DC voltage switching device, in particular for interrupting a current flow, and DC voltage system

Abstract

The invention relates to a DC voltage switching device (10) having a first, second, third and fourth device terminal (11-14), a first current path (1), a current detection unit (30), a second current path (2) and a single short-circuit switch (50), wherein a fuse (20, 21) is arranged in each of the two current paths (1, 2). An anti-series circuit (60) comprising a first actuatable semiconductor switch (61) and a second actuatable semiconductor switch (62) is arranged in one of the two current paths (1, 2). A control and evaluation unit (40) is designed to switch on the single short-circuit switch (50) when the current intensity measured by the current detection unit (30) reaches or exceeds a predetermined threshold value, wherein, in the switched-on state, the single short-circuit switch (50) is connected in series either with the first or with the second fuse (20, 21) depending on the direction of the current flowing through the two current paths (1, 2).

Description

[0001] Phoenix Contact GmbH & Co. KG 1 January 26, 2024

[0002] P-2023-0045 BE / WO 23PH 0007WOP

[0003] DC switching device, in particular for interrupting a current flow, and DC system

[0004] Description

[0005] The invention relates to a DC switching device that can, in particular, interrupt an electrical current flow between the input and output sides of the DC switching device or between two DC devices. The invention further relates to a DC system comprising such a DC device.

[0006] For example, in order to electrically connect a DC load to or disconnect it from a DC voltage source, a DC switching device is usually used. An external DC voltage source, e.g. a DC power supply or a DC bus, can be connected to the input terminals of the DC switching device, while a DC load can be connected to the output terminals of the DC switching device. To electrically switch the DC load on and off, the DC switching device comprises at least one switching element. A controllable semiconductor switching element is often used for this purpose, which is arranged in the positive conductor running between the first input terminal and the first output terminal or in the negative conductor running between the second input terminal and the second output terminal. Furthermore, an electromechanical switch can additionally be provided.When the semiconductor switching element is switched on, a current flows between the DC voltage source and the DC voltage load. This current flow can be prevented or interrupted by switching off or opening the semiconductor switching element.

[0007] In particular, to protect the DC voltage device and / or an electrical load connected to it from damage or destruction as a result of a short circuit, special measures must be taken. For example, an electronic switch for interrupting a current flow is known from EP 3 891 890 B1. A regenerative load can be connected to a second and fourth terminal of the electronic switch, while a power source can be connected to a first and third terminal. Furthermore, the electronic switch has two anti-serially connected semiconductor switches to enable bidirectional shutdown of the electronic switch. Two fuses are connected in series with the two semiconductor switches, with the two semiconductor switches being arranged between the two fuses.The two fuses serve to protect the load, the power source, or the switching device itself in the event of a short-circuit current. To protect the two anti-serially connected semiconductor switches from a short-circuit current, two short-circuiters, which can be thyristors, are connected to the fuses in such a way that a series circuit consisting of a fuse and a short-circuiter is located between the first and third terminals and between the second and fourth terminals.

[0008] The present invention is based on the object of creating a DC switching device, in particular for interrupting a current flow, and a DC voltage system which can be constructed with fewer components and thus more cost-effectively than the known electronic switch while providing reliable short-circuit resistance.

[0009] A core idea of ​​the invention can be seen in the provision of a DC switching device which requires only a single short-circuit switch, even if the DC switching device can be operated in both current directions.

[0010] The above-mentioned technical problem is solved by the features of claim 1. Accordingly, a DC switching device, in particular for interrupting a current flow, is provided, which may, for example, have the following features:

[0011] - a first and a second device connection,

[0012] - a first current path electrically connected to the first and second device terminals,

[0013] - a third and a fourth device connection,

[0014] - a second current path electrically connected to the third and fourth device terminals,

[0015] - a current detection device designed to measure the current intensity of a current flowing through the first or second current path,

[0016] - a first electrical fuse arranged in the first current path,

[0017] - a second electrical fuse arranged in the second current path,

[0018] - an anti-serial circuit arranged in the first current path, which has a first controllable semiconductor switch and a second controllable semiconductor switch connected anti-serially thereto, wherein a first diode is connected anti-parallel to the first semiconductor switch and a second diode is connected anti-parallel to the second semiconductor switch, wherein the first electrical fuse and the anti-serial circuit are connected in series,

[0019] - a single controllable short-circuit switch having a first terminal and a second terminal, wherein the first terminal is electrically connected to the first current path and arranged between the first device terminal and the first electrical fuse, and the second terminal is electrically connected to the second current path and arranged between the fourth device terminal and the second electrical fuse,

[0020] - a control and evaluation device connected to the current detection device, wherein the control and evaluation device is configured to switch on or close the single short-circuit switch when the current intensity measured by the current detection device reaches or exceeds a predetermined threshold value. In the switched-on state, the single short-circuit switch is connected in series with either the first or the second fuse, depending on the direction of the current flowing through the two current paths. The above-mentioned technical problem is also solved with the features of claim 2.

