Electrical switch for interrupting an electrical high voltage connection and method for interrupting an electrical high voltage connection

Abstract

The present invention relates to an electrical switch (102) for interrupting a high-voltage electrical connection (108), particularly in a power supply system of a vehicle (100), wherein the switch (102) has the following features: a. a first interface (202) for connecting a first sub-section of the high-voltage connection (108) and a second interface (204) for connecting a second sub-section of the high-voltage connection (108); b. a first contact (206) electrically connected to the first interface (202) and a second contact (208) electrically connected to the second interface (204), wherein the first contact (206) and the second contact (208) are electrically connected to each other at a separable contact point (110); c. an overcurrent disconnect device (112) electrically connected to the second interface (204); and d.an arc switch (114) designed to generate, in the event of an overload, a substitute arc (402) leading to the overcurrent disconnect device (112) to a switching arc (300) that arises during operation when the contact point (110) between the first contact (206,210) and the second contact (208) is interrupted.

Description

Technical field

[0001] The present invention relates to an electrical switch for interrupting a high-voltage electrical connection, a motor vehicle with a corresponding switch and a method for interrupting a high-voltage electrical connection. State of the art

[0002] The present invention is described below primarily in connection with switching elements for vehicle electrical systems. However, the invention can be used in any application where electrical loads are switched.

[0003] When the live contacts of a switch are interrupted, a switching arc can occur. This arc can damage the contacts, especially in overload situations, because it can generate a high energy input. To prevent this damage, a fuse can be connected in series with the switch. The fuse interrupts the current flow in the switching arc when the energy accumulated in the fuse due to ohmic losses, and the associated heating of the fuse's tripping area, exceeds a characteristic limit value for that fuse.

[0004] In a fuse, a constriction melts in the event of an overload. This constriction should be dimensioned so that the current can flow under normal circumstances without excessive heating, but is reliably destroyed in the event of an overload.

[0005] DE 42 43 314 A1 discloses a current-limiting switch.

[0006] The publication EP 3 157 033 A1 relates to an interruption chamber of an electrical protective device which includes an arc formation chamber.

[0007] Publication US 3 004 116 A shows a combination of insulating materials to support a relatively stationary contact in an air disconnect switch.

[0008] WO 2017 / 063683 A1 refers to an AC contactor that contains a diode for arc quenching.

[0009] Document WO 2019 / 057870 A1 concerns an electrical switch for interrupting a current path. Description of the invention

[0010] One object of the invention may therefore be to provide a switch and a method for interrupting a high-voltage connection, as well as a vehicle equipped with the switch, using means that are as simple as possible in terms of construction.

[0011] The problem is solved by the subject matter of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims, the description, and the accompanying figures. In particular, the independent claims of one claim category may also be further developed analogously to the dependent claims of another claim category.

[0012] An electrical switch for interrupting a high-voltage electrical connection, particularly in a vehicle's power supply system, is presented, wherein the switch has the following features: a. a first interface for connecting a first section of the high-voltage connection and a second interface for connecting a second section of the high-voltage connection; b. a first contact electrically connected to the first interface and a second contact electrically connected to the second interface, wherein the first contact and the second contact are electrically connected to each other at a separable contact point; c. an overcurrent disconnect device electrically connected to the second interface; and d. an arc switch configured to generate, in the event of an overload, a substitute arc leading to the overcurrent disconnect device to replace a switching arc that occurs during operation when the contact point between the first contact and the second contact is interrupted.

[0013] Furthermore, a method for interrupting an electrical high-voltage connection, particularly in a vehicle's power supply system, is presented, wherein the method comprises an interruption step, a generation step, and an extinguishing step, wherein in the interruption step a contact point of an electrical switch arranged in the high-voltage connection is disconnected in response to a disconnect signal, in the generation step a substitute arc leading to an overcurrent disconnect device of the switch, which is de-energized when the contact point is closed, is generated to form a switching arc in the disconnected contact point using an arc diverter, and in the extinguishing step the substitute arc is extinguished by activating the overcurrent disconnect device.

[0014] Furthermore, a vehicle with at least one switch according to the approach presented here is presented, wherein the switch is arranged in an electrical high-voltage connection of a voltage supply system of the vehicle, wherein a contact point of the switch can be disconnected using an actuator responding to a disconnect signal.

[0015] A high-voltage connection can be an electrical conductor in a hybrid or electric vehicle designed to safely conduct automotive high voltage. Automotive high voltage can be understood to mean, in particular, an electrical voltage between 300 and 1000 volts. Additionally, the high-voltage connection has a conductor cross-section required to transmit the vehicle's electrical drive power. The high-voltage connection can be implemented as a cable or busbar. Current-carrying components of the switch, such as interfaces and contacts, have a conductor cross-section adapted to the conductor cross-section of the high-voltage connection and corresponding contact surfaces.

[0016] The switch's interfaces can be referred to as connection terminals and include devices for the safe electrical contacting of the high-voltage connection components. When the contact point is closed, the switch contacts can be pressed directly together or connected via intermediate conductive elements. When the contact point is open, the contacts or the intermediate elements can be pushed or pulled apart. When the contact point is open, the contacts can be spaced apart by a distance adapted to the high-voltage voltage.

