Cables, coils and motors

Abstract

The present application relates to a cable, comprising a conductor and an insulating layer wrapped around the conductor, wherein the outer contour of the cross section of the conductor is enclosed by four adjacent sides, the sides comprising a long side and a short side, and two adjacent sides are connected by a conductor fillet structure. The outer contour of the cross section of the insulating layer has insulating layer fillet structures that are the same in number and one-to-one correspondence with the conductor fillet structures, and the maximum thickness of the insulating layer fillet structures is greater than the average thickness of the remaining parts of the insulating layer except for the insulating layer fillet structures. The present application also relates to a coil and a motor. The cable described herein has low AC loss when the coil branch is unbalanced, and has high voltage resistance, heat resistance, and ATF oil resistance.

Description

Technical Field

[0001] The present application relates to the technical field of wires, and in particular to a cable, a coil and a motor. Background Art

[0002] Industrial motors, ships, railway vehicles, and electric vehicles all require coil electrical equipment, and the coils of such coil electrical equipment are generally manufactured by winding or bending insulated wires on the stator. With the rapid development of science and technology, the requirements for coil electrical equipment are also increasing. For example, the size of coil electrical equipment needs to be further reduced, and it can be driven at high voltage, high speed (frequency), and high power density to improve efficiency.

[0003] As the demand for high-efficiency and high-output electrical equipment increases, the use of inverters and high voltages is becoming more and more common. As a result, the inverter surge voltage value generated by inverter control increases, causing the partial discharge inception voltage (PDIV) of the insulated wire to reach 500V or higher, which requires the insulated wire to have a higher partial discharge inception voltage of 1200~1600Vp (high withstand voltage) than conventional insulated wires to suppress the occurrence of partial discharge caused by the increase in inverter surge voltage.

[0004] In order to place more wires in a limited space to increase the high temperature generated by the power density, some electrical or electronic equipment designs use ATF oil as a heat dissipation measure. Therefore, the insulating wire coating must also be resistant to ATF oil.

[0005] In addition, the coil is also affected by higher operating temperatures. When the coil gets hot, eddy current loss will be generated, resulting in reduced motor efficiency. Therefore, the insulation wire coating also needs to have high heat resistance and suppress the increase in coil temperature. In addition, when the coil branches are unbalanced, the coil will generate excessive AC losses.

[0006] For this reason, there is a continuous need in the art to develop a cable that has low AC loss, is resistant to high voltage, is heat resistant, and is resistant to ATF oil. Summary of the invention

[0007] In order to solve or at least partially solve the above-mentioned technical problems, the present application provides a cable with low AC loss, high voltage resistance, heat resistance and ATF oil resistance when the coil branch is unbalanced. The cable includes a conductor and an insulating layer wrapped around the outer circumference of the conductor, the outer contour of the conductor includes a conductor fillet structure, and the outer contour of the insulating layer includes an insulating layer fillet structure, and their number is the same and the positions correspond one to one. By setting the maximum thickness of the insulating layer fillet structure to be greater than the average thickness of the remaining parts of the insulating layer except the insulating layer fillet structure, the AC loss generated by the coil when the coil branch is unbalanced can be effectively reduced. In other embodiments, the insulating layer also includes a flexible composite material layer and a protective film layer made of specific materials. By controlling their thickness, the high voltage resistance, heat resistance and ATF oil resistance of the cable of the present application can be effectively improved.

[0008] The present application also aims to provide a coil, which comprises a stator around which the cable described herein is wound.

[0009] The object of the present application is also to provide a motor, which includes the coil as described above.

[0010] In a first aspect, the present application provides a cable, comprising a conductor and an insulating layer surrounding the conductor. In this embodiment, the outer contour of the cross section of the conductor is enclosed by four adjacent sides, the sides comprising a long side and a short side, and two adjacent sides are connected by a conductor fillet structure. In this embodiment, the outer contour of the cross section of the insulating layer has the same number of insulating layer fillet structures as the conductor fillet structures and one-to-one corresponding to each other, and the maximum thickness of the insulating layer fillet structure is greater than the average thickness of the remaining parts of the insulating layer except the insulating layer fillet structure.

[0011] In an implementation manner of the first aspect, the maximum thickness of the rounded corner structure of the insulating layer is between 0.003 mm and 0.01 mm thicker than the average thickness of the remaining parts of the insulating layer except the rounded corner structure of the insulating layer.

