Current conductor arrangement for a motor vehicle for reducing exposure in the context of electromagnetic compatibility with respect to the environment

Abstract

A current conductor arrangement for a motor vehicle (10) for conducting electrical energy from a primary current distributor (14a, 14b) to a secondary current distributor (18), which is remote from the primary current distributor and to which at least one electrical load (16, 17) can be connected, is characterized in that a splitter unit (19) is arranged on the primary current distributor (14a, 14b) and the splitter unit is connected to the secondary current distributor (18) by at least two spatially separated line strands (20a, 20b, 20c) for splitting the total current, wherein for each line strand (20a, 20b, 20c) a maximum strand current (IMax1, IMax2, IMax3) at which the limit values for electromagnetic compatibility with respect to the environment (limit values for EMC with respect to the environment) are adhered to is stored, and wherein for each line strand (20a, 20b, 20c) the splitter unit (19) comprises a current-measuring device (24a, 24b, 24c) and a series resistance setting device (26a, 26b, 26c) for setting a series resistance, and the series resistance in each line strand (20a, 20b, 20c) can be set such that the relevant maximum strand current (IMax1, IMax2, IMax3) is not exceeded. As a result, the electromagnetic fields are reduced. By adapting the line resistance in each line strand, the limit values for EMC with respect to the environment can be adhered to without restricting comfort functions for passengers.

Description

[0001] Mercedes-Benz Group AG

[0002] Conductor arrangement for a motor vehicle to reduce EMC exposure

[0003] The invention relates to a conductor arrangement for a motor vehicle for conducting electrical energy from a primary power distributor to a remote secondary power distributor to which at least one electrical consumer can be connected, a method for operating such a conductor arrangement, and a motor vehicle equipped therewith.

[0004] Due to the increasing use of high-power electrical devices outside the engine compartment of motor vehicles, the electrical currents flowing through the wiring to these devices are sometimes considerable. If such electrical devices are located in the rear of the vehicle and the power source is at the front (or vice versa), and the wiring therefore has to be installed below the passenger compartment, the currents, often in the three-digit range, generate electromagnetic fields of considerable magnitude. These fields can interfere with medical devices and potentially cause malfunctions, such as those of pacemakers or insulin pumps, and may also have consequences for the health of vehicle occupants. Therefore, there are limits that must be observed for electromagnetic compatibility (EMC limits) to prevent unacceptably high exposure of vehicle occupants to electromagnetic fields.

[0005] The same applies if high-voltage power lines run between a traction battery of an electrically powered vehicle and an electric drive motor below the passenger compartment.

[0006] It is known from DE 102021 116 576 A1 to make an EMC setting and, depending on the setting, to control or switch off individual electrical consumers accordingly. To ensure EMC II, measures must therefore be taken in existing vehicle electrical system designs, which lead to high installation space costs and weight disadvantages for the vehicle, such as the installation of shielding plates on the individual cables, external routing of cables (outside the interior, which would require body shell modifications), parallel grounding, or a significant reduction in current by eliminating electrical systems, which would lead to a reduction in comfort in the vehicle.

[0007] The object of the invention is to reduce the electromagnetic loads occurring in the passenger compartment when high currents are transmitted through power supply lines.

[0008] The invention is defined by the features of the independent claims. Advantageous further developments and embodiments are the subject of the dependent claims.

[0009] The problem is solved according to a first aspect of the invention according to claim 1 in that a splitter unit is arranged on the primary power distributor, and this is connected to the secondary power distributor via at least two spatially separated conductor strands for dividing the current, wherein a maximum strand current is stored for each conductor strand at which the limits of electromagnetic compatibility with the environment (EMC limits) are complied with, wherein furthermore the splitter unit comprises a current measuring device and a series resistor adjusting device for each conductor strand for setting a series resistor and the series resistor in each conductor strand is adjustable so that the respective maximum strand current is not exceeded.

