Planar transformer with integrated inductor and converter comprising such a transformer
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- VALEO ELECTRIFICATION SAS
- Filing Date
- 2025-12-19
- Publication Date
- 2026-06-25
AI Technical Summary
Existing planar transformers with integrated inductance face challenges when used as voltage dividers, requiring a wide output winding that increases the transformer's size and complicates connections due to protruding inductor turns.
A transformer design with a multilayer printed circuit board and magnetic core that allows windings to extend through openings between auxiliary legs, enabling wider windings without increasing overall size and facilitating easy connections.
Enables wider windings with easy access for connections, maintaining transformer size and improving connectivity without increasing overall dimensions.
Smart Images
Figure EP2025088261_25062026_PF_FP_ABST
Abstract
Description
Description TITLE: PLANE TRANSFORMER WITH INTEGRATED INDUCTANCE AND CONVERTER CONTAINING SUCH A TRANSFORMER Technical field of the invention
[0001] The present invention relates to a planar transformer with integrated inductance and a converter comprising such a transformer.
[0002] The invention can in particular be used in a mobility device such as, for example, a motor vehicle, a train, an aircraft or a drone. A motorized land vehicle is, for example, a car, a motorcycle, a motorized bicycle, or a motorized wheelchair. Technological background
[0003] A planar transformer with integrated inductance is known from the prior art, comprising: a multilayer printed circuit board having several conductive layers; windings each having at least one turn formed in one of the conductive layers of the multilayer printed circuit board; at least one inductor having at least one turn formed in one of the conductive layers of the multilayer printed circuit board; a magnetic core comprising: • main legs passing through the multilayer printed circuit board, the windings of the coils being wound around one of the main legs so that the coils are magnetically coupled to each other, the inductor loop being wound around a second of the main legs and possibly the first main leg, and • Auxiliary magnetic flux return legs located around the multilayer printed circuit board, so that the multilayer printed circuit board has an inner portion to the auxiliary legs.
[0004] In this well-known transformer, two auxiliary legs are provided, running laterally alongside the windings. Thus, there are two end openings between these two auxiliary legs. Furthermore, two inductors are provided.
[0005] To allow the turns of these two inductors to protrude, the multilayer printed circuit board extends from the inner part through the two end openings to present two outer parts to the auxiliary legs. Thus, the turn(s) of the first inductor extend into the first outer part to protrude through the first end opening, while the turn(s) of the second inductor extend into the second outer part to protrude through the second end opening.
[0006] Such a known transformer has two windings, one input and one output, with the same number of turns, so as to serve as galvanic isolation and not as a voltage converter.
[0007] However, if such a transformer is to be used as a voltage divider, this implies that the output winding must have fewer turns than the input winding, and thus carry a higher current. This necessitates a wide output winding, which requires spacing the two auxiliary legs between which it extends, thereby increasing the transformer's overall size. Furthermore, the connection to the output winding must be made through the end openings, which is difficult in part because these openings are already used to accommodate the protruding turns of the inductors.
[0008] It may therefore be desirable to provide a transformer that makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention
[0009] A transformer with integrated inductance is therefore proposed, comprising: a multilayer printed circuit board with several conductive layers; windings, each with at least one turn formed in one of the conductive layers of the multilayer printed circuit board; at least one inductor with at least one turn formed in one of the conductive layers of the multilayer printed circuit board; and a magnetic core comprising: • main legs passing through the multilayer printed circuit board, the windings of the coils being wound around one of the main legs so that the coils are magnetically coupled to each other, the inductor loop being wound around a second of the main legs and possibly the first main leg, and • auxiliary magnetic flux return legs situated around the multilayer printed circuit board, such that the multilayer printed circuit board has a portion inside the auxiliary legs; characterized in that the multilayer printed circuit board passes from the inner portion through a first opening existing between two auxiliary legs to present a first portion outside the auxiliary legs, the turn of a first of the windings extending into the first outer portion of the multilayer printed circuit board.
