Vehicle having high-voltage on-board electrical system and method for operating high-voltage on-board electrical system

Abstract

The invention relates to a vehicle (4) having a high-voltage on-board electrical system (3) with a traction battery (5), a charging interface (6) for coupling a DC charging station (2), a high-voltage potential line (HV + L, HV-L) and a reference potential line (ML). According to the invention, a direct current-direct current converter (7) is arranged in one of the high-voltage potential lines (HV + L, HV-L) and a series circuit comprising a varistor (8) and a current measuring device (9) is arranged between the other high-voltage potential line (HV + L, HV-L) and the reference potential line (ML), and when the current intensity measured by the current measuring device (9) exceeds at least one specified limit value, the varistor (8) and the current measuring device (9) are connected to the reference potential line (ML). A processing unit (10) coupled to the current measuring device (9) and the DC-DC converter (7) turns off the DC-DC converter (7); or a respective DC-DC converter (7) is arranged in the two high-voltage potential lines (HV + L, HV-L) and a respective series circuit comprising a varistor (8) and a current measuring device (9) is arranged between each high-voltage potential line (HV + L, HV-L) and the reference potential line (ML), wherein a processing unit (10) coupled to the respective current measuring device (9) and the DC-DC converter (7) switches off the DC-DC converter (7) when the current intensity measured by at least one of the current measuring devices (9) exceeds at least one specified limit value.

Description

Technical Field

[0001] The invention relates to a vehicle having a high-voltage on-board electrical system and a method for operating a high-voltage on-board electrical system according to the features of the preamble of claim 1 . Background Art

[0002] For example, as described in DE 10 2017 009 352 A1, an energy coupler for electrically coupling an onboard electrical system and an electrical coupling method for an onboard electrical system are known in the prior art. An energy coupler for electrically coupling a first onboard electrical system to which a first DC voltage is applied and a second onboard electrical system to which a second DC voltage is applied has a first clocked and a second clocked energy converter, each of which has an onboard electrical system interface and an intermediate circuit interface. The onboard electrical system interface of the first clocked energy converter is connected to the first onboard electrical system, while the onboard electrical system interface of the second clocked energy converter is connected to the second onboard electrical system. The intermediate circuit interfaces of the first clocked and the second clocked energy converters are connected to the same intermediate DC circuit. The first potential of the intermediate DC circuit is electrically connected to one of the potentials of the first onboard electrical system by means of the first clocked energy converter. The second potential of the intermediate DC circuit is electrically connected to one of the potentials of the second onboard electrical system by means of the second clocked energy converter. Summary of the invention

[0003] The object of the present invention is to specify a vehicle with an improved high-voltage onboard electrical system and an improved method for operating a high-voltage onboard electrical system in view of the prior art.

[0004] According to the invention, this object is achieved by a vehicle having a high-voltage on-board electrical system having the features of claim 1 and a method for operating a high-voltage on-board electrical system having the features of claim 6 .

[0005] Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0006] The vehicle has a high-voltage on-board electrical system. The term “high voltage”, also abbreviated to HV, refers in particular to a DC voltage, in particular above approximately 60 V. The term “high voltage” should be designed in particular in accordance with standard ECE R 100.

[0007] The high-voltage on-board electrical system has a traction battery, a charging interface for electrically coupling with a DC charging station outside the vehicle, a high-voltage positive potential line, a high-voltage negative potential line, and a reference potential line. The traction battery is designed to supply power to at least one electric drive device to drive the vehicle. Therefore, the vehicle is particularly an electric vehicle or a hybrid vehicle.

[0008] In one embodiment according to the present invention, a DC-DC converter is arranged in one of the high-voltage potential lines, and a series circuit including a varistor and a current measuring device is arranged between the other high-voltage potential lines and the reference potential line. In addition, in this embodiment according to the present invention, a processing unit coupled to the current measuring device and the DC-DC converter is designed, which is designed and arranged to shut down the DC-DC converter when the current intensity measured by the current measuring device exceeds at least one specified limit value.

