Electrical system for a motor vehicle that is at least partially electrically powered, motor vehicle and process

Abstract

The invention relates to an electrical system (12) for an at least partially electrically powered motor vehicle (10), comprising at least one primary energy circuit (14) for providing electrical energy to at least one electrical consumer (18) of the motor vehicle (10), a secondary energy circuit (14) for providing electrical energy to an electrical consumer (20) designed redundantly with respect to the electrical consumer (18), and a separating element (38) for separating the primary energy circuit (14) from the secondary energy circuit (16), characterized in that the separating element (38) is designed such that, in the event of a fault in the primary energy circuit (14), at least some electrical energy can be transferred from the secondary energy circuit (16) to the primary energy circuit (14). The invention further relates to a motor vehicle (10) and a method.

Description

[0001] The invention relates to an electrical system for an at least partially electrically powered motor vehicle, comprising at least one primary power circuit for providing electrical energy to at least one electrical consumer of the motor vehicle, a secondary power circuit for providing electrical energy to an electrical consumer configured redundantly to the electrical consumer, and a separating element for separating the primary power circuit from the secondary power circuit. Furthermore, the invention relates to a motor vehicle having an electrical system and a method for operating an electrical system.

[0002] A redundant power supply for so-called ASIL-D vehicle functions is currently divided into two independent on-board power systems. The basis of the on-board power systems is the connection between the channels of the independent elements or element clusters, energy sources, energy transmission / separation, and energy management. In the event of an initial fault in one of the two on-board power system channels, the connection between the two on-board power systems is always severed to achieve maximum independence. For example, the primary power circuit is implemented with an active source, for example a so-called converter, and a passive source, for example an energy storage device, while the secondary power circuit is implemented with only a passive source, in particular an energy storage device. The power supply includes electronically separable power paths to the consumers.

[0003] The immediate disconnection of the on-board power systems requires a higher degree of redundancy in the primary energy sources for certain fault scenarios. If, for example, the DC-DC converter fails in the primary power circuit, the remaining passive storage must be designed to maintain the entire load in the primary power circuit until the electronic shutdown of the disconnectable power paths in the event of a fault, and the resulting reduced load until the completion of a so-called minimal-risk maneuver. The advantage is a simple design of the connecting element between the on-board power systems, for example, in the form of a DC-DC converter or a circuit breaker, which only needs to cause a disconnection of the on-board power system.

[0004] DE 10 2016 007 988 A1 relates to an on-board electrical system for a motor vehicle, having an on-board electrical system branch with a first normal operating voltage, having a second on-board electrical system branch with a second normal operating voltage and having a charging circuit device coupled to the first and second on-board electrical system branches for supplying the second on-board electrical system branch with electrical energy from the first on-board electrical system branch, wherein the two on-board electrical system branches are coupled in the charging circuit device and by a voltage converter and by a switching device connected in parallel to the voltage converter, and wherein the second normal operating voltage is greater than the first normal operating voltage and the switching device is designed, on the one hand, in a normal operation in which a first actual operating voltage of the first on-board electrical system branch is lower than a second actual operating voltage of the second on-board electrical system branch,to block a current flow from the second vehicle electrical system branch into the first vehicle electrical system branch through the switching device, and on the other hand is designed to allow a current flow from the first vehicle electrical system branch into the second vehicle electrical system branch through the switching device when the second actual operating voltage is lower than the first actual operating voltage in order to provide an improved fail-safe power supply in the motor vehicle.

[0005] The object of the present invention is to provide an electrical on-board network, a motor vehicle and a method by means of which electrical energy can be provided in a simple manner for an electrical consumer in the electrical on-board network.

[0006] This object is achieved by an electrical system, a motor vehicle, and a method according to the independent patent claims. Advantageous embodiments are specified in the subclaims.

[0007] One aspect of the invention relates to an electrical system for an at least partially electrically operated motor vehicle, having at least one primary energy circuit for providing electrical energy for at least one electrical consumer of the motor vehicle, having a secondary energy circuit for providing electrical energy for an electrical consumer designed to be redundant with respect to the electrical consumer, and having a separating element for separating the primary energy circuit from the secondary energy circuit.

