Load converter for converting alternating current to low-voltage direct current

Abstract

Load converter for converting alternating current into low voltage direct current. The invention relates to a load converter for converting alternating current into low voltage direct current, comprising a transformer (100) comprising: a plurality of adjacent cells (C1, C2, C3, C4), a magnetic core (110) comprising a first leg (111, 121, 131, 141) and a second leg (112, 122, 132, 142) per cell, and in each cell (C1, C2, C3, C4): a primary winding (10), a secondary winding (20) and a tertiary winding (30) wound around the first leg and one of the primary winding and the secondary winding wound around the second leg, and an inductor (40) connected in series;the primary winding (10), respectively the secondary winding (20), of one cell being connected in series with the primary winding, respectively the secondary winding, of an adjacent cell, and the tertiary winding (30) of one cell is connected in parallel with the tertiary winding of the adjacent cell. (Figure 2);

Description

Title of the invention: Load converter for converting alternating current into low-voltage direct current

[0001] The present invention relates to the field of load converters for current conversion intended for use in an electric or hybrid vehicle. More particularly, the invention relates to a converter for converting alternating current into low-voltage direct current.

[0002] An electric vehicle or a hybrid vehicle comprises an electric drive system and several auxiliary electrical components (such as the on-board computer, audio equipment, headlights, etc.). The electric drive system is powered by a high-voltage battery (generally between 100 and 900V). The auxiliary components are powered by a low-voltage battery (typically 12, 24, or 48V).

[0003] In order to ensure the charging of the high-voltage supply battery and the low-voltage supply battery, the vehicle is equipped with two converters.

[0004] The first converter is an on-board charger (also known by the abbreviation OBC) which receives an alternating current (also called AC) input from an external electrical network. The on-board charger outputs a high-voltage direct current (DC).

[0005] The on-board charger thus comprises two magnetic power components: a power inductor, which is part of the circuit that converts alternating current into high-voltage direct current, and a high-frequency transformer that transforms the high-voltage direct current into isolated high-voltage direct current (also called an isolated high-voltage DC-DC transformer). The on-board charger allows the high-voltage power supply battery to be recharged.

[0006] The second converter is a DC-DC converter that converts the isolated high-voltage direct current from the on-board charger into a low-voltage direct current (also called isolated high-voltage DC-DC). It includes a high-frequency transformer. This second DC-DC converter powers the low-voltage supply battery to meet the needs of the vehicle's auxiliary equipment, i.e., low-power equipment such as the on-board computer, headlights, etc.

[0007] Until now, the on-board charger and the DC-DC converter were installed in the vehicle as two separate units connected to each other, each having its In the interest of compactness, new solutions have appeared on the market in which the onboard charger and the DC-DC converter are housed in the same casing. This notably reduces the onboard volume.

[0008] More specifically, in such a product of these new solutions, the on-board charger, which includes several magnetic components, and the DC-DC converter are integrated into a single housing. This is a rather complex mechatronic integration. While such a solution can be deployed rapidly because the component parts already exist, the final product has high production costs and low repeatability in the assembly process. Existing solutions are therefore not entirely satisfactory.

[0009] In order to improve this type of converter, it is desirable to reduce the number of semiconductors while ensuring a good level of current conversion performance, if possible with a reduced mass and size of the converter.

[0010] The present invention falls within this context and aims to provide a load converter for converting an alternating current into a low voltage direct current combining the functions of an on-board charger and an easy-to-manufacture DC-DC converter, comprising few parts and modular in terms of available power.

[0011] To this end, the invention relates to a load converter for converting alternating current into low-voltage direct current and high-voltage direct current, comprising an alternating current-to-direct current converter and a transformer for converting direct current into low-voltage direct current and high-voltage direct current, characterized in that the transformer comprises: - a plurality of adjacent cells, - a magnetic core comprising a first leg and a second leg per cell,

[0012] and in each cell: a primary winding, a secondary winding and a tertiary winding wound around the first leg and one among the primary winding and the secondary winding wound around the second leg and an inductor connected in series;

[0013] and in that the primary winding, respectively the secondary winding, of a cell is connected in series with the primary winding, respectively the secondary winding, of an adjacent cell, and the tertiary winding of a cell is connected in parallel with the tertiary winding of the adjacent cell.

