On-board power system for a motor vehicle, motor vehicle and method for operating an on-board power system

Abstract

On-board electrical system (2) for a motor vehicle (1) comprising a control device (4), an energy storage device (3) and a plurality of components (5-9) operable via the energy storage device (3), wherein the on-board electrical system (2) is divided into at least two sub-networks (10-14) and the sub-networks (10-14) each comprise at least one of the components (5-9), wherein the components (5-9) of different sub-networks (10-14) are each assigned to at least one different operating state of the motor vehicle (1), wherein components (5-9) assigned to a heating operating state, an air conditioning operating state, a chassis control operating state and / or an exhaust gas treatment operating state are each arranged in a separate sub-network (10-14), wherein each of the sub-networks (10-14) is separable from the energy storage device (3) via at least one switching device (15-19), and the control device (4) is configured to is,to control the switching devices (15 - 19) in dependence on operating state information which describes at least one current operating state of the motor vehicle (1) in such a way that the sub-networks (10 - 14) which comprise a component (5 - 9) assigned to the current operating state are connected to the energy store (3), and the sub-networks (10 - 14) which do not comprise a component (5 - 9) assigned to the current operating state are disconnected from the energy store (3).

Description

[0001] The invention relates to an on-board electrical system for a motor vehicle, comprising a control device, an energy storage device, and a plurality of components operable via the energy storage device. The on-board electrical system is divided into at least two sub-networks, each of which comprises at least one of the components. Furthermore, the invention relates to a motor vehicle and a method for operating an on-board electrical system.

[0002] On-board electrical systems of motor vehicles, particularly electric vehicles with an electric traction motor, are generally designed so that an energy storage device connected to the on-board electrical system, such as a traction battery, can be separated from the other components of the on-board electrical system, or from a high-voltage system of the vehicle, via switching devices also known as main isolating elements. All components integrated into the on-board electrical system, which may be implemented as a high-voltage on-board electrical system, can thus be separated from the energy storage device by opening the main isolating elements.

[0003] With closed main separators, the components can be supplied via the energy storage device, meaning the on-board electrical system is active and the voltage from the energy storage device is present at all components. With an active on-board electrical system, the voltage from the energy storage device is also present at components whose function is not currently required during operation of a motor vehicle including the on-board electrical system.

[0004] This has the disadvantage that the components are constantly stressed by the voltage of the energy storage device, even though their function is only required temporarily and not permanently. Various types of automotive electrical systems are known from the state of the art.

[0005] DE 10 2012 206 932 A1 describes a motor vehicle electrical system with at least two sub-networks that are interconnected by means of a DC-DC converter and a bypass switch. A consumer with at least two different power requirements is connected to a first of the sub-networks, and the motor vehicle electrical system is configured to feed a voltage from the second sub-network into the first sub-network only via the DC-DC converter in a first operating mode with the bypass switch open when a first power requirement is present from the at least one consumer, and to feed power from the second sub-network into the first sub-network via the bypass switch in a second operating mode with the bypass switch closed when a second, higher power requirement is present from the at least one consumer.

[0006] DE 10 2018 202 590 A1 discloses a switching device for a high-voltage electrical system of a motor vehicle, which has at least two sub-networks. The switching device comprises at least one current measuring unit, a switching element, and a control unit. The switching device is designed to safely disconnect a high-voltage battery from other high-voltage consumers in the event of a short circuit in the high-voltage electrical system.

[0007] DE 10 2014 201 345 A1 discloses an on-board electrical system for a vehicle with a low-voltage sub-network for at least one low-voltage consumer and with a high-voltage sub-network for at least one high-voltage consumer and an electric generator. The high-voltage sub-network further comprises a battery configured to generate a high voltage and output it to the high-voltage sub-network. The low-voltage sub-network is connected to the energy storage device via a coupling unit, which can selectively connect battery units of the energy storage device to the low-voltage sub-network. This ensures that the battery units of the energy storage device have as uniform a charge level as possible.

