Abstract
An electrotechnical device for an aircraft includes a housing having a surface and a magnetic circuit formed by a stack of laminated sheets and composed of a yoke. The yoke is fixed on the surface of the housing by means of a thermal interface and has a surface. At least one low-frequency coil component is attached to at least part of the surface of the yoke by attachment means.
Claims
1. An electrotechnical device for an aircraft comprising: a housing having a surface, a magnetic circuit formed by a stack of laminated sheets and composed of a yoke, said yoke being attached on the surface of said housing by a thermal interface, said yoke having a surface, and at least one low-frequency coil component, said coil component being attached to at least one portion of the surface of said yoke by attachment means.
2. The electrotechnical device of claim 1, wherein the thermal interface is a thermal paste, and wherein the yoke is glued to the surface of the housing.
3. The electrotechnical device of claim 1, wherein the thermal interface comprises a phase change material.
4. The electrotechnical device according to claim 1, wherein the surface of the housing and/or the surface of the yoke is flat.
5. The electrotechnical device according to claim 1, wherein the surface of the housing and/or the surface of the yoke is concave or convex.
6. The electrotechnical device according to claim 1, further comprising a plurality of low-frequency coil components, said coil components being aligned on at least one portion of the surface of the yoke so as to form a line of coil components, and wherein each end of the line of coil components is attached to the surface of the yoke by the attachment means.
7. The electrotechnical device according to claim 1, further comprising a plurality of low-frequency coil components, wherein each coil component is attached to at least one portion of the surface of the yoke by the attachment means, the attachment means being arranged between each coil component.
8. The electrotechnical device according to claim 1, wherein the or each coil component is insulated from the yoke and its magnetic circuit by an electrically insulating material.
9. The electrotechnical device according to claim 1, wherein the housing and/or the yoke is equipped with cooling means.
10. An aircraft comprising at least one electrotechnical device according to claim 1.
Description
BRIEF DESCRIPTION OF FIGURES
[0072] The invention will be better understood and other details, characteristics and advantages of the present invention will become clearer from the following description made by way of non-limiting example and with reference to the attached drawings, in which:
[0073] FIG. 1 is a very schematic view of the device according to the invention, comprising a coil component, for example of the power transformer type,
[0074] FIG. 2 is a very schematic view of the device according to the invention, comprising coil components, for example of the coil type,
[0075] FIG. 3 is a schematic perspective view of the yoke and the coil-type coil components of the device according to one embodiment of the invention, and in the box A, an enlarged cross-sectional view of a portion of said device,
[0076] FIG. 4 is a schematic view of a configuration comprising the device according to the invention,
[0077] FIGS. 5A and 5B are cross-sectional views of coil components integrated into a yoke according to one embodiment of the invention, without and with an external radial air-gap, respectively,
[0078] FIGS. 6A to 6D are cross-sectional views of coil components integrated into a yoke according to an embodiment of the invention, respectively without air-gaps, with an internal longitudinal air-gap, with external longitudinal air-gaps and with external radial air-gaps,
[0079] FIGS. 7A to 7E are cross-sectional views of coil components integrated into a yoke according to an embodiment of the invention, respectively without air-gap, with a radial external air-gap, with a longitudinal internal air-gap, with radial external air-gaps and with longitudinal external air-gaps,
[0080] FIGS. 8A to 8C are cross-sectional views of coil components integrated into a yoke according to an embodiment of the invention, respectively without air-gaps, with external radial air-gaps and with external longitudinal air-gaps,
[0081] FIGS. 9A to 9C are cross-sectional views of coil components integrated in a yoke according to an embodiment of the invention, respectively without air-gap, with external radial air-gaps and with external longitudinal air-gaps, and
[0082] FIG. 10 is a cross-sectional view of coil components integrated into a yoke according to an embodiment of the invention.
[0083] The elements having the same functions in the different embodiments have the same references in the figures.
DESCRIPTION OF THE EMBODIMENTS
[0084] FIGS. 1 to 3 show electrotechnical devices for aircraft according to the invention.
[0085] A device 10 comprises a housing 12 having a surface S12 and comprising cooling means. In FIGS. 1 and 2, the cooling means are in the form of fins 14 that extend radially from an external surface S14 of the housing 12. The housing 12 can be a casing. The surface S12 of the housing 12 can be flat, as shown in FIGS. 1 and 2, or concave, or convex.
