Electric machine stator and corresponding winding method

Abstract

Electric machine stator and corresponding winding method The present invention relates to an electric machine stator (20) formed of a wound stator body (12), the stator (20) comprising at least three phases, the circumference of the stator body (12) comprising S series (s1, s2, s3, s4) of K consecutive notches per phase, the winding of the notches (e1, e13) of the same phase being formed of a same phase formed of several conductors (1, 2, 3, 4, 5, 6, 7, 8) electrically connected in parallel, different conductors of the phase being present in at least two of the K notches of a series of K notches, said different conductors corresponding to the same passage of the phase on the circumference of the stator body (12), the stator (20) being characterized in that given a k-th notch position, each of the conductors of the phase is present at the k-th notch position in at least one of the S series of K notches. (Figure 7)

Description

Title of the invention: Stator of an electric machine and corresponding winding method

[0001] The present invention relates to the field of electrical engineering and more specifically concerns a wound stator for an electrical machine and a method of winding a stator, finding particular application in the automotive field.

[0002] The electrical machines used in thermal vehicles, for example alternators, operate at low voltage, i.e. at the supply voltage of the on-board network, which is of the order of 12V (Volts) or more. For such applications, the stators of these electrical machines conventionally comprise a so-called corrugated winding.

[0003] Such a stator consists of a yoke (also called stator body) generally formed from a packet of magnetic steel sheets, stacked axially, that is to say along the axis of rotation of the rotor of the electrical machine, namely a radial flux machine. The yoke has, on its internal circumference, angularly distributed notches passing axially through the stator, and in which the different conductors of the stator phases are inserted. For example, if the stator is three-phase, several notches out of a multiple of three consecutive notches will be filled by a distinct phase.

[0004] A phase comprises one or more conductors and forms undulations by insertion into the notches dedicated to this phase along the circumference of the stator, this circumference being traversed several times to radially fill the notches dedicated to this phase. In other words, several turns of winding of each phase are necessary to completely wind the stator, and obtain a number of “turns” corresponding to the desired electrical power.

[0005] The phase may comprise several conductors electrically connected in parallel or in series. In this case the multiple phase conductors are inserted at the same time into each notch dedicated to the phase, when winding the latter along the circumference of the stator.

[0006] Today, vehicles are mostly electrified, that is to say they each have at least one electric machine capable of delivering torque to the vehicle's wheels. Such an electric machine is powered by a high-voltage battery, that is to say a voltage greater than 60V.

[0007] The stators of such an electrical machine, as well as the windings of these stators, must be sized accordingly. In particular, to deliver the mechanical power necessary for traction or propulsion of the vehicle, such a stator may have several consecutive notches per stator phase, along its internal circumference. In order to allow the winding of such an electrical machine, multi-conductor phases are more preferred, because they are more flexible to transmit the same quantity of current as a conductive bar.

[0008] However, the inventors have observed, in such a case, overheating of the stator winding, the magnetic flux produced by the rotor inducing current differences between the different conductors of the same phase.

[0009] Figures 1 to 4 illustrate in particular winding elements of a stator 10 (referenced [Fig.3]) in which a stator body 12 comprises several consecutive notches filled by all of the conductors (referenced [Fig.2]) of the same phase 50, and presenting such a problem of overheating.

[0010] [Fig.l] represents a first notch el of a first series si (referenced [Fig.2]) of four notches, in which all the conductors of the same phase 50 have been inserted four times, that is to say on four layers of windings 11, 12, 13 and 14 corresponding to four passages of all the conductors on the circumference of the stator body 12, that is to say four turns of the winding of the stator body 12. By passage of a set of conductors of the same phase in this application, we mean a passage of these conductors on the circumference of the stator, that is to say a corrugated winding of the phase on a single turn of the stator, unless otherwise stated.

[0011] The first notch comprises two conductors 1 and 2 of phase 50, electrically connected in parallel, phase 50 comprising in all eight conductors 1, 2, 3, 4, 5, 6, 7 and 8 electrically connected in parallel and distributed in the different series of consecutive notches of the stator body 12 dedicated to phase 50.

[0012] [Fig.l] illustrates a change in arrangement of conductors 1 and 2 from notch el of the first series si of notches, to a notch el3 of a second series s2 (referenced [Fig.2]) of notches dedicated to phase 50. This change in position corresponds to an alternation of the radial position of conductors 1 and 2, and is due to the process of inserting the conductors of phase 50 into the corresponding notches, which uses a specific machine.

[0013] It should be noted that in the case of [Fig.l], the notches having a width (in the ortho-radial direction) corresponding to one conductor only, the arrangement of the conductors 1 and 2 in the notches is predictable taking into account the operation of the specific machine used to insert these conductors into the stator slots. This is generally not the case when a notch has a width of several conductors.

[0014] [Fig.2] schematically represents a flattened portion of the internal circumference of the stator body 12, on which only the phase 50 is wound by forming undulations of each of the conductors of phase 50. More precisely, phase 50 is represented by four pairs of conductors 51, 52, 53 and 54, the pair of conductors 51 comprising conductors 1 and 2 and being inserted in each first notch of a series si, s2 or s3 of notches dedicated to phase 50, the pair of conductors 52 comprising conductors 3 and 4 and being inserted in each second notch of a series si, s2 or s3 of notches dedicated to phase 50, the pair of conductors 53 comprising conductors 5 and 6 and being inserted in each third notch of a series si, s2 or s3 of notches dedicated to phase 50, and the pair of conductors 54 comprising conductors 7 and 8 and being inserted in each fourth and last notch of a series si, s2 or s3 notches dedicated to phase 50.

[0015] The numbering NI corresponds to the successive radial locations of the conductors in the notches of the stator body 12, eight distinct radial locations being numbered and corresponding to the four winding layers of the stator 10, the radial location 1 corresponding to the radial location proximal to the bottom of each notch, and the radial location 8 corresponding to the radial location proximal to the air gap of the electrical machine comprising the stator 10.

