Stator for electric machine

Abstract

To provide a stator for an electric machine in which a hairpin winding has a scalable layout for improved manufacturing of a wide range of electric machines.SOLUTION: A stator for electric machine 1 includes a stator core 2 having a plurality of slots and a hairpin winding 3. The hairpin winding has a hairpin conductor 4 with two legs connected at a head. The legs of the hairpin conductor are received in at least two radially adjacent layers in the slots, the head extends outside the stator core at an insertion end, and an end section of the leg opposite the head extends outside the stator core at a welded end 10.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present application relates to a stator for an electric machine comprising a stator core having a plurality of slots and hairpin windings. [Background technology]

[0002] Increasing performance requirements for electric machines have resulted in windings made of hairpin conductors with rectangular wire cross sections that provide higher slot filling and power density. The stator winding structure and winding connections to the phase lead wires and neutral wire are distributed to minimize the number of specially shaped hairpin conductors, which facilitates manufacturing.

[0003] China Utility Model No. 213782983 relates to a flat wire hairpin stator structure and a motor. The flat wire hairpin stator structure includes a stator core, a stator winding, and a bus bar. The stator core includes a core body and a plurality of stator grooves that are uniformly spaced apart on the inner peripheral wall surface of the core body and extend in the axial direction of the core body. The stator winding has a plurality of layers of flat wire conductors inserted into each stator slot, one end of each layer of the flat wire conductor is an insertion end, and the other end of each layer of the flat wire conductor is a welding end, and the layers of the flat wire conductor are bent in the circumferential direction of the core body to form a U-phase winding, a V-phase winding, and a W-phase winding in an encircling manner. The conductor lead wires and conductor neutral wires of the parallel branches of each phase winding are disposed at the welding ends of the flat wire conductors. The busbars include a U-phase lead busbar, a V-phase lead busbar, a W-phase lead busbar, and a neutral busbar, which are arranged at the welded ends of the flat wire conductors, simplifying the multi-layer flat wire conductor layout of the stator windings and reducing the overall size of the flat wire hairpin motor.

[0004] China Patent Publication No. 113809857 discloses a multi-layer hairpin-type flat wire winding stator with a stator core and a hairpin flat wire wave winding. A stator slot is arranged in the stator core, and the hairpin flat wire wave winding is embedded in the stator slot. The hairpin flat wire wave winding has three or more branches. The stator slots on which the three-phase windings of the hairpin flat wire wave winding are located are arranged in pairs to be spaced apart and arranged consecutively. After any branch goes around a half-period layer, it is changed to an equivalent slot of an adjacent stator slot, and when the branch is changed to an equivalent slot of an adjacent stator slot so that the layers cross, a long-distance connection or a short-distance connection is adopted, so that the leading and trailing ends of all the branches are located in the radially innermost and outermost layers of the stator. Long or short distance connections occur only when a lamination is displaced across to the equivalent slots of adjacent stator slots so that the leading and trailing ends of the branches are positioned at the radially innermost and outermost laminations of the armature, allowing a single branch of each phase to pass through equivalent locations in all laminations of all stator slots of the phase in which it is located.

[0005] China Patent Publication No. 114172294 discloses a flat-wire motor, a wire pull-out mechanism and a winding mechanism thereof, the wire pull-out mechanism has a neutral bar arranged perpendicular to the axis of the winding of the flat-wire motor and has an arc-shaped plate embedded in the end surface of the winding, the inward-curved surface and the outward-curved surface of the arc-shaped plate are arranged with coupling posts used for connecting with the winding, the coupling posts arranged on the inward-curved surface and the outward-curved surface are arranged alternately, the wiring terminal has a wiring board arranged perpendicular to the plane in which the arc-shaped plate is located, an access line is arranged in the middle of the wiring board, which is away from one side of the arc-shaped plate and is used to access the external wiring voltage, and the wiring board has pull-out wires arranged at two ends, which are used to connect with the winding. According to the flat-wire motor, the wire pull-out mechanism and the winding mechanism thereof, the design cost of the flat-wire motor can be reduced.

[0006] Chinese Utility Model No. 215300307 discloses a flat wire winding structure and a stator, and a motor including the stator, the flat wire winding structure is arranged in a stator core, and a tooth row section of the stator core is provided with a plurality of wire slots, each wire slot is provided with an even number of mounting positions, and the mounting positions are arranged in a radial direction and are used to accommodate pins of a plurality of flat wire coil conductors, the flat wire winding structure has a first phase winding, a second phase winding, and a third phase winding, each phase winding has four parallel branches, and the first phase winding, the second phase winding, and the third phase winding are each a double-layer winding structure, and in the winding circle surrounding the stator core, each parallel branch is introduced from the upper layer of one wire slot and led out from the lower layer of the other wire slot, and two different parallel branches of the same phase winding are overlapped in the wire slot to form a double-layer winding structure. The motor provided by this utility model has improved torque output capabilities as well as a higher power factor. Summary of the Invention [Problem to be solved by the invention]

[0007] The challenge is to provide a stator for an electric machine with a stator core having a plurality of slots and hairpin windings, where the hairpin windings have a scalable layout to improve manufacturing of a wide range of electric machines. [Means for solving the problem]

[0008] This object is achieved by a stator for an electric machine according to claim 1. Advantageous embodiments are the subject of the dependent claims.

[0009] A stator for an electric machine includes a stator core having a plurality of slots and a hairpin winding. The hairpin winding has a hairpin conductor with two legs connected at a head, a slot pitch between the two legs defined by the head, and the slot pitch of each hairpin conductor is the same. The legs of the hairpin conductor are received in at least two radially adjacent layers in the slots, the head extends outside the stator core at an insertion end, and an end section of the leg opposite the head extends outside the stator core at a weld end. The hairpin winding defines at least three phase windings, each phase winding having at least one branch, and each branch of each phase winding having a phase terminal formed on one of the end sections for connection to a phase busbar and a neutral terminal formed on one of the end sections for connection to a neutral busbar. All of the phase and neutral terminals are disposed on at least one of the outermost layer of the radially adjacent layers and the innermost layer of the radially adjacent layers at the welded ends of the hairpin winding.