[0017] An overcurrent disconnect device can be designed to absorb the necessary disconnect power for a short circuit in the high-voltage vehicle electrical system. This can be, for example, 1.5 MW in a 450V system and up to 5 MW in a 900V system. The overcurrent disconnect device is de-energized during normal operation and is only energized in the event of an overload. If the overcurrent disconnect device is implemented as a sand-filled fuse, it can be significantly smaller in the approach presented here than a conventional fuse connected in series with the contact point. Due to the small size of the fuse wire, the overcurrent disconnect device can have a very short response time.

[0018] In an electric arc, gas is ionized, and charge carriers move from one side of the arc to the other, driven by an electrical potential difference. The gas can be ionized, for example, by an electric field, i.e., an electrical potential between two electrodes. These electrodes can then also be the starting and ending points of the arc. The starting and ending points are defined by the direction of an electric current flowing to equalize the electrical potential. The arc follows the path of least resistance. The number of charge carriers in the arc is determined by the electric current flowing through it. The greater the current flow, the stronger the heat emission from the arc. The gas can be further ionized by this heat emission. An ionized channel can thus form between the electrodes.

[0019] An arc diverter can provide a new path with a lower resistance than the original path of a switching arc generated at the contact point when the contacts separate. This does not result in a simple arc jump, i.e., the immediate extinction of the primary arc (referred to as the switching arc). Instead, the switching arc and a substitute arc initially burn simultaneously, potentially sharing a common base point. This base point can be located on the path between the two contacts of the actual contact point, either on one of the contacts or between them. The common base point can also shift repeatedly during the separation process to achieve the lowest overall resistance. Due to its lower resistance, the substitute arc draws energy from the switching arc until the switching arc extinguishes.The substitute arc is extinguished by the activation of the overcurrent disconnect device.

[0020] The arc-break device can comprise the first contact, a movable jumper that electrically connects the first contact to the second contact when the contact point is closed, and an electrode of the overcurrent disconnect device. The jumper can be spaced apart from the electrode when the contact point is closed. When the contact point is broken, the jumper can be designed to be lifted from the first contact towards the electrode to generate the replacement arc. The jumper can be a movable part of the second contact. Alternatively, the jumper can also be lifted from the second contact when the contact point is broken. If the switch is intended only for interrupting the high-voltage connection, particularly for a single interruption, the jumper can make direct contact with the electrode when the contact point is broken. The replacement arc can then ignite shortly before contact.To switch the high-voltage connection during operation, a separate switching point can be provided in series with the contact point.

[0021] The switching bridge can be spaced from the electrode by an air gap when the contact point is separated. The minimum energy transfer required to generate the substitute arc in the arc switch can depend on the air gap. The air gap allows the switch to also be used to switch the high-voltage connection during operation. The switch can be designed for a corresponding number of switching cycles. The air gap can be referred to as the air gap. The air gap can be dimensioned such that a flashover of the substitute arc to the overcurrent protection device only occurs above a defined energy input, charge carrier density, or current threshold, but not below it, so that the overcurrent protection device remains inactive.The air gap makes the arc-stop device energy-dependent, otherwise the overcurrent protection device would trip immediately with every switching operation. The air gap can be so large that the substitute arc only jumps at an instantaneous power greater than 10 kW, especially greater than 25 kW, and particularly greater than 50 kW.

[0022] With a separated contact point, the arc gap between the first contact and the switching bridge can be greater than the air gap. The arc gap can be the shortest geometric path for the switching arc between its starting and ending points. An obstacle between the starting and ending points can influence the arc gap, as the switching arc will then follow a longer arc path around the obstacle. The arc gap can also be influenced by a non-contact force acting on the switching arc, such as air movement and / or a magnetic field. If the arc gap is longer than the air gap, a substitute arc can ignite.

[0023] The electrode may be overmolded with a thermoplastic insulator. The minimum energy transfer required to ignite a substitute arc in the arc switch may depend on the thickness of the insulator. This minimum energy transfer may also depend on the specific resistance of the thermoplastic insulator material. If the minimum energy transfer in the switching arc is exceeded, the insulator may melt and expose the electrode. The switching bridge may then touch the electrode, resulting in direct electrical contact between the two. Alternatively, the remaining air gap between the switching bridge and the electrode may be so small that the substitute arc exhibits a low energy transfer.

[0024] A further overcurrent disconnect device can be electrically connected to the second interface. The arc disconnect device can comprise the first contact, the second contact, a movable switching bridge that electrically connects the first contact to the second contact when the contact point is closed, an electrode of the overcurrent disconnect device, and a further electrode of the further overcurrent disconnect device. When the contact point is closed, the switching bridge can be spaced apart from the electrode and the further electrode. When the contact point is open, a combined arc gap between the switching bridge and the first contact and between the switching bridge and the second contact can be greater than both the first air gap between the first contact and the further electrode and the second air gap between the second contact and the electrode.Individual arc gaps between the contacts and the switching bridge can add up to the combined arc gap. As soon as one of the air gaps is smaller than the combined arc gap, this air gap can be attractive enough to ignite the substitute arc.

[0025] The arc switch may have a movable separating element that can be positioned between the first and second contacts. The separating element can increase the arc gap between the first and second contacts, cover the first contact, and, alternatively or additionally, cover the second contact if it is positioned at the contact point. A separating element may be made of an electrically insulating material, such as ceramic. The separating element can push the contacts apart. The separating element may be wedge-shaped. The separating element may be actuated by a drive mechanism. The separating element can geometrically increase the arc gap because it presents an obstacle to the switching arc. The separating element can reduce the relative distance to the electrode of the overcurrent protection device, thereby igniting the substitute arc for the overcurrent protection device.The isolating element can make an initial current path very unattractive to the arc. The isolating element can be moved in front of the first contact and cover it. This covering prevents the switching arc from reigniting after the overcurrent disconnect device has been triggered.

