Choke arrangement, electromagnetic interference filter and method for manufacturing a choke arrangement

Abstract

The present invention relates to a choke arrangement (1) comprising a common-mode choke (2) with a core (21) and at least two windings (23) surrounding the core (21), a differential-mode inductance formed by a hardened encapsulation material (40), wherein the encapsulation material (40) surrounds the common-mode choke (2), and wherein the encapsulation material (40) has a magnetic permeability µ r >1, preferably µ r >2, exhibits.

Description

State of the art

[0001] The present invention relates to a choke arrangement, an electromagnetic interference filter with at least one of the choke arrangements and a method for manufacturing the choke arrangement.

[0002] The integration of differential-mode chokes and common-mode chokes into filters of switching converters is an established approach to reduce interference and improve the performance of electronic systems. Within the filter, these components constitute the differential-mode inductance and common-mode inductance, respectively. Previously known methods for integrating the chokes into filters include the use of separate common-mode and differential-mode chokes, as well as the integration of the differential-mode inductance into the common-mode choke. Such integration of the differential-mode inductance as a separate core component within the common-mode choke is exemplified in EP 3 683 811 A1. Disclosure of the invention

[0003] The inductor arrangement according to the invention, with the features of claim 1, has the following advantages: Compared to using common-mode and differential-mode inductance in two separate components, the inductor arrangement according to the invention offers the advantage that the effort required for an additional component can be saved, since, according to the invention, the differential-mode inductance is integrated into the common-mode inductor. Furthermore, space is saved on a printed circuit board, for example, the circuit board of a filter and its associated housing. Assembly effort is reduced because fewer components need to be mounted. Furthermore, efficiency is improved because additional resistances, which occur when using separate components, are eliminated.Compared to previously known solutions where the differential-mode inductance is already integrated into the common-mode choke, the choke arrangement described here offers the advantage that, according to the invention, there is no separate core component for the differential-mode inductance that would have to be inserted and joined separately during the assembly process. If, as is the case in the prior art, a separate core component is used as the differential-mode inductance, the air gap must be set extremely precisely, since this determines the inductance values ​​of the differential-mode inductance; this results in a very high assembly effort.If, in the prior art, an inhomogeneous air gap between the separate core component (differential-mode inductance) and the core of the common-mode choke (common-mode inductance) is not properly adjusted during the assembly process, this has negative consequences for the electromagnetic performance due to partial saturation of the common-mode choke core, since, for example, anisotropic or laminated cut-tape cores saturate in layers towards the air gap. These disadvantages of the prior art are overcome according to the invention by constructing the choke arrangement as follows: The choke arrangement comprises a common-mode choke with a core and at least two windings surrounding the core. Furthermore, the choke arrangement comprises a differential-mode inductance formed by a hardened encapsulation material. This encapsulation material surrounds the common-mode choke. According to the invention, the encapsulation material has a magnetic permeability µ. r>1, preferably µ r >2. Due to this magnetic permeability and the fact that the encasing material surrounds the common-mode choke, the encasing material can represent the differential-mode inductance. According to the invention, it is provided that a separate core component is not used as the differential-mode inductance, but rather the encasing material with a magnetic permeability of µ is used. r>1 is used. According to the invention, the differential-mode inductance is integrated, and the same windings and core material are used for the common-mode choke. This results in comparable DC resistances in the common-mode choke winding and reduces or eliminates the resistance of the differential-mode inductance. The use of the encapsulating material ensures direct contact between the differential-mode inductance and the common-mode choke, resulting in no or an evenly distributed air gap and thus reducing the risk of partial saturation due to inhomogeneous air gap reluctance. The entire choke assembly is very compact because the cavities in the design, for example, the spaces between the winding turns, can be utilized by means of the encapsulating material. The technical performance of the choke assembly is better compared to the prior art because the encapsulating material has a magnetic permeability of µ. r>1 is thermally conductive and can thus dissipate heat to the outside. Overall, compared to a separate solid core as a push-pull inductor, a higher push-pull inductance can be achieved with the solution according to the invention. As will be shown, the magnetic permeability of the encapsulation material can be easily adjusted to almost any desired value.

[0004] The dependent claims describe preferred embodiments of the invention.