[0010] The advantage of this stator is that the hairpin winding structure is scalable for electric machines with different parameters in terms of number of layers per slot, number of slots, number of turns of the phase winding, number of slots per pole and per phase, number of parallel branches per phase, number of poles, number of phases. The same slot pitch of each hairpin conductor means that all hairpin conductors extend over the same number of slots in the circumferential direction of the slots and the same number of layers in the radial direction. The actual distance measurement between the two legs depends on the distance of each slot and layer, which increases in the radial direction. The location of all phase and neutral terminals at the welded ends of the hairpin winding improves the manufacturing process since the welding operations constituting the contacts with each busbar are performed in a limited area.

[0011] The hairpin conductor may be formed from a wire having a rectangular cross section, for example from a flat wire. The wire of the hairpin conductor is generally solid, but may be hollow, for example to provide a cooling duct through the hairpin conductor. The legs and the head may be formed by bending the wire. The legs are accommodated in different slots and in different layers of the stator core, the slot pitch of the head extending over the circumferential distance between the two slots and the radial distance between the two layers. The stator core has a generally cylindrical shape and defines a longitudinal axis, with respect to which all circumferential, axial and radial statements should be understood. The end sections of the branches are electrically interconnected, usually by welding, each branch forming a conductor with one of the phase terminals at one end and one of the neutral terminals at the other end. The connected end sections of two successive hairpin conductors of a branch extend over the same slot pitch as the head. The neutral terminals may be connected to a single neutral busbar, forming a star connection, or the neutral terminals of each phase winding pair may be connected to one of a number of neutral busbars, forming a delta connection. Because the phase and neutral terminals are all located at the welded ends of the hairpin windings, the connections of the phase and neutral terminals are advantageously easily made. Furthermore, the phase and neutral busbars may be located between the phase and neutral terminals of the radially outermost and innermost layers, thereby reducing the overall axial length of the stator. The groups of end sections forming the phase and neutral terminals may be welded in pairs, thereby extending axially beyond the groups of end sections forming the electrical interconnections that form the parallel branches of the phase windings. The neutral terminals of each branch are located on a radially opposite layer to each of the phase terminals of each branch. Thus, each branch winding begins at a phase terminal and extends from the innermost or outermost layer, respectively, to the radially opposite layer. The branches starting from the innermost layer are wound around the stator in the opposite rotational direction to the branches starting from the outermost layer.

[0012] According to one embodiment, the sector of the stator circumference occupied by the phase and neutral terminals at the welded ends defines the terminal connection range. The extension of the terminal connection range over the stator circumference is reduced, meaning that the phase and neutral terminals are packaged together as closely as possible, reducing the terminal connection range to the smallest possible extension. The resulting minimum extension depends on the number of poles and the number of slots per pole and per phase of the stator.

[0013] According to another embodiment, the phase terminals are evenly distributed between the outermost and the innermost layers. For example, the first half of the phase terminals are arranged on the outermost layer and the second half of the phase terminals are arranged on the innermost layer. By distributing the phase terminals on the outermost and the innermost layers, the advantage is obtained that the circumferential extent of the welding operation is reduced, since the phase terminals are grouped together over a limited extent of the circumference. In general, the number of branches per phase winding may be any natural number greater than zero. The skilled person will understand that it is not possible to distribute the phase terminals evenly when there is an odd number. In any case, a distribution of one phase terminal on the outermost layer and two phase terminals on the innermost layer, or two phase terminals on the outermost layer and three phase terminals on the innermost layer, is still advantageous, since the associated neutral terminal is always arranged on the layer opposite the phase terminals, respectively.

[0014] According to another embodiment, each phase winding has multiple parallel branches, and at least one pair of phase terminals of the parallel branches of at least one phase winding both extend from one common phase slot, such that if a phase winding has two parallel branches, one phase terminal is arranged in the outermost layer of the common phase slot and the other phase terminal is arranged in the innermost layer of the common phase slot.

[0015] According to another embodiment, pairs of phase terminals of parallel branches of at least one phase winding extend in pairs from adjacently arranged common phase slots. If the phase winding has, for example, four or six branches, two or three phase terminals can be arranged on the outermost layer and two or three further phase terminals can be arranged on the innermost layer, these phase terminals being arranged in pairs in two or three common phase slots, which can be arranged adjacently.

[0016] According to another embodiment, each phase winding has a plurality of parallel branches, with a first half of the phase terminals of at least one parallel branch of the phase winding extending from an innermost layer of at least one first offset phase slot, and a second half of the phase terminals of at least one parallel branch of the phase winding extending from an outermost layer of at least one second offset phase slot, the at least one first offset phase slot being circumferentially offset with respect to the at least one second offset phase slot. This embodiment is particularly useful for hairpin windings with an odd number of phase windings. If the parallel branches of at least one phase winding are paired together in one common phase slot and the parallel branches of at least one other phase winding are circumferentially distributed to offset the phase slots, the resulting distribution of the cooperating neutral terminals overlaps more closely with the phase terminals over a limited circumferential range, which also reduces the circumferential range of the welding operation.

[0017] According to another embodiment, each phase winding has multiple parallel branches, and at least one pair of neutral terminals of the parallel branches of at least one phase winding both extend from one common neutral slot. Thus, if a phase winding has two parallel branches, for example, one neutral terminal is arranged in the outermost layer of the common neutral slot, and the other neutral terminal is arranged in the innermost layer of the common neutral slot. Furthermore, if a phase winding has three or more parallel branches, multiple pairs of neutral terminals of the parallel branches of at least one phase winding may extend in pairs from multiple adjacently arranged common neutral slots.

