC converter is equal to the input voltage of the second DC-DC converter. Preferably, the third DC-DC converter, like the second DC-DC converter, is electrically connected to the first and third electrical terminals.

[0037] The third DC-DC converter provides a third output voltage. Preferably, this corresponds to the output voltage of the first DC-DC converter and / or the output voltage of the second DC-DC converter, but it can also be different from them. The third DC-DC converter provides electrical energy at battery terminals that are different from at least one of the battery terminals to which the first DC-DC converter and the second DC-DC converter are connected. Preferably, the third DC-DC converter is connected to the first battery terminal and the third battery terminal, wherein, in particular, the first battery terminal is a negative terminal and the third battery terminal is a positive terminal.

[0038] The third DC-DC converter preferably serves to provide electrical energy for another subnetwork of the vehicle electrical system. For example, the first DC-DC converter and / or the second DC-DC converter supply a first vehicle electrical system, and the second DC-DC converter supplies a second subnetwork. Both the first and second subnetworks are preferably low-voltage subnetworks, so that they operate at a comparatively low voltage. This has already been mentioned.

[0039] The first and second subnetworks are preferably electrically isolated from each other or only electrically connected via DC-DC converters. In this respect, the two subnetworks can be operated independently. Preferably, the third DC-DC converter has a rated power that is at least equal to, but preferably higher than, the rated power of the second DC-DC converter. This allows the third DC-DC converter to be used to operate loads with a comparatively high energy demand.

[0040] The invention further relates to an on-board electrical system for a motor vehicle, comprising a traction battery, in particular a traction battery as described in this description, wherein the traction battery has a cell arrangement comprising several battery cells which are electrically connected to electrical battery terminals of the traction battery.It is provided that a first DC-DC converter is electrically connected to a first part of the battery cells providing a first electrical voltage, and a second DC-DC converter is electrically connected to a second part of the battery cells that differs from the first part, in particular providing a second electrical voltage different from the first electrical voltage, wherein the first DC-DC converter and the second DC-DC converter are electrically connected in parallel to a first battery terminal and / or a second battery terminal of the traction battery.

[0041] The advantages of such a design for the electrical system and the traction battery have already been mentioned. Both the electrical system and its traction battery can be further developed as explained in this description, and reference is made to those explanations.

[0042] A further development of the invention provides that the traction battery is electrically connected via the first DC-DC converter and the second DC-DC converter to a first subnetwork of the vehicle electrical system and via a third DC-DC converter to a second subnetwork of the vehicle electrical system. Such a configuration of the vehicle electrical system has already been discussed. With the aid of the traction battery, both the first and the second subnetwork can be reliably supplied with electrical energy. Accordingly, additional energy storage devices in the subnetworks are unnecessary and therefore preferably not provided. The two subnetworks are thus designed without energy storage devices.This excludes, of course, the capacities and / or inductances necessarily present in the subnetworks; these are not intended for the targeted intermediate storage of electrical energy over a relevant period, but arise from necessities unrelated to energy supply. The weight of the vehicle electrical system can be significantly reduced by means of the described design of the traction battery and the vehicle electrical system.

[0043] The invention also relates to a method for operating an on-board electrical system for a motor vehicle, in particular an on-board electrical system according to the explanations in this description, wherein the on-board electrical system comprises a traction battery with a cell arrangement having several battery cells which are electrically connected to electrical battery terminals of the traction battery.It is provided that a first DC-DC converter is electrically connected to a first part of the battery cells providing a first electrical voltage, and a second DC-DC converter is electrically connected to a second part of the battery cells that differs from the first part, in particular providing a second electrical voltage different from the first electrical voltage, wherein the first DC-DC converter and the second DC-DC converter are electrically connected in parallel to a first battery terminal and / or a second battery terminal of the traction battery and are operated at least temporarily to provide electrical energy from the traction battery at the battery terminals.

[0044] Reference is again made to the explanations in this description regarding the advantages and possible beneficial further training opportunities.

[0045] A further development of the invention provides that at least one of the following steps is carried out: supplying electrical energy with the second DC-DC converter deactivated by means of the first DC-DC converter; adjusting an electrical voltage supplied by the second DC-DC converter to a voltage present between the battery terminals; supplying electrical energy with the first DC-DC converter deactivated by means of the second DC-DC converter; and adjusting an electrical voltage supplied by the first DC-DC converter to the voltage present between the battery terminals. For example, several or all of the aforementioned steps are carried out, particularly in the order given.