[0010] Thus, thanks to the invention, it is possible to enlarge the first winding without increasing the overall size of the transformer, and in particular of the magnetic core. Furthermore, since part of the first winding protrudes through the first opening, it is easy to provide a connection with this protruding portion.
[0011] The invention may further include one or more of the following optional features, in any technically feasible combination.
[0012] Optionally, the conductive layers of the printed circuit board include an upper outer conductive layer, at least one inner conductive layer, and a lower outer conductive layer, and the turn of the first winding is formed in one of the outer layers.
[0013] Optionally, the first winding's coil is also in the shape of a circular crown.
[0014] Optionally, the inductor loop and the loop of a second winding are formed in the same conductive layer of the multilayer printed circuit board, and the inductor loop extends around the loop of the second winding.
[0015] Optionally, the inductor loop also extends into the first outer part of the multilayer printed circuit board.
[0016] Optionally, the multilayer printed circuit board passes from the inner part through a second opening existing between two auxiliary legs to present a second part outside the auxiliary legs, and the inductor loop extends into the second outer part of the multilayer printed circuit board.
[0017] Optionally, the transformer also includes two inductors and four auxiliary legs defining four openings between which the multilayer printed circuit board passes from the inner part to present first, second, third and fourth outer parts to the auxiliary legs, and: the turn of the first winding extends into the first outer part and into the third outer part; the turn of the first inductor extends into the second outer part, but not the turns of the windings; and the turn of the second inductor extends into the third outer part, but not the turns of the windings.
[0018] Optionally, the transformer also includes two inductors and three auxiliary legs defining three openings between them through which the multilayer printed circuit board passes from the inner part to present three outer parts to the auxiliary legs, and: the turn(s) of the first winding extend into the first outer part; the turn(s) of the first inductor extend into the second outer part, but not the turns of the windings; and the turn(s) of the second inductor extend into the second outer part, but not the turns of the windings.
[0019] Optionally, the transformer also includes first and second inductors and two auxiliary legs defining two openings between them; the multilayer printed circuit board projects from the inner part through the two openings to present two parts external to the auxiliary legs, and: The turns of the first winding extend into the first outer part; and the turns of the inductors extend into the second outer part, but not the turns of the windings.
[0020] Optionally, the transformer also has three main legs aligned, with the first main leg in the middle of the other two.
[0021] Optionally, the first inductor is also connected in series with one of the windings, preferably other than the first winding.
[0022] Optionally, the auxiliary legs are also equidistant from the first main leg.
[0023] Optionally, the transformer also includes first, second, third, and fourth auxiliary legs, the first and second auxiliary legs being symmetrical to the third and fourth auxiliary legs with respect to a first transverse plane to the multilayer printed circuit board, the first and fourth auxiliary legs being symmetrical to the second and third auxiliary legs with respect to a second transverse plane to the multilayer printed circuit board, the first and second transverse planes intersecting perpendicularly in the first main leg.
[0024] Optionally, the auxiliary legs also have a circular or rectangular cross-section.
[0025] Optionally, the main legs also have a circular or rectangular cross-section.
[0026] Also proposed is an electrical converter comprising: a transformer with integrated inductance according to the invention, in which the inductance is connected in series with one of the windings other than the first winding, and further having another inductance in series with the first winding; and for each of the windings, an active bridge to which this winding and the inductance in series with this winding are connected Brief description of the figures
[0027] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: Figure 1 is an electrical diagram of an electrical converter according to the invention, Figure 2 is an exploded perspective view of a transformer of the electrical converter of Figure 1, Figure 3 is a side sectional view of the transformer of Figure 2, Figure 4 is a first top sectional view of the transformer of Figure 2, Figure 5 is a second top sectional view of the transformer of Figure 2, Figure 6 is a third top sectional view of the transformer of Figure 2, Figure 7 is a top view of an AC transformer that can be used in the electrical converter of Figure 1, and Figure 8 is a top view of an AC transformer that can be used in the electrical converter of Figure 1. Detailed description of the invention
[0028] With reference to Figure 1, an electrical converter 100, in particular DC-DC, according to the invention will now be described.