[0018] According to another embodiment, each phase winding has a plurality of parallel branches, a first half of the neutral terminal of at least one parallel branch of the phase winding extends from an innermost layer of at least one first offset neutral slot, and a second half of the neutral terminal of at least one parallel branch of the phase winding extends from an outermost layer of at least one second offset neutral slot, and the at least one first offset neutral slot is circumferentially offset with respect to the at least one second offset neutral slot. By offsetting the neutral terminal of the phase winding to the first and second offset neutral slots in the circumferential direction, one of the first and second offset neutral slots can be located between two common phase slots, resulting in a closer overlap of the slots occupied by the phase and neutral terminals. Those skilled in the art will appreciate that half of the neutral terminal or half of the phase terminal of one phase winding can be offset, both with the same beneficial results.

[0019] The slots occupied by the phase terminals and neutral terminals are a common phase slot, a first offset phase slot, a second offset phase slot, a common neutral slot, a first offset neutral slot, and a second offset neutral slot, which together define a terminal slot range extending circumferentially over a fraction of the total number of slots. The terminal slot range may extend over less than 2 / 3 of the total number of slots, and preferably over less than 1 / 2 of the total number of slots. The terminal slot range may further extend over a contiguous range of adjacent slots in which at least one phase terminal or at least one neutral terminal is located.

[0020] According to another embodiment, each phase winding has several parallel branches, at least the phase terminal of the first branch and the neutral terminal of the second branch are arranged on one of the outermost and innermost layers, and the first branch and the second branch are connected on the opposite layers of the outermost and innermost layers. This embodiment reduces the number of phase and neutral terminals by connecting the two branches, and the neutral terminal of the first branch and the phase terminal of the second branch can be arranged on the same layer. The connection between the phase terminal of the first branch and the neutral terminal of the second branch can be formed by a jumper, and the branches of each phase winding can be connected in pairs in this way.

[0021] Exemplary embodiments and further features and advantages are described with reference to the drawings. [Brief description of the drawings]

[0022] [Figure 1A] 1 is a cross-sectional view illustrating an embodiment of a stator for an electric machine. [Figure 1B] 1 is a cross-sectional view illustrating an embodiment of a stator for an electric machine. [Figure 2A] FIG. 1B is an enlarged detail view of the stator of FIG. 1A. [Figure 2B] FIG. 1C is an enlarged detail view of the stator of FIG. [Diagram 3] FIG. 1 is a diagram showing a hairpin conductor. [Figure 4] FIG. 2 is a perspective view showing the embodiment of FIG. 1. [Diagram 5] FIG. 5 is an enlarged detail view of FIG. [Figure 6] FIG. 2 is a generalized schematic diagram of a winding structure. [Figure 7] FIG. 4 is a generalized schematic diagram of a winding structure according to another embodiment. [Figure 8] FIG. 4 is a generalized schematic diagram of a winding structure according to another embodiment. [Figure 9] 1 is a perspective view illustrating an embodiment of a stator for an electric machine. [Figure 10] FIG. 10 is an enlarged detail view of FIG. [Figure 11] FIG. 10 is an enlarged detail of FIG. 9 with the busbars shown in an exploded view. [Figure 12] FIG. 12 is a perspective view showing a detail of FIG. [Figure 13] FIG. 4 is an exemplary schematic diagram of a winding configuration for a stator according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In Fig. 1A an embodiment of a stator 1 for an electric machine is shown in a schematic cross-section in the direction of the longitudinal axis A. The stator core 2 has a number of slots 5 in which hairpin windings (see Fig. 4) are accommodated. In the illustrated embodiment, the stator core 2 has 48 slots 5 evenly distributed in the circumferential direction of the stator core 2. The legs of the hairpin conductors (see Fig. 3) are accommodated in the slots 5 in at least two radially adjacent layers Li, where i is an index representing the number Z of layers Li. The stator 1 of Fig. 1A comprises eight layers.

[0024] In Fig. 1B another embodiment of the stator 1 is shown in a schematic cross-sectional view in the direction of the longitudinal axis A. The stator core 2 again has 48 slots 5 evenly distributed in the circumferential direction of the stator core 2, each slot 5 having in this embodiment four layers.

[0025] In Fig. 2A an enlarged detail view of one of the slots 5 of Fig. 1A is shown. In the illustrated embodiment, the legs 6 are housed in eight radially adjacent layers Li in the slot 5, L1 being the innermost layer and L8 being the outermost layer. More generally, the outermost layer is denoted Lz, which stands for any number z of layers Li.

[0026] Figure 2B shows an enlarged detail of one of the slots 5 of Figure 1B. This embodiment has four radially adjacent layers Li occupied by legs 6, with L1 being the innermost layer and L4 being the outermost layer Lz.

[0027] In FIG. 3 the hairpin conductor 4 is shown in detail. The hairpin winding (see FIG. 4) is made up of several hairpin conductors 4 with two legs 6 connected at a head 7, where the slot pitch is defined by the number of slots 5 through which the heads 7 extend. The slot pitch of each hairpin conductor 4 of the hairpin winding is identical. The two legs 6 of the hairpin conductor 4 are accommodated in two different slots 5 and in two different layers Li. The hairpin conductor 4 is shown in the form it has when mounted on the stator 1. However, before assembly the end section 8 is straight and in line with the legs 6. The end section 8 is bent after the hairpin winding is inserted in the slot 5.

