FR3143183A1 - Three-phase transformer for isolated voltage converter - Google Patents

Abstract

Three-phase transformer (15) for isolated voltage converter (12), comprising: - a magnetic circuit (22), comprising a first part and a second part, each part comprising: a base (26) of substantially triangular outline, and three pads (27) each extending towards the base of the other part of the magnetic circuit, - three supports (30) of electrical conductors (31, 32), each support (30) being mounted on two pads (27) in view belonging respectively to one and the other part of the magnetic circuit, each support (30) of electrical conductors carrying two electrical windings in inductive coupling with one another via the magnetic circuit, - a housing (50) in which the supports (30) of electrical conductors, the electrical windings and the magnetic circuit (22) are arranged, and - a connection terminal block (45), fixed to the housing (50) and defining six terminals (60 ) for connecting the three-phase transformer to the rest of the isolated voltage converter. Abstract figure: Fig.2

Description

Three-phase transformer for isolated voltage converter

The present invention relates to a three-phase transformer for an isolated voltage converter, such a voltage converter being for example integrated into a component for the electrical supply of a vehicle electrical energy storage unit, also called a "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. The voltage converter receives, for example, an alternating voltage from an electrical network and supplies the battery with a direct voltage. This converter can convey a power greater than 5kW, for example greater than 7kW, for example greater than 11kW, in particular 22kW or more.

It is known to connect the transformer to the rest of the electrical circuit of the converter to make a direct connection to an electronic card placed above the transformer. This results in space problems for placing the card precisely above the transformer, and the need to carry out wave soldering in the assembled converter.

There is a need to remedy the aforementioned drawbacks. The invention aims to meet this need and it achieves this, according to one of its aspects, using a three-phase transformer for an isolated voltage converter, comprising:

- a magnetic circuit, comprising a first part and a second part, each part comprising: a base with a substantially triangular outline, and three pads each extending towards the base of the other part of the magnetic circuit,

- three electrical conductor supports, each support being mounted on two facing pads belonging respectively to one and the other of the parts of the magnetic circuit, each electrical conductor support carrying two electrical windings in inductive coupling one with the 'other via the magnetic circuit,

- a housing in which the electrical conductor supports, the electrical windings and the magnetic circuit are arranged, and

- a connection terminal block, fixed to the housing and defining six terminals for connecting the three-phase transformer to the rest of the isolated voltage converter.

According to the invention, the connection terminal block makes it possible to offset the connection to the rest of the electrical circuit of the voltage converter isolated outside the housing. It is therefore no longer necessary to free up space above the transformer to accommodate an electronic card. This makes it easier to install the transformer in its environment.

The terminal block may have an elongated shape and the six terminals may be arranged in a row. Such an elongated shape and such positioning of the terminals one after the other can further facilitate the installation of the terminal block in the constrained environment of the voltage converter.

The terminal block may comprise a body and a plurality of electrically conductive bars, each terminal being defined by a portion of a bar. Each electrically conductive bar has for example a portion, opposite the portion defining the terminal, which is electrically connected to one of the electrical conductors, for example via a hollow sleeve inside which the conductor is inserted and fixed by crimping or welding.

Each portion of a bar defining a terminal is for example a flat portion, capable of coming into contact with an electrical track of an electronic card for connecting the transformer to the rest of the voltage converter.

Each electrically conductive bar can locally comprise a hole and the fixing of this electrically conductive bar to the body is carried out by means of a screw received in this hole.

According to an example of implementation, the body may comprise a plurality of housings, each housing cooperating with an electrically conductive bar for fixing the latter to the body, the bar fixing screw being received in the housing. In this example of implementation, the bar is fixed to the body directly via the screw, without any intermediate part.

According to another example of implementation, the body can comprise a plurality of housings, each housing comprising an insert providing a hole, each insert cooperating with an electrically conductive bar for fixing the latter on the body, the fixing screw of the bar being received in an insert hole. In this other example of implementation, the bar is fixed to the body via the screw and the insert received in the housing. Such fixation via an insert can be more robust.

When inserts are present, each insert can define a positioning relief of the portion of the electrically conductive bar defining the hole. Such an insert can, in addition to the aforementioned robustness, also help position the portion of the electrically conductive bar on the terminal block.

