DE102016224618A1 - Vehicle electrical system with high availability - Google Patents

Abstract

A vehicle electrical system comprises a first sub-network (10) of a first voltage level, a second sub-network (20) of a second voltage level and a number of consumers (V, S, EPS). At least a first energy store is connected to the first subnetwork (10) for the purpose of feeding in energy and / or for the removal of energy. At least a second energy store (Batt2) is connected to the second subnetwork (20) for the purpose of feeding in energy and / or for the removal of energy. A part number of the number of consumers (S, EPS) can be coupled to the first and the second subnetwork (10, 20) and can be supplied with energy from the first and / or the second subnetwork (10, 20) as a function of an operating situation. Furthermore, a third sub-network (30) of a third voltage level is provided, which is higher than the first and the second voltage level. Connected to the third subnetwork (30) is a third energy store (Batt3), which comprises at least one sub-tap (BKP) to which, based on a reference potential of the vehicle electrical system, a voltage corresponding to the first voltage level is present. The first sub-network (10) is connected to the sub-tap (BKP) of the third energy store (Batt3), whereby the first energy store of the first sub-network (10) is provided by a storage section (B1) of the third energy store (Batt3).

Description

The invention relates to a vehicle electrical system with high availability during a driving operation of a vehicle, in particular in autonomous or semi-autonomous driving functions.

Vehicles that permit autonomous or semi-autonomous driving require a highly available electrical energy supply of various safety-relevant components and functions. In particular, it must be ensured that, during the journey, a fault or defect in the vehicle electrical system can not or only with minimum probability lead to a loss of driving functions. When an error or defect occurs in the vehicle electrical system, it must be ensured, at least for a certain period of time, that safety-relevant components or functions are still working until a driver of the vehicle can safely bring it to a standstill. Such components include, for example, dynamic stability control, electric steering, a display and control component, a driver assistance system, and the like.

Can be impaired the availability of the vehicle electrical system by a variety of different errors. These are determined by 1 , which shows a schematic representation of a conventional vehicle electrical system with two energy storage explains.

The vehicle electrical system 1, which is designed by way of example to a rated voltage of 12 volts, includes by way of example a generator G as an energy source, two energy storage Batt1, Batt2 and three consumers V, S, EPS. In a hybrid or electric vehicle, the power source is a DC / DC converter. All of these components G, Batt1, Batt2, V, S, EPS are connected to a common physical electrical system consisting of cables and power distributors. In addition, an optional safety battery terminal SBK is provided in the physical vehicle electrical system, wherein the safety battery terminal SBK is arranged between the energy store Batt1 and the components G, Batt2. The safety battery terminal SBK divides the physical electrical system into a first sub-string, to which the battery Batt1 is connected, and a second sub-string, to which the generator G and the second energy store Batt2 are connected. Two power distributors SV, SH are also connected by way of example to the first sub-string. Each of the power distributors SV, SH comprises a number of terminals KL or fuses, to which the consumers V, S, ERS or other components of the vehicle electrical system are connected. Contrary to the drawing, the consumers V, S, EPS could also be connected to one of the terminals KL of the power distributor SH.

The safety battery terminal SBK is usually a one-time, pyrotechnic switching element. Normally, the first and the second sub-string via the safety battery terminal SBK permanently electrically connected to each other. Only in the event of a crash, for security reasons, e.g. using a signal output by an airbag control unit, the safety battery terminal SBK is opened by appropriate control in order to separate the electrical connection between the first sub-string and the second sub-string. Furthermore, as a result, the current distributors SV, SH are also electrically isolated from the second energy store Batt2 and from the generator G.

However, the supply of consumers can also be caused by other defects in an undesirable manner. A defect of the generator G may have different effects depending on the type of defect. If the generator G generates a voltage which is less than the battery voltage, then the energy stores Batt1, Batt2 are discharged. This eventually leads to the failure of or the energy storage Batt1, Batt2, so that the consumers of the vehicle electrical system can not be supplied with energy. If the voltage generated by the generator G is greater than a first predetermined threshold, the energy stores Batt1, Batt2 are or will be overloaded. This also ultimately leads to the failure of or the energy storage Batt1, Batt2. If the voltage generated by the generator G exceeds a second threshold value, overvoltage circuits built into the loads detect the exceeding of this voltage wave and switch off the corresponding consumers.

Conversely, if, for example, the first energy store Batt1 fails, the consumers connected to the power distributors SV, SH can still be supplied with energy via the generator G and / or the second energy store Batt2, at least for a certain time.

