Winding, inductive filter and integrated filtering transformer

Abstract

The invention relates to a winding configured to ensure the passage of an electric current between two main connection points, the device comprising: - a magnetic core (12), - a main electrical conductor (14) in the form of a first flat ribbon extending between two ends, each equipped with one of the main connection points (14c, 14d), and wound around the magnetic core (12) to form an inductance, - an auxiliary electrical conductor (20) in the form of a second ribbon wound together with the main electrical conductor, and equipped with an auxiliary connection point (20c), - an electrical insulator (22) separating the main electrical conductor from the auxiliary electrical conductor to form a capacitor between the two electrical conductors. Figure for the abstract: Fig. 1.

Description

Title of the invention: Winding, inductive filter and transformer with integrated filtering

[0001] The invention relates to a winding, an inductive filter and a transformer improving the filtering of certain high-frequency disturbances.

[0002] The invention finds particular utility in the aeronautical field where the current trend is to increase the number of electrical equipment and therefore the on-board electrical power.

[0003] An aircraft generally comprises a large number of electrical loads supplied with power by an on-board electrical supply network. For example, the aircraft's flight controls, air conditioning systems and internal lighting use three-phase alternating current electrical machines. The electrical energy supplied to these machines comes from power converters connected to an on-board network delivering electrical energy in direct or alternating form. The on-board network may comprise, for example, electrical generators, storage batteries, or even means of connection to an electrical supply network external to the aircraft and enabling the aircraft to be supplied with electricity when it is parked at an airport. 540V direct current networks and / or 115V or 230V 400Hz alternating current networks are commonly found on board aircraft.As is known, power converters receive energy from the on-board network to convert it into polyphase alternating energy adapted to the power and frequency requirements of the load.

[0004] Among the converters, we often find transformers for lowering or raising an alternating voltage. We also find static converters comprising electronic switches. Examples include inverters operating in pulse width modulation in order to generate an alternating voltage. Certain loads, supplied with polyphase alternating voltage, may require the presence of a neutral in addition to the different supply phases. The neutral can be generated at the output of the inverter by means of a particular transformer.

[0005] In static converters, the switching frequency is much higher than the frequency of the useful alternating voltage generated by the inverter. The presence of this switching frequency tends to create high-frequency disturbances which tend to propagate on the on-board networks. It is possible to have low-pass filters at the input or output of the converters to filter out high-frequency disturbances. These filters can be made up of inductors connected in series and capacitors in parallel. The presence of transformers also tends to filter high-frequency disturbances due to inductance in the transformer windings. It is often necessary to supplement these transformers with capacitors also connected in parallel.

[0006] In many vehicles and more particularly in aircraft, the reduction of on-board mass is a recurring problem that arises. The current trend towards increasing on-board electrical equipment therefore tends to increase not only the mass but also the volume of the filters necessary for the proper functioning of the on-board electrical system.

[0007] The invention aims to overcome all or part of the problems mentioned above by proposing to reduce or even eliminate the external capacitors associated with the inductors and transformers.

[0008] To this end, the invention relates to a winding configured to ensure the passage of an electric current between two main connection points, the device comprising: - a magnetic core, - a main electrical conductor in the form of a first flat ribbon extending between two ends each equipped with one of the main connection points, and being wound around the magnetic core to form an inductance, - an auxiliary electrical conductor in the form of a second ribbon wound together with the main electrical conductor, and equipped with an auxiliary connection point, - an electrical insulator separating the main electrical conductor from the auxiliary electrical conductor to form a capacitance between the two electrical conductors.

[0009] Advantageously, the main electrical conductor and the auxiliary electrical conductor are superimposed over their entire length defined along an axis extending in a plane perpendicular to an axis of the magnetic core.

[0010] Advantageously, the main electrical conductor and the auxiliary electrical conductor are partially superimposed.

[0011] The auxiliary connection point may be located at one of the ends of the auxiliary electrical conductor, an end defined along an axis extending in a plane perpendicular to an axis of the magnetic core.

[0012] Alternatively, the auxiliary connection point may be located between the ends of the auxiliary electrical conductor, ends defined along an axis extending in a plane perpendicular to an axis of the magnetic core.

