Vehicle equipped with a high-voltage in-vehicle electrical system and method for operating a high-voltage in-vehicle electrical system

Abstract

The present invention relates to a vehicle (4) comprising a high-voltage in-vehicle electrical system (3) having an electric vehicle battery (5), a charging terminal (6) for connection to a DC charging station (2), high-voltage potential lines (HV+L, HV-L), and a reference potential line (ML). According to the present invention, a DC-DC 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). When the current intensity measured by the current measuring device (9) exceeds at least one predetermined limit value, a processing unit (10) connected to the current measuring device (9) and the DC-DC converter (7) switches off the DC-DC converter (7), or DC-DC converters (7) are respectively arranged in the two high-voltage potential lines (HV+L, HV-L), and series circuits each comprising a varistor (8) and a current measuring device (9) are respectively arranged between each high-voltage potential line (HV+L, HV-L) and the reference potential line (ML). When the current intensity measured by at least one of the current measuring devices (9) exceeds at least one predetermined limit value, the processing unit (10) connected to each current measuring device (9) and the DC-DC converter (7) switches off the DC-DC converter (7).

Description

Technical Field

[0001] The present invention relates to a vehicle equipped with a high-voltage in-vehicle electrical system having the characteristics of the superordinate concept of claim 1 and a method for operating the high-voltage in-vehicle electrical system.

Background Art

[0002] From the prior art as described in Patent Document 1, an energy coupler for electrically connecting an in-vehicle electrical system and a method for electrically connecting an in-vehicle electrical system are known. An energy coupler for electrically connecting a first in-vehicle electrical system to which a first DC voltage is applied to a second in-vehicle electrical system to which a second DC voltage is applied has a first clock-controlled energy converter and a second clock-controlled energy converter, each having an in-vehicle electrical system terminal and an intermediate circuit terminal. The in-vehicle electrical system terminal of the first clock-controlled energy converter is connected to the first in-vehicle electrical system, and the in-vehicle electrical system terminal of the second clock-controlled energy converter is connected to the second in-vehicle electrical system. The intermediate circuit terminals of the first clock-controlled energy converter and the second clock-controlled energy converter are connected to a common DC intermediate circuit. The first potential of the DC intermediate circuit is electrically connected to one of the potentials of the first in-vehicle electrical system using the first clock-controlled energy converter. The second potential of the DC intermediate circuit is electrically connected to one of the potentials of the second in-vehicle electrical system using the second clock-controlled energy converter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem underlying the present invention is to provide a vehicle equipped with a high-voltage on-vehicle electrical system improved over the prior art, and an improved method for operating the high-voltage on-vehicle electrical system.

Means for Solving the Problem

[0005] According to the present invention, this problem is solved by a vehicle equipped with a high-voltage on-vehicle electrical system having the features of claim 1 and a method for operating the high-voltage on-vehicle electrical system having the features of claim 6. Advantageous embodiments of the present invention are the subject matter of the dependent claims.

[0006] The vehicle has an electrical high-voltage on-vehicle electrical system. The term "high voltage", also abbreviated as HV, is understood in particular to be a DC voltage greater than about 60V. In particular, the term "high voltage" must be interpreted in accordance with the standard ECE R 100.

[0007] The high-voltage on-vehicle electrical system has an electric vehicle battery, a charging terminal for electrically connecting to a DC charging station outside the vehicle, a high-voltage positive potential line, a high-voltage negative potential line, and a reference potential line. At least one electrical drive mechanism for driving the vehicle is provided in the electric vehicle battery for electrical energy supply. Accordingly, the vehicle is in particular an electric vehicle or a hybrid vehicle.

[0008] In one embodiment according to the present invention, a DC-DC converter is arranged on one of the high-voltage potential lines, and a series circuit consisting of a varistor and a current measuring device is arranged between the other high-voltage potential line and the reference potential line. Further, in an embodiment according to the present invention, a processing unit connected to the current measuring device and the DC-DC converter is provided, and this processing unit is designed and configured to switch off the DC-DC converter when the current intensity measured by the current measuring device exceeds at least one predetermined limit value.

[0009] In the method according to the invention for operating the high-voltage in-vehicle electrical system of a vehicle in this embodiment, correspondingly, the current measuring device is evaluated by the processing unit, and when the current intensity measured by the current measuring device exceeds at least one predetermined limit value, the DC-DC converter is switched off.