[0028] FIG. 4 shows the stator 1 of FIG. 1 in a perspective view. The head 7 of the hairpin conductor 4 extends outside the stator core 2 at the insertion end 9. The part of the hairpin winding 3 extending at the insertion end 9 is also called the crown side. The end section 8 of the leg 6 opposite the head 7 extends outside the stator core 2 at the welded end 10. The hairpin winding 3 is assembled outside the stator 1 and then inserted into the slots 5 from the insertion end 9. The end sections 8 of the legs 6 are straight until after insertion into the stator core 2 and are subsequently bent into the shape shown, where the end sections 8 of the legs 6 in one slot 5 are bent alternately from layer to layer in a clockwise and counterclockwise direction. The hairpin winding 3 defines a three-phase winding for the three phases U, V and W. Each phase winding has four parallel branches starting with phase terminals Un, Vn, Wn and ending with neutral terminals NUn, NVn, NWn. In the designation of the phase and neutral terminals, "U, V and W" identify the phase and "n" is an index identifying each branch, i.e. 1 to 4 in this embodiment. The phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn are fully described in FIG. 5 and will be explained in more detail with reference to FIG. 5. All phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn are arranged at a welded end 10. The hairpin conductors 4 forming one branch are electrically interconnected in series by spot welding at the end section 8. The end section 8 forming the phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn extends axially beyond the end section 8 forming a spot welded electrical interconnection 16. The four phase terminals Un of the parallel branches of the U-phase winding are respectively connected to a U-phase busbar 12, the phase terminals Vn of the V-phase winding are respectively connected to a V-phase busbar 14, and the phase terminals Wn of the W-phase winding are respectively connected to a W-phase busbar 15. The neutral terminals NUn, NVn, NWn are all connected to a neutral busbar 11, forming a star connection in this embodiment. The terminal connection range 17 is defined by the sector of the circumference of the stator 1 occupied by the phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn at the welded end 10.The terminal connection area 17 extends over less than half the circumference of the stator 1, and in this embodiment over one third of the circumference of the stator 1.

[0029] In Fig. 5 the welded end 10 of Fig. 4 is shown in an enlarged detail view without busbars. The arrangement of the phase terminals Un, Vn, Wn and the neutral terminals NUUn, NVn, NWn is explained in its entirety with reference to Fig. 5. The hairpin winding 3 defining the three-phase winding has four parallel branches for each phase U, V, W. The phase terminals are designated U1, U2, U3, U4, V1, V2, V3, V4, W1, W2, W3, W4 and the neutral terminals are designated NU1, NU2, NU3, NU4, NV1, NV2, NV3, NV4, NW1, NW2, NW3, NW4. The phase terminals U1, U2, V1, V2, W1, W2 and the neutral terminals NU3, NU4, NV3, NV4, NW3, NW4 are arranged on the outermost layer L8 of the radially adjacent layers Li, and the phase terminals U3, U4, V3, V4, W3, W4 and the neutral terminals NU1, NU2, NV1, NV2, NW1, NW2 are arranged on the innermost layer L1 of the radially adjacent layers Li. In the illustrated embodiment, the phase terminals Un, Vn, Wn are evenly distributed between the outermost layer Lz and the innermost layer L1. The phase terminals Un, Vn, Wn and the neutral terminals NUUn, NVn, NWn are concentrated in one sector of the circumference of the stator 1, the terminal connection area 17. The row of radially extending end sections 8 generally corresponds to the 48 slots of the stator 1, provided that the end sections 8 are all bent in the clockwise and counterclockwise direction at the same radial distance. The terminal connection area 17 therefore extends over 16 of the 48 slots 5, or over a 120° circular sector of the stator 1 in this embodiment. The terminal connection area 17 includes four slots 5 or rows having end sections 8 with relatively short spot-welded electrical interconnections 16 surrounded by relatively long phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn. All welding operations for the connection of the phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn to the busbars 11, 12, 14, 15 are limited to 1 / 3 of the stator circumference.

[0030] In Fig. 6, a generalized schematic diagram of a winding structure for a stator with arbitrary parameters is shown for the U, V and W phases. The upper matrix for each phase shows an example branch of each phase winding with phase terminals Uk, Vk, Wk of each parallel branch number k in the outermost layer Lz and neutral terminals NUk, NVk, NWk of said parallel branch number k in the innermost layer L1, where k is an integer between 1 and N / 2, and N is the total number of parallel branches per phase winding. The lower matrix for each phase U, V, W shows further example branches of each phase winding with phase terminals Ul, Vl, Wl of parallel branch number l in the innermost layer L1 and neutral terminals NUl, NVl, NWl of said parallel branch number l in the outermost layer Lz, where l is an integer between N / 2+1 and N. The matrix represents slots 5 in columns and layers Li in rows for any number of slots 5 and layers Li, showing that the proposed concept is modular and applicable to stator cores with any parameters, provided that the parameters comply with the conditions described below, where z is the number of layers and Qs is the number of stator slots 5.

[0031] The layers are denoted Li, where i is the index from the innermost layer L1 to the outermost layer Lz. The matrix number i thus denotes the row, where i is an integer from 1 to z, i=[1,z]. The slots are denoted Sj, where j is the index from S1 to SQs. The matrix number j thus denotes the column, where j is an integer from 1 to Qs, j=[1,Qs]. The number of phase terminals in the outermost layer Lz is k, where k=[1,N / 2]. The number of phase terminals in the innermost layer L1 is l, where l=[N / 2+1,N]. The number of layers per slot z is at least 2, where 2≦z, and z is an even integer. The number of pole pairs p is at least 1, where 1≦p, and p is an integer. The number of slots per pole and per phase q is at least 1, where 1≦q, and q is an integer. The number of parallel branches per phase winding, N, is between 2 and twice the number of slots per pole and per phase, where 2≦N≦2q, and N is a positive divisor of 2q. The number of turns in a phase winding, Nph, is calculated as Nph=(p*q*Z) / N. The number of phase windings, m, is at least 3, m≧3, and m is an integer. The number of stator slots, Qs, follows the rule Qs=2p*m*q.