[0012] In an implementation of the first aspect, a maximum curvature radius of the rounded corner structure of the insulating layer is smaller than a sum of a maximum curvature radius of a conductor rounded corner structure corresponding to the rounded corner structure of the insulating layer and a minimum thickness of the insulating layer.

[0013] In an implementation of the first aspect, a maximum curvature radius of the insulating layer rounded structure is 0.003 mm to 0.02 mm smaller than a sum of a maximum curvature radius of a conductor rounded structure corresponding to the insulating layer rounded structure and a minimum thickness of the insulating layer.

[0014] In an implementation manner of the first aspect, the long side of the cross section of the conductor forms a smooth conductor protrusion structure outwardly.

[0015] In an implementation manner of the first aspect, a radius of curvature of the conductor protrusion structure is greater than or equal to three times the thickness of a cross section of the conductor in a short side direction.

[0016] In one implementation of the first aspect, the insulating layer includes:

[0017] A first insulating layer, disposed around the conductor;

[0018] a second insulating layer, arranged around the first insulating layer;

[0019] The thickness ratio of the first insulating layer to the second insulating layer is greater than 2:1, and the thickness of the first insulating layer is between 65 and 80 micrometers.

[0020] In an implementation of the first aspect, among the sides of the cross section of the conductor, a middle section of at least one side is recessed inwardly, so as to form a conductor strip groove on the conductor which is arranged along the length direction of the conductor and recessed inwardly.

[0021] In an implementation manner of the first aspect, the depth of the strip groove is in the range of 1.2 to 2 times the radius of curvature of the rounded corner of the conductor, and the width of the strip groove is in the range of 1 / 4 to 1 / 3 of the length of the side where the strip groove is located. In this implementation manner, the width of the strip groove on the side away from the insulating layer is smaller than the width of the strip groove on the side close to the insulating layer.

[0022] In one embodiment of the first aspect, the cable further comprises a flexible composite material layer and a protective film layer. The flexible composite material layer is arranged around the insulating layer, and the flexible composite material layer is prepared by composite of polyaramid fiber paper and polyimide film, and the thickness of the flexible composite material layer is 50 to 100 microns. The protective film layer is a PPS polyphenylene sulfide film spirally wound on the flexible composite material layer in the form of a multi-layer film layer, and the thickness of the protective film layer is 50 to 80 microns.

[0023] In one embodiment of the first aspect, the material of the first insulating layer includes a continuous phase resin and at least one dispersed phase resin having different dielectric constants.

[0024] In one embodiment of the first aspect, at 25° C., the dielectric constants of the continuous phase resin and the dispersed phase resin are not higher than 3.2, and the dielectric constant of the dispersed phase resin is lower than the dielectric constant of the continuous phase resin.

[0025] In one embodiment of the first aspect, the continuous phase resin and the dispersed phase resin are crystalline resins with a melting point of 300° C. or above, or the continuous phase resin and the dispersed phase resin are non-crystalline resins with a glass transition temperature of 130° C. or above.

[0026] In one embodiment of the first aspect, the glass transition temperature of the dispersed phase resin is higher than the glass transition temperature of the continuous phase resin, and the temperature difference of the glass transition temperatures is not less than 100°C.

[0027] In one embodiment of the first aspect, the storage elastic modulus of the continuous phase resin and the dispersed phase resin at 25° C. is 1 GPa to 6 GPa.

[0028] In one embodiment of the first aspect, at 25° C., the apparent viscosity of the dispersed phase resin is lower than the apparent viscosity of the continuous phase resin; at 380° C., the apparent viscosity of the dispersed phase resin is higher than the apparent viscosity of the continuous phase resin.

[0029] In one embodiment of the first aspect, the continuous phase resin includes a modified polyetheretherketone resin, the dispersed phase resin includes a modified polystyrene resin, and the mass ratio of the modified polyetheretherketone resin to the modified polystyrene resin is 35:60 to 60:35, wherein the modified polyetheretherketone resin includes 80% to 90% of polyetheretherketone by mass and 10% to 20% of polyphenylene sulfone by mass, and the modified polystyrene resin includes 80% to 90% of syndiotactic polystyrene by mass and 10% to 20% of atactic polystyrene by mass.