[0010] In an alternative embodiment according to the invention, a DC-DC converter is arranged on each of two high-voltage potential lines, and a series circuit consisting of a varistor and a current measuring device is arranged between each high-voltage potential line and the reference potential line. Further, in this alternative embodiment according to the invention, a processing unit connected to each current measuring device and DC-DC converter is provided, and this processing unit is designed and configured to switch off the DC-DC converter when the current intensity measured by at least one of the current measuring devices exceeds at least one predetermined limit value.

[0011] In the method according to the invention for operating the high-voltage in-vehicle electrical system of a vehicle in this alternative embodiment, correspondingly, the current measuring device is evaluated by the processing unit, and when the current intensity measured by at least one of the current measuring devices exceeds at least one predetermined limit value, the DC-DC converter is switched off.

[0012] By using one DC-DC converter or two DC-DC converters, it becomes possible to charge an electric vehicle battery at a charging voltage lower than the battery voltage of the electric vehicle battery at a DC charging station. For example, at a DC charging station, it is possible to charge an 800V electric vehicle battery at a charging voltage of 400V or 500V. The DC-DC converter or each DC-DC converter is particularly configured as a galvanically coupled DC-DC converter. This is a low-cost and space-saving solution. However, when an insulation fault occurs in the vehicle, as a direct result, there is a problem that another insulation fault may occur at the opposite high potential on the DC charging station side. Many 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 at the DC charging station to protect the insulation part. This varistor at the DC charging station has a terminal voltage of, for example, 500V to 550V. When this varistor at the DC charging station operates or the insulation is broken, a short circuit of the electric vehicle battery occurs. This short circuit causes a break in the ground potential line in the charging cable that electrically connects the vehicle to the DC charging station in the so-called CHAdeMO charging standard. This is because this ground potential line is very thin. At present, as limit values, 100 mAs for protecting the varistor at the DC charging station and 7000 As for protecting the ground potential line in the charging cable are defined. 2 are defined.

[0013] This problem is solved by the solution means according to the present invention. Because, in the solution means according to the present invention, when an insulation failure occurs in the high-voltage in-vehicle electrical system of the vehicle, and as a result, the insulation part on the DC charging station side may be exposed to an excessively high applied voltage, the corresponding varistor in the high-voltage in-vehicle electrical system of the vehicle first shifts to a low-resistance state. For this reason, in particular, the varistor in the first embodiment according to the present invention mentioned above, or each varistor in the alternative embodiment according to the present invention mentioned above, is configured to shift to a low-resistance state when it exceeds a predetermined voltage lower than, for example, the design voltage of 500V of a DC charging station outside the vehicle that is configured to electrically connect the charging terminals. Therefore, this predetermined voltage is, for example, 450V. At the same time, in particular, the varistor or each varistor has a corresponding characteristic curve. Therefore, the varistor shifts to a low-resistance state before exceeding the design voltage of the DC charging station.

[0014] Using the current measurement of the corresponding current measurement device, the generated conduction path can be measured quickly and without interference. Through evaluation using a processing unit, this measured current, that is, the current intensity of the current, is compared with at least one predetermined limit value or a plurality of predetermined limit values, and when necessary, that is, when the limit value is exceeded, thereby, one or more DC-DC converters are switched off very quickly. That is, the function of the DC-DC converter is stopped.

[0015] For example, the processing unit is connected to a contactor of an electric vehicle battery and / or to an isolator arranged on at least one of the high-voltage potential lines. In this case, the processing unit is designed and configured to activate the contactor and / or at least one isolator for separation when the current intensity measured by the current measuring device in the first embodiment according to the invention mentioned above, or the current intensity measured by at least one of the two current measuring devices in the alternative embodiment according to the invention mentioned above, exceeds at least one predetermined limit value. Correspondingly, in the method for activation, for example, when the current intensity measured by the current measuring device in the first embodiment according to the invention mentioned above, or the current intensity measured by at least one of the two current measuring devices in the alternative embodiment according to the invention mentioned above, exceeds at least one predetermined limit value, the processing unit activates the contactor and / or at least one isolator for separation. Thereby, further, that is, in addition to the above-mentioned switching off of one or more DC-DC converters, in order to eliminate the short-circuit current, the electric vehicle battery is very quickly instructed to open its own contactor and / or activate one or more isolators to cut off the short-circuit current. The isolator or each isolator is configured, for example, as a semiconductor switch, a diode, or a bursting fuse, that is, a pyrotechnic isolator also referred to as a pyro-fuse. Since the current takes a lower value at this early point in time in a low-resistance varistor compared to a conductive insulation short circuit in a DC charging station, one isolator or a plurality of isolators, and also, for example, the contactor of the electric vehicle battery can be configured to be smaller. Because no design for the short-circuit current is required.