[0029] The 100 converter is in particular bidirectional and offers galvanic isolation.
[0030] In the illustrated example, the 100 power converter is an active triple bridge converter and current doubler.
[0031] The first 100 electrical converter initially has two input terminals IN+, IN- designed to receive between them a DC input voltage VIN.
[0032] The electrical converter 100 further comprises first, second and third active bridges 104, 106, 108 each comprising four transistors 104A-D, 106A-D, 108A-D.
[0033] Each transistor, such as the 104A-D, 106A-D, or 108A-D, is a metal-oxide-gate field-effect transistor (MOSFET), a silicon metal-oxide-gate field-effect transistor (SiMOSFET), a silicon carbide metal-oxide-gate field-effect transistor (SiCMOSFET), an insulated-gate bipolar transistor (IGBT), or a gallium nitride field-effect transistor (GaN). FET).
[0034] In each active bridge 104, 106, 108, the four transistors 104A-D, 106A-D, 108A-D are arranged in two switching arms, each switching arm having two transistors connected to each other at a midpoint.
[0035] The switching arms of the first active bridge 104 are connected between the input terminals IN+, IN-. In this way, each of the switching arms of the first active bridge 104 receives the input voltage VIN.
[0036] The electrical converter 100 further comprises a transformer 110 having a magnetic core 112, as well as a primary winding BP, a secondary winding BS and a tertiary winding BT wound around the magnetic core 112 to be magnetically coupled to each other.
[0037] The transformer 110 has an integrated inductance, and therefore also includes a primary inductance LP and a secondary inductance LS connected in series with the primary winding BP and the secondary winding BS, respectively. As will be detailed later, the primary inductance LP and the secondary inductance LS each have at least one turn wound around the magnetic core 112. The transformer 110 also has a tertiary inductance LT in series with the tertiary winding BT. Preferably, unlike the primary inductance LP and the secondary inductance LS, the tertiary inductance LT is achieved by appropriately sizing the transformer 110 to control a parasitic inductance so that the latter constitutes the tertiary inductance LT.
[0038] Each winding BP, BS, BT with its inductance LP, LS, LT in series is connected to one of the respective active bridges 104, 106, 108, more precisely between the two midpoints of this active bridge.
[0039] The first electrical converter 100 further includes a control device 114, such as a microcontroller, designed to control the transistors 104A-D, 106A-D, 108A-D of the first, second and third active bridges 104, 106, 108, so that the input voltage VIN is converted into a first output voltage VOUT106 at the output of the second active bridge 106 and into a second output voltage VOUT108 at the output of the third active bridge 108.
[0040] For example, the primary and secondary windings BP and BS have the same number of turns, so the first output voltage VOUT 106 is approximately equal to the input voltage VIN. Again, for example, the tertiary winding BT has fewer turns than the primary winding BP, so the second output voltage VOUT 108 is lower than the input voltage VIN.
[0041] The electrical converter 100 further includes a current doubler 116 connected between the midpoints of one of the second and third active bridges 106, 108, preferably the third active bridge 108, as the latter has a higher output current than the second active bridge 106. The current doubler 116 includes first and second coupled inductors 118, 120 and a magnetic core 122 for magnetic coupling of the coupled inductors 118, 120.
[0042] With reference to Figure 2, transformer 110 will now be described in more detail.
[0043] The transformer 110 is planar and thus comprises a multilayer printed circuit board 202. This board is substantially planar and has two faces 202H, 202B separated by a thickness 204 of the multilayer printed circuit board 202. The two faces 202H, 202B extend one above the other along a direction V taken as the vertical direction. Thus, the printed circuit board 202 defines two sides CH, CB: a first side CH located above (along the direction V) the first face 202H, and a second side CB located below (along the direction V) the second face 202B.
[0044] The multilayer printed circuit board 202 also has three openings 206i, 2062, 2063 in its thickness 204.
[0045] The control device 114 is for example mounted on the multilayer printed circuit board 202.
