MAGNETIC INDUCTION COMPONENT COMPRISING A CUT METAL STRIP COATED WITH A DIELECTRIC RESIN AND ITS MANUFACTURING PROCESS

Abstract

The magnetic induction component (1A) comprises a metal strip, which has been cut to form a planar magnetic induction circuit (10). The planar magnetic induction circuit (10) is coated with a resin deposited by immersing the planar magnetic induction circuit (10) in a bath of liquid resin and by cross-linking the resin while the planar magnetic induction circuit (10) is immersed, so as to form a dielectric coating (11) that completely covers both faces (100; 101) and the edges (102) of the planar magnetic induction circuit (10), including the edges (103) at the junction between each face and each edge, with the possible exception of one or more electrical connection areas (10a; 10b) of the planar magnetic induction circuit (10). Figure 1

Description

Title of the invention: MAGNETIC INDUCTION COMPONENT COMPRISING A CUT METAL STRIP COATED WITH A DIELECTRIC RESIN AND ITS MANUFACTURING METHOD technical field

[0001] The present invention relates to the technical field of magnetic induction circuits, which are made by cutting a metal strip. In this field, the invention consists of an improvement in the electrical insulation of this particular type of magnetic induction circuit. The invention thus has as its principal objects a new magnetic induction component, which is made from a cut metal strip, as well as its manufacturing process. It also relates to a planar magnetic induction machine, in particular a planar electrical transformer, comprising one or more of these new magnetic induction components, as well as a planar inductor made from this new magnetic induction component. Previous art

[0002] The term "electrical transformer" is generally understood to mean a device for transforming the current and voltage values ​​of an alternating electrical energy source into other, different current and voltage values, but with the same waveform and frequency. The transformation principle is based on magnetic induction. In its simplest form, a transformer comprises a primary magnetic induction circuit, a magnetic circuit, and a secondary magnetic induction circuit.

[0003] In a conventional transformer, each magnetic induction circuit most often takes the form of a dipole of several turns of copper conductor wire coated with thin electrical insulation ("enamelled wire") and forming a coil or winding. The magnetic circuit most often takes the form of a stack of iron-silicon alloy laminations or of ferrite. This magnetic circuit channels the magnetic fluxes and significantly increases the transformer's efficiency compared to circuits located in ambient air.

[0004] Besides the traditional transformer mentioned above, another type of electrical transformer, called "planar", has been developed more recently, in which the magnetic induction circuits are in the form, not of coils, but of planar magnetic induction circuits.

[0005] A planar magnetic induction circuit can have different shapes, the most common shapes being a flat loop or a winding of several flat loops in the shape of a spiral.

[0006] The construction of a planar transformer consists of alternating primary and secondary planar induction circuits, with the necessary electrical insulation between each layer. The entire assembly is placed and insulated between two ferrites, typically E-shaped and I-shaped, which are in contact and thus close the magnetic circuit. Adhesives and other mechanical devices can be used to hold the magnetic circuits tightly together and to the ferrites.

[0007] Compared to traditional winding transformers, planar electrical transformers offer the following advantages:

[0008] - ability to operate at high frequencies (in hundreds of kHz),

[0009] - less compactness and weight at equal switching power,

[0010] - better efficiency, less leakage current,

[0011] - flat geometric shape more favorable to heat dissipation.

[0012] Planar magnetic induction circuits can be used not only to manufacture a planar electrical transformer, but more generally to manufacture any other type of planar magnetic induction machine, such as by a planar spiral coil.

[0013] In a simplified implementation, a single planar magnetic induction circuit can also be used to create a planar inductance dipole, which is more commonly referred to as an inductance or, by anglicism, "self", which can, for example, be used to filter an electric current, or to create a high-voltage pulse.

[0014] To date, various technologies are used for the realization of a planar magnetic induction circuit.

[0015] Up to a few hundred watts, the planar magnetic induction circuit, and for example the turns of the winding, is etched on printed circuits “PCB” (from the English “Printed Circuit Board”).

[0016] On the other hand, for higher power electric currents, and typically for powers greater than one kilowatt, a planar magnetic induction circuit is used which is made from a metal strip which has been cut.

[0017] Metal strips are usually made from metal strips or thin metal sheets, and are cut to form the planar magnetic induction circuit having the appropriate geometric shape, for example a flat loop or a flat winding of several non-contiguous loops in the shape of spiral. This cut is most often made by stamping or by laser or waterjet cutting.

[0018] By way of example only, the materials used are most often copper or aluminum. By way of example only, the most common thicknesses can be in the range of 0.5 mm to 1 mm.

[0019] A protective but electrically conductive surface treatment (tinning - nickel plating - silver plating - thermal or cold spraying of a conductive metal...) may also have been carried out on the original strips or sheets, or may be implemented after the making of the strips.

