Electrical system for a vehicle and methods for operating an electrical system

Abstract

Electrical system (1) for a vehicle with - a first partial on-board network (6), - a DC voltage converter (5) which is electrically coupled with its output to the first sub-system (6), designed for the electrical supply of electrical consumers (7.1 to 7.n) intended for comfort functions, - an electrical energy storage device (8) connected or switchable in parallel to the first partial vehicle electrical system (6), - a first electrical switch (9) arranged between the first sub-system (6) and the energy storage device (8), which in a first switching state electrically connects the first sub-system (6) and the energy storage device (8) and in a second switching state electrically disconnects the first sub-system (6) and the energy storage device (8), - a second sub-system (10) that is electrically connected or switchable in parallel to the first sub-system (6) and the electrical energy storage device (8), - a second electrical switch (11) arranged between the energy storage device (8) and the second sub-system (10), which in a first switching state electrically connects the energy storage device (8) and the second sub-system (10) and in a second switching state electrically disconnects the energy storage device (8) and the second sub-system (10) from each other, - a third sub-system (12) which is electrically connected or switchable in parallel to the first sub-system (6), the second sub-system (10) and the electrical energy storage device (8), wherein the second sub-system (10) and the third sub-system (12) are designed to provide a redundant electrical supply for electrical consumers (15.1 to 15.m) that are safety-relevant for the operation of the vehicle, - a further DC voltage converter (14), which is electrically coupled to the third sub-system (12) via its output, and - a third electrical switch (13) arranged between the second sub-system (10) and the third sub-system (12), which in a first switching state electrically connects the second sub-system (10) and the third sub-system (12) and in a second switching state electrically disconnects the second sub-system (10) and the third sub-system (12).

Description

[0001] The invention relates to an electrical on-board network for a vehicle.

[0002] The invention further relates to a method for operating such an electrical on-board network.

[0003] From DE 10 2016 200 097 A1, an electrical system for a motor vehicle is known. The electrical system comprises a base network, to which a channel with two subnetworks is connected. Each subnetwork contains electrical loads that are to be operated within a predefined range of values ​​for an electrical quantity and are connected to the base network via a DC-DC converter. The predefined range of values ​​for the electrical quantity is set for each subnetwork via the DC-DC converter. The loads are assigned to the subnetworks based on their electrical supply requirements, with redundant loads being assigned to different subnetworks. Safety-relevant loads are optionally assigned to different subnetworks.

[0004] Further conventional vehicle electrical systems for supplying electrical consumers in a vehicle are known from EP 3 530 513 A1 and DE 10 2021 118 869 A1.

[0005] The invention is based on the objective of providing a novel electrical system for a vehicle and a novel method for operating such an electrical system.

[0006] The problem is solved according to the invention by an electrical on-board network which has the features specified in claim 1, and by a method which has the features specified in claim 8.

[0007] Possible embodiments of the invention are the subject of the dependent claims.

[0008] The electrical on-board network according to the invention for a vehicle has: - a first partial electrical system, - a DC / DC converter, whose output is electrically coupled to the first sub-system, - an electrical energy storage device connected or switchable in parallel to the first part of the vehicle electrical system, - a first electrical switch arranged between the first sub-system and the energy storage device, which in a first switching state electrically connects the first sub-system and the energy storage device and in a second switching state electrically disconnects the first sub-system and the energy storage device from each other, - a second sub-system that is electrically connected or switchable in parallel to the first sub-system and the electrical energy storage device, - a second electrical switch arranged between the energy storage device and the second sub-system, which in a first switching state electrically connects the energy storage device and the second sub-system and in a second switching state electrically disconnects the energy storage device and the second sub-system, - a third sub-system that is electrically connected or switchable in parallel to the first sub-system, the second sub-system and the electrical energy storage device, - another DC / DC converter, whose output is electrically coupled to the third sub-system, and - a third electrical switch arranged between the second and third sub-system, which in a first switching state electrically connects the second and third sub-system and in a second switching state electrically separates the second and third sub-system.

