Vehicle electrical system topology for a drive train of a battery electric vehicle

Abstract

The invention relates to a vehicle electrical system topology (1) for a drive train (20) of a battery electric vehicle. The vehicle electrical system topology (1) comprises an electrically rechargeable high-voltage battery (2) for providing an electrical high-voltage output voltage (V-HV). Furthermore, the vehicle electrical system topology comprises an electrical HV input connection (3) for connecting the on-board electrical system topology (1) to an electrical charging station (30, 31) for charging the high-voltage battery (2). Furthermore, the vehicle electrical system topology comprises a DC-to-DC converter (4) for converting an electrical high-voltage input voltage (HV-E) into the high-voltage output voltage (HV-A), which is greater than the input voltage and can be or is electrically connected to the high-voltage battery (2) via the HV input connection (3). In addition, the vehicle electrical system topology comprises an electrical switch (5) arranged between the DC-to-DC converter (4) and the high-voltage battery (2) for electrically interrupting the electrical connection between the DC-to-DC converter (4) and the high-voltage battery (2). According to the invention, the vehicle electrical system topology comprises an electrical bypass (XX) having an electrical bypass line (6) that electrically connects the HV input connection (3) to the high-voltage battery (2) past the DC-to-DC converter (4). According to the invention, at least one electrical bypass switch (7a, 7b) for interrupting said electrical connection is arranged in the electrical bypass or in the electrical bypass line (6).

Description

[0001] Description

[0002] title

[0003] On-board electrical system topology for a drive train of a battery-electric vehicle

[0004] The invention relates to an on-board electrical system topology for a powertrain of a battery-electric vehicle and to a powertrain with such an on-board electrical system topology. The invention further relates to a method for operating such an on-board electrical system topology.

[0005] Conventional battery-electric vehicles with high-voltage batteries are often equipped with an electrical system topology that allows the use of charging stations to recharge the high-voltage battery. These charging stations can provide a maximum charging voltage of 400 volts, which is lower than the nominal output voltage of the high-voltage battery when fully charged, which might be, for example, 800 volts. To address this, the vehicle's electrical system topology may include a DC-DC converter acting as a boost converter, which increases the lower voltage level of the charging station to the nominal output voltage of the high-voltage battery. For example, a charging voltage of 400V provided by the charging station can thus be increased to 800 volts by means of the DC-DC converter.

[0006] The term "on-board network topology" refers here to the electrical structure, in particular the electrical wiring, of an on-board network.

[0007] However, a disadvantage of such a vehicle electrical system topology is that it precludes the use of electric charging stations with a charging voltage corresponding to the nominal output voltage of the high-voltage battery. In other words, it is therefore an object of the present invention to provide an improved embodiment of the vehicle electrical system topology described above, in which the aforementioned disadvantage is eliminated.

[0008] This problem is solved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims.

[0009] The basic idea of ​​the invention is therefore to equip a vehicle electrical system topology with the DC voltage converter described above, which functions as a boost converter, so that a low electrical voltage level of the charging station can be increased to the nominal electrical output voltage of the high-voltage battery.

[0010] In addition to the DC-DC converter, the proposed solution in the vehicle electrical system topology includes an electrical bypass, which allows the boost converter to be bypassed if necessary. This makes it possible to connect a charging station with an electrical charging voltage that corresponds to the nominal output voltage of the high-voltage battery. With the aid of electrical switches, the vehicle electrical system topology according to the invention makes it possible to selectively activate either the DC-DC converter or the aforementioned electrical bypass, depending on whether the high-voltage battery is to be charged with an electrical charging voltage equal to its nominal electrical output voltage or with a charging voltage lower than this nominal output voltage.

[0011] Furthermore, the DC / DC converter can absorb electrical currents caused by the inverter and other consumers.

[0012] Voltage fluctuations are reduced or dampened. This means that the vehicle electrical system requires fewer filters and capacitors to achieve the desired damping of voltage fluctuations without the need for a DC-DC converter. This results in cost advantages. Furthermore, the DC-DC converter can regulate the output voltage to an optimum level, which also offers advantages when controlling an electric machine electrically connected to the vehicle electrical system as part of the electric drivetrain. In particular, control losses can be reduced, which in turn improves system efficiency.

[0013] A vehicle equipped with the on-board network topology according to the invention can therefore be charged very flexibly with electrical energy from charging stations with different charging voltage levels. Since, in principle, more charging stations are available for charging the vehicle, the flexibility of vehicle operation also improves, particularly with regard to the achievable range between two charging stops, as charging stations with different charging voltages can now be used. In addition, the provision of a DC-DC converter offers a number of advantages.