The aforementioned screws can simultaneously allow the fixing of the electrically conductive bars on the electronic card with which the connection of the transformer to the rest of the voltage converter is made.

Regardless or not of the presence of an insert, the exterior wall of each housing can provide a recess capable of accommodating an end portion of the electrically conductive bar, in order to ensure correct positioning of this bar.

In all of the above, the body can be made of plastic, for example plastic such as polybutylene terephthalate (PBT), or polyamide (PA).

Each insert can be made of metal, in particular steel. Alternatively, each insert can be made of composite material. For example, six inserts are provided, and all of these inserts can have the same shape and/or the same dimensions.

The three electrical conductor supports can be arranged so as to define a geometric pattern being an equilateral triangle. This arrangement of the three electrical conductor supports according to an equilateral triangle can ensure balancing between the electrical parameters such as the inductances of the electrical windings and reduce the magnetic volume.

The housing may have a substantially triangular outline, in particular an equilateral triangle, and the terminal block may be arranged along one of the sides of this outline.

The invention also relates, according to another of its aspects, to a component for the electrical supply of a vehicle electrical energy storage unit, comprising the transformer defined above. The electrical energy storage unit is for example a battery which can have one of the above nominal voltages.

The invention can be better understood on reading the description which follows of non-limiting examples of its implementation and on examining the appended drawing in which:

The invention can be better understood on reading the description which follows of non-limiting examples of its implementation:

- schematically represents part of the electrical circuit of a component for the electrical supply of a vehicle electrical energy storage unit

- shows in elevation an example of a three-phase transformer that can be used in the circuit of the ,

- represents in isolation the magnetic circuit of the three-phase transformer of the ,

- partially represents the three-phase transformer of Figures 2 and 3 when the housing cover is removed

- represents a detail of an example of a system for holding the cover of the transformer housing on the support,

- represents the housing cover of the ,

- represents in isolation the body of the terminal block visible on the ,

- represents the body of the in which inserts are arranged,

- represents the terminal block of Figures 7 and 8 with electrically conductive bar and screw,

- represents the face of the transformer opposite to that shown on the ,

- is a view of the transformer's electrical conductor support from the same side as the , and shows the system for maintaining the support on the magnetic circuit and the system for maintaining the support on the body of the transformer housing carried by this support

- represents the body of the transformer housing on which the support of electrical conductors of the ,

- is a view similar to the and also shows ribs allowing the distance of this support relative to the portion of the magnetic circuit on which it is mounted,

- , And are views similar to that of the , when the electrical conductor support is mounted on the portion of the magnetic circuit,

- is a side sectional view of the ,

- represents three electrical conductor supports of the transformer and their electrical conductors, in the absence of the magnetic circuit,

- represents in isolation one of the three electrical conductor supports of the with its electrical conductors, and

- represents the support of electrical conductors of the without its electrical conductors.

We represented on the a part of the electrical circuit 1 of a component for the electrical supply of a vehicle electrical energy storage unit. This component is also called a “charger”. The electrical energy storage unit, not shown on this , is for example a battery, which can have a nominal voltage greater than 60V, for example greater than or equal to 300V, 400V, 800V, or even 1000V.

Circuit 10 receives as input an alternating voltage from a network not shown which is here three-phase. A rectifier making it possible to convert this alternating voltage into a direct voltage, and also carrying out, if necessary, a power factor correction function (“Power factor correction” in English), is arranged upstream of a direct bus 11. Downstream on this direct bus, from the electrical network, is placed an isolated voltage converter 12, here being a DC/DC. This converter 12 comprises in a known manner an inverter 14, a three-phase transformer 15, and a rectifier 16 supplying the vehicle with a direct voltage isolated from the electrical network. As can be seen on the , the three-phase transformer 15 is connected to each of the rectifier 16 and the inverter 14 by a block of inducances 17 and a block of capacitors 18, so as to define a CLLLC structure. Other structures are of course possible, such as an LLC, CLLC, LC or even CL structure.

As can be seen on the , each phase has a primary winding 20 and a secondary winding 21 in inductive coupling with each other, and the primary windings 20 are star-connected and the secondary windings 21 are also star-connected.