[0014] Magnetic components are an important element in a load converter. Market requirements for power transmission are evolving. The goal is to deliver more power while simultaneously miniaturizing the size of magnetic components. Furthermore, component assembly methods must to be as simple as possible in order to reduce manufacturing costs. The converter of the invention meets all these requirements, as will become apparent from reading the description of the invention.

[0015] Thanks to the characteristics of the charge converter of the invention, the two high-frequency transformers of the on-board charger and the DC-DC converter are judiciously integrated into a single transformer. In other words, instead of having two high-frequency transformers as is the case in prior art solutions, the invention uses only a single transformer with an innovative winding arrangement.

[0016] In the context of the invention, the transformer is divided into several cells. On the high-voltage side, for the primary and secondary windings, the cells are connected in series. On the low-voltage side, for the tertiary winding, the cells are connected in parallel. Since the currents are higher, connecting them in parallel reduces copper losses in the windings.

[0017] Such a converter combines the transformer and the inductor. This results in a considerable reduction in the size of the components. The converter of the invention has the advantages of being small, lightweight, and easy to assemble.

[0018] In the load converter of the invention, the transformer comprises several cells. Each cell can supply a predetermined power, for example, 1 kW (kilowatt). It is thus possible to adapt the number of cells in the transformer according to the required output power of the converter. Since market demand is for a converter output power of 2 kW, the transformer in this case comprises at least two cells. The number of cells is a compromise between the maximum required output power and the converter's size. This number of cells could be, for example, six. In the following, the invention will be described with a non-limiting example of four cells.

[0019] According to an optional feature of the invention, the first and second legs are parallel to each other. The magnetic core extends between a lower wall and an upper wall, both in an XY plane of an orthonormal coordinate system defined by the X, Y, and Z axes. The lower and upper walls are parallel to each other. The magnetic core also includes two lateral walls that delimit it. The lateral walls extend between the lower and upper walls, perpendicular to the lower and upper walls. The lateral walls extend perpendicularly to the XY plane. In other words, they extend in an XZ plane.

[0020] The first legs and the second legs extend from the lower wall, perpendicular to the lower wall and parallel to the side walls. Each Each cell consists of a first leg and a second leg that are aligned. The cells are arranged side by side, parallel to each other. In other words, the cells are distributed between the two lateral walls of the magnetic core. It follows that the first and second legs are parallel to each other within the same cell, and the first and second legs of different cells are also parallel to each other.

[0021] This parallel arrangement of the legs allows the primary, secondary, and tertiary windings of the transformer to be formed around the legs. In all embodiments of the invention, the primary, secondary, and tertiary windings are formed around the first legs. Depending on the embodiment considered, either the primary or secondary winding is formed around the second legs.

[0022] According to an optional feature of the invention, the primary, secondary, and tertiary windings are wound in a first direction within one cell and in a second direction, opposite to the first, in the adjacent cell. For example, to generate the desired inductance, the secondary winding must surround the first and second legs of each cell. However, the winding around the legs in one cell is carried out in one direction, and the winding around the legs in the adjacent cell must be carried out in the opposite direction in order to generate a magnetic flux on the opposing magnetic material. This helps to reduce losses in the core in general at the transformer level.

[0023] According to an optional feature of the invention, the primary and secondary windings are interlaced around the first leg of each cell to form a main interlacing, and the tertiary winding is wound on either side of the main interlacing. This specific stacking is used to reduce copper losses in the component.