[0008] It is provided that the isolating element is designed in such a way that in the event of a fault in the primary energy circuit, at least some electrical energy can be transferred from the secondary energy circuit to the primary energy circuit.

[0009] This makes it possible to provide electrical energy to the electrical consumer even in the event of a fault.

[0010] The electrical load can, in particular, be an emergency device capable of performing a minimum-risk maneuver. For example, this could be a steering device or braking device. This makes it possible, in particular, to design smaller energy sources in the primary power circuit, since electrical energy can be provided by the second secondary power circuit even in the event of a fault.

[0011] In particular, instead of directly disconnecting the primary power circuit and the secondary power circuit in the event of a fault, the disconnection is only initiated via the disconnecting element when a current or energy transfer threshold is reached. The energy transfer becomes availability-relevant, meaning that in addition to the safe state of disconnection, it also has the safe state of energy transfer. In the primary power circuit, the passive source can thus be significantly reduced or even eliminated entirely, provided a converter element can carry the entire system power. The active source must be able to support the load for the minimum-risk maneuver from the secondary power circuit up to the corresponding energy threshold.In the secondary energy circuit, the passive source must, in addition to the load profile of the secondary energy circuit during the minimum risk maneuver, also provide the power flow of the primary energy circuit that occurs due to a fault in the active source. Alternatively to eliminating the primary energy storage, the energy reserve of the storage can also be reduced and used to eliminate redundancies in the active source, for example, converter output stages or control. It is essential that the power that occurs in the event of a fault is fed from the secondary energy circuit via the isolating element or connecting element by the secondary energy source.

[0012] According to an advantageous embodiment, if the energy in the primary energy circuit falls below a predetermined threshold, the isolating element disconnects the connection between the primary energy circuit and the secondary energy circuit. In particular, it can be provided that, for example, the minimum risk maneuver is performed via the secondary energy circuit when the predetermined threshold is exceeded. This prevents electrical energy from flowing into the primary energy circuit that is no longer sufficient to power the electrical consumer. In particular, it is thus possible to ensure that the redundantly designed electrical consumer can be controlled accordingly via the secondary energy source or the secondary energy circuit. This can increase the safety of the motor vehicle.

[0013] It is also advantageous if the failure of a DC-DC converter occurs in the primary power circuit. This allows the active source element, in particular, to be identified as the fault. Should such a failure occur, the minimum risk maneuver can still be reliably implemented via the primary power circuit.

[0014] It has also proven advantageous if, in the event of a detected fault, the on-board electrical system is configured to perform an emergency maneuver for the vehicle. This emergency maneuver can be performed, in particular, as a so-called minimum-risk maneuver. This is a maneuver that allows the vehicle to be parked safely. This can increase vehicle safety.

[0015] In a further advantageous embodiment, the on-board electrical system includes an electronic computing device designed to control the isolating element. In particular, the electronic computing device can, for example, detect corresponding voltage levels in the primary power circuit and the secondary power circuit. Depending on the voltage levels, the isolating element can thus allow a flow of energy from the secondary power circuit to the primary power circuit or even perform a separation. This allows the on-board electrical system to operate reliably.

[0016] It is also advantageous if the redundant consumer is designed with reduced functionality compared to the consumer. For example, a braking device or a steering device can be provided as a consumer in the primary power circuit and operated accordingly using electrical energy. The redundant consumer can be designed with reduced functionality, for example, without steering capability and only with braking capability. Thus, the redundant consumer is designed for a minimum-risk maneuver, while the consumer can be designed for normal driving, for example. This allows the on-board electrical system to be operated with fewer components while still being safe.

[0017] A further advantageous embodiment provides for additional non-safety-critical loads to be incorporated into the primary power circuit. For example, corresponding loads, such as air conditioning, infotainment, or the like, can be supplied with electrical energy primarily via a power circuit.