[0020] In the case of a planar magnetic induction circuit made of a metal strip, which has been cut to obtain the required geometric shape, the electrical insulation of this particular type of planar magnetic induction circuit is currently achieved using flexible plastic films, for example polyethylene terephthalate (PET), poly(ethylene naphthalate) (PEN), polyimide (PI), which typically have a thickness of a few tens to a few hundred microns. These films are cut to size.

[0021] Thus, in a planar magnetic induction machine, such as for example a planar electrical transformer, each planar magnetic induction circuit, made of a cut metal strip, is electrically isolated from the other circuits by at least one flexible film, generally planar.

[0022] However, this electrical insulation of a planar magnetic induction circuit, consisting of a cut metal strip, by means of flexible film(s), presents several disadvantages.

[0023] In operation, the planar magnetic induction circuits are traversed by electric currents and voltages.

[0024] Since all unitary magnetic induction circuits are not at the same electrical potential, a leakage current tends to be established between each magnetic induction circuit, both in the air and along the insulating material (flexible film).

[0025] In air, this leakage current takes the shortest path between each circuit. This shortest path in air between two circuits is usually characterized by a parameter designated as the "electrical insulation distance in air." If the electrical potential difference exceeds the electrical stiffness of air, an electric arc is established between the two magnetic induction circuits and can lead to the alteration or even destruction of the magnetic device. It should be noted that the electrical stiffness of air is affected by its humidity and especially by pressure. It is several times lower at altitude than at ground level, which has significant implications, for example, for the design of a magnetic device installed in an aircraft.

[0026] Along the insulating material, the path traveled by the leakage current is characterized by a parameter designated as the "Current Tracking Coefficient." If the electrical potential difference is too high, the current tracking resistance will be insufficient, and an electric arc will form between the two circuits, leading to damage or even destruction of the magnetic induction machine. Depending on the nature of the organic material used for the insulating films, the current tracking resistance of a leakage electric current varies. It is characterized by a Current Tracking Index (CTI). Pollution present on the surface of the insulating film also reduces the current tracking resistance. A pollution index is therefore generally added to the CTI.

[0027] For magnetic induction machines implementing planar magnetic induction circuits based on cut strips electrically insulated by means of insulating film(s), taking into account electrical isolation distances and path distances has an important impact on the size of these devices.

[0028] International standards, for example TI IEC 62497-1 in railways, set the minimum distance to be respected according to the class of the insulating material, the degree of ambient pollution and a voltage.

[0029] For example, for a voltage of 1000V, use at low altitude (<2000m), a medium group material (II), and a medium pollution level (PD2), this distance is 7.1mm. This therefore requires the manufacturer, on the one hand, to increase the overlap of the insulating film to comply with these minimum distances and, on the other hand, to lengthen the distance between the magnetic induction circuits and the ferrites, which then reduces the magnetic field strength in the circuits. The result is a less compact magnetic machine with lower efficiency.

[0030] Furthermore, when a planar magnetic induction circuit, consisting of a metal strip, and another nearby conductive circuit, and in particular another planar magnetic induction circuit consisting of a metal strip, are subjected to different potentials, an electric field is established between them. Due to point effects, these fields are maximal at the edges of the metal strip(s). If the electric field strength at these points exceeds the electrical strength of dry air (on the order of 30 kV per cm), the air ionizes and micro-discharges ("partial discharges") can occur regularly and detrimentally. Eventually, these discharges progressively deteriorate the insulating material, until it fails completely and an electric arc is created between the conductors.To avoid these phenomena, manufacturers of magnetic induction machines are forced to limit the maximum permissible voltages and / or increase the thickness of the insulation. (thickness of flexible films). This results in a magnetic machine with less power and / or less compact size.

[0031] Finally, and to a disadvantage, designers of magnetic induction machines comprising one or more planar magnetic induction circuits, based on cut strips and electrically insulated by means of one or more insulating films, are limited in their technological choices of these films, for which they cannot freely determine an optimal thickness. In practice, they are thus forced to restrict themselves to the standard thicknesses of the film manufacturer and cannot define an optimal insulation thickness. Presentation of the invention

[0032] An objective of the invention is to propose a new technical solution which makes it possible to overcome the aforementioned disadvantages inherent in electrical insulation by means of one or more insulating films, or at least one metal strip, which has been cut so as to form a planar magnetic induction circuit. Summary of the invention

[0033] The invention thus relates first to a magnetic induction component comprising a metal strip, which has been cut to form a planar magnetic induction circuit. The planar magnetic induction circuit is coated with a resin, which is deposited by immersing the planar magnetic induction circuit in a bath of liquid resin and by cross-linking the resin while the planar magnetic induction circuit is immersed so as to form a dielectric, electrically insulating coating that completely covers both faces and the edges of the planar magnetic induction circuit, including the edges at the junction between each face and each edge, with the possible exception of one or more electrical connection areas of the planar magnetic induction circuit.

