High-voltage electrical system for a vehicle, vehicle with a high-voltage electrical system and method for operating a high-voltage electrical system for a vehicle

Abstract

High-voltage electrical system (3) for a vehicle (1), characterized by a high-voltage battery (2), at least one electric drive unit (4, 5), at least one electrical auxiliary unit (6, 7) and a bidirectional low-voltage DC-DC converter (8) which is coupled to a low-voltage vehicle electrical system (9), - wherein a drive potential line pair (10) with a drive separation arrangement (11) is provided for the electrical connection of the at least one electric drive unit (4, 5) to the high-voltage battery (2), and the drive separation arrangement (11) can connect or separate the drive potential line pair (10) and thus the at least one electric drive unit (4, 5) to the high-voltage battery (2), - wherein an auxiliary unit potential line pair (12) with an auxiliary unit disconnection arrangement (13) is provided for the electrical connection of the at least one electrical auxiliary unit (6, 7) and the low-voltage DC-DC converter (8) to the high-voltage battery (2), and the auxiliary unit disconnection arrangement (13) can connect or disconnect the auxiliary unit potential line pair (12) and thus the at least one electrical auxiliary unit (6, 7) and the low-voltage DC-DC converter (8) to the high-voltage battery (2), and - wherein a pre-charging and discharging circuit (24) is provided which comprises a pre-charging and discharging isolating arrangement (25) in a connecting potential line pair (26) coupled to the auxiliary unit potential line pair (12) and the drive potential line pair (10), and a first connection point of the connecting potential line pair (26) to the auxiliary unit potential line pair (12) is located between the auxiliary unit isolating arrangement (13) and the at least one electrical auxiliary unit (6, 7) and the low-voltage DC-DC converter (8), and a second connection point of the connecting potential line pair (26) to the drive potential line pair (10) is located between the drive isolating arrangement (11) and the at least one electrical drive unit (4, 5).

Description

The invention relates to an electrical high-voltage vehicle electrical system for a vehicle, to a vehicle having an electrical high-voltage vehicle electrical system and to a method for operating an electrical high-voltage vehicle electrical system for a vehicle.Vehicles having an electrical high-voltage on-board electrical system are generally known from the prior art.For example, DE 10 2019 008 835 A1 discloses a vehicle having an electrical high-voltage on-board electrical system which is divided into two subareas, the first subarea being arranged in a first installation space of the vehicle and the second subarea being arranged in at least one second installation space of the vehicle. The subdivision of the electric high-voltage vehicle electrical system into the two subareas is designed in such a way that only work under electric voltage of the first subarea of the electric high-voltage vehicle electrical system is possible in the first installation space of the vehicle, and work in a stress-free state of the second subarea of the electric high-voltage vehicle electrical system is possible in the at least one second installation space of the vehicle.In addition, DE 10 2013 225 884 A1 shows a method for operating an electrical on-board power supply system of a motor vehicle, in which a low-voltage energy store is coupled to a high-voltage energy store via a voltage converter by means of an intermediate circuit store. According to the method, the intermediate circuit storage is precharged via the voltage converter by means of electrical energy from the low-voltage energy storage.The object of the invention is to specify an electrical high-voltage vehicle electrical system for a vehicle which is improved in comparison with the prior art, a vehicle which is improved in comparison with the prior art and has an electrical high-voltage vehicle electrical system, and a method for operating an electrical high-voltage vehicle electrical system for a vehicle which is improved in comparison with the prior art.The object is achieved according to the invention by an electric high-voltage vehicle electrical system for a vehicle having the features of claim 1, a vehicle having an electric high-voltage vehicle electrical system having the features of claim 8 and a method for operating an electric high-voltage vehicle electrical system for a vehicle having the features of claim 10.Advantageous embodiments of the invention are the subject matter of the dependent claims.An electric high-voltage on-board power supply system according to the invention for a vehicle comprises a high-voltage battery, at least one electric drive unit, at least one electric auxiliary unit and a bidirectional low-voltage DC converter, wherein a drive potential line pair with a drive isolation arrangement is provided for the electrical connection of the at least one electric drive unit to the high-voltage battery, wherein an auxiliary unit potential line pair with an auxiliary unit isolation arrangement is provided for the electrical connection of the at least one electric auxiliary unit and of the low-voltage DC converter to the high-voltage battery, and wherein a pre- and discharge circuit is provided which comprises a pre- and discharge isolation arrangement in a connection potential line pair coupled to the auxiliary unit potential line pair and the drive potential line pair.On the basis of the drive disconnection arrangement, the drive potential line pair and thus the at least one electrical drive unit can be connected or disconnected to the high-voltage battery.On the basis of the auxiliary unit isolation arrangement, the auxiliary unit potential line pair and thus the at least one electrical auxiliary unit and the low-voltage DC-DC converter can be connected or disconnected to the high-voltage battery.A connection point of the pre- and discharge circuit, in particular of the connection potential line pair, to the auxiliary unit potential line pair is situated after the auxiliary unit isolation arrangement, i.e. between the auxiliary unit isolation arrangement and the at least one electrical auxiliary unit, and a connection point of the pre- and discharge circuit, in particular of the connection potential line pair, to the drive potential line pair is situated after the drive isolation arrangement, i.e. between the drive isolation arrangement and the at least one electrical drive unit.The drive potential line pair and the auxiliary unit potential line pair are thus electrically connected in parallel when the drive disconnect arrangement and the auxiliary unit disconnect arrangement