Protective device for voltage limiting elements of a low-voltage line leading out of a vehicle's high-voltage area

Abstract

Vehicle high-voltage device with a high-voltage area (HV) arranged in a housing (G) and with at least one low-voltage line (NL) exiting the high-voltage area through a passage (D), wherein the at least one low-voltage line comprises a communication line, a control line or a sensor line, and wherein the passage (D) is provided in an outwardly bounding housing wall (GW) of the housing (G), wherein the at least one low-voltage line (NL) is connected to a ground potential (M) or a connection thereto via a voltage limiting element (V) and a current limiting element (SG) connected thereto in series.

Description

[0001] It is known to equip vehicles with an electric drive or other electrical components. To achieve high performance, especially for traction, high voltages are used, for example, 400 volts or more, which, unlike the otherwise common 12-volt electrical systems, can pose a danger to people. Protective mechanisms exist, described, for example, in documents WO 2016 / 189135 A1, DE 10 2014 002 819 A1 and DE 102 47 308 B3, and are based on protecting a low-voltage supply signal against overload, for example by detecting arcs or other overcurrent-related phenomena to initiate appropriate measures, or by using voltage limiters such as Zener diodes.

[0002] For this reason, vehicles with a high-voltage electrical system (i.e., a high-voltage electrical system – HV system) are housed in an enclosure that physically separates the high-voltage section (HV section) from the surrounding environment. However, low-voltage lines, for example for signaling purposes, extend from the enclosure. If an insulation fault occurs within the high-voltage section, leading to a connection between a high-voltage potential of the high-voltage section and one of the low-voltage lines, there is a risk of dangerous touch voltage, especially since the insulation of the low-voltage lines (outside the high-voltage section) is not designed for the voltages of the HV system.

[0003] It is an object of the invention to demonstrate a way to safely reduce the risk of injury from an insulation fault-induced high voltage on a low-voltage line that is routed out of a high-voltage area.

[0004] This problem is solved by the vehicle high-voltage device according to claim 1. Further features, embodiments, properties and advantages will become apparent with the dependent claims as well as with the figure and the description.

[0005] A vehicle high-voltage device is described, which has a high-voltage section. The term "section" in this context has a physical meaning and can be understood as a limited volume or area. Components such as switches, especially disconnect switches or changeover switches, voltage converters, rectifiers or power converters, as well as filters or fuses, or even batteries, which have a high-voltage operating voltage or high-voltage nominal voltage, may be located here. Functionally related low-voltage components, such as control circuits, sensors, communication devices, and the like, may also be located here. These elements can be present individually, in multiples, or in any combination. The low-voltage components are also located within the high-voltage section. The prefix "high-voltage" (HV) signifies a voltage range of more than 60 V, or at least 200 V, 400 V, or 800 V.The prefix "low voltage" (LV) indicates a voltage range of less than 60 V, with a maximum of 40 V, 20 V, 14 V, 12 V, or 5 V. At least one low-voltage line exists, for example, as a low-voltage supply line, communication line, control line, or sensor line, to functionally connect components located within the high-voltage range from the outside (for control, communication, status detection, low-voltage supply, etc.).

[0006] The high-voltage section is housed in an enclosure. The enclosure is preferably closed. The interior of the enclosure preferably forms the outer boundaries of this high-voltage section. However, further high-voltage components, not yet mentioned, may be located outside the enclosure and be electrically connected to its interior. The at least one low-voltage line exits the enclosure into its exterior. For this purpose, the enclosure has a passage, for example, in the form of an opening. The at least one low-voltage line passes through this passage. This can be a continuous line passing through the passage itself, or it can be extended through the passage by a connected conductor section. Both of these scenarios are encompassed by the definition "passes through the passage." The passage is provided in an exterior wall of the enclosure.The housing wall thus forms a boundary for the physical extent of the high-voltage area. The high-voltage area is limited by the housing wall and preferably does not extend beyond it. Preferably, no high-voltage lines, but only low-voltage lines (or at least one of them) extend through the opening. However, as mentioned, in the event of an insulation fault within the housing (the high-voltage area), these lines can carry a dangerous potential from the high-voltage area into a non-high-voltage area (low-voltage area) beyond the housing wall.

[0007] To protect against high touch voltages that can occur when a low-voltage line within the high-voltage area receives a high-voltage potential (of a component or high-voltage line) due to an insulation fault, at least one voltage limiting element is provided. The high-voltage potential here refers approximately to a ground potential. The at least one voltage limiting element conducts when a voltage above a voltage limit (breakdown voltage) is applied to it, and not otherwise. The voltage limiting element begins to conduct when the voltage limit is reached.

