A motor structure

Abstract

This invention relates to the field of motor design and manufacturing technology, and provides a motor structure that solves the problems of poor heat dissipation and easy local overheating in the end windings. The motor structure includes a stator core and windings. The windings include a winding slot portion assembled within a stator core slot and a winding end portion extending beyond the end face of the stator core. The cross-sectional width W of the winding end portion is... end The cross-sectional width W of the portion inside the winding slot is greater than the width of the winding slot. slot And W end >W end,min W end,min This refers to the minimum cross-sectional width of the end winding, determined based on the target temperature difference constraint between the end winding and the slot winding. This invention achieves axial temperature uniformity of the winding without adding a cooling system, eliminating localized hot spots and improving power density and insulation life.

Description

Technical Field

[0001] This invention relates to the field of motor design and manufacturing technology, and specifically to a motor structure. Background Technology

[0002] With the rapid development of new energy vehicles, high-dynamic industrial servo systems and integrated robot joints, motors are evolving towards higher power density, and the overheating problem caused by high integration and high current density is becoming increasingly prominent.

[0003] In actual operation, the windings inside the stator slots are in direct contact with the stator core with high thermal conductivity through an extremely thin insulation layer. The heat dissipation path is short, the thermal resistance is small, and the heat dissipation conditions are relatively good. However, the end windings extend outside the stator core and are usually surrounded by media with low thermal conductivity, such as air, cooling oil, or epoxy resin. Their heat dissipation thermal resistance is much greater than that of the part inside the winding slots.

[0004] In traditional motor design, the structure of the winding slot portion is consistent with that of the winding end portion, resulting in comparable heat generation power at the end and within the slot. However, when the heat dissipation conditions at the end are significantly worse than in the slot, this design inevitably leads to severe localized heat concentration in the end region. This localized high temperature not only accelerates the aging of the winding insulation layer and causes faults such as inter-turn short circuits, but also becomes a bottleneck limiting the overall temperature rise margin of the motor, greatly restricting its power density and operational reliability.

[0005] It is evident that existing motor structures are insufficient to effectively address the problem of heat concentration at the ends, and the industry urgently needs a targeted motor structure to overcome the aforementioned engineering bottlenecks. Summary of the Invention

[0006] To address the problem of localized heat concentration in existing motors due to poor end-heat dissipation conditions, this invention provides a motor structure that utilizes a three-node thermal resistance network model to accurately derive the optimal width of the end windings, achieving uniform global temperature distribution without increasing the burden on the external cooling system.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: This invention provides a motor structure, including a stator core and a winding, wherein the winding comprises a winding slot portion assembled in a stator core slot and a winding end portion extending out of the stator core end face, characterized in that: The cross-sectional width W of the winding end portion end The cross-sectional width W of the portion inside the winding slot is greater than the width of the winding slot. slot And W end >W end,min W end,min The minimum end winding cross-sectional width is determined based on the target temperature difference constraint between the end winding and the slot winding.

[0008] In a preferred embodiment, the W end,min Determined in the following ways: With casing temperature T c To standardize heat dissipation, a temperature node T at the center of the end winding is constructed. e Slot winding center temperature node T s and casing temperature node T c A three-node thermal resistance network model; Calculate the equivalent thermal resistance R from the end to the housing respectively. ec The equivalent thermal resistance R from the tank to the housing sc And the axial thermal resistance R from the end to the groove ax ; The end heating power Q is obtained according to the loss calculation formula. e and the heat generation power Q in the tank s Based on the R ec R sc and R ax Establish a set of three-node steady-state thermal equilibrium equations; Preset the center temperature node T of the end winding e Temperature T of the center node of the winding in the slot s The target temperature difference threshold ΔT between the two is solved to satisfy the temperature difference constraint T. e -T s Minimum end winding cross-sectional width W ≤ ΔT end,min .