[0030] In an implementation manner of the first aspect, the material of the first insulating layer further includes a stabilizer, and the mass of the stabilizer is 2% to 6% of the total mass of the material of the first insulating layer.

[0031] In one embodiment of the first aspect, the storage elastic modulus of the second insulating layer at 25° C. is not less than 3 GPa, and the storage elastic modulus at 300° C. is not less than 130 MPa.

[0032] In one embodiment of the first aspect, at 25° C., the tensile modulus of the material of the first insulating layer is greater than the tensile modulus of the material of the second insulating layer, and the difference between the two is not less than 500 MPa, wherein the tensile modulus of the material of the second insulating layer is greater than 2500 MPa.

[0033] In one implementation of the first aspect, the material of the second insulating layer includes polyetheretherketone resin.

[0034] In a second aspect, the present application provides a coil, wherein the cable as described in the first aspect is wound around a stator of the coil.

[0035] In a third aspect, the present application provides a motor, comprising the coil as described in the second aspect.

[0036] Compared with the prior art, the beneficial effect of the present application is that the two mutually connected edges of the conductor and the insulation layer of the cable described herein are connected by a smooth rounded structure, and the maximum thickness of the rounded structure of the insulation layer is greater than the average thickness of the remaining parts of the insulation layer except the rounded structure of the insulation layer, which can effectively reduce the AC loss generated by the coil when the coil branch is unbalanced.

[0037] The insulating layer includes a first insulating layer and a second insulating layer, and the material of the first insulating layer includes a continuous phase resin with different dielectric constants and at least one dispersed phase resin. The continuous phase resin and the dispersed phase resin with different dielectric constants cooperate with each other to make the first insulating layer have a lower dielectric constant, thereby improving the partial discharge inception voltage of the cable. Furthermore, by limiting the performance parameters such as the glass transition temperature, storage elastic modulus, and apparent viscosity of the continuous phase resin and the dispersed phase resin, the heat resistance, stress cracking resistance, partial discharge inception voltage and other properties of the cable are improved. By limiting the performance parameters of the second insulating layer material, the insulating effect and environmental resistance of the insulating layer can be enhanced, and the corona discharge resistance, mechanical properties, chemical resistance, ATF oil resistance and heat resistance can be improved.

[0038] In addition, the insulating layer may also include a flexible composite material layer and a protective film layer. The flexible composite material layer may be prepared by composite of polyaramid fiber paper and polyimide film, and the thickness of the flexible composite material layer is 50 to 100 microns. The protective film layer may be a PPS polyphenylene sulfide film spirally wound on the flexible composite material layer in the form of a multilayer film layer, and the thickness of the protective film layer is 50 to 80 microns. The high voltage resistance and heat resistance of the cable of the present application can be effectively improved, and the cable has ATF oil resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the implementation of the present application, the following is a brief introduction to the relevant drawings. It is understood that the drawings described below are only used to illustrate some implementations of the present application, and those skilled in the art can also obtain many other technical features and connection relationships not mentioned in this document based on these drawings.

[0040] Figure 1 is a three-dimensional schematic diagram of a cable according to one embodiment of the present application;

[0041] Figure 2 is a schematic cross-sectional view of a cable according to one embodiment of the present application;

[0042] Figure 3 yes Figure 2 A partial enlarged view of the fillet area;

[0043] Figure 4 is a three-dimensional schematic diagram of a cable according to another embodiment of the present application;

[0044] Figure 5 is a three-dimensional schematic diagram of a cable from another perspective in another embodiment of the present application;

[0045] Figure 6 is a schematic cross-sectional view of a cable according to another embodiment of the present application;

[0046] Figure 7 yes Figure 6 A partial enlarged view of the middle conductor strip groove portion;

[0047] Figure 8 This is a schematic diagram of centering and positioning of a conductor routing operation in one embodiment of the present application;

[0048] Fig. 9 yes Figure 8 Side view of

[0049] Fig.10 is a schematic diagram of the use of a cable in another embodiment of the present application;

[0050] Fig.11 yes Fig. 9 Side view of

[0051] Fig.12 A schematic cross-sectional view showing a cable according to another embodiment of the present application;

[0052] Fig.13 A schematic cross-sectional view of a cable according to yet another embodiment of the present application is shown.

