Single-phase transformer for vehicle electric energy storage unit charger

Abstract

Single-phase transformer (15) for resonant voltage converter (8), comprising: - a magnetic circuit (16), - a primary winding (17) comprising an inner part (17a), and - a secondary winding (18), comprising an inner part (18a), the magnetic circuit (16) comprising a central leg (20) comprising successively along its longitudinal axis (X): - a first portion (21) around which is wound the inner part (17a) of the primary winding (17), and - a second portion (22) around which is wound the inner part (18a) of the secondary winding (18), the primary winding (17) comprising an outer part (17b) wound around the inner part (18a) of the secondary winding (18) and the secondary winding (18) comprising an outer part (18b) wound around the inner part (17a) of the primary winding (17). Abbreviated figure: Fig. 3

Description

Title of the invention: Single-phase transformer for charging a vehicle's electrical energy storage unit

[0001] The present invention relates to a single-phase transformer for a component providing power to a vehicle electrical energy storage unit, this component also being referred to as the "charger" of this electrical energy storage unit. The electrical energy storage unit is, for example, a battery, which may have a nominal voltage greater than 60V, for example, greater than or equal to 300V, 400V, 800V, or even 1000V. This charger comprises, in a known example:

[0002] - an inverter / rectifier receiving an alternating voltage as input from a network electrical and providing a direct current output voltage, and

[0003] - a DC / DC converter disposed downstream of the inverter / rectifier and connected to the electrical energy storage unit and incorporating an isolation transformer which can be single-phase or polyphase.

[0004] There is a need to further improve such chargers. The invention aims to meet this need and achieves this, in one aspect, by means of a single-phase transformer for voltage conversion, comprising:

[0005] - a magnetic circuit,

[0006] - a primary winding comprising an inner part, and

[0007] - a secondary winding, comprising an inner part,

[0008] the magnetic circuit comprising a central leg comprising successively along its longitudinal axis:

[0009] - a first portion around which the inner part of is wound the primary winding, and

[0010] - a second portion around which the inner part of is wound the secondary winding,

[0011] the primary winding comprising an outer part wound around the inner part of the secondary winding and the secondary winding comprising an outer part wound around the inner part of the primary winding.

[0012] The transformer described above features partial interlacing between the primary and secondary windings, which reduces the proximity effect by making the magnetic field around the windings more homogeneous. This reduces AC losses in the transformer. Controlling the distribution of leakage inductance between the primary and secondary windings, along with reducing the proximity effect, allows for benefit from a high-efficiency transformer while having a reduced size, which is favorable in terms of cost and space.

[0013] In the transformer above, it is possible not to provide a physical component mounted in series with the primary winding of the transformer to achieve a resonant inductance.

[0014] A first air gap can be provided in the first portion of the central leg and a second air gap can be provided in the second portion of the central leg.

[0015] For example, only one first air gap and one second air gap are provided. Other numbers of first and second air gaps are possible. Whatever the number, there can be an equal number of first air gap(s) and second air gap(s).

[0016] The first and second portions of the central leg can be separated by a third portion of the central leg, and a gap can be provided in this third portion. In other words, one can find, when moving successively along the longitudinal axis of the central leg:

[0017] - the first air gap provided in the first portion of the central leg around which is wound around the inner part of the primary winding,

[0018] - the air gap provided in the third portion of the central leg around which No winding is present; this air gap can still be called the "third air gap," and

[0019] - the second air gap provided in the second portion of the central leg around from which the inner part of the secondary winding is wound.

[0020] The presence of the third air gap can make it possible to increase the overall size of the air gap provided in the central leg, by benefiting from more distributed air gaps.

[0021] Each air gap can extend the same distance along the longitudinal axis of the central leg. Alternatively, only the first and second air gaps extend the same distance along the longitudinal axis of the central leg, with the third air gap extending a larger distance along this axis. This size of the third air gap allows for the introduction of a resin suitable for potting to harden and immobilize the elements with which it comes into contact, without the presence of the third air gap causing any fringe effect.

[0022] The distance along the longitudinal axis of the central leg separating two consecutive air gaps can be constant over all the air gaps provided in the second portion of the central leg. The manufacture of the central leg components can be simplified.

[0023] The central leg may be devoid of air gap elsewhere than in the first, second and third portions mentioned above.

[0024] The median plane of the third air gap can be a plane of symmetry for the central leg.

[0025] Each first and second air gap can be made in FR4 and the third air gap can be occupied by air.

[0026] In all the above, the central leg may have a circular or oval cross-section.

[0027] In all the foregoing, the magnetic circuit of the transformer may comprise:

[0028] - two external legs between which the central leg is physically disposed, And

[0029] - two cylinder heads, each cylinder head being disposed at a longitudinal end and allowing the magnetic flux circulating in the central leg to loop back into the outer legs.

