ON-BOARD ENGINE AND POWER MODULE FOR SUCH A

Description

[0001] The invention relates to an on-board network and a power module for such an on-board network.

[0002] An on-board electrical system is typically used to distribute energy within a vehicle. The on-board electrical system typically has multiple supply lines connecting various consumers to one or more energy sources for the purpose of supplying electrical energy. The consumers and energy sources are connected to the on-board electrical system accordingly. Some on-board electrical systems have multiple subnetworks with different voltage levels to optimally operate consumers with different electrical requirements. The subnetworks are electrically interconnected so that energy can be exchanged between them as needed.

[0003] A power module is used to distribute energy within an on-board network.

[0004] DE 101 50 379 A1 describes a power supply system for safety-relevant consumers. These are each supplied with power via two separate supply lines.

[0005] DE 10 2014 214 103 A1 describes an on-board power system topology with two redundant loads, each in one of two safety-relevant sub-networks. One of the sub-networks is connected to a low-voltage on-board power system, the other to a high-voltage on-board power system. The two on-board power systems are connected via a DC / DC converter. The redundant loads can be supplied independently from each of the two on-board power systems.

[0006] DE 100 53 584 A1 describes a redundant power supply for safety-relevant consumers in a motor vehicle. A special distribution eliminates the need for DC / DC converters.

[0007] Further on-board networks are described in WO 2004 / 042888 A1, DE 10 2017 208 030 A1 and DE 198 46 319 C1.

[0008] Against this background, it is an object of the invention to provide an improved on-board power supply that ensures the highest possible reliability with regard to the supply of energy to a safety-relevant consumer. Furthermore, an improved power module for such an on-board power supply is to be provided.

[0009] The object is achieved according to the invention by an on-board electrical system having the features according to claim 1 and by a power module having the features according to claim 14. Advantageous embodiments, refinements, and variants are the subject of the subclaims. The statements relating to the on-board electrical system also apply mutatis mutandis to the power module, and vice versa.

[0010] The electrical system is designed for use in a vehicle. The vehicle is, in particular, a motor vehicle, e.g., a car or truck. The vehicle is, in particular, powered by an electric motor or an internal combustion engine, or both.

[0011] The on-board electrical system has a first subnetwork and a second subnetwork, to each of which at least one energy source is connected, wherein the first subnetwork has a different voltage level than the second subnetwork. Accordingly, at least one first energy source is connected to the first subnetwork and at least one second energy source is connected to the second subnetwork. The energy source of the respective subnetwork determines its voltage level. The voltage level of the respective subnetwork indicates which voltage is available in the subnetwork to supply consumers. Accordingly, the two energy storage devices have different voltages in accordance with the different voltage levels of the two subnetworks. Preferably, the first subnetwork has a lower voltage level than the second subnetwork.

[0012] The on-board electrical system has at least one safety-relevant consumer connected to one of the subnetworks, wherein this subnetwork has two subnetworks and the consumer is connected to both subnetworks, so that the consumer is connected to the subnetwork's energy source via two separate supply lines. This is in contrast to DE 101 50 379 A1 mentioned above, in which a component is not connected to the same energy source of the corresponding subnetwork via two separate connecting lines. In the following, "consumer" is understood to mean a safety-relevant consumer, unless explicitly stated otherwise. The consumer is directly connected, in particular, only to one of the subnetworks, i.e., not directly to the other subnetwork.In particular, the energy source is connected to only one of the sub-networks, but the two sub-networks are interconnected in such a way that both sub-networks are supplied from the energy source. The sub-network is therefore divided into two sub-networks, and each sub-network comprises one of the supply lines, so that the consumer can be supplied with energy via different sub-networks, i.e. is redundantly connected to the energy source. If one of the supply lines or one of the sub-networks fails, energy is still supplied via the other sub-network with the other supply line. One or more convenience consumers that may be present, on the other hand, are each preferably only connected to a single sub-network and are therefore not supplied redundantly.