[0026] The arc switch can include at least one blow-out magnet for extending the switching arc. The field direction of the blow-out magnet can be oriented perpendicular to the path of the switching arc. A blow-out magnet can provide a magnetic field. Due to the Lorentz force, the magnetic field can exert a lateral force on moving charge carriers. Since the switching arc consists of moving charge carriers, it can be deflected laterally using at least one blow-out magnet. The direction of the deflection depends on the direction of movement of the charge carriers and the field direction of the magnetic field. The blow-out magnet can be oriented such that the switching arc is deflected towards the electrode of the overcurrent protection device.

[0027] The blow-out magnet can be an electromagnet connected between the second interface and the switching bridge. When the contact point is broken, the switching bridge can be positioned at a distance from the first and second contacts. Upon breaking the contact point, the electromagnet can be energized by an electric current flow resulting from a voltage drop across a further switching arc between the switching bridge and the second contact. This current-direction-dependent magnetic field is then generated to extend the switching arc, always in the direction of the overcurrent disconnect device. If a permanent magnet is used as the blow-out magnet, the direction of its lateral deflection changes depending on the direction of the current flow.To ensure the direction of the deflection remains constant and the switching arc is extended towards the electrode of the overcurrent protection device even with differing current directions, the field direction can be set depending on the current direction. This field direction can be set using a current-carrying coil. The coil is part of the electromagnet. The current direction in the coil depends on the current direction through the switch. With the electromagnet, only one overcurrent protection device is required.

[0028] The overcurrent protection device is designed as a sand-filled fuse. The fuse is destroyed upon activation. When the fuse blows, a melting element melts, and an electric arc forms in its place. The energy released by the arc melts at least part of the sand filling. The molten sand then interrupts or extinguishes the arc, thus eliminating the substitute arc. Because the overcurrent protection device is de-energized during normal operation, the fuse can blow quickly if the substitute arc ignites.

[0029] The switch may include a measuring device for detecting the flow of electrical current between the interfaces. This measuring device may be configured to provide a disconnect signal to interrupt the contact point when the current flow exceeds a threshold value. By measuring the current flow and interrupting in response to the disconnect signal, the switch can automatically interrupt the high-voltage connection before other live parts are damaged. Brief character description

[0030] An advantageous embodiment of the invention is explained below with reference to the accompanying figures. These show: Fig. 1 shows a vehicle with a switch according to an embodiment; Fig. 2 shows a switch with a disconnecting element according to an embodiment; Figs. 3 to 4 show an interruption process of a high-voltage connection using a switch with a disconnecting element according to an embodiment; Fig. 5 shows a switch with a further overcurrent disconnecting device according to an embodiment; Figs. 6 to 8 show an interruption process of a high-voltage connection using a switch with a further overcurrent disconnecting device according to an embodiment; Fig. 9 shows an interruption process of a high-voltage connection using a switch with an electromagnet according to an embodiment; and Fig. 10 shows a switch with an insulated electrode according to an embodiment.

[0031] The figures are merely schematic representations and serve only to illustrate the invention. Identical or equivalent elements are consistently identified by the same reference numerals. Detailed description

[0032] For easier understanding, the reference symbols to the following description are used. Figures 1-10 retained as a reference.

[0033] Fig. 1 Figure 1 shows a representation of a vehicle 100 with a switch 102 according to an exemplary embodiment. The vehicle has a traction battery 104 and at least one electric drive unit 106. The traction battery 104 is connected to the drive unit 106 via a high-voltage connection 108. For the sake of simplicity, the control electronics required for the operation of the drive unit 106 are not shown here.

[0034] The switch 102 is located between the traction battery 104 and the drive unit 106 in the high-voltage connection 108. Each terminal of the traction battery 104 is connected via a line of the high-voltage connection 108 to a corresponding terminal of the drive unit 106. The switch 102 has separate contacts for each terminal. The switch 102 is therefore multi-pole and designed to disconnect the traction battery 104 from the rest of the vehicle 100 at all poles.

[0035] For each pole, the switch 102 has a contact point 110 between a section of the high-voltage connection 108 connected to the traction battery 104 and a section of the high-voltage connection 108 connected to the drive unit 106. Additionally, the switch has for each pole an overcurrent disconnect device 112, which during operation is connected to only one of the sections of the high-voltage connection 108, and an arc switch 114. The arc switch 114 is designed to generate, in the event of an overload, a substitute arc leading to the overcurrent disconnect device 112 to replace the switching arc that occurs when the contact point 110 is interrupted.

[0036] Fig. 2 Figure 1 shows a representation of a switch 102 with a separating element 200 according to an exemplary embodiment. The switch 102 essentially corresponds to the switch in Figure 1. Fig. 1In contrast, the switch 102 shown here is single-pole. The switch 102 has a first interface 202 to a first section of the high-voltage connection and a second interface 204 to a second section of the high-voltage connection. The first interface 202 is electrically connected to a first contact 206 of the contact point 110. The second interface 204 is electrically connected to a second contact 208 of the contact point 110.