[0013] The materials of the main electrical conductor and the auxiliary electrical conductor (20) may be the same or different.

[0014] The auxiliary electrical conductor may be equipped with a second connection point- auxiliary wiring.

[0015] The electrical conductors extend along a main axis extending in a plane perpendicular to an axis of the magnetic core and a secondary axis perpendicular to the main axis. A degree of overlap of the two conductors along the secondary axis may vary along the main axis.

[0016] The electrical conductors may each have a U-shape, the U-shapes being nested.

[0017] The invention also relates to a transformer comprising at least one winding according to the invention, the winding forming a primary winding of the transformer and a second main electrical conductor wound around the magnetic core of the electromagnetic winding and forming a secondary of the transformer.

[0018] The invention also relates to a component comprising two windings (10) according to the invention, the two windings are wound around the same closed magnetic core.

[0019] The invention will be better understood and other advantages will appear on reading the detailed description of an embodiment given by way of example, a description illustrated by the attached drawing in which:

[0020] [Fig.l] schematically represents in perspective a winding according to the invention;

[0021] [Fig.2] schematically represents in section, the winding of [Fig.l];

[0022] Figures 3 to 8 show electrical conductors and electrical insulation of the winding in flattened view;

[0023] Figures 9 to 12 show several variants of the shape of one of the electrical conductors;

[0024] [Fig. 13] shows a variant of winding the electrical conductors;

[0025] [Fig. 14] schematically represents a neutral transformer putting into implements the invention;

[0026] [Fig. 15] represents an inductive filter comprising two windings in accordance with the invention.

[0027] For the sake of clarity, the same elements will bear the same references in the different figures.

[0028] [Fig.l] schematically represents a winding 10 in perspective comprising a magnetic core 12 and an electrical conductor 14 called the main electrical conductor and wound around the magnetic core 12. The magnetic core 12 has, in the example shown, the shape of a bar extending along an axis 16. Any other shape of magnetic core is possible within the scope of the invention. It is in particular possible to implement a closed magnetic core in order to channel the magnetic field lines. Such a closed core then comprises a rectilinear part extending along the axis 16.

[0029] [Fig.2] shows the winding 10 in section in a plane perpendicular to the axis 16. The main electrical conductor 14 is in the form of a flat ribbon wound around the magnetic core 12. The main electrical conductor 14 mainly comprises a strip of electrically conductive material formed between two main faces 14a and 14b which are parallel to the axis 16.

[0030] The main electrical conductor 14 extends between two main connection points 14c and 14d so as to form an electrical winding around the magnetic core 12. In practice, each main connection point 14c and 14d is located at one end of the strip. An electric current flowing in the main electrical conductor 14 generates a magnetic induction in the magnetic core 12 oriented mainly along the axis 16.

[0031] The main electrical conductor 14 and the magnetic core 12 form an inductance which can be used in particular as a filtering inductance, in particular taken in isolation or as part of a transformer.

[0032] The winding 10 comprises an auxiliary electrical conductor 20 and an electrical insulator 22 separating the main electrical conductor 14 from the auxiliary electrical conductor 20. The auxiliary electrical conductor 20 is also in the form of a flat ribbon wound together with the main electrical conductor 14 to form a capacitance between the two electrical conductors 14 and 20. The auxiliary electrical conductor 20 also mainly comprises a strip of electrically conductive material formed between two main faces 20a and 20b which are also parallel to the axis 16. In the same way, the electrical insulator 22 is in the form of a flat ribbon wound together with the two electrical conductors 14 and 20. The electrical insulator 22 also mainly comprises a strip of electrically insulating material formed between two main faces 22a and 22b which are parallel to the axis 16.

[0033] In practice, the main electrical conductor 14 forms one of the conductive plates or electrodes of the capacitor. The auxiliary electrical conductor 20 forms the other electrode of the capacitor. The auxiliary electrical conductor 20 is equipped with an auxiliary connection point 20c for electrically connecting the other electrode of the capacitor.