[0034] The complete coating of the strip, with the possible exception of one or more localized electrical connection areas, provides complete electrical insulation of the conductor from the air, which makes it possible to do away with the minimum distance of electrical path in the air and in general to produce more compact magnetic induction machines with better efficiency.

[0035] More particularly, in the case of a magnetic induction machine, for example of the electrical transformer type, comprising a stack of several magnetic induction components according to the invention, the space between each planar magnetic induction circuit and the peripheral ferrite of the magnetic circuit is reduced to the thickness of the casing plus a slight functional clearance allowing the mounting of the magnetic induction components. The magnetic field is therefore stronger, because the magnetic induction circuits can be closer to the magnetic circuit. The magnetic induction machine is therefore more compact and offers better efficiency.

[0036] The complete coating of the cut strip also advantageously raises the voltage threshold at which partial discharges occur. Indeed, the most intense electric field is initially present at the edges (point effect) of the strip(s). Since these edges are coated with resin, the ambient air is separated from them by the thickness of the resin. The electric field is therefore less intense at these edges. This makes it possible to increase the operating voltage of the magnetic induction component without the risk of partial discharges. The magnetic induction component can thus switch more power.

[0037] The thickness of the coating on the planar magnetic induction circuit is freely adjustable. The designer of the magnetic induction component can thus dimension these thicknesses more precisely and optimally, without being constrained by the choice of a standard thickness from a film manufacturer. The magnetic induction component can therefore be more efficient.

[0038] Optionally, according to the invention, the magnetic induction component of the invention may also include the following optional technical features, taken individually or in combination: - The coating is multi-layered. - The said resin is a sand-cured photo-hardening resin. - The resin contains inorganic matter fillers. - Inorganic material fillers are selected from the following list: silicon dioxide (SiO2) and / or alumina (Al2O3) and / or boron nitride (h-BN), and / or silicon carbide (SiC), and / or titanium dioxide (TiO2). - The resin contains ferroic fillers such as barium titanate (BaTiO3). - The planar magnetic induction circuit forms a loop or a winding of several spiral-shaped loops. - The planar magnetic induction circuit forms a flat coil.

[0039] The invention has as its second object a planar inductance comprising at least one of the aforementioned magnetic induction components.

[0040] The invention has as its third object an electrical transformer comprising at least one of the aforementioned magnetic induction components.

[0041] Preferably, the electrical transformer comprises a stack of at least one planar magnetic induction circuit and at least two of the aforementioned magnetic induction components, and said planar magnetic induction circuit being sandwiched between said magnetic induction components.

[0042] The invention has as its fourth object a method for manufacturing a magnetic induction component in which a planar magnetic induction circuit obtained by cutting a metal strip is immersed in a bath of liquid resin, and the said resin is crosslinked while the planar magnetic induction circuit is immersed, so as to form a planar magnetic induction circuit, and the crosslinking of said resin so as to form a dielectric, electrically insulating coating which completely covers both faces and the edges of the planar magnetic induction circuit, including the edges at the junction between each face and each edge, with the possible exception of one or more electrical connection areas of the planar magnetic induction circuit.

[0043] Optionally, according to the invention, the manufacturing process of the invention may also include the following optional technical features, taken individually or in combination: - The resin is photocurable and crosslinking is achieved at least by irradiating the resin with light radiation. - The coating is a multi-layer coating obtained by iterative formation of several superimposed layers of cross-linked resin. - The crosslinking of the resin is achieved by carrying out several successive crosslinking operations and by moving the planar magnetic induction circuit in the liquid resin bath before each crosslinking operation, so as to form, at each crosslinking operation, an additional layer of the multilayer coating. - To obtain a complete coating of the planar magnetic induction circuit, in a first phase, a partial coating of the planar magnetic induction circuit immersed in the resin bath is carried out by cross-linking the resin, said partial coating completely covering at least one of the faces of the planar magnetic induction circuit, then in a second phase the planar magnetic induction circuit is turned over and the coating of the planar magnetic induction circuit immersed in the resin bath is completed by cross-linking the resin, so as to completely cover at least the other face of the planar magnetic induction circuit and to obtain a final coating completely covering both faces and the edges of the planar magnetic induction circuit, including the edges at the junction between each face and each edge, with the possible exception of one or more electrical connection areas of the planar magnetic induction circuit. - The resin is a photocurable and the crosslinking of the resin is achieved at least by irradiating the liquid resin bath with light radiation. - Regardless of the variant, the resin can also be thermosetting and the magnetic induction component is also exposed to a heat source in order to obtain a more complete crosslinking of the resin. Brief description of the figures

[0044] Other features and advantages of the invention will become more apparent upon reading the following detailed description of several embodiments of the invention, which detailed description is given by way of non-limiting and non-exhaustive example of the invention, and with reference to the accompanying drawings in which:

[0045] [Fig-1] Fig. 1 is an isometric perspective view of a first variant particular embodiment of a magnetic induction component, which conforms to the invention and whose magnetic induction circuit forms a two-turn spiral.