[0005] Preferably, the common-mode choke is encased in the coating material. This coating material can also be referred to as potting compound.

[0006] As an alternative to encapsulating the common-mode choke with the coating material, it is preferably provided that the common-mode choke is overmolded with the coating material. This is done in particular using an injection molding process.

[0007] In both methods, casting and overmolding, a mold is used into which the common-mode choke is placed. Through casting or overmolding with the coating material, the coating material conforms to the surface of the common-mode choke and / or the windings. The outer shape and, if applicable, the segmentation of the coating material can be determined by the mold.

[0008] Furthermore, it is preferably provided that the common-mode choke is overmolded using a multi-component process, for example, a two-component injection molding process. Accordingly, it is defined that the common-mode choke is preferably overmolded with at least two components of different materials using a multi-component process, wherein the coating material constitutes one of these at least two components. At least one further component with which the common-mode choke can be overmolded is preferably an electrically insulating material, for example, plastic.

[0009] This additional component allows, for example, individual segments of the encapsulation material to be electrically separated from one another. Furthermore, this additional component also makes it possible to electrically insulate the entire choke assembly from the outside, to influence thermal management, or to provide suitable devices for attaching the choke assembly to other system components.

[0010] Preferably, the encapsulation material comprises a plastic matrix and embedded microparticles. These microparticles consist of a soft magnetic material, for example, ferrite. The magnetic permeability of the encapsulation material can be adjusted accordingly by varying the number of microparticles and the material of the microparticles.

[0011] Furthermore, it is preferably provided that the encapsulation material has a thermal conductivity of at least 0.7 W / mK, preferably at least 1 W / mK. This thermal conductivity can be adjusted, in particular, by selecting the appropriate quantity and material of the microparticles. The integration of the soft magnetic particles into the encapsulation material significantly increases its thermal conductivity. This allows the encapsulation material to be used efficiently for heat dissipation from the common-mode choke, especially from the windings. Such improved cooling allows the conductor cross-section to be reduced, resulting in a higher energy density and corresponding savings in overall material volume. With the reduced conductor cross-section, more turns can also be applied to the common-mode choke with the same core geometry.This additionally increases the differential-mode and common-mode inductance of the choke, which can be further increased by the outer mass.

[0012] Preferably, the windings of the common-mode choke are located on the top side of the core, and thus the windings are embedded in the encasing material. In particular, the windings, and especially preferably the individual turns of each winding, are directly enveloped by the encasing material. The encasing material thus contacts the turns and / or the core.

[0013] Preferably, the encapsulation material is divided into individual segments, which are preferably not in contact with each other. In particular, each winding is embedded in its own segment of the encapsulation material. These segments, especially those separated from one another, are particularly suitable for high-voltage applications.

[0014] Preferably, the core of the common-mode choke is a closed ring shape. The ring shape defined here need not be round, but can also be polygonal, for example, square or hexagonal. Crucially, the ring shape requires that the core has a central recess so that the individual windings can run around the core. In particular, the core is toroidal.

[0015] The core has an inner surface, an outer surface, a top surface, and a bottom surface opposite the top surface. The inner surface of the core faces the central recess of the ring shape. Preferably, the coating material is in contact with the core on the inner surface and / or the outer surface and / or the top surface and / or the bottom surface. In some areas, the coating material may not be in direct contact with the core, but rather directly with the windings.

[0016] Preferably, the core of the common-mode choke comprises an inner core and a housing. Preferably, the housing has a magnetic permeability µ. r >1, preferably µ r >2. For this purpose, it is specifically provided that the housing comprises a plastic matrix and embedded microparticles, wherein the microparticles consist of a soft magnetic material. The microparticles for the housing can be the same type of particles as those used in the encapsulation material. Alternatively, other particles can be used for the housing to adjust the desired magnetic permeability of the housing. The use of a housing around the inner core with a magnetic permeability greater than 1 improves the leakage flux through this housing.

[0017] Preferably, the housing completely surrounds the inner core. This ensures that the inner core is covered on all sides by the housing. Furthermore, it is preferably the case that the inner core comprises a nanocrystalline material, and in particular is made of nanocrystalline material.

[0018] In an alternative preferred variant, the core comprises the inner core, but without a casing.

