Traction arrangement for a vehicle, and method for configuring a traction arrangement for a vehicle

Abstract

The invention relates to a traction arrangement (1) for a vehicle (50), the traction arrangement comprising: a first power electronics component (2); at least one second power electronics component (3); and an unshielded traction conductor (4) which comprises two electrical conductors (4-1, 4-2) and forms an electrical connection to the first power electronics component (2) and to the at least one second power electronics component (3), wherein a distance (d) of the electrical conductors (4-1, 4-2) along the traction conductor (4) is selected such that an inductance of the traction conductor (4) has a predefined value. The invention also relates to a method for configuring a traction arrangement (1) for a vehicle (50).

Description

[0001] Description

[0002] Traction arrangement for a vehicle and method for configuring a traction arrangement for a vehicle

[0003] The invention relates to a traction arrangement for a vehicle and a method for configuring a traction arrangement for a vehicle.

[0004] Electric vehicles use traction cables to distribute electrical energy between power electronic components, for example, from a high-voltage battery to pulse-controlled inverters and drive motors (electric machines). Large magnetic fields can occur in the vicinity of these traction cables, caused by the currents flowing through the traction cables. In the case of alternating current components, the magnetic fields can lead to unwanted excitation of vehicle parts, which can cause disturbing noises. Vibrations can also cause other negative effects, such as accelerated aging and accelerated wear on components and / or joints.

[0005] The invention is based on the object of providing a solution to the aforementioned problem.

[0006] The object is achieved according to the invention by a traction arrangement having the features of patent claim 1 and a method having the features of patent claim 8. Advantageous embodiments of the invention emerge from the subclaims.

[0007] In particular, a traction arrangement for a vehicle is provided, comprising a first power electronic component, at least one second power electronic component and an unshielded traction line, which comprises two electrical conductors and forms an electrical connection to the first power electronic component and to the at least one second power electronic component, wherein a distance of the electrical conductors along the traction line is selected such that an inductance of the traction line has a predetermined value.Furthermore, in particular, a method is provided for configuring a traction arrangement for a vehicle, wherein the traction arrangement comprises a first power electronic component, at least one second power electronic component and an unshielded traction line which comprises two electrical conductors and forms an electrical connection to the first power electronic component and to the at least one second power electronic component, comprising: determining a predetermined value for an inductance of the traction line, adjusting a distance of the electrical conductors along the traction line so that the predetermined value for the inductance is present.

[0008] The traction arrangement and the method make it possible to reduce or even completely prevent unwanted excitations of vehicle parts caused by an unshielded traction line. This is achieved by setting the inductance of the traction line to a predetermined value. For this purpose, a distance between electrical conductors of the traction line is selected or adjusted accordingly. By adjusting the distance between the electrical conductors, the inductance of the traction line can be changed and thus set to the predetermined value. The predetermined value is determined and / or selected in particular such that disruptive excitations are reduced or prevented at least within a predetermined operating range of the traction arrangement.

[0009] A power electronic component is, in particular, a drive converter, in particular a pulse-controlled inverter, or an electric drive motor. The traction arrangement can be a traction arrangement in a vehicle with front-wheel drive and rear-wheel drive. The traction line serves, in particular, to electrically connect the power electronic component(s) to one another and / or to a high-voltage battery of the vehicle. The power electronic arrangement can also include the high-voltage battery. In principle, the power electronic component can also be an electric air conditioning compressor. Furthermore, traction lines can, in particular, also include secondary lines that are electrically connected to the traction line, for example, to form a connection to an electric air conditioning compressor.

[0010] The excitation by the currents flowing through the traction line is explained in more detail below using an example to illustrate this: Each electric drive motor is powered, in particular, by a drive converter (e.g., a pulse-controlled inverter, PWR) with its own storage capacitance, also known as an intermediate circuit capacitance. This capacitance, together with the intermediate circuit capacitance of the other drive converter(s) and the electrical conductors of the traction line between the drive converters, forms an oscillating circuit. The oscillation of this oscillating circuit can be described as follows: with: : DC link capacitance PWR 1

[0011] C2: DC link capacitance PWR 2

[0012] L : Inductance of the traction line between PWR 1 and PWR 2 f res : Resonance frequency

[0013] In an unshielded traction cable, the (line) inductance is higher than in a shielded traction cable. Thus, resonances are more pronounced. Furthermore, unshielded cables have lower losses (ohmic component, R) than shielded cables. This increases the quality factor of the resonant circuit and increases the resonance peak.

