DE102013216703B4 - Unit for interference suppression of a pulse inverter - Google Patents

Abstract

Assembly (10) for interference suppression of a pulse-controlled inverter (3), in particular for the drive train (1) of an electric vehicle, - with a housing (20) for receiving a connection line (30) to be contacted with the pulse-controlled inverter (3), the housing (20 ) comprises a lower housing part (21) and a cover (22) which can be placed on the lower housing part (21) to close the housing (20), and a connecting terminal (32) in the housing interior (31) delimited by the lower housing part (21) ) is arranged for connecting the connecting line (30), and with a two-part filter ferrite (40) which has a straight section (41) and a forked counterpart (42) with at least two teeth (43), the straight section (41 ) is fixed in the lower housing part (21), and the counterpart (42) is fixed to the cover (22) in such a way that the teeth (43) of the counterpart (42) with the cover (22) on a flat side (61) of the straight section (41), see chap o that between the straight section (41) and the counterpart (42) an annularly enclosed cavity (60) is formed, in which the connection line (30) rests in an assembled state.

Description

The invention relates to a structural unit for attenuating electromagnetic interference signals that occur on a connection line of a pulse-controlled inverter (also known as “PWR” for short). The pulse-controlled inverter is used in particular in the drive train of an electric vehicle.

The drive train of an electric vehicle - be it a purely electric vehicle or a vehicle with hybrid drive - typically includes a (high-voltage) battery, an electric motor and a (pulse) inverter to convert the DC voltage supplied by the battery into that used to drive the Electric motor required - mostly multi-phase - AC voltage. The high-voltage supply assigned to this power circuit is typically in a voltage range of around 400 volts.

In such pulse inverters, interfering high-frequency signal components arise from switching processes during conversion. Filter ferrites are usually used to suppress interference, i.e. to filter out these high-frequency signal components. Such filter ferrites are used on the one hand on the load side, that is between the pulse-controlled inverter and the drive motor connected to it as a load, and on the other hand, on the input side, that is between the pulse-controlled inverter and the high-voltage battery of the electric vehicle.

The connecting lines that penetrate the filter ferrites are often only a short length of a few centimeters and are used in particular to connect the power rails of the PWR to a connector. These connection lines are often comparatively rigid due to their short length and, at the same time, a large conductor cross-section.

To make contact with the PWR, the connection lines are often screwed to the associated busbar of the PWR in a connection housing, each using a (ring) cable lug. In most cases, the cable lug is crimped onto the connection line before the filter ferrite is installed.

The filter ferrites used are mostly ring-shaped, closed ferrite cores through which the connection line provided with the cable lug has to be threaded.

Due to the comparatively large width of conventional cable lugs, the opening in the toroidal core must be dimensioned comparatively large, so that an unfavorably large air gap remains between the connecting line and the toroidal core in the assembled state. In addition, the assembly of the filter ferrite is sometimes tedious due to the rigidity of the connection line and the often cramped installation space in the connection housing.

From the DE 10 2007 033 294 A1 and from the DE 10 2009 014 149 A1 a connection terminal or a connection box with a two-part housing is known in each case, a part of a two-part filter ferrite being arranged in each housing half. When the housing is assembled, the two ferrite parts form an annular filter ferrite through which a cable to be connected is passed.

From the JP H04 - 53 194 A (Abstract) an interference suppression unit for a cable is known in which the cable is passed through a two-part filter ferrite. The cable lies in a forked section of the filter ferrite which is held on a rail and which can be closed by a straight section of the filter ferrite.

The invention is based on the object of specifying a device for interference suppression of a pulse-controlled inverter which, in spite of a compact and easily assembled structure, enables effective interference suppression of the PWR.

This object is achieved according to the invention with respect to a module for suppressing interference in the PWR by the features of claim 1. With respect to a PWR that is provided with the module, the object is achieved by the features of claim 6. Advantageous and in part inventive designs and developments are the subject of the subclaims.

The structural unit according to the invention for interference suppression of a pulse-controlled inverter, which is used in particular for the drive train of an electric vehicle, comprises a (connection) housing which is used to accommodate a connection line. The housing is formed by a - in particular approximately trough-shaped - lower housing part which can be closed by an associated cover. A connection terminal for connecting the connection line is arranged in the lower part of the housing.

A connection line is to be understood in particular as an electrical line that is used to connect the pulse-controlled inverter directly or indirectly to an input-side supply line or a load-side discharge line in an electrically conductive manner. Such a connection line is formed in particular by a cable which, in typical dimensions, has, for example, a line cross-section of approximately 30-50 mm ² and which, within a connection housing, has a length in the range of approximately 3 cm, for example.