[0030] The flow circulating in the central leg and looping back into the external legs does not advantageously pass through any other gaps than those mentioned above provided in the central leg.

[0031] Each breechblock can be made from a single piece with a part of the central leg and each outer leg. This piece can then have an "E" shape.

[0032] The magnetic circuit can form a shell for the transformer, the electrical winding being contained within the magnetic circuit.

[0033] Within this application:

[0034] - "axial" or "axially" means "moving along the longitudinal axis" of the central leg,” and

[0035] - "radial" or "radially" means "in a plane perpendicular to the axis longitudinal of the central leg, along a radius by analogy with the case where the cross-section of the central leg is circular.

[0036] Within the primary winding, the inner and outer parts can be connected in series. Similarly, within the secondary winding, the inner and outer parts can be connected in series. The number of turns can differ between the inner and outer parts of the primary winding. Similarly, the number of turns can differ between the inner and outer parts of the secondary winding.

[0037] The outer part of the primary winding can extend around the inner part of the secondary winding by less than the axial dimension over which this inner part of the secondary winding extends, and the outer part of the secondary winding can extend around the inner part of the primary winding by less than the axial dimension over which this inner part extends. of the primary winding. In other words, there is no total axial overlap of the inner part of the primary, or secondary, winding by the outer part of the secondary, or primary, winding.

[0038] In all the foregoing, the primary winding may include an additional outer portion extending around the inner portion of this primary winding, axially in line with the outer portion of the secondary winding, and the secondary winding may include an additional outer portion extending around the inner portion of this secondary winding, axially in line with the outer portion of the primary winding.

[0039] The number of turns may differ within the primary winding between the additional outer part and: the inner part and / or the outer part. Similarly, the number of turns may differ within the secondary winding between the additional outer part and: the inner part and / or the outer part.

[0040] The various parts of the primary winding can be connected in series. For example, the inner part of the primary winding is connected in series with the additional outer part of that primary winding via the outer part of the primary winding. Similarly, the various parts of the secondary winding can be connected in series. For example, the inner part of the secondary winding is connected in series with the additional outer part of that secondary winding via the outer part of the secondary winding.

[0041] The transformer winding formed by the combination of the primary and secondary windings can thus be formed by several radially stacked layers. Along the central leg, the inner radial layer of the winding can be formed successively by turns of the primary winding and turns of the secondary winding, according to a single primary / secondary alternation. The outer radial layer of the winding can be formed successively by turns of the primary winding and turns of the secondary winding according to three primary / secondary alternations.Such an arrangement of the primary and secondary windings on the central leg can further improve the distribution of leakage inductance between the primary and secondary windings and further improve the electrical performance of the transformer by allowing the intrinsic realization of the resonant inductance, while being simple to manufacture, and therefore of reduced cost.

[0042] For example, the following succession is found on the radially outer layer: secondary / primary / secondary / primary.

[0043] The electrical winding of the transformer comprises, for example, three layers along the central leg, and:

[0044] - two of these layers are radially inner layers such as above, And

[0045] - the third layer is the radially outer layer as above.

[0046] The various outer parts of the primary and secondary windings can be arranged so that, when moving along the longitudinal axis of the central leg in the outermost layer of the transformer's electrical winding formed by the union of the primary and secondary windings, one finds successively from one longitudinal end to the other:

[0047] - at least one turn belonging to the additional outer part of the winding primary, wound around the inner part of the primary winding,

[0048] - at least one turn belonging to the outer part of the secondary winding, wrapped around the inner part of the primary winding;

[0049] - at least one turn belonging to the outer part of the primary winding surrounded around the inner part of the secondary winding, and

[0050] - at least one turn belonging to the additional outer part of the winding secondary, wound around the inner part of the secondary winding.

[0051] According to this configuration, on either side of the third part of the central leg around which no winding is arranged, there are opposite interlaced areas, with on one side: turn(s) of the inner part of the primary winding with turn(s) of the outer part of the secondary winding around, and on the other side: turn(s) of the inner part of the secondary winding with turn(s) of the outer part of the primary winding around.

[0052] Alternatively, the various outer parts of the primary and secondary windings can be arranged so that, when moving along the longitudinal axis of the central leg in the outermost layer of the transformer's electrical winding formed by the union of the primary and secondary windings, one finds successively from one longitudinal end to the other:

[0053] - at least one turn belonging to the outer part of the primary winding, wound around the inner part of the secondary winding,

[0054] - at least one turn belonging to the additional outer part of the winding secondary, wound around the inner part of the secondary winding,

[0055] - at least one turn belonging to the additional outer part of the winding primary, wound around the inner part of the primary winding, and

[0056] - at least one turn belonging to the outer part of the secondary winding, wrapped around the inner part of the primary winding.

[0057] According to this configuration, on either side of the third part of the central leg around which no winding is arranged, we find opposite areas with on one side: turn(s) of the inner part of the primary winding with turn(s) of the additional outer part of the primary winding around, and on the other side: turn(s) of the inner part of the secondary winding with turn(s) of the additional outer part of the secondary winding around.