[0008] This results in a protective device for the voltage limiting elements of a low-voltage line leading out of a vehicle's high-voltage section. The protective device is provided by the current limiting element, which is connected in series with the voltage limiting elements (or the voltage limiting element itself), thus protecting the voltage limiting elements from overcurrent.

[0009] If an insulation fault occurs, a high-voltage potential from the high-voltage (HV) section can be transferred to at least one low-voltage line, and the voltage limiting element will begin to conduct due to the voltage limit being exceeded. If the high-voltage potential of the low-voltage line is connected to a high-power high-voltage source, such as a high-voltage electrical system, a high-voltage battery, or another high-voltage source (such as a charging station), then the voltage limiting element will conduct a high current when the voltage limit is reached. To prevent this high current from destroying or damaging the voltage limiting element, rendering it incapable of providing protection against high touch voltage, a current limiting element is used.This current limiting element is connected to the voltage limiting element in such a way that it reduces or limits the magnitude, or at least the rate of increase, of the current (when the voltage limiting element begins to conduct). Limiting the magnitude of the current protects the voltage limiting element from thermal overload. This is also the case when the rate of increase of the current is limited, whereby limiting the rate of increase creates a period during which the voltage limiting element is not overloaded and during which other protective mechanisms can take effect. Thus, if, when the rate of increase is limited, a current critical for the voltage limiting element is only reached at the end of this period, other protective mechanisms (such as disconnecting a voltage source or discharge) can take effect before this end, and the voltage limiting element is protected.

[0010] The at least one low-voltage line is connected to a ground potential (or another leakage potential) or a connection point for this purpose via a voltage limiting element and a current limiting element connected in series with it. Through the series connection, the current limiting element limits the current (or its rate of rise) flowing through the voltage limiting element when the latter conducts or begins to conduct due to a voltage above the voltage limit (breakdown voltage) of the current limiting element. This protects the function of the voltage limiting element, at least until further safety measures such as disconnection or discharge take effect.

[0011] In one embodiment, several low-voltage lines are provided, exiting the housing or the high-voltage area through the opening. Each of the low-voltage lines (or at least a plurality thereof) is connected to a common current-limiting element via a voltage-limiting element. The first ends of the multiple voltage-limiting elements are connected to the individual low-voltage lines. Opposite second ends of the voltage-limiting elements are connected to one and the same common current-limiting element, which in turn connects the voltage-limiting elements to ground potential (generally: leakage potential). In other words, the low-voltage lines are connected via individual voltage-limiting elements to a common connection point, which is in turn connected to ground potential (generally: leakage potential) via a common current-limiting element.This allows one current limiting element to be used for multiple voltage limiting elements, saving costs and installation space.

[0012] Another embodiment provides that the same common voltage limiting element and the same common current limiting element are used for several low-voltage lines. This is made possible by connecting elements that link the multiple low-voltage lines to the common voltage limiting element and the common current limiting element, respectively. The connecting elements can be diodes that prevent a high-voltage potential from one low-voltage line from being transferred to another low-voltage line via the connecting elements. Therefore, if several low-voltage lines are present, each is connected via a connecting element, such as a diode, to a series circuit that leads to the ground potential (generally: leakage potential) or the connection for this purpose. The series circuit has a (common) voltage limiting element and a (common) current limiting element connected in series with it.The connecting elements can lead to the (common) voltage limiting element, which in turn is connected to ground potential via the current limiting element, or the connecting elements can lead to the (common) current limiting element, which in turn is connected to ground potential via the voltage limiting element. If a resistor or a conductor is chosen as the connecting element, the potentials of one low-voltage line are transferred to others; however, the voltage limiting element is also triggered in the event of an insulation fault. In this configuration, as in other embodiments, it is protected by the current limiting element, which limits the current or its rise (for the voltage limiting element). Embodiments are described in which the components serving as protection are provided at or within the passage.The components serving as safeguards comprise: the at least one voltage limiting element and / or the at least one current limiting element (preferably also the relevant connection points with the at least one low-voltage conductor and / or the connecting elements, if present). These components may be provided on the inside or outside of the housing wall or in a feedthrough, particularly at the point on the housing wall where the feedthrough is located. These components may be provided in a module, such as a module housing, or may be provided as an insulated module. The module may be arranged at the feedthrough (on the inside or outside of the housing wall) or within the feedthrough. In particular, the module may be directly adjacent to a cable feedthrough through which the at least one low-voltage conductor passes. The cable feedthrough extends through the feedthrough.through a through-opening that creates the passage. The following are some variations.

