Asymmetric wire insulation for traction motor stator

Abstract

The present disclosure provides "Asymmetric wire insulation for traction motor stators." A stator assembly is presented. The stator assembly includes a stator core defining slots and magnetic wires positioned within the slots. Each magnetic wire includes a conductive core and an insulation layer surrounding the core. The insulation layer can have a varying thickness, with thinner portions spanning certain sides of the wire and thicker portions spanning other sides.

Description

Technical Field

[0001] This disclosure relates to stator wire configurations for use in electric vehicle motors. Background Technology

[0002] Magnetic wire is a component in electric vehicle motors that enables the generation of the magnetic field that drives the motor. The performance of an electric vehicle motor can depend on the conductivity, insulation, and durability of this wire. Adjusting these properties reduces energy loss and improves thermal management. Summary of the Invention

[0003] A stator assembly is provided. The stator assembly includes a stator core defining a plurality of slots and a plurality of magnetic wires positioned within the slots. Each magnetic wire includes a conductive core surrounded by an insulating layer, wherein portions of the insulating layer crossing certain sides of the magnetic wire are thinner than those crossing other sides. The thinner portions of the insulating layer may be adjacent to the stator core, while the thicker portions may be adjacent to other magnetic wires. The asymmetric thickness of the insulating layer allows for an increase in copper area while maintaining the overall size of the magnetic wire, thereby increasing the conductive core fill factor within the slots of the stator core. The insulating layer may be made of a polymeric material such as polyimide, polyesterimide, or polyamideimide. Additionally, the magnetic wires may have a rectangular cross-sectional shape.

[0004] A traction motor is provided. The traction motor includes a rotor, a stator, and a plurality of magnetic wires. The stator has a stator core defining slots, and the plurality of magnetic wires are arranged in the slots to form stator windings. Each magnetic wire includes a conductive core and an insulating layer with an asymmetrically distributed thickness. The insulating layer may include: a first region with increased thickness for phase-to-phase voltage insulation, capable of withstanding a root-mean-square voltage effect of 1280V; and a second region with decreased thickness for phase-to-core voltage insulation, capable of withstanding a root-mean-square voltage effect of 950V. The magnetic wires may have reduced external dimensions while maintaining the cross-sectional area of ​​the conductive core. The insulating layer may include a region with a thickness of 40 micrometers, and the magnetic wires may have a rectangular cross-sectional shape.

[0005] A method for manufacturing a stator assembly is provided. The method includes winding a plurality of wires within slots in a stator such that the insulation covering the sides of the wires facing the core of the stator is thinner than the insulation covering the sides of adjacent wires facing the core within the slots. The method may further include applying an asymmetric insulation layer to the conductive core of the wires before winding the plurality of wires within the slots of the stator. Applying the asymmetric insulation layer may include increasing the insulation thickness on the sides of the conductive core requiring phase-to-phase voltage insulation and decreasing the insulation thickness on the sides requiring phase-to-core voltage insulation. The reduced insulation thickness in the low-voltage region may be controlled to be measured between 30 micrometers and 40 micrometers. The conductive core may be extruded to have a rectangular cross-sectional shape to maximize copper filling within the slots of the stator core. The stator assembly may include an asymmetric insulation layer made of a polymeric material. The polymeric material may be polyimide, polyesterimide, or polyamideimide. Attached Figure Description

[0006] Figures 1A-1C are plan views of the cross-section of the magnetic wires used in the stator assembly;

[0007] Figure 2A This is a plan view of the stator core.

[0008] Figure 2B It is wrapped with magnetic wire. Figure 2A A plan view of the cross-section of the slot in the stator core; and

[0009] Figure 3 This is a flowchart of a method for manufacturing a stator assembly. Detailed Implementation

[0010] According to this disclosure, detailed embodiments of stator assemblies, traction motors, and related manufacturing methods are provided. These embodiments illustrate the configuration of magnetic wires with asymmetrical insulation layers and their integration into stator windings for traction motors. The included figures and descriptions are illustrative and may not depict every possible variation or configuration of the assembly or method. Certain features may be emphasized or simplified to highlight aspects of magnetic wire design, insulation layer distribution, and associated manufacturing processes. Therefore, the specific structural and operational details described are not intended to limit the scope but are intended as guidance for those skilled in the art to implement the various embodiments.