[0009] In a preferred embodiment, the equivalent thermal resistance R from the end to the housing ec satisfy: , Where h e λ is the local convective heat transfer coefficient at the end. m L is the equivalent thermal conductivity of the end cooling medium. end N is the half-turn length of the end winding. s r is the number of stator slots. so r is the outer radius of the stator. sy The radius of the stator slot bottom is denoted as .

[0010] In a preferred embodiment, the equivalent thermal resistance R from the groove to the housing sc It consists of two parallel heat transfer paths, satisfying: ; Where R sc1 The heat from the windings within the corresponding slots is transferred to the stator yoke via the stator teeth and then conducted to the heat conduction path of the housing, R sc2The heat from the windings in the corresponding slots is transferred to the stator yoke via the bottom of the stator slots and then conducted to the heat conduction path of the housing.

[0011] In a preferred embodiment, the axial thermal resistance R from the end to the groove ax It consists of two parallel heat transfer paths, satisfying:

[0012] Where R ax1 R is the thermal resistance of the axial heat transfer path between the end winding and the slot winding, through which heat is transferred via the conductor material. ax2 The thermal resistance is the axial heat transfer path through which heat from the end winding is transferred to the slot region via the stator teeth.

[0013] In a preferred embodiment, the end heating power Q e and the heat generation power Q in the tank s They respectively satisfy: , , Where I is the effective value of the winding current, ρ Cu L is the resistivity of the winding material. slot d is the half-turn length of the winding in the slot, N is the number of turns of the winding, and d is the overall thickness of the winding.

[0014] In a preferred embodiment, the winding end portion and the winding slot portion are made of a continuous conductive material, and because W end >W slot When current passes through, the current density at the end portion of the winding is lower than the current density in the slot portion of the winding.

[0015] In a preferred embodiment, the three-node steady-state thermal equilibrium equations are:

[0016] .

[0017] The motor windings are made by stacking and connecting several layers of annular conductor laminations in sequence, and the annular conductors are made by lamination or laser cutting.

[0018] The beneficial effects of this invention are as follows: This invention solves the problem of localized overheating at the end windings, achieving axial temperature uniformity in the windings. In traditional motor designs, the end windings extend beyond the stator core, resulting in poor heat dissipation and often becoming localized heat concentration areas, thus limiting power density improvements. This invention constructs a thermal resistance network model that includes only the temperatures of three nodes: the end windings, the slot windings, and the casing windings. It introduces a target temperature difference constraint ΔT between the end windings and the slot windings, and actively increases the width W of the end cross-section. end Make it larger than the width W inside the groove.slot This reduces the end current density and decreases the end heat generation power. Ultimately, it ensures that the temperature difference between the end and the center of the winding in the slot meets the T... e -T s <ΔT, which achieves a more balanced axial temperature distribution in the winding and eliminates the bottleneck of local overheating at the ends.

[0019] This invention effectively improves the power density of the motor. Through the precise structural design described above, this invention solves the problem of significantly limited motor output power caused by high end winding temperatures, resulting in a substantial increase in the overall temperature rise margin of the motor. Without altering the overall outer diameter of the motor or the external cooling system, it significantly improves the motor's power density and operational reliability. Simultaneously, the reduction and equalization of the end winding temperature significantly slows down the thermal aging process of the insulation material, extends the service life of the motor's insulation system, and further enhances the long-term operational reliability of the motor.

[0020] This invention differs from conventional constant-width winding designs. Unlike traditional windings with a globally uniform cross-section geometry, this invention introduces a multi-node thermal resistance network model from heat transfer mechanics into winding size design. From the dual perspectives of heat transfer analysis and precise loss allocation, it provides accurate mathematical and physical constraints on irregular winding structures, offering a solid theoretical foundation for their design. This innovation departs from the long-standing industry practice of "equal width within the slot and at the end," opening a new technical path for the thermal design of high-power-density motors.

