COMMON MODE CHOKE

Description

State of the art

[0001] The invention relates to a common-mode choke. The common-mode choke has a particularly magnetically permeable, particularly circular-ring-shaped toroidal core. The common-mode choke also has at least one coil and at least one additional coil. The coil and the additional coil are each arranged in the region of the toroidal core in such a way that a magnetic flux passing through the coils can capture the toroidal core.

[0002] Common-mode chokes are used for EMC (electromagnetic compatibility) suppression. For this purpose, common-mode chokes have at least two or just two coils that can interact magnetically with each other via a toroidal core. The coil current in the two coils is preferably directed in opposite directions, so that EMC interference in the toroidal core is magnetically canceled out.

[0003] DE 10 2016 223195 shows a transformer that can also be used as a choke, with primary windings consisting of cup-shaped windings. DE 42 21 769 shows a common-mode choke manufactured by soldering segment-shaped inner and outer conductors. Disclosure of the invention

[0004] According to the invention, the toroidal core encloses a particularly cylindrical aperture. The coils comprise at least one or only one electrical inner conductor, in particular a busbar, for each coil turn. The inner conductor is arranged in the aperture, with the coil turn having an outer conductor electrically connected to the inner conductor. The outer conductor forms a cylindrical shell section, in particular a cylindrical shell segment. The outer conductor is designed to enclose a peripheral section of the toroidal core. Claim 1 specifies the invention; it is based, in particular, on a closure cover for closing off the cavity in which the toroidal core is located.

[0005] This allows the common-mode choke to be designed particularly compactly and cost-effectively with a high inductance. Furthermore, the common-mode choke can be designed with low resistance for high-current applications, especially with a current flow of several hundred amperes. It has been recognized that the impedance of a common-mode choke can be effectively increased if the cross-sectional area of ​​the aperture can be fully energized by the inner conductors.

[0006] The circumference of the toroidal core preferably extends along a ring-shaped perimeter around the aperture. The toroidal core is preferably circular, more preferably hollow-cylindrical.

[0007] In a preferred embodiment, the inner conductors arranged in the opening together form a cylinder and jointly fill the opening. The inner conductors preferably each have a cross-section shaped like a segment of a circle. In an embodiment with only one turn for one of the two coils, in particular a positive coil and a negative coil, the common-mode choke can thus have an inner conductor which is semi-cylindrical and semicircular in cross-section. In an embodiment in which each coil has two turns or partial turns, the common-mode choke can have an inner conductor for each turn or partial turn which is shaped like a quarter-segment of a cylinder or a quarter-segment of a circle in cross-section. The opening can thus advantageously be designed with a particularly small opening cross-section to produce a high inductance of the common-mode choke.The common mode choke can thus be provided in a particularly space-saving manner.

[0008] The inner conductors are preferably each designed as a straight bar. Advantageously, the inner conductors can be provided cost-effectively using an extruded profile or a rolled profile and by cutting them from a bar.

[0009] In a preferred embodiment, the coils each have only one coil turn or partial coil turn, and the outer conductors, or additionally the inner conductors, are semicircular in cross-section. Advantageously, the inner conductors of the coil and the additional coil can jointly fill the aperture completely or almost completely—preferably with the exception of an insulation gap. The outer conductors can advantageously enclose the toroidal core completely or almost completely, preferably with the exception of an insulation gap. The insulation gap can be filled with air or an insulator, preferably plastic or ceramic. The insulator is preferably formed by the holding body.

[0010] In a preferred embodiment, the coils each have two coil turns or partial coil turns. The outer conductors and / or the inner conductors are each designed with a quarter-circle segment shape in cross-section. Advantageously, a common-mode choke with two coil turns or partial turns can thus have a high inductance, since the inductance of a common-mode choke increases quadratically with the number of turns.

[0011] In a preferred embodiment, the common-mode choke has an electrically insulating holding body, in particular a plastic or ceramic body. The plastic body extends at least between adjacent outer conductors or additionally between two adjacent inner conductors. The holding body preferably extends between two adjacent coil windings. As a result, the individual coil windings are advantageously electrically insulated from one another.

[0012] The holding body, in particular a plastic body or ceramic body, preferably encloses an annular cavity for receiving the toroidal core, which is designed to accommodate the toroidal core. Advantageously, the common-mode choke can thus be provided in a cost-effective and space-saving manner. The plastic body can, for example, be provided together with the outer conductors and the inner conductors using an injection molding process by overmolding the outer and inner conductors. The inner conductor and the outer conductor, and a connecting section connecting the inner conductor and the outer conductor, thus together form a coil turn or partial coil turn.

