Patent Application
20250074198
It is known practice to equip vehicles with an electrical drive or other electrical components. In order to achieve high powers, particularly for traction, use is made of high voltages, for example of 400 volts or more, which, in contrast to the otherwise customary 12 volt on-board electrical systems, can pose a danger to people.
For this reason, vehicles that have an on-board electrical system with high voltage (i.e. a high-voltage on-board electrical system—HV on-board electrical system), are provided in a housing, by means of which a high-voltage region (HV region) is physically separated from the environment of the housing. However, low-voltage lines lead out of the housing for signal purposes for example. If an insulation fault occurs inside the high-voltage region, which leads to a connection of a high-voltage potential of the high-voltage region to one of the low-voltage lines, then there is the danger of a dangerous contact voltage, particularly as the insulation of the low-voltage lines (outside of the high-voltage region) is not configured for the voltages of the HV on-board electrical system.
An aspect of the invention is an option which can be used safely to reduce danger due to a high voltage, which is induced by an insulation fault, on a low-voltage line that is led out of a HV region.
A vehicle high-voltage device is described, which has a high-voltage region. In this context, the term “region” has a physical meaning and can be understood as a delimited volume or delimited area. Here, components such as switches, particularly isolation switches or changeover switches, voltage converters, rectifiers or power converters and also filters or fuses or also rechargeable batteries may be provided, which have a high operating voltage or high nominal voltage. Low-voltage components functionally associated with these components may also be provided there, such as drive circuits, sensors, communication devices, and the like. These elements may be present individually, multiple times or in any desired combination. The low-voltage components are likewise located in the high-voltage region. The prefix “high-voltage” (HV) means a high-voltage range of more than 60 V, of at least 200 V, 400 V or 800 V. The prefix “low-voltage” (LV) means a voltage range of less than 60 V, of a maximum of 40 V, 20 V, 14 V, 12 V or 5 V. There is at least one low-voltage line, for example as low-voltage supply line, communication line, control line or sensor line, to functionally connect components, which are located inside the high-voltage region, from outside (for activation, communication, detecting state, low-voltage supply, etc.).
The high-voltage region is arranged in a housing. The housing is preferably closed. The interior of the housing preferably forms the external boundaries of this high-voltage region. However, further HV components may also be present outside the housing, which have not hitherto been mentioned and which are electrically connected to the interior of the housing. The at least one low-voltage line passes out of the housing into the external region of the housing. To this end, the housing has an outlet in the shape of an opening for example. The at least one low-voltage line passes through the outlet. Here, a continuous line passes itself through the outlet or is extended through the outlet by a connected conductor section. The definition “passes through the outlet” should include both of these cases. The outlet is provided in an outwardly delimiting housing wall of the housing. The housing wall therefore forms a boundary for the physical extent of the high-voltage region. The high-voltage region is delimited by the housing wall and preferably does not extend beyond the housing wall. Preferably, no high-voltage lines, rather only low-voltage lines (or at least one of these) extend through the outlet. However, as mentioned, in the event of an insulation fault inside the housing (of the high-voltage region), the low-voltage lines can carry a dangerous potential of the high-voltage region to a (non-high-voltage region, low-voltage region) beyond the housing wall.
At least one voltage-limiting element is provided for protection from high contact voltages that may occur if the low-voltage line inside the high-voltage region gains a high-voltage potential (of a component or high-voltage line) of the high-voltage region due to an insulation fault. The high-voltage potential here relates to a ground potential. The at least one voltage-limiting element conducts if a voltage above a voltage limit (breakdown voltage) is applied at the voltage-limiting element, and otherwise does not. If the voltage limit is reached, the voltage-limiting element begins to conduct.
The result is therefore a protective device for voltage-limiting elements of a low-voltage line that is led out of a vehicle high-voltage region. The protective device is provided by the current-limiting element that is connected in series to the voltage-limiting elements (or the voltage-limiting element), as a result of which the current-limiting element protects the voltage-limiting elements from excess current.