[0021] The motor winding design method of this invention is simple and extremely low-cost, requiring no additional cooling system. Compared to structural solutions that require complex internal cooling channels, guide plates, or multiple types of stator laminations, this invention does not rely on any additional cooling components or complex manufacturing processes. It significantly improves end temperature rise simply by changing the geometry of the winding ends (widening the end cross-section). Furthermore, compared to complex simulation methods that require establishing a refined three-dimensional thermal network model and solving numerous thermal resistance and thermal capacity matrices, this invention only requires three temperature nodes and one temperature difference constraint to complete the design, greatly reducing the design threshold and computational cost, and facilitating engineering implementation and widespread application.

[0022] This invention provides explicit and quantifiable physical design criteria. Most existing thermal management methods offer temperature prediction tools, but designers still need to rely on experience or extensive simulation iterations to determine structural dimensions. This invention, through analytical derivation, transforms the design problem into solving for the minimum end section width W that satisfies temperature difference constraints. end,min This provides a clear lower limit for the physical design. Designers only need to use the basic parameters of the motor and the preset temperature difference threshold to directly calculate the required minimum end width. The design objective is clear, quantifiable, and reproducible, significantly improving design efficiency and the reliability of the design results.

[0023] This invention possesses excellent versatility and adaptability. The design method described herein is not dependent on a specific motor type (it is applicable to permanent magnet synchronous motors, induction motors, switched reluctance motors, etc.) nor on a specific cooling method (natural cooling, air cooling, and liquid cooling are all acceptable). The three-node thermal resistance network model can flexibly adjust the thermal resistance calculation formula according to the actual motor structure, and the temperature difference threshold ΔT can be freely set according to the insulation heat resistance level and application requirements, thus exhibiting broad engineering applicability. Attached Figure Description

[0024] Figure 1 A schematic diagram illustrating the definition of winding structure dimensional parameters designed according to the design method of the present invention; Figure 2 A schematic diagram defining the cross-sectional dimensions of the stator core structure designed according to the design method of the present invention; Figure 3 A schematic diagram of the overall structure of the motor designed according to the design method of the present invention; Figure 4 The temperature rise curves of a conventional motor and a motor provided according to an embodiment of the present invention are shown respectively under rated operating conditions.

[0025] Explanation of reference numerals in the attached figures: 1-The inner part of the winding slot; 2-The end part of the winding; 3-The stator core. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] This invention addresses the technical problem of poor heat dissipation in the end windings of existing motors, which easily become localized hot spots. It proposes a motor structure that reduces the end current density and mitigates the temperature difference between the end winding and the winding within the slot by increasing the cross-sectional width of the end winding. The following is a detailed explanation... Figures 1 to 4 The implementation of this invention will be described in detail.

[0028] like Figure 1 As shown in the figure, in the motor structure described in this embodiment, the cross-sectional width W of the winding end portion is... end The cross-sectional width W of the portion inside the winding slot is greater than the width of the winding slot. slot And satisfy W end >W end,min W end,min This is the minimum end winding cross-sectional width determined based on the target temperature difference constraint between the end winding and the slot winding. W end,minThe determination is based on the motor's design input parameters, including geometric dimensions, material properties, and rated operating conditions. Specifically, this includes: winding geometric parameters, stator core geometric parameters, material properties, and rated operating parameters. The winding geometric parameters include: overall winding thickness d, and the half-turn length L within the slot. slot Length of half-turn of end winding L end Width of winding section W in slot slot Number of winding turns N, number of stator slots N s The stator core geometric parameters include: the stator outer circle radius r. so Stator slot bottom radius r sy Stator tooth width W t Insulation parameters include: winding insulation layer thickness δ ins and the equivalent thickness δ of the bottom insulation layer b Material properties include: resistivity ρ of the winding material. Cu Thermal conductivity λ of winding material Cu Thermal conductivity λ of winding insulation material ins The thermal conductivity λ of the stator core Fe The equivalent thermal conductivity λ of the end cooling medium m The end local convective heat transfer coefficient h e The rated operating parameter is the effective value of the winding current I. These parameters can be obtained directly from the motor design drawings, material data sheets, and rated operating conditions.