[0034] The electrical insulator 22 forms the dielectric of the capacitor. The face 14a faces the face 20b and are separated by the electrical insulator 22. The capacitor is electrically connected between the connection point 20c and one of the connection points 14c or 14d.

[0035] The invention makes it possible to combine, within the same component, an inductance formed by the main conductor 14 wound around the magnetic core 12 and a capacitance formed between the two electrical conductors 14 and 20. On the magnetic core 12, [Fig. 2], the main conductor 14 is wound around the magnetic core genetic 12 to form a turn. In practice, it is possible to implement the invention for a greater number of turns.

[0036] Figures 3 to 8 show different variants of the electrical conductors 14 and 20 and the electrical insulator 22 in a flattened view in which a surface wound around the axis 16 is shown in a plane. In other words, the electrical conductors 14 and 20 and the electrical insulator 22 wound around the magnetic core are shown in the form of superimposed planes in Figures 3 to 8.

[0037] In [Fig. 3], the surfaces formed by the electrical conductors 14, 20 and the electrical insulator 22 are completely superimposed. In other words, the two strips are superimposed over their entire length, the length running along an axis XX shown in the form of a straight line in [Fig. 3] and spiraling around the magnetic core 12 in a plane perpendicular to the axis 16. Along an axis YY perpendicular to the axis XX and therefore parallel to the axis 16, the surfaces formed by the electrical conductors 14, 20 and the electrical insulator 22 are also completely superimposed. In this complete superposition configuration, the capacitance formed between the two electrical conductors 14 and 20 is maximum.

[0038] It is possible to adapt the value of the capacitance formed between the two electrical conductors 14 and 20 to the filtering requirement of the system equipped with a winding according to the invention. [Fig. 4] represents a variant in which an electrical insulator 22-1 and an auxiliary electrical conductor 20-1 are similar, respectively to the electrical insulator 22 and to the auxiliary electrical conductor 20 except for the overlap along the axis XX which, in the variant represented in [Fig. 4], is partial. It is also possible to vary the overlap along the axis YY. For example, [Fig. 5] represents an auxiliary electrical conductor 20-2 only partially covering the main electrical conductor 14 along the axis YY. The variation in the overlap rate can of course be defined along the axes XX and YY independently of each other. It is for example possible to define a complete overlap along the axis XX and a partial overlap along the axis YY.This simplifies the manufacture of the winding by keeping ribbons of the same length along the XX axis for the two conductors and for the insulation. The adaptation of the capacity value is then done by varying the respective widths of the ribbons, widths defined along the YY axis. In the variant shown in [Fig.5], the coverage rate along the YY axis is constant along the XX axis. It is also possible to vary the coverage rate along the YY axis, along the XX axis.

[0039] In the variants shown in Figures 3, 4 and 5, the auxiliary electrical conductor is equipped with a single connection point located at one of the ends along the axis XX of the strip forming the auxiliary electrical conductor. [Fig.6] represents an alternative where the auxiliary connection point 20c is located between the ends of the tape forming the auxiliary electrical conductor 20. In other words, a portion of the auxiliary electrical conductor 20 is located on one side of the auxiliary connection point 20c and another portion of the auxiliary electrical conductor 20 is located on the other side of the auxiliary connection point 20c.

[0040] The main and auxiliary connection points can be made by means of a tab projecting from the surface of the electrical conductor considered along the YY axis. The tab can be attached and punched onto the electrical conductor considered. Thus, once the electrical conductors are wound around the magnetic core 12, the connection points project from the winding and are easily accessible for connecting the coil. This embodiment of the connection points is suitable for any position of the connection points along the XX axis.

[0041] [Fig.7] represents a variant of the winding in which the auxiliary electrical conductor 20 is equipped, in addition to the connection point 20c located at one end of the strip forming the auxiliary electrical conductor, with a second connection point 20d located at the other end of the strip along the axis XX. In addition to the capacitance present between the two conductors 14 and 20, the second connection point 20d makes it possible to use the auxiliary electrical conductor to circulate an electric current therein as in the main electrical conductor 14. In addition to the capacitance, the winding can also be used as a transformer with two windings 14 and 20. In practice, the terms “main electrical conductor” and “auxiliary electrical conductor” are then interchangeable.By making the two conductors 14 and 20 from the same material with a 100% coverage rate along the XX and YY axes, the disparity between the inductance values ​​of the two conductors 14 and 20 is minimized. This winding variant is then well suited to the production of a common mode filter that is both inductive and capacitive.

