DE102012003365A1 - Planar intrinsically safe transducer, has layer structure whose two circuits are galvanically separated from each other by insulation layers and magnetic layers that are separated from each other and assigned with different potentials - Google Patents

Abstract

The transducer (20) has a layer structure formed as a printed circuit board (9) and comprising circuits (1-3). Two of the circuits are respectively designed as primary and secondary circuits of a transformer and galvanically separated from each other by insulation layers (6b, 6c) and two magnetic layers (4a, 4b), where the insulation layers are arranged between the layers on which the circuits are respectively arranged. The magnetic layers respectively limit two sides of the layer structure. The magnetic layers are separated from each other and assigned with different potentials.

Description

The present invention relates generally to the field of interface technology with electronic components that can be used for measurement, control and regulation tasks, in particular as a buffer amplifier. These isolation amplifiers provide a galvanic isolation between a primary circuit and a secondary circuit and are suitable, for example, for intrinsically safe operation.

The present invention relates to a transformer, in particular a planar, non-interference-prone transformer, which is suitable for intrinsically safe circuits and is referred to below as a planar intrinsically safe transformer.

Intrinsically safe transformers or transformers are used for the galvanic isolation of circuits according to various standards, whereby both energy and signals and / or data can be transmitted via the transformers.

In various regulations and standards, for example DIN EN 60079-11 , minimum clearances for the separation of the circuits and thus also the windings or windings of the transformers are specified for different safety classes of equipment. These minimum distances are dependent on the insulating medium, so that the minimum distances in solid insulation, creepage distances and creepage distances are divided. In a typical insulation class, for example 375 V protection level, the minimum separation distance for solid insulation is, for example, 1 mm, the creepage distance in air 10 mm and the creepage distance under a protective layer about 3.3 mm.

Intrinsically safe transformers are designed and optimized in terms of geometry in such a way that the required separation distances for a certain level of protection are ensured. This can be ensured both by wound coils and by printed or etched coils on printed circuit boards. In the case of printed or etched coils, it is advantageous that no additional winding processes are required and good reproducibility can be ensured. Further advantages may lie in an improved thermal property with the same core volume. Furthermore, manufacturing costs can be lower.

DE 10 2005 041 131 A1 discloses an intrinsically safe transformer with wound coils, wherein the windings of the coils are mounted due to required isolation distances on different ring cores, which are magnetically coupled together via an additional embedded in a circuit board winding. The transformer thus formed is based on classic winding technology combined with a printed circuit board technology, wherein the circuit board is used both for insulation and for mechanical fixation.

In US 2011/0140824 A1 a transformer is proposed in which the circuits or windings to be isolated are mounted asymmetrically on different printed circuit boards, which are then connected one above the other with a magnetic core to a transformer or transformer. The core can in this case be formed from two halves, which are glued and / or stapled, for example, in order to ensure mechanical stability.

In US 2011/0095620 A1 For example, a planar transformer for miniaturized applications is described with two turns lying on opposite sides of an insulating substrate. The basic physical principle of the transmission of energy or data is based on induction. However, this is not an intrinsically safe transformer, wherein no magnetic core is used.

In EP 0 715 322 A1 is a transformer or transformer described, the conductor tracks is made entirely in planar technology with layer structure in which the conductor tracks are housed in a one-piece assembled circuit board. The circuit board is surrounded by a closed magnetic core.

It is an object of the present invention to propose miniaturization possibilities of the above-described planar transformers, in particular to enable miniaturization of intrinsically safe planar transformers.

This object is achieved by the features of claim 1. Further embodiments emerge from the subclaims.

According to the invention, a planar intrinsically safe transformer is provided with a layer structure, for example in the form of one or more printed circuit boards. The layer structure may comprise a plurality of circuits, wherein at least one first circuit and at least one second circuit are intrinsically safe or galvanically isolated from each other. Furthermore, the transformer has a first magnetic layer and a second magnetic layer, wherein the first magnetic layer delimits a first side of the layer structure and the second magnetic layer delimits a second side of the layer structure.

The transformer thus has at least one first circuit and at least one second circuit within a layer structure, wherein the first circuit and the second circuit are galvanically separated from each other by at least one insulating layer. The first magnetic. Layer and the second magnetic layer can be assigned to different potential groups or circuits.

The first circuit is in this case, for example, the primary circuit and the second circuit is in this case, for example, the secondary circuit of a transformer. Further, the transformer or transformer has a first magnetic layer and a second magnetic layer, wherein the first magnetic layer defines a first side of the layer structure and the second magnetic layer defines a second side of the layer structure. It is provided that the first magnetic layer and the second magnetic layer are separated from one another and can be assigned to different potential groups or circuits.