[0024] According to an optional feature of the invention, the transformer further comprises, in each cell, a shielding layer wound on either side of the main winding, between the main winding and the tertiary winding. The shielding layer may be made of copper traces. The shielding layer is connected to the product ground. This improves performance in terms of electromagnetic noise.

[0025] According to an optional feature of the invention, the tertiary winding being the first tertiary winding, the transformer further comprises a second tertiary winding, the second tertiary winding of a cell being connected in parallel with the second tertiary winding of the adjacent cell, and the first The tertiary winding is wound on one side of the main interleave and the second tertiary winding is wound on the other side of the main interleave.

[0026] The presence of the two tertiary windings around the primary and secondary windings allows for a balancing of the current of the two tertiary windings.

[0027] According to an optional feature of the invention, each of the windings being wound around a leg in a plurality of layers, the transformer comprises an electronic board having openings and superimposed tracks wound around the openings, the tracks forming the windings and each leg passing through an opening of the electronic board.

[0028] Thanks to electronic board technology, it is easy to implement the interlacing according to the specific arrangement of the invention, while allowing for a high power density. The electronic board contains all the transformer windings. Depending on the winding configuration considered, the same trace is wound around the openings of the electronic board. The stacking of the windings is made possible by vias that allow the connection between the different layers of the electronic board.

[0029] According to an optional feature of the invention, the magnetic core comprises: - a lower wall from which the legs rise to a leg height, - two side walls rising from the lower wall to a wall height greater than or equal to leg height, - a top wall in contact with the two side walls.

[0030] This arrangement of the magnetic core with first and second legs allows for winding around the legs with minimal bulk. Such a magnetic core is also easily adaptable to the required output power of the converter.

[0031] According to an optional feature of the invention, the wall height of the two side walls is greater than the leg height of the legs. This means that the upper surface of the first and second legs does not come into contact with the upper wall of the magnetic core. There is therefore a gap between the upper end of the legs and the upper wall of the core. The height of this gap can be adjusted to define an air gap. For example, epoxy resin can be applied to the upper end of the legs to adjust the height of the gap. A series of layers of epoxy resin and ferrite can thus be used. This variation in the height of the gap reduces copper losses in the windings around the legs and affects the resulting inductance value.

[0032] The invention also covers a motor vehicle comprising an on-board network configured to be powered by a low voltage direct current, the vehicle being configured to be connected to an alternating current network, the motor vehicle comprising such a load converter.

[0033] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0034] [Fig. 1] schematically represents a load converter capable of converting an alternating current into a low voltage direct current and into a high voltage direct current according to the invention,

[0035] [Fig.2] schematically represents a cross-sectional view of the magnetic core of the converter of the invention,

[0036] [Fig.3] schematically represents one embodiment of the windings in the converter of the invention,

[0037] [Fig.4] schematically represents a cross-sectional view of the magnetic core of the converter of the invention with an indication of the winding directions,

[0038] [Fig.5] schematically represents another embodiment of the windings in the converter of the invention,

[0039] [Fig.6] schematically represents another embodiment of the windings in the converter of the invention,

[0040] [Fig.7] schematically represents another embodiment of the windings in the converter of the invention,

[0041] [Fig.8] schematically represents a view of the complete magnetic core of the converter of the invention,

[0042] [Fig.9] schematically represents a motor vehicle comprising a converter of the invention.

[0043] The features, variants, and different embodiments of the invention, as described or as they will be presented in the detailed description that follows, can be combined in various ways, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0044] For the sake of clarity, the same elements are designated by the same references in the different figures.

[0045] Figure 1 schematically represents a load converter 300 capable of converting alternating current (AC) into low-voltage direct current (DC LV) and high-voltage direct current according to the invention. The load converter 300 comprises an AC-to-DC converter 310 and a transformer 100 for converting the DC output from converter 310 into low-voltage DC LV and high-voltage direct current. As will become apparent from the description of the invention below, the converter of the invention combines the functionality of an on-board charger with that of a DC-DC converter by combining the transformer of the on-board charger and that of the DC-DC converter.To achieve this, it comprises cells, a magnetic core, and a specific arrangement of high-voltage windings (primary and secondary windings) and low-voltage windings (tertiary windings), explained below.