[0016] The numbering Ne corresponds to the successive angular positions (or to the angular numbering) of the notches on the internal circumference of the stator body 12, the first series si of notches dedicated to the phase 50 corresponding to the notches numbered 1 to 4, the second series s2 of notches dedicated to the phase 50 corresponding to the notches numbered 13 to 16 and the third series s3 of notches dedicated to the phase 50 corresponding to the notches numbered 25 to 28.

[0017] In the example of figures 1 to 4, the stator 10 therefore comprises three phases, and the stator body 12 comprises 48 notches, the conductors of a phase being wound in four series of four successive notches arranged along the internal circumference of the stator body 12.

[0018] In this application, S is the number of consecutive series of notches, dedicated to the winding of phase 50 along the circumference of the stator considered, K the number of consecutive notches per series of notches, L the number of winding layers in a notch and M the number of passages of the conductor along the circumference of the stator considered, to wind all of the conductors of phase 50. We therefore have in the example of FIGS. 1 to 4, S = 4, K = 4, L = 4 and M = 4.

[0019] Figures 3 and 4 illustrate seven successive positions 301 to 307 of a rotor of the electrical machine comprising the stator 10, during operation of this electrical machine. The rotor comprises four wound salient poles, exciting different conductors of the phase 50 in the positions 301 to 307 of the rotor. The pairs of conductors excited, that is to say receiving a consequent magnetic field produced by the rotor, are colored according to different textures depending on the pairs of conductors 51, 52, 53 or 54 concerned in phase 50. The pairs of conductors of the other phases of the stator 10 are not colored.

[0020] During the first position 301 of the rotor, the four poles of the rotor each approach a series of notches s1, s2, s3 or s4 dedicated to the phase 50, so that a part of each of the salient poles is opposite a first notch of such a series. As a result, conductors 1 and 2, in each first notch of the series s1, s2, s3 and s4 of notches, are subjected to a magnetic field which induces a non-negligible current in conductors 1 and 2. The current flowing in conductors 1 and 2 is therefore of a value distinct from the current flowing in conductors 3, 4, 5, 6, 7 and 8 which are not subjected to such a magnetic field, conductors 3, 4, 5, 6, 7 and 8 become receivers with respect to the current coming from conductors 1 and 2, which can cause heating of conductors 3, 4, 5, 6, 7 and 8 of low resistivity.

[0021] During the second position 302 of the rotor, a part of each of the salient poles of the rotor is opposite the first two notches of one of the series of notches dedicated to the phase 50. As a result, the pairs of conductors 51 and 52 are subjected to a magnetic field which induces a non-negligible current in the conductors 1, 2, 3 and 4. The difference in current flowing on the one hand in the conductors 1, 2, 3 and 4 and on the other hand 5, 6, 7 and 8 can cause heating of the conductors 5, 6, 7 and 8 even greater than that of the conductors 3 to 8 at the position 301 of the rotor since the current induced in the conductors 1, 2, 3 and 4 is doubled.

[0022] At the third position 303 of the rotor, a portion of each of the salient poles of the rotor is opposite the first three notches of one of the series of notches dedicated to phase 50. As a result, the pairs of conductors 51, 52 and 53 are subjected to a magnetic field which induces a significant current in the conductors 1, 2, 3, 4, 5 and 6. The difference in current flowing on the one hand in the conductors 1, 2, 3, 4, 5 and 6 and on the other hand 7 and 8 can cause heating of the conductors 7 and 8, also greater than that of the conductors 5, 6, 7 and 8 at the previous position 302 of the rotor, the current induced in the conductors 1, 2, 3, 4, 5 and 6 being tripled compared to the still previous position 301.

[0023] During the fourth position 304 of the rotor, each of the salient poles of the rotor is opposite the four notches of one of the series of notches dedicated to the phase 50. As a result, all the pairs of conductors of the conductor 50 are subjected to a current induced by the magnetic field of the rotor and are traversed by an approximately equal current, which causes little or no heating of the conductors of the phase 50.

[0024] At the fifth position 305 of the rotor, a portion of each of the salient poles of the rotor remains opposite the last three notches of one of the series of notches dedicated to phase 50. As a result, the pairs of conductors 52, 53 and 54 are subjected to a magnetic field which induces a significant current in the conductors 3, 4, 5, 6, 7 and 8. The difference in current flowing on the one hand in the conductors 1, 2 and on the other hand in the conductors 3, 4, 5, 6, 7 and 8 can cause heating of the conductors 1 and 2 of the same order as the heating observed at position 303 of the rotor for the conductors 7 and 8.

[0025] At the sixth position 306 of the rotor, a portion of each of the salient poles of the rotor remains opposite the last two notches of one of the series of notches dedicated to phase 50. As a result, the pairs of conductors 53 and 54 are subjected to a magnetic field which induces a significant current in the conductors 5, 6, 7 and 8. The difference in current flowing on the one hand in the conductors 1, 2, 3 and 4 and on the other hand in the conductors 5, 6, 7 and 8 can cause heating of the conductors 1, 2, 3 and 4 of the same order as the heating observed at position 302 of the rotor for the conductors 5, 6, 7 and 8.

[0026] Finally, during the seventh position 307 of the rotor, a part of each of the salient poles of the rotor remains opposite the last notch of each series of notches dedicated to the phase 50. As a result, the conductors 7 and 8 are subjected to a magnetic field inducing a significant current in these conductors. The difference in current flowing on the one hand in the conductors 7 and 8 and on the other hand in the other conductors of the phase 50 causes a heating of the conductors 1 to 6 of the same order of magnitude as the heating of the conductors 3 to 8 at the first position 301 of the rotor.

[0027] The table in [Fig.4] summarizes for each position 301 to 307 of the rotor mentioned above, the number of notches containing the different pairs of conductors 51, 52, 53 54, in which we find these subjected to a non-negligible induced current from the rotor.

