STATOR FOR AN ELECTRIC MOTOR WITH COMPACT WINDINGS AND METHOD FOR MANUFACTURING SUCH A STATOR

Description

technical field

[0001] The invention relates to the field of electrical engineering, and more specifically to that of rotating machines. It specifically concerns a particular motor stator winding structure, as well as a manufacturing process enabling advantages in terms of compactness and switching frequency of the motor supply circuit. Previous techniques

[0002] In general, electric motor stators consist of a magnetic circuit with a central opening designed to receive a rotor. This magnetic circuit includes a peripheral yoke from which extend various radial projections forming the stator poles, oriented towards the rotor. Each of these projections receives a winding intended to be energized by one phase of a set of currents or voltages generating a rotating alternating field.

[0003] Generally, the windings are made separately, by winding wire around a template shaped like the stator pole. After fabrication, these windings are inserted into the internal volume of the stator and then placed onto the pole protrusions. It is therefore understandable that this type of installation process involves certain constraints.

[0004] Indeed, the internal volume corresponding to the rotor's overall dimensions must be sufficient to accommodate each winding before it is mounted on the stator pole. This necessitates limiting the depth of each pole to a dimension smaller than the rotor's diameter. Simultaneously, the final positioning of each winding is achieved through a radial translation centered on the pole. Thus, the portion of the winding first inserted onto the pole must be narrow enough to pass between the windings mounted on the two adjacent poles. Consequently, an empty volume is created at the bottom of the cavities housing the stator windings, due to the angular separation between two consecutive poles. Therefore, empty volumes free of electrical conductors remain within the stator.

[0005] On another level, this type of winding also presents a drawback related to the circuit geometry during winding formation. Indeed, when the individual turns are created by winding around the template, a parasitic capacitance appears between two successive turns due to their proximity. This parasitic capacitance limits the maximum frequency that can be used to power the stator windings.

[0006] Indeed, it is necessary to limit this switching frequency below the resonance frequency corresponding to the LC circuit consisting of the inductance of the coil and this parasitic capacitance.

[0007] One solution for spacing consecutive turns is to use winding techniques known as "pilgrim's step". However, this solution is limited since it only allows for a slight spacing between successive turns, and it also introduces irregular areas in the winding which reduce the electrical conductivity fill rate.

[0008] Another solution involves creating U-shaped conductors, which are then assembled and mounted on a pole piece, as described in documents CH108795A, JP2005137174 A, or US6548933 B2. However, this assembly is tricky to perform and leads to a lack of reproducibility of electrical properties from one motor to another. Description of the invention

[0009] One of the objectives of the invention is therefore to propose an electric motor structure, and more specifically its stator winding, that optimizes the internal volume of the stator to maximize the motor's ampere-turns. Another objective is to enable control and reduction of the parasitic capacitance present between turns, with a high level of reproducibility.

[0010] Another objective of the invention is to provide a motor that can operate under high voltages, by controlling the breakdown voltage within the winding, as well as operating at a higher switching frequency, for the purpose of high-speed operation and low harmonics.

[0011] To achieve this, the Applicant designed an electric motor stator, which in a known manner comprises a magnetic circuit having a plurality of radial polar protrusions.

[0012] According to the invention, this stator is characterized in that it comprises, for all or part of these protrusions, a set of conductive zones of general U-shape, arranged around this protrusion, the ends of each of these conductive zones being located at the level of a substantially common plane.

[0013] In addition, this stator also includes at least one connecting element comprising a plurality of conductive tracks connected to distinct ends of the conductive areas, so as to define a continuous electrical circuit forming a winding around one or more radial pole protrusions.

[0014] In other words, the invention consists of constructing the stator winding from two distinct parts. The first part forms a set of partial turns, which extend around the stator poles. The ends of these conductive areas all open onto one side of the stator, where they are then connected to a connection device, such as a printed circuit board, busbar, or similar, which allows for the individual connections of the partial turns.

[0015] Thus, the stator winding circuit is defined by the succession of partial turns which are connected to each other through the common connecting element.

[0016] In other words, the invention makes it possible to carry out the winding by an axial mounting of all the partial turns around the stator pole, then a closure of the stator winding by means of an added element in a second step.

[0017] This operating method advantageously utilizes the entire available volume within the stator's magnetic circuit, particularly the space between the stator poles. In existing solutions, the windings are inserted radially by pushing the stator pole into the central recess of the winding. This requires that the recess be larger than the end of the stator pole.

