Rotary transformer having a large-diameter segmented radial air gap
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN ELECTRICAL & POWER
- Filing Date
- 2024-06-17
- Publication Date
- 2026-05-06
AI Technical Summary
Existing power transfer solutions for aircraft turbomachines, such as slip rings, have limited lifespan due to friction wear, leading to high operating costs and integration challenges in severe environments, particularly for large diameter rotation shafts.
A large diameter segmented radial air gap rotating transformer with external and internal annular stator and rotor sectors, utilizing electromagnetic induction for contactless power transfer, facilitating maintenance and industrialization with standard magnetic circuit shapes and interchangeable sectors.
Enhances reliability and lifespan, reduces operating costs, and improves accessibility for integration, enabling efficient electrical defrosting of aircraft turbomachine components.
Smart Images
Figure FR2024050789_02012025_PF_FP_ABST
Abstract
Description
[0001] Large diameter segmented radial air gap rotating transformer
[0002] Technical Field
[0003] The present invention relates to the field of power transfer between a fixed reference point and a rotating reference point for the electrical (electrothermal) de-icing of the propeller blades of an aircraft turbomachine and relates to a single-phase rotating transformer used in a harsh environment for the contactless transmission of electrical energy by electromagnetic induction between first and second electrical windings of this transformer.
[0004] Prior art
[0005] On electric or hybrid aircraft, as on conventional aircraft, there are several surfaces to protect against frost on the fixed and rotating parts of the turbomachine. The protection envisaged for the rotating parts is generally exclusively electrothermal based on electric heating mats formed of layers of resistance covering the surfaces to be protected.
[0006] To ensure the transfer of power and therefore convey the electrical energy from the fixed part to the rotating part where the electric heating mats are installed, it is known to use a device called a "slip ring" whose principle consists of rubbing several fixed conductive rings secured to the fixed part on circular conductive tracks secured to the rotating part, in order to create an electrical connection between the fixed part and the rotating part of the turbomachine. However, the major drawback of this solution lies in its very limited service life due to the wear of the parts in continuous friction, which therefore generates unacceptable operating costs on a single-aisle commercial aircraft of the A320 or B737 type where the rotating part endures multiple rotations.
[0007] Furthermore, it is known that due to the harsh environment (thermal, electromagnetic and vibration) existing in hybrid aircraft with numerous electrified engine loads, the integration of electrical equipment is a major challenge and must meet multiple constraints linked both to accessibility for assembly / disassembly and to the routing of power cables with large bending radii and services such as cooling.
[0008] There is therefore a current need for a reliable and long-life solution for transferring power from a fixed reference to a rotating reference applicable to large diameter rotating shafts and respecting the constraints of under-wing line replaceable equipment (LRU: Line Replaceable Unit).
[0009] Statement of the invention
[0010] The main purpose of the present invention is therefore a large diameter rotating transformer, segmented into quarters, whose maintenance is facilitated and does not interfere with the other systems and modules of the aircraft turbomachine, despite its installation in a confined, constrained and difficult-to-access area. Another purpose is to propose a transformer whose topology facilitates "original assembly" by axially inserting the transformer into the engine in a single operation. Another purpose is to propose a transformer suitable for transfer in resonant or non-resonant mode with simplified but robust control. Yet another purpose is to allow industrialization of this rotating transformer at a lower cost, while limiting material waste during manufacturing.
[0011] These aims are achieved by a rotating transformer intended to be installed around a rotating movable shaft, the rotating transformer being made up of a plurality of external annular stator sectors and a plurality of internal annular rotor sectors, the juxtaposition over 360° of these external annular stator and internal rotor sectors forming an external stator ring and an internal rotor ring made up of a set of elementary stator and rotor magnetic circuits, each of the elementary stator magnetic circuits comprising an external magnetic core and a first electrical winding and each of the elementary rotor magnetic circuits comprising an internal magnetic core and a second electrical winding to allow a transfer of electrical energy by electromagnetic induction between the external stator and internal rotor rings,characterized in that the internal and external magnetic cores are mounted axially and separated by a radial air gap, the external and internal magnetic cores each having a C or I shape and in that the external magnetic cores and / or the internal magnetic cores have at each of the air gaps annular expansions produced by cutting into adjacent sectors a circular magnetic ring formed from an axial stack of circular sheets.,
[0012] Thus, with this contactless power transfer, an improvement in the reliability, the lifetime and consequently the operating cost of the transformer can be obtained. In addition, better accessibility to the transformer is possible, facilitating its integration into the systems and modules of the aircraft turbomachine. Use of standard magnetic circuit shapes facilitates industrialization. Such a rotating transformer is advantageously used for the electrical de-icing of the propeller blades and the nose cone of an aircraft turbomachine.