[0046] [Fig.2] The [Fig.2] is an isometric perspective view of the planar magnetic induction circuit of the magnetic induction component of the [Fig.1].

[0047] [Fig.3] The [Fig.3] is a cross-sectional view of the magnetic induction component of the [Fig.1] in the section plane III-III.

[0048] [Fig.4] The [Fig.4] is an isometric perspective view of a second particular embodiment of a magnetic induction component, which is in accordance with the invention and whose magnetic induction circuit forms a two-turn spiral.

[0049] [Fig.5] The [Fig.5] is a cross-sectional view of the magnetic induction component of the [Fig.4] in the cutting plane VV.

[0050] [Fig.6] The [Fig.6] is a schematic top view of a third particular embodiment of a magnetic induction component, which is in accordance with the invention and whose magnetic induction circuit forms a flat coil.

[0051] [Fig.7] The [Fig.7] is an isometric view of an example of a planar electrical transformer, which is manufactured by stacking several magnetic induction components according to the invention.

[0052] [Fig.8] The [Fig.8] is an exploded view of the planar electrical transformer of the [Fig.7]. Detailed description

[0053] Figure [1] shows a first particular embodiment of a magnetic induction component IA, which includes a planar magnetic induction circuit 10 ([Fig.2]), obtained by cutting a metal strip of constant thickness E.

[0054] This cutting is for example carried out by stamping or by laser cutting or water jet cutting.

[0055] This metal strip can be obtained from a metal sheet or metal strip. Without limiting the scope of the invention, this metal strip can for example be made of copper or aluminium, and can for example have a thickness E between 0.5mm and 1mm.

[0056] The planar magnetic induction circuit 10 thus comprises two main opposite faces 100 and 101, which are substantially parallel and oriented parallel to the plane (X,Y) of figures 1 and 3, slices 102 which correspond to the thickness of the circuit, which are oriented substantially perpendicular to the two main faces 100 and 101 and which extend over the entire length of the circuit, and edges 103 at the junction between each main face 100, 101 and each slice 102.

[0057] At its two ends, this planar magnetic induction circuit 10 has respectively two zones 10a and 10b forming two electrical connection terminals of the planar magnetic induction circuit 10, so as to be able to form a closed electrical circuit.

[0058] In the particular example of [Fig.1], the planar magnetic induction circuit 10 forms a two-turn winding in the shape of a flat spiral.

[0059] In another embodiment, the planar magnetic induction circuit 10 may also consist of a single turn or may form a winding comprising more than two non-contiguous turns. The turns may be more or less spaced apart from each other and have a square, circular, or other type of geometry.

[0060] With reference to the magnetic induction component IC of [Fig.6], in another variant, the planar magnetic induction circuit 10 can also have, for example, the shape of a flat coil.

[0061] With reference to Figures 1 and 3, the planar magnetic induction circuit 10 is completely coated with a dielectric resin, which, after cross-linking, forms a solid dielectric coating 11, electrically insulating, covering completely both faces 100 and 101 and the edges 102 of the cut metal strip, including the edges 103, with the possible exception of the two aforementioned electrical connection zones 10a and 10b ([Fig.1]).

[0062] In the particular variant of Figures 1 and 3, and in the particular variant of [Fig.6], the coating 11 fills the spaces between the turns of the winding of the magnetic induction component 1A or IC.

[0063] In another variant, such as that illustrated in Figures 4 and 5, the encapsulation 11 of the magnetic induction component IB can be made so as to completely and as closely as possible encapsulate the planar magnetic induction circuit 10, over the entire length of this circuit, with the possible exception of the electrical connection areas 10a and 10b, and without filling the spaces between turns.

[0064] In another embodiment, the two electrical connection zones 10a and 10b can also be completely covered by the encapsulation 11; in this In this case, access to these two zones 10a and 10b, electrical connection of circuit 10, can be achieved in a second step by drilling through the coating 11.

[0065] This complete encapsulation 11 of the planar magnetic induction circuit 10 makes it possible to improve the electrical insulation of the planar magnetic induction circuit 10 by obtaining the advantages previously described (see "Summary of the invention").

[0066] The resin can form a single-layer coating 11.

[0067] Preferably however, the coating 11 is a multilayer coating, in particular obtained by iterative formation of several superimposed layers.

[0068] The electrical resistance of a multilayer dielectric coating 11 is advantageously greater than that of a single dielectric layer of the same thickness (concept of transport charge and molecular displacement).

[0069] The thickness of the single-layer coating 11 or of each layer of the multi-layer coating 11 can advantageously be precisely controlled and adapted on a case-by-case basis.

[0070] The resin forming said coating 11 can be made up of any type of dielectric, electrically insulating resin, and more particularly of a thermosetting resin or a photosetting resin which can be applied initially in the form of a more or less viscous liquid and can subsequently be hardened (reticulation of the resin) to obtain the final solid coating 11.