[0018] Thus, in the case where this pole has lateral flares intended to smooth the motor torque, the volume located behind these flares is somehow lost.

[0019] The geometry of the elements constituting the winding is particularly advantageous. In practice, the different conductive zones are arranged concentrically around the stator pole piece. In other words, the various U-shaped partial turns are arranged in the same plane, and the radius of curvature of their curved sections increases outwards. In other words, these partial turns are nested one inside the other, with a nearly constant spacing between each one, forming a flat or curved layer.

[0020] In practice, these different layers, including nested partial turns, can themselves be stacked by being juxtaposed along a radial axis. In other words, the different partial turns form a matrix in which each element is defined by its order number relative to the stator pole, and by its order number relative to the rotor.

[0021] In practice, the cuts that separate two successive layers can be flat, and thus easily made by techniques such as electro-erosion with a continuous wire, or cutting by laser beam, water jet or equivalent.

[0022] Alternatively, the cuts separating two successive layers can also be curved to define turns of substantially constant radial dimensions and exhibiting a curvature centered on the axis of rotation of the rotor.

[0023] In practice, the space between adjacent conductive areas can be filled with an electrically insulating resin, thus ensuring the dielectric strength of the winding. This insulation can also be achieved by using sheets of electrically insulating material inserted between adjacent conductive areas. Such arrangements ensure good dielectric strength of the winding, given the dimensions of the cutouts forming the gap between adjacent turns, which can reach several tens to several hundred microns, compared to the reduced insulating power of the protective sheaths covering the wires of prior art windings, which is on the order of tens of microns.

[0024] Such an arrangement thus allows the motor to be used at particularly high supply voltages.

[0025] In practice, the connecting element ensuring the electrical link between the different turns can be made in different ways.

[0026] For example, a connecting element can be used for each pole end, thus defining a winding at each stator pole with all the turns that make up the coil. Conversely, a connecting element can be used for several pole ends, and in particular for all the stator windings.

[0027] In other words, this connecting element can be a single unit, ensuring the connection between turns within a given stator winding, but also between two different windings, preferably windings supplied by the same phase of the power supply voltage system. Thus, it is possible to combine turns from two diametrically opposed windings by connecting them through the connecting element, thereby increasing the distance between consecutive turns of the same overall winding.

[0028] In practice, this connection device can be implemented in various forms, depending on the application and the required voltage and current levels. It can be a multilayer printed circuit board with traces of a width adapted to the applied current level. It can also be a device combining more substantial conductors, such as those known as bus bars.

[0029] In more sophisticated embodiments of the invention, it is possible to incorporate active semiconductor elements on this connecting member, enabling the monitoring, diagnosis, or even reconfiguration of the coils to correct a fault or ensure an operating point distinct from that of the original configuration. This reconfiguration can be particularly useful in high-speed, high-power machines. Indeed, the invention allows all or part of the turns to be connected in series or parallel, depending on the operating conditions. Thus, when it is desired to reduce the magnetic flux generated by the stator winding, it is possible to reduce the number of turns by connecting some turns in parallel, for the same supply current, thereby reducing the number of ampere-turns. It is also possible to vary the number of turns in real time, in order to control the instantaneous flux, for example, at a constant current.The number of turns can vary between two opposite extreme values, depending on the number and direction of the turns put in series.

[0030] Another aspect of the invention relates to a method for manufacturing an electric motor stator as mentioned above, thus comprising a stator magnetic circuit including a plurality of radial polar protrusions.

[0031] According to the invention, this process comprises the following steps: First, the creation in a block of conductive material of a plurality of through cuts, defining a set of mechanically joined conductive zones of general U shape around one or more central recesses; then, an insertion of this set of conductive zones into the magnetic circuit in a substantially axial movement until the radial polar protrusions fill the central recess(es) of this set of conductive zones; finally, the fixing on this set of conductive zones of one or more connecting members, comprising a plurality of conductive tracks connected to distinct ends of the conductive zones, so as to define a continuous electrical circuit forming a winding around one or more radial polar protrusions.

[0032] In other words, the method according to the invention consists of manufacturing the winding from a block of compact material, and of making slots in this block that define partial elementary turns. This block can then be placed on the stator pole by axial displacement, and not by radial threading onto the stator pole.

