Device for supplying electrical power to a de-icing system

Abstract

The invention relates to a device (30) for supplying electrical power to a de-icing system (46), comprising a rotor comprising a ring (32) bearing a plurality of generators (36, G, G1, G2), each generator comprising a pinion (40) comprising a toothing; further comprising a ring gear (34) that is coaxial with the ring and comprises an annular toothing engaged with the toothings of the pinions; further comprising a stator (64) bearing at least one clamping member (42) for rotationally clamping the ring gear; further comprising control means (48) for controlling said at least one clamping member making it possible to control said at least one clamping member between a first position for clamping / blocking the ring gear and a second position for releasing the ring gear.

Description

Description Title: Power supply device for a defrosting system technical field

[0001] This disclosure falls within the field of aircraft de-icing devices and more specifically de-icing devices for aircraft turbomachinery propeller blades. Previous technique

[0002] With reference to Figure 1, a turbomachine is schematically represented, more specifically a twin-flow axial turbojet 10. The illustrated turbojet 10 extends along an X-axis and comprises successively, in the direction of gas flow in the turbomachine, a fan 12, a compression section which may include a low-pressure compressor 14 and a high-pressure compressor 16, a combustion chamber 18, and a turbine section which may include a high-pressure turbine 20, a low-pressure turbine 22, and an exhaust nozzle.

[0003] During various phases of flight, aircraft frequently encounter weather conditions conducive to icing, characterized by a combination of low temperatures and humidity. This accumulation of ice on different aircraft surfaces leads to impaired aerodynamic performance, increased weight, and reduced maneuverability. Ice can form on the aircraft's turbomachinery, particularly on propeller blades such as those found on fan blades. This problem can also occur on the propeller blades of a turboprop engine.

[0004] The presence of ice on one or more blades of a bladed turbine wheel causes a deformation of its profile, resulting in a decrease in the bladed wheel's efficiency and a redistribution of rotating mass around its axis. These changes can generate significant vibrations, potentially leading to failure. Furthermore, if sufficiently large pieces of ice break off in flight, they can be drawn into the turbomachine's air intakes or strike the aircraft structure, causing damage due to the significant kinetic energy they have acquired.

[0005] To mitigate this risk, most turbine blades prone to icing on turbomachinery are equipped with a de-icing system using heated mats, for example made of electrical resistors, which prevent ice formation.

[0006] Figure 2 shows a propeller 24 comprising blades 26. Heating elements 28 are arranged on the blades 20, which allows them to be defrosted. This type of system can be installed on a bladed fan wheel, for example on the fan 12 of Figure 1.

[0007] An electric generator can be installed on the propeller shaft, and current must be transferred to the propeller hub to power the heating mats. This requires supplying electrical power from a fixed point to a moving point, which presents challenges.

[0008] For this purpose, there are three main devices for transferring and / or generating electrical power in a rotating frame of reference.

[0009] The first type is based on a device called a "slip ring." The principle relies on the friction of a fixed part or brush against one or more conductive tracks on the hub, thus transferring power and signals through contact between the brush and the hub tracks. A second type of device uses at least one rotating transformer. In a typical rotating transformer, two electrical windings are mounted on rotating parts of the device. One winding receives electrical power from an external source, while the other is connected to another system or electrical loads. When the primary winding is energized, it creates a magnetic field that induces a voltage in the secondary winding, thus enabling the transfer of electrical power between the two systems.In a third device, at least one generator is used to produce electricity by converting a primary energy source, usually mechanical, into electric current. It typically consists of coils of conductive wire (windings) that rotate within a magnetic field created either by permanent magnets or by electromagnets powered by an electric current. When the coils rotate in the magnetic field, this induces an electric current in the wires, thus generating electricity.

[0010] However, power transfer with a change of reference frame faces the difficulty related to the relative oscillations of the two reference frames, the "fixed" reference frame and the "rotating" reference frame.