[0058] Depending on either of the above configurations, we thus find, by moving in planes perpendicular to the longitudinal axis:

[0059] - planes in which a turn of the inner part of the primary winding is surrounded by a turn of the outer part of the secondary winding,

[0060] - planes in which a turn of the inner part of the primary winding is surrounded by a turn of the additional outer part of the primary winding,

[0061] - planes in which a turn of the inner part of the secondary winding is surrounded by a turn of the outer part of the primary winding,

[0062] - planes in which a turn of the inner part of the secondary winding is surrounded by a turn of the additional outer part of the secondary winding.

[0063] According to either of the above configurations, the inner part of the primary winding may comprise several radially superimposed layers, and the primary winding may be formed by an electrical conductor defining a succession of turns arranged such that:

[0064] - for each layer of the inner part, the turns follow one another along the axis longitudinal of the central leg within said layer then, at the axial end of this layer, the turns are offset radially, succeeding each other axially in the next layer of the inner part of the primary winding radially speaking to the other axial end of this next layer, then,

[0065] - the electrical conductor extends to a longitudinal end of the part outer part of the primary winding and then define turns succeeding one another until the other longitudinal end of this outer part of the primary winding, then

[0066] - the electrical conductor extends to one longitudinal end of the additional outer part of the primary winding and then define turns succeeding one another until the other longitudinal end of this additional outer part of the primary winding.

[0067] According to either of the above configurations, the inner part of the secondary winding may comprise several radially superimposed layers, and the secondary winding may be formed by an electrical conductor defining a succession of turns arranged such that:

[0068] - for each layer of the inner part, the turns follow one another along the axis longitudinal of the central leg within said layer then, at the axial end of this layer, the turns are radially offset, succeeding each other axially in the next layer of the inner part of the secondary winding radially speaking to the other axial end of this next layer, then,

[0069] - the electrical conductor extends to a longitudinal end of the part outer part of the secondary winding and then define turns succeeding one another until the other longitudinal end of this outer part of the secondary winding, then

[0070] - the electrical conductor extends to one longitudinal end of the additional outer part of the secondary winding and then define turns succeeding one another until the other longitudinal end of this additional outer part of the secondary winding.

[0071] In all the above, each of the primary and secondary windings can be made using a Litz wire.

[0072] According to a first example of implementation, the ratio between the number of turns of the secondary winding and the number of turns of the primary winding can be between 1 and 1.1. Such a transformer ratio value is particularly relevant when the electrical energy storage unit has a nominal voltage of 800V and when the DC / DC voltage converter is of the CLLC type.

[0073] According to a second embodiment, the ratio between the number of turns in the secondary winding and the number of turns in the primary winding can be between 0.5 and 0.6. Such a transformer ratio is particularly relevant when the electrical energy storage unit has a nominal voltage of 400V, so as to adapt the output voltage of an upstream inverter / rectifier to this nominal voltage of 400V, and when the DC / DC voltage converter is of the CLLC type. The secondary winding can be made using a Litz wire comprising between 1100 and 1400 strands, for example, 1400 strands. Each strand has, for example, a diameter between 50 µm and 100 µm, for example, 50 µm, 60 µm, or 71 µm.

[0074] According to this second embodiment, the secondary winding can comprise two wires arranged in parallel, such that each turn of the secondary winding comprises these two wires. Thus, each of the aforementioned parts of the secondary winding, namely the inner part, the outer part, and, where applicable, the additional outer part, is formed by these two parallel wires which together define the turns of the part in question. Each Litz wire is, for example, a Litz wire comprising between 1100 and 1400 strands, for example, 1400 strands. Each strand has, for example, a diameter between 50 µm and 100 µm, per For example, 50pm or 60pm or 71pm. Using two Litz wires in parallel to create the secondary winding allows the effective cross-sectional area of ​​the electrical conductor in the secondary to be doubled, enabling the transfer of the required power level without significant losses.

[0075] In all the foregoing, the primary and secondary windings can be mounted on a coil support, itself mounted on the central leg. As is known, the aforementioned polymerizable resin (known as "potting"), used to harden and immobilize the elements with which it comes into contact, can be introduced between the central leg, the coil support, and the windings. The shape of the coil support can be chosen to promote the distribution of the resin, and thus improve the cooling of the transformer.

[0076] The central leg is for example made of MnZn ferrite.

[0077] The transformer can allow the transfer of power on the order of 1 IkW.

[0078] The invention also relates, according to another aspect, to a DC / DC voltage converter, comprising a transformer as defined above. This DC / DC voltage converter is, for example, a resonant converter.

[0079] This DC / DC voltage converter is for example of type 800V / 800V or 800V / 400V.