[0029] In this embodiment, W end,min Determined in the following ways: (1) Construct a three-node thermal resistance network model With the casing node temperature T c To standardize heat dissipation, a reference temperature T is established, which includes the center node temperature T of the end winding. e Temperature T of the center node of the winding in the slot s and casing node temperature T c A three-node thermal resistance network model. The three key thermal resistances in the model are: the equivalent thermal resistance R from the end to the housing. ec The equivalent thermal resistance R from the tank to the housing sc and the axial thermal resistance R from the end to the groove. ax They are defined as follows: The heat generated by the end windings is mainly transferred to the housing through two parallel paths: one is local convective heat transfer between the outer surface of the end windings and the cooling medium, and the other is radial heat conduction from the end windings to the housing through the cooling medium. Therefore, the equivalent thermal resistance R from the end windings to the housing is... ec Represented as: ; R ecThe first item corresponds to the local convective heat transfer path between the end outer surface and the end cooling medium; R ec The second item corresponds to the radial heat conduction path of the cooling medium between the end winding and the housing.

[0030] Equivalent thermal resistance R from the tank to the housing sc It consists of two parallel heat transfer paths. The first path involves heat from the windings within the slots being transferred to the stator yoke via the stator teeth and then conducted to the casing. The second path involves heat from the windings within the slots being transferred to the stator yoke via the bottom of the stator slots and then conducted to the casing. Therefore: ; Among them, R sc1 The heat transfer path corresponding to the winding in the slot is transferred from the stator teeth to the stator yoke and then to the housing, satisfying the following conditions: ; R sc2 The heat transfer path of the winding in the corresponding slot is transferred from the bottom of the stator slot to the stator yoke and then to the housing, satisfying the following conditions: .

[0031] Axial thermal resistance R from end to groove ax It also consists of two parallel heat transfer paths. One is an axial heat transfer path connecting the end winding and the slot winding via a conductor material; the other is an axial heat transfer path from the end winding to the slot region via the stator teeth. Therefore:

[0032] Among them, R ax1 The axial heat conduction path connecting the end winding and the slot winding via a conductor material satisfies:

[0033] R ax2 The heat from the corresponding end winding is transferred through the stator teeth to the axial heat conduction path in the slot region, satisfying the following: .

[0034] (2) Calculate the heat generation power and establish the heat balance equation. According to the loss calculation formula, the end heating power Q e and the heat generation power Q in the tank s They are respectively:

[0035]

[0036] Combined with thermal resistance R ec R sc and R axEstablish the three-node steady-state thermal equilibrium equations:

[0037] .

[0038] (3) Solve for the minimum end width that satisfies the temperature difference constraint. Preset end center node temperature T e Temperature T of the center node of the winding in the slot s The target temperature difference threshold ΔT between the two values ​​must satisfy the temperature difference constraint T. e -T s ≤ΔT. Combining the above heat balance equations with this temperature difference constraint, since T is within a reasonable range... e -T s With W end The rate increases and then monotonically decreases, taking the critical condition T. e -T s =ΔT, substitute into the system of equations and eliminate T e , T s You can get information about W end The nonlinear equation is obtained by solving the equation using numerical iterative methods (such as the bisection method or Newton's method). The solution obtained is the minimum end winding cross-sectional width W. end,min .

[0039] In the motor structure of this invention, the winding is made by sequentially stacking and connecting several layers of annular conductor laminations of different sizes, wherein the portion located within the stator core slots maintains a certain width. W slot The winding end portion extending beyond the core end face expands to a width of W end The ends and the portion inside the winding slot are integrally formed or welded from a continuous conductive material (such as copper or aluminum) to ensure electrical conductivity. Because... W end > W slot Under the same current, the current density at the end is lower than the current density inside the tank, thus the heating power at the end is lower. Q e Compared to a uniform cross-section design, the thermal resistance is significantly reduced; at the same time, the increased cross-section improves internal heat conduction at the ends and increases the heat dissipation surface area, thus reducing the thermal resistance from the ends to the housing. R ec The combined effect of these two factors effectively suppresses the temperature rise at the end, ultimately reducing the actual temperature difference. T e- T s<Δ T This achieves a more balanced axial temperature distribution in the windings, preventing localized overheating at the ends.

