Electric motor stator, electric motor, transmission system and vehicle

Abstract

The present disclosure relates to an electric motor stator. A stator coil in the electric motor stator includes three first phase windings, each of which includes multiple layer windings and the multiple layer windings are connected in series, and each first phase winding includes multiple hairpin conductors connected in series; the hairpin conductor includes a short-span hairpin conductor and a longspan hairpin conductor, a first conductor leg and a second conductor leg of the short-span hairpin conductor are respectively arranged in two adjacent layers, and a first conductor leg and a second conductor leg of the long-span hairpin conductor are respectively arranged in an innermost layer and an outermost layer, wherein a welding end of an outgoing wire section of each hairpin conductor is aligned radially against a welding end of an incoming wire section of another adjacent hairpin conductor in the same first phase winding.

Description

[0001] Description

[0002] Electric motor stator, electric motor, transmission system and vehicle

[0003] Technical Field

[0004] The present disclosure relates to an electric motor stator, an electric motor comprising the electric motor stator, a transmission system comprising the electric motor and a vehicle comprising the transmission system.

[0005] Background Art

[0006] A stator of an AC motor is generally composed of a laminated core and a stator coil. A periodically changing AC current is fed into the stator coil, which causes a constantly rotating air gap magnetic field of the same frequency to be excited. The rotating air gap magnetic field can drive rotation of the rotor of the AC motor, which can be either an asynchronous motor or a synchronous motor.

[0007] To improve the performance of the AC motor, flat wire conductors are increasingly used for the stator coils of AC motors. Compared to round wire conductors, flat wire conductors are conducive to an increased motor slot fill rate and therefore may generate a stronger magnetic field, which in turn increases the power density.

[0008] Summary of the Invention

[0009] The present disclosure provides an electric motor stator. A stator coil of the electric motor stator is composed of flat wire, in particular hairpin conductors (Hair- Pin). Welding ends of the respective hairpin conductors of the electric motor stator according to the present disclosure have neat arrangement, which makes wiring of the welding ends easy and also facilitates simplification of tooling used for twisting the welding ends.

[0010] The present disclosure provides an electric motor stator. The electric motor stator comprises: a stator core constructed as a hollow cylinder and arranged with multiple slots in a circumferential direction; and a stator coil comprising three first phase windings, each of which comprising multiple layer windings connected in series, and each first phase winding comprising multiple hairpin conductors connected in series, wherein the hairpin conductor respectively has a first conductor leg and a second conductor leg, and a non-welding end connected in between, the first conductor leg and the second conductor leg are respectively arranged in different slots, multiple layers of conductor legs are arranged in each slot, an end part of the first conductor leg has an incoming wire section, an end part of the second conductor leg has an outgoing wire section, and the incoming wire section and the outgoing wire section extend out of the slot, wherein the hairpin conductor comprises a short-span hairpin conductor and a long-span hairpin conductor, a first conductor leg and a second conductor leg of the short-span hairpin conductor are respectively arranged in two adjacent layers, and a first conductor leg and a second conductor leg of the long-span hairpin conductor are respectively arranged in an innermost layer and an outermost layer, wherein a welding end of an outgoing wire section of each hairpin conductor is aligned radially against a welding end of an incoming wire section of another adjacent hairpin conductor in the same first phase winding.

[0011] According to an embodiment of the present disclosure, a pitch of the shortspan hairpin conductor is a uniform pitch, and a pitch of the long-span hairpin conductor is a short pitch or a long pitch.

[0012] According to an embodiment of the present disclosure, the number of slots per pole per phase of the electric motor stator is 3.

[0013] According to an embodiment of the present disclosure, the number of layers of the conductor leg is 2(N+2), wherein N is a positive integer.

[0014] According to an embodiment of the present disclosure, the number of layers of the conductor leg is 6; each first phase winding comprises a first layer winding, a second layer winding and a third layer winding, the first layer winding is arranged in a first layer and a second layer, the second layer winding is arranged in a third layer and a fourth layer, and the third layer winding is arranged in a fifth layer and a sixth layer; a short-span hairpin conductor is arranged in the first layer winding, the second layer winding and the third layer winding, and the short-span hairpin conductor is slanted in a clockwise direction; a long-span hairpin conductor is arranged between the first layer winding and the third layer winding, and the long- span hairpin conductor is slanted in the clockwise direction; the short-span hairpin conductor is arranged between the first layer winding and the second layer winding, and the short-span hairpin conductor is slanted in an anticlockwise direction, and the short-span hairpin conductor is arranged between the second layer winding and the third layer winding, and the short-span hairpin conductor is slanted in an anticlockwise direction.