[0013] A coil turn preferably extends along a complete winding circuit around a coil core, in particular the toroidal core. A partial coil turn preferably extends along a partial circuit around the coil core, in particular the toroidal core. It has been recognized that partial coil turns that have at least one inner conductor can also contribute significantly to the inductance formation of the choke coil.

[0014] In a preferred embodiment, the holding body has an insulating layer or an insulating material designed to electrically insulate the outer conductors and / or the inner conductors from the toroidal core. The insulating layer preferably forms an insulating jacket surrounding the toroidal core. Advantageously, the common-mode choke can thus be designed to be voltage-resistant, in particular high-voltage-resistant. A high voltage, particularly for automotive applications, such as electric vehicle or hybrid vehicle applications, is, for example, between a few hundred volts and a thousand volts.

[0015] In a preferred embodiment, the outer conductor of a coil winding is connected to the inner conductor via a connecting section, wherein the connecting section is configured as a circular segment. Thus, a surface region of the toroidal core can advantageously also be enclosed by a coil winding or coil partial winding, which extends between the opening wall region and a radially outwardly facing outer surface of the toroidal core. The surface region is preferably circular and has a circular surface extending between a diameter of the opening and an outer diameter of the toroidal core.

[0016] Preferably, the turns or partial turns of the coil and the additional coil, when joined together to fill the aperture and / or to enclose the toroidal core, form a cup shape. The aforementioned connecting section forms a cup base, the outer conductors form an outer cup wall, and the inner conductors form a cylinder or pin, which extends, in particular, centrally from the cup base into the cavity enclosed by the outer conductors and thus the cup wall. Preferably, an insulating gap or an insulating material, in particular a plastic material, extends between the coil turns.

[0017] The partial winding is preferably U-shaped in section. Further preferably, the inner conductor and the outer conductor each form a U-shaped leg, with the connecting section forming a U-shaped base connecting the U-shaped legs.

[0018] In a preferred embodiment, the outer conductor and a connecting section formed thereon form a can segment, with the connecting section forming a can base segment. The can segments of all coil windings of the common-mode choke can thus collectively form a type of can. The can is preferably designed to accommodate the toroidal core.

[0019] In a preferred embodiment, the outer conductors and / or the inner conductors each have a molded-on soldering foot for soldering to a circuit carrier. Advantageously, the common-mode choke can thus be soldered to a circuit carrier using surface mounting, in particular SMD (surface-mounted device) mounting, for example, in a reflow soldering oven.

[0020] In a preferred embodiment, the solder pads each have a contact surface, with the contact surfaces being arranged in a common connection plane. Advantageously, the common-mode choke can thus be reflow soldered to a flat circuit carrier.

[0021] The circuit carrier is preferably an IMS circuit carrier (IMS = Insulated Metal Substrate), DCB circuit carrier (DCB = Direct Copper Bonded), AMB circuit carrier (AMB = Active Metal Brazed), LTCC circuit carrier (LTCC = Low Temperature Cofired Ceramics) or an HTCC circuit carrier (HTCC = High Temperature Cofired Ceramics).

[0022] The invention will now be described below with reference to figures and further exemplary embodiments. Further advantageous embodiments will become apparent from a combination of the features described in the figures and in the dependent claims. Figure 1shows an embodiment of a common-mode choke in which coil windings each comprise an inner conductor, the inner conductors together filling the opening of a toroidal core of the common-mode choke; Figure 2 shows a view of the Figure 1 shown common mode choke, in which the coil windings together form a cup in which the toroidal core can be accommodated; Figure 3 shows the Figures 1 and 2 shown common mode choke, in a plan view of the cavity in which the toroidal core can be accommodated; Figure 4 shows a diagram in which a current flow through the coil turns of the coil and an opposite current flow through the coil turns of the other coil are shown.

[0023] Figure 1shows an exemplary embodiment of a common-mode choke 1 in a sectional view. The common-mode choke 1 has a toroidal core 2, which is particularly magnetically permeable. The toroidal core 2 is made of ferrite, for example, and has an opening 20. The common-mode choke 1 also has a coil winding 3 of a first coil and a coil winding 4 of a second coil.

[0024] In this exemplary embodiment, the coil winding 3 comprises an outer conductor 5 and an inner conductor 7, which are each connected to one another via a connecting section 13. The coil winding 3 is formed in one piece in this exemplary embodiment. The coil winding 4 comprises an outer conductor 6 and an inner conductor 8, which are each electrically connected to one another via a connecting section 14. The outer conductors 6 and 5 each form a part, in particular a segment, of a cylinder wall of a hollow cylinder. The connecting sections 13 and 14 each form a base segment of a cup segment formed by the coil windings 3 and 4.