[0014] Additionally, the available DC-DC converter can stabilize the electrical system voltage. In particular, it can stabilize transients and reduce high-voltage ripple when an electric drive is drawing peak power from the electrical system. Finally, the provision and use of the DC-DC converter also offers advantages regarding electromagnetic shielding, known to those skilled in the art as "EMC," which can be reduced compared to conventional solutions without a DC-DC converter.

[0015] Following the inventive concept explained above, an on-board electrical system topology according to the invention comprises a high-voltage battery connection for connecting an electrically rechargeable high-voltage battery, which in turn provides a high-voltage output voltage. Such a high-voltage battery can therefore be connected to the high-voltage battery connection. Furthermore, the on-board electrical system topology comprises an electrical HV input connection for connecting the on-board electrical system topology to an electrical charging station for charging the high-voltage battery. The on-board electrical system topology also comprises a DC / DC converter for converting a high-voltage input voltage into a higher high-voltage output voltage, via which the HV input connection can be electrically connected to, or is connected to, the high-voltage battery.Furthermore, the vehicle electrical system topology includes an electrical switch located between the DC-DC converter and the high-voltage battery for electrically interrupting the electrical connection between the DC-DC converter and the high-voltage battery terminal, and thus the high-voltage battery connected to the high-voltage battery terminal. For this purpose, the electrical switch can be configured to change between a closed state, in which the electrical connection between the DC-DC converter and the high-voltage battery exists, and an open state, in which the electrical connection between the DC-DC converter and the high-voltage battery is interrupted. The electrical switch can, in particular, be a semiconductor switch, preferably a power transistor.

[0016] The DC-DC converter can be equipped with additional functionalities. In particular, it can be designed to operate in at least one mode as a boost converter and another as a buck converter, and to be switchable between these modes. In this way, when a vehicle is in operation without an electric charging station, the DC-DC converter can increase or decrease the output voltage provided by the high-voltage battery depending on the battery's state of charge.

[0017] According to the invention, the vehicle electrical system topology comprises an electrical bypass with an electrical bypass line that routes the high-voltage input connection past the DC-DC converter and electrically connects it to the high-voltage battery connection or the high-voltage battery itself. According to the invention, at least one electrical bypass switch for interrupting this electrical connection is arranged in the electrical bypass or in the electrical bypass line. Analogous to the electrical switch, the electrical bypass switch can also be configured to change between a closed state, in which the electrical connection between the DC-DC converter and the high-voltage battery exists, and an open state, in which the electrical connection between the DC-DC converter and the high-voltage battery is interrupted. The electrical bypass switch can also be a semiconductor switch, preferably a power transistor.The DC-DC converter can be selectively activated or deactivated using the electrical switch and the bypass switch. In the former case, the high-voltage input voltage, i.e., the charging voltage of the electric charging station, is converted into a higher high-voltage output voltage and then supplied to the high-voltage battery for charging. In the latter case, this conversion is omitted, and consequently, the high-voltage input voltage, i.e., the charging voltage of the electric charging station, is supplied unchanged to the high-voltage battery for charging.

[0018] The vehicle electrical system topology can also include a control / regulating device for controlling the electrical switch or bypass switches and thus for switching between different switching states of the vehicle electrical system topology. If the vehicle electrical system topology is installed in a motor vehicle, the control / regulating device can be a control unit already present in the vehicle.

[0019] Considering the switching states of the switch and the electrical switch described above, an embodiment proves particularly advantageous in which the vehicle electrical system topology is switchable at least between a first and a second switching state. In the first switching state, the electrical switch between the DC-DC converter and the high-voltage battery connection is closed, so that the DC-DC converter can be electrically connected to the high-voltage battery via the switch. In this case, the boost converter is active, and the high-voltage battery can be charged by connecting the vehicle electrical system topology to a charging station whose charging voltage is lower than the nominal output voltage of the high-voltage battery.Furthermore, in the first switching state, all existing bypass switches are open, so the electrical connection between the high-voltage input terminal and the high-voltage battery terminal is interrupted via the electrical bypass line. In contrast, in the second switching state, the electrical switch between the DC-DC converter and the high-voltage battery terminal is open, thus interrupting the electrical connection between the DC-DC converter and the high-voltage battery via this switch. Additionally, in the second switching state, at least one bypass switch is closed, so the electrical bypass is activated. The second switching state can also be selected when the vehicle is in operation, i.e., when no electric charging station is connected to the vehicle's electrical system.In particular, the first bypass switch can be set to the closed position and the second bypass switch to the open position. In this case, the DC-DC converter can dampen or even completely suppress electrical voltage spikes in the vehicle electrical system. This reduces the number of filter elements and capacitors required in the vehicle electrical system and the inverter connected to it. This has a positive effect on the manufacturing costs of the vehicle electrical system.