[0008] DE 10 2019 129 785 A1 relates to an integrated energy supply system for an electrically powered vehicle. The energy supply system comprises two high-voltage sub-grids, each with a DC voltage source and a DC-DC converter. Two electric motors can be operated via the DC voltage source. Each of the motors is connected to the respective energy storage device via a switching device. Switching elements provided in the on-board network enable the various components to be interconnected in a granular manner. The individual motors, the individual DC-DC converters, a low-voltage emergency power supply, another high-voltage DC-DC converter, and an inverter connected to a charging port are each assigned individual isolating devices, via which these components can be individually disconnected.The switching elements can thus be used to switch on or off the components required in a driving mode, a charging mode and / or a low-voltage on-board power supply mode.

[0009] DE 10 2018 203 039 A1 discloses an on-board electrical system for a motor vehicle, comprising a traction accumulator, two traction sub-electrical systems, and at least one further sub-electrical system. The traction sub-electrical systems can each be separated from the traction accumulator used as an energy storage device via a switching device. The further sub-electrical system contains an AC charging port, an AC charging unit, a DC-DC converter, a heating unit, and an electric air conditioning compressor. These components are connected together in a sub-electrical system and can be separated from the energy storage device via the switching device. The different sub-electrical systems can be connected or disconnected in different operating modes of the motor vehicle.

[0010] DE 10 2019 007 030 A1 describes an electrical system for an at least partially electrically powered motor vehicle. The electrical system comprises a control device, a high-voltage energy storage device, and several components operable via the high-voltage energy storage device. Several switching devices are arranged between the high-voltage energy storage device and the components, via which the components can be connected to the energy storage device or operated depending on the operating state. The components described in this context are a DC charger, two traction electric motors, and low-voltage components of a 48-volt electrical system. Furthermore, a 12-volt electrical system 42 is provided as a separate electrical system, which is connected to the 48-volt electrical system via a DC-DC converter. The components are each assigned to different sub-systems, each having a different voltage level.The switching devices can be used to operate different sub-networks in different operating states of the motor vehicle, namely driving mode, AC charging, DC charging, preconditioning and service operating mode.

[0011] The invention is based on the object of providing an improved on-board electrical system for a motor vehicle, which in particular reduces the loads on unnecessary components of the on-board electrical system.

[0012] To achieve this object, in an on-board power supply system of the type mentioned at the outset, it is provided according to the invention that the components of different sub-networks are each assigned to at least one different operating state of the motor vehicle, wherein components which are assigned to a heating operating state, an air conditioning operating state, a chassis control operating state and / or an exhaust gas treatment operating state are each arranged in a separate sub-network, wherein each of the sub-networks is separable from the energy storage device via at least one switching device and the control device is designed to control the switching devices as a function of operating state information which describes at least one current operating state of the motor vehicle in such a way that the sub-networks which comprise a component assigned to the current operating state are connected to the energy storage device, and the sub-networks,which do not include any component assigned to the current operating state, are separated from the energy storage device.

[0013] This advantageously makes it possible for only those components to be connected to the energy storage device that are actually required in the current operating state of the motor vehicle. Components that are not required in the current operating state can be disconnected from the energy storage device by the switching devices, so that only those components that are actually used in the current operating state of the motor vehicle are connected to the energy storage device. Dividing the components into different sub-networks makes it possible to connect individual components or groups of components that are operated in a specific operating state of the motor vehicle, individually or as a group, to the energy storage device via the switching device assigned to the respective sub-network.This can advantageously reduce the operating hours of the individual components, since these are generally not used in all operating conditions of the vehicle, i.e. not permanently.

[0014] Furthermore, the on-board electrical system according to the invention has the advantage that the isolation of the components or the respective sub-networks from the energy storage device by the switching devices can result in a lower load, in particular on the input circuitry of the respective components, since the components arranged in the sub-networks are not permanently connected to the energy storage device. In particular, it is possible for the components to be completely or at least partially de-energized by the isolation of the respective sub-network. Furthermore, the respective components or individual circuit components of the respective components in the isolated sub-networks do not affect the part of the on-board electrical system that is in operation.

