Patent Publication Number: US-2018034351-A1

Title: Method for winding a stator of a rotary electrical machine, and corresponding wound stator

Description:
The present invention relates to a method for winding a stator of a rotary electrical machine, as well as to the corresponding wound stator. The invention has a particularly advantageous application for a stator of a rotary electrical machine, such as, for example, an alternator, an alternator-starter, or an electric motor. 
     In a known manner, rotary electrical machines comprise a stator and a rotor integral with a shaft. The rotor can be integral with a driving and/or driven shaft, and can belong to a rotary electrical machine in the form of an alternator, as described in document EP0803962, or an electric motor as described in document EP0831580. The electrical machine comprises a casing which supports the stator. This casing is also configured to rotate the shaft of the rotor, for example by means of bearings. 
     This alternator comprises in particular a housing, and, inside the latter, a claw rotor which is integral in rotation directly or indirectly with a shaft, and a stator, which surrounds the rotor with the presence of a small air gap. The rotor comprises a coil and a pair of magnet wheels consisting of a cylindrical portion which supports the coil of the rotor, as well as disc portions which extend from the ends of the cylindrical portion. In addition, a plurality of magnetic poles in the form of claws extend axially from the said disc portions, such as to cover the rotor coil. The claws of one magnet wheel face axially towards the other magnet wheel, with the claw of one magnet wheel penetrating in the space which exists between two adjacent claws of the other magnet wheel, such that the claws of the magnet wheels are imbricated relative to one another. The outer periphery of the claws has axial orientation, and defines with the inner periphery of the stator body the air gap between the stator and the rotor. The inner periphery of the claws is inclined, the claws being thinner at their free end. 
     As a variant, the rotor comprises a body formed by a stack of sheets of metal plates which are retained in the form of a set by means of an appropriate securing system, such as rivets which pass through the rotor axially from one side to the other. The rotor comprises poles which are formed for example by permanent magnets accommodated in cavities provided in the magnetic mass of the rotor, as described for example in document EP0803962. Alternatively, in a so-called “projecting” poles architecture, the poles are formed by coils which are wound around arms of the rotor. 
     The stator comprises a body constituted by a stack of thin metal plates, as well as a phase winding which is received in the notches of the stator which are open towards the interior. There are generally three or six phases. In the stators of alternators of this type, the most commonly used types of windings are firstly so-called “concentric” windings, constituted by coils closed on themselves which are wound around teeth of the stator, and secondly windings of the so-called “undulating” type. 
     An undulating winding comprises a plurality of phase windings, each phase winding comprising a spiral conductor, each turn of which forms undulations which pass through the notches in the body. Thus, in each turn, the conductor has loop structures which are situated alternately on both sides of the rotor or the stator, connecting to one another segment structures which are situated inside the notches in the stator. The conductor can be formed by one or a plurality of electrically conductive wires. 
     Document FR2947968 teaches the implementation of an in situ winding method in which all of the phase windings are wound at the same time and in parallel in the corresponding notches in the stator body. In the case of a hexaphase winding comprising two three-phase systems, this means that the inputs of the two systems which are obtained at the beginning of the winding are grouped together in a single area, whereas the outputs of the two systems obtained at the end of the winding are grouped together in a distinct area, spaced from the input area. 
     Consequently, in the case when it is wished to carry out coupling of the two three-phase systems, it is necessary to carry out a complementary operation of orientation and binding of phase windings in order to group together firstly the inputs and outputs of the first three-phase system, and secondly the inputs and outputs of the second three-phase system, or to group together one or a plurality of phase windings of the first system with one or a plurality of phase windings of the second system, such as to create two three-phase systems. However, a complementary binding operation of this type is lengthy and costly to carry out on an assembly line. 
     The objective of the invention is to eliminate this disadvantage efficiently by proposing a method for winding a stator for a multiphase electrical machine, the said stator comprising notches which are designed to receive conductors of a winding, the said winding comprising a winding for each phase, and forming two systems each comprising a respective group of windings, the said method comprising steps of installation of the conductors in the said notches, repeated such as to form a winding comprising a plurality of concentric turns. 