[0013] Preferably, the C-shaped or I-shaped internal and external magnetic cores are formed from a radial stack of flat sheets of a magnetic material of the amorphous or nanocrystalline type or FeNi, a block of magnetic powder made of amorphous powder or other material or an axial stack of wound sheets of FeNi or another material such as FeSi or FeCo and the annular expansions are formed from an axial stack of circular sheets of FeNi or another material such as FeSi or FeCo.
[0014] Advantageously, the circular magnetic ring has notches in the form of crenellations to facilitate its assembly by fitting with the C-shaped or I-shaped magnetic elements. Preferably, the external or internal C-shaped or I-shaped magnetic cores are produced by cutting into two identical parts a standard oblong-shaped magnetic element consisting of a radial stack of wound sheets or an axial stack of flat sheets.
[0015] Advantageously, the number of external magnetic cores per external annular sector of stator is or is not identical to the number of internal magnetic cores per internal annular sector of rotor.
[0016] Preferably, the winding on the stator as on the rotor which can be wire or ribbon is either a concentric winding around each external magnetic core for the stator and internal for the rotor or a single winding surrounding all the external magnetic cores for the stator and internal for the rotor of a given annular sector.
[0017] Advantageously, the external annular stator sectors are identical and interchangeable with each other and / or the internal annular rotor sectors are identical and interchangeable with each other.
[0018] According to the embodiment considered, the external annular stator sectors are electrically interconnected with each other by flexible interconnection parts accessible for assembly / disassembly through circumferential access hatches and the internal annular rotor sectors are electrically interconnected with each other by flexible interconnection parts accessible for assembly / disassembly through circumferential access hatches.
[0019] Depending on the transformer integration mode, the stator and rotor can be reversed: the stator can be formed of internal annular sectors as the rotor can be formed of external annular sectors.
[0020] Brief description of the drawings Other characteristics and advantages of the present invention will emerge more clearly from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not in any limiting nature and in which:
[0021] [Fig. 1] Figure 1 illustrates a part of an aircraft turbomachine incorporating a rotating transformer according to the invention,
[0022] [Fig. 2] Figure 2 shows a section of the rotating transformer of Figure 1,
[0023] [Fig. 3A-3B] Figures 3A and 3B show an exemplary embodiment of an external stator magnetic core making up the rotating transformer district of Figure 2,
[0024] [Fig. 4A-4B] Figures 4A and 4B show two examples of a segment of the stator quarter composing the rotating transformer quarter of Figure 2,
[0025] [Fig. 5] Figure 5 illustrates another example of embodiment of a part of a rotating transformer according to the invention,
[0026] [Fig. 6] Figure 6 illustrates a first example of a rotating transformer district segment according to the invention, and
[0027] [Fig. 7] Figure 7 illustrates a second example of a rotating transformer district segment according to the invention.
[0028] Description of the embodiments
[0029] The principle of the invention implemented is based on a segmentation of the rotating transformer, at the stator (called primary) as at the rotor (called secondary), into several annular sectors or quarters each having a mass and a replacement time compatible with a ground maintenance operation limiting the downtime of the aircraft, so that the maintenance and replacement interventions (assembly / disassembly) are facilitated and can be carried out by conventional tools through dedicated access hatches, without having to disassemble or interfere with the other parts of the aircraft turbomachine. To do this, the annular stator sectors are identical and interchangeable with each other and the annular rotor sectors are identical and interchangeable with each other.