[0046] The magnetic core 112 of the transformer 110 has several legs J1-3, J'1-4 extending vertically from one side of the printed circuit board 202 to the other. More specifically, the magnetic core 112 has three main legs J1-3 passing through the multilayer printed circuit board 202 in the three openings 2O61-3, respectively. For example, as in the illustrated example, the main legs J1-3 are aligned, with the main leg J3 in the middle of the other two, J1 and J2. Also for example, as in the illustrated example, the main legs J1-3 have a circular cross-section.
[0047] The magnetic core 112 further comprises at least two auxiliary legs J'1-4 located around the multilayer printed circuit board 202, i.e., not passing through the multilayer printed circuit board 202. These auxiliary legs J'1-4 are designed to allow magnetic flux return and, therefore, no winding is intended to be wound around the auxiliary legs J'1-4. For example, as in the illustrated example, the auxiliary legs J'1-4 have a rectangular cross-section. Moreover, preferably, as in the illustrated example, the auxiliary legs J'1-4 are located equidistant from the main leg J3.
[0048] Four auxiliary legs J'1-4 are provided for example, as in the illustrated example. In this case, preferably, the auxiliary legs J'1, J'2 are symmetrical to the auxiliary legs J'3, J'4 with respect to a first plane PT 1 transverse to the multilayer printed circuit board 202, and the auxiliary legs J'1, J'4 are symmetrical to the auxiliary legs J'2, J'3 with respect to a second plane transverse to the multilayer printed circuit board, the first and second transverse planes intersecting perpendicularly to each other in the main leg J3.
[0049] Thus, the magnetic flux return of the BP, BS, BT windings and the LP, LS inductors is divided substantially equally between the auxiliary legs.
[0050] The magnetic core 112 further comprises a first element 208H, for example in the form of a plate, connecting together the first ends of the legs J1-3, J'1-4 located on the first CH side of the multilayer printed circuit board 202, and a second element 208B, for example in the form of a plate, connecting together the second ends of the legs J1-3, J'1-4 located on the second CB side of the multilayer printed circuit board 202.
[0051] With reference to Figure 3, the 202 multilayer printed circuit board includes, for example, from top to bottom in the V direction, an outer upper conductive layer TOP, several inner conductive layers INT1-6 (for example six inner layers as in the illustrated example), and an outer lower conductive layer BOT.
[0052] Each of the windings BP, BS, BT has at least one turn BP1-3, BS1 - 3, BT 1 -2 formed in one of the conductive layers TOP, INT 1 -6, BOT.
[0053] The turns BP1-3, BS1-3, BT1-2 of the BP, BS, BT windings are wound around the main leg J3, so that the BP, BS, BT windings are magnetically coupled together.
[0054] For example, the BP1-3 and BS1-3 turns of the primary BP and secondary BS windings are alternately formed in the internal conductive layers INT1-6 of the 202 multilayer printed circuit board. Thus, in the illustrated example, the BPP1-3 turns of the primary BP winding are formed in layers INT1, INT3, and INT5, respectively, while the BS1-3 turns are formed in layers INT2, INT4, and INT6, respectively. As another example, the BT1-2 turns of the tertiary BT winding are formed in the upper external conductive layer TOP and the lower external conductive layer BOT, respectively.
[0055] The tertiary inductance LT must have a relatively low value (15 nH or more) because the tertiary winding BT has fewer turns than the primary winding BP. This value can be achieved by ensuring a sufficiently large thickness for the outer layers TOP and BOT. For example, this thickness could be 300 µm or more.
[0056] Each of the LP, LS inductors has at least one LP1-3, LS1-3 turn, each LP1-3, LS1-3 turn being formed in one of the TOP, INT1-6, or BOT conductive layers. Thus, the LP, LS inductors can easily be connected in series with the BP primary and LP secondary windings, respectively, within the 202 multilayer printed circuit board.