[0019] Preferably, the common-mode choke has exactly two windings, exactly three windings, or exactly four windings. Preferably, each winding comprises several turns. The windings preferably comprise an electrical conductor, in particular wire, with electrical insulation.

[0020] The invention further comprises an electromagnetic interference filter with at least one choke arrangement as previously described.

[0021] Furthermore, the invention discloses a method for manufacturing a choke assembly, in particular the choke assembly described above. The method comprises at least the following steps: First, a common-mode choke and an encapsulation material are provided. The common-mode choke has a core and at least two windings surrounding the core. The common-mode choke can also have the optional configurations described above. The encapsulation material has a magnetic permeability µ. r >1, preferably µ r >2. The encapsulation material can have the optional configurations described above.

[0022] In the next process step, a differential-mode inductance is formed by encasing the common-mode choke with the encapsulating material. In this state, the encapsulating material is liquid or viscous. The encapsulation is carried out, in particular, by potting or overmolding in an injection molding process. As described in the context of the choke arrangement according to the invention, the common-mode choke can also be overmolded in a multi-component process, in which case the encapsulating material constitutes one component, and a further component made of a different material can be used additionally, for example, to electrically separate the segments of the encapsulating material from one another or to implement other functions on the choke arrangement.

[0023] In the next process step, the coating material is hardened and the throttle assembly is demolded. Brief description of the drawings

[0024] A preferred embodiment of the invention is described in detail below with reference to the accompanying drawings. The drawing shows: Fig. 1 a schematic view of a throttle arrangement according to the invention in a preferred embodiment of the invention, Fig. 2 a schematic representation of a common-mode choke of the choke arrangement according to the invention in the preferred embodiment of the invention, Fig. 3 a schematic side view of Fig. 1, Fig. 4 a schematic top view of Fig. 1, Fig. 5 a simplified, schematic representation of the throttle arrangement according to the invention in the preferred embodiment of the invention, Fig. 6 a purely schematic representation of an electromagnetic interference filter according to the invention with the choke arrangement according to the preferred embodiment of the invention, and Fig. 7 a purely schematic representation of a method according to the invention for producing the throttle according to the preferred embodiment of the invention. Embodiments of the invention

[0025] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0026] The following refers to the Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5 a throttle arrangement 1 described. Fig. Figure 6 shows an electromagnetic interference filter 100 with the choke arrangement 1. Fig. Figure 7 shows a method 200 for manufacturing the throttle arrangement 1.

[0027] Fig. Figure 1 shows the choke arrangement 1 with common-mode choke 2 and casing mass 40. Fig. In Figure 2, the outer mass 40 is hidden to show the structure of the common-mode choke 2 more precisely. Fig. 3 and Fig. Figure 4 shows schematic side views and top views of the throttle assembly 1. Fig. Figure 5 shows a simplified schematic view of the throttle arrangement 1. The following section will first refer to the Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5. Referenced.

[0028] The common-mode choke 2 comprises a core 21. The core 21 has an inner core 29, which is surrounded by a housing 22. The division into inner core 29 and housing 22 is shown purely schematically. Fig. 5. The inner core 29 preferably consists of nanocrystalline material. The housing 22 preferably has a magnetic permeability greater than 1.

[0029] In the illustrated embodiment, the common-mode choke 2 comprises four windings 23. Each winding 23 comprises several turns 24 formed from an insulated wire. Fig. Figure 2 illustrates that the common-mode choke 2, particularly the core 21, has an inner surface 25, an outer surface 26, a top surface 27, and a bottom surface 28. The core 21 is annular. The coating material 40 preferably rests against the inner surface 25, the outer surface 26, the top surface 27, and the bottom surface 28 of the core 21.

[0030] The encapsulation mass 40 has a magnetic permeability greater than 1. In the illustrated embodiment, the encapsulation mass 40 is divided into four segments 41. The segments 41 do not touch each other. Each segment 41 of the encapsulation mass 40 encloses one of the windings 23. A free space 42 is shown between the segments 41.