[0042] Alternatively to the connection of the two connection points 20c and 20d, the variant shown in [Fig.7] also makes it possible to propose a winding using only the capacity between the two conductors without circulating current in the auxiliary electrical conductor 20, in which it is possible to choose the connection point either 20c or 20d.

[0043] [Fig.8] shows a variant in which two separate auxiliary electrical conductors 20-3 and 20-4 are present, each forming a separate capacity with the main electrical conductor. It is of course possible to provide more than two separate capacities. The two auxiliary electrical conductors 20-3 and 20-4 are each shown with two connection points, respectively 20-3c, 20-3d and 20-4c, 20-4d. It is also possible to provide only one connection point. connection by auxiliary electrical conductor 20-3 and 20-4. This connection point can be arranged at one end of the strip forming the auxiliary electrical conductor considered along the XX axis or between the ends of the strip considered. As for the variant of [Fig.7], the variant of [Fig.8] can be implemented either by circulating a current between the connection points, 20-3c and 20-3d on the one hand and 20-4c and 20-4d on the other hand. It is also possible to connect only one auxiliary connection point by auxiliary electrical conductors 20-3 and 20-4.

[0044] [Fig. 9] represents a variant of the auxiliary electrical conductor 20-5 equipped with two auxiliary connection points, as shown in Figures 7 and 8. The auxiliary electrical conductor 20-5 extends generally along the axis XX and winds around the axis XX in order to generate an additional inductance between the two auxiliary connection points. In addition to the capacitance generated between the conductors 14 and 20-5, the auxiliary electrical conductor 20-5 generates a first inductance linked to the magnetic core 12 due to its winding around the magnetic core 12 and a second inductance not linked to the magnetic core 12 due to the serpentine shape of the auxiliary electrical conductor 20-5 around the axis XX. This serpentine shape forms a variation of the overlap rate of the two conductors 14 and 20-5 along the axis YY, along the axis XX.

[0045] Figures 10, 11 and 12 show other possible examples for varying the overlap rate of the two conductors 14 and 20 along the YY axis, along the XX axis. More precisely, in [Fig. 10], the auxiliary conductor 20-6 has a shape whose width along the YY axis varies sinusoidally along the XX axis. In [Fig.l 1], the auxiliary conductor 20-7 has a shape whose width along the YY axis varies in a sawtooth pattern along the XX axis and in [Fig. 12], the auxiliary conductor 20-8 has a shape whose width along the YY axis varies in notches along the XX axis. The shapes of the auxiliary conductors shown in Figures 9 to 12 are periodic along the XX axis. Any other periodic shape is also possible. It is also possible to produce an auxiliary conductor having an aperiodic shape. It is also possible to vary the shape of the main conductor 14, or even of both conductors at the same time.

[0046] Any conductor shape with angular contours, such as the sawtooth and crenellated shapes shown in Figures 11 and 12, can cause peak effects in the electric field between the two conductors. On the other hand, rounded shapes, such as that shown in [Fig. 10], can prevent these peak effects.

[0047] [Fig. 13] shows an embodiment of a winding 25 according to the invention in which the main conductor 14-1 and auxiliary conductor 20-9 both have a U-shape along the axis YY. The two U-shapes are nested. More precisely, one of the branches of one of the U-shapes is inserted between the two branches of the other U-shape. U. The 22-1 insulation separating the two conductors 14-1 and 20-9 is also folded and snakes between the legs of the respective U-shapes.

[0048] The two conductors 14-1 and 20-9 and the insulator 22-1 are first folded into a U and nested flat, i.e. the axis XX being rectilinear. This nested assembly is then wound around the magnetic core 12. In other words, the axis XX is wound in a spiral around the magnetic core as illustrated in [Fig.l]. In [Fig. 13], the nested assembly is wound in two layers around the magnetic core 12. This nesting makes it possible to increase the number of capacitive interfaces for each turn of the spiral. For example, in [Fig. 13], seven capacitive interfaces appear for a spiral with two turns around the axis 16.

