Patent Publication Number: US-11393620-B2

Title: Transformer apparatus and method for manufacturing it

Description:
RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 371 of the filing date of International Patent Application No. PCT/EP2017/061703, having an international filing date of May 16, 2017, which claims priority to German Application No. 10 2016 211 085.3, filed Jun. 22, 2016, the contents of both of which are incorporated herein by reference in their entirety. 
     The present invention relates to a transformer apparatus, to a method for manufacturing a transformer apparatus, to a corresponding apparatus and to a corresponding computer program product. 
     Transformers with galvanic isolation can be manufactured e.g. with copper wire windings around a ferrite core on the primary and on the secondary side. Another possibility to accomplish this would be e.g. by means of planar transformers, whose windings can be implemented within a printed circuit board. 
     In this context, the present invention provides an improved transformer apparatus, an improved method for manufacturing a transformer apparatus, an improved apparatus as well as an improved computer program product in accordance with the main claims. Advantageous embodiments can be derived from the sub-claims and from the following description. 
     According to embodiments of the present invention, it is particularly possible to provide a combination of a press-fit element with a primary winding and a circuit-board-based planar transformer with a secondary winding and to thereby implement a hybrid transformer or a hybrid planar transformer. In this way it is possible to e.g. combine the advantages of conventionally wound transformers with the advantages of planar transformers. It is thus possible to arrange in particular primary windings and secondary winding in structurally separate units which are coupled to each other, wherein at least one of these can be configured as a circuit board. 
     When compared to a transformer that is completely made in a planar configuration, it is advantageously possible to reduce the complexity of a circuit board configuration due to the combination particularly in accordance with the embodiments of the present invention. Furthermore, by eliminating e.g. the primary winding in the circuit board, it is possible to omit among other things the buried through-hole platings or the so-called buried vias within the circuit board and thus to simplify the configuration of the circuit board. In addition to this, it is also possible to particularly implement creepages and clearances by means of the insert element that is made of e.g. plastic material and these do not need not be considered within the circuit board. Depending on a ratio of the number of the windings, it is also possible to achieve a reduction of the amount of layers of the printed circuit board or of the amount of layers within the printed circuit board, for example by at least 2 or 4 layers, depending on the ratio of the number of the windings of only e.g. 5:1:1 or 16:1:1. It is particularly possible to increase a degree of the copper filling of an available winding window in the transformer core. 
     Compared to conventionally wound transformers, it is e.g. possible to improve among other things a cooling or heat dissipation, to simplify the manufacturing, to implement creepages and clearances in a simplified way, to implement an electrical contacting in a different manner than by means of screw connections or solder joints, to simplify the configuration and connection techniques for high power applications and to reduce a leakage inductance. 
     When compared to planar transformers that are configured in a single circuit board, it is possible to particularly reduce the number of layers of the printed circuit board in order to utilize the winding window. Furthermore, primary windings for example, onto which high voltage potential may be supplied, only need to fulfill reduced requirements for creepages and clearances or isolation distances. 
     A transformer apparatus is presented, wherein the transformer apparatus comprises a transformer core, at least one primary winding and at least one secondary winding, wherein the transformer apparatus features an insert element, in which the at least one primary winding is arranged, and a printed circuit board, in which the at least one secondary winding is arranged, wherein the insert element, the circuit board and the transformer core can be coupled to each other or are coupled to each other. 
     The transformer apparatus may be implemented as a transformer apparatus with galvanic isolation. The transformer core may be implemented as a ferrite core or as an iron core. It can be arranged that the insert element can be mechanically and optionally in addition to this also electrically coupled to the circuit board or that they are coupled to each other. 
     According to one embodiment, the insert element may comprise at least one stranded wire and an electrically insulating material. In this case, the at least one stranded wire may be embedded into the electrically insulating material. The electrically insulating material may comprise a plastic material. The at least one stranded wire may be a high-frequency stranded wire. Such an embodiment provides the advantage that, particularly due to a primary winding on the basis of a high-frequency stranded wire, it is possible to achieve a reduction of primary passage losses by means of an increased overall wire cross-section. Creepages and clearances can also be implemented in a simple manner by means of an embedding into a plastic carrier. 