[0086] The device also comprises a magnetic circuit formed by a stack of laminated sheets. The laminated sheets forming the magnetic circuit can be insulated magnetic sheets, by a varnish or by a specific treatment according to the material used, so as to make the laminated magnetic circuit of only one part. The magnetic circuit is therefore cut out of laminated sheets in one portion. There is no assembly of several portions to form the magnetic circuit. This allows to avoid assembly problems and guarantee the electrical parameters of the component. The magnetic circuit can be formed by a stack of laminated iron-silicon, iron-nickel, or iron-cobalt sheets. The thickness of the laminated sheets is chosen according to the envisaged eddy current losses contributing to the efficiency of the component. Note that the modification of the thickness of the magnetic circuit is a factor that allows to adapt the characteristics of the component (inductances, voltages etc.) without changing its definition (sheet metal, conductor section etc.).
[0087] The magnetic circuit consists of a yoke 16 which has a surface S16. The magnetic circuit and the yoke are therefore formed in one part. The yoke 16 is attached to the surface S12 of the housing 12. The surface S16 of the yoke 16 can be flat, as shown in FIGS. 1 to 3, or concave, as shown in FIGS. 5A to 10, or convex.
[0088] A thermal interface 15 is positioned between the yoke 16 and the housing 12, and then the component is attached via flanges positioned on the yoke 16. The thermal interface 15 can be a thermal paste. Thus, the yoke 16 can be glued to the housing 12, and more precisely to the surface S12 of the housing 12. Alternatively, the thermal interface 15 may comprise a phase change material. This advantageously allows a good thermal contact between the yoke and the housing, and thus a good thermal exchange between the yoke and the housing, and thus a better cooling of the device. This also allows to eliminate the need for additional parts to attach the yoke to the housing.
[0089] The yoke 16 has a mechanical strength function and a thermal dissipation function by conduction towards the housing 12. The contact between the yoke 16 and the housing 12 allows to facilitate the thermal dissipation of the Joule effect losses of the device 10.
[0090] Although not shown, the cooling means may comprise orifices made in the yoke 16 and fluid or ventilation means arranged so as to make circulate a fluid or an air flux through these orifices.
[0091] Thus, the device can be cooled by natural convection, or by forced convection with air circulating inside and/or outside the device 10, or by forced convection with a fluid circulating in the housing 12 or in the yoke 16.
[0092] The device 10 also comprises one or more low-frequency coil components 18. The coil components 18 may be of the power transformer type, as shown in FIG. 1, and/or the coil type, as shown in FIGS. 2 and 3. The device 10 may comprise only power transformers, or only coils, or both power transformers and coils. In FIG. 1, the coil component 18 is attached to the entire surface S16 of the yoke 16, while in FIG. 2, the three coil components 18 are attached to only a portion of the surface S16 of the yoke 16. Of course, the device 10 may comprise a different number of coil components 18, which may be arranged differently on the surface S16 of the yoke 16.
[0093] The coil components are attached to at least one portion of the surface S16 of the yoke 16 by attachment means 17. The attachment means 17 are configured to ensure that the coil components 18 are held on the yoke 16 along each axis, i.e., in the direction of the axes defining the surface S16 of the yoke 16 and in the direction radial to the surface S16 of the yoke 16.
[0094] As shown in FIG. 2, the coil components 18 may be aligned on the surface S16 of the yoke 16 so as to form a line of coil components 18. Each end of the line of coil components 18 can be attached to the surface S16 of the yoke 16 by attachment means 17a.
[0095] As shown in FIG. 2, each coil component 18 may also be attached to the surface S16 of the yoke 16 by attachment means 17b arranged between each coil component 18.
[0096] In FIG. 3, the attachment flanges 17a, 17b are in the form of retaining plates screwed to the housing 12.
[0097] Since the yoke 16 is connected to the housing 12 by a thermal interface 15, the attachment means 17 are specified to exert sufficient pressure to ensure the desired thermal resistance.
[0098] In particular, the yoke 16 serves as a structure for the coil components, and allows the holding and the support of their attachment to the housing 12. The yoke advantageously allows the type and the number of coil components to be adapted according to the needs of the device and the integration of the device with its environment.