[0014] The ohmic resistance R of the entire resonant circuit is simplified here as the ohmic resistance of the traction line.

[0015] If the clock frequency (particularly taking into account sidebands and / or the effect of the rotating field frequency) of at least one of the drive converters is selected so that it lies in the range of the resonance frequency, very high reactive currents (4^) of up to several 10 A or several 100 A are formed. These currents can be considered as excitation of the oscillatory traction arrangement, taking into account the current spectrum of the power electronic component fp WR and a current amplification factor a specific to the traction arrangement; as follows:

[0016] Lblind i ' LPWR

[0017] As described above, these reactive currents generate large magnetic fields along the traction line and lead to additional losses (electrical heat, conduction) as well as to stress and / or heating of the intermediate circuit capacitances. Furthermore, fluctuations in the vehicle electrical system voltage result, which can be detrimental to the function of the high-voltage components and can lead to a reduction in the torque available from the drive.

[0018] By a suitable selection of the inductance L of the traction line and its adaptation within the traction arrangement by (in particular section-wise) changing a distance between the electrical conductors of the traction line, the excitation by reactive currents can be reduced or prevented at least in a given operating range (in particular a given frequency range of the drive converters).

[0019] The drive inverters of an electric drive machine typically operate in the range of a few kHz. Modulation methods based on pulse-width modulation are used here. The alternating current (sinusoidal) required by the drive machine is provided via a modulation method with a carrier or clock frequency. The drive inverter current spectrum results in particular from multiples of the clock frequency, multiples of the electrical frequency of the drive machine (electric machine), and combinations of multiples of these two elementary system frequencies. This spectrum becomes broader with increasing speed. In addition, the spectral density ratios between the multiples of the clock frequency also change depending on the speed.

[0020] Above a certain speed, the clock frequency can be selected to be equivalent to the rotating field frequency (block clocking). The spectrum of this operating mode essentially corresponds to a rectangular spectrum of the rotating field frequency.

[0021] When designing a high-voltage system, it is advisable to minimize reactive currents and thus the load on the DC link capacitors, as well as the resulting magnetic fields. This can be achieved by selecting the drive inverter's clock frequency so that it lies within the range of minimum current gain, but in any case outside the resonant frequency.

[0022] Depending on the length and distance (or distances) of the traction line and the capacitance values ​​of the intermediate circuit capacitors, the oscillation capability and thus also the current gain of the high-voltage system under consideration differ. The influencing factors become clear when considering the relationship between the resonant frequency of the resonant circuit. The dimensioning of the intermediate circuit capacitors is closely coordinated with the drive motor and therefore can generally be influenced only slightly. However, the (line) inductance of the traction line can be changed. The (line) inductance can be estimated analytically, in particular, as follows:

[0023] With increasing line length l, the inductance L of the traction line increases with the radius r w However, longer cables result in increased material costs and weight.

[0024] The system resonance can thus be adjusted via the inductance, particularly by adjusting the distance d between the electrical lines of the traction line. The greater the distance d, the greater the inductance (taking into account the logarithmic relationship and the magnetic permeability / ).

[0025] In one embodiment, the distance is selected to be constant over a predetermined section of the traction line. In particular, the distance can be selected and / or adjusted over a larger section. Furthermore, a distance can also be selected and / or adjusted only for a section of the traction line that is accessible to adjustment. In particular, the predetermined section can comprise the entire length of the traction line. The entire length of the line here includes, in particular, the length that is accessible to a distance change.

[0026] In one embodiment, the spacing of the electrical conductors along the traction line is selected differently for each section. This allows the traction arrangement to be designed more flexibly and, in particular, to be adapted more flexibly to given conditions, such as design and / or installation space restrictions, etc. Along with the section-by-section spacing, the lengths of the individual sections can also be selected. The total inductance of the traction line results from the sum of the individual n sections:

[0027] L = LL + L2 + ••• + L n

[0028] In one embodiment, it is provided that the electrical conductors are guided and / or fastened at least in sections in at least one cable duct and / or at least one cable guide. As a result, the distance between the electrical conductors can be selected and / or adjusted particularly easily over a predetermined section. The at least one cable duct and / or the at least one cable guide can be open or closed. The electrical conductors are arranged and / or fastened, for example, with the aid of the at least one cable duct and / or the at least one cable guide on the body or on the high-voltage battery of the vehicle. For example, the at least one cable duct and / or the at least one cable guide can be arranged or can be arranged on an upper side of the high-voltage battery.In particular, it can be provided that each of the electrical conductors is guided in its own cable duct or cable guide.