[0020] According to an advantageous embodiment, a first and a second electrical bypass switch are provided in the bypass line. In this embodiment, the first bypass switch is arranged in a first branch and the second bypass switch in a second branch of an electrical parallel circuit formed in the bypass line. In the second branch of the parallel circuit, an impedance, in particular in the form of at least one ohmic resistor, is also arranged electrically in series with the second bypass switch. This embodiment allows for particularly reliable pre-charging of a largely or even completely discharged high-voltage battery, whose voltage level, due to its discharge, is far below the charging voltage of typically 800 volts provided by the charging station when connected.To prevent voltage flashovers and the resulting formation of wear-inducing arcs when connecting the vehicle's electrical system to the charging station, due to the large voltage difference between the charging voltage and the current voltage level of the nearly fully discharged high-voltage battery, the first bypass switch can be opened and the second bypass switch closed before connecting the charging station. This ensures that the electrical connection from the charging station to the high-voltage battery, provided by the electrical bypass, is made via the aforementioned impedance, thus limiting the electrical current flow from the charging station to the high-voltage battery and consequently preventing voltage flashovers and arcs.

[0021] A particularly advantageous feature is the ability to switch to a third switching state, in which the first bypass switch is open and the second bypass switch is closed. Furthermore, to activate the bypass, the electrical switch between the DC-DC converter and the high-voltage battery is also open in the third switching state – just as in the second. In the third switching state, the high-voltage battery can be electrically pre-charged via the bypass until its voltage level exceeds a threshold at which the risk of voltage flashovers is eliminated or at least significantly reduced. The vehicle electrical system can then be switched to the second switching state, in which the electrical connection between the charging station and the bypass's high-voltage battery is made via the first branch and thus without impedance, i.e., with low resistance.Consequently, the high-voltage battery can be charged with maximum electrical charging current in the second switching state. In this second switching state, the first bypass switch is closed and the second bypass switch is open. The electrical charging therefore occurs via the first branch, bypassing the impedance in the second branch, and thus with low resistance.

[0022] In a preferred embodiment, the DC-DC converter is configured as a boost converter and comprises a first high-voltage side and a second high-voltage side. Furthermore, the DC-DC converter / boost converter is configured to convert a high-voltage input voltage provided at the first high-voltage side into a high-voltage output voltage provided at the second high-voltage side that is greater than the high-voltage input voltage. Preferably, the first high-voltage side can be inductively coupled to the second high-voltage side. In this case, the two high-voltage sides are galvanically isolated from each other.

[0023] According to an advantageous embodiment, the high-voltage battery connection or the high-voltage battery itself can be electrically connected to a low-voltage electrical system via a further DC / DC converter for converting the high-voltage output voltage into a low voltage. In this way, said low-voltage electrical system can be supplied with electrical energy. In particular, a rechargeable low-voltage battery provided in the low-voltage electrical system can be electrically charged using the electrical system topology according to the invention.

[0024] Preferably, the electrical charging voltage provided by a charging station for charging the high-voltage battery can be 400 volts or 800 volts, and the high-voltage battery itself can be 800 volts. The invention further relates to an electric drivetrain for a battery-electric vehicle. The electric drivetrain comprises an electric drive for propelling the vehicle and a previously described, inventive electrical system topology according to one of the preceding claims for supplying the drive with electrical energy. The advantages of the inventive electrical system topology explained above are therefore transferred to the inventive electric drivetrain.

[0025] The invention further relates to a method for operating a previously described on-board electrical system topology or a previously described drive train according to the invention, wherein a high-voltage battery is connected to the high-voltage battery terminal for carrying out the method. The advantages of the on-board electrical system topology according to the invention, as explained above, therefore also apply to the method according to the invention. According to the method, the on-board electrical system topology is switched to the first switching state when the high-voltage input terminal is connected to an (first) electrical charging station that provides an electrical charging voltage that is lower than the high-voltage output voltage of the high-voltage battery.Furthermore, according to the procedure, the on-board network topology is switched to the second switching state when the high-voltage input connection is connected to a (second) electrical charging station that provides an electrical charging voltage equal to the nominal electrical output voltage of the high-voltage battery.