[0037] A movable switching bridge 210 is arranged between the first contact 206 and the second contact 208, and is rigidly connected to the first contact 206 via an electrically conductive joint. When the contact point 110 is closed, the switching bridge 210 is pressed against the second contact 208, so that they are conductively connected. The switching bridge 210 is pressed against the second contact 208, for example, by a spring force.

[0038] A first terminal of the overcurrent disconnect device 112 is electrically connected to the second interface 204 and the second contact 208. A free second terminal of the overcurrent disconnect device 112 is connected to an electrode 212 of the arc diverter 114. The second contact 208, the isolating element 200, and the switching bridge 210 are further components of the arc diverter 114. When the contact point 110 is closed, the switching bridge 210, and thus also the first contact 206, are spaced apart from the electrode 212.

[0039] The separating element 200 is wedge-shaped and designed to be inserted between the second contact 208 and the switching bridge 210 in order to lift or push the switching bridge 210 away from the second contact 208. During lifting or pushing, the switching bridge 210 is moved towards the electrode 212. When the contact point 110 is broken, the movable separating element 200 covers the second contact 208.

[0040] In one embodiment, the switch 102 is designed as a single-use disconnect switch for overload situations. For switching under normal operating conditions, another switch (not shown) is connected in series with the illustrated switch 102. When the contact point 110 is interrupted by the disconnecting element 200, the switching bridge 210 is pressed against the electrode 212. This establishes direct contact between the switching bridge 210 and the electrode 212. In an overload situation, the previously de-energized overcurrent disconnect device 112 then immediately activates and reliably interrupts the current flow. Since the overcurrent disconnect device 112 is de-energized in normal operating conditions, it can be dimensioned accordingly and activate even with a small current flow.

[0041] In one embodiment, the switch 102 is designed to be used as an operating switch under normal operating conditions. Here, the switching bridge 210 and the electrode 212 are separated from each other by an air gap 214, even when the contact point 110 is interrupted. The switching bridge 210 therefore never touches the electrode 212. Energy transfer can only occur through a substitute arc ignited between the switching bridge 210 and the electrode 212.

[0042] The Figures 3 and 4 Figure 1 shows illustrations of an interruption process of a high-voltage connection using a switch 102 with a disconnecting element 200 according to an exemplary embodiment. The switch 102 essentially corresponds to the switch in Figure 1. Fig. 2The high-voltage connection (not shown) is connected to interfaces 202 and 204, and there is an overload situation in which it is necessary to safely interrupt the high-voltage connection, for example to disconnect the drive unit from the traction battery in case of damage.

[0043] In Fig. 3The separating element 200 begins to lift the switching bridge 210 from the second contact 208. In the resulting gap, a switching arc 300 ignites between the switching bridge 210, connected to the first contact 206, and the second contact 208. The switching arc 300 generates a plasma of free charge carriers between the switching bridge 210 and the second contact 208. The separating element 200 pushes the switching bridge 210 towards the free electrode 212 of the overcurrent disconnect device 112. Due to the electrically conductive connection through the overcurrent disconnect device 112, the electrode 212 is at the same electrical potential as the second contact 208. An electric field is generated between the switching bridge 210 and the electrode 212. The field strength of the electric field increases as the air gap 214 decreases.

[0044] In Fig. 4The separating element 200 extends an arc gap 400 from the switching bridge 210 around the separating element 200 to the second contact 208 to such an extent that a substitute arc 402 via the air gap 214 between the switching bridge 210 and the electrode 212 offers a path with lower electrical resistance than the path via the primary arc gap 400. The plasma of the switching arc floods the area of ​​the air gap 214 with free charge carriers. This ignites the substitute arc 402 between the switching bridge 210 and the electrode 212. The switching arc 300 extinguishes due to its higher electrical resistance, and the electrical energy to be dissipated is discharged by the overcurrent disconnect device 112.

[0045] Since the electrical energy conducted through the overcurrent disconnect device 112 is greater than the response threshold of the overcurrent disconnect device 112, the overcurrent disconnect device 112 activates and permanently interrupts the electrical current flow through the high-voltage connection. The substitute arc 402 extinguishes. The isolating element 200 covers the second contact 208 and thus prevents the switching arc 300 between the switching bridge 210 and the second contact 208 from reigniting.

[0046] Fig. 5 Figure 1 shows a representation of a switch 102 with a second overcurrent disconnect device 500 according to an exemplary embodiment. The switch 102 essentially corresponds to the switch in Figure 1. Fig. 2In contrast, the switching bridge 210 is movable on both sides, i.e., it can be lifted off the first contact 206 and the second contact 208. One end of the second overcurrent disconnect device 500 is connected to the first interface 202. The other end of the second overcurrent disconnect device 500 is connected to a second electrode 502. In contrast to the illustration in Fig. 2 The first electrode 212 of the first overcurrent disconnect device 112 is spaced from the first contact 206 by the first air gap 214, while the second electrode 502 is spaced from the second contact 208 by a second air gap 504. The air gaps 214 and 504 are of equal length. In other words, the overcurrent disconnect devices 112 and 500 are installed in a mirrored configuration.

[0047] In one embodiment, a first blow-out magnet 506 is arranged in the region of the first contact 206 and the first electrode 212. A second blow-out magnet 508 is arranged in the region of the second contact 208 and the second electrode 502. The blow-out magnets 506 and 508 each provide magnetic fields oriented in opposite directions.