Another problem that can lead to the failure of single or multiple consumers are failures or defects in the physical electrical system, such. Cable or power distributor. For example, by contact corrosion or aged fuses the voltage level of the vehicle electrical system can deteriorate, even to the failure of components. Also due to cable breakage or occurring short circuits, the functionality of individual or all components may be impaired.

The occurrence of the described errors in a like in 1 shown vehicle electrical system thus leads to certain functions in a vehicle from the time of the occurrence of the error are no longer available, so that a safe vehicle movement can not be guaranteed. This applies in particular to vehicles with autonomous or semi-autonomous driving functions.

To solve the problems described above proposes the DE 10 2014 221 281 the applicant before to provide safety-related functions, such as highly reliable consumer, depending on an operating situation from the first and / or from the second sub-strand with energy. For this purpose, it is intended to couple these highly fail-safe consumers with both the first and the second sub-string. The redundancy is provided by a controllable decoupling element, which supplies the consumers optionally from the first and / or the second sub-strand with energy.

In future vehicle on-board networks, not only a plurality of sub-strands, but also sub-strands with different voltage levels are provided, for example, in order to produce, e.g. To provide consumers with very high power consumption from a sub-string with a higher voltage (for example, 48V). The sub-strands of different voltage levels are connected to a flow of energy among each other, via a DC-DC converter. In such on-board network architectures there is the problem that a further energy store, e.g. a 48V battery, in which vehicle must be provided. By then already three energy storage costs rise and the space required for this to an undesirable level.

It is an object of the present invention to provide a vehicle electrical system with multiple voltage levels, which structurally and / or functionally improved and whose availability is high when an error occurs.

This object is achieved by a vehicle electrical system according to the features of claim 1. Advantageous embodiments result from the dependent claims.

A vehicle electrical system is proposed which comprises a first subsystem of a first voltage level, a second subsystem of a second voltage level and a number of consumers. At least a first energy store is connected to the first subsystem of the first voltage level for feeding energy and / or for removing energy. At least a second energy store is connected to the second subsystem of the second voltage level for feeding energy and / or for removing energy. At least a part number of the number of consumers can be coupled to the first and the second subnetwork and can be supplied with energy from the first and / or the second subnetwork as a function of an operating situation. A vehicle electrical system with the components described above is for example from the DE 10 2014 221 281 A1 known and is referred to as a two-store electrical system.

The vehicle electrical system is further characterized in that it comprises a third sub-network of a third voltage level. In this case, the third voltage level is higher than the first and the second voltage level of the first and the second subnetwork. To the third subnet a third energy storage is connected. The third energy store comprises at least one partial tap on which, based on a reference potential of the vehicle electrical system, a voltage corresponding to the first voltage level of the first subnet is present. A node of the first subnet is connected to the sub-tap of the third energy store, whereby the first energy store of the first subnet is provided by a memory section of the third energy store.

Such a vehicle electrical system is functionally a three-store electrical system, wherein at least the third energy store of the third subnetwork has a higher voltage than the first and the second energy store of the first and the second subnetwork. Because the first energy store of the first subnetwork is provided by a memory section of the third energy store, the first energy store of the first subnetwork does not need to be provided physically. Its elimination is made possible by the fact that a partial tap is provided in the third energy store to which, based on a reference potential of the vehicle electrical system, a voltage corresponding to the first voltage level is present. If the first subnet is connected to the sub-tap of the third energy store, the memory section lying between the sub-tap and the reference potential of the vehicle represents the first energy store of the first sub-network. As a result, a vehicle electrical system can be provided which, due to its topology, provides the redundant supply of consumers. The elimination of the first energy storage of the first sub-network costs, space and weight can be saved. Although the vehicle electrical system thus only includes two different energy stores physically, the topology of the vehicle electrical system corresponds to a three-store electrical system.

According to an expedient embodiment, the vehicle electrical system comprises a controllable energy transfer element, which is designed to compensate for the state of charge of memory cells in the memory section of the third energy store, if these have a charge underside or cover over memory cells of a residual storage section of the third energy store. The controllable energy transfer element makes it possible to exchange energy between the third subnetwork and the first or the second subnetwork, in order to be able to compensate for any charge shortage of the memory section of the third energy store that represents the first energy store by charging. The controllable energy transfer element can also be configured and arranged such that the recharging or discharging of the storage section of the third energy store takes place from the third subnet, provided that an energy generator is connected to it.