[0049] The main electrical conductor 14 is caused to be traversed by an electric current having an intensity which may be greater than that circulating in the auxiliary electrical conductor, in particular when an output phase of a converter circulates through the main electrical conductor and the auxiliary electrical conductor is equipped with only a single connection point and is only used to generate a capacitance. The materials of the two electrical conductors 14 and 20 may then be different. For example, the material of the main electrical conductor 14 may be metallic, for example based on aluminum or copper. The material of the auxiliary electrical conductor 20 may also be metallic or made of other conductive materials such as in particular based on graphite. The materials of the two electrical conductors 14 and 20 may be diamagnetic, non-magnetic or ferromagnetic.The choice of the type of material may be different for the two electrical conductors 14 and 20. It is for example possible to jointly produce the auxiliary electrical conductor 20 and the insulator 22 for example in the form of a flexible printed circuit. This is particularly suitable if one wishes for example to adapt the design of the auxiliary electrical conductor 20-5 as appears in figures 9 to 12.

[0050] [Fig. 14] represents an example of a neutral transformer 30 adapted to the output of a three-phase inverter. In practice, a three-phase inverter, or more generally a multi-phase inverter, generates three phases u, v, w without neutral. Certain multi-phase loads may require connection to an electrical neutral potential in addition to the connection to the different phases. The transformer 30 can be connected to the three phases of the inverter in parallel with the connection to the load. The transformer 30 delivers a neutral potential denoted N which is intended to be connected to the load.

[0051] The transformer 30 comprises a magnetic core 32 comprising three branches 32u, 32v and 32w. Around the branch 32u are wound jointly, as previously described, a main electrical conductor 14u and an auxiliary electrical conductor 20u. Similarly, around the branch 32v are wound jointly a 14v main electrical conductor and a 20v auxiliary electrical conductor. Around the 32w branch are wound together a 14w main electrical conductor and a 20w auxiliary electrical conductor.

[0052] The first connection point of the main electrical conductor 14u is connected to the phase u, the first connection point of the main electrical conductor 14v is connected to the phase v and the first connection point of the main electrical conductor 14w is connected to the phase w.

[0053] The second connection point of the main electrical conductor 14u is connected to an input of another 34v winding arranged around the 32v branch, the second connection point of the main electrical conductor 14v is connected to an input of another 34w winding arranged around the 32w branch and the second connection point of the main electrical conductor 14w is connected to an input of another 34u winding arranged around the 32u branch. The outputs of the windings 34u, 34v and 34w are connected together to form the neutral N of the transformer 30.

[0054] The auxiliary electrical conductors 20u 20v and 20w are connected together for example to an electrical ground 36 which can be the neutral N by means of a resistive component R. In [Fig. 14], the connection of the auxiliary connection points of the auxiliary electrical conductors 20u 20v and 20w is shown in the vicinity of the respective connection points of the main electrical conductors 14u, 14v and 14w to the corresponding phases u, v and w. Alternatively, it is quite possible to arrange the auxiliary connection points at the other end of the respective auxiliary electrical conductors 20u 20v and 20w and even between the ends in the manner described in [Fig.6].

[0055] The signal of each phase u, v and w, sees an inductance formed by the two windings connected in series, for example the winding 14u and the winding 34v for the phase u, and a capacitance in parallel, for example the capacitance associated with the auxiliary electrical conductor 20u. This inductance and this capacitance form a low-pass filter. The resistor R makes it possible to dampen the filtered high-frequency disturbances.

[0056] As shown in [Fig. 14], for each of the phases, the transformer 30 comprises only one auxiliary electrical conductor associated with each main electrical conductor. It is also possible to complete this embodiment by associating an auxiliary electrical conductor wound jointly with each of the windings 34u, 34v and 34w. The different auxiliary electrical conductors can be connected in different ways, for example in series, in parallel or by implementing a combination of series and parallel connections.