[0015] According to an embodiment of the present disclosure, the number of slots of the electric motor stator is 54, a pole pitch is 9, and the number of slots per pole per phase is 3; each pole-phase group in the first layer winding, the second layer winding and the third layer winding comprises first, second and third short-span hairpin conductors, and the three short-span hairpin conductors have a pitch of 9 and are slanted in the clockwise direction; the pole-phase group between the first layer winding and the second layer winding comprises first, second and third shortspan hairpin conductors, and the three short-span hairpin conductors have a pitch of 9 and are slanted in the anticlockwise direction, wherein the first short-span hairpin conductors are connected in series to form a first series circuit, the second shortspan hairpin conductors are connected in series to form a second series circuit, and the third short-span hairpin conductors are connected in series to form a third series circuit; a pole-phase group between the first layer winding and the third layer winding comprises first, second and third long-span hairpin conductors, and the three long-span hairpin conductors are slanted in the clockwise direction, and the first long-span hairpin conductor has a pitch of 11 and connects the first series circuit and the third series circuit, the second long-span hairpin conductor has a pitch of 8 and connects the second series circuit and the first series circuit, and the third long- span hairpin conductor has a pitch of 8 and connects the third series circuit and the second series circuit.

[0016] According to an embodiment of the present disclosure, the stator coil further comprises three second phase windings, the second phase winding and the first phase winding have the same structure, the arrangement of the hairpin conductors in the second phase winding has an offset pole pitch relative to the arrangement of the hairpin conductors in the first phase winding, and the first phase winding and the second phase winding are connected in parallel.

[0017] According to an embodiment of the present disclosure, each first phase winding has a winding incoming wire end and a winding outgoing wire end, and the winding incoming wire end is connected to a first conductor leg of the outermost layer, and the winding outgoing wire end is connected to another second conductor leg of the outermost layer.

[0018] The present disclosure further provides an electric motor, the electric motor comprising the electric motor stator mentioned above.

[0019] The present disclosure further provides a transmission system, the transmission system comprising the electric motor mentioned above.

[0020] The present disclosure further provides a vehicle, the vehicle comprising the transmission system mentioned above.

[0021] Brief Description of the Drawings

[0022] In order to explain the technical solutions of embodiments of the present disclosure more clearly, drawings required for describing the embodiments are briefly described below. Obviously, the drawings in the description below are merely some exemplary embodiments of the present disclosure, and those skilled in the art could obtain other drawings based on these drawings without expending inventive effort.

[0023] Fig. 1 is a structural schematic drawing of an electric motor stator according to an embodiment of the present disclosure;

[0024] Fig. 2 is a schematic drawing of a welding end of a stator coil according to an embodiment of the present disclosure;

[0025] Fig. 3 is a schematic drawing of a non- welding end of a stator coil according to an embodiment of the present disclosure;

[0026] Fig. 4 is a schematic drawing of a short-span hairpin conductor according to an embodiment of the present disclosure;

[0027] Fig. 5 is a schematic drawing of a long-span hairpin conductor according to an embodiment of the present disclosure;

[0028] Fig. 6 is a schematic drawing of another long-span hairpin conductor according to an embodiment of the present disclosure;

[0029] Fig. 7 is a winding diagram of a W phase winding of a stator coil according to an embodiment of the present disclosure;

[0030] Fig. 8 is a winding diagram of a V phase winding of a stator coil according to an embodiment of the present disclosure; and

[0031] Fig. 9 is a winding diagram of a U phase winding of a stator coil according to an embodiment of the present disclosure.

[0032] Detailed Description of the Invention

[0033] In order to clarify the technical solution objective, the technical solution and advantages of the present disclosure, the technical solution of embodiments of the present disclosure is described clearly and completely below in conjunction with the drawings accompanying particular embodiments of the present disclosure. In the drawings, identical reference numerals denote identical components. It must be explained that the embodiments described are some, not all, of the embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of the present disclosure without the need for inventive effort shall fall within the scope of protection of the present disclosure.

