WO2014048726A1

WO2014048726A1 - Cooling device

Info

Publication number: WO2014048726A1
Application number: PCT/EP2013/068719
Authority: WO
Inventors: Ingolf Hoffmann; Norbert Huber; Stephan Ippisch; Jochen SCHÄFER; Lothar SCHÖN; Stefan Stocker
Original assignee: Siemens Aktiengesellschaft
Priority date: 2012-09-27
Filing date: 2013-09-10
Publication date: 2014-04-03
Also published as: DE102012217607A1; CN104737247B; CN104737247A

Abstract

The invention relates to a cooling device, in particular for coils of a transformer, comprising: a substantially flat mat (10) with a first and a second surface (1, 2) on which lines (4) are arranged for guiding a fluid, said lines being connected to one another by openings (5) provided in the mat (10). The fluid can be introduced into lines (4) arranged on the second surface (2) of the mat (10) from lines (4) arranged on the first surface (1) of the mat (10) through said openings. The use of said device enables choke coils to have a high cooling efficiency, also having a compact design with a reduced weight while simultaneously reducing production costs.

Description

description

The invention relates to a device for cooling, in particular for choke coils, as well as coil windings which use such a device for cooling.

For some time, inductors have been known which are used for damping, radio interference suppression, commutation, current limitation, suppression of undesirable frequencies or for energy storage in switching regulators and switching power supplies. Such coils, also called inductors, are inductive passive components, which are mainly used in the field of power supply of electrical or electronic equipment or systems and in power electronics.

The inductors consist of at least one winding of a conductor through which the full load current of the circuit flows, with windings which are wound on a bobbin and are usually provided with a soft magnetic core. The winding arrangement, its shape and the wire diameter, the winding and the core material determine the value of the inductance and other properties of the inductor. Through the winding of reactors, the full load current of the following circuit flows. Therefore, to keep Ohmic losses low, they often have a relatively wide cross-section. At present, inductors are wound through several layers of an insulated conductor, depending on the required number of turns. Due to the electrical stress of the coil, there are thermal losses in the winding and the coil carrier or coil core. The individual winding layers are electrically isolated from each other by introducing an insulating material. Due to the necessary conductor insulation, the power density of the coils is limited because it leads to overheating in the coil core

and / or the coil winding can come. In order to reduce thermal losses, concepts have been developed for example, provide a water cooling of inductors, which are based on the introduction of metallic heat sinks in the winding structure. For this purpose, special heatsinks must be provided for different arrangement.

Another way of cooling the choke coil is a mounting on a cooling plate. In some cases, the introduction of the cooling plate can lead to increased electrical losses due to eddy currents. In addition, the introduction of heat sinks increases the coil weight and the dimensions of the coil.

Furthermore, mats are known which are used for cooling, which, however, only work with a limited bending radius of the winding or the bobbin. For smaller coil dimensions, this is no longer possible.

It is an object of the present invention to provide a device for cooling, in particular for choke coils, which has a high cooling efficiency, has a low weight and allows a compact design, while reducing the manufacturing cost. This object is achieved by means of a device for cooling, in particular for choke coils, which comprises:

a substantially planar mat having a first and a second surface, wherein on the two surfaces thereof lines for guiding a fluid - in particular a cooling fluid - are provided, which are interconnected by provided in the mat openings through which the fluid passes from the arranged on the first surface of the mat lines in the arranged on the second surface of the mat lines can be introduced. It is particularly advantageous in this embodiment that a uniform cooling of the Drosselspulbereiche in contact with it can be ensured. In addition, the special arrangement of the lines on the two surfaces of the allows Matt also a casting with the surrounding winding area. It is particularly advantageous that by the

Grouting not only increases the mechanical stability of the choke coil, but also creates a better thermal connection. This significantly improves cooling efficiency.

To ensure a uniform flow through the device for cooling, the lines for guiding a fluid have a structure that corresponds to polygons. Particularly advantageous in this case are regular polygon structures.