[0046] As shown in [Fig. 1], the converter 310 receives an alternating current (AC) at its input. It is an AC / DC converter including a power factor corrector (also known by its abbreviation PFC). A capacitive filtering device 311, also called a link capacitor and more commonly known by its English term "DC-link capacitor," is connected to the output of the converter 310. The capacitive filtering device 311 smooths the DC voltage supplied to the transformer 100. The transformer 100 transforms this DC voltage into two DC voltages: a high voltage and a low voltage. The transformer 100 is described in detail below.

[0047] Fig. 2 schematically represents an isometric view of the magnetic core 110 and a cross-sectional view in the transverse XY plane of the magnetic core 110 of the transformer 100 of the converter of the invention.

[0048] In the embodiment illustrated in [Fig. 2], the transformer comprises four cells C1, C2, C3, C4. This is an illustrative example, and a different number of cells does not depart from the scope of the invention. Each cell delivers a specific power, for example, 1 kW. Since the transformer comprises four cells, it can deliver 4 kW at the output. This transformer configuration has the advantage of allowing the number of cells to be modulated according to the required output power of the converter. For example, if a power of 8 kW is desired, the transformer will comprise eight cells, each delivering 1 kW.

[0049] The transformer 100 comprises a magnetic core 110 including, per cell, a first leg 111, 121, 131, 141 and a second leg 112, 122, 132, 142. As shown in [Fig. 2], cell C11 comprises the first leg 111 and the second leg 112. Cell C2 is adjacent to cell C11, that is, it is arranged next to cell C11 in the XY plane. Cell C2 comprises the first leg 121 and the second leg 122. On the same principle, cells C3 and C4 include respectively the first legs 131, 141 and the second legs 132, 142.

[0050] Although represented in parallelepiped shape, the legs are not limited to this shape.

[0051] The magnetic core 110 is made of ferromagnetic material, for example ferrite.

[0052] In each cell C1, C2, C3, C4, the transformer 100 comprises a primary winding 10, a secondary winding 20, and a tertiary winding 30 wound around the first leg 111, 121, 131, 141, and one of the primary and secondary windings wound around the second leg 112, 122, 132, 142. It also comprises an inductor 40 connected in series. Furthermore, the primary winding 10 and the secondary winding 20 of one cell are connected in series with the primary winding 10 and the secondary winding 20 of an adjacent cell, and the tertiary winding 30 of one cell is connected in parallel with the tertiary winding 30 of the adjacent cell. These windings are visible in [Fig. 3].

[0053] Figure 3 schematically represents an embodiment of the windings in the converter of the invention. On the right of the figure, the series connection of the primary winding 10 and secondary winding 20 and of the inductor 40 between cells C1, C2, C3, C4 is shown. The parallel connection of the tertiary winding 30 is also shown.

[0054] The different windings per leg are illustrated on the left side of the figure. As shown, this represents the stacking of the windings along the height of a leg, i.e., along the Z-axis. At cell C1, the primary winding 10, the secondary winding 20, and the tertiary winding 30 are wound around the first leg 111. The secondary winding 20 is wound around the second leg 112. Similarly, at cell C2, the primary winding 10, the secondary winding 20, and the tertiary winding 30 are wound around the first leg 121. The secondary winding 20 is wound around the second leg 122. A winding is understood to mean at least one turn. Each winding thus comprises at least one turn wound around a leg. In the illustrated example, the secondary winding 20 around the second leg of one of the cells comprises a winding of three turns around the leg.This is yet another illustrative example to describe the invention, but it should not be understood as exhaustive.