If there is an insulation fault, then a high-voltage potential from the HV region can be transmitted to the at least one low-voltage line and the voltage-limiting element begins to conduct due to the voltage limit being exceeded. If the high-voltage potential of the low-voltage line is connected to a powerful high-voltage source, such as a high-voltage on-board electrical system, a high-voltage rechargeable battery or a different high-voltage source (such as a charging station), then the voltage-limiting element carries a high current intensity when the voltage limit is reached. A current-limiting element is used to prevent this high current intensity from destroying or damaging the voltage-limiting element so it can no longer realize the protection from high contact voltage. This current-limiting element is connected to the voltage-limiting element in such a manner that it reduces or limits the level or at least the rate of increase of the current intensity (when the voltage-limiting element begins to conduct). The voltage-limiting element is protected from thermal overload by the limiting of the level of the current intensity. This is also the case for the limiting of the rate of increase of the current intensity, wherein the limitation of the increase creates a time period in which the voltage-limiting element is not overloaded and during which other protective mechanisms can take effect. Therefore, when limiting the rate of increase, if a current intensity that is critical for the voltage-limiting element is only reached at the end of the time period, then other protective mechanisms (such as disconnecting a voltage source or discharge) can take effect already before this end and the voltage-limiting element is protected.
The at least one low-voltage line is connected via a voltage-limiting element and a current-limiting element, which is connected in series thereto, to a ground potential (or a different discharge potential) or a connection for the same. Due to the series connection, the current-limiting element limits the current (or the rate of increase thereof) that flows through the voltage-limiting element if the same 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.
In one embodiment, a plurality of low-voltage lines are provided, which pass through the outlet out of the housing or the high-voltage region. Each of the low-voltage lines (or at least a majority thereof) is in each case connected via a voltage-limiting element to a common current-limiting element. First ends of the plurality of 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 the ground potential (in general: discharge potential). In other words, the low-voltage lines are connected via individual voltage-limiting elements to a common connecting point, which is in turn connected via a common current-limiting element to the ground potential (in general: discharge potential). This means that a current-limiting element can be used for a plurality of voltage-limiting elements, as a result of which costs and installation space can be saved.
A further embodiment provides that the same, common voltage-limiting element and the same, common current-limiting element are used for a plurality of low-voltage lines. This is enabled by connecting elements that connect the plurality of low-voltage lines to the common voltage-limiting element or the common current-limiting element. The connecting elements may be diodes that prevent a high-voltage potential of a low-voltage line from being transmitted to a different low-voltage line by means of the connecting elements. Therefore, if a plurality of low-voltage lines are present, then these are in each case connected via a connecting element, such as a diode, to a series circuit that leads to the ground potential (in general: discharge potential) or the connection for the same. The series circuit has a (common) voltage-limiting element and a (common) current-limiting element that is connected in series thereto. Here, the connecting elements can lead to the (common) voltage-limiting element that is in turn connected via the current-limiting element to the ground potential or the connecting elements lead to the (common) current-limiting element that is in turn connected via the voltage-limiting element to the ground potential. If a resistor or a line is chosen as connecting element, then the potentials of a low-voltage line are transferred to others, but the voltage-limiting element is similarly triggered in the event of an insulation fault. This is also protected in this configuration, as in other embodiments, by the current-limiting element, which limits the current intensity or the increase thereof (for the voltage-limiting element).
Embodiments are described, in which the components used for protection are provided on or in the outlet. The components used for protection comprise: the at least one voltage-limiting element and/or the at least one current-limiting element (preferably also the relevant connecting points to the at least one low-voltage line and/or the connecting elements, if present). These components may be provided on the inner side or outer side or in a bushing of the housing wall, particularly at the point on the housing wall at which the outlet is located. These components can be provided in a module, for example in a module housing or can be provided as an insulator-encapsulated module. The module can be arranged at the outlet (on the inner side or outer side of the housing wall) or in the outlet. In particular, the module may directly physically adjoin a cable leadthrough, through which the at least one low-voltage line is led. The cable leadthrough extends through the outlet or through a passage opening, which realizes the outlet. Corresponding variants are presented in the following.
The at least one voltage-limiting element and/or the current-limiting element may be provided in a module. This is preferably arranged on an inner side of the housing wall at the outlet. Furthermore, a cable leadthrough may be provided in the outlet, through which the at least one low-voltage line is led, and the at least one voltage-limiting element and the current-limiting element are provided in the cable leadthrough. Furthermore, the at least one low-voltage line may lead to a plug-in connection device that is arranged in the outlet and/or on an outer side of the housing wall at the outlet. The at least one voltage-limiting element and/or the current-limiting element can be integrated in the plug-in connection device or can be arranged on the plug-in connection device, preferably directly or physically adjacent. A physical integration of the voltage-limiting element or the voltage-limiting elements and the current-limiting element with the plug-in connection device to which the at least one low-voltage line leads is one option for compact realization. Here, the voltage-limiting element and/or the current-limiting element can be arranged in a housing of the plug-in connection device or directly on a housing of the plug-in connection device (“plug-in connection housing”). In the latter case, preferably as a separate housed or encapsulated module, which directly adjoins the plug-in connection housing in particular. The plug-in connection device is for example a signal jack or a signal plug with a plurality of contacts, to which in each case one separate low-voltage line leads or is connected to the same. This plug-in connection device preferably leads through the outlet of the housing wall from the interior (high-voltage region) into the environment of the housing, in which the high-voltage region is located. In other words, the plug-in connection device is located in the interior of the housing in which the high-voltage region is located or is connected to the low-voltage lines on the inner side of the housing wall and can be electrically contacted from outside this housing by plugging in a complementary (low-voltage) plug-in device, which is used in particular for continuing the low-voltage lines in the external region of this housing. The contacts of the plug-in device can be located in the plug-in connection housing, which contacts are connected to the low-voltage lines, where the voltage- and current-limiting elements—preferably also the connecting elements, if present—are also preferably located. These elements are electrically insulated from the contacts by an insulating device. The insulating device is likewise preferably located in the plug-in connection housing.