[0011] This phenomenon is particularly pronounced due to the forces exerted by the propeller blades and the leverage effect on the bearings, which can lead to mechanical deformation. This difficulty is compounded by larger diameters, as the effects of thermal and centrifugal expansion also come into play.

[0012] This oscillation phenomenon therefore makes it difficult to use known means of transferring power to de-icing devices.

[0013] Indeed, the presence of oscillations makes it difficult for the brushes to slide on a ring in the case of the first device, known as a "slip ring." In the second case, large-diameter rotating transformers do not have their own bearings and their performance is degraded by the need for large air gaps to accommodate the oscillations. Large-diameter bearings can be considered, but they present inherent technical difficulties, such as lubrication problems or differential expansion issues. Regarding the third type of device, large-diameter generators are difficult to manufacture due to thermal and mechanical deformations and also present the problem of large air gaps, which degrade their performance.

[0014] It is observed that the difficulty related to oscillations proves problematic in all current devices. Summary

[0015] To this end, a device is proposed for supplying power to electrical equipment, such as a defrosting system, comprising: A rotor comprising a ring carrying a plurality of generators, each generator comprising a pinion having teeth, A crown gear coaxial with the ring and featuring annular teeth that mesh with the teeth of the pinions, A stator carrying at least one rotating clamping element for the crown, Control means for said at least one clamping element allowing said at least one clamping element to be controlled between a first clamping / locking position of the crown and a second position of releasing the crown.

[0016] Thus, when the clamping element is in the first position, the ring gear is locked against rotation relative to the stator, so that each of the generator pinions is rotated via the teeth on the ring gear's annular teeth. When the clamping element is in the second position, the ring gear is no longer locked against rotation on the stator; the coupling of the ring gear's annular teeth with the generator pinion teeth drives the ring gear in rotation, thus the ring gear is rotationally fixed to the rotor. This configuration therefore results in neither wear nor loss of lubrication when the generators are stopped. Furthermore, it allows for a mechanical disconnect system that frees the generators from driving the rotor.This type of disconnection is useful for safety reasons, particularly when using permanent magnet machines where the rotating voltage cannot be eliminated. For example, in the event of an internal short circuit in generators, to avoid the risks of overheating and fire, one commonly applicable solution is to stop the rotation.

[0017] The proposed configuration incorporates multiple generators distributed around the rotor axis, enabling the generator rotors to rotate at high speeds compared to the rotational speed of the drive shaft, which is intended to be coupled to a propeller. This produces an electrical current, typically alternating current, with high efficiency. Positioning the generators in the rotating frame has the advantage of generating the electrical current directly within the rotating frame, thus eliminating the need for a connection between a fixed and a moving frame.

[0018] Furthermore, designing the lightest possible generator with a large diameter and low power output, with a diameter disproportionate to the power required, results in a hollow machine with a small difference between its outer and inner diameters. This generator would therefore be fragile and susceptible to mechanical stresses from centrifugal forces or deformations due to thermal expansion and the engine environment, such as vibrations. Moreover, the air gap would be large for a generator of this power output because large-diameter bearings are impractical for such a small machine, and the air gap would need to accommodate propeller oscillations. In addition, as a general rule... The necessary mechanical clearance between the rotor and stator depends directly on the diameter due to deformations and manufacturing difficulties. Therefore, the present configuration overcomes the manufacturing difficulties of large-diameter generators by offering multiple generators, each with a reduced diameter and equipped with bearings, instead of a single large generator.

[0019] In embodiments, said at least one rotational clamping member of the ring is connected to the stator by a support system comprising a first linkage allowing a first degree of freedom along a first direction extending along a radial direction of the ring and a second linkage allowing a second degree of freedom along a second direction extending along a direction perpendicular to the radial direction and to an axis of rotation of the rotor, the support system being configured so that the first linkage and the second linkage are active and so that the support system is fixed along the axis of rotation of the rotor when said at least one clamping member is in its first position.