[0032] The U-phase branch of the upper matrix starts at a phase terminal Uk in the outermost layer Lz of slot S1. The hairpin connector 4 is represented by an arrow pointing to the slot and phase to which the hairpin extends. The dashed arrow indicates that the hairpin winding 4 may extend in any number of slots and layers as required. The branch terminates at a neutral terminal NUk in the innermost layer L1 of slot SQ-(2*q). The U-phase branch of the lower matrix starts at a phase terminal Ul in the innermost layer L1 of slot S1. The winding direction of the hairpin connector 4 has the opposite direction of rotation to the branch of the upper matrix. The branch terminates at a neutral terminal NUl in the outermost layer Lz of slot S1+(3*q). When the two branches of the U phase shown in FIG. 6 are mounted on a stator core, slot S1 is one of the common phase slots 51, slot SQ-(2*q) is the first offset neutral slot 57, and slot S1+(3*q) is the second offset neutral slot 58.

[0033] The V-phase branch of the upper matrix starts at a phase terminal Vk in the outermost layer Lz of slot S1+(2*q). The branch terminates at a neutral terminal NVk in the innermost layer L1 of slot SQ. The V-phase branch of the lower matrix starts at a phase terminal Vl in the innermost layer L1 of slot S1+(2*q). The branch terminates at a neutral terminal NVl in the outermost layer Lz of slot S1+(5*q). When the two branches of the V-phase are mounted in the stator core, slot S1+(2*q) is one of the common phase slots 51, slot SQ is the first offset neutral slot 57, and slot S1+(5*q) is the second offset neutral slot 58.

[0034] The W-phase branch of the upper matrix starts at a phase terminal Wk in the outermost layer Lz of slot S1+(4*q). The branch terminates at a neutral terminal NWk in the innermost layer L1 of slot S1+q. The W-phase branch of the lower matrix starts at a phase terminal Wl in the innermost layer L1 of slot S1+(4*q). The branch terminates at a neutral terminal NWl in the outermost layer Lz of slot SQ-(4*q). When the two branches of the W-phase are mounted in the stator core, slot S1+(4*q) is one of the common phase slots 51, slot S1+q is the first offset neutral slot 57, and slot SQ-(4*q) is the second offset neutral slot 58.

[0035] The terminal slot range 18 of the winding structure extends from slot SQ-(4*q) through slot S1 to slot S1+(4*q). No phase or neutral terminals extend from slots SQ-q and SQ-(3*q), resulting in relatively short spot-welded electrical interconnects 16 surrounded by relatively long phase and neutral terminals in terminal connection range 17 (FIG. 4). When the generalized winding pattern is applied to the exemplary embodiment of FIGS. 4 and 5, the shown windings are those starting from phase terminals U1, V1, W1 and U3, V3, W3, and the stator core 2 has the following parameters: z = 8 layers per slot, p = 4 pole pairs, q = 2 slots per pole and per phase, N=4 parallel branches, Nph=32 turns of phases in series, k=3 phases, Qs=48 slots.

[0036] In FIG. 7, a generalized schematic diagram of a winding structure according to another embodiment is shown only for the U phase. The nomenclature and conditional statements made for FIG. 6 apply analogously to FIG. 7. However, an embodiment is shown for a stator with a number N of parallel branches, N<2q, which is less than twice the number of slots per pole and per phase. The branches start at phase terminals Uk in the outermost layer Lz of slots S1 and complete their winding around, but do not terminate at, the innermost layer L1 of slots SQ-(2*q). Instead, the end section 8 extending from slots SQ-(2*q) is connected at a first end to a jumper 19, which is connected at its second end to the end section 8 extending from the innermost layer L1 of slots S1. From here, the branch changes the direction of rotation of the winding direction of the hairpin connector 4 and terminates at a neutral terminal NUk in the outermost layer Lz of slots S1+(3*q). In this embodiment, all phase terminals Un of the branches per phase can be introduced only through the outermost layer Lz, while the corresponding neutral terminals NUn leave on the same layer, the outermost layer Lz. On the innermost layer L1, the configuration of jumpers 19 allows a parallel connection while redistributing the outputs of the branches towards the input layer. Those skilled in the art will understand that the phase terminals Un and the corresponding neutral terminals NUn can alternatively be arranged on the innermost layer L1, with the connections by jumpers 19 realized on the outermost layer Lz.

[0037] In Fig. 8 a generalized schematic diagram of a winding structure according to another embodiment is shown, in which the extension of the terminal connection area 17 (Fig. 9) around the circumference of the stator 1 is reduced. The nomenclature and conditional statements made for Fig. 6 apply analogously to Fig. 8. The U and V phases are similar to the embodiment of Fig. 6 and are not shown again. This embodiment differs only with respect to the W phase, but this difference may apply to any one of the phases.

[0038] The W-phase winding has multiple parallel branches, two of which are shown, one in the upper matrix and one in the lower matrix. In the upper matrix, a phase terminal Wk extends from the outermost layer Lz of slots S+(4*q) and a neutral terminal NWk extends from the innermost layer L1 of slots S1+q. In the lower matrix, a phase terminal Wl extends from the innermost layer L1 of slots SQ-q and a neutral terminal NWl extends from the outermost layer Lz of slots S1+q. A phase terminal Wk extends from a first offset phase slot 52 and a phase terminal Wl extends from a second offset phase slot 53. The first offset phase slot 52 is circumferentially offset with respect to at least one second offset phase slot 53. However, both neutral terminals NWk, NWl extend from one common neutral slot 56. By offsetting half of the phase terminals of at least one phase, the resulting structure does not enclose any of the relatively short electrical interconnections 16 spot welded between the relatively long phase and neutral terminals in the terminal connection area 17, as can be seen from FIG.

