Electromagnetic coil comprising a first plate and a plurality of conductive tracks

Abstract

The first plate (15A) comprises a plurality of ordered conductive tracks (28A) winding around the first central orifice, each track defining an inner end (30A) and an outer end (35A). The inner end of each track is closer to the first central orifice than the outer end. The first plate includes a plurality of contiguous elementary patterns around the first central orifice. Each conductive track extends over at least two contiguous elementary patterns and forms, on each of said contiguous elementary patterns, a conductive strand. Each conductive strand comprises corrugations in a plane of the first plate.

Description

[0001] DESCRIPTION

[0002] TITLE: Electromagnetic coil comprising a first plate and a plurality of conductive tracks

[0003] The present invention relates to an electromagnetic coil.

[0004] The present invention relates to the field of electromagnetic coils in printed circuits. More specifically, the present invention relates to electromagnetic coils intended for use in very high frequency systems.

[0005] “Very high frequencies” means signals with a frequency between 100 kHz and 10 MHz, preferably between 100 kHz and 600 kHz.

[0006] An electromagnetic coil is a primarily inductive electrical device. However, it is well known that when the frequency of the current flowing through a coil increases, the coil also has a resistive effect on the current. This effect can be modeled by a resistor in series with a perfectly inductive coil. This effect is then a source of power loss in the circuit.

[0007] Said resistor has a resistance whose value varies according to the frequency. This evolution is characterized in two parts. In a first part corresponding to frequencies lower than a critical frequency, the resistance has a low value, called continuous resistance to characterize the fact that it is the low frequency resistance. In a second part corresponding to frequencies higher than the critical frequency, the resistance evolves approximately linearly with the frequency.

[0008] This is particularly problematic when you want to use a coil at high frequencies.

[0009] This phenomenon is notably the consequence of the fact that in a conventional coil, the distance traveled by each turn is not the same. Indeed, some internal turns have a significantly short length compared to those of the external turns.

[0010] The state of the art is known to us that the Litz coil can push the critical frequency to higher values.

[0011] Known Litz coils use a coil wire entanglement so that the distance traveled by one turn is roughly the same as the distance traveled by the other turns. To achieve this entanglement, it is known to twist the wires together. However, this coil structure is often not very applicable to printed circuit boards because of their bulkiness, which prevents embedding.

[0012] There is therefore a need for a coil that can achieve the performance of a Litz coil while minimizing the coil's footprint.

[0013] To this end, the subject of the invention is an electromagnetic coil comprising a first plate defining a first central orifice, the first plate comprising a plurality of ordered conductive tracks winding around the first central orifice, each track defining an inner end and an outer end, the inner end of each track being closer to the first central orifice than the outer end, the first plate comprising a plurality of contiguous elementary patterns around the first central orifice, each conductive track extending over at least two contiguous elementary patterns and forming on each of said contiguous elementary patterns a conductive strand, the coil being characterized in that each conductive strand comprises corrugations in a plane of the first plate.

[0014] According to particular embodiments, the electromagnetic coil according to the invention comprises one or more of the following characteristics, taken in isolation or in all technically feasible combinations:

[0015] - the coil comprises at least one second plate comprising a second central orifice, the second plate being arranged opposite the first plate and spaced therefrom in a transverse direction perpendicular to each of the plates, the second plate comprising a plurality of respective conductive tracks, ordered and winding around the second central orifice, each conductive track of the second plate defining a respective inner end and an outer end, the coil further comprising, for each end of each conductive track of the first plate, a conductive column extending in the transverse direction connecting said end to one end of a respective conductive track of the second plate;

[0016] - the or each plate comprises, between each pair of successive conductive tracks, an insulating strip whose width is constant and predefined; each conductive strand is formed of at least two conductive paths spaced from each other by an insulating path of the same width as the insulating strips; each conductive track of a respective plate is substantially aligned in the transverse direction with an insulating strip of the other plate; - each conductive track of the first plate is substantially aligned in the transverse direction with a corresponding conductive track of the second plate; and each conductive strand is formed from a plurality of circular arcs;

[0017] - the first central orifice has a circular geometry, the conductive tracks of the first plate being identical to each other except for a rotation around a center of the first central orifice of the first plate.

[0018] The invention also relates to a method for designing such an electromagnetic coil, the method being implemented by an electronic design device and comprising the following steps: receiving dimensions of the first central orifice, a number of conductive tracks on the first plate, a track width and a width of an insulating strip between two conductive tracks, generating at least one elementary pattern from the dimensions, the number of conductive tracks on the first plate, the track width and the width of an insulating strip between two tracks, received,

[0019] - concatenation of the plurality of times the same elementary pattern(s) to form the coil, and generation of a coil file suitable for transmission to a production machine for the automatic manufacture of the coil.

[0020] The invention also relates to a computer program product comprising software instructions which, when executed by a computer, implement such a design method.

[0021] The invention will be better understood by reading the following description, given with reference to the appended figures in which:

[0022] [FIG. 1] Figure 1 is a schematic representation of an electromagnetic coil according to a first embodiment of the invention;

[0023] - [FIG. 2] Figure 2 is a schematic representation of the coil along a section plane perpendicular to a transverse direction;

[0024] - [FIG. 3] Figure 3 is a detailed view of two elementary patterns of the electromagnetic coil according to the first embodiment of the invention;

[0025] - [FIG. 4] Figure 4 is a detailed view of two superimposed elementary patterns of an electromagnetic coil according to an alternative embodiment of the first embodiment;

[0026] [FIG. 5] Figure 5 is a schematic representation of an electromagnetic coil according to a second embodiment of the invention; [FIG. 6] Figure 6 is a detailed view of an elementary pattern of a first plate of an electromagnetic coil according to the second embodiment of the invention;

[0027] [FIG. 7] Figure 7 is a detailed view of an elementary pattern of a second plate of an electromagnetic coil according to the second embodiment of the invention;

[0028] [FIG. 8] Figure 8 is a detailed view of an elementary pattern of an electromagnetic coil according to an alternative embodiment of the second embodiment; and

[0029] [FIG. 9] Figure 9 is a schematic representation of a first plate of an electromagnetic coil according to a third embodiment of the invention.