[0031] In the simplified representation according to Fig. Figure 5 omits the representation of the segmentation; only two of the windings 23 are shown. Fig. Figure 5 illustrates a main flow path 54 in the inner core 29 of the common-mode choke 2. Furthermore, it shows Fig. 5 in the area of ​​winding 23, a magnetic flux region 50 is found in the inner core 29 along the main flux path 54. Subsequent to the magnetic flux region 50, a branch leakage flux region 51 extends from the inner core 29 across any air gap to the housing 22. In the housing 22, particularly due to the magnetic permeability of the housing 22, a first leakage flux region 52 extends through the housing 22. The second leakage flux region 53 is found in the enclosure 40 and thus in the differential-mode inductance. As shown in the schematic diagram in Fig. Figure 5 shows that the encapsulation mass 40 is at least in contact with the outer surface 26 and the inner surface 25 of the core 21, so that the push-pull inductance acts both inside and outside.

[0032] Fig. Figure 6 schematically shows an electromagnetic interference filter 100. This filter may include a printed circuit board 101. The printed circuit board contains at least one of the described choke arrangements 1 and, optionally, further components 102.

[0033] Fig. Figure 7 schematically illustrates the process 200 for manufacturing the choke assembly 1. In a first process step 201, the described common-mode choke 2 is prepared. In a second process step 202, the described coating material 40 is prepared. In the third process step 203, the common-mode choke or the common-mode inductor is coated. This is done by overmolding or overmolding the common-mode choke 2 with the coating material 40. In the fourth process step 204, the coating material 40 is cured, and the finished choke assembly 1 is demolded. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 3 683 811 A1

[0002]

Claims

[1] Throttle arrangement (1) comprising - a common-mode choke (2) with a core (21) and at least two windings (23) surrounding the core (21), and - a differential-mode inductance formed by a hardened encapsulation material (40), wherein the encapsulation material (40) encapsulates the common-mode choke (2), and wherein the encapsulation material (40) has a magnetic permeability µ r >1, preferably µ r >2, exhibits. [2] Throttle arrangement according to claim 1, wherein the common-mode choke (2) is encapsulated with the covering material (40). [3] Throttle arrangement according to claim 1, wherein the common-mode choke (2) is overmolded with the covering material (40); - preferably wherein the common-mode choke (2) is overmolded with at least two components made of different materials, in particular in a multi-component process, wherein the coating material (40) is one of the at least two components. [4] Throttle arrangement according to one of the preceding claims, wherein the enclosing mass (40) comprises a plastic matrix and embedded µ-particles, the µ-particles being made of soft magnetic material. [5] Throttle arrangement according to one of the preceding claims, wherein the encapsulation mass (40) has a thermal conductivity of at least 0.7W / mK, preferably at least 1W / mK. [6] Throttle arrangement according to one of the preceding claims, wherein the covering mass (40) is divided into individual segments (41) which preferably do not touch each other; in particular, wherein each winding (23) is embedded in its own segment (41) of the covering mass (40). [7] Choke arrangement according to one of the preceding claims, wherein the core (21) of the common-mode choke (2) is closed annular, in particular toroidal; preferably wherein: - the core (21) comprises an inner side (25), an outer side (26), a top side (27) and a bottom side (28) opposite the top side (27), wherein the covering mass (30) is in contact with the core (21) at the inner side (25) and / or the outer side (26) and / or the top side (27) and / or the bottom side (28). [8] Choke arrangement according to one of the preceding claims, wherein the core (21) of the common-mode choke (2) comprises an inner core (29) and a housing (22); preferably: - wherein the housing (22) has a magnetic permeability µ r >1, preferably µ r >2, has; - and / or wherein the housing (22) comprises a plastic matrix and embedded µ-particles, the µ-particles being made of soft magnetic material. [9] Electromagnetic interference filter (100) with at least one choke arrangement (1) according to one of the preceding claims. [10] Method for manufacturing a throttle arrangement (1), in particular the throttle arrangement (1) according to any one of the preceding claims, comprising the following steps: - Providing a common-mode choke (2) with a core (21) and at least two windings (23) surrounding the core (21), - Providing an enclosing mass (40), wherein the enclosing mass (40) has a magnetic permeability µ r >1, preferably µ r >2, exhibits - Forming a differential-mode inductance by encasing, in particular by casting or overmolding, the common-mode choke (2) with the encasing material (40), - subsequent hardening of the coating material (30) and demolding of the throttle assembly (1).

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