[0015] The total capacitance available, for example, for filter capacitors such as Y capacitors in component filter systems may be limited for safety reasons in a motor vehicle's on-board electrical system. This total capacitance must be distributed among all components in the vehicle connected to the energy storage system. To achieve the desired filtering properties of a component filter system, for example, designed as an EMC filter (EMC = electromagnetic compatibility), the use of additional inductors in the filter system may therefore be necessary, taking into account the permissible total capacitance. However, these inductors require more space than comparable capacitances and are also generally more expensive and heavier.

[0016] By dividing the components into two or more sub-networks that can be separately connected or disconnected, the effect can be exploited that, depending on the operating state of the vehicle, certain combinations of components are not in operation simultaneously. By excluding certain combinations of components connected to the energy storage system, the total capacity budget for Y capacitors can be distributed among a smaller number of components that can be operated simultaneously, allowing larger capacitances and thus smaller inductances to be used in the filter devices of the components to achieve the desired filtering effect. This advantageously enables a cost-reduced, space-saving, and weight-reduced design of filter devices in the components.

[0017] The components in the at least two sub-networks connected to the energy storage device via the switching devices can thus each have a filter device with at least one Y-capacitor each. Since a permissible total capacitance for the Y-capacitors in the vehicle electrical system only extends to the subset of the maximum number of sub-networks or components in operation at the same time, the total capacitance of the Y-capacitors in all components of the vehicle electrical system can advantageously be made larger than in a vehicle electrical system in which all components are connected to the energy storage device simultaneously or permanently. Because only a subset of the sub-networks or components is connected to the energy storage device in each of the operating states of the motor vehicle, the permissible total capacitance can nevertheless advantageously be maintained in each of the operating states.

[0018] The filter device can, in particular, be a filter device on the input side of the component. The input of the component is understood to be the side of the component where the voltage generated by the energy storage device drops. However, this does not preclude the possibility that the component, for example, a bidirectional DC-DC converter or an electrical machine in generator mode, can also deliver power to the energy storage device.

[0019] The operating state information can be determined by the control device itself or it can be transmitted to it by another control unit, for example, a control unit of a motor vehicle comprising the on-board electrical system. The operating states can advantageously be selected in particular such that functional groups or clusters are formed from components that are assigned to specific functions or operating states of the motor vehicle. The on-board electrical system of the motor vehicle can, in particular, be a high-voltage electrical system, in which electromagnetic interference can arise from switching operations, for example, of a traction converter or other power electronics elements.

[0020] According to the invention, it can be provided that at least one input of the components can be switched off by the switching devices. In this way, in particular, a filter device present on the input side of the component, such as an EMC filter for filtering interference occurring in the vehicle electrical system, is completely disconnected from the energy storage device or separated from the rest of the vehicle electrical system if the component or components of the sub-network are not required in the current operating state. This advantageously reduces the total capacitance generated by the connected filter devices, which is still connected to the energy storage device in the operating state.

[0021] According to the invention, the switching devices can be designed as devices separate from the components. The switching devices can be connected, for example, via electrical connecting means such as cables or busbars to the input of the component or the inputs of several components of a sub-network and / or the energy storage device. The switching devices can be arranged, for example, in or on a housing of the energy storage device.

[0022] According to the invention, the switching devices can each comprise at least one switching element, in particular a semiconductor switch and / or a contactor. A transistor, for example, can be used as the semiconductor switch. This enables the switching devices to have a sufficiently good current-carrying capacity when the switching elements are closed, so that the components arranged in the respective subnetworks can be reliably supplied with current.

[0023] According to the invention, it can be provided that the energy storage device has two poles, wherein the connections to both poles can be interrupted by the switching devices for each sub-network, or wherein the connection to one of the poles can be interrupted by the switching devices for at least two of the sub-networks, and the connection between the other pole and the at least two sub-networks can be interrupted by a further switching device.