[0013] A "safety-relevant load" is defined as a load that fulfills a safety-relevant function, i.e., a safety function. Such loads are assigned to a risk class, abbreviated to "ASIL" (automotive safety integrity level), based on a risk classification, particularly in accordance with ISO 26262 (more generally IEC 61508), and are therefore also referred to as ASIL loads for simplicity. A safety-relevant load serves to reliably and safely ensure the safety and, in particular, the integrity of a machine, in particular a vehicle, or one or more persons, in particular vehicle occupants or other road users, or a combination thereof. Examples of safety-relevant loads in a vehicle include a braking system, a steering system, a roll stabilization system, a drive system, a chassis control system, an airbag, a system for ensuring vehicle stability, and the like.Safety-relevant loads must be distinguished from comfort loads, which do not perform a safety-relevant function but merely provide one or more comfort functions. Such comfort loads are also assigned to the "QM" class and are therefore also labeled as QM loads. Examples of comfort loads include air conditioning, seat adjustment, an audio system, and the like. For safety-relevant loads, a redundant power supply is regularly required, e.g., from the cited standards. Such a requirement typically does not exist for comfort loads.

[0014] The on-board electrical system further comprises a power module that connects the two subnetworks to each other and is designed such that each of the two supply lines can be connected to both energy sources, so that the load can be supplied from both energy sources via both supply lines. This means that a load on one of the subnetworks can be supplied from several different energy sources, which are connected to different subnetworks, via at least two different subnetworks of this same subnetwork. The load is therefore not only redundantly connected to a single energy source in the same subnetwork, but is also connected to the energy source from the other subnetwork. In addition to the redundancy of the connection, redundancy of the energy source is also realized.The consumer can be supplied via two separate connecting lines on the one hand and via two separate energy sources on the other.

[0015] The power module serves to distribute the electrical energy from the energy sources to the various subnetworks and sub-networks, thus advantageously ensuring the described redundancy of the consumer's energy supply. The power module is designed to distribute electrical energy. The power module is preferably an electrical circuit, which in one expedient embodiment has a circuit board on which suitable components for implementing the functionality of the power module are arranged and interconnected. "Electrical energy" is understood here to mean, in particular, energy for operating a respective consumer, i.e., a certain amount of electrical power is provided so that the consumer can perform a function.This is in contrast to electrical signals or control signals, which only serve to transmit data to or from a consumer and do not transmit power and therefore do not serve to operate the consumer.

[0016] The energy source of a respective subnetwork is, in particular, only directly connected to that same subnetwork and is only indirectly connected to the other subnetwork via the power module. The same applies analogously to the consumer, which is accordingly only directly connected to one subnetwork, but only indirectly to the other subnetwork via the power module. A respective energy source is, in particular, only connected to one subnetwork of a respective subnetwork and is therefore only indirectly connected to other subnetworks, in particular via the power module. The power module thus acts as an intermediary or distributor between the two subnetworks and, in particular, also between the subnetworks. The power module also marks a boundary between the two subnetworks, separating them from one another, so to speak. The two subnetworks are preferably connected to one another exclusively via the power module.A consumer, on the other hand, is directly connected to at least two subnetworks of one of the subnetworks, thus creating a redundant connection. A convenience consumer, like the energy sources, is connected to only one subnetwork.

[0017] The explanations also apply mutatis mutandis to configurations with multiple security-relevant consumers, which are either all connected to one of the subnets or alternatively distributed across the two subnets. The explanations also apply mutatis mutandis to configurations with more than two subnets and also to configurations in which multiple subnets each have multiple subnets. However, without limiting the generality, the following initially assumes two subnets and two subnets per subnet. This configuration is also particularly preferred.

[0018] A key advantage of the invention is that each safety-relevant load is supplied via two separate supply lines, and can be supplied from at least two different energy sources via each of the two supply lines. Thus, the load's energy supply is, in a sense, doubly redundant: once via the two supply lines and further via the supply from two energy sources via each of the two supply lines.

[0019] A further advantage is that the multitude of options for supplying energy to the consumer means that the consumer is particularly well protected against a fault in one of the subnetworks or in a component connected to it, e.g. one of the energy storage devices.