are closed. By means of the pre- and discharge circuit, in particular by means of its pre- and discharge isolation arrangement, the drive potential line pair and the auxiliary unit potential line pair, i.e. its respective positive potential line and its respective negative potential line, can be electrically connected to one another by closing the pre- and discharge isolation arrangement. This is expediently only effected when at least the drive isolating arrangement and, for example, additionally also the auxiliary unit isolating arrangement is open.A vehicle according to the invention comprises such an electrical high-voltage on-board system.The electric drive unit is provided in particular for driving the vehicle. The at least one electric drive unit is thus in particular a so-called electric traction machine of the vehicle. The high-voltage electrical system can also comprise, for example, a plurality of such electrical drive units, in particular a front electrical drive unit, in particular for driving wheels of a front axle of the vehicle, and a rear electrical drive unit, in particular for driving wheels of a rear axle of the vehicle. The at least one electrical auxiliary unit is designed, for example, as an electrical refrigerant compressor or as an electrical heating unit. The electric high-voltage on-board electrical system can also comprise, for example, a plurality of such electric auxiliary units, for example both the electric refrigerant compressor and the electric heating unit.The solution according to the invention enables, in particular, a pre-charge of at least one capacitor of the at least one electric drive unit via an electric supply path of the at least one electric auxiliary unit or of the plurality of electric auxiliary units, i.e. via the auxiliary unit potential line pair. The electric high-voltage on-board electrical system is in particular constructed in such a way that the at least one auxiliary unit or the plurality of auxiliary units and the at least one electric drive unit or the plurality of electric drive units can be connected or are connected to the high-voltage battery via separate isolating arrangements, i.e. via the auxiliary unit isolating arrangement or the drive isolating arrangement, and can therefore be operated independently of one another. For a respective switch-on process, capacitors in these components, i.e. at least one capacitor of the at least one electric drive unit or at least one capacitor of the at least one electric auxiliary unit, must first be precharged via a defined current before these components are connected directly to the high-voltage battery by closing the respective isolating arrangement.The solution according to the invention makes it necessary, in particular for precharging, for example only a single low-voltage DC converter, in particular having only two high-voltage potential line connections for connecting only one high-voltage potential line pair, with the result that higher shunt capacitances are avoided when using two low-voltage DC converters or when using a low-voltage DC converter having more high-voltage potential line connections for connecting a plurality of high-voltage potential line pairs. The precharging for two different battery outputs of the high-voltage battery to the at least one electrical auxiliary unit or the plurality of electrical auxiliary units and to the at least one electrical drive unit or the plurality of electrical drive units is thus effected via this single low-voltage DC-DC converter.In addition, for example, no pre-charge resistor or only one pre-charge resistor is required, whereby the number of pre-charge resistors is reduced compared to other solutions. Furthermore, the pre-charge and discharge circuit according to the invention and in particular the arrangement according to the invention in the connection potential line pair between the auxiliary unit potential line pair and the drive potential line pair is a decentralized solution in comparison with other pre-charge circuits which have to be arranged directly on the drive isolation arrangement. The solution according to the invention thus enables a reduction in the installation space required and a better adaptation of the so-called packaging, i.e. the arrangement of the components of the high-voltage electrical system, to circumstances of the vehicle. This decentralized solution therefore enables a substantially more variable spatial arrangement of the components of the high-voltage electrical system, with the result that they can be adapted particularly well to the installation space available and do not require a fixed spatial arrangement. For example, this decentralized pre- and discharge circuit can be arranged in a front installation space or in a rear installation space of the vehicle, depending on the installation space conditions which are present and which enable the arrangement of the pre- and discharge circuit.The solution according to the invention makes it possible in particular to shut off the at least one electric drive unit or the plurality of electric drive units when they are / are not required, in particular independently of the at least one electric auxiliary unit or the plurality of electric auxiliary units, for example during a DC charging process. As a result, a design of Y capacitors in the high-voltage on-board electrical system can be optimized.The at least one capacitor of the at least one electric drive unit and / or the at least one capacitor of the at least one electric auxiliary unit is in particular a Y capacitor, in particular for producing electromagnetic compatibility. The effect of Y capacitors in the field of electromagnetic compatibility, in particular radio interference suppression, is known to the person skilled in the art, so that no separate further explanation is required in this regard. Reference is also made to the relevant standardization, for example Directive 2014 / 30 / EU on electromagnetic compatibility, DIN EN 61000 and others.For reasons of electrical safety, an electrical energy stored in all Y capacitors should not exceed a predeterminable maximum value. Such a value is, for example, 0.2 J. This regularly leads to a design such that capacitance values of the Y capacitors are generally selected to be smaller on the vehicle side than would be necessary for a proper establishment of the electromagnetic compatibility, in particular with respect to the electrical components which are connected to the high-voltage electrical system.In particular during the DC charging process, i.e. for charging by means of a DC voltage, it is necessary that an energy content of all effective Y capacitors does not exceed a predefined total energy content. At present, a maximum value of 0.2 J is provided for