[0040] Figure 3 The diagram illustrates a specific motor structure according to the present invention. The motor winding is made of several layers of annular conductor laminations stacked sequentially. The winding includes a winding slot portion 1 fitted into the stator core 3 and a winding end portion 2 extending out of the end face of the stator core 3. The cross-sectional width W of the winding end portion is... end Satisfy: W end >W end,min ,and W end > W slot The winding end portion and the winding slot portion are integrally formed or welded together from a continuous conductive material (such as copper or aluminum) to ensure electrical conductivity. Because... W end > W slot Under the same current, the current density at the end is lower than that inside the tank, thus significantly reducing the heat generation power at the end compared to a uniform cross-section design. Simultaneously, the increased cross-section improves internal heat conduction at the end and increases the heat dissipation surface area, reducing the thermal resistance from the end to the casing. Both of these factors combined effectively suppress the temperature rise at the end, ultimately resulting in a lower actual temperature difference. T e- T s<Δ T This achieves a more balanced axial temperature distribution in the windings.

[0041] To further explain W end,min The process of determining the motor parameters is illustrated below with a specific set of motor parameters. In this embodiment, the required motor parameters and their values ​​are shown in the table below:

[0042] In addition, the casing temperature T c Set to 40℃, and set the target temperature difference threshold ΔT to 0.5℃.

[0043] With other parameters remaining constant, as the width W of the end winding cross-section... end Increasing the end winding resistance decreases, the end heating power decreases, and the temperature difference T between the end winding and the center of the slot winding increases. e -T s The temperature difference threshold decreases, therefore the minimum end winding cross-sectional width W that satisfies the temperature difference threshold can be obtained through iterative search or monotonic solution. end,min .

[0044] Calculations show that T is satisfied. e -T s The minimum end winding cross-sectional width W under the condition ≤ΔT end,min =5.558mm. At this time, the center temperature T of the end winding is... eThe temperature is 49.382℃, and the center temperature T of the winding inside the slot is... s The temperature is 48.882℃, which meets the requirements of T. e -T s =ΔT=0.5℃. Therefore, when the actual designed end winding cross-sectional width W end Satisfy W end When the diameter is ≥5.558mm, it can be ensured that the temperature difference between the motor end winding and the slot winding under rated operating conditions does not exceed 0.5℃.

[0045] Under the parameters of this embodiment, the width W of the end winding cross-section end Designed to be no less than W end,min =5.558mm. By increasing the width of the end winding cross-section, the end heating power can be effectively reduced and the temperature difference between the end and the winding in the slot can be reduced, thereby meeting the predetermined temperature difference constraint conditions.

[0046] Reference Figure 4 In order to verify the technical effect of the motor structure of the present invention, Figure 4 The temperature rise curves of a conventional motor and the motor in this embodiment are shown in comparison under the same rated operating conditions.

[0047] like Figure 4 As shown in (a), after a conventional motor reaches steady state under rated operating conditions, the temperature of its end windings rises sharply due to poor end heat dissipation conditions, forming significant high-temperature hot spots that are much higher than the temperature of the windings in the slots. This becomes a bottleneck that limits the overall temperature rise margin and power density of the motor.

[0048] like Figure 4 As shown in (b), with the motor structure of the present invention, under the same operating conditions, the temperature rise trend of the end winding is significantly suppressed due to the reduced heating power of the end winding. Under steady state, the temperature difference between the end winding and the slot winding is extremely small, meeting the preset temperature difference threshold requirement, and the global temperature distribution exhibits high consistency, eliminating the phenomenon of local high temperature.