[0057] More precisely, the primary inductor LP has at least one turn LP1-3 (for example, three, as in the illustrated example) wound around the main leg J1 and, preferably, the third main leg J3. For example, each turn LP1-3 of the primary inductor LP is formed in the same conductive layer as a turn BP1-3 of the primary winding BP, BS, BT. In this case, the turn LP1-3 of the primary inductance LP, LS preferably extends around turn BP1-3 of the primary winding BP.
[0058] Similarly, the secondary inductance LS has at least one turn (for example, three, as in the illustrated example) wound around the main leg J2 and, preferably, the third main leg J3. For example, each turn LS1-3 of the secondary inductance LS is formed in the same conductive layer as a turn BS1-3 of the secondary winding BS. In this case, the turn LS1-3 of the secondary inductance LS preferably extends around this turn BS1-3 of the secondary winding BP.
[0059] Winding the turn(s) of the primary LP and / or secondary LS inductances allows integration into the transformer 110, which allows a reduction in the total length of the tracks, as well as losses and total volume.
[0060] With reference to Figure 4, the auxiliary legs J'1-4 define an interior space El (delimited by dotted lines in Figure 4) into which a so-called interior part of the multilayer printed circuit board 202 extends.
[0061] The four auxiliary legs J'1-4 define between them four openings EA1, EA2, EB1, EB2 through which the multilayer printed circuit board 202 passes from its inner part to present first, second, third and fourth outer parts PA1, PA2, PB1, PB2 protruding from the inner space El delimited by the auxiliary legs J'1-4.
[0062] As can be seen in Figure 4, turn BT1 of the tertiary winding BT extends into the outermost section PA1 and the third outermost section PA2. This is also true for the other turn BT2 of the tertiary winding BT. In contrast, turns BT1-3 of the tertiary winding BT do not extend into the other two outer sections PB1 and PB2 of the multilayer printed circuit board 202. Similarly, turns BP1-3 and BS1-3 of the primary winding BP and secondary winding BS do not extend into the outermost sections PB1 and PB2 of the multilayer printed circuit board 202.
[0063] Referring to Figure 5, the LP1 turn of the primary inductor LP extends into the outer part PB1, as well as into the outer parts PA1 and PA2 where the BT1-3 turns of the tertiary winding BT extend. This is also true for the other LP2-3 turns of the primary inductor LP.
[0064] With reference to Figure 6, the LS1 loop of the secondary inductor LS extends into the outer part PB2, as well as into the outer parts PA1, PA2 where the Turns BT1-3 of the tertiary winding BT are extended. This is also true for the other turns LS2-3 of the secondary inductance LS.
[0065] With reference to figure 7, another 700 transformer according to the invention will now be described.
[0066] The transformer 700 is identical to the transformer 110, except that it has only two auxiliary legs J'1, J'2, defining between them two openings EA1, EB1, through which the multilayer printed circuit board 202 passes from its inner part to present first and second outer parts PA1, PB2 to the auxiliary legs J'1-2.
[0067] The EA1 opening is used to extend the BT1-3 turn(s) of the tertiary winding, while the opening is used to extend the LP1-3, LS1-3 turn(s) of the primary LP and secondary LS inductances.
[0068] More specifically, the turns BT1-3 of the tertiary winding BT extend into the outer part PA1. Conversely, the turns BP1-3 of the tertiary winding BT do not extend into the other outer part PB1, nor do the turns BP1-3 and BS1-3 of the other windings BP and BS. Furthermore, the turns LP1-3 and LS1-3 of the primary inductor LP and the secondary inductor LS extend into the outer part PB1.
[0069] With reference to figure 8, another 800 transformer according to the invention will now be described.
[0070] The transformer 800 is identical to the transformer 110, except that it has only three auxiliary legs J'1 -3, defining between them three openings EA1 , EB1 -2, through which the multilayer printed circuit board 202 passes from its inner part to present three outer parts PA1 , PB1 *2 to the auxiliary legs J'1 -2.
[0071] The EA1 opening is used to extend the BT 1-3 turn(s) of the BT tertiary winding, while the other two openings are used to extend the LP1-3, LS1-3 turn(s) of the LP primary and LS secondary inductances respectively.