     According to one characteristic, one of the steps of installation of the conductors in a series of notches is subdivided into a first step of installation of at least one of the conductors of a first turn of the first system, followed by a second step of installation of at least one of the conductors of the first turn of the second system, whereas the first step of installation of at least one of the conductors of the first system is continued. 
     The invention thus makes it possible to position the inputs of the two systems in two different locations, which facilitates the coupling of the two systems by permitting positioning of the inputs opposite the corresponding control electronics. The invention thus makes it possible to eliminate the step of orientation and binding carried out in the methods according to the prior art. 
     According to one embodiment, during the step of installation of at least one of the conductors of a first turn of the first system, all the conductors of a first turn of the first system are installed, and during the second step of installation of at least one of the conductors of the first turn of the second system, all the conductors of the first turn of the second system are installed. 
     According to one embodiment, the said subdivided installation step also comprises a first step of installation of the conductors of a final turn of the first system, and a second step of installation of the conductors of the final turn of the second system, the said first step of installation of the conductors of the final turn of the first system ending before the second step of installation of the conductors of the final turn of the second system. 
     The invention also makes it possible to position the outputs of the two systems in two different locations, which facilitates the coupling of the two systems by permitting positioning of the outputs opposite the corresponding control electronics. 
     According to one embodiment, the second step of installation of the conductors of the final turn of the second system is continued, whereas the first step of installation of the conductors of the final turn of the first system ends, in a number of notches corresponding to a predetermined angle of the said stator. 
     According to one embodiment, the said first and second steps of installation of the conductors of the final turn are triggered simultaneously. 
     According to one embodiment, the said first and second steps of installation of at least one of the conductors of the first turn end simultaneously. 
     According to one embodiment, the portions of the conductors of the first turn which are installed firstly in the said notches during the first or second step of installation of at least one of the conductors of the first turn correspond respectively to the inputs of the winding of the first system or of the second system. 
     According to one embodiment, with the parts of a conductor which connect the two parts of this conductor which are installed in two consecutive notches being loop structures, the method also comprises a step of drawing at least one of the loop structures such as to form an excess length, followed by a step of passage of an input wire of the winding through the said excess length, such that the said input wire is retained. 
     According to one embodiment, the portions of the conductors the final turn which are installed finally in the said notches during the first or second step of installation of the conductors of the final turn correspond respectively to the outputs of the winding of the first system or of the second system. 
     According to one embodiment, with the parts of a conductor which connect the two parts of this conductor installed in two consecutive notches being loop structures, the method also comprises a step of drawing at least one of the loop structures, such as to form an excess length, followed by a step of passage of an output wire of the winding through the said excess length, such that the said output wire is retained. 
     According to one embodiment, the second step of installation of at least one of the conductors of the first turn of the second system is triggered when a number of notches corresponding to a predetermined angle of the said stator is covered by the first step of installation of at least one of the conductors of the first turn of the first system. 
     The invention also relates to a stator of a multiphase electrical machine, the said stator comprising notches which are designed to receive conductors of a winding, the said winding comprising a winding for each phase, and forming two systems each comprising a respective group of windings, the said winding comprising a plurality of concentric turns formed by conductors in a series of notches, characterised in that the first turn comprises conductors of the first system which are installed in a first series of notches, and conductors of the second system which are installed in a second series of notches, the number of notches of the first series filled by the conductors of the first system being greater than that of the number of notches of the second series filled by the conductors of the second system. 
     According to one embodiment, the final turn comprises conductors of the first system which are installed in a first series of notches, and conductors of the second series which are installed in a second series of notches, the number of notches of the first series filled by the conductors of the first system being smaller than the number of notches of the second series filled by the conductors of the second system. 
     According to one embodiment, the sum of the number of notches of the first series which are filled by the conductors of the first system in the first turn and the final turn is equal to the sum of the number of notches of the second series which are filled by the conductors of the second system in the first turn and the final turn. 
    
    
     
       The invention will be better understood by reading the following description and examining the figures which accompany it. These figures are provided purely by way of illustration, and in no way limit the invention. 