[0021] Accordingly, a DC switching device is provided, in particular for interrupting a current flow, which may, for example, have the following features:

[0022] - a first and a second device connection,

[0023] - a first current path electrically connected to the first and second device terminals,

[0024] - a third and a fourth device connection,

[0025] - a second current path electrically connected to the third and fourth device terminals,

[0026] - a current detection device designed to measure the current intensity of a current flowing through the first or second current path,

[0027] - a first electrical fuse arranged in the first current path,

[0028] - a second electrical fuse arranged in the second current path,

[0029] - an anti-serial circuit arranged in the second current path, which has a first controllable semiconductor switch and a second controllable semiconductor switch connected in anti-serial thereto, wherein a first diode is connected in anti-parallel to the first semiconductor switch and a second diode is connected in anti-parallel to the second semiconductor switch, wherein the second electrical fuse and the anti-serial circuit are connected in series,

[0030] - a single controllable short-circuit switch having a first terminal and a second terminal, wherein the first terminal is electrically connected to the first current path and arranged between the second device terminal and the first electrical fuse, and the second terminal is electrically connected to the second current path and arranged between the third device terminal and the second electrical fuse,

[0031] - a control and evaluation device connected to the current detection device, wherein the control and evaluation device is designed to switch on or close the single short-circuit switch when the current intensity measured by the current detection device reaches or exceeds a predetermined threshold value, wherein in the switched-on state the single short-circuit switch is connected in series with either the first or the second fuse depending on the direction of the current flowing through the two current paths.

[0032] Preferably, the control and evaluation device is implemented as a microcontroller, microprocessor or as an analog circuit.

[0033] The short-circuit switch can, for example, be designed as a thyristor or triac with a bidirectional current flow.

[0034] To enable energy-efficient operation of the DC switching device, an electromechanical switch with a mechanical switching contact can be provided, wherein the mechanical switching contact is connected in parallel with the first and second semiconductor switches, and the control and evaluation device is designed to control the electromechanical switch. Preferably, the control and evaluation device ensures that during a switch-on process, the two semiconductor switches are first switched on and then the mechanical switching contact is closed.

[0035] Preferably, a DC voltage supply device can be connected to the first and third device terminals, and an electrical device can be connected to the second and fourth device terminals, or vice versa. The electrical device can be a non-regenerative electrical device, such as a non-ohmic resistor, a regenerative electrical device, or another DC voltage supply device. The DC voltage supply device can be, for example, a DC supply network.

[0036] The current detection device can comprise, for example, a current sensor or magnetic field sensor. Furthermore, the current detection device can be connected directly into the respective current path. Alternatively, the current detection device can comprise a shunt resistor and be configured to detect a voltage across the shunt resistor and its polarity in order to determine the current flowing through the respective current path and its direction.

[0037] The current detection device can be connected in series with the first or second fuse.

[0038] The above-mentioned technical problem is also solved by the features of claim 8.

[0039] Accordingly, a DC voltage system is provided, which may include the previously described DC voltage device. A DC voltage supply device and an electrical device, for example, a regenerative electrical device, may be connected to the DC voltage device. The DC voltage supply device may, for example, be a grounded DC voltage source with a positive pole and a ground connection, a DC supply network, or a DC voltage bus.

[0040] According to an advantageous embodiment, the first and second device terminals each serve as positive poles, and the third and fourth device terminals each serve as negative poles or ground connections. The control and evaluation device of the DC switching device is designed, for example, to first control the first semiconductor switch to conduct while simultaneously keeping the second semiconductor switch off, particularly during a switch-on process, and then to close the mechanical switching contact when a current is to flow from the first device terminal to the third device terminal. When the current measured by the current detection device reaches or exceeds the predetermined threshold, the first short-circuit switch is closed.This is preferably the case when a DC voltage supply device is connected to the first and third device terminals, and an electrical load that is not capable of regenerative power is connected to the second and fourth device terminals. The control and evaluation device can further be designed to first control the second semiconductor switch to be conductive and simultaneously keep the first semiconductor switch off, and then to close the mechanical switching contact when a current is to flow from the second device terminal to the fourth device terminal, and to close the second short-circuit switch when the current intensity measured by the current detection device reaches or exceeds the predetermined threshold value. This is preferably the case when an electrical load that is not capable of regenerative power is connected to the first and third device terminals, and a DC voltage supply device is connected to the second and fourth device terminals.