[0072] In conclusion, it is clear that a transformer such as the one described above allows the turns of a winding to be widened without significantly increasing the size of the transformer, while still providing easy access to the winding for connection.
[0073] It should also be noted that the invention is not limited to the embodiments described above. Indeed, it will be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.
[0074] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.
Claims
Demands [1] Transformer (110; 700; 800) with integrated inductance, comprising: a multilayer printed circuit board (202) having several conductive layers (TOP, INT1-6, TOP); windings (BP, BS, BT) each having at least one turn (BP1-3, BS1-3, BT1-2) formed in one of the conductive layers (TOP, INT1-6, TOP) of the multilayer printed circuit board (202); at least one inductor (LP, LS) having at least one turn (LP1-3, LS1-3) formed in one of the conductive layers (INT1-6, TOP, BT) of the multilayer printed circuit board (202); a magnetic core (112) comprising: • main legs (J1-3) passing through the multilayer printed circuit board (202), the turns (BP1-3, BS1-3, BT1-2) of the windings (BP, BS, BT) being wound around a first (J3) of the main legs (J1-3) so that the windings (BP, BS, BT) are magnetically coupled to each other, the turn (LP1-3, LS1-3) of the inductor (LP, LS) being wound around a second (J1, J2) of the main legs (J1-3) and possibly the first main leg (J3), and • auxiliary magnetic flux return legs (J'1-4) located around the multilayer printed circuit board (202), such that the multilayer printed circuit board (202) has an inner part to the auxiliary legs (J'1-4); characterized in that the multilayer printed circuit board (202) passes from the inner part through a first opening (EA1, EA2) existing between two auxiliary legs (J'1-J'2, J'3-J'4) to present a first outer part (PA1, PA2) to the auxiliary legs (J'1-4), the turn (BT1-2) of a first (BT) of the windings (BP, BS, BT) extending into the first outer part (PA1, PA2) of the multilayer printed circuit board (202). [2] Transformer (110; 700; 800) with integrated inductance according to claim 1, wherein the conductive layers (TOP, INT1-6, TOP) of the printed circuit board (202) include an upper outer conductive layer (TOP), at least one inner conductive layer (INT1-6), and an outer conductive layer lower (BOT), and in which the turn (BT1 -2) of the first winding (BT) is formed in one of the outer layers (TOP, BOT). [3] Transformer (110; 700; 800) with integrated inductance according to claim 2, wherein the turn (BT1 -2) of the first winding (BT) is in the form of a circular crown. [4] Transformer (110; 700; 800) with integrated inductance according to any one of claims 1 to 3, wherein the turn (LP1-3, LS1-3) of the inductance (LP, LS) and the turn (BP1-3, BS1-3) of a second (BP, BS) winding are formed in the same conductive layer (INT1-6) of the multilayer printed circuit board (202), and wherein the turn (LP1-3, LS1-3) of the inductance (LP, LS) extends around the turn (BP1-3, BS1-3) of the second winding (BP, BS). [5] Transformer (110; 700; 800) with integrated inductance according to any one of claims 1 to 4, wherein the turn (LP1-3, LS1-3) of the inductance (LP, LS) extends into the first outer part (PA1, PA2) of the multilayer printed circuit board (202). [6] Transformer (110; 700; 800) with integrated inductance according to claim 5, wherein the multilayer printed circuit board (202) passes from the inner part through a second opening (EB1, EB2) existing between two auxiliary legs (J'1 - J'4, J'2 - J'3) to present a second outer part (PB1, PB2) to the auxiliary legs (J'1 -4), and wherein the turn (LP1 -3, LS1 -3) of the inductance (LP, LS) extends into the second outer part (PB1, PB2) of the multilayer printed circuit board (202). [7] Transformer (110) with integrated inductance according to claim 6, comprising two inductances (LP, LS) and four auxiliary legs (J'1 -4) defining between them four openings (EA1 , EA2, EB1 , EB2) between which the multilayer printed circuit board (202) passes from the inner part to present