FERROMAGNETIC ELEMENT FOR ENERGY RECEIVER ELEMENT OF A WIRELESS ELECTRICAL ENERGY TRANSFER SYSTEM.

Abstract

This disclosure relates to a ferromagnetic element intended to be included in an electrical energy receiving element configured to cooperate with an electrical energy emitting element such that the electrical energy receiving element and the electrical energy emitting element form an electrical energy transfer system designed to allow the transfer of electrical energy in the form of a magnetic field from the electrical energy emitting element to the electrical energy receiving element, wherein at least one characteristic relating to at least one constituent material of said ferromagnetic element is dependent, in each region of said ferromagnetic element, on a level of the expected magnetic field in that region. Such a ferromagnetic element comprises material only where necessary, thereby reducing its mass and thus the total mass of the electrical energy receiving element, without disturbing the induced magnetic field.Figure to be published with the abbreviation: Fig. 3A.

Description

Title of the invention: FERROMAGNETIC ELEMENT FOR ENERGY RECEIVER ELEMENT OF A WIRELESS ELECTRICAL ENERGY TRANSFER SYSTEM. technical field

[0001] The scope of this disclosure relates to wireless power transfer using a wireless power transfer system. More specifically, this disclosure relates to a ferromagnetic element of a power receiver element of the wireless power transfer system. This power receiver element is installed in a vehicle, including an aircraft. STATE OF PRIOR ART

[0002] In order to reduce CO2 emissions and noise pollution in airport areas, electric motors can be placed at the level of the landing gear of an aircraft (for example: nose landing gear of the aircraft, and main landing gear), in order to carry out all the operational phases taking place on the taxiways of aircraft in electric mode.

[0003] To power the batteries of these electric motors, wireless electrical power transfer systems have been developed. Figure 1 schematically illustrates a front view of an example of a wireless electrical power transfer system. This wireless electrical power transfer system comprises: an electrical power receiver element ER carried on board the aircraft, and an electrical power transmitter element EE embedded in the ground of the taxiways. The electrical power transmitter element EE is configured to transfer electrical power in the form of a magnetic field to the electrical power receiver element ER when the latter is positioned opposite said electrical power transmitter element EE.The electrical energy receiving element ER then converts the electrical power received from the electrical energy emitting element EE and transmits this converted electrical power to the batteries powering the electric motors (not shown in [Fig.1]).

[0004] The electrical energy emitting element EE and the electrical energy receiving element ER comprise several components such as: an envelope 101R, 101E in which coils 102R, 102E are inserted, a ferromagnetic element 103R, 103E and an aluminum plate 104R, 104E having an electrical shielding function.

[0005] This ferromagnetic element 103R is used so that the magnetic field generated by the electrical energy emitting element EE can close around the coils 102R of the electrical energy receiving element ER. It is thus possible to constrain the magnetic field generated by the electrical energy emitting element EE and to limit the losses of magnetic energy.

[0006] This ferromagnetic element 103R is generally composed of ferrites, for example in the form of parallelepiped tiles placed side by side. The ferrites have a high mass density, representing approximately one-third of the total mass of the electrical energy receiving element ER carried in the aircraft.

[0007] Furthermore, after modeling the magnetic field at the level of the ferromagnetic element 103R of the electrical energy receiving element ER, it can be observed that the use of ferrites is not optimized because the levels of the magnetic field are inhomogeneous, or even detrimental in certain areas of the ferromagnetic element 103R.

[0008] It is therefore desirable to overcome these drawbacks of the prior art.

[0009] In particular, it is desirable to provide a solution which makes it possible to reduce the weight of the electrical energy receiving element without disturbing the induced magnetic field circulating in this electrical energy receiving element. Description of the invention

[0010] A ferromagnetic element is proposed herein for inclusion in an electrical energy receiving element configured to cooperate with an electrical energy emitting element such that the electrical energy receiving element and the electrical energy emitting element form an electrical energy transfer system designed to allow the transfer of electrical energy in the form of a magnetic field from the electrical energy emitting element to the electrical energy receiving element. The ferromagnetic element is characterized in that at least one characteristic relating to at least one constituent material of said ferromagnetic element is dependent, in each region of said ferromagnetic element, on a level of the expected magnetic field in that region.