[0053] Description of reference numerals:

[0054] 1. Conductor; 10. Conductor rounded corner structure; 11. Conductor raised structure; 12. Conductor strip groove; 2. Insulation layer; 20. Insulation layer rounded corner structure; 21. Insulation layer raised structure; 22. Insulation layer strip groove; 23. First insulation layer; 24. Second insulation layer; 3. Flexible composite material layer; 4. Protective film layer; 100. Cable; 200. V-shaped clamp; 300. Cable fixing clamp. DETAILED DESCRIPTION

[0055] Unless otherwise defined, technical or scientific terms used in the present specification and claims shall have the common meanings understood by persons having ordinary skills in the technical field to which the present invention belongs.

[0056] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0057] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be connected, detachably connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0059] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings and embodiments of the present application.

[0060] Example 1

[0061] refer to Figures 1 to 3 , this embodiment relates to a cable 100 according to one implementation described herein.

[0062] First reference Figure 1 , Figure 1 Schematic diagram of a cable according to an embodiment of the present application. Figure 1 It can be seen that the cable 100 may include a conductor 1 and an insulating layer 2 surrounding the conductor 1. The insulating layer 2 may include a first insulating layer 23 and a second insulating layer 24. In a specific embodiment, the first insulating layer 23 is arranged around the conductor 1, and the second insulating layer 24 is arranged around the first insulating layer 23. The thickness ratio of the first insulating layer 23 to the second insulating layer 24 is greater than 2:1, and the thickness of the first insulating layer 23 is between 65 and 80 microns.

[0063] The features of the various components of the cable will now be described in more detail.

[0064] conductor

[0065] refer to Figure 2 and Figure 3 , Figure 2 is a schematic cross-sectional view of a cable according to one embodiment of the present application, and Figure 3 yes Figure 2 A partial enlarged view of the rounded corner area. The outer contour of the cross section of the conductor 1 is surrounded by four adjacent sides, including long sides and short sides, and the two adjacent sides are connected by the conductor rounded corner structure 10. The outer contour of the cross section of the insulating layer 2 has the same number of insulating layer rounded corner structures 20 as the conductor rounded corner structures 10 and one-to-one corresponding, and the maximum thickness of the insulating layer rounded corner structure 20 is greater than the average thickness of the remaining parts of the insulating layer 2 except the insulating layer rounded corner structure 20. When the conductor 1 passes through the current, the charge is easy to accumulate at the tip or corner (i.e., the spike effect), corresponding to the generation of a larger electric field, so the appropriate increase in the thickness of the rounded corner structure 20 is conducive to improving the reliability of insulation protection. In addition, when the wire is bent, the outer layer material of the tip or corner will extend more seriously, resulting in a reduction in thickness. Properly increasing the thickness of the corresponding part is conducive to maintaining and ensuring the insulation protection effect. In addition, for the extrusion process, due to the influence of curvature at the sharp corner, the fluidity of the molten extruded material will be slightly worse, so defects are prone to occur. On this basis, appropriately increasing the thickness is helpful to reduce the coating defects in this area. Of course, excessive local thickness will also cause inconsistent thickness of the coating layer, which can easily lead to excessive changes in the scale of thermal expansion and contraction caused by temperature changes, and then create the risk of cracking or wrinkling. In addition, when the wire is bent, the inner arc surface is prone to accumulation and marking problems caused by the overly thick coating layer. In a preferred embodiment, the maximum thickness of the fillet structure of the insulating layer is between 0.003mm and 0.01mm thicker than the average thickness of the rest of the insulating layer except for the fillet structure of the insulating layer. Through this arrangement, the conductor can be set at the position of the stator core wire slot to reduce the AC loss of the motor, while the DC resistance of the conductor remains almost unchanged.

[0066] In a specific embodiment, reference Figure 3, the maximum radius of curvature of the insulating layer rounded structure 20 is smaller than the sum of the maximum radius of curvature of the conductor rounded structure 10 corresponding to the insulating layer rounded structure 20 and the minimum thickness of the insulating layer 2. Structurally, the above-mentioned technical means enable the insulating layer 2 to have a relatively larger thickness at the rounded corners, so that the thickness change process of the outer edge of the conductor 1 from the maximum radius of curvature to the minimum radius of curvature can be followed. Specifically, the uniform change from the smallest to the largest and the reverse uniform change from the largest to the smallest in this part can be followed. In this way, during extrusion coating, it is not easy to have problems of uneven flow or local accumulation of molten material. In a preferred embodiment, the maximum radius of curvature of the insulating layer rounded structure 20 is 0.003mm to 0.02mm smaller than the sum of the maximum radius of curvature of the conductor rounded structure 10 corresponding to the insulating layer rounded structure 20 and the minimum thickness of the insulating layer 2.