[0025] The coil windings 3 and 4 each form in the Figure 1The longitudinal section shown has a U-shape, with the U-shape comprising an outer conductor and the inner conductor connected to the outer conductor via the connecting section each forming a U-leg. The connecting section 13 or 14 forms a U-shaped base.

[0026] The inner conductors 7 and 8, together with a separating web 10 enclosed between the inner conductors 7 and 8, form a column or a pin that extends into an opening in the toroidal core 2. The pin thus formed is integrally formed on the can base, formed by the connecting sections 13 and 14, and extends, in particular, centrally in a cavity 12 enclosed by the outer walls 5 and 6. The cavity 12 is designed as a hollow cylinder such that a hollow cylinder-shaped toroidal core, such as the toroidal core 2, can be accommodated in the cavity 12. The common-mode choke 1 also has a holding body, which in this exemplary embodiment is made of plastic, in particular injection-molded plastic. The holding body comprises the aforementioned separating web 10 and an insulating layer 9 lining the inner wall of the can.The insulating layer 9 extends radially circumferentially on an inner side of the outer wall of the cup, on the cup bottom, and on an outer wall facing the cavity 12 of the inner conductors forming the aforementioned pin, in particular the inner conductors 6 and 7.

[0027] In this embodiment, the toroidal core 2 is attached to the cup bottom by means of adhesive 15.

[0028] The common-mode choke 1 is designed to be connected to a circuit carrier by surface soldering. For this purpose, soldering feet are molded onto the U-shaped legs, in particular the outer conductors and the inner conductors of the coil windings, the contact surfaces of which are arranged in a common plane, in particular a connection plane for soldering to a circuit carrier. The coil winding 3 has a soldering foot 28 molded onto the outer conductor 5 with a contact surface 42 and a soldering foot 30 molded onto the inner conductor 7 with a contact surface 44. The coil winding 4 has a soldering foot 27 molded onto the outer conductor 6 with a contact surface 41 and a soldering foot 29 molded onto the inner conductor 8 with a contact surface 43.

[0029] Figure 1 also shows a cover 16, which is part of the common mode choke 1.

[0030] The closure cover 16 is designed to close the cavity 12, particularly after the toroidal core 2 has been inserted into the cavity 12. For this purpose, the closure cover 16 is designed to extend flat and is annular, and has an opening through which the aforementioned pin enclosing the inner conductors can be passed. The closure cover 16 can be placed on a support shoulder formed by the insulating layer 9. The cavity 12 of the common-mode choke 1 can thus be protected from the ingress of dirt or moisture.

[0031] Figure 1also shows a circuit carrier 21, which is designed to be soldered to the common-mode choke. The circuit carrier 21 can form a contact system together with the common-mode choke. The circuit carrier is designed to electrically connect the coil windings of the same coil to one another. The circuit carrier is, for example, an IMS circuit carrier, DCB circuit carrier, AMB circuit carrier, LTCC circuit carrier, or an HTCC circuit carrier.

[0032] Figure 2 shows the Figure 1 The common mode choke shown above is particularly seen from the side. Shown is a section line 19, which Figure 1 represented sectional view.

[0033] In this exemplary embodiment, the common-mode choke 1 comprises four galvanically isolated coil windings. In this exemplary embodiment, each of the coil windings forms a can segment, in particular a can quarter segment. Partitions or separating webs for electrically isolating the can segments from one another are formed between the can segments—in this exemplary embodiment by means of plastic injection molding. A partition 10 in this exemplary embodiment forms a can bisector along a longitudinal axis 40, thus electrically insulating opposite can segments from one another. A further separating web 11, which forms a can bisector, is designed to electrically insulatingly separate two can halves comprising two can segments from one another. In this exemplary embodiment, the partitions 10 and 11 are arranged perpendicular to one another.Coil winding 3 extends between the partition walls 10 and 11, and opposite it is coil winding 4. Transversely to the opposing coil windings 3 and 4, a coil winding 17 and a coil winding 18 are arranged opposite one another between the cup wall 11 and the cup wall 10. Along a radial circumference around the toroidal core 2 and around the longitudinal axis 40, coil winding 3 is separated by the partition wall 10 and followed by coil winding 17. Coil winding 17 is separated from coil winding 4 by the partition wall 11 along the radial circumference. Coil winding 18 is arranged adjacent to coil winding 4 along the radial circumference, separated by the partition wall 10.