[0016] Accordingly, with the solution means according to the present invention, through current measurement, it becomes possible to quickly and without interference identify that the transition of the high voltage potential in the high voltage vehicle-mounted electrical system has exceeded the regulation, whereby the functions of one or more DC-DC converters can be stopped very early. As a result, the varistor in the DC charging station or the insulation in the DC charging station will not be overloaded by the overvoltage. This is because the voltage is limited to a value below the insulation design voltage by the varistor in the high voltage vehicle-mounted electrical system. Furthermore, since the generated high voltage vehicle-mounted electrical system short-circuit current is retained in the vehicle by the varistor in the high voltage vehicle-mounted electrical system, damage or destruction of the varistor and the grounding potential line of the charging cable in the DC charging station due to high current is avoided. Furthermore, with the solution means according to the present invention, different from other solution means, fault identification is achieved without interference, so that interruption of defective charging is avoided. Furthermore, due to the relatively low trigger voltage of the varistor in the high voltage vehicle-mounted electrical system, the generated fault can be identified more quickly, whereby the generated battery current is still limited by the resistance of the varistor. As a result, there is no need to design according to a high short-circuit current, so that the use of a smaller isolator and / or contact for interruption is realized.

[0017] In summary, the above solution means can quickly take safety measures through a low-resistance varistor based on the evaluation of current measurement and the comparison with one or more predetermined limit values of current intensity during an insulation fault, in particular realizing an early switch-off of one or more DC-DC converters, and also realizing an early opening of contacts and / or isolators, for example already at a very low current.

[0018] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Brief Description of the Drawings

[0019]

Figure 1

Mode for Carrying Out the Invention

[0020] FIG. 1 shows a schematic diagram of a high-voltage in-vehicle electrical system 3 of a vehicle 4 electrically connected to a DC charging station 2 via a charging cable 1.

[0021] The vehicle 4 is in particular an electric vehicle or a hybrid vehicle. That is, the vehicle 4 has at least one electrical drive unit for its own drive. For the electrical energy supply of this at least one electrical drive unit, the high-voltage in-vehicle electrical system 3 has an electric vehicle battery 5.

[0022] The high-voltage in-vehicle electrical system 3 further has a charging terminal 6 for electrically connecting to a DC charging station 2 outside the vehicle. This connection is made via the charging cable 1. For this purpose, the charging cable 1 is electrically connected to or is electrically connected with the DC charging station 2 and the charging terminal 6.

[0023] The high-voltage in-vehicle electrical system 3 further 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 an earth potential line. This also applies to the charging cable 1 and the DC charging station 2 as shown in FIG. 1.

[0024] Furthermore, in the high-voltage in-vehicle electrical system 3, in particular, an insulation resistance Riso+BN between the high-voltage positive potential line HV+L and the reference potential line ML, an insulation resistance Riso-BN between the high-voltage negative potential line HV-L and the reference potential line ML, a Y capacitor C+BN between the high-voltage positive potential line HV+L and the reference potential line ML, and a Y capacitor C-BN between the high-voltage negative potential line HV-L and the reference potential line ML are provided.

[0025] Similarly, the DC charging station 2 is provided with, in particular, an insulation resistance Riso+LS between the high-voltage positive potential line HV+L and the reference potential line ML, an insulation resistance Riso-LS between the high-voltage negative potential line HV-L and the reference potential line ML, a Y capacitor C+LS between the high-voltage positive potential line HV+L and the reference potential line ML, and a Y capacitor C-LS between the high-voltage negative potential line HV-L and the reference potential line ML.

[0026] The high-voltage in-vehicle electrical system 3 is configured to charge the electric vehicle battery 5 at a charging voltage lower than the battery voltage of the electric vehicle battery 5, particularly at the DC charging station 2. For example, at the DC charging station 2, it is configured to charge an 800V electric vehicle battery at a charging voltage of 400V or 500V. For example, the electric vehicle battery 5 is planned to have a battery voltage of 800V, and the DC charging station 2 has a charging voltage of 500V, also referred to as the design voltage. To achieve the above charging of the electric vehicle battery 5, the high-voltage in-vehicle electrical system 3 has a DC-DC converter 7, which is arranged on the high-voltage positive potential line HV+L of the high-voltage in-vehicle electrical system 3 in the illustrated embodiment. The DC-DC converter 7 is configured as a galvanically coupled DC-DC converter 7.