[0046] In the first operating state of the vehicle's electrical system, electrical energy is supplied to the battery terminals, specifically for the subnetwork or first subnetwork, using the first DC-DC converter. The second DC-DC converter, however, is deactivated. This means that the electrical energy at the battery terminals is supplied using electrical energy drawn from the first set of battery cells.

[0047] In a second operating state of the vehicle electrical system, the second DC-DC converter is activated, and the voltage it provides at its output, also known as the output voltage, is adjusted to match the voltage present between the battery terminals. In other words, the second DC-DC converter is operated in such a way that it provides the same electrical voltage at its output as the first DC-DC converter.

[0048] In the third operating state of the vehicle electrical system, the first DC-DC converter is deactivated, and the electrical energy at the battery terminals is supplied using the second DC-DC converter. Switching between the first or second operating state and the third operating state occurs in such a way that there is no interruption in the power supply to the battery terminals.

[0049] In a fourth operating state of the vehicle electrical system, the first DC-DC converter is activated and its output voltage is adjusted to match the voltage between the battery terminals, which is the voltage supplied by the second DC-DC converter. The system can then switch back to the first operating state, again without interrupting the power supply.

[0050] Preferably, the electrical energy at the battery terminals is supplied using the first DC-DC converter while the vehicle is stationary. During operation, the electrical energy is supplied using the second DC-DC converter. If a third DC-DC converter is present in addition to the first and second DC-DC converters, the electrical energy at the battery terminals is preferably supplied by the first DC-DC converter as long as the third DC-DC converter is deactivated.

[0051] If the third DC-DC converter is deactivated, the system switches from the first DC-DC converter to the second DC-DC converter to provide electrical power to the battery terminals. This ensures that, with the first DC-DC converter deactivated, the second DC-DC converter takes over the power supply. This guarantees a flexible and highly efficient supply of electrical power.

[0052] The features and combinations of features described in the description, in particular those described in the following figure description and / or shown in the figures, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention, in particular the scope of the claims. Thus, embodiments that are not explicitly shown or explained in the description and / or the figures, but which emerge from or can be derived from the explained embodiments, particularly within the scope of the claims, are also to be considered as encompassed by the invention.

[0053] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The drawing shows: Fig. 1 a schematic representation of an on-board electrical system for a motor vehicle, which has several sub-networks and a traction battery, as well as Fig. 2 a schematic representation of a battery module of the traction battery.

[0054] The Fig. Figure 1 shows a schematic representation of an electrical system 1 for a motor vehicle. The electrical system 1 comprises a first subnetwork 2, a second subnetwork 3, and a third subnetwork 4, which are shown here only in a highly schematic form. The first subnetwork 2 and the second subnetwork 3 are preferably low-voltage subnetworks, i.e., they have a nominal voltage or operating voltage of less than 100 V, preferably at most 60 V, and particularly preferably at most 48 V, 24 V, or 12 V. The third subnetwork 4, on the other hand, is a high-voltage subnetwork with a nominal voltage or operating voltage of at least 100 V, preferably at least 200 V, 400 V, or 800 V.

[0055] The vehicle electrical system 1 has a traction battery 5, which supplies subnetworks 2, 3, and 4 with electrical energy or current. For this purpose, subnetworks 2 and 3 are connected to battery terminals 6, 7, and 8 of the traction battery 5. Battery terminals 6, 7, and 8 are in turn electrically connected to battery cells 9 of the traction battery 5, which are not shown individually here. The battery cells 9 are components of battery modules 10, three of which are shown here as examples.

[0056] The battery modules 10 are electrically connected in series between two high-voltage battery terminals 11 and 12. The third subnetwork 4 is electrically connected to the traction battery 5 via the high-voltage battery terminals 11 and 12. The traction battery 5 also has a first DC-DC converter 13, a second DC-DC converter 14, and a third DC-DC converter 15. The first DC-DC converter 13 is electrically connected to the battery modules 10 such that it receives a first voltage from them. The second DC-DC converter 14 is electrically connected to the battery modules 10 such that it receives a second voltage, and the third DC-DC converter 15 is connected such that it receives a third voltage.

[0057] For this purpose, a cell arrangement 16, which is composed of the battery cells 9, has a first electrical pole 17, a second electrical pole 18, a third electrical pole 19 and a fourth electrical pole 20. The poles 17, 18, 19 and 20 are electrically connected to the cell arrangement 16 such that the first electrical pole 17 has a first electrical potential, the second electrical pole 18 a second electrical potential, the third electrical pole 19 a third electrical potential and the fourth electrical pole 20 a fourth electrical potential.

