Direct-voltage switching device, in particular for interrupting a current flow, and direct-voltage system

Abstract

The invention relates, inter alia, to a direct-voltage switching device (10) comprising a first, a second, a third and a fourth device terminal (11-14), a first current path (1), a second current path (2), and a single electrical fuse (20). An anti-series circuit (60) which has a first controllable semiconductor switch (61) and a second controllable semiconductor switch (62) is located in one of the two current paths (1, 2), while the fuse (20) is located in the other current path (1, 2). A first and a second controllable short-circuit switch (50, 51) and a current-determining device (30) are also provided. A control and evaluation device (40) is designed to switch on the first or second short-circuit switch (50, 51) according to the direction and current intensity sensed by the current-determining device (30), if the sensed current intensity reaches or exceeds a predefined threshold value, said short-circuit switch redirecting a short-circuit current through the fuse (20).

Description

[0001] DC switching device, in particular for interrupting a current flow, and DC system

[0002] Description

[0003] 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.

[0004] 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.

[0005] 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 semiconductor switches connected in series to enable current to flow in both directions through 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.

[0006] 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.

[0007] A core idea of ​​the invention can be seen in the provision of a DC switching device which requires only a single fuse, even if the DC switching device can be operated in both current directions.

[0008] 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 can have the following features:

[0009] - a first and a second device connection,

[0010] - a first current path electrically connected to the first and second device terminals,

[0011] - a third and a fourth device connection,

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

[0013] - a single electrical fuse,

[0014] - an anti-serial circuit comprising a first controllable semiconductor switch and a second controllable semiconductor switch (62) connected anti-serially to the first semiconductor switch, 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 electrical fuse is arranged in the second current path and the first and second semiconductor switches are arranged in the first current path,

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

[0016] - a first 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 anti-serial circuit, and the second terminal is electrically connected to the second current path and arranged between the third device terminal and the electrical fuse,

[0017] - a second 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 anti-serial circuit, and the second terminal is electrically connected to the second current path and arranged between the fourth device terminal and the electrical fuse,

[0018] - a control and evaluation device which is connected to the current detection device, wherein the control and evaluation device is designed to switch on the first or second short-circuit switch as a function of the direction and current intensity detected by the current detection device, provided that the detected current intensity reaches or exceeds a predetermined threshold value.

[0019] The above-mentioned technical problem is also solved by the features of claim 2.

[0020] Accordingly, a DC switching device, in particular for interrupting a direct current flow, is provided, which can have the following features:

[0021] - a first and a second device connection,

[0022] - a first current path electrically connected to the first and second device terminals,

[0023] - a third and a fourth device connection,

[0024] - a second current path electrically connected to the third and fourth device terminals,

[0025] - a single electrical fuse,

[0026] - an anti-serial circuit comprising a first controllable semiconductor switch and a second controllable semiconductor switch, 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 electrical fuse is arranged in the first current path and the first and second semiconductor switches are arranged in the second current path,

[0027] - a current detection device designed to determine the direction and current intensity of a current flowing through the first or second current path,

[0028] - a first 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 electrical fuse, and the second terminal is electrically connected to the second current path and arranged between the third device terminal and the anti-serial circuit, - a second 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 electrical fuse, and the second terminal is electrically connected to the second current path and arranged between the fourth device terminal and the anti-serial circuit,

[0029] - a control and evaluation device which is connected to the current detection device, wherein the control and evaluation device is designed to switch on the first or second short-circuit switch as a function of the direction and current intensity detected by the current detection device, provided that the detected current intensity reaches or exceeds a predetermined threshold value.

[0030] The first and second short-circuit switches can, for example, each be designed as a thyristor or triac with a bidirectional current flow.

[0031] To enable energy-efficient operation of the DC switching device, a mechanical switching contact of an electromechanical switch can be provided, wherein the mechanical switching contact is connected in parallel to the first and second semiconductor switches, and the control and evaluation device is designed to control the electromechanical switch. In particular, the control and evaluation device ensures that during a switch-on process, the corresponding semiconductor switch is first switched on and then the mechanical switching contact is closed.