[0009] The present electrical system, thanks to its switches and energy storage, enables the three sub-systems to be reliably supplied with electrical power using only two DC-DC converters and a single electrical energy storage device, eliminating the need for numerous semiconductor switches in a power distribution unit. This results in significant savings in cost, weight, and installation space. Simultaneously, it ensures that all sub-systems are sufficiently independent of each other, as required by ISO 26262-9:2018, so that an electrical fault in one sub-system does not affect the others. This fulfills redundancy requirements for electrical systems, for example, up to Automotive Safety Integrity Level D (ASIL D). The DC-DC converters also allow for the electrical supply of static loads within the sub-systems.The energy storage system makes it possible to supply dynamic electrical loads to the sub-networks. This allows for buffering of dynamic processes by the energy storage system, thus enabling the DC-DC converter coupled to the first sub-network to be designed for a lower peak power output.Since such dynamic buffering during vehicle operation is primarily required only for safety-relevant electrical consumers, such as the steering or brakes, which are redundantly supplied in the second and third sub-networks, and since the first sub-network contains electrically powered consumers with low dynamic loads intended for comfort functions, the energy storage system can be used to buffer the dynamic electrical consumers of the second sub-network by opening the first switch and the third switch. The dynamic consumers of the third sub-network, on the other hand, can be supplied via a dynamic buffer in the additional DC-DC converter. This allows for a particularly small energy storage system, resulting in savings in cost, weight, and installation space.

[0010] The energy storage device can be electrically coupled to all sub-networks or at least one of the sub-networks by means of the switches, with the energy storage device covering certain tasks in the individual sub-networks.

[0011] In the first sub-wiring system, the DC-DC converter is primarily intended for supplying power to all static loads. The energy storage device is intended for supplying power during operating states in which the DC-DC converter is deactivated, for example, to power vehicle functions when the vehicle is parked, such as an anti-theft alarm system. Furthermore, the energy storage device is intended to supply the electrical consumers of the first sub-wiring system during minor dynamic processes while the vehicle is in motion. The first sub-wiring system may contain several conventional power distribution units with fuses and / or power distribution units with semiconductor switches for connecting the electrical consumers to the first sub-wiring system.

[0012] In the second sub-network, the energy storage device is primarily intended to supply all static and dynamic electrical loads, with the second switch being closed during vehicle operation. For example, the second sub-network includes several power distribution units with semiconductor fuses for connecting electrical loads, such as safety-critical components. Depending on the safety concept, fuse links can also be used. Furthermore, it is envisaged that, during normal vehicle operation, the energy storage device is charged via the closed first switch and / or the closed second switch.

[0013] In the third sub-network, the additional DC-DC converter, for example through direct coupling with a high-voltage electrical energy storage system, offers high availability for supplying all static and dynamic loads in the third sub-network. For example, several power distribution units with semiconductor fuses are provided for connecting electrical loads, such as safety-critical loads, to the third sub-network. Depending on the safety concept, fuse links can also be used for this purpose.

[0014] According to one possible configuration of the electrical system, the first sub-system is designed to supply electrical loads intended for comfort functions. This configuration achieves a separation between the electrical loads in the second and third sub-systems, such as safety-related electrical loads, and those intended for comfort functions. This, in turn, means that the DC-DC converter connected to the first sub-system and the electrical loads in the first sub-system do not need to meet stringent safety or availability requirements, resulting in cost and complexity reductions.This eliminates the need for complex safety mechanisms that, according to VDA 450, must be implemented in a mixed electrical system channel, i.e., a sub-system containing both comfort functions and safety-related electrical consumers. Furthermore, the potential separation of the electrical supply for safety and comfort functions reduces the load on the energy storage system, as this separation results in a significantly lower so-called worst-case load according to VDA 450. Additionally, this separation ensures that there is no feedback from the first sub-system to the second and third sub-systems.