[0041] In practice, the first and second semiconductor switches are preferably switched on simultaneously. This is particularly useful when, for example, a DC power supply is connected to the first and third device terminals, and a regenerative electrical load or a second DC power supply is connected to the second and fourth device terminals, since the current direction is not fixed.

[0042] The invention is explained in more detail below using two exemplary embodiments in conjunction with the accompanying drawings. For simplicity of illustration, identical components are provided with identical reference numerals. They show:

[0043] Fig. 1 is a circuit diagram of an exemplary DC switching device, and Fig. 2 is an alternative circuit diagram of an exemplary DC switching device.

[0044] Fig. 1 shows the circuit diagram of an exemplary DC voltage system 5, which has an exemplary DC voltage switching device 10. The DC voltage switching device 10 has a first and a third device terminal 11, 12, to which a DC voltage supply device 100 can be connected. Furthermore, the DC voltage device 10 has a second and a fourth device terminal 13, 14, to which an electrical device 90 can be connected. It should be noted that the electrical device 90 can also be connected to the device terminals 11 and 12, and the DC voltage supply device 100 can be connected to the device terminals 13 and 14. The DC voltage supply device 100 can be, for example, a grounded DC voltage source with a positive pole and a ground connection, a DC supply network, or a DC voltage bus.The electrical device 90 can be designed, for example, as a regenerative or non-regenerative DC voltage load 90 or a further DC voltage supply device.

[0045] A first current path 1 runs between the first device connection 11 and the second device connection 13. An anti-serial circuit 60 and an electrical fuse 20 connected in series with it are connected into the current path 1. The anti-serial circuit

[0046] 60 has a first controllable semiconductor switch 61 and a second controllable semiconductor switch 62, which is connected anti-serially to the first semiconductor switch 61. A first diode 70 is connected anti-parallel to the first semiconductor switch 61, and a second diode 71 is connected anti-parallel to the second semiconductor switch 62. The two semiconductor switches 61, 62 can be designed, for example, as field-effect transistors or as insulated-gate bipolar transistors (IGBTs). In the present example, the two semiconductor switches

[0047] 61 and 62 are each implemented as an n-channel IGBT transistor. For example, the electrical fuse 20 is arranged between the collector electrode of the semiconductor switch 61 and the device terminal 11, while the collector electrode of the semiconductor switch 62 can be connected directly to the device terminal 13.

[0048] A current detection device 30 can be arranged between the fuse 20 and the collector terminal of the semiconductor switch 61, as shown by way of example in Fig.

[0049] 1. According to the exemplary embodiment shown, the current detection device 30 can be connected in series with the fuse 20 in the first current path 1. However, the current detection device 30 can be connected at any point in the first or second current path 1, 2. For example, the current detection device 30 can also have a shunt resistor connected in the first or second current path (not shown). In this case, the current detection device is designed to detect a voltage across the shunt resistor and its polarity in order to determine the current flowing through the respective current path and its direction therefrom.

[0050] Current detection device It is only important that the current detection device 30, however it is implemented, is designed to determine the current intensity of a direct current flowing through the current paths 1 and 2 in order to detect a short-circuit current.

[0051] The emitter electrodes of the two semiconductor switches 61 and 62 form a common connection point. The cathode of diode 70 is connected to the collector electrode of semiconductor switch 61, while the anode of diode 70 is connected to the emitter electrode of semiconductor switch 61. Similarly, the cathode of diode 71 is connected to the collector electrode of semiconductor switch 62, while the anode of diode 71 is connected to the emitter electrode of semiconductor switch 62. The gate electrodes of semiconductor switches 61 and 62 are each connected to an input of a control and evaluation device 40, which can be embodied, for example, as a microcontroller. The control and evaluation device 40 is also connected on the input side to the current detection device 30.