[0029] In one embodiment, the traction arrangement comprises at least one fastening element, which serves to fasten the electrical conductors to a vehicle body at a selected distance from one another, at least in certain sections. The fastening element can be designed, for example, as a clamp (clip). The at least one fastening element can serve for the point-by-point fastening of an electrical conductor to the body and / or another part of the vehicle. With the aid of several of these fastening elements, the electrical conductors of the traction line can be arranged and / or fastened to the body and / or another part of the vehicle.However, the at least one fastening element can also be designed as a holding device that holds a larger section of one of the electrical conductors or of both electrical conductors and arranges it on the body and / or another part of the vehicle at the selected distance. In other words, the at least one fastening element can also be used for non-point arrangement and / or fastening. It can be provided that the at least one fastening element can be configured with respect to a distance between the two electrical conductors so that a distance between the electrical conductors can be adjusted on the at least one fastening element. In particular, it can be provided that a set distance can be fixed after adjustment so that the distance remains in the installed state.

[0030] In one embodiment, the predetermined value of the inductance is selected such that resonance excitation is reduced or prevented at least in a selected operating range of the traction assembly. This allows a direct influence on the vibration behavior (electrical, electromagnetic, and / or mechanical) of the traction assembly, particularly in interaction with the body and / or other components of the vehicle. The selected operating range refers in particular to an operating frequency or clock frequency of the drive converter and / or the drive motors (electrical motors).

[0031] In one embodiment of the method, it is provided that, in order to determine the predetermined value of the inductance of the traction line, a frequency-dependent current gain along the traction line is determined and compared with a predetermined operating range of the traction arrangement. In this way, a spectrum of the current gain can be determined starting from an actual state of the traction line (i.e. with a distance between the electrical lines that has not yet been set or a distance that has already been set). By comparing it with a predetermined operating range (in particular with regard to a frequency range of the drive converters and / or drive machines), the inductance can be selected, for example with the aid of the equation given above, such that a resonance frequency or a resonance range of the current gain lies outside of the predetermined operating range, rather than within the predetermined operating range.

[0032] Further features of the method are described in the description of the various embodiments of the traction arrangement. The advantages of the method are the same as those of the various embodiments of the traction arrangement.

[0033] Furthermore, in particular, a vehicle is also created, comprising at least one traction arrangement according to one of the described embodiments.

[0034] The invention will be explained in more detail below using preferred embodiments with reference to the figures.

[0035] Fig. 1 is a schematic diagram illustrating embodiments of the traction arrangement for a vehicle;

[0036] Fig. 2 is a schematic diagram illustrating an embodiment of the traction arrangement for a vehicle;

[0037] Fig. 3 is a schematic diagram illustrating an embodiment of the traction arrangement for a vehicle; Fig. 4 is a schematic diagram illustrating an embodiment of the traction arrangement for a vehicle;

[0038] Fig. 5 is a schematic flow diagram illustrating embodiments of the method for configuring a traction arrangement for a vehicle;

[0039] Fig. 6 is a schematic flow diagram illustrating an embodiment of the method for configuring a traction arrangement for a vehicle;

[0040] Fig. 7 is an example diagram for a frequency-dependent current gain to illustrate an embodiment.

[0041] Fig. 1 shows a schematic representation to illustrate an embodiment of the traction arrangement 1 for a vehicle 50. The traction arrangement 1 comprises a first power electronic component 2, at least one second power electronic component 3, and an unshielded traction line 4, which comprises two electrical conductors 4-1, 4-2 and forms an electrical connection to the first power electronic component 2 and to the at least one second power electronic component 3. The traction line 4 is electrically connected in particular to a high-voltage battery 5 of the vehicle 50. The high-voltage battery 5 can be part of the traction arrangement 1.

[0042] The first power electronic component 2 is, for example, a drive converter, in particular a pulse-controlled inverter, which supplies a drive motor (electrical machine), for example, a rear-wheel drive. The at least one second power electronic component 3 is, for example, a drive converter, in particular a pulse-controlled inverter, which supplies another drive motor (electrical machine), for example, a front-wheel drive.

[0043] A distance d between the electrical conductors 4-1, 4-2 along the traction line is selected such that an inductance of the traction line 4 has a predetermined value. Depending on the desired inductance of the traction line 4, the distance d is increased or decreased. The relationship between the distance d and the inductance stated in the general part can be used as a basis for this. It can be provided that the distance d is selected to be constant over a predetermined section of the traction line 4. This is shown schematically in Fig. 1. There, the distance d is the same or constant over the entire length of the traction line 4.