[0015] According to another possible configuration of the electrical system, the second and third sub-systems are designed to provide a redundant electrical supply for safety-relevant electrical consumers. This ensures a reliable power supply for electrical consumers with redundancy requirements, thus meeting high ASIL standards. Homogeneous redundancy, such as providing an energy storage device for each sub-system, can be avoided because the parallel-connected energy storage device, which can be coupled via switches, serves as a backup power source, as does the additional DC-DC converter directly connected to the third sub-system. This prevents dependent faults, particularly common-cause and cascading faults.

[0016] In the aforementioned configuration of the first sub-network for the electrical supply of electrical consumers intended for comfort functions, and in the aforementioned configuration of the second and third sub-networks for the redundant electrical supply of electrical consumers relevant to the operation of the vehicle, it is possible, among other things, for the second and third sub-networks to be electrically separated from each other by means of the third switch. Furthermore, a bidirectional electrical current flow between the sub-networks can be realized through appropriate control. This enables the sub-networks to be electrically isolated from each other within a very short fault tolerance time in the event of electrical faults or undervoltage events in at least one of the sub-networks, using the first switch and / or the third switch, depending on a safety concept for maintaining functional safety.Thus, independence between the sub-networks can be ensured by a non-conductive state of the switches at certain undervoltage, overvoltage, and / or overcurrent thresholds. It is also possible to direct the returned electrical energy to the electrical energy storage system by closing the switches in a regenerative braking mode, in which an electrical load located in the second and / or third sub-network feeds electrical energy back into the respective sub-network in generator mode. This effectively and cost-efficiently prevents overvoltages and thus the failure of one or more sub-networks. Regenerative braking via one of the DC-DC converters into a high-voltage electrical system can therefore be eliminated or at least reduced in size.

[0017] According to another possible configuration of the electrical system, the second and / or third sub-system are additionally designed to supply electrical components essential for the vehicle's safety operation. These components are assigned exclusively to either the second or third sub-system and are not connected to a redundant electrical supply. This ensures that even components requiring no redundant power supply can be reliably supplied via the second or third sub-system.

[0018] According to another possible configuration of the electrical system, it features a high-voltage electrical system that is coupled, or can be coupled, to at least one high-voltage energy storage device. This high-voltage system enables the supply of high-voltage power to the vehicle's electrical consumers. Furthermore, the coupling with the high-voltage system allows functions to draw their necessary energy from the high-voltage system when the vehicle is parked by simply closing the switches. This eliminates the need for the energy storage device to handle these functions, allowing it to be significantly smaller. This results in savings in cost, weight, and installation space for the energy storage device.

[0019] According to another possible configuration of the electrical system, the additional DC-DC converter connected to the third sub-system is coupled with its input to the high-voltage energy storage system. Such a direct connection of the third sub-system to the high-voltage energy storage system, and a connection of the second sub-system to the high-voltage energy storage system via the switch, increases the availability of power to the electrical consumers in both sub-systems. Furthermore, due to this direct connection, it is not necessary to shut down the second and third sub-systems after a vehicle crash, especially if the high-voltage energy storage system is disconnected from the high-voltage system by a switching element.For example, by appropriately controlling the switches when the vehicle is parked, it is possible to reduce the energy demands on the energy storage system. This is because, during the parked state, potentially high energy demands on the storage system—for example, to ensure 60 minutes of hazard warning lights after a crash—can be met by the secondary DC-DC converter if it is directly coupled to the high-voltage energy storage system. With such a direct coupling of the secondary DC-DC converter to the high-voltage energy storage system, there is no need to shut down the secondary DC-DC converter during or after a crash. Furthermore, pre-charging the secondary DC-DC converter is simplified by allowing energy to be fed from the energy storage system to the secondary DC-DC converter via the closed second and third switches.Additionally, energy efficiency can be increased when the vehicle is parked, as the second DC-DC converter can be used for certain processes instead of the first. The direct connection of the second DC-DC converter to the high-voltage energy storage system eliminates the need to power the entire high-voltage electrical system. Furthermore, while the vehicle is in operation, the power buffer of the second DC-DC converter can be efficiently used for dynamic processes in the first sub-system by appropriately controlling the switches, thus creating a balancing function. This allows the vehicle user to activate more comfort functions in the first sub-system. Simultaneously, the power consumption of the DC-DC converter connected to the first sub-system can be reduced, resulting in savings in cost, weight, and installation space.

