DE102020210215A1 - Transformer, power electronic component with transformer and method for manufacturing a transformer - Google Patents

Abstract

The invention relates to a transformer (1), comprising a printed circuit board (2) which has a first and a second winding arrangement and is arranged between a first and a second core part (3.1, 3.2) of a transformer core (3), the first core part (3.1) is partially accommodated in recesses (4) of the printed circuit board (2), so that the two core parts (3.1, 3.2) rest on one another in some areas. According to the invention, the first core part (3.1) and the second core part (3.2) are connected in a form-fitting manner, with the form-fitting acting perpendicularly to the printed circuit board (2), so that the two core parts (3.1, 3.2) are held together by the form-fitting, preferably solely by the form-fitting The invention further relates to a power electronic component with a transformer (1) according to the invention and a method for producing a transformer (1).

Description

The invention relates to a transformer having the features of the preamble of claim 1. The invention also relates to a power electronic component having a transformer according to the invention and a method for producing a transformer.

State of the art

From the DE 10 2016 113 752 A1 a sensor arrangement for a motor vehicle is known. The sensor arrangement includes a voltage supply device with a transformer which is designed as a planar transformer. A first and a second coil of the transformer are formed by first and second conductive traces, which are arranged on a first and a second side of a printed circuit board. A two-part ferrite core is inserted into openings in the printed circuit board in such a way that the two ferrite core parts lie on top of one another and thereby encompass the coils. Furthermore, at least one holding element is provided for connecting the two ferrite core parts. By configuring the transformer as a planar transformer, a space-saving voltage supply device can be provided.

Proceeding from the prior art mentioned above, the present invention is based on the object of specifying a robust transformer that is as simple as possible to produce.

To solve the problem, the transformer with the features of claim 1 is proposed. Advantageous developments can be found in the dependent claims. In addition, a power electronic component with a transformer according to the invention and a method for producing a transformer are proposed.

Disclosure of Invention

The proposed transformer comprises a printed circuit board having a first and a second winding arrangement, which is arranged between a first and a second core part of a transformer core. Sections of the first core part are accommodated in recesses in the printed circuit board, so that the two core parts lie on top of one another in certain areas. According to the invention, the first core part and the second core part are connected in a form-fitting manner, with the form-fitting acting perpendicular to the printed circuit board, so that the two core parts are held together by the form-fitting, preferably solely by the form-fitting. This means that another connection, for example an adhesive and/or clamped connection, of the two core parts can be dispensed with. In this way, the production, in particular the assembly, of the transformer according to the invention can be simplified.

The number of parts in the transformer is reduced if no further connecting means, such as a clamp, are used at all. As a result, the space requirement and the manufacturing costs are reduced. At the same time, a secure and robust connection of the two core parts is established via the form fit. Due to the fact that the positive locking acts perpendicularly to the printed circuit board, the two core parts are firmly held together. Even shocks cannot harm this connection.

The proposed transformer is preferably designed as a planar transformer analogous to the prior art mentioned at the outset. The winding arrangements can accordingly be formed in particular by conductor tracks on the printed circuit board. The winding arrangements thus also come to lie between the two core parts. At least one core part, in this case the first core part, is cut out in the area of the winding arrangements.

The form fit connecting the two core parts is preferably realized by means of geometries which engage behind one another on the surfaces of the two core parts which face one another. The geometries can be formed during the manufacture of a core part and/or subsequently by post-processing a core part. Particularly suitable geometries are geometries of opposite design, which interlock according to the tongue and groove principle. In addition, the geometries have to engage behind one another in order to achieve the form fit. For example, a first geometry can be a spring in the form of a web with at least one web flank that is undercut. The further geometry can then be a groove with an undercut groove flank for receiving the tongue or the web. It is also possible for a plurality of webs to form a first geometry, which each engage in a groove forming a second geometry.