[0026] In a preferred embodiment of the method according to the invention, the vehicle electrical system topology is switched to the second switching state when a motor vehicle with this topology is operating in ferry mode and the electrical system topology is not connected to an electric charging station. The second switching state can also be selected when the motor vehicle is operating in ferry mode, i.e., when no electric charging station is connected to the electrical system topology. In this case, the DC-DC converter can dampen or even completely suppress electrical voltage spikes in the vehicle electrical system topology.

[0027] This reduces the number of filter elements and capacitors required in the vehicle electrical system topology, which are then needed in an inverter connected to that system. This has a positive impact on the manufacturing costs of the vehicle electrical system topology. Depending on the high-voltage battery's state of charge, the DC-DC converter can be used as a boost converter or a buck converter, provided it is equipped with the appropriate functionality and, in particular, is switchable between a "boost converter" and a "buck converter" operating mode.

[0028] In a further preferred embodiment of the method according to the invention, the vehicle electrical system topology is switched to the third switching state for a specific period of time before switching to the second switching state to pre-charge the high-voltage battery. The third switching state allows for particularly reliable pre-charging of a largely or even completely discharged high-voltage battery, whose voltage level, due to the discharge, is far below the charging voltage of typically 800 volts provided by the charging station. In the third switching state, the electrical current flow from the charging station to the high-voltage battery is limited, thereby preventing the occurrence of voltage flashovers or arcing.

[0029] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0030] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0031] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0032] They show, schematically: Fig. 1 in circuit diagram form

[0033] Illustration of an example of a vehicle electrical network topology according to the invention in a first switching state,

[0034] Fig. 2 shows the vehicle electrical system topology of Figure 1 in a second switching state,

[0035] Fig. 3 shows the vehicle electrical system topology of Figure 1 in a third switching state.

[0036] Figure 1 shows, in a circuit diagram-like representation, an example of an on-board network topology 1 according to the invention. The on-board network topology 1 is part of a drive train 20 according to the invention of a battery-electric vehicle, which in turn has an electric drive 21 for propelling the vehicle, which is only roughly schematically indicated in Figure 1.

[0037] According to Figure 1, the vehicle electrical system topology 1 comprises an electrically rechargeable high-voltage battery 2 for providing a high-voltage output voltage V-HV, in particular to the drive 21. Furthermore, the vehicle electrical system topology 1 comprises a high-voltage input terminal 3 and a ground terminal 23, each for connecting the vehicle electrical system topology 1 to an electrical charging station 30, which provides a charging voltage L1-HV that is lower than the high-voltage output voltage V-HV. The high-voltage battery 2 can be electrically charged by transferring energy from the charging station 30 to the vehicle electrical system topology 1.

[0038] The on-board network topology 1 includes a DC-DC converter 4 for converting a high-voltage input voltage HV-E into a higher high-voltage output voltage HV-A. The charging station 30, connected to the high-voltage input terminal 3, is electrically connected to the high-voltage battery 2 via the DC-DC converter 4 in order to transfer electrical energy to the high-voltage battery 2 and thus charge it electrically.

[0039] In this example, the DC-DC converter 4 is configured as a boost converter 11 and comprises a first HV side 12a and a second HV side 12b. The DC-DC converter 4, or boost converter 11, is configured to convert a high-voltage input voltage HV-E provided at the first HV side 12a into a high-voltage output voltage HV-A provided at the second HV side, which is higher than the high-voltage input voltage HV-E. For this purpose, the first HV side 12a can be inductively coupled to the second HV side 12b.

[0040] As shown in Figure 1, the on-board network topology 1 further includes an electrical switch 5 arranged between the DC voltage converter 4 and the high-voltage battery 2 for electrically interrupting the electrical connection between the DC voltage converter 4 and the high-voltage battery 2.

[0041] In the example scenario, the high-voltage battery 2 can be electrically connected to a low-voltage electrical system 14 via a further DC-DC converter 13 to convert the high-voltage output voltage HV-A into a low-voltage voltage NV. The high-voltage battery 2 can also be electrically connected to an onboard charging device 18 via a further electrical switch 19.

[0042] Furthermore, the high-voltage battery 2 can be electrically connected to the electric drive 20 of the drive train 21 via an electrical inverter 22.