[0033] It follows that this mounting method allows the entire volume located between the stator poles to be occupied, with wider windings in the area closest to the cylinder head than in the area closest to the rotor.

[0034] Such a shape is of course impossible to introduce onto the stator poles by a radial movement, since the windings which would be put in place beforehand would prevent the introduction of subsequent windings.

[0035] This manufacturing method ensures near-perfect regularity in the geometry of the windings and stator coils, with a significant improvement in the reproducibility of these constructions, particularly compared to windings made manually in the prior art. Due to its construction, the winding has ends whose position is precise and identical from one winding to another, allowing these ends to serve as indexes or reference points for positioning additional components with mechanical or electrical functions. This high degree of manufacturing regularity thus reduces the variability of winding parameters dependent on its geometry, notably its dielectric strength and the parasitic capacitances between turns, which directly affect the winding's resonant frequency.Reducing parasitic capacitances also has the direct consequence of reducing and controlling high-frequency common-mode currents that flow between the winding and the frame and which are very often the cause of premature bearing wear (even for slow-speed machines).

[0036] In practice, the process advantageously includes a step consisting of bonding the conductive areas with an insulating material. In other words, the spaces between adjacent turns are filled with a material that provides both electrical insulation between adjacent turns and also bonds this set of partial turns together to allow for handling and maintaining its shape.

[0037] In practice, this insulating material can be a resin contained in a bath into which all the conductive areas are immersed after the cuts defining the geometry of the partial turns have been made. This ensures that these gaps are filled with insulation, for example in the form of an insulating resin introduced under vacuum and subsequently polymerized, while the partial turns are held spatially relative to each other by a retaining flange.

[0038] Advantageously, in practice, the manufacturing process includes a step of extracting the portion defining the central recess from the block of conductive material. In practice, all the conductive areas are also separated from the portion of the conductive material block that holds these areas together during the cutting process. In other words, after the cuts defining the partial turns are made, these turns are still held together by a piece of material that remains connected to all the partial turns. This piece is then removed, along with the portion of material located at the center of the partial turns, which is intended to house the stator pole.

[0039] In practice, various techniques can be used to perform the different cuts. One example is electro-erosion with a continuous wire, which allows cuts to be defined in the form of ruled surfaces, and advantageously, developable surfaces in the mathematical sense of the term.

[0040] Other techniques can also be considered such as water jet or laser cutting, or even needle electro-erosion techniques, allowing the material block to be machined from a single face, and thus making curved cuts for defining concentric turns, as well as for separating successive layers of radially stacked turns.

[0041] Various geometries can be used to construct this stator winding. This allows for as many individual sets of conductive zones as there are pole protrusions, so that they can be individually inserted into the magnetic circuit. In other words, a set of turns is created for each stator pole, and these different sets are installed independently within the frame.

[0042] Conversely, it is possible to create multiple sets of conductive zones within a single block of conductive material, allowing this complex component to be inserted into the stator's magnetic circuit in a single step. In other words, the process involves creating several, or even all, of the stator windings (except for the closing portion) within a single block, which can then be axially inserted into the motor's magnetic circuit in one step. Of course, depending on industrial constraints, it is possible to produce one or more blocks incorporating all or part of these stator windings.

[0043] In practice, it is possible to make the characteristic cuts according to different geometries and orientations.

[0044] Thus, in a first embodiment, it is possible to create radial cuts that pass through the virtual axis of the stator, these cuts separating concentric turns associated with the same pole piece. In other words, two adjacent turns located at the same distance from the motor axis are separated by planes passing through the motor axis.

[0045] In another embodiment, these same planes separating concentric turns can all be parallel, and distributed on either side of a median plane passing through the axis of the motor.

[0046] Regarding the cutouts separating adjacent coils located at different distances from the motor axis, several possibilities can be implemented.

[0047] Thus, these cuts can be flat, and perpendicular to the radial symmetry plane of the stator winding under consideration.

