Choke with cooling device

Abstract

The invention relates to a choke with a cooling device, which comprises a hollow soft magnetic core (10) and at least two electrical conductors (20; 21) introduced into a cavity of the soft magnetic core (10), the electrical conductors being arranged in the cavity with a spacing (A) between their inner sides, thereby forming an intermediate region in the cavity, wherein a cooling element (30) is arranged in the intermediate region.

Description

Technical Field

[0001] The invention relates to a choke with a cooling device. Background Art

[0002] EMV filter (EMV = Electromagnetic filter Electromagnetic compatibility (EMC) is used in power electronics in vehicles to ensure that the vehicle electrical system is not disturbed as much as possible. The current prior art has a design scheme for filters with purely passive cooling. Due to passive cooling, although the filter has a large structural space, the losses or heat generated by the filter may not be effectively dissipated. Here, the common mode choke, which is the main component of the filter, is particularly important in terms of heat dissipation.

[0003] like Figure 1 As shown, the common mode choke 1 has a soft magnetic core 10 and at least two conductive rails 20 and 21 guided inside the soft magnetic core 10 for DC connection. The soft magnetic core 10 is usually implemented as a hollow body, for example, as a cylinder or as a plurality of rings. For example, the conductive rails 20 and 21 introduced into the cavity carry high currents that may be up to several hundred amperes. Due to the high current, the conductive rails 20 and 21 generate significant heat losses that cannot be effectively dissipated by conventional passive cooling. Summary of the invention

[0004] It is therefore an object of the present invention to provide a choke for an EMC filter in which better heat dissipation is ensured. According to the invention, this object is achieved by the choke according to the invention.

[0005] A choke is provided, which has a hollow soft magnetic core and at least two electrical conductors introduced into the cavity of the soft magnetic core, the electrical conductors being arranged in the cavity with a spacing between their inner sides, thereby forming an intermediate region in the cavity, wherein a cooling element is arranged in the intermediate region. The choke is preferably an electrical choke, in particular a common mode choke. The (common mode) choke can be arranged, for example, at the high voltage input of a power electronic device when used in a power electronic device, for example, between a DC high voltage plug (DC=Gleichstrom, direct current) and an intermediate circuit capacitor when used in an inverter.

[0006] Such an electrical conductor can be designed, for example, as a conductor track, a wire or a litz wire. The electrical conductor consists, in particular, of a material with good electrical conductivity, such as copper or aluminum.

[0007] This soft magnetic core is made of a soft magnetic material. This is to be understood in particular as a ferromagnetic material that can be easily magnetized in a magnetic field. According to DIN EN 60404-1, this material can in particular be a raw material with a coercivity of less than or equal to 1000 A / m.

[0008] Better heat dissipation can be achieved by providing cooling elements inside the choke, specifically in the space between the inner sides of the conductors of the soft magnetic core and thus directly on the conductors. Such cooling elements are therefore used to dissipate heat from the cavity, in particular from the conductors.

[0009] In an embodiment, the cooling element has a thickness corresponding to the spacing between the electrical conductors. In an embodiment, the cooling element occupies the entire intermediate area between the electrical conductors. By filling the entire space between the electrical conductors, heat removal is further improved.

[0010] In an embodiment, at least one further cooling element is arranged on the outer side of at least one electrical conductor.

[0011] In an embodiment, the cooling element or at least one of the cooling elements, in particular the other cooling element, is formed as a latent heat storage with a phase change material. Depending on the material used, the latent heat storage can store thermodynamic energy (i.e. heat and cold) for a long time in order to release them later. For this purpose, a phase change material (PCM) is used, which changes its physical state depending on the ambient temperature. Advantageously, a material is used that changes state from liquid to solid and vice versa, thereby providing a high storage capacity. The phase change material is prepared, for example, from salts or organic compounds such as alkanes or fatty acids.

[0012] In an embodiment, at least one cooling layer is arranged between at least one of the electrical conductors and at least one cooling element assigned to the at least one of the electrical conductors. Such a cooling layer is formed of a heat insulating material and is used to cool the electrical conductor, and can be formed in different ways, as will be described below.

[0013] In an embodiment, the cooling element and / or at least one further cooling element has at least one cooling channel in its interior. The cooling channel is preferably configured to be flowed through by a cooling medium, such as a cooling liquid or a cooling gas. Such an embodiment can be referred to as active cooling or an active cooling element.

[0014] In an embodiment, the cooling element and / or at least one further cooling element is formed from a ceramic material. Such a ceramic material may be, for example, a material that is also used for power modules, for example, Al2O3 or AlN.

[0015] The heat removal is further improved by providing further cooling elements, cooling layers, cooling channels or combinations thereof, by which the electrical conductors are optionally surrounded from a plurality of sides and are optionally formed from a material that dissipates heat well.