[0055] According to an optional feature of the invention, the primary, secondary, and tertiary windings are interlaced. In other words, one turn of the winding The secondary winding is sandwiched between two turns of the primary winding. Similarly, one turn of the primary winding is sandwiched between two turns of the secondary winding. This means that two turns of the same winding are not directly overlapped around their legs. This specific winding stacking reduces the proximity effect and thus limits component losses.

[0056] For each cell C1, C2, C3, C4, the primary winding 10 and the secondary winding 20 are intertwined around the first leg 111, 121, 131, 141 of the cell. The stacking of the turns of the primary winding 10 and the secondary winding 20 forms a main intertwining 50. The tertiary winding 30 is wound on either side of the main intertwining 50.

[0057] The main interlacing 50 is thus arranged between at least two turns of the tertiary winding 30. This distribution of the tertiary winding 30 around the main interlacing 50 ensures a balancing of the current of the two tertiary windings 30.

[0058] Figure 4 schematically represents a cross-sectional view in the XY plane of the magnetic core 110 of the converter of the invention, indicating the winding directions. The primary winding 10, the secondary winding 20, and the tertiary winding 30 are wound in a first direction SI in one cell and in a second direction S2, opposite to the first direction SI, in the adjacent cell. The winding direction of each cell must be opposite to the winding direction of its adjacent cell(s) in order to generate an opposing magnetic flux between two adjacent cells. This ensures the cancellation of magnetic fluxes on the walls of the magnetic core, thereby minimizing core losses.

[0059] The space between the first legs determines the value of the magnetizing inductance. The space between the second legs determines the value of the series inductance.

[0060] Based on Figures 3 and 4, and considering cell Cl, it can be understood that the primary winding 10 and tertiary winding 30 are wound around the first leg 111. The secondary winding 20 is wound around the first leg 111 and the second leg 112. This creates an additional flux in the secondary winding that is not related to the primary and tertiary windings. This results in a series inductance of the secondary winding.

[0061] The second legs 112, 122, 132, 142 produce the inductances and the first legs 111, 121, 131, 141 have the role of current transformation.

[0062] Figure 5 schematically represents another embodiment of the windings in the converter of the invention. In this embodiment, the transformer 100 further comprises in each of the cells C1, C2, C3, C4 a A shielding layer 60 is wound on either side of the primary winding 50, between the primary winding 50 and the tertiary winding 30. Inserting a shielding layer 60 into the winding stack reduces common-mode noise, resulting in improved electromagnetic noise performance.

[0063] Figure 6 schematically represents another embodiment of the windings in the converter of the invention. In this embodiment, the transformer comprises two tertiary windings 31, 32. In a cell, the second tertiary winding 32 of one cell is connected in parallel with the second tertiary winding 32 of the adjacent cell. The first tertiary winding 31 is wound on one side of the main layup 50, and the second tertiary winding 32 is wound on the other side of the main layup 50. Put another way, the first tertiary winding 31 can be wound at the base of the stack around the first legs, and the second stack can be wound around the first legs, overlapping the main winding 50.

[0064] The arrangement of the main interlacing 50 between the first tertiary winding 31 and the second tertiary winding 32 ensures the balancing of the current of the tertiary windings.

[0065] Figure 7 schematically represents another embodiment of the windings in the converter of the invention. This winding embodiment is identical to that shown in Figure 6, except for the winding around the second legs. In the embodiment shown in Figure 7, the primary winding 10 is wound around the second leg 122 (instead of the secondary winding 20 in the previous embodiment). Thus, the primary, secondary, and tertiary windings are wound around the first legs, and the primary winding is wound around the second leg. In this embodiment, it is understood that the primary winding 10 is wound around both legs of each cell. The inductor is located on the primary side. This results in a change in the operating mode of the converter. The choice of variant is made according to the load mode envisaged for the converter.

[0066] The positioning of the inductor on the primary or secondary side is determined according to the specification that the converter must meet, i.e., according to the voltage range to be addressed for charging the high-voltage battery. For example, if the voltage range is wide, the inductor is placed on the secondary side.

