Electric motor stator and electric motor

Abstract

An electric motor stator, comprising a stator core (1), a stator winding (2) and connecting portions (3). The stator core (1) is provided with a plurality of slots (1c) distributed at intervals in the circumferential direction (C) thereof. The stator winding (2) is mounted on the stator core (1), conductors of the stator winding (2) being inserted into each slot (1c). The slots (1c) comprise first slots and second slots. In the first slots, the connecting portions (3) are formed by means of performing varnish impregnation and then curing, and the parts of the stator winding (2) located in the first slots and the stator core (1) are thus mutually fixed by means of the connecting portions (3). In the second slots, a cooling flow path in communication with two axial sides of the stator core (1) is formed, enabling a cooling fluid in the cooling flow path to cool the winding parts in the second slots. In this way, the requirements for both the structural stability and heat dissipation of the electric motor stator are met. Further provided is an electric motor comprising the electric motor stator. The electric motor has a stable structure and can continuously operate in a peak current density state.

Description

Motor stator and motor Technical Field

[0001] The present application relates to the field of motors, and in particular to a motor stator and a motor comprising the motor stator. Background Art

[0002] In pure electric vehicles or hybrid electric vehicles, an electric motor is usually used as a power source to drive the vehicle. The electric motor usually includes a motor stator and a motor rotor that can rotate relative to the stator. The motor stator includes a stator core and a stator winding assembled together. The peak current density of the motor that serves as the power source of the vehicle is greater than the peak current density of a traditional motor. Therefore, the heat generated by the stator winding is very large, and the motor cannot continue to operate at the peak current density state by indirectly cooling the stator winding. Therefore, those skilled in the art have proposed a cooling method for directly cooling the stator winding in the slots of the stator core to improve the cooling effect. In this cooling method, the cooling fluid flows directly through the slots of the stator core to directly cool the portion of the stator winding located in the slots.

[0003] For example, in US patent application publication number US 20220216743 A1, titled "In-slot Cooling Enhancement Structure for Coated Stators," features protruding into the slot are formed on the slot sidewalls to define a flow path for cooling fluid. In utility model patent publication number CN 209448600 U, titled "In-slot Oil Cooling Structure for Flat Wire Motors," a bayonet structure formed on the slot sidewalls creates gaps between the conductors (flat wires) within the slot, serving as cooling paths for the cooling fluid.

[0004] However, in the prior art represented by the above-mentioned solution, although the stator winding can be directly cooled well, the slots of the stator core lack a structure to firmly fix the stator winding, which may cause the portion of the stator winding located in the slots of the stator core to move relative to the stator core, thereby causing problems such as wear of the insulation layer of the conductor.

[0005] Summary of the Invention

[0006] This application is made in light of the aforementioned problems with the prior art. One object of this application is to provide a motor stator that can balance the fixation between the stator winding and the stator core with direct cooling of the stator winding, thereby having a stable stator structure and ensuring a sufficient heat dissipation effect. Another object of this application is to provide a motor including the aforementioned motor stator, having a stable structure and capable of continuous operation at peak current density.

[0007] In order to achieve the above objectives, the present application may adopt the following technical solutions.

[0008] The present application provides a motor stator, comprising a stator core, a stator winding, and a connecting portion. The stator core is formed with a plurality of slots spaced apart in a circumferential direction thereof. The stator winding is mounted on the stator core. A conductor of the stator winding is inserted into each of the slots. The slots include a first slot and a second slot.

[0009] In the first slot, a paint dipping operation is performed and then cured to form the connection portion, so that the portion of the stator winding located in the first slot and the stator core are fixed to each other via the connection portion, and

[0010] A cooling flow path communicating with both axial sides of the stator core is formed in the second slot, so that a cooling fluid flowing through the cooling flow path can cool the winding portion in the second slot.