[0028] The heating of the stator winding observed by the inventors does not occur when each phase is single-conductor or when it is multi-conductor connected in series and not in parallel and inserted in a single large slot per phase and per salient pole or pair of rotor poles (the rotor may have non-salient poles, and be for example magnetized). However, such designs have the disadvantages of greater difficulty in cooling the stator winding, and / or poor control of the positioning of the conductors in the slots, which can generate inhomogeneity of the winding which harms the performance of the machine.

[0029] The inventors' analysis of the operation of the wound electric machine presented in relation to Figures 1 and 4, has enabled the inventors to remedy at least in part the aforementioned drawbacks by providing an electric machine stator and a method of winding a body of such an electric machine stator, which allows less heating of the winding and therefore limits the cooling requirements of the winding.

[0030] To this end, the invention proposes an electrical machine stator formed from a wound stator body, the stator comprising at least three phases, the circumference of the stator body comprising S series of K consecutive notches per phase, the winding of the notches of the same phase being formed from several conductors electrically connected in parallel, different conductors of the phase being present in at least two of the K notches of a series of K notches, said different conductors corresponding to the same passage of the phase on the circumference of the stator body, the stator being characterized in that given any k-th notch position, each of the conductors of the phase is present at the k-th notch position in at least one of the S series of K notches.

[0031] The stator according to the invention is here that of a radial flux machine, the stator body being able to be identical to a stator body of the prior art, provided that it has several series of consecutive notches per phase, for example 4 series of 4 consecutive notches as in figures 1 to 4, or else 8 series of four consecutive notches, the numbers S and K being arbitrary but strictly greater than 1. In addition, the number S is in fact equal to the number of poles of the rotor opposite the stator according to the invention (in particular S = 4 = number of salient poles in the case of figures 3 and 4). The stator body comprises notches axially crossing its internal circumference, and is for example of cylindrical shape and made of magnetic steel sheets. In variants it can be in one piece or in several parts, made of simple steel and / or of parallelepipedal external shape.

[0032] It should be noted that in this patent application, the term "axial" (or "axial" in the plural) refers, unless otherwise stated, to a direction parallel to the rotating axis of the rotor of the electrical machine in question or to a position along this direction. Similarly, the term "radial" (or "radial" in the plural) refers, unless otherwise stated, to a direction orthogonal to the rotating axis of the rotor of the electrical machine in question, and secant to this rotating axis, or to a position along this direction. Finally, the terms "angular" or "ortho-radial" (or "ortho-radial" in the plural) refer, unless otherwise stated, to a direction orthogonal to the axial direction and to a radial direction, or to a position along this direction, which is in fact rotating around the rotating axis of the rotor.

[0033] The stator winding according to the invention is formed by several passages of the phase on the circumference of the stator body, i.e. several turns of winding, different conductors of the phase being inserted once in each passage in at least two notches of each series of notches dedicated to the phase. Several passages are necessary to wind the entire phase. The other phases constituting also the windings are of course wound in a similar manner, the stator comprising multi-conductor phases. The different phases of the stator are preferably, but not necessarily, wound at the same time.

[0034] The stator according to the invention being mainly intended to form an electric traction or automobile propulsion machine, it preferably comprises three phases, but as a variant it can comprise more phases, for example six phases.

[0035] Finally, the k-th notch position corresponds to a distinct angular position of a notch in any series of K notches, so there are K k-th distinct angular positions per phase.

[0036] According to the invention, for each k-th notch position, each conductor of the phase of the stator wound according to the invention is found in at least one of the series of notches at this k-th position. Thus, when the poles of the rotor are each located opposite the k-th notch of each series of notches dedicated to the phase, each conductor of the phase is excited in a non-negligible manner by at least one of the poles of the rotor, which makes it possible to reduce the differences in current flowing between the different conductors of the phase, and therefore to reduce heating of the winding of the stator according to the invention.

[0037] The notches of the stator according to the invention may comprise several layers of winding. For example, in the stator of an electric machine according to the invention, each notch comprises L layers of winding formed by M passages of the phase on the circumference of the stator body, - a winding layer on a series of K notches corresponding to several phase passages, the different phase conductors in each winding layer on the same series of K notches then being present several times, or - a winding layer on a series of K notches corresponding to a single phase passage, the different conductors in each winding layer on the same series of K notches then being present only once.

[0038] In the first case, the phase comprises for example only one or two conductors in parallel per notch for only part of the series of K notches, a first pass of the phase is therefore not sufficient to fill all the notches, and one or more other passes are necessary to wind the notches not wound during the first pass. For example the phase comprises four conductors in parallel, inserted two by two at each pass in only two notches of a series of four notches, two passes are therefore necessary to wind the series of four notches on a winding layer, two of the notches of the series of notches therefore comprising an electrical supply in series with the other two notches of the series of notches. In the first case, M is therefore a non-unit multiple of L, that is to say is at least twice L.

[0039] In the second case, the phase comprises at least one conductor per notch of a series of K notches, for example two conductors are inserted per notch and per passage, the phase then having K*2 conductors electrically connected in parallel, and the number M of passages of the phase on the circumference of the stator is equal to the number L of winding layers.

[0040] According to an optional but advantageous characteristic of the invention, each of the conductors is present at the k-th notch position M*S / K times. This makes it possible to angularly homogenize the excitation of the different conductors by the rotor, and therefore to allow less heating of the winding, which makes it possible to improve the electrical and magnetic performances of the electrical machine.

[0041] For example, with M equal to L and 4, S equal to 8 and K equal to 4, each of the conductors is present eight times at a first notch position of at least two (since there are only four winding layers) of the eight series of notches dedicated to the phase, eight times at a second notch position of at least two of the eight series of notches dedicated to the phase, eight times at a third notch position of at least two of the eight series of notches dedicated to the phase, and eight times at a fourth and final notch position of at least two of the eight series of notches dedicated to the phase. In particular, each first notch of each series contains this conductor, or else certain first notches contain this conductor and others do not. The same is true for the second, third and fourth notches of each series.