[0027] However, when an insulation fault occurs in the vehicle 4, as a direct result, there is a problem that another insulation fault may occur at the opposite high potential on the side of the DC charging station 2. Many 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 to protect the insulation part. This varistor in the DC charging station 2 has a terminal voltage of, for example, 500V to 550V. When this varistor in the DC charging station 2 operates or the insulation part is damaged, the electric vehicle battery 5 is short-circuited. This short circuit causes the destruction of the ground potential line, i.e., the reference potential line ML, in the charging cable 1 in the so-called CHAdeMO charging standard. This is because this ground potential line is very thin. At present, as limit values, 100 mAs for protecting the varistor in the DC charging station 2 and 7000 As for protecting the ground potential line in the charging cable 1 are defined. 2 is defined

[0028] In FIG. 1, the flow of the normal charging current during charging of the electric vehicle battery 5 is shown by the first arrow P1. Further, in FIG. 1, the above-described fault case is represented by the fault symbol FS. In the illustrated example, as represented by the connection line penetrating the insulation resistance Riso+BN, the high voltage potential and the reference potential are conductively connected due to the insulation fault in the vehicle 4. As a result, the short-circuit current flowing into the high voltage in-vehicle electrical system 3 is represented by the second arrow P2.

[0029] To solve the above problem, in the illustrated embodiment, a series circuit composed of 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.

[0030] In an alternative embodiment (not shown), the DC-DC converter 7 is arranged on the high-voltage negative potential line HV-L of the high-voltage vehicle electrical system 3, and is similarly configured as a galvanically coupled DC-DC converter 7. In this case, correspondingly, a series circuit consisting of a varistor 8 and a current measuring device 9 is arranged between the high-voltage positive potential line HV+L and the reference potential line ML. Accordingly, in this case, a corresponding fault case where the high-voltage negative potential and the reference potential are conductively connected due to an insulation fault in the vehicle 4 can be detected.

[0031] Furthermore, in the illustrated embodiment as well as in other embodiments not shown, a processing unit 10 connected to the current measuring device 9 and the DC-DC converter 7 is provided, and this processing unit 10 is designed and configured to switch off the DC-DC converter 7 when the current intensity measured by the current measuring device 9 exceeds at least one predetermined limit value.

[0032] In a method for operating the high-voltage vehicle electrical system 3 of the vehicle 4, correspondingly, the current measuring device 9 is evaluated by the processing unit 10, and when the current intensity measured by the current measuring device 9 exceeds at least one predetermined limit value, the DC-DC converter 7 is switched off.

[0033] The above problem is solved by using the above-described embodiment of the high-voltage vehicle electrical system 3 of the vehicle 4 when an insulation fault occurs in the vehicle 4, whereby the insulation on the side of the DC charging station 2 may be exposed to an excessively high applied voltage. To ensure this, the varistor 8 is configured to transition to a low-resistance state when a predetermined voltage lower than, for example, the design voltage of 500V of the DC charging station 2 outside the vehicle is exceeded. Accordingly, this predetermined voltage is, for example, 450V. At the same time, in particular, the varistor 8 has a corresponding characteristic curve. Accordingly, the varistor 8 transitions to a low-resistance state before exceeding the design voltage of the DC charging station 2.

[0034] Using the current measurement of the current measuring device 9, the generated conductive path can be measured quickly and without interference. Through the evaluation using the processing unit 10, this measured current, i.e., the current intensity of this current, is compared with at least one predetermined limit value or a plurality of predetermined limit values, and when necessary, i.e., when the limit value is exceeded, thereby, the DC-DC converter 7 is switched off very quickly. That is, the function of the DC-DC converter 7 is stopped.

