TURBO GENERATOR FOR A HYBRID ELECTRIC AERONAUTIC PROPULSION

Description

Technical Field

[0001] The present invention relates to the field of aeronautical hybrid propulsion and more particularly concerns a turbogenerator whose electrical generator can deliver a plurality of output voltages with distinct power levels. Previous technique

[0002] In a conventional turbogenerator, an electric generator coupled to a heat engine generates total power at a given voltage level. This energy is then converted to the various output voltage levels required by the electrical loads via power electronics, which has the disadvantage of high mass, especially when the voltage conversion ratios are very large, thus requiring the use of multiple conversion stages.

[0003] This power electronics is also an additional link in the chain of efficiency and leads to a degradation of reliability, generating both a need for additional power to compensate for this drop in efficiency, and a need for additional cooling linked to the thermal nature of the associated losses.

[0004] In addition, conventionally the gas generators of aeronautical turbines are equipped with an electric starter that can operate in generator mode when the turbine is started (with a conventional voltage level of 28Vdc), whose efficiency is generally low (around 70-75%) and which also has a relatively high mass (around 1.5kg per kW).

[0005] However, the increasing maturity of hybrid electric propulsion architectures in aeronautics allows the use of electrical receivers that can potentially exploit different power and voltage levels.

[0006] We know from application FR2566975 an electric generator with multiple outputs comprising a common permanent magnet rotor and a stator equipped with a plurality of windings allowing in particular the creation of three distinct but not independent three-phase systems.

[0007] Document FR2618616 shows a multi-rotor and multi-stator motor structure in which the axial dimensions of the rotor and stator are identical.

[0008] In document FR2566975, the illustrated generator allows different output voltages to be obtained with sectorized stators.

[0009] Furthermore, there is now a need to address the technical challenges posed by these new architectures, both in the rationalization of electrical generation and conversion devices and in reducing the size of these electrical generation and conversion devices while improving their efficiency and reliability. Description of the invention

[0010] To address this need, an aeronautical turbogenerator for hybrid electric propulsion is proposed according to independent claim 1, this turbogenerator comprising: a heat engine, an electric generator, mechanically coupled to the heat engine and comprising a rotor and a stator, the rotor extending along an axial direction and comprising a common rotor magnetized yoke comprising a plurality of permanent magnets defining at least three axially distributed movable annular rings, the stator comprising a stator magnetic yoke comprising a plurality of electrical windings defining axially and / or circumferentially distributed fixed sectors, characterized in that at least two fixed sectors, one of which axially covers at least two movable annular rings, are arranged angularly so as not to coincide with each other and thus deliver at least two distinct and independent voltage levels.

[0011] Thus, it is possible to make directly usable polyphase alternating electrical networks available to electrical receivers while increasing reliability, availability of electrical power and reducing bulk.

[0012] Preferably, at least one fixed stator sector has an axially different dimension from another fixed stator sector.

[0013] Advantageously, to a movable annular rotor ring of a determined axial dimension, corresponds a fixed stator sector of a different axial dimension.

[0014] Preferably, a rotating annular rotor ring is associated with both a part of a first fixed stator sector and a part of a second fixed stator sector.

[0015] Advantageously, the fixed stator sectors are separated by a simple air gap or by obstacles forming walls.

[0016] Depending on the embodiment envisaged, the fixed stator sectors are in even number and arranged symmetrically on either side of a longitudinal axis of the electric generator or the fixed stator sectors are arranged asymmetrically with respect to a longitudinal axis of the electric generator.

[0017] Preferably, the heat engine is a gas turbine or an internal combustion engine.

[0018] Advantageously, the rotor has one of the following magnetizations: radial, parallel or Halbach type and the stator has a diametrical or concentric winding. Brief description of the drawings

[0019] Other features and advantages of the present invention will become clearer from the description given below, with reference to the accompanying drawings which illustrate non-limiting examples of its embodiment and on which: [ Fig. 1 ] There figure 1 is a schematic view of an aeronautical turbogenerator, [ Fig. 2 ] There figure 2 represents two half-views in longitudinal section of an aeronautical turbogenerator electric generator according to first and second embodiments of the invention, [ Fig. 3 ] There figure 3 represents two half-views in longitudinal section of an aeronautical turbogenerator electric generator according to the third and fourth embodiments of the invention, [ Fig. 4A-4B ] There figure 4 represents two cross-sectional views of an aeronautical turbogenerator electric generator according to the fifth and sixth embodiments of the invention, [ Fig. 5A-5B ] There figure 6 represents first and second examples of mechanical connection of the windings of the fixed sectors of the stator of the electric generator of the figure 4 , And [ Fig. 6 ] There figure 6 represents a scrolling top view of an aeronautical turbogenerator electric generator according to a seventh embodiment of the invention. Description of the implementation methods