[0030] Figure 1 represents an electromagnetic coil 10, also called coil 10, according to a first embodiment of the invention.

[0031] The coil 10 comprises a first plate 15A and preferably a second plate 15B spaced from the first plate 15A by a layer of insulation 16.

[0032] For the sake of readability, the insulation is not shown in Figure 1 but is clearly shown in Figure 2. Figure 2 represents a sectional view of Figure 1 along a plane perpendicular to a transverse direction T and between the two plates 15A, 15B.

[0033] The coil 10 preferably comprises two connection vias 20, also called external vias 20, each connecting the first 15A and the second 15B plates.

[0034] Optionally, the coil 10 comprises a central core (not shown), for example made of ferromagnetic material. The central core is housed in a central orifice 25A of the first plate 15A. Preferably, the central core is also housed in a central orifice 25B of the second plate 15B.

[0035] Optionally, the coil 10 further comprises a plurality of columns 22, also called internal vias 22, connecting the first plate 15A and the second plate 15B.

[0036] In the first embodiment, the first plate 15A is circular. Preferably, the first plate 15A is a disc comprising the first central orifice 25A. The first plate 15A therefore has the shape of a ring.

[0037] The first plate 15A comprises a plurality of conductive tracks 28A, ordered and winding around the first central orifice 25A.

[0038] Each track 28A defines an inner end 30A and an outer end 35A. The inner end 30A of each track 28A is closer to the first central orifice 25A than the outer end 35A. Preferably, each conductive track 28A wraps around the first orifice 20A in a first direction of rotation. In other words, each conductive track 28A extends, from its outer end 35A, towards its inner end 30A in the first direction of rotation.

[0039] The first direction of rotation is for example clockwise or counterclockwise.

[0040] Preferably, each track 28A comprises, at each end 30A, 35A, a respective conductive pad 36A.

[0041] The first plate 15A advantageously comprises between each pair of successive conductive tracks 28A, an insulating strip 37A. The plate is preferably, with the exception of the conductive tracks 28A, made of an insulating material forming the insulating strips 37A. The insulating material is for example epoxy. Alternatively, the insulating material is any type of material used for printed circuits, such as Polyimide.

[0042] The width of each insulating strip 37A is for example constant at any point of said strip 37A, and preferably predefined. This width is preferably identical for each insulating strip 37A of the first plate 15A. In other words, a distance between two contiguous tracks 28A is constant at any point of the first plate 15A.

[0043] The distance between two conductive tracks 28A is defined as being, for a point on one of the two conductive tracks 28A, the length of the shortest segment connecting this point and a point on the second conductive track 28A. By definition, this segment is perpendicular to each of the two conductive tracks 28A.

[0044] The conductive tracks 28A of the first plate 15A are preferably identical to each other except for one rotation around a center of the first central orifice 25A of the first plate 15A.

[0045] The first plate 15A comprises a plurality of contiguous elementary patterns 40A around the first central orifice 25A. Each elementary pattern 40A preferably has the shape of an angular portion of a ring.

[0046] Each conductive track 28A extends over at least two contiguous elementary patterns 40A and forms, on each of said contiguous elementary patterns 40A, a conductive strand 45A, 46A, 47A.

[0047] Preferably, the first plate 15A comprises as many elementary patterns 40A as there are conductive tracks 28A.

[0048] Each conductive track 28A is formed by the conductive strands 45A, 46A, 47A of at least two juxtaposed elementary patterns 40A.

[0049] Preferably, each elementary pattern 40A comprises a number of conductive strands 45A, 46A, 47A, equal to the number of elementary patterns 40A necessary to form a conductive track 28A. Said number is preferably an odd number. In the case where the coil 10 comprises the second plate 15B, said second plate 15B is arranged opposite the first plate 15A and spaced therefrom in a transverse direction T perpendicular to each of the plates 15A, 15B.

[0050] The second plate 15B is substantially similar to the first plate 15A. Thus, the second plate 15B is circular and comprises a second central orifice 20B. The first 20A and second 20B central orifices are opposite each other in the transverse direction T. The second plate 15B further comprises a plurality of respective conductive tracks 25B ordered winding around the second central orifice 25B. Each conductive track 28B of the second plate 15B further comprises respective inner 30B and outer 35B ends and a respective conductive pad 36B for each end 30B, 35B.

[0051] In a similar manner to the first plate 15A, the second plate 15B comprises insulating strips 37B and contiguous elementary patterns 40B comprising conductive strands 45B, 46B, 47B forming the conductive tracks 25B when said patterns are juxtaposed.

[0052] Each elementary pattern 40A of the first plate 15A faces an elementary pattern 40B of the second plate 15B. Thus, each conductive pad 36A of the first plate 15A faces a respective conductive pad 36B of the second plate 15B. Each column 22 joins a respective pad 36A of the first plate 15A and a respective pad 36B of the second plate 15B, preferably two pads 36A, 36B facing each other.

[0053] A difference between the first plate 15A and the second plate 15B is that the conductive tracks 28B of the second plate 15B wind around the second central orifice 15B in a second direction of rotation opposite to the first direction of rotation.

[0054] Figure 3 represents a view from below of two superimposed patterns 40A, 40B of the coil 10 according to a first embodiment.

[0055] In the first embodiment, the strands 45A, 46A, 47A are radially ordered relative to the first central orifice 25A. The plurality of conductive strands 45A, 46A, 47A comprises an inner strand 45A, an outer strand 47A and optionally one or more intermediate strands 46A.

