Filter with circuit board and busbars

Abstract

Featuring filters for electromagnetic interference: a printed circuit board (5, 15) with conductor tracks, with a first side and with a second side opposite the first side, a first busbar (1, 11) which is attached to the first side of the circuit board (5, 15) and is electrically connected to at least one of the conductor tracks; a second busbar (2, 12) which is attached to the second side of the circuit board (5, 15) and is electrically connected to at least one of the conductor tracks; and at least one capacitor which is or are connected via the conductor tracks to the first and / or second busbar (1, 2; 11, 12); wherein the circuit board (5, 15) is arranged between the first busbar (1, 11) and the second busbar (2, 12) for their insulation, characterized by at least one magnetic element (4.1, 4.2, 14) arranged in a ring shape around the first and second busbars (1, 2; 11, 12), wherein at least in the area of ​​at least one magnetic element the circuit board (5, 15) is arranged between the first busbar (1, 11) and the second busbar (2, 12) for their insulation.

Description

Technical area

[0001] The invention relates to a filter for electromagnetic interference with a printed circuit board and busbars according to the preamble of claim 1. State of the art

[0002] Electronic systems in vehicles, such as motor vehicles, are becoming increasingly complex. The electrical components are becoming increasingly sensitive to electromagnetic interference and are also causing increasing levels of radio interference. Therefore, filters for suppressing electromagnetic interference, such as EMI or EMC filters, are increasingly being used in vehicle electrical systems. This issue is particularly relevant in electrically powered vehicles due to the high currents and high switching speeds of current transformers.

[0003] These filters are typically formed from a combination of one or more conductor rails, one or more inductors, and one or more capacitors. In existing solutions, the inductors and capacitors are connected to the conductor rails either directly or via cables. To achieve isolation between the electrical components, either sufficiently large distances or insulation, e.g., by encapsulating the electronic components, is provided. However, existing solutions suffer from the problem that they do not meet the existing requirements in vehicle construction regarding vibration, ease of high-volume production, high manufacturing quality, low space requirements, low weight, and flexibility for various power applications.

[0004] US 5875091 A discloses a generic filter according to the preamble of claim 1, comprising a busbar arrangement with filter capacitors. The busbars run parallel to a circuit board on both sides and are mechanically connected to each other by fastenings. The busbars are pressed against conductive layers on the circuit board, thus establishing electrical contact. Filter capacitors are arranged on a part of the circuit board that extends transversely beyond the busbars, with the poles of the filter capacitors each connected to one of the two conductive layers.

[0005] JP 2014-120518 A describes a filter that uses inductors for noise suppression. Several busbars extend through magnetic ring elements, with the busbars either insulated by air or by a plastic sheath. The entire assembly is then mounted on a circuit board, which is equipped with capacitors, which in turn are electrically connected to the busbars. Description of the invention

[0006] The object of the invention is to find an alternative filter that better meets the combination of the described requirements.

[0007] According to the invention, this object is achieved with a filter according to claim 1.

[0008] Arranging two busbars on opposite sides of a printed circuit board to create a filter offers a number of advantages. The busbars remain insulated from each other by the printed circuit board and can be arranged very close together, regardless of the power or current and / or voltage for which the filter is designed. Additional weight due to encapsulated insulation is also eliminated. Furthermore, complex cabling of electrical components or their direct mounting on the busbars is no longer necessary, as the electrical components can now be easily and automatically arranged on the printed circuit board and connected to the busbars via conductive tracks.The mounting of the electrical components, in particular the busbars, capacitors and magnetic elements on conductor tracks also allows for a very robust assembly, which ensures a good, reliable and long-lasting connection even in the event of strong vibrations.

[0009] The filter further comprises at least one magnetic element and at least one capacitor, with the busbars separated from the circuit board at least in the area of ​​the magnetic element. This allows the magnetic elements around the busbars to be made smaller and lighter for the implementation of current-compensated chokes or current transformers. The capacitors can be easily installed on the circuit board as electrical components.

[0010] Further advantageous embodiments are specified in the dependent claims.