[0034] Compared with the embodiments shown in the drawings, a feasible embodiment solution within the scope of protection of the present disclosure may have fewer components, another component not shown in any of the drawings, a different component, a component arranged differently, or a component connected differently, etc. Further, two or more components in a drawing may be implemented in a single component, or a single component shown in a drawing may be implemented as a plurality of separate components.

[0035] Fig. 1 is a structural schematic drawing of an electric motor stator 100 according to an embodiment of the present disclosure. The electric motor stator 100 comprises a stator core 110. The stator core 110 is constructed as a hollow cylinder. The stator core 110 can, for example, be formed by stacking silicon steel plates. Multiple slots 101 are arranged along the circumference of the stator core 110. In the embodiment shown in Fig. 1, the stator core 110 has 54 slots 101. In an embodiment according to the present disclosure, an insulator 102, such as an insulating paper, may also be arranged in the slots 101.

[0036] A stator coil 120 is arranged in the slots 101 of the stator core 110. In an embodiment of an electric motor that is constructed as an AC motor, such as an asynchronous motor or a synchronous motor, the stator coil 120 has three phase windings for three phases: U, V and W. Each phase winding has at least one branch. In the case of multiple branches, multiple branches are connected in parallel. In the embodiment shown in Fig. 1, a phase winding with two branches is shown as an example; each branch of each phase winding has two connection ends 150, i.e. a winding incoming wire end and a winding outgoing wire end. A total of 12 connection ends 150 are shown in Fig. 1.

[0037] According to an embodiment of the present disclosure, a phase winding may, for example, have multiple layers, that is, a phase winding may comprise multiple layer windings, and these layer windings are connected in series. In the embodiment shown in Fig. 1, a phase winding consists of three layer windings. These three layer windings form three concentric rings. Correspondingly, multiple layers of conductor legs need to be arranged in a slot 101, and the number of layers of the conductor legs is equal to the number of layer windings multiplied by 2. In the embodiment shown in Fig. 1, 6 layers of conductor legs are arranged in a slot 101.

[0038] Each phase winding consists of multiple hairpin conductors 121 connected in series. The specific structure of the hairpin conductor 121 is shown in Fig. 4 to Fig. 5. The hairpin conductor 121 respectively has a first conductor leg 401 and a second conductor leg 402, and a non-welding end 407 connected in between, the first conductor leg 401 and the second conductor leg 402 are respectively arranged in different slots 101, an end part of the first conductor leg 401 has an incoming wire section 403, an end part of the second conductor leg 402 has an outgoing wire section 404, and the incoming wire section 403 and the outgoing wire section 404 extend out of the slot 101. The incoming wire section 403 of the first hairpin conductor 121 is bent relative to the first conductor leg 401, for example, in an anti- clockwise direction, so as to approach and abut the outgoing wire section 404 of the second hairpin conductor 121; the outgoing wire section of the second hairpin conductor 121 is bent relative to the second conductor leg 402, for example, in a clockwise direction, so as to approach and abut the incoming wire section 403 of the first hairpin conductor 121. An incoming welding end 405 is formed at the end of the incoming wire section 403, and an outgoing welding end 406 is formed at the end of the outgoing wire section 404. The incoming welding end 405 of the first hairpin conductor 121 and the outgoing welding end 406 of the second hairpin conductor 121 are welded together, and multiple hairpin conductors 121 are connected in this manner in sequence to form a phase winding. In Fig. 1, an upper end of the stator coil 120 is a welding end 130 of the stator coil 120, which will also be shown in detail in Fig. 2. In Fig. 1, a lower end of the stator coil 120 is a nonwelding end of the stator coil 120, that is, a crown end 140, which will also be shown in detail in Fig. 3.

[0039] Fig. 2 is a schematic drawing of a welding end 130 of a stator coil 120 according to an embodiment of the present disclosure. As shown in Fig. 2, an incoming wire section 403 is bent anticlockwise in a circumferential direction, and an outgoing wire section 404 is bent clockwise in the circumferential direction, and an outgoing welding end 406 of the outgoing wire section 404 of each hairpin conductor 121 is aligned radially against an incoming welding end 405 of the incoming wire section 403 of another adjacent hairpin conductor 121 in the same first phase winding. In the present disclosure, all incoming wire sections 403 are uniformly bent anticlockwise, and all outgoing wire sections 404 are uniformly bent clockwise, with no specially bent incoming or outgoing wire sections. All welding ends 405, 406 are aligned against each other in pairs, which makes welding between the welding ends 405, 406 very easy. In the prior art, especially in the case where there are multiple layers of winding of the phase windings, there are situations where the welding ends cannot be aligned against each other, and in order to connect such welding ends, additional conductors are often required to bridge the two welding ends, which adds to the complexity of the welding operation; in another aspect, there are special requirements for tooling used to bend the incoming and outgoing wire sections, adding to the complexity of the tooling, or the tooling cannot bend all the incoming and outgoing wire sections into place through a simple operation, such as performing a bending operation twice.