[0020] There figure 1 illustrates schematically an electrical power generation system P for an aircraft comprising an electric generator 10 mechanically coupled to a heat engine 12 via a drive shaft 14 itself connected to a propulsive load 16 of the aircraft.

[0021] In an aircraft, and more specifically in a hybrid-electric aircraft, the heat engine is typically a gas turbine, and the assembly formed by this gas turbine and the electric generator constitutes what is known as an aircraft turbogenerator. In some more specific applications, this heat engine can also be an internal combustion engine, for example, a diesel engine.

[0022] A gas turbine typically comprises a single-stage or multi-stage compressor (axial or centrifugal), one or more combustion chambers, and a single-stage or multi-stage power turbine (radial or centrifugal), which may or may not include a free turbine. When it includes such a free turbine, the free turbine and the electric generator are mounted on the same drive shaft, which is concentric with a high-pressure shaft that supports the compressor and the power turbine. This shaft also supports a starter / generator that starts the gas turbine. When the gas turbine is of the coupled turbine type, the drive shaft is directly connected to the high-pressure shaft. In the following description, the drive shaft 14 may therefore refer interchangeably to either of these two gas turbine configurations or to the output shaft of an internal combustion engine.

[0023] In accordance with the invention and as shown by the figures 2 And 3 The electric generator 10 has a longitudinal axis XX' which defines an axial direction and a perpendicular radial direction. It comprises a permanent magnet rotor formed of a common magnetized yoke 100 and a ring formed of a plurality of alternating polarity permanent magnets 102 distributed around this common rotor magnetized yoke 100 (see the magnifying glass associated with this rotor). The rotor is sectored in the axial direction in that this ring of magnets is arranged in several successive annular rings (only three annular rings are illustrated for the sake of simplicity in the drawings) independent of each other and which can be of identical dimensions, along this axial direction, as shown by the three annular rings 102A, 102B, 102C of the upper part of the figure 2 , or of different dimensions as shown by the three annular rings 102A, 102B, 102C of the lower part of the same figure 2 . This plurality of permanent magnets thus defines axially distributed mobile annular rings.

[0024] This sectorized permanent magnet rotor is surrounded by one or more stator(s). A stator consists of a common stator magnetic yoke 200 and a plurality of windings 202 distributed along this common stator magnetic yoke 200 (see the magnifying glass associated with this stator).

[0025] A stator is configured to deliver, independently of each other, a distinct level of polyphase voltage via an electrical connection 204.

[0026] This stator is also sectored along the axial direction; each axial sector of stator 202A, 202B, 202C can have the same dimensions in this axial direction (see the upper part of the figure 2 ) or not (see the lower part of the figure 2 ), defining axially distributed fixed sectors. The axially distributed fixed sectors of the stator can be of the same size as the axially distributed moving annular rings of the opposite rotor, as shown in the figure 2 , or be of a different dimension as shown by the figure 3 Thus, on the upper part of the figure 3 , three axial annular rotor rings (taken for this example to be of the same dimensions) correspond to two axial stator sectors 202A, 202D and on the lower part of the figure 3 For every three axial rotor annular rings, there is a single or common stator sector 202E that covers all parts of the axial rotor annular rings. More generally, the rotor has at least three movable annular rings and the stator has at least one fixed axial sector covering at least two movable annular rings.

[0027] The magnetization of the rotor magnets 102 can be radial, parallel, Halbach type or any other suitable configuration and the stator winding 202 can be diametrical or concentric type.