[0048] The Figure 6 , 7 and 8 Figures 1 and 2 show illustrations of an interruption process of a high-voltage connection using a switch 102 with a further overcurrent disconnect device 500 according to an exemplary embodiment. As shown in the Figures 3 and 4 The high-voltage connection is linked to interfaces 202 and 204, but is not shown.

[0049] In Fig. 6The switching bridge 210 is lifted from the first contact 206 and the second contact 208 by an actuator (not shown). A switching arc 300 is ignited at each of the two contacts 206 and 208. Since the switching arcs 300 are connected in series, their arc lengths 400 add up to a total arc length. The charge carriers in both switching arcs 300 move perpendicular to the magnetic fields of the blow-out magnets 506 and 508. The resulting Lorentz force deflects the switching arcs 300 laterally. The arc lengths 400 are lengthened by this lateral deflection. The total arc length increases accordingly.

[0050] Due to the Lorentz force, the switching arc 300 between the first contact 206 and the switching bridge 210 is additionally deflected in the direction of the first electrode 212, which is at the same electrical potential as the second contact 208 via the electrically conductive first overcurrent disconnect device 112.

[0051] In Fig. 7 The total arc distance, combined from the individual arc gaps 400, became greater than the first air gap 214. The substitute arc 402 ignited between the first contact 206 and the first electrode 212, and the first overcurrent disconnect device 112 activated. At the same time, the switching arc between the second contact 208 and the switching bridge 210 also extinguished, as this current path was interrupted.

[0052] In Fig. 8 the current flows in the opposite direction to what is shown in the Figure 6 and 7This causes the Lorentz force to act in the opposite direction. The switching arc 300 between the switching bridge 210 and the second contact 208 is deflected towards the second electrode 502. As a result, the total arc distance is greater than the second air gap 504. The substitute arc 402 has ignited between the second contact 208 and the second electrode 502, and the second overcurrent disconnect device 500 is activated. The switching arc between the first contact 206 and the switching bridge 210 also extinguishes, as this current path is interrupted.

[0053] Fig. 9 Figure 1 shows a representation of an interruption process of a high-voltage connection using a switch 102 with an electromagnet 900 according to an exemplary embodiment. The switch 102 essentially corresponds to the switch in the Figures 5 to 7In contrast, the switch 102 shown here has only one overcurrent disconnect device 112 and, accordingly, only one electrode 212, which is effective for both current directions. The electrode 212 is as shown in Fig. 2 arranged in the area of ​​the second contact 208, but is as in Fig. 5 spaced apart from the second contact 208 by the air gap 214.

[0054] Likewise, as in Fig. 5The switching bridge 210 is movable on both sides and can be lifted from both the first contact 206 and the second contact 208 by an actuator 902 in response to a disconnect signal 904. This causes two switching arcs 300 to ignite when the contact point 110 is interrupted. Since the switching arcs 300 have a higher electrical resistance than the electrical conductors of the contacts 206, 208, and the switching bridge 210, an electrical voltage drops across the switching arcs 300. The voltage drop of the switching arc 300 between the switching bridge 210 and the first contact 206 is tapped here to redirect the switching arc 300 between the second contact 208 and the switching bridge 210 to the electrode 212. For this purpose, the electromagnet 900 is connected between the first contact 206 and the switching bridge 210.The electromagnet 900 generates a magnetic field whose field lines are aligned perpendicular to the direction of movement of the charge carriers of the arc when current flows through it.

[0055] The direction of current in electromagnet 900 is therefore dependent on the direction of current through switch 102. Consequently, the direction of the magnetic field generated by electromagnet 900 also depends on the current direction. The field direction thus always corresponds to the direction of the charge carriers in the switching arc 300. The switching arc is therefore always deflected in the direction of electrode 212.

[0056] If the total arc length across both switching arcs 300 is greater than the air gap 214, the substitute arc (not shown here) ignites at electrode 212, and the resulting current flow through the overcurrent disconnect device 112 causes it to activate. The activation of the overcurrent disconnect device 112 permanently interrupts the high-voltage connection.

[0057] Fig. 10 Figure 1 shows a representation of a switch 102 with an insulated electrode 212 according to an exemplary embodiment. The switch 102 essentially corresponds to the switch in Figure 2. Fig. 2 In contrast, the electrode 212 of the overcurrent disconnect device 112 is arranged here within a contact circle of the rotatably mounted switching bridge 210 and covered by an insulator 1000 made of a thermoplastic material. The switching bridge 210 can abut the insulator 1000. During a normal switching operation, the insulator 1000 prevents direct electrically conductive contact between the switching bridge 210 and the electrode 212. The thickness of the insulator 1000 then corresponds to the remaining air gap 214.

[0058] When the switching bridge 210 is in contact with the insulator 1000, the air gap 214 is very small, resulting in a high-strength electric field between the switching bridge 210 and the electrode 212. This electric field affects the weaker switching arc that also occurs during normal switching at the contact point 110. The electric field deflects the switching arc into an arc shape, thereby lengthening its arc path. Due to the increased arc path, the switching arc extinguishes more quickly because its electrical resistance increases sharply with the length of the arc.

[0059] When the contact point 110 is separated, the separating element 200 also extends the arc gap, since the switching arc burns around the separating element 200. In one embodiment, to interrupt the switching arc, the separating element 200 penetrates a notch 1002 in a housing of the switch 102 after the contact point 110 has separated. By penetrating the notch 1002, the switching arc can be effectively cut off.