The two magnetic layers thus form magnetic cores or core parts that are galvanically separated from the closest circuits by z. B. paint are separated so that turns of the coils can not be short-circuited by a magnetic layer.

The technical solution is therefore to provide a transformer with a non-closed or strongly opened magnetic core, in which a first magnetic layer and a second magnetic layer are separated from each other and may have different potentials or different circuits can be assigned. The transmitter may have a layer structure based on a multilayer printed circuit board. Also, etching methods for producing the layer structure can be used.

Thus, a transformer or transformer is provided whose magnetic core is separated. It can be synonymous of several coupled coils are spoken, the magnetic fields are conducted with shielding ferrites. Alternatively or additionally, the term of a transformer with an air gap can also be selected.

The transformer or transformer according to the invention can all of Standard DIN EN 60079-11 meet the required safety distances and at the same time offers the functionality in terms of energy and / or data or signal transmission.

According to the invention, the total thickness of a transformer is reduced or minimized. This is particularly advantageous if the transformers are to be integrated into narrow housings which have, for example, a total thickness of approximately 6 mm and if a maximum of approximately 4.5 mm space is available within the housing. Thus, it is a particular advantage of the invention to be able to provide an intrinsically safe transformer which does not exceed a total thickness of, for example, 4.5 mm. An advantage of the invention is that the overall height of the intrinsically safe transformer is reduced at constant horizontal dimensions.

According to one exemplary embodiment of the transformer according to the invention, the first circuit is arranged on a first layer and the second circuit is arranged on a second layer, an insulation layer being arranged in each case between the first layer and the second layer. The insulation layer may be considered as a main insulation layer, while other insulation layers may be used as sub-insulation layers within the first and / or second circuit to provide, for example, electrically conductive coils with multiple turns, for example, by the circuits having multiple layers via an electrical contact , For example, within the secondary insulation, can be connected.

According to one embodiment of the transformer according to the invention can be provided that the first circuit adjacent to the first magnetic layer and the second circuit adjacent to the second magnetic layer.

In this way, the other conventional insulation on the magnetic core, in particular between the individual circuits and the core can be omitted, since the core is separated into several parts and the individual components of the core can be assigned to the respective closest circuits and their potentials. This is possible, among other things, since the proportions of the magnetic core can assume different potentials and are not connected to one another electrically and mechanically.

It is thus provided that the first circuit is adjacent to the first magnetic layer and the second circuit is adjacent to the second magnetic layer. In this context, "adjoining" means that the layers are in the immediate vicinity, but do not have to touch because, for example, between the layers, a lacquer layer is present.

According to one embodiment of the transformer according to the invention can be provided be that the first circuit and the second circuit have a minimum isolation distance T0 to each other and at no geometric location between the first circuit and the second circuit of the minimum isolation distance T0 is exceeded.

According to one embodiment of the transformer according to the invention, a total insulation thickness between the first magnetic layer and the second magnetic layer of (N-1) × T0 can be provided, where T0 is the minimum isolation distance and N is the number of surely galvanically isolated circuits. Thus, a reduction in the number of insulating layers in the vertical direction (direction along the layer structure) takes place with N intrinsically separate windings such that the total required insulation layer in the vertical dimension between the magnetic core parts of the transmission is only (N-1) times the minimum thickness of T0 is, that is, (N-1) × T0 instead of conventionally N × T0.

According to one embodiment of the transformer according to the invention, with a required minimum insulation thickness T0 of an insulation layer of about 1 mm, the total thickness of the transformer is not more than about 4 mm. In the total thickness of the transformer thicknesses of printed conductors, insulation materials, ferrites, paints, etc. are taken into account.

Furthermore, the space requirement of the transformer is reduced or minimized. This increases the available space for, for example, other electronic components, and may be enabled by, for example, higher frequencies and / or other materials.

Also, the geometry of the magnetic cores or core parts can be optimized or minimized so that the space requirement is minimal and the geometric shape of the cores or core parts is as simple as possible. This is consistent with the required cost optimization of electronic devices incorporating intrinsically safe transformers. Furthermore, due to the non-closed magnetic core eliminates the conventionally required recesses in the circuit board, which can save space and cost. Another advantage of the invention is that the core parts can be inexpensively mounted on the layer structure with standard bonding methods and conventional tolerances and the transformer can thereby be produced inexpensively.