The current-limiting element can be formed as a resistor or as an inductor or have a resistance and/or an inductance. The current-limiting element can be provided as a series circuit of a resistor and an inductor. If the current-limiting element comprises a resistor, then this resistor is used to limit the current. The resistor is configured in such a way that in the case of a maximum voltage or nominal voltage of the high-voltage region 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 or of at least 5000 A or 8000 A. The resistance may be 0.1-10 ohms (depending on the voltage in the high-voltage region). The inductance may have a value of 1 μH or more, for example 5 μH or 10 μH or 20 μH. As a result, the rate of increase in current is limited in the event of a sudden insulation fault or a contact current that begins suddenly, so that over an initial time window, the current remains below a value that could be damaging for the voltage-limiting element. Further measures such as shutdown or discharge can be implemented in this time window.
The at least one low-voltage line may be a low-voltage supply line (for 12 V, 14 V, 24 V, 5 V), may be a communication line (for a CAN bus, for a LAN connection or for a proprietary signal transmission), for example for transmitting signals that characterize an operating state (error signal, idle signal, activation signal, etc.), may be a control line (for activating a component inside the high-voltage region) or may be a sensor line, for example of a temperature, current, voltage, magnetic-field, speed or torque sensor, or else of a battery management system. It is common to these lines that the level thereof during fault-free operation does not exceed a limit such as for example 60 V, 40 V, 20 V or 14 V or 12 V.
The voltage-limiting element can be formed as a varistor, gas discharge tube, spark gap, protective diode, thyristor circuit, TVS thyristor, DIAC, Zener diode, suppressor diode, four-layer diode or combination thereof. The voltage-limiting element can be provided as an individual element or as a bundle of parallel-connected identical individual elements which can be designed as explained previously.
The voltage-limiting element is set up with a voltage threshold from which the voltage-limiting element conducts. This threshold preferably corresponds to the breakdown voltage. This may be at least 40 V, 60 V, 400 V, 450 V or more than 600 V. In one embodiment in particular, the breakdown voltage is 30-35 volts. The threshold is greater than the maximum of all maximum voltages of all low-voltage lines which pass through the outlet (or are continued through the outlet).
The high-voltage region is preferably configured for nominal voltages of at least 400 V or 600 V or 800 V. The at least one low-voltage line can be configured for a maximum voltage of not more than 40 V, 20 V, 14 V or 5 V in fault-free operation. This corresponds to the maximum levels during fault-free signal transmission or during fault-free (low) voltage supply.
The current-limiting element is configured to limit a current flowing through the current-limiting element (or the voltage-limiting element) to a maximum current value. The maximum peak current configuration of the voltage-limiting element is greater than the maximum current value of the current-limiting element. In other words, the current-limiting element is configured to limit the current or the increase in current in such a way that the operating range of the voltage-limiting element is not exceeded.
The FIGURE is used to explain the device described here.
The FIGURE shows a vehicle high-voltage device having a high-voltage region HV and a housing G in which the high-voltage region HV is arranged. The housing G encloses the high-voltage region HV in a physical manner, as a result of which the high-voltage region is protected from access from outside. There is a plurality of low-voltage lines NL that pass out of the high-voltage region HV and in particular out of the housing G. These low-voltage lines are used for example for the low-voltage supply of components inside the housing or the high-voltage region or else for communication with these components, for example for the activation thereof, or to transmit (low-voltage) signals from these components to the exterior of the housing by means of a low-voltage line, for example in the case of a sensor as one of the components.