[0042] In another example with M equal to 8, L equal to 4, S equal to 8 and K equal to 4, each of the conductors is present sixteen times at a first notch position of at least four (since two passes are required to fill the four winding layers) of the eight series of notches dedicated to the phase, sixteen times at a second notch position of at least four of the eight series of notches dedicated to the phase, sixteen times at a third notch position of at least four of the eight series of notches dedicated to the phase, and sixteen times at a fourth and last notch position of at least four of the eight series of notches dedicated to the phase. In particular, each first notch of each series contains this conductor twice, or else certain first notches contain this conductor and others do not. The same is true for the second, third and fourth notches of each series.

[0043] According to another optional but advantageous characteristic of the invention, given any 1st layer of winding, each of the conductors is present in this 1st layer (M*S) / (K*L) times at the kth notch position. This makes it possible to radially homogenize the distribution of the magnetic fields to the different conductors of the phase, and therefore to have increased electrical and magnetic performances of the electrical machine comprising the stator according to the invention. Indeed, the magnetic fields which induce currents in the conductors of the phases vary according to the different layers of the winding, thus generating different currents according to the different layers of winding.

[0044] In one embodiment of the invention, each passage of the phase corresponds to the insertion of a pair of two of the conductors electrically connected in parallel into each of said at least two of the K notches. For example, with a phase with four conductors electrically connected in parallel and K equal to 4, at each passage of the phase around the circumference of the stator body, two notches are wound per series of K notches per passage, each of the two notches receiving two conductors per passage and two passages making it possible to produce a winding layer. In another example, with a phase with eight conductors electrically connected in parallel and K equal to 4, at each passage of the phase around the circumference of the stator body, two conductors are inserted into each of the notches of the series of K notches. Inserting two conductors per notch at each turn of the winding makes it easier and makes the winding process faster.

[0045] In this embodiment of the invention, each notch preferably accommodates only one of the conductors in its width, the conductors of each pair of conductors being arranged radially at different positions in the notch. This makes it possible to better control the radial position of the conductors when winding them. In this embodiment, the notch has a width, in the angular direction, of one conductor, and the thickness of a winding layer in the radial direction is two conductors. In an alternative embodiment, when, on the contrary, the notch has a width, in the angular direction, of two conductors, the thickness of a winding layer in the radial direction is a single conductor, each passage of the conductor in the notch corresponding to the insertion of a pair of two conductors in the notch.

[0046] Furthermore, in this embodiment of the invention where the notch is the width of a single conductor, preferably each pair of conductors is present in a 1-th layer (M*S) / L times, the radial positions of the conductors of the pair of conductors in this 1-th layer being permuted between different notches comprising this pair of conductors in this 1-th layer. These radial permutations are carried out so as to radially homogenize the distribution of the magnetic fields to the different conductors of the same pair, they are therefore carried out regularly or at least so that each conductor of a pair of conductors shares the same radial position with the other conductor of the pair of conductors, the same number of times. These permutations take place within the same series of notches or from one series of notches to another series of notches.

[0047] The invention also relates to a method for winding a stator body of an electrical machine comprising at least three phases, the circumference of the stator body comprising S series of K consecutive notches per phase, the method comprising, for the notches of the same phase, a step of winding the notches, the winding step comprising M passages on the circumference of the same phase formed of several conductors electrically connected in parallel, each passage inserting different conductors of the phase in at least two of the K notches per series of K notches, the method being characterized in that given any k-th notch position in a series of K notches, each of the conductors is inserted at this k-th notch position in at least one of the S series of K notches.

[0048] This winding method makes it possible to obtain a stator according to the invention. It uses a multi-conductor phase per phase of the electrical machine, the phases preferably being wound at the same time on the stator body.

[0049] The stator winding is preferably multi-layer to obtain the mechanical power necessary for the propulsion or traction of a vehicle. The winding step therefore preferably forms in each notch, L winding layers, each winding layer on a series of K notches being formed by one or more passages of the phase in the series of K notches. When several passages of the phase are necessary to form a winding layer on a series of notches, the length of the multi-conductor phase is a multiple of the length of a multi-conductor phase allowing such a winding layer to be formed by a single passage.

[0050] According to an optional but advantageous characteristic of the invention, each conductor of the phase forms, during a passage of the phase from one series of K notches to another, a corrugation capable of forming a surface intended to be crossed by a magnetic field, of different amplitude depending on the series of K notches considered, the notch positions corresponding to the conductor in each series of K notches being chosen so that the average of the amplitudes of the surfaces thus formed for the conductor during the winding step is identical for each conductor. This characteristic makes it possible to homogenize the magnetic flux transmitted to the rotor or transmitted by the rotor (depending on the motor or generator mode of operation of the electrical machine) so that it is the same between each pair of consecutive series of notches, and therefore not to degrade the electrical and magnetic performances of the electrical machine.

[0051] In one embodiment of the invention, as mentioned above in relation to the stator according to the invention, each passage of the phase corresponds to the insertion of a pair of two of the conductors electrically connected in parallel in each of said at least two of the K notches.

[0052] In this embodiment of the invention, each notch housing only one of the conductors in its width, the winding step comprises a step of permuting the radial position of the conductors of a pair of conductors, of a notch of a series of K slots to another slot in the same series of K slots or in another series of K slots. This permutation is carried out when winding one or more winding layers, each winding layer possibly requiring one or more passes of the phase around the circumference of the stator body.

[0053] In an exemplary embodiment of the invention, each passage of the phase forms a winding layer over a series of K notches, and the winding step comprises a permutation step consisting of inserting, during a passage, the conductors into the notches of a series of K notches, according to a distribution from 1 to K of the conductors, inverse of a distribution from K to 1 of the same conductors in the previous series of K notches.

[0054] In other words, in this first type of angular permutation, conductors numbered 1 to K follow each other angularly in this order in the same winding layer in a clockwise direction, in the K notches of the series of notches, the same conductors following each other angularly from the conductor numbered K to the conductor numbered 1 in this order in the same winding layer in a clockwise direction, in the K notches of the previous series of notches. This permutation allows optimization of the shapes of the connections between the conductors of 2 consecutive series of K notches outside the notches. In particular, it allows minimizing the crossings of the conductors and thus reducing the thickness of the stator bun.