[0024] In this case, for example, a switching element can be arranged between the two poles of the energy storage device and the sub-network in the connections between each sub-network and the energy storage device, so that the connections to a positive pole and a negative pole can be separated individually for each sub-network. It is also possible that for each of the sub-networks or for at least two of the sub-networks, a switching device is provided only in the connection to one of the poles, for example the positive pole, with a further common switching device being provided for separating the connections to the other pole of the energy storage device. The individual sub-networks can thus be separated separately by opening the connection to one of the poles using the switching device assigned to the respective sub-network, whereby a complete separation of all components is possible by additionally opening the further switching device. The further switching device orThe switching element of the additional switching device can also be referred to as the main isolating element. Even when using a switching element, one or two main isolating elements can be provided in each connection between the poles of the energy storage device and each of the sub-grids, which can additionally isolate one or both poles of the energy storage device from the switching devices assigned to the respective sub-grids.

[0025] According to the invention, it can be provided that the control device is configured to control the switching devices in response to the operating state information when there are multiple current operating states such that the sub-networks that comprise a component assigned to at least one of the multiple current operating states are connected to the energy storage device, and the sub-networks that do not comprise a component assigned to at least one of the multiple current operating states are disconnected from the energy storage device. When there are multiple current operating states, e.g., when driving and simultaneously operating the air conditioning or the like, it is sufficient if the at least one component of a sub-network is assigned to one of the multiple current operating states in order to establish a connection between the energy storage device and the corresponding component or its sub-network.Accordingly, if there are several current operating states, those components or those sub-networks that are not assigned to any of the current operating states, i.e. the components that are not required in the current operating states of the vehicle, are disconnected from the energy storage system.

[0026] In a preferred embodiment of the invention, components assigned to a driving mode, a direct current charging mode, an alternating current charging mode, and / or a low-voltage vehicle electrical system supply mode can each be arranged in a separate subnetwork. Accordingly, the operating state information can describe, as operating states, a driving mode, a direct current charging mode, an alternating current charging mode, and / or a supply mode of a low-voltage vehicle electrical system.

[0027] According to the invention, it can be provided that at least one component designed as a traction electric motor is assigned to the driving operating state, at least one component designed as a direct current charging device is assigned to the direct current charging operating state, at least one component designed as an alternating current charging device is assigned to the alternating current charging operating state, at least one component designed as a direct current converter is assigned to the low-voltage vehicle electrical system supply operating state, at least one component designed as a heater is assigned to the heating operating state, at least one component designed as an air conditioning device is assigned to the air conditioning operating state, a component designed as a chassis device is assigned to the chassis control operating state and / or a component designed as an exhaust gas treatment device is assigned to the exhaust gas treatment operating state.

[0028] Such a division of components enables the creation of different sub-networks or the assignment of components to operating states such that all sub-networks are not operated simultaneously. For example, charging the energy storage device does not require both an AC charging device and a DC charging device. Furthermore, one or more traction electric motors of the on-board electrical system, or of a motor vehicle with the on-board electrical system, are not required simultaneously with a DC charging device and / or an AC charging device, since an electric vehicle is generally charged while stationary.A component designed as a DC-DC converter, which is designed to supply a low-voltage electrical system in the low-voltage electrical system supply operating state, can, for example, convert the voltage of the energy storage device to a voltage level of, for example, 12 V, 24 V, or 48 V. Depending on the voltage level, the low-voltage electrical system can also be referred to as a medium-voltage electrical system (MV electrical system).

[0029] According to the invention, the vehicle electrical system can be a high-voltage vehicle electrical system, in particular with a voltage of 60 V or higher. For example, the voltage of the high-voltage vehicle electrical system can be between 200 V and 1500 V. The energy storage device can be, for example, a traction energy storage device such as a traction battery, by means of which, for example, at least one component of the vehicle electrical system designed as a traction electric motor can be operated.

[0030] A motor vehicle according to the invention is intended to include an on-board power supply according to the invention. All statements regarding the on-board power supply according to the invention also apply accordingly to the motor vehicle according to the invention.