[0010] The invention therefore consists of installing at least two parallel but spaced-apart power lines in the vehicle instead of a single power line with a high current and correspondingly high electromagnetic fields. The lower currents in each line reduce the strength of the electromagnetic fields. The spacing between the lines, preferably at least 10 cm, and more preferably more than 20 cm, further reduces the effects of the electromagnetic fields. Furthermore, the splitter unit stores a value for the maximum current in each line, ensuring that this current complies with the EMC limits for that line, depending on its position in the vehicle and, in particular, its distance from passenger seats.By adjusting the line resistance in each cable run, it is also ensured for each cable run that no EMC limit value is exceeded.

[0011] The conductor arrangement according to the invention will be used in particular between a main distribution board and a secondary power distribution board, wherein the main distribution board is arranged directly at a power source, i.e., a battery or a DC / DC converter. The conductor arrangement can also be used for other power lines with high currents in the vicinity of the passenger compartment.

[0012] The measure proposed according to the invention requires only a small additional component and can therefore also be integrated into existing vehicle electrical systems by connecting the core of the splitter unit to the output of the existing main distributor. This allows compliance with EMC limits without restricting passenger comfort functions.

[0013] If the maximum current in each conductor is the same, then this also applies to the partial currents in the conductors, so that the total resistance of each conductor is then almost identical. This cannot be guaranteed solely by dimensioning the conductors based on manufacturing tolerances, conductor lengths, conductor cross-sections, material, aging, etc. Aging, in particular, is a critical parameter for conductor resistance that cannot be controlled during the service life. The splitter unit can equalize all outputs and optimally distribute the current by using variable resistors.

[0014] According to an advantageous embodiment of the invention, the conductor arrangement comprises three or four conductor strands. The number of conductor strands is selected depending on the magnitude of the current to be conducted from the primary to the secondary current distributor.

[0015] According to a beneficial further education, the primary power distribution board is a

[0016] A main power distribution unit connected to a battery or a DC / DC converter. Preferably, the splitter unit is an integral part of the main power distribution unit, resulting in a compact design. However, the splitter unit can also be a separate unit.

[0017] Preferably, the power source is a low-voltage (LV) power source with a maximum voltage of 60V, i.e., preferably a 12V power source commonly used in vehicles with internal combustion engines or a 48V power source frequently used in electric vehicles. However, the invention can equally be applied to high-voltage lines in electrically powered vehicles with voltages exceeding 300V.

[0018] According to an advantageous embodiment of the conductor arrangement, the series resistor adjustment device additionally includes a current interruption position. A phase fault current is stored in the splitter unit for each conductor strand. If the splitter unit detects an exceedance of this phase fault current in a conductor strand, the series resistor adjustment device can be switched to the current interruption position, thereby interrupting the current through the apparently defective conductor strand. The conductor arrangement can thus be used to detect a short circuit in a conductor strand and, in such a case, to disconnect that strand.

[0019] According to a second aspect of the invention, a motor vehicle is proposed comprising at least one conductor arrangement according to one of the preceding claims.

[0020] According to a third aspect of the invention, a method for operating a previously described current conductor arrangement is proposed, wherein the current in the conductor strands is continuously measured by the splitter unit and compared with the respective maximum strand currents, wherein, if the maximum strand current in a conductor strand is exceeded, the resistance value is increased by means of the series resistor adjusting device.

[0021] Further advantages, features, and details will become apparent from the following description, in which—with reference to the drawings—at least one embodiment is described in detail. Identical, similar, and / or functionally equivalent parts are identified by the same reference numerals. The drawings show:

[0022] Fig. 1: a schematic representation of a motor vehicle with a first embodiment of a conductor arrangement;

[0023] Fig. 2: a schematic representation of a motor vehicle with a second embodiment of a conductor arrangement;

[0024] Fig. 3: a splitter unit;

[0025] Fig. 4: schematic flowchart for current control in a cable harness.