[0048] In another embodiment, these cutouts can be cylindrical and centered on the motor axis to separate radially offset turns associated with the same pole protrusion. In practice, these cutouts can be formed by a circular tool such as a hole saw or similar, or they can result from the assembly of several concentric cylindrical elements of staggered diameters. In other words, in this case, the block of conductive material is made by assembling several concentric tubes fitted one on top of the other and secured to a retaining piece, typically a disc. Thus, the cutouts to delimit the conductive areas that will form the future turns are made on all the tubes simultaneously, without requiring subsequent assembly or positioning of the turns relative to each other. Brief description of the figures

[0049] The method of implementing the invention, as well as the resulting advantages, will become clear from the following description of the embodiment, supported by the attached figures in which: There figure 1 is a rough perspective view of a block of conductive material on which the different cuts used to define the partial turns are identified. figure 2 is a view of the face of the block of the figure 1 parallel to the radial plane of the stator winding. The figure 3 is a view from below of the block of the figure 1 . THE Figures 4 and 5 are views of the faces of the block of the figure 1 , according to orthoradial planes, corresponding to the faces respectively in contact with the stator head and opposite the rotor. The figure 6 is a median cross-sectional view along plane VI-VI' of the figure 1 . There figure 7 is a rough perspective view of the block of the figure 1in which a fraction has been eliminated, to illustrate the detail of the geometry of the partial turns. The figure 8 is a view of the block of the figure 1 shown after removal of the piece of material holding together the different partial turns. The figures 9 to 11 are rough perspective views of stator winding assemblies similar to that of the figure 8 , produced according to different orientations and cutting geometries. The figure 12 is a rough perspective view showing the assembly operation of the different blocks of the figure 8 inside the engine stator. The figure 13 is a rough perspective view showing the placement of the connecting element on the ends of the blocks inserted into the stator at the figure 12 . There figure 14 is a schematic cross-sectional view along a radial plane of the connecting element of the figure 13, also showing the upper part of the partial turn blocks on two diametrical stator windings. The figure 15 is a schematic top view showing the connecting organ of the figure 13 , as well as some conductive tracks connecting elementary turns.

[0050] Of course, the various elements illustrated in the figures have been shown with dimensions and proportions which may deviate from reality, and which have been given only to facilitate understanding of the invention. Method of implementing the invention

[0051] As already mentioned, the invention relates to a method for manufacturing a stator winding of an electric motor, as well as the winding and more generally the stator thus obtained.

[0052] To carry out this process, one can, as illustrated very schematically in the figure 1, use a block of conductive material, typically copper-based or equivalent, whose volume corresponds approximately to that of an elementary winding intended to be placed on a stator pole.

[0053] This block 1 is worked to produce a set of cuts, which will define elementary turns allowing the part of the stator winding to be made which will be inserted inside the stator magnetic circuit.

[0054] More specifically, and as illustrated in the figure 1 the block 1 has a face 2, which, when the winding is inserted into the stator, is intended to come into contact with the stator yoke. In the rest of the description, this face will be considered the front face of the block. Thus, the rear face 3 is the one that will be positioned opposite the rotor, while the lateral faces 4 And 5These will be positioned opposite the adjacent stator windings. The underside 6 corresponds to the lower end of the stator winding, while the upper face 7 block one corresponds to the one where the different partial turns will be connected to each other by the connecting element mentioned above.

[0055] The block 1 features several series of through cutouts, that is to say, extending respectively from the front face 2 all the way to the back 3, and a side face 4 to the other 5. Specifically, the front 2 includes a set of cutouts 10,11,12,13 which define on the back face patterns of a general U shape, which are nested one inside the other of the largest 10 outwards towards the smallest 13 in the center.

[0056] The central cutout 13corresponds roughly to the contours of the stator pole on which the future stator winding will be installed. As illustrated in the figure 6 these cutouts 10-13 are traversing the face 3 all the way to the back 2. Specifically, these cutouts have different angles. The cutout 13 has two sides 131 132 substantially parallel, and separated by a distance slightly greater than the dimension of the stator pole measured orthoradially. Conversely, the cut 10 has two sides 101 102 which form a non-zero angle with each other, so that the stator winding has a roughly trapezoidal cross-section, wider on its rear face than on its front face. In theory, the angle between the faces 101 And 102 can go up to a value of 360° divided by the number of stator poles.

[0057] In one particular embodiment, these cutouts can be made using electro-erosion techniques, which involve passing a conductive wire, forming an electrode, through the front face. 2 all the way to the back 3, by moving according to the pattern of the different cuts to form the planes delimiting the future coils. In a particular case, it can be advantageous as illustrated in Figures 4 and 5 to perform an initial drilling 18, of a diameter sufficient to allow the insertion of the electrode wire, to then initiate the cut with a smaller width. Similarly, to facilitate the creation process, it can be advantageous to connect successive U-shaped cuts with segments 19,20,21 allowing for the various cuts to be made 10-13 continuous, without interruption of the electro-erosion process.