[0040] In order to achieve the neat arrangement of welding ends shown in Fig. 2, a new type of hairpin conductor needs to be designed and arranged. In one aspect, the new hairpin conductor is needed to connect multiple layer windings in a phase winding in series. In another aspect, where the number of slots per pole per phase or a pole-phase group is greater than 1, the new hairpin conductor is also required for a series connection between hairpin conductors in different orders in a polephase group. This will be explained in detail later. Fig. 3 is a schematic drawing of a non- welding end 140 of a stator coil 120 according to an embodiment of the present disclosure. It can be seen from Fig. 3 that the hairpin conductor 121 has two shapes, a short-span hairpin conductor 310 and a long-span hairpin conductor 320. The first conductor leg and the second conductor leg of the short-span hairpin conductor 310 are respectively arranged in two adjacent layers of the stator slot. The first conductor leg and the second conductor leg of the long-span hairpin conductor 320 are respectively arranged in an innermost layer and an outermost layer of the stator slot, and in the case of six layers shown in Fig. 1 to Fig. 3, the two conductor legs of the long-span hairpin conductor 320 are arranged in the first and sixth layers, respectively. According to an embodiment of the present disclosure, a pitch of the short-span hairpin conductor 310, for example, may be a uniform pitch, and a pitch of the long-span hairpin conductor 320, for example, may be a short pitch or a long pitch. According to an embodiment of the present disclosure, “pole pitch” refers to the number of slots occupied by each pole of the electric motor along an air gap circumferential surface, and the pole pitch is equal to the number of stator slots / number of magnetic poles. “Pitch” refers to the number of slots between two conductor legs of a hairpin conductor spanning thereover. The pitch of the hairpin conductor is called “uniform pitch” when the pitch is equal to the pole pitch; the pitch of the hairpin conductor is called “short pitch” when the pitch is less than the pole pitch; and the pitch of the hairpin conductor is called “long pitch” when the pitch is greater than the pole pitch. Fig. 5 shows a long-span hairpin conductor 321 with a long pitch. By lengthening the non-welding end, the pitch of the two conductor legs of the long-span hairpin conductor 321 is greater than the pole pitch. Fig. 6 shows a long-span hairpin conductor 322 with a short pitch. By twisting the non-welding end, the pitch of the two conductor legs of the long-span hairpin conductor 322 is less than the pole pitch.

[0041] To illustrate more clearly how the hairpin conductor 121, especially the shortspan hairpin conductor 310 and the long-span hairpin conductor 320, are connected into a phase winding and a stator coil, Figs. 7, 8 and 9 illustrate winding diagrams of a stator coil according to an embodiment of the present disclosure. In the embodiment shown in Figs. 7, 8 and 9, the stator coil comprises three phase windings: a W phase winding, a V phase winding and a U phase winding. Each phase winding has two branches, i.e. a first phase winding and a second phase winding, and the first phase winding and the second phase winding are connected in parallel. The stator core has 54 slots, and “1”, “2”, “3”, ..., “54” are respectively used to mark the 54 slots in Figs. 7, 8 and 9. Six conductor legs are arranged in each slot; that is, one slot can be divided into 6 layers, and the 6 layers are respectively marked with “1”, “2”, “3”, “4”, “5” and “6”. According to an embodiment of the present disclosure, the number of layers of the stator slot can also, for example, be 2(N+2), wherein N is a positive integer. In other words, the number of layers of the stator slot can be 6, 8, 10 and so on. The dotted line shown in Figs. 7, 8 and 9 represents a distance spanned by a non-welding end of a hairpin conductor, and the number of layers and the number of slots spanned by the non-welding end of the hairpin conductor are clearly visible in the winding diagrams shown in Figs. 7, 8 and 9. The solid line shown in Fig. 7 represents a connection between an incoming wire section of a hairpin conductor and an outgoing wire section of another hairpin conductor, and the number of layers and the number of slots spanned by the connection of the hairpin conductors are clearly visible in the winding diagrams shown in Figs. 7, 8 and 9. As shown in Figs. 7, 8 and 9, the connections between the hairpin conductors in the present disclosure have exactly the same span, i.e. span the same number of layers (2 layers) and the same number of slots (9 slots). Therefore, the incoming wire sections and outgoing wire sections of the hairpin conductors used for bridging have the same span. This makes bending of the incoming and outgoing wire sections simple, and tooling for bending can also be designed more simply.