[0011] In an advantageous embodiment, the at least one magnetic element is ring-shaped, and each at least one ring-shaped magnetic element is plugged onto a protrusion of the circuit board via a ring opening of the magnetic element. This type of assembly is simple, fast, and robust.

[0012] In an advantageous embodiment, the busbars are mechanically attached to the circuit board using fasteners, which simultaneously ensure an electrical connection between the respective busbar and a corresponding conductor track on the circuit board. This has the advantage of eliminating complex and vulnerable solder connections.

[0013] In one embodiment, the first busbar and the second busbar rest directly on the circuit board with a contact surface. This allows for a particularly robust mechanical and electrical connection between the busbars and the circuit board.

[0014] In one embodiment, the circuit board has a first conductor track area on the first side in the region of the contact area with the first busbar, which establishes electrical contact between the first busbar and the first conductor track area. Furthermore, the circuit board has a second conductor track area on the second side in the region of the contact area with the second busbar, which establishes electrical contact between the second busbar and the second conductor track area. This allows for a particularly good electrical connection between the busbars and the circuit board. Furthermore, the busbar behaves like a conductor track on the circuit board.

[0015] In one embodiment, the filter comprises a metallic housing, wherein the housing has at least one ground potential surface, wherein the circuit board has at least one ground conductor surface. Each of the at least one ground potential surface of the housing is pressed onto a corresponding ground conductor surface by fastening means, thus creating a ground connection from the circuit board to the housing. This has the advantage that no additional cables are required between the filter housing and the circuit board. Short description of the characters

[0016] The invention is explained in more detail with reference to the attached figures, in which Fig. 1 a circuit of a first embodiment of a filter. Fig. 2 a three-dimensional view of the first embodiment of the filter. Fig. 3 a top view of the first embodiment of the filter. Fig. 4 a sectional view through the busbars and the circuit board in the region of a magnetic element of the first embodiment. Fig. 5 a view of a first side of a circuit board of the first embodiment of a filter. Fig. 6 a view of a second side of a circuit board of the first embodiment of a filter. Fig. 7 a first exploded view of the first embodiment of the filter with the circuit board, the busbars and the magnetic elements. Fig. 8 a first exploded view of the first embodiment of the filter with the filter and its housing. Fig. 9 a circuit of a second embodiment of a filter. Fig. 10 a three-dimensional view of the second embodiment of the filter. Fig. 11 a three-dimensional view of the second embodiment of the filter before assembly of PCB, busbars and magnetic element. Fig. 12 a first side view of the second embodiment of the filter. Ways to implement the invention

[0017] Fig. Figures 1 to 8 show a first embodiment of a filter according to the invention. The filter comprises a circuit board 5 with electrical components. Electrical components of the filter comprise a first busbar 1, a second busbar 2, at least one capacitor, and at least one magnetic element.

[0018] The circuit board 5 is a plate made of an electrically insulating material with conductor tracks for connecting the electrical components of the filter. The circuit board 5 has a first side and a second side opposite the first side. The circuit board 5 preferably has at least one lateral side that is or are arranged at right angles to the normal of the circuit board plane (plane of the first and second sides). The circuit board 5 preferably has four lateral sides. The circuit board 5 preferably has one or more recesses and / or projections 5.1 on the at least one lateral side in order to plug and hold the at least one magnetic element onto the circuit board 5.

[0019] The at least one magnetic element is arranged in a ring shape around the first and second busbars 1 and 2 and, in the first exemplary embodiment, forms a current-compensated choke with the first and second busbars 1, 2. Ring-shaped means that the magnetic element forms a complete or at least a large part of a closed curve around the first and second busbars 1 and 2, so that the magnetic element forms a current-compensated choke with the two busbars 1 and 2 and the two busbars 1 and 2 are guided through the ring opening formed by the magnetic element. The closed curve preferably forms a circle (torus), but in other examples can also be rectangular, square, n-sided (polygonal) or shaped in some other way. In the case of a torus (bagel-shaped), the cross-section of the circumferential torus bead is preferably rectangular.This facilitates the attachment of the annular magnetic element to a projection 5.1 of the circuit board 5. The magnetic element preferably forms a closed ring. However, the magnetic element can also form a non-closed ring or a ring consisting of several sub-sectors (e.g., two half-toroids).

