Manufacturing-optimized EMC input filter and assembly process

Abstract

Proposed is a manufacturing-optimized EMC input filter for a power electronics application in a vehicle, comprising a housing open on one underside with at least two magnetic cores arranged inside the housing, wherein the housing has several through-holes and mounting pockets, the through-holes being designed to accommodate DC busbars or stamped grids, and the mounting pockets being designed to accommodate X or Y capacitors, and a printed circuit board arranged and mechanically connected to the underside of the housing, and wherein the printed circuit board is designed and populated such that an X capacitor and at least one Y capacitor per magnetic core are arranged on a side of the printed circuit board facing the interior of the housing and opposite the mounting pockets, and are electrically contacted by a conductor track of the printed circuit board.and a DC negative and a DC positive busbar, which passes through two through-holes in the housing and through central holes in the magnetic cores, and a number of stamped grids corresponding to the number of X and Y capacitors, which are passed through the through-holes from a top side of the housing opposite the bottom side and are electrically contacted at one end with the circuit board, and at the other end rest on one of the DC busbars or a ground connection and are thus mechanically connected. A mounting method is also proposed.

Description

[0001] The present invention relates to the field of electromobility, in particular to electronic modules for an electric drive.

[0002] The use of electronic modules, such as power electronic modules, in motor vehicles has increased significantly in recent decades. This is due, on the one hand, to the need to improve fuel economy and vehicle performance, and, on the other hand, to advances in semiconductor technology. The main component of such an electronic module is a DC / AC inverter, which is used to supply electrical machines such as electric motors or generators with a multi-phase alternating current (AC). This involves converting a direct current generated by a DC energy source, such as a battery or accumulator, into a multi-phase alternating current. EMC input filters, like a DC link capacitor, are part of an inverter. Current designs for EMC input filters are very complex in terms of design and manufacturing.

[0003] Therefore, the object of the invention is to improve the design of the DC EMC input filter so that it is optimized in terms of manufacturing technology, and to provide a corresponding assembly method.

[0004] This problem is solved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0005] A production-optimized EMC input filter for a power electronics application in a vehicle is proposed, comprising a housing open on an underside thereof with at least two magnetic cores arranged within the housing, wherein the housing has a plurality of through-openings and receiving pockets, wherein the through-openings are formed for receiving DC busbars or lead frames, and wherein the receiving pockets are formed for receiving X or Y capacitors, and a printed circuit board arranged on the underside of the housing and mechanically connected thereto, and wherein the printed circuit board is formed and populated in such a way that on a side of the printed circuit board facing the interior of the housing and opposite the receiving pockets, an X capacitor and at least one Y capacitor per magnetic core are arranged and electrically contacted with a conductor track of the printed circuit board.and a DC negative and a DC positive busbar, which are passed through two through-holes in the housing and through central holes in the magnetic cores, and a number of lead frames corresponding to the number of X and Y capacitors, which are passed from a top side of the housing opposite the bottom through the through-holes and are electrically contacted with the circuit board at one end, and rest with the other end on one of the DC busbars or a ground connection and are mechanically connected thereto.

[0006] In one embodiment, an adhesive is provided in the receiving pockets or on top of the X and Y capacitors.

[0007] In one version, the lead frames have a spring geometry in a central area.

[0008] Furthermore, an electronic module is provided, comprising the EMC input filter, and an inverter arrangement which is configured to convert a DC input current filtered by the EMC input filter into an AC output current.

[0009] Furthermore, an electric drive of a vehicle is provided, comprising the electronic module for controlling the electric drive.

[0010] Furthermore, an assembly method for the EMC input filter is provided, a printed circuit board is provided which is populated with X and Y capacitors at predetermined positions and in which conductor tracks are led from the X and Y capacitors to predetermined contact points on the printed circuit board, and wherein, in one or more steps, the housing manufactured as a pre-assembled assembly with magnetic cores arranged therein is connected to the populated printed circuit board and the DC minus and DC plus busbars by placing the printed circuit board on the open underside of the housing and securing it there, and the DC minus and DC plus busbars are pushed through the housing and the central holes of the magnetic cores, and in a further step, the lead frames are pushed through the through-openings of the housing and are electrically contacted with one end on the printed circuit board at the contact points provided for them,and with another end resting on the DC minus or DC plus busbars.

