EP2711942B1 - Cooling of an electrical component - Google Patents

Description

The invention relates to an electrical component. During operation, the electrical component heats up. For operation of the electrical component cooling may be provided.

The electrical component, which heats up during operation, is in particular an inductive component. Examples of inductive components are a coil, a transformer or a winding of an electrical machine. Inductive components can heat up due to ohmic losses as well as magnetic losses. This heating can be reduced or limited by suitable cooling measures. A limitation is particularly necessary if materials of certain components of the electrical component work only up to certain temperatures and / or retain their technical properties.

From the US 2006/0082945 A1 For example, an electrical component is known in which is to be removed from the coil by U-shaped heat conducting plates, which protrude in parts in a coil.

It is possible to positively influence the electrical component in its temperature behavior by over-dimensioning the component. The electrical component is then sized, for example, for greater power than necessary in order to be able to dispense with additional cooling measures. However, this often leads to a larger and possibly more expensive electrical component. Another way to improve the thermal behavior of the electrical component is to shed this electrical component. Advantageously, a complete electrical component is encapsulated with the electrical component. The thermally conductive potting compound allows a removal of the heat energy away from the heat source. The casting takes place for example in a metallic cup or a metallic housing. Both forms a container for the potting compound. The container may be mounted on a cooling plate for improved cooling.

In a further embodiment of the potting, the electrical component can be completely potted in a cavity of a target housing, wherein the molded cavity is available for cooling.

From the EP 2 455 953 A1 is the use of a thermal grease for heat dissipation in an electrical component known.

An object of the invention is to provide an alternative to the cooling of an electrical component, in which it is possible to dispense with a complete encapsulation of the electrical component. The casting increases the manufacturing costs of the electrical component. Furthermore, the potting may be a hindrance in a disassembly of the electrical component, which is particularly detrimental to a recycling of the electrical component.

A solution to the problem arises in an electrical component having the features of claim 1. The claims 2 to 6 show further possible features of the electrical component.

An electrical component is in particular one which has an inductive element. An inductive element is for example a coil or a winding. The winding is, for example, a part of an electrical machine, in particular a motor or generator. Also, a transformer or a coil has at least one winding. For example, a coil is used as a choke coil. The coil as well as the transformer can be designed as air winding, or as an electrical component having an iron core. The iron core is in particular made of a laminated material and constitutes an element for guiding the magnetic flux.

The electrical component has, in addition to the inductive element and a heat conducting material. By means of the heat conduction material, it is possible to conduct heat energy away from the electrical component. The heat conduction material is in particular a material which is of a consistency such that it can be positioned. This means that no potting takes place. By means of a potting heat-conductive potting compound can contact parts of the electrical component thermally conductive. In the manufacture of the electrical component, the potting compound is initially liquid to cure thereafter. The potting compound is introduced into a cavity in a liquid state and cures there. The potting compound is not localized position, because it flows in the liquid state in cavities and is not localized before curing itself localized. The local limit is given by the cavity.

It is different with a Wärmeleitmaterial, which is even locally localized position. In the manufacture of the electrical component, it is possible to apply or attach the thermal interface material at certain localized locations. It remains at least temporarily at the place where it is applied or attached. Examples of a heat conduction material which can be positioned locally limited are a thermal paste, a heat conducting foil and / or a heat conducting pad (heat conducting pad).

In one embodiment of the electrical component, the inductive element has a winding or is designed as a winding. The winding is, for example via the heat conducting material (this is locally self-limiting positionable) connected to a heat sink thermally conductive directly.

In one embodiment of the electrical component, a winding has a multiplicity of heat conducting materials. In this case, the winding may have a plurality of winding layers, wherein the heat conducting material is located between the winding layers. By the Wärmeleitmaterial in a winding, the heat transport can be transported within a winding. This can be advantageously used, for example, in a winding head of an electrical machine.

In one embodiment of the electrical component, it has an element for guiding a magnetic flux. This element for guiding a magnetic flux, for example, a stator core of an electrical machine, a rotor core of an electrical machine, the yoke of a transformer, an iron core of a coil, in particular a throttle. The element for guiding the magnetic flux is for example directly in contact with the heat-conducting material. Furthermore, the heat conducting material has a direct contact with a heat sink. The heat sink may advantageously be designed as a housing of the electrical component.