The lack of the closed or nearly closed core may result in additional circuit design requirements as the inductances and couplings of the coils are typically reduced by this measure. This can be compensated by appropriate countermeasures. For example, capacitive effects can be utilized for efficient energy transfer and for compensation of the occurring leakage inductances, which can often lead to one or more resonances in the system.

Some embodiments of the invention are shown purely schematically in the drawings and will be described in more detail below. It shows:

1 a schematic representation of a conventional transformer with two circuits;

2 a schematic representation of a conventional transformer with three circuits;

3 a schematic representation of a transformer with two circuits according to a first embodiment of the invention;

4 a schematic representation of a transformer with two circuits according to a second embodiment of the invention; and

5 and 6 each a schematic representation in different views of a transfer with two spiral-shaped coils according to a third embodiment of the invention.

1 shows a schematic representation of a conventional transformer 10 with a first circuit 1 and a second circuit 2 , The transformer 10 is designed as an intrinsically safe PCB transformer, such as from EP 0 715 322 A1 known. The transformer 10 has a layer structure with primary and a secondary side, each through the two circuits 1 . 2 be formed.

1 shows a cross section through a printed circuit board 9 that of a core 4 is enclosed, being the core 4 the circuit board 9 pierces in several places. The puncture can, for example, by milling in the circuit board 9 to be provided. The circuit board 9 has several layers made up of layers of tracks 5a to 5d and insulation layers 6a to 6c such as 7a to 7b composed. In this special layer structure, the insulation layers can be subdivided into such ( 6a to 6c ), which are the individual circuits 1 . 2 separate from each other and such ( 7a to 7b ), which provide isolation within each circuit. The insulation layers 7a to 7b allow a variety of conductor structures, such as spiral windings on the location 5a that with a return conductor on the location 5b can be provided. The layers within a circuit can be electrically contacted 8th as be connected, for example, a Durchlochkontaktierung.

In the layer structure of the intrinsically safe transformer off 1 are the two circuits 1 . 2 or potential groups 1 . 2 electrically isolated from each other via a first solid insulation or solid insulation of thickness T1 (insulation 1). Here, the insulation thickness T1 is greater than or equal to the protection level required for the protection class, which is a necessary condition for an intrinsically safe transformer. The required level of protection thus corresponds to the minimum insulation distance T0, also referred to as the required insulation thickness or minimum insulation thickness. Because the core 4 is considered as a conductive body, in addition to the required first insulation between the primary and secondary side (insulation 1), a second insulation between the individual turns of the circuits and the core 4 be ensured (isolation 2). The second insulation can be divided into two parts T21 and T22, wherein the sum of the thicknesses T21 and T22 of the second insulation is also greater than or equal to the minimum insulation thickness T0 required for the protection class. For example, the two parts of the second insulation have an equal thickness.

An additional constraint for the interpretation of a transfer is, for example, in DIN EN 60079-11 so required that neither of the two shares T21 and T22 may fall below a minimum proportion of the total second insulation, for example one third of the second insulation. As a rule, the two components T21 and T22 are chosen to be identical and equal to half the first insulation for reasons of symmetry.

The classic PCB transformer 10 is with a magnetic core 4 equipped to achieve the best possible magnetic conductivity combined with a maximum shielding effect. Here, the magnetic core encloses 4 the circuit board 9 or parts of the circuit board with or without an air gap and is both above and below the circuit board 9 and each side of the circuit board 9 arranged. Since the production-related thicknesses TK1 and TK2 of the magnetic core 4 above and below the circuit board 9 typically greater than the required insulation thickness T0 with TK1, TK2 T0 (when T0 is, for example, 1 mm), this results in a total thickness of the printed circuit board transformer 10 at least four times the minimum insulation thickness T0. Here, the layer thicknesses of the tracks ( 5a to 5d ) and the thicknesses of the additional insulation layers ( 7a to 7b ) not yet included.

If the required thickness of the insulation layer T0 is, for example, 1 mm, then the total thickness of the conventional printed circuit board transformer is 10 greater than 4 mm. In many applications, the thickness is between 6 mm and 12 mm with a total area of about 6 cm ² to 8 cm ² .

2 shows a schematic representation of a conventional transformer 10 with three circuits 1 . 2 . 3 , 2 illustrates a layer structure of a circuit board 9 in the case of three safely galvanically isolated circuits 1 . 2 . 3 as a further embodiment, starting from 1 , The turns of the first circuit 1 or the first potential group 1 are in this example as three tracks levels 5a to 5c executed while the turns of the circuit 2 and the circuit 3 each with two tracks 5d and 5e respectively. 5f and 5g are executed.