[0042] Each phase winding, i.e. a first phase winding and a second phase winding, respectively comprises three layer windings, i.e. a first layer winding, a second layer winding and a third layer winding, and the first layer winding is arranged in a first layer and a second layer, the second layer winding is arranged in a third layer and a fourth layer, and the third layer winding is arranged in a fifth layer and a sixth layer. A short-span hairpin conductor is arranged in the first layer winding, the second layer winding and the third layer winding, and the short-span hairpin conductor is slanted in a clockwise direction. The short-span hairpin conductor in the layer winding spans 2 layers and 9 slots. This type of hairpin conductor that spans two layers can form a neater welding end arrangement compared to a hairpin conductor that does not span layers, and in the case where the phase winding comprises a first phase winding and a second phase winding, the space in the slot can be fully utilized to increase the slot fill rate.

[0043] A long-span hairpin conductor is arranged between the first layer winding and the third layer winding, so that the first layer winding and the third layer winding are connected together, and the long-span hairpin conductor is slanted in a clockwise direction. The number of layers spanned by the long-span hairpin conductor is 6. The number of slots spanned by one of the long-span hairpin conductors is 11, and the number of slots spanned by two others is 8, which will be explained in detail later.

[0044] The short-span hairpin conductor is arranged between the first layer winding and the second layer winding, and the short-span hairpin conductor is slanted in an anticlockwise direction, and the short-span hairpin conductor is also arranged between the second layer winding and the third layer winding, and the short-span hairpin conductor is slanted in an anticlockwise direction, wherein the anticlockwise direction is opposite to the clockwise direction. The short-span hairpin conductor between layer windings spans 2 layers and 9 slots.

[0045] A series connection between the three layer windings is achieved by means of long-span hairpin conductors and short-span hairpin conductors arranged between the layer windings. The case where each pole-phase group in each layer winding comprises three hairpin conductors is explained below with continued reference to Figs. 7, 8 and 9.

[0046] In a process of designing a multipole AC motor, the arrangement of phase windings or the connection of the hairpin conductors must be determined first. The arrangement of the phase windings needs to conform to certain principles, such as the number of slots occupied by each phase winding, i.e. the number of hairpin conductors thereof, being equal; the resultant fundamental electric potential and magnetic potential being the maximum; and non-operational harmonics being the minimum, etc. The following takes the embodiment shown in Figs. 7, 8 and 9 as an example to explain the arrangement of phase windings. In this embodiment, the number of phases of the electric motor is m = 3, the number of slots of the electric motor stator is Z = 54, the number of pole pairs is p = 3 (comprising a first pole pair, a second pole pair and a third pole pair), and the number of poles of the electric motor rotor is 2*p = 6. The stator slots are first assigned to each phase and each pole, i.e. the number of slots per pole per phase is determined as q = Z / (2p*m) = 3. The electrical angle range of one pole is 180°. For three-phase windings, each phase occupies an electrical angle of 60°, i.e. a phase band of 60°. The three-phase windings therefore comprise phase bands in sequence: W-, V+, U-, W+, V-, U+. The winding or conductor of phase W is distributed in W-, W+, the winding or conductor of phase V is distributed in V-, V+, and the winding or conductor of phase U is distributed in U-, U+.

[0047] As shown in Figs. 7, 8 and 9, for the first pole pair, slots 1, 2 and 3 are assigned to the W- phase band; slots 4, 5 and 6 are assigned to the V+ phase band; slots 7, 8 and 9 are assigned to the U- phase band; slots 10, 11 and 12 are assigned to the W+ phase band; slots 13, 14 and 15 are assigned to the V- phase band; and slots 16, 17 and 18 are assigned to the U+ phase band.