[0016] In one embodiment, the cooling element and / or at least one further cooling element protrudes from the cavity into the outer region of the choke. Thus, an improved thermal insulation of the outer part of the soft magnetic core can also be achieved.

[0017] In an embodiment, the electrical conductors are designed as conductor rails and are arranged substantially parallel to one another in the cavity.

[0018] Further features and advantages of the invention are apparent from the following description of exemplary embodiments of the invention with reference to the accompanying drawings which show details. The individual features can be realized individually or in multiples in any desired combination in the embodiment variants of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] Figure 1 A common mode choke according to the prior art is shown;

[0021] Figure 2 shows a cross section of a common mode choke with a cooling element according to an embodiment of the present invention;

[0022] Figure 3 A cross section of a common mode choke having multiple cooling elements according to another embodiment of the present invention is shown.

[0023] In the following description of the figures, the same elements or functional parts have the same reference numerals. DETAILED DESCRIPTION

[0024] The core of the present invention is to provide at least one cooling element in the common mode choke, thereby enabling effective cooling and reducing the installation space.

[0025] This is achieved through Figure 2 and Figure 3 The common mode choke 1 shown in FIG. is realized by a structural change. Specifically, the region of the electrical conductors 20, 21 located inside the soft magnetic core 10 of the common mode choke 1 is supplemented with at least one further component for active cooling. The electrical conductors 20 and 21 are preferably designed as conductor rails.

[0026] Figure 2 and 3The cross section of the soft magnetic core 10 of the common mode choke 1 is shown. Since the soft magnetic core 10 is implemented as a ring or a hollow cylinder, the cross section is at least approximately circular and therefore has a cavity. The conductors 20 and 21 each have a rectangular cross section and are oriented to each other in such a way that they are arranged at a distance A from each other. Advantageously, the conductors are arranged substantially parallel to each other in the cavity. The diameter of the cavity is selected to be at least as large as the width L of the longest or widest conductors 20, 21, so that these conductors can be introduced into the cavity. Alternatively, the width L of the conductors 20, 21 can also be selected depending on the available diameter of the cavity. It is important that the conductors 20, 21 can be introduced into the cavity and can be arranged there.

[0027] The inner sides of the electrical conductors 20, 21 are the sides facing each other. These sides are arranged at a distance A from each other. These inner sides and the inner wall of the core 10 form an intermediate space. As will be described later, the electrical conductors 20, 21 are introduced into the cavity of the core 10. The outer sides of the electrical conductors 20, 21 are the sides facing the inner wall of the soft magnetic core 10.

[0028] Figure 2 A first embodiment of the invention is shown with a single cooling element 30. This cooling element 30 can be used for active cooling when it is formed, for example, from a ceramic material with cooling channels guided therein. Here, a cooling medium is actively circulated therein by means of corresponding devices, for example a pump. When the cooling element is formed from a heat-insulating material, the cooling element can also be used as a passive cooling element. The cooling element is arranged in the intermediate space between the two conductor rails 20 and 21. Advantageously, the thickness of the cooling element 30 corresponds to the spacing A. It is also advantageous that the cooling element 30 occupies the entire space between the conductors 20 and 21, that is, the thickness not only corresponds to the spacing A but also extends at least over the entire width L of the conductor rails. Preferably, the cooling element 30 also extends over the entire length of the cavity.

[0029] Figure 3 2 shows a schematic cross-sectional view of another embodiment. In order to make the cooling more effective, at least one further cooling element 40 or 41 is arranged on the outer side of at least one of the electrical conductors 20 and 21. Advantageously, two such further cooling elements 40 and 41 are provided, one of which is arranged on the outer side of each electrical conductor 20 and 21. In this embodiment, the Figure 2 The described cooling element 30 is also arranged between the inner sides of the electrical conductors 20 and 21. That is, the further cooling elements 40, 41 are arranged on the outer sides of the electrical conductors 20, 21, which are opposite the inner sides of the conductors 20, 21, and the cooling element 30 is arranged on the inner sides.

[0030] Thus, the electrical conductors 20 and 21 are surrounded by the cooling element 30 and the further cooling elements 40 and 41 over a large area, so that by this embodiment, double-sided cooling is achieved for each of the electrical conductors 20 and 21. The further cooling elements 40 and 41 should be arranged as far as possible over the entire available width L of the outer side of each electrical conductor 20, 21, in order to thereby achieve the greatest possible cooling effect. It is also advantageous if, as described above, the cooling element 30 occupies the entire intermediate area between the inner sides of the electrical conductors 20, 21.