[0011] In an optional solution, the stator winding includes a plurality of card issuing units, each of which includes a first arm and a second arm, and the first arm and the second arm of the same card issuing unit are located in different slots.

[0012] For at least a portion of the card issuing units, one of the first arm portion and the second arm portion is located in the first slot and the other of the first arm portion and the second arm portion is located in the second slot.

[0013] In another optional solution, for each of the card issuing units, one of the first arm portion and the second arm portion is located in the first slot and the other of the first arm portion and the second arm portion is located in the second slot.

[0014] In another optional solution, the number of the slots spanned by the first arm portion and the second arm portion of the card issuing unit is defined as a pitch, and all the card issuing units have the same pitch.

[0015] In another optional scheme, the card-isolating unit further includes a crown side end, a first torsion side end and a second torsion side end, one end of the first arm portion and one end of the second arm portion are connected to the crown side end, the first torsion side end is connected to the other end of the first arm portion and is connected to other card-isolating units, and the second torsion side end is connected to the other end of the second arm portion and is connected to other card-isolating units.

[0016] In another optional scheme, the stator winding includes protruding parts extending from both axial sides of the stator core, and the motor stator also includes annular cavities located on both sides of the stator core, the protruding parts are located in the corresponding annular cavities, and the cooling fluid from one of the annular cavities flows into the other annular cavity through the cooling flow path.

[0017] In another optional scheme, the motor stator also includes a fluid inlet connected to one of the annular cavities and a fluid outlet connected to the other annular cavity. When the motor stator is parallel to the horizontal plane with the axial direction, the fluid inlet is located at the bottom of the motor stator and the fluid outlet is located at the top of the motor stator.

[0018] In another optional solution, the first arm portion and the second arm portion extend linearly along the axial direction, and the first arm portion and the second arm portion are arranged in layers in the groove.

[0019] In another optional solution, each phase winding of the stator winding includes a plurality of sub-windings connected in parallel or in series.

[0020] The present application also provides the following motor, comprising the motor stator described in any one of the above technical solutions.

[0021] By adopting the above technical solution, the present application provides a motor stator and a motor including the motor stator. In the motor stator, a stator core and a stator winding are assembled together. The stator core is formed with a plurality of slots, and the conductors of the stator winding are inserted into the slots, and these slots include a first slot and a second slot. In the first slot, a connection portion is provided which is formed by curing after the paint dipping operation, so that the conductor of the stator winding located in the first slot and the stator core are fixed to each other via the connection portion. In the second slot, a cooling flow path is formed which is connected to both axial sides of the stator core, so that the cooling fluid flowing through the cooling flow path can cool the conductor in the second slot.

[0022] In this way, on the one hand, the additional connection portion provided in the first slot, formed by a paint-impregnation process followed by curing, can securely secure the portion of the stator winding located in the first slot to the stator core, thereby stabilizing the motor stator structure. On the other hand, the cooling flow path formed in the second slot can directly cool the stator winding, thereby meeting the heat dissipation requirements of the motor stator during operation. Furthermore, the motor structure including the above-mentioned motor stator is stable and can continuously operate at peak current density. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1A is a perspective schematic diagram showing an assembly of a stator core and a stator winding of a motor stator according to a first embodiment of the present application.

[0024] FIG. 1B is a partial perspective schematic diagram showing the assembly in FIG. 1A , showing a connecting portion (a darker black portion in the figure) in a perspective manner.

[0025] FIG. 1C is a schematic cross-sectional view showing the assembly in FIG. 1A .

[0026] FIG. 2 is a perspective schematic diagram showing a card issuing unit of the motor winding in FIG. 1A .

[0027] FIG. 3 is a perspective schematic diagram showing the stator of the motor in FIG. 1A .

[0028] FIG4 is a schematic diagram showing the circumferential expansion of the motor winding of the motor stator according to the second embodiment of the present application, in which the connection structure of part of the card issuing unit is shown.