[0048] For the second pole pair, slots 19, 20 and 21 are assigned to the W- phase band; slots 22, 23 and 24 are assigned to the V+ phase band; slots 25, 26 and 27 are assigned to the U- phase band; slots 28, 29 and 30 are assigned to the W+ phase band; slots 31, 32 and 33 are assigned to the V- phase band; and slots 34, 35 and 36 are assigned to the U+ phase band.

[0049] For the third pole pair, slots 37, 38 and 39 are assigned to the W- phase band; slots 40, 41 and 42 are assigned to the V+ phase band; slots 43, 44 and 45 are assigned to the U- phase band; slots 46, 47 and 48 are assigned to the W+ phase band; slots 49, 50 and 51 are assigned to the V- phase band; and slots 52, 53 and 54 are assigned to the U+ phase band.

[0050] Conductors are arranged in all the slots, and conductors of the same phase (W phase or V phase or U phase) are sequentially connected in series to form a phase winding.

[0051] In an embodiment of the present disclosure, the conductor is constructed as a hairpin conductor. Three hairpin conductors in three slots that are assigned to each pole and each phase form a pole-phase group. Therefore, each pole-phase group in the first layer winding, the second layer winding and the third layer winding comprises first, second and third short- span hairpin conductors. Taking the first phase winding of phase W in Fig. 7 as an example, in the first layer winding that occupies layers 1, 2, a pole-phase group comprises three hairpin conductors (abbreviated as “PIN”); for example, a first PIN spans slots 1, 10, a second PIN spans slots 2, 11, and a third PIN spans slots 3, 12. These three short-span hairpin conductors have a pitch of 9 and are slanted in a clockwise direction.

[0052] The pole-phase group between the first layer winding and the second layer winding comprises first, second and third short- span hairpin conductors. Taking the first phase winding of phase W in Fig. 7 as an example, in the first layer winding that occupies layers 1, 2 and the second layer winding that occupies layers 3, 4, a pole-phase group comprises three hairpin conductors (abbreviated as “PIN”); these three PINs span from layer 3 to layer 2, and the first PIN spans slots 19, 28, the second PIN spans slots 20, 29, and the third PIN spans slots 21, 30. These three short-span hairpin conductors have a pitch of 9 and are slanted in an anticlockwise direction.

[0053] As can be seen from Fig. 7, the short- span hairpin conductor in the layer winding and the short-span hairpin conductor between layer windings both have a pitch of 9. Therefore, the first short-span hairpin conductors in each pole-phase group are connected in series and form a first series circuit; the second short-span hairpin conductors in each pole-phase group are connected in series and form a second series circuit; and the third short-span hairpin conductors in each pole-phase group are connected in series and form a third series circuit.

[0054] In order to connect the first series circuit, the second series circuit and the third series circuit in series, first, second and third long-span hairpin conductors in the pole-phase group between the first layer winding and the third layer winding use long pitch and short pitch. Taking the first phase winding of phase W in Fig. 7 as an example, between the first layer winding that occupies layers 1 , 2 and the third layer winding that occupies layers 5, 6, a pole-phase group comprises three hairpin conductors (abbreviated as “PIN”); these three PINs span from layer 1 to layer 6, and the first PIN spans slots 19, 30 with a pitch of 11 (long pitch), the second PIN spans slots 20, 28 with a pitch of 8 (short pitch), and the third PIN spans slots 21, 29 with a pitch of 8 (short pitch). The first PIN connects the first series circuit and the third series circuit, the second PIN connects the second series circuit and the first series circuit, and the third PIN connects the third series circuit and the second series circuit.

[0055] In the case where a phase winding has three layer windings and the number of slots per pole per phase is 3 (a pole-phase group containing three conductors), if normal short-span hairpin conductors are used instead of the long-span hairpin conductors of the long pitch and short pitch according to the present disclosure, then welding ends of two hairpin conductors cannot approach and align against each other. In order to connect the welding ends of these two hairpin conductors, additional conductors are required for bridging. This adds an extra process and also leads to the presence of welding ends that are not neatly arranged.