[0031] For a method according to the invention for operating an on-board electrical system, it is provided that the on-board electrical system comprises a control device, an energy storage device and a plurality of components operable via the energy storage device, wherein the on-board electrical system is divided into at least two sub-networks and the sub-networks each comprise at least one of the components, wherein the components of different sub-networks are each assigned to at least one different operating state of the motor vehicle, wherein components which are assigned to a heating operating state, an air conditioning operating state, a chassis control operating state and / or an exhaust gas treatment operating state are each arranged in a separate sub-network, wherein each of the sub-networks is separable from the energy storage device via at least one switching device,wherein the control device controls the switching devices in dependence on operating state information describing at least one current operating state of the motor vehicle in such a way that the sub-networks which comprise a component assigned to the current operating state are connected to the energy storage device, and the sub-networks which do not comprise a component assigned to the current operating state are disconnected from the energy storage device.

[0032] According to the invention, it can be provided that the control device controls the switching devices in a plurality of current operating states depending on the operating state information in such a way that the sub-networks which comprise a component assigned to at least one of the plurality of current operating states are connected to the energy store, and the sub-networks which do not comprise a component assigned to at least one of the plurality of current operating states are disconnected from the energy store.

[0033] All advantages and embodiments described above in relation to the on-board network according to the invention or the motor vehicle according to the invention also apply accordingly to the method according to the invention and vice versa.

[0034] Further advantages and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. These are schematic representations and show: Fig. 1 a schematic side view of a motor vehicle according to the invention, Fig. 2 a first embodiment of an on-board network according to the invention, and Fig. 3 a second embodiment of an on-board network according to the invention.

[0035] In Fig. Figure 1 shows a schematic side view of a motor vehicle 1. The motor vehicle 1 comprises an on-board electrical system 2, which includes an energy storage device 3. The on-board electrical system 2 serves to distribute electrical energy drawn from the energy storage device 3 within the motor vehicle 1. The energy storage device 3 is a high-voltage energy storage device, which also serves as a traction energy storage device for the motor vehicle 1. The energy storage device 3 can, for example, be designed as a battery and comprise a plurality of battery cells connected in parallel and / or series.

[0036] In Fig. Figure 2 shows a first exemplary embodiment of the vehicle electrical system 2. In addition to the energy storage device 3, the vehicle electrical system 2 comprises a control device 4 and several components 5-9 operable via the energy storage device 3. In the present exemplary embodiment, the vehicle electrical system 2 is divided into five sub-networks 10-14, each of which comprises one of the components 5-9. The components 5-9 of the sub-networks 10-14 can each be separated from the energy storage device 3 via at least one switching device 15-19.

[0037] The switching devices 15-19 each comprise at least one switching element 20, by means of which the connection of the associated sub-network 10-14 to one pole of the energy storage device 3 or to both poles of the energy storage device 3 can be severed. Furthermore, two main isolating elements 21 are provided, via which the energy storage device 3 can be additionally separated from the switching devices 15-19 and thus from the components 5-9 or the entire sub-networks 10-14. The main isolating elements 21 are also each designed as switching elements. The switching elements 20 of the switching devices 15-19 and / or the main isolating elements 21 can each be designed, for example, as a semiconductor switch, in particular as a transistor, and / or as a contactor. The main isolating elements 21 as well as the switching devices 15-19 and the energy storage device 3 can be arranged in a common housing 22 of the energy storage device 3.

[0038] The switching devices 15-19 can each de-energize the inputs of components 5-9 by opening at least one switching element 20 of the switching devices 15-19. The switching devices 15, 17, and 19 each comprise a switching element 20, so that the connection between a positive pole of the energy storage device 3 and the input of components 5, 7, and 9 can be interrupted. The switching devices 16 and 18 each comprise two switching elements 20, so that the connections between a positive pole and a negative pole of the energy storage device 3 and the input of components 6 and 8 can be interrupted.

[0039] Components 5-9, each arranged in separate sub-networks 10-14, are each assigned to at least one different operating state of motor vehicle 1. Component 5, for example, is designed as an air conditioning device and assigned to an air conditioning state of motor vehicle 1. Component 6 is designed as a traction electric motor and assigned to a driving operating state of motor vehicle 1. Component 7 is designed as a DC-DC converter and assigned to a low-voltage on-board electrical system supply operating state of motor vehicle 1. Component 8 is designed as a DC charging device and assigned to a DC charging operating state of motor vehicle 1. Component 9 is designed as an AC charging device and assigned to an AC charging operating state of motor vehicle 1.