The three-phase transformer 15 comprises in the example considered a magnetic circuit 22, comprising a first part 23 and a second part 24. Each part 23, 24 comprises: a base 26 of substantially triangular outline, and three pads 27 each extending in direction of the base 26 of the other part of the magnetic circuit 22. Each base 26 here has a contour defining an equilateral triangle.

The transformer 15 further comprises three supports 30 of electrical conductors 31, 32, each support 30 being here mounted on two facing pads 27 belonging respectively to one and the other of the parts 23, 24 of the magnetic circuit. Two electrical conductors 31, 32 associated with the same support 30 respectively have a portion defining a primary winding 20 and a portion defining a secondary winding 21. These electrical conductors 31, 32 are for example Litz wire.

As can be seen on the , the three supports 30 of electrical conductors 31, 32 are positioned so as to define an equilateral triangle.

The transformer 15 further comprises a housing 50 comprising a body 51 closed by a cover 52, which are visible in Figures 4 and 6. This body 51 and this cover 52 are for example made of metal, for example aluminum. The supports 30 and the magnetic circuit 22 are arranged inside the housing 50. The body 51 is filled with a resin capable of being polymerized to harden and immobilize the components arranged inside the body ("potting" in English ).

As can be seen in Figures 4 and 6, the housing 50 also has a triangular outline, being more precisely here an equilateral triangle. The housing is in the example considered exclusively formed by the body 51 and the cover 52, but the invention is not limited to a housing 50 consisting of two parts.

As can be seen on the , each pad 27 defines its own air gap 28, for example via a zone of the pad 27 filled with non-magnetic material such as an epoxy resin composite reinforced with fiberglass (FR4) or ceramic. This zone occupied by this non-magnetic material defines, for example, an entire section of the pad. Several sections are for example assembled with this area of the pad 27 to constitute this pad 27.

As can be seen on the , an additional air gap 29 is present between the facing ends of two pads 27 belonging respectively to different parts 23, 24 of the magnetic circuit 22. Thus, in the example of magnetic circuit 22 considered, each magnetic field allowing inductive coupling between a primary winding 20 and a secondary winding 21 cross exactly three air gaps.

Still on the , we see that the magnetic circuit 22 of the example considered comprises a central leg 40 carried by one of the parts 23, 24 of the magnetic circuit 22. This central leg 40 is here made in one piece with the part 23 of the magnetic circuit 22 which carries it.

We see on the that the central leg 40 extends in this example continuously between two ends each being in contact with one of the bases 26 of the magnetic circuit 22, so that no air gap is left in the central leg 40.

We also see on the or on the that the central leg 40 has a core 41 and three protrusions 42 extending from this core 41, each protrusion 42 extending between two neighboring pads 27 carried by the same part of the magnetic circuit.

As can be seen on the , in the example considered, each stud 27 has a circular exterior contour, and each protrusion 42 of the central leg 40 here has a wall facing the studs 27 of rounded shape.

As can be seen on the , the three-phase transformer 15 includes a connection terminal block 45. This connection terminal block 45 is fixed to one side of the housing 50 of the three-phase transformer 15. As can be seen in the , the terminal block 45 here defines six terminals 60 for the connection of the three-phase transformer 15 to the rest of the electrical circuit 10, these terminals 60 being represented schematically on the . These terminals 60 come here into contact with electrical tracks of an electronic card not shown.

The connection terminal block 45 presents, as can be seen on the , an elongated shape, and the six terminals 60 are here arranged in a row.

The different elements of the terminal block 45 according to the embodiment shown will now be described with reference to Figures 7 to 9

The terminal block 45 here comprises a body 61 and a plurality of electrically conductive bars 62, each terminal 60 being defined by a portion 63 of a bar. Each portion 63 is here flat, so as to come into contact with an electrical track of the electronic card mentioned above. The body 61 can be made of plastic, for example PBT, PA, etc.

Each electrically conductive bar 62 has for example a portion 65, opposite the portion 63 defining the terminal, which is electrically connected to one of the electrical conductors 31, 32, here via a hollow sleeve 66 inside which the conductor 31, 32 is inserted, for example fixed by crimping or welding.