[0009] In the method for operating a high-voltage on-board electrical system of a vehicle according to the present invention, it is accordingly designed that the current measuring device is analyzed by the processing unit and the DC-DC converter is shut down when the current intensity measured by the current measuring device exceeds at least one specified limit value.

[0010] In an alternative embodiment according to the present invention, it is designed to arrange a DC-DC converter in each of the two high-voltage potential lines, and to arrange a series circuit including a varistor and a current measuring device between each high-voltage potential line and the reference potential line. In addition, in this alternative embodiment according to the present invention, a processing unit coupled to the corresponding current measuring device and the DC-DC converter is designed, which is designed and arranged to shut down the DC-DC converter when the current intensity measured by at least one current measuring device in the current measuring devices exceeds at least one specified limit value.

[0011] In the method for operating a high-voltage on-board electrical system of a vehicle according to the present alternative embodiment, it is accordingly designed that the current measuring devices are analyzed by a processing unit and the DC-DC converter is shut down when the current intensity measured by at least one of the current measuring devices exceeds at least one specified limit value.

[0012] By using a DC-DC converter or two DC-DC converters, it is possible to charge the traction battery at a DC charging station using a charging voltage lower than the battery voltage of the traction battery, for example, using a charging voltage of 400V or 500V to charge an 800V traction battery at a DC charging station. The DC-DC converter or the corresponding DC-DC converter is particularly designed as a DC-coupled DC-DC converter. This is a cost-effective and space-saving solution. However, the problem is that once an insulation fault occurs in the vehicle, the direct consequence may be another insulation fault in the reverse potential on the DC charging station side. In order to protect the insulation device, some DC charging station manufacturers install a varistor between the reference potential and the high-voltage positive potential or between the reference potential and the high-voltage negative potential in the DC charging station. The varistor in the DC charging station has a clamping voltage of 500V to 550V, for example. If the varistor is triggered in the DC charging station or the insulation is destroyed, this can lead to a short circuit in the traction battery, which in the so-called CHAdeMO charging standard can lead to the destruction of the ground potential line in the charging line, which is used for the electrical coupling to the DC charging station, because the ground potential line is designed to be very thin. Currently, the following limit values ​​are defined: 100 mAs for protecting the varistor in the DC charging station and 7000 mAs2 for protecting the ground potential line in the charging line.

[0013] This problem is solved by the solution described in the present invention, because in the solution described in the present invention, if an insulation fault occurs in the high-voltage system of the vehicle, which may then cause the insulation device on the DC charging station side to be subjected to an excessively high voltage, the relevant varistor of the vehicle's high-voltage on-board electrical system will first transition to a low-resistance state. For this purpose, it is particularly designed that the varistor in the first embodiment according to the present invention or the corresponding varistor in the alternative embodiment according to the present invention is designed to transition to a low-resistance state when a specified voltage is exceeded that is lower than the design voltage of the DC charging station outside the vehicle (for example, 500V), and the charging interface is designed for electrical coupling of the DC charging station outside the vehicle. In this way, the specified voltage is, for example, 450V. Therefore, it is particularly designed that the varistor or the corresponding varistor has a corresponding characteristic curve. In this way, before exceeding the design voltage of the DC charging station, the varistor has already transitioned to a low-resistance state.

[0014] By means of current measurement by means of the associated current measuring device, the resulting conductive path can be measured quickly and accurately. By means of an analysis by means of a processing unit, this measured current, i.e. its current intensity, is compared with at least one specified limit value or with a plurality of specified limit values ​​and, if necessary (i.e. when exceeded), the DC-DC converter is switched off very quickly, i.e. its function is stopped.