[0030] Power transfer between the stator and the rotor is done by electromagnetic induction and without contact. The stator is powered by dedicated electronics (single-phase resonant (soft switching) or non-resonant (hard switching) or full-wave inverter) operating at high frequencies (several tens of kilohertz) or at low frequencies.
[0031] As shown in Figure 1 which is a part of an aircraft turbomachine, the rotating transformer 10 according to the invention is mounted between a rotating transmission shaft 12 forming a rotating part of the turbomachine and a casing 14 forming a fixed part of the turbomachine, provided with circumferential access hatches 14A through which each of the annular quarters or sectors of the rotating transformer 10 can be installed or easily removed for repair or maintenance and then reinstalled once these replacement operations have been carried out.
[0032] Figure 2 illustrates more precisely an example of an annular sector or quarter 20 of the rotating transformer 10 (which in the illustrated example comprises a single path but two axially offset redundant paths would also be possible) consisting of a fixed stator quarter 22 secured to the casing and a rotating rotor quarter 24 secured to the transmission shaft, the rotor quarter being mounted axially in the stator quarter to form the transformer quarter while maintaining a radial air gap e between stator and rotor. The rotating transformer formed by the juxtaposition over 360° of several quarters 20 has a large diameter, of the order of a meter or more, which allows the rotor to receive a transmission shaft also of large diameter, such as a propeller shaft.
[0033] According to the invention, the 360° juxtaposition of these different annular sectors to the stator and the rotor form an outer stator ring and an inner rotor ring consisting of a plurality of single-phase elementary stator and rotor magnetic circuits respectively comprising a stator magnetic core 30 and a first electrical winding (primary 32) and a rotor magnetic core 34 and a second electrical winding (secondary 36), the stator and rotor magnetic cores being separated by the radial air gap e. The stator (or rotor) windings at a sector are interconnected in series. Similarly, the stator (or rotor) sectors are also interconnected in series to form the primary winding of the complete single-phase transformer (or secondary). Other connection methods for the primary and secondary windings are possible to optimize transfer performance.For example, in the case of N sectors (N being an even number), the person skilled in the art may envisage, without demonstrating inventive activity, connecting the N / 2 sectors connected in series in two parallel branches.
[0034] As previously indicated, both in the stator and in the rotor, the annular sectors are identical and interchangeable with each other. However, the number of these elementary magnetic circuits per annular sector is not necessarily identical in the stator and in the rotor, the choice of the number of magnetic circuits in the stator and in the rotor being guided by design considerations and optimization of transfer performance.
[0035] An annular sector at the stator or rotor is designed as a removable and replaceable LRU (Line Replaceable Unit) under the wing through dedicated circumferential access hatches 14A. They are electrically interconnected by flexible interconnection parts also accessible for assembly / disassembly through the circumferential access hatches 14A. It is important to note that these electrical interconnection parts for both the stator and the rotor must be flexible (braid type or equivalent) and not mechanically structural to limit (or even avoid) the transmission of mechanical forces between adjacent sectors.
[0036] The type of material used for the magnetic core may or may not be different for the stator and rotor (for example, a stack of FeNi wound laminations for the stator and a powder block for the rotor). However, a magnetic core made of amorphous or nanocrystalline wound laminations or in the form of a powder block of any other suitable magnetic material (for example, amorphous powder) is preferably considered. The use of amorphous or nanocrystalline materials, which are particularly suitable for high frequency, makes it possible to reduce the size and mass of the transformer as well as its losses.
[0037] Different topologies are possible for each elementary magnetic circuit in the stator and rotor allowing the production of the rotating transformer according to the invention. These topologies all have in common the fact that the stator magnetic cores (or external stator 30) and / or the rotor magnetic cores (or internal rotor 34) have at their two ends expansions 30A, 30B; 34A, 34B produced economically with standard magnetic shapes without wasting materials during cutting. The expansions are intended to avoid a discontinuity of the magnetic field lines during rotation, thereby improving the transfer efficiency and simplifying the management of the resonant or non-resonant mode by simplified control independent of the rotation (no variation of the magnetic parameters of the transformer as a function of the angular position).