Each electrically conductive bar 62 locally comprises a hole 67 and the fixing of this electrically conductive bar 62 on the body 61 is carried out by means of a screw 68 received in this hole 67. The body 61 here comprises six housings 69, and each of these housings receives an insert 70 providing a hole 71, the aforementioned screw 68 being received in an insert hole 71. Thus, the fixing of the electrically conductive bar 62 on the body 61 is done via the screw 68 and the insert 70 received in housing 69. Each insert 70 can be made of metal, in particular steel. Alternatively, each insert is made of composite material. Six inserts are for example provided, and all these inserts 70 have in the example considered the same shape and the same dimensions. Each screw 68 can, in addition to ensuring the fixing of an electrically conductive bar 62 on the body 61, also ensure the fixing of the electrically conductive bar 62 on the electronic card not shown.

As can be seen on the , each insert 70 can define a positioning relief 73 of the portion 63 of the electrically conductive bar defining the hole 67. This positioning relief 73 is for example a flat surface of circular shape.

As can be seen in Figures 2, 7 and 8, the exterior wall of each housing 69 can provide a recess 75 capable of accommodating an end portion 64 of the electrically conductive bar 62, in order to ensure correct positioning of this bar on the body 61 and to avoid any relative rotation between this bar and this body.

In another example of implementation not shown, the body 61 comprises a plurality of housings 69 which directly receive the screws 68, in the absence of insert 70. In this other example of implementation, the fixing of the bar electrically conductor 62 on the body 61 is done directly via the screw 68, without an intermediate part.

As can be seen in Figures 4 and 5, each support 30 of electrical conductors can integrate a system 80 for holding the cover 52 on this support 30.

Each support 30 comprises for example a single pin 81 projecting relative to the rest of the support 30 along the longitudinal axis of the latter. Alternatively, only two of the three supports of the transformer 15 include a pin 81, the third support 30 being devoid of it.

There represents in detail a pin 81, the latter being able to have a section perpendicular to the longitudinal axis of the support which is cruciform. Each pin 81 of a support 30 of electrical conductors is in the example considered received by force in an opening provided in the cover 52, as can be seen in the . The relative arrangement of the pins 81 of the supports 30 makes it possible to immobilize the cover 52.

As can be seen on the , the system 80 for holding the cover 52 on the support 30 can extend along the longitudinal axis of the support 30 on the same side of the support 30 as a system for guiding electrical conductors 85 which will be described in reference to figures 18 to 20.

In these Figures 18 to 20, the holding system 80 is not shown, the guiding system 85 may be present without necessarily the holding system 80 being present.

As can be seen on the , each electrical conductor 31, 32 carried by a support 30 of the transformer 15 can be guided outside the winding 20, 21 which it defines.

In the example considered, each of these conductors 31, 32 is guided by the guiding system 85 beyond each of the ends of the electrical winding 20, 21 which it defines. As already mentioned previously, the first ends of the electrical conductors can constitute an output to the electrical circuit 10 outside the transformer 15, and three of the second ends of the electrical conductors can lead to a common point via a star connection to the primary, and three more of these second ends of the electrical conductors can lead to a common point via another star connection at the secondary.

The support 30 of the two electrical windings 31, 32 includes:

- a wall 90 around which the electrical windings 20, 21 are arranged, and this wall 90 defines in the example considered but in a non-limiting manner a hollow cylinder of circular cross section, and

- three edges 92, 93, 94 offset along the longitudinal axis of the support, so that one of the electrical windings 31 is arranged between the first 92 and the second edge 92 and the other of the electrical windings 32 is arranged between the second 93 and the third 94 edge, as is clearly visible on the For example. The distance between two consecutive edges 92, 93 and 93, 94 remains constant in the example considered.

The guiding system 85 acts on the electrical conductors on the one hand via clamps 97 and 98, and on the other hand via additional walls 105 and 106.

In the example of Figures 18 to 20, the guide system 85 comprises, for each electrical conductor 31, 32, on the one hand a first clamp 97 cooperating with this electrical conductor 31, 32 beyond the first end of the electrical winding 20, 21 which it defines. Such a clamp 97 has for example two arms 99 curved so as to match a zone of the contour of this end of the electrical conductor, as shown in the or 20. This is a circular outline. Each clamp 97 is for example, but in a non-limiting manner, made in one piece with the rest of the support 30 of electrical conductors. As already explained, each first clamp 97 cooperates for example with a portion of electrical conductor 31,32 on the way to a connection terminal 60.