[0013] The at least one voltage limiting element and / or the current limiting element can be provided in a module. This module is preferably arranged on an inner side of the housing wall at the opening. Furthermore, a cable gland can be provided in the opening through which the at least one low-voltage line passes, and the at least one voltage limiting element and the current limiting element are provided in the cable gland. The at least one low-voltage line can also lead to a plug connector, which is arranged in the opening and / or on an outer side of the housing wall at the opening. The at least one voltage limiting element and / or the current limiting element can be integrated into the plug connector or can be arranged on the plug connector, preferably directly or physically adjacent to it. Physical integration of the voltage limiting element or current limiting element is not required.The integration of the voltage limiting elements and the current limiting element with the plug-in connector, to which the at least one low-voltage line leads, offers a compact implementation option. The voltage limiting element and / or the current limiting element can be arranged within a housing of the plug-in connector or directly on a housing of the plug-in connector ("plug-in connector housing"). In the latter case, preferably as a separate, enclosed or overmolded module, which is particularly adjacent to the plug-in connector housing. The plug-in connector is, for example, a signal socket or a signal plug with multiple contacts, each of which has its own low-voltage line leading to or connected with it. This plug-in connector preferably extends through the opening in the housing wall from the interior (high-voltage area) to the surrounding area of ​​the housing, where the high-voltage area is located.In other words, the connector is located inside the housing containing the high-voltage section, or on the inside of the housing wall, and is connected to the low-voltage lines. It can be electrically connected from outside this housing by inserting a complementary (low-voltage) connector, which serves, in particular, to extend the low-voltage lines to the outside of this housing. The connector housing may contain the contacts of the connector that are connected to the low-voltage lines, preferably also including the voltage and current limiting elements; preferably also the connecting elements, if present. These elements are electrically insulated from the contacts by an insulating device. The insulating device is preferably also located within the connector housing.

[0014] The current limiting element can be configured as a resistor or an inductor, or it can have both. The current limiting element can be configured as a series connection of a resistor and an inductor. If the current limiting element includes a resistor, this resistor serves to limit the current. The resistor is designed such that, at the maximum voltage or nominal voltage of the high-voltage range or components thereof, the maximum peak current of the voltage limiting element is not exceeded. The voltage limiting element can be designed with a maximum peak current of at least 500 A, 5000 A, or 8000 A. The resistance can be 0.1–10 ohms (depending on the voltage in the high-voltage range). The inductance can have a value of 1 µH or more, for example, 5 µH, 10 µH, or 20 µH.This limits the rate of current rise in the event of a sudden insulation fault or sudden touch current, ensuring that the current remains below a value that could damage the voltage limiting element for an initial period. During this period, further measures such as shutdown or discharge can be implemented.

[0015] The at least one low-voltage line can be a low-voltage supply line (for 12 V, 14 V, 24 V, or 5 V), a communication line (for a CAN bus, a LAN connection, or proprietary signal transmission), for example, to transmit signals indicating an operating state (error signal, idle signal, activation signal, etc.), a control line (for controlling a component within the high-voltage range), or a sensor line, such as for a temperature, current, voltage, magnetic field, speed, or torque sensor, or even a battery management system. These lines have in common that their voltage level does not exceed a limit, such as 60 V, 40 V, 20 V, 14 V, or 12 V, during normal operation.

[0016] The voltage limiting element can be configured as a varistor, gas discharge tube, spark gap, protection diode, thyristor circuit, TVS thyristor, DIAC, Zener diode, suppressor diode, four-layer diode, or a combination thereof. The voltage limiting element can be a single component or a bundle of identical components connected in parallel, configured as described above.

[0017] The voltage limiting element is equipped with a voltage threshold above which it conducts. This threshold preferably corresponds to the breakdown voltage. This can be at least 40 V, 60 V, 400 V, 450 V, or more than 600 V. In particular, the breakdown voltage in one embodiment is 30–35 volts. The threshold is greater than the maximum of all the maximum voltages of all the low-voltage lines that pass through (or continue through) the opening.

[0018] The high-voltage section is preferably designed for nominal voltages of at least 400 V, 600 V, or 800 V. The at least one low-voltage line can be designed for a maximum voltage of no more than 40 V, 20 V, 14 V, or 5 V under fault-free operation. This corresponds to the maximum levels during fault-free signal transmission or fault-free (low-voltage) power supply.