In a particularly preferred embodiment, the polygons have an even number of corner nodes. Regular polygons with a straight number of vertices allow a structure that allows a uniform mechanical load and flow through the device for cooling.

In order to enable a structure that allows the spool areas to be sealed with the device for cooling without the formation of trapped air, lines meeting each other in an adjacent corner node extend for substantially a half of their length on the same surface the mat. As a result, each complementary recessed areas remain on the mat back, which greatly facilitate the casting of the coil and improve because there are no delimited on all sides area on the mat, in which a potting compound can not flow. In this way, the formation of trapped air is significantly reduced or even avoided and thereby ensures the thermal connection of the device for cooling to the surrounding winding area.

In an expedient embodiment, the openings provided in the mat are each arranged in a middle of the length between two corner nodes of the fluid-carrying line. This will ensure that the cooling performance on both surfaces of the mat is about the same. In a particularly suitable embodiment of the invention, the lines for guiding a fluid and the mat provided therewith can be produced from an elastic and / or electrically non-conductive plastic. This makes it possible to arrange the device for cooling in partial areas of the choke coil, which has slight bends. Furthermore, the use of plastics allows easy and inexpensive production of the device for cooling, which thereby has a low weight and avoids unwanted electrical losses caused, as occurs in metallic heat sinks. Due to the optimal cooling capacity, compact design of the choke coil can be carried out. In a further, particularly advantageous embodiment, spacers are provided which can be introduced into the surfaces of the mat which are recessed by lines for guiding a fluid. By introducing mechanically stable spacers into the surfaces of the mat which are recessed from lines for guiding a fluid, a mechanical pressure which arises during the winding process of the inductor can be absorbed and a mechanical deformation or destruction of the device for cooling, in particular of the lines for guiding a Fluids are prevented.

A further aspect of the invention relates to a coil winding, in particular of choke coils, with a device for cooling as previously described, in which the device between predetermined winding layers and / or winding areas of the coil are arranged. Such coil windings can be optimized in terms of their electrical performance and their thermal losses by the targeted arrangement of the device for cooling. In the following the invention and its embodiments will be explained in more detail with reference to a drawing. Here, the single figure shows a schematic representation of a device for cooling according to an embodiment of the invention - mat - for better illustration, a section of the mat is worked out in an enlarged perspective view. In the illustrated advantageous embodiment, the device for cooling is realized as a cooling mat 10. The cooling mat 10 has an inlet 20, via which a fluid - in particular a cooling fluid - is introduced into the device for cooling. Through lines 4 - here for clarity, only a few of them provided with reference numerals - the fluid is passed to a drain 30 of the cooling mat 10, in which the heated cooling liquid can escape.

The illustrated cooling mat 10 can be used particularly advantageously for cooling inductors - not shown here. In this case, one or more cooling mats 10 are arranged in certain winding layers and / or winding regions of a choke coil in order to be able to cool them as effectively as possible. Due to electrical stresses of the inductor, there are thermal losses in the winding and / or the bobbin or coil core, which must be dissipated as uniformly as possible. Such cooling mats 10 are preferably arranged, for example, in the case of rectangular bobbins with small bending radii, on the planes or slightly curved surfaces of the bobbin or on certain winding layers of the choke coil - not shown here.

For the most efficient cooling performance of the cooling mat 10, a uniform flow through the cooling mat 10 with the fluid must be ensured. For this purpose, the cooling mat 10 has a structure of lines 4 for guiding a fluid, which run partly on a first and second surface 1, 2 of the mat 10. In the mat 10 openings 5 are provided - even a few of them in the figure for the sake of clarity provided with reference numerals, via which the individual portions of the lines 4 are interconnected. Through these openings 5, the fluid from the on the first Surface 1 of the mat 10 arranged lines 4 flow in the arranged on the second surface 2 of the mat 10 lines 4 and vice versa. In the figure, a honeycomb-like structure of the lines 4 can be seen when they are viewed as a projection on the cooling mat surface receiving them. In the embodiment shown in the figure, the lines 4 form a regular hexagon. Since individual portions of the leads 4 are disposed on the different surfaces 1 and 2 of the mat 10, the adjacent corner nodes 6 formed by intersecting leads form Y-structures protruding from the respective surface 1, 2 of the mat 10. In this case, adjacent Y structures which form the corner nodes 6 of the hexagon are each arranged alternately on one of the surfaces 1, 2 of the mat 10. This results in recesses or lead-free areas on the respective surface 1, 2 of the mat 10, which allow casting of the mat 10 between individual winding layers or a winding layer and a coil core of the choke coil. This special arrangement is when casting with a