[0071] Preferably, a resin that is photocurable by means of suitable radiation, for example UV radiation, will be chosen because the polymerization (crosslinking) of this type of resin is much faster than that of a thermosetting resin whose polymerization is obtained by supplying thermal energy only.

[0072] Thermal catalysts may also be introduced into the resin to achieve thermal hardening of areas that cannot receive light radiation. These catalysts will be chosen so as not to react to the encapsulation temperature of the conductors (80°C and above).

[0073] Furthermore, whatever the resin used to make the coating 11, it is possible, but not essential according to the invention, to add micro and / or nanometric inorganic fillers to the resin.

[0074] These charges - depending on their nature - will improve the performance of the insulation:

[0075] - Thermal conductivity:

[0076] The heat from the conductors (heating by Joule effect) can be better dissipated outwards. The magnetic induction component 10 can thus be used to switch more power without excessive internal heating.

[0077] - Electrical aging (resistance to partial discharges):

[0078] Inorganic fillers are much more resistant to electric arcs than the organic matter constituting the resin, which makes it possible to increase the life of the magnetic induction component 10.

[0079] - Thermal resistance:

[0080] Inorganic fillers impart consistency to the resin thus filled. Since these fillers only deteriorate at very high temperatures (at least several hundred degrees), a resin thus filled has better heat resistance. The magnetic induction component 10 can therefore be classified in a higher thermal class.

[0081] - Reduction of the intensity of the electric field in the encapsulation 11:

[0082] By utilizing the ferroic properties of certain fillers, it is possible, through the electret effect, to reduce the electric field concentration in the encapsulation 11. The partial discharge voltage threshold will be raised. This then makes it possible to increase the operating voltage of the magnetic induction circuit 10 without the risk of partial discharges. The magnetic induction component 10 can thus be used to switch more power.

[0083] - Improved resistance to electrical path:

[0084] Inorganic fillers on the surface of the coating 11 will impede the flow of electric current from one potential to another. The connections can be brought closer together. The magnetic induction component 10 can thus be used to create a more compact magnetic machine.

[0085] By way of non-limiting and non-exhaustive examples, silicon dioxide (SiO2), alumina (Al2O3), barium sulfate (BaSO4), boron nitride (h-BN), silicon carbide (SiC), or titanium dioxide (TiO2) can be used alone or in combination as inorganic fillers, depending on the desired objectives. Barium titanate (BaTiO3) can also be used as a ferroic filler. All these fillers can be micrometric and / or nanometric in size.

[0086] By way of example only, and without limiting or exhaustively listing the invention, the resin may be an organic compound whose characteristics may be:

[0087] - dynamic viscosity: 100 to 4000 rnPa.s,

[0088] and / or

[0089] - temperature class: (E 120°C, F 155°C, H 180°C, N 200°C, R 220°C, etc.) in accordance with IEC 60085 standard,

[0090] and / or

[0091] - dielectric strength greater than or equal to 20 kV / mm,

[0092] and / or

[0093] - of a chemical nature selected from: polyurethane (PUR), thermoplastic elastomer (TPE), polyester acrylate, ...

[0094] In the case of a photocurable resin, the resin includes photoinitiating agents which are chosen according to their ability to crosslink the resin and the wavelength of the light source used.

[0095] One or more different types of photoinitiators may be used. Typically, photoinitiating agents may, for example, be TPO (Diphenyl(2,4,6-trimethylbenzoyl) oxide phosphine) or (Phenylbis(2,4,6-trimethylbenzoyl) oxide phosphine (BAPO).

[0096] When the resin is also thermosetting, the magnetic induction component can advantageously and optionally be exposed to a heat source to obtain more complete cross-linking of the resin, particularly in internal areas that cannot be exposed to a light source. This exposure to a heat source is preferably carried out after the magnetic induction component has been exposed to the aforementioned radiation. In this case, thermal catalysts from the peroxide family (e.g., tert-butyl peroxybenzoate or tert-butyl peroxybenzoate) can optionally be added to the resin.

[0097] Advantageously, the resin can be mixed with a diluent, for example isobornyl acrylate (IBOA). This diluent makes it possible to impart:

[0098] - superior flexibility to the coating after curing the resin,

[0099] - a lower viscosity for the resin, which facilitates its workability,

[0100] - an improved capacity for incorporating inorganic fillers into the resin as well than adjuvants.

[0101] Advantageously, a thixotropic agent can be added to the resin formulation to limit the fine-graining effects on the edges 103 of the circuit 10 before the resin hardens.

[0102] Advantageously, coupling agents can also be incorporated into the resin formulation. These agents—for example, of the "silane" type—promote the adhesion of the resin to a support and also facilitate the dispersion of inorganic fillers.

[0103] Examples of use of the magnetic induction component

[0104] The magnetic induction component of the invention can be used alone as a planar inductance (or inductor) or can be used in the making of a planar magnetic induction machine, such as for example an electrical transformer.