According to a first variant, the energy transfer element can electrically interconnect the first subnetwork with the second subnetwork. This makes it possible, for example, with the help of the energy transfer element energy, e.g. from the second energy storage in the first subnet and thus to transfer the memory portion of the third energy storage.

In another variant, the energy transfer element between a node of the third subnet and the sub-tap of the third energy storage can be interconnected. This makes it possible, while bypassing the residual storage section of the third energy store, to recharge the storage section of the third energy store, which represents the first energy store, directly from the third subnetwork.

It is expedient if the energy transfer element is a DC-DC converter. The DC-DC converter can transmit energy between its input and output by means of appropriate control.

Alternatively or in addition to the DC-DC converter, the energy transfer element may comprise a switching element, which is switched in the normal operation of the electrical system by means of a first control signal and switched off when a fault occurs in the first or the second subnet by means of the first control signal. This embodiment variant relates to the arrangement according to the first variant, in which the energy transfer element electrically interconnects the first subnetwork with the second subnetwork. The reversible controllable switching element may, for example, be a semiconductor switching element, such as e.g. a MOSFET and the same, or be a relay. In normal operation of the electrical system, the reversibly controllable switching element electrically connects the first and the second sub-network with each other. When an error occurs, e.g. in the cabling of the first or second subnetwork or a component connected to the first or second subnetwork (e.g., power source, energy storage or consumer), the electrical connection between the first and second subnetworks is separated by means of the reversibly controllable switching element. The supply of the number of parts of the consumer is then via that subnetwork, in which the power supply is still possible undisturbed.

It is sufficient if the provision of the power supply from the non-faulty subnet is made possible only for a certain time. During this period, the possibly autonomous or semi-autonomously operated vehicle should be brought to a standstill between the occurrence of the fault and the depletion of the power supply.

Does the energy transfer element alternatively or in addition to the reversibly switchable switching element on the already mentioned DC-DC converter, which is controlled in the normal operation of the electrical system by means of a corresponding control signal such that this energy from the first subnet to the second subnet, or vice versa, transmits, for example a supply of the number of parts to consumers from both subnets are made possible. This is, for example, in safety-relevant consumers, such as e.g. an electrically trained steering possible whose electric drive has two coils, one of which is supplied from the first subnet and the other from the second subnet.

Furthermore, when an error occurs in the first or the second subnetwork, the DC / DC converter can be controlled by means of a corresponding control signal in such a way that it prevents an energy transmission between the first and the second subnetwork. In this case, the function of the DC-DC converter corresponds to the function of the reversibly controllable switching element described above.

If the energy transfer element comprises both the reversibly controllable switching element and the DC-DC converter, these are connected in parallel. When an error occurs then the reversibly controllable switching element must be turned off and switched off the DC-DC converter in order to separate the electrical connection between the first and the second subnet. To an energy transfer of the second to enable the first subnet, the controllable switching element is suitably switched blocking and transfer the energy via the DC-DC converter to the first subnet and thus the memory portion of the third energy storage. The recharging can also be done with conductive switched controllable switching element.

The separation of the first and the second subnetwork in the security-relevant case can be done in the presence of the controllable switching element either in real time and event-driven or even before the occurrence of the security-relevant case. In the first case, a high outlay for the switching element is required because it must be ensured by diagnoses and ASIL technology of the switching element whose reliable operation. If the controllable switching element is switched to blocking already before the occurrence of the security-relevant case, this can be done e.g. directly after the start or before moving the vehicle. In this case, the controllable switching element can be realized in a simple, non-real-time execution. The switching element can be configured, for example, as a relay with diagnosis. In this case, a sufficient capacity of the second energy storage for the regular driving operation or the DC converter mentioned above between the third subnet and the second subnet is required.

In the arrangement of the energy transfer element between the first and the second subnetwork, the idle or quiescent power requirement of the vehicle is preferably synergistically via the second energy store and the first energy store, i. H. supplies the memory section of the third energy store of the third subnet. This reduces the dimensioning of the second energy store. The recharging of the memory portion of the third energy storage can then, as described, carried out with the controllable switching element open, via the DC-DC converter.

According to a further expedient embodiment, the first and the second voltage level are the same voltage levels. In particular, the first and the second voltage level have a nominal voltage of 12V. In contrast, the rated voltage of the third voltage level is higher. For example, the third voltage level may have a rated voltage of 24V or 48V or higher.

A further embodiment provides that the third subnet and the second subnet are coupled via a DC-DC converter. The DC-DC converter ensures a flow of energy between the third and the second subnetwork and at the same time adapts an adaptation of the rated voltage of the third subnetwork and to the nominal voltage of the second subnetwork.