[0055] In another exemplary embodiment of the invention, the winding step comprises a permutation step consisting of inserting the conductors, during a phase transition, two by two according to two consecutive notch positions of a series of K notches, inverses of their notch positions in the previous series of K notches, the conductors corresponding to this transition in the series of K notches thus being two by two inverted with respect to the previous series of K notches.

[0056] In other words, in this second type of angular permutation, the K notches of each series of notches on a winding layer being divided into pairs of two successive notches, the conductors located in a first of the two successive notches of a pair of notches in the series of notches are found in the second of the two successive notches of the pair of notches in the previous series of notches. This permutation allows an optimization of the shapes of the connections between the conductors of two consecutive series of K notches outside the notches. It allows in particular to reduce the thickness of the stator bun, by crossings distributed angularly regularly between the different pairs of conductors.

[0057] The different types of permutations mentioned above are for example carried out from one series of notches to another, during the same passage of the phase or between two phase transitions, for example when forming a new winding layer, the different winding layers of the same slot being able to contain different conductors corresponding to different phase transitions. Several types of permutations can be carried out simultaneously or alternately from one series of slots to another series of slots during the same phase transition if they are not incompatible, in particular a radial permutation and an angular permutation.

[0058] Furthermore, according to an optional but advantageous characteristic of the winding method according to the invention, during the winding step, each of the conductors is inserted at the k-th notch position M*S / K times. Preferably during this winding step, given any 1-th winding layer, each of the conductors is present in this 1-th layer (M*S) / (K*L) times at the k-th notch position.

[0059] According to one of the optional characteristics of the invention, at least one of the conductors is a multi-strand Litz wire.

[0060] The winding method according to the invention has advantages similar to those of the electric machine stator according to the invention.

[0061] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0062] [Fig-1] already described in relation to the prior art, illustrates notches of a body of a stator of an electric machine,

[0063] [Fig.2] already described in relation to the prior art, schematically represents a winding of the phase on a flattened portion of the internal circumference of the stator body of [Fig.l],

[0064] [Fig.3] already described in relation to the prior art, illustrates six successive positions of a rotor of the electric machine of figures 1 and 2, during operation of this electric machine,

[0065] [Fig.4] already described in relation to the prior art, represents a seventh position of the rotor in the electrical machine of figures 1 to 3, as well as a representative table of a quantity of conductors of a multi-conductor phase of the stator, excited by the rotor per conductor concerned of the phase and per position of the rotor illustrated figures 3 and 4,

[0066] [Fig.5] schematically represents a winding according to the invention of a multi-phase conductors on a flattened portion of the internal circumference of a body of a stator of an electric machine according to the invention, in one embodiment of the invention,

[0067] [Fig.6] illustrates six successive positions of a rotor of the electric machine of the [Fig.5], during operation of this electric machine, in this embodiment of the invention,

[0068] [Fig.7] illustrates a seventh position of the rotor of the electric machine of figures 5 and 6, as well as a representative table of a quantity of conductors of a multi-conductor phase represented [Fig.5], excited by the rotor, by relevant conductor of the phase and by position of the rotor as illustrated in figures 6 and 7,

[0069] [Fig.8] represents the distribution of the conductors of a multi-conductor phase in different series of notches of a stator of an electric machine according to the invention, in another embodiment of the invention,

[0070] [Fig.9] represents an example of radial permutation carried out from a series from one notch to another in the electric machine of [Fig.8],

[0071] [Fig. 10] represents a first type of angular permutation carried out from one series of notches to another in the electric machine of [Fig.8],

[0072] [Fig. 11] represents a second type of angular permutation carried out from one series of notches to another in the electric machine of [Fig.8], and

[0073] [Fig. 12] represents a distribution of the conductors of a multi-conductor phase of a wound stator according to yet another embodiment of the invention.

[0074] According to a first embodiment of the invention shown with reference to Figures 5 to 7, a stator 20 (referenced [Fig.6]) according to the invention comprises a stator body, identical to that of Figures 1 to 4, but this stator body 12 is wound differently in the stator 20 according to the invention compared to the stator 10 of Figures 1 to 4. As a result, the elements of Figures 1 and 4 identical to those of Figures 5 to 7 are referenced in the same way.

[0075] The stator 20 comprises three phases, each multi-conductor phase, each multi-conductor phase being in its structure, identical to the phase 50 of [Fig.2], but in the invention the conductors of each multi-conductor phase 50 are arranged differently in the notches of the stator body 12, as shown [Fig.5]. In [Fig.5], the eight conductors of such a phase 50, electrically connected in parallel, are grouped according to the pairs of conductors 51, 52, 53 and 54, and inserted two by two in each notch of the four series s1 to s4 of four notches of the stator body 12 dedicated to this phase 50.

[0076] In this first embodiment, all the notches of the same series of notches of the stator body 12 are wound at the same time. We therefore have S = 4, M = L = 4, and K = 4.

[0077] In this first embodiment of the invention:

[0078] - the pair of conductors 51 of phase 50 is inserted first into the first notch el of the first series of notches si, then in the fourth notch of the second series of notches s2, then in the third notch of the third series of notches s3, then in the second notch of the fourth series of notches s4;

[0079] - the pair of conductors 52 of phase 50 is inserted first in the second notch of the first series of notches si, then in the third notch of the second series of notches s2, then in the fourth notch of the third series of notches s3, then in the first notch of the fourth series of notches s4;

[0080] - the pair of conductors 53 of the phase 50 is inserted first in the third notch of the first series of notches si, then in the second notch of the second series of notches s2, then in the first notch of the third series of notches s3, then in the fourth notch of the fourth series of notches s4;

[0081] - the pair of conductors 54 of the phase 50 is inserted first in the fourth notch of the first series of notches si, then in the first notch el3 of the second series of notches s2, then in the second notch of the third series of notches s3, then in the third notch of the fourth series of notches s4.