[0056] The inner strand 45A is closest to the first central orifice 25A. The outer strand 47A is furthest from the first central orifice 25A. The intermediate strand(s) 46A are radially ordered between the inner strand 45A and outer strand 47A.

[0057] Each conductive strand 45A, 46A, 47A comprises corrugations in a plane of the first plate 20A. In other words, each conductive strand 45A, 46A, 47A has, in its path on the first plate 20A, undulations. Preferably, each conductive strand 45A, 46A, 47A is formed of a plurality of end-to-end circular arcs, around distinct points so that each strand 45A, 46A, 47A does not form any break. In other words, each conductive strand 45A, 46A, 47A is derivable at least once at any point of the elementary pattern 40A, and preferably an infinite number of times.

[0058] According to the example of figure 3, each elementary pattern 40A, 40B comprises an internal strand 45A, an external strand 47A and three intermediate strands 46A.

[0059] Preferably, the elementary pattern 40A further comprises an internal dead zone 48A and an external dead zone 49A.

[0060] In the remainder of the description, we define “an arc of a circle of a first type of orientation”, also called “internally oriented arc of a circle” or “internally oriented arc” as being an arc of a circle around a center located between said arc and a center of the plate 15A, 15B associated with said arc, i.e. a middle of the corresponding central orifice 25A, 25B.

[0061] Similarly, an “arc of a circle of a second type of orientation”, also called an “externally oriented arc of a circle”, or an “externally oriented arc” is defined as being an arc of a circle around a center whose location is such that said arc is located between the center of the plate 15A, 15B and said center.

[0062] An alternation of internally and externally oriented circular arcs, or externally and internally oriented, then forms corrugations.

[0063] In the example of Figure 3, each intermediate strand 46A is formed, from top to bottom on the right part of Figure 3: of a first internally oriented arc A1A defined around a first center, of a second externally oriented arc A2A defined around a second center, of a third internally oriented arc A3A defined around a third center, of a fourth externally oriented arc A4A defined around a fourth center, and of a fifth internally oriented arc A5A defined around a fifth center.

[0064] Preferably, the first, second, third, fourth and fifth centers are the same for each intermediate strand 46A. In other words, the portions of each intermediate strand 46A forming each arc A1A, A2A, A3A, A4A, A5A are concentric.

[0065] For each arc of a circle A1 A, A2A, A3A, A4A, A5A of the intermediate strands 46A, the angular displacement of said arc is identical for each of the intermediate strands 46A. Thus, the length of said arc A1 A, A2A, A3A, A4A, A5A in a chosen intermediate strand 46A is equal to the product of said angular displacement and the distance of said arc A1 A, A2A, A3A, A4A, A5A from the center from which this arc A1 A, A2A, A3A, A4A, A5A is formed. The internal strand 45A is formed, from top to bottom on the right part of figure 3: of a sixth externally oriented arc of a circle A6A defined around a sixth center, and of a seventh internally oriented arc of a circle A7A defined around a seventh center.

[0066] The seventh arc A7A of the internal strand 45A has a substantially smaller angular displacement than that of the third arc of each intermediate strand 46A.

[0067] Furthermore, the internal strand 45A comprises, at the end of the eighth arc A8A, one of the conductive pads 36A. Said conductive pad 36A is preferably located angularly in the middle of the elementary pattern 40A.

[0068] The outer strand 47A is formed in a similar manner to the intermediate strand(s) 46A except that it comprises, before its first arc A1 A, a respective conductive pad 36A.

[0069] Preferably, the first center and the fifth center are each the center of the first plate 15A, i.e. the center of the first central orifice 25A.

[0070] As visible in Figure 3, each intermediate strand 46A and the external strand 47A define, during their tracing, a radial sliding. In other words, given that the internal strand 45A only extends to the middle of the elementary pattern 40A, the intermediate strand 46A closest to the first central orifice 25A, extends, after said middle, in the extension of the internal strand 45A. Thus, the conductive track 28A comprising said intermediate strand 46A also comprises the internal strand 45A on the following elementary pattern 40A.

[0071] Likewise, all the other intermediate strands 46A slide by one unit in radial order between the top and the bottom of the elementary pattern 40. The same applies to the external strand 47A which becomes, on the following pattern 40A, the intermediate strand 46A furthest from the first central orifice 25A.

[0072] This sliding of order of strands 45A, 46A, 47A makes it possible to wind each conductive track 20A around the first central orifice 25A.

[0073] The remainder of the elementary pattern 40A is filled with insulating material, thus forming the insulating strips 37A.

[0074] Thanks to the aforementioned construction, a distance between the conductive strands 45A, 46A, 47A is constant at all points of said strands 45A, 46A, 47A, thus limiting the risk of short circuit between two strands 45A, 46A, 47A.

[0075] The internal dead zone 48A is an area of ​​insulating material between the first central hole 25A and the internal strand 45A.

[0076] The external dead zone 49A is an area of ​​insulating material between the external strand 47A and a radially outer edge of the pattern 40A. Each elementary pattern 40B of the second plate 20B is analogous to the elementary pattern 40A of the first plate 20A previously described by replacing the reference A with the reference B and by reversing top and bottom. Thus, the intermediate strands 46A, 46B and external strands 47A, 47B of the two patterns 40A, 40B are substantially aligned as visible on the right part of Figure 3.

[0077] On the right-hand side of figure 3, the arcs A1 B, A2B, A3B, A4B, A5B, A6B, A7B of the pattern 40B of the second plate 15B are not shown for the sake of visibility but are analogous to those described previously for the pattern 40A of the first plate 15A by reversing the notions of top and bottom in their description.

[0078] The left part of Figure 3 represents schematic sections of the elementary patterns 40A, 40B at two angular ends of said patterns 40A, 40B.