[0043] Furthermore, the on-board network topology 1 comprises an electrical bypass 15 with an electrical bypass line 6, which electrically connects the HV input terminal 3 at the DC-DC converter 4 to the high-voltage battery 2. A first and a second electrical bypass switch 7a, 7b are arranged in the electrical bypass 15 and its electrical bypass line 6, respectively, for interrupting the electrical connection between the HV input terminal 3 and the high-voltage battery 2 formed by the bypass 15 and the bypass line 6.

[0044] An electrical parallel circuit 8 is formed in the electrical bypass line 6. The first bypass switch 7a is arranged in a first branch 9a and the second bypass switch in a second branch 9b of this parallel circuit 8. In the second branch 9b of the parallel circuit 8, an impedance 10 in the form of an ohmic resistor 17 is also arranged electrically in series with the second bypass switch 7b. In contrast, no such impedance 10 is arranged in the first branch 9a. The first branch 9a is therefore electrically low-impedance compared to the second branch 9b. The vehicle electrical system topology 1 described above is switchable between a first, a second, and a third switching state.

[0045] In the first switching state shown in Figure 1, the electrical switch 5 between the DC-DC converter 4 and the high-voltage battery 2 is closed, so that the DC-DC converter 4 is electrically connected to the high-voltage battery 2 via the switch. Furthermore, in the first switching state, all bypass switches 7a, 7b in the bypass line 6 are open, so that the electrical connection between the HV input terminal 3 and the high-voltage battery 2 via the bypass line 6 is interrupted.

[0046] In the method according to the invention, the on-board network topology 1, as shown in Figure 1, is switched to the first switching state when the HV input terminal 3 is connected to, or is connected to, the electrical charging station 30 shown, which provides an electrical charging voltage V-L1 that is lower than the HV output voltage HV-A of the high-voltage battery 2. In the course of the method according to the invention, the on-board network topology 1 is switched to the second switching state when the HV input terminal 3 is connected to, or is connected to, an electrical charging station 31 that provides an electrical charging voltage V-L2 that is equal to the HV output voltage HV-A of the high-voltage battery 2.

[0047] In contrast to the first switching state, in the second switching state the electrical switch 5 between the DC-DC converter 4 and the high-voltage battery 2 is open, thus interrupting the electrical connection between the DC-DC converter 4 and the high-voltage battery 2 via this switch 5. Furthermore, in the second switching state the first bypass switch 7a is closed and the second bypass switch 7b is open. In this switching state, the charging voltage is not increased. The second switching state can also be selected when the vehicle is in operation, i.e., when no electrical charging station 31 is connected to the vehicle electrical system topology 1. In this case, the DC-DC converter 4 can dampen or even completely suppress electrical voltage spikes in the vehicle electrical system topology. This reduces the number of filter elements and capacitances required in an electrical inverter 22 connected to the vehicle electrical system topology 1.Figure 3 shows the on-board network topology 1 in the third switching state.

[0048] According to the inventive method, the on-board network topology 1 can be switched to the third switching state for a specific period of time before switching to the second switching state in order to pre-charge the high-voltage battery 2. The third switching state differs from the second switching state in that the first bypass switch 7a is open and the second bypass switch 7b is closed. Furthermore, in the third switching state, the electrical switch 5 between the DC-DC converter 4 and the high-voltage battery 2 is open.

[0049] The on-board network topology 1 can also be equipped with a control / regulation device 16 for controlling the electrical switch 5 or the electrical bypass switches 7a, 7b and thus for switching between the switching states.

Claims

Patent claims 1. On-board electrical system topology (1) for a powertrain (20) of a battery-electric vehicle, comprising a high-voltage battery connection (2a) for connecting an electrically rechargeable high-voltage battery (2) for providing an electrical high-voltage output voltage (V-HV), comprising an electrical HV input connection (3) for connecting the on-board electrical system topology (1) to an electrical charging station (30, 31) for charging the high-voltage battery (2), comprising a DC-DC converter (4) for converting a high-voltage input voltage (HV-E) provided at the HV input connection (3) into a higher high-voltage output voltage (HV-A) than the high-voltage input voltage (HV-E), wherein the HV input connection (3) can be electrically connected to or is connected to the high-voltage battery (2) via the DC-DC converter (4),with an electrical switch (5) arranged between the DC-DC converter (4) and the high-voltage battery terminal (2a) for electrically interrupting this electrical connection between the DC-DC converter (4) and the high-voltage battery (2), with an electrical bypass (15) comprising an electrical bypass line (6) by which the HV input terminal (3) at the DC-DC converter (4) can be electrically connected to the high-voltage battery terminal (2a) or is connected by way of a bypass, wherein at least one electrical bypass switch (7a, 7b) for interrupting this electrical connection is arranged in the bypass (15), in particular in the bypass line (6).