[0011] Advantageously, such a ferromagnetic element only includes matter where necessary, which makes it possible to reduce its mass and therefore the total mass of the electrical energy receiving element, without disturbing the induced magnetic field.

[0012] According to one embodiment, said at least one characteristic relating to said at least one material is a quantity of said at least one material in said area in question.

[0013] According to one embodiment, the quantity of said at least one material in a first zone of said ferromagnetic element is higher than in a second zone when in this first zone the level of magnetic field is higher than in the second zone.

[0014] According to one embodiment, said at least one characteristic relating to said at least one material is a magnetic permeability of said at least one material in said area in question.

[0015] According to one embodiment, said magnetic permeability of said at least material in a first zone is lower than in a second zone when in this first zone the level of magnetic field is higher than in the second zone.

[0016] Also proposed here is an electrical energy receiving element configured to cooperate with an electrical energy emitting element such that the electrical energy receiving element and the electrical energy emitting element form an electrical energy transfer system designed to allow the transfer of electrical energy in the form of a magnetic field from the electrical energy emitting element to the electrical energy receiving element. This electrical energy receiving element comprises a ferromagnetic element as described above.

[0017] Also proposed here is an aircraft comprising an electrical energy receiving element as described above.

[0018] Also proposed here is an electrical power transfer system for supplying power to equipment on an aircraft as described above. This system comprises an electrical power receiver element as described above, installed on the aircraft, and an electrical power transmitter element on the ground. Brief description of the drawings

[0019] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of at least one exemplary embodiment, said description being made in relation to the accompanying drawings, among which:

[0020] [Fig-1] schematically illustrates a front view of an example of a system of wireless electrical energy transfer;

[0021] [Fig.2A] and [Fig.2B] schematically illustrate a perspective view, respectively a front view, of the induced magnetic field levels circulating in the ferromagnetic element of an energy receiving element according to the prior art; [Fig.3A], [Fig.3B] and [Fig.3C] schematically illustrate, respectively, a perspective view, a top view and a front view, of a ferromagnetic element of an energy receiving element, according to an embodiment;

[0022] [Fig.4A], [Fig.4B], [Fig.4C] and [Fig.4D] schematically illustrate, respectively, a perspective view, a cross-sectional view, a top view and a side view, of a ferromagnetic element, according to an embodiment.

[0023] DETAILED DESCRIPTION OF IMPROVEMENTS

[0024] Fig. 2A and Fig. 2B schematically illustrate a perspective view, respectively a front view, of the expected induced magnetic field levels in a conventional ferromagnetic element 103R (for example as presented in connection with Fig. 1) of an electrical energy receiving element ER on board a vehicle, such as an aircraft.

[0025] As described previously, the levels of the magnetic field induced in the ferromagnetic element 103R are inhomogeneous. In an xy plane, the areas of the ferromagnetic element 103R in which the magnetic field is high (i.e., between 30.8 and 37 mTesla), denoted Fl, F2, are located in particular in an area beginning at a first distance, denoted dl, from the sides of the ferromagnetic element 103R and ending at a second distance, denoted d2, from the center of the ferromagnetic element 103R. The areas of the ferromagnetic element 103R in which the induced magnetic field level is low (i.e., between 6 and 12.2 mTesla), denoted NI, N2, N3, N4, N5, are located in particular around a central part of the sides of the ferromagnetic element 103R, as well as around the very center of the ferromagnetic element 103R. In a zy plane (see [Fig.2B]), the areas of the ferromagnetic element 103R in which the magnetic field level is high (F1 and F2) are located in a lower part of the ferromagnetic element 103R, i.e. in contact with a lower face of the ferromagnetic element 103R which is in contact with the coils 102R. The areas with low magnetic field NI, N2 and N4 are located in an upper part of the ferromagnetic element 103R, i.e. in contact with an upper face of the ferromagnetic element 103R which is not in contact with the coils 102R.