[0038] Thus, and as shown in Figures 3A and 3B, the magnetic core 30 of the stator and the magnetic core 34 of the rotor are each obtained from an assembly of two elements: a standard magnetic element 40 in the shape of a C or U (better known by the acronym C-core) preferably resulting from a cutting of a radial stack of wound sheets 42, and an annular expansion 44 resulting from the cutting of a magnetic circular ring 46 made of an axial stack of circular sheets predefined to the correct diameter. The circular ring is cut into a determined number of annular sectors intended to constitute the complete transformer. To improve the mechanical robustness of the assembly and facilitate the fitting of the C-cores into the expansions, the rings are advantageously cut to create notches 44A in the shape of crenellations.
[0039] Figure 4A shows the assembly obtained with a radial stack of wound sheets on the stator and an axial stack of circular sheets cut on the rotor. Figure 4B illustrates a variant with an axial stack of flat sheets on the stator and an axial stack of circular sheets cut on the rotor. In these two illustrated variants, which are not limiting, the expansions are devoid of notches.
[0040] As illustrated in these figures 4A and 4B, the winding 32 at the stator 30 is a concentric winding around each C-core of the stator. Similarly, the winding 36 at the rotor 34 is a concentric winding around each C-core of the rotor. The windings can be wire or ribbon depending on the different integration and performance constraints to be met.
[0041] Preferably, the stator windings at the level of an annular sector are interconnected in series. The annular sectors are also interconnected in series to form the primary winding of the complete transformer. The same principle of interconnection between sectors and within each sector is implemented for the rotor. However, other modes of interconnection are possible, as previously specified.
[0042] The magnetic core of the stator 30, like that of the rotor 34, comprises annular expansions 30A, 30B; 34A, 34B at each of their two ends, but a configuration without expansion at the stator or at the rotor (but not at both, stator and rotor) is also possible, as will be shown further with reference to figures 6 and 7. The stator and rotor expansions (which do not comprise notches in the two examples illustrated) are separated by the radial air gap e.
[0043] In the embodiment illustrated in Figure 5, the magnetic cores at the stator and rotor are made by assembling an I-shaped magnetic element (or I-Core 50, 52) and an annular expansion 54A, 54B; 56A, 56B mounted at each of the two opposite ends of these two magnetic elements, each forming a bridge between two expansions. The stator and rotor annular expansions are each separated by the radial air gap e. The stator windings 58, 60 or at the rotor can each be wound around a single magnetic element (a single I-Core bridge) or around several as illustrated (for example, one per transformer quarter or sector).
[0044] All parts are assembled and held together by suitable mechanical parts (not shown).
[0045] Figure 6 illustrates a first example of a segment (a part comprising four stator magnetic cores) of a transformer district in which only the magnetic cores of the stator 30 comprise at each of their two ends annular expansions 30A, 30B, the radial air gap e being located between these annular expansions at the stator and the two ends of the magnetic cores of the rotor 34. The windings at the stator as at the rotor are concentric windings 32, 36 around each C-core type element.
[0046] Figure 7 illustrates a second example of a segment (a part comprising four stator magnetic cores) of a transformer district in which only the magnetic cores of the rotor 34 comprise at each of their two ends annular expansions 34A, 34B, the radial air gap e then being located between these annular expansions of the rotor and the two ends of the magnetic cores of the stator 30. The windings on the stator as on the rotor are here also concentric windings 32, 36 around each C-core element.
[0047] Of course, the two above-mentioned examples can be implemented with I-core stator elements as illustrated in Figure 5 instead of C-Core. It can be noted that if in the previous examples, the windings on the stator as on the rotor around each C-Core independently, it is however possible to form a single winding surrounding all the C-core elements of a given annular sector of transformer both on the stator and on the rotor.
[0048] It should be noted that if the transformer integration zone is accessible and allows dismantling of a complete ring on the stator as well as on the rotor, a single 360° winding could also be considered on the stator as well as on the rotor.