[0020] Thus, according to this configuration, the movement of the clamping element is blocked in the direction coaxial with the rotor's axis of rotation by the support system. The two degrees of freedom allowed by this configuration permit the assembly formed by the clamping element and the ring to eccentric slightly relative to the stator, through a translational movement in the plane perpendicular to the rotor's axis of rotation, that is, along the first and second directions.

[0021] Preferably, the first and second links each allow a travel greater than or equal to the maximum oscillation amplitude of the rotor relative to the stator. This can therefore absorb oscillations of the ring gear without exerting excessive stress on the generator pinions when the clamping element is in the first position, i.e., when the generators are activated.

[0022] This configuration also improves performance compared to current solutions, because the presence of oscillation between fixed and moving reference points requires large air gaps to accommodate the oscillations, which leads to a degradation of energy efficiency.

[0023] According to one aspect, the support system may include an arm whose first end is fixed to the stator by a pivot joint and whose second end cooperates by sliding by form joint, for example via a slide, along the first radial direction with said at least one clamping member to achieve the first degree of freedom, the support system being connected to the stator by an elastic member configured to permit the second degree of freedom along the second direction.

[0024] In a particular configuration, the elastic element alone simultaneously provides both the first and second degrees of freedom. Such a design is simple to implement but places more stress on the gears compared to the previous design.

[0025] Said at least one clamping element may include at least one bracket carrying movable clamping elements arranged on either side of the crown and intended to clamp the crown.

[0026] The caliper may have a U-shaped form with two arms between which an outer portion of the ring is engaged. The caliper may also include movable elements, such as pistons, carried by each arm and displaceable along a direction coaxial with the rotor's axis of rotation. The clamping mechanism's control means move it to the first locking position so that the pistons clamp the ring.

[0027] In a particular embodiment, the stator carries at least three clamping elements, preferably evenly distributed around the axis of the ring. This arrangement allows a clamping force to be applied at several points on the ring and preferably distributed uniformly around its axis.

[0028] The generators can be evenly distributed around the ring axis. In a configuration where the generators are not evenly distributed around the ring axis, a balancing constraint must be respected, for example, by making the center of gravity coincide with the center of rotation. Furthermore, the gears must be arranged so as to ensure good guidance of the ring gear; in other words, there must be a sufficient number of them, and the maximum angular spacing must be less than 180°, for example, a maximum of 120°, preferably a maximum of 30°.

[0029] In some embodiments, the crown teeth can be radially internal teeth.

[0030] In a particular embodiment, at least two generators from the plurality of generators are connected in series in a circuit and are arranged so as to generate electromotive forces in phase.

[0031] To achieve this effect, the internal windings of the generators can be arranged so that all generators produce synchronized electromotive forces. This condition can, for example, be achieved during the insertion of the toothed ring by properly positioning the generator rotors angularly.

[0032] This configuration allows the electromotive forces produced by the generators to be summed by connecting them in series, without requiring an AC voltage rectification step. One possibility would be to rectify the voltages of each generator individually to add DC voltages, but such a configuration would increase the number of rotating components.

[0033] The generator circuit may include a primary terminal and a secondary terminal, with at least one switch arranged in the circuit so that a first terminal is connected to a junction terminal of two successive generators and a second terminal is connected to the primary terminal of the circuit.

[0034] The number and positioning of switches determine the discrete voltage values ​​obtainable at the primary and secondary terminals of the generator circuit. This configuration allows adjustment of the circuit's output voltage by varying the number of generators connected in series. For example, with 10 identical generators connected in series and a switch positioned so that one terminal is connected to a junction terminal of the fourth and fifth generators, and the other terminal is connected to the primary terminal of the circuit, the output voltage would be ten times the individual electromotive force (EMF) of a generator when the switch is open, but four times the individual EMF of a generator when the switch is closed. Adjusting the circuit's output voltage can compensate for voltage variations related to speed.

[0035] In a particular embodiment, the circuit comprises: a first part of the circuit comprising k1 generators and without a switch; a second part of the circuit comprising k2 generators and comprising between 1 and k2 switches arranged each between two consecutive generators and the primary terminal of the circuit.