[0020] Particularly preferred, especially in connection with a vehicle, is a configuration in which the consumer is connected to the one of the two subnetworks with the higher voltage level. If the first subnetwork has the lower voltage level, the consumer is then connected to the second subnetwork, i.e. to the subnetwork with the higher voltage level in comparison. This creates a configuration in which a safety-relevant consumer is operated at the higher voltage, so that this consumer is optimally protected on the one hand and, on the other hand - compared to a corresponding consumer at a lower voltage - is also advantageously supplied with higher power at lower current.

[0021] A particularly advantageous embodiment is one in which the vehicle electrical system has at least two safety-relevant consumers, each of which is connected to the two subnetworks via two supply lines in the manner described above. In other words, the vehicle electrical system has a first safety-relevant consumer connected to the first subnetwork. This first subnetwork has two subnetworks, and the first consumer is connected to both subnetworks, so that the first consumer is connected to the energy source of the first subnetwork via two separate supply lines.The on-board electrical system also has a second safety-relevant load connected to the second subnetwork. This second subnetwork also has two subnetworks, and the second load is connected to both subnetworks, so that the second load is connected to the power source of the second subnetwork via two separate supply lines. Overall, therefore, in each subnetwork, i.e., at different voltage levels, at least one load is supplied with power in a doubly redundant manner.

[0022] In a suitable embodiment, the first subnetwork has a voltage level of 12 V and the second subnetwork a voltage level of 48 V and the consumer is connected to the second subnetwork. The on-board electrical system therefore has a 12 V subnetwork and a 48 V subnetwork. The consumer is a 48 V consumer. It is important that a safety-relevant consumer is operated at the higher of the two voltage levels and at the same time is optimally redundantly protected, as already described in more general terms above. The values ​​12 V and 48 V refer in particular to the nominal voltage and not to the actual voltage, which is typically slightly above or below the nominal voltage, e.g. up to 10% higher or lower.

[0023] The respective energy source is preferably an electrical storage device, in particular a battery or a supercapacitor. A generator, i.e., an electric motor operated as a generator, is also advantageous as an energy source. In a preferred embodiment, a first electrical storage device is connected to the first subnetwork as the first energy source. A second electrical storage device is connected to the second subnetwork as the second energy source, and a generator, e.g., a vehicle alternator, is connected as an additional energy source. In this embodiment, the on-board electrical system has three energy sources in total.

[0024] Preferably, the generator and the electrical storage system are connected to different subgrids of the second subgrid. This is not mandatory in itself, but has the advantage that the two energy sources of the second subgrid are distributed across different subgrids, and in the event of a fault in one of the subgrids, potentially only one energy source fails, while the other energy source remains usable. The concepts with two energy sources and with energy sources distributed across different subgrids are also fundamentally advantageous for the first subgrid and can be applied there as well.

[0025] The two subnetworks are generally DC voltage networks. The power module connects the two subnetworks and thus also different voltage levels, which are converted accordingly by the power module. Preferably, the power module has at least one DC-DC converter, via which the two subnetworks are connected to one another, for supplying one subnetwork with energy from the other subnetwork and vice versa. The DC-DC converter therefore serves to convert the voltage levels. In the embodiment with a 48 V subnetwork and a 12 V subnetwork, the DC-DC converter is therefore a 48 V / 12 V converter. The DC-DC converter also represents a boundary between the first and second subnetworks.

[0026] In this case, both subnetworks each have two subnetworks, and the power module has two, in particular, similar DC-DC converters. A first of the two DC-DC converters connects a first subnetwork of the first subnetwork with a first subnetwork of the second subnetwork. A second of the two DC-DC converters then analogously connects a second subnetwork of the first subnetwork with a second subnetwork of the second subnetwork. Thus, two subnetworks from different subnetworks are each connected via a DC-DC converter. In this respect, the power module is advantageously designed to be redundant with regard to the DC-DC converters. Since the subnetworks of a subnetwork are also interconnected, even in the event of a fault in one of the DC-DC converters, each subnetwork and each consumer connected to it can continue to be supplied from any other subnetwork to which a power source is connected.The two DC-DC converters also represent a boundary between the first and second subnetwork.

[0027] The DC-DC converters also serve as switches to electrically isolate the subnetworks connected to them in the event of a fault.