In a further development of the invention, it is proposed that the geometries be designed in such a way that the two core parts can be displaced relative to one another in a plane parallel to the printed circuit board. In this way, the form fit can be implemented in a simple manner during assembly of the transformer by pushing the second core part onto the first core part. For example, the geometries can be rail-like. This is the case when at least one web and one groove are formed as geometries that engage in one another and behind one another. With several Ste Gen and grooves, these are preferably formed parallel to each other. If there is only one wide web and only one wide groove, the web flanks can also not be formed parallel, but rather run towards one another. The flanks of the groove then run accordingly, so that self-centering is achieved when the second core part is pushed onto the first core part.

Furthermore, it is proposed that the first core part is supported on the printed circuit board via at least one elastic damping element and/or a spring element. The support of the first core part via the at least one elastic damping element and/or spring element prevents the first core part from hitting the printed circuit board and damaging it, particularly in the event of vibrations. This is because the kinetic energy is converted into deformation energy by the at least one elastic damping element and/or spring element. The at least one elastic damping element and/or spring element thus reduces the load on the transformer. At the same time, the robustness of the transformer increases. This is therefore particularly suitable for mobile applications.

In an advantageous embodiment of the invention, the first core part is supported on the printed circuit board via at least one elastic damping element and one spring element. If the damping element shows a settling behavior over time, this can be compensated for by the spring element.

According to a preferred embodiment of the invention, the printed circuit board has webs between the recesses for accommodating the first core part in sections, and the thickness of the printed circuit board is reduced in the area of the webs. This means that the circuit board forms a recess. The second core part is accommodated in sections in the area of the recess. With the help of the printed circuit board, an unintentional displacement of the second core part relative to the first core part can thus be prevented after assembly has taken place. This further increases the robustness of the transformer. If the first core part is supported on the printed circuit board via at least one elastic damping element and/or spring element, the at least one damping element and/or spring element can be used to exert a prestressing force on the first core part, so that the latter moves the second core part into the area of the recess pulls in the circuit board. The second core part is then held in position by the prestressing force.

As a further development measure, it is proposed that the second core part has at least one, preferably at least two, side surfaces running at an angle α<90° to the printed circuit board, so that the cross-sectional area of the second core part increases with increasing distance from the printed circuit board. The at least one side surface running at an angle to the printed circuit board serves to position the two core parts in relation to the printed circuit board. Because while the second core part is pulled into the area of the recess of the circuit board due to the pretension of the first core part, the sloping side surface comes into contact with the circuit board and causes the two core parts to be displaced in a plane parallel to the circuit board. In this way, the assembly of the transformer can be further simplified, since the two core parts align themselves with respect to the printed circuit board during assembly.

Furthermore, the first core part preferably has three parallel plateaus, each of which engages in a recess in the printed circuit board. The three plateaus include a preferably centrally arranged plateau, which is set back from the other two plateaus and delimits a gap together with the second core part. The magnetic resistance of the magnetic circuit and thus the inductance of the transformer can be adjusted via the gap. The inductance value of the transformer is a design parameter for use in circuit topologies such as use in a flyback circuit. Depending on the field of application of the transformer, the gap can have a gap width of 10-300 μm, for example 40 μm. The plateau delimiting the gap may have been machined by grinding so that it is set back from the other plateaus.

A transformer according to the invention can be used in particular in a power electronic component, for example in an inverter or in a DC/DC converter. A power electronic component, for example an inverter or DC/DC converter, with a transformer according to the invention is therefore also proposed. For example, the electronic power component can be a high-voltage inverter for a fuel cell system of a vehicle. The small amount of space required and the increased robustness of the transformer according to the invention prove to be particularly advantageous in a mobile application.

• - Einsetzen des ersten Kernteils in Ausnehmungen der Leiterplatte, so dass in Ausnehmungen des ersten Kernteils eingesetzte elastische Dämpfungselemente und/oder Federelemente zur Anlage an der Leiterplatte gelangen,
• - Zusammendrücken der Dämpfungselemente und/oder der Federelemente, so dass das erste Kernteil tiefer in die Leiterplatte eintaucht und auf der anderen Seite der Leiterplatte zur formschlüssigen Verbindung mit dem zweiten Kernteil wieder auftaucht,
• - formschlüssiges Verbinden des zweiten Kernteils mit dem ersten Kernteil.