Potting the formation of air bubbles significantly reduced or avoided. Air inclusions would have a negative effect because they are a thermal insulator and thereby restrict a preferred thermal connection of the mat 10 to the elements to be cooled of the inductance coil.

It has been found that a honeycomb-hexagonal arrangement of the lines 4 has a particularly advantageous mechanical effect and, moreover, allows a uniform flow through the mat 10 with the fluid flowing through the lines 4. This increases the cooling capacity.

In addition, spacers 3 can be introduced into the areas of the Y structures of the mat 10 which are recessed from lines 4, whereby a mechanical pressure which arises during a winding process of the choke coil can be absorbed and thereby a mechanical deformation of the mat 10 so- how their lines 4 can be prevented. In this way it is ensured that no line 4 is interrupted and thus the fluid can flow uniformly in all areas of the mat 10.

In other - not shown here - embodiments, the arrangement of the lines 4, for example, be square, thereby forming in the corner node 6 L-shaped structures that have similar advantages as the just discussed in the hexagonal arrangement of the lines 4 Y- structures. In addition, arrangements of lines 4 are possible, which may have any shape of a polygon, but also other, for example, curved shapes. The preferred embodiments here have a straight corner number - here six -, whereby adjacent corner nodes 6 can be arranged alternately on the one surface 1 and another surface 2 of the mat 10. The resulting advantage has been discussed above and relates to the uniform casting of the mat 10 with the elements to be cooled of the choke coil through the intended recessed areas of the cooling mat 10th

As the material for the mat 10 and its conduits 4, plastics are elastically preferred since they have a low weight, allow easy manufacture of the device for cooling, and are inexpensive. In addition, many of the plastics are also electrical insulators, thereby minimizing electrically induced inductor losses due to alternating voltages. Another advantage of elastic plastics is their ability to be deformed without being damaged. As a result, installation and a specific arrangement of the cooling mat 10 in the inductance coil are considerably favored. Reactive coils, which have such a device for cooling, have a more compact construction than conventional inductors, can be produced inexpensively and above all operated cost-effectively.

Claims

claims

1. Device for cooling, in particular for coils of a transformer, comprising:

a substantially planar mat (10) having first and second surfaces (1, 2),

on the two surfaces (1, 2) of lines (4) are provided for guiding a fluid,

which are interconnected by openings (5) provided in the mat (10),

passing the fluid from the conduits (4) disposed on the first surface (1) of the mat (10) to conduits disposed on the second surface (2) of the mat (10)

(4) can be introduced.

2. Apparatus according to claim 1, characterized in that a structure of the lines (4) for guiding a fluid in particular corresponds to regular polygons.

3. Device according to claim 1 or 2, characterized in that the polygons have a straight corner node number (6).

4. Device according to one of claims 1 to 3, characterized in that in each case in an adjacent corner node (6) hitting lines (4) for guiding a fluid substantially over half its length on the same surface (1, 2 ) of the mat (10).

5. Device according to one of claims 1 to 4, characterized in that provided in the mat (10) openings

(5) are arranged at a center of the length of the conduits (4) for guiding a fluid.

6. Device according to one of claims 1 to 5, characterized in that the lines (4) for guiding a fluid and the mat provided therewith (10) are made of an elastic plastic.

7. Device according to one of claims 1 to 6, characterized in that spacers (3) are einbringba in the recessed lines of lines (4) for guiding a fluid surfaces.