[0015] For example, the processing unit is designed to be coupled to the contactor of the traction battery and / or a disconnection element arranged in at least one of the high-voltage potential lines. The processing unit is designed and arranged to activate the contactor and / or at least one disconnection element for disconnection if the current intensity measured by the current measuring device in the first embodiment of the invention or by at least one of the two current measuring devices in the alternative embodiment of the invention exceeds at least one specified limit value. Accordingly, if the current intensity measured by the current measuring device in the first embodiment of the invention or by at least one of the two current measuring devices in the alternative embodiment of the invention exceeds at least one specified limit value, the operating method is designed, for example, for the processing element to activate the contactor and / or at least one disconnection element for disconnection. In addition, in this way, in addition to the above-mentioned shutdown of the DC-DC converter, in order to eliminate the short-circuit current, the traction battery is also very quickly prompted to disconnect its contactor and / or activate one or more disconnection elements, thereby cutting off the short-circuit current. The disconnecting element or the corresponding disconnecting element is designed, for example, as a semiconductor switch, a diode or an exploding fuse, i.e. as a pyrotechnic disconnecting element (also called a pyrotechnic fuse). Compared to a short circuit of the traction battery caused by a short circuit of the conductive insulation in the DC charging station, since at this earlier moment the current values ​​of the varistor with a lower resistance value are still lower, the disconnecting element and, for example, the contactor of the traction battery can be designed smaller, since the short-circuit current does not need to be taken into account in the design.

[0016] The solution according to the invention therefore makes it possible to detect quickly and accurately whether a defined high-voltage potential deviation has been exceeded in the vehicle's high-voltage onboard electrical system by current measurement, and then to stop the function of the DC-DC converter at an early stage. In this way, the varistors in the DC charging station or the insulation devices in the DC charging station will not be overloaded due to overvoltage, because the voltage is limited to a value below the designed insulation resistance by the varistor in the high-voltage onboard electrical system. In addition, it is possible to avoid the varistors of the DC charging station and the ground potential line of the charging line being damaged or destroyed due to large currents, because the generated traction battery short-circuit current is retained inside the vehicle by the varistor in the high-voltage onboard electrical system. In addition, by means of the solution according to the invention, erroneous charging interruptions can be avoided, because, unlike other solutions, this solution can accurately detect faults. In addition, due to the lower varistor triggering voltage in the high-voltage onboard electrical system, the occurring faults can be detected more quickly, in this way, the resulting battery current is still limited by the varistor resistance. In this way, smaller disconnection elements and / or contactors can be selected for shutdown, because large short-circuit currents do not need to be taken into account during the design.

[0017] In summary, in the event of an insulation fault, the solution described enables rapid initiation of safety measures using a low-resistance varistor based on the analysis of the current measurement by comparison with one or more specified current intensity limit values, in particular early shutdown of the DC-DC converter and early disconnection of the contactor and / or the disconnecting element, for example at low currents, thereby achieving the further advantages described. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the present invention are explained in more detail below with reference to the accompanying drawings.

[0019] In the attached figure:

[0020] Figure 1 An embodiment of a high-voltage onboard electrical system of a vehicle electrically connected to a DC charging station via a charging cable is schematically shown. DETAILED DESCRIPTION

[0021] Figure 1 An embodiment of a high-voltage onboard electrical system 3 of a vehicle 4 electrically connected to a DC charging station 2 via a charging cable 1 is schematically shown.

[0022] The vehicle 4 is in particular an electric vehicle or a hybrid vehicle, ie it has at least one electric drive for its drive. In order to supply power to the at least one electric drive, the high-voltage on-board electrical system 3 has a traction battery 5 .

[0023] Furthermore, the high-voltage onboard electrical system 3 has a charging interface 6 for electrical coupling to the vehicle-external DC charging station 2 . This is done via a charging cable 1 which is implemented or already electrically coupled to the DC charging station 2 and the charging interface 6 .

[0024] In addition, the high-voltage vehicle electrical system 3 has a high-voltage positive potential line HV+L, a high-voltage negative potential line HV-L and a reference potential line ML, in particular, a ground potential line. Figure 1 As shown, this also applies to the charging cable 1 and the DC charging station 2 .