[0020] In the first embodiment, the at least one magnetic element comprises two magnetic elements 4.1 and 4.2. These are preferably identically designed and / or mounted in an identical manner on the circuit board 5. These two magnetic elements 4.1 and 4.2 are preferably arranged on opposite lateral sides of the circuit board 5. The two busbars 1 and 2 preferably extend generally along a longitudinal axis through both annular openings of the two magnetic elements 4.1 and 4.2.

[0021] The at least one capacitor is electrically connected to the first and second busbars 1 and 2 via the conductor tracks of the circuit board 5. Each of the at least one capacitor is electrically connected to the circuit board 5 using one of the known mounting methods. Preferably, the through-hole mounting (THT) commonly used in power electronics is used, although surface-mounted mounting techniques such as SMD or other mounting techniques are also possible.

[0022] In the first embodiment, the at least one capacitor comprises a current capacitor 3.1 (also called X capacitor) connected between the first busbar 1 and the second busbar 2, as is shown for example in the circuit in Fig. 1. In the embodiment with two magnetic elements 4.1 and 4.2, the current capacitor 3.1 is preferably contacted between the two magnetic elements 4.1 and 4.2 with the first and second busbars 1 and 2. Alternatively or additionally, the at least one capacitor comprises a first ground capacitor 3.21 connected between the first busbar 1 and a ground 7 and / or a second ground capacitor 3.22 connected between the second busbar 2 and the ground 7, as shown for example in the circuit in Fig. 1. In the exemplary embodiment with two magnetic elements 4.1 and 4.2, the ground capacitors 3.21 and 3.22 are preferably contacted between the two magnetic elements 4.1 and 4.2 with the first and second busbars 1 and 2. Each functional capacitor, such as the current capacitor 3.1 and the ground capacitors 3.21 and 3.22, can itself consist of several connected individual capacitor units, each of which is individually connected to the circuit board 5. As a rule, the capacitor units of a functional capacitor are connected in parallel via the conductor tracks of the circuit board 5. However, for very high currents, a serial chaining of the capacitor units is also conceivable. In the exemplary embodiment in Fig. 2 and Fig. 3, the earth capacitors 3.21 and 3.22 and the current capacitor, for example, each consist of two capacitor units connected in parallel.

[0023] Fig. Figure 1 shows a first embodiment of a filter; however, many other filter circuits comprising at least one capacitor and at least one magnetic element are possible. Preferably, the filter is a passive filter. Preferably, the filter is an EMI or EMC filter. The filter is preferably designed for a power range greater than 500W and / or a current range greater than 50A.

[0024] The first busbar 1 and the second busbar 2 are made of an electrically conductive, preferably metallic, material. The busbars 1 and 2 are rigid (unlike flexible cables and wires). The first busbar 1 is attached to the first side of the circuit board 5 and the second busbar 2 to the second side of the circuit board 5, so that the first and second busbars 1 and 2 are electrically insulated from one another by the insulating circuit board 5 and there is no risk of a short circuit. The busbars 1 and 2 are designed to conduct the system current. This is preferably a direct current. The cross-sectional area of ​​each current conductor 1 and 2 is preferably at least ten square millimeters, preferably at least 20 square millimeters.

[0025] The first busbar 1 and the second busbar 2 each have a first end and a second end, each end having a connection terminal 1.1, 2.1. Preferably, the cross-section of the busbars is rectangular, perpendicular to the current direction. This is one way to achieve a flat support surface for the respective busbar 1 and 2 on the flat circuit board 5. Preferably, the ends of the busbars 1 and 2 with the connection terminals 1.1 and 2.1 protrude beyond the lateral sides of the circuit board 5, so that the filter can be easily connected to cables or plugs or other connections of a vehicle's electrical network. Preferably, the filter further comprises a housing (not shown in the figures) which encloses (preferably all) the electronic components of the filter, wherein the four ends of the two busbars 1 and 2 with the four connection terminals 1.1 and 2.1 protrude from the housing.