[0049] In summary, the advantages of this invention lie in its full consideration of the three-dimensional multi-path heat transfer coupling characteristics of motors under harsh heat dissipation environments. By utilizing a rigorous three-node steady-state thermal resistance network model, it achieves precise physical constraints on the winding end dimensions and specific optimization of winding heat distribution without increasing the burden on the additional cooling system. This motor structure, which eliminates end heat concentration, is extremely beneficial for overcoming the bottleneck of continuous power density in motor operation and extending the service life of the insulation system. Unlike traditional equal-width winding designs, it has significant value for engineering application.

[0050] Compared with the prior art, the present invention has the following beneficial effects: This invention solves the problem of localized overheating at the motor ends, achieving axial temperature uniformity in the windings. In traditional motor structures, the end windings extend beyond the stator core, resulting in poor heat dissipation and often becoming localized heat concentration areas, thus limiting power density improvements. This invention constructs a thermal resistance network model that includes only the temperatures of three nodes: the end windings, the slot windings, and the casing windings. It introduces a target temperature difference constraint ΔT between the end windings and the slot windings, and actively increases the width W of the end cross-section. end Make it larger than the width W inside the groove. slot This reduces the end current density and decreases the end heat generation power. Ultimately, it ensures that the temperature difference between the end and the center of the winding in the slot meets the T... e -T s <ΔT, which achieves a more balanced axial temperature distribution in the winding and eliminates the bottleneck of local overheating at the ends.

[0051] This invention effectively improves the power density of the motor. Through the precise structural design described above, this invention solves the problem of significantly limited motor output power caused by high end winding temperatures, resulting in a substantial increase in the overall temperature rise margin of the motor. Without altering the overall outer diameter of the motor or the external cooling system, it significantly improves the motor's power density and operational reliability. Simultaneously, the reduction and equalization of the end winding temperature significantly slows down the thermal aging process of the insulation material, extends the service life of the motor's insulation system, and further enhances the long-term operational reliability of the motor.

[0052] This invention differs from conventional equal-width designs. Unlike traditional windings with a globally uniform cross-section geometry, this invention introduces a multi-node thermal resistance network model from heat transfer mechanics into winding size design. From the dual perspectives of heat transfer analysis and precise loss allocation, it provides accurate mathematical and physical constraints on irregular winding structures, offering a solid theoretical foundation for their design. This innovation departs from the long-standing industry practice of "equal width within the slot and at the end," opening a new technical path for the thermal design of high-power-density motors.

[0053] The motor structure design method of this invention is simple and extremely low-cost, requiring no additional cooling system. Compared with structural solutions that require complex internal cooling channels, guide plates, or multiple types of stator laminations, this invention does not rely on any additional cooling components or complex manufacturing processes. It can significantly improve the end temperature rise simply by changing the geometry of the winding ends (widening the end cross-section). Furthermore, compared with complex simulation methods that require establishing a refined three-dimensional thermal network model and solving a large number of thermal resistance and thermal capacity matrices, this invention only requires three temperature nodes and one temperature difference constraint to complete the design, greatly reducing the design threshold and computational cost, and facilitating engineering implementation and widespread application.

[0054] This invention provides explicit and quantifiable physical design criteria. Most existing thermal management methods offer temperature prediction tools, but designers still need to rely on experience or extensive simulation iterations to determine structural dimensions. This invention, through analytical derivation, transforms the design problem into solving for the minimum end section width W that satisfies temperature difference constraints. end,min This provides a clear lower limit for the physical design. Designers only need to use the basic parameters of the motor and the preset temperature difference threshold to directly calculate the required minimum end width. The design objective is clear, quantifiable, and reproducible, significantly improving design efficiency and the reliability of the design results.