[0025] In addition, in the high-voltage vehicle electrical system 3, in particular, an insulation resistor Riso+BN is designed between the high-voltage positive potential line HV+L and the reference potential line ML, an insulation resistor Riso-BN is designed between the high-voltage negative potential line HV+L and the reference potential line ML, a Y capacitor C+BN is designed between the high-voltage positive potential line HV+L and the reference potential line ML, and a Y capacitor C-BN is designed between the high-voltage negative potential line HV+L and the reference potential line ML.

[0026] Similarly, in the DC charging station 2, an insulation resistor Riso+LS is specifically designed between the high-voltage positive potential line HV+L and the reference potential line ML, an insulation resistor Riso-LS is designed between the high-voltage negative potential line HV+L and the reference potential line ML, a Y capacitor C+LS is designed between the high-voltage positive potential line HV+L and the reference potential line ML, and a Y capacitor C-LS is designed between the high-voltage negative potential line HV+L and the reference potential line ML.

[0027] The high-voltage on-board electrical system 3 is designed in particular to charge the traction battery 5 at the DC charging station 2 with a charging current lower than the battery voltage of the traction battery 5, for example, to charge an 800V traction battery at the DC charging station 2 with a charging voltage of 400V or 500V. For example, a traction battery 5 with a battery voltage of 800V is designed, and the DC charging station 2 has a charging voltage of 500V, which is also referred to as the design voltage. In order to realize the above-mentioned charging of the traction battery 5, the high-voltage on-board electrical system 3 has a DC-DC converter 7, which is arranged in the high-voltage positive potential line HV+L of the high-voltage on-board electrical system 3 in the embodiment shown. The DC-DC converter 7 is designed as a DC-coupled DC-DC converter 7.

[0028] But the problem is that once an insulation fault occurs in the vehicle 4, the direct consequence may be another insulation fault in the reverse potential on the DC charging station 2 side. In order to protect the insulation device, some DC charging station manufacturers install a varistor (not shown here) between the reference potential and the high-voltage positive potential or between the reference potential and the high-voltage negative potential in the DC charging station 2. The varistor in the DC charging station 2 has a clamping voltage of 500V to 550V, for example. If the varistor is triggered in the DC charging station 2 or the insulation device is damaged, it will cause the traction battery 5 to short-circuit, which in the so-called CHAdeMO charging standard will cause the ground potential line (i.e., the reference potential line ML) in the charging line 1 to be damaged because the ground potential line is designed to be very thin. At present, the following limit values ​​are defined: 100mAs is used to protect the varistor in the DC charging station 2 and 7000As2 is used to protect the ground potential line in the charging line 1.

[0029] exist Figure 1 In FIG. 5 , the current flow direction of the normal charging current during the charging process of the traction battery 5 is shown by means of the first arrow P1. Figure 1 The fault situation is shown in FIG. 4 by means of a fault icon FS. In the example shown, as shown by the connecting line through the insulation resistor Riso+BN, the high voltage positive potential is conductively connected to the reference potential due to an insulation fault in the vehicle 4. The short-circuit current flowing in the high voltage onboard electrical system 3 is shown by means of a second arrow P2.

[0030] In order to solve the above problem, in the embodiment shown, a series circuit including a varistor 8 and a current measuring device 9 is arranged between the high voltage negative potential line HV-L and the reference potential line ML.

[0031] In an alternative embodiment not shown, the DC-DC converter 7 is arranged in the high-voltage negative potential line HV-L of the high-voltage onboard electrical system 3 and is also designed as a DC-coupled DC-DC converter 7. Next, it is correspondingly designed to arrange a series circuit including a varistor 8 and a current measuring device 9 between the high-voltage negative potential line HV+L and the reference potential line ML. In this case, a corresponding fault situation can be detected, that is, the high-voltage negative potential is conductively connected to the reference potential due to an insulation fault in the vehicle 4.