         FIG. 1  is a view in perspective of a wound stator obtained further to implementation of the winding method according to the present invention; 
         FIGS. 2 a  to 2 d    illustrate, for a stator represented in flat projection, the different types of turns obtained during implementation of the winding method according to the present invention; 
         FIG. 3  illustrates the coupling of the two three-phase systems obtained further to implementation of the method according to the present invention; 
         FIG. 4  is the list of the numbers of notches filled by the conductors of the phases of the different systems respectively during the creation of the starting turn, odd turns, even turns, and the final winding turn; 
         FIG. 5  illustrates a step of passage of an input wire of the winding into a loop structure. 
     
    
    
     Elements which are identical, similar or analogous retain the same reference from one figure to another. 
       FIG. 1  is a view in perspective of a wound stator  10  of a rotary electrical machine which comprises mainly a body  11  in which there are fitted a plurality of phase windings PH 1 -PH 3 ; PH 1 ′-PH 3 ′forming a winding. The rotary machine is for example an alternator or an alternator-starter. This machine is preferably designed to be implemented in a motor vehicle. It will be remembered that an alternator-starter is a rotary electrical machine which can work reversibly, firstly as an electric generator when functioning as an alternator, and secondly as an electric motor, in particular in order to start the thermal engine of the motor vehicle. 
     The stator body  11  has an annular cylindrical form with an axis X, and consists of an axial stack of flat metal plates. The body  11  comprises teeth  12  which are distributed angularly regularly around an inner circumference of a head  13 . These teeth  12  delimit notches  15  in pairs. The head  13  corresponds to the solid annular portion of the body  11 , which extends between the base of the notches  15  and the outer periphery of the body  11 . 
     The notches  15  open axially on both sides of the body  11 . The notches  15  are also open radially in the inner face of the body  11 . The notches  15  can have parallel edges, i.e. the inner faces opposite one another are parallel to one another. Alternatively, in another configuration, teeth  12  with parallel edges can be found, and in this case the notches are known as trapezoidal. There are for example  36 ,  48 ,  60 ,  72 ,  84  or  96  notches  15 . In this embodiment, the stator  10  comprises  72  notches. Preferably, the stator  10  is without tooth roots, in order to facilitate the insertion of the conductors during the winding step. Alternatively, in another configuration, the teeth  12  can be provided with tooth roots. Insulators  16  are arranged in the notches  15  in the stator. 
     In order to form the stator winding  10 , a plurality of phase windings PH 1 -PH 3 , PH 1 ′-PH 3 ′ are installed in the notches  15  in the body  11 . In this case, the hexaphase stator comprises six phase windings in order to form two three-phase systems coupled to one another. The invention is however applicable to stators comprising a larger number of three-phase systems, or to systems each comprising a number of phase windings different from three windings. 
     Each phase winding PH 1 -PH 3 , PH 1 ′-PH 3 ′ is constituted by a conductor C 1 -C 3 , C 1 ′-C 3  which is bent in a serpentine form, and wound inside the stator in the notches  15  in order to form a turn, with the winding of a plurality of concentric turns forming the winding of the complete phase. Each notch  15  receives the conductor C 1 -C 3 , C 1 ′-C 3 ′ of a single phase several times, and thus when there are N phases, the conductors of a single phase winding PH 1 -PH 3 , PH 1 ′-PH 3 ′ is inserted every N notches  15 . 
     In each turn, the conductor C 1 -C 3 , C 1 ′-C 3 ′ thus has loop structures  19   a,    19   b  which are situated alternately on both sides of the rotor or the stator, connecting to one another segment structures  18  which are situated in a series of notches  15  associated with a given phase winding. It should be noted that each conductor C 1 -C 3 , C 1 ′-C 3 ′ can comprise a single wire or a bundle M of conductive wires, M being equal to 2 or more. In this case, the wires have a round cross-section. Alternatively, in order to optimise the filling of the notches  15 , the wires can have a rectangular or square cross-section. The conductors are preferably made of copper covered with enamel. 