[0028] In an advantageous embodiment, the two subnetworks each have two subnetworks and the two subnetworks of the first subnetwork are separably connected to one another via a first switch. Analogously, the two subnetworks of the second subnetwork are also separably connected to one another via a second switch. The switches are used in particular to separate a respective subnetwork in the event of a fault, i.e. if a fault occurs in one of the subnetworks, this subnetwork is separated from the other subnetworks by opening the corresponding switch. Otherwise, i.e. during normal operation and without a fault, the switches are closed in order to connect the subnetworks accordingly and to ensure advantageous redundancy. The switches are each designed, for example, as semiconductor switches or alternatively as relays or contactors.

[0029] Preferably, the two switches are integrated into the power module, meaning the switches are each components of the power module. The switches and the DC-DC converters are then advantageously combined in the power module, so that the entire connection of the sub-networks is particularly compact and spatially concentrated, meaning that it can be accommodated, and preferably is, in a single location in the vehicle. The components of the power module are therefore not distributed throughout the vehicle.

[0030] A combination of the design with two switches and the design with two DC-DC converters is particularly preferred. This results in a power module with a particularly high degree of integration. The switches connect the subnetworks within a respective subnetwork, while the DC-DC converters connect the subnetworks to one another. By switching the switches and the DC-DC converters accordingly, the subnetworks can then be connected to one another in almost any way, for maximum redundancy, and separated from one another with particular flexibility in the event of a fault. In the case of two subnetworks, each with two subnetworks, the first switch connects the subnetworks of the first subnetwork, the second switch connects the subnetworks of the second subnetwork, the first DC-DC converter connects the first two subnetworks of the two subnetworks, and the second DC-DC converter connects the second two subnetworks of the two subnetworks.

[0031] Overall, this results in a particularly compact design, since the entire connection of the subnetworks and subnetworks with one another, and thus also the redundant supply of the load, is implemented by the power module. The doubly redundant supply of a safety-relevant load is preferably implemented entirely by the power module; all functions used here are expediently integrated into the power module. One function, in particular, is adjusting the voltage as needed in order to supply the load in one subnetwork with energy from the other subnetwork. For this purpose, the power module has one or more DC-DC converters, as described. Another function, in particular, is to connect the subnetworks and in particular their subnetworks with one another or to separate them from one another as required. For this purpose, the power module has one or more switches, as described.The power module itself is particularly compact and can be installed in the vehicle, for example, instead of a 12 V battery in the engine compartment or in a spare wheel well in the trunk. The power module features a particularly high degree of integration.

[0032] The power module preferably has a separate connection for each sub-network, so that the sub-networks of a sub-network are only connected to one another via the power module and at the loads. The connections are each designed as a pole to which the loads, convenience loads, and energy sources of the respective sub-network are connected outside the power module. The connections for each sub-network are connected in particular via a switch as described above. A DC-DC converter as described above is arranged between the connections of different sub-networks. For two sub-networks, each with two sub-networks, the power module has a total of four connections. Outside the power module, the two sub-networks are preferably not connected to one another. In an advantageous embodiment, the sub-networks are also not connected to one another outside the power module.

[0033] There are basically two different variants for the arrangement of each energy source, both of which are advantageous and preferred. In a first variant, the energy source is arranged outside the power module and designed separately therefrom, which results in corresponding flexibility. In a second variant, however, the energy source is integrated into the power module, which results in a particularly compact design. In a particularly preferred embodiment, at least one energy source in each of the first and second subnetworks is designed as an electrical storage device, i.e. for example as a battery or supercapacitor, and is integrated into the power module. The power module therefore already provides an energy source in the form of an electrical storage device for each of the two subnetworks, so that such a device does not have to be connected externally. This achieves a particularly high degree of integration.However, it is advisable to connect an external generator - as described above - to charge the two electrical storage units.

[0034] In a suitable embodiment, the on-board electrical system has at least one convenience consumer that is not safety-relevant and is connected to one of the energy sources via a single supply line. The convenience consumer is therefore not redundantly connected, but rather only to one of the subnetworks of just one of the subnetworks.

[0035] The problem is further solved by a vehicle having an on-board power supply or a power module as described above. The problem is also solved by using a power module as described above in an on-board power supply, as well as by using a power module or an on-board power supply as described above in a vehicle.