[0105] More particularly, in the case of a planar electrical transformer, the magnetic induction component of the invention can be used as a primary circuit, by electrically connecting the planar magnetic induction circuit 10 to a current or voltage source (not shown) so that it is traversed by an alternating electric current preferably of high power, typically of power greater than one kilowatt, and generates by electromagnetic induction a variable magnetic field oriented transversely to the plane (X, Y) of the magnetic induction component.

[0106] The magnetic induction component of the invention can also be used as a secondary circuit of a planar electrical transformer, so that the planar induction circuit 10 is traversed by an electric current when it is subjected to a variable magnetic field oriented transversely to the plane (X, Y) of the magnetic induction component.

[0107] By way of example, a planar transformer 2 comprising a stack 20 of several magnetic induction components 1 and several electrically conductive planar induction circuits 10' is shown in figures 7 and 8.

[0108] In this stack 20, the magnetic induction components 1 conform to the invention and each planar induction circuit 10' forms an electrically conductive winding in the shape of a flat spiral.

[0109] The magnetic induction components 1 and the planar induction circuits 10' are arranged alternately and are superimposed in direct contact, without the interposition of an additional insulator. Each planar induction circuit 10' is thus sandwiched between two magnetic induction components 1. Electrical insulation between each magnetic induction circuit 10' and each planar magnetic induction circuit 10 adjacent to a magnetic induction component 1 is achieved by means of the electrically insulating encapsulation 11 of each magnetic induction component 1.

[0110] The planar induction circuits 10 of the magnetic induction components 1 are connected or capable of being electrically connected to each other to form the primary (or respectively secondary) circuit of the transformer, which is intended to be connected to a voltage or current source. The planar induction circuits 10' of the magnetic induction components 1' are connected or capable of being electrically connected to each other to form the secondary (or respectively primary) circuit of the transformer.

[0111] This planar transformer 2 also includes a magnetic circuit consisting of an I-shaped ferrite 21 and an E-shaped ferrite 22, which are assembled so as to sandwich the stack 20 of the magnetic induction components 1 and the planar magnetic induction circuits 10'.

[0112] Examples of manufacturing methods for the magnetic induction component of the invention

[0113] The aforementioned coating 11 of the magnetic induction component can more particularly be achieved by implementing a resin spraying technique or can be achieved by additive manufacturing. Resin spraying manufacturing

[0114] The spraying process consists of fragmenting the resin, in liquid form, into microparticles and dynamically projecting it in a thin layer (for example on the order of 10 microns) onto the magnetic induction circuit 10.

[0115] Typically a propellant gas (compressed air or neutral gas) can be used to fractionate the resin in an injector and to project it in a thin layer onto the magnetic induction circuit 10.

[0116] Thus, in a first step (a), the liquid resin 11 is projected, in the form of microparticles, onto all surfaces (faces 100 and 101, slices 102 and edges 103) of the magnetic induction circuit 10, so as to form a thin layer of controlled thickness, which completely coats the magnetic induction circuit 10.

[0117] During this first step (a), the injector used to project the resin can be automatically moved relative to the magnetic induction circuit 10 and / or the magnetic induction circuit 10 can be automatically moved relative to the injector.

[0118] Alternatively, the electrical connection area(s) 10a and 10b of the magnetic induction circuit 10 can be temporarily masked (temporary application of a protective coating to the electrical connection areas 10a and 10b, which are then removed at the end of the process), so as not to be covered with resin and / or the spraying can be controlled automatically so as not to project resin onto the electrical connection areas 10a and 10b.

[0119] In a second step (b), the magnetic induction circuit 10 is then exposed to a suitable light source for the time required for the crosslinking of the resin layer.

[0120] The operation [steps (a) and (b)] is repeated as many times as necessary until a multilayer coating of the desired thickness (for example 200 microns) is obtained.

[0121] The advantage of the process is its ability to provide a perfectly controlled thickness for the final coating 11, including on the edges 103 of the conductor. Unlike the use of films that only insulate the faces and not the edges, the coating of the magnetic induction circuit 10 is complete, including on the edges, except possibly at the electrical connection areas 10a and 10b.

[0122] According to a second advantage, unlike overmolding a part, it does not require forming tooling (mold),

[0123] A third advantage is to allow, where appropriate, the targeted deposition within the total thickness of the coating 11 of layers loaded with ferroic particles or of a surface layer which increases the roughness of the surface of the coating 11

[0124] A fourth advantage of a multilayer deposit is to increase the electrical resistance of the coating 11 compared to a single layer of the same thickness (concept of transport charge and molecular displacement). Additive manufacturing

[0125] Several processes are available on the market and can be used interchangeably to make the coating 11 of the magnetic induction circuit 10.

[0126] Examples include:

[0127] - additive manufacturing by stereolithography (SLA 3D).