The guiding system 85 also comprises a second clamp 98 cooperating with the electrical conductor beyond the second end of the electrical winding which it defines, these first 97 and second 98 clamps succeeding one another along the one of the first 92, second 93 and third 94 ledges. As already explained, each second clamp 98 cooperates for example with a portion of electrical conductor 31,32 on the way to a common point of a star connection.

More precisely, in the example considered:

- the first rim 92 comprises two first clamps 97 which each cooperate respectively with one of the electrical conductors 31, 32 beyond the first end of the electrical winding 20, 21 which it defines, and two second clamps 98 which each cooperate respectively with an electrical conductor beyond the second end of this electrical winding 20, 21, and

- the second rim 93 comprises a first clamp 97, disposed under a first clamp 97 of the first rim 92, and a second clamp 98, disposed under a second clamp 98 of the first rim. The clamps carried by the second rim 94 make it possible to guide the electrical conductor 32 outside the electrical winding disposed between the second rim 93 and the third rim 94.

We see in Figures 18 to 20 that, along the edge 92, there are two pairs of pliers each formed of a first pliers 97 and a second pliers 98, and that the distance between two pairs of pliers is greater to the distance between two pliers of the same pair.

We also see in these Figures 19 and 20 that the clamps 97, 98 carried by the second rim 93 are aligned along the axis of the cylindrical wall 90 with clamps 97, 98 carried by the first rim 92.

We will now describe the two additional walls 105 and 106 of the guide system 85. These two additional walls 105 and 106 are here offset so as to define between them a guide channel 108 receiving the electrical conductors 31, 32 in a stacked manner. exterior of the windings 20, 21 which they define. Channel 108 here has a constant dimension. These additional walls extend in the example considered on either side of an arcuate portion of the first rim 92, projecting axially beyond this first rim 92. In the overlapping zone of this first rim 92, the additional walls 105 and 106 each define an arcuate portion, the wall 106 having a radius greater than the wall 105, as is also visible on the .

We see in Figures 18 to 20 that the wall 106 comprises first openings 110 for the passage of the electrical conductors 31, 32 towards the electrical winding 20, 21 which it defines, and second openings 111 in which no electrical winding pass. It can be seen that the first openings 110 are arranged radially facing a clamp 97, 98.

In the example of Figures 10 to 12, each support 30 of electrical conductors 31, 32 also integrates a holding system 120 on the body 51 of the housing 50. This holding system 120 here comprises a pin 121, having in this example a section perpendicular to the longitudinal axis of the support which is cruciform. This pin 121 extends axially away from the rest of the support 30 from the third rim 94. As can be seen in Figures 10 and 12, each pin 121 is received by force in an opening 122 provided in the body 51 of the housing 50. This holding system can ensure immobilization of the magnetic circuit 22 on the body 51 of the housing before polymerization of the resin contained in this housing 50.

When such holding systems 120 exist, they may or may not be combined with the aforementioned holding systems 80 and guiding systems 85. As can be seen in Figures 10 to 12, each holding system 120 can then extend axially on one side of the support 30 while the holding system 80 and the guiding system 85 extend axially on the opposite side of support 30.

We will now describe with reference to Figures 13 to 15, a functionality which can be integrated into all or part of the supports 30 of electrical conductors 31, 32. A system 130 for holding support 30 of electrical conductors 31, 32 on the magnetic circuit 22 is thus provided. This holding system 130 is in the form of two pads 132 projecting relative to the rest of the support 30. When the holding system 120 is provided, these systems 130 and 120 can extend axially on the same side of the support , the pin 121 and a pad 132 being arranged in particular side by side as can be seen in the example of the .

Each pad 132 here defines a surface 135 coming into contact with a surface 136 of a base 26 of the magnetic circuit 22. The surfaces 135 and 136 are planar here. Each pad 132 is for example supported by a reinforcement 133, as visible on the .