[0099] The coiling of a coil component 18 may be made of enamelled round wire of copper, aluminium or composite alloy, possibly twisted, or of a flat of copper or aluminium, or of an insulated copper or aluminium foil. The coiling can be made by a copper foil, following a copper annealing process, so as to allow a good cohesion of the coil component. The coiling and/or the magnetic circuit can be impregnated and/or encapsulated.
[0100] The magnetic circuit allows to channel the magnetic flux of the coil components 18.
[0101] The yoke 16 may comprise protrusions 20 extending radially from the surface S16. A protrusion 20 may comprise at least one central tooth 21a surrounded by two outer teeth 21b. Alternatively, a protrusion 20 may comprise only one or a plurality of central teeth 21a, or only two outer teeth 21b. As shown in the box A of FIG. 3, a coil 18 is integrated on a protrusion 20. One or more coils integrated in their magnetic circuit form a coil component. This coil 18 is wound around the central tooth 21a, and is surrounded by the two outer teeth 21b. The central tooth 21a may be connected at its radial end to the outer teeth 21b by a connecting segment 23 that extends longitudinally to the surface S16 of the yoke 16.
[0102] As shown in the box A of FIG. 3, a coil 18 may be insulated from the yoke 16, and thus from its magnetic circuit, by an electrically insulating material 22, such as a Kapton® type material or epoxy resin.
[0103] As shown in the box A of FIG. 3, the protrusion 20 may be provided with radial air-gaps 24. These air-gaps 24 extend in the radial direction to the surface S16 of the yoke 16. These radial air-gaps 24 are arranged on the connecting segment 23 connecting the central tooth 21a and the outer teeth 21b.
[0104] FIG. 4 shows an example of configuration that comprises a device according to the invention. The device comprises six uncoupled coils Lc11, Lc12, Lc13, Lc21, Lc22, and Lc23 that are configured to parallel two inverters 30, 32 to control an electric actuator 34. The coils Lc11-Lc23 are connected to the actuator 34 via a connector 48 and power cables 50a, 50b, 50c. The coils Lc11-Lc23 are interphase coils. These coils are configured to limit the fault current between each same phase of the inverters 30, 32 and to limit over-voltages to the terminals of the electric actuator 34. The coils Lc11-Lc23 in the box B of
[0105] FIG. 4 correspond to the coils 18 in FIG. 3. The inverters 30, 32 can be DC-AC power converters (DC-AC for Direct Current-Alternative Current). The inverters 30, 32 form a power electronics portion 46, which is connected to a control electronic board 36, which forms a control electronic portion. The control electronic board 36 is connected, via a connector 38, to a communication bus 40. The inverters 30, 32 are connected, via a connector 42, to a direct current bus 44. The set of coils Lc11-Lc23, the power electronics 46 and the control electronics 36 form the equipment 52 which is arranged in the yoke 16, and thus in the housing 12, and which can, for example, be easily integrated into a switch cabinet.
[0106] As shown in FIGS. 5A and 5B, the device may comprise two coils 54a, 54b connected in series and having an identical direction of flux. These coils are single-phase components which allow to ensure filtering, smoothing, parallelization or energy transfer functions. The coils 54a, 54b are integrated on a protrusion 20 of the yoke 16. In these figures, the protrusion 20 comprises only two outer teeth 21b, which are connected to each other by a connecting segment 23 at their radial end. Each coil 54a, 54b is wound around an outer tooth 21b. These coils 54a, 54b are not completely surrounded by the protrusion 20. These coils can be made on one or more protrusions 20 of the yoke 16 in order to minimize their height.
[0107] In order to minimize the volume-to-mass ratio of the magnetic circuit and to reduce the dependence on variations in the magnetic properties of the material used to make the magnetic circuit, a radial air-gap 24 can be added, as shown in FIG. 5B. Thus, the protrusion 20 is provided with an air-gap 24 that extends in a direction radial to the surface S16 of the yoke 16. The radial air-gap 24 is arranged on the connecting segment 23 of the outer teeth 21b of the protrusion 20.