[0036] The problem is solved, in particular, by a method for operating a power module or an on-board electrical system. To separate the two subnetworks of a subnetwork, e.g., in the event of a fault in one of the subnetworks, a switch that electrically connects the two subnetworks during normal operation is opened, so that the two subnetworks are then electrically separated from one another. The above statements regarding the on-board electrical system and the power module also apply mutatis mutandis to the method. In particular, advantageous method steps arise mutatis mutandis from the previous statements regarding the behavior of the on-board electrical system and the power module.

[0037] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, the following schematically show: Fig. 1 a vehicle with an on-board network, Fig. 2 a first variant of the on-board network Fig. 1 , Fig. 3 a second variant of the electrical system Fig. 1 .

[0038] In Fig. 1 A vehicle 2 is shown, which has an on-board network 4, which is only indicated very schematically by connecting lines between several components of the vehicle 2. The vehicle 2 is a motor vehicle, e.g. a car or truck, and is powered, for example, by an electric motor or an internal combustion engine, or both. Fig. 2 an embodiment of a first variant of the on-board network 4 is shown in more detail, in Fig. 3 An embodiment of a second variant is shown in more detail.

[0039] The on-board electrical system 4 generally has a first subnetwork 6 and a second subnetwork 8, to each of which at least one energy source 10, 12, 14 is connected. The first subnetwork 6 has a different, in this case a lower, voltage level than the second subnetwork 8. At least one first energy source 10 is connected to the first subnetwork 6, and at least one second energy source 12 is connected to the second subnetwork 8. The energy source 10, 12, 14 of the respective subnetwork 6, 8 determines its voltage level. In the exemplary embodiments shown, the voltage level of the first subnetwork 6 is 12 V and the voltage level of the second subnetwork 8 is 48 V; however, other voltages are also possible and suitable in principle.

[0040] The on-board electrical system 4 has at least one, and here, by way of example, four safety-relevant consumers 16, each of which is connected to one of the subnetworks 6, 8. Each subnetwork 6, 8 has two subnetworks 18, 20, 22, 24, and a respective consumer 16 is connected to both subnetworks 18, 20, 22, 24 of a single subnetwork 6, 8, so that the consumer 16 is connected to the energy source 10, 12, 14 of the corresponding subnetwork 6, 8 via two separate supply lines V1, V2. This is shown in the Fig. 2 and 3shown as an example for one of the consumers 16, however, as is clear, all four consumers 16 are each connected separately via two connecting lines V1, V2. The respective energy source 10, 12, 14 is connected to only one of the subnetworks 18, 20, 22, 24; however, the two subnetworks 18, 20, 22, 24 of a respective subnetwork 6, 8 are interconnected in such a way that both subnetworks 18, 20, 20, 24 are supplied by the associated energy source 10, 12, 14. Thus, each of the two subnetworks 6, 8 is divided into two subnetworks 18, 20, 22, 24, each of which comprises one of the supply lines V1, V2, so that the consumer 16 can be supplied with energy via different subnetworks 18, 20, 22, 24, ie is redundantly connected to the energy source 10, 12, 14.In contrast, one or more comfort consumers 26 that may be present are each only connected to a single sub-network 18, 20, 22, 24 and are therefore not supplied redundantly.

[0041] The safety-relevant consumers 16 each fulfill a safety-relevant function and serve to reliably and safely ensure the safety and integrity of the vehicle 2 or one or more occupants of a vehicle 2 or other road users. Safety-relevant consumers of a vehicle are, for example, as in Fig. 1 shown a braking system or a steering system or, in a variant not shown, alternatively or additionally a roll stabilization system, a drive system, a chassis control system, an airbag, a system for ensuring vehicle stability and the like. Safety-relevant consumers 16 are to be distinguished from comfort consumers 26, which do not fulfill a safety-relevant function, but merely one or more comfort functions. Examples of comfort consumers 26 are a seat adjustment as in Fig. 1 recognizable or alternatively or additionally an air conditioning system, an audio system or the like.