[0052] A second current path 2 runs between the third device terminal 12 and the fourth device terminal 14, into which, in the illustrated embodiment, only one electrical fuse 21 is connected. Preferably, no semiconductor switches are implemented in the second current path 2.

[0053] The exemplary interconnection of the two semiconductor switches 61 and 62 and the two diodes 70 and 71 ensures that a) when the first semiconductor switch 61 is electrically conductive and the second semiconductor switch 62 is simultaneously controlled to be electrically blocking, a current can flow from the device connection 11 via the fuse 20, the current detection device 30, the first semiconductor switch 61, the diode 71, the load 90, and the fuse 21 to the device connection 12, or that, b) when the second semiconductor switch 62 is electrically conductive and the first semiconductor switch 61 is simultaneously controlled to be electrically blocking, a current can flow from the device connection 13 via the second semiconductor switch 62, the diode 70, the current detection device 30, the fuse 20, the device connections 11 and 12, and the fuse 21 to the device connection 14.

[0054] In order to be able to switch the DC voltage device 10 into an energy-saving mode during operation, i.e. the load 90 is switched on and an electrical current flows, for example, from the DC voltage supply device 100 via the semiconductor switch 61 to the load 90, a mechanical switching contact 81 of an electromechanical switch 80 can be connected in parallel to the first and second semiconductor switches 61, 62. The electromechanical switch 80 can be designed as a relay. According to an exemplary embodiment, the electromechanical switch 80 has an excitation coil 82 which can be connected to the control and evaluation device 40, as shown in Fig. 1. The excitation coil 82 is located in a control circuit which can be controlled by the control and evaluation device 40 to open and close accordingly in order to be able to open or close the mechanical switching contact 81.The mechanical switching contact 81 is designed, for example, as a normally open contact.

[0055] Furthermore, the DC voltage switching device 10 has a single controllable short-circuit switch 50 with a first terminal 50a, which is designed as an anode terminal, and a second terminal 50b, which is designed as a cathode terminal. The first terminal 50a is electrically connected to the first current path 1 and is arranged between the first device terminal 11 and the first electrical fuse 20. The second terminal 50b is electrically connected to the second current path 2 and is arranged between the fourth device terminal 14 and the second electrical fuse 21. The short-circuit switch 50 also has a control terminal, which is connected to an output of the control and evaluation device 40. Fig. 2 shows the circuit diagram of another exemplary DC voltage system 5', which has an exemplary DC voltage switching device 10'.The DC switching device 10' has a first and a third device terminal 11, 12, to which a DC voltage supply device 100 can be connected. Furthermore, the DC voltage device 10 has a second and a fourth device terminal 13, 14, to which an electrical DC voltage load 90 can be connected. It should be noted that the load 90 can also be connected to the device terminals 11 and 12, and the DC voltage supply device 100 can be connected to the device terminals 13 and 14, as shown in Fig. 2. The DC switching device 10' differs from the DC switching device 10, in particular, only in that an anti-serial circuit 60 and an electrical fuse 21 connected in series therewith are arranged in the second current path 2, and an electrical fuse 20 is arranged in the first current path 1. No semiconductor switches are arranged in the first current path. Therefore, in Fig. 1 and Fig. 2, the same components are provided with the same reference numerals.

[0056] A first current path 1 runs between the first device terminal 11 and the second device terminal 13, into which, in the illustrated embodiment, only an electrical fuse 20 is connected. No semiconductor switches are implemented in the current path 1.

[0057] A second current path 2 runs between the third device connection 13 and the fourth device connection 14. An anti-serial circuit 60 and an electrical fuse 21 connected in series with it are connected into the current path 2. The anti-serial circuit

[0058] 60 has a first controllable semiconductor switch 61 and a second controllable semiconductor switch 62, which is connected anti-serially to the first semiconductor switch 61. A first diode 70 is connected anti-parallel to the first semiconductor switch 61, and a second diode 71 is connected anti-parallel to the second semiconductor switch 62. The two semiconductor switches 61, 62 can be designed, for example, as field-effect transistors or as insulated-gate bipolar transistors (IGBTs). In the present example, the two semiconductor switches

[0059] 61 and 62 are each implemented as an n-channel IGBT transistor. For example, the electrical fuse 21 is arranged between the collector electrode of the semiconductor switch 62 and the device terminal 12, while the collector electrode of the

[0060] semiconductor switch 61 can be directly connected to the device connection 14.

