Disconnecting device for safely interrupting an electrical conductor and current conduction device

Abstract

The invention relates to a disconnecting device for safely interrupting an electrical conductor, the disconnecting device (200) comprising a disconnecting switch (230) with a disconnecting switch input contact (231) and a disconnecting switch output contact (232), which establishes or breaks an electrical connection between the disconnecting switch input contact (231) and the disconnecting switch output contact (232) according to a control signal (1), a triggerable safety element (240) which is connected in series with the disconnecting switch input contact (231) or the disconnecting switch output contact (232), and a logic unit (250) which is configured to determine a conductivity of the disconnecting switch (230) between the disconnecting switch input contact (231) and the disconnecting switch output contact (232) and to trigger the triggerable safety element (240) depending on the determined conductivity and the control signal (1).The invention also relates to a current-conducting device, in particular a charging cable or a charging station for an electric vehicle, comprising the disconnecting device (200).

Description

The present invention relates to a disconnecting device for safely interrupting an electrical conductor and a current-carrying device with such a disconnecting device. Background of the invention To ensure certain safety objectives, a reliable interruption of current or voltage may be desirable, particularly in connection with electrotechnical devices. Electromechanical disconnect switches (e.g., contactors or relays) can be used to interrupt voltages or currents. Increased safety through redundancy can be achieved by using two such electromechanical disconnect switches in series. However, such a solution is heavy, expensive, and requires considerable installation space. Disclosure of the invention According to the invention, a disconnecting device for safely interrupting an electrical conductor and a current-carrying device with such a disconnecting device, comprising the features of the independent claims, are proposed. Advantageous embodiments are the subject of the dependent claims and the following description. The disconnecting device includes a disconnect switch with a disconnect switch input contact and a disconnect switch output contact. The disconnect switch is configured to establish or break an electrical connection between the disconnect switch input contact and the disconnect switch output contact according to a control signal. In other words, the disconnect switch can be opened or closed according to the control signal, with no electrical connection between the disconnect switch input contact and the disconnect switch output contact in the open state and an electrical connection between the disconnect switch input contact and the disconnect switch output contact in the closed state. It should be noted that the terms “input contact”, “output contact”, etc., within the scope of this disclosure are to be understood merely as distinguishable terms for “contact” or “connection” and do not define any current direction or the like. In embodiments of the invention, the disconnect switch can be designed as an electromechanical disconnect switch (so-called contactor, relay) or a semiconductor disconnect switch (e.g., MOSFET, IGBT). This allows for the provision of a robust and reliable disconnect device for the safe interruption of an electrical conductor. However, malfunctions can occur during the operation of a disconnect switch, causing it to remain closed even though it should be open according to the control signal. For example, a switching contact of an electromechanical disconnect switch can weld or stick together due to wear, aging, and / or damage, or a semiconductor disconnect switch can fail, etc. This can pose a significant safety risk. Therefore, the disconnecting device also features a releasable safety element connected in series with either the disconnect switch input contact or the disconnect switch output contact. For clarity, it should be emphasized that the disconnect switch and the safety element are distinct components. Each can be designed for through-hole (THT) or surface-mount (SMD) mounting on a printed circuit board. This releasable safety element allows the disconnecting device to be electrically interrupted or deactivated, even if the disconnect switch cannot be opened due to malfunctions. To trigger the trippable safety element, the disconnecting device includes a logic unit configured to determine the conductivity of the disconnect switch between the disconnect switch input contact and the disconnect switch output contact. Depending on this determined conductivity and the control signal, the logic unit triggers the trippable safety element. The logic unit can be an integrated circuit, such as an ASIC or microcontroller, and / or a discrete circuit, e.g., operational amplifiers, etc. The invention thus advantageously proposes the use of a remotely or externally triggerable safety element as a second disconnecting element in combination with a disconnect switch to implement a safe disconnecting device. This allows for a reduction in the cost, installation space, and weight of the disconnecting device, particularly compared to two electromechanical disconnect switches. According to at least one embodiment, the logic unit is configured to trigger the trippable safety element when it is determined that the disconnect switch is conductive and the control signal indicates that the disconnect switch should not be conductive. This ensures that the disconnect device can be safely opened in the event of a fault. According to at least one embodiment, the releasable safety element is designed as a releasable fuse, which has a fuse element input contact and a fuse element output contact connected by a fusible link, and a heating element configured to thermally interrupt the fusible link when activated. By using a fuse element, an overcurrent protection can also be provided, which, for example, eliminates the need for another overcurrent protection device already present in the system. According to at least one embodiment, the heating element has a heating element input contact and a heating element output contact, wherein the heating element input contact is connectable to the fuse element input contact and / or the fuse element output contact, and wherein the heating element output contact is connectable to an electrical potential that differs from an electrical potential at the heating element input contact or the heating element output contact. For example, one of the potentials at the heating element input contact or the heating element output contact can be the potential that is intended to interrupt the disconnecting device, and the other can be ground. In particular, the heating element is designed, when connected to the aforementioned potentials, i.e., when a suitable voltage is applied, to generate a temperature that melts the fusible link of the fuse. Another aspect of the invention relates to a current-carrying device, in particular a charging cable or a charging station for an electric vehicle, comprising a disconnecting device according to this disclosure. Especially in current-carrying devices that are regularly used by people, the disconnecting device offers particular advantages with regard to functional safety. It also enables compliance with standards and regulations that require a redundant disconnecting device. Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing. The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing. Brief description of the drawings Fig. 1 shows a charging cable according to embodiments of the invention in a schematic overview view. Fig. 2 shows a disconnecting device according to embodiments of the invention in a roughly schematic circuit diagram view. embodiment(s) of the invention Fig. 1 shows a schematic representation of a charging cable 100, which can preferably be used as a current conducting device 101 within the scope of the invention. The charging cable 100 has a first connector 110, a connecting cable 130, and a second connector 120. Such a charging cable 100 is used to connect, for example, a charging station, such as a charging column or wallbox, to a vehicle. The connectors 110 and 120 can be, in particular, CCS or Type 2 connectors. One or both connectors 110 and 120 can also be equipped with adapters 1 for different connector systems, such as Schuko® plugs, etc. The connecting cable 130 can, for example, have two electrical conductors (one phase conductor P and one neutral conductor N) for a single-phase alternating current, but can also have more than two electrical conductors, in particular four (three phase conductors L1, L2, L3 and the neutral conductor N) for a three-phase alternating current. Furthermore, the charging cable can have a protective conductor PE, and can, for example, also have at least one communication line, such as a so-called CP line, PP line, etc. The charging cable 100 has one or more disconnect devices 200, which have a closed and an open position. In the open position, at least the phase conductor(s) (e.g., P, L1, L2, L3) are interrupted, but preferably also the neutral conductor (N). In the closed position, all electrical conductors are continuous or uninterrupted. Accordingly, the charging cable can have at least one disconnect device 200 and, in particular, up to four disconnect devices 200. In Fig. 2 a separating device, such as can be used within the scope of the invention, is shown in a roughly schematic manner and is generally labelled 200. The disconnecting device 200 has a disconnecting device input contact 210 and a disconnecting device output contact 220, which are connected to the electrical conductor to be interrupted. As explained above, the terms "input contact", "output contact", etc. are to be understood merely as distinguishable terms for "connection" and do not define current direction or anything similar. The disconnecting device 200 has a disconnecting switch 230 with a disconnecting switch input contact 231 and a disconnecting switch output contact 232, which establishes or breaks an electrical connection between the disconnecting switch input contact 231 and the disconnecting switch output contact 232 according to a control signal 1. In the embodiment shown, the disconnect switch 230 has an electromechanical disconnect switch 233 (so-called contactor or relay) to ensure the safest possible interruption. To provide redundancy for the interruption, the disconnecting device 200 also has a triggerable safety element 240 which is connected in series with the disconnect switch input contact 231. In the illustrated embodiment, the releasable safety element 240 comprises a releasable fuse 241, which has a fuse element input contact 242 and a fuse element output contact 243 connected by a fusible link 244, and a heating element 245 configured to thermally interrupt the fusible link 244 when activated. This creates particularly reliable redundancy because the fusible link 244 has no mechanical or electronic components that could themselves be faulty and is also structurally different from the disconnect switch 230. Furthermore, this also provides overcurrent protection through the disconnect device 200, meaning that a separate overcurrent protection for each electrical conductor in the charging cable 100 is unnecessary. Furthermore, the disconnecting device 200 has a logic unit 250 which is configured to determine a conductivity of the disconnecting switch 230 between the disconnecting switch input contact 231 and the disconnecting switch output contact 232 and, depending on the determined conductivity and the control signal 1, to trigger the triggerable safety element 240. In particular, the logic unit 250 can determine conductivity by measuring the current flow through the logic unit 250 from a logic unit input contact 251 to a logic unit output contact 252. If a current flow is measurable, the disconnect switch is conductive. The logic unit can comprise an integrated circuit S, such as an ASIC or microcontroller, and / or discrete circuits, e.g., operational amplifiers, etc. The logic unit 250 is configured to trigger the triggerable safety element 240 when it is determined that the disconnect switch 230 is conductive and the control signal 1 indicates that the disconnect switch 230 should not be conductive. The heating element 245 has two heating element input contacts 246 and one heating element output contact 247, with one of the heating element input contacts 246 being connected to the fuse element input contact 242 and the other heating element input contact 246 being connected to the fuse element output contact 243. The heating element output contact 247 can be connected by the logic unit 250 to an electrical potential 253, for example ground, which differs from an electrical potential at the heating element input contact 246, for example 230 V. To trigger the triggerable safety element 240, the logic unit 250 connects the heating element output contact 247 to the electrical potential 253, so that a current flows through the heating element 245, which heats it up so that the fusible link 244 melts and the conductivity of the disconnecting device 200 between the disconnecting device input contact 210 and the disconnecting device output contact 220 is interrupted.