[0042] The on-board electrical system 4 further comprises a power module 28, which connects the two subnetworks 6, 8 to one another and which is designed such that each of the two supply lines V1, V2 can be connected to all energy sources 10, 12, 14, so that the load 16 can be supplied via both supply lines V1, V2 from all energy sources 10, 12, 14. The load 16 is therefore not only redundantly connected to a single energy source 10, 12, 14 in the same subnetwork 6, 8, but is also connected to one or more energy sources 10, 12, 14 from the other subnetwork 6, 8. In addition to the redundancy of the connection, redundancy of the energy supply is therefore also realized.

[0043] The power module 28 serves overall to distribute the electrical energy of the energy sources 10, 12, 14 to the various subnetworks 6, 8 and subnetworks 18, 20, 22, 24 and thus ensures the described redundancy of the energy supply to the consumer 16. In the exemplary embodiments shown, the power module 28 is an electrical circuit which here has a circuit board 30 on which suitable components for implementing the functionality of the power module 28 are arranged and interconnected.

[0044] A respective energy source 10, 12, 14 is directly connected only to one of the subnetworks 6, 8 and is only indirectly connected to the other subnetwork 6, 8 via the power module 28. The same applies analogously to the consumers 16 and also to the comfort consumers 26, which are each connected directly to only one subnetwork 6, 8, but only indirectly to the other subnetwork 6, 8 via the power module 28. A respective energy source 10, 12, 14 is also only connected to one of the subnetworks 18, 20, 22, 24 and is therefore only indirectly connected to the remaining subnetworks 18, 20, 22, 24, namely via the power module 28. A respective consumer 16, in contrast, is directly connected to at least two subnetworks 18, 20, 22, 24 of one of the subnetworks 6, 8, so that a redundant connection is realized. A respective comfort consumer 26, in contrast, is only connected to one subnetwork 18, 20, 22, 24.

[0045] As already described, the first subnet 6 in the Fig. 2 and 3 a voltage level of 12 V, and the second subnetwork 8 a higher voltage level of 48 V. A special feature is that at least one safety-relevant consumer 16 is connected to the second subnetwork 8 and operates at the higher voltage, thereby receiving a redundant power supply. This is fundamentally independent of which and how many consumers 16 and convenience consumers 26 are connected to the first subnetwork 6 at 12 V and how the energy sources 10, 12, 14 are distributed.

[0046] The energy sources 10, 12 are each designed as electrical storage devices, in this case even as batteries. Alternatively, a design as a supercapacitor is also suitable. A generator is also suitable as an energy source 14. In the exemplary embodiments shown, a first electrical storage device is connected to the first subnetwork 6 as the first energy source 10, and a second electrical storage device is connected to the second subnetwork 8 as the second energy source 12, as well as a generator as an additional energy source 14, so that the on-board electrical systems 4 shown each have three energy sources 10, 12, 14. Alternatives with a different number and distribution of energy sources 10, 12, 14 are fundamentally possible and also suitable, provided that at least one energy source 10, 12, 14 is connected to each of the subnetworks 6, 8, so that at least one energy source 10, 12, 14 is present per subnetwork 6, 8.

[0047] In the examples of the Fig. 2 and 3The generator 14 and the second electrical storage unit 12 are connected to different sub-grids 22, 24 of the second sub-grid 8. This is not mandatory in itself, but has the advantage that the two energy sources 12, 14 of the second sub-grid 8 are distributed across different sub-grids 22, 24, and in the event of a fault in one of the sub-grids 22, 24, potentially only one energy source 12, 14 fails, while the other remains usable. This concept is also applicable analogously to the first sub-grid 6.

[0048] The power module 28 connects the two subnetworks 6, 8 and thus also the different voltage levels. To supply one subnetwork 6, 8 with energy from the other subnetwork 6, 8 and vice versa, the power module 28 has at least one, and here two, DC-DC converters 32, 34, via which the two subnetworks 6, 8 are connected to each other. The DC-DC converters 32, 34 serve to convert the voltage levels and are specifically designed here as 48 V / 12 V converters. The DC-DC converters 32, 34 also represent a boundary between the two subnetworks 6, 8.