As deduced from the , the cooperation between the two pads 132 of a support 30 and the base 26 can ensure immobilization in rotation of the support 30 on the magnetic circuit 22.

We will now describe with reference to Figures 13 to 16 another functionality which can be integrated into all or part of the supports 30 of electrical conductors 31, 32. We see in these figures that the cylindrical wall 90 of the support 30 comprises ribs 142 extending away from the wall 90 towards the stud 27 on which this support is mounted.

In the example considered, six ribs 142 are provided, but the invention is not limited to a precise number of ribs 142. These six ribs 142 thus constitute a spacing system 140 of the cylindrical wall 90, and therefore electrical windings 20, 21 which it carries, of pad 27.

We see in Figures 13 to 16 that all the ribs 142 can have the same shape and be distributed uniformly around the stud 27.

We also see in these figures that each rib 142 can extend continuously along the axis of the support 30 from the first rim 92 to the third rim 94.

In a variant not shown, all or part of the ribs extend discontinuously along the axis of the support 30.

As can be seen on the , each rib 142 does not extend for example as far as the pad 27 on which the support 30 is mounted. An empty space ensuring easy assembly thus remains present between each end of a rib facing the stud 27 and this stud 27.

As already mentioned, each support 30 of electrical conductors 31, 32 can be made in one piece.

When this support 30 integrates:

-the ribs 142, and/or

- the holding system 80 of the cover 52 on the support, and/or

- the guiding system 85 of electrical conductors, and/or

- the system for holding the support 120 on the body 51 of the housing, and/or

- the system 130 for holding the support on the magnetic circuit 22,

all these systems can be made in one piece or not with the rest of the support 30. In a particular example, the support 30 is thus in one piece and has all or part of the aforementioned functionalities.

The invention is not limited to the examples which have just been described.

Claims (11)

Three-phase transformer (15) for isolated voltage converter (12), comprising:
- a magnetic circuit (22), comprising a first part and a second part, each part comprising: a base (26) of substantially triangular outline, and three pads (27) each extending towards the base of the other part of the magnetic circuit,
- three supports (30) of electrical conductors (31, 32), each support (30) being mounted on two facing pads (27) belonging respectively to one and the other of the parts of the magnetic circuit, each support ( 30) electrical conductors carrying two electrical windings in inductive coupling with one another via the magnetic circuit,
- a housing (50) in which the supports (30) of electrical conductors, the electrical windings and the magnetic circuit (22) are arranged, and
- a connection terminal block (45), fixed to the housing (50) and defining six terminals (60) for connecting the three-phase transformer to the rest of the isolated voltage converter. Transformer according to claim 1, the terminal block (45) having an elongated shape and the six terminals (60) being arranged in a row. Transformer according to claim 1 or 2, the terminal block (60) comprising a body (61) and a plurality of electrically conductive bars (62), each terminal (60) being defined by a portion (63) of a bar (62) . Transformer according to claim 3, each electrically conductive bar (62) locally comprising a hole (67) and the fixing of this electrically conductive bar (62) to the body (61) of the terminal block (45) is carried out by means of a screw (68) received in this hole (67). Transformer according to claim 4, the body (61) comprising a plurality of housings (69), each housing (69) cooperating with an electrically conductive bar (62) for fixing the latter on the body (61), the screw ( 68) for fixing the bar being received in the housing (69). Transformer according to claim 4, the body (61) comprising a plurality of housings (69), each housing (69) comprising an insert (70) providing a hole (71), each insert (70) cooperating with an electrically conductive bar ( 62) for fixing the latter on the body (61), the fixing screw (68) of the bar (62) being received in a hole (71) of insert (70). Transformer according to claim 6, each insert (70) defining a positioning relief (73) of the portion (63) of the electrically conductive bar (62) defining the hole (67). Transformer according to any one of the preceding claims, the body (61) of the terminal block (45) being made of plastic. Transformer according to claim 8 and one of claims 6 and 7, each insert (70) being made of metal, in particular steel. Transformer according to any one of the preceding claims, the housing (50) having a substantially triangular contour, and the terminal block (45) being arranged along one of the sides of this contour. Component (1) for the electrical supply of a vehicle electrical energy storage unit, comprising the transformer (15) according to any one of the preceding claims.