this purpose, which is not to be exceeded. Due to the large number of electrical components of the vehicle and the increasing power, for example in the case of high-voltage components, the total capacitance of the Y capacitors present increases and increases, as a result of which the energy content stored there also increases in accordance with the increasing total capacitance. Moreover, it should be noted that, in particular in the high-voltage range, the energy content of the Y capacitors is particularly critical, especially since it should be noted that the electrical energy stored in the Y capacitors is a function of the electrical voltage of the Y capacitors in a quadratic manner. As a result, it is particularly difficult to meet the requirement with respect to the maximum energy content with respect to a respective high-voltage potential, particularly in the region of high voltage. It has proven problematic, especially in vehicles, to simultaneously meet requirements with respect to both electromagnetic compatibility and requirements with respect to electrical safety with respect to the energy of the Y capacitors.As already mentioned above, this problem is solved by the solution according to the invention, because the solution according to the invention makes it possible, for example, to shut off the at least one electric drive unit or the plurality of electric drive units during the DC charging, in particular independently of the at least one electric auxiliary unit or the plurality of electric auxiliary units, so that a different configuration of the Y capacitors of the components of the high-voltage electrical system is made possible.The pre- and discharge circuit can furthermore also be used for discharging the at least one capacitor of the at least one electrical drive unit or the capacitors of the plurality of electrical drive units and the at least one capacitor of the at least one electrical auxiliary unit or the capacitors of the electrical auxiliary units.The drive isolation arrangement is in particular designed as an all-pole isolation element, for example as an all-pole contactor, which can only close and open both potential lines of the drive potential line pair simultaneously. In particular, the solution described above is then particularly advantageous, since this solution makes it possible to be able to use only a single low-voltage DC-DC converter, in particular having only two high-voltage potential line connections for connecting only one high-voltage potential line pair. Furthermore, other solutions of the precharge circuit cannot be combined with such an all-pole separating element.When using the all-pole separating element as a drive separating arrangement for the at least one electric drive unit or the plurality of electric drive units, at least one resistor or both resistors can thus be saved compared to another solution of the precharge with two precharge resistors.Advantageously, the auxiliary unit isolation arrangement can comprise two isolation elements, which are each arranged on a pole of the auxiliary unit potential line pair and are designed as a contactor. The potential lines of the auxiliary unit potential line pair can then be individually switched with this, so that here, for example, a connection or disconnection of the potential lines of the auxiliary unit potential line pair is made possible in a pole-wise manner.In one possible embodiment, the pre- and discharge circuit comprises a pre-charge resistor, which is arranged in particular in a positive potential line of the connection potential line pair. This makes it possible in particular to pre-charge the at least one capacitor of the at least one electric drive unit or the capacitors of the electric drive units also by means of the high-voltage battery, alternatively or additionally to the possibility of pre-charging by means of the bidirectional low-voltage DC-DC converter and a low-voltage on-board system of the vehicle. If the pre-charge and discharge circuit does not have a pre-charge resistor, the pre-charge and discharge circuit is more cost-effective and the use of installation space is improved, but it is then not possible to pre-charge the at least one capacitor of the at least one electrical drive unit or the capacitors of the electrical drive units also by means of the high-voltage battery.The pre- and discharge separating arrangement comprises in particular a separating element in each potential line of the connecting potential line pair, which separating element is designed as a relay or, for example, as a switch or contactor, and which can be switched in particular independently of one another. This makes it possible, in particular for precharging and / or discharging the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units and / or the at least one capacitor of the at least one electric auxiliary unit or the capacitors of the electric auxiliary units, to open or close the two separating elements one after the other, in particular for precharging first the separating element in the negative potential line and then the separating element in the positive potential line.The charging and discharging circuit is arranged, for example, in a front installation space or in a rear installation space of the vehicle. Due to the decentralized solution of the pre- and discharge circuit, this can be selected to be adapted to existing installation space conditions on the vehicle.For example, the low-voltage DC-DC converter and / or the at least one electrical auxiliary unit, in particular the electrical heating unit and / or the electrical refrigerant compressor, and / or the front electrical drive unit, are arranged in the front installation space. Alternatively or additionally, for example an alternating current charging box, a direct current charging box, an inductive charging unit, an electric on-board charging unit and / or the low-voltage on-board electrical system or components thereof can be arranged in the front installation space.For example, the auxiliary unit separating arrangement and / or the drive separating arrangement and / or the rear electric drive unit are arranged in the rear installation space. Alternatively or additionally, for example, the AC charging box, the DC charging box, the inductive charging unit, the electric on-board charging unit, a current sensor, the auxiliary unit isolation arrangement, the drive isolation arrangement, a DC charging box isolation arrangement, a fuse, a filter unit for fast interference pulses and high-energy interference pulses (surge & burst filter) and / or the low-voltage on-board electrical system or components thereof can be arranged in the rear installation space.The high-voltage battery is arranged, for example, outside these two installation