[0019] The current limiting element is designed to limit the current flowing through it (or the voltage limiting element) to a maximum current value. The maximum peak current rating of the voltage limiting element is greater than the maximum current rating of the current limiting element. In other words, the current limiting element is designed to limit the current or current rise in such a way that the operating range of the voltage limiting element is not exceeded. The Fig. Figure 1 serves to explain the device described here.

[0020] The Fig. Figure 1 shows a vehicle high-voltage device with a high-voltage section HV and a housing G in which the high-voltage section HV is located. The housing G physically encloses the high-voltage section HV, thus protecting it from external access. Several low-voltage lines NL extend from the high-voltage section HV and, in particular, from the housing G. These lines serve, for example, to supply low-voltage power to components within the housing or the high-voltage section, or to communicate with these components, such as for controlling them, or to transmit (low-voltage) signals from these components to the outside of the housing via a low-voltage line, for example, in the case of a sensor as one of the components.

[0021] The low-voltage lines (NL) thus serve for low-voltage signal transmission between components within the high-voltage (HV) range and a component outside the depicted high-voltage (HV) range, i.e., components in a low-voltage (NV) range. Alternatively or additionally, the low-voltage lines (NL) serve to supply low-voltage power to components within the high-voltage (HV) range. Such components within the high-voltage (HV) range are low-voltage components (sensors, control circuits, communication devices, etc.) or, more generally, components that receive and / or output a low-voltage signal or level (communication signal or low-voltage supply voltage). These can be components with a low-voltage section or can be low-voltage components in their own right.

[0022] The low-voltage lines NL are led out of the high-voltage area HV (or the housing G) through a passage D, i.e., into an area outside the high-voltage area HV or the housing G. The housing G, and in particular a housing wall GW, separates the high-voltage area HV from the area outside the high-voltage area HV or the housing G.

[0023] The passage D is provided in an outwardly bounding housing wall GW of the housing G. The passage D is designed as a through-opening.

[0024] To provide protection against a high-voltage potential that may occur in the event of an insulation fault on one of the low-voltage lines NL, the low-voltage lines are connected to a ground potential M (or another leakage potential) or to a connection for this purpose via at least one voltage limiting element V and a current limiting element SG connected in series with it.

[0025] The serial arrangement ensures that the current is limited by the voltage limiting element V, which serves for overvoltage protection, while the current limiting element SG limits the rate of increase and / or the current amplitude itself.

[0026] In the Fig.This is achieved by the four voltage limiting elements V (varistors), each of which connects the four low-voltage lines NL individually via the (common) current limiting element SG. This means that only one current limiting element is required for multiple voltage limiting elements V or low-voltage lines NL. An inductor is shown as the current limiting element. This limits the current, particularly at the beginning of an insulation fault, and thus limits the rate of current rise. By limiting the rate of current rise (current rise rate, current rise speed), the current is restricted, at least for a certain period at the beginning of the insulation fault. This period can be used to trigger further safety mechanisms. Therefore, limiting the current also includes limiting the current at the beginning of an insulation fault.Instead of the inductor shown, a resistor or a series connection of an inductor and a resistor can also be used.

[0027] Another possibility is to use multiple interconnects such as diodes instead of the several voltage limiting elements V shown, and a series connection of a current limiting element SG and a voltage limiting element V instead of the current limiting element SG shown. This allows for savings in the number of voltage limiting elements V, while the interconnects are less expensive, thus resulting in overall cost savings.

[0028] This can also be implemented in a two-terminal configuration by connecting a first group of diodes to the low-voltage lines NL, and connecting this first group of diodes to ground potential via a common current-limiting element SG and a voltage-limiting element V, with the forward bias of all diodes in the first group pointing towards ground potential. This creates the connection for one of two polarities. A second group of diodes is connected to the low-voltage lines NL, and this second group of diodes is connected to ground potential via another common current-limiting element SG and another voltage-limiting element V, with the forward bias of all diodes in the second group pointing away from ground potential. This creates the connection for one of two polarities. The common current-limiting element and the voltage-limiting element are connected in series.This also applies to the additional common current limiting element SG and the additional voltage limiting element V.