According to the invention, the structural unit comprises a two-part filter ferrite, in particular a reversibly divisible filter ferrite. A filter ferrite is an electrotechnical component which is formed by a ferrite body (ferrite core) with which an electrical line is sheathed in a manner known per se in order to attenuate high-frequency interfering signals in the line.

According to the invention, the filter ferrite comprises a first, straight (in particular rod-shaped or plate-shaped) section. This section is often referred to as an "I-shape" ferrite core based on its shape. In addition, the filter ferrite comprises a second part, which is also referred to below as the “counterpart”. The counterpart is fork-shaped when viewed in cross section and thus has at least two teeth, starting from a back, between which a gap is formed. A ferrite core with two teeth is also referred to as a “C” or “U” shaped ferrite core. In the context of the invention, however, the second part can also comprise more than two, in particular three teeth (“E-shape”) or four teeth.

In a pre-assembly state in which the associated connection line is not yet in the housing, the straight section of the filter ferrite is already firmly fixed in the lower housing part, i.e. (in particular rigidly) connected to it. The part can in particular be glued in the lower part of the housing or locked in a receptacle provided for this purpose. The straight section is arranged at a point on the housing at which it is covered by the connection line received in the housing as intended.

According to the invention, the counterpart is fixed to the cover. The counterpart is arranged on the cover in such a way that when the cover is installed it is positioned as intended opposite the straight section and is fixed in opposition to the straight section, so that the teeth of the counterpart come into contact with a flat side of the straight section, so that between the straight section and the counterpart (more precisely between two teeth and the back of the counterpart and the flat side of the straight section) an annularly closed cavity is formed in which the connecting line rests in an assembled state.

To assemble the structural unit, the connection line is first inserted into the housing, which is in the pre-assembly state, and screwed into the housing with the associated connection rail or connection terminal of the PWR. The fork-shaped counterpart is then placed on the connecting line thus positioned and fixed and is fixed in opposition to the straight section.

The geometry of the filter ferrite according to the invention with a flat part and a counterpart fork-like in cross section is particularly advantageous for the assembly of the associated connection line. The fact that the flat section does not or at least only very little hinders the introduction of the (sometimes very stiff) connection line into the housing has a particularly favorable effect on the assembly. In particular, the lines provided with the ring cable lug do not have to be passed through a hollow ferrite mold in a complex manner.

When the fork-like counterpart is placed on, the connection line is preferably not only positioned, but already mounted and thus fixed with regard to its position, so that the counterpart can also be placed on without any problems.

As a result of the two-part filter ferrite, the filter ferrite can advantageously be dimensioned in accordance with the cable thickness of the connecting line and not in accordance with the associated cable lug. As a result, the filter ferrite can be designed in such a way that it tightly encloses the connection line in the assembled state, whereby its filter / damping effect is advantageously improved. In addition, the filter ferrite overall can be of comparatively compact dimensions.

For the purpose of tolerance compensation, the counterpart is expediently spring-loaded on the cover, i.e. elastically connected to the cover. A spring element that elastically connects the counterpart to the cover can in particular be formed as a plastic or metal spring or by an elastically deformable elastomer or foam body. Here, the straight section and the counterpart are pressed together by the spring force of the spring element.

In one embodiment, the straight section and / or the counterpart are arranged on a housing wall which, when the housing is installed as intended, adjoins a heat sink (which is also used in particular to cool the PWR). In this way, effective cooling of the filter ferrite is achieved in particular via the straight section (fixed to the housing wall).

The pulse-controlled inverter according to the invention is provided with at least one structural unit as described above. The structural unit can be provided both on the input side and on the output side of the PWR. In both cases, either single-phase filter ferrites or multi-phase (common mode) filter ferrites can be used. At In the case of single-phase filter ferrite, the filter ferrite only surrounds a single, current-carrying line (I-shape in combination with U- or C-shape). In the case of multi-phase filter ferrite, the ferrite core surrounds several lines (I-shape in combination with E-shape or a comb-like counterpart with four teeth), the currents of which add up to zero under normal conditions. For example, the two supply lines that connect the poles of the high-voltage battery to the inverter's intermediate circuit rails are routed through a two-phase filter ferrite. The three phase lines of a three-phase load circuit can also be routed through a three-phase filter ferrite. Such a common mode filter ferrite advantageously only acts on common-mode interference which disturbs the symmetry of the currents flowing in the enclosed lines.