spaces, in particular in its own battery installation space, in particular in a central installation space in the longitudinal direction of the vehicle and thus in particular in an installation space arranged between the front and rear installation spaces.In a method according to the invention for operating an electric high-voltage vehicle electrical system, the pre- and discharge separation arrangement of the pre- and discharge circuit is closed for pre-charging the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units and of the at least one capacitor of the at least one electric auxiliary unit or the capacitors of the plurality of electric auxiliary units when the auxiliary unit separation arrangement is open and the drive separation arrangement is open, in particular by first closing the separation element in the negative potential line and then closing the separation element in the positive potential line, and by means of the low-voltage DC converter coupled to a low-voltage vehicle electrical system of the vehicle, the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units is pre-charged and the at least one capacitor of the at least one electric auxiliary unit or the capacitors of the plurality of electric auxiliary units is pre-charged. Subsequently, the drive separating arrangement and the auxiliary unit separating arrangement are expediently closed and, expediently, the pre- and unloading separating arrangement is subsequently opened. It is particularly advantageous that no pre-charge resistor is required in the pre-and-discharge circuit for this purpose, i.e. this also works with an embodiment of the high-voltage electrical system in which the pre-and-discharge circuit does not have a pre-charge resistor.Alternatively or additionally, in this method for pre-charging the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units, when at least one capacitor of the at least one electric auxiliary unit is already charged or when the capacitors of the plurality of electric auxiliary units are already charged, for example after a direct current charging process, the pre-and discharge separating arrangement of the pre-and discharge circuit, which expediently comprises the pre-charging resistor, is closed when the auxiliary unit separating arrangement is closed and in particular by first closing the separating element in the negative potential line and then closing the separating element in the positive potential line, and the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units are pre-charged by means of the high-voltage battery. Subsequently, the drive separating arrangement is expediently closed and expediently the pre- and unloading separating arrangement is subsequently opened. This allows the at least one capacitor of the at least one electrical drive unit or the capacitors of the plurality of electrical drive units to be precharged also by means of the high-voltage battery.Alternatively or additionally, in this method, for discharging the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units and the at least one capacitor of the at least one electric auxiliary unit or the capacitors of the plurality of electric auxiliary units, the auxiliary unit isolation arrangement and the drive isolation arrangement are opened, the pre- and discharge isolation arrangement of the pre- and discharge circuit is closed and the at least one capacitor of the at least one electric drive unit or the capacitors of the plurality of electric drive units and the at least one capacitor of the at least one electric auxiliary unit or the capacitors of the plurality of electric auxiliary units are discharged by means of the low-voltage DC-to-DC converter. Subsequently, the preliminary and discharge separating arrangement is expediently opened. The pre- and discharge circuit can thus also be used for discharging the at least one capacitor of the at least one electrical drive unit or the capacitors of the plurality of electrical drive units and the at least one capacitor of the at least one electrical auxiliary unit or the capacitors of the plurality of electrical auxiliary units. If necessary, for example during the charging process of the high-voltage battery, the auxiliary unit disconnecting arrangement can now be closed again. A short-term deactivation is not a problem, since this is not perceived by a user of the vehicle.The method results in particular in the advantages already described above with respect to the high-voltage electrical system and to the vehicle.The vehicle, in particular a motor vehicle, in particular a road vehicle, is in particular designed as an electric vehicle or as a hybrid vehicle. In particular, a high-voltage battery can be electrically charged by connecting the vehicle, in particular its high-voltage on-board power supply system, to at least one vehicle-external electrical energy source, i.e. in particular a charging station.The term "high voltage" is to be understood in particular as an electrical direct voltage which is in particular greater than approximately 60 V. In particular, the term "high voltage" should be interpreted in conformity with the standard ECE R 100. The term "low voltage" is to be understood accordingly in particular as an electrical DC voltage which is lower in comparison therewith, in particular an electrical DC voltage of at most 30 V, in particular at most 28 V, in particular at most 24 V, in particular at most 14 V, in particular at most 12 V, in particular a rated voltage of the electrical low-voltage on-board system of the vehicle, which therefore comprises the electrical high-voltage on-board system and the electrical low-voltage on-board system, wherein the electrical DC voltage, in particular rated voltage, of the high-voltage on-board system is greater than the electrical DC voltage, in particular rated voltage, of the low-voltage on-board system.