[0020] According to another possible configuration of the electrical system, the DC-DC converter connected to the first sub-system is coupled to the high-voltage system via its input. In particular, the DC-DC converter connected to the third sub-system is also coupled to the high-voltage system, at least indirectly, via the high-voltage energy storage system. This enables the DC-DC converters to be powered. The first, second, and third sub-systems are each specifically designed as low-voltage systems.

[0021] According to another possible configuration of the electrical system, it includes a monitoring device for monitoring electrical parameters in the sub-systems. This allows for the detection of electrical faults, overvoltage events, undervoltage events, and dynamic parameters affecting the sub-systems.

[0022] According to another possible configuration of the electrical system, it features a control unit that is linked to the monitoring device via data transmission. This control unit is designed to control the switches based on the electrical parameters of the sub-systems. For example, the control unit is configured to receive crash signals and fault signals, such as signals relating to electrical faults in the electrical system, detected by the monitoring device (e.g., vehicle-integrated sensors). When such signals are present, the control unit activates the switches in such a way that the sub-systems can be electrically isolated from one another and / or can continue to be reliably supplied with electrical energy even in the event of faults.In order to achieve safe and reliable automated operation of the switches by means of the control unit, in another possible design of the electrical on-board network the switches are designed as mechanical switches or semiconductor switches.

[0023] In the inventive method for operating the aforementioned electrical on-board network, it is provided that in regenerative operation, in which an electrical load arranged in the second and / or third sub-network feeds electrical energy back into the respective sub-network in generator mode, the switches are closed or are closed so that the regenerated electrical energy is fed into the electrical energy storage device. This effectively and cost-efficiently prevents overvoltages and thus the failure of one or more sub-networks. Regeneration via one of the DC-DC converters into a high-voltage electrical system can therefore be eliminated or at least reduced in size.

[0024] Furthermore, the inventive method for operating the aforementioned electrical on-board network provides that - in the event of an electrical overload in the first sub-system, with the first switch and the second switch closed, the third switch is closed and the sub-systems are electrically supplied via both DC-DC converters, - in the event of high dynamics of electrical parameters in all sub-systems and a risk of the voltage falling below a predetermined limit value in the second sub-system, the third switch and / or the first switch may be opened while the second switch is closed, - if an electrical fault occurs in the first sub-system while all switches in the first sub-system are closed, and is detected by a voltage threshold being undershot or exceeded, the first switch is opened, - in the event of an electrical fault occurring in the second sub-system while all switches are closed, and detected by a voltage threshold being undershot or exceeded, the third switch is opened and, if necessary, the second switch is opened and - if an electrical fault occurs in the third sub-network when all switches are closed and is detected by a voltage threshold being undershot or exceeded, the third switch is opened.

[0025] Thus, it is possible to reliably supply the three sub-networks with electrical power using only two DC-DC converters and the single electrical energy storage device, without requiring a large number of semiconductor switches in a power distribution system. This ensures that all sub-networks are independent of each other according to ISO 26262-9:2018, meaning that an electrical fault in one sub-network does not affect the others. Redundancy requirements for electrical systems, for example up to Automotive Safety Integrity Level D (ASIL D), are met.

[0026] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing.