[0035] Additionally, for example, the processing unit 10 can be connected to a contactor (not shown here) of the electric vehicle battery 5, and / or can be connected to an isolator 11 arranged on at least one of the high voltage potential lines HV+L, HV-L of the high voltage vehicle electrical system 3. In this case, the processing unit is designed and configured to activate the contactor and / or at least one isolator 11 for separation when the current intensity measured by the current measuring device 9 exceeds at least one predetermined limit value. Correspondingly, in this method for activation, for example, when the current intensity measured by the current measuring device 9 exceeds at least one predetermined limit value, the processing unit 10 activates the contactor and / or at least one isolator 11 for separation. Thereby, further, i.e., in addition to the above-mentioned switch-off of the DC-DC converter 7, in order to eliminate the short-circuit current, the electric vehicle battery 5 is very quickly instructed to open its own contactor and / or activate one or more isolators 11 to cut off the short-circuit current. The isolator 11 or each isolator 11 is configured as, for example, a diode, or a semiconductor switch, or a rupture fuse, as shown in the illustrated example. Since the current takes a lower value at this early point in time in the low-resistance varistor 8 compared to the conductive insulation short circuit in the DC charging station 2, one isolator 11 or a plurality of isolators 11, and also, for example, the contactor of the electric vehicle battery 5 can be configured to be smaller. This is because there is no need for a design for the short-circuit current.

[0036] In another embodiment (not shown), one DC-DC converter 7 of the high-voltage vehicle electrical system 3 is arranged on each of the high-voltage positive potential line HV+L and the high-voltage negative potential line HV-L, and is similarly configured as a galvanically coupled DC-DC converter 7. Correspondingly, a series circuit composed of a varistor 8 and a current measuring device 9 is arranged between each of the high-voltage potential lines HV+L, HV-L and the reference potential line ML. Here, it is possible to detect a fault case where the high-voltage positive potential and the reference potential are conductively connected due to an insulation fault in the vehicle 4, and it is also possible to detect a fault case where the high-voltage negative potential and the reference potential are conductively connected due to an insulation fault in the vehicle 4.

[0037] In this embodiment, correspondingly, a processing unit 10 connected to each current measuring device 9 and DC-DC converter 7 is provided, and this processing unit 10 is designed and configured 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 predetermined limit value.

[0038] In a method for operating the high-voltage vehicle electrical system 3 of the vehicle 4, correspondingly, the current measuring device 9 is evaluated by the processing unit 10, and when the current intensity measured by at least one of the current measuring devices 9 exceeds at least one predetermined limit value, the DC-DC converter 7 is switched off.

[0039] The above problem is solved even when using this embodiment of the high-voltage in-vehicle electrical system 3 of the vehicle 4, where respective insulation faults occur in the vehicle 4, thereby potentially exposing the insulation part on the DC charging station 2 side to an excessively high applied voltage. For this reason, in this embodiment, in particular, each varistor 8 is configured to shift to a low-resistance state when exceeding a predetermined voltage lower than, for example, the design voltage of 500 V of the DC charging station 2 outside the vehicle. Thus, this predetermined voltage is, for example, 450 V. At the same time, in particular, each varistor 8 has a corresponding characteristic curve. Thus, the varistor 8 shifts to a low-resistance state before exceeding the design voltage of the DC charging station 2. Thus, in this embodiment, two varistors 8 are each configured in this way.

[0040] Also in this embodiment, correspondingly, the generated conduction path can be measured quickly and without problems by measuring the current of the corresponding current measuring device 9. Through evaluation using the processing unit 10, this measured current, i.e., the current intensity of the current, is compared with at least one predetermined limit value or a plurality of predetermined limit values, and when necessary, i.e., when exceeding the limit value, thereby the DC-DC converter 7 is switched off very quickly. That is, the function of the DC-DC converter 7 is stopped.

[0041] Additionally, also in this embodiment, the processing unit 10 can be connected to the contacts of the electric vehicle battery 5 and / or to the isolator 11 arranged on at least one of the high voltage potential lines HV+L, HV-L of the high voltage vehicle electrical system 3. In this case, the processing unit is designed and configured to activate the contacts and / or at least one isolator 11 for separation when the current intensity measured by at least one of the two current measuring devices 9 exceeds at least one predetermined limit value. Correspondingly, in this method for activation, for example, when the current intensity measured by at least one of the two current measuring devices 9 exceeds at least one predetermined limit value, the processing unit 10 activates the contacts and / or at least one isolator 11 for separation. Thereby, further, i.e., in addition to the above-described switching off of the DC-DC converter 7, in order to eliminate the short-circuit current, the electric vehicle battery 5 is instructed to open its own contacts and / or activate one or more isolators 11 very quickly to cut off the short-circuit current. Here too, the isolator 11 or each isolator 11 can be configured, for example, as a semiconductor switch, a diode, or a bursting fuse. Since the current takes on a lower value at this early point in time in the low-resistance varistor 8 compared to a conductive insulation short circuit at the DC charging station 2, one isolator 11 or a plurality of isolators 11, and also, for example, the contacts of the electric vehicle battery 5 can be configured more compactly. This is because no design for the short-circuit current is required.