[0026] Fig. 1 is a schematic representation of a motor vehicle 10a with a DC / DC converter 12 as a power source for a low-voltage network of the motor vehicle 10a to supply the installed electrical devices. A battery can be installed in the motor vehicle 10a instead of, or in addition to, the DC / DC converter 12. A primary or main power distribution unit 14 is located in the immediate vicinity of the DC / DC converter 12, to which the majority of the electrical consumers located in the front area of ​​the motor vehicle 10a are connected. In order to supply electrical energy to devices such as seat heaters 16 for the rear seats, as well as other electrical consumers 17, a further, secondary power distribution unit 18 is located in the rear area of ​​the motor vehicle 10a. The secondary power distribution unit 18 is supplied with power from the main power distribution unit 14a via electrical lines.For this purpose, a splitter unit 19 according to the invention is arranged in close proximity to the main power distributor 14a, and is connected to each other via three electrically parallel conductor strands 20a, 20b, 20c. The three conductor strands 20a, 20b, 20c are spaced apart from each other, the two outer conductor strands 20a, 20c laterally in the area of ​​the door sills, and the middle conductor strand 20b in the center of the vehicle. If present in the vehicle, this conductor strand 20b is routed through a cardan tunnel.

[0027] The configuration of Fig. 2 is functionally largely identical to that of Fig. 1, with the difference that in the motor vehicle 10b, the function of the splitter unit 19 is integrated into the main power distributor 14b, thus avoiding a high-current electrical connection between the main power distributor 14a and the splitter unit 19 as shown in Fig. 1. The operation of the splitter unit 19 is explained in more detail with reference to Fig. 3. The splitter unit 19 comprises an input 22 connected to the main power distributor 14a (Fig. 1), which is divided into three conductor strands 20a, 20b, 20c. As shown by the dashed lines, the splitter unit 19 can have further conductor strands.

[0028] Current measuring devices 24a, 24b, 24c are arranged in all conductor strings 20a, 20b, 20c. These devices measure the partial currents in the conductor strings 20a, 20b, 20c, which, in a 12V network, are in the range of 30–60A. Furthermore, series resistor adjustment devices 26a, 26b, 26c are arranged in each conductor string 20a, 20b, 20c. These devices are preferably designed as MOSFETs or as potentiometers. The series resistor adjustment devices 26a, 26b, 26c are configured to assume a variable resistance value in order to adjust the total resistance of the associated conductor string 20a, 20b, 20c and thus the current through it. The resistance value of the series resistor adjusting devices 26a, 26b, 26c is preferably in the range of 1 - 20 mOhm.

[0029] The splitter unit 19 further comprises a storage unit 28a, 28b, 28c for each conductor string 20a, 20b, 20c, in which the maximum string current l is stored. MaThe maximum current l of each line is stored as xi, IM3X2, lMax3 for each line string 20a, 20b, 20c. Ma The maximum current li, lMax2, lMax3 for each conductor 20a, 20b, 20c is set according to the physical conditions such that EMC limits are met, provided this maximum current flows through the conductor 20a, 20b, 20c. The splitter unit 19 also includes a controller 30a, 30b, 30c for the conductor 20a, 20b, 20c for controlling the series resistor adjustment devices 26a, 26b, 26c based on a comparison of the maximum current li. Ma xi , IM3X2, lMax3 with the current h , l2, 13 measured by the respective current meter 24a, 24b, 24c with the aim of adjusting the electrical resistance in the respective conductor string 20a, 20b, 20c so that the actual current h , l2, 13 equals the respective maximum string current l Ma xi , lMax2, lMax3 does not exceed.

[0030] Memory locations 28a, 28b, and 28c each contain a value for a phase fault current, which can be the same for all phases and clearly defines an impermissibly high current, for example, twice the maximum occurring current. If the respective controller 30a, 30b, or 30c determines, based on the current measurement in the respective line 20a, 20b, or 20c, that the phase fault current is exceeded, this indicates a short circuit in the line 20a, 20b, or 20c, so that the respective line 20a, 20b, or 20c is switched off via the respective series resistor control device 26a, 26b, or 26c.