[0079] In each section of this figure 3, the strands 45A, 46A, 47A corresponding to the elementary pattern 40A of the first plate 20A are represented at the top and the strands 45B, 46B, 47B corresponding to the elementary pattern 40B of the second plate 20B are represented at the bottom.

[0080] In the first embodiment, the strands 45A, 46A, 47A of the first plate 20A are aligned in the transverse direction T with the strands 45B, 46B, 47B of the second plate 20B. In other words, each strand 45B, 46B, 47B is substantially a projection of a strand 45A, 46A, 47A in the transverse direction T.

[0081] In the section shown at the top left, it is visible that the internal strand 45A of the elementary pattern 40A of the first plate 15A is aligned with the intermediate strand 46B of the pattern 40B of the second plate 15B closest to the central orifice 25B.

[0082] The left part of Figure 3 illustrates the offset between a start and an end of the elementary patterns 40A, 40B. Indeed, for the first plate 15A, the internal strand 45A has disappeared at the end of the pattern 40A and all the other strands 46A, 47A are offset by one row closer to the first central orifice 25A. For the second plate 15B, the internal strand 45B has appeared at the end of the pattern 40A and all the other strands 46B, 47B are offset by one row further from the second central orifice 25B. This is due to the opposite directions of rotation between the first 15A and second 15B plates.

[0083] Furthermore, the internal dead zones 48A, 48B of the first 15A and second 15B plates are analogous. Similarly, the external dead zones 49A, 49B of the first 15A and second 15B plates are analogous.

[0084] Figure 4 illustrates an alternative embodiment of the first embodiment.

[0085] According to this variant, each conductive track 28A, 28B of a respective plate 15A, 15B is substantially aligned in the transverse direction T with an insulating strip 37A, 37B of the other plate 15A, 15B. Thus, according to this variant, the first plate 15A is analogous to the example described previously with reference to FIG. 3 with the following differences.

[0086] In the example illustrated in Figure 4, the patterns 40A, 40B respectively comprise an internal strand 45A, 45B, an external strand 47A, 47B and four intermediate strands 46A, 46B. It is clear that, as for the first example of the first embodiment, the number of intermediate strands is for example equal to three or equal to any other value.

[0087] According to this variant, the elementary pattern 40B of the second plate 15B also has the distinctions described below, compared to the example described previously.

[0088] In particular, the external strand 47B of each elementary pattern 40B of the second plate 15B has, before the first arc of a circle A1 B, an initial arc of a circle AIB connecting its conductive pad 36B to said first arc A1 B. The initial arc of a circle AIB is oriented externally and defined around an initial center preferentially located in the external dead zone 49B not shown.

[0089] The angular displacement and / or the location of some of the centers of the arcs of circles A1A, A1B, A2A, A2B, A3A, A3B, A4A, A4B, A5A, A5B, A6A, A6B, A7A, A7B are distinct from the first embodiment so that each strand 45A, 46A, 47A of the pattern 40A of the first plate 15A is aligned with an insulating strip 37B of the pattern 40B of the second plate 15B, in the transverse direction T. Similarly, each strand 45B, 46B, 47B of the pattern 40B of the second plate 15B is aligned with an insulating strip 37A of the pattern 40A of the first plate 15A, in the transverse direction T.

[0090] It is then understood that the strands 45A, 46A, 47A of the pattern 40A of the first plate 15A are not aligned with the strands 45B, 46B, 47B of the pattern 40B of the second plate 15B, in the transverse direction T.

[0091] For the sake of readability in Figure 4, the arcs A1A, A2A, A3A, A4A, A5A are only illustrated for the external strand 47A of the elementary pattern 40A of the first plate 15A.

[0092] According to this variant, among the internal strands 45A, 45B, only that of the elementary pattern 40A of the first plate 15A is distinct from what was described previously. Indeed, this internal strand 40A comprises, in place of the sixth externally oriented arc A6A, an eighth internally oriented arc A8A around an eighth center.

[0093] These arrangements of the internal strands 45A, 45B and of the external strand 47B of the elementary pattern 40B of the second plate 15B allow, although the strands 45A, 46A, 47A, 45B, 46B, 47B are not aligned in the transverse direction T, that the conductive pads 36A, 36B are so aligned so that the conductive tracks 28A, 28B are connected by the columns 22. The alignment of the strands 45A, 46A, 47A 45B, 46B, 47B of a plate 15A, 15B with a respective insulating strip 37A, 37B of the other plate is further shown in the left part of FIG. 4.

[0094] According to this embodiment variant, the elementary patterns 40A, 40B also have the sliding mechanism of the strands previously described as visible in figure 4 representing the same sections as those of figure 3 but with reference to the elementary patterns 40A, 40B according to the embodiment variant.

[0095] SECOND EMBODIMENT OF THE INVENTION

[0096] Figures 5, 6, 7, and 8 illustrate a second embodiment of the invention.

[0097] Only the differences with the coil 10 according to the first embodiment will be detailed. All the characteristics which are not detailed in this second embodiment are similar to those of the first embodiment.

[0098] The numerical references in the description of this second embodiment are incremented by the value 100. Thus, the coil according to the second embodiment bears the reference 110.

[0099] More particularly, Figure 5 illustrates coil 1 10.

[0100] Each conductive strand 145A, 146A, 147A, 145B, 146B, 147B of the first plate 115A, and preferably also of the second plate 115B, comprises two conductive paths 150A, 151A, 150B, 151B spaced from each other by an insulating path 152A, 152B of the same width as the insulating strips 137A, 137B. Preferably, each conductive strand 145A, 146A, 147A, 145B, 146B, 147B comprises an internal path 150A, 150B and an external path 151A, 151B further from the central orifice 125A, 125B than the internal path 150A, 150B.

[0101] Each elementary pattern 140A, 140B further comprises an additional channel 153A, 153B further from the central orifice 125A, 125B than the external channel 151A, 151B of the external strand 147A, 147B.