According to a further expedient embodiment, the vehicle electrical system further comprises at least a first power distributor and at least a second power distributor. The at least one first power distributor comprises a plurality of first terminals, to each of which a number of consumers is connected, wherein the at least one first power distributor is connected to the second subnet. The at least one second power distributor comprises a plurality of second terminals, to each of which the number of parts of the number of consumers is connected, wherein the second power distributor is connected to the first subnet. The at least a part number of the number of consumers can be supplied with energy from the first and / or the second power distributor as a function of the operating situation. According to this embodiment, the first and the second power distributor are used for the redundant supply of the number of parts to consumers.

According to a further expedient embodiment, the consumers coupled to the first and the second subnetwork are safety-relevant components of the vehicle which are necessary or used for the maintenance or execution of an autonomous movement of the vehicle. In particular, this includes components which are required for a lateral guidance of the vehicle, such as e.g. a steering. Safety-related components can also be used for longitudinal guidance components, such as Brake system, or a driver assistance system or a dynamic stability control or one or more display control units or gateways for bus systems.

The second energy store may be a conventional lead-acid battery. Alternatively, the second energy storage device may be a supercup or a lithium-ion battery, which are respectively designed to receive and dispense generation peaks and load peaks.

The third energy store may be correspondingly a conventional lead-acid battery, a lithium-ion battery or a high-voltage battery. The structure of the third energy store is such that it provides a rated voltage corresponding to the third voltage level at its output terminals.

The vehicle electrical system may also include a control device for controlling the energy transfer element. The control device is designed to control the energy transfer element in such a way as to reload the storage section of the third energy store, if this opposite to a residual storage section of the third energy storage has a charge shortage. This is to ensure that all memory cells of the third energy storage have, if possible, a same voltage.

In addition, the control device for controlling the energy transfer element may be designed to switch the otherwise switched on power transfer element blocking while receiving an error signal that signals the detection of a safety-critical error and at the same time the number of parts of the consumer coupled to the first and the second subnet are to connect by driving exclusively electrically to the first or the second subnet, which does not have the safety-critical error. The control device may be part of the energy transfer element. The control unit may also be an external control unit.

As described above, the safety-critical fault can be a short circuit or an overvoltage or undervoltage in one part of the vehicle electrical system. In order to connect the number of parts of the consumer only electrically to the first or the second subnet, which does not have the safety-critical error, a corresponding switching device may be provided in the corresponding consumers, which performs a switch to the error-free subnet for power supply. At the same time, depending on the content of the error signal, an electrical connection to the faulty subnet is resolved. The separation of the two subnets can be performed in real-time or event-controlled in the security-relevant case.

According to another operating strategy, the energy transfer element may already be subject to a safety-critical error, e.g. be opened directly after the start of the vehicle, so that a separation of the connection between the first and the second subnet is made. The supply of the number of consumers then takes place from the second subnet. A supply of consumers from the first energy storage, d. H. the memory portion of the third energy storage, then takes place when an error occurs. The energy balance is effected, as described, via the energy transfer element between the first and second sub-networks, e.g. in the state of the vehicle.

• 1 eine schematische Darstellung eines herkömmlichen Zwei-Speicher-Bordnetzes bei dem keine redundante Versorgung von Verbrauchern vorgesehen ist;
• 2 eine schematische Darstellung eines aus dem Stand der Technik bekannten Zwei-Speicher-Fahrzeug-Bordnetzes, bei dem eine redundante Versorgung ausgewählter Verbraucher ermöglicht ist;
• 3 eine schematische Darstellung eines erfindungsgemäß ausgebildeten Drei-Speicher-Fahrzeug-Bordnetzes mit zwei Spannungsebenen, bei dem ein Energietransferelement zwischen einem ersten und einem zweiten Teilnetz gleicher Spannungsebene angeordnet ist;
• 4 eine schematische Darstellung eines erfindungsgemäßen Drei-Speicher-Fahrzeug-Bordnetzes mit unterschiedlichen Spannungsebenen, bei dem ein Energietransferelement zwischen einem Knotenpunkt eines dritten Teilnetzes einer dritten Spannungsebene und einem Teilabgriff eines Energiespeichers des dritten Teilnetzes verschaltet ist; und
• 5 eine schematische Darstellung eines erfindungsgemäßen Drei-Speicher-Fahrzeug-Bordnetzes, welches eine abgewandelte Verschaltung des Energietransferelements gegenüber 4 illustriert.