[0056] In the embodiments shown in Figs. 7, 8, and 9, a second phase winding is also arranged in phases W, V and U. In each phase, the second phase winding has the same structure as the first phase winding. The hairpin conductor in the second phase winding is offset by one pole pitch, i.e. 9 slots, relative to the hairpin conductor in the first phase winding. The first phase winding and the second phase winding are independent of each other and respectively form series circuits, and the first phase winding and the second phase winding are connected in parallel to form a complete phase winding. In one phase, with the first phase winding already arranged, the hairpin conductors in the second phase winding occupy the free layers in each slot in this phase. Taking phase W as an example, with the first phase winding already arranged, the first layer of slots 10, 11, 12 is free, and the second layer of slots 19, 20, 21 is free; these free layers are used to arrange the hairpin conductors in the second phase winding. The arrangement of the second phase winding allows 6 layers in the 54 slots to be fully utilized, wherein as many conductors as possible are arranged, resulting in a significantly higher slot fill rate.

[0057] According to an embodiment of the present disclosure, the stator winding comprises three forms of hairpin conductor: a short-span hairpin conductor, a long- span hairpin conductor with a short pitch and a long-span hairpin conductor with a long pitch. The 162 hairpin conductors in the stator coil according to the present disclosure, classified according to the number of slots and layers spanned, comprise the following types of hairpin conductor (PIN).

[0058] The stator winding according to the present disclosure uses fewer types of hairpin conductors, which makes the process of manufacturing and processing the hairpin conductors simple.

[0059] According to an embodiment of the present disclosure, the first phase windings of phases W, V and U may, for example, have winding incoming wire ends and winding outgoing wire ends, and the second phase windings of the phases W, V and U may, for example, have winding incoming wire ends and winding outgoing wire ends. The winding incoming wire end is connected to a first conductor leg of an outermost layer, and the winding outgoing wire end is connected to another second conductor leg of the outermost layer. In the embodiments shown in Figs. 7, 8 and 9, the inward arrow indicates the winding incoming wire end, and the outward arrow indicates the winding outgoing wire end. In this embodiment, one of the winding incoming wire end and winding outgoing wire end is arranged at a welding end of the long-pitch long-span hairpin conductor (1-6-11). The other of the winding incoming wire end and winding outgoing wire end is arranged at one end of the short-span hairpin conductor (1-2-9) that is adjacent to the long-pitch long-span hairpin conductor (1-6-11). In other words, welding between the long-pitch long- span hairpin conductor (1-6-11) and the adjacent short-span hairpin conductor (1-2- 9) is eliminated, and the two welding ends respectively act as a winding incoming wire end and a winding outgoing wire end of the corresponding winding.

[0060] According to another aspect of the present disclosure, an electric motor is proposed, comprising the electric motor stator as mentioned above.

[0061] According to another aspect of the present disclosure, a transmission system is proposed, comprising the electric motor as mentioned above.

[0062] According to another aspect of the present disclosure, a vehicle is proposed, comprising the transmission system as mentioned above. The vehicle may be an electrified vehicle, for example, a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a range extended EV, or a fuel cell electric vehicle (FCEV). The vehicle may also be a hydrogen-powered vehicle. On the basis of the above, the vehicle may realize the functions of the electrically excited synchronous motor 1 as mentioned above, and has the advantages as mentioned above.

[0063] In the present disclosure, unless otherwise defined, the technical or scientific terms used herein shall have the common meanings understood by those skilled in the art. The words “first”, “second”, and the like used in the description and claims of the patent application disclosed herein do not indicate any order, quantity or importance, being merely used to distinguish different component parts. Likewise, words such as “a” or “one” do not necessarily represent a quantity limit. The words “comprise”, “include” and the like mean that an element or object appearing before the word encompasses elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as “connect” or “link” are not restricted to a physical or mechanical connection, and may include an electrical connection, whether direct or indirect. The terms “upper”, “lower”, “left”, “right” and the like are only used to indicate a relative positional relationship, and when the absolute position of a described object changes, the relative positional relationship may also change accordingly.

[0064] Demonstrative ways of implementing the solutions provided in the present disclosure have been described in detail above with reference to preferred embodiments, but those skilled in the art will understand that as long as the concept of the present disclosure is not deviated from, various changes and modifications could be made to the specific embodiments above, and various technical features and structures set forth in the present disclosure could be combined in various ways, without exceeding the scope of protection of the present disclosure, which is specified by the attached claims.