[0032] The short-circuit protection measure of the invention is particularly effective when using the mechanical switch. If a short-circuit current occurs when the mechanical switch contact is closed, the reaction time of the electromechanical switch or the mechanical switch contact to open it is so slow, particularly due to its geometry, mass, and inertia, that a connected load and / or the DC device can be damaged or even destroyed. This is where the two short-circuit switches in conjunction with the single fuse help. As soon as the control and evaluation device detects a short-circuit current and its flow direction, the corresponding short-circuit switch is switched on, and the short-circuit current is diverted via the single fuse, which then quickly blows.Thanks to the special wiring of the two short-circuit switches with the single fuse, the thermal load on the cables up to the location of the short circuit can be minimized in the event of a short circuit.

[0033] 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.

[0034] 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.

[0035] The current detection device can, for example, be connected in series with the fuse or the anti-serial circuit.

[0036] The above-mentioned technical problem is also solved by the features of claim 8.

[0037] Accordingly, a DC voltage system is provided, which may include the previously described DC voltage device. For example, a DC voltage supply device and an electrical load, which may be configured, for example, as 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. It should be noted that two DC voltage supply devices, such as two DC supply networks, may also be connected to the DC voltage device.

[0038] According to an advantageous embodiment, the first and second device terminals each serve as a positive pole and the third and fourth device terminals each serve as a negative pole or ground connection, wherein the control and evaluation device of the DC switching device is designed, for example, in particular during a switch-on process, to first control the first semiconductor switch in a conductive manner and at the same time to keep the second semiconductor switch in a blocking manner and then to close the mechanical switching contact when a current is to flow from the first device terminal to the third device terminal, and, when the current intensity measured by the current measuring device reaches or exceeds the predetermined threshold value, to close the first short-circuit switch.This is preferably the case if 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.

[0039] The control and evaluation device can further be configured to first control the second semiconductor switch to conduction while simultaneously keeping the first semiconductor switch off. Subsequently, the mechanical switching contact is closed when a current is to flow from the second device terminal to the fourth device terminal. When the current measured by the current measuring device reaches or exceeds the predetermined threshold value, the mechanical switching contact is closed. 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 is connected to the second and fourth device terminals.However, if, for example, a DC voltage supply device is connected to the first and third device connection and a regenerative electrical load or a second DC voltage supply device is connected to the second and fourth device connection, the control and evaluation device must ensure that both the first and the second semiconductor switch are switched on, since the current direction is not fixed.

[0040] 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:

[0041] 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.

[0042] 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 connection 11, 12, to which, for example, a DC voltage supply device 100 can be connected. Furthermore, the DC voltage device 10 has a second and a fourth device connection 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 connections 11 and 12, and the DC voltage supply device 100 can be connected to the device connections 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.

[0043] A first current path 1 runs between the first device terminal 11 and the second device terminal 13. An anti-serial circuit 60 is connected into the current path 1, which circuit 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

[0044] 61 and 62 are each implemented as an n-channel IGBT transistor. The collector electrode of semiconductor switch 61 is connected to device terminal 11, while the collector electrode of semiconductor switch 62 is connected to device terminal 13. 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

[0045] 62 are each connected to an input of a control and evaluation device 40, which can be configured, for example, as a microcontroller. The control and evaluation device 40 is also connected on the input side to the current detection device 30.

[0046] A second current path 2, into which an electrical fuse 20 is connected, runs between the third device connection 12 and the fourth device connection 13. It should be noted that the DC switching device 10 only has this one fuse 20. According to the exemplary embodiment shown, a current detection device 30 can be connected in series with the fuse 20 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.It is only important that the current detection device 30, however it is implemented, is designed to determine the current intensity and direction of a direct current flowing through the current paths 1 and 2 in order to detect a short-circuit current and its flow direction.

[0047] 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 first semiconductor switch 61, the diode 71, the load 90, the fuse 20 and the current detection device 30 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 device connections 11 and 12, the fuse 20 and the current detection device 30 to the device connection 14.

[0048] In order to prevent an excessively high blocking voltage from being inadvertently applied to the semiconductor switches 61 and 62 during operation, it is advantageous to control both semiconductor switches 61 and 62 simultaneously by the control and evaluation device 40.