[0029] Explanation of the reference numerals 1 stator core; 1c slot; 2 stator winding; 2p extension portion; 2u hairpin unit; 2u1 first hairpin unit; 2u2 second hairpin unit; 2u3 third hairpin unit; 21 first arm portion; 22 second arm portion; 23 crown side end portion; 24 first torsional side end portion; 25 second torsional side end portion; 3 connecting portion; 4a first ring assembly; 4p1 fluid inlet; 4b second ring assembly; 4p2 fluid outlet; A axial direction; C circumferential direction. DETAILED DESCRIPTION

[0030] The specific embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0031] In this application, unless otherwise specified, "axial," "radial," and "circumferential" refer to the axial, radial, and circumferential directions of the motor stator, respectively. "Radially outward" refers to the side radially away from the central axis of the motor, and "radially inward" refers to the side radially closer to the central axis of the motor.

[0032] The following describes the motor stator according to the first embodiment of the present application in conjunction with the accompanying drawings.

[0033] (Motor stator according to the first embodiment of the present application)

[0034] The motor stator according to the first embodiment of the present application is a hairpin-type motor stator. As shown in Figures 1A to 1C, the motor stator includes a stator core 1, a stator winding 2, and a connecting portion 3 assembled together. The stator core 1 and the stator winding 2 are firmly fixed together by the connecting portion 3.

[0035] In this embodiment, as shown in Figures 1A to 1C, the stator core 1 has a generally cylindrical shape as a whole, and the stator core 1 can be formed into a laminated body by stacking silicon steel sheets in the axial direction A. The stator core 1 includes a yoke and a plurality of teeth. The yoke extends continuously along the entire circumference C. The plurality of teeth extend radially inward from the yoke, and the plurality of teeth are spaced apart in the circumferential direction C, so that the plurality of slots 1c are defined by the plurality of teeth and are evenly distributed and spaced apart in the circumferential direction C. The axial ends of these slots 1c are open toward the outside, the radial outer ends of the slots 1c are closed, and the radial inner ends are open.

[0036] In this embodiment, as shown in Figures 1A to 1C , the stator winding 2 is wound around the stator core 1, and the conductor of the stator winding 2 is inserted into each slot 1 c of the stator core 1. In each slot 1 c, the conductor of the stator winding 2 is arranged in a radial direction and in layers, with multiple layers, for example, six layers, being provided in each slot 1 c (see Figure 1C ).

[0037] As shown in Figures 1A and 1B, the stator winding 2 is a hairpin winding that is inserted into the stator core 1 and twisted into shape using a hairpin unit 2u (see Figure 2), and then electrically connected, for example, by welding. Each phase winding of the stator winding 2 may include multiple sub-windings connected in parallel or series, each sub-winding being composed of multiple hairpin units 2u. Specifically, as shown in Figure 2, each hairpin unit 2u is formed from a flat wire conductor and includes a first arm portion 21, a second arm portion 22, a crown-side end portion 23, a first torsional end portion 24, and a second torsional end portion 25 that are formed integrally. The first arm portion 21 and the second arm portion 22 both extend linearly along the axial direction A of the stator core 1. The first arm portion 21 and the second arm portion 22 of the same hairpin unit 2u are located in different slots 1c and at different layers within the slot 1c. For example, the first arm 21 of a hairpin unit 2u can be located in the first layer of one slot 1c and the second arm 22 can be located in the second layer of another slot 1c. The first arm 21 of another hairpin unit 2u can be located in the third layer of one slot 1c and the second arm 22 can be located in the fourth layer of another slot 1c. The first arm 21 of yet another hairpin unit 2u can be located in the fifth layer of one slot 1c and the second arm 22 can be located in the sixth layer of another slot 1c. This allows the number of crown layers at the axial end of the stator winding 2 (i.e., the protruding portion 2p extending from the stator core 1 along the axial direction A) to be half the number of layers of the flat wire in the slots 1c of the stator core 1. Furthermore, assuming that the number of slots 1c spanned by the first arm 21 and the second arm 22 of the hairpin unit 2u is a pitch, hairpin units 2u having the same or different pitches can be provided in the stator winding 2. 2 , the crown-side end portion 23 has a bent shape, and one end of the first arm portion 21 and one end of the second arm portion 22 are connected to the crown-side end portion 23. Thus, after the stator winding 2 is installed in place, the multiple crown-side end portions 23 form a crown-shaped structure at the axial end of the winding. The first torsional end portion 24 is connected to the other end of the first arm portion 21 for electrical connection to another hairpin unit 2u, for example, by welding. The second torsional end portion 25 is connected to the other end of the second arm portion 22 for electrical connection to another hairpin unit 2u, for example, by welding.