[0039] In Fig. 9, another embodiment of a stator 1 for an electric machine is shown in a perspective view. The end sections 8, which extend outside the stator core 2 at the welded ends 10, are straight until after insertion into the stator core 2 and are then bent into the shape shown, the end sections 8 being bent alternately from layer to layer in a clockwise and counterclockwise direction. The hairpin windings 3 define a three-phase winding for the three phases U, V and W. Each phase winding has four parallel branches starting at phase terminals Un, Vn, Wn and terminating at neutral terminals NUn, NVn, NWn, which are explained in more detail with reference to Fig. 10.

[0040] In Fig. 10 an enlarged detail view of Fig. 9 is shown. Figs. 9 and 10 are explained together. All phase terminals Un, Vn, Wn and neutral terminals NUUn, NVn, NWn are arranged at a welded end 10. The hairpin conductors 4 forming one branch are electrically interconnected in series by spot welding at the end section 8. The end section 8 forming the phase terminals Un, Vn, Wn and neutral terminals NUUn, NVn, NWn extends axially beyond the end section 8 forming a spot welded electrical interconnection 16. The four phase terminals Un of the parallel branches of the U-phase winding are connected respectively to the U-phase busbar 12, the phase terminals Vn of the V-phase winding are connected to the V-phase busbar 14 and the phase terminals Wn of the W-phase winding are connected respectively to the W-phase busbar 15. All neutral terminals NUUn, NVn, NWn are connected to the neutral busbar 11 forming a star connection in this embodiment. The terminal connection area 17 is defined by the sector of the circumference of the stator 1 occupied by the phase terminals Un, Vn, Wn and the neutral terminals NUn, NVn, NWn at the welded end 10. The terminal connection area 17 extends over 1 / 4 of the circumference of the stator 1 or over 12 of the 48 slots. The extension of the terminal connection area 17 is reduced and therefore more compact than that shown in FIG.

[0041] The hairpin winding 3 defining the three-phase winding has four parallel branches, one for each phase U, V and W. The phase terminals are designated U1, U2, U3, U4, V1, V2, V3, V4, W1, W2, W3 and W4 and the neutral terminals are designated NU1, NU2, NU3, NU4, NV1, NV2, NV3, NV4, NW1, NW2, NW3 and NW4. The phase terminals U1, U2, V1, V2, W1, W2 and the neutral terminals NU3, NU4, NV3, NV4, NW3, NW4 are arranged on the outermost layer L8 of the radially adjacent layers Li, and the phase terminals U3, U4, V3, V4, W3, W4 and the neutral terminals NU1, NU2, NV1, NV2, NW1, NW2 are arranged on the innermost layer L1 of the radially adjacent layers Li. In the illustrated embodiment, the phase terminals Un, Vn, Wn are evenly distributed between the outermost layer Lz and the innermost layer L1. The phase terminals Un, Vn, Wn and the neutral terminals NUUn, NVn, NWn are concentrated in one sector of the circumference of the stator 1, the terminal connection area 17. The row of radially extending end sections 8 generally corresponds to the 48 slots of the stator 1, provided that the end sections 8 are all bent in the clockwise and counterclockwise direction at the same radial distance. The terminal connection range 17 therefore extends over 12 of the 48 slots or over a 90° circular sector of the stator 1 in this embodiment. The terminal connection range 17 does not include any slots or rows having end sections 8 with relatively short spot-welded electrical interconnections 16. All welding operations for the connection of the phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn to the busbars 11, 12, 14, 15 are limited to ¼ of the stator circumference.

[0042] Figure 11 shows an enlarged detail of Figure 9 with exploded views of neutral busbar 11, U-phase busbar 12, V-phase busbar 14, and W-phase busbar 15. Figure 12 shows the detail of Figure 11 in a perspective view with neutral busbar 11, U-phase busbar 12, V-phase busbar 14, and W-phase busbar 15 shown in their final positions as they are attached to the welded ends 10 of the hairpin windings 3.

[0043] In FIG. 13, an example of a schematic diagram of a winding structure for another embodiment of a stator is shown. The assignment of the phase terminals Un, Vn, Wn and neutral terminals NUUn, NVn, NWn of the hairpin winding to the slots 5 of the stator is illustrated. The matrix represents the slots 5 as columns and the layers L1 to L8 as rows. The top row lists the slot numbers 1 to 48. The left column lists the layer designations L1 to L8. The matrix is ​​divided into three parts, which can be understood in consecutive order by the slot numbers. The notation of the matrix elements indicates the path of each branch through the slots and layers. The notation is in the form of "Ux_y" for the U-phase branch, "Vx_y" for the V-phase branch, and "Wx_y" for the W-phase branch, where x indicates the branch number and y indicates the consecutive serial number from the respective phase terminals Un, Vn, Wn to the respective neutral terminals NUUn, NVn, NWn of each branch. Therefore, the matrix elements including the four phase terminals of the U phase are written as U1_1, U2_1 in the outermost layer L8 of slot numbers 1 and 2, and U3_1, U4_1 in the innermost layer L1. Therefore, the four phase terminals of the V phase are written as V1_1, V2_1 in the outermost layer L8 of slot numbers 5 and 6, and V3_1, V4_1 in the innermost layer L1. Therefore, the four phase terminals of the W phase are written as W1_1, W2_1 in the outermost layer L8 of slot numbers 9, 10, 45, and 46, and W3_1, W4_1 in the innermost layer L1.