[0108] As shown in FIGS. 6A to 6D, the device may comprise an uncoupled coil 56. This coil 56 is integrated into a protrusion 20 of the yoke, and more precisely wound around the central tooth 21a of the protrusion 20. This coil 56 is surrounded by the two outer teeth 21b of the protrusion 20. These outer teeth form return branches on the coil 56. This allows to reduce the EMC problems, and in particular the radiated emissions induced by the leakage fluxes of the coils, which can disturb the electronic boards, sensors and other coil components located in the vicinity. These outer teeth allow to channel a portion of this magnetic flux.
[0109] The magnetic circuit in FIG. 6A comprise no air-gap, while the magnetic circuits in FIGS. 6B to 6D comprise one or more air-gaps 24.
[0110] As shown in FIG. 6B, the longitudinal air-gap 24 may be positioned on the central tooth 21a. This allows to reduce the disturbances between the coil components.
[0111] As shown in FIG. 6C, the longitudinal air-gaps 24 can be positioned on the outer teeth 21b. As shown in FIG. 6D, the radial air-gaps 24 may be positioned on the outer teeth 21b, and more specifically on the connecting segment 23 between the outer teeth 21b. The position of the air-gaps on the outer teeth advantageously allows to facilitate the coiling operation.
[0112] As shown in FIGS. 7A to 7E, the device may comprise two coils 58a, 58b wound so as to be in opposite flux. The coils 58a, 58b are interleaved or coupled. In particular, the components are coupled or common mode interphase inductors that can manage the differential mode in the case of the topologies shown in FIGS. 7C-7E. The coils 58a, 58b are integrated in a protrusion 20 of the yoke 16.
[0113] In FIGS. 7A and 7B, the protrusion 20 comprises only two outer teeth 21b, which are connected to each other by a connecting segment 23 at their radial ends. Each coil 58a, 58b is wound around an outer tooth 21b. These coils 58a, 58b are not completely surrounded by the protrusion 20. As shown in FIG. 7B, a radial air-gap 24 may be positioned on the connecting segment 23 between the outer teeth 21b.
[0114] However, with this topology arrangement, the resulting magnetic flux closes in the air, which can cause induced currents in the surrounding metal elements and disturb electronic boards or coil components nearby.
[0115] In FIG. 7C, the protrusion 20 comprises two outer teeth 21b, which are connected to each other by a connecting segment 23 at their radial ends. As before, each coil 58a, 58b is wound around an outer tooth 21b. These coils 58a, 58b are therefore not completely surrounded by the protrusion 20. An additional tooth, here a central tooth 21a, is added compared to FIGS. 7A and 7B in order to channel this resulting flux and control the leakage inductance of the component. The coils 58a, 58b are separated by the central tooth 21a. The coils 58a, 58b are separated by the central tooth 21a.
[0116] In FIGS. 7D and 7E, the protrusion 20 comprises two central teeth 21a, which are connected to each other by a connecting segment 23 at their radial ends. Each coil 58a, 58b is wound around a central tooth 21a. Additional teeth, in this case two outer teeth 21b, are added with respect to FIGS. 7A and 7B so as to channel this resulting flux and control the leakage inductance of the component. Each coil 58a, 58b is surrounded by an outer tooth 21b and the other coil 58b, 58a. Thus, these coils 58a, 58b are completely surrounded.
[0117] As shown in FIG. 7C, a longitudinal air-gap 24 may be positioned on the central tooth 21a. This allows the magnetic flux to be channelled into the central tooth 21a, which has a high equivalent reluctance compared to the main reluctance, so that the mutual inductance is as high as possible (differential mode management).
[0118] As shown in FIG. 7D, the radial air-gaps 24 may be positioned on the outer teeth 21b, and more specifically on the connecting segment 23 between the outer teeth 21b. As shown in FIG. 7E, the longitudinal air-gaps 24 can be positioned on the outer teeth 21b. This advantageously allows to have an armoured version, by channelling the resulting magnetic flux in the outer teeth 21b.
[0119] A multi-phase free-flux power transformer, or autotransformer, can be formed by a plurality of coils. The coils can be connected according to the adopted configuration (star, triangle, zigzag, etc.) and arranged in series or in parallel according to the needs related in particular to the integration portion. The number of coils depends on the desired function. FIGS. 8A to 8C show an example of an embodiment of a device comprising a multi-phase power transformer formed by three-phase coils 62a, 62b, 63a, 63b, 64a, 64b of the armoured type, the coils being locally integrated on only a portion of the surface S16 of the yoke 16. The coils 62a, 63a, 64a are primary coils and the coils 62b, 63b, 64b are secondary coils. In this example, the transformer is galvanically isolated. In other words, there is no electrical connection between the primary portion and the secondary portion.