[0080] The invention also relates, according to another aspect, to a vehicle electrical energy storage unit charger, comprising:

[0081] - an inverter / rectifier suitable for electrical connection to a voltage network alternative, and

[0082] - the DC / DC voltage converter as defined above, this converter of A DC / DC voltage suitable for electrical interposition between the inverter / rectifier and the electrical energy storage unit. The primary winding can then be electrically connected to the inverter / rectifier and the secondary winding to the electrical energy storage unit.

[0083] The inverter / rectifier can be controlled to have on its DC output a The input voltage is 800V, and the DC / DC converter is then configured to adapt this voltage value according to the nominal voltage of the electrical energy storage unit, which may be, for example, 400V or 800V, as previously mentioned. Thus, depending on whether the electrical energy storage unit has a nominal voltage of 400V or 800V, the transformer ratio is selected to adapt the 800V output of the inverter / rectifier to this value of 400V or 800V.

[0084] The inverter / rectifier can perform a factor correction function of power (or "power factor correction"). This correction, as is known, ensures that the current drawn from the grid is as close as possible to a perfect sine wave. to the network's pulse rate. This reduces reactive current and subharmonics, which increase energy losses during conduction.

[0085] The charger is, for example, reversible, allowing alternative operation:

[0086] - the charging of the electrical energy storage unit from the electrical grid, and

[0087] - the power supply to a load or the electrical network from the unit of electrical energy storage.

[0088] In all the above, the electrical network voltage may be polyphase, in particular three-phase. This voltage may have a frequency of 50 Hz or 60 Hz and an RMS value of 230 V or 240 V. Alternatively, the network voltage may be single-phase.

[0089] Where appropriate, the charger may include a device for detecting an insulation fault between at least one of the following:

[0090] - of one phase of the alternating voltage and earth, and

[0091] - from the neutral of the alternating voltage and earth,

[0092] such a detection device is for example made according to the teaching of the international application filed by the Applicant on 22 / 02 / 24 under number PCT / EP2024 / 054589 or according to the teaching of the European application filed by the Applicant on 22 / 02 / 24 under number 24159251.8.

[0093] Alternatively, the network can supply a direct current voltage. In this case, the charger does not have an inverter / rectifier upstream of the DC / DC voltage converter.

[0094] The charger may or may not be contained in a housing that also houses another DC / DC voltage converter for converting the voltage of the electrical energy storage unit into the voltage of the onboard network, this other DC / DC voltage converter providing, for example, a conversion:

[0095] - 800V / 12V

[0096] - 800V / 48V

[0097] - 400V / 12V, or

[0098] - 400V / 48V

[0099] The invention will be better understood upon reading the following description of non-limiting examples of its implementation:

[0100] - [Fig. 1] represents a charger providing power to a unit of vehicle electrical energy storage,

[0101] - [Fig.2] represents a schematic view of a transformer according to a first example of implementation of the invention forming part of the charger of [Fig.1],

[0102] - [Fig.3] is an axial cross-sectional view of the transformer of [Fig.2],

[0103] - [Fig.4] is a view similar to that of [Fig.3] of a transformer variant, representing more specifically the position of the coils,

[0104] - [Fig.5] is a view similar to [Fig.3] of a transformer according to a second example of an implementation of the invention,

[0105] - [Fig.6] is a view similar to that of [Fig.5] of a transformer variant, representing more specifically the position of the coils, and

[0106] - [Fig.7] is an electrical circuit modeling the transformer of figures 2 to 6.

[0107] Figure 1 shows a charger 2 for a vehicle electrical energy storage unit 4. This charger 2 comprises:

[0108] - a connector 5 suitable for being connected to an electrical network supplying a voltage alternative in the example considered,

[0109] - an inverter / rectifier 6, and

[0110] - a DC / DC voltage converter 8.

[0111] As can be seen in [Fig.1], the inverter / rectifier 6 is here arranged in cascade between the connector 5 and the DC / DC voltage converter 8.

[0112] The electrical energy storage unit 4 is here a battery used for powering an electric vehicle propulsion machine. This battery has, for example, a nominal voltage greater than 60V, in particular 300V, in particular 400V, in particular 800V, or even 1000V.

[0113] The electrical network is for example a three-phase network carrying a voltage at a first frequency which is 50Hz or 60Hz and whose effective value is 230V or 240V.

[0114] As shown in [Fig.1], an alternating current filtering stage 10 may be provided, this filtering stage 10 being here arranged in series between the connector 5 and the inverter / rectifier 6. This filtering stage 10 allows, for example, when the alternating voltage is polyphase, common mode current filtering and / or differential current filtering.

[0115] Optionally, another DC current filtering stage 11 may be present, then arranged in series between the DC / DC voltage converter 8 and the electrical energy storage unit 4, as shown in [Fig.1].

[0116] The DC / DC voltage converter 8 is for example a resonant converter, for example of type CLLC or CLLLC or LLC.