[0031] Figure 4 schematically illustrates a flowchart for the control of the current h by the controller 30a, using a line 20a as an example. After start 100, in step 101 the current h in the line 20a is measured using the current measuring device 24a. In step 102, it is checked whether the current h is greater than the maximum line current l stored in the memory 28a. Ma xi ■ If this is not the case, the process returns to step 101 and the current is measured again. If, however, the current h is greater than the maximum phase current l Ma In step 103, the resistance value of the series resistor adjusting device 26a is increased using the controller 30a. Then, in step 102, it is checked again whether the current h is now below the value of the maximum phase current l. Ma xi has sunk.

[0032] The same process is carried out for the other conductor strings 20b, 20c in the same way.

[0033] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are truly only examples and are not to be understood in any way as limiting, for example, the scope of protection, the possible applications, or the configuration of the invention.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

Claims

Mercedes-Benz Group AG Patent claims 1. Conductor arrangement for a motor vehicle (10) for conducting electrical energy from a primary power distributor (14a, 14b) to a remote secondary power distributor (18) to which at least one electrical consumer (16, 17) can be connected, characterized in that a splitter unit (19) is arranged on the primary power distributor (14a, 14b), and this is connected to the secondary power distributor (18) via at least two spatially separated conductor strands (20a, 20b, 20c) for dividing the total current, wherein a maximum strand current (l) is available for each conductor strand (20a, 20b, 20c). Ma xi li iaxs) is stored, in which the limits of electromagnetic compatibility with the environment (EMC limits) are complied with, wherein the splitter unit (19) further comprises a current measuring device (24a, 24b, 24c) and a series resistor adjusting device (26a, 26b, 26c) for each conductor string (20a, 20b, 20c) for setting a series resistor and the series resistor in each conductor string (20a, 20b, 20c) is adjustable so that the respective maximum string current liviaxs) is not exceeded.

2. Conductor arrangement according to claim 1, characterized in that it comprises three or four conductor strands (20a, 20b, 20c).

3. Current conductor arrangement according to claim 1 or 2, characterized in that the primary current distributor is a main current distributor (14a) which is connected to a battery or a DC / DC converter (12) as a current source.

4. Current conductor arrangement according to claim 3, characterized in that the splitter unit (19) is an integral part of a main current distributor (14b).

5. Current conductor arrangement according to claim 3, characterized in that the current source is a low-voltage (LV) current source with a voltage of less than 60V.

6. Current conductor arrangement according to claim 3, characterized in that the current source is a high-voltage current source (LV) with a voltage of more than 300V.

7. Current conductor arrangement according to one of the preceding claims, characterized in that the series resistor adjusting device (26a, 26b, 26c) comprises a current interrupter position and in the splitter unit (19) a strand fault current (l) is provided for each conductor strand (20a, 20b, 20c). Err i_i , I ErrL2, 1 ErrLs) is stored, where if the splitter unit (19) in a line string (20a, 20b, 20c) an exceedance of the string fault current (l Erri_i , I ErrL2, 1 ErrLs) determines that the series resistor adjusting device (26a, 26b, 26c) can be switched to the current interrupting position.

8. Motor vehicle (10a, 10b) , comprising at least one conductor arrangement according to one of the preceding claims.

9. Method for operating a current conductor arrangement according to one of claims 1 to 7, characterized in that the current in the conductor strands is continuously measured by the splitter unit (19) (101) and compared with the respective maximum strand currents (l Ma xi , IM3X2, li iaxs) is compared (102), where when the maximum string current is exceeded (l Ma xi , IM3X2, liviaxs) in a conductor string (20a, 20b, 20c) by means of the series resistor adjusting device (26a, 26b, 26c) the resistance value is increased (103).

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