[0067] Back to Figure 2 , the long side of the cross section of the conductor 1 can form a smooth conductor protrusion structure 11 outward. The raised conductor surface puts the material of the coating layer in a stretched state, which is more conducive to its attachment to the surface of the conductor 1 so as to discharge the residual gas between the coating layer and the conductor 1. When the temperature changes, the thermal expansion properties of the conductor 1 and the insulating layer 2 of different materials are inconsistent, which easily leads to inconsistent dimensional shrinkage. At this time, the straight or inner arc-shaped coating layer is relatively easier to detach from the surface of the conductor 1, and the protrusion structure used in this patent can eliminate this problem. In addition, the provision of a smooth protrusion structure is also conducive to achieving a uniform transition of the coating layer when the angle thickness increases.

[0068] On the other hand, the raised surface of conductor 1 is also the centering reference for the wire routing during the extrusion and plastic coating production. Setting the raised surface of conductor 1 can make the wire routing, the center reference and the center alignment of the extrusion die more accurate, thereby improving the quality control of production.

[0069] In addition, the plastic-coated conductor corresponding to the raised conductor surface is also raised. During the use of the motor, the stacked raised surfaces of the conductors are attached to each other and close to the middle, and a gradually increasing side gap can be formed from the inside to the outside on both sides. On the one hand, this can reduce the risk of insulation breakdown caused by charge accumulation at the corners of the conductors, and on the other hand, it also increases the exposed surface area and optimizes the heat dissipation effect of the motor.

[0070] Another point is that the convex contact of the stacked conductors is relatively flexible, which is conducive to reducing the vibration caused by vibration and electromagnetic alternating attraction during the use of the motor, preventing the insulation layer from being worn out due to large-area collision and friction between the conductors, and reducing noise. In a preferred embodiment, the radius of curvature of the conductor protrusion structure 11 is greater than or equal to three times the thickness of the cross section of the conductor 1 in the short side direction.

[0071] The conductor 1 may be formed as Figure 2 In the rectangular conductor of the cross-sectional view shown, the outer contour of the conductor 1 may include two long sides and two short sides, and the ends of the short sides and the long sides may be connected by the conductor rounded corner structure 10. Figure 2 In the illustrated embodiment, the conductor 1 may include four symmetrically arranged conductor fillet structures 10 .

[0072] Furthermore, the conductor 1 may be a single conductor formed using one conductor, or may be a stranded conductor formed by twisting a plurality of single conductors.

[0073] The material of conductor 1 can be, for example, annealed copper wire, aluminum wire or their alloy wire. The material of the copper wire is preferably oxygen-free copper or deoxidized copper. Recently, with the limited supply of rare earths for rare earth magnet motors, the demand for high-power density permanent magnet synchronous motors requiring rare earth magnets has continued to grow. The resulting design is the synchronous reluctance aluminum motor. This type of motor eliminates the use of rare earths and minimizes the use of copper, while making the synchronous reluctance aluminum motor lighter. Therefore, in the foreseeable future, aluminum alloy conductors will become increasingly important. Aluminum alloy conductors can include: aluminum-copper alloy, aluminum-silver alloy, aluminum-zinc alloy, aluminum-iron alloy or E-AlMgSi aluminum-magnesium-silicon alloy, etc.

[0074] The size of the conductor 1 is not particularly limited. For example, when the cross section of the conductor 1 is rectangular, the length of the long side is preferably 2.5 to 4.6 mm, and the length of the short side is preferably 1.6 to 3.0 mm. The ratio of the length of the short side to the long side is preferably 1:1.2 to 1:3. The R angle of the conductor rounded structure 10 is less than 0.5 mm, and the best is 0.3 mm.

[0075] The properties of the conductor 1 are not particularly limited, for example: elongation at break is 30-40% or more, tensile strength is 200 MPa or more, and yield strength is less than 140 MPa.