[0128] - additive manufacturing by image projection via a chip containing micro steerable mirrors (DLP 3D) and its improved continuous production version of CLIP liquid interfaces from CARBON 3D Corp.

[0129] - additive manufacturing by image projection via a liquid crystal mask (3D LCD)

[0130] These technologies are based on a platform which rises (or falls) in a bath of liquid resin contained in a tank, in combination with a light source which allows the bath of liquid resin to be irradiated, so as to form point by point (SLA3 3D) or layer by layer (DLP and LCD 3D) the desired coating; the light energy allows the resin to be hardened locally.

[0131] More specifically, the manufacture of a magnetic induction component of the invention is carried out as follows:

[0132] (1) the numerical model of the coating 11 to be produced is created,

[0133] (2) this model is sliced, each slice representing a layer at to manufacture,

[0134] (3) the magnetic induction circuit 10 is positioned flat on the platform; this circuit The magnetic induction 10 is held in place via non-permanent adhesive, localized clamping, suction, etc.

[0135] (4) The tray is placed in its original position in a tank containing a bath of Resin 11 in liquid form,

[0136] (5) The platform is then moved back to its starting position, so as to immerse the The magnetic induction circuit 10 is immersed at the appropriate depth in the liquid resin bath, depending on the desired thickness of the first coating layer. The 2D image of the first layer is projected—via the light source—onto one of the faces (e.g., the main face 100) of the magnetic induction circuit 10 immersed at the appropriate depth in the liquid resin bath. This irradiates the portion of the resin bath located between said face (e.g., the main face 100) and the magnetic induction circuit 10. magnetic induction circuit 10 and the light source. The resin hardens locally according to the projected image, through the action of photo-initiating agents, which trigger its crosslinking.

[0137] (6) the tray is moved in the liquid resin bath to the thickness of the layer next (typically 10 to 50 microns).

[0138] (7) the next image of the layer is projected, and the resin hardens over the thickness released between the light source and the previously hardened surface.

[0139] (8) Steps (6) and (7) are repeated as many times as there are layers to be reproduced.

[0140] (9) the magnetic induction circuit, which is coated, is then detached from the plate partially by several superimposed layers of cross-linked resin covering entirely one face (for example the main face 100), slices 102 and edges 103 of face 100, the other face 101 magnetic induction circuit and its edges not being coated.

[0141] (10) the partially encapsulated magnetic induction circuit 10 is reversed and repositions it on the platform; the partially coated magnetic induction circuit 10 is held in place via a non-permanent adhesive, by localized clamping or by suction, etc.

[0142] (11) The tray is placed in its original position in the tank containing the resin 11 in liquid form

[0143] (12) The platform is then moved to its starting position

[0144] (13) and additive manufacturing by multiple layers is continued on the other side 101 as for the first face 100, so as to completely cover the other face 101 and obtain the magnetic induction component which is insulated front and back, including on all its edges 102 and edges 103.

[0145] (14) the magnetic induction component is then detached from the plate

[0146] Back-and-forth movements of the platform between each layer made can to be triggered in order to promote the migration of resin into the work area.

[0147] A subsequent cleaning treatment with a solvent (such as isopropyl alcohol) can be carried out, as well as post-heating and / or curing under a light source.

[0148] The wavelength of light energy for crosslinking the resin layers is chosen according to the activation spectrum of the photoinitiator agents incorporated into the resin. Typically 355 nm in laser (3D SLA), a range of 365 nm–405 nm for 3D DLP and 3D LCD processes, or even in the lower part of the visible spectrum.

[0149] This process has the same advantages as those previously described for spray deposition.

[0150] It also offers several other advantages:

[0151] - the magnetic induction circuit 10 being immersed in the liquid resin bath during crosslinking, there are no microcavities of air encapsulated in the coating 11, which could be the site of partial discharges under an electric field.

[0152] - This process offers the possibility of creating particular shapes, beyond the simple coating of the magnetic induction circuit 10. Thus, by adding hardened resin, volumes, walls and protrusions can be created which will electrically isolate the other parts of the magnetic machine, increase electrical path distances or serve as geometric support.

[0153] - Additive manufacturing is selective. The layered digital model can predict to mask the electrical connection areas 10a, 10b so that resin does not harden over these areas. Therefore, there will be no need to install removable spacers over these areas.

[0154] Finally, halfway between the two technologies previously presented (spraying and additive manufacturing), it is also possible to produce the magnetic induction component of the invention using MJP 3D technology, based on targeted projection of photo-curable resin by means of a micro-nozzle matrix.

Claims

Demands

1. A method for manufacturing a magnetic induction component (IA; IB; IC) in which a planar magnetic induction circuit (10) obtained by cutting a metal strip is immersed in a bath of liquid resin, and said resin is crosslinked while the planar magnetic induction circuit (10) is immersed, so as to form a dielectric coating (11), which completely covers both faces (100; 101) and the slices (102) of the planar magnetic induction circuit (10), including the edges (103) at the junction between each face and each slice, with the possible exception of one or more electrical connection zones (10a; 10b) of the planar magnetic induction circuit (10).