[0026] According to one embodiment, in order to reduce the total mass of the electrical energy receiving element ER, one or more characteristics relating to one or more constituent materials of the ferromagnetic element 103R (hereafter referred to as material characteristics) are adapted to the variations in the expected induced magnetic field level in the ferromagnetic element 103R. More specifically, material characteristics such as, for example, the amount of material in each zone of the ferromagnetic element (i.e., the shape and topology of the ferromagnetic element), and / or the magnetic permeability of the material(s) used in the ferromagnetic element in each zone of the ferromagnetic element, will depend on the different levels of the expected induced magnetic field in these zones. More specifically, the value of one or more of these characteristics, or a combination thereof, is adapted to the variations in the expected induced magnetic field level. The characteristics in each zone of the ferromagnetic element depend on the value of the magnetic field induced in those zones. Here, a "zone" of the 103R or 303 ferromagnetic element, in a three-dimensional xyz plane, is understood to be a portion (i.e., a predetermined volume) of the total volume of the 103R or 303 ferromagnetic element.

[0027] Figs. 3A, 3B, and 3C schematically illustrate, respectively, a perspective view, a top view, and a front view of an example of a ferromagnetic element 303 of an electrical energy receiving element ER according to one embodiment. Figs. 4A, 4B, 4C, and 4D schematically illustrate, respectively, a perspective view, a cross-sectional view, a top view, and a side view of an example of a ferromagnetic element 303 according to one embodiment.

[0028] In this embodiment, the amount of material in each zone of the ferromagnetic element 303 depends on the different levels of the expected induced magnetic field in the ferromagnetic element 303 in those zones. Thus, the shape (i.e., boundary of the ferromagnetic element 303) and the topology (i.e., amount of material within a specific zone of the ferromagnetic element 303) depend on these different levels of the expected induced magnetic field. In other words, instead of having a ferromagnetic element of regular shape and constant thickness (e.g., substantially rectangular and made up of several tiles of the same material and of the same dimensions), the ferromagnetic element 303 has a shape and a topology that depend on the levels of the expected induced magnetic field as shown previously in connection with Figs. 2A and 2B.

[0029] It should be noted that a view of the left side, the right side or the rear side of the ferromagnetic element 303 are similar to the front view of this ferromagnetic element 303.

[0030] More specifically, the ferromagnetic element 303 contains matter (e.g., a quantity of a material such as ferrite) only in the "necessary" locations, that is, in areas of the ferromagnetic element 303 where the expected magnetic field levels are considered to be medium (e.g., 12.2 to 30.8 mTesla) to high (e.g., 30.8 to 37 mTesla). Conversely, in areas of the ferromagnetic element 303 where the expected magnetic field level is low or even zero (e.g., areas NI to N5), the ferromagnetic element 303 contains little or no material. Furthermore, the higher the expected induced magnetic field level in an area of ​​said ferromagnetic element, the more material the ferromagnetic element 303 contains in that area.In other words, in the Fl and F2 zones where the expected induced magnetic field level is high, there is more material in the ferromagnetic element 303 than in the zones where the expected induced magnetic field level is average. This is reflected in particular by . a greater thickness of the ferromagnetic element 303 around the Fl and F2 zones where the expected induced magnetic field level is high (see [Fig. 3B]). This makes it possible to remove or add material (e.g., ferrite) from the ferromagnetic element 303 in certain areas to optimize its weight, without disturbing the induced magnetic field levels.

[0031] Thus, in one embodiment, in an xy plane, the ferromagnetic element 303 has a shape substantially parallelogram-like with rounded corners. In other words, the ferromagnetic element 303 is substantially parallelepiped-shaped. Furthermore, the ferromagnetic element 303 includes a recess 304 (i.e., a region of the ferromagnetic element 303 not containing any material) centered around the center, denoted C, of ​​the ferromagnetic element 303. This recess 304 is substantially circular with a predetermined radius. The ferromagnetic element 303 therefore comprises an inner edge 303a following the contour of the recess and an outer edge 303b following the contour of the ferromagnetic element 303. The outer edge comprises a plurality of sides (e.g., four sides) whose center is hollowed out towards the center C of the ferromagnetic element 303. In other words, material is removed at the center of each side of the outer edge.

[0032] Furthermore, in a zy and zx plane (see [Fig.3C]), the thickness of the ferromagnetic element 303 varies between a lower bound, denoted Binf, and an upper bound, denoted Bsup, predetermined. If we consider an orthonormal coordinate system xyz, whose point 0 corresponds to the center C of the ferromagnetic element 303, then the ferromagnetic element 303 has a maximum thickness, denoted Emax along the y-axis (respectively -y) at a third distance d3 from the center C of the ferromagnetic element 303 and a minimum thickness, denoted Emin at the inner edge 303a and the outer edge 303b of the ferromagnetic element 303. The third distance d3 is, for example, equal to one-quarter of the total length of the ferromagnetic element 303 in the y and -y directions from the center C of the ferromagnetic element 303.