[0082] Each pair of conductors therefore completely fills a first notch (i.e. all the layers of windings of this notch) of one of the series of notches si to s4, a second notch of one of the series of notches si to s4, a third notch of one of the series of notches si to s4 and a fourth notch of one of the series of notches si to s4.

[0083] Since the notches have the width of a single conductor, the radial positions of the conductors in each pair of conductors can only be different in each notch. In this first embodiment, the radial position of a conductor in a pair of conductors is the same from one series of notches to another. Alternatively, this radial position is alternated from one series of notches to another, i.e. in the first winding layer corresponding to the radial locations NI 1 and 2, the conductor 1 is at radial location 1 in the first series of notches si, but is at radial location 2 in the second series of notches s2, while the conductor 2 is at radial location 2 in the first series of notches si, but is at radial location 1 in the second series of notches s2.

[0084] As visible in [Fig.5], the pairs of conductors 51, 52, 53, 54 form undulations of different widths (in the angular direction) between two consecutive series of notches. Nevertheless, on the circumference of the stator 20, the averages of the widths of the undulations formed by the pairs of conductors 51, 52, 53 and 54 are identical, so that the magnetic flux produced between each pair of consecutive series of notches by the phase 50 in the stator 20 is identical in amplitude from one pair of consecutive series of notches to another. In addition, the fact that the averages of the widths of the undulations are identical makes it possible to have the same lengths of conductors and therefore the same electrical resistances between the different conductors placed in parallel, thus minimizing problems of electrical imbalances which can cause the conductors to heat up.

[0085] Figures 6 and 7 illustrate seven successive positions 301 to 307 of a rotor of the electrical machine comprising the stator 20, during operation of this electrical machine, these positions and the rotor being identical to those of Figures 3 and 4. The excited pairs of conductors, that is to say receiving a significant magnetic field produced by the rotor, are colored according to different textures depending on the pairs of conductors 51, 52, 53 or 54 concerned in phase 50. The pairs of conductors of the other phases of the stator 20 are not colored.

[0086] During the first position 301 of the rotor, the four poles of the rotor each approach a series of notches s1, s2, s3 or s4 dedicated to the phase 50, so that a part of each of the salient poles is opposite a first notch of such a series. Given the arrangement of the pairs of conductors 51, 52, 53 and 54 of the phase 50 in these first notches, each of these pairs of conductors is excited in a non-negligible manner by the rotor in this first position 301, in a homogeneous manner. More precisely, four winding layers of each of the pairs of conductors 51, 52, 53 and 54 receive the magnetic flux from the rotor. No overheating of the conductors due to a difference in current flowing in the different conductors of the phase 50 is therefore to be observed.

[0087] During the second position 302 of the rotor, a part of each of the salient poles of the rotor is opposite the first two notches of one of the series of notches dedicated to the phase 50. Given the arrangement of the pairs of conductors 51, 52, 53, 54 in these notches, eight winding layers of each of the pairs of conductors 51, 52, 53, 54 receive the magnetic field of the rotor in an equivalent manner. As a result, no overheating of the conductors occurs.

[0088] During the third position 303 of the rotor, a part of each of the salient poles of the rotor is opposite the first three notches of one of the series of notches dedicated to the phase 50. In this configuration, twelve winding layers of each of the pairs of conductors 51, 52, 53, 54 receive the magnetic field of the rotor in an equivalent manner. As a result, no overheating of the conductors occurs.

[0089] In the fourth position 304 of the rotor, each of the salient poles of the rotor is opposite the four notches of one of the series of notches dedicated to the phase 50. In this configuration, sixteen winding layers of each of the pairs of conductors 51, 52, 53, 54 receive the magnetic field of the rotor in an equivalent manner. As a result, no overheating of the conductors occurs.

[0090] During the fifth position 305 of the rotor, a part of each of the salient poles of the rotor remains opposite the last three notches of one of the series of notches dedicated to phase 50. In this configuration, twelve layers of winding of each pairs of conductors 51, 52, 53, 54 receive the magnetic field of the rotor in an equivalent manner. As a result, no overheating of the conductors occurs.

[0091] During the sixth position 306 of the rotor, a part of each of the salient poles of the rotor remains opposite the last two notches of one of the series of notches dedicated to the phase 50. In this configuration, eight winding layers of each of the pairs of conductors 51, 52, 53, 54 receive the magnetic field of the rotor in an equivalent manner. As a result, no overheating of the conductors occurs.

[0092] Finally, during the seventh position 307 of the rotor, illustrated [Fig.7], a part of each of the salient poles of the rotor remains opposite the last notch of each series of notches dedicated to the phase 50. In this configuration, four layers of winding of each of the pairs of conductors 51, 52, 53, 54 receive the magnetic field of the rotor in an equivalent manner.As a result, there is no overheating of the conductors.

[0093] The table in [Fig.7] summarizes, for each position 301 to 307 of the rotor in the stator 20, the number of winding layers by different pairs of conductors 51, 52, 53 54, in which we find these subjected to a non-negligible induced current of the rotor, divided by four. It can be seen that even if the number of winding layers excited by the rotor during the different positions varies, this number of winding layers of phase 50 concerns the same quantity of each conductor of phase 50. This makes it possible to avoid overheating of phase 50 during operation of the electrical machine comprising the stator 20. Even if this number of layers was not identical for all the conductors for the same position of the rotor, the fact that all the conductors are excited at the same time reduces overheating compared to the prior art.

[0094] [Fig.8] represents a distribution of the conductors 1 to 8 of a phase in the 96 slots of a stator according to a second embodiment of the invention, in which the stator has eight successive series S1 to S8 of four slots. In this second embodiment of the invention, the conductors are wound in pairs in each of the slots of each series of slots at each winding turn, four layers of winding L1, L2, L3 and L4 making it possible to fill all the slots. In other words, in this second embodiment, L = M = 4, S = 8 and K = 4.

[0095] The Ne lines include a numbering of the notches along the circumference of the stator. The k / K lines give the k-th position values of each notch in a series of K notches.