[0049] Furthermore, the exemplary DC voltage device 10 has two intersecting short-circuit switches 50 and 51, each of which is designed as thyristors, for example. The short-circuit switches 50 and 51 are each connected to an output of the control and evaluation device 40, which is designed, for example, to either switch on the short-circuit switch 50 and leave the short-circuit switch 51 off, or vice versa, depending on a detected short-circuit current and its direction. As can be seen in Fig. 1, the first controllable short-circuit switch 50 has a first terminal 50a, which can be designed as an anode terminal, and a second terminal 50b, which can be 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 anti-serial circuit 60 or the collector electrode of the semiconductor switch 62.The second terminal 50b is electrically connected to the second current path 2 and is arranged between the third device terminal 12 and a terminal of the electrical fuse 20. The short-circuit switch 50 further has a control terminal connected to an output of the control and evaluation device 40.

[0050] The second controllable short-circuit switch 51 has a first terminal 51a, which can be designed as an anode terminal, and a second terminal 51b, which can be designed as a cathode terminal. The first terminal 51a is electrically connected to the first current path 1 and is arranged between the first device terminal 11 and the anti-serial circuit 60 or the collector terminal of the semiconductor switch 61. The second terminal 51b is electrically connected to the second current path 2 and is arranged between the fourth device terminal 14 and another terminal of the electrical fuse 20. The short-circuit switch 51 further has a control terminal that is connected to an output of the control and evaluation device 40.

[0051] 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 switching contact 81 is designed, for example, as a normally open contact.

[0052] Fig. 2 shows the circuit diagram of another 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 connection 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 connection 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 connections 11 and 12, and the DC voltage supply device 100 can be connected to the device connections 13 and 14, as shown in Fig. 2. The DC voltage switching device 10' differs from the DC voltage switching device 10, in particular, only in that an electrical fuse 20 is arranged in the first current path 1 and an anti-serial circuit 60 is arranged in the second current path 2. Therefore, in Fig. 1 and Fig.2 identical components have the same reference numerals.

[0053] A current path 2 runs between the device connection 12 and the second device connection 14. The anti-serial circuit 60 is connected into the current path 2 and 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 61 and 62 are each implemented as n-channel IGBT transistors.Here, the collector electrode of semiconductor switch 61 is connected to device terminal 14, while the collector electrode of semiconductor switch 62 is connected to device terminal 12. 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 equipped with a current measuring device 30 on the input side.

[0054] Another current path 1 runs between device connection 11 and device connection 12, into which electrical fuse 20 is connected. It should be noted that DC switching device 10 has only this one fuse 20. According to the exemplary embodiment shown, current measuring device 30 can be connected in series with fuse 20 in current path 1. However, current detecting device 30 can be connected at any point in the first or second current path 1, 2. Alternatively, current detecting device 30 can also have a shunt resistor connected in parallel to one of the two current paths 1, 2. In this case, current detecting device 30 can be designed to detect a voltage across the shunt resistor (not shown) and its polarity in order to determine the current flowing through the respective current path and its direction.It is only important that the current detection device 30, however it is implemented, is designed to determine the current intensity and direction of a direct current flowing through the current paths 1 and 2 in order to detect a short-circuit current and its flow direction.

[0055] 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 first semiconductor switch 61, the diode 71, the load 90, the fuse 20 and the current detection device 30 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 device connections 11 and 12, the fuse 20 and the current detection device 30 to the device connection 14.

[0056] Furthermore, the exemplary DC voltage device 10 has two intersecting short-circuit switches 50 and 51, which can each be designed, for example, as a thyristor or triac with bidirectional current conduction. Such components are characterized by their speed, current-carrying capacity, and cost structure. The short-circuit switches 50 and 51 are each connected to an output of the control and evaluation device 40, which is designed, for example, to either switch on the short-circuit switch 50 and simultaneously switch off the short-circuit switch 51, or vice versa, depending on a detected short-circuit current and its direction.

[0057] As can be seen in Fig. 2, the first controllable short-circuit switch 50 has a first terminal 50a, which can be designed as an anode terminal, and a second terminal 50b, which can be 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 a terminal of the 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 collector electrode of the semiconductor switch 62. The short-circuit switch 50 further has a control terminal that is connected to an output of the control and evaluation device 40.