2. A method according to claim 1, wherein the resin is photocurable and the crosslinking is achieved at least by irradiating the resin with light radiation.

3. A method according to any one of claims 1 or 2, wherein the coating (11) is a multilayer coating obtained by iterative formation of several superimposed layers of crosslinked resin.

4. A method according to any one of claims 1 to 3, wherein the crosslinking of the resin is obtained by carrying out several successive crosslinking operations and by moving the planar magnetic induction circuit (10) in the liquid resin bath before each crosslinking operation, so as to form, at each crosslinking operation, an additional layer of the multilayer coating (11).

5. A method according to any one of claims 1 to 4, wherein, in order to obtain complete encapsulation of the planar magnetic induction circuit (10), a partial encapsulation of the planar magnetic induction circuit (10) immersed in the resin bath is carried out in a first phase by cross-linking the resin, said partial encapsulation completely covering at least one face (100) of the planar magnetic induction circuit (10), and then in a second phase the planar magnetic induction circuit (10) is turned over and the encapsulation of the planar magnetic induction circuit (10) immersed in the resin bath is completed by cross-linking the resin, so as to completely cover at least the other face (101) of the induction circuit

6. planar magnetic (10) and to obtain a final coating completely covering both faces (100; 101) and the slices (102) of the planar magnetic induction circuit (10), including the edges (103) at the junction between each face and each slice, with the possible exception of one or more areas (10a; 10b) of electrical connection of the planar magnetic induction circuit (10). A method according to any one of claims 1 to 5 comprising the following successive steps: (1) we create the digital model of the coating (11) to be produced; (2) this model is cut into slices, each slice representing a layer to be manufactured; (3) the magnetic induction circuit (10) is positioned flat on a platform, the magnetic induction circuit (10) being held in place; (4) the tray is placed at an origin position in a tank containing a bath of liquid resin (11); (5) the platform is moved to its starting position, so as to immerse the magnetic induction circuit (10) to the appropriate depth in the liquid resin bath, depending on the desired thickness of the first coating layer, and the 2D image of the first layer is projected, via a light source, onto a first face of the magnetic induction circuit (10) immersed to the appropriate depth in the liquid resin bath and the part of the liquid resin bath located between said first face of the magnetic induction circuit (10) and the light source is thus irradiated, and the resin hardens locally according to the projected image; (6) the tray is moved into the liquid resin bath to the thickness of the next layer, and preferably from 1 Opm to 50 pm; (7) the image of the next layer is projected and the resin hardens on the thickness released between the light source and the previously hardened surface; (8) steps (6) and (7) are repeated as many times as there are layers to reproduce; (9) the magnetic induction circuit is detached from the plate, which is partially coated by several superimposed layers of cross-linked resin covering only one face; (10) the partially coated magnetic induction circuit (10) is turned over and repositioned on the platform, the partially coated magnetic induction circuit (10) being held in place; (11) the platform is placed in its original position in the tank containing the resin (11) in liquid form; (12) the platform is moved to its starting position; (13) additive manufacturing is continued by multi-layer on the other side as for the first side, so as to completely coat the other side and obtain a magnetic induction component whose magnetic induction circuit (10) is insulated on front and back, including on all its edges (102) and edges (103); (14) the magnetic induction component is detached from the platform.

7. A method according to claim 6, wherein volumes, walls and protrusions are created by adding hardened resin.

8. A method according to any one of claims 1 to 7, wherein the resin is further thermosetting and the magnetic induction component (IA; IB; IC) is also exposed to a heat source, in order to obtain more complete crosslinking of the resin.

9. A method according to any one of claims 1 to 8, wherein the liquid resin bath comprises inorganic material fillers.

10. A method according to claim 9, wherein the inorganic material fillers are selected from the following list: silicon dioxide (SiO2) and / or alumina (Al2O3) and / or boron nitride (h-BN), and / or silicon carbide (SiC), and / or titanium dioxide (TiO2).

11. A method according to any one of claims 1 to 10, wherein the liquid resin bath comprises ferroic fillers such as, for example, barium titanate (BaTiO3).

12. A method according to any one of claims 1 to 11, wherein the thickness of the coating layer or of each coating layer in the case of a multilayer coating is between 5 µm and 50 µm and more preferably is on the order of 25 µm

13. A manufacturing method in which at least one magnetic induction component is manufactured by implementing the method according to any one of claims 1 to 12, and said at least one magnetic induction component is used to manufacture a planar inductance or to manufacture an electrical transformer.

14. Method according to claim 13, wherein at least two magnetic induction components are manufactured by implementing the method according to any one of claims 1 to 12, and an electrical transformer is manufactured comprising a stack (20) of at least one planar magnetic induction circuit (10') sandwiched between said magnetic induction components (1).

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