[0049] In the case of the designs according to the Fig. 2 and 3The first subnetwork 6 has a first subnetwork 18 and a second subnetwork 20, and the second subnetwork 8 also has a first subnetwork 22 and a second subnetwork 24. The first DC-DC converter 32 connects the first subnetwork 18 of the first subnetwork 6 to the first subnetwork 22 of the second subnetwork 8. The second DC-DC converter 34 similarly connects the second subnetwork 20 of the first subnetwork 6 to the second subnetwork 24 of the second subnetwork 8. Thus, the first subnetworks 18, 22 and the second subnetworks 20, 24 are connected via a respective DC-DC converter 32, 34. Since the sub-networks 18, 20, 22, 24 of a sub-network 6, 8 are also interconnected, even in the event of a fault in one of the DC-DC converters 32, 34, each sub-network 18, 20, 22, 24 and each consumer 16 connected to it can continue to be supplied from any other sub-network 18, 20, 22, 24 to which an energy source 10, 12, 14 is connected.

[0050] The two sub-networks 18, 20 of the first sub-network 6 are separably connected to one another via a first switch 36. Similarly, the two sub-networks 22, 24 of the second sub-network 8 are separably connected to one another via a second switch 38. The switches 36, 38 serve to disconnect a respective sub-network 18, 20, 22, 24 in the event of a fault by opening the corresponding switch 36, 38. Otherwise, i.e. during normal operation and without a fault, the switches 36, 38 are closed. In the exemplary embodiments shown, the two switches 36, 38 are integrated into the power module 28, namely on the circuit board 30. In a variant not shown, the DC-DC converters 32, 34 are also mounted on the circuit board 30.

[0051] As can be seen from the Fig. 2 and 3As is clear, the switches 36, 38 connect a respective first subnetwork 18, 22 with the corresponding second subnetwork 20, 24 within the same subnetwork 6, 8, while the DC-DC converters 32, 34 connect the different subnetworks 6, 8. By switching the switches 36, 38 and the DC-DC converters 32, 34 accordingly, the subnetworks 18, 20, 22, 24 can be connected and disconnected in almost any way.

[0052] In this case, the power module 28 has a separate connection 40 for each sub-network 18, 20, 22, 24, i.e., four connections 40 in this case. As a result, the sub-networks 18, 20, 22, 24 of a sub-network 6, 8 are connected to one another only via the power module 28 and at the loads 16. The connections 40 are each designed as a pole to which the loads 16, convenience loads 26, and energy sources 10, 12, 14 of the respective sub-network 18, 20, 22, 24 are connected outside the power module 28. The connections 40 of a respective sub-network 6, 8 are connected via one of the switches 36, 38. However, one of the DC-DC converters 32, 34 is arranged between two connections 40 of different sub-networks 6, 8.

[0053] A respective energy source 10, 12, 14 is arranged either outside the power module 28 and separately therefrom, as in Fig. 2 shown, or alternatively integrated into the power module 28, as shown in Fig. 3 shown. Especially in Fig. 3 the energy sources 10, 12 designed as electrical storage devices are integrated into the power module 28, while the generator 14 is as in Fig. 2 outside the power module 28. The power module 28 of the Fig. 3 thus has an energy source 10, 12 in the form of an electrical storage device for each of the two subnetworks 6, 8, so that such a device does not have to be connected externally. List of reference symbols

[0054] 2Vehicle 4On-board electrical system 6First subnetwork (12 V) 8Second subnetwork (48 V) 10First energy source, first electrical storage device 12Second energy source, second electrical storage device 14Energy source, generator 16Safety-relevant consumer 18First subnetwork (in the first subnetwork) 20Second subnetwork (in the first subnetwork) 22First subnetwork (in the second subnetwork) 24Second subnetwork (in the second subnetwork) 26Comfort consumer 28Power module 30Board 32First DC-DC converter 34Second DC-DC converter 36First switch 38Second switch 40Connection V1, V2 connecting line