[0038] In this embodiment, as shown in Figures 1B and 1C, all slots 1c are divided into a first slot and a second slot. In the first slot, a varnishing process is performed and then cured to form a connecting portion 3, so that the portion of the stator winding 2 located in the first slot is fixed to the stator core 1 via the connecting portion 3. The varnishing process can be carried out using existing varnishing materials and methods, and the connecting portion 3 in the first slot fills the gap between the arms 21 and 22 of the hairpin unit 2u and the slot wall as much as possible. In the second slot, a concave-convex structure can be formed on the slot wall to form a cooling flow path extending along the axial direction A of the motor stator and connecting to both axial sides of the stator core 1, so that the cooling fluid flowing through the cooling flow path can cool the winding portion in the second slot. In this embodiment, for at least a portion of the hairpin units 2u, the first arm 21 of each hairpin unit 2u in this portion is located in the first slot, and the second arm 22 is located in the second slot. In this way, on the one hand, by utilizing the additional connection part 3 provided in the first slot, which is formed by curing after the paint dipping operation, the part of the stator winding 2 located in the first slot can be firmly fixed to the stator core 1, so that the motor stator structure is stable; on the other hand, by utilizing the cooling flow path formed in the second slot, the stator winding 2 can be directly cooled, thereby meeting the heat dissipation requirements of the motor stator during operation.

[0039] As shown in Figure 3, the motor stator according to the first embodiment of the present application further includes a first ring assembly 4a and a second ring assembly 4b located on either axial side of the stator core 1. Both the first ring assembly 4a and the second ring assembly 4b are fixed to the stator core 1. The first ring assembly 4a defines a first annular cavity extending continuously along the circumferential direction C. The stator winding 2 extends axially from the stator core 1 to one side and is located within the first annular cavity. The second ring assembly 4b defines a second annular cavity extending continuously along the circumferential direction C. The stator winding 2 extends axially from the stator core 1 to the other side and is located within the second annular cavity. Furthermore, the first ring assembly 4a further defines a fluid inlet 4p1 communicating with the first annular cavity, through which external cooling fluid can enter the first annular cavity. The second ring assembly 4b further defines a fluid outlet 4p2 communicating with the second annular cavity, through which cooling fluid within the second annular cavity can exit. In this way, the cooling fluid that enters the first annular cavity through the fluid inlet 4p1 first cools the protruding portion 2p of the stator winding 2 on one axial side, and then flows along the cooling flow path formed in the second slot of the stator core 1. In this process, the portion of the stator winding 2 located in the second slot is cooled, and then flows into the second annular cavity to cool the protruding portion 2p of the stator winding 2 on the other axial side. Finally, the cooling fluid flows out through the fluid outlet 4p2 and returns to the fluid inlet 4p1 after circulating through the external circulation loop. In this way, the cooling effect on the motor stator can be further improved. In addition, as shown in Figure 3, in order to further improve the above-mentioned cooling effect, when the motor stator is parallel to the horizontal plane with the axial direction A, the fluid inlet 4p1 is located at the bottom of the motor stator and the fluid outlet 4p2 is located at the top of the motor stator, which is conducive to the cooling fluid being able to spread throughout the first annular cavity and the second annular cavity.