[0011] Unless otherwise expressly stated, all values ​​and ranges relating to quantities, measurements, percentages, weights, and similar numerical references in this document should be understood as being preceded by the term "about". This applies even where the term "about" is not explicitly used. The intention is that all values ​​and ranges encompass variations that may arise from standard measurement tolerances, manufacturing processes, material properties, and the intended functionality of the disclosed aspects. For example, the dimension "40 micrometers" should be interpreted as "about 40 micrometers". Similarly, when a composition is described as having "5% by weight of component", it should be understood as "about 5% by weight of component". Furthermore, when values ​​are presented as ranges such as "30 to 40 micrometers", the range should be interpreted as actually referring to "about 30 to about 40 micrometers". Such variations are implicitly incorporated within the scope of this disclosure.

[0012] This disclosure relates to an asymmetric wire insulation design for magnetic wires used in the stator of traction motors (particularly in electric vehicles). Magnetic wires are components in these motors that enable the generation of the magnetic field required for operation. The properties of the magnetic wires (including their conductivity, insulation properties, and durability) directly affect the efficiency, reliability, and power output of the motor.

[0013] Magnetic wires consist of a conductive core, such as copper or aluminum, surrounded by an insulating layer. Copper is often the preferred material for the conductive core due to its electrical conductivity, low resistive loss, and mechanical strength. These properties are sometimes necessary to minimize energy loss, reduce heat generation, and ensure structural integrity under the high-speed and high-vibration conditions typical of electric vehicle traction motors. Aluminum, while lighter, has lower conductivity and can be used in applications where weight reduction outweighs the need for higher performance.

[0014] The insulator surrounding the conductive core is used to electrically isolate the conductive core from adjacent wires and the grounded stator core. This insulator can be made of a polymer material with high dielectric strength, thermal stability, and mechanical elasticity. Suitable materials include polyimide, polyesterimide, and polyamideimide. In high-performance motors, the insulator can be a multilayer system to provide additional protection against thermal aging and mechanical effects.

[0015] One of the considerations when designing wire insulators is their ability to withstand partial discharge, which occurs when a local discharge partially crosses the insulator under high voltage. Over time, this partial discharge affects the insulator. Therefore, the insulator must meet the partial discharge initiation voltage (PDIV) requirement. These requirements may be affected by voltage effects experienced in different areas of the motor.

[0016] Traction motors experience phase-to-phase voltage effects and phase-to-core voltage effects. Phase-to-phase voltage effects occur between adjacent conductors carrying currents from different phases and typically involve the highest voltage difference. In contrast, phase-to-core voltage effects occur between a conductor and the grounded stator core and are typically lower.

[0017] In the example, the phase-to-phase terminal voltage of an 800-volt (V) traction motor can be calculated as follows:

[0018]

[0019] in:

[0020] TV = Terminal Voltage

[0021] SF PD = Factor used for partial discharge

[0022] SF 热 = Heat factor

[0023] Substitute the value:

[0024]

[0025] In the same example, the phase-to-core RMS of an 800V traction motor can be calculated as follows:

[0026]

[0027] Based on the equation, the phase-to-phase RMS voltage can reach approximately 1280V, while the phase-to-core RMS voltage is closer to 950V. These differences in voltage effects allow for insulation designs that vary the insulation thickness to suit the specific requirements of each region.

[0028] This disclosure introduces an asymmetric insulation design that applies a thicker insulator to regions with higher electrical insulation requirements (such as interphase regions) and a thinner insulator to regions with lower requirements (such as phase-to-core regions). This can be achieved through an insulation extrusion process, allowing for controlled application of insulation thickness. For example, in a magnetic wire design, the insulation thickness on all sides of the wire can be uniformly 170 micrometers. However, in the proposed asymmetric design, the thickness in low-voltage regions can be reduced to as little as 40 micrometers while maintaining the necessary electrical insulation properties.