To solve the problem mentioned above, a method for producing a transformer is also proposed, which has a first and a second winding arrangement having printed circuit board and a first and a two tes core part to form a transformer core includes. The procedure includes the steps:

• - Insertion of the first core part in recesses of the printed circuit board, so that elastic damping elements and/or spring elements inserted in recesses of the first core part come to rest on the printed circuit board,
• - Compressing the damping elements and/or the spring elements, so that the first core part dips deeper into the printed circuit board and reappears on the other side of the printed circuit board for the positive connection with the second core part,
• - Positive connection of the second core part with the first core part.

If the damping elements and/or spring elements are relieved again after the positive connection of the two core parts has been established, this leads to a prestressing force on the first core part. This pushes the first core part away from the printed circuit board. At the same time, the second core part comes into contact with the printed circuit board, so that the first core part cannot be pressed any further out of the recesses in the printed circuit board. The two core parts are thus held together and positioned in relation to the printed circuit board by the positive connection of the two core parts and the prestressing by means of the damping and/or spring elements. Further connecting means are not required, so that the production, in particular the assembly, of the transformer is simplified. The prestressing by means of the damping and/or spring elements also has the advantage that the robustness of the transformer increases, since these are able to compensate for vibrations by converting kinetic energy into deformation energy.

For positively connecting the two core parts, the second core part is preferably pushed onto the first core part in a plane parallel to the printed circuit board, so that geometries formed on mutually facing surfaces of the two core parts engage behind one another. The geometries are such that they allow the two core parts to be displaced relative to one another in a plane parallel to the printed circuit board. The geometries can in particular be rail-like, for example according to the tongue and groove principle, with the geometries not only intermeshing but also engaging behind one another. This is the case, for example, when the at least one groove and the at least one tongue have at least one undercut flank.

It is also proposed that the prestressing force produced when the damping elements and/or spring elements are pressed together is used to position the transformer core in relation to the printed circuit board, with at least one side surface of the second core part running at an angle α <90° to the printed circuit board for contact with a a recess delimiting edge of the circuit board is brought. As already described above in connection with the transformer according to the invention, the second core part is brought into contact with the edge of the printed circuit board by the prestressing force of the damping and/or spring elements, so that when the second core part is pulled into the printed circuit board, the edge rests on the edge sloping side surface of the second core part leads to a displacement of the two core parts or the transformer core in a plane parallel to the printed circuit board. The transformer core aligns itself in this way with respect to the circuit board.

• 1 einen ersten erfindungsgemäßen Transformator a) in einem Längsschnitt, b) in einer Draufsicht (von unten), c) in einer perspektivischen Darstellung (nur die beiden Kernteile), d) in einer weiteren perspektivischen Darstellung (nur die beiden Kernteile), e) in einer perspektivischen Darstellung (nur das obere Kernteil) und f) in einer perspektivischen Darstellung (nur das untere Kernteil),
• 2 a) und b) jeweils eine perspektivische Darstellung der beiden formschlüssig verbundenen Kernteile für einen zweiten erfindungsgemäßen Transformator,
• 3 einen Längsschnitt durch einen dritten erfindungsgemäßen Transformator und
• 4 einen Längsschnitt durch einen vierten erfindungsgemäßen Transformator.

The invention is explained in more detail below with reference to the accompanying drawings. These show:

• 1 a first transformer according to the invention a) in a longitudinal section, b) in a plan view (from below), c) in a perspective view (only the two core parts), d) in a further perspective view (only the two core parts), e) in a perspective view (only the upper core part) and f) in a perspective view (only the lower core part),
• 2 a) and b) in each case a perspective representation of the two core parts connected in a form-fitting manner for a second transformer according to the invention,
• 3 a longitudinal section through a third transformer according to the invention and
• 4 a longitudinal section through a fourth transformer according to the invention.