[0018] It is also advantageous if only safety-critical consumers are incorporated in the secondary power circuit. In particular, only one safety-critical consumer is incorporated in the secondary power circuit, for example, to ensure safe parking of the vehicle. This allows the on-board electrical system to be provided with fewer components.

[0019] A further aspect of the invention relates to a motor vehicle with at least one electrical system according to the preceding aspect. The motor vehicle is designed as an at least partially electrically powered motor vehicle or as a fully electrically powered motor vehicle.

[0020] Furthermore, the invention also relates to a method for operating an on-board electrical system according to the preceding aspect. Electrical energy is provided for a consumer by the primary power circuit. The redundant secondary power circuit is provided. In the event of a fault in the primary power circuit, electrical energy is provided from the secondary power circuit via the isolating element for the primary power circuit.

[0021] Advantageous embodiments of the electrical system are considered advantageous embodiments of the motor vehicle and the method. The electrical system and the motor vehicle have physical features that enable the corresponding method steps to be carried out.

[0022] Further features of the invention emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combination, but also in other combinations or on their own.

[0023] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawings. They show: Fig. 1 is a schematic block diagram according to a first embodiment of a motor vehicle with an embodiment of an electrical system; and Fig. 2 shows a further schematic block diagram according to an embodiment of a motor vehicle with an embodiment of an electrical system.

[0024] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0025] Fig. 1 shows a schematic block diagram of an embodiment of a purely schematically illustrated motor vehicle 10 with a corresponding electrical system 12. The electrical system 12 has a primary power circuit 14 and a secondary power circuit 16. For example, an electrical consumer 18 is formed in the primary power circuit 14, and an electrical consumer 20 designed to be redundant with the electrical consumer 18 is formed in the secondary power circuit 16.

[0026] In the present embodiment, the primary energy circuit 14 has a passive energy source 22, for example in the form of a high-voltage battery. Furthermore, the primary energy circuit 14 has a first DC-DC converter 24 and a second DC-DC converter 26. Furthermore, additional loads 28, 30, and 32 are shown in the primary energy circuit 14. The primary energy circuit 14 also has another passive energy source 34, for example in the form of a lithium-ion battery.

[0027] In addition to the redundantly designed electrical load 20, the secondary power circuit 16 also includes a passive power source 36, for example in the form of a lithium-ion battery. Furthermore, a separating element 38 is provided between the primary power circuit 14 and the secondary power circuit 16.

[0028] In particular, the passive energy source 22, the DC-DC converters 24, 26, the further passive energy source 34, the isolating element 38 and the further passive energy source 36 are designed as so-called ASIL-B components.

[0029] In particular, it is provided that the separating element 38 is designed such that in the event of a fault in the primary energy circuit 14, at least electrical energy can be transferred from the secondary energy circuit 16 to the primary energy circuit 14.

[0030] In particular, it can be provided that if the energy in the primary energy circuit 14 falls below a predetermined threshold value, the isolating element 38 disconnects a connection between the primary energy circuit 14 and the secondary energy circuit 16. Furthermore, the fault can occur, for example, if a DC-DC converter 24, 26 in the primary energy circuit 14 fails. Furthermore, if the fault is detected, the on-board electrical system 12 can be configured to carry out an emergency maneuver for the motor vehicle 10. Furthermore, it can be provided that the on-board electrical system 12 has an electronic computing device 40 configured to control the isolating element 38.

[0031] Furthermore, it can be provided that the redundant consumer 20 is designed with a reduced functionality compared to the consumer 18.

[0032] The Fig. 1 further shows that additional non-safety-critical consumers 30, 32 are formed in the primary energy circuit 14. Furthermore, the Fig. 1, that only safety-critical consumers 20 are formed in the secondary energy circuit 16.