[0058] The first electrical voltage applied to the input side of the first DC-DC converter 13 is located between the first electrical terminal 17 and the second electrical terminal 18. The second electrical voltage applied to the second DC-DC converter 14 is located between the second electrical terminal 18 and the third electrical terminal 19, and the third electrical voltage for the third DC-DC converter 15 is located between the third electrical terminal 19 and the fourth electrical terminal 20. Accordingly, some of the three DC-DC converters 13, 14, and 15 are each electrically connected to one of the electrical terminals 17, 18, 19, and 20, respectively.

[0059] Alternatively, the three DC-DC converters 15 are each electrically connected to the first electrical terminal 17. In this case, the third electrical terminal 19 is preferably omitted. The first DC-DC converter 13 is then additionally connected to the second electrical terminal 18, and the second DC-DC converter 14 and the third DC-DC converter 15 are additionally connected to the fourth electrical terminal 20. The first electrical terminal 17 is, for example, a negative terminal, whereas the second electrical terminal 18 and the fourth electrical terminal 20 are each positive terminals.

[0060] The first electrical terminal 17 is directly connected to the high-voltage battery terminal 11, and the fourth electrical terminal 20 is directly connected to the high-voltage battery terminal 12. The second electrical terminal 18 branches off between two of the battery modules 10, as does the third terminal 19. On the output side, the three DC-DC converters 13, 14, and 15 are each electrically connected to the first battery terminal 6. The first DC-DC converter 13 and the second DC-DC converter 14 are connected in parallel to the second battery terminal 7, and the third DC-DC converter 15 is connected to the third battery terminal 8.

[0061] In an alternative embodiment, the second DC-DC converter 14 is omitted, leaving only the first DC-DC converter 13 and the third DC-DC converter 15. The first DC-DC converter 13 is electrically connected to the first electrical terminal 17 and the second electrical terminal 18; the third DC-DC converter 15 is connected to the second electrical terminal 18 and the fourth electrical terminal 20. The third electrical terminal 19 is not necessary and can be omitted. On the output side, the first DC-DC converter 13 and the third DC-DC converter 15 are connected together to the first battery terminal 6. Furthermore, the first DC-DC converter 13 is connected to the second battery terminal 7 and the third DC-DC converter 15 is connected to the third battery terminal 8.

[0062] The Fig.Figure 2 shows, purely as an example, a schematic representation of the battery module 10 of the traction battery 5. The battery module 5 has a first module terminal 21 and a second module terminal 22, between which one or more of the battery cells 9 are connected, in particular electrically in series. Additionally, the battery module 10 has a first switch 23 and a second switch 24. The first switch 23 is electrically connected in series with the battery cells 9 between the module terminals 21 and 22. The second switch 24 is arranged electrically in parallel with the battery cells 9 and the first switch 23 between the module terminals 21 and 22.

[0063] Using switches 23 and 24, the battery cells 9 can be selectively connected to the module terminals 21 and 22, or the module terminals 21 and 22 can be connected directly to each other, bypassing battery cell 9. This allows the battery cells 9 of the battery module 10 to be selectively used to supply the vehicle electrical system 1 with electrical energy. This results in particularly flexible operation of the vehicle electrical system 1. REFERENCE MARK LIST: 1 On-board electrical system 2 1. Subnetwork 3 2nd subnetwork 4 3rd subnetwork 5 traction batteries 6 1. Battery connection 7 2. Battery connection 8 3. Battery connection 9 battery cells 10 battery modules 11 High-voltage battery connection 12 high-voltage battery connection 13 1. DC-DC converter 14 2. DC-DC converter 15 3. DC-DC converter 16 cell arrangement 17 1. electrical pole 18 2nd electrical pole 19 3rd electrical pole 20 4th electrical pole 21 1. Module connection 22 2. Module connection 23 1. Switch 24 2. Switch QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 102 306 A1

[0002] DE 10 2022 120 021 B3

[0003] EP 3 945 657 A1

[0004]