[0060] In the event of an overload, the switching arc releases so much thermal energy that the insulator 1000 at least partially melts and / or vaporizes. This exposes the electrode 212 and ignites the substitute arc between the switching bridge 210 and the electrode 212. Because the switching bridge 210, due to the melted insulator 1000, comes very close to the electrode 212, or may even directly touch it, the substitute arc releases only a small amount of thermal energy until the overcurrent disconnect device 112 activates and extinguishes the substitute arc.

[0061] In other words, they show Figures 1 to 10Arc-delay switches. These switches can be used for protection and switching in high-voltage (HV) electrical systems. The previously used series-connected fuses for thermal protection of the lines can be eliminated with this approach. The problems that arise when using conventional contactors and fuses in series due to the combination of these two components are thus avoided.

[0062] In the event of a short circuit, for example, the lifting of the switching contacts or contact levitation due to electromagnetic forces leads to uncontrolled arcing in the contactor, which delays the ignition of the series-connected fuse. The contactor thus influences the fuse's behavior.

[0063] Additionally, due to the inertia of fuses connected in series, large conductor cross-sections are necessary for small overcurrents and dynamic current profiles. Furthermore, a series-connected fuse, by its very design as a predetermined breaking point, is always a significant source of thermal losses. This heat input can cause problems in the dimensioning of high-voltage (HV) switchgear boxes and may even necessitate active cooling devices.

[0064] Conventional contactors cannot handle the interrupting power required in the event of a short circuit in the vehicle electrical system and can explode, for example, at a short-circuit current exceeding three kiloamperes (kA), when they are triggered to open. To prevent this, the contactors can remain closed, and the series-connected fuse, with its sand filling, is intended to carry the interrupting power, absorb the interrupting energy, and thus break the current flow. Conventional series-connected fuses face a conflicting objective: on the one hand, they must be able to carry the load current with minimal losses and heat generation, which can be achieved by using the largest possible cross-section of the constriction; on the other hand, they must interrupt the circuit as quickly as possible in the event of a short circuit, which can be achieved by using the smallest possible cross-section of the constriction to prevent the dissipated interrupting energy (power times time) from becoming too high.

[0065] The switch 102 presented here can perform both the switching function of the contactor and the protection function of the fuse. The central element of the switch 102 is an "arc diverter" 114.

[0066] When the short-circuit current is switched off, an arc is drawn up by opening contacts 206, 208 (positive primary contact and negative primary contact). This arc is then separated by a separating element 200, for example a wedge made of an insulating material, against an insulator. Figures 1 to 10The secondary contact, designated electrode 212, is pushed forward, and simultaneously the negative (or positive, or both) primary contact is covered by the isolating element 200. A second arc is generated at the secondary contact. This secondary contact, in turn, is connected to a preferably sand-filled fuse cell, in which the disconnection energy is ultimately dissipated. The fuse cell is one possible form of overcurrent disconnect device and can be described as a "sacrificial section." With the melting of the fuse wire and the extinguishing of the arc by the cooling liquefied sand, the arc is extinguished, and the switch 102 interrupts the current flow. The path is galvanically isolated.The fuse cell is dimensioned in such a way that the arc between the primary contacts is extinguished first, and only then is the arc in the fuse cell interrupted in order to prevent the majority of the arc energy from "falling back" to the arc between the primary contacts.

[0067] An active pyrofuse can be used as an overcurrent disconnect device instead of a standard fuse. However, sand-filled fuse elements are generally advantageous for energy absorption during short-circuit interruption.

[0068] The approach presented here results in cost savings through a smaller overcurrent disconnect device than in series circuits, significantly lower heat input and space savings.

[0069] The approach presented here makes it possible to combine the safety-relevant function of switching and protecting the HV voltage in one component and thus to ensure precise function, especially during the transition from normal operation to fault operation at switching loads of approximately 1,000 A to 2,000 A.

[0070] The arc-delay circuit eliminates the need for the series fuse element, which previously caused significant heat input into the switch box due to its resistance. In the approach presented here, the fuse element is only energized in the event of a fault. This means the continuous current-carrying capacity of the system is no longer limited by the fuse. Previously, the fuse element could only be sized to prevent damage to the wiring and, in particular, the high-voltage contactors, especially from burning out. At this maximum rated value, the continuous current-carrying capacity of the fuse is naturally also limited due to the thermal stress limit.

[0071] The approach presented here can take into account the ever-increasing demands on the "DC fast charging" of electric vehicles and achieve an increased continuous current carrying capacity.

[0072] In the approach presented here, during the interruption of the short-circuit current, only the arc at the short-circuit point burns in addition to the arc in the fuse element. Previously, when using conventional high-voltage contactors, two additional arcs always occurred at the two contactor contacts due to contact levitation (contact lifting due to Lorentz and Holm's constraint forces), typically starting at 6,000 A.

[0073] The arc-fuse diverter 114 allows the use of a parallel-connected fuse or other fuse-like isolating element, particularly one filled with sand, with a high-voltage contactor. The arc-fuse diverter uses a secondary contact that directs the current into this fuse element.

[0074] In Fig. 2A switch 102 is shown with an additional secondary contact designated as electrode 212 and a sand-filled safety element designated as overcurrent disconnect device 112.