[0096] Each notch has a width of a single conductor, the conductors of each pair of conductors wound during a single passage of the conductor in a notch having a radial positioning which varies homogeneously along the circumference of the stator. In particular, conductors 1 and 2 are each located on the first line of the winding layer L1 four times, on four k-th distinct slots, and each on the second row of winding layer L1 four times, on four k-th distinct slots. The same is true when considering the other winding layers L2, L3, L4, and each of the other conductors 3, 4, 5, 6, 7, 8 on each of the winding layers. Each pair of conductors is distributed twice on each of the four k-th slot positions, on the same winding layer.

[0097] This second embodiment has the advantage, compared to the first embodiment, of optimizing the placement of the conductors radially. Since the magnetic fields are greater for the conductors that are closest to the rotor, it is possible, by optimizing the distribution of the conductors radially on the different winding layers, to homogenize on the different conductors the differences in magnetic fields relative to the distance from the rotor, in particular concerning the conductors of the same pair of conductors.

[0098] [Fig.9] schematically represents an example of radial permutation carried out from a series S2 of notches numbered 21 to 24, to another series S3 of notches numbered 33 to 36. For greater visibility, in this example, in each winding layer and each notch of the series S2 of notches, the radial positions of the conductors of the pair of conductors in this winding layer and in this notch are reversed with respect to the radial positions of these conductors in the corresponding winding layer and in the notch of the series S3 of notches. This permutation is simple to implement, the conductors being permuted only radially and two by two.

[0099] The [Fig. 10] schematically represents a first type of angular permutation carried out from a series S3 of notches numbered 33 to 36 to another series S4 of notches numbered 45 to 48. For greater visibility, in this example, each winding layer undergoes the same angular permutation, which consists of placing the pair of conductors present in the first notch of the series S3 of notches 33 to 36, in the last notch of the series S4 of notches 45 to 48, to place the pair of conductors present in the second notch of the series S3 of notches 33 to 36 in the penultimate notch of the series S4 of notches 45 to 48, and so on until placing the pair of conductors present in the last notch of the series S3 of notches 33 to 36, in the first notch of the S4 series of notches 45 to 48.In this first type of angular permutation, the radial positions of the conductors of the same pair of conductors are not modified from the S3 series of notches 33 to 36 to the S4 series of notches 45 to 48.

[0100] [Fig. 11] schematically represents a second type of angular permutation carried out from a series S5 of notches numbered 57 to 60 to another series S6 of notches numbered 69 to 72. For greater visibility, in this example, each winding layer undergoes the same angular permutation, which consists of permuting two by two the angular positions of the pairs of conductors in two consecutive notches of the series S6 of notches 69 to 72 with respect to the two corresponding consecutive notches of the series S5 of notches 57 to 60. Thus the pair of conductors 7,8 which is in the first notch 57 of the series S5 of notches, is found in the second notch 70 of the series S6 of notches, the pair of conductors 5,6 which is in the second notch 58 of the series S5 of notches, is found in the first notch 69 of the series S6 of notches, the pair of conductors 3,4 which is in the third notch 59 of the series S5 of notches, is found in the fourth notch 72 of the series S6 of notches and the pair of conductors 1,2 which is in the fourth notch 60 of the S5 series of notches, is found in the third notch 71 of the S6 series of notches.In this second type of angular permutation, the radial positions of the conductors of the same pair of conductors are not modified from the S5 series of notches 57 to 60 to the S6 series of notches 69 to 72.

[0101] It can be seen that the distribution of the phase conductors on the winding layers L1 and L3 of [Fig.8] is obtained by alternating a radial permutation (of series S2 to S3, S4 to S5, S6 to S7 and S8 to SI) and an angular permutation of the first type (of series S3 to S4 and S7 to S8) or of the second type (of series S5 to S6 and SI to S2), these two types of angular permutation alternating in turn between two radial permutations, that is to say that each type of angular permutation is carried out every four series of notches.

[0102] Similarly, the distribution of the phase conductors on the winding layers L2 and L4 of [Fig.8] is obtained by alternating a radial permutation (of series S3 to S4, S5 to S6, S7 to S8 and SI to S2) and an angular permutation of the first type (of series S4 to S5 and S8 to SI) or of the second type (of series S2 to S3 and S6 to S7), these two types of angular permutation alternating in turn between two radial permutations, that is to say that each type of angular permutation is carried out every four series of notches.

[0103] These alternations between the different permutations from one series of notches to another make it possible to distribute the pairs of conductors in a homogeneous manner in the four consecutive notches, thus avoiding the heating phenomena observed initially, while having a simple and repeatable permutation mechanism.

[0104] [Fig. 12] shows a distribution of the conductors 1 to 4 of a phase 60 comprising only four conductors electrically connected in parallel, in the 96 slots of a stator according to a third embodiment of the invention, in which the stator body, identical to that of figures 8 to 11, has eight series S1 to S8 of four slots. The numbering of the slots and series of slots of the stator body stator is therefore identical to that of [Fig.8].

[0105] In this third embodiment of the invention, the conductors 1 to 4 are wound in pairs in only two of the slots of each series of slots at each winding turn, so eight winding turns are required to fill the four winding layers L10, L20, L30 and L40 of all the slots. In other words, in this third embodiment, L = 4, M = 8, S = 8 and K = 4.

[0106] In this third embodiment of the invention, the conductors of each pair of conductors wound during the same passage of the phase in a notch have a radial positioning which varies homogeneously along the circumference of the stator. In particular, conductors 1 and 2 are each located on the first line of the winding layer L10 eight times, including twice on four k-th distinct notches, and each on the second line of the winding layer L10 eight times, including twice on four k-th distinct notches. The same applies when considering the other winding layers L20, L30, L40, and each of the other conductors 3 and 4 on each of the winding layers. Each pair of conductors is distributed four times on each of the four k-th notch positions, on the same winding layer.

[0107] Winding only two notches of each series at each passage of the phase on the circumference of the stator body makes it possible to carry out more permutations on the same series of notches.