[0031] The cooling element 30 and the further cooling elements 40 and 41 are advantageously made of ceramic material. In another active embodiment of cooling, at least one cooling channel may be present in the middle or in other regions of one or more cooling elements 30, 40, 41. The cooling medium can be guided through the cooling channel to dissipate the heat of the conductors 20, 21. When it is expected that a larger heat receiving portion is present in the region away from the middle of the respective cooling element 30, 40, 41 than in other regions, the cooling channels can be arranged staggered in this region, for example. Due to the relatively good thermal conductivity of ceramics, the heat losses generated by the electrical conductors 20 and 21 can be effectively transferred to the cooling medium optionally present in the cooling channel. In addition to thermal insulation, the ceramic can also have the task of forming an electrical insulation portion between the conductors 20 and 21.

[0032] The cooling elements 30, 40 and 41 can also be formed by a cooling layer. The material used for such a cooling layer is, for example, FR4 material, ie, a glass fiber mesh or the like impregnated in epoxy resin.

[0033] Alternatively, the cooling elements 40 and 41 are formed as latent heat stores, ie have a phase change material which, as described above, can transfer heat by means of a phase change effect. Examples of latent heat stores are heat pipes, which are used, for example, in computer construction.

[0034] In a further alternative embodiment, one or more (not shown) insulating and / or cooling layers may be provided between each electrical conductor 20, 21 and the associated cooling element 30, 40, 41. These insulating or cooling layers may serve as additional thermal insulation to enhance the cooling effect and may be formed, for example, of a thermal interface material (TIM). However, when they are formed of a ceramic material, they may also be used for electrical insulation. By using a plurality of insulating and / or cooling layers, which may also be formed of different materials, heat dissipation may be optimized.

[0035] In summary, the cooling elements 30, 40 and 41 can therefore be constructed identically, for example, as active cooling elements or passive cooling elements. However, the cooling elements 30, 40 and 41 can also be constructed differently. For example, the cooling element 30 can be formed as an active cooling element made of a ceramic material with a cooling channel and a cooling medium that actively circulates in the cooling channel. Here, an additional cooling layer can be present between the cooling element 30 and the associated electrical conductors 20, 21. In this case, as described above, the cooling elements 40 and 41 can be formed as latent heat storage. Here, an additional cooling layer can also be present between each cooling element 40, 41 and the associated electrical conductors 20, 21.

[0036] Furthermore, in a further (not shown) embodiment, extensions of the cooling element 30 and, if present, the further cooling elements 40 and 41 can be provided protruding from the soft magnetic core 10 in order to ensure electrical insulation to the outside of the core 10. In addition, better heat removal can also be achieved by enlarging the surface.

[0037] Reference numerals list

[0038] 1 Common mode choke

[0039] 10 Soft magnetic core

[0040] 20, 21 Electrical conductors, conductor rails

[0041] 30 Cooling element

[0042] 40, 41 Additional cooling elements

[0043] L Width

[0044] A Spacing

Claims

1. A choke (1) for an electromagnetic compatibility filter in a power electronic device in a vehicle, the choke being arranged at a high voltage input of the power electronic device, the choke having a hollow soft magnetic core (10) and at least two electrical conductors (20; 21) for DC connection introduced into a cavity of the soft magnetic core (10), the electrical conductors being arranged in the cavity with a spacing (A) between their inner sides, thereby forming an intermediate area in the cavity, characterized in that A cooling element (30) is arranged in the middle region, wherein the electrical conductors (20; 21) are designed as conductor rails and are arranged parallel to one another in the cavity, and wherein the electrical conductors (20; 21) each have a rectangular cross section.

2. The choke (1) according to claim 1, wherein: The cooling element (30) has a thickness corresponding to the distance (A) between the electrical conductors (20; 21).

3. The choke (1) according to claim 1 or 2, wherein: The cooling element (30) occupies the entire intermediate area between the electrical conductors (20; 21).

4. The choke (1) according to claim 1 or 2, wherein: At least one further cooling element (40; 41) is arranged on the outer side of at least one electrical conductor (20; 21).

5. The choke (1) according to claim 4, wherein: At least one further cooling element (40; 41) forms a latent heat store with a phase change material.

6. The choke (1) according to claim 1 or 2, wherein: At least one cooling layer is arranged between at least one of the electrical conductors (20; 21) and a cooling element (30) associated with the at least one of the electrical conductors.

7. The choke (1) according to claim 1 or 2, wherein: The cooling element (30; 40; 41) has at least one cooling channel in its interior.

8. The choke (1) according to claim 1 or 2, wherein: The cooling element (30; 40; 41) is formed from a ceramic material.

9. The choke (1) according to claim 1 or 2, wherein: The cooling element (30; 40; 41) projects into the outer region of the choke (1).

10. The choke (1) according to claim 1, wherein: The choke (1) is a common mode choke.

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