[0061] A current detection device 30 can be arranged between the fuse 21 and the collector terminal of the semiconductor switch 62, as shown by way of example in Fig. 2. According to the exemplary embodiment shown, the current detection device 30 can be connected in series with the fuse 21 in the second current path 2. However, the current detection device 30 can be connected at any point in the first or second current path 1, 2. For example, the current detection device 30 can also have a shunt resistor connected in the first or second current path (not shown). In this case, the current detection device is designed to detect a voltage across the shunt resistor and its polarity in order to determine the current flowing through the respective current path and its direction.Current detection deviceIt is only important that the current detection device 30, however it is implemented, is designed to determine the current intensity of a direct current flowing through the current paths 1 and 2 in order to detect a short-circuit current.

[0062] The emitter electrodes of the two semiconductor switches 61 and 62 form a common connection point. The cathode of diode 70 is connected to the collector electrode of semiconductor switch 61, while the anode of diode 70 is connected to the emitter electrode of semiconductor switch 61. Similarly, the cathode of diode 10 is connected to the collector electrode of semiconductor switch 62, while the anode of diode 71 is connected to the emitter electrode of semiconductor switch 62. The gate electrodes of semiconductor switches 61 and 62 are each connected to an input of a control and evaluation device 40, which can be embodied, for example, as a microcontroller. The control and evaluation device 40 is also connected on the input side to the current detection device 30.The exemplary interconnection of the two semiconductor switches 61 and 62 and the two diodes 70 and 71 in turn ensures that a) when the first semiconductor switch 61 is electrically conductive and the second semiconductor switch 62 is simultaneously electrically blocked, a current can flow from the device connection 11 via the fuse 20, the load 90, the first semiconductor switch 61, the diode 71, the current detection device 30 and the fuse 21 to the device connection 12, or that, b) when the second semiconductor switch 62 is electrically conductive and the first semiconductor switch 61 is simultaneously electrically blocked, a current can flow from the device connection 13 via the fuse 20, the device connections 11 and 12, the fuse 21, the current detection device 30, the second semiconductor switch 62 and the diode 70 to the device connection 14.

[0063] In order to be able to switch the DC voltage device 10 into an energy-saving mode during operation, i.e. the load 90 is switched on and an electrical current flows, for example, from the DC voltage supply device 100 via the semiconductor switch 61 to the load 90, a mechanical switching contact 81 of an electromechanical switch 80 can be connected in parallel to the first and second semiconductor switches 61, 62. The electromechanical switch 80 can be designed as a relay. According to an exemplary embodiment, the electromechanical switch 80 has an excitation coil 82 which can be connected to the control and evaluation device 40, as shown in Fig. 1. The excitation coil 82 is located in a control circuit which can be controlled by the control and evaluation device 40 to open and close accordingly in order to be able to open or close the mechanical switching contact 81.The mechanical switching contact 81 is designed, for example, as a normally open contact.

[0064] Furthermore, the DC voltage switching device 10 has a single controllable short-circuit switch 50 with a first terminal 50a, which is designed as an anode terminal, and a second terminal 50b, which is designed as a cathode terminal. The first terminal 50a is electrically connected to the first current path 1 and is arranged between the second device terminal 13 and the first electrical fuse 20. The second terminal 50b is electrically connected to the second current path 2 and is arranged between the third device terminal 12 and the second electrical fuse 21. The short-circuit switch 50 also has a control terminal, which is connected to an output of the control and evaluation device 40.

[0065] A predetermined threshold value that defines a short-circuit current is preferably stored in each of the DC voltage devices 10 and 10'. For this purpose, the control and evaluation device 40 preferably has a memory in which the predetermined threshold value is stored. The predetermined threshold value can also be stored in a separate memory that the control and evaluation device 40 can access.

[0066] It should also be noted that device terminals 11 and 13 can function as positive poles, in which case current path 1 acts as the positive conductor. Device terminals 12 and 14 can function as negative poles or ground terminals, in which case current path 2 acts as the negative conductor or ground line.

[0067] The operation of the DC voltage devices 10 in conjunction with the DC voltage system 5 shown in Fig. 1 is explained below.

[0068] Let us now assume that the DC voltage system 5 or the DC voltage device 10 is to be activated in order to electrically couple the electrical load 90 to the DC voltage supply device 100.