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 schematically shows a vehicle, FIG. 2 schematically shows an embodiment of an electric high-voltage vehicle electrical system for a vehicle, FIG. 3 schematically shows charging of capacitors of electric drive units and electric auxiliary units, FIG. 4 schematically shows charging of capacitors of electrical drive units, FIG. 5 schematically shows a discharging of capacitors of electric drive units and electric auxiliary units, FIG. 6 schematically shows a further embodiment of an electric high-voltage vehicle electrical system for a vehicle and charging of capacitors of electric drive units and electric auxiliary units, and FIG. 7 schematically shows a further embodiment of an electric high-voltage vehicle electrical system for a vehicle.Corresponding parts are provided with the same reference numerals in all figures.FIG. 1 shows a schematic illustration of a vehicle 1. the vehicle 1, in particular a motor vehicle, in particular a road vehicle, is in particular designed as an electric vehicle or as a hybrid vehicle. In particular, a high-voltage battery 2 can be electrically charged by connecting the vehicle 1, in particular an electrical high-voltage on-board system 3 of the vehicle 1, to at least one vehicle-external electrical energy source, i.e. in particular a charging station.FIGS. 2 to 7 show various embodiments of the high-voltage electrical system 3. the high-voltage electrical system 3 comprises in all embodiments the high-voltage battery 2, at least one electrical drive unit 4, 5, at least one electrical auxiliary unit 6, 7 and a bidirectional low-voltage DC-DC converter 8, which is coupled to a low-voltage electrical system 9, in particular to a 12 V low-voltage electrical system, of the vehicle 1. In the examples shown here, the electric high-voltage on-board electrical system 3 comprises a front electric drive unit 4 and a rear electric drive unit 5.In the examples shown here, the bidirectional low-voltage DC-DC converter 8 and the front electric drive unit 4 and the electric auxiliary unit 6, which is designed as an electric heating unit, and the electric auxiliary unit 7, which is designed as an electric refrigerant compressor, and likewise the low-voltage on-board electrical system 9 or at least components thereof are arranged in a front installation space VB of the vehicle 1, and the rear electric drive unit 5 is arranged in a rear installation space HB of the vehicle 1. The high-voltage battery 2 or at least cell modules of the high-voltage battery 2 is / are arranged outside these two installation spaces VB, HB, in particular in a central installation space MB in the longitudinal direction of the vehicle 1 between the front installation space VB and the rear installation space HB.For the electrical connection of the electrical drive units 4, 5 to the high-voltage battery 2, a drive potential line pair 10 having a drive disconnection arrangement 11 is provided, so that the electrical drive units 4, 5 are electrically connected to the high-voltage battery 2 or electrically disconnected from it depending on a switching position of the drive disconnection arrangement 11. In the examples illustrated here, the drive disconnect arrangement 11 is arranged in the rear installation space HB of the vehicle 1. In the embodiments of the high-voltage vehicle electrical system 3 illustrated here, it is designed as an all-pole separating element, for example as an all-pole contactor, which can only close and open both potential lines HV+, HV- of the drive potential line pair 10 simultaneously. In this way, in particular, a connection of the electric drive units 4, 5 to the high-voltage battery 2 and likewise a disconnection from the high-voltage battery 2 are made possible by a single switching process in each case.For the electrical connection of the electrical auxiliary units 6, 7 and the low-voltage DC converter 8 to the high-voltage battery 2, an auxiliary unit potential line pair 12 having an auxiliary unit isolation arrangement 13 is provided, so that the low-voltage DC converter 8 and the electrical auxiliary units 6, 7 are electrically connected to the high-voltage battery 2 or electrically disconnected from it depending on a switching position of the auxiliary unit isolation arrangement 13. In the examples illustrated here, the auxiliary unit separation arrangement 13 is arranged in the rear installation space HB of the vehicle 1. It comprises, for example, two separating elements 14, 15 each designed as a contactor.In the examples illustrated here, the electrical high-voltage on-board electrical system 3 furthermore comprises a DC charging box 16, wherein a DC charging potential line pair 17 having a DC charging isolation arrangement 18 is provided for the electrical connection of the DC charging box 16 to the high-voltage battery 2, such that the DC charging box 16 is electrically connected to the high-voltage battery 2 or is electrically disconnected from it as a function of a switching position of the DC charging isolation arrangement 18. In the examples shown here, a filter unit 19 for fast interference pulses and high-energy interference pulses (surge & burst filter) is arranged in the DC charging potential line pair 17 between the DC charging isolation arrangement 18 and the DC charging box 16. In the examples shown here, both the DC charging box 16 and the filter unit 19 for fast interference pulses and high-energy interference pulses and the DC charging separation arrangement 18 are arranged in the rear installation space HB of the vehicle 1. In the embodiments of the high-voltage on-board system 3 illustrated here, the DC charging isolation arrangement 18 is designed as an all-pole isolation element, for example as an all-pole contactor, which can only close and open both potential lines HV+, HV- of the DC charging potential line pair 17 simultaneously.Between the isolating arrangements 11, 13, 18 and the high-voltage battery 2, in the examples shown, a current sensor 20 is furthermore arranged in the positive potential line HV+, which current sensor is arranged in the rear installation space HB of the vehicle 1 in the examples shown.In the examples shown here, the high-voltage electrical system 3 furthermore comprises an electrical on-board charger unit 21, which is coupled to an AC charging box 22 of the vehicle 1 and to the auxiliary unit potential line pair 12. In the examples shown here, the electric on-board charger unit 21 is arranged in the front installation space VB of the vehicle 1 and the AC charging box 22 is arranged in the rear installation space HB of the vehicle 1 in the examples shown here.In the positive potential line HV+ of the auxiliary unit line pair 12, in the examples shown here, a fuse 23 is arranged downstream of the auxiliary unit isolation arrangement 13, i.e. starting from the latter in the direction of the auxiliary units 6, 7, of the low-voltage DC converter 8 and of the electric on-board charger unit 21, which fuse is arranged in the rear installation space HB of the vehicle 1 in the examples shown here.The two electric drive units 4, 5 are connected electrically in parallel to one another in the examples shown. Furthermore, in the examples shown, the two electrical auxiliary units 6, 7 are electrically connected in parallel with one another.In the embodiments of the electric high-voltage on-board system 3 shown here, the auxiliary unit potential line pair 12 and the drive potential line pair 10 can thus be connected to the high-voltage battery 2 via separate and independently switchable isolation arrangements 13, 11, such that the electric auxiliary units 6, 7 and the electric drive