     With reference to  FIGS. 2 a  to 2 d   , a description is provided hereinafter of the method which makes it possible to obtain the hexaphase wound stator  10  (N=6) comprising a first three-phase system A formed by the phase windings PH 1 -PH 3 , and a second three-phase system B formed by the windings PH 1 ′-PH 3 ′. Each phase winding PH 1 -PH 3 , PH 1 ′-PH 3 ′ is constituted by a corresponding wound conductor C 1 -C 3 , C 1 ′-C 3 ′. In this case, the conductors C 1 -C 3 , C 1 ′-C 3 ′ each comprise a bundle of M=2 wires, even though a single wire per conductor has been represented in the figures in order to facilitate understanding of the method. 
     More specifically, as illustrated in  FIG. 2 a   , a first step of installation of the conductors C 1 -C 3  of the first system A is carried out so as to form a first turn, known as a starting turn SD. For this purpose, the conductors C 1 -C 3  are inserted in three distinct notches  15  corresponding to the first system A. Two adjacent notches  15  of this assembly are spaced from one another by a notch which is left free in order to permit subsequent insertion of the conductors C 1 ′-C 3 ′ of the second three-phase system B, as explained hereinafter. In the example represented, the conductors C 1 -C 3  of the first system A are inserted in the notches which are numbered respectively  26 ,  28  and  30 . 
     The portions of the conductors C 1 -C 3  of the starting turn which are installed first in the notches  15  during this first installation step correspond to the inputs E 1 -E 3  of the winding of the first system. 
     The conductors C 1 -C 3  of the first system A are then bent in order to form loop structures  19   a,  in this case with a substantially triangular form, which extend from a single side of the stator  10 . The conductors C 1 -C 3  of the first system A are then each inserted in the following notch  15 , which is situated N notches after the first. The conductors C 1 -C 3  are then bent in order to form loop structures  19   b  which extend from a side opposite that of the first loop structures  19   a.  Thus, the loop structures  19   a,    19   b  are situated on the exterior of the stator  10 , alternately on one side or the other of the stator, with the assembly of the loop structures  19   a,    19   b  which extend from a single side of the stator  10  forming a winding chignon. 
     The winding of the first system A alone thus continues to be formed until a number of notches  15  corresponding to a predetermined angle α of the stator  10  is covered by the first step of installation of the conductors C 1 -C 3  of the first system A. This angle α is predetermined such that the inputs E 1 -E 3 ; E 1 ′-E 3 ′ of the two three-phase systems A, B are situated respectively opposite the corresponding control electronics. 
     When this predetermined angle α is reached, for example an angle α of approximately 120°, a second step of installation of the conductors C 1 -C 3 ′ of the starting turn SD of the second system B is carried out. For this purpose, the portions of the conductors C 1 ′-C 3 ′ of the second system B corresponding to the inputs E 1 ′-E 3 ′ are inserted in the free notches  15  situated between the notches filled by the first system A, as well as in an adjacent notch  15 , such as to have alternately a notch  15  which receives a conductor of one of the systems A, B, then a notch  15  which receives a conductor of the other system A, B. The conductors C 1 ′-C 3 ′ of the second system B can thus for example be inserted in the notches  15  which are numbered respectively 1, 3 and 5, whereas the conductors C 1 -C 3  of the first system A are in the notches  15  which are numbered respectively 2, 4 and 6 (cf.  FIG. 4 ). 
     With the step of installation of the conductors C 1 -C 3  of the first system A continuing, simultaneous winding is then carried out of the two three-phase systems A, B. In other words, simultaneous winding in parallel is carried out of the N conductors C 1 -C 3 , C 1 ′-C 3 ′ in the successive series of N notches  15 . With the winding of the systems A, B having been carried out in a first direction K 1  during the winding of the starting turn SD, a change of direction CH 1  then takes place, represented in broken lines, in order to go to a second direction of winding K 2 , so as to form an odd turn SI, as illustrated in  FIG. 2   b.    
     The two systems A, B are then wound simultaneously in the odd turn SI according to a complete revolution of the stator  10 , i.e. all the notches  15  in the stator  10  are filled in succession by a series of N notches by the two systems A, B, in the direction K 2  (cf.  FIG. 4 ). 