[0069] The control and evaluation device 40 is therefore designed to control a switch-on process by first switching the semiconductor switch 61 electrically conductive and the semiconductor switch 62 electrically blocking. At this moment, a direct current flows from the direct voltage supply device 100 via the device connection 11, the semiconductor transistor 61, the diode 71, through the load 90, and via the device connection 12 back to the direct voltage supply device 100. If the electromechanical switch 80 is implemented, the control and evaluation device 40 causes the direct voltage switching device 10 to close the mechanical switching contact 81 after a definable period of time after the semiconductor switch 61 has been switched conductive. The direction and current intensity of the direct current are preferably continuously determined by the current detection device 30 and transmitted to the control and evaluation device 40.

[0070] If a short circuit now occurs, both the semiconductor switch 61 and, if present, the mechanical switching contact 81 would have to be switched off. However, due to the mechanical design and the occurrence of arcs, the reaction time of the electromechanical switch 80 to open the mechanical switching contact 81 is too long to ensure reliable short-circuit resistance. Thanks to the inventive measure, however, sufficient short-circuit resistance can now be ensured, particularly when using an electromechanical switch.

[0071] The control and evaluation device 40 detects the occurrence of a short circuit by the fact that the direct current measured by the current detection device 30 reaches or exceeds the predetermined threshold value. In response to this, the control and evaluation device 40 causes the DC switching device 10 to switch on or close the short-circuit switch 50. From this moment on, the short-circuit current flows from the device connection 11 via the short-circuit switch 50 and the fuse 21 to the device connection 12, thereby blowing the fuse 21. In the switched-on state, the single short-circuit switch 50 is now connected in series with the fuse 21.

[0072] If the load 90 is configured to feed energy back to the DC voltage supply device 100, or if the DC voltage supply device 100 is connected to the device terminals 13 and 14 and the load is connected to the device terminals 11 and 12, a switch-on process of the DC voltage switching device 10 proceeds as follows: The control and evaluation device 40 is now configured to control a switch-on process by first switching the semiconductor switch 62 electrically conductive and the semiconductor switch 61 electrically blocking. At this moment, a direct current flows from the DC voltage supply device 100 via the device terminal 13, the semiconductor transistor 62, the diode 70, through the load 90, and via the device terminal 14 back to the DC voltage supply device 100.If the electromechanical switch 80 is implemented, the control and evaluation device 40 causes the DC switching device 10 to close the mechanical switching contact 81 after a definable period of time after the semiconductor switch 62 has been switched on. The current intensity of the direct current is preferably continuously determined by the current detection device 30 and transmitted to the control and evaluation device 40.

[0073] The control and evaluation device 40 detects the occurrence of a short circuit by the fact that the direct current measured by the current detection device 30 reaches or exceeds the predetermined threshold value. In response, the control and evaluation device 40 causes the DC switching device 10 to switch on the short-circuit switch 50. From this moment on, the short-circuit current flows from the device terminal 13, via the semiconductor switch 62, the diode 70, the current detection device 30, the fuse 20, the short-circuit switch 50, and back to the device terminal 14, thereby blowing the fuse 20. In the switched-on state, the single short-circuit switch 50 is now connected in series with the fuse 20.

[0074] Thanks to the special wiring of the single short-circuit switch 50 with the fuses 20 and 21, the load on current paths 1 and 2 and possible connecting cables can be reduced in the event of a short circuit.

[0075] Furthermore, it should be noted that the rated current and overload current of the short-circuit switch 50, the semiconductor switches 61, 62 and the diodes 70, 71, as well as the electromechanical switch 80, are advantageously matched to the rated current (i.e., the tripping characteristic) of the fuses 20 and 21. The operation of the DC switching device 10' essentially corresponds to the operation of the DC switching device 10, so that, to avoid repetition, reference is made to the explanations regarding the DC switching device 10.