[0117] The DC / DC voltage converter 8 includes a single-phase transformer 15 allowing the establishment of galvanic isolation within the charger 2 and the adaptation of the voltage gain of the converter.

[0118] As can be seen in Figures 2 to 6, the transformer 15 comprises:

[0119] - a magnetic circuit 16,

[0120] - a primary winding 17, and

[0121] - a secondary winding 18.

[0122] More specifically, the primary winding 17 here comprises an inner part 17a and an outer part 17b, and the secondary winding 18 comprises an inner part 18a and an outer part 18b. The parts 17a and 17b of the primary winding 17 are here connected in series, and the parts 18a and 18b of the secondary winding 18 are also connected in series.

[0123] The magnetic circuit includes a central leg 20 comprising successively along its longitudinal axis (X):

[0124] - a first portion 21 around which the inner part 17a of is wound the primary winding 17,

[0125] - a third portion 23 around which no winding is arranged, and

[0126] - a second portion 22 around which the inner part 17b of is wound the secondary winding 18.

[0127] Figures 3 to 6 show that the outer part 17b of the inner winding 17 is wound around a fraction of the inner part 18a of the secondary winding 18. Similarly, figures 3 to 6 show that the outer part 18b of the outer winding 18 is wound around a fraction of the inner part 17a of the primary winding 17.

[0128] It can also be seen in figures 3 and 5 that several air gaps 24 are provided in the central leg 20.

[0129] In the example of Figures 3 and 5, these air gaps 24 are respectively:

[0130] - a first air gap 24a provided in the first portion 21 of the central leg 20,

[0131] - a third air gap 24c provided in the third portion 23 of the central leg 20, and

[0132] - a second air gap 24b provided in the second portion 22 of the central leg 20.

[0133] It can also be seen in Figures 3 and 5 that not all the air gaps 24a, 24b and 24c necessarily extend over the same dimension along the longitudinal axis (X) of the central leg 20. It can also be seen in Figures 3 and 5 that the distance along this longitudinal axis (X) which separates two consecutive air gaps can remain constant over all the air gaps 24 provided in the central leg 20. Still in the example considered, the central leg 20 is devoid of air gaps except in the first, second and third portions.

[0134] In all the above, the central leg 20 has, for example, an oval cross-section.

[0135] As can be seen in [Fig.2], the magnetic circuit 16 of the transformer 15 also includes in the example considered:

[0136] - two external legs 26 between which the leg is physically disposed central 20, and

[0137] - two cylinder heads 27, each cylinder head 27 being disposed at a longitudinal end along the (X) axis and allowing the magnetic flux circulating in the central leg 20 to loop back into the external legs 26.

[0138] As can be seen in [Fig.2], each cylinder head 27 may have cutouts at the junction with the central leg in order to reduce the cross-section of the magnetic circuit at this junction.

[0139] In the example of [Fig. 2], each yoke 27 is made in one piece from a portion of the central leg 20 and each outer leg 26, so that the magnetic circuit 16 comprises two "E"-shaped pieces. [Fig. 2] shows that the magnetic circuit 16 encapsulates the primary winding 17 and the secondary winding 18, forming a kind of shell for the transformer 15. This shell has, for example, the following dimensions:

[0140] - length along the longitudinal axis (X): 61 mm,

[0141] - width in a plane perpendicular to the axis (X): 64 mm,

[0142] - height in a plane perpendicular to the axis (X): 31.6 mm.

[0143] All these dimensions of the magnetic circuit 16 can therefore be less than 10 cm.

[0144] The magnetic circuit 16 is, for example, made of ferrite

[0145] Although not visible in [Fig.2], the transformer 15 may include a coil support, for example made of plastic, which is interposed between the various windings 17, 18 and the central leg 20. This coil support includes several edges following one another along the longitudinal axis (X) and separating two-by-two parts of the primary winding 17 and the secondary winding 18.

[0146] A resin suitable for being potted to harden and immobilize the elements with which it comes into contact can occupy all or part of the existing space inside the magnetic circuit 16 to interpose itself between the central leg 20, the coil support and the primary windings 17 and 18.

[0147] As can be seen in Figures 3 and 5, in the examples considered, the primary winding 17 further includes an additional outer part 17c which extends around the inner part 17a of this primary winding 17, axially in the continuation of the outer part 18b of the secondary winding 18.

[0148] Around the first portion 21 of the central leg 20, the winding is thus made up of several layers with:

[0149] - one or more internal layers formed by the inner part 17a of the primary winding 17, and

[0150] - one or more outer layers, an axial fraction of which is formed by the part additional outer part 17c of the primary winding 17 and the other axial fraction is formed by the outer part 18b of the secondary winding 18.

[0151] Similarly, it can be seen in Figures 3 and 5 that, in the examples considered, the secondary winding 18 still includes an additional outer part 18c which extends around the inner part 18a of this secondary winding 18, axially in the continuation of the outer part 17b of the primary winding 17.