[0033] In particular, the Fig. 1, that instead of directly disconnecting the power circuits 14, 16 in the event of a fault, the disconnection is only brought about via the disconnecting element 38 when a current or energy transfer threshold is reached. The energy transfer becomes availability-relevant, i.e., in addition to the safe state of disconnecting, it also has the safe state of transferring energy. In the primary power circuit 14, the passive source 22 can be significantly reduced or even eliminated entirely provided the DC-DC converters 24, 26 can carry the entire system line. The active source must be able to carry the load in the minimum risk maneuver from the secondary power circuit 16 up to the energy threshold. In the secondary power circuit 16, the passive source 36 must, in addition to the load profile of the secondary power circuit 16, also provide the power flow of the primary power circuit 14 that occurs due to a fault in the active source.As an alternative to eliminating the primary storage, the storage's energy reserve can also be reduced and used to eliminate redundancies in the active source, such as the DC-DC converter output stages or their control systems. It is essential that the power generated during the initial fault is supplied from the secondary energy circuit 16 via the isolating element 38 by the secondary energy source.

[0034] Fig. 2 shows a further embodiment of a motor vehicle 10 with the electrical system 12. Compared to the Fig. In the embodiment shown in Figure 1, for example, the primary power circuit 14 has yet another electrical load 42. Furthermore, the secondary power circuit 16 has further electrical loads 44, 46.

[0035] Particularly in a vehicle with high load, a fault may occur in the DC-DC converter 24, 26, for example, a failure in the output stage. The power and consumption in the primary power circuit 14 are supplied via the secondary power circuit 16 and the remaining output stage for the time interval T. After a time t, the electronic fuses of the primary power circuit 14 are switched off. Subsequently, the power of the consumers is supplied exclusively via the DC-DC converters 24, 26. List of reference symbols 10 motor vehicle 12 electrical system 14 primary energy circuit 16 secondary energy circuit 18 consumers 20 redundantly designed consumers 22 passive energy source 24 DC-DC converters 26 DC-DC converters 28 consumers 30 consumers 32 consumers 34 passive energy source 36 passive energy source 38 Separator 40 electronic computing device 42 consumers 44 consumers 46 consumers QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] DE 10 2016 007 988 A1

[0004]

Claims

[1] Electrical system (12) for an at least partially electrically operated motor vehicle (10), with at least one primary energy circuit (14) for providing electrical energy for at least one electrical consumer (18) of the motor vehicle (10), with a secondary energy circuit (14) for providing electrical energy for an electrical consumer (20) designed redundantly to the electrical consumer (18), and with a separating element (38) for separating the primary energy circuit (14) from the secondary energy circuit (16), characterized by that the separating element (38) is designed such that in the event of a fault in the primary energy circuit (14) at least some electrical energy can be transferred from the secondary energy circuit (16) to the primary energy circuit (14). [2] Electrical system (12) according to claim 1, characterized bythat when a predetermined threshold value for energy in the primary energy circuit (14) is undershot, the separating element (38) separates a connection between the primary energy circuit (14) and the secondary energy circuit (16). [3] Electrical system (12) according to claim 1 or 2, characterized by that the fault occurs in the event of a failure of a DC-DC converter (24, 26) in the primary energy circuit (14). [4] Electrical system (12) according to one of the preceding claims, characterized by that in the event of a detected fault, the electrical system (12) is designed to carry out an emergency maneuver for the motor vehicle (10). [5] Electrical system (12) according to one of the preceding claims, characterized by that the electrical system (12) has an electronic computing device (40) which is designed to control the separating element (38). [6] Electrical system (12) according to one of the preceding claims, characterized by that the redundant consumer (20) is designed with a reduced functionality compared to the consumer (18). [7] Electrical system (12) according to one of the preceding claims, characterized by that additional non-safety-critical consumers (30,32) are formed in the primary energy circuit (14). [8] Electrical system (12) according to one of the preceding claims, characterized by that only safety-critical consumers (20) are formed in the secondary energy circuit (16). [9] Motor vehicle (10) with at least one electrical system (12) according to one of claims 1 to 8. [10] Method for operating an electrical system (12) according to one of claims 1 to 8, comprising the steps: - providing electrical energy to a consumer (18) through the primary energy circuit (14); - providing the redundant secondary power circuit (16); and - In the event of a fault in the primary energy circuit (14), providing electrical energy from the secondary energy circuit (16) via the isolating element (38) for the primary energy circuit (14).

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