[0026] In one embodiment, the busbars 1 and 2 are each fastened to the circuit board 5 with fastening means 6, such as screws, threaded pins, clamps, rivets, printed circuit board inserts (PCB inserts), soldering pads or other fastening means.

[0027] In one exemplary embodiment, the attached first busbar 1 rests directly on the first side of the printed circuit board 5. This has the advantage that the printed circuit board 5 rests on the printed circuit board 5 with a large surface area, thus allowing a stable connection even in the event of strong vibrations. The cross-section of the first busbar 1 is preferably perpendicular to the current flow direction or to the longitudinal axis of the first busbar 1 such that it forms a flat contact surface with the first side of the printed circuit board 5. The cross-section of the first busbar 1 is preferably perpendicular to the current flow direction or to the longitudinal axis of the first busbar 1, with one of the four sides forming the contact surface. This contact surface of the first busbar 1 is in physical contact with the printed circuit board 5 when attached to the printed circuit board 5, i.e., it touches the printed circuit board 5.This contact area between the first busbar 1 and the circuit board 5 preferably extends in the direction of current flow over at least 30%, preferably at least 40%, preferably at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80% of the length of the circuit board 5 and / or the length of the first busbar 1 projected onto the circuit board 5. The attached second busbar 2 also lies directly on the second side of the circuit board 5 and the previous descriptions regarding the support of the first busbar 1 on the first side of the circuit board 5 also apply to the support of the second busbar 2 on the second side of the circuit board 5.

[0028] The first side of the circuit board 5 preferably has a first conductor track area 10.1 in the region of the contact area with the first busbar 1. This allows a large-area electrical contact to be created between the first busbar 1 and the circuit board 5. This first conductor track area 10.1 is preferably formed parallel to the circuit board plane. The first conductor track area 10.1 preferably covers at least 10%, preferably at least 20%, at least 30%, preferably at least 40%, preferably at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90% of the contact area between the first busbar 1 and the circuit board 5. As a result, the first busbar 1 behaves like a conductor track on the circuit board 5. Fig. 6 and Fig. 7 show the first side of the printed circuit board 5 and the conductor track area 10.1 under the first busbar 1. The electrical contact and / or the mechanical fastening can be created by a soldered connection. Alternatively or additionally, the electrical contact can also be established by pressure caused by the fastening means 6 from the first busbar 1 to the first side of the printed circuit board 5. Preferably, the fastening means 6 are arranged in the printed circuit board 5 in the region of the contact area with the first busbar 1 or in the region of the first conductor track area 10.1, so that the fastening means 6 press the first busbar 1 onto the first conductor track area 10.1. The first conductor track area 10.1 can also consist of a plurality of separate first conductor track areas, e.g. if the first busbar 1 has different connection points, e.g. before and after the magnetic element.For the same reason, the second side of the printed circuit board 5 has a second conductor track area 10.2 in the region of the contact surface with the second busbar 2 (see . Fig. 5). The second conductor track area 10.2 has, with respect to the second busbar 2 and the second side of the printed circuit board 5, the corresponding features as the first conductor track area 10.1 with respect to the first busbar 1 and the first side of the printed circuit board 5.

[0029] Alternatively or additionally, the fastening means 6 electrically contact the busbars 1 and 2 with corresponding conductor tracks of the circuit board 5. This can be achieved, for example, by designing the recesses or threads of the circuit board 5 for the fastening means 6 with an electrically conductive, e.g., metallic, surface that is connected to the corresponding conductor track. This creates a sufficiently large and stable contact surface between the conductor track and the corresponding busbar 1, 2. However, other contact means, such as contact surfaces parallel to the circuit board plane and / or soldered contacts, are also possible.