[0152] Around the second portion 22 of the central leg 20, the winding is thus made up of several layers with:

[0153] - two internal layers formed by the inner part 18a of the winding Secondary 18, and

[0154] - an outer layer of which an axial fraction is formed by the outer part additional 18c of the secondary winding 18 and the other axial fraction is formed by the outer part 17b of the primary winding 17.

[0155] As will be seen later with reference to Figures 4 and 6, the various parts 17a, 17b, and 17c of the primary winding 17 can be connected in series. The inner part 17a, for example, is connected in series with the additional outer part 17c via the outer part 17b. Similarly, the various parts 18a, 18b, and 18c of the secondary winding 18 can be connected in series.

[0156] As can be seen in Figures 3 to 6, in the transformers 15 considered, the winding formed by the combination of the primary winding 17 and the secondary winding 18 consists of several radially stacked layers. Along the central leg 20, two radially inner layers of this winding are formed successively by turns of the primary winding 17 and by turns of the secondary winding 18, according to a single primary / secondary alternation. In contrast, the radially outer layer of this winding is formed successively by turns of the primary winding and by turns of the secondary winding according to three primary / secondary alternations. For example, the following sequence is found on the radially outer layer in the case of Figures 3 to 6: secondary / primary / secondary / primary.

[0157] As shown in Figures 3 and 5, when moving along the longitudinal axis (X) of the central leg 20 in the outer layer of the transformer's electrical winding formed by the union of the primary and secondary windings, one finds successively from one longitudinal end to the other:

[0158] - at least one turn belonging to the outer part 17b of the primary winding 17, wound around the inner part 18a of the secondary winding 18,

[0159] - at least one turn belonging to the additional outer part 18c of the secondary winding 18, wound around the inner part 18a of the secondary winding 18,

[0160] - at least one turn belonging to the additional outer part 17c of the primary winding 17, wound around the inner part 17a of the primary winding 17, and

[0161] - at least one turn belonging to the outer part 18b of the winding secondary, wound around the inner part 17a of the primary winding 17.

[0162] As can be seen in Figures 3 and 5, on either side of the third part 23 of the central leg 20, there are opposite areas with:

[0163] - on one side: turn(s) of the inner part 17a of the primary winding 17 with turn(s) of the additional outer part 17c of the primary winding 17 around, and

[0164] - on the other side: turn(s) of the inner part 18a of the secondary winding 18 with turn(s) of the additional outer part 18c of the secondary winding 18 around.

[0165] In the other embodiment shown in Figures 4 and 6, when moving along the longitudinal axis (X) of the central leg 20 in the outer layer of the transformer's electrical winding formed by the union of the primary and secondary windings, one finds successively from one longitudinal end to the other:

[0166] - at least one turn belonging to the additional outer part 17c of the primary winding 17, wound around the inner part 17a of the primary winding 17,

[0167] - at least one turn belonging to the outer part 18b of the winding secondary 18, wound around the inner part 17a of the primary winding 17;

[0168] - at least one turn belonging to the outer part 17b of the primary winding 17 surrounded around the inner part 18a of the secondary winding, and

[0169] - at least one turn belonging to the additional outer part 18c of the secondary winding 18, wound around the inner part 18a of the secondary winding 18.

[0170] As can be seen in Figures 4 and 6, on either side of the third part 23 of the central leg 20, there are opposite interlaced areas, with:

[0171] - on one side: turn(s) of the inner part 17a of the primary winding 17 with turn(s) of the outer part 18b of the secondary winding 18 around, and

[0172] - on the other side: turn(s) of the inner part 18a of the secondary winding 18 with turn(s) of the outer part 17b of the primary winding 17 around.

[0173] According to Figures 3 to 6, we thus find, by moving in planes perpendicular to the longitudinal axis (X):

[0174] - planes in which a turn of the inner part 17a of the winding primary winding 17 is surrounded by a turn of the outer part 18b of the secondary winding 18,

[0175] - planes in which a turn of the inner part 17a of the primary winding 17 is surrounded by a turn of the additional outer part 17c of the primary winding 17,

[0176] - planes in which a turn of the inner part 18a of the winding secondary winding 18 is surrounded by a turn of the outer part 17b of the primary winding 17,

[0177] - planes in which a turn of the inner part 18a of the secondary winding 18 is surrounded by a turn of the additional outer part 18c of the secondary winding.

[0178] As can be seen in Figures 4 to 6, the turns of the primary winding 17 can follow one another as follows, within this primary winding:

[0179] - for each layer of the inner part 17a, the turns follow one another along from the longitudinal axis (X) then, at the axial end of this layer, the turns are radially offset, succeeding each other axially in the next layer of the inner part 17a of the primary winding 17 radially speaking until the other axial end of this next layer, then,

[0180] - the electrical conductor forming the primary winding 17 extends to a longitudinal end of the outer part 17b of the primary winding 17 and then defines successive turns up to the other longitudinal end of this outer part 17b of the primary winding 17, then

[0181] - the electrical conductor forming the primary winding 17 extends to a longitudinal end of the additional outer part 17c of the primary winding 17 and then defines one or more turns succeeding each other until the other longitudinal end of this additional outer part 17c of the primary winding 17.