[0044] As an example, the structure of the hairpin winding 3 will be described with respect to the first branch of the U-phase. The leg 6 (see FIG. 3) forming the phase terminal U1 is arranged in the outermost layer L8 in slot number 1, with matrix element notation U1_1. The second leg 6 of the same hairpin conductor 4 is arranged in the adjacent layer L7 in slot number 7 as the adjacent negative pole of the U-phase winding, with matrix element notation U1_2. The distance from the layer L8 of slot number 1 to the layer L7 of slot number 7 is the slot pitch of the hairpin conductor 4. The slot pitch, which is six slots 5 in the circumferential direction and one layer Li in the axial direction, is the same for all hairpin conductors 4 of the hairpin winding 3. Further as an example, the path of the first branch of the U-phase winding will be described. The end section 8 of leg 6, labeled U1_2, is spot welded at the weld end 10 to U1_3 in the outermost layer L8 of slot number 13 as the next positive pole of the U-phase winding, and to the next second hairpin conductor 4, labeled U1_4 in the adjacent layer L7 of slot number 19 as the next negative pole of the U-phase winding. The end section 8 of leg 6, labeled U1_4, is spot welded to the third hairpin conductor 4 having the designation U1_5 in layer L8 of slot number 25 as the positive pole, and U1_6 in layer L7 of slot number 31 as the negative pole, etc. It should be noted that the slot pitch, which is 6 slots in the circumferential direction and 1 layer Li in the axial direction, is also extended on the weld end 10 by the bent end section 8, where both end sections 8 of each weld pair 16 are offset by half the slot pitch (see FIG. 9). The fourth hairpin conductor 4 returns to the negative U-phase pole with a leg designated U1_8 in slot number 43. The second winding around the stator core 2 again starts with the fifth hairpin conductor 4 with designation U1_9 in the next layer L6, this time in slot number 1. The branching continues, this time oscillating between layers L6 and L5, before changing to layers L4 and L3 after another turn around the stator core 2. The final winding in the inner layers L2 and L1 ends with the sixteenth hairpin conductor 4 of the branch. Designation U1_32 indicates the position of the leg 6 with the neutral terminal NU1 at its end section 8 in the innermost layer L1 in slot number 43.Note that neutral terminal NU1, due to its offset over half the slot pitch, is not located in a circumferential position of slot number 43, but rather in a circumferential position of slot number 46. Note further that end section 8 of phase terminal U1 of the same branch in the outermost layer L8 is offset in the opposite direction so that it also has a circumferential position of slot number 46.

[0045] As for the other branches with phase terminals U2, V1, V2, W1, W2 in the outermost layer L8, they take a parallel path to the above mentioned branches and start from slot numbers 2, 5, 6, 9 and 10 respectively. The slot pitch of the hairpin conductors 4 is identical. The branches ending at the neutral terminals NU3, NU4, NV3, NV4, NW3, NW4 in the outermost layer L8 must also take a parallel path to avoid crossing branches and to provide the same slot pitch of the hairpin conductors 4. Thus, the branches starting from the phase terminals U3, U4, V3, V4, W3, W4 in the innermost layer L1 are wound around the stator core 2 in the opposite rotational direction to the branches with phase terminals U1, U2, V1, V2, W1, W2 in the outermost layer L8. The branches start from the innermost layer L1 and take a path towards the slots with smaller consecutive numbers. For example, the third branch of the W-phase winding starts at phase terminal W3 with designation W3_1 in the innermost layer L1 with slot number 45. The second leg 6 of the same hairpin conductor 4 is located as the adjacent negative pole of the W-phase winding in the adjacent layer L2 with slot number 39 with matrix element designation W3_2. The distance from layer L1 with slot number 45 to layer L2 with slot number 39 is the same slot pitch of the hairpin conductor 4, which is 6 slots in the circumferential direction and 1 layer Li in the axial direction. Thus, all branches with phase terminals Un, Vn, Wn and neutral terminals NUn, NVn, NWn run parallel paths evenly distributed in the innermost layer L1 and the outermost layer L8.

[0046] The phase terminals Un, Vn extend in pairs from a common phase slot 51, called a slot. The phase terminals U1 and U3 extend from a common phase slot 51 having slot number 1. However, those skilled in the art will appreciate that the end sections 8 in the outermost layer L8 are bent in the opposite rotational direction to the end sections 8 in the innermost layer L1, so that the phase terminals Un, Vn extending in pairs from the common phase slot 51 are not arranged in the same row at the weld end 10. In the illustrated embodiment, the phase terminals U1 and U3 are offset in the circumferential direction by six rows or slots, i.e., the slot pitch of the hairpin conductor, respectively. In the illustrated embodiment, pairs of parallel branch phase terminals Un, Vn extend in pairs from adjacently arranged common phase slots 51. The common phase slots 51 of the U-phase winding are slot numbers 1 and 2, and the common phase slots 51 of the V-phase winding are slot numbers 5 and 6. Phase terminals Wn of the W-phase winding are offset, with W1 and W2 extending from slot numbers 9 and 10, referred to as the first offset phase slot 52, and W3 and W4 extending from slot numbers 45 and 46, referred to as the second offset phase slot 53.

[0047] The neutral terminals NU1, NU2, NV1 and NV2 of the parallel branches of each phase winding U, V extend from the innermost layer L1 of the first offset neutral slots 57, and the neutral terminals NU3, NU4, NV3 and NV4 extend from the outermost layer Lz of the second offset neutral slots 58. The first offset neutral slots 57 of the U phase winding are slot numbers 43 and 44, which are offset with respect to the second offset neutral slots 58 of the U phase winding, which are slot numbers 7 and 8. The first offset neutral slots 57 of the V phase winding are slot numbers 47 and 48, which are offset with respect to the second offset neutral slots 58 of the V phase winding, which are slot numbers 11 and 12. The offset is 12 slots in each case. The neutral terminals NW1, NW2, NW3, and NW4 of the W-phase winding extend from a common neutral slot 56, which is slot numbers 3 and 4 in this embodiment.