The low voltage lines NL are therefore used for low-voltage signal transmission between components inside the high-voltage region HV and a component outside the illustrated high-voltage region HV, i.e. components in a low-voltage region NV. Alternatively or additionally, the low-voltage lines NL are used for low-voltage supply of components inside the high-voltage region. Components of this type inside the high-voltage region HV are low-voltage components (sensors, drive circuits, communication devices, etc.) or in general components, which receive and/or emit a low-voltage signal or level (communication signal or low supply voltage). These may be components with a low-voltage section or may be low-voltage components.
The low-voltage lines NL are led out of the high-voltage region HV (or the housing G) through an outlet D, i.e. into a region outside of the high-voltage region HV or the housing G. The housing G and in particular a housing wall GW separates the high-voltage region HV from the region outside of the high-voltage region HV or the housing G.
The outlet D is provided in an outwardly delimiting housing wall GW of the housing G. The outlet D is formed as a passage opening.
In order to constitute protection from 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 via at least one voltage-limiting element V and a current-limiting element SG, which is connected in series thereto, to a ground potential M (or a different discharge potential) or to a connection for the same.
The series arrangement ensures that the current is limited by the voltage-limiting element V that is used for overvoltage protection, wherein the current-limiting element SG limits the rate of increase and/or the current amplitude itself.
In the FIGURE, this is realized by the four voltage-limiting elements V (varistors), which connect each of the four low-voltage lines NL individually via the (common) current-limiting element SG. As a result, only one current-limiting element is necessary for a plurality of voltage-limiting elements V or low-voltage lines NL. An inductor is illustrated as current-limiting element. The inductor limits the current particularly at the beginning of a corresponding insulation fault and therefore limits the rate of increase in current. Due to limitation of the increase in current (rate of increase in current), the current is limited at least for a time window at the start of the occurrence of the insulation fault. This time window can be used for triggering further safety mechanisms. Limitation of the current is therefore also to be understood to mean the limitation of a current at the start of the occurrence of an insulation fault. Instead of the illustrated inductor, a resistor or a series circuit of an inductor and a resistor can be used.
One further option is to use a plurality of connecting elements such as diodes instead of the plurality of voltage-limiting elements V illustrated, wherein instead of the current-limiting element SG illustrated, a series circuit of a current-limiting element SG and a voltage-limiting element V is used. As a result, voltage-limiting elements V can be saved, wherein the connecting elements are less expensive and therefore costs can be saved overall.
This can also be realized in a two-pole manner, in that a first group of diodes is connected to the low-voltage lines NL and this first group of diodes is connected via a common current-limiting element SG and a voltage-limiting element V to the ground potential, wherein the forward direction of all diodes of the first group points to the ground potential. As a result, the discharge is created 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 via a further common current-limiting element SG and a further voltage-limiting element V to the ground potential, wherein the forward direction of all diodes of the second group points away from the ground potential. As a result, the discharge is created for one of two polarities. The common current-limiting element and the voltage-limiting element are connected in series. This also applies for the further common current-limiting element SG and the further voltage-limiting element V.
It is illustrated symbolically that the plurality of low-voltage lines NL extend through the outlet D. The outlet separates the high-voltage region from a region outside of the housing G, particularly from a low-voltage region NV. More exacting insulation specifications apply in the high-voltage region HV than in the low-voltage region NV. Components of the low-voltage region NV should not therefore be loaded with the potentials or voltages of the high-voltage region, as appropriate insulation ratings apply only inside the high-voltage region HV (particularly with regard to max. operating voltage, permissible insulation voltage, etc.). An LV plug may be provided, which extends through the passage or which connects directly to the passage on the other side of the passage (with respect to the region HV). 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 and also the connecting elements are provided there. These may be accommodated in a module or module housing. The voltage-limiting and current-limiting elements are preferably insulated in accordance with an insulation rating that also applies for the HV region or that demands stricter measures than the same. This is used for protecting the elements mentioned 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 connection device, which contains the low-voltage lines NL. The end points of the lines NL, which are illustrated on the right, may be contacts of an LV plug-in connection device, for example a signal plug-in device (signal jack, signal connector), which is arranged on the housing G of the HV region (particularly at the passage D) and which offers a connection option for the LV region. The plug-in connection device is preferably insulated in accordance with the expected operating voltages or the maximum voltage or insulation rated voltage of the high-voltage region HV.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 203 889.1 | Apr 2021 | DE | national |
This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2022/058093, filed Mar. 28, 2022, which claims priority to German Patent Application No. 10 2021 203 889.1, filed Apr. 19, 2021, the contents of such applications being incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/058093 | 3/28/2022 | WO |