[0034] The connecting section 13 of coil winding 3, the connecting section 14 of coil winding 4, a connecting section 25 of coil winding 17, and a connecting section 26 of coil winding 18 together form a can bottom of the can formed by the coil windings. The outer conductors 5, 6 and an outer conductor 22 of coil winding 17, as well as an outer conductor of coil winding 18, together form a can wall, which encloses the cavity 12 for accommodating the toroidal core 2.

[0035] Soldering feet are formed on the outer conductors, wherein a soldering foot 28 is formed on the outer conductor 5 of the coil winding 3, a soldering foot 27 formed on the outer conductor 6 of the coil winding 4, and a soldering foot 31 formed on the outer conductor 22 of the coil winding 17 are designated by way of example. The outer conductors each have, for example, at least one, two, or as in Figure 2 As shown, it has three soldering feet.

[0036] Figure 3 shows the Figures 1 and 2 The previously described common-mode choke 1 in a top view of the soldering feet and the cavity 12. The partition walls 10 and 11 are arranged so as to cross one another and form a right angle between them. The coil windings 3, 17, 4 and 18, which are arranged radially around the vertical axis 40, each form a quarter-circle segment. The insulating layer 9 of the holding body, which is formed onto the partition walls 10 and 11, encompasses an annular cavity for receiving the Figure 1 shown toroidal core 2.

[0037] The insulating layer 9 thus forms a kind of toroidal trough, which electrically insulates the toroidal core 2 from the outer conductors 3, 17, 4 and 18, and from the inner conductors 7, 8, 35 and 36.

[0038] The inner conductor 35 is part of the coil winding 17, and the inner conductor 36 is part of the coil winding 18. The coil winding 18 has an outer conductor 33, which is connected by means of the Figure 2 shown connecting element 26 as a cup bottom segment is connected to the inner conductor 36.

[0039] The inner conductors 7 and 8 are separated by the partition walls 10 and 11, which also extend between the inner conductors, and lie opposite each other. The partition wall 10 forms a central web 23 in the area between the inner conductors. The partition wall 11 forms a central web 24 in the area between the inner conductors. The central webs 23 and 24 together form a kind of cross and intersect at the center of the common-mode choke. The center, in particular a center of a rotationally symmetrical design of the common-mode choke 1, is formed by the longitudinal axis 40.

[0040] The inner conductors 35 and 36 are opposite each other, separated by the partition walls 10 and 11.

[0041] The solder pads 27, 28, 31, 32 of the outer conductors and the solder pads 29, 30, 37, and 38 of the inner conductors each have contact surfaces arranged coplanar with one another. Thus, the inner conductors and the solder pads can be jointly soldered to a circuit carrier, in particular a ceramic circuit carrier.

[0042] To form a coil of the common-mode choke 1 comprising two coil turns, an inner conductor, for example the inner conductor 7, can be soldered to an electrically conductive layer of a circuit carrier via the soldering foot 29. The electrically conductive layer then connects the soldering foot 29 to the outer conductor, which is arranged directly adjacent to the inner conductor 7 in the radial direction of rotation, in this exemplary embodiment to the outer conductor 22 of the coil turn 17, and there to the soldering foot 31. The coil, comprising two coil turns, then has the soldering foot 28 of the outer conductor of the coil turn 5 as a first connection, and further the soldering foot 31 of the inner conductor 35 of the coil turn 17 as a second connection.

[0043] To form the further coil of the common mode choke 1, for example, the inner conductor 9 of the coil winding 4 can be covered by means of a further electrically conductive layer of the - in Figure 1shown - circuit carrier are electrically connected to the outer conductor 33 of the adjacent coil winding 18. The currents of the inner conductors of the same coil thus flow in the same direction in the opening of the toroidal core.

[0044] Figure 4 shows a circuit diagram in which the design of the coil and the further coil of the Figures 1, 2 and 3 The coil and the further coil each comprise two turns. A coil current through the coil can flow from the soldering foot 28 of the outer conductor 5 through a first turn of the coil via the outer conductor 28, from there via the connecting section 13 to the inner conductor 7. There, a magnetic coupling is generated in the toroidal core 2. The current can be fed via a circuit carrier, for example the one shown in Figure 1The current can flow from the soldering foot 29 to the soldering foot 31 of the adjacent coil segment, shown in the circuit carrier 21. This forms a second turn of the coil. The current can flow further via the outer conductor 22, the connecting section 25 to the inner conductor 35, which thus flows through the toroidal core 2 in the same direction as the current through the inner conductor 7.