[0033] It should be noted that the face 303c on the underside of the ferromagnetic element 303 is substantially flat and included in the xy plane.

[0034] According to one embodiment, the ferromagnetic element 303 consists of a single piece in a predefined material (e.g., ferrite) and whose shape and topology are as described above.

[0035] Alternatively, the ferromagnetic element 303 consists of several pieces made of a predefined material (e.g., ferrite) which, when assembled together, form a ferromagnetic element 303 whose shape and topology are as described above. Figs. 3A to 3C show a ferromagnetic element 303 comprising a plurality of pieces (e.g., 8 pieces).

[0036] According to one embodiment, the ferromagnetic element 303 has variable magnetic permeability. More specifically, the magnetic permeability for each region of the ferromagnetic element 303 depends on the expected level of the induced magnetic field in that region. This variability in magnetic permeability can be achieved either by using several materials, each with a different magnetic permeability, or by using a single material with a different magnetic permeability (e.g., obtained by sintering different powders, allowing control of the magnetic permeability value spatially within the material).The objective is to use one or more materials with low magnetic permeability in areas of the ferromagnetic element 303 where the expected level of induced magnetic field is high, and one or more materials with higher magnetic permeability in areas of the ferromagnetic element 303 where the level of magnetic field is low.

[0037] It is thus possible to homogenize the magnetic field induced in the ferromagnetic element 303 to reduce losses and therefore heating of the ferromagnetic element 303, while also reducing the mass of this ferromagnetic element 303. Furthermore, the electrical energy receiving element ER, comprising such a lighter ferromagnetic element 303, also has its total weight reduced. This is particularly advantageous when such an electrical energy receiving element ER, forming part of the electrical energy transfer system 100 as described above, is used in an aircraft to supply electrical power to equipment (e.g., electric motor batteries) (e.g., aircraft landing gear) of the aircraft.

Claims

Demands

1. Ferromagnetic element (303) intended to be included in an electrical energy receiving element (ER) configured to cooperate with an electrical energy emitting element (EE) such that the electrical energy receiving element (ER) and the electrical energy emitting element (EE) form an electrical energy transfer system (100) designed to permit the transfer of electrical energy in the form of a magnetic field from the electrical energy emitting element (EE) to the electrical energy receiving element (ER), wherein at least one feature relating to at least one constituent material of said ferromagnetic element (303) is dependent, in each zone of said ferromagnetic element (303), on a level of the expected magnetic field in that zone.

2. Ferromagnetic element (303) according to claim 1, wherein said at least one feature relating to said at least one material is an amount of said at least one material in said area in question.

3. Ferromagnetic element (303) according to claim 2, wherein the quantity of said at least one material in a first zone of said ferromagnetic element (303) is higher than in a second zone when in this first zone the magnetic field level is higher than in the second zone.

4. Ferromagnetic element (303) according to any one of claims 1 to 3, wherein said at least one feature relating to said at least one material is a magnetic permeability of said at least one material in said area in question.

5. Ferromagnetic element (303) according to claim 4, wherein said magnetic permeability of said at least material in a first zone is lower than in a second zone when in this first zone the magnetic field level is higher than in the second zone.

6. An electrical energy receiving element (ER) configured to cooperate with an electrical energy emitting element (EE) such that the electrical energy receiving element (ER) and the electrical energy emitting element (EE) form an electrical energy transfer system (100) designed to permit the transfer of electrical energy in the form of a magnetic field from the element

7.

8. electrical energy emitter (EE) to electrical energy receiving element (ER), said electrical energy receiving element (ER) comprising a ferromagnetic element (303) according to any one of claims 1 to 5. Aircraft comprising an electrical energy receiving element (ER) according to claim 6. Electrical energy transfer system (100) intended to supply equipment power to an aircraft according to claim 7, said system (100) comprising an electrical energy receiving element (ER) according to claim 6 carried on board the aircraft and, on the ground, an electrical energy transmitting element (EE).

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