[0075] In one embodiment, the illustrated switch 102 includes a device (not shown) for measuring the current for an intelligent protection function. If a short-circuit current exceeds an upper current threshold, for example 1000 A, the opening of the contactor is initiated.

[0076] In another embodiment, the switch 102 is designed to process a trigger signal which is intended to lead to shutdown.

[0077] The following describes the shutdown process. Particular attention is paid to the fault condition, i.e., the overload situation. The regular switching cycles are identical; only the arc behavior differs.

[0078] In Fig. 3A separating element 200, for example a wedge made of an insulating material, lifts the contact lever and an electric arc is drawn up.

[0079] In Fig. 4 The insulator wedge covers the primary contact on the right.

[0080] After the primary contact on the right is covered, the arc initially burns in the narrow gap between the insulator and the primary contact and around the tip of the separating element 200. Since the volume in the gap is very limited and the separating element 200 further increases the arc length, the voltage drop in the arc rises rapidly. Simultaneously, charge carriers are accelerated to the secondary contact, which is also at the lower potential. Depending on the charge carrier density and the distance of the secondary contact to the contact lever, a second arc ignites between the contact lever and the secondary contact. Due to the resistance ratios, the energies of the two arcs are divided. Because the separating element 200 obstructs the primary arc, a large portion of the short-circuit current is diverted into the secondary path before the primary arc is completely extinguished.In the fuse element located in the secondary path, several constrictions burn through as a result of the short-circuit current and the associated input of thermal energy. Due to the fuse's design, a long arc is quickly generated, in which the essential energy transfer, which is necessary for interrupting the short-circuit current, takes place. The instantaneous power can reach up to approximately 5 MW and locally melts the sand filling. The molten sand extinguishes the arc, thus interrupting the current flow. Through appropriate timing of the interruption process, the breaking element 200 is advanced sufficiently within the fuse element during the interruption of the current flow to prevent the arc from "jumping back" to the primary contact.

[0081] The principle of diverting the electric arc into a secondary safety element in a charge carrier-controlled (energy-guided) manner is called an arc diverter.

[0082] In Fig. 5 A switch 102 with a bridge contact and an arc diverter is shown. Two secondary contacts are provided here, as the switch 102 is intended to be able to disconnect bidirectionally with the same separation capability.

[0083] In Fig. 6 The figure shows how two arcs are formed when the contact bridge opens. The blow-out magnets 506 and 508, with their different field directions, blow the arcs out of the contact area in a lens shape to the left when the current flows from right to left in the arrangement (conventional current direction).

[0084] In Fig. 7 The diagram shows that with further opening and at high current intensities, the arc is blown against the left secondary contact. The current commutates as in the Figures 3 and 4The secondary contact is described in detail, as this eliminates the voltage drop across the second arc at the bridge primary contact on the right ("incentive" for commutation).

[0085] In Fig. 8 Commutation to the right secondary contact is shown when the current flows from left to right (conventional current direction).

[0086] In Fig. 10 The secondary electrode is surrounded by a thermoplastic material that acts as an insulator. When regular currents are interrupted, an electric field builds up between the moving primary contact and the secondary electrode. This deflects the charge carriers of the arc, which occurs when the moving insulator penetrates between the primary contacts, towards the insulated secondary electrode. This results in a greater arc length, which helps the moving insulator to constrict the arc.

[0087] Since the thermal energy of the arc is normally insufficient to melt the insulator of the secondary electrode, the secondary electrode does not function as an arc diverter, but rather has an arc-extending effect, which is otherwise performed by a blow-out magnet.

[0088] When disconnecting fault currents, the thermal energy of the arc is sufficient to melt the thermoplastic insulation of the secondary electrode. Once the electrode is exposed, the secondary arc builds up between the movable primary contact and the secondary electrode. The movable insulator constricts the remaining primary arc, and the main disconnecting power is commutated into the overcurrent disconnect device connected to the secondary electrode. In this case, the secondary electrode thus acts as an arc diverter.

[0089] In Fig. 10The insulator 1000 is shown on the secondary electrode. This design is advantageous because, after the thermoplastic melts, there is a small gap between the movable primary contact and the secondary electrode, which keeps the arc voltage and thus the power output in the arc low. Furthermore, the insulation prevents premature ignition of the secondary arc under low switching loads.

[0090] Since the devices and methods described in detail above are exemplary embodiments, they can be modified extensively by a person skilled in the art without departing from the scope of the invention. In particular, the mechanical arrangements and the relative sizes of the individual elements are chosen only as examples. REFERENCE MARK LIST

[0091] 100 Vehicle 102 Switch 104 Traction battery 106 Drive unit 108 High-voltage connection 110 Contact point 112 Overcurrent disconnect device 114 Arc switch 200 Separating element 202 First interface 204 Second interface 206 First contact 208 Second contact 210 Switching bridge 212 Electrode 214 Air gap 300 switching arcs 400 Arc gap 402 Replacement arc 500 Second overcurrent disconnect device 502 Second electrode 504 Second air gap 506 First blow magnet 508 Second blow magnet 900Electromagnet 902Actuator 904Disconnection signal 1000Isolator 1002Notch

Claims

1. Electrical switch (102) for interrupting a high-voltage electrical connection (108), wherein the switch (102) has the following features: a. a first connection terminal (202) for connecting a first subsection of the high-voltage connection (108) and a second connection terminal (204) for connecting a second subsection of the high-voltage connection (108); b. a first contact (206) electrically conductively connected to the first connection terminal (202) and a second contact (208) electrically conductively connected to the second connection terminal (204), wherein the first contact (206) and the second contact (208) are electrically conductive connected to one another at a disconnectable contact point (110); c. an overcurrent disconnection device (112) electrically conductively connected to the second connection terminal (204); and d. an arc switch (114) designed to generate, in the event of an overload, a replacement arc (402), which leads to the overcurrent disconnection device (112), for a switching arc (300) arising during operation when the contact point (110) between the first contact (206, 210) and the second contact (208) is interrupted, characterized in that the overcurrent disconnection device (112) is designed as a fuse filled with sand.