[0182] The secondary winding 18 can be made in the same way as just described with reference to the primary winding 17.

[0183] We will continue to describe, with the aid of Figures 3 and 4, a first example of implementation in which the DC / DC voltage converter 8 converts a voltage of 800V on the DC output of the inverter / rectifier 6 into a voltage of 800V which corresponds to the nominal voltage of the electrical energy storage unit 4.

[0184] According to this first example of implementation, the ratio between the number of turns of the secondary winding 18 and the number of turns of the primary winding 17 can be between 1 and 1.1. The secondary winding 18 has, for example, 26 turns, while the primary winding 17 has 25.

[0185] The distribution of the 26 turns of the secondary winding is, for example, as shown below:

[0186] - the inner part 18a of the secondary winding 18 is in the form of two radially stacked layers which together form 18 turns,

[0187] - the outer part 18b of the secondary winding 18 is in the form of a single layer that forms 6.5 turns, and

[0188] - the additional outer part 18c of the secondary winding 18 is in the form of a single layer that forms 1.5 turns.

[0189] The distribution of the 25 turns of the primary winding is, for example, as shown below:

[0190] - the inner part 17a of the primary winding 17 is in the form of two radially stacked layers which together form 17 turns,

[0191] - the outer part 17b of the primary winding 17 is in the form of a single layer that forms 6.5 turns, and

[0192] - the additional outer part 17c of the primary winding 17 is in the form of the shape of a single layer that forms 1.5 turns.

[0193] Each of the primary winding 17 and of the secondary winding 18 is for example made using a Litz wire.

[0194] The transformer 15 as dimensioned above for the 800V / 800V application corresponds, for example, to the electrical diagram according to [Fig.7] with:

[0195] - a magnetizing inductance Lm equal to 115pH,

[0196] - a primary leakage inductance Lp equal to 17pH,

[0197] - a secondary leakage inductance Ls equal to 17pH

[0198] We will continue to describe, with the aid of Figures 5 and 6, a second example of implementation in which the DC / DC voltage converter 8 converts a voltage of 800V on the DC output of the inverter / rectifier 6 into a voltage of 400V which corresponds to the nominal voltage of the electrical energy storage unit 4. The ratio between the number of turns of the secondary winding 18 and the number of turns of the primary winding 17 can be between 0.5 and 0.6.

[0199] The secondary winding 18 has, for example, 13 turns, while the primary winding 17 has 25.

[0200] The distribution of the 13 turns of the secondary winding is, for example, as shown below:

[0201] - the inner part 18a of the secondary winding 18 is in the form of two radially stacked layers which together form 9 turns,

[0202] - the outer part 18b of the secondary winding 18 is in the form of a single layer that forms 3.5 turns, and

[0203] - the additional outer part 18c of the secondary winding 18 is in the form of a single layer that forms 0.5 turns.

[0204] The distribution of the 25 turns of the primary winding is, for example, as shown below:

[0205] - the inner part 17a of the primary winding 17 is in the form of two radially stacked layers which together form 17 turns,

[0206] - the outer part 17b of the primary winding 17 is in the form of a single layer that forms 6.5 turns, and

[0207] - the additional outer part 17c of the primary winding 17 is in the form of the shape of a single layer that forms 1.5 turns.

[0208] Each of the primary winding 17 and the secondary winding 18 is, for example, made using Litz wire. According to this second embodiment, and as is clear from [Fig. 6], the secondary winding 18 can comprise two Litz wires arranged in parallel, such that each turn of the secondary winding 18 comprises these two wires. Thus, each of the aforementioned parts of the secondary winding, namely the inner part 18a, the outer part 18b, and the additional outer part 18c, is formed by these two parallel wires, which together define the turns of the part in question of the secondary winding 18. Each of these Litz wires is, for example, a Litz wire of 1400 strands, with each strand having a diameter of 50 µm.

[0209] The transformer 15 as dimensioned above for the 800V / 400V application corresponds, for example, to the electrical diagram according to [Fig. 7] with:

[0210] - a magnetizing inductance Lm equal to 115pH,

[0211] - a primary leakage inductance Lp equal to 17pH,

[0212] - a secondary leakage inductance Ls equal to 5pH.

[0213] The invention is not limited to the example just described.

[0214] In one variant, the alternating voltage of the network is single-phase.

[0215] In another variant, the voltage of the electrical network is direct.