[0067] Figure 8 schematically represents a view of the complete magnetic core 110 of the converter of the invention. The magnetic core 110 comprises a lower wall 150 from which the legs 111, 121, 131, 141, 112, 122, 132, 142 rise. over a leg height hj. The lower wall 150 extends in the XY plane and provides support for the first and second legs.

[0068] The magnetic core 110 comprises two side walls 151, 152 extending from the lower wall 150 to a wall height hp greater than or equal to the leg height hj. The magnetic core 110 also comprises an upper wall 153 in contact with the two side walls 151, 152. There is no gap between the upper wall 153 and the two side walls 151, 152. The upper wall 153 rests completely on the two side walls 151, 152.

[0069] In one embodiment, the first and second legs may have a height hj equal to the height hp of the side walls 151, 152. In this case, the upper wall 153 also rests on the first and second legs, without gaps between the upper wall and the upper surface of the legs.

[0070] In another embodiment, the wall height hp of the side walls 151, 152 is greater than the leg height hj of the legs. This means that the upper wall 153 is in contact with both side walls 151, 152, but not with the upper surface of the legs. Therefore, there is an air gap between the legs and the upper wall 153 of the magnetic core. Epoxy resin can be sandwiched in this gap between the leg and the upper wall 153. This is the air gap. Alternatively, a successive stacking of epoxy resin and ferrite is possible. The difference between the wall height hp and the leg height hj allows the desired inductance value to be adjusted. This adjustment reduces copper losses in the windings around the legs.

[0071] As explained previously, each winding comprises one or more turns. Each winding is wound around a leg 111, 121, 131, 141, 112, 122, 132, 142 in a plurality of layers. The windings can be made of magnetic wires or busbars.

[0072] According to an optional feature of the invention, the windings are obtained by means of an electronic board, or PCB (short for Printed Circuit Board). In this case, the transformer comprises an electronic board 70 having openings 211, 221, 231, 241, 212, 222, 232, 242 and superimposed traces wound around the openings. The stacking of the traces on the electronic board and the connection between the different layers is achieved by vias. Thus, the traces form the windings. For example, if we consider cell C1, the primary, secondary, and tertiary windings are wound in the electronic board around the opening 211 (illustrated in [Fig. 4]), and the secondary winding is wound in the electronic board around the opening 212.

[0073] Each leg of the magnetic core passes through an opening in the electronic board. As illustrated in [Fig. 4], leg 111 passes through opening 211 and leg 112 passes through opening 212. When the electronic board 70 is positioned within the magnetic core, that is, when its openings pass through the legs, the windings around opening 211 are thus positioned around the first leg 111 and the secondary winding around opening 212 is positioned around the second leg 112. The same principle applies to the legs of the adjacent cells, with the windings around the openings provided for this purpose in the electronic board. It is therefore understood that each leg of the magnetic core corresponds to an opening in the electronic board.

[0074] Using such an electronic board containing all the transformer windings offers numerous advantages. Thanks to well-established PCB manufacturing processes, it is easy to produce such an electronic board and it is possible to implement different winding configurations as discussed in this document.

[0075] The transformer is thus obtained with only three components: the electronic board 70, which contains all the windings arranged in a specific configuration unique to the invention; the base of the magnetic core (formed by the lower wall 150, the side walls 151, 152, and the legs); and the upper wall of the core. With its small footprint, such a transformer can be adapted to the power requirements of the load converter 300 in which it is installed. Numerous parameters are adjustable, such as the number of cells, the winding configuration, the spacing between the legs, and the spacing between the upper surface of the legs and the upper wall of the magnetic core.

[0076] Figure 9 schematically represents a motor vehicle comprising a The 300 charge converter of the invention. The motor vehicle 400 includes an on-board network intended to be powered by a low voltage DC BT current and to be connected to an AC alternating current network.