[0102] Figure 6 represents a first elementary pattern 140A of the first plate 115A of the coil 110 according to the second embodiment, in a so-called non-aligned configuration. In a manner similar to that explained with reference to Figure 4, in this configuration, each conductive path 150A, 151A of each elementary pattern 140A of the first plate 15A, is substantially aligned with an insulating path 152B, or an insulating strip 137B, of an elementary pattern 140B of the second plate 115B.

[0103] Conversely, each conductive path 150B, 151B of each elementary pattern 140B of the second plate 115B, is substantially aligned with an insulating path 152A, or an insulating strip 137A, of a respective elementary pattern 140A of the first plate.

[0104] 115A.

[0105] Each path 150A, 151A, 150B, 151B of each strand 145A, 146A, 147A, 145B, 146B, 147B is formed from a plurality of circular arcs, some oriented internally and some oriented externally forming corrugations.

[0106] In the examples of figures 6 and 7, the elementary patterns 140A, 140B represented, respectively comprise four conductive strands 145A, 146A, 147A, 145B, 146B, 147B, and therefore nine conductive paths 150A, 151A, 152A, 150B, 151B, 152B, 153A, 153B.

[0107] Each path 150A, 151A of each intermediate strand 146A, is for example formed, from top to bottom in FIG. 6, of a first internally oriented arc A1A defined around a first center, of a second internally oriented arc A2A defined around a second center, of a third externally oriented arc A3A defined around a third center, of a fourth internally oriented arc A4A defined around a fourth center, and of a fifth internally oriented arc A5A defined around a fifth center, of a sixth internally oriented arc A6A defined around a sixth center, of a seventh externally oriented arc A7A defined around a seventh center, and of an eighth internally oriented arc A8A defined around an eighth center.

[0108] Said centers are common to each track 150A, 151A of the intermediate strands 146A. In other words, the tracks 150A, 151A are, for each arc A1A, A2A, A3A, A4A, A5A, A6A, A7A, A8A, concentric.

[0109] For each arc of the tracks 150A, 151 A of the intermediate strands 146A, the angular movement of said arc is identical for each of the tracks 150A, 151 A. Thus, the length of said arc in a track 150A, 151 A is equal to the product of said angular movement and the distance of said arc from the center from which this arc is formed.

[0110] Concerning the external strand 147A, its internal track 150A is identical to the tracks 150A, 151A of the intermediate strands 146A with the exception of the first arc and the second arc.

[0111] Rather than the first arc A1A, the inner path 150A of the outer strand 147A includes a ninth externally oriented arc A9A defined around a ninth center. Rather than the second arc A2A, the inner path 150A of the outer strand 147A includes a tenth internally oriented arc A10A defined around a tenth center.

[0112] The angular displacement of the tenth arc A10A is significantly lower than the angular displacement of the second arc A2A.

[0113] The outer lane 151A of the outer strand 147A is identical to the lanes 150A, 151A of the intermediate strands 146A except for the first A1A and second A2A arcs. In particular, the outer lane 151A of the outer strand 147A does not include the first A1A arc. Rather than the second A2A arc, the outer lane 151A of the outer strand 147A includes a twelfth internally oriented A12A arc defined around a twelfth center.

[0114] The external path 151 A of the external strand 147A further comprises, before the twelfth arc A12A, a respective conductive pad 136A.

[0115] The internal path 150A of the internal strand 145A comprises an internally oriented thirteenth arc A13A defined around a thirteenth center, an internally oriented fourteenth arc A14A defined around a fourteenth center, an externally oriented fifteenth arc A15A defined around a fifteenth center, and a respective constructive pad 136A at the end of the fifteenth arc A15A.

[0116] The angular displacement of the thirteenth arc A13A is significantly higher than the angular displacement of the second arc A2A.

[0117] The outer path 151A of the inner strand 145A comprises the first arc A1A, the second arc A2A, the fourteenth arc A14A, the fifteenth arc A15A, an internally oriented sixteenth arc A16A defined around a sixteenth center and a respective conductive pad 36 at the end of the sixteenth arc A16A.

[0118] The fourteenth A14A, fifteenth A15A and sixteenth A16A arc of the external track 151 A make it possible to bypass the conductive pad 36A of the internal track 150A of the internal strand 145A.

[0119] The angular movement of the second arc A2A of the external track 151 A of the internal strand 145A is greater than for the intermediate goods 146A.

[0120] The additional channel 153A extends from the end of the pattern 140A opposite the twelfth arc A12A, and at a distance from the eighth arc A8A of the external channel 151A of the external strand 147A equal to the width of the insulating strip 137A. The additional channel 153A comprises a single externally oriented seventeenth arc A17A defined around a seventeenth center, and at the end of said arc A17A, a respective pad 36A.

[0121] Each elementary pattern 140A of the first plate 15A according to the second embodiment also includes the shifting mechanism described previously with reference to the first embodiment. In particular, this mechanism is for example applied to all the paths 150A, 151A of the intermediate strands 146A and outer strands 147A.

[0122] The remainder of the pattern 140A is, as in the first embodiment, filled with insulating material forming the insulating strips 137A and the insulating channels 152A.

[0123] Preferably, the first center is the center of the first central orifice 125A.

[0124] Preferably, the second center is the center of the first central orifice 125A. Preferably, the fourth center is the center of the pad 136A associated with the internal path 150A of the internal strand 145A.

[0125] Preferably, the fifth center is the center of the first central orifice 125A.

[0126] Preferably, the sixth center is the middle of a segment connecting the center of the pad 136A associated with the internal path 150A of the internal strand 145A and the center of the pad 136A associated with the external path 151A of the internal strand 145A.

[0127] Preferably, the seventh center is the center of the 136A pellet associated with the additional channel 153A.

[0128] Preferably, the eighth center is the center of the first central orifice 125A.