[0048] The common phase slot 51, the common neutral slot 56, the first offset neutral slot 57, the second offset neutral slot 58, the first offset phase slot 52, and the second offset phase slot 53 together define a terminal slot range 18 that extends circumferentially over a fraction of the total number of slots. In this embodiment, the terminal slot range 18 extends from slot number 43 to slot number 12, i.e., 18 slots. None of the slots in the terminal slot range are occupied by non-terminal end sections 8 in the outermost layer L8 or the innermost layer L1. The terminal slot range 18 is larger in number of slots than the terminal connection range 17 by the slot pitch of the hairpin connector, which is 6 slots (see FIG. 9). [Explanation of symbols]

[0049] 1 Stator 2 Stator core 3 Hairpin Winding 4 Hairpin Conductor 5 Slots 51 Common Phase Slot 52 1st offset phase slot 53 Second offset phase slot 56 Common Neutral Slots 57 1st offset neutral slot 58 Second offset neutral slot 6 legs 7 head 8 End section 9 Insertion end 10 Welded Ends 11 Neutral busbar 12 U-phase busbar 14 V-phase busbar 15 W phase busbar 16 Spot welded interconnects 17 Terminal connection range 18 Terminal Slot Range 19 Jumper A Longitudinal axis Li layer U, V, W phase windings Un phase terminal, U phase winding Vn phase terminal, V phase winding Wn phase terminal, W phase winding NUn Neutral terminal, U phase winding NVn Neutral terminal, V phase winding NWn Neutral terminal, W phase winding

Claims

1. A stator (1) for an electric machine, comprising: The rotor includes a stator core (2) having a plurality of slots (5) and a hairpin winding (3), The hairpin winding (3) comprises a hairpin conductor (4) with two legs (6) connected at a head (7), the slot pitch between the two legs (6) being defined by the head (7), the slot pitch of each one of the hairpin conductors (4) being the same; the leg (6) of the hairpin conductor (4) is received in the slot (5) in at least two radially adjacent layers (Li), the head (7) extends outside the stator core (2) at an insertion end (9), and an end section (8) of the leg (6) opposite the head (7) extends outside the stator core (2) at a welded end (10); said hairpin winding (3) defining at least three phase windings (U, V, W), each phase winding having at least one branch, each branch of each phase winding having a phase terminal (Un, Vn, Wn) formed on one of said end sections (8) for connection to a phase busbar and a neutral terminal (NUn, NVn, NWn) formed on one of said end sections (8) for connection to a neutral busbar; all of the phase terminals and the neutral terminals are disposed on at least one of the outermost layer (Lz) of the radially adjacent layers (Li) and the innermost layer (L1) of the radially adjacent layers (Li) at the welded end (10) of the hairpin winding (3); A stator (1) for an electric machine.

2. 2. The stator according to claim 1, wherein a terminal connection area (17) is defined by a sector of the circumference of the stator (1) occupied by the phase terminals (Un, Vn, Wn) and the neutral terminal (NUn, NVn, NWn) at the welded end (10), and the extension of the terminal connection area (17) around the circumference of the stator (1) is minimized.

3. 3. A stator according to claim 1 or 2, wherein each phase winding has a plurality of parallel branches, and at least one pair of phase terminals (Un, Vn, Wn) of the parallel branches of at least one phase winding both extend from one common phase slot (51).

4. 4. The stator according to claim 3, wherein pairs of phase terminals (Un, Vn, Wn) of the parallel branches of the at least one phase winding extend in pairs from a plurality of adjacently arranged common phase slots (51).

5. 5. The stator of claim 1, wherein each phase winding has a plurality of parallel branches, a first half of the phase terminals (Un, Vn, Wn) of the parallel branches of at least one phase winding extending from an innermost layer (L1) of at least one first offset phase slot (52) and a second half of the phase terminals (Un, Vn, Wn) of the at least one phase winding extending from an outermost layer (Lz) of at least one second offset phase slot (53), the at least one first offset phase slot (52) being circumferentially offset with respect to the at least one second offset phase slot (53).

6. 6. The stator according to claim 1, wherein each phase winding has a plurality of parallel branches, and wherein at least one pair of neutral terminals (NUn, NVn, NWn) of the parallel branches of at least one phase winding both extend from one common neutral slot (56).

7. 7. The stator of claim 6, wherein pairs of the neutral terminals (NUn, NVn, NWn) of the parallel branches of the at least one phase winding extend in pairs from a plurality of adjacently disposed common neutral slots (56).

8. 8. The stator according to claim 1, wherein each phase winding has a plurality of parallel branches, a first half of the neutral terminals (NUn, NVn, NWn) of the parallel branches of at least one phase winding extending from an innermost layer (L1) of at least one first offset neutral slot (57) and a second half of the neutral terminals (NUn, NVn, NWn) of the at least one phase winding extending from an outermost layer (Lz) of at least one second offset neutral slot (58), the at least one first offset neutral slot (57) being circumferentially offset with respect to the at least one second offset neutral slot (58).

9. 7. A stator according to claim 6, wherein the common phase slot (51), the first offset phase slot (52), the second offset phase slot (53), the common neutral slot (56), the first offset neutral slot (57), and the second offset neutral slot (58) together define a terminal slot range extending circumferentially over a fraction of the total number of slots (5).

10. 10. A stator according to claim 6, wherein the terminal slot area extends over a continuous area of ​​adjacent slots (51, 52, 53, 56, 57, 58) in which at least one phase terminal or at least one neutral terminal is arranged.

11. 11. A stator according to claim 1, wherein each phase winding has a plurality of parallel branches, and at least a phase terminal of a first branch and a neutral terminal of a second branch are arranged on one of an outermost layer (Lz) and an innermost layer (L1), and the first branch and the second branch are connected on opposite layers of the outermost layer (Lz) and the innermost layer (L1).

12. 2. The stator of claim 1, wherein the phase terminals (Un, Vn, Wn) are evenly distributed between the outermost layer (Lz) and the innermost layer (L1).

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