[0044] It can be provided that the distance d1, d2, d3, d4, d5 of the electrical conductors 4-1, 4-2 along the traction line 4 is selected to be different in certain sections. This embodiment is illustrated schematically in Fig. 2. The inductances L2, L3, L4 and L5 of the individual sections add up to the total inductance.

[0045] It can be provided that the electrical conductors 4-1, 4-2 are guided and / or fastened at least in sections in at least one cable duct and / or at least one cable guide 6-1, 6-2. This embodiment is illustrated schematically in Fig. 3. Two cable ducts or cable guides 6-1, 6-2 are provided, in which the electrical conductors 4-1, 4-2 are each arranged at a constant distance d from one another. The distance d is constant over most of the traction line 4; only at the ends of the cable ducts or cable guides 6-1, 6-2 can the distance between the electrical conductors 4-1, 4-2 be different, in the example shown, in order to feed the electrical conductors 4-1, 4-2 to the respective power electronic components 2, 3. The cable ducts or cable guides 6-1, 6-2 can, for example, be made of a plastic or comprise such a material.The cable ducts or cable guides 6-1, 6-2 can be arranged, for example, on the upper side of the high-voltage battery 5 (Fig. 1) in the vehicle. The cable ducts or cable guides 6-1, 6-2 can be designed as individual / separate components or can be interconnected.

[0046] It can be provided that the traction arrangement 1 has at least one fastening element 7, which serves to fasten the electrical conductors 4-1, 4-2 to a body 51 of the vehicle at a distance from one another that is selected at least in certain sections. This embodiment is illustrated schematically in Fig. 4. Several fastening elements 7 are shown, which are designed, for example, as clamps 8 that are connected to the body 51 and in which the electrical conductors 4-1, 4-2 are held at certain points. The fastening elements 7, in particular the clamps 8, can be designed such that they can be arranged at different positions on the body 51, so that a distance between the electrical conductors 4-1, 4-2 can be changed and adjusted in certain sections in order to set the predetermined value for the inductance. In the example shown, a circular conductor loop 9 is formed in this way or for this purpose.It can be provided that the predetermined value of the inductance is selected such that resonance excitation is reduced or prevented at least in a selected operating range of the traction arrangement 1. In particular, the selected operating range relates to a clock or carrier frequency of a modulation of the power electronic components 2, 3, in particular the drive converter (pulse-controlled inverter).

[0047] Figure 5 shows a schematic flow diagram illustrating embodiments of the method for configuring a traction arrangement for a vehicle. The traction arrangement is, for example, the traction arrangement shown in Figure 1.

[0048] In a measure 100, a predetermined value for the inductance of the traction line is determined. This can be done, for example, using analytical and / or numerical methods and / or simulation.

[0049] In a measure 101, a spacing of the electrical conductors along the traction line is adjusted so that the specified value for the inductance is achieved. It can be provided that the spacing of the electrical conductors is adjusted over a specified section of the traction line. It can be provided that the spacing of the electrical conductors is adjusted differently in each section along the traction line.

[0050] Figure 6 shows a schematic flowchart illustrating embodiments of the method for configuring a traction arrangement for a vehicle. In particular, the determination of the predetermined value for the inductance of the traction line is described in more detail as part of measure 100 (Figure 5).

[0051] In step 100a, an operating range of the traction arrangement is determined. In particular, the frequencies occurring during operation are determined. In the simplest case, this determination can be achieved by specifying the operating range, particularly the clock and carrier frequencies. Traction converters typically operate in the frequency range of a few kHz.

[0052] In a measure 100b, a frequency-dependent current gain along the traction line is determined based on parameters of the technical design of the traction arrangement. The technical design includes, in particular, the values ​​of electrical components and dimensions of the traction line, such as the intermediate circuit capacitors, and the geometric arrangement and design of the electrical conductors of the traction line. In particular, a starting or actual distance between the electrical conductors is initially assumed. Based on this, an ohmic resistance (R) and the inductance (L) of the traction line can be determined using analytical and / or numerical calculation methods. Using these parameters, the frequency-dependent current gain can be determined.