[0011] In one embodiment, the circuit board is provided as a pre-assembled unit. Alternatively, the circuit board is manufactured in a preliminary step by populating it with X and Y capacitors at predetermined positions and routing traces from the X and Y capacitors to predetermined contact points on the circuit board.

[0012] In one embodiment, an adhesive is applied inside the receiving pockets or on top of the X and Y capacitors before the circuit board is attached to the bottom of the housing.

[0013] In one embodiment, the EMC input filter is inserted into an inverter housing together with at least one inverter and a DC link capacitor in a further step, and then all DC minus and DC plus contacts are connected to the corresponding terminals in one operation.

[0014] In one version, the DC minus and DC plus contacts are connected by laser welding.

[0015] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details of the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0016] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. Fig. 1 shows a sectional view of an EMC input filter according to the prior art. Fig. 2 shows a sectional view of an EMC input filter according to an embodiment of the present invention. Fig. 3 shows an exploded view of the Fig. 2 shown EMC input filter.

[0017] In the following descriptions of the figures, the same elements or functions are provided with the same reference symbols.

[0018] The basic idea is to provide a structure of a DC-side EMC input filter 10 that is as simple as possible, i.e., production-optimized, which is part of an inverter used for electric drives of vehicles.

[0019] In Fig. Figure 1 shows a sectional view of an EMC input filter 10 according to the prior art. The EMC input filter 10 has a three-part housing 100, in the middle part of which magnetic cores 11 are arranged. The illustration shows a two-stage filter, i.e., two magnetic cores 11. DC busbars (DC plus 20 and DC minus 21) are guided from one end to the other through the length (x-direction) of the housing 100 and through an opening in the center of the magnetic cores 11. Two Y capacitors 30 per magnetic core 11 are arranged in receiving pockets 102, 103 in the area of ​​an underside of the housing 100 and below the magnetic cores 11, each of which is electrically connected to ground (GND) and DC plus potential.Furthermore, on the right of the image, below and next to a magnetic core 11, an X capacitor is arranged between the DC negative and DC positive busbars 20, 21, thus making electrical contact. X and Y capacitors 30, 31 are interference suppression capacitors known to those skilled in the art and are therefore not described in detail. The X and Y capacitors 30, 31 are arranged in the receiving pockets 102, 103, which are part of the housing 100, and are secured therein by means of a potting compound. To electrically contact the X and Y capacitors 30, 31, lead frames 50 are molded into the housing 100.

[0020] To Fig. 1 according to the prior art, the following steps are necessary. A pre-assembly is produced which essentially consists of a housing 100 with magnetic cores 11 arranged and fastened therein. Lead frames 50 are injected into the housing 100 in order to be able to later electrically contact components such as the X and Y capacitors 30, 31 with, for example, the DC minus and DC plus busbars 20, 21 or ground (GND). In the next step, the DC minus and DC plus busbars 20, 21 are pushed in the x-direction from one end to an opposite end through the housing 100 and the central openings of the magnetic cores 11. The pre-assembly is then turned over and the receiving pockets 102, 103 are activated by plasma cleaning so that the potting compound adheres later.Following the plasma treatment, the X and Y capacitors 30, 31, equipped with pre-assembled wires, are inserted into the housing, i.e., into the provided receiving pockets 102, 103, and the electrical connections between the wires and the lead frame 50 are established by resistance welding. Following this, the receiving pockets 102, 103 are filled with a potting compound. The housing 100 is then placed in a heating furnace to cure the potting compound and thus create the firm connection between the potting compound and the housing 100. In a final step, lead frames (in . Fig. 1 (not visible due to the sectional view) are mechanically connected to the corresponding DC negative and DC positive busbars 20, 21 by laser welding. The now finished EMC input filter 10 is then inserted into the inverter housing.