[0058] Additionally, the block 1also features another series of cutouts extending from one side 4 to the other 5, along planes parallel to the front face 2. These cutouts can be made as illustrated in the figure 2 from the lower face 6, extending towards the upper face 7, while leaving a portion free of cuts 35, serving as a base ensuring the overall cohesion of the different portions defined between the cuts.

[0059] The result of these different cuts is illustrated in the figure 7 in which a portion of the block has been masked, so as to show part of the elementary turns. More precisely, the machined block thus comprises a central portion 40, which has a volume similar to that of the stator pole on which the stator winding will be inserted.

[0060] The block partially illustrated at the figure 7also includes the heel 35, which ensures the stability of the different layers of partial turns 104-109, 204, 304, 404.This block is therefore easy to handle and can be treated to ensure the application of an insulating coating. More specifically, in a particular case, this block can be immersed in an epoxy or similar resin, which penetrates the cutouts and fills the corresponding volumes. In practice, the filling can be done under vacuum to control the resin's penetration into the cutouts between the turns and prevent the formation of air bubbles that would be detrimental to the dielectric properties. Advantageously, the assembly is then placed in an oven to ensure the resin polymerizes. It should be noted that the thickness of the insulating material is therefore relatively significant compared to the insulation used to sheath the wires of wound coils, as it corresponds approximately to the thickness of an electrical discharge machining (EDM) cutout, on the order of a few tens to a few hundred microns. This thickness also has the advantage of being very consistent and reproducible.

[0061] Of course, the electrical insulation of the individual turns of the block can be achieved using other techniques, particularly the insertion of solid materials in the form of insulating sheets. It is also possible to combine two types of insulation by inserting sheets of insulating material into some of the cutouts, especially those formed by parallel planes, while the other cutouts are filled with a liquid resin designed to solidify.

[0062] In a later step illustrated at the figure 8 the heel 35 is then eliminated, which on the one hand frees up the portions 50 defined between the lateral faces 4, 5 of the block, and the outermost cut 10, due to the trapezoidal shape of the future winding. Simultaneously, the elimination of the heel 35allows the ends of all the partial turns to be freed, and thus defines a matrix of connections to be made to finalize the winding.

[0063] The variant illustrated at the figure 9 shows the assembly of six basic blocks 3251-3256 each corresponding to one-sixth of the overall stator winding. Each block 3251-3256, is achieved through a series of flat cuts 3267-3271. These cuts are subdivided into two groups of cuts perpendicular to each other, defining spirals. 3261-3263 presenting distinct sections. It is possible to normalize the average section, by making parallel groupings of turns of sections with values ​​furthest from the average, by the mechanisms described above and incorporated in the connecting element.

[0064] In the variant illustrated at the Figure 10 The various stator windings are made in a single block4250, from two separate sets of cuts. In the example shown, two cuts 4261, 4262,Cylindrical cuts are made throughout the block to define three levels of windings at three distinct distances from the motor center. These cuts can be made by concentric grooves created by electrical discharge machining (EDM) and the insertion of a thin bell-shaped cutter, with as many cutters as there are gaps required along the radial direction. Alternatively, an equivalent geometry could be achieved by fitting concentric cylindrical metal tubes, with a gap between the tubes corresponding to the space between two radially offset levels of windings. These tubes are embedded in a series of concentric grooves of the same average diameter made in a discoidal metal base, advantageously machined. In this way, the tubes are held in position relative to each other to allow for the creation of the through cuts defining the radial cuts. 4270-4274formed by planes passing through the motor axis. This geometry allows for turns with a substantially homogeneous cross-section within the stator winding.

[0065] In an illustrated variant the figure 11 The block containing the six stator windings also features cylindrical cutouts. 5261-5263 similar to those carried out on the variant of the Figure 10 Additionally, this block receives several groups of flat cutouts. 5270 5271, 5280, 5290 along parallel planes extending from one side of the block to the other, thus creating cuts in the two diametrically opposed stator windings. These cuts are made by electro-erosion, and in the illustrated example, three series of cuts are used to create all the turns of the future stator winding.