Claims

1. Vehicle electrical system (4) - which is designed for use in a vehicle (2), - which has a first subnetwork (6) and a second subnetwork (8), to each of which at least one energy source (10, 12, 14) is connected, wherein the first subnetwork (6) has a different voltage level than the second subnetwork (8), - which has at least one safety-relevant consumer (16) connected to one of the subnetworks (6, 8), wherein this subnetwork (6, 8) has two partial networks (18, 20, 22, 24) and the consumer (16) is connected to both partial networks (18, 20, 22, 24), such that the consumer (16) is connected to the energy source (10, 12, 14) of the subnetwork (6, 8) via two separate supply lines (V1, V2), - which has a power module (28) which connects the two subnetworks (6, 8) to each other and is designed in such a way that each of the two supply lines (V1, V2) can be connected to both energy sources (10, 12, 14), such that the consumer (16) can be respectively supplied from both energy sources (10, 12, 14) via both supply lines (V1, V2), characterized - in that both subnetworks (6, 8) each have two partial networks (18, 20, 22, 24), wherein the power module (28) has two DC-DC converters (32, 34) which represent a boundary between the first and the second subnetwork (6, 8), - in that a first of the two DC-DC converters (32) connects a first partial network (18) of the first subnetwork (6) to a first partial network (22) of the second subnetwork (8), - in that a second of the two DC-DC converters (34) connects a second partial network (20) of the first subnetwork (6) to a second partial network (24) of the second subnetwork (8), such that two partial networks (18, 20, 22, 24) each from different subnetworks (6, 8) are connected via a DC-DC converter (32, 34).

2. Vehicle electrical system (4) according to Claim 1, wherein the energy source (10, 12, 14) of a respective subnetwork (6, 8) is directly connected only to that same subnetwork (6, 8) and is connected to the other subnetwork (6, 8) only indirectly via the power module (28), wherein the consumer (16) is directly connected only to one subnetwork (6, 8) and is connected to the other subnetwork (6, 8) only indirectly via the power module (28).

3. Vehicle electrical system (4) according to either of Claims 1 and 2, wherein the first subnetwork (6) has a lower voltage level than the second subnetwork (8).

4. Vehicle electrical system (4) according to one of Claims 1 to 3, wherein the consumer (16) is connected to that one of the two subnetworks (6, 8) which has the higher voltage level.

5. Vehicle electrical system (4) according to one of Claims 1 to 4, wherein the first subnetwork (6) has a voltage level of 12 V and the second subnetwork (8) has a voltage level of 48 V, and wherein the consumer (16) is connected to the second subnetwork (8).

6. Vehicle electrical system (4) according to one of Claims 1 to 5, wherein a first electrical storage device is connected to the first subnetwork (6) as a first energy source (10), and wherein a second electrical storage device is connected to the second subnetwork (8) as a second energy source (12) and a generator is connected as an additional energy source (14).

7. Vehicle electrical system (4) according to Claim 6, wherein the generator (14) and the second electrical storage device (12) are connected to different partial networks (22, 24) of the second subnetwork (8).

8. Vehicle electrical system (4) according to one of Claims 1 to 7, wherein the power module (28) has at least one DC-DC converter (32, 34), via which the two subnetworks (6, 8) are connected to each other, for the purpose of supplying one subnetwork (6, 8) with energy from the other subnetwork (6, 8) and vice versa.

9. Vehicle electrical system (4) according to one of Claims 1 to 8, wherein the two subnetworks (6, 8) each have two partial networks (18, 20, 22, 24), wherein the two partial networks (18, 20) of the first subnetwork (6) are separably connected to each other via a first switch (36), and wherein the two partial networks (22, 24) of the second subnetwork (8) are separably connected to each other via a second switch (38).

10. Vehicle electrical system (4) according to Claim 9, wherein the two switches (36, 38) are integrated in the power module (28).

11. Vehicle electrical system (4) according to one of Claims 1 to 10, wherein the power module (28) has a separate connection (40) for each partial network (18, 20, 22, 24).

12. Vehicle electrical system (4) according to one of Claims 1 to 11, wherein at least one energy source (10, 12, 14) of each of the first subnetwork (6) and the second subnetwork (8) is in the form of an electrical storage device and is integrated in the power module (28).

13. Vehicle electrical system (4) according to one of Claims 1 to 12, wherein this has at least one comfort consumer (26) which is not safety-relevant and which is connected to one of the energy sources (10, 12, 14) via only one supply line.