[0027] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0028] This shows: Fig. 1. Schematic representation of an electrical equivalent circuit of a vehicle's electrical system during normal operation. Fig. 2. Schematic representation of an electrical equivalent circuit of the vehicle electrical system according to Fig. 1 during a feed-back from an electrical consumer, Fig. 3. Schematic representation of an electrical equivalent circuit of the vehicle electrical system according to Fig. 1 during an overload in a comfort sub-network of the vehicle electrical system, Fig. 4. Schematic representation of an electrical equivalent circuit of the vehicle electrical system according to Fig. 1 during an operating state with high dynamics in the vehicle electrical system, Fig. 5 schematically an electrical equivalent circuit diagram of the vehicle electrical system according to Fig. 1 in the event of a fault in a comfort sub-network of the vehicle electrical system, Fig. 6 schematically an electrical equivalent circuit diagram of the vehicle electrical system according to Fig. 1 in the event of a fault in a first safety subnetwork of the vehicle electrical system and Fig. 7 schematically an electrical equivalent circuit diagram of the vehicle electrical system according to Fig. 1 in the event of a fault in a second safety subnetwork of the vehicle electrical system.

[0029] Corresponding parts are marked with the same reference symbols in all figures.

[0030] In Fig. Figure 1 shows an electrical equivalent circuit diagram of a possible embodiment of an electrical on-board network 1 of a vehicle during a normal operating condition.

[0031] The on-board network 1 comprises a high-voltage on-board network 2 and an electrical high-voltage energy storage device 3, which can be optionally coupled to or decoupled from the high-voltage on-board network 2 via a switching element 4.

[0032] A DC-DC converter 5 is coupled to the high-voltage electrical system 2. A first sub-electrical system 6 is electrically coupled to an output of the DC-DC converter 5, with the DC-DC converter 5 being intended to supply all static loads in the first sub-electrical system 6. The first sub-electrical system 6 is, in particular, a low-voltage electrical system, with a nominal voltage of the first sub-electrical system 6 being, for example, 12 volts.

[0033] The first sub-network 6, for example, is designed as a comfort network for the electrical supply of electrical consumers 7.1 to 7.n intended for comfort functions of the vehicle. Such comfort functions include, for example, seat heating, interior lighting, seat ventilation, seat massage, an entertainment system, etc. In addition, the first sub-network 6 can also supply other electrical consumers 7.1 to 7.n not intended for comfort functions.

[0034] In a manner not shown in detail, the first sub-network 6 comprises several power distributors with fuses and / or power distributors with semiconductor switches for connecting the electrical consumers 7.1 to 7.n to the first sub-network 6.

[0035] The on-board network 1 further comprises an electrical energy storage device 8 that is electrically connected or switchable in parallel to the first sub-on-board network 6. The DC / DC converter 5 is provided for charging the energy storage device 8.

[0036] Between the first sub-system 6 and the energy storage device 8, a first electrical switch 9 is arranged, which in a first switching state electrically connects the first sub-system 6 and the energy storage device 8 and in a second switching state electrically disconnects the first sub-system 6 and the energy storage device 8 from each other.

[0037] The on-board network 1 further comprises a second on-board network 10, which is electrically connected or switchable in parallel to the first sub-on-board network 6 and the energy storage device 8. The DC / DC converter 5 is provided for supplying all static loads in the second sub-on-board network 10.

[0038] A second electrical switch 11 is arranged between the energy storage device 8 and the second sub-system 10, which in a first switching state electrically connects the energy storage device 8 and the second sub-system 10 and in a second switching state electrically disconnects the energy storage device 8 and the second sub-system 10.

[0039] The on-board network 1 further comprises a third on-board network 12 that is electrically connected or switchable in parallel to the second sub-on-board network 10.

[0040] Between the second sub-system 10 and the third sub-system 12 a third electrical switch 13 is arranged, which in a first switching state electrically connects the second sub-system 10 and the third sub-system 12 and in a second switching state electrically disconnects the second sub-system 10 and the third sub-system 12 from each other.

[0041] The third sub-system 12 is electrically coupled at its input to an output of another DC-DC converter 14. The input of this further DC-DC converter 14 is coupled to the high-voltage energy storage device 3 and, when the switching element 4 is closed, to the high-voltage system 2. The further DC-DC converter 14 is intended to supply all loads in the third sub-system 12 and converts an electrical voltage from the high-voltage system 2 into an electrical voltage of the third sub-system 12.