Explanation of Reference Numerals

[0042] 1 Charging cable 2 DC charging station 3 High voltage vehicle electrical system 4 Vehicle 5 Electric vehicle battery 6 Charging terminal 7 DC-DC converter 8 Varistor 9 Current measuring device 10 Processing Unit 11 Isolator Y Capacitor of C+BN High-Voltage In-Vehicle Electrical System Y Capacitor of C-BN High-Voltage In-Vehicle Electrical System Y Capacitor of C+LS Charging Station Y Capacitor of C-LS Charging Station FS Fault Symbol HV+L High-Voltage Positive Potential Line HV-L High-Voltage Negative Potential Line ML Reference Potential Line P1 First Arrow P2 Second Arrow Insulation Resistance of Riso+BN High-Voltage In-Vehicle Electrical System Insulation Resistance of Riso-BN High-Voltage In-Vehicle Electrical System Insulation Resistance of Riso+LS Charging Station Insulation Resistance of Riso-LS Charging Station

Claims

1. A vehicle (4) equipped with a high-voltage in-vehicle electrical system (3), wherein the high-voltage in-vehicle electrical system (3) has a battery (5) for an electric vehicle, a charging terminal (6) for electrically connecting to a DC charging station (2) outside the vehicle, a high-voltage positive potential line (HV+L), a high-voltage negative potential line (HV−L), and a reference potential line (ML). In the vehicle (4), a DC-DC converter (7) is arranged on one of the high-voltage potential lines (HV+L, HV−L), and a series circuit composed of 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). A processing unit (10) connected to the current measuring device (9) and the DC-DC converter (7) is provided. When the current intensity measured by the current measuring device (9) exceeds at least one predetermined limit value, the processing unit (10) is designed and configured to stop the function of the DC-DC converter (7) by switching off the DC-DC converter (7), or DC-DC converters (7) are respectively arranged on the two high-voltage potential lines (HV+L, HV−L), and series circuits composed of a varistor (8) and a current measuring device (9) are respectively arranged between each high-voltage potential line (HV+L, HV−L) and the reference potential line (ML). A processing unit (10) connected to each current measuring device (9) and the DC-DC converter (7) is provided. When the current intensity measured by at least one of the current measuring devices (9) exceeds at least one predetermined limit value, the processing unit (10) is designed and configured to stop the function of the DC-DC converter (7) by switching off the DC-DC converter (7). The vehicle (4) is characterized by the above.

2. The varistor (8), or each varistor (8), is configured to transition to a low-resistance state when exceeding a predetermined voltage lower than the design voltage of the DC charging station (2) outside the vehicle, which is configured to be electrically connected to the charging terminal (6). The vehicle (4) according to Claim 1 is characterized by this.

3. ​ The vehicle (4) according to claim 1 or 2, characterized in that the DC-DC converter (7), or each of the DC-DC converters (7), is configured as a galvanically coupled DC-DC converter (7).

4. The vehicle (4) according to any one of claims 1 to 3, characterized in that the processing unit (10) is connected to the contacts of the electric vehicle battery (5) and / or to an isolator (11) arranged on at least one of the high voltage potential lines (HV+L, HV-L), and is designed and configured to activate the contacts and / or at least one of the isolators (11) for separation when the current intensity measured by the current measuring device (9), or the current intensity measured by at least one of the two current measuring devices (9), exceeds the at least one predetermined limit value.

5. The vehicle (4) according to any one of claims 1 to 4, characterized in that the isolator (11) is configured as a semiconductor switch, a diode, or a rupture fuse.

6. In a method for operating the high voltage vehicle electrical system (3) of a vehicle (4) according to any one of claims 1 to 5, when the current measuring device (9) is evaluated by the processing unit (10) and the current intensity measured by the current measuring device (9) exceeds at least one predetermined limit value, the DC-DC converter (7) is switched off, or the method, characterized in that when the current measuring device (9) is evaluated by the processing unit (10) and the current intensity measured by at least one of the current measuring devices (9) exceeds at least one predetermined limit value, the DC-DC converter (7) is switched off.

7. The method according to claim 6, characterized in that the processing unit (10) activates the contacts and / or at least one isolator (11) for separation when the current intensity measured by the current measuring device (9), or the current intensity measured by at least one of the two current measuring devices (9), exceeds the at least one predetermined limit value.

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