     Alternatively, the insert element may comprise a further circuit board, into which the at least one primary winding can be arranged. Such an embodiment offers the advantage that, with a reduced current load at the at least one primary winding, the insert element can also be implemented in form of a further or additional circuit board as an insert element. The number of layers of the two circuit boards can also be reduced by means of this embodiment variant. 
     The insert element can furthermore feature at least one press-fit element that is to be pressed into the printed circuit board in order to couple the insert element with the printed circuit board. The at least one press-fit element can be formed e.g. from a metallic material. Such an embodiment provides the advantage that the insert element, which is e.g. designed as a plastic carrier with the at least one primary winding, and the circuit board can be connected to each other in an easy, quick and reliable manner by means of a press-fitting technique. 
     To accomplish this, the insert element may feature a plurality of press-fit elements. Two press-fit elements of the plurality of press-fit elements may therefore be formed as electrical connections for the primary winding. Thus, two press-fit elements can be electrically connected to the primary winding and can be electrically contacted by means of a press-fitting into the circuit board. Such an embodiment presents the advantage that space and effort can be utilized, wherein a dual function by way of a mechanical and electrical connection can also be partially achieved by means of the press-fit elements. 
     The printed circuit board can also feature a plurality of layers. To accomplish this, the at least one secondary winding can be formed as at least one layer of the circuit board. The circuit board can be designed merely by way of an example in particular with four layers comprising optional intermediate layers. Such an embodiment offers the advantage that the at least one secondary winding can be implemented in a space-utilizing manner. 
     The circuit board may furthermore feature at least one through-hole plating. In this case, the at least one through-hole plating can extend through all the layers of the circuit board. Such an embodiment offers the advantage that particularly buried through-hole platings within the circuit board can be omitted, and the cost for configurating of the printed circuit board can be reduced in this way. 
     Furthermore, the transformer apparatus may comprise at least one heat sink to dissipate heat from the circuit board and additionally or alternatively also from the insert element. To accomplish this, the circuit board can be arranged or is arranged between the at least one heat sink and the insert element. Such an embodiment provides the advantage that a heat dissipation or cooling of the transformer apparatus can be improved. 
     The transformer apparatus may hereby also feature a heat conducting layer to dissipate the heat from the circuit board to the at least one heat sink. To accomplish this, the heat conducting layer can be arranged or is arranged between the circuit board and the at least one heat sink. The heat conducting layer can be designed as a heat conducting foil on both sides. Such an embodiment provides the advantage that a heat dissipation as well as a heat transfer can be further improved. 
     A method for the manufacturing of a transformer apparatus is presented, wherein the method comprises a step of forming of an insert element, in which at least one primary winding of the transformer apparatus is arranged, a step of configuring a circuit board, in which at least one secondary winding of the transformer apparatus is arranged, and a step of a mutual coupling of the insert element, the circuit board and a transformer core. 
     By means of carrying out the method, an embodiment of the above-mentioned transformer apparatus can be manufactured in an advantageous manner. The step of forming and the step of configurating can hereby be carried out at the same time or at least partially in a sequential manner in any desired order. It is also possible that a partial assembly can be carried out at the transformer core in the step of forming and additionally or alternatively in the step of configurating. 
     According to one embodiment, at least one stranded wire can be embedded into an electrically insulating material in the step of forming. The electrically insulating material may refer to a plastic material. Such an embodiment provides the advantage, that the insert element can be implemented in a constructively simple and cost efficient manner. 
     Alternatively, another circuit board with the at least one secondary winding can be constructed in the step of forming. The further circuit board can be designed with multiple layers. To accomplish this, the at least one secondary winding can be formed as at least one layer of the additional circuit board. Such an embodiment offers the advantage that, in particular when there is a reduced current load at the at least one primary winding, the insert element can be implemented with at least one secondary winding that is configured in a planar manner. 
     A further apparatus is presented that is configured to carry out the steps of an embodiment of the before-mentioned method. 
     The apparatus may refer to an electrical device that processes electrical signals, such as e.g. sensor signals, and which sends out control signals in dependence of this. The apparatus may feature one or more suitable interfaces, which can be configured in a hardware and/or software manner. For a hardware configuration, the interfaces may e.g. be part of an integrated circuit, in which the functions of the apparatus are implemented. The interfaces may also refer to individual, integrated circuits or at least partially consist of discrete components. For a software configuration, the interfaces can be software modules, which are present on e.g. a microcontroller in addition to other software modules. 