[0036] In this configuration, when the generators are all identical, the output voltage is at least k1 times the individual electromotive force of a generator plus between 1 and k2 times the individual electromotive force of a generator, depending on the positioning of a closed switch.

[0037] In a particular embodiment, the circuit includes a controllable AC / AC voltage converter inserted in series in the generator circuit and comprising primary and secondary terminals to which the terminals of a generator are connected, the converter being capable of supplying a voltage between zero and a nominal amplitude voltage of the generator.

[0038] Thanks to this variant, it is possible to achieve all intermediate voltage values ​​that were unattainable with the previous version. For example, in the previous version, if the rated amplitude voltage of a generator was 10V and 12 generators were connected in series, the output voltage could vary from 10V to 120V in 10V increments, depending on the switch configuration. By introducing the controllable AC / AC voltage converter, one of the generators could now deliver a voltage between 0 and 10V instead of 10V. Thus, this configuration could allow for any output voltage between 0 and 120V.

[0039] In the event that part of the circuit is without a switch, the converter should preferably be placed in series with generators of that part, in order to be usable regardless of the arrangement and closure of the switches.

[0040] In some embodiments, the generators can be of the permanent magnet synchronous type without brushes.

[0041] This choice makes it possible to avoid having to power the rotating parts with brushes or any other device, such as a transformer or an auxiliary generator.

[0042] This document also relates to a turbomachine assembly comprising a device as described above, in which the rotor has an annular row of blades and a de-icing system carried by the rotor blades.

[0043] This document also relates to a turbomachine, such as a turbojet or a turboprop, which may include said turbomachine assembly. Brief description of the drawings

[0044] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: Fig. 1

[0045] [Fig. 1], already described previously, is a schematic view of a turbomachine along a cross-sectional plane including the longitudinal axis; Fig. 2

[0046] [Fig. 2], already described previously, is a cross-sectional view of a propeller incorporating a de-icing device; Fig. 3

[0047] [Fig. 3] is a schematic perspective view of a power supply device for a defrosting system; Fig. 4

[0048] [Fig. 4] illustrates two perspective views from two different orientations of the device in Figure 3, illustrating more particularly the clamping element; Fig. 5

[0049] [Fig. 5] is a schematic view along the axis of rotation of the rotor of the power supply device, illustrating the support system of the crown clamping element; Fig. 6

[0050] [Fig. 6] illustrates an electrical circuit comprising a plurality of generators; Fig. 7

[0051] [Fig. 7] illustrates a particular realization of the circuit in Figure 7 comprising a plurality of switches; Fig. 8

[0052] [Fig. 8] illustrates the electrical circuit of figure 7 featuring an AC / AC voltage converter. Description of the implementation methods

[0053] Reference is now made to figures 3 to 8 illustrating the power supply device of a blade de-icing system for an annular row of moving blades.

[0054] Figure 3 shows a device 30 for supplying a de-icing system, comprising a ring 32 connected to a rotor with longitudinal axis L. The rotor may be a turbomachine rotor as illustrated with reference to Figure 1 and may include an annular row of movable blades. The ring 32 carries a plurality of generators 36, which in this example are mounted on a radially inner face of the ring. As illustrated, the generators 36 are regularly distributed around the longitudinal axis L of the ring 32. The generators 36 could be non-regularly distributed, for example, to facilitate integration into an engine environment and to take into account a space constraint. Each generator 36 includes a housing 38 containing a shaft, guided in rotation by bearings, one free end of which, projecting from the housing 38, carries a gear 40 having teeth.The teeth of the pinions 40 can thus together form an annular row of teeth. Furthermore, the generators 36 can be of the brushless permanent magnet synchronous type.