units 4, 5 can be operated independently of one another. If both the drive isolation arrangement 11 and the auxiliary unit isolation arrangement 13 are closed, the drive potential line pair 10 and the auxiliary unit potential line pair 12 are electrically connected in parallel.At least in some of the components of the electrical on-board power supply 3, in particular in the electrical auxiliary units 6, 7 and the electrical drive units 4, 5, capacitors, in particular Y capacitors, are present, which have to be precharged initially via a defined current for a respective switching-on process, before these components are connected directly to the high-voltage battery 2 by closing the respective disconnect arrangement 13, 11, in particular the drive disconnect arrangement 11 and the auxiliary unit disconnect arrangement 13. In order to make this possible in the embodiments of the electrical high-voltage vehicle electrical system 3 illustrated here with the drive isolation arrangement 11 designed as an all-pole isolation element, in particular as an all-pole contactor, and with only a single low-voltage DC voltage converter 8, in particular with only two high-voltage potential line connections for connecting only one high-voltage potential line pair to the low-voltage DC voltage converter 8, a pre- and discharge circuit 24 is provided, which comprises a pre- and discharge isolation arrangement 25 in a connection potential line pair 26 coupled to the auxiliary unit potential line pair 12 and the drive potential line pair 10.A connection point of the pre- and discharge circuit 24, in particular of the connection potential line pair 26, to the auxiliary unit potential line pair 12 is situated after the auxiliary unit isolation arrangement 13, i.e. between the auxiliary unit isolation arrangement 13 and the electrical auxiliary units 6, 7, and a connection point of the pre- and discharge circuit 24, in particular of the connection potential line pair 26, to the drive potential line pair 10 is situated after the drive isolation arrangement 11, i.e. between the drive isolation arrangement 11 and the electrical drive units 4, 5.The pre- and discharge separating arrangement 25 advantageously comprises a separating element 27, 28, which is designed for example as a relay, in particular as a high-voltage relay, or for example as a switch or contactor, in each potential line HV+, HV- of the connecting potential line pair 26, which can advantageously be switched independently of one another.By means of the pre- and discharge circuit 24, in particular by means of its pre- and discharge isolation arrangement 25, the drive potential line pair 10 and the auxiliary unit potential line pair 12, i.e. their respective positive potential line HV+ and their respective negative potential line HV- can thus be electrically connected to one another, i.e. electrically connected to one another in series, by closing the pre- and discharge isolation arrangement 25. This is expediently only effected when at least the drive isolating arrangement 11 and, for example, additionally also the auxiliary unit isolating arrangement 13 is open.The pre- and discharge circuit 24 is thus designed as a decentralized pre- and discharge circuit 24, since although it must be arranged between the supply path of the electrical auxiliary units 6, 7 and the supply line to the electrical drive units 4, 5, i.e. between the auxiliary unit potential line pair 12 and the drive potential line pair 10, its positioning in the vehicle 1 is freely or at least relatively freely selectable, since it in particular does not have to be arranged directly on the drive isolation arrangement 11. Therefore, for example, it may be disposed in the front installation space VB of the vehicle 1 as shown in FIGS. 2 to 6, or may be disposed in the rear installation space HB of the vehicle 1 as shown in FIG. 7. The positioning of the charging and discharging circuit 24 can thus take place freely according to existing installation space conditions of the respective vehicle 1, in particular of a respective vehicle type and / or a respective vehicle series.As already mentioned above, the pre-charging of the capacitors of the electric drive units 4, 5 is made possible by means of the pre-and-discharge circuit 24, as is shown in FIGS. 3, 4 and 6 and is described in more detail below, and for example additionally also makes possible the pre-charging of the capacitors of the electric auxiliary units 6, 7, as is shown in FIGS. 3 and 6 and is described in more detail below. Furthermore, by means of the pre- and discharge circuit 24, discharging of the capacitors of the electric drive units 4, 5 and of the electric auxiliary units 6, 7 is also made possible, as is shown in FIG. 5 and is described in more detail below.In the embodiments according to FIGS. 2 to 5 and 7, the pre-and-discharge circuit 24 additionally comprises a pre-charge resistor 29. this pre-charge resistor 29 is expediently arranged in the positive potential line HV+ of the connection potential line pair 26, in the embodiments shown in each case in front of the separating element 27 in the positive potential line HV+ of the connection potential line pair 26, i.e. between the auxiliary power line pair 12 and the pre-and-discharge separating arrangement 25.FIG. 6 shows an embodiment in which the pre- and discharge circuit 24 does not have a pre-charge resistor 29, thus expediently has exclusively the pre- and discharge separating arrangement 25. As a result, only one of the two variants of the precharging of the capacitors of the electric drive units 4, 5 can be carried out, as is likewise described in more detail below.FIGS. 2 to 5 show embodiments of the high-voltage electrical system 3 in which the pre-charge and discharge circuit 24 comprising the pre-charge resistor 29 is arranged in the front installation space VB of the vehicle 1. FIG. 7 shows an embodiment of the high-voltage electrical system 3, in which the pre-charging and discharging circuit comprising the pre-charging resistor 29 is arranged in the rear installation space HB of the vehicle 1.FIG. 6 shows an embodiment of the high-voltage electrical system 3 in which the pre-charge and discharge circuit 24, which does not have a pre-charge resistor 29, is arranged in the front installation space VB of the vehicle 1. Alternatively, this pre- and discharge circuit 24, which does not have a pre-charge resistor 29, can also be arranged in the rear installation space HB of the vehicle 1 in further embodiments of the high-voltage electrical system 3 which are not illustrated here. The advantage of this embodiment without a series resistor 29 is the saving of the pre-charge resistor 29, whereby costs are reduced and the use of installation space is improved.FIG. 3 shows a