[0021] As can be seen from the description, numerous manufacturing steps and diverse production processes are involved, requiring a high level of expensive manufacturing resources. The new concept described below significantly simplifies the production of the EMC input filter 10.

[0022] To Fig. 2 and Fig. To manufacture the inventive EMC input filter 10 shown in Figure 3, the following steps are necessary. As already known from the prior art, a pre-assembly is produced, which essentially consists of a housing 100 open at its bottom with magnetic cores 11 arranged and secured therein. The housing 100 is also formed to accommodate the magnetic cores 11, which have a hole (an opening) in the center. This hole remains free so that the DC minus and DC plus busbars 20, 21 can be guided through the holes, as shown in both Fig. 1 as well as in Fig. 2. Furthermore, the housing 100 has a plurality of through-openings, some of which are formed and arranged to allow the DC-minus and DC-plus busbars 20, 21 to be pushed through the housing 100 and the openings of the magnetic cores 11, as shown in Fig. 2. Other through-holes not shown in the figures are formed and arranged to allow lead frames 50 (described below) to be pushed through the housing 100 to establish electrical contact between the printed circuit board 40 (described below) and the DC-negative and DC-positive busbars 20, 21. This means that the position, number, and size of the through-holes are adapted to the application.

[0023] In addition, a populated printed circuit board 40 is produced, on which the X and Y capacitors 30, 31 are provided (on the same side of the printed circuit board 40). The X and Y capacitors 30, 31 are electrically contacted with conductor tracks of the printed circuit board 40, e.g., by soldering. The conductor tracks are in turn electrically contactable with the DC negative and DC positive power rails 20, 21 via the lead frames 50 described below. Furthermore, ground (GND) is provided via at least one conductor track. One contact of the Y capacitors 30 is contacted with a conductor track of the printed circuit board 40 providing ground (GND). The other contact of the Y capacitors 30 and the contacts of the X capacitors 31 are contacted with conductor tracks of the printed circuit board 40, which are electrically connected to either the DC negative or the DC positive power rail 20, 21.

[0024] The printed circuit board 40 is arranged on a bottom side U of the housing 100 and mechanically connected to the housing 100. For this purpose, the printed circuit board 40 has connection areas, which are formed, for example, as holes. The housing 100 has screw points 104, with which the connection areas of the printed circuit board 40 are brought into alignment. The fastening is carried out, for example, by means of screws 60, as shown in Fig. 3. Furthermore, the arrangement of the X and Y capacitors 30, 31 on the circuit board 40 is provided such that they are immersed in the corresponding receiving pockets 102, 103 of the housing 100 when the circuit board 40 is / is fastened to the housing 100. In contrast to the prior art, it is not necessary to use a potting compound to fasten the X and Y capacitors 30, 31 in the receiving pockets 102, 103, since they are already fastened to the circuit board 40 and thus to the housing 100. However, an adhesive, e.g., a silicone adhesive, can still be provided in the receiving pockets 102, 103 (or on the upper sides of the X and Y capacitors 30, 31). However, this is not primarily used to attach the X and Y capacitors 30, 31, but rather as a buffer to protect the X and Y capacitors 30, 31 from vibrations.This step alone eliminates the need for plasma activation or the preparation and heating of a potting compound, thus saving on process equipment.

[0025] After the pre-assembly (i.e., housing 100 with magnetic cores 11 arranged therein) and circuit board 40 are connected to each other, the next step is to push the DC negative and DC positive busbars 20, 21 longitudinally (in the x-direction) from one end to an opposite end through the housing 100 and the central holes (openings) of the magnetic cores 11. It is also possible to first insert the DC negative and DC positive busbars 20, 21 into the housing 100 and then attach the circuit board 40, or to mount both simultaneously.