Claims

Claims1. An electric motor stator, comprising: a stator core constructed as a hollow cylinder and arranged with multiple slots in a circumferential direction; and a stator coil comprising three first phase windings, each of which comprising multiple layer windings connected in series, and each first phase winding comprising multiple hairpin conductors connected in series, wherein the hairpin conductor respectively has a first conductor leg and a second conductor leg, and a non-welding end connected in between, the first conductor leg and the second conductor leg are respectively arranged in different slots, each slot is arranged with multiple layers of conductor legs, an end part of the first conductor leg has an incoming wire section, an end part of the second conductor leg has an outgoing wire section, and the incoming wire section and the outgoing wire section extend out of the slot, wherein the hairpin conductor comprises a short-span hairpin conductor and a long-span hairpin conductor, the first conductor leg and the second conductor leg of the short-span hairpin conductor are respectively arranged in two adjacent layers, and the first conductor leg and the second conductor leg of the long-span hairpin conductor are respectively arranged in an innermost layer and an outermost layer, wherein a welding end of the outgoing wire section of each hairpin conductor is aligned radially against a welding end of the incoming wire section of another adjacent hairpin conductor in the same first phase winding.

2. The electric motor stator according to Claim 1 , wherein a pitch of the shortspan hairpin conductor is a uniform pitch, and a pitch of the long-span hairpin conductor is a short pitch or a long pitch.

3. The electric motor stator according to Claim 1 , wherein the number of slots per pole per phase of the electric motor stator is 3.

4. The electric motor stator according to Claim 1, wherein the number of layers of the conductor leg is 2(N+2), wherein N is a positive integer.

5. The electric motor stator according to Claim 1 , wherein the number of layers of the conductor leg is 6; each first phase winding comprises a first layer winding, a second layer winding and a third layer winding, the first layer winding is arranged in a first layer and a second layer, the second layer winding is arranged in a third layer and a fourth layer, and the third layer winding is arranged in a fifth layer and a sixth layer; the short-span hairpin conductor is arranged in the first layer winding, the second layer winding and the third layer winding, and the short-span hairpin conductor is slanted in a clockwise direction; the long-span hairpin conductor is arranged between the first layer winding and the third layer winding, and the long-span hairpin conductor is slanted in the clockwise direction; the short-span hairpin conductor is arranged between the first layer winding and the second layer winding, and the short-span hairpin conductor is slanted in an anticlockwise direction, and the short-span hairpin conductor is arranged between the second layer winding and the third layer winding, and the short-span hairpin conductor is slanted in an anticlockwise direction.

6. The electric motor stator according to Claim 5, wherein the number of slots of the electric motor stator is 54, a pole pitch is 9, and the number of slots per pole per phase is 3; each pole-phase group in the first layer winding, the second layer winding and the third layer winding comprises first, second and third short-span hairpin conductors, and the three short-span hairpin conductors have a pitch of 9 and are slanted in the clockwise direction; each pole-phase group between the first layer winding and the second layer winding comprises first, second and third short-span hairpin conductors, and the three short-span hairpin conductors have a pitch of 9 and are slanted in theanticlockwise direction, wherein the first short-span hairpin conductors are connected in series to form a first series circuit, the second short-span hairpin conductors are connected in series to form a second series circuit, and the third short-span hairpin conductors are connected in series to form a third series circuit; a pole-phase group between the first layer winding and the third layer winding comprises first, second and third long-span hairpin conductors, and the three long- span hairpin conductors are slanted in the clockwise direction, and the first long- span hairpin conductor has a pitch of 11 and connects the first series circuit and the third series circuit, the second long-span hairpin conductor has a pitch of 8 and connects the second series circuit and the first series circuit, and the third long- span hairpin conductor has a pitch of 8 and connects the third series circuit and the second series circuit.

7. The electric motor stator according to Claim 1 or 5, wherein the stator coil further comprises three second phase windings, the second phase winding and the first phase winding have the same structure, the arrangement of the hairpin conductors in the second phase winding has an offset pole pitch relative to the arrangement of the hairpin conductors in the first phase winding, and the first phase winding and the second phase winding are connected in parallel.

8. The electric motor stator according to Claim 1, wherein each first phase winding has a winding incoming wire end and a winding outgoing wire end, and the winding incoming wire end is connected to a first conductor leg of the outermost layer, and the winding outgoing wire end is connected to another second conductor leg of the outermost layer.

9. An electric motor, comprising the electric motor stator according to any one of Claims 1 to 8.

10. A transmission system, comprising the electric motor according to Claim11. A vehicle, comprising the transmission system according to Claim 10.

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