[0129] Preferably, the ninth center is located in the 136A pellet associated with the external pathway 151 A of the external strand 147A.

[0130] Preferably, the tenth center is the center of the first orifice 125A.

[0131] Preferably, the twelfth center is the center of the first orifice 125A.

[0132] Preferably, the thirteenth center is the center of the first central orifice 125A.

[0133] Preferably, the sixteenth center is the center of the pad 136A associated with the internal path 150A of the internal strand 145A.

[0134] Referring to Figure 7, each elementary pattern 140B of the second plate 15B is analogous to the elementary patterns 140A of the first plate 125A by replacing the letter A with the letter B in the reference numerals and by reversing the notions of top and bottom. In addition, the elementary pattern 140B of the second plate 15B includes the differences described below compared to the elementary pattern 140A of the first plate 15A described previously.

[0135] In particular, for the tracks 150B, 151B of the intermediate strands 146B, the angular displacement of the sixth arc A6B is greater than for the intermediate strands 146A of the first plate 15A. Thus, the angular displacement of the eighth arc A8B of the tracks 150B, 151C of the intermediate strands 146B of the second plate 15B is smaller than for the first plate 15A.

[0136] The external path 151 B of the internal strand 145B comprises the first arc A1 B, the second arc A2B (which is analogous to those of the intermediate strands 146B), the third arc A3B, the fourth arc A4B, the sixteenth arc A16B and the pad 136B connected to the sixteenth arc A16B. Thus, the external path 151 B of the internal strand 145B does not comprise, unlike the case of the first plate 15A, the fourteenth arc A14A and the fifteenth arc A15A.

[0137] The internal path 150B of the internal strand 145B comprises only the thirteenth arc A13B, the third arc A3B and the pad 136B connected to the third arc A3B. The external path 151 B of the external strand 147B further comprises an eleventh arc A11 B oriented externally, before the twelfth arc A12B. The eleventh arc A11 B is therefore connected to the pad 136B and to the twelfth arc A12B.

[0138] The pad 136B of the internal path 150B of the internal strand 145B of the elementary pattern 140B of the second plate 15B is preferentially connected to the pad 136A of the external path 151A of the internal strand 145A of the elementary pattern 140A of the first plate 15A by a respective column 122, so that there is an inversion between the internal path 150B and external path 151A.

[0139] Likewise, the pad 136B of the external path 151B of the internal strand 145B of the elementary pattern 140B of the second plate 115B is preferentially connected to the pad 136A of the internal path 150A of the internal strand 145A of the elementary pattern 140A of the first plate 115A by a respective column 122, so that there is an inversion between the internal 151B and external 150A paths.

[0140] The pad 136B of the additional channel 153B of the elementary pattern 140B of the second plate 115B is preferentially connected to the pad 136A of the external channel 151A of the external strand 147A of the elementary pattern 140A of the first plate 115A by a respective column 122.

[0141] Similarly, the pad 136B of the external channel 151B of the external strand 147B of the elementary pattern 140B of the second plate 115B is connected to the pad 136A of the additional channel 153A of the elementary pattern 140A of the first plate 115A, by a respective column 122.

[0142] A variant of the second embodiment is shown in Figure 8.

[0143] In this variant, the tracks 150A, 151A of the elementary pattern 140A of the first plate 115A are substantially aligned with the tracks 150B, 151B of the elementary pattern 140B of the second plate 115B, as explained previously with reference to FIG. 3.

[0144] Figure 8 shows the elementary pattern 140A of the first plate according to this variant. The elementary pattern of the second plate 15B is similar to that described previously.

[0145] As visible in Figure 8, each elementary pattern 140A of the first plate 15A is analogous to the elementary patterns 140A of the first plate 15A with the following differences:

[0146] In particular, for the paths 150A, 151A of the intermediate strands 146A, the angular displacement of the sixth arc A6A is greater than for the intermediate strands 146A described previously. Thus, the angular displacement of the eighth arc A8A of the paths 150A, 151A of the intermediate strands 146A is smaller than that described previously. The external path 151A of the internal strand 145A comprises the first arc A1A, the second arc A2A (which is analogous to those of the intermediate strands 146A), the third arc A3A, the fourth arc A4A, the sixteenth arc A16A and the pad 136A connected to the sixteenth arc A16A. Thus, the external path 151A of the internal strand 145A does not comprise, contrary to what is described previously, the fourteenth arc A14A and the fifteenth arc A15A.

[0147] The internal path 150A of the internal strand 145A comprises only the thirteenth arc A13A, the third arc A3A and the pad 136A connected to the third arc A3A.

[0148] It is then understood that the elementary pattern 140A of the first plate 15A according to this variant is analogous to the elementary pattern 140B of the second plate 15B described previously by reversing the notions of top and bottom and by replacing the letter A with the letter B in the references, with the difference that the external path 151 A of the external strand 147A does not include an eleventh arc.

[0149] THIRD EMBODIMENT

[0150] A third embodiment is illustrated in Figure 9.

[0151] Only the differences with the coil 10 according to the first embodiment will be detailed. All the characteristics which are not detailed in this third embodiment are analogous to the first embodiment.

[0152] The numerical references in the description of this third embodiment are incremented by the value 200 compared to the first embodiment. Thus, the coil according to the second embodiment bears the reference 210.

[0153] More particularly, Figure 9 illustrates the first plate 215A of the coil 210.

[0154] The second plate 215B is substantially similar to the first plate.

[0155] In this third embodiment, each plate 215A, 215B is substantially rectangular and defines a substantially rectangular or oblong central orifice 225A, 225B.

[0156] The plate 215A is formed from a plurality of contiguous patterns including linear patterns 240A and corner patterns 241A. The linear patterns 240A are substantially rectangular and the corner patterns are portions of rings.