[0030] In one exemplary embodiment, the busbars 1 and 2 are each designed to run in opposite directions in a meandering shape, so that the busbars 1 and 2 are spaced apart at different distances from one another in different regions. Preferably, the distance between the first busbar 1 and the second busbar 2 is smaller in the region of the at least one magnetic element than in the region of the fastening means 6, particularly when the fastening means 6 extend through the circuit board 5 to the other side and there is a risk of a spark or short circuit between the fastening means 6 electrically connected to one busbar 1 or 2 and the other busbar 2 or 1. Preferably, the distance between the first busbar 1 and the second busbar 2 is smaller in the region of the at least one magnetic element than in the region of the ends of the busbars 1 and 2 that protrude beyond the circuit board 5.This is particularly advantageous because in this area, busbars 1 and 2 are no longer insulated from each other by the circuit board 5, thus requiring a larger safety distance. Preferably, busbars 1 and 2 are identical; if they are meandering in opposite directions, they can simply be arranged on the circuit board 5 rotated by 180° to achieve the opposite direction.

[0031] Fig. Figure 4 shows a section through a portion of the circuit board 5, the first busbar 1, and the second busbar 2 in the region of the magnetic element (in its ring opening). Preferably, the first and second busbars 1 and 2 are arranged on the circuit board 5 such that the projections of the busbars 1 and 2 onto the circuit board 5 at least partially overlap. This allows the ring opening to be made smaller, and the magnetic element can be made smaller and thus lighter.

[0032] Fig. Figure 8 shows a housing 9 of the filter. Preferably, the circuit board 5 has at least one ground conductor surface 7. In Fig. 8, four ground conductor surfaces 7 are arranged in the four corners of the circuit board 4. These ground conductor surfaces 7 can be arranged on the first side and / or on the second side of the circuit board 5. The at least one ground conductor surface 7 defines the ground potential of the filter on the circuit board 5. The ground conductor surface 7 is connected to the metallic housing 9. This is advantageously achieved via at least one ground potential surface 8 in the housing 9, which, when the housing 9 is assembled, presses against the at least one ground conductor surface 7 and thus creates the ground connection to the housing 9. This eliminates the need for a ground connection to the housing via an additional cable. Preferably, a fastening recess extends through the at least one ground conductor surface 7 and / or the at least one ground potential surface 8. This allows a good ground connection to be achieved simply by fastening the circuit board 5 to the housing 9.Preferably, the housing 8 has a first shell for covering the first side of the circuit board 5 and a second shell for covering the second side of the circuit board 5. The two shells each have a fastening recess in the region of the at least one ground conductor surface 7 and / or the at least one ground potential surface 8. As a result, the circuit board 5 can be pressed together in the region of the at least one ground conductor surface 7 between the first shell and the second shell by means of a screw connection.

[0033] Fig. Figures 9 to 12 show a second embodiment of a filter according to the invention. The filter comprises a printed circuit board 15 with electrical components. Electrical components of the filter comprise a first busbar 11, a second busbar 12, at least one capacitor 13, and at least one magnetic element 14. Unless explicitly stated otherwise, the description of the printed circuit board 5 and the electrical components of the first embodiment also applies to the printed circuit board 15 and the electrical components of the second embodiment.

[0034] Fig.Figure 9 shows a circuit diagram for the second embodiment. Here, the filter is implemented as an active filter. The active filter comprises a current transformer 23, an amplification circuit 24, and a capacitor 13. The active filter is preferably an EMI or EMC filter. The filter is preferably designed for a power range greater than 500W and / or a nominal current greater than 50A.

[0035] The current transformer 23 converts the alternating interference currents of the first and second busbars 11 and 12 into a measuring current in the auxiliary winding 27. For this purpose, the magnetic element 14 couples the first and second busbars 11 and 12 to the auxiliary winding 27. For this purpose, the magnetic element is preferably arranged in a ring around the first and second busbars 1 and 2, as described in the first exemplary embodiment. The current transformer 23 preferably forms a current-compensated common-mode current transformer. The auxiliary winding 27 can be designed as a conductor track on the printed circuit board 15. However, it is also possible to implement the auxiliary winding as a wire that is connected to the printed circuit board 15 or to one of the electrical components of the printed circuit board 15.

[0036] The amplification circuit 24 generates the compensation current or the compensation voltage based on the alternating currents measured in the current transformer.

[0037] The capacitor 13 is designed to input the compensation current or voltage to the first busbar 11 and the second busbar 12, respectively, in order to cancel the alternating interference currents or voltages of the first busbar 11 and the second busbar 12 at least within the bandwidth of the active filter. As described in the first embodiment, the two capacitors 13 are each mounted on the circuit board 15 and connected to the first busbar 11 or the second busbar 12 by means of conductor tracks.