[0066] Subsequently, as illustrated in the figure 12 six of these blocks 251-256 analogous to the block 25 of the figure 8 are selected to then be inserted into the magnetic circuit 150 of the stator. More precisely, this magnetic circuit 150 It features a peripheral cylinder head from which six radial protrusions emerge. 151-156, designed to form the stator poles. At the center of these six protrusions is the location of the future motor rotor. Thus, through an axial translational movement, illustrated by arrow T, the different blocks 251-256 are introduced astride the polar outgrowths 151-156,by filling as much as possible the volumes 160 defined between two successive pole protrusions. It should be noted that the arrangement of these blocks of partial turns can be done independently of the shape of the radial pole ends, which, in a form not shown, could include protrusions extending orthoradially. It is therefore observed that the stator volume is almost completely filled, compared to values ​​of around 50% for conventional wire windings.

[0067] Subsequently, and as illustrated in the figure 13 the magnetic circuit 150, equipped with all the blocks 251-256 forming the bulk of the windings receives a connection element 500, designed to ensure the connection between partial elementary turns in order to form the complete stator windings. More specifically, this connecting element 500comes in the form of a printed circuit board with a plurality of areas 501-506 connection pads 511,512. These cones 511,512 are arranged to face the extremities 2512,2511 Partial windings emerge from the stator's yoke. Naturally, various connection methods are possible for mounting the connecting element onto the partial winding assemblies. These include the use of solder paste, or even brazing, to connect the connection pads of the connecting element to the ends of the windings cut from the solid metal block. Alternatively, the printed circuit board forming the connecting element could have, on its side facing the windings, a set of pins that fit into additional holes drilled at the ends of the windings.

[0068] Of course, this connection element can be implemented using methods other than a printed circuit board, particularly with metallic components such as bus bars or similar designs. In the configuration shown, the printed circuit board serves as a single unit for all stator windings, but it is possible to design a connection element for one or more stator windings.

[0069] The connecting organ 600, as illustrated in the figure 14 ensures the connection between the ends 604,605 turns that are located on one side of the stator pole, with the ends 704,705,706,707 located on the other side of the same pole, in order to define complete turns around that pole. This connection is made via the tracks 801,802 extending inside the printed circuit board, between the connection pads 614-616 and the cones 714-716. Meanwhile, the coils extend to the ends 609, 709They can be connected to the power supply system, or to other windings, via the pads. 620,630 located on the upper surface of the connecting element 600. The tracks 801,802 represented at the figure 11 are given as an example, and their exact positioning as well as the determination of the corresponding connection points will be explained in detail below.

[0070] The printed circuit board can advantageously be a multilayer board, allowing the conductive traces to be arranged on different levels and, in particular, permitting the electrical connection of several geometrically parallel traces to increase the conductive cross-section between two connection pads. It is also possible to widen the traces to increase this cross-section as needed.

[0071] As schematically illustrated in the figure 15 the tracks 901,902,903allow the connection of the ends of partial turns that are not located on directly adjacent layers of turns. More specifically, the track 901 allows you to connect the end 915 of the partial loop formed by the conducting portion between the ends 915 995, with the end 971, belonging to the spiral extending between the ends 971 And 931. Additionally, the track 902 allows you to connect the end 931 with the end 987, belonging to the spiral extending to the end 927. The track 903 connects the end 927 of the spiral mentioned above with the end 963 belonging to the spiral extending to the end 943.It can be seen that the successive turns of this overall winding are not located on adjacent layers (in a radial direction), but are significantly further apart. Consequently, the parasitic capacitance between two consecutive turns is greatly reduced, so that the winding's natural modes, evaluated by taking into account the elementary inductances of each turn and the parasitic capacitances existing between each turn, are found at significantly higher frequencies. It follows that the motor thus constructed can be powered with voltage systems generated by PWM (Pulse Width Modulation) systems operating at switching frequencies significantly higher than in the prior art.

[0072] In practice, the routing that determines the optimal positioning of the tracks can be obtained through an optimization process aimed at minimizing parasitic capacitances, or increasing the natural frequencies of the winding.

[0073] As an example, this process can implement the definition of a mathematical distance that accounts for the degree of proximity of the two half-turns to be interconnected, for example a function of the coordinates measuring the squared difference between the length of the interconnecting segment linking the two half-turns to be interconnected and the length of the segment that would short-circuit the half-turn itself.