[0042] The second and third sub-systems 10, 12 are specifically designed as low-voltage systems and are intended, for example, for a redundant electrical supply to the same electrical consumers 15.1 to 15.m. The nominal voltage of the sub-systems 10, 12 is, for example, 12 volts. In particular, the sub-systems 10, 12 are safety systems designed for a redundant electrical supply of electrical consumers 15.1 to 15.m that are safety-relevant for the operation of the vehicle. The electrical consumers 15.1 to 15.m are, for example, used for the operation of a steering system, brakes, lighting, automated driving functions of the vehicle, etc. For example, the electrical consumers 15.1 to 15.m are control units. In possible configurations, however, the second sub-system 10 and / or the third sub-system 10 can also each supply additional safety-relevant electrical consumers 15.1 to 15.Electrical consumers 15.1 to 15.m are supplied with power to each of the sub-networks 10 and 12, and do not require a redundant electrical supply. These electrical consumers are intended, for example, to perform functions such as windshield wipers or exterior vehicle lighting. Both sub-networks 10 and 12 each comprise, in a manner not shown in detail, several power distribution units with semiconductor fuses for connecting the electrical consumers 15.1 to 15.m to the respective sub-network 10 and 12. Depending on the existing safety concept, fuse links may be used instead of power distribution units with semiconductor fuses.

[0043] In the illustrated embodiment of the vehicle electrical system 1 during normal operation, the first switch 9 and the second switch 11 are closed. The third switch 13 can be open or closed depending on an operating strategy. The DC-DC converter 5 supplies electrical energy to the electrical consumers 7.1 to 7.n of the first sub-system 6 and the electrical consumers 15.1 to 15.m of the second sub-system 10. Furthermore, the DC-DC converter 5 charges the energy storage device 8. It is also possible for the additional DC-DC converter 14 to charge the energy storage device 8. This is particularly advantageous when the vehicle is parked, since charging the energy storage device 8 via the additional DC-DC converter 14, which is directly coupled to the high-voltage energy storage device 3, does not require activating the high-voltage electrical system 2.The energy storage device 8 is intended for buffering dynamic processes in the first and second sub-network 6, 10.

[0044] Fig. Figure 2 shows an electrical equivalent circuit diagram of the vehicle electrical system 1 according to Fig. 1 during a feed-back of an electrical consumer 15.2, for example an electric steering system of the vehicle, into the second and / or third sub-network 10, 12.

[0045] During such an operating state of the vehicle electrical system 1, switches 9, 11, and 13 are closed. Should the third switch, 13, be open, it will be closed, at least briefly.

[0046] If a vehicle user performs a dynamic maneuver, such as a double lane change, the steering system may feed electrical current into the second and / or third sub-network 10, 12. Such an injection is detected, for example, by a monitoring device (not shown) designed to monitor electrical parameters in the sub-networks 6, 10, 12. Based on the switching states of switches 9, 11, 13, the energy storage device 8 can absorb the regenerated current from several steering components, thus preventing an overvoltage in the sub-networks 6, 10, 12. This is represented by an energy flow E1.

[0047] In Fig. Figure 3 is an electrical equivalent circuit diagram of the on-board network 1 according to Fig. 1 shown during an overload in the first sub-network 6.

[0048] If, for example, too many consumers 7.1 to 7.n are activated, the DC-DC converter 5 alone may not be able to supply the first sub-network 6 with sufficient electrical energy. This is detected, for example, by the monitoring device. In this case, the third switch 13 is closed, if it is not already closed, so that the additional DC-DC converter 14, in addition to the DC-DC converter 5, supplies the sub-networks 6, 10, and 12 with electrical energy and can buffer any peak loads. This is represented by an energy flow E2.