[0040] The motor stator according to the second embodiment of the present application will be described below with reference to the accompanying drawings.

[0041] (Motor stator according to the second embodiment of the present application)

[0042] The motor stator according to the second embodiment of the present application has substantially the same structure as the motor stator according to the first embodiment of the present application, and the differences therebetween are mainly described below.

[0043] In this embodiment, the stator core 1 of the motor stator has 48 slots 1c. Figure 4 shows a schematic diagram of the slots 1c deployed along the circumferential direction C. The solid line extending vertically in the figure represents the first slot, and the dashed line represents the second slot. The numbers on the solid and dashed lines represent the slot 1c numbers. The number of slots 1c spanned by the first arm 21 and the second arm 22 of the motor winding's hairpin unit 2u is defined as the pitch. In this embodiment, hairpin units 2u with identical pitches can be provided in the motor winding. As shown in Figure 4, this pitch is 6. The first arm 21 of the first hairpin unit 2u1 is located in slot 1 (the first slot) and the second arm is located in slot 7 (the second slot). The first arm 21 of the second hairpin unit 2u2 is located in slot 7 (the second slot) and the second arm 22 is located in slot 13 (the first slot). The first arm 21 of the third hairpin unit 2u3 is located in slot 13 (the first slot) and the second arm 22 is located in slot 19 (the second slot). By analogy, for each hairpin unit 2u of the stator winding 2, one arm is located in the first slot and the other arm is located in the second slot.

[0044] It should be understood that the above embodiments are merely illustrative and are not intended to limit the present application. Those skilled in the art may, based on the teachings of this application, make various modifications and alterations to the above embodiments without departing from the scope of this application. Further, the following supplementary explanations are provided.

[0045] i. The present application also provides a motor comprising the motor stator according to the present application. The stator core 1 and stator winding 2 of the motor stator are securely fixed to each other, and the stator winding 2 can be effectively cooled. Thus, the motor comprising the motor stator has a stable structure and can continuously operate at peak current density (maximum continuous power).

[0046] ii. During simulation experiments of an example motor stator of the present application, a required maximum continuous power (e.g., 90 kW) was set. The actual continuous operating power of the motor stator of the present application under continuous cooling conditions was significantly greater than the maximum continuous power. Even when the actual continuous operating power of the motor stator (e.g., 190 kW) was significantly greater than the required maximum continuous power, the computer fluid dynamics simulation results showed that the temperature of the motor stator remained below the maximum allowable temperature, demonstrating that the cooling effect of the motor stator of the present application was sufficient.

[0047] iii. In a modification of the above embodiment, not all slots 1 c in the stator core 1 are divided into first slots and second slots, and only part of the slots 1 c may be divided into first slots and second slots.

[0048] iv. It is understood that the connection portion 3 formed by the paint impregnation process followed by curing effectively secures the stator winding 2, eliminating the need for additional design and processing for securing the stator winding 2, thereby reducing associated costs. Furthermore, compared to conventional solutions that cool the protruding portion of the stator winding or the surface of the stator core, the motor stator of this application offers enhanced cooling. Furthermore, compared to conventional solutions that secure the stator winding 2 through the stator core's fixing features and the mutual support between the stator winding conductors, the motor stator of this application offers enhanced securing of the stator winding 2.

[0049] v. The present application does not limit the method of forming the cooling flow path in the second groove. Various other appropriate methods, including but not limited to various methods disclosed in the prior art, can be used to form the cooling flow path in the second groove.

[0050] vi. This application does not limit the method for causing the cooling fluid to flow through the second slots and for cooling the extension 2p. Various other appropriate methods, including but not limited to those disclosed in the prior art, may be used to cause the cooling fluid to flow through the second slots and cool the extension 2p. For example, the cooling fluid may flow into the motor stator from one axial side and out from the other axial side, or the cooling fluid may flow into the middle of the motor stator and out from both axial ends.