• 1 in schematischer Darstellung einen Antriebsstrang eines Elektrofahrzeugs mit einem Pulswechselrichter, dessen Zu- und Ableitungen jeweils mit einer Baueinheit versehen sind, die jeweils einen Filterferrit zur Entstörung umfasst,
• 2 in dreidimensionaler Darstellung eine der Baueinheiten gemäß 1,
• 3 in einer Längsschnittdarstellung die Baueinheit gemäß 2,
• 4 in ausschnittsweiser Darstellung gemäß 1 eine Baueinheit mit einem Common Mode-Filterferrit zur Entstörung der Zuleitungen,
• 5 in einer Querschnittsdarstellung den Filterferrit für die Ausführungsform gemäß 4, und
• 6 und 7 in Darstellung gemäß 4 bzw. 5 eine Baueinheit mit einem Common Mode Filterferrit zur Entstörung der Ableitungen bzw. den zugehörigen Filterferrit.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Show in it:

• 1 a schematic representation of a drive train of an electric vehicle with a pulse-controlled inverter, the feed and discharge lines of which are each provided with a structural unit that each includes a filter ferrite for interference suppression,
• 2 one of the structural units according to FIG 1 ,
• 3 in a longitudinal sectional view the unit according to 2 ,
• 4th in excerpts according to 1 a unit with a common mode filter ferrite for interference suppression of the supply lines,
• 5 the filter ferrite for the embodiment according to FIG 4th , and
• 6th and 7th in representation according to 4th or. 5 a unit with a common mode filter ferrite for interference suppression of the discharges or the associated filter ferrite.

Corresponding parts are always provided with the same reference symbols in all figures.

1 shows the drive train in a roughly schematic overview 1 of an electric vehicle. The powertrain 1 essentially comprises a high-voltage battery 2 , which supplies a DC voltage of around 400 volts, a pulse inverter 3 for converting the from the high-voltage battery 2 supplied DC voltage into a three-phase AC voltage, as well as an electric motor 4th .

The high-voltage battery 2 is by means of two electrical leads 6th with the pulse inverter 3 connected, during this by means of three derivatives 7th with the electric motor 4th is electrically connected.

For partial interference suppression of the pulse inverter 3 is in the first embodiment shown here for each inlet or outlet 6.7, a separate structural unit 10 intended.

One of the building units 10 is in 2 shown in a single representation in a pre-assembly state.

The structural unit 10 includes a housing 20th , which is essentially characterized by an upwardly open, flat cuboid housing lower part 21 is formed with an associated cover 22nd can be closed with the help of screw connections. The case 20th is made of die-cast aluminum, for example.

At one end 24 of the housing 20th is an implementation 25th introduced through the one connection line (not yet installed here) 30th in the housing 20th is insertable. Inside the housing 31 of the housing 20th is a connection terminal 32 recorded, based on the (according to 3 ) a power rail 33 through the case back 34 as an electrically conductive connection to the pulse-controlled inverter 3 is led out. The connection terminal 32 is with a threaded hole 35 Mistake.

The structural unit 10 further comprises a two-part filter ferrite 40 , which in turn is a first straight section 41 and a second, as a counterpart 42 includes designated, fork-like portion.

The first straight section 41 is formed by a flat, rectangular ferrite body. The counterpart 42 is fork-shaped in cross section. With the counterpart 42 This is a U-shaped ferrite core available as a standard design. The two legs or webs of the counterpart 42 are - without limitation to a certain shape - as teeth 43 designated. Every tooth 43 preferably has a constant thickness in cross section and a flat free end.

The first part 41 is according to 1 inside the housing 31 on the case back 34 between implementation 25th and the connection terminal 32 flat on the case back 34 fixed adjacent, here glued with a thermally conductive adhesive.

The counterpart 42 is on the lid 22nd fixed. The sectional view in 3 it can be seen that the counterpart 42 with his back 50 on the intended use of the housing interior 31 facing inside 51 of the lid 22nd is fixed. The teeth 43 protrude approximately vertically from the inside 51 from. The counterpart 42 is with the help of two spring elements 52 , which are each formed here by an elastic plastic body, opposite the cover 22nd resiliently fixed.

The connecting cable 30th comprises a cable that is flexible in and of itself, but relatively stiff due to its short length and comparatively large diameter 55 , which in turn is formed by a conductor sheathed with electrical insulation.

To the cable 55 is on the one hand a connector 56 attached while the other hand on the cable 55 a (ring) cable lug 57 is crimped on.