[0157] As in the previously described embodiments, each conductive track 228A extends over a plurality of patterns, and forms on each pattern 240A, 241A a respective conductive strand 245A, 246A, 247A.

[0158] Each pattern 240A, 241A comprises an inner strand 245A, one or more intermediate strands 246A and an outer strand 247A, ordered with respect to their distance from the central orifice 225A. Each strand 245A, 246A, 247A is for example formed from a plurality of circular arcs placed end to end.

[0159] Preferably, each intermediate strand 246A comprises a first externally oriented arc of a circle A1A, a second internally oriented arc of a circle A2A, a third internally oriented arc of a circle A3A and a fourth externally oriented arc of a circle A4A.

[0160] The inner strand 245A comprises a fifth externally oriented arc of a circle A5A, a sixth externally oriented arc of a circle A6A and a respective conductive pad 236A connected to a respective conductive pad 236B of the second plate 215B by a respective column 222.

[0161] The outer strand 247A comprises a respective conductive pad 236A, a seventh externally oriented arc of a circle A7A, an eighth internally oriented arc of a circle A8A. Said conductive track 236A is connected to a respective conductive pad 236B of the second plate 215B by a respective column 222.

[0162] Each strand 245A, 246A, 247A, 245B, 246B, 247B of each pattern 240A, 241A, 240B, 241B is, at any point on the strand, at a constant distance from the nearest strand. Each pattern 240A, 241A, 240B, 241B further comprises, between each strand 245A, 246A, 247A, 245B, 246B, 247B, an insulating strip 237A, 237B whose width is equal to said constant distance.

[0163] Each elementary pattern 240A, 241A, 240B, 241B of the coil 210 according to the third embodiment also comprises the shift mechanism described previously.

[0164] A method of designing a coil 10, 110, 210 according to one of the preceding embodiments will now be described.

[0165] The method is implemented by an electronic design device not shown. The electronic design device is preferably a computer capable of implementing a computer program comprising software instructions, which when executed by said computer, implement a design method as described below.

[0166] The method comprises a step of receiving dimensions of the central orifice 25A, 25B, 125A, 125B, 225A, 225B, of a number of conductive tracks 28A, 28B, 128A, 128B, 228A, 228B per plate 15A, 15B, 1 15A, 115B, 215A, 215B, of a track width and of a width of an insulating strip 37A, 137A, 237A between two successive tracks.

[0167] The method further comprises a step of generating at least one elementary pattern 40A, 40B, 140A, 140B, 240A, 241 A, 240B, 241 B as described previously from the dimensions, the number of conductive tracks per plate, the track width and the width of an insulating strip between two received tracks.

[0168] Preferably, the design device generates a pattern 40A, 140A, 240A of the first plate 15A, 115A, 215A and a pattern 40B, 140B, 240B of the second plate 15B, 115B, 215B.

[0169] The method further comprises a step of concatenating, a plurality of times, the same elementary pattern(s) 40A, 40B, 140A, 140B, 240A, 241A, 240B, 241B to form the coil 10, 110, 210. Preferably, the design device concatenates several times the pattern 40A, 140A, 240A, 241A associated with the first plate 15A, 115A, 215A to form said plate 15A, 115A, 215A, and concatenates several times the pattern 40B, 140B, 240B, 241B associated with the second plate 15B, 115B, 215B to form the second plate 15B, 115B, 215B.

[0170] Preferably, the method further comprises a step of associating a number N of coils 10, 110, 210, by superimposing them and connecting them by the connection vias 20, 120, 220. The number N is greater than or equal to 1. In particular, one of the respective connection vias 20, 120, 220 of a coil 10, 110, 210 is connected to one of the connection vias 20, 120, 220 of another coil 10, 110, 210. Thus, a set of coil(s) is formed.

[0171] The method further comprises a step of generating a file of the coil 10, 110, 210, or of the set of coil(s), suitable for being transmitted to a production machine for the automatic manufacture of the coil 10, 110, 210.

[0172] During the manufacture of the coil 10, 110, 210, or the set of coil(s) the conductive tracks 28A, 28B, 128A, 128B, 228A, 228B are formed from a conductive material and insulating material is injected between the tracks 28A, 28B, 128A, 128B, 228A, 228B to form the insulating strips 37A, 37B, 137A, 137B, 237A, 237B and / or the insulating paths 152A, 152B. The or each coil 10, 110, 210 is then pressed in the transverse direction T. Thus, when the conductive strands are not aligned, the risk of damaging said strands during pressing is reduced.

[0173] The conductive material is, for example, copper.

[0174] With the coil 10, 110210 according to the invention the corrugations of the conductive strands 45A, 46A, 47A, 45B, 46B, 47B, 145A, 146A, 147A, 145B, 146B, 147B, 245A, 246A, 247A, 245B, 246B, 247B make it possible to extend the length of each conductive track 28A, 128A, 228A, 28B, 128B, 228B without significantly increasing the size of the coil 10, 110, 210.

[0175] Furthermore, due to the offset mechanism, each conductive track 28A, 128A, 228A, 28B, 128B, 228B is identical to the other conductive tracks 28A, 128A, 228A, 28B, 128B, 228B within one rotation about the centers of the first 15A, 15A, and second plates 15B, 215B, in the first two embodiments.

[0176] In the third embodiment, the offset mechanism makes it possible to ensure that each conductive track 28A, 128A, 228A, 28B, 128B, 228B extends as much, close to the central orifice 25A, 125A, 225A, 25B, 125B, 225B, as far from said orifice 25A, 125A, 225A, 25B, 125B, 225B.

[0177] Thus, in each embodiment, the current flowing in each track spends as much time close to the central holes as far from the holes.

[0178] This allows the Litz effect of the coil to be obtained and therefore reduces the resistance induced by the coil at high frequencies.