[0040] Depending on the at least one current operating state of the motor vehicle 1, not all of the components 5 - 9 are required at the same time. For example, in a direct current charging operating state in which the energy storage device 3 is charged via a direct current source, only component 7 designed as a DC-DC converter for supplying a low-voltage on-board electrical system and component 8 designed as a direct current charging device are required. Since the motor vehicle is not moving in a charging operating state, component 6 designed as a traction electric motor, for example, is not required there. It is also possible that component 5 designed as an air conditioning device, for example, is not required in the charging operating state. Furthermore, component 9 designed as an alternating current charging device is likewise not required in the direct current charging operating state.

[0041] As a further example, a driving mode of motor vehicle 1 is required, in which component 8 configured as a traction electric motor is required. Furthermore, in addition to the driving mode for operating low-voltage components, a low-voltage vehicle electrical system supply mode may exist, for which component 7 configured as a DC-DC converter is operated. Additionally, an air conditioning mode may exist, in which component 5 configured as an air conditioning device is used. Since charging the motor vehicle while driving is not possible, components 8 and 9 configured as charging devices are not required, so they can be switched off by disconnecting sub-networks 13 and 14 and de-energized at least on the input side.

[0042] Another example is stationary air conditioning of motor vehicle 1, which requires component 8 configured as a traction electric motor. In addition, the charging operating state may be present, for example, when the motor vehicle is being charged while stationary, and / or the low-voltage vehicle electrical system supply operating state may be present, for example, when a multimedia device of the motor vehicle operated via the low-voltage vehicle electrical system is being used.

[0043] In addition to these examples, other operating states or combinations of operating states are also possible, in each of which only a portion of components 5-9 are required. The unused components 5-9 or sub-networks 10 to 14 are disconnected from the energy storage device via switching devices 15 to 19 and de-energized at least on the input side. The allocation of the available components to the possible operating states, as well as the operating states considered in each case, can depend in particular on the type and / or design of motor vehicle 1.

[0044] The current operating state or states of the motor vehicle are described by operating state information available to the control device 4. The control device 4 can determine the operating state information itself, or it can be transmitted to the control device 4 by another control unit (not shown) of the motor vehicle 1. The control device 4 controls the switching devices 15-19 in a method for operating the on-board electrical system 2 as a function of the operating state information in order to disconnect the components not required for the at least one current operating state from the energy storage device 3.The switching devices 15-19 are controlled by the control device 4 such that the sub-networks 10-14 that comprise a component 5-9 assigned to the current operating state are connected to the energy storage device 3, and the sub-networks 10-14 that do not comprise a component 5-9 assigned to the current operating state are disconnected from the energy storage device 3. The connections between the control device 4 and the switching devices 15-19 are shown in FIG. Fig. 2 not shown for the sake of clarity.

[0045] In the case of operating state information that describes more than one current operating state, e.g., a driving operating state of the motor vehicle 1 and an air conditioning operating state of the motor vehicle 1, the components 5-9 that are assigned to at least one of the operating states are operated by connecting the respective subnetworks 10-14 to the energy storage device 3. The components 5-9 that are not assigned to any of the current operating states are disconnected from the energy storage device 3 by appropriately controlling the switching elements 15-19.

[0046] The present representation of components 5 - 9 and the sub-networks 10 - 14 in the on-board electrical system 2 is not exhaustive. The on-board electrical system 2 can, in particular, comprise further components, e.g., components designed as heating elements, which are assigned to a heating operating state of the motor vehicle, as chassis devices, which are assigned to a chassis control operating state, and / or as exhaust gas treatment devices, which are assigned to an exhaust gas treatment operating state. The components can, in particular, be arranged in one or more sub-networks, wherein the sub-network or sub-networks are each connected to the energy storage device 3 via a switching device, so that the further components can also be connected to or disconnected from the energy storage device 3 depending on the operating state information.A chassis control operating state may, for example, exist when an adaptive chassis control is activated, and an exhaust gas treatment operating state may, for example, exist when the motor vehicle 1 comprises an internal combustion engine and this is in operation.