The invention will be explained in more detail below with reference to exemplary embodiments in the drawing. Show it:

• 1 a schematic representation of a conventional two-storage vehicle electrical system in which no redundant supply of consumers is provided;
• 2 a schematic representation of a known from the prior art two-storage vehicle electrical system, in which a redundant supply of selected consumers is possible;
• 3 a schematic representation of an inventively designed three-memory vehicle electrical system with two voltage levels, in which an energy transfer element between a first and a second sub-network of the same voltage level is arranged;
• 4 a schematic representation of a three-memory vehicle electrical system according to the invention with different voltage levels, in which an energy transfer element between a node of a third sub-network of a third voltage level and a partial tap of an energy storage of the third sub-network is connected; and
• 5 a schematic representation of a three-memory vehicle electrical system according to the invention, which faces a modified interconnection of the energy transfer element 4 illustrated.

2 shows a schematic representation of one in the DE 10 2014 221 281 A1 described vehicle Bornetzes 1 on which the vehicle electrical system according to the invention 1 based. This in 2 shown vehicle electrical system 1 is in a first subnet 10 and a second subnet 20 divided. The first and second subnets 10 . 20 are via a decoupling element EE coupled together. In accordance with a control of the decoupling element EE can be the first subnet 10 and the second subnet 20 be electrically connected to each other or have no electrical connection to each other.

The first subnet comprises in the electrical equivalent circuit diagram a first energy store Batt1. At the first energy storage Batt1 it is a 12V battery of the vehicle electrical system 1 For example, a lead accumulator.

To the second subnet 20 are in the electrical equivalent circuit an energy source in the form of a generator G , an optional second energy storage BATT2 and one or more optional consumers V connected. The generator G For example, it is mechanically driven by an internal combustion engine that converts the rotational energy into electrical energy. If the vehicle is an electrified vehicle such as a plug-in hybrid vehicle or a hybrid electric vehicle or a battery-powered vehicle, instead of the generator G one DC / DC Transducer provided. In a corresponding manner is a dimensioning of the first energy storage Batt1 for a semi-autonomous driving operation required. The second energy storage Batt2 is, for example, a lithium-ion battery. The second energy storage BATT2 is able to absorb large currents in a short time or, if a consumer V briefly has a high power consumption to deliver a correspondingly high current. Optionally, the second subnet 20 also comprise one or more further energy stores, such as double-layer capacitors (supercaps). The only optionally connected directly to the second subnet consumer V may be any power consumer component, such as a starter motor and the like.

Contrary to the graphic representation of the connection of the consumer V to the second subnet 20 The consumers installed in a vehicle are connected to the terminals of a power distributor. Typically, a vehicle has one or more such power distributors. In 2 are two first power distributors SV . SH to the second subnet 20 connected. Each of the first power distributors SV . SH includes an individual number of terminals KL , wherein each of the terminals are associated with one or more fuses. All or at least the vast majority of consumers of the vehicle electrical system, which are not shown in detail, are at respective terminals KL the first power distributor SV . SH connected. The first power distribution SV . SH are typically arranged at spatially different locations in the vehicle. For example, the first power distributor SV in the front of the vehicle and the first power distributor SH arranged in the rear of the vehicle. As a result, the electrical connection of the respective consumer or components can be made with relatively short lines. The electrical connection of the first power distributor SV . SH to the first or the second subnetwork 10 . 20 is about the decoupling element EE realized.

Similarly, a second power distributor SV2 having a number of terminals KL, via the decoupling element EE with the first subnet 10 electrically connected.

While some, in 2 not shown in detail consumers or components only with a clamp KL one of the first power distributors SV . SH are electrically connected to the second subnet 20 to be supplied with energy are safety-relevant consumers or components S . EPS both with the second power distributor SV2 and with one of the first power distributor (here: first power distributor SV ) coupled. Depending on an operating situation of the vehicle electrical system 1 become these safety-critical consumers S . EPS from the first subnet 10 and / or supplied with energy from the second subnetwork. To the optional supply of energy from one of the two subnets 10 . 20 consumers are able to realize this S . EPS via corresponding switching means, which the consumers either with the first power distributor SV or the second power distributor SV2 connect electrically.