[0179] It will be noted that several coils 10, 110, 210 can be stacked in the transverse direction T and connected to each other using connection vias 20, 120, 220 connecting a second plate 15B, 115B, 215B respective of a coil 10, 110, 210 and a first plate 15A, 115A, 215 respective of another coil 10, 110, 210. This makes it possible to increase the number of conductive tracks in the stack of coils and therefore to vary the induction of said stack.

Claims

CLAIMS 1. An electromagnetic coil (10; 110; 210) comprising a first plate (15A; 115A; 215A) defining a first central orifice (25A; 125A; 225A), the first plate (15A; 115A; 215A) comprising a plurality of ordered conductive tracks (28A; 128A; 228A) winding around the first central orifice (25A; 125A; 225A), each track (28A; 128A; 228A) defining an inner end (30A; 130A; 230A) and an outer end (35A; 135A; 235A), the inner end (30A; 130A; 230A) of each track (28A; 128A; 228A) being closer to the first central orifice (25A; 125A; 225A) than the outer end (35A; 135A; 235A), the first plate (15A; 115A; 215A) comprising a plurality of elementary patterns (40A; 140A; 240A, 241A) contiguous around the first central orifice (25A; 125A; 225A), each conductive track (28A; 128A; 228A) extending over at least two elementary patterns (40A; 140A;240A, 241 A) contiguous and forming on each of said elementary patterns (40A; 140A; 240A, 241 A) contiguous a conductive strand (45A, 46A, 47A; 145A, 146A, 147A; 245A, 246A, 247A), the coil (10; 110; 210) being characterized in that each conductive strand (45A, 46A, 47A; 145A, 146A, 147A; 245A, 246A, 247 A) comprises corrugations in a plane of the first plate (15A; 115A; 215A).; 2. Coil (10; 110; 210) according to claim 1, comprising at least one second plate (15B; 115B; 215B) comprising a second central orifice (25B; 125B; 225B), the second plate (15B; 115B; 215B) being arranged opposite the first plate (15A; 115A; 215A) and spaced therefrom in a transverse direction (T) perpendicular to each of the plates (15A, 15B; 115A, 115B; 215A, 215B), the second plate (15B; 115B; 215B) comprising a plurality of respective conductive tracks (28B; 128B; 228B), ordered and winding around the second central orifice (25B; 125B; 225B), each conductive track (28B; 128B; 228B) of the second plate (15B; 1 15B; 215B) defining a respective inner end (30B; 130B; 230B) and an outer end (35B; 135B; 235B), the coil (10; 1 10; 210) further comprising, for each end (30A, 35A; 130A, 135A; 230A, 235A) of each conductive track (28A; 128A;228A) of the first plate (15A; 1 15A; 215A), a conductive column extending (22; 122; 222) in the transverse direction (T) connecting said end (30A, 35A; 130A, 135A; 230A, 235A) to an end (30B, 35B; 130B, 135B; 230B, 235B) of a respective conductive track (28A; 128A; 228A) of the second plate (15B; 115B; 215B).; 3. Coil (10; 110; 210) according to claim 2, in which the or each plate (15A, 15B; 115A, 115B; 215A, 215B) comprises, between each pair of successive conductive tracks (28A, 28B; 128A, 128B; 228A, 228B), an insulating strip (37A, 37B; 137A, 137B; 237A, 237B) whose width is constant and predefined.

4. Coil (10; 110; 210) according to claim 3, in which each conductive strand (145A, 145B, 146A, 146B, 147A, 147B) is formed of at least two conductive paths (150A, 150B, 151A, 151B) spaced from each other by an insulating path (152A, 152B) of the same width as the insulating strips (137A).

5. Coil (10; 110; 210) according to claim 3 or 4, wherein each conductive track (28A, 28B; 128A, 128B; 228A, 228B) of a respective plate (15A, 15B; 115A, 115B; 215A, 215B) is substantially aligned in the transverse direction (T) with an insulating strip (37A, 37B; 137A, 137B, 152A, 152B; 237A, 237B) of the other plate (15A, 15B; 115A, 115B; 215A, 215B).

6. Coil (10; 110; 210) according to any one of claims 1 to 4, in which each conductive track (28A; 128A; 228A) of the first plate (15A; 115A; 215A) is substantially aligned in the transverse direction (T) with a corresponding conductive track (28B; 128B; 228B) of the second plate (15B; 115B; 215B).

7. Coil (10; 110; 210) according to any one of the preceding claims, in which each conductive strand (45A, 46A, 47A; 145A, 146A, 147A; 245A, 246A, 247A) is formed from a plurality of circular arcs.

8. Coil (10; 110; 210) according to any one of the preceding claims, in which the first central orifice (25A; 125A) has a circular geometry, the conductive tracks (28A; 128A) of the first plate being identical to each other apart from a rotation around a center of the first central orifice (25A; 125A) of the first plate (15A; 115A).

9. Method for designing a coil (10; 110; 210) according to any one of the preceding claims, the method being implemented by an electronic design device and comprising the following steps: receiving dimensions of the first central orifice (25A; 125A; 225A), of a number of conductive tracks (28A; 128A; 228A) on the first plate (15A; 115A; 215A), of a track width and of a width of an insulating strip (37A; 137A, 152A; 237A) between two conductive tracks (28A; 128A; 228A), - generating at least one elementary pattern (40A; 140A; 240A, 241A) from the dimensions, of the number of conductive tracks (28A; 128A; 228A) on the first plate (15A; 115A; 215A), of the track width and of the width of an insulating strip between two tracks, received, - concatenation of the plurality of times the same elementary pattern(s) (40A; 140A; 240A, 241 A) to form the coil (10; 110; 210), and generation of a file of the coil (10; 110; 210) suitable for being transmitted to a production machine for the automatic manufacture of the coil (10; 110; 210).

10. Computer program product comprising software instructions which, when executed by a computer, implement a design method according to claim 9.

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