[0047] The vehicle electrical system 2 can, for example, be a high-voltage vehicle electrical system, in particular with a direct voltage of 60 V or higher, wherein the high voltage in the vehicle electrical system 2 is provided by the energy storage device 3. The voltage of the high-voltage vehicle electrical system can, for example, be 200 V, 400 V, 800 V, 1000 V, or 1500 V. A component 7 designed as a DC-DC converter can, for example, serve to supply a low-voltage vehicle electrical system with a voltage between 12 V and 48 V, which can also be referred to as a medium-voltage vehicle electrical system.

[0048] The main isolating elements 21 allow the energy storage device 3 to be separated from all sub-grids 10-14, e.g., when the motor vehicle 1 is switched off or deactivated. For some of the components, such as component 6 configured as a traction electric motor and / or component 8 configured as a direct current charging device, two switching elements 20 may be provided for each of the switching devices 16 and 18 for safety reasons, so that both a connection to a positive pole of the energy storage device 3 and a negative pole of the energy storage device 3 can be separated separately. For other components, in this case components 5, 7, 9, it may be sufficient if only the connection to the positive pole of the energy storage device 3 is separated by the single switching element 20.

[0049] The switching devices 15-19 also de-energize the inputs of components 5-9, so that the voltage of energy storage device 3 no longer drops across the inputs of components 5-9. This reduces the operating hours of the individual components 5-9, since they are only connected to the energy storage device 3 on the input side when the current operating state of motor vehicle 1 requires it.

[0050] By dividing the components 5 - 9 into the individual sub-networks 10 - 14 or by assigning the components 5 - 9 to the individual operating states of the motor vehicle 1, it is advantageously achieved that in the various operating states of the motor vehicle 1, the number of components 5 - 9 in operation at the same time is lower than the total number of components 5 - 9 of the on-board electrical system 2. In this way, a total capacitance, which is provided for the filter devices arranged, for example, on the input side in the components 5 - 9, can be distributed among a subset of the components 5 - 9. This increases the proportion of the total capacitance available per component. This makes it possible to use larger capacitances in the filter devices, which are designed, for example, as EMC filters, and to correspondingly reduce the inductances in the filter devices.This advantageously reduces the installation space requirements as well as the costs and weight of the filter devices in components 5 - 9.

[0051] In Fig.3 shows a second exemplary embodiment of an on-board electrical system 2. This corresponds to the first exemplary embodiment of the on-board electrical system 2 with regard to the energy storage device 3, the control device 4, the components 5-9, and the sub-networks 10-14. One difference is that the on-board electrical system 2 has only a single main isolating element 21, which can separate the negative pole of the energy storage device 3 from all sub-networks 10-14. Since a switching element 20 is provided for each of the sub-networks 10-14 as a component of the switching devices 15-19, a main isolating element, which separates the positive pole of the energy storage device 3 from the sub-networks 10-14 or the components 5-9, can advantageously be dispensed with, since the separation can also be achieved by the respective switching elements 20 of the switching device 15-19 integrated into the positive path.