[0055] This invention possesses excellent versatility and adaptability. The motor structure of this invention is not dependent on a specific motor type (it can be applied to permanent magnet synchronous motors, induction motors, switched reluctance motors, etc.) nor on a specific cooling method (natural cooling, air cooling, and liquid cooling are all acceptable). The three-node thermal resistance network model can flexibly adjust the thermal resistance calculation formula according to the actual motor structure, and the temperature difference threshold ΔT can be freely set according to the insulation heat resistance level and application requirements, thus exhibiting broad engineering applicability.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made to the above embodiments within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A motor structure comprising a stator core and windings, the windings comprising a winding slot portion fitted into a stator core slot and a winding end portion extending out of the stator core end face, characterized in that: The cross-sectional width W of the winding end portion end The cross-sectional width W of the portion inside the winding slot is greater than the width of the winding slot. slot And W end >W end,min W end,min The minimum end winding cross-sectional width is determined based on the target temperature difference constraint between the end winding and the slot winding.

2. The motor structure according to claim 1, characterized in that, The W end,min Determined in the following ways: With casing temperature T c To standardize heat dissipation, a temperature node T at the center of the end winding is constructed. e Slot winding center temperature node T s and casing temperature node T c A three-node thermal resistance network model; Calculate the equivalent thermal resistance R from the end to the housing respectively. ec The equivalent thermal resistance R from the tank to the housing sc And the axial thermal resistance R from the end to the groove ax ; The end heating power Q is obtained according to the loss calculation formula. e and the heat generation power Q in the tank s Based on the R ec R sc and R ax Establish a set of three-node steady-state thermal equilibrium equations; Preset the center temperature node T of the end winding e Temperature T of the center node of the winding in the slot s The target temperature difference threshold ΔT between the two is solved to satisfy the temperature difference constraint T. e -T s Minimum end winding cross-sectional width W ≤ ΔT end,min .

3. The motor structure according to claim 2, characterized in that, The equivalent thermal resistance R from the end to the housing ec satisfy: ， Where h e λ is the local convective heat transfer coefficient at the end. m L is the equivalent thermal conductivity of the end cooling medium. end N is the half-turn length of the end winding. s r is the number of stator slots. so r is the outer radius of the stator. sy The radius of the stator slot bottom is denoted as .

4. The motor structure according to claim 2, characterized in that, The equivalent thermal resistance R from the slot to the housing sc It consists of two parallel heat transfer paths, satisfying: ； Where R sc1 The heat from the windings within the corresponding slots is transferred to the stator yoke via the stator teeth and then conducted to the heat conduction path of the housing, R sc2 The heat from the windings in the corresponding slots is transferred to the stator yoke via the bottom of the stator slots and then conducted to the heat conduction path of the housing.

5. The motor structure according to claim 2, characterized in that, The axial thermal resistance R from the end to the groove ax It consists of two parallel heat transfer paths, satisfying: Where R ax1 R is the thermal resistance of the axial heat transfer path between the end winding and the slot winding, through which heat is transferred via the conductor material. ax2 The thermal resistance is the axial heat transfer path through which heat from the end winding is transferred to the slot region via the stator teeth.

6. The motor structure according to claim 2, characterized in that, The end heating power Q e and the heat generation power Q in the tank s They respectively satisfy: ， ， Where I is the effective value of the winding current, ρ Cu L is the resistivity of the winding material. slot d is the half-turn length of the winding in the slot, N is the number of turns of the winding, and d is the overall thickness of the winding.

7. The motor structure according to claim 1, characterized in that, The end portion of the winding and the inner portion of the winding slot are made of a continuous conductive material, and because W end >W slot When current passes through, the current density at the end portion of the winding is lower than the current density in the slot portion of the winding.

8. The motor structure according to claim 2, characterized in that, The three-node steady-state thermal equilibrium equations are as follows: 。 9. The motor structure according to claim 1, characterized in that, The motor windings are made by stacking and connecting several layers of annular conductor laminations in sequence, and the annular conductors are made by lamination or laser cutting.

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