Claims

Traction battery (5) for an on-board electrical system (1) of a motor vehicle, with a cell arrangement (16) comprising several battery cells (9) which are electrically connected to electrical battery terminals (6, 7, 8) of the traction battery (5), characterized in that a first DC voltage converter (13) is electrically connected to a first part of the battery cells (9) which provides a first electrical voltage and a second DC voltage converter (14) is electrically connected to a second part of the battery cells (9) which differs from the first part, wherein the first DC voltage converter (13) and the second DC voltage converter (14) are electrically connected in parallel to a first battery terminal (6) and / or a second battery terminal (7) of the battery terminals (6, 7, 8) of the traction battery (5). Traction battery according to claim 1, characterized in that the first DC voltage converter (13) is electrically connected to a first electrical pole (17) of the cell arrangement (16) having a first electrical potential and to a second electrical pole (18) of the cell arrangement (16) having a second electrical potential, and the second DC voltage converter (14) is electrically connected to the first electrical pole (17) or the second electrical pole (18) of the cell arrangement (16) and to a third electrical pole (19) of the cell arrangement (16) having a third electrical potential. Traction battery according to one of the preceding claims, characterized in that the first part of the battery cells (9) is electrically connected on one side to the first electrical pole (17) and on the other side to the second electrical pole (18), and the second part of the battery cells (9) is electrically connected on one side to the first electrical pole (17) and on the other side to the third electrical pole (19). Traction battery according to one of the preceding claims, characterized in that the battery cells (9) are part of battery modules (10), wherein a first part of the battery modules (10) is electrically connected on one side to the first electrical pole (17) and on the other side to the second electrical pole (18), and a second part of the battery modules (10) is electrically connected on one side to the second electrical pole (18) and on the other side to the third electrical pole (19), wherein each of the battery modules (10) has at least one of the battery cells (9) and a switch arrangement. Traction battery according to one of the preceding claims, characterized in that each of the battery modules (10) has a first module connection (20) and a second module connection (21), wherein at least one of the battery cells (9) is electrically connected to the first module connection (20) and the second module connection (21) via a first switch (22) of the switch arrangement and a second switch (23) of the switch arrangement in parallel to the at least one battery cell (9) and the first switch (22). Traction battery according to one of the preceding claims, characterized in that a third DC voltage converter (15) is electrically connected in parallel to the second DC voltage converter (14) to the second electrical pole (18) and / or the third electrical pole (19) and / or the second part of the battery cells (9), wherein the third DC voltage converter (15) is electrically connected to the first battery terminal (6) and a third battery terminal (8) of the battery terminals (6, 7, 8). On-board electrical system (1) for a motor vehicle, comprising a traction battery (5), in particular a traction battery (5) according to one or more of the preceding claims, wherein the traction battery (5) comprises a cell arrangement (16) having several battery cells (9) which are electrically connected to electrical battery terminals (6, 7, 8) of the traction battery (5), characterized in that a first DC voltage converter (13) is electrically connected to a first part of the battery cells (9) providing a first electrical voltage and a second DC voltage converter (14) is electrically connected to a second part of the battery cells (9) different from the first part, wherein the first DC voltage converter (13) and the second DC voltage converter (14) are electrically connected in parallel to a first battery terminal (6) and / or a second battery terminal (7) of the battery terminals (6, 7, 8) of the traction battery (5). On-board electrical system according to claim 7, characterized in that the traction battery (5) is electrically connected via the first DC voltage converter (13) and the second DC voltage converter (14) to a first subnetwork (2) of the on-board electrical system (1) and via a third DC voltage converter (15) to a second subnetwork (3) of the on-board electrical system (1). Method for operating an on-board electrical system (1) for a motor vehicle, in particular an on-board electrical system (1) according to one or more of the preceding claims, wherein the on-board electrical system (1) comprises a traction battery (5) with a cell arrangement (16) having several battery cells (9) which are electrically connected to electrical battery terminals (6, 7, 8) of the traction battery (5), characterized in that a first DC-DC converter (13) is electrically connected to a first part of the battery cells (9) providing a first electrical voltage and a second DC-DC converter (14) is electrically connected to a second part of the battery cells (9) different from the first part, wherein the first DC-DC converter (13) and the second DC-DC converter (14) are electrically connected in parallel to a first battery terminal (6) and / or a second battery terminal (7) of the battery terminals (6, 7, 8).8) are electrically connected to the traction battery (5) and are operated at least temporarily to provide electrical energy from the traction battery (5) at the battery terminals (6, 7, 8). The method according to claim 9, characterized in that at least one of the following steps is performed: - providing electrical energy with the second DC-DC converter (14) deactivated by means of the first DC-DC converter (13), - adjusting an electrical voltage provided by the second DC-DC converter (14) to a voltage present between the battery terminals (6, 7, 8), - providing electrical energy with the first DC-DC converter (13) deactivated by means of the second DC-DC converter (14), and - adjusting an electrical voltage provided by the first DC-DC converter (13) to the voltage present between the battery terminals (6, 7, 8).

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