[0058] The second controllable short-circuit switch 51 has a first terminal 51a, which can be configured as an anode terminal, and a second terminal 51b, which can be configured as a cathode terminal. The first terminal 51a is electrically connected to current path 1 and is arranged between the first device terminal 11 and a second terminal of the fuse 20. The second terminal 51b is electrically connected to current path 2 and is arranged between the fourth device terminal 14 and the collector electrode of the semiconductor switch 61. The short-circuit switch 51 further has a control terminal connected to an output of the control and evaluation device 40.

[0059] In order to be able to switch the DC voltage device 10 into an energy-saving mode during operation, i.e. when 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. 2. 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 in order to open or close the mechanical switching contact 81.

[0060] To be able to close. The switching contact 81, for example, is designed as a normally open contact.

[0061] A predetermined threshold value that defines a short-circuit current is 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.

[0062] 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. The following explains the operation of DC devices 10 and 10' in conjunction with the DC system 5 shown in Fig. 1. Assume that electrical device 90 is, for example, an electrical, non-regenerative DC load.

[0063] 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.

[0064] The control and evaluation device 40 is therefore designed to control a switch-on process by first electrically conducting the semiconductor switch 61 and then electrically blocking the semiconductor switch 62. 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, for example, after a definable period of time after the semiconductor switch 61 has been switched on.Alternatively or additionally, the control and evaluation device 40 can cause the DC switching device 10 to close the mechanical switching contact 81, for example, after a predetermined current threshold is reached. For this purpose, a threshold value can be stored in the DC switching device 10, which the control and evaluation device 40 can access. The control and evaluation device 40 then compares this threshold value with the current value supplied by the current detection device 30. If the measured current value exceeds the threshold value, the control and evaluation device ensures that the mechanical switching contact 81 is closed. The direction and current intensity of the DC current are preferably continuously determined by the current detection device 30 and transmitted to the control and evaluation device 40.If a short circuit now occurs, both the semiconductor switch 61 would have to be switched off and the mechanical switching contact 81 would have to be opened. 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, short-circuit resistance can now be ensured, particularly when using an electromechanical switch.

[0065] 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 and the determined direction of the current flowing from device connection 11 to device connection 13, the control and evaluation device 40 causes the DC switching device 10 to switch on the short-circuit switch 51. From this moment on, the short-circuit current flows via the short-circuit switch 51 and the fuse 20 to the device connection 12, thereby triggering the fuse 20. Thanks to the special interconnection of the short-circuit switches 51 and 50 with the fuse 20, the load on current paths 1 and 2 and any connecting cables can be reduced in the event of a short circuit.

[0066] It should also be noted that the control and evaluation device 40 can, for example, also be configured to switch on the short-circuit switch 50 after the short-circuit switch 51 has been switched on, in order to enable a stepped short-circuit diversion with the aim of conducting a current via two paths to current path 2, which is connected to ground. In this way, for example, line capacitances to the load 90 can be short-circuited by means of the second short-circuit switch 50.

[0067] In the event that 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 designed 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 via the device terminal 13, the semiconductor transistor 62, the diode 70 and via the device terminals 11 and 12 back to the device terminal 14. A switch-on process can occur in a similar manner if the DC voltage supply device 100 is connected to the device terminals 11 and 12, and the load 90 connected to the device terminals 13 and 14 is designed to feed energy back to the DC voltage supply device 100.

[0068] 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 61 has been switched on. 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.

[0069] 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 and the determined direction of the current flowing from device connection 13 to device connection 14, 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 via the short-circuit switch 50 and the fuse 20 to the device connection 14, thereby triggering the fuse 20. Thanks to the special interconnection of the short-circuit switches 51 and 50 with the fuse 20, the load on current paths 1 and 2 and any connecting cables can be reduced in the event of a short circuit.

[0070] It should also be noted that the control and evaluation device 40 can, for example, also be configured to switch on the short-circuit switch 51 after the short-circuit switch 50 has been switched on, in order to enable a stepped short-circuit diversion with the aim of conducting a current via two paths to current path 2, which is connected to ground. In this way, for example, line capacitances to the load 90 can be short-circuited by means of the second short-circuit switch 51.