     A computer program product with a program code that can be stored on a machine-readable carrier such as e.g. a semiconductor memory, a hard drive or an optical storage and which is used to carry out the method in accordance with one of the above-described embodiments when the program is executed on a computer or on a device is also advantageous. 
    
    
     
       The invention will be explained in more detail by way of examples with reference to the attached drawings. The drawings show: 
         FIG. 1  a schematic sectional depiction of a planar transformer; 
         FIG. 2  a schematic sectional depiction of a transformer apparatus in accordance with one design example of the present invention; 
         FIG. 3  a schematic sectional depiction of a partial section of the transformer apparatus from  FIG. 2 ; 
         FIG. 4  a schematic sectional depiction of the insert element of the transformer apparatus from  FIG. 2 ; 
         FIG. 5  a schematic sectional depiction of the circuit board of the transformer apparatus from  FIG. 2 ; 
         FIG. 6  a schematic depiction of the circuit board of the transformer apparatus from  FIG. 2 ; 
         FIG. 7  a schematic depiction of the insert element of the transformer apparatus from  FIG. 2 ; 
         FIG. 8  a flow chart of a method for the manufacturing in accordance with one design example of the present invention; and 
         FIG. 9  a schematic depiction of an apparatus in accordance with one design example of the present invention. 
     
    
    
     In the following description of preferred design examples of the present invention, identical or similar reference signs are used for the elements that are depicted in the various figures and that function in a similar manner, wherein a repeated description of these elements will be omitted. 
       FIG. 1  depicts a schematic sectional depiction of a planar transformer  100 . In other words,  FIG. 1  depicts merely an 8-layer circuit board configuration of a planar transformer  100  by way of an example. In this example, the primary winding and the secondary winding of the planar transformer  100  are arranged within one single circuit board. 
     With reference to the depiction in  FIG. 1 , the circuit board configuration of the PCB comprises the following layer from top to bottom: a first layer  101 , a semi-finished product layer  110  or prepreg layer  110  (prepreg=preimpregnated fibers), a second layer  102 , a core layer  120 , a third layer  103 , another semi-finished layer  110 , a fourth layer  104 , another core layer  120 , a fifth layer  105 , a further semi-finished layer  110 , a sixth layer  106 , a further core layer  120 , a seventh layer  107 , a further semi-finished layer  110  and an eighth layer  108 . 
     The second layer  102 , the third layer  103 , the sixth layer  106  and seventh layer  107  are hereby used for the primary winding, wherein the first layer  101 , the fourth layer  104 , the fifth layer  105  and the eighth layer  108  are used for the secondary winding. 
     The circuit board configuration of the circuit board furthermore features by way of an example only one through-hole plating  130  and it exemplifies only two buried through-hole platings  140  or so-called buried vias. 
       FIG. 2  depicts a schematic sectional depiction of a transformer apparatus  200  in accordance with one design example of the present invention. The transformer apparatus  200  comprises a transformer core  210  that is formed e.g. of ferrite. In addition to this, the transformer apparatus  200  comprises an insert element  220  in which at least one primary winding of the transformer apparatus  200  is arranged or formed. The transformer apparatus  200  also comprises a circuit board  230  in which at least one secondary winding of the transformer apparatus  200  is arranged or formed. 
     The insert element  220 , the circuit board  230  and the transformer core  210  are mechanically coupled to each other. To accomplish this, the insert element  220  and the circuit board  230  are at least partially arranged within the transformer core  210 . The insert element  220  and the circuit board  230  represent separate, mutually coupled assemblies or elements. In this way the at least one primary winding and the at least one secondary winding are arranged within separate elements. In other words, the at least one primary winding is implemented by means of the insert element  220  wherein the at least one secondary winding is implemented by means of the circuit board  230 . The insert element  220  and the circuit board  230  will be dealt with in more detail in the following with reference to the following figures. 
     In accordance with the design example of the present invention that is depicted in  FIG. 2 , the insert element  220  comprises a plurality of press-fit elements  225 , from which only two press-fit elements  225  are explicitly shown for a better representation. The press-fit elements  225  are formed in order to be pressed into the circuit board  230 , in order to couple the insert element  220  with the circuit board  230 . In the depiction of  FIG. 2 , the press-fit elements  225  are pressed into circuit board  230 . 