[0076] Insulation layer

[0077] The insulating layer 2 is wrapped around the outer circumference of the conductor 1 and fits the conductor 1 , so the outer contour of the insulating layer 2 is substantially the same as the outer contour of the conductor 1 , but is larger in size.

[0078] In a specific embodiment, the insulating layer 2 may include a first insulating layer 23 and a second insulating layer 24, and the thickness ratio of the first insulating layer 23 to the second insulating layer 24 is greater than 2:1, and the thickness of the first insulating layer 23 is between 65 and 80 microns. The thickness of the first insulating layer 23 and the second insulating layer 24 is set in this way, so that the cable can resist edge bending when it is wound into a coil and significantly improve the processability, and it is not easy to crack even when the curvature radius (0.3) at the corner of the conductor is very small. In addition, the thickness of the first insulating layer 23 and the second insulating layer 24 is set in this way to help improve its resistance to surface scratches and cracks generated during the coil edge bending process.

[0079] Example 2

[0080] refer to Figures 4 to 7 , this embodiment relates to a cable 100 according to another implementation described herein. Figure 4 4 is a three-dimensional schematic diagram of the cable of this embodiment. Figure 5 It is a three-dimensional schematic diagram of the cable of this embodiment from another viewing angle. Figure 6 is a schematic cross-sectional view of the cable of this embodiment, Figure 7 yes Figure 6 A partial enlarged view of the conductor strip groove part.

[0081] In this embodiment, among the sides of the cross section of the conductor 1, the middle section of at least one side is recessed inwards, so as to form a conductor strip groove 12 on the conductor 1, which is arranged along the length direction of the conductor 1 and recessed inwards. In a preferred embodiment, the depth of the conductor strip groove 12 is in the range of 1.2 to 2 times the radius of curvature of the fillet of the conductor 1, and the width of the conductor strip groove 12 is in the range of 1 / 4 to 1 / 3 of the length of the side where the conductor strip groove 12 is located. In a more preferred embodiment, the width of the conductor strip groove 12 on the side away from the insulating layer 2 is smaller than the width of the conductor strip groove 12 on the side close to the insulating layer 2.

[0082] Similarly, at positions corresponding to the conductor strip grooves 12 , the insulating layer 2 also includes insulating layer strip grooves 22 .

[0083] Example 3

[0084] This embodiment relates to a centering and positioning solution for conductor routing according to an implementation of the present application. Figure 8 and Fig. 9 A single cable is installed in two upper and lower positioning fixtures, and the center of the conductor 1 is found by using the upper and lower V-shaped fixtures 200 arranged opposite to each other. In actual use, the V-shaped fixture 200 can be replaced with a V-shaped roller to reduce the friction on the surface of the conductor 1.

[0085] Example 4

[0086] This embodiment relates to a method for using a cable according to an implementation of the present application, specifically a method for using the cable described herein in a drive motor. Fig.10 and Fig.11 , multiple cables or a single cable are installed in the cable fixing fixture 300 after being wound multiple times. In this embodiment, multiple cables have different cross-sectional shapes, wherein the cable closest to the opening of the cable fixing fixture 300 has a strip groove structure, and the opening of the strip groove is open toward the cable fixing fixture 300. In a preferred embodiment, a four-layer flat copper hairpin wire is embedded in the slot of the stator core of the motor, the bottom three layers are cables 100 with insulating layer protrusion structures 21 on both sides, and the top layer is a cable 100 with insulating layer strip grooves 22. In this way, the bottom cable 100 can achieve the original intention of the cable installation intention described above, and the groove surface of the outer layer can appropriately balance the electromagnetic alternating influence caused by the rounded corners on the outer side of the conductor, thereby reducing the AC loss of the current passing through the conductor.

[0087] Example 5

[0088] The dielectric constant of the insulation layer significantly affects the partial discharge inception voltage (PDIV) of the cable, and as the dielectric constant of the insulation layer increases, the partial discharge inception voltage of the cable tends to decrease. The dielectric constant of the insulation layer is affected by temperature. When the temperature rises, the dielectric constant of the insulation layer increases accordingly. For example, for some insulation layers, when the temperature rises from 25°C to 200°C, its relative dielectric constant will increase by about 1.2 to 1.6 times. Therefore, when the cable is used in a high temperature environment, the dielectric constant of the insulation layer will increase significantly, thereby significantly reducing the partial discharge inception voltage of the cable. For example, the partial discharge inception voltage of some insulation layers at 200°C is about 1 / 3 less than that at 25°C. The sharp drop in the partial discharge inception voltage of the cable is likely to cause an increase in the surge voltage of the inverter, which in turn leads to the occurrence of partial discharge.