The decoupling element EE is in the simplest embodiment, a reversibly controllable switching element S1, for example, a semiconductor switching element or a relay. In a normal operation of the electrical system 1 the switching element S1 is turned on by means of a first control signal and thereby electrically connects the first and the second sub-networks 10, 20 to each other. In this intended operation of the electrical system, the consumers S . EPS over the first power distributor SV from the second subnet 20 energized. When an error occurs, such as a generator failure G , the switching element S1 is turned off, ie opened. At the same time by the mentioned switching means in the respective consumers S . EPS a switchover from the first power distributor SV on the second power distributor SV2 performed. The safety-critical consumers S . EPS can now from the first subnet 10 or the first energy store connected thereto Batt1 be energized.

As the energy content of the first energy storage Batt1 limited, the energy supply can consumers S . EPS only for a certain period of time. This time and thus the energy content of the first energy storage Batt1 must be dimensioned such that since the occurrence of the error in the second subnet 20, the vehicle can for example still be brought to a safe stop. For this purpose, it may be sufficient, for example, to inform the driver acoustically and / or optically about the occurrence of the fault at the time of occurrence of the fault, so that the driver can safely bring the vehicle to a standstill within a predetermined period of time. The duration should be at least 10 seconds.

For reasons of energy efficiency, therefore, only safety-relevant consumers or components are supplied redundantly either via the first or the second power distributor with energy. Such consumers are, for example, components needed for the lateral guidance of the vehicle, such as e.g. a motor for controlling a steering.

The activation of the decoupling element EE and the switching means in the consumers S , EPS can be done with the same signal, so that with the disconnection of the electrical connection between the first and the second subnet 10 . 20 At the same time a switch to the error-free subnet can be made.

Instead of the switching element S1, the decoupling element EE also a DC-DC converter DC / DC include. The DC-DC converter DC / DC can be controlled in a manner that corresponds to the functionality of the switching element S1 just described. In addition, it is possible by suitable control of the DC-DC converter DC / DC in normal operation of the electrical system to control this so that the consumer S . EPS both via the first and the second power distributor SV . SV2 be energized. This will be in the consumers S . EPS contained switching elements correspondingly controlled, so that an electrical connection to both the first and to the second power distributor SV . SV2 consists. When an error occurs in the first or in the second subnet, the DC-DC converter DC / DC controlled such that this is the electrical connection between the first and the second subnet 10 . 20 disconnects, so that the supply to consumers S . EPS only one of the two power distributors SV . SV2 and thus from one of the two subnets 10 . 20 he follows.

Alternatively, both the switching element and the parallel-connected DC-DC converter DC / DC be provided. The switch S1 and the DC-DC converter DC / DC are then driven parallel to each other when an error occurs that the subnets 10 . 20 are electrically isolated from each other.

To a fault of the DC-DC converter DC / DC It is also serial to the DC-DC converter DC / DC a fuse F provided, which by the first energy storage Batt1 can be triggered.

The separation of the two subnets 10 . 20 in safety-relevant case thus takes place via the decoupling element EE , This can be done in real time or event driven. An alternative operating strategy is that even before the occurrence of a safety-relevant event, the decoupling element EE is opened. Prerequisite to the power distributors SV and SH Energy supply to connected consumers is a balancing efficiency of the generator G or a sufficient energy content of the second energy store BATT2 ,

The stand energy or quiescent power requirements of the vehicle can be synergistically via the two energy storage Batt1 and BATT2 be supplied. Recharging or full charging can be done with teilentladenem first energy storage Batt1 and opened switching element S1 via the parallel-connected DC-DC converter DC / DC respectively. This reduces the dimensioning of the second energy store BATT2 ,

3 shows an extension of the in 2 described vehicle electrical system. The vehicle electrical system according to the invention 1 is a so-called three-memory vehicle electrical system, which next to the first subnet 10 and the second subnet 20 a third subnet 30 includes. The first subnet 10 and the second subnet 20 have a same voltage level, eg with a rated voltage of 12V. On the other hand, the rated voltage of the voltage level of the third subnetwork 30 higher. For example, the third subnet is a 48V subnet. The rated voltage could also have a different value, for example 24V or 96V. In principle, the third subnetwork could also be a high-voltage subnetwork with a rated voltage of several 100V.

The third subnet 30 includes a third energy storage Batt3 and an energy generator SGR , eg a starter generator. The third subnet 30 is via a DC-DC converter DC / DC2 with the second subnet 20 connected. The DC-DC converter DC / DC2 assumes the task of a voltage conversion between the nominal voltage of the third subnetwork 30 and the rated voltage of the second sub-network 20 and an energy transfer from the third subnet 30 to the second subnet 20 ,

The third energy store Batt3 is between a central line of the third subnetwork 30 and a reference potential of the vehicle interconnected and has between its terminals on the rated voltage of the third voltage level corresponding terminal voltage (eg 48V). In a manner known to those skilled in the art, the third energy store comprises Batt3 a number of memory cells (battery cells), wherein at a partial tap BKP of the third energy store Batt3 , Based on the reference potential of the vehicle electrical system, a voltage can be tapped, which is the rated voltage of the first subnet 10 , eg 12V, corresponds.