[0032] Whether in the described embodiment or in another embodiment not shown, a processing unit 10 coupled to the current measuring device 9 and the DC-DC converter 7 is also designed, which is designed and arranged to shut down the DC-DC converter 7 when the current intensity measured by the current measuring device 9 exceeds at least one specified limit value.

[0033] In the method for operating high-voltage onboard electrical system 3 of vehicle 4 , it is accordingly provided that processing unit 10 evaluates current measuring device 9 and switches off DC-DC converter 7 when the current intensity measured by current measuring device 9 exceeds at least one specified limit value.

[0034] The problem is solved by means of the implementation of the high-voltage on-board electrical system 3, that is, if an insulation fault occurs in the vehicle 4, resulting in the insulation device on the DC charging station 2 side being subjected to an excessively high voltage, the varistor 8 of the high-voltage on-board electrical system 3 of the vehicle 4 will first transition to a low resistance state. In order to ensure this, it is proposed to design the varistor 8 to transition to a low resistance state when a specified voltage is exceeded that is lower than the design voltage of the DC charging station 2 outside the vehicle (for example, 500V). In this case, the specified voltage is, for example, 450V. Thus, in particular, the varistor 8 is designed to have a corresponding characteristic curve. In this way, the varistor will have transitioned to a low resistance state before exceeding the design voltage of the DC charging station 2.

[0035] The resulting conductive path can be measured quickly and accurately by means of the current measurement of the current measuring device 9. This measured current (i.e. its current intensity) is compared with at least one specified limit value or with a plurality of specified limit values ​​by means of an analysis by means of the processing unit 10 and, if necessary (i.e. when exceeded), the DC-DC converter 7 is switched off very quickly, i.e. its function is stopped.

[0036] For example, it can be additionally designed that the processing unit 10 is coupled to a contactor (not shown here) of the traction battery 5 and / or a disconnection element 11 arranged in at least one of the high-voltage potential lines HV+L, HV-L of the high-voltage on-board electrical system 3. The processing unit is designed and arranged to activate the contactor and / or at least one disconnection element 11 for disconnection when the current intensity measured by the current measuring device 9 exceeds at least one specified limit value. Accordingly, for example, in the operating method, it is designed that when the current intensity measured by the current measuring device 9 exceeds at least one specified limit value, the processing unit 10 activates the contactor and / or at least one disconnection element 11 for disconnection. In addition, in this way, in addition to the above-mentioned shutdown of the DC-DC converter 7, in order to eliminate the short-circuit current, the traction battery 5 is also very quickly prompted to disconnect its contactor and / or activate one or more disconnection elements 11, thereby cutting off the short-circuit current. As shown in the example shown, the disconnection element 11 or the corresponding disconnection element 11 is designed, for example, as a diode or a semiconductor switch or an exploding fuse. Compared to a short circuit of the traction battery 5 caused by a short circuit of the conductive insulation in the DC charging station 2, since at this earlier moment the current value of the varistor 8 with a lower resistance value is still lower, the disconnecting element 11 or a corresponding disconnecting element 11 and, for example, a contactor of the traction battery 5 can be designed to be smaller, because the short-circuit current does not need to be taken into account during the design.

[0037] In another embodiment not shown, a DC-DC converter 7 of a high-voltage onboard electrical system 3 is arranged in each of the high-voltage positive potential line HV+L and the high-voltage negative potential line HV-L, and is also designed as a DC-coupled DC-DC converter 7. Accordingly, a series circuit including a varistor 8 and a current measuring device 9 is arranged between each high-voltage negative potential line HV+L, HV-L and the reference potential line ML. In this case, a fault condition can be detected, i.e., the high-voltage positive potential is conductively connected to the reference potential due to an insulation fault in the vehicle 4, and a fault condition can be detected, i.e., the high-voltage negative potential is conductively connected to the reference potential due to an insulation fault in the vehicle 4.