[0028] THE figures 4A et 4B illustrate two further embodiments of the invention in which the stator sectoring is no longer axial but circumferential, defining fixed sectors that are at least partially annular, while the rotor sectoring remains axial. On the figure 4A This circumferential sectoring is symmetrical in that the fixed sectors of stators 204A-204F are even in number (six in the illustrated example, which is not exhaustive) and arranged symmetrically on either side of the longitudinal axis XX' of the electric generator. On the figure 4B This circumferential sectoring is asymmetrical in that the fixed stator sectors 206A-206F, which can be even in number (six in the illustrated example), are arranged asymmetrically with respect to the longitudinal axis XX' of the electric generator, that is, without respecting any particular symmetry around the rotor. Each sector is associated with an electrical connection that allows the delivery of a specific polyphase voltage level. The stator assemblies formed by the yoke 200, the windings 202, and the electrical connection 204 are supported by the motor frame 210.

[0029] As schematically shown figures 5A et 5B The mechanical strength of the windings can be ensured by obstacles forming walls 208 or external bolting 209. In this second configuration, the motor casing consists only of an external ring forming a cage 220, the stators being spaced by a simple air gap 230.

[0030] Finally, the figure 6 illustrates a final example of a preferred embodiment in which at least one fixed axial sector of the stator is also sectored in a circumferential direction. Thus, a first stator 240A (endcap, winding and electrical connection) which extends over several axial annular rings of rotor 102A, 102B is followed by a second stator 240B (endcap, winding and electrical connection) which also extends over several axial annular rings of rotor 102B, 102C, an axial annular ring of common rotor 102B being surrounded by a sectored stator to receive both a part of the first stator 240A and a part of the second stator 240B.

[0031] With the invention, at least two fixed sectors are arranged angularly so as not to coincide with each other and to cooperate with at least one movable annular ring to deliver at least two distinct and independent voltage levels.

[0032] It should be noted that all the architectures described above allow the generation of N electrical power outputs with N different polyphase voltage levels using a single turbogenerator. Furthermore, the direct mechanical connection to the shaft of the heat engine allows for high rotational speeds (considered high speed), thus minimizing the mass of the electrical generators. In the case of using a single-seat, linked-turbine gas turbine, it is possible to eliminate the starter-generator.

Claims

1. An turbogenerator for hybrid electric aeronautical propulsion comprising: - a heat engine (12) - an electrical generator (10) mechanically coupled to the heat engine and including a rotor and a stator, the rotor extending in an axial direction and including a common magnetized rotor yoke (100) comprising a plurality of permanent magnets (102) defining at least three axially distributed movable annular rings (102A, 102B, 102C), the stator including a magnetic stator yoke (200) comprising a plurality of electrical windings (202) defining axially (202A, 202B, 202C, 202D, 202E) and / or circumferentially (204A, 204B, 204C, 204D, 204E, 204F; 206A, 206B, 206C, 206D, 206E, 206F) distributed stationary sectors, characterized in that at least two stationary sectors, including one covering axially at least two movable annular rings, are further arranged angularly so as not to coincide with one another and thus deliver at least two distinct and independent voltage levels.

2. The aeronautical turbogenerator according to claim 1, characterized in that at least one stationary sector has axially a dimension that is different from another stationary stator sector.

3. The aeronautical turbogenerator according to claim 1, characterized in that, to a rotor movable annular ring with a determined axial dimension, corresponds a stationary stator sector with a different axial dimension.

4. The aeronautical turbogenerator according to claim 2, characterized in that, to a rotor movable annular ring (102B) is associated both a portion of a first stationary stator sector (240A) and a portion of a second stationary stator sector (240B).

5. The aeronautical turbogenerator according to claim 4, characterized in that the stationary stator sectors are spaced by a simple air gap (230) or by obstacles forming walls (208).

6. The aeronautical turbogenerator according to claim 1, characterized in that the stationary stator sectors are even in number and arranged symmetrically on either side of a longitudinal axis of the electrical generator.

7. The aeronautical turbogenerator according to claim 1, characterized in that the stationary stator sectors are arranged asymmetrically relative to a longitudinal axis of the electrical generator.

8. The aeronautical turbogenerator according to any one of claims 1 to 7, characterized in that the heat engine (12) is a gas turbine or an internal-combustion engine.

9. The aeronautical turbogenerator according to any one of claims 1 to 8, characterized in that the rotor (100, 102) has one of the following magnetizations: radial, parallel or Halbach type.

10. The aeronautical turbogenerator according to any one of claims 1 to 9, characterized in that the stator (200, 202, 204) has a diametrical or concentric winding.