[0049] While reference has been made as an application to the de-icing of propeller blades and the nose cone of an aircraft turbomachine, other possible applications, particularly in the aeronautical industry, which can benefit from the use of rotating transformers include the feedback of information from torque sensors for variable blade setting in aircraft and propeller pitch setting in helicopters, for example. For such applications, the elimination of the conventional rubbing brush commutator and its replacement with a rotating transformer is advantageous because it makes the equipment more reliable by eliminating the risk of breakdown created by frequent wear of the brushes.
[0050] Thus, the invention presents in particular the following advantages:
[0051] . facilitation of original equipment operations, . improvement of the reliability and lifespan of the defrosting system through a contactless transfer solution,
[0052] . reduced system operating costs through improved reliability and accessibility (improved equipment replacement time),
[0053] . easy integration of the defrosting system on the turbomachine.
Claims
Claims
1. A rotating transformer (10) with a radial air gap intended to be installed around a rotating movable shaft (12), the rotating transformer consisting of a plurality of external annular stator sectors (22) and a plurality of internal annular rotor sectors (24), the juxtaposition over 360° of these external annular stator and internal rotor sectors forming an external stator ring and an internal rotor ring consisting of elementary stator and rotor magnetic circuits, the internal annular rotor sectors being mounted axially in the external annular stator sectors, each of the elementary stator magnetic circuits comprising an external magnetic core (30, 50) and a first electrical winding (32, 58) and each of the elementary rotor magnetic circuits comprising an internal magnetic core (34, 52) and a second electrical winding (36,60) to allow a transfer of electrical energy by electromagnetic induction between the outer stator and inner rotor rings, characterized in that the inner (34, 52) and outer (30, 50) magnetic cores, each having a C, U or I shape, are mounted axially and separated by a radial air gap (e), the outer magnetic cores and / or the inner magnetic cores having at each of their two ends annular expansions (30A, 30B; 34A, 34B; 54A, 54B; 56A, 56B) which are sectors of a circular magnetic ring (46) cut out and formed from an axial stack of circular sheets.,
2. A rotating transformer according to claim 1, wherein the C-shaped or I-shaped inner and outer magnetic cores (30, 34; 50, 52) are formed from a radial stack of wound sheets of a magnetic material of amorphous or nanocrystalline type, an axial stack of flat sheets or a block of magnetic powder. made of amorphous powder and the annular expansions are formed from an axial stack of circular sheets of FeNi, FeSi or FeCo.
3. A rotating transformer according to claim 1 or claim 2, wherein the annular expansions are sectors of a cut-out circular magnetic ring, formed from an axial stack of circular sheets and comprising notches (44A) in the form of crenellations.
4. A rotating transformer according to any one of claims 1 to 3, wherein the C-shaped or I-shaped external or internal magnetic cores are two identical parts of a standard oblong-shaped cut-out magnetic element (42) consisting of a radial stack of wound laminations or an axial stack of flat laminations.
5. A rotating transformer according to any one of claims 1 to 4, wherein the number of external magnetic cores per external stator annular sector is or is not the same as the number of internal magnetic cores per internal rotor annular sector.
6. Rotating transformer according to any one of claims 1 to 5, in which the winding on the stator as on the rotor which can be wire or in ribbons is either a concentric winding around each external or internal magnetic core or a single winding surrounding all the external or internal magnetic cores of a given annular sector.
7. A rotating transformer according to any one of claims 1 to 6, wherein the outer stator annular sectors are identical and interchangeable with each other and / or the inner rotor annular sectors are identical and interchangeable with each other.
8. A rotating transformer according to any one of claims 1 to 7, wherein the outer annular stator sectors are electrically interconnected with each other by parts flexible interconnections accessible for assembly / disassembly through circumferential access hatches (14A).
9. A rotating transformer according to any one of claims 1 to 7, wherein the internal annular rotor sectors are electrically interconnected with each other by flexible interconnecting parts accessible for assembly / disassembly through circumferential access hatches (14A).
10. Use of a rotating transformer according to any one of claims 1 to 9 for the electrical de-icing of the propeller blades and the nose cone of an aircraft turbomachine.