[0038] For this embodiment, a processing unit 10 coupled to the corresponding current measuring device 9 and the DC-DC converter 7 is designed accordingly, and is designed and arranged to shut down the DC-DC converter 7 when the current intensity measured by at least one current measuring device in the current measuring device 9 exceeds at least one specified limit value.

[0039] In the method for operating the high-voltage onboard electrical system 3 of the vehicle 4, it is accordingly designed that the current measuring devices 9 are analyzed by the processing unit 10 and the DC-DC converter 7 is shut down when the current intensity measured by at least one of the current measuring devices 9 exceeds at least one specified limit value.

[0040] The problem is also solved by means of this embodiment of the high-voltage on-board electrical system 3, that is, if a corresponding insulation fault occurs in the vehicle 4, resulting in the insulation device on the DC charging station 2 side being subjected to an excessively high voltage, the relevant varistor 8 of the high-voltage on-board electrical system 3 of the vehicle 4 will first transition to a low resistance state. For this reason, in the present embodiment, it is accordingly proposed that the varistor 8 is particularly designed to transition to a low resistance state when a specified voltage (for example, 500V) is exceeded that is lower than the design voltage of the DC charging station 2 outside the vehicle. In this way, the specified voltage is, for example, 450V. Thus, it is particularly designed that the corresponding varistor 8 has a corresponding characteristic curve. In this way, before exceeding the design voltage of the DC charging station 2, the varistor will have already transitioned to a low resistance state. Therefore, the two varistors 8 are respectively designed in this way in this embodiment.

[0041] For this embodiment, the resulting conductive path can also be measured quickly and accurately by means of current measurement by the associated current measuring device 9. By means of analysis by means of the processing unit 10, this measured current (i.e. its current intensity) is compared with at least one specified limit value or with a plurality of specified limit values ​​and, if necessary (i.e. when exceeded), the DC-DC converter 7 is switched off very quickly, i.e. its function is stopped.

[0042] Additionally, in this embodiment, the processing unit 10 can also be designed to be coupled to the contactor of the traction battery 5 and / or the disconnection element 11 arranged in at least one of the high-voltage potential lines HV+L, HV-L of the high-voltage on-board electrical system 3. The processing unit is designed and arranged to activate the contactor and / or at least one disconnection element 11 for disconnection when the current intensity measured by at least one of the two current measuring devices 9 exceeds at least one specified limit value. Accordingly, for example, in the operating method, it is designed that when the current intensity measured by at least one of the two current measuring devices 9 exceeds at least one specified limit value, the processing unit 10 activates the contactor and / or at least one disconnection element 11 for disconnection. In addition, in this way, in addition to the above-mentioned shutdown of the DC-DC converter 7, in order to eliminate the short-circuit current, the traction battery 5 is also very quickly prompted to disconnect its contactor and / or activate one or more disconnection elements 11, thereby cutting off the short-circuit current. For example, the disconnection element 11 or the corresponding disconnection element 11 can also be designed as a semiconductor switch, a diode or an exploding fuse. Compared to a short circuit of the traction battery 5 caused by a short circuit of the conductive insulation in the DC charging station 2, since at this earlier moment the current value of the varistor 8 with a lower resistance value is still lower, the disconnecting element 11 or a corresponding disconnecting element 11 and, for example, a contactor of the traction battery 5 can be designed to be smaller, because the short-circuit current does not need to be taken into account during the design.