[0089] In view of this, Example 5 of the present application improves the first insulating layer in the cable of the aforementioned embodiment to reduce the dielectric constant of the first insulating layer, thereby improving the above-mentioned partial discharge starting voltage characteristics. At the same time, the lower dielectric constant can also suppress the heat generation in the first insulating layer, thereby suppressing the degradation caused by heat. Specifically, this embodiment uses two or more resins with different dielectric constants as the material for making the first insulating layer. More specifically, the material of the first insulating layer may include a continuous phase resin and at least one dispersed phase resin, and the dielectric constants of the continuous phase resin and the dispersed phase resin are different, and the dielectric constants of the dispersed phase resins are also different.

[0090] The continuous phase resin and dispersed phase resin of different dielectric constants cooperate with each other to make the first insulating layer have a lower dielectric constant. When the selected continuous phase resin has a higher dielectric constant, a dispersed phase resin with a lower dielectric constant can be selected; when the selected continuous phase resin has a lower dielectric constant, a dispersed phase resin with a lower or slightly higher dielectric constant can be selected, thereby making the blended material of the continuous phase resin and the dispersed phase resin have a lower dielectric constant as a whole. Of course, in an ideal situation, two resins with lower dielectric constants can be selected, but in most cases they will be limited by other factors, such as temperature resistance, mechanical properties, etc. Therefore, the purpose of reducing the dielectric constant of the first insulating layer can be effectively achieved by blending resins with different dielectric constants.

[0091] Furthermore, the inventors of the present application have conducted in-depth research on cable materials, hoping to find a method that can make the cable have a higher partial discharge inception voltage at both low and high temperatures (e.g., 200°C to 300°C). After a lot of exploration, the inventors of the present application were pleasantly surprised to find that at 25°C, when the dielectric constants of the continuous phase resin and the dispersed phase resin are below 3.2, the cable can show a higher partial discharge inception voltage both under low temperature conditions and under high temperature conditions, thereby effectively avoiding the problem of breakdown caused by partial discharge in the cable due to inverter surge voltage. The dielectric constants of the continuous phase resin and the dispersed phase resin do not exceed 3.2 and 2.7, respectively. Preferably, the dielectric constants of the continuous phase resin and the dispersed phase resin are 3.1 and 2.6.

[0092] In some specific examples, the dielectric constant of the dispersed phase resin is lower than the dielectric constant of the continuous phase resin, thereby reducing the dielectric strength of the continuous phase resin, thereby increasing the partial discharge inception voltage of the cable. As an example, the dielectric constant of the continuous phase resin is 3.1, and the dielectric constant of the continuous phase resin is below 2.6.

[0093] The continuous phase resin and the dispersed phase resin may be a crystalline resin or a non-crystalline resin. When the continuous phase resin and the dispersed phase resin are crystalline resins, a crystalline resin with a melting point of more than 300°C is preferred; when the continuous phase resin and the dispersed phase resin are non-crystalline resins, a non-crystalline resin with a glass transition temperature of more than 130°C is preferred to improve the heat resistance of the cable. As an example, the crystalline resin may include a mixed resin of one or more of thermoplastic polyimide (TPI), nylon 6, modified polyetheretherketone resin, polyaryletherketone (PAEK, polyetherketoneketone), etc. In a specific embodiment, the modified polyetheretherketone resin includes polyetheretherketone (PEEK, polyetheretherketone) and polyphenylene sulfone resins (PPSU, Polyphenylene sulfone resins). The above-mentioned non-crystalline resin may include polyamide (PAI), modified polystyrene resin. In a specific embodiment, the modified polystyrene resin includes syndiotactic polystyrene (SPS) and atactic polystyrene.