[0055] The device 30 also includes a ring 34 coaxial with the ring 32, having teeth formed on a radially internal cylindrical face. The teeth of the ring 34 mesh with the teeth of the generators 36, as can be seen in Figures 3 and 4, and more particularly in Figure 5. It can be observed that the ring may include a plurality of orifices or openings running longitudinally through the ring; these openings allow for a reduction in the mass of the ring 34 and improve heat dissipation.

[0056] In other embodiments, the teeth of the ring gear 34 could be radially external, so that the ring gear 34 would be arranged radially inside the pinions 40 for rotational coupling with their teeth. In one variant, the plurality of generators 36 could be mounted on a radially external face of the ring 32.

[0057] In another embodiment, the pinions 40 of the generators 36 could not be protruding, and the teeth of the pinions 40 would not be engaged directly with the ring 34 but with an element attached to the ring 34, having teeth and offset at the level of the teeth of the pinions 40.

[0058] In yet another embodiment, the generators 36 could be arranged in pairs, coaxially with the teeth opposite each other with respect to a plane perpendicular to the axis L. The crown 34 could then comprise two annular teeth, a first tooth to cooperate with a first generator of each pair and a second tooth to cooperate with a second generator of each pair.

[0059] The device 30 further comprises at least one clamping member 42 for rotation of the ring 34, which is carried by a stator. In the particular case illustrated in Figure 3, the device comprises three clamping members 42 evenly distributed around the longitudinal axis L. As will be described with reference to Figure 5, each clamping member 42 can be connected to the stator by a support system 50 allowing two degrees of freedom in the plane perpendicular to the axis L of rotation of the rotor. In other cases, the stator could carry a different number of clamping elements 42, which could be arranged differently around the longitudinal axis L, in particular to meet a space constraint.

[0060] The device 30 also includes control means 48 for the clamping elements 42, allowing the clamping elements 42 to be controlled between a first clamping / locking position of the crown 34 and a second position of releasing the crown 34.

[0061] When the control means 48 lock the ring gear 34 onto the stator, the ring gear is fixed relative to the rotor. The teeth of the generator pinions 40 36, which mesh with the teeth of the ring gear 34, then begin to rotate, thus generating electricity. In the case of a brushless permanent magnet synchronous generator, the no-load voltage can be proportional to the rotational speed of the generator shaft. When the control means 48 release the ring gear 34, its annular teeth achieve a rotational coupling between the ring gear 34 and the rotor ring 32 via the teeth of the generator pinions 40 36. In this position, the generator shafts 36 do not rotate, and the generators 36 do not generate electricity.

[0062] An output 44 of the generator circuit, which may be similar to circuits 68, 76, and 80 described later with reference to Figures 6 to 8, can be connected to a defrosting system 46 carried by an annular row of blades. The defrosting system 46 may include a plurality of heating elements arranged on the blades or within the blades of the annular row of blades. In particular, each blade may include one heating element.

[0063] With reference to Figure 4, the clamping member 42 may include a yoke 43. The yoke may be U-shaped with two arms that may be substantially parallel, between which a radially external portion of the ring 34 is engaged. The yoke 43 may also include movable clamping elements arranged on either side of the ring 34 and designed to longitudinally clamp the ring 34 on opposite faces. The movable clamping elements may be pistons, for example, pistons connected to a hydraulic circuit. The hydraulic circuit could be the turbomachine's oil circuit.

[0064] With reference to Figure 5 and as previously mentioned, a clamping member 42 can be connected to the stator by a support system 50 comprising a first linkage 52 allowing a first degree of freedom along a first direction D1 extending radially from the ring. The support system 50 also includes a second linkage 56, allowing a second degree of freedom along a second direction D2 extending perpendicularly to the radial direction and to an axis of rotation of the rotor. The support system 50 can be configured so that the first linkage 52 and the second linkage 56 are active and so that the support system 50 is fixed along the axis of rotation of the rotor when the clamping member 42 is in its first position. When the links are active, they can each allow a travel greater than or equal to a maximum oscillation amplitude of the rotor relative to the stator.