The first subnet 10 is with the node BKP of the third energy store Batt3 connected. As a result, the intermediate between the partial tap BKP and the reference potential of the third energy store Batt3 lying memory section B1 the first energy store of the first subnetwork 10 out 2 ready. In other words, the first energy storage Batt1 , the arrangement known from the prior art according to 2 has, thereby eliminating that the first subnet 10 with the partial tap BKP of the third energy store Batt3 is connected to the one, based on the reference potential of the vehicle electrical system 1 , the first subnet 10 appropriate voltage is applied. A residual storage section B2 of the third energy store Batt3 is accordingly between the partial tap BKP and the central line of the third subnetwork 30 arranged.

The operating strategy to ensure the supply of safety-relevant consumers S . EPS which works with both the first power distributor SV as well as with the second power distributor SV2 may be connected in accordance with 2 be implemented procedure described. To a occurring in the operation of the vehicle electrical system charge under - or cover the memory section B1 associated memory cells with respect to the residual memory section B2 associated memory cells of the third energy storage Batt3 To be able to compensate, the decoupling element EE as an energy transfer element ETE be used. By appropriate operation of the DC-DC converter DC / DC as an energy transfer element ETE may be a reloading of the memory section B1 of the third energy store Batt3 associated memory cells take place. The energy required for recharging can, for example, from the second energy storage BATT2 and / or the third subnet 30 via the DC-DC converter DC / DC2 be removed. The charge equalization takes place until the cell voltages of the memory cells of the memory section B1 and the voltages of the memory cells of the residual memory section B2 correspond to each other.

Will the charge balance on the DC-DC converter DC / DC made, the reversibly controllable switching element S1 (if this is ever present) remains switched off. Includes the decoupling element EE only the controllable switching element S1, the charge balance can also via the controllable switching element S1 connected as an energy transfer element ETE respectively. In the sole presence of the controllable switching element S1, it is expedient to use an ASIL-capable switching element.

The 4 and 5 show variations of the in 3 illustrated vehicle electrical system 1 , It is in 3 provided energy transfer element ETE between the first and second subnets 10 . 20 each accounted for. This means the first and second subnets 10 . 20 have no electrical connection to each other. The supply of safety-relevant consumers S . EPS takes place in normal operation via the second subnet 2 and the second energy storage BATT2 , If the energy that can be supplied by the second energy store supplies power to the safety-relevant consumers S, EPS is not sufficient, via the DC-DC converter DC / DC2 from the third subnet 30 additional energy can be purchased. If an error occurs, eg in the second subnet 20 , can supply the security consumers S . EPS then over the memory section B1 of the third energy store Batt3 from the first subnet 30 respectively. The compensation of the charge shortage occurs via a DC-DC converter DC / DC3 which is between the central line of the subnetwork 30 and the reference potential of the vehicle electrical system is interconnected. The DC-DC converter DC / DC3 can be designed here as a buck converter, for example as a buck converter. On the output side is the DC-DC converter DC / DC3 with the node BKP connected. The DC-DC converter DC / DC3 is to compensate for the charge shortage, for example, from the starter generator SGR fed.

The variant according to 5 differs in that the DC-DC converter DC / DC3 input side with the central line of the third subnet 30 and the partial tap BKP and the output side with the reference potential of the vehicle Bornetzes 1 and the partial tap BKP is interconnected. In this variant, the DC-DC converter can be designed as a Cuk converter or flyback converter with galvanic isolation.

The proposed vehicle electrical system allows the simple and cost-effective implementation of a three-storage vehicle electrical system, which physically requires only two energy storage. An additional redundant energy storage of the first subnetwork can be omitted by the synergetic use of a Teilabgriffes the energy storage of the third subnetwork, which is operated with a higher nominal voltage. Safety-relevant functions can be ensured by the intelligent supply and interconnection as well as by a simple modification of the usual 48/12-volt standard architecture. In particular, highly autonomous driving with redundant supply of safety-relevant consumers is made possible.