Claims

Disconnecting device (200) for safely interrupting an electrical conductor, the disconnecting device (200) comprising: -- a disconnecting switch (230) with a disconnecting switch input contact (231) and a disconnecting switch output contact (232), which establishes or breaks an electrical connection between the disconnecting switch input contact (231) and the disconnecting switch output contact (232) according to a control signal (1), -- a trippable safety element (240) which is connected in series with the disconnecting switch input contact (231) or the disconnecting switch output contact (232), -- a logic unit (250) which is configured to determine a conductivity of the disconnecting switch (230) between the disconnecting switch input contact (231) and the disconnecting switch output contact (232) and, depending on the determined conductivity and the control signal (1), the trippable safety element (240) to trigger. Disconnecting device (200) according to claim 1, wherein the logic unit (250) is configured to trigger the triggerable safety element (240) when it is determined that the disconnect switch (230) is conductive and the control signal (1) indicates that the disconnect switch (230) should not be conductive. Disconnecting device (200) according to claim 1 or 2, wherein the releasable safety element (240) comprises a releasable fuse (241) having a fuse element input contact (242) and a fuse element output contact (243) connected by a fusible conductor (244), and a heating element (245) configured to thermally interrupt the fusible conductor (244) when actuated. Disconnecting device (200) according to claim 3, wherein the heating element (245) has a heating element input contact (246) and a heating element output contact (247), wherein the heating element input contact (246) is connectable to the fuse element input contact (242) and / or the fuse element output contact (243), and wherein the heating element output contact (247) is connectable to an electrical potential that differs from an electrical potential at the heating element input contact. Disconnecting device (200) according to one of the preceding claims, wherein the disconnecting switch (230) comprises an electromechanical disconnecting switch (233) or a semiconductor disconnecting switch. Current conduction device (101), in particular charging cable (100) or charging station for an electric vehicle, comprising a disconnecting device (200) according to one of the preceding claims.

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