[0038] As in the first embodiment, the first busbar 11 is attached to the first side of the circuit board 15 and the second busbar 12 is attached to the second side of the circuit board 15, so that the first and second busbars 11 and 12 are electrically insulated from each other by the insulating circuit board 15 and there is no risk of a short circuit.

[0039] The first busbar 11 and the second busbar 12 each have a first end and a second end, each end having a connection terminal. Preferably, the cross-section of the busbars is rectangular at right angles to the current direction. This is one way to achieve a flat support surface for the respective busbar 11 and 12 on the flat circuit board 15. Preferably, the ends of the busbars 11 and 12 with the connection terminals protrude beyond the lateral sides of the circuit board 15 so that the filter can be easily connected to cables or plugs or other connections of a vehicle's electrical network. Preferably, the filter further comprises a housing (not shown in the figures) which encloses (preferably all) the electronic components of the filter, wherein the four ends of the two busbars 11 and 12 with the four connection terminals protrude from the housing.

[0040] In one embodiment, the busbars 11 and 12 are each fastened to the circuit board 15 using fastening means such as screws, threaded pins, clamps, rivets, circuit board inserts, solder joints, or other fastening means. The embodiments for fastening and contacting the busbars 11 and 12 with the circuit board 15 are as in the first embodiment.

[0041] In one embodiment, the busbars 11 and 12 are designed such that the busbars 11 and 12 have different distances from one another in different areas. Preferably, the distance between the first busbar 11 and the second busbar 12 is smaller in the area of ​​the magnetic element than in the area of ​​the ends of the busbars 11 and 12 protruding beyond the circuit board 15. This is particularly advantageous because in this area the busbars 11 and 12 are no longer insulated from one another by the circuit board 15 and thus a larger safety distance is required. Preferably, the distance between the busbars 11 and 12 in the area of ​​the magnetic element, in particular in the opening of the toroidal core 14, is minimal. The busbars 11 and 12 are preferably identical and can be arranged rotated by 180° on the circuit board 15 in order to achieve the different distances.In contrast to the first embodiment, the different distance is realized by a larger distance from the circuit board plane of the circuit board 15, while in the first embodiment the larger distance is achieved by a lateral arrangement in the circuit board plane.

[0042] The first busbar 1 and the second busbar 2 completely overlap in the area of ​​the magnetic element (in its ring opening), whereas in the first embodiment, there is only a partial overlap. However, it is also possible to realize a complete overlap in the first embodiment and only a partial overlap in the second embodiment.

[0043] The filter according to the invention makes it possible to achieve a small and lightweight filter of high quality, the design and dimensions of which can be used for a wide range of voltages, currents and / or powers.