As a consequence of the previous concept of an intrinsically safe operation, for safe galvanic isolation of all three circuits 1 . 2 . 3 three insulation layers with a first insulation (insulation 1), a second insulation (insulation 2) and a third insulation (insulation 3) are used, each of which must be greater than or equal to the minimum insulation thickness T0 must be selected. This consequently increases the overall thickness of the transformer 10 , Generally, the total insulation thickness at N is surely galvanically isolated circuits at least N × T0. The total thickness of the transformer 10 takes into account further layer thicknesses, such as the conductor track thickness 5a to 5g and the other insulation layers 7a to 7c ,

3 shows a schematic representation of a transformer 20 according to an embodiment of the invention with a first circuit 1 and a second circuit 2 , which are galvanically isolated from each other.

The height of the transformer 20 can be reduced according to the invention, since the originally closed or almost closed magnetic core 4 who in 1 and 2 is shown is omitted. Rather, the magnetic core 4 of different proportions 4a and 4b formed, for example, are formed from ferrite plates and can cause a shielding effect of the magnetic field substantially.

By the separation of the core 4 in two sub-kernels 4a . 4b can on the second isolation (isolation 2) of the 1 or to the third isolation (isolation 3) of the 2 between the circuits 1 . 2 . 3 and the core 4 be waived. It is intended as in 3 showed that no connection between the considered as electrically conductive core shares 4a . 4b is available. Here, the core shares 4a . 4b the respective closest potential groups 1 . 2 be assigned.

The present invention thus uses an approach described in more detail below for reducing the total thickness of the in 1 and 2 shown known layer structure. As described amounts to known dimensions according to 1 and 2 the total insulation thickness is at least N × T0, where N is the number of safely separate circuits 1 . 2 . 3 and T0 is the minimum insulation thickness in the insulating medium, which is taken into account for the protection level.

By the described separation of the core 4 can on the insulation layers 6a and 6c from the 1 respectively. 6a and 6d from the 2 can be omitted and the total thickness of the transformer is reduced accordingly by at least 1 × T0. In general, the total insulation thickness can thus be reduced from at least N × T0 to (N-1) × T0.

According to the invention, the total insulation thickness becomes (N-1) × T0 by separating the magnetic core 4 on two parts 4a . 4b reduced. In the special case of two (N = 2) isolating circuits 1 . 2 For example, the minimum total isolation thickness is reduced from 2xT0 to 1xT0 by a reduction factor of two. Generally, the reduction factor is N / (N-1).

Advantageously, the minimum distance corresponds to all core components 4a . 4b also at least the required minimum insulation to an intrinsically safe transformer 20 provide. It should be noted that the required separation distance between the core portions may vary depending on the isolation medium.

4 shows a further embodiment of a transformer according to the invention 20 , Here, the transformer points 20 a first circuit 1 , a second circuit 2 and a third circuit 3 on. The overlaps of the core shares 4a . 4b to the circuit board 9 of the transformer 20 in 4 are different compared to 3 , Furthermore, in 4 the second circuit 2 shifted to the right, so offset to the first circuit 1 , Thus, in this embodiment, the circuits are 1 . 2 . 3 aligned differently.

5 and 6 show a further embodiment of an intrinsically safe transformer according to the invention 20 in different perspectives.

In 5 are three different views of a transformer 20 shown. In 5 (a) is the complete transformer 20 to see in 5 (b) is the transformer 20 without the core parts 4a . 4b represented and in 5 (c) is also the circuit board 9 away.

In 6 are all layers of the transfer 20 out 5 shown in exploded view. The circular basic shape of the coils 5 and 6 can also be modified such that there is a rectangular basic shape with spiral turns. Accordingly, it may be useful in this case, even the basic shape of the core parts 4a . 4b rectangular shape.

In 5 and 6 are the two circuits of the potential groups 1 and 2 on different layers of the circuit board 9 arranged. Both potential groups are isolated 1 . 2 over the insulation layer 6b with the thickness T1 which is greater than or equal to the minimum insulation thickness T0 of the respective protective group. In the case of spiral coils, the inner coil can be contacted 8th be provided and on an additional location 5b . 5c to be led back.

to increase the electromagnetic coupling between the two coils 1 . 2 and for reducing or minimizing stray fields may be above and below the circuit boards 9 magnetic materials are attached. In the embodiments of the 5 and 6 this is due to two cylindrical ferrite plates 4a and 4b realized. The total thickness of the transformer thus formed 20 For example, 3.6 mm while the extent in the x-direction and y-direction, for example, each about 20 mm.