Claims

Patent claims 1. DC switching device (10), in particular for interrupting a current flow, comprising: - a first and a second device connection (11, 13), - a first current path (1) which is electrically connected to the first and second device terminals (11, 13), - a third and a fourth device connection (12, 14), - a second current path (2) which is electrically connected to the third and fourth device terminals (12, 14), - a current detection device (30) which is designed to measure the current intensity of a current flowing through the first or second current path (1, 2), - a first electrical fuse (20) arranged in the first current path (1), - a second electrical fuse (21) arranged in the second current path (2), - an anti-serial circuit (60) arranged in the first current path (1), which has a first controllable semiconductor switch (61) and a second controllable semiconductor switch (62) connected anti-serially thereto, wherein a first diode (70) is connected anti-parallel to the first semiconductor switch (61) and a second diode (71) is connected anti-parallel to the second semiconductor switch (62), wherein the first electrical fuse (20) and the anti-serial circuit (60) are connected in series, - a single controllable short-circuit switch (50) having a first terminal (50a) and a second terminal (50b), wherein the first terminal (50a) is electrically connected to the first current path (1) and is arranged between the first device terminal (11) and the first electrical fuse (20), and the second terminal (50b) is electrically connected to the second current path (2) and is arranged between the fourth device terminal (14) and the second electrical fuse (21), - a control and evaluation device (40) which is connected to the current detection device (30), wherein the control and evaluation device (40) is designed to control the single short-circuit switch (50) when the current intensity measured by the current detection device (30) reaches or exceeds a predetermined threshold value, wherein in the switched-on state the single short-circuit switch (50) is connected in series with either the first or the second fuse (20, 21) depending on the direction of the current flowing through the two current paths (1, 2).

2. DC switching device (10'), in particular for interrupting a current flow, comprising: - a first and a second device connection (11, 13), - a first current path (1) which is electrically connected to the first and second device terminals (11, 13), - a third and a fourth device connection (12, 14), - a second current path (2) which is electrically connected to the third and fourth device terminals (12, 14), - a current detection device (30) which is designed to measure the current intensity of a current flowing through the first or second current path (1, 2), - a first electrical fuse (20) arranged in the first current path (1), - a second electrical fuse (21) arranged in the second current path (2), - an anti-serial circuit (60) arranged in the second current path (2), which has a first controllable semiconductor switch (61) and a second controllable semiconductor switch (62) connected anti-serially thereto, wherein a first diode (70) is connected anti-parallel to the first semiconductor switch (61) and a second diode (71) is connected anti-parallel to the second semiconductor switch (62), wherein the second electrical fuse (20) and the anti-serial circuit (60) are connected in series, - a single controllable short-circuit switch (50) having a first terminal (50a) and a second terminal (50b), wherein the first terminal (50a) is electrically connected to the first current path (1) and is arranged between the second device terminal (13) and the first electrical fuse (20), and the second terminal (50b) is electrically connected to connected to the second current path (2) and arranged between the third device connection (12) and the second electrical fuse (20), - a control and evaluation device (40) which is connected to the current detection device (30), wherein the control and evaluation device (40) is designed to switch on the single short-circuit switch (50) when the current intensity measured by the current detection device (30) reaches or exceeds a predetermined threshold value, wherein in the switched-on state the single short-circuit switch (50) is connected in series with either the first or the second fuse (20, 21) depending on the direction of the current flowing through the two current paths (1, 2).

3. DC voltage switching device according to claim 1 or 2, further comprising an electromechanical switch (80) with a mechanical switching contact (81), wherein the mechanical switching contact (81) is connected in parallel to the first and second semiconductor switches (61, 62), wherein the control and evaluation device (40) is designed to control the electromechanical switch (80).

4. DC voltage switching device according to one of the preceding claims, wherein a DC voltage supply device (100) can be connected to the first and third device terminals (11, 12) and an electrical device (90) can be connected to the second and fourth device terminals (13, 14), or vice versa.

5. DC switching device according to one of the preceding claims, wherein the current detecting device (30) comprises a current sensor.

6. DC switching device according to one of the preceding claims, wherein the current detecting device (30) is connected in series with the first or the second fuse (20, 21).

7. DC switching device according to one of the preceding claims, wherein the short-circuit switch (50) is each designed as a thyristor.

8. DC voltage system (5; 5') comprising a DC voltage device (10; 10') according to one of the preceding claims, a DC voltage supply device (100) connected to the DC voltage device (10; 10') and an electrical device (90) connected to the DC voltage device (10; 10').

9. DC voltage system (5; 5') according to claim 8, wherein the first and second device terminals (11, 13) are each defined as a positive pole and the third and fourth device terminals (12, 14) are each defined as a negative pole or ground connection, wherein the control and evaluation device (40) of the DC voltage switching device (10; 10') is designed to first control the first and / or second semiconductor switch (61) in a conductive manner and then to close the mechanical switching contact (81), and, when the current intensity measured by the current detection device (30) reaches or exceeds the predetermined threshold value, to switch on the single short-circuit switch (50).

10. DC voltage system (5; 5') according to claim 8 or 9, wherein the DC voltage supply device (100) is a DC supply network.

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