Claims

[1] Electromagnetic interference filter comprising: a printed circuit board (5, 15) with conductor tracks, with a first side and with a second side opposite the first side, a first bus bar (1, 11) mounted on the first side of the circuit board (5, 15) and electrically connected to at least one of the conductor tracks; a second busbar (2, 12) mounted on the second side of the circuit board (5, 15) and electrically connected to at least one of the conductor tracks; and at least one capacitor which is or are connected to the first and / or second busbar (1, 2; 11, 12) via the conductor tracks; wherein the printed circuit board (5, 15) is arranged between the first busbar (1, 11) and the second busbar (2, 12) for their insulation, characterized by at least one magnetic element (4.1, 4.2, 14) which is arranged in a ring around the first and second busbars (1, 2; 11, 12), wherein at least in the region of the at least one magnetic element, the circuit board (5, 15) is arranged between the first busbar (1, 11) and the second busbar (2, 12) for the purpose of insulating them. [2] Filter according to claim 1, wherein the first and the second busbar (1, 2; 11, 12) are each mechanically fastened to the circuit board (5, 15) by fastening means (6) leading through the circuit board (5, 15), wherein the fastening means (6) form a conductive connection between the corresponding conductor track of the circuit board (5) and the busbar (1, 2). [3] Filter according to claim 1 and 2, wherein the distance between the first busbar (1) and the second busbar (2) in the region of the fastening means (6) is greater than in the region of the at least one magnetic element. [4] Filter according to claim 2 or 3, wherein the at least one capacitor comprises a current capacitor (3.1) connected between the first and second busbars (1, 2). [5] Filter according to one of claims 2 to 4, wherein the at least one capacitor comprises a first ground capacitor (3.21) connected between the first busbar (1) and the ground (7), and optionally a second ground capacitor (3.22) connected between the second busbar (2) and the ground (7). [6] Filter according to one of claims 2 to 5, wherein the at least one magnetic element (4.1, 4.2, 14) is in each case designed as a magnetic toroidal core which is plugged onto a projection (5.1) of the printed circuit board (5), wherein the first and second busbars (1, 2) on the opposite first and second sides of the printed circuit board (5) are guided through the ring opening of the magnetic toroidal core. [7] Filter according to one of claims 2 to 6, wherein the at least one magnetic element (4.1, 4.2) forms a current-compensated choke with the first and second busbars (1, 2). [8] Filter according to one of claims 1 to 7, wherein the at least one magnetic element comprises two magnetic elements (4.1, 4.2), wherein the at least one capacitor (3) is connected between the two magnetic elements (4.1, 4.2) to the first and / or second busbar (1, 2). [9] Filter according to one of claims 2 to 6, wherein the filter is an active filter. [10] Filter according to claim 9, wherein the at least one magnetic element (14) forms a current transformer with the first and second busbars (11, 12) to convert interference currents in the first and second busbars (11, 12) into a measuring current in an auxiliary winding (27). [11] The filter of claim 9 or 10, wherein the at least one capacitor comprises a first coupling capacitor (13) for inputting a compensation current generated on the basis of a measuring current to the first bus bar (11), and a second coupling capacitor (13) for inputting the compensation current to the second bus bar (12). [12] Filter according to one of claims 2 to 11, wherein the first and second busbars (1, 2, 11, 12) each have a first end with a first connection terminal (1.1, 2.1) and a second end with a second connection terminal (1.1, 2.1), wherein the first end and the second end of the first and second busbars (1, 2; 11, 12) each protrude beyond the circuit board (5). [13] Filter according to claim 12, wherein the distance between the first busbar (1, 11) and the second busbar (2, 12) is greater in the region of the first and / or second ends than in the region of the at least one magnetic element (4.1, 4.2, 14). [14] Filter according to claim 12 or 13, wherein the first busbar (1, 11) and the second busbar (2, 12) are insulated from each other continuously by the printed circuit board (5, 15) except in the region of the projecting first and second ends. [15] Filter according to one of claims 1 to 14, wherein the first busbar (1, 11) and the second busbar (2, 12) rest with a contact surface directly on the printed circuit board (5, 15). [16] Filter according to claim 15, wherein the printed circuit board (5, 15) has on the first side in the region of the contact surface with the first busbar (1, 11) a first conductor track surface (10.1) which establishes an electrical contact between the first busbar (1, 11) and the first conductor track surface (10.1) and the printed circuit board (5, 15) has on the second side in the region of the contact surface with the second busbar (2, 12) a second conductor track surface (10.2) which establishes an electrical contact between the second busbar (2, 12) and the second conductor track surface (10.2). [17] Filter according to one of claims 1 to 16, wherein the filter comprises a metallic housing (9), wherein the housing (9) has at least one ground potential surface (8), wherein the printed circuit board (5, 15) has at least one ground conductor surface (7), wherein each of the at least one ground potential surface (8) of the housing (9) is pressed by fastening means onto a corresponding ground conductor surface (7) and thus an earth connection is created from the printed circuit board (5) to the housing (8). [18] Filter according to one of claims 1 to 17, wherein the filter is designed for a power range greater than 500 watts and / or for a current range greater than 50A. [19] Vehicle with a direct current electrical network and a filter according to one of claims 1 to 18 connected to the direct current electrical network. [20] A vehicle according to claim 19, wherein the vehicle is powered by an electric motor for locomotion.

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