[0026] After the pre-assembly (i.e., housing 100 with magnetic cores 11 arranged therein), circuit board 40, and DC-minus and DC-plus busbars 20, 21 are mechanically connected to each other, separate lead frames 50 are inserted into the corresponding through-openings (not visible in the figures) in the housing 100 in order to establish the electrical connection for the X and Y capacitors 30, 31. Thus, a number of lead frames 50 corresponding to the number of X and Y capacitors 30, 31 is provided. Fig. 2 and Fig. In the embodiment shown in Figure 3, two Y capacitors 30 are provided for each filter stage (i.e., for each magnetic core 11), so that four lead frames 50 are required to contact the DC plus contact of each of the Y capacitors 30. Furthermore, an X capacitor 31 is provided, for which two lead frames 50 are required: one to connect it to DC plus, the other to connect it to DC minus.

[0027] The lead frames 50 are formed from an electrically conductive material such as copper. The lead frames 50 are guided through the through-openings with a (lower) end 51 from an upper side of the housing 100 opposite the underside U. This end 51 is electrically contacted on the circuit board 40. For this purpose, the end 51 can have one or more pins that are inserted into recesses provided on the circuit board 40 that are connected to conductor tracks on the circuit board 40 and then soldered in place, for example, to establish an electrical connection with other components arranged on the circuit board 40, such as the X or Y capacitors 30, 31. The other end 52 of the lead frame 50 protrudes on the top side of the housing 100 and rests on the DC minus or DC plus bus bar 20, 21, depending on whether the lead frame 50 is to be contacted with an X or a Y capacitor 30, 31.It is advantageous if the end 52 is arranged as described, since this makes it possible to process the EMC input filter 10 by laser welding only after it has been inserted into the inverter housing, along with all other busbars present there. This eliminates the need for a laser welding system, which would otherwise be required for the production of the EMC input filter 10.

[0028] The lead frames 50 also advantageously have a spring geometry in a central area, e.g. a double-curved shape, as in Fig. 3. Due to the spring effect of at least one bend in the central region of the lead frame 50, manufacturing tolerances can be compensated during assembly.

[0029] The cores 11 are generally formed as rings and have a circular cross-section. However, they can also have an oval or other cross-section, with a hole (an opening) always being provided in their center for the passage of the DC busbars 20, 21. The cores 11 are surrounded by the housing 100 in such a way that the holes are left free so that the DC busbars 20, 21 can pass through. Soft magnetic materials, e.g. ferrites or suitable nanocrystalline materials, are generally used as core materials for the magnetic cores 11. The latter have a significantly higher filtering effect and are therefore increasingly used. Nanocrystalline cores consist of a very thin strip material (sheet metal) which is wound or pressed into several layers and then baked.In the invention described below, the cores 11 are also formed as known from the prior art, i.e. in particular as nanocrystalline cores 11.

[0030] The new design concept of the EMC filter 10 significantly simplifies assembly, reducing the susceptibility to errors, manufacturing effort, and thus costs. Furthermore, individual components such as the housing 100 can be significantly simplified.

[0031] The EMC input filter is advantageously used as part of an electronic module with a housing referred to as an inverter housing, which serves to operate an electric drive of a vehicle, in particular an electric vehicle and / or a hybrid vehicle, and / or electrified axles. The electronic module comprises an inverter arrangement with a DC / AC inverter that converts the DC input current filtered by the EMC input filter into an AC output current. It can also comprise or be part of an AC / DC rectifier, a DC / DC converter, a transformer, and / or another electrical converter or a part of such a converter. In particular, the electronic module serves to supply current to an electric machine, for example, an electric motor and / or a generator.A DC / AC inverter is preferably used to generate a multi-phase alternating current from a direct current generated by means of a DC voltage from an energy source, such as a battery or accumulator. List of reference symbols 100 housings 101 Passage opening 102 Storage pocket for 30 103 Storage pocket for 31 104 screwing points 10 EMC input filters 11 magnetic cores 20 DC plus busbar 21 DC negative power rail 30 Y capacitors 31 X-capacitor 40 circuit board 50 punched grids 51, 52 ends of 50 60 screws (mechanical fastening) U bottom of 100