In one embodiment of the electrical component, this has a heat sink, wherein the heat conduction material between the heat sink and the inductive element. This improves the heat transfer between the inductive element and the heat sink.

In one embodiment of the electrical component, this has a heat sink, wherein the heat conduction material between the heat sink and the element for guiding the magnetic flux. This improves the heat transfer between the magnetic flux guide element and the heat sink.

In one embodiment of the electrical component, the latter has a heat sink, wherein the heat conduction material is between the heat sink and a cooling flap, wherein the cooling flap is in particular heat-conductively connected to a power semiconductor component. This improves the heat transfer away from the power semiconductor. Power semiconductors are, for example, IGBTs, MOSFETs, etc.

In one embodiment of the electrical component, the heat conduction material is a thermal compound. The thermal grease is well suited for positioning. Advantageously, this can be designed so that at a first warming their Viscosity changed so that its creep increases. Thus, the contacted surface can be increased.

In one embodiment of the electrical component, the heat conducting material is a heat conducting foil. The film is for example one-sided or double-sided self-adhesive. The film may itself have or be coated with the heat-conducting material.

In one embodiment of the electrical component, the heat conduction material is a heat conduction pad. The heat-conducting pad can be self-adhesive on one or both sides. The heat-conducting pad may itself have or be coated with the heat-conducting material.

In one embodiment of the electrical component, this is a transformer. The transformer has at least one winding. The cooling may e.g. by pressing the magnetic core (ferrites) of the inductive component over e.g. Warmeleitpads done to a cooling plate. For this purpose, e.g. a metal spring can be used which presses the component onto the cooling plate. A connection of the electrical conductor (the winding) of the inductive component to a cooling plate, for example, via a Wärmeleitpad, an insulating nipple, screws and / or metal dome.

If a transformer has a magnetic core (in particular an iron core), then it can be coupled in a heat-conducting manner directly to the heat sink via the heat-conducting means. Advantageously, the winding of the transformer has a thermally conductive direct coupling via the heat conducting means to the heat sink.

In one embodiment of the electrical component, this is an electrical machine. The electrical machine has windings. Windings are inductive elements. Furthermore, the electric machine has a laminated core. windings and / or a laminated core are thermally conductively coupled via the heat conducting means with a heat sink. Thus, in a manufacturing process, the heat transfer medium can be easily placed between the heat sink and the laminated core. It is just as simple with a transformer in which the heat conduction between iron core and heat sink is positioned. Advantageously, the heat-conducting centers are then pressed in between correspondingly, so that contact with a large surface can form. This method is simpler, faster and / or less expensive compared to a grout.

In one embodiment of the electrical component, this is a coil. The coil is used, for example, as a reactor. In particular, the throttle has an iron core, wherein the coil similar to the transformer or the electric machine, the heat conduction between the heat sink and winding or iron core, as an element for guiding a magnetic flux having.

In one embodiment of the electrical component, pillows (heat-conducting pads) of a specific thickness or with a specific property are used as heat-conducting means. Such pillows are also referred to as a pad. The thermal pad has, for example, a thickness of about 0.23 mm and a lambda value of about 1.8 W / mK. It is also possible to use thicker heat-conducting cushions, which can advantageously also have a damping effect against vibrations. Such a pad may have a thickness of about 0.38 mm and a lambda value of about 1 W / mK. With the same lambda value, much thinner heat-conducting pads with a thickness of approx. 0.15 mm can also be used. There are also other variants conceivable, even up to electrically conductive Wärmeleitmaterialen for the connection of the magnetic material (ferrite), which carries the magnetic flux, since no electrical insulation is absolutely necessary here. With the help of a thick thermal pad, it is also possible to compensate for manufacturing tolerances.

A further possibility for improving the cooling of an electrical component results from a combination of the stated use of heat conducting material with the use of highly thermally conductive plastics in the production of a wound body for a winding.