In the described transformers or transformers 20 of the 3 to 6 can be provided that the individual turns provided with the appropriate safety distances are superimposed in a special layer structure. Thus, there are insulation layers (first layers) for the required separation distances and further substantially thinner insulation layers (additional layers), which serve, for example, the return of a conductor within a winding. This is necessary, among other things, when a spiral winding on another layer must be led from the inside to the outside. The thus formed transformer or transformer can all of Standard EN 60079-11 meet the required safety distances and at the same time offers the functionality in terms of energy and / or data or signal transmission.

LIST OF REFERENCE NUMBERS

1

Circuit or potential group

2

Circuit or potential group

3

Circuit or potential group

4

magnetic core

4a

first part of a magnetic core

4b

second part of a magnetic core

5a to 5g

Wiring layers

6a to 6d

Insulation layers between the circuits

7a to 7c

Insulation layers within a circuit

8th

electrical contact

9

circuit board

10

conventional transformer or transformer

20

inventive transformer or transformer

T0

Minimum insulation / protection / insulation thickness

TK1

first thickness of a magnetic core

TK2

second thickness of a magnetic core

T1

first insulation thickness

T2

second insulation thickness

T21

Distance / insulation thickness

T22

Distance / insulation thickness

T31

Distance / insulation thickness

T32

Distance / insulation thickness

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102005041131 A1 [0006]
• US 2011/0140824 A1 [0007]
• US 2011/0095620 A1 [0008]
• EP 0715322 A1 [0009, 0036]

Cited non-patent literature

• DIN EN 60079-11 [0004]
• Standard DIN EN 60079-11 [0018]
• DIN EN 60079-11 [0039]
• Standard EN 60079-11 [0057]

Claims (10)

Planar intrinsically safe transformer ( 20 ) comprising a layer structure with a plurality of circuits ( 1 . 2 . 3 ), wherein a first circuit ( 1 ) and at least one second circuit ( 2 ) galvanically separated from each other by at least one insulating layer ( 6b . 6c ), a first magnetic layer ( 4a ) and a second magnetic layer ( 4b ), wherein the first magnetic layer ( 4a ) defines a first side of the layer structure and the second magnetic layer ( 4b ) delimits a second side of the layer structure , characterized in that the first magnetic layer ( 4a ) and the second magnetic layer ( 4b ) are separated from each other and can be assigned to different potential groups. Transformer according to claim 1, characterized in that the first circuit ( 1 ) is arranged on a first layer and the at least second circuit ( 2 ) is arranged on a second layer, wherein between the first layer and the at least second layer in each case the insulating layer ( 6b . 6c ) is arranged. Transformer according to Claim 1 or Claim 2, characterized in that the first circuit ( 1 ) to the first magnetic layer ( 4a ) and the second circuit ( 2 ) to the second magnetic layer ( 4b ) adjoins. Transformer according to one of claims 1 to 3, characterized in that the first circuit ( 1 ) and the second circuit ( 2 ) have a minimum isolation distance T0 to each other and at no geometric location between the first circuit and the second circuit of the minimum isolation distance T0 is exceeded. Transformer according to claim 4, characterized in that a total insulation thickness between the first magnetic layer ( 4a ) and the second magnetic layer ( 4b ) (N - 1) × T0, where T0 is the minimum isolation distance and N is the number of electrically isolated circuits ( 1 . 2 . 3 ). Transformer according to one of claims 1 to 5, characterized in that at least one circuit ( 1 . 2 . 3 ) of two conductive layers ( 5a . 5b ) and between the conductive layers ( 5a . 5b ) at least one insulating layer ( 7a ) is arranged. Transformer according to claim 6, characterized in that the conductive layers ( 5a . 5b ) form one or more windings of a coil by the conductive layers ( 5a . 5b ) are connected to an electrical connection (8). Transformer according to one of claims 1 to 7, characterized in that a total height of the transformer ( 20 ) four times the total insulation distance of the insulation ( 6b ) formed between a primary side as a first circuit ( 1 ) and a secondary side formed as a second circuit ( 2 ) does not exceed. Transformer according to one of claims 1 to 8, characterized in that at a required minimum insulation thickness T0 of the insulating layer ( 6 ) of about 1 mm the total thickness of the transformer ( 20 ) is not more than about 4 mm. Transformer according to one of claims 1 to 9, characterized in that the minimum insulation thickness T0 is at least about 0.25 mm, preferably about 1 mm.

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