[0077] The invention effectively solves the problem it set out to address, namely, providing a load converter combining the two functions of an OBC and a DC-DC converter. Thanks to a specific arrangement of the windings within the transformer, the load converter of the invention exhibits high modularity according to output power requirements, for example, 2, 4, or 6 kW. It has a small footprint and is simple to assemble.

[0078] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, the characteristics of different embodiments variations of the invention can be combined to realize the invention, provided that these variations are not incompatible with each other.

Claims

Demands

1. A load converter (300) for converting alternating current (AC) into low-voltage direct current (LV DC) and high-voltage direct current (HV DC), comprising an AC-DC converter (310) and a transformer (100) for converting direct current (DC) into low-voltage direct current (LV DC) and high-voltage direct current (HV DC), characterized in that the transformer (100) comprises: - a plurality of adjacent cells (C1, C2, C3, C4), - a magnetic core (110) comprising a first leg (111, 121, 131, 141) and a second leg (112, 122, 132, 142) per cell, and in each cell (C1, C2, C3, C4): a primary winding (10), a secondary winding (20) and a tertiary winding (30) wound around the first leg (111, 121, 131, 141) and one among the primary winding and the secondary winding wound around the second leg (112, 122,132, 142) and an inductor (40) connected in series; and in that the primary winding (10), respectively the secondary winding (20), of one cell is connected in series with the primary winding (10), respectively the secondary winding (20), of an adjacent cell, and the tertiary winding (30) of one cell is connected in parallel with the tertiary winding (30) of the adjacent cell.

2. Converter according to claim 1, wherein the first legs and the second legs are parallel to each other.

3. Converter (300) according to claim 1 or 2, wherein the primary winding (10), the secondary winding (20) and the tertiary winding (30) are wound in a first direction (SI) in one cell and in a second direction (S2), opposite to the first direction (SI), in the adjacent cell.

4. Converter (300) according to any one of claims 1 to 3, wherein the primary winding (10) and the secondary winding (20) are interlaced around the first leg (111, 121, 131, 141) of each cell (C1, C2, C3, C4) so ​​as to form a main interleave (50), and the tertiary winding (30) is wound on either side of the main interleave (50).

5. Converter (300) according to claim 4, wherein the transformer further comprises in each cell (Cl, C2, C3, C4) a shielding layer (60) wound on either side of the main interlacing (50), between the main interlacing (50) and the tertiary winding (30).

6. Converter (300) according to claim 4 or 5, the tertiary winding (30) being the first tertiary winding (31), the transformer further comprising a second tertiary winding (32), the second tertiary winding (32) of a cell (C1, C2, C3, C4) being connected in parallel with the second tertiary winding (32) of the adjacent cell, and the first tertiary winding (31) is wound on one part of the main lay (50) and the second tertiary winding (32) is wound on the other part of the main lay (50).

7. Converter (300) according to any one of claims 1 to 6, each of the windings being wound around a leg (111, 121, 131, 141, 112, 122, 132, 142) in a plurality of layers, the transformer comprising an electronic board (70) having openings (211, 221, 231, 241, 212, 222, 232, 242) and superimposed tracks wound around the openings, the tracks forming the windings and each leg passing through an opening of the electronic board.

8. Converter (300) according to any one of claims 1 to 7, wherein the magnetic core (110) comprises: - a lower wall (150) from which the legs (111, 121, 131, 141, 112, 122, 132, 142) rise to a leg height, - two side walls (151, 152) rising from the lower wall (150) to a wall height (hp) greater than or equal to the leg height (hj), - an upper wall (153) in contact with the two side walls (151, 152).

9. Converter (300) according to claim 8, wherein the wall height (hp) of the two side walls (151, 152) is greater than the leg height (hj) of the legs.

10. Motor vehicle (400) comprising an on-board network configured to be powered by low voltage direct current (LV DC), the vehicle being configured to be connected to an alternating current (AC) network, the motor vehicle comprising a load converter (300) according to any one of claims 1 to 9.

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