2. Switch (102) according to Claim 1, wherein the arc switch (114) comprises the first contact (206), a movable switching bridge (210) electrically conductively connecting the first contact (206) to the second contact (208) when the contact point (110) is closed, and an electrode (212) of the overcurrent disconnection device (112), wherein, when the contact point (110) is closed, the switching bridge (210) is spaced apart from the electrode (212) and is designed, when the contact point (110) is interrupted, to be lifted off the first contact (206) in the direction of the electrode (212) in order to generate the replacement arc (402).

3. Switch (102) according to Claim 2, wherein, when the contact point (110) is disconnected, the switching bridge (210) is spaced apart from the electrode (212) by an air gap (214), wherein a minimum energy turnover in the arc switch (114) required for igniting a replacement arc (402) is dependent on the air gap (214).

4. Switch (102) according to Claim 3, wherein, when the contact point (110) is disconnected, an arc distance (400) between the second contact (208) and the switching bridge (210) is greater than the air gap (214).

5. Switch according to any one of Claims 2 to 4, wherein the electrode (212) is overmoulded with a thermoplastic insulator (1000), wherein a minimum energy turnover in the arc switch (114) required for igniting a replacement arc (402) is dependent on a thickness of the insulator (1000).

6. Switch (102) according to Claim 1, wherein a further overcurrent disconnection device (500) is electrically conductively connected to the first interface (202), wherein the arc switch (114) comprises the first contact (206), the second contact (208), a movable switching bridge (210) electrically conductively connecting the first contact (206) to the second contact (208) when the contact point (110) is closed, an electrode (212) of the overcurrent disconnection device (112), and a further electrode (502) of the further overcurrent disconnection device (500), wherein, when the contact point (110) is closed, the switching bridge (210) is spaced apart from the electrode (212) and the further electrode (502), wherein, when the contact point (110) is disconnected, a combined arc distance (400) between the switching bridge (210) and the first contact (206) and between the switching bridge (210) and the second contact (208) is greater than both a first air gap (214) between the first contact (206) and the electrode (212) and a second air gap (504) between the second contact (208) and the further electrode (502).

7. Switch (102) according to any one of the preceding claims, wherein the arc switch (114) has at least one blowout magnet (506, 508) for extending the switching arc (300), wherein a field direction of a magnetic field generated by the blowout magnet (506, 508) is aligned transversely to a profile of the switching arc (300).

8. Switch (102) according to Claim 7, wherein the blowout magnet (506, 508) is an electromagnet (900) connected between the first interface (202) and the switching bridge (210), wherein, when the contact point (110) is disconnected, the switching bridge (210) is spaced apart from the first contact (206) and the second contact (208), wherein, when the contact point (110) is interrupted, the electromagnet (900) is energized by a flow of electric current resulting from an arc voltage at a further switching arc (300) between the switching bridge (210) and the first contact (206) in order to generate a current-direction-dependent magnetic field for extending the switching arc (300) in the direction of the overcurrent disconnection device (112).

9. Switch (102) according to any one of the preceding claims, wherein the arc switch (114) has a movable, insulating disconnection element (200), wherein the disconnection element (200) can be arranged between the first contact (206) and the second contact (208), wherein the disconnection element (200) increases an arc distance (400) between the first contact (206) or the switching bridge (210) and the second contact (208) and / or covers the first contact (206) or the switching bridge (210) and / or the second contact (208) when it is arranged in the contact point (110).

10. Switch (102) according to any one of the preceding claims, having a measuring device for detecting a flow of electric current between the first interface (202) and the second interface (204), wherein the measuring device is designed to provide a disconnection signal (904) for interrupting the contact point (110) when the flow of current is greater than a threshold value.

11. Method for interrupting a high-voltage electrical connection (108), wherein the method comprises an interruption step, a generation step and an extinguishing step, wherein, in the interruption step, a contact point (110) of an electrical switch (102) according to any one of Claims 1 to 10 arranged in the high-voltage connection (108) is disconnected in response to a disconnection signal (904), in the generation step, a replacement arc (402), which leads to a de-energized overcurrent disconnection device (112) of the switch (102) when the contact point (110) is closed, is generated for a switching arc (300) arising in the disconnected contact point (110) and, in the extinguishing step, the replacement arc (402) is extinguished by the overcurrent disconnection device (112) being tripped.

12. Vehicle (100) having at least one switch (102) according to any one of Claims 1 to 10, wherein the switch (102) is arranged in an electrical high-voltage connection (108) of a voltage supply system of the vehicle (100), wherein a contact point (110) of the switch (102) can be disconnected using an actuator (902) in response to a disconnection signal (904).

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