     When the revolution of the odd turn SI is completed, a change of direction CH 2  takes place, in order to return to the direction of winding K 1 , so as to carry out an even turn SP, as illustrated in  FIG. 2 c   . The two systems A, B are then wound simultaneously in the even turn SP according to a complete revolution of the stator  10 , i.e. all the notches  15  in the stator  10  are filled in succession by a series of N notches by the two systems A, B, in the direction K 1  (cf.  FIG. 4 ). 
     It should be noted that during a phase of winding in the inverse direction, each loop structure  19   a,    19   b  of a conductor C 1 -C 3 , C 1 ′-C 3 ′ belonging to a given winding PH 1 -PH 3 ; PH 1 ′-PH 3 ′ will be placed in the free space between two loop structures  19   a,    19   b  of the conductors C 1 -C 3 , C 1 ′-C 3 ′ obtained during the winding phase in the first direction. A symmetrical winding of the distributed undulating type is thus obtained. 
     When the revolution of the even turn SP has been completed, a further change of direction CH 3  takes place in order to form a new odd turn SI, and so on, until the required number of turns has been obtained. If it is wished to carry out six complete turns (without counting the starting turn SD or the end of winding turn SF), there are thus three changes of direction CH 2  in order to go from the turns 1/3/5 formed in the direction K 2  to the turns 2/4/6 formed in the direction K 1 . In addition, there are two changes of direction CH 3  in order to go from the turns 2/4 formed in the direction K 1  to the turns 3/5 formed in the direction K 2 . 
     In the present case, the direction K 1  corresponds to the insertion of the conductors C 1 -C 3 , C 1 ′-C 3 ′ in decreasing series of notches  15 , whereas the direction K 2  corresponds to insertion of the conductors C 1 -C 3 , C 1 ′-C 3 ′ in increasing series of notches  15 . However, as a variant, these two directions of winding K 1 , K 2  could be inverted. 
     At the end of the winding process, and after having carried out a final change of direction, as illustrated in  FIG. 2 d    a first step is carried out of installation of the conductors C 1 -C 3  of the final turn SF of the first system A, and a second step of installation of the conductors C 1 ′-C 3 ′ of the final turn SF of the second system B. 
     These two installation steps are triggered simultaneously. However, the step of installation of the conductors C 1 -C 3  of the final turn SF of the first system A ends before the step of installation of the conductors C 1 ′-C 3 ′ of the final turn SF of the second system B. 
     The portions of the conductors of the final turn SF which are installed last in the notches  15  during the first or second step of installation of the conductors C 1 -C 3 , C 1 ′-C 3 ′ of the final turn correspond respectively to the outputs S 1 -S 3  of the winding of the first system A or to the outputs S 1 ′-S 3 ′ of the winding of the second system B. 
     It should be noted that the second step of installation of the conductors C 1 ′-C 3 ′ of the final turn SF of the second system B is continued, whereas the first step of installation of the conductors C 1 -C 3  of the final turn SF of the first step A ends with a number of notches  15  corresponding to a predetermined angle β of the stator  10 . This angle β, for example of approximately 120°, is predetermined such that the outputs S 1 -S 3 , S 1 ′-S 3 ′ of the two three-phase systems A, B are situated opposite the corresponding control electronics. 
     Thus, at the end of the process, the inputs E 1 -E 3 , E 1 ′-E 3 ′ and the outputs S 1 -S 3 , S 1 ′-S 3 ′ of each system are grouped together in the same area, such that it is easily possible to carry out the coupling in the form of a triangle of each of the three-phase systems A, B. 
     For this purpose, in the first system A, the input E 1  of the first phase winding PH 1  is connected to the output S 2  of the second phase winding PH 2 , the output S 1  of the first phase winding PH 1  is connected to the output S 3  of the third phase winding PH 3 , and the input E 2  of the second phase winding PH 2  is connected to the input E 3  of the third phase winding PH 3 . 