Compared to a production of the electrical component using a potting compound results in a cost savings and environmental benefits. Furthermore, a critical process in production, namely the (sometimes repeated) potting of a component can be omitted. As a result, high costs for maintenance-intensive production equipment (potting systems) can be saved. The omission of the potting process shortens the throughput times in production, which leads to renewed cost reduction. Compared to the solution with a potting, the cooled area can be substantially increased, resulting in a marked reduction in thermal resistance (e.g., doubling the area and halving the thermal resistance). The element for guiding the magnetic flux (in particular a ferrite core), cooling flanges, a winding and / or a winding body may be coupled in heat-conducting manner on opposite sides, so that a multi-sided cooling arrangement results. In addition, cooling flanges can have more cooling surface due to the omission of fastening bores.

Through improved cooling, the size of the inductive elements can be reduced, resulting in a saving of magn. Material (leads the magnetic flux) and conductor material can result. Of course, a smaller inductive element also means that the devices equipped with it can also be made smaller. This is particularly advantageous in vehicle construction or in aircraft construction. The electrical component is thus used for example in a car which has an electric drive.

In one embodiment of the electrical component, all springs, screws or other materials that the attachment serve the inductive element omitted, since both a thermal and a mechanical connection is realized by a sandwich cooling, ie a pressing of the inductive element between two parts of a heat sink, serving as an intermediate layer of a heat conducting material.

In the manufacture of magnetic cores serving as a magnetic flux guiding element, there may be a problem that it is difficult to keep the dimensions of the finished product in close tolerance bands. This may be due, for example, to enormous size changes during a furnace process which, depending on the size of the component, can quickly affect the millimeter range. Magnet cores (ferrite cores) for transformers, chokes, etc. are advantageously ground at least on the surfaces to which they are joined together. As a result, the tolerance in this spatial direction can be maintained or determined relatively accurately. A narrow tolerance band of all surfaces is often only possible by means of subsequent processing (for example grinding), which, however, has a negative effect on the cost of the part. Advantageously, the cooling with the heat conducting material acts on these principally relatively imprecisely manufactured surfaces, being compensated by the heat conducting material manufacturing tolerances. Advantageously, the heat conduction material is therefore on a surface which is not abraded compared to other surfaces and / or has higher manufacturing tolerances than other surfaces of the respective component.

FIG 1

eine erste schematische Darstellung eines Transformators;

FIG 2

einen ersten Schnitt durch den Transformator;

FIG 3

eine zweite schematische Darstellung eines Transformators;

FIG 4

einen zweiten Schnitt durch den Transformator;

FIG 5

eine dritte schematische Darstellung eines Transformators; und

FIG 6

einen dritten Schnitt durch den Transformator.

The invention is described by way of example by figures. Showing:

FIG. 1

a first schematic representation of a transformer;

FIG. 2

a first section through the transformer;

FIG. 3

a second schematic representation of a transformer;

FIG. 4

a second section through the transformer;

FIG. 5

a third schematic representation of a transformer; and

FIG. 6

a third section through the transformer.

The representation according to FIG. 1 schematically shows a transformer 1. The transformer 1 is an electrical component, in particular an inductive power device. The transformer 1 comprises a magnetic core material (eg, a ferrite). The magnetic core material constitutes an element for guiding a magnetic flux. Further, the transformer 1 has a winding 2. The winding 2 is an inductive element, wherein the winding can be formed with and without winding body. The transformer 1 also has power terminals 7. For cooling, the transformer 1, which also has a symbolically illustrated housing 8, two cooling straps 6, which are integrated into the housing 8. A sectional view along a line II-II is in FIG. 2 shown. This sectional view is used for a more detailed explanation of the cooling principle as well as the fastening principle. These principles are shown by way of example only on a transformer, but are also transferable eg to an electric machine or a throttle.