     In accordance with the design example of the present invention as it is depicted in  FIG. 2 , the transformer apparatus  200  features by way of example a heatsink  240  for the dissipation of heat from the circuit board  230  and/or from the insert element  220 . The circuit board  230  is hereby arranged between the heat sink  240  and the insert element  220 . The heat sink  240  is at least coupled thermally with the circuit board  230 . In addition to this, the transformer apparatus  200  hereby features a heat conducting layer  250  for the dissipation of heat from circuit board  230  to the heat sink  240 . The heat conducting layer  250  is arranged between the circuit board  230  and the heat sink  240 . The heat conducting layer  250  is hereby designed e.g. as heat conducting foil. The heat sink  240  is thus coupled thermally at least to the circuit board  230  via the heat conducting layer  250 . 
       FIG. 3  depicts a schematic sectional depiction of a partial section of the transformer apparatus from  FIG. 2 . In the partial section that is depicted in  FIG. 3 , the transformer core  210 , the insert element  220  and the circuit board  230  from the transformer apparatus are shown. The primary winding of the transformer apparatus is arranged within the insert element  220 . The secondary winding of the transformer apparatus is arranged within the circuit board  230 . 
       FIG. 4  depicts a schematic sectional depiction of the insert element  220  of the transformer apparatus from  FIG. 2 . The primary winding  460  is also explicitly shown. The primary winding  460  is implemented by using at least one stranded wire  422  or a high frequency stranded wire  422 , which is embedded into an electrically insulating material  424  as an overmolding for electrical insulation. The electrically insulating material  424  refers to e.g. a plastic material. The insert element  220  thus comprises the stranded wire  422  or the high frequency stranded wire  422  and the electrically insulating material  424 . The primary winding  460  is created by means of the stranded wire  422  or the high frequency stranded wire  422 . 
     According to another design example, the insert element  220  can comprise another circuit board or be implemented as an additional circuit board, in which the primary winding is arranged. 
       FIG. 5  depicts a schematic sectional depiction of the circuit board  230  of the transformer apparatus from  FIG. 2 . The circuit board  230  exemplifies an 4-layer circuit board configuration of a planar transformer with a secondary winding and without a primary winding. 
     With reference to the depiction in  FIG. 5 , the circuit board configuration of the circuit board comprises the following layers from top to bottom: a first layer  531 , a core layer  535 , a second layer  532 , a semi-finished product layer  536  or prepreg layer  536  (prepreg=preimpregnated fibers), a third layer  533 , a further core layer  535  and a fourth layer  534 . The circuit board  230  thus features a plurality of layers  531 ,  532 ,  533 ,  534 ,  535  and  536 . The at least one secondary winding of the transformer apparatus is formed as at least one layer  531 ,  532 ,  533  and/or  534  of the circuit board. 
     The circuit board  230  furthermore exemplifies merely one through-hole plating  537 . The through-hole plating  537  extends through-out all layers  531 ,  532 ,  533 ,  534 ,  535  and  536  of the circuit board  230 . 
       FIG. 6  depicts a schematic depiction of the circuit board  230  of the transformer apparatus from  FIG. 2 . The circuit board  230  is hereby shown in a schematic top view or partially transparent top view. In  FIG. 6 , a secondary winding  670  is explicitly shown within the circuit board  230 . Secondary winding  670  is formed or implemented as at least one layer, or in at least one layer of the circuit board  230 . 
       FIG. 7  depicts a schematic depiction of the insert element  220  of the transformer apparatus from  FIG. 2 . The insert element  220  is hereby shown in a schematic top view or partially transparent top view. From the insert element  220 , a plurality of press-fit elements  225  and  725 , the stranded wire  422  or the high frequency stranded wire  422 , the electrically insulating material  424  and the primary winding  460  are depicted in  FIG. 7 . 
     The primary winding  460  is hereby implemented in the insert element  220  by means of the high frequency stranded wire  422 . The high-frequency stranded wire  422  is hereby wound several times. The high frequency stranded wire  422  is embedded or overmolded into the electrically insulating material  424 . 