[0074] This process requires defining a criterion to be optimized which, from the point of view of proximity effects, can for example be a total distance corresponding to the sum of said elementary mathematical distances for the whole of the coil.

[0075] The solution to the optimization problem consists of minimizing this total distance if one focuses on proximity effects. Depending on the intended application, one can seek to optimize frequency performance and / or conduction losses. In this case, it is advantageous to approach the problem from a multi-criteria perspective, particularly with a view to simultaneously minimizing proximity effects and the additional resistances related to the total length of the interconnecting circuits—two criteria that may appear to be conflicting.

[0076] Of course, in variations not shown, the various partial turns are not necessarily connected together within a winding assigned to a single pole. The invention thus also covers variations in which the winding is constructed by combining turns from different poles, resulting in a significant reduction, or even a negligible reduction, of the parasitic capacitance between adjacent turns.

[0077] It follows from the foregoing that the invention enables the production of electric motors with a particularly high stator winding filling rate. Another important advantage is the ability to operate at exceptionally high switching frequencies and a reduction in the intensity of common-mode parasitic currents circulating in the machine and its surroundings. A further industrial advantage concerns the reproducibility of electrical parameters, particularly voltage withstand, due to the deterministic construction of the windings.

Claims

1. A method for producing a stator for an electric motor, comprising a stator magnetic circuit comprising a plurality of radial polar protuberances, the method comprising the following steps: • producing, in a block of conductive material (1), a plurality of through-cuts (10-13, 30) defining a set of mechanically conductive zones (104-109, 204, 304, 404) of generally U-shaped around one or more central openings, the conductive zones thus forming U-shaped partial turns; • inserting said set of conductive zones (251-256, 3251-3256) into the magnetic circuit with a substantially axial movement until the radial polar protuberances (151-156) fill the one or more central openings of said set of conductive zones; and • attaching, on said set of conductive zones, one or more connection components (500) comprising a plurality of conducting tracks connected to distinct ends of said conductive zones, so as to define a continuous electrical circuit forming a winding around one or more radial polar protuberances.

2. Method according to claim 1, characterized in that it comprises a step consisting of securing said conductive zones by an electrically insulating material.

3. Method according to claim 2, characterized in that the set of conductive zones is dipped into an insulating resin bath.

4. The method according to claim 1, further comprising a step of extracting, from the block of conductive material, the one or more portions (40) defining the one or more central openings.

5. The method according to claim 1, further comprising a step of separating the set of conductive zones from a portion of the block of conductive material that maintains said conductive zones secured together during the production of the through-cuts.

6. The method according to claim 1, wherein as many sets of conductive zones as polar protrusions of the stator magnetic circuit are produced, said sets being then individually inserted into the magnetic circuit.

7. The method according to claim 1, wherein a plurality of sets of conductive zones are produced in a single block of conductive material, said plurality being then inserted into the magnetic circuit on several radial polar protuberances.

8. The method according to claim 1, wherein the through-cuts are produced using a technique selected from the group consisting of electro-erosion, water-jet cutting, and laser cutting.

9. A stator for an electric motor obtained according to the method of any one of claims 1 to 8.

10. The stator according to claim 9, wherein the through-cuts include radial cuts (4270-4274) passing through a virtual axis of the stator and separating, within said partial turns, concentric turns associated with a same radial polar protuberance (151-156).

11. The stator according to claim 9, wherein the through-cuts include cuts (5270, 5271, 5280, 5290) extending along planes parallel to the virtual axis of the stator and separating, within said partial turns, concentric turns associated with a same radial polar protuberance (151-156).

12. The stator according to claim 9, wherein the through-cuts include cylindrical cuts (4261, 4262, 5261-5263) centered on the virtual axis of the stator and separating, within said partial turns, radially offset turns associated with a same radial polar protuberance (151-156).

13. The stator according to claim 9, wherein the through-cuts include flat cuts (3270, 3271) parallel to the virtual axis of the stator and separating, within said partial turns, radially offset turns associated with a same radial polar protuberance (151-156).

14. The stator according to any one of claims 9 to 13, comprising one connection component for each radial polar protuberance (151-156).

15. The stator according to any one of claims 9 to 14, comprising a common connection component (500) for several radial polar protuberances (151-156).