[0029] With the PDIV target established, the following equation can be used to design the insulation system for the motor, including both the magnetic wire and slot liner thickness:

[0030]

[0031] The composite relative permittivity of the paint layer and clear coat system It can be calculated as follows:

[0032]

[0033] in:

[0034]

[0035] An additional factor of 1.33 was applied to account for the winding process and treatment. The coating thickness was designed to address two main cases: interphase PDIV and phase-to-core PDIV. To address interphase PDIV, the following equation was used:

[0036]

[0037] By replacement:

[0038]

[0039]

[0040] To solve the phase-to-core PDIV for a given channel liner thickness of 0.175 mm, we have the following equation:

[0041]

[0042] This means that the insulator used can be only 3 micrometers thick on the magnetic wire wall. Reducing the insulation thickness in the low-voltage region allows for an increase in the copper fill factor within the stator slots. By reducing the space occupied by the insulator, more copper can be packed into the slots, resulting in a 7%–10% increase in the copper cross-sectional area for a given slot size, as shown in the following equation:

[0043]

[0044] This increased copper fill directly translates to higher current carrying capacity, resulting in greater torque and power output. A 1% increase in copper fill typically corresponds to an increase of about 1% in motor torque and power output, but the exact improvement depends on the motor design and operating conditions.

[0045] The asymmetrical insulation design exhibits improved thermal performance. Thinner insulation in the low-voltage region reduces thermal resistance, thereby promoting heat dissipation from the copper conductors to the stator core and end windings. Increased thermal conductivity lowers the motor's operating temperature, thus reducing cooling requirements and improving overall efficiency. Furthermore, minimizing copper losses by increasing the copper cross-sectional area reduces winding resistance, further enhancing efficiency and extending the vehicle's driving range.

[0046] By using less insulation material, the overall manufacturing complexity of the magnetic wire is reduced. Furthermore, the improved motor efficiency and power output achieved through increased copper fill can lead to simplified system-level operation. For example, a more efficient motor may require a smaller battery or a less extensive cooling system.

[0047] From a reliability perspective, asymmetrical insulation design minimizes thermal and electrical effects on motor components, thereby reducing the likelihood of insulation problems and other performance issues.

[0048] Figures 1A-1C are cross-sectional views of magnetic wires suitable for use in stator assemblies. Figure 1A shows the baseline of a current configuration where the magnetic wire comprises a conductive core surrounded on all sides by an insulation layer of uniform thickness. This symmetrical wire cross-section maintains consistent phase-to-phase and phase-to-core voltage insulation and maintains the overall wire dimensions, which are typical in conventional designs. However, this configuration does not adjust the conductive core area or the fill factor within the stator core slots.

[0049] Figure 1B illustrates a first concept for the magnetic wire 10, which modifies the insulation layer 12 to increase the area of ​​the conductive core 14 while maintaining the overall dimensions of the magnetic wire 10. In this configuration, the thickness of the insulation layer on the sidewalls facing the stator core is reduced, thereby allowing circumferential expansion of the material in the conductive core 14. This increases the material fill factor within the stator core slots, thereby increasing the current-carrying capacity without changing the external dimensions of the magnetic wire 10. The reduced thickness of the insulation layer 12 on these sidewalls allows for improved conductivity while maintaining sufficient insulation to achieve phase-to-phase and voltage insulation.

[0050] Figure 1C illustrates a second concept for the magnetic wire 16, which reduces the overall size of the magnetic wire 16 while maintaining the cross-sectional area of ​​the conductive core 18. In this design, the insulation layer 20 is uniformly thinned on all sides, resulting in a smaller external size of the magnetic wire 16. This configuration is advantageous for applications requiring compact stator windings because it allows for improved space efficiency within the stator core slots while preserving the area of ​​the conductive core 18 to maintain the conductivity of the magnetic wire 16. The reduced thickness of the insulation layer 20 is configured to provide sufficient insulation for phase-to-phase voltage and phase-to-core voltage, with specific regions potentially having a thickness optimized for RMS voltage requirements.

[0051] Figure 2A and Figure 2B The configuration of the magnetic wires used in the traction motor and stator assembly is shown. Figure 2A A traction motor 22 with a rotor 24 and a stator 26 is shown. The stator 26 defines a plurality of slots 30 configured to receive stator windings formed by a plurality of magnetic wires 36. Figure 2BAn enlarged cross-sectional view of the windings in slot 30 is shown. Each magnetic wire 36 includes a conductive core 38 surrounded by an asymmetric insulating layer 40, wherein portions of the asymmetric insulating layer 40 are asymmetrically distributed to improve the performance of the traction motor 22.