[0057] It is also possible to provide an auxiliary electrical conductor common to the two windings of the same branch. For example, for the 32u branch, a auxiliary electrical conductor is common to the main electrical conductor 14u and the winding 34u.

[0058] [Fig. 15] represents a component 40 that can be implemented in particular as a common mode inductive filter or as a transformer. The component 40 comprises two windings 10 as described previously. The windings are both wound around the same magnetic core 42 which is, in the example shown, closed. It is of course possible to provide more than two windings 10 wound around the same magnetic core. This magnetic core can be closed or open. As an inductive filter, the component 40 is for example adapted to filter the output of a rectifier delivering a DC voltage carried by a positive phase + and a negative phase -. Each phase circulates through the main electrical conductor 14 of each winding 10. The auxiliary electrical conductors 20 of each winding 10 are connected together, for example to the electrical ground 36 possibly by means of a resistive component R.In the absence of an auxiliary electrical conductor, it is common to associate such a common mode filter with external capacitors, one per phase, each connected between the phase considered and an electrical ground of the system in which the filter is integrated. By implementing the invention, it is possible to do without external capacitors or at least to reduce the values.

Claims

Claims

1. Coil configured to ensure the passage of an electric current between two main connection points, the device comprising: - a magnetic core (12; 32; 42), - a main electrical conductor (14; ; 14-1; 14u, 14v, 14w) in the form of a first flat ribbon extending between two ends each equipped with one of the main connection points (14c, 14d), and being wound around the magnetic core (12; 32; 42) to form an inductance, - an auxiliary electrical conductor (20; 20-1; 20-2; 20-3; 20-4; 20-5; 20-6; 20-7; 20-8; 20-9; 20u, 20v, 20w) in the form of a second ribbon wound together with the main electrical conductor, and equipped with an auxiliary connection point (20c), - an electrical insulator (22; 22-1) separating the main electrical conductor from the auxiliary electrical conductor to form a capacitance between the two electrical conductors.

2. Winding according to claim 1, in which the main electrical conductor (14) and the auxiliary electrical conductor (20) are superimposed over their entire length defined along an axis (XX) extending in a plane perpendicular to an axis (16) of the magnetic core (12).

3. Winding according to one of the preceding claims, in which the main electrical conductor (14) and the auxiliary electrical conductor (20; 20-1; 20-2) are partially superimposed.

4. Winding according to one of the preceding claims, in which the auxiliary connection point (20c) is located at one of the ends of the auxiliary electrical conductor (20; 20-1; 20-2), end defined along an axis (XX) extending in a plane perpendicular to an axis (16) of the magnetic core (12).

5. Winding according to one of claims 1 to 3, in which the auxiliary connection point (20c) is located between the ends of the auxiliary electrical conductor (20; 20-1; 20-2), ends defined along an axis (XX) extending in a plane perpendicular to an axis (16) of the magnetic core (12).

6. Winding according to one of the preceding claims, in which the materials of the main electrical conductor (14) and the auxiliary electrical conductor (20) are different.

7. Winding according to one of the preceding claims, in which the auxiliary electrical conductor (20; 20-3, 20-4) is equipped with a second auxiliary connection point (20d; 20-3d; 20-4d).

8. Winding according to the preceding claim, in which the electrical conductors (14, 20-5; 20-6; 20-7; 20-8) extend along a main axis (XX) extending in a plane perpendicular to an axis (16) of the magnetic core (12) and a secondary axis (YY) perpendicular to the main axis (XX) and in which a degree of coverage of the two conductors along the secondary axis (YY) varies along the main axis (XX).

9. A winding according to any preceding claim, wherein the electrical conductors (14-1, 20-9) each have a U-shape, the U-shapes being nested.

10. Transformer comprising at least one winding (10) according to one of the preceding claims forming a primary winding (14u, 14v, 14w) of the transformer and a second main electrical conductor (34u, 34v, 34w) wound around the magnetic core (32) of the electromagnetic winding and forming a secondary of the transformer (30).

11. Component comprising two windings (10) according to one of claims 1 to 9, in which the two windings (10) are wound around the same closed magnetic core (42).

Images