[0051] Here, the above-mentioned annular cavity for accommodating the protruding portion 2p can be formed in various ways.

[0052] vii. The present application does not limit the form of the conductors constituting the stator winding. For example, the stator winding may be composed of a flat wire conductor, or a flat wire conductor and a round conductor.

Claims

1. A motor stator, comprising a stator core (1), a stator winding (2), and a connecting portion (3), wherein the stator core (1) is formed with a plurality of slots (1c) spaced apart and distributed in a circumferential direction (C) thereof, the stator winding (2) being mounted on the stator core (1), a conductor of the stator winding (2) being inserted into each of the slots (1c), and the slots (1c) comprising a first slot and a second slot. In the first slot, a paint dipping operation is performed and then cured to form the connecting portion (3), so that the portion of the stator winding (2) located in the first slot and the stator core (1) are fixed to each other via the connecting portion (3), and A cooling flow path is formed in the second slot and communicates with both axial sides of the stator core (1), so that the cooling fluid flowing through the cooling flow path can cool the winding part in the second slot.

2. The motor stator according to claim 1, characterized in that: The stator winding (2) includes a plurality of card-isolating units (2u), each of the card-isolating units (2u) including a first arm portion (21) and a second arm portion (22), the first arm portion (21) and the second arm portion (22) of the same card-isolating unit (2u) being located in different slots (1c). For at least a portion of the card issuing unit (2u), one of the first arm portion (21) and the second arm portion (22) is located in the first slot and the other of the first arm portion (21) and the second arm portion (22) is located in the second slot.

3. The motor stator according to claim 2, characterized in that: For each of the card issuing units (2u), one of the first arm portion (21) and the second arm portion (22) is located in the first slot and the other of the first arm portion (21) and the second arm portion (22) is located in the second slot.

4. The motor stator according to claim 2 or 3, characterized in that The number of the slots (1c) spanned by the first arm portion (21) and the second arm portion (22) of the card issuing unit (2u) is a pitch, and the pitches of all the card issuing units (2u) are the same.

5. The motor stator according to claim 2 or 3, characterized in that: The card-hairing unit (2u) further comprises a crown side end portion (23), a first torsion side end portion (24) and a second torsion side end portion (25); one end of the first arm portion (21) and one end of the second arm portion (22) are connected to the crown side end portion (23); the first torsion side end portion (24) is connected to the other end of the first arm portion (21) and is connected to other card-hairing units (2u); and the second torsion side end portion (25) is connected to the other end of the second arm portion (22) and is connected to other card-hairing units (2u).

6. The motor stator according to any one of claims 1 to 3, characterized in that: The stator winding (2) includes protruding portions (2p) extending from both axial sides of the stator core (1), and the motor stator also includes annular cavities located on both sides of the stator core (1), the protruding portions (2p) are located in the corresponding annular cavities, and the cooling fluid from one annular cavity flows into the other annular cavity through the cooling flow path.

7. The motor stator according to claim 6, characterized in that: The motor stator further comprises a fluid inlet (4p1) communicating with one of the annular cavities and a fluid outlet (4p2) communicating with the other annular cavity. When the motor stator is parallel to a horizontal plane with the axial direction (A), the fluid inlet (4p1) is located at the bottom of the motor stator and the fluid outlet (4p2) is located at the top of the motor stator.

8. The motor stator according to any one of claims 1 to 3, characterized in that: The first arm portion (21) and the second arm portion (22) extend linearly along the axial direction (A), and the first arm portion (21) and the second arm portion (22) are arranged in layers in the groove (1c).

9. The motor stator according to any one of claims 1 to 3, characterized in that: Each phase winding of the stator winding (2) comprises a plurality of sub-windings connected in parallel or in series.

10. A motor comprising the motor stator according to any one of claims 1 to 9.

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