[0043] Reference numerals list

[0044] 1 Charging cable

[0045] 2 DC Charging Stations

[0046] 3 High-voltage on-board electrical system

[0047] 4 Vehicles

[0048] 5 Traction battery

[0049] 6 Charging port

[0050] 7 DC-DC Converter

[0051] 8. Varistor

[0052] 9 Current measuring device

[0053] 10 Processing Units

[0054] 11 Breaking element

[0055] C+BN High Voltage Vehicle Electrical System Y Capacitor

[0056] C-BN High Voltage Vehicle Electrical System Y Capacitor

[0057] C+LS Charging Station Y Capacitor

[0058] C-LS Charging Station Y Capacitor

[0059] FS Fault Icon

[0060] HV+L High voltage positive potential line

[0061] HV-L High voltage negative potential line

[0062] ML reference potential line

[0063] P1 First Arrow

[0064] P2 Second arrow

[0065] Riso+BN Insulation resistance of high voltage on-board electrical system

[0066] Riso-BN High Voltage On-board Electrical System Insulation Resistance

[0067] Riso+LS Charging Station Insulation Resistance

[0068] Riso-LS Charging Station Insulation Resistance

Claims

1. A vehicle (4) having a high voltage on-board electrical system (3), wherein: The high-voltage on-board electrical system (3) comprises: - a traction battery (5), - a charging interface (6) for electrical coupling with a DC charging station (2) external to the vehicle, - High voltage positive potential line (HV+L), - High Voltage Negative Potential Line (HV-L), and - Reference potential line (ML), It is characterized in that - a DC-DC converter (7) is arranged in one of the high voltage potential lines (HV+L, HV-L), and a series circuit including a varistor (8) and a current measuring device (9) is arranged between the other high voltage potential line (HV+L, HV-L) and the reference potential line (ML), wherein a series circuit connected to the current measuring device (9) and the DC - a processing unit (10) coupled to the DC-DC converter (7), the processing unit being designed and arranged to switch off the DC-DC converter (7) and thereby stop the function of the DC-DC converter (7) when the current intensity measured by the current measuring device (9) exceeds at least one specified limit value, or - the DC-DC converter (7) is arranged in each of the two high-voltage potential lines (HV+L, HV-L), and a series circuit including the variable resistor (8) and the current measuring device (9) is arranged between each of the high-voltage potential lines (HV+L, HV-L) and the reference potential line (ML), wherein a processing unit (10) coupled to the corresponding current measuring device (9) and the DC-DC converter (7) is designed, The processing unit is designed and arranged to switch off the DC-DC converter (7) when the current intensity measured by at least one of the current measuring devices (9) exceeds at least one specified limit value, thereby stopping the function of the DC-DC converter (7).

2. The vehicle (4) according to claim 1, It is characterized in that The varistor (8) or the corresponding varistor (8) is designed to transition to a low resistance state when a specified voltage is exceeded that is lower than the design voltage of the vehicle-external DC charging station (2), and the charging interface (6) is designed for electrical coupling to the vehicle-external DC charging station (2).

3. The vehicle (4) according to any one of the preceding claims, It is characterized in that The DC-DC converter (7) or the corresponding DC-DC converter (7) is designed as a DC-coupled DC-DC converter (7).

4. The vehicle (4) according to any one of the preceding claims, It is characterized in that The processing unit (10) is coupled to a contactor of the traction battery (5) and / or a disconnecting element (11) arranged in at least one of the high-voltage potential lines (HV+L, HV-L), and is designed and arranged to activate the contactor and / or at least one disconnecting element (11) for disconnection when the current intensity measured by the current measuring device (9) or at least one of the two current measuring devices (9) exceeds at least one specified limit value.

5. The vehicle (4) according to any one of the preceding claims, It is characterized in that The disconnecting element (11) is designed as a semiconductor switch, a diode or an exploding fuse.

6. A method for operating a high-voltage on-board electrical system (3) of a vehicle (4) according to any one of the preceding claims, It is characterized in that The processing unit (10) analyses the current measuring device (9) and switches off the DC-DC converter (7) when the current intensity measured by the current measuring device (9) exceeds at least one specified limit value, or The processing unit (10) analyses the current measuring devices (9) and switches off the DC-DC converter (7) when the current intensity measured by at least one of the current measuring devices (9) exceeds at least one specified limit value.

7. The method according to claim 6, It is characterized in that When the current intensity measured by the current measuring device (9) or at least one of the two current measuring devices (9) exceeds at least one specified limit value, the processing unit (10) activates a contactor and / or at least one of the disconnecting elements (11) for disconnection.

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