Claims

Demands

1. A single-phase transformer (15) for a voltage converter (8), in particular a resonant voltage converter (8), comprising: - a magnetic circuit (16), - a primary winding (17) comprising an inner portion (17a), and - a secondary winding (18) comprising an inner portion (18a), the magnetic circuit (16) comprising a central leg (20) comprising successively along its longitudinal axis (X): - a first portion (21) around which the inner portion (17a) of the primary winding (17) is wound, and - a second portion (22) around which the inner portion (18a) of the secondary winding (18) is wound, the primary winding (17) comprising an outer portion (17b) wound around the inner portion (18a) of the secondary winding (18), and the secondary winding (18) comprising an outer portion (18b) wound around the inner portion (18a) of the secondary winding (18). (17a) of the primary winding (17).

2. Transformer according to claim 1, a first air gap (24a) being provided in the first portion (21) of the central leg (20) and a second air gap (24b) being provided in the second portion (22) of the central leg (20).

3. Transformer according to claim 1 or 2, the first portion (21) and the second portion (22) of the central leg (20) being separated by a third portion (23) of the central leg, and an air gap (24c) being provided in this third portion (23).

4. Transformer according to any one of the preceding claims, the outer part (17b) of the primary winding (17) extending around the inner part (18a) of the secondary winding (18) over less than the axial dimension over which this inner part (18a) of the secondary winding (18) extends, and the outer part (18b) of the secondary winding (18) extending around the inner part (17a) of the primary winding (17) over less than the axial dimension over which this inner part (17a) of the primary winding (17) extends.

5. Transformer according to the preceding claim, the primary winding (17) comprising an additional outer portion (17c) extending around the inner portion (17a) of this primary winding (17), axially in the continuation of the outer portion (18b) of the secondary winding (18), and the secondary winding (18) comprising an additional outer portion (18c) extending around the inner portion (18a) of this secondary winding (18), axially in the continuation of the outer portion (17b) of the primary winding (17).

6. Transformer according to claim 5, the various outer (17b, 18b) and additional outer (17c, 18c) parts of the primary and secondary windings being arranged such that, when moving along the longitudinal axis (X) of the central leg (20) in the outermost layer of the transformer winding formed by the union of the primary winding (17) and the secondary winding (18), one finds successively from one longitudinal end to the other: - at least one turn belonging to the additional outer part (17c) of the primary winding, - at least one turn belonging to the outer part (18b) of the secondary winding, - at least one turn belonging to the outer part (17b) of the primary winding, and - at least one turn belonging to the additional outer part (18c) of the secondary winding.

7. Transformer according to claim 5, the various outer (17b, 18b) and additional outer (17c, 18c) parts of the primary and secondary windings being arranged so that, when moving along the longitudinal axis (X) of the central leg (20) in the outermost layer of the electrical winding of the transformer formed by the union of the primary winding (17) and the secondary winding (18), one finds successively from one longitudinal end to the other: - at least one turn belonging to the outer part (17b) of the primary winding, - at least one turn belonging to the additional outer part (18c) of the secondary winding, - at least one turn belonging to the additional outer part (17c) of the primary winding, and - at least one turn belonging to the outer part (18b) of the secondary winding.

8. Transformer according to any one of claims 5 to 7, the inner part (17a) of the primary winding (17) comprising several radially superimposed layers, the primary winding (17) being formed by an electrical conductor defining a succession of turns arranged such that: - for each layer of the inner part (17a), the turns follow one another along the longitudinal axis (X) of the central leg (20) within said layer and then, at the axial end of this layer, the turns being radially offset, succeeding one another axially in the next layer of the inner part (17a) of the primary winding (17) radially speaking to the other axial end of this next layer, and then,- the electrical conductor extends to one longitudinal end of the outer part (17b) of the primary winding and then defines successive turns to the other longitudinal end of this outer part (17b) of the primary winding, then - the electrical conductor extends to one longitudinal end of the additional outer part (17c) of the primary winding and then defines successive turns to the other longitudinal end of this additional outer part (17c) of the primary winding.

9. Transformer according to any one of the preceding claims, the ratio between the number of turns of the secondary winding (18) and the number of turns of the primary winding (17) being between 1 and 1.

1.

10. Transformer according to any one of claims 1 to 7, the ratio between the number of turns of the secondary winding (18) and the number of turns of the primary winding (17) being between 0.5 and 0.

6.

11. Transformer according to the preceding claim, the secondary winding (18) comprising two wires arranged in parallel, such that each turn of the secondary winding (18) comprises these two wires.

12. DC / DC voltage converter (8), comprising a transformer (15) according to any one of the preceding claims, the converter being in particular resonant.

13. Charger (2) of a vehicle electrical energy storage unit (4), comprising: - an inverter / rectifier (6) suitable for being electrically connected to an alternating voltage network, and - the DC / DC voltage converter (8) resonating according to claim 12, this DC / DC voltage converter (8) being suitable for being electrically interposed between the inverter / rectifier (6) and the electrical energy storage unit (4).

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