[0052] The slot 30 is defined by the stator core wall 32 and lined with a slot liner 34 to electrically insulate the magnetic wires 36 from the stator core wall 32. Each magnetic wire 36 includes a conductive core 38 and an asymmetric insulating layer 40 surrounding the conductive core 38. The asymmetric insulating layer 40 is asymmetrically distributed, having a reduced thickness on the side adjacent to the stator core wall 32 and an increased thickness on the side adjacent to the other magnetic wires 36. This configuration allows for an increased fill factor of the conductive core 38 within the slot 30 while maintaining the overall dimensions of the magnetic wires 36 and providing sufficient insulation for phase-to-phase and phase-to-core voltage requirements.

[0053] The asymmetric insulating layer 40 includes a first region 42 with increased thickness to provide enhanced insulation for phase-to-phase voltage insulation; in this example, the first region is configured to withstand a root-mean-square voltage effect of 1280 V. A second region 44 with reduced thickness is configured for phase-to-core voltage insulation, in this example capable of withstanding a root-mean-square voltage effect of 950 V. In one embodiment, the asymmetric insulating layer 40 has a thickness of approximately 40 micrometers in the reduced region 44, thereby achieving compact and efficient use of space within the slot 30. This configuration increases the fill factor of the conductive material, thereby increasing the current-carrying capacity of the magnetic wire 36 without reducing the cross-sectional area of ​​the conductive core 38.

[0054] The asymmetric insulating layer 40 can be made of a polymeric material such as polyimide, polyesterimide, or polyamideimide, which provides high durability and electrical insulation properties. The magnetic wires 36 can have a rectangular cross-sectional shape, thereby allowing for further optimization of the slot fill factor.

[0055] Figure 3 This is a flowchart illustrating method 46 for manufacturing a stator assembly. Method 46 begins at step 48, wherein a stator core having a plurality of slots is formed. The stator core is configured to receive stator windings, wherein the slots provide designated areas for placing magnetic wires.

[0056] At step 50, a plurality of conductive cores are extruded. These conductive cores form the conductive elements of the magnetic wire and are shaped to achieve a desired cross-sectional geometry, such as a rectangular shape, to maximize the conductive core fill factor within the stator core slot.

[0057] At step 52, an asymmetric insulating layer is applied around the multiple conductive cores to form multiple magnetic wires. The insulating layer is applied with an asymmetric thickness to provide enhanced electrical insulation properties. Thicker regions of the insulating layer are configured to withstand higher phase-to-phase voltages, while thinner regions are designed for phase-to-core voltage insulation, thereby optimizing the fill factor of the magnetic wires within the stator core slots without reducing the conductive core area. This step may involve techniques such as coating or extrusion to achieve the desired insulating layer configuration.

[0058] At step 54, multiple magnetic wires are positioned in slots in the stator core to form a stator winding. The magnetic wires are aligned and secured within the slots to establish the electrical path necessary for generating electromagnetic forces in the stator assembly.

[0059] The above embodiments are specific examples that do not describe all possible forms of this disclosure. Features of the illustrated embodiments may be combined to form other embodiments of the disclosed concepts. The language used in the specification is descriptive and not restrictive. The scope of the following claims is broader than the specific disclosed embodiments and also includes modifications to the illustrated embodiments.

[0060] According to the present invention, a stator assembly is provided, the stator assembly having: a stator core defining a plurality of slots; and a plurality of magnetic wires in the slots, each of the magnetic wires having a side surface, a conductive core, and an insulating layer surrounding the conductive core, wherein a portion of the insulating layer across some of the side surfaces is thinner than a portion of the insulating layer across other side surfaces.

[0061] According to an embodiment, the portion of the insulating layer spanning some of the sides faces the stator core.

[0062] According to an embodiment, the portion of the insulating layer that crosses the other sides of the side faces the other magnetic wires in the magnetic wires.

[0063] According to an embodiment, the insulating layer is made of a polymer material.

[0064] According to the embodiments, the polymer material is polyimide, polyesterimide, or polyamideimide.

[0065] According to an embodiment, the magnetic wire has a rectangular cross-sectional shape.