2. On-board network topology according to claim 1 , characterized in that the on-board network topology (1) is designed to be switchable between a first and a second switching state, in the first switching state the electrical switch (5) between the DC-DC converter (4) and the high-voltage battery terminal (2a) is closed, so that the DC-DC converter (4) is electrically connected to the high-voltage battery terminal (2a) via the electrical switch (5), in the first switching state all bypass switches (7a, 7b) present in the bypass line (6) are open, so that the electrical connection between the HV input terminal (3) and the high-voltage battery terminal (2a) is interrupted via the bypass line (6), in the second switching state the electrical switch (5) between the DC-DC converter (4) and the high-voltage battery (2) is open and thus the electrical connection between the DC-DC converter (4) and the high-voltage battery terminal (2a) is interrupted via this switch (5),In the second switching state, the high-voltage input terminal (3) is electrically connected to the high-voltage battery (2) via the electrical bypass (15), and preferably at least one bypass switch (7a, 7b) is closed for this purpose.

3. On-board network topology according to claim 1 or 2, characterized in that a first and a second electrical bypass switch are provided in the bypass line (6). (7a, 7b) are provided, the first bypass switch (7a) is arranged in a first branch (9a) and the second bypass switch is arranged in a second branch (9b) of an electrical parallel circuit (8) formed in the bypass line (6), and in the second branch (9b) of the parallel circuit (8) an impedance (10), in particular an ohmic resistance, (17) is arranged electrically in series with the second bypass switch (7b).

4. On-board network topology according to claim 2 or 3, characterized in that in the second switching state the first bypass switch (7a) is closed and the second bypass switch (7b) is open, the on-board network topology (1) can be switched to a third switching state in which the first bypass switch (7a) is open and the second bypass switch (7b) is closed.

5. On-board network topology according to claim 4, characterized in that in the third switching state the electrical switch (5) between DC voltage converter (4) and high-voltage battery (2) is open.

6. On-board network topology according to one of the preceding claims, characterized in that the DC-DC converter (4) is designed as a boost converter (11) and comprises a first HV side (12a) and a second HV side (12b) and is configured to convert a high-voltage electrical input voltage (HV-E) provided at the first HV side into a high-voltage electrical output voltage (HV-A) provided at the second HV side, which is greater than the high-voltage electrical input voltage (HV-E), preferably the first HV side (12a) is inductively coupled to the second HV side (12b).

7. On-board network topology according to one of the preceding claims, characterized in that the high-voltage battery connection (2a) can be electrically connected or is connected to a low-voltage on-board network (14) via a further DC voltage converter (13) for converting the electrical high-voltage output voltage (HV-A) into an electrical low voltage (NV).

8. On-board network topology according to one of the preceding claims, characterized in that the electrical charging voltage (L1-V, L1-V) is 400 volts or 800 volts, the nominal output voltage (V-HV) of the high-voltage battery (2) is 800 volts.

9. Powertrain (20) for a battery-electric vehicle, comprising an electric drive (21) for propelling the vehicle, with an on-board network topology (1) according to one of claims 1 to 8 for supplying the drive (21) with electrical energy.

10. Method for operating an on-board electrical system topology (1) according to one of claims 2 to 8 or a powertrain (20) according to claim 9, wherein a high-voltage battery (2) is connected to the high-voltage battery connection (2a), according to which the on-board electrical system topology (1) is switched to the first switching state when the HV input connection (3) is connected to a (first) electrical charging station (30) that provides an electrical charging voltage (V-L1) that is lower than the HV output voltage (HV-A) of the high-voltage battery (2), according to which the on-board electrical system topology (1) is switched to the second switching state when the HV input connection (3) is connected to a (second) electrical charging station (31) that provides an electrical charging voltage (V-L2) that is equal to the HV output voltage (HV-A) of the high-voltage battery (2).

11. Method according to claim 10, characterized in that the on-board network topology is switched to the second switching state in a state in which a motor vehicle with the on-board network topology is in ferry operation and the on-board network topology is not connected to an electric charging station.

12. Method according to claim 10 or 11, when referring back to one of claims 4 to 8, characterized in that the on-board network topology (1) is switched to the third switching state for a certain period of time to pre-charge the high-voltage battery (2) before switching to the second switching state.

Images