The representation according to FIG. 2 shows the transformer 1. The transformer 1 has a first housing part 9 and a second housing part 10. Between the two housing parts 9 and 10 are the active parts of the transformer 1. The ferrite core 4 is positioned as an element for guiding the magnetic flux between the parts 9 and 10 of the housing. Such a heat conducting material 3 is also located between the second housing part 10 and the ferrite core 4. This results in a kind of sandwich cooling, since the ferrite core is located between two housing parts and with these on the Wärmeleitmaterialien 3 in thermally conductive contact. The housing with the first housing part 9 and the second housing part 10 is a heat sink, the two heat sink parts 9 and 10th having. The heat conduction material 3 is clamped in particular between the ferrite core 4 and the respective housing parts 9 and 10. The heat-conducting material 3 is, for example, heat-conducting pads, which in particular are glued to at least one of the adjacent parts. The Wärmeleitmaterial 3 is after FIG. 2 Also positioned between the inductive element 2, so the winding, and the first and second housing part 9 and 10 respectively. This also results in a kind of sandwich cooling. The heat transfer can take place both via the ferrite core 4 and via the winding 2 and / or via a winding body. Thus, the heat removal is a large area available, even if a bobbin is included. Optionally, by additional cooling flanges or cooling flaps 6, which are incorporated in the winding 2 and / or via flat-shaped power connections 7, a heat flow take place.

The heat-conducting material 3 is, for example, a highly heat-conductive soft silicone, a highly thermally conductive thermosilicone, a thermally conductive silicone-free film, a silicone-free phase change film (phase change film) or the like.

Since inductive power components often also require mechanical fastening, they can be fastened with clips, screws, etc. On the transformer 1 shown by way of example FIG. 1 It can be seen that no further fastenings are necessary here, because the transformer, almost as in a potting compound (see FIG. 2 ) is embedded. In addition, compared to the usual brackets or screws, both a fixation of the winding body or the winding, as well as the magnetic core (ferrite core) guaranteed.

In one embodiment of the electrical component 1 according to FIG. 2 it is advantageous if the inductive element 2 with the element for guiding the magnetic flux 4 in a direction 11 is not fixed, that is loosely connected. Thus, the inductive element 2 within the ferrite core 4 at least in such a way be movable, that a manufacturing tolerance of the housing parts 9 and 10 is compensated.

In order to further improve one of the described types of cooling, as in the sectional images FIG. 3 and 5 can be seen, thermally conductive materials (eg: Wärmeleitpads) between the winding 2 and the ferrite core 4 to be positioned. A further increase in heat dissipation can be achieved by additional layers of thermally conductive materials 3 between the winding layers 12. As a result, a continuous heat conduction from the inner of the inductive element 4 (winding) is constructed to the heat sink.

The representation according to FIG. 3 shows as already described a transformer 1, which has 2 layers of heat conducting material 3 in the winding. A section IV through the transformer 1 gives the representation after FIG. 4 , Here, several layers of heat conducting material 3 and winding layers 12 are shown alternately. By means of the layers of Wärmeleitmaterial in the winding 4, an improved cooling is possible. The cooling can also be improved by a thermal coupling of the winding body 13 to the housing.

The representation according to FIG. 5 shows a further section VI through the transformer 1. This section is in FIG. 6 shown. It is shown that there is also between the inductive element 2 (winding) and the element for guiding the magnetic flux 4 (ferrite core) 3 Wärmeleitmaterial. The heat-conducting material 4 is, for example, a pad which extends beyond the element 4, so that, for example, it can also contact a heat sink.

Claims (6)

1. Electrical component (1), which has an inductive element (2) and a thermally conductive material (3), wherein the thermally conductive material (3) can be positioned in a localised manner, wherein the electrical component (1) has an element (4) for guiding a magnetic flux, characterised in that the electrical component (1) has a first cooling element body (9) and a second cooling element body (10), wherein the thermally conductive material (3):

   - is between the cooling elements parts (9, 10) and the inductive element (2) and between the cooling element parts (9, 10) and the element (4) for guiding the magnetic flux, wherein the thermally conductive material (3) is a thermally conductive paste, a thermally conductive film and/or a thermally conductive cushion.
2. Electrical component (1) according to claim 1, wherein the inductive element (2) is a winding.
3. Electrical component (1) according to claim 2, wherein the winding has a plurality of thermally conductive materials (3).
4. Electrical component (1) according to one of claims 1 to 3, wherein the electrical component (1) is a transformer.
5. Electrical component (1) according to one of claims 1 to 3, wherein the electrical component (1) is an electrical machine.
6. Electrical component (1) according to one of claims 1 to 3, wherein the electrical component is a coil.

Images