LIST OF REFERENCE NUMBERS

1

Vehicle electrical system

10

first subnet

20

second subnet

30

third subnet

Batt1

first energy store

BATT2

second energy store

Batt3

third energy storage

B1

Memory section of the third energy storage

B2

Remaining memory portion of the third energy storage

BKP

Teilabgriff

EE

decoupling

ETE

Energy transfer element

DC / DC

DC-DC converter of the decoupling element EE between the first and second subnets

DC / DC2

DC-DC converter between the second and third subnetwork

DC / DC3

DC converter

F

fuse

G

generator

KL

jam

S, EPS

safety-relevant consumers

V

consumer

SV, SH

first power distributor

SV2

second power distributor

SGR

Energeierzeuger (starter generator)

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014221281 [0010]
• DE 102014221281 A1 [0014, 0039]

Claims (12)

Vehicle electrical system, comprising - a first sub-network (10) of a first voltage level, to which at least a first energy store is connected for feeding energy and / or for the removal of energy; - A second sub-network (20) of a second voltage level, to which at least a second energy store (Batt2) is connected to the supply of energy and / or for the removal of energy; - A number of consumers (V, S, EPS), wherein at least a part number of the number of consumers (S, EPS) with the first and with the second subnet (10, 20) can be coupled and depending on an operating situation from the first and / or the second subnetwork (10, 20) can be supplied with energy; and characterized in that a third subnetwork (30) of a third voltage level is provided, which is higher than the first and the second voltage level, to the third subnetwork (30) a third energy store (Batt3) is connected, which at least one Teilabgriff ( BKP) to which, based on a reference potential of the vehicle electrical system, a voltage corresponding to the first voltage level is applied, and a node of the first subnet (10) to the sub-tap (BKP) of the third energy store (Batt3) is connected, whereby the first energy store of the first subnetwork (10) is provided by a memory section (B1) of the third energy store (Batt3). Vehicle electrical system after Claim 1 characterized in that it comprises a controllable energy transfer element (ETE), which is designed to compensate for the state of charge of memory cells in the memory section (B1) of the third energy store (Batt3), when compared to memory cells of a residual memory section (B2) of the third energy store ( Batt3) have a charge underside or cover. Vehicle electrical system after Claim 2 , characterized in that the energy transfer element (ETE) electrically interconnects the first subnetwork (10) with the second subnetwork (20). Vehicle electrical system after Claim 2 , characterized in that the energy transfer element (ETE) between a node of the third subnet (30) and the sub-tap (BKP) is connected. Vehicle electrical system according to one of Claims 2 to 4 , characterized in that the energy transfer element (ETE) is a DC-DC converter (DC / DC, DC / DC3). Vehicle electrical system after Claim 2 or 3 , characterized in that the energy transfer element (ETE) comprises a switching element, which is switched in the normal operation of the electrical system by means of a first control signal and switched off when a fault in the first or the second subnet (10, 20) by means of the first control signal , Vehicle electrical system according to one of Claims 2 . 3 or 6 , characterized in that the DC-DC converter (DC / DC, DC / DC3) is controlled in the normal operation of the electrical system by means of a second control signal such that this energy from the first subnet (10) to the second subnet (20), or vice versa, transmits and when an error occurs in the first or the second subnetwork (10, 20) is controlled by means of the second control signal such that it prevents an energy transfer between the first subnetwork (10) and the second subnetwork (20). Vehicle electrical system according to one of the preceding claims, characterized in that the first and the second voltage level equal voltage levels, in particular with a nominal voltage of 12 V, are. Vehicle electrical system according to one of the preceding claims, characterized in that the third voltage level has a nominal voltage of 24 V or 48 V. Vehicle electrical system according to one of the preceding claims, characterized in that the third subnetwork (30) and the second subnetwork (20) are coupled via a DC-DC converter. Vehicle electrical system according to one of the preceding claims, wherein it further comprises: at least one first power distributor (SV, SH) which comprises a plurality of first terminals to which the number of consumers (S, EPS) is respectively connected, the at least one first power distributor (SV, SH) being connected to the second subnet ( 20) is connected; and - At least a second power distributor (SV2) comprising a plurality of second terminals, to which in each case the number of parts of the number of consumers (V, S, EPS) is connected, wherein the second power distributor (SV2) to the first subnet (10) is connected, wherein the at least a part number of the number of consumers (S, EPS) depending on the operating situation of the first and / or the second power distributor (SV, SV2) can be supplied with energy. Vehicle electrical system according to one of the preceding claims, in which the consumers (S, EPS) coupled to the first and the second sub-network (10, 20) are safety-relevant components of the vehicle necessary for the maintenance or carrying out an autonomous movement of the vehicle are necessary or used.

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