To the pulse inverter 3 with the help of the unit 10 The connection cable is to be wired as intended 30th by performing 25th passed through.

Then on the one hand the connector (only roughly indicated here) 56 in a manner known per se in the implementation 25th anchored. On the other hand is the cable lug 57 with the hole provided for this purpose on the threaded hole in the connection terminal, which is also provided for this purpose 32 screwed. Finally the lid becomes 22nd on the lower part of the housing 21 put on and screwed, creating the counterpart 42 opposite the section 41 is positioned and fixed as intended. According to the in 3 The assembly state shown is the counterpart 42 opposite the section 41 positioned and fixed in such a way that all of the filter ferrite 40 now the cable 55 fully enclosed or sheathed. By the spring force of the spring elements 52 are the teeth 43 of the counterpart 42 with the formation of a completely closed, tunnel-like cavity 60 against a plan page 61 of the section 41 pressed.

In the installed state of the unit 10 borders the case back 34 to one, among other things, for cooling the pulse-controlled inverter 3 provided heat sink, whereby the plan is attached filter ferrite 40 is also effectively cooled.

In 4th is a section of the drive train 1 shown in which the structural unit 10 according to a second embodiment for the simultaneous interference suppression of both feed lines 6th serves. In contrast to the single-phase first embodiment, in this embodiment the housing is not shown in detail here 20th two connection cables 30th recorded.

According to 5 is the cover-side counterpart 42 of the filter ferrite shown here as a single representation 40 In contrast to the first embodiment, it is formed by an E-shaped ferrite core (also available as a standard component). In the assembly state shown, each of the two connecting lines is located 30th each in one between the first section 41 and the counterpart 42 formed cavity 60 a.

The illustration clearly shows that the dimensioning of the filter ferrite 40 , in particular its leg width, based on the line diameter of the cable 55 takes place, and thus the filter ferrite 40 close to the cable 55 is applied.

In a third embodiment of the structural unit 10 is this to accommodate three connection cables 30th educated. This embodiment is used in accordance with 6th for connecting the pulse-controlled inverter on the AC side 3 . The cover-side counterpart 42 is according to 6th seen in cross-section like a comb with four teeth 43 educated. Again, the respective connection lines are located 30th as intended in the corresponding cavities 60 a.

In a further, not shown here, embodiment of the invention are the pulse-controlled inverters 3 , the input and / or output-side provided filter ferrites 40 , as well as the connection terminals 32 received together in a single housing that can be closed by a (overall) cover, so that the respective structural units 10 are an integral part of this common housing. In this case, both the supply lines 6th as well as the derivatives 7th associated counterparts 42 assembled together.

The subject matter of the invention is not limited to the exemplary embodiments described above. Rather, further embodiments of the invention can be derived from the above description by a person skilled in the art. In particular, the individual features of the invention described on the basis of the various exemplary embodiments and their design variants can also be combined with one another in other ways.

Claims (5)

Component (10) for interference suppression of a pulse-controlled inverter (3), in particular for the drive train (1) of an electric vehicle, - with a housing (20) for receiving a connection line (30) to be contacted with the pulse-controlled inverter (3), the housing (20 ) comprises a lower housing part (21) and a cover (22) which can be placed on the lower housing part (21) to close the housing (20), and in which it is delimited by the lower housing part (21) Housing interior (31) a connecting terminal (32) for connecting the connecting line (30) is arranged, as well as - with a two-part filter ferrite (40), which has a straight section (41) and a forked counterpart (42) with at least two teeth (43) wherein the straight section (41) is fixed in the lower housing part (21), and the counterpart (42) is fixed to the cover (22) in such a way that the teeth (43) of the counterpart (42) when the cover is in place ( 22) meet a flat side (61) of the straight section (41), so that between the straight section (41) and the counterpart (42) an annularly enclosed cavity (60) is formed in which the connection line (30) is in one Assembly state is present. Assembly (10) according to Claim 1 , with at least one spring element (52) by which the counterpart (42) is spring-loaded on the cover (22). Assembly (10) according to Claim 1 or 2 , wherein the counterpart (42) has three or four teeth (43), so that between the straight section (41) and the counterpart (42) placed on it, several cavities (60) for receiving a connection line (30) are formed. Assembly (10) according to one of the Claims 1 to 3 , the straight section (41) and / or the counterpart (42) being arranged on a housing wall (34) that is intended to adjoin a heat sink. Pulse-controlled inverter (3), in particular for the drive train (1) of an electric vehicle, with at least one structural unit (10) according to one of the Claims 1 to 4th .

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