[0065] In this example, the support system 50 comprises an arm 66, one end of which is fixed to the stator 64 by a pivot joint, and the other end of which slides by means of a form joint via the first joint 52 along the first direction D1 with the clamping member 42 to achieve the first degree of freedom. The arm comprises a first part in the form of a rod 60, one end 60a of which coincides with the end of the arm 66 and is fixed to the stator by the pivot joint, and the other end 60b of which is connected to a second part 62 having an elongated housing along the first direction D1. The clamping member 42, more particularly the bracket 43, comprises a finger extending along the longitudinal axis. This finger is engaged in the housing of the second part of the arm 66.The arm 66 could comprise two second parts 62 arranged on either side of the clamping member 42, each cooperating with a finger oriented along the longitudinal axis. The fit between the finger and the circumference of the housing is such that it allows a sliding connection between these two elements.

[0066] In some embodiments, and for example as illustrated in Figure 5, the support system 50 can be connected to the stator by an elastic element 56, for example a spring, configured to allow the second degree of freedom along the second direction D2. The elastic element 56, which can be a spring, can thus be connected at its ends to the stator and a central part of the latter can be connected to the arm 66 and more particularly to the first rod-shaped part 60.

[0067] Referring to Figure 6, generators G, which may be the generators 36 described previously, can be connected in series in a circuit 68. The circuit 68 of generators G may include a primary terminal 72 and a secondary terminal 74, and the output voltage 70 of the circuit 68 can be measured at these terminals. Furthermore, the generators G can be arranged to generate electromotive forces in phase. In this case, the output voltage 70 of the circuit 68 corresponds to the sum of the voltages delivered individually by the generators. For example, in the case of n identical generators each delivering 10 V, the output voltage 70 of the circuit 68 would be n times 10 V.

[0068] In the example in Figure 7, the circuit 76 includes switches Z arranged in the circuit such that one terminal is connected to a junction terminal 78 of two successive generators and a second terminal is connected to the primary terminal 72 of the circuit 76. In this example, the circuit 76 has a first circuit segment P1 with k1 generators G1 and no switches, and a second circuit segment P2 with k2 generators G2 and k2 switches Z, which are arranged such that one terminal of each switch is connected to a junction terminal 78 of two successive generators and a second terminal is connected to the primary terminal 72 of the circuit 76. More specifically, only one first terminal of a single switch is connected to a junction terminal 78 of two successive generators, and the second terminals are all connected together to the primary terminal 72 of the circuit. 76.

[0069] In other embodiments, the circuit 76 may include a number of switches between 1 and k2.

[0070] This configuration allows the output voltage of the circuit to be adjusted by changing the number of generators connected in series. For example, if the k1+k2 generators G1, G2 are identical and deliver a voltage of U Volts, the output voltage of the circuit would be (k1+k2)*UV if only switch Zk2 was closed, (k1+k2-1)*UV if only switch Zk2-i was closed, and (k1 + 1)*UV if only switch Zi was closed.

[0071] As shown in Figure 8, the circuit 80, similar to the circuit 76, may also include a controllable AC / AC voltage converter 82, for example, of the power thyristor type, inserted in series in the circuit 80, for example such that an input terminal a3 of the converter 82 is connected to a terminal of a generator GI2 and an output terminal a4 of the converter 82 is connected to the secondary terminal 74 of the circuit 80. The converter 82 further includes primary terminals a1 and secondary terminals a2 to which terminals b1 and b2 of a generator G1i are connected, respectively. The converter may be capable of supplying a voltage between zero and the rated amplitude voltage of said generator G1i.In other cases, the converter can be inserted in series between two successive generators G1, G2, but preferably between generators of the first part of circuit P1 in order to be usable regardless of the arrangement of switches Z.