[0108] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the characteristics of the different embodiments or variants of the invention envisaged in this application can be combined to achieve the invention, to the extent that these embodiments or variants are not incompatible with each other. In addition, the phase can have a different number of eight or four conductors electrically connected in parallel, the number of notches per series of notches or winding layers can be different from four. Finally, the conductors are not necessarily of round or copper section, they can be of rectangular section.

Claims

Claims

1. Stator (20) of an electric machine formed from a wound stator body (12), the stator (20) comprising at least three phases, the circumference of the stator body (12) comprising S series (si, s2, s3, s4, SI, S2, S3, S4, S5, S6, S7, S8) of K consecutive notches per phase, the winding of the notches (el, el3) of the same phase (50, 60) being formed from several conductors (1, 2, 3, 4, 5, 6, 7, 8) electrically connected in parallel, different conductors of the phase (50, 60) being present in at least two of the K notches of a series of K notches, said different conductors corresponding to the same passage of the phase (50, 60) on the circumference of the stator body (12), the stator (20) being characterized in that given any k-th notch position, each of the phase conductors (50, 60) is present at the k-th notch position in at least one of the S series of K notches.

2. Stator (20) of an electric machine according to claim 1, in which each notch (el, el3) comprises L layers of winding (Ll, L2, L3, L4, L10, L20, L30, L40) formed by M passages of the phase (50, 60) on the circumference of the stator body (12), - a layer of winding (L10, L20, L30, L40) on a series (S1, S2, S3, S4, S5, S6, S7, S8) of K notches corresponding to several passages of the phase (60), the different conductors of the phase in each layer of winding on the same series of K notches then being present several times, or - a layer of winding (Ll, L2, L3, L4) on a series of K notches corresponding to a single passage of the phase (50), the different conductors of the phase in each layer of winding on the same series of K notches then being present only once.

3. An electric machine stator (20) according to claim 2, wherein each of the conductors is present at the k-th notch position M*S / K times.

4. An electric machine stator (20) according to claim 3 wherein, given any 1-th winding layer (L1, L2, L3, L4, L10, L20, L30, L40), each of the conductors is present in this 1-th layer (M*S) / (K*L) times at the k-th slot position.

5. Stator (20) of an electric machine according to any one of claims 2 to 4, in which each passage of the phase (50, 60) corresponds to the insertion of a pair of two of the conductors electrically connected in parallel into each of said at least two of the K notches.

6. Stator (20) of an electric machine according to claim 5, in which each notch (el, el3) housing only one of the conductors in its width, the conductors of each pair of conductors are arranged radially at different positions in the notch.

7. An electric machine stator (20) according to claims 2 and 6, wherein each pair of conductors being present in a 1-th layer (M*S) / L times, the radial positions of the conductors of the pair of conductors in this 1-th layer are permuted between different notches having this pair of conductors in this 1-th layer.

8. Method for winding a stator body (12) of an electric machine comprising at least three phases, the circumference of the stator body (12) comprising S series (si, s2, s3, s4, SI, S2, S3, S4, S5, S6, S7, S8) of K consecutive notches per phase, the method comprising, for the notches (el, el3) of the same phase, a step of winding the notches, the winding step comprising M passages on the circumference of the same phase (50, 60) formed of several conductors (1, 2, 3, 4, 5, 6, 7, 8) electrically connected in parallel, each passage inserting different conductors of the phase (50, 60) into at least two of the K notches per series of K notches, the method being characterized in that given any k-th position notch in a series of K notches, each of the conductors is inserted at this k-th notch position in at least one of the S series of K notches.

9. Method for winding a body (12) of an electric machine stator according to the preceding claim, in which the winding step forms in each notch, L winding layers (L1, L2, L3, L4, L10, L20, L30, L40), each winding layer on a series of K notches being formed by one or more passages of the phase (50, 60) in the series of K notches.

10. Method for winding a body (12) of an electric machine stator according to claim 8 or 9, in which each conductor of the phase (50, 60) forms, during a passage of the phase from one series of K notches to another, a corrugation capable of forming a surface intended to be crossed by a magnetic field, of different amplitude depending on the series of K notches considered, the notch positions corresponding to the conductor in each series of K notches being chosen so that the average of the amplitudes of the surfaces thus formed for the conductor during the winding step is identical for each conductor.

11. A method of winding an electrical machine stator body (12) according to any one of claims 8 to 10, wherein each passage of the phase (50, 60) corresponds to the insertion of a pair of two of the conductors electrically connected in parallel into each of said at least two of the K notches.

12. A method of winding an electric machine stator body (12) according to claim 11, wherein each notch (el, el3) housing only one of the conductors in its width, the winding step comprises a step of permuting the radial position of the conductors of a pair of conductors, from one notch of a series of K notches to another notch of the same series of K notches or of another series of K notches.

13. A method of winding an electric machine stator body (12) according to any one of claims 8 to 12, wherein each passage of the phase (50) forms a winding layer over a series of K notches, and wherein the winding step comprises a permutation step consisting of inserting, during a passage, the conductors into the notches of a series of K notches, according to a distribution from 1 to K of the conductors, inverse of a distribution from K to 1 of the same conductors in the previous series of K notches.

14. Method for winding a body (12) of an electric machine stator according to any one of claims 8 to 12, in which the winding step comprises a permutation step consisting of inserting the conductors, during a passage of the phase (50, 60), two by two according to two consecutive notch positions of a series of K notches, inverses of their notch positions in the previous series of K notches, the conductors corresponding to this passage in the series of K notches thus being two by two inverted with respect to the previous series of K notches.

15. A method of winding an electric machine stator body (12) according to any one of claims 8 to 14, wherein in the winding step, each of the conductors is inserted at the k-th notch position M*S / K times.

16. A method of winding an electric machine stator body (12) according to any one of claims 9 to 15, wherein given any 1-th winding layer (L1, L2, L3, L4, L10, L20, L30, L40), each of the conductors is present in this 1-th layer (M*S) / (K*L) times at the k-th slot position.

17. A method of winding an electric machine stator body (12) according to any one of claims 1 to 16, wherein at least one of the conductors is a multi-strand Litz wire.

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