first, second, third and fourth outer parts (PA1 , PA2, PB1 , PB2) to the auxiliary legs (J'1 -4), and in which: the turn (BT 1 -3) of the first winding (BT) extends into the first outer part (PA1 ) and into the third outer part (PA2); the turn (LP1 -3) of the first inductance (LP) extends into the second outer part (PB1), but not the turns (BP1 -3, BS1 -3, BT1 -3) of the windings (BP, BS, BT); and the turn (LS1 -3) of the second inductance (LS) extends into the third outer part (PB2), but not the turns (BP1 -3, BS1 -3, BT1 -3) of the windings (BP, BS, BT). [8] Transformer (800) with integrated inductance according to claim 6, comprising two inductances (LP, LS) and three auxiliary legs (J'1-3) defining between them three openings (EA1, EB1, EB2) between which the multilayer printed circuit board (202) passes from the inner part to present three outer parts (PA1, PB1, PB2) to the auxiliary legs (J'1-4), and in which: the turn(s) (BT1-3) of the first winding (BT) extend into the first outer part (PA1); the turn(s) (LP1-3) of the first inductance (LP) extend into the second outer part (PB1), but not the turns (BP1-3, BS1-3, BT1-3) of the windings (BP, BS, BT); and the turn(s) (LS1 -3) of the second inductance (LS) extend into the second outer part (PB2), but not the turns (BP1 -3, BS1 -3, BT1 - 3) of the windings (BP, BS, BT). [9] Transformer (700) with integrated inductance according to claim 6, comprising first and second inductances (LP, LS) and two auxiliary legs (J'1-2) defining between them two openings (EA1, EB1), in which the multilayer printed circuit board (202) is projected from the inner part through the two openings (EA1, EB1) to present two outer parts (PA1, PB1) to the auxiliary legs (J'1-2), and in which: the turn(s) (BT1-3) of the first winding (BT) extend into the first outer part (PA1); and the turns (LP1-3, LS1-3) of the inductances (LP, LS) extend into the second outer part (PB1), but not the turns (BP1-3, BS1-3, BT1-3) of the windings (BP, BS, BT). [10] Transformer (110; 800) with integrated inductance according to any one of claims 1 to 9, comprising three aligned main legs (J1-3), with the first main leg (J3) in the middle of the other two (J1, J2). [11] Transformer (110; 700; 800) with integrated inductance according to any one of claims 1 to 10, wherein the first inductance (LP) is connected in series with one (BP) of the windings, preferably other than the first winding (BT). [12] Transformer (110) with integrated inductance according to any one of claims 1 to 11, wherein the auxiliary legs (J'1-4) are equidistant from the first main leg (J3). [13] Transformer (110) with integrated inductance according to any one of claims 1 to 12, comprising first, second, third and fourth auxiliary legs (J'1-4), the first and second auxiliary legs (J'1, J'2) being symmetrical to the third and fourth auxiliary legs (J'3, J'4) with respect to a first plane (PT1) transverse to the multilayer printed circuit board (202), the first and fourth auxiliary legs (J'1, J'4) being symmetrical to the second and third auxiliary legs (J'2, J'3) with respect to a second plane (PT2) transverse to the multilayer printed circuit board (202), the first and second transverse planes (PT1, PT2) intersecting perpendicularly to each other in the first main leg (J3). [14] Transformer (110; 700; 800) with integrated inductance according to any one of claims 1 to 13, wherein the auxiliary legs (J'1 -4) have a circular or rectangular cross-section. [15] Transformer (110; 700; 800) with integrated inductance according to any one of claims 1 to 14, wherein the main legs (J1-3) have a circular or rectangular cross-section. [16] Electrical converter (100) comprising: a transformer (110; 700; 800) with integrated inductance according to any one of claims 1 to 15, in which the inductance (LP) is connected in series with one of the windings other than the first winding (BT), and further having another inductance in series with the first winding (BT); and for each of the windings, an active bridge (104, 106, 108) to which this winding and the inductance in series of this winding are connected.