[0066] According to the present invention, a traction motor is provided, the traction motor having: a rotor; a stator core surrounding the rotor and defining a plurality of slots; and a plurality of wires arranged in the slots to form stator windings, each of the wires including a conductive core and an insulating layer having a thickness asymmetrically distributed around the conductive core.

[0067] According to an embodiment, each of the lines includes a first region of the insulation layer with increased thickness for phase-to-phase voltage insulation.

[0068] According to an embodiment, each of the lines includes a second region of the insulation layer with a reduced thickness for phase-to-core voltage insulation.

[0069] According to an embodiment, the first region of the insulating layer is configured to withstand a 1280V interphase root mean square voltage effect.

[0070] According to an embodiment, the second region of the insulating layer is configured to withstand a phase-to-core root mean square voltage effect of 950V.

[0071] According to an embodiment, the insulating layer of each of the lines includes a region with a thickness of 40 micrometers.

[0072] According to an embodiment, each of the lines has a rectangular cross-sectional shape.

[0073] According to the present invention, a method of manufacturing a stator assembly includes: winding a plurality of wires in a slot of the stator such that an insulator covering the side of the wires facing the core of the stator is thinner than an insulator covering the side of an adjacent wire facing the stator in the slot of the wires.

[0074] In one aspect of the invention, the method includes applying an asymmetric insulating layer to the conductive core of the plurality of wires prior to the winding.

[0075] In one aspect of the invention, the application includes increasing the insulation thickness on the side of the conductive core that requires phase-to-phase voltage insulation and decreasing the insulation thickness on the side that requires phase-to-core voltage insulation.

[0076] In one aspect of the invention, the asymmetric insulating layer has a thickness of 30-40 micrometers on the side where phase-to-core voltage insulation is required.

[0077] In one aspect of the invention, the conductive core is extruded into a rectangular cross-sectional shape to maximize the copper filling within the slot.

[0078] In one aspect of the invention, the asymmetric insulating layer is made of a polymer material.

[0079] In one aspect of the invention, the polymer material is a polyimide, a polyesterimide, or a polyamideimide.

Claims

1. A stator assembly comprising: Stator core, the stator core defining a plurality of slots; as well as The slot contains a plurality of magnetic wires, each of which has a side surface, a conductive core, and an insulating layer surrounding the conductive core, wherein a portion of the insulating layer across some of the side surfaces is thinner than a portion of the insulating layer across other side surfaces.

2. The stator assembly of claim 1, wherein the portion of the insulating layer spanning some of the sides faces the stator core.

3. The stator assembly of claim 1, wherein the portion of the insulating layer spanning the other sides of the sides faces the other magnetic wires of the magnetic wires.

4. The stator assembly of claim 1, wherein the insulating layer is made of a polymer material.

5. The stator assembly of claim 4, wherein the polymer material is polyimide, polyesterimide, or polyamideimide.

6. The stator assembly of claim 1, wherein the magnetic wire has a rectangular cross-sectional shape.

7. A traction motor, comprising: Rotor; A stator core that surrounds the rotor and defines a plurality of slots; as well as Multiple wires are arranged in the slot to form a stator winding, each of the wires including a conductive core and an insulating layer having a thickness asymmetrically distributed around the conductive core.

8. The traction motor of claim 7, wherein each of the wires includes a first region of the insulation layer having increased thickness for phase-to-phase voltage insulation.

9. The traction motor of claim 8, wherein each of the wires includes a second region of the insulation layer having a reduced thickness for phase-to-core voltage insulation.

10. The traction motor of claim 8, wherein the first region of the insulation layer is configured to withstand a 1280V interphase root mean square voltage effect.

11. The traction motor of claim 9, wherein the second region of the insulation layer is configured to withstand a phase-to-core root mean square voltage effect of 950V.

12. The traction motor of claim 7, wherein the insulation layer of each of the wires comprises a region with a thickness of 40 micrometers.

13. The traction motor of claim 7, wherein each of the lines has a rectangular cross-sectional shape.

14. A method for manufacturing a stator assembly, comprising: Multiple wires are wound into slots in the stator such that the insulator covering the side of the wires facing the core of the stator is thinner than the insulator covering the side of the adjacent wires facing the stator within the slot.

15. The method of claim 14, further comprising applying an asymmetric insulating layer to the conductive core of the plurality of wires prior to the winding.

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