Claims

Demands

1. Device (30) for supplying power to electrical equipment, such as a defrosting system (46), comprising: A rotor comprising a ring (32) carrying a plurality of generators (36, G, G1, G2), each generator (36, G, G1, G2) comprising a pinion (40) having teeth, A crown (34) coaxial with the ring (32) and comprising annular teeth engaging with the teeth of the pinions (40), A stator (64) carrying at least one clamping element (42) for rotation of the crown (34), Control means (48) of said at least one clamping member (42) allowing said at least one clamping member (42) to be controlled between a first clamping / locking position of the crown and a second releasing position of the crown (34).

2. Device according to claim 1, wherein said at least one rotating clamping member (42) of the ring (34) is connected to the stator by a support system (50) comprising a first linkage (52) allowing a first degree of freedom along a first direction (D1) extending along a radial direction of the ring (34) and a second linkage (56) allowing a second degree of freedom along a second direction (D2) extending along a direction perpendicular to the radial direction and to an axis of rotation of the rotor, the support system (50) being configured such that the first linkage (52) and the second linkage are active and such that the support system (50) is fixed along the axis of rotation of the rotor when said at least one clamping member (42) is in its first position.

3. Device according to claim 2, wherein said first and second links (52, 56) each allow a travel greater than or equal to a maximum oscillation amplitude of the rotor relative to the stator (64).

4. Device according to claim 2 or 3, wherein the support system (50) comprises an arm (66) having a first end fixed to the stator (64) by a pivot joint and a second end cooperating by sliding by form joint along the first radial direction (D1) with said at least one clamping member (42) to achieve the first degree of freedom, the support system (50) being connected to the stator (64) by an elastic member (56) configured to permit the second degree of freedom along the second direction (D2).

5. Device according to any one of claims 1 to 4, wherein said at least one clamping member (42) comprises at least one bracket (43) carrying movable clamping elements arranged on either side of the ring (34) and intended to clamp the ring (34).

6. Device according to any one of claims 1 to 5, wherein the stator (64) carries at least three clamping members (42), preferably regularly distributed around the axis of the ring (34).

7. Device according to any one of claims 1 to 6, wherein the generators (36, G, G1, G2) are regularly distributed around the axis of the ring (32).

8. Device according to any one of claims 1 to 7, wherein the crown teeth (34) are radially internal teeth.

9. Device according to any one of claims 1 to 8, wherein at least two generators (36, G, G1, G2) of the plurality of generators (36, G, G1, G2) are mounted in series in a circuit (68, 76, 80) and are arranged so as to generate electromotive forces in phase.

10. Device according to claim 9, wherein the circuit (68, 76, 80) of generators (36, G, G1, G2) comprises a primary terminal (72) and a secondary terminal (74), at least one switch (Z) being arranged in the circuit (68, 76, 80) such that a first terminal is connected to a junction terminal (78) of two successive generators (36, G, G1, G2) and a second terminal is connected to the primary terminal of the circuit (68, 76, 80).

11. Device according to claim 10, comprising: a first part (P1) of circuit (68, 76, 80) comprising k1 generators (36, G, G1, G2) and without switch (Z) a second part (P2) of circuit (68, 76, 80) comprising k2 generators (36, G, G1, G2) and comprising between 1 and k2 switches (Z) each arranged between two consecutive generators (36, G, G1, G2) and the primary terminal (72) of the circuit (68, 76, 80).

12. Device according to claim 10 or 11, comprising a controllable AC / AC voltage converter (82) inserted in series in the generator circuit (68, 76, 80) (36, G, G1, G2) and comprising primary and secondary terminals to which the terminals of a generator (G1) are connected, the converter (82) being capable of supplying a voltage between zero and a nominal amplitude voltage of the generator (G1).

13. Device according to any one of claims 1 to 12, wherein the generators (36, G, G1, G2) are of the brushless permanent magnet synchronous type.

14. Turbomachine assembly comprising a device according to any one of claims 1 to 13, wherein the rotor has an annular row of blades and a de-icing system (46) carried by the rotor blades.

15. Turbomachine, such as a turbojet or turboprop, comprising an assembly according to claim 14 or a device according to any one of claims 1 to 13.

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