variant of the precharging of the capacitors of the electric drive units 4, 5 and of the electric auxiliary units 6, 7. For this purpose, when the auxiliary unit separating arrangement 13 is open and the drive separating arrangement 11 is open, the pre- and discharge separating arrangement 25 of the pre- and discharge circuit 24 is closed, wherein advantageously the separating element 28 in the negative potential line HV- is closed first and then the separating element 27 in the positive potential line HV+ is closed. By means of the low-voltage DC-to-DC converter 8 coupled to the low-voltage on-board electrical system 9 of the vehicle 1, the capacitors of the electric drive units 4, 5 and of the electrical auxiliary units 6, 7 are now precharged, as shown schematically by means of precharge arrows VP, wherein only the precharging of the capacitors of the electric drive units 4, 5 is shown schematically here by means of these precharge arrows VP. Subsequently, the drive disconnect assembly 11 and the auxiliary unit disconnect assembly 13 are closed. Thereafter, the pre- and discharge separating assembly 25 is opened.FIG. 3 shows this variant of precharging the capacitors of the electric drive units 4, 5 and of the electric auxiliary units 6, 7 by means of the embodiment of the precharge and discharge circuit 24 which has the precharge resistor 29. However, this variant of precharging the capacitors of the electric drive units 4, 5 and of the electric auxiliary units 6, 7 functions in the same way also by means of the embodiment of the precharge and discharge circuit 24, which does not have a precharge resistor 29, as shown in FIG. 6. If the auxiliary unit separating arrangement 13 is not yet open, it is first opened. When the auxiliary unit separating arrangement 13 is open and the drive separating arrangement 11 is open, the pre- and discharge separating arrangement 25 of the pre- and discharge circuit 24 is then closed, wherein advantageously the separating element 28 in the negative potential line HV- is closed first and then the separating element 27 in the positive potential line HV+ is closed. By means of the low-voltage DC-to-DC converter 8 coupled to the low-voltage on-board electrical system 9 of the vehicle 1, the capacitors of the electric drive units 4, 5 and of the electrical auxiliary units 6, 7 are now precharged, as shown schematically by means of the precharge arrows VP, wherein only the precharging of the capacitors of the electric drive units 4, 5 is shown schematically here by means of these precharge arrows VP. Subsequently, the drive disconnect assembly 11 and the auxiliary unit disconnect assembly 13 are closed. Thereafter, the pre- and discharge separating assembly 25 is opened.FIG. 4 shows a further variant in which, however, only the capacitors of the electric drive units 4, 5 can be precharged and which can be carried out only with the embodiment of the precharge and discharge circuit which comprises the precharge resistor 29. This variant can be used in particular when the capacitors of the electrical auxiliary units 6, 7 are already charged, for example after a DC charging process. The auxiliary unit separating arrangement 13 is then closed and the drive separating arrangement 11 is open. The pre- and discharge separating arrangement 25 of the pre- and discharge circuit 24 is closed, wherein advantageously firstly the separating element 28 in the negative potential line HV- and subsequently the separating element 27 in the positive potential line HV+ is closed. The capacitors of the electric drive units 4, 5 are now precharged by means of the high-voltage battery 2, as shown schematically by means of the precharge arrows VP. This takes place via the auxiliary unit potential line pair 12 and the connecting potential line pair 26 with the closed pre- and discharge separating arrangement 25, and the drive separating arrangement 11 is then closed. Thereafter, the pre- and discharge separating assembly 25 is opened.In this variant, it is thus possible to pre-charge the capacitors of the electric drive units 4, 5 also by means of the high-voltage battery 2. However, this variant is only possible by means of the embodiment of the pre- and discharge circuit 24 which comprises the pre-charge resistor 29.As already mentioned, the pre- and discharge circuit 24 can also be used for discharging the capacitors of the electric drive units 4, 5 and of the electric auxiliary units 6, 7. This is shown in FIG. 5 for the embodiment of the high-voltage electrical system 3 in which the pre-charge and discharge circuit 24 comprises the pre-charge resistor 29. However, this also works in the same manner described in more detail below in the embodiment of the high-voltage electrical system 3 in which the pre-charge and discharge circuit 24 does not comprise a pre-charge resistor 29.For discharging the capacitors of the electric drive units 4, 5 and the capacitors of the electric auxiliary units 6, 7, the auxiliary unit separating arrangement 13 and the drive separating arrangement 11 are opened, as shown in FIG. 5. Subsequently, the pre- and discharge isolating arrangement 25 of the pre- and discharge circuit 24 is closed, for example by first closing the isolating element 28 in the negative potential line HV- and then closing the isolating element 27 in the positive potential line HV+. The capacitors of the electric drive units 4, 5 and of the electric auxiliary units 6, 7 are now discharged by means of the low-voltage DC-DC converter 8, as shown schematically by means of discharge arrows EP, wherein only the discharging of the capacitors of the electric drive units 4, 5 is shown schematically here by means of these discharge arrows EP. Subsequently, the pre- and discharge separating arrangement 25 is opened. If necessary, for example during the charging process of the high-voltage battery 2, the auxiliary unit disconnecting arrangement 13 can now be closed again. A short-term deactivation is not a problem, since this is not perceived by a user of the vehicle 1.The precharging and discharging have been described here in each case on the basis of the precharge and discharge circuit 24 arranged in the front installation space VB of the vehicle 1. The position of the pre-and-discharge circuit 24 in the vehicle 1, however, has no influence thereon, i.e. the pre-charge and discharge functions in the same way if the respective pre-and-discharge circuit 24, in particular the respective embodiment of the pre-and-discharge circuit 24, with or without a series resistor 29, is arranged in the rear installation space HB of the vehicle 1.List of reference characters1 Vehicle 2 High-voltage battery 3 High-voltage on-board power supply system 4 Front electric drive unit 5 Rear electric drive unit 6, 7 Electric auxiliary unit 8 Low-voltage DC voltage converter 9 Low-voltage on-board power supply system 10 Drive potential line pair 11 Drive isolation arrangement 12 Auxiliary unit potential line pair 13 Auxiliary unit isolation arrangement 14, 15 Isolation element of the auxiliary unit isolation arrangement 16 Direct current charging box 17 Direct current charging potential line pair 18 Direct current charging isolation arrangement 19 Filter unit 20 Current sensor 21 On-board charging unit 22 Alternating current charging box 23 Fuse 24 Pre-charging and discharging circuit 25 Pre-charging and discharging isolation arrangement 26 Connection potential line pair 27, 28 Isolation element of the pre-charging and discharging isolation arrangement 29 Pre-charging resistor EP Discharge arrow VP Pre-charging arrow HV+ Plus potential line HV- Minus potential line HB Rear installation space MB Average installation space VB Front installation space