Claims

[1] Production-optimized EMC input filter (10) of a power electronics application in the vehicle, comprising - a housing (100) open on a bottom side (U) thereof, with at least two magnetic cores (11) arranged within the housing (100), wherein the housing (100) has a plurality of through-openings (101) passing through the housing (100) and receiving pockets (102, 103), wherein the through-openings (101) are formed for receiving DC busbars (20, 21) or lead frames (50), and wherein the receiving pockets (102, 103) are formed for receiving X or Y capacitors (30, 31), and - a printed circuit board (40) which is arranged on the underside (U) of the housing (100) and is mechanically connected thereto, and wherein the printed circuit board (40) is formed and populated in such a way that on a side of the printed circuit board (40) facing the interior of the housing (100) and opposite the receiving pockets (102, 103), an X-capacitor (31) and at least one Y-capacitor (31) per magnetic core (11) are arranged and electrically contacted with a conductor track of the printed circuit board (40), and - a DC minus and a DC plus busbar (20, 21) passing through two through-openings (101) of the housing (100) and through central holes of the magnetic cores (11), and - a number of lead frames (50) corresponding to the number of X and Y capacitors (30, 31), which are guided through the through-openings from an upper side of the housing (100) opposite the underside (U) and are electrically contacted with the printed circuit board (40) at one end (51), and rest with another end (52) on one of the DC busbars (20, 21) or a ground connection and are mechanically connected thereto. [2] EMC input filter according to claim 1, wherein an adhesive is provided in the receiving pockets (102, 103) or on top of the X and Y capacitors (30, 31). [3] EMC input filter according to claim 1 or 2, wherein the punched grids (50) have a spring geometry in a central region, [4] Electronic module comprising the EMC input filter according to one of claims 1 to 3, and an inverter arrangement which is designed to convert a DC input current filtered by the EMC input filter (10) into an AC output current. [5] Electric drive of a vehicle, comprising the electronic module according to claim 4 for controlling the electric drive. [6] Assembly method for an EMC input filter (10) according to one of claims 1 to 3, wherein - a printed circuit board (40) is provided which is equipped with X and Y capacitors (30, 31) at predetermined positions and in which conductor tracks are led from the X and Y capacitors (30, 31) to predetermined contact points on the printed circuit board (40), wherein - in one or more steps, the housing (100) manufactured as a pre-assembly with magnetic cores (11) arranged therein is connected to the populated printed circuit board (40) and the DC minus and DC plus busbars (20, 21) by placing the printed circuit board (40) on the open underside (U) of the housing (100) and fastening it there, and the DC minus and DC plus busbars (20, 21) are pushed through the housing (100) and the central holes of the magnetic cores (11), and - in a further step, the lead frames (50) are pushed through the through-openings of the housing (100) and are electrically contacted with one end (51) on the printed circuit board (40) at the contact points provided for this purpose, and rest with another end (52) on the DC minus or DC plus busbars (20, 21). [7] Assembly method according to claim 6, wherein the printed circuit board (40) is provided as a pre-assembled unit, or wherein the printed circuit board (40) is manufactured in a preliminary step by equipping it with X and Y capacitors (30, 31) at predetermined positions and by routing conductor tracks from the X and Y capacitors (30, 31) to predetermined contact points on the printed circuit board (40). [8] Assembly method according to claim 6 or 7, wherein before applying the circuit board (40) to the underside (U) of the housing (100), an adhesive is applied to the interior of the receiving pockets (102, 103) or to the top side of the X and Y capacitors (30, 31). [9] Assembly method according to claim 6, 7 or 8, wherein the EMC input filter (10) is inserted in a further step into an inverter housing together with at least one inverter and an intermediate circuit capacitor, and then all DC minus and DC plus contacts are connected to the associated terminals in one operation. [10] Assembly method according to claim 9, wherein the connection of the DC minus and DC plus contacts is carried out by laser welding.

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