     The insert element  220  features a plurality of press-fit elements  225  and  725 . More specifically, the insert element  220  comprises only by way of example four press-fit elements  225  and  725 . Of these, the example shows that only two press-fit elements  225  are designed for fastening the insert element  220  or for press-fitting the insert element  220  into the circuit board of the transformer apparatus. By way of example, two other press-fit elements  725  of the plurality of press-fit elements  225  and  725  are designed as electrical connections for the primary winding  460  as well as for fastening the insert element  220  or for press-fitting the insert element  220  into the circuit board of the transformer apparatus. The press-fit elements  725  are thus used both to electrically contact the primary winding  460  as well as to mechanically fix the insert element  220 . In other words, electrical connections for the primary winding  460  are thus connected or combined with two press-fit elements  725 . 
       FIG. 8  depicts a flow chart of a method  800  for the manufacturing or a manufacturing method  800  in accordance with one design example of the present invention. The manufacturing method  800  can be carried out in order to produce a transformer apparatus. In more exact terms, manufacturing method  800  can be carried out to produce the transformer apparatus from  FIG. 2  or a similar transformer apparatus. 
     The manufacture  800  comprises a step  810  of forming an insert element, in which at least one primary winding of the transformer apparatus is arranged. The manufacturing method  800  also comprises a step  820  of configurating a printed circuit board, in which at least one secondary winding of the transformer apparatus is arranged. The manufacturing method  800  furthermore includes a step  830  of coupling the insert element, the circuit board, and a transformer core together. 
     The step  810  of forming and the step  820  of configurating can be carried out in any desired order and additionally or alternatively at least partially at the same time. 
     According to one design example, at least one stranded wire can be embedded into an electrically insulating material in the step  810  of forming. Alternatively, another circuit board with the at least one secondary winding can be configured in the step  810  of forming. 
       FIG. 9  depicts a schematic depiction of an apparatus  900  in accordance with one design example of the present invention. Apparatus  900  is designed as a control unit. Apparatus  900  is configured to initiate or control the manufacturing of a transformer apparatus. More specifically, apparatus  900  is designed to initiate or control the manufacturing of the transformer apparatus from  FIG. 2  or of a similar transformer apparatus. 
     Apparatus  900  is connected to a manufacturing system  950  in such a manner, that a transmitting of signals can be carried out. The manufacturing system  950  features by way of example only one first machine  960 , one second machine  970  and one third machine  980 . 
     Apparatus  900  comprises a forming device  910 , which is designed to control the first machine  960  in order to form the insert element, in which at least one primary winding of the transformer apparatus is arranged. Apparatus  900  furthermore comprises a configuration device  920 , which is designed to control the second machine  970  for the configurating of a circuit board, in which at least one secondary winding of the transformer apparatus is arranged. Furthermore, apparatus  900  comprises a coupling device  930 , which is designed to control the third machine  970  for the mutual coupling of the insert element, the circuit board and a transformer core. 
     If a design example includes an “and/or” linking between a first characteristic and a second characteristic, this can be read in such a way that the design example according to one embodiment features both the first characteristic as well as the second characteristic and according to another embodiment either only the first characteristic or only the second characteristic. 
     LIST OF REFERENCE SIGNS 
     
         
           100  planar transformer 
           101  first layer 
           102  second layer 
           103  third layer 
           104  fourth layer 
           105  fifth layer 
           106  sixth layer 
           107  seventh layer 
           108  eighth layer 
           110  semi-finished layer or prepreg layer 
           120  core layer or core 
           130  through-hole plating 
           140  buried through-hole plating 
           200  transformer apparatus 
           210  transformer core 
           220  insert element 
           225  press-fit element 
           230  circuit board 
           240  heat sink 
           250  heat conducting layer 
           422  stranded wire 
           424  electrically insulating material 
           460  primary winding 
           531  first layer 
           532  second layer 
           533  third layer 
           534  fourth layer 
           535  core layer 
           536  semi-finished layer or prepreg layer 
           537  through-hole plating 
           670  secondary winding 
           725  press-fit element 
           800  method for manufacturing or manufacturing method 
           810  step of forming 
           820  step of configuring 
           830  step of mutual coupling 
           900  apparatus 
           910  forming device 
           920  configuring device 
           930  coupling device 
           950  manufacturing system 
           960  first machine 
           970  second machine 
           980  third machine