[0045] A current directed opposite to the current through the coil can flow through the additional coil, whose first coil turn is formed by the outer conductor 6, the connecting section 14, and the inner conductor 8. The second turn of the additional coil is formed by the outer conductor 33, the connecting section 26, and the inner conductor 36. The turns are each formed in one piece, for example, from copper, in particular pure copper.

[0046] EMC interference that is superimposed on the currents can thus cancel each other out in the toroidal core 2.

Claims

1. Common mode choke (1) having an in particular magnetically permeable in particular ring-shaped annular core (2) and at least one coil (5, 13, 7, 22, 25, 35) and at least one further coil (6, 14, 8, 33, 26, 36), wherein the coil (5, 13, 7, 22, 25, 35) and the further coil (6, 14, 8, 33, 26, 36) are each arranged in the region of the annular core (2) in such a way that a magnetic flux passing through the coils encompasses the annular core (2), wherein the annular core (2) encloses an in particular cylindrical aperture (20), and the coils (5, 6, 7, 8, 13, 14, 22, 25, 26, 33, 35, 36) comprise, for each coil winding (3, 4, 17, 18), at least one respective electrical inner conductor (7, 8, 35, 36), in particular a busbar, which is arranged in the aperture (20), wherein the coil winding has an outer conductor (5, 6, 22, 33) electrically connected to the inner conductor (7, 8, 35, 36), wherein the outer conductor (5, 6, 22, 33) forms a cylinder jacket portion, in particular a cylinder jacket segment, which is designed to enclose a circumferential portion of the annular core (2), characterized in that the common mode choke has a closure lid (16), wherein the in particular annular closure lid (16) is designed to close a cavity (12) into which the annular core (2) is inserted.

2. Common mode choke (1) according to Claim 1, characterized in that the inner conductors (7, 8, 35, 36) arranged in the aperture (20) together form a cylinder shape and thus conjointly fill the aperture (20), and the inner conductors (7, 8, 35, 36) each have a circular segmental cross section.

3. Common mode choke (1) according to Claim 1 or 2, characterized in that the coils (5, 6, 7, 8, 13, 14, 22, 25, 26, 33, 35, 36) each have only one coil winding (3, 4, 17, 18), and the outer conductors (5, 6, 22, 33) or additionally the inner conductors (7, 8, 35, 36) are for this purpose each semicircular in cross section.

4. Common mode choke according to Claim 1 or 2, characterized in that the coils (5, 6, 7, 8, 13, 14, 22, 25, 26, 33, 35, 36) each have two coil windings (3, 4, 17, 18), wherein the outer conductors (5, 6, 22, 33) and / or the inner conductors (7, 8, 35, 36) are for this purpose each designed with a quarter-circular segmental cross section.

5. Common mode choke (1) according to one of the preceding claims, characterized in that the common mode choke (1) has an electrically insulating holding body (9), in particular a plastic body, which extends at least between mutually adjacent outer conductors (5, 6, 22, 33), or additionally inner conductors (7, 8, 35, 36), and which encloses the annular cavity (12) for receiving the annular core (2), which annular cavity is designed to receive the annular core (2).

6. Common mode choke (1) according to Claim 5, characterized in that the holding body (9) has an insulating layer (9), which is designed to electrically insulate the outer conductors (5, 6, 22, 33) and / or the inner conductors (7, 8, 35, 36) from the annular core (2).

7. Common mode choke (1) according to one of the preceding claims, characterized in that the outer conductor (5, 6, 22, 33) of a coil winding (3, 4, 17, 18) is connected to the inner conductor (7, 8, 35, 36) via a circular segmental connection portion (13, 14, 25, 26).

8. Common mode choke (1) according to Claim 7, characterized in that the outer conductor (5, 6, 22, 33) and a connection portion (13, 14, 25, 26) moulded onto the latter form a cup segment, wherein the connection portion (13, 14, 25, 26) forms a cup bottom segment.

9. Common mode choke (1) according to Claim 7 or 8, characterized in that the outer conductors (5, 6, 22, 33) and / or the inner conductors (7, 8, 35, 36) each have a moulded-on solder foot (27, 28, 29, 30, 31, 32) for soldering to a circuit carrier (21).

10. Common mode choke (1) according to one of the preceding claims, characterized in that the solder feet (27, 28, 29, 30, 31, 32) each have a contact surface (41, 42, 43, 44), wherein the contact surfaces are arranged in a common connecting plane.