[0049] By opening the third switch 13 and / or the first switch 9, in the event of electrical faults or undervoltage events in at least one of the sub-networks 6, 10, 12, the sub-networks 6, 10, 12 can be electrically isolated from each other within a very short fault tolerance time, depending on a safety concept for maintaining functional safety. This ensures that all sub-networks 6, 10, 12 are independent of each other according to ISO 26262-9:2018, such that an electrical fault in one sub-network 6, 10, 12 does not affect the other sub-networks 6, 10, 12. In this way, redundancy requirements for electrical systems, for example up to Automotive Safety Integrity Level D (ASIL D), are met. Fig. Figure 4 shows an electrical equivalent circuit diagram of the vehicle electrical system 1 according to Fig. 1 during a high dynamic operating condition in the on-board network 1.

[0050] During such an operating state of the on-board network 1, switches 9, 11, 13 are initially closed.

[0051] For example, if a vehicle user performs a dynamic maneuver, such as a so-called double-braked lane change, all electrical consumers 15.1 to 15.m, including the steering, brakes, and / or other dynamic consumers, may demand a high amount of energy from the energy storage device 8. If the energy storage device 8 cannot supply this amount of energy and a temporary undervoltage occurs in the sub-networks 6, 10, and 12, the third switch 13 and the first switch 9 are opened to counteract the undervoltage before the limits of the safety concept for maintaining functional safety, such as voltage thresholds, are reached. The temporary occurrence of the undervoltage is detected, for example, by the monitoring device.

[0052] In Fig. 5 is an electrical equivalent circuit diagram of the on-board network 1 according to Fig. 1 shown in the case of an electrical fault F1 in the first sub-network 6.

[0053] During such an operating state of the on-board network 1, switches 9, 11, 13 are initially closed.

[0054] If an electrical fault F1 occurs in the first sub-network 6, for example a short circuit to ground resulting in undervoltage, the first switch 9 is immediately opened within the specified fault tolerance time to protect the safety-relevant consumers 15.1 to 15.m. Voltage thresholds, for example, are used as triggers for this, with the fault F1 being detected, for example, by the monitoring device.

[0055] Fig. Figure 6 shows an equivalent electrical circuit diagram of the vehicle electrical system 1 according to Fig. 1 in case of an electrical fault F2 in the second sub-system 10.

[0056] During such an operating state of the on-board network 1, switches 9, 11, 13 are initially closed.

[0057] If an electrical fault F2 occurs in the second sub-system 10, for example a short circuit to ground resulting in undervoltage, the third switch 13 is immediately opened within the specified fault tolerance time to protect the safety-relevant loads 15.1 to 15.m of the third sub-system 12. If necessary, the second switch 11 is also opened. Voltage thresholds, for example, are used as triggers for this, with the fault F2 being detected, for example, by the monitoring device.

[0058] In Fig. Figure 7 is an electrical equivalent circuit diagram of the on-board network 1 according to Fig. 1 shown in the case of an electrical fault F3 in the third sub-network 12.

[0059] During such an operating state of the on-board network 1, switches 9, 11, 13 are initially closed.

[0060] If an electrical fault F3 occurs in the third sub-network 12, for example a short circuit to ground resulting in undervoltage, the third switch 13 is immediately opened within the specified fault tolerance time to protect the safety-relevant consumers 15.1 to 15.m of the second sub-network 10. Voltage thresholds, for example, are used as triggers for this, with the fault F3 being detected, for example, by the monitoring device. Reference symbol list 1 On-board electrical system 2 high-voltage electrical systems 3 high-voltage energy storage units 4 switching element 5 DC-DC converters 6 first sub-network 7.1 to 7.n Consumers 8 Energy storage 9 switches 10 second partial on-board network 11 switches 12 third sub-network 13 switches 14 DC / DC converters 15.1 to 15.m Consumer E1, E2 Energy flow F1 to F3 errors