Claims

High-voltage electrical system (3) for a vehicle (1), characterized a high-voltage battery (2), at least one electric drive unit (4, 5), at least one electric auxiliary unit (6, 7) and a bidirectional low-voltage DC-to-DC converter (8) which is coupled to a low-voltage on-board electrical system (9), - wherein a drive potential line pair (10) with a drive disconnection arrangement (11) is provided for the electrical connection of the at least one electric drive unit (4, 5) to the high-voltage battery (2), and the drive disconnection arrangement (11) can connect or disconnect the drive potential line pair (10) and thus the at least one electric drive unit (4, 5) to the high-voltage battery (2), - wherein a drive potential line pair (10) with a drive disconnection arrangement (11) is provided for the electrical connection of the at least one electric auxiliary unit (6, In addition, in the case of the low-voltage DC converter (7) and the low-voltage DC converter (8) with the high-voltage battery (2), an auxiliary unit potential line pair (12) with an auxiliary unit isolation arrangement (13) is provided and the auxiliary unit isolation arrangement (13) can connect or disconnect the auxiliary unit potential line pair (12) and therefore the at least one electrical auxiliary unit (6, 7) and the low-voltage DC converter (8) with the high-voltage battery (2), and - wherein a pre- and discharge circuit (24) is provided which comprises a pre- and discharge isolation arrangement (25) in a connection potential line pair (26) coupled to the auxiliary unit potential line pair (12) and the drive potential line pair (10) and a first connection point of the connection potential line pair (26) with the auxiliary unit potential line pair (12) between the auxiliary unit isolation arrangement (13) and the at least one electrical auxiliary unit (6, 6), 7) and the low-voltage DC-to-DC converter (8), and a second connection point of the connection potential line pair (26) to the drive potential line pair (10) is located between the drive isolating arrangement (11) and the at least one electric drive unit (4, 5).High-voltage electrical system (3) according to Claim 1, characterized in that the drive disconnect arrangement (11) is designed as an all-pole disconnect element.High-voltage electrical system (3) according to Claim 1 or 2, characterized in that the auxiliary unit disconnection arrangement (13) comprises two disconnection elements (14, 15), which are each arranged on a pole of the auxiliary unit potential line pair (12) and are designed as a contactor.High-voltage electrical system (3) according to one of the preceding claims, characterized in that the pre-charging and discharging circuit (24) comprises a pre-charging resistor (29).High-voltage electrical system (3) according to Claim 4, characterized in that the precharge resistor (29) is arranged in a positive potential line (HV+) of the connecting potential line pair (26).High-voltage electrical system (3) according to one of the preceding claims, characterized in that the pre- and discharge disconnection arrangement (25) comprises a disconnection element (27, 28), which is designed as a relay, switch or contactor, in each potential line (HV+, HV-) of the connecting potential line pair (26) and can be connected independently of one another.High-voltage electrical system (3) according to one of the preceding claims, characterized in that the at least one electrical auxiliary unit (7, 6) is designed as an electrical refrigerant compressor or as an electrical heating unit.Vehicle (1) having an electrical high-voltage on-board electrical system (3) according to one of the preceding claims.Vehicle (1) according to Claim 8, characterized in that the charging and discharging circuit (24) is arranged in a front installation space (VB) or in a rear installation space (HB) of the vehicle (1).Method for operating an electric high-voltage vehicle electrical system (3) according to one of Claims 1 to 7, wherein - for pre-charging at least one capacitor of the at least one electric drive unit (4, 5) and at least one capacitor of the at least one electric auxiliary unit (6, 7) with the auxiliary unit isolation arrangement (13) open and the drive isolation arrangement (11) open, the pre-and discharge isolation arrangement (25) of the pre-and discharge circuit (24) is closed and, by means of the low-voltage DC converter (8) coupled to a low-voltage vehicle electrical system (9), the at least one capacitor of the at least one electric drive unit (4, 5) and the at least one capacitor of the at least one electric auxiliary unit (6, 7) are pre-charged, and / or - for pre-charging the at least one capacitor of the at least one electric drive unit (4, 5) with the at least one capacitor of the at least one electric auxiliary unit (6, 5) already charged, In the case of a closed auxiliary unit separation arrangement (13) and an open drive separation arrangement (11), the pre- and discharge separation arrangement (25) of the pre- and discharge circuit (24) is closed and the at least one capacitor of the at least one electrical drive unit (4, 5) is precharged by means of the high-voltage battery (2), and / or - for discharging the at least one capacitor of the at least one electrical drive unit (4, 5) and of the at least one capacitor of the at least one electrical auxiliary unit (6, 7), the auxiliary unit separation arrangement (13) and the drive separation arrangement (11) are opened, the pre- and discharge separation arrangement (25) of the pre- and discharge circuit (24) is closed and the at least one capacitor of the at least one electrical drive unit (4, 5) and the at least one capacitor of the at least one electrical auxiliary unit (6, 7) are discharged by means of the low-voltage DC converter (8).

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