Detailed description of the drawings

The in the 1a) until 1f) The transformer 1 shown comprises a printed circuit board 2 with conductor tracks (not shown) arranged on both sides as winding arrangements of the transformer 1. The printed circuit board 2 is arranged between two core parts 3.1, 3.2 of a transformer core 3. The first core part 3.1 has two parallel recesses 17, so that three parallel plateaus 14, 15 are formed, two outer plateaus 14 and a middle plateau 15, which is set back compared to the two outer plateaus 14 (see Fig 1e) ). The first core part 3.1 is accommodated in recesses 4 of the printed circuit board 2 via the three plateaus 14, 15. The second core part 3.2 is set against it from the other side of the printed circuit board 2, so that in the region of the central plateau 15 there is a gap 16 between the two the core parts 3.1, 3.2 is formed (see 1a) ).

The first core part 3.1 is supported indirectly on the printed circuit board 2 via elastic damping elements 9. The damping elements 9 are accommodated in the recesses 17 of the first core part 3.1. Furthermore, the first core part 3.1 and the second core part 3.2 are positively connected. For this purpose, the two core parts 3.1, 3.2 have geometries 5, 6 which engage behind one another on the surfaces 7, 8 facing one another (see 1c ) to 1f)).

In the present case, the first core part 3.1 has a first geometry 5 on its surface 7 in the form of a groove. The groove flanks are undercut (see 1e) ). On its surface 8, the second core part 3.2 has a second geometry 6 in the form of a tongue that can be brought into engagement with the groove. For this purpose, the tongue is designed in the opposite manner to the groove or to the first geometry 5 . This means that the spring is also undercut (see 1f) ). The tongue and groove also have a varying width when viewed from above (see Fig 1b) ), so that when the positive connection is established by pushing the second core part 3.2 into the first core part 3.2, the two core parts 3.1, 3.2 are self-centering relative to one another.

To produce the form-fitting connection, the first core part 3.1 is first inserted into the printed circuit board 2, so that the damping elements 9 come to rest on the printed circuit board 2. Then the damping elements 9 are pressed together, so that the first core part 3.1 dips deeper into the recesses 4 of the circuit board 2 and reappears on the other side of the circuit board 2 from the recesses 4. In this position, the second core part 3.2 can now be pushed onto the first core part 3.1, so that the geometries 5, 6 engage in one another and behind one another. The damping elements 9 are then relieved again, so that they push the first core part 3.1 away from the printed circuit board 2. The first core part 3.1 pulls the second core part 3.2 into the printed circuit board 2. This is because the printed circuit board 2 has a smaller thickness in the area of the webs 11 which separate the recesses 4, so that a recess 12 is formed (see FIG 1a) ). The recess 12 enables the second core part 3.2 to be accommodated in the circuit board 2, so that the circuit board 2 prevents unintentional displacement of the two core parts 3.1, 3.2 relative to one another. This is because the second core part 3.2 has at least one side surface 13, preferably two side surfaces 13 arranged diagonally, which are each inclined at an angle α <90° with respect to the printed circuit board 2 (see Fig 1a) ). During assembly of the transformer, the side faces 13 each come to rest against an edge 18 of the printed circuit board 2, so that the two core parts 3.1, 3.2 align themselves with respect to the printed circuit board 2 (see 1b) ).

the 2 is a modification of the transformer 1 of 1 refer to. In the modification, the geometries 5 and 6 are rotated by 90° in the plane of the surfaces 7 and 8 (see 2 B) ), so that the undercut side surfaces of the geometries 5 and 6 each run parallel to the three plateaus 14, 15 of the first core part 3.1 (see 2a) ). If at least one side surface 13 of the second core part 3.2 runs obliquely in order to align the transformer core 3 in relation to the printed circuit board 2, this preferably runs perpendicular to the two undercut side surfaces of the geometry 6. Over the side surface 13 resting on the edge 17 of the printed circuit board 2 then an unwanted displacement of the two core parts 3.1, 3.2 relative to each other is prevented. Two side surfaces 13 arranged across a corner are preferably designed to run obliquely in order to align the transformer core 3 in relation to the printed circuit board 2 .

the 3 is another modification of the transformer 1 of 1 refer to. The modification consists in that, in addition to the damping elements 9, spring elements 10 are accommodated in the recesses 17 of the first core part 3.1. Since the damping elements 9 can settle over time, so that the prestressing force of the damping elements 9 decreases, the loss of the prestressing force can be compensated for with the help of the spring elements 10 .