Claims

[1] On-board electrical system (2) for a motor vehicle (1) comprising a control device (4), an energy storage device (3) and a plurality of components (5-9) operable via the energy storage device (3), wherein the on-board electrical system (2) is divided into at least two sub-networks (10-14) and the sub-networks (10-14) each comprise at least one of the components (5-9), wherein the components (5-9) of different sub-networks (10-14) are each assigned to at least one different operating state of the motor vehicle (1), wherein components (5-9) assigned to a heating operating state, an air conditioning operating state, a chassis control operating state and / or an exhaust gas treatment operating state are each arranged in a separate sub-network (10-14), wherein each of the sub-networks (10-14) is separable from the energy storage device (3) via at least one switching device (15-19), and the control device (4) is designed toto control the switching devices (15 - 19) in dependence on operating state information which describes at least one current operating state of the motor vehicle (1) in such a way that the sub-networks (10 - 14) which comprise a component (5 - 9) assigned to the current operating state are connected to the energy store (3), and the sub-networks (10 - 14) which do not comprise a component (5 - 9) assigned to the current operating state are disconnected from the energy store (3). [2] On-board network (2) according to claim 1, characterized by that at least one input of the components (5 - 9) can be switched off by the switching devices (15 - 19). [3] On-board network (2) according to claim 2, characterized by that the switching devices (15 - 19) are designed as separate devices from the components (5 - 9). [4] On-board network (2) according to one of the preceding claims, characterized bythat the switching devices (15 - 19) each comprise at least one switching element (20). [5] On-board network (2) according to one of the preceding claims, characterized by that the energy store (3) has two poles, wherein the connections to both poles can be interrupted by the switching devices (15 - 19) for each sub-network (10 - 14) or wherein the connection to one of the poles can be interrupted by the switching devices (15 - 19) for at least two of the sub-networks (10 - 14) and the connection between the other pole and the at least two sub-networks (10 - 14) can be interrupted by a further switching device. [6] On-board network (2) according to one of the preceding claims, characterized byin that the control device (4) is designed to control the switching devices (15 - 19) in the case of a plurality of current operating states as a function of the operating state information in such a way that the sub-networks (10 - 14) which comprise a component (5 - 9) assigned to at least one of the plurality of current operating states are connected to the energy store (3), and the sub-networks (10 - 14) which do not comprise a component (5 - 9) assigned to at least one of the plurality of current operating states are separated from the energy store (3). [7] On-board network (2) according to one of the preceding claims, characterized by that components (5 - 9) which are assigned to a driving operating state, a direct current charging operating state, an alternating current charging operating state and / or a low-voltage on-board network supply operating state are each arranged in a separate sub-network (10 - 14). [8] On-board network (2) according to one of the preceding claims, characterized by that at least one component designed as a traction electric motor (6) is assigned to the driving operating state, at least one component designed as a direct current charging device (8) is assigned to the direct current charging operating state, at least one component designed as an alternating current charging device (9) is assigned to the alternating current charging operating state, at least one component designed as a direct current converter (7) is assigned to the low-voltage on-board network supply operating state, at least one component designed as a heater is assigned to the heating operating state, at least one component designed as an air conditioning device (5) is assigned to the air conditioning operating state, a component designed as a chassis device is assigned to the chassis control operating state, and / or a component designed as an exhaust gas treatment device is assigned to the exhaust gas treatment operating state. [9] On-board network (2) according to one of the preceding claims, characterized by that the vehicle electrical system (2) is a high-voltage vehicle electrical system. [10] Motor vehicle (1) comprising an on-board network (2) according to one of the preceding claims. [11] Method for operating an on-board electrical system (2) of a motor vehicle (1), wherein the on-board electrical system (2) comprises a control device (4), an energy storage device (3) and a plurality of components (5-9) operable via the energy storage device (3), wherein the on-board electrical system (2) is divided into at least two sub-networks (10-14) and the sub-networks (10-14) each comprise at least one of the components (5-9), wherein the components (5-9) of different sub-networks (10-14) are each assigned to at least one different operating state of the motor vehicle (1), wherein components (5-9) which are assigned to a heating operating state, an air conditioning operating state, a chassis control operating state and / or an exhaust gas treatment operating state are each arranged in a separate sub-network (10-14), wherein each of the sub-networks (10-14) is connected to the Energy storage (3) is separable,wherein the control device (4) controls the switching devices (15-19) as a function of operating state information describing at least one current operating state of the motor vehicle (1) in such a way that the sub-networks (10-14) which comprise a component (5-9) assigned to the current operating state are connected to the energy store (3), and the sub-networks (10-14) which do not comprise a component (5-9) assigned to the current operating state are disconnected from the energy store (3). [12] Method according to claim 11, characterized byin that the control device (4) controls the switching devices (15 - 19) in the case of a plurality of current operating states as a function of the operating state information in such a way that the sub-networks (10 - 14) which comprise a component (5 - 9) assigned to at least one of the plurality of current operating states are connected to the energy store (3), and the sub-networks (10 - 14) which do not comprise a component (5 - 9) assigned to at least one of the plurality of current operating states are separated from the energy store (3).

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