Planar transformer layer, assembly of layers for planar transformer, and planar transformer

Abstract

A planar transformer layer is provided. The planar transformer comprises distinct electrical connections and thermal connections. An assembly of layers for a planar transformer is also provided. An electronic energy conversion equipment item for a satellite provided with at least one planar transformer is also provided.

Claims

1. An assembly of layers comprising a plurality of primary planar transformer layer turns of windings, each of the primary planar transformer layer turns of windings comprising distinct electrical connections and thermal connections having a hole in primary layers, the hole with an extension towards an interior of the layer based on a top view to locally maximize the heat flux towards a heat sink, wherein the extension is narrower than the hole.

2. The planar transformer layer according to claim 1, wherein a thermal connection of the thermal connections is comb-shaped.

3. The assembly of layers of claim 1, further comprising: a plurality of secondary planar transformer layers without distinct electrical and thermal connections, wherein the secondary planar transformer layers are separated from the primary planar layer turns of windings and covered by a dielectric material, except for the thermal connection or connections of the plurality primary planar transformer layers.

4. A planar transformer comprising at least one assembly of layers including: plurality of primary planar transformer layer turns of windings, each of the primary planar transformer layer turns of windings comprising distinct electrical connections and thermal connections having a hole in primary layers, the hole with an extension towards an interior of the layer based on a top view to locally maximize the heat flux towards a heat sink, wherein the extension is narrower than the hole; and a plurality of secondary planar transformer layers without distinct electrical and thermal connections, wherein the secondary planar transformer layers are separated from the primary planar transform layer turns and covered by a dielectric material, except for the thermal connection or connections of the plurality primary planar transformer layers.

5. The planar transformer according to claim 4, wherein a plurality of assemblies stacked one on top of the other, in which the thermal connections of the primary layers are connected to a heat sink.

6. The planar transformer according to claim 5, wherein the heat sink comprises a cold source and a dielectric part.

7. The planar transformer according to claim 6, wherein the cold source is arranged on the outer part of the heat sink, surrounding the dielectric part.

8. The planar transformer according to claim 5, further comprising a magnetic core and an associated fixing element.

9. The planar transformer according to claim 1, wherein the extension extends only towards the interior of the layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood on studying a few embodiments described as nonlimiting examples and illustrated by the attached drawings in which:

(2) FIG. 1 schematically illustrates a planar transformer according to the prior art;

(3) FIG. 2 schematically illustrates a planar transformer according to one aspect of the invention;

(4) FIGS. 3 and 4 schematically illustrate a planar transformer layer according to two aspects of the invention;

(5) FIGS. 5 to 11 schematically illustrate an embodiment of a transformer according to one aspect of the invention.

(6) In the different figures, the elements that have the same references are identical.

DETAILED DESCRIPTION

(7) FIG. 2 represents a planar transformer according to one aspect of the invention, in which an individual winding 6 comprise one or more layers of copper 7 of which at least one 7a performs the thermal function. These layers of copper 7 are electrically insulated for example by a dielectric insulation 8. In this particular case an individual winding or individual assembly 6 comprises, for example, a layer 7a performing the thermal function, and two others 7b, conventional, not performing it.

(8) The left-hand part of FIG. 2 represents, by arrows, the diffusion of the thermal energy in the planar transformer by the layers 7a, of which a part is surrounded by a dielectric 9 in proximity to a cold source 10. Thus, a continuous thermal path, or heat sink, is created between the windings 6 and the cold source 10. The thermal efficiency of the cold source 10 plays an important role in obtaining the final efficiency of the transformer.

(9) The reduction of thermal resistance of the electrical conductors of the transformer makes it possible to significantly increase (more than double) the transferred power, despite an electrical output voltage multiplied by five, without increasing the volume occupied by the transformer.

(10) FIG. 3 shows a planar transformer layer 7a comprising distinct electrical connections 12 and thermal connections 13.

(11) The thermal connections 13, in this case four of them per layer 7a, comprise a hole 14, making it possible to fixedly hold together a plurality of layers 7a.

(12) For example, the holes 14 of the thermal connections 13 can comprise an extension 14a towards the interior of the layer 7a. These extensions 14a make it possible to locally maximize the heat flux towards the cold source to do so given the constraint of a mechanical fixing of the transformer by means of screws.

(13) As a variant, as illustrated in FIG. 4, the thermal connections can be comb-shaped, and thus without holes, which makes it possible to adapt to another transformer fixing means.

(14) Any other type of distinct thermal connection can of course be envisaged, regardless of its shape, that makes it possible, by means of another element, to fixedly link a stacking of layers or of assemblies of layers.

(15) Hereinafter in the description, in a nonlimiting manner, only thermal links 13 with holes 14 will be described.

(16) The rest of the description illustrates an exemplary embodiment of the invention.

(17) The winding production technology is based on flexible circuits made up of an electrical circuit on a layer encapsulated between two flexible insulation layers.

(18) The windings produced are then stacked.

(19) As illustrated in FIG. 5, in order to easily perform the assembly of a transformer, it is possible to produce an assembly comprising, for example, a planar transformer layer 7a comprising distinct electrical connections 12 and thermal connections 13 and two conventional planar transformer layers 7b, directly by the manufacturer of the circuit in order to obtain an individual winding or assembly of layers.

(20) FIG. 6 represents a stack of a plurality of assemblies of layers according to FIG. 5, which constitutes the assembly of the windings of the transformer according to an aspect of the invention.

(21) In order to drain the heat flux leaving the primary turns or, in other words, the turns or layers 7a, it is necessary to create a continuous path to the flat base of the transformer.

(22) The assembly of the transformer is performed as follows.

(23) As illustrated in FIG. 7, after having stacked assemblies of individual layers or windings 6 on a rig, the four heat-sinking placements, here disposed in proximity to the corners, are closed by means of capping pieces made of aluminium 16 and a comb of dielectric material 17. These pieces 16 and 17 play a role of sealing and reproducibility of the stacking. Once this operation is finished, the feet of the transformer which extend the exchange to the cold plate or cold source 10, are slipped. In effect, in the proposed assembly, there is a break in the link between the transformer and the cold source. More generally, this function could directly form part of the cold source which would have the effect of further improving the thermal efficiencies.

(24) Next, as illustrated in FIG. 8, the four feet 16, 17 of a dielectric resin 18 have a good thermal conductivity. The design takes into account the voltages involved between the individual windings 6 in order to guarantee the electrical insulation.

(25) Finally, ferrite cores 19 (magnetic cores) are placed around the winding made up of the stacking of the individual windings 6. The present transformer proposes completely decoupling the heat flux from the losses by the copper 6 and from the losses by the irons 19. Consequently, the ferrites 19 are held mechanically by a piece 20, for example made of aluminium, also serving as a heat sink to the flat base.

(26) FIG. 10 shows the cutting plane of FIG. 8 to obtain the cross-sectional view of FIG. 11.