[0120] In FIGS. 8A to 8C, the protrusion 20 comprises three central teeth 21a-1, 21a-2, 21a-3 and two outer teeth 21b, which are connected to each other by a connecting segment 23 at their radial ends. The coils 62a-62b are wound around a first tooth 21a-1, while the coils 63a-63b are wound around a second tooth 21a-2 and the coils 64a-64b around a third tooth 21a-3. Specifically, the coils 62a-62b are concentric, with the coil 62b being wound around the coil 62a, which is itself wound around the first tooth 21a-1. Similarly, the coils 63a-63b are concentric, with the coil 63b being wound around the coil 63a, which is itself wound around the second first tooth 21a-2. Similarly, the coils 64a-64b are concentric, with the coil 64b being wound around the coil 64a, which is itself wound around the third tooth 21a-3. The coil 62b is surrounded by an outer tooth 21b-1 and by the second central tooth 21a-2. The coil 64b is surrounded by an outer tooth 21b-2 and the second central tooth 21a-2. Thus, the coils 62a-64b are completely surrounded. In these figures, there are thus two coils integrated around each tooth 21a-1, 21a-2 and 21a-3, one for the primary portion, and one for the secondary portion.
[0121] The magnetic circuit in FIG. 8A comprise no air-gap, while the magnetic circuits in FIGS. 8B and 8C comprise air-gaps 24.
[0122] As shown in FIG. 8B, the radial air-gaps 24 may be positioned on the outer teeth 21b, and more specifically on the connecting segment 23 between the outer teeth 21b. This advantageously allows to increase the magnetic leaks and the self-inductance.
[0123] As shown in FIG. 8C, the longitudinal air-gaps 24 may be positioned on the central teeth 21a-1, 21a-2, 21a-3. This advantageously allows to limit the magnetic flux. When the air-gaps are positioned on the outer teeth, this allows to increase the magnetizing inductances.
[0124] The air-gaps allow to adjust the parameters of the power transformer and to reduce the impact of the material composing the magnetic circuit.
[0125] Depending on the integration constraints, the number of teeth or coils per phase can be increased. Also, the pattern developed on the whole yoke can be modified, connecting each coil of the same phase in series or in parallel to reduce the thickness of the device.
[0126] For example, FIGS. 9A to 9C show FIGS. 8A to 8C, respectively, with a replicate of the transformer on the surface S16 of the yoke 16. The primary coils 62a, 63a, 64a and the secondary coils 62b, 63b, 64b are integrated over the entire circumference of the surface S16 of the yoke 16. This configuration advantageously allows to maximize the central space of the yoke 16.
[0127] A transformer, or a forced-flux multi-phase autotransformer, can be implemented locally on only a portion of the surface S16 of the yoke 16, as shown in FIG. 10. The transformer comprises six coil components 66a, 66b, 68a, 68b, 70a and 70b.
[0128] In FIG. 10, the protrusion 20 comprises a central tooth 21a and two outer teeth 21b. The coils 66a-66b are wound around a first outer tooth 21b, while the coils 68a-68b are wound around the central tooth 21a, and the coils 70a-70b are wound around a second outer tooth 21b. Specifically, the coils 66a-66b are concentric, the coil 66b being wound around the coil 66a. Similarly, the coils 68a-68b are concentric, the coil 68b being wound around the coil 68a; and the coils 70a-70b are concentric, the coil 70b being wound around the coil 70a. The coils 66b and 70b are not completely surrounded.
[0129] The magnetic circuit in FIG. 10 comprises no air-gap. Of course, this magnetic circuit may comprise an air-gap on the protrusion 20, as previously described for FIGS. 8B, 8C, 9B and 9C.
[0130] As before, for integration constraints, the number of teeth or coils per phase can be increased or the pattern developed on the entirety of the yoke can be modified by connecting each coil of the same phase in series or in parallel in order to reduce the thickness of the device.