Claims

[1] Electrical system (1) for a vehicle with - a first partial on-board network (6), - a DC voltage converter (5) which is electrically coupled with its output to the first sub-system (6), designed for the electrical supply of electrical consumers (7.1 to 7.n) intended for comfort functions, - an electrical energy storage device (8) connected or switchable in parallel to the first partial vehicle electrical system (6), - a first electrical switch (9) arranged between the first sub-system (6) and the energy storage device (8), which in a first switching state electrically connects the first sub-system (6) and the energy storage device (8) and in a second switching state electrically disconnects the first sub-system (6) and the energy storage device (8), - a second sub-system (10) that is electrically connected or switchable in parallel to the first sub-system (6) and the electrical energy storage device (8), - a second electrical switch (11) arranged between the energy storage device (8) and the second sub-system (10), which in a first switching state electrically connects the energy storage device (8) and the second sub-system (10) and in a second switching state electrically disconnects the energy storage device (8) and the second sub-system (10) from each other, - a third sub-system (12) which is electrically connected or switchable in parallel to the first sub-system (6), the second sub-system (10) and the electrical energy storage device (8), wherein the second sub-system (10) and the third sub-system (12) are designed to provide a redundant electrical supply for electrical consumers (15.1 to 15.m) that are safety-relevant for the operation of the vehicle, - a further DC voltage converter (14), which is electrically coupled to the third sub-system (12) via its output, and - a third electrical switch (13) arranged between the second sub-system (10) and the third sub-system (12), which in a first switching state electrically connects the second sub-system (10) and the third sub-system (12) and in a second switching state electrically disconnects the second sub-system (10) and the third sub-system (12) from each other. [2] Electrical system (1) according to claim 1, wherein the second sub-system (10) and / or the third sub-system (12) are additionally designed to provide an electrical supply for safety-relevant electrical consumers (15.1 to 15.m) for the operation of the vehicle, which are each assigned only to the second sub-system (10) or the third sub-system (12) and are not provided for a redundant electrical supply. [3] Electrical system (1) according to claim 1 or 2, comprising a high-voltage electrical system (2) which is coupled or can be coupled to at least one high-voltage electrical energy storage device (3). [4] Electrical on-board network (1) according to claim 3, wherein the DC voltage converter (5) coupled to the first partial on-board network (6) is coupled with its input to the high-voltage on-board network (2). [5] Electrical on-board network (1) according to claim 3 or 4, wherein the further DC voltage converter (14) coupled to the third partial on-board network (12) is coupled with its input to the electrical high-voltage energy storage device (3). [6] Electrical on-board network (1) according to one of the preceding claims, comprising a monitoring device for monitoring electrical parameters in the sub-on-board networks (6, 10, 12). [7] Electrical on-board network (1) according to claim 6, comprising a control unit coupled to the monitoring device via data technology, which is designed at least to control the switches (9, 11, 13) depending on the electrical parameters of the sub-on-board networks (6, 10, 12). [8] Method for operating an electrical on-board network (1) according to one of the preceding claims, wherein - in a regenerative operation in which an electrical consumer (15.1 to 15.m) arranged in the second sub-system (10) and / or third sub-system (12) feeds electrical energy back into the respective sub-system (10, 12) in generator mode, the switches (9, 11, 13) are closed or are closed, so that the regenerated electrical energy is fed into the electrical energy storage device (8), - in the event of an electrical overload in the first sub-system (6), with the first switch (9) and the second switch (11) closed, the third switch (13) is closed and the sub-systems (6, 10, 12) are supplied electrically by means of both DC voltage converters (5, 14), - in the event of high dynamics of electrical parameters in all sub-networks (6, 10, 12) and a risk of the voltage falling below a predetermined limit value in the second sub-network (10) with the second switch (11) closed, the third switch (13) and / or the first switch (9) may be opened, - if an electrical fault (F1) occurs in the first sub-system (6) when all switches (9, 11, 13) are closed and is detected by a fall below or exceeding a predetermined voltage limit, the first switch (9) is opened, - if an electrical fault (F2) occurs in the second sub-system (10) when all switches (9, 11, 13) are closed and is detected by a fall below or exceeding a specified voltage limit, the third switch (13) is opened and - if an electrical fault (F3) occurs in the third sub-system (12) when all switches (9, 11, 13) are closed and is detected by a fall below or exceeding a specified voltage limit, the third switch (13) is opened.

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