In the 4 another transformer 1 according to the invention is shown. Here, too, the two core parts 3.2, 3.2 are positively connected to one another via geometries 5, 6. However, the geometry 5 includes two web-like springs which are designed with an undercut in cross section and engage in oppositely designed groove-shaped geometries 6 on the surface 8 of the second core part 3.2 and at the same time engage behind them.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016113752 A1 [0002]

Claims (10)

Transformer (1), comprising a printed circuit board (2) having a first and a second winding arrangement, which is arranged between a first and a second core part (3.1, 3.2) of a transformer core (3), the first core part (3.1) being recessed in sections (4) of the printed circuit board (2) so that the two core parts (3.1, 3.2) lie on top of each other in areas, characterized in that the first core part (3.1) and the second core part (3.2) are connected in a form-fitting manner, with the form-fitting being perpendicular to the Circuit board (2) acts so that the two core parts (3.1, 3.2) are held together by the form fit, preferably solely by the form fit. Transformer (1) after claim 1 , characterized in that the form fit is realized via geometries (5, 6) engaging behind one another on the mutually facing surfaces (7, 8) of the two core parts (3.1, 3.2), which are preferably designed in such a way that the two core parts (3.1, 3.2) are mutually displaceable in a plane parallel to the printed circuit board (2). Transformer (1) after claim 1 or 2 , characterized in that the first core part (3.1.) is supported on the printed circuit board (2) via at least one elastic damping element (9) and/or a spring element (10). Transformer (1) according to one of the preceding claims, characterized in that the circuit board (2) has webs (11) between the recesses (4) and the thickness of the circuit board (2) is reduced in the area of the webs (11), so that the printed circuit board (2) forms a recess (12), in the area of which the second core part (3.2) is accommodated in sections. Transformer (1) according to one of the preceding claims, characterized in that the second core part (3.2) has at least one, preferably at least two, side surfaces (13) running at an angle (α) < 90° to the printed circuit board (2), so that the cross-sectional area of the second core part (3.2.) increases with increasing distance from the printed circuit board (2). Transformer (1) according to one of the preceding claims, characterized in that the first core part (3.1) has three parallel plateaus (14, 15) which each engage in a recess (4) of the printed circuit board (2), the three plateaus a preferably centrally arranged plateau (15) which is set back from the other two plateaus (14) and together with the second core part (3.2) delimits a gap (16). Electronic power component, for example an inverter or DC/DC converter, with a transformer (1) according to one of the preceding claims. Method for producing a transformer (1), comprising a printed circuit board (2) having a first and a second winding arrangement and a first and a second core part (3.1, 3.2) for forming a transformer core (3), comprising the steps: - Insertion of the first core part (3.1) in recesses (4) of the printed circuit board (2), so that elastic damping elements (9) and/or spring elements (10) are inserted in recesses (17) of the first core part (3.1) to rest on the printed circuit board (2) arrive, - Compressing the damping elements (9) and/or spring elements (10) so that the first core part (3.1) dips deeper into the printed circuit board (2) and on the other side of the printed circuit board (2) for a positive connection with the second core part (3.2 ) reappears, - Positive connection of the second core part (3.2) with the first core part (3.1). procedure after claim 8 , characterized in that for positive connection the second core part (3.2) is pushed onto the first core part (3.1) in a plane parallel to the printed circuit board (2), so that surfaces (7, 8) of the two core parts (3.1, 3.2) trained geometries (5, 6) engage behind each other. procedure after claim 8 or 9 , characterized in that the prestressing force produced when the damping elements (9) and/or the spring elements (10) are pressed together is used to position the transformer core (3) in relation to the printed circuit board (2), at least one being at an angle (a) Side surface (13) of the second core part (3.2) running <90° to the printed circuit board (2) is brought into contact with an edge (18) of the printed circuit board (2) delimiting a recess (4).

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