[0029] The diagram symbolically shows that the several low-voltage lines (NL) extend through the opening (D). The opening separates the high-voltage area from an area outside the housing (G), specifically from a low-voltage area (NV). Higher insulation requirements apply in the high-voltage area (HV) than in the low-voltage area (NV). Components of the low-voltage area (NV) should therefore not be exposed to the potentials or voltages of the high-voltage area, as appropriate insulation specifications apply only within the high-voltage area (HV) (particularly with regard to maximum operating voltage, permissible insulation voltage, etc.). An NV connector may be provided, either extending through the opening or connecting directly to it on the side beyond (relative to the HV area). The voltage limiting elements (V) and the current limiting element (SG) are preferably also provided there.In further embodiments, the voltage limiting element, the current limiting element, the further voltage limiting element, and the current limiting element, as well as the connecting elements, are provided there. These can be housed in a module or module housing. The voltage limiting and current limiting elements are preferably insulated according to an insulation design that is also valid for the HV range or that requires stricter measures. This serves to protect the aforementioned elements in the event of an insulation fault. The module or module housing is preferably provided directly on or in a housing of a plug-in connector device that carries the low-voltage lines NL.The endpoints of the lines NL shown on the right can be contacts of a low-voltage (LV) connector, such as a signal connector (signal socket, signal terminal), which is arranged on the housing G of the high-voltage (HV) area (in particular at the through-hole D) and which provides a connection option for the LV area. The connector is preferably insulated according to the expected operating voltages or the maximum voltage or insulation design voltage of the high-voltage (HV) area.

Claims

[1] Vehicle high-voltage device comprising a high-voltage section (HV) arranged in a housing (G) and comprising at least one low-voltage line (NL) exiting the high-voltage section through a passage (D), wherein the at least one low-voltage line comprises a communication line, a control line or a sensor line, and wherein the passage (D) is provided in an outwardly bounding housing wall (GW) of the housing (G), wherein the at least one low-voltage line (NL) is connected to a ground potential (M) or a terminal therefor via a voltage limiting element (V) and a current limiting element (SG) connected thereto in series. [2] Vehicle high-voltage device according to claim 1, wherein several low-voltage lines (NL) are provided, each of which is connected via a voltage limiting element (V) to a common current limiting element (SG) which is connected to the ground potential (M) or the connection thereto. [3] Vehicle high-voltage device according to claim 1, wherein several low-voltage lines (NL) are provided, each of which is connected via a connecting element, such as a diode, to a series circuit which leads to the ground potential (M) or the connection thereto, wherein the series circuit has a common voltage limiting element (V) and a common current limiting element (SG) connected thereto in series. [4] Vehicle high-voltage device according to one of claims 1-3, wherein - that at least one voltage limiting element (V) and current limiting element (SG) are provided in a module that is arranged on an inside of the housing wall (GW) at the passage, or - a cable gland is provided in the passage through which at least one low-voltage line is routed, and at least one voltage limiting element (V) and current limiting element (SG) is provided in the cable gland, or - which leads to at least one low-voltage line to a plug-in connector device which is located in the opening and / or on an outside of the housing wall (GW) at the opening and which has at least one voltage limiting element (V) and current limiting element (SG) integrated into the plug-in connector device or located directly on the plug-in connector device. [5] Vehicle high-voltage device according to one of the preceding claims, wherein the current limiting element (SG) provided for limiting the current or current increase by the voltage limiting element comprises a resistance and / or an inductance. [6] Vehicle high-voltage device according to one of the preceding claims, wherein the at least one low-voltage line comprises a low-voltage supply line. [7] Vehicle high-voltage device according to one of the preceding claims, wherein the voltage limiting element (V) comprises a varistor, a gas discharge tube, a spark gap, a protection diode, a thyristor circuit, a TVS thyristor, a DIAC, a Zener diode, a suppressor diode, and / or a four-layer diode. [8] Vehicle high-voltage device according to one of the preceding claims, wherein the voltage limiting element (V) is provided with a voltage threshold above which it conducts, which is at least 40 V, 60 V, 400 V, 450 V or more than 600 V. [9] Vehicle high-voltage device according to one of the preceding claims, wherein the high-voltage section is designed for nominal voltages of at least 400 V or 800 V and the at least one low-voltage line is designed for a maximum voltage of not more than 40 V, 20 V, 14 V or 5 V in fault-free operation. [10] Vehicle high-voltage device according to one of the preceding claims, wherein the current limiting element is designed to limit a current flowing through this element to a maximum current value, and wherein the maximum peak current design of the voltage limiting element (V) is greater than the maximum current value of the current limiting element.

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