[0071] Furthermore, it should be noted that the rated current and overload current of the short-circuit switches 50 and 51, the semiconductor switches 61, 62, the diodes 70, 71, and the electromechanical switch 80 are advantageously matched to the rated current (i.e., the tripping characteristic) of the fuse 20. Preferably, the dielectric strength of the semiconductor switches 61 and 62 is greater than the operating voltage.

[0072] The functioning of the DC switching device 10' essentially corresponds to the functioning of the DC switching device 10, so that in order 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 single electrical fuse (20), - an anti-serial circuit (60) comprising a first controllable semiconductor switch (61) and a second controllable semiconductor switch (62), 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 electrical fuse (20) is arranged in the second current path (2) and the first and second semiconductor switches (61, 62) are arranged in the first current path (1), - a current detection device (30) which is designed to determine the direction and current intensity of a current flowing through the first or second current path (1, 2), - a first 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 anti-serial circuit (60), and the second terminal (50b) is electrically connected to the second current path (2) and is arranged between the third device terminal (12) and the electrical fuse (20), - a second controllable short-circuit switch (51) having a first terminal (51a) and a second terminal (51b), wherein the first terminal (51a) is electrically connected to the first current path (1) and is arranged between the first device terminal (11) and the anti-serial circuit (60), and the second terminal (51b) is electrically connected to the second current path (2) and is arranged between the fourth device terminal (14) and the 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 first or second short-circuit switch (50, 51) as a function of the direction and current intensity detected by the current detection device (30), provided that the detected current intensity reaches or exceeds a predetermined threshold value.

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 single electrical fuse (20), - an anti-serial circuit (60) comprising a first controllable semiconductor switch (61) and a second controllable semiconductor switch (62), 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 electrical fuse (20) is arranged in the first current path (1) and the first and second semiconductor switches (61, 62) are arranged in the second current path (2), - a current detection device (30) which is designed to determine the direction and current intensity of a current flowing through the first or second current path (1, 2), - a first 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 electrical fuse (20), and the second terminal (50b) is electrically connected to the second current path (2) and is arranged between the third device terminal (12) and the anti-serial circuit (60), - a second controllable short-circuit switch (51) having a first terminal (51a) and a second terminal (51b), wherein the first terminal (51a) is electrically connected to the first current path (1) and is arranged between the first device terminal (11) and the electrical fuse (20), and the second terminal (51b) is electrically connected to the second current path (2) and is arranged between the fourth device terminal (14) and the anti-serial circuit (60), - 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 first or second short-circuit switch (50, 51) as a function of the direction and current intensity detected by the current detection device (30), provided that the detected current intensity reaches or exceeds a predetermined threshold value.

3. DC voltage switching device according to claim 1 or 2, further comprising a mechanical switching contact (81) of an electromechanical switch (80), wherein the mechanical switching contact is connected in parallel to the first and second semiconductor switches (61, 62), wherein the control and evaluation device 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) is connected to the first and third device terminals (11, 12) and a DC voltage supply device (100) is connected to the second and fourth Device connection (13, 14) can be connected to an electrical device (90) 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 detection device (30) is connected in series with the fuse (20) or the anti-serial circuit (60).

7. DC switching device according to one of the preceding claims, wherein the first and second short-circuit switches (50, 51) are 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 (90) connected to the DC voltage device (10; 10') and an electrical device (100) 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 the positive pole and the third and fourth device terminals (12, 14) are each defined as the negative pole, wherein the control and evaluation device (40) of the DC voltage switching device (10; 10') is designed to firstly switch the first semiconductor switch (61) to be conductive and then to close the mechanical switching contact (81) when a current is to flow from the first device terminal (11) to the third device terminal (12), and, when the current intensity measured by the current detection device (30) reaches or exceeds the predetermined threshold value, to close the first short-circuit switch (50), or to firstly switch the second semiconductor switch (62) to be conductive and then to close the mechanical switching contact (81) when a current is to flow from the second device connection (13) to the fourth device connection (14), and, when the current intensity measured by the current detection device (30) reaches or exceeds the predetermined threshold value, to close the second short-circuit switch (51).

10. DC voltage system (5; 5') according to claim 8 or 9, wherein the DC voltage supply device (90) is a DC supply network.

Images