     In addition, in the second system B, the input E 1 ′ of the first phase winding PH 1 ′ is connected to the output S 2 ′ of the second phase winding PH 2 ′, the output S 1 ′ of the first phase winding PH 1 ′ is connected to the output S 3 ′ of the third phase winding PH 3 ′, and the input E 2 ′ of the second phase winding PH 2 ′ is connected to the input E 3 ′ of the third phase winding PH 3 ′. 
     It will be appreciated that, as a variant, the three-phase systems A, B can be coupled in the form of a star. As an alternative, A can be coupled in the form of a star whereas B will be coupled in the form of a triangle. 
     As can be seen in  FIG. 4 , in the wound stator  10 , the starting turn SD comprises conductors C 1 -C 3  of the first system A installed in a first series of notches Ser_ 1 _SD and conductors C 1 ′-C 3 ′ of the second system B installed in a second series of notches Ser_ 2 _SD, with the number of notches  15  of the first series Ser_ 1 _SD filled by the conductors C 1 -C 3  of the first system A being greater than that of the number of notches of the second series Ser_ 2 _SD filled by the conductors C 1 ′-C 3 ′ of the second system B. The difference between the number of notches of these two series Ser_ 1 _SD and Ser_ 2 _SD corresponds to the predetermined angle α between the inputs E 1 -E 3 ; E 1 ′-E 3 ′ of the two systems A, B. 
     In addition, the final turn SF comprises conductors C 1 -C 3  of the first system A installed in a first series of notches Ser_ 1 _SF and conductors C 1 ′-C 3 ′ of the second system B installed in a second series of notches Ser_ 2 _SF, with the number of notches  15  of the first series Ser_ 1 _SF filled by the conductors C 1 -C 3  of the first system A being smaller than the number of notches  15  of the second series Ser_ 2 _SF filled by the conductors C 1 ′-C 3 ′ of the second system B. The difference between the number of notches of these two series Ser_ 1 _SF and Ser_ 2 _SF corresponds to the predetermined angle β between the inputs S 1 -S 3 , S 1 ′-S 3 ′ of the two systems A, B. 
     In addition, the sum of the number of notches  15  of the first series Ser_ 1 _SD, Ser_ 1 _SF filled by the conductors C 1 -C 3  of the first system A in the first turn SD and the final turn SF is equal to the sum of the number of notches  15  of the second series Ser_ 2 _SD, Ser_ 2 _SF filled by the conductors C 1 ′-C 3 ′ of the second system B in the first turn SD and the final turn SF. 
     As illustrated in  FIGS. 1, 4 and 5 , the parts of a conductor which connect the two parts of this conductor accommodated or installed in two consecutive notches  15  are loop structures  19   a  or  19   b.    
     A stator has been represented with a winding comprising inputs and outputs which are all situated on the outer diameter of the winding, i.e. in the layer of the winding which is furthest from the axis. It is also possible to provide a winding according to which the 3 inputs E 1 -E 3  of the first system are situated on the inner diameter, i.e. in the layer of the winding which is closest to the axis, whereas the 3 outputs S 1 -S 3  of the first system are situated on the outer diameter, i.e. in the layer of winding which is furthest from the axis. The same applies to the second system, i.e. it is also possible to provide a winding according to which the 3 inputs E′ 1 -E′ 3  of the second system are situated on the inner diameter, i.e. in the layer of winding which is closest to the axis, whereas the 3 outputs S′ 1 -S′ 3  of the second system are situated on the outer diameter, i.e. in the layer of winding which is furthest from the axis. 
     As illustrated in  FIG. 5 , it is possible to modify a loop structure  19   a  such as to form an excess length. It is then possible to pass an input wire E 1  of the winding through the said excess length, such that the said input wire is retained. It would also be possible, instead of the input wire, to pass an output wire S 1 -S 3 , S 1 ′-S 3 ′ into the said excess length. 
     Similarly, it is also possible to modify a loop structure  19   b  such as to form an excess length. In this case, it is then possible to pass either an input wire or an output wire of the winding through the said excess length, such that the said input or output wire is retained. 
     It will be appreciated that the foregoing description has been provided purely by way of example, and does not limit the scope of the invention, a departure from which would not be constituted by replacing the different elements or steps by any other equivalents.