[0053] An example result is shown in Fig. 7. Fig. 7 shows the current gain on the y-axis and the frequency on the x-axis. The first peak 10-1 at approximately 6 kHz represents an example initial situation (L = 2.7 pH), which is changed by increasing the distance between the electrical conductors and a concomitant increase in the inductance value. By increasing the distance and increasing the inductance values, the two example resonance peaks 10-2 (L = 3.5 pH) and 10-3 (L = 5 pH) shift to lower frequencies. In this way, a resonance range of the traction arrangement can be shifted outside the specified operating range (specified frequency range, e.g., around 6 kHz), so that the occurrence of resonant oscillations can be reduced or even completely prevented.

[0054] In step 100c (Fig. 6), the frequency-dependent current gain is compared with the determined operating range. In particular, it is checked whether a resonant frequency of the traction arrangement lies within the frequency range of the operating range. If this is the case, the inductance value is changed in step 100d. The process then returns to step 100b, and steps 100b and 100c are repeated with the changed value. If this is not the case, a distance between the electrical conductors corresponding to the initial or changed inductance value is determined in step 100e. This can be done, for example, using the relationship specified in the general description.The test and optimization loop 100b, 100c, 100d is carried out in particular until the frequencies of the operating range are completely outside the resonance range or at least to the extent that a sufficiently acceptable system behavior is achieved.

[0055] In step 101, the specified spacing of the electrical conductors along the traction line is then adjusted so that the specified value for the inductance is achieved. Resonance of the traction assembly is then entirely or at least predominantly outside the specified operating range of the traction assembly. Disturbing excitations of vehicle parts and noise can thus be reduced or even completely eliminated.

[0056] List of reference symbols

[0057] 1 Traction arrangement

[0058] 2 first power electronic component

[0059] 3 second power electronic component

[0060] 4 Traction line

[0061] 4-1 electrical conductor

[0062] 4-2 electrical conductor

[0063] 5 high-voltage battery

[0064] 6-1 Cable duct / cable guide

[0065] 6-2 Cable duct / cable routing

[0066] 7 Fastening element

[0067] 8 terminal

[0068] 9 circular conductor loop

[0069] 50 vehicles

[0070] 51 Body

[0071] 100-101 Measures of procedure d distance dx distance (section x)

[0072] Inductance (section x)

Claims

Patent claims 1. Traction arrangement (1) for a vehicle (50), comprising: a first power electronic component (2), at least one second power electronic component (3), and an unshielded traction line (4) which comprises two electrical conductors (4-1, 4-2) and forms an electrical connection to the first power electronic component (2) and to the at least one second power electronic component (3), wherein a distance (d) of the electrical conductors (4-1, 4-2) along the traction line (4) is selected such that an inductance of the traction line (4) has a predetermined value.

2. Traction arrangement (1) according to claim 1, characterized in that the distance (d) is selected to be constant over a predetermined section of the traction line (4).

3. Traction arrangement (1) according to claim 1 or 2, characterized in that the distance (d) of the electrical conductors (4-1, 4-2) along the traction line (4) is selected to be different in sections.

4. Traction arrangement (1) according to one of the preceding claims, characterized in that the electrical conductors (4-1, 4-2) are guided and / or fastened at least in sections in at least one cable duct and / or at least one cable guide (6-1, 6-2).

5. Traction arrangement (1) according to one of the preceding claims, characterized by at least one fastening element (7) which serves to fasten the electrical conductors (4-1, 4-2) to a body (51) of the vehicle (50) at a distance (d) from one another which is selected at least in sections.

6. Traction arrangement (1) according to one of the preceding claims, characterized in that the predetermined value of the inductance is selected such that resonance excitation is reduced or prevented at least in a selected operating range of the traction arrangement (1).

7. Vehicle (50) comprising at least one traction arrangement (1) according to one of claims 1 to 6.

8. A method for configuring a traction arrangement (1) for a vehicle (50), wherein the traction arrangement (1) comprises a first power electronic component (2), at least one second power electronic component (3) and an unshielded traction line (4) which comprises two electrical conductors (4-1, 4-2) and forms an electrical connection to the first power electronic component (2) and to the at least one second power electronic component (3), comprising: determining a predetermined value for an inductance of the traction line (4), setting a distance (d) of the electrical conductors (4-1, 4-2) along the traction line (4) such that the predetermined value for the inductance is present.

9. Method according to claim 8, characterized in that the predetermined value of the inductance is selected such that resonance excitation is reduced or prevented at least in a selected operating range of the traction arrangement (1).

10. Method according to one of claims 8 or 9, characterized in that to determine the predetermined value of the inductance of the traction line (4), a frequency-dependent current gain along the traction line (4) is determined and compared with a predetermined operating range of the traction arrangement (1).

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