[0094] When preparing the first insulating layer, in order to improve the adhesion of the first insulating layer, the crystallization process of the resin will be suppressed, that is, the first insulating layer is prepared by a crystallization control method. The first insulating layer prepared by this method will have a lower crystallinity. If the cable coated with the first insulating layer is prepared into a winding coil and wound into the stator, the first insulating layer will be deformed by the extrusion force, which will cause the breakdown voltage (BDV) to decrease. However, if the crystallinity of the resin is not suppressed when preparing the first insulating layer, it is easy to cause the crystallinity of the first insulating layer to be too high, thereby causing the elongation at break to decrease. For example, when the material of the first insulating layer is a modified polyetheretherketone resin, since the modified polyetheretherketone resin is a semi-crystalline polymer, its crystallization state will affect the performance, thereby affecting the performance of the first insulating layer. When the modified polyetheretherketone resin is in a fully crystalline state, its strength, insulation and temperature resistance will be improved, thereby improving the strength, insulation and temperature resistance of the first insulating layer. However, the modified polyetheretherketone resin in a fully crystalline state is prone to make the first insulating layer brittle due to excessive hardness, thereby increasing the risk of the wire in a bent state. However, when the modified polyetheretherketone resin is in an insufficiently crystalline state, the flexibility of the first insulating layer can be improved, which is more suitable for the bending of the wire, but the corresponding strength, insulation and temperature resistance will be reduced, thereby reducing the performance of the wire. In order to resolve this contradiction, this embodiment makes the glass transition temperature of the dispersed phase resin higher than the glass transition temperature of the continuous phase resin, and controls the temperature difference between the glass transition temperatures of the two to be not less than 100°C. In some preferred embodiments, an appropriate proportion of modified polystyrene resin is added to the modified polyetheretherketone resin. Because the crystallization temperature of the modified polystyrene resin is higher than that of the polyetheretherketone resin, it is possible to achieve the flexibility of the modified polyetheretherketone resin in an insufficiently crystalline state by adopting a crystallinity control method during extrusion production, while maintaining sufficient strength, insulation and temperature resistance of the first insulating layer. In this way, the reduction of the elastic modulus of the continuous phase resin at high temperature can be suppressed, and the problem of reduced elongation at break of the first insulating layer can be solved.

[0095] The inventors of the present application have also found that when the storage elastic modulus of the continuous phase resin and the dispersed phase resin at 25°C is 1GPa to 6GPa, it is beneficial for the cable to be prepared into a winding coil. When the storage elastic modulus of the continuous phase resin and the dispersed phase resin at 25°C is less than 1GPa, the wear characteristics are poor, so when the cable is prepared into a winding coil, there may be structural damage, affecting the electrical performance of the winding coil. When the storage elastic modulus of the continuous phase resin and the dispersed phase resin at 25°C exceeds 6GPa, the cable flexibility will decrease, and it will not be easy to form the winding.

[0096] When selecting the continuous phase resin and the dispersed phase resin, the apparent viscosity of the two must also be taken into account. At low temperatures, such as 25°C, the apparent viscosity of the dispersed phase resin must be lower than the apparent viscosity of the continuous phase resin, so that the dispersed phase resin can maintain a state of dispersion in the continuous phase resin and maintain a better dielectric effect (lower dielectric constant). At high temperatures, such as 380°C, the apparent viscosity of the dispersed phase resin must be higher than the apparent viscosity of the continuous phase resin, because when extruding and coating the wire, the material needs to be at a high temperature (such as 380°C or above) to be fully coated around the conductor. If the continuous phase resin has a lower viscosity at high temperatures, it will be more conducive to the full flow of the continuous phase, and then to the uniform dispersion of the dispersed phase. At the same time, it is also conducive to the coating of the insulating layer on the surface of the conductor, so that the wire has a higher partial discharge starting voltage and maintains the performance of the wire under use conditions (the use temperature is lower than the processing temperature of 380°C). Preferably, at 25° C., the apparent viscosity of the continuous phase resin is about 1000 Pa.s, and the apparent viscosity of the dispersed phase resin is 200 Pa.s. At 400° C., the apparent viscosity of the continuous phase resin is about 150 Pa.s.

[0097] In summary, the material selection of the first insulating layer of the present application needs to consider many factors to further improve the heat resistance, stress cracking resistance, partial discharge starting voltage and other properties of the cable and the winding coil made of the cable.

[0098] Based on this, the present embodiment also provides a specific material selection for the first insulating layer, wherein the continuous phase resin includes a modified polyetheretherketone resin, and the dispersed phase resin includes a modified polystyrene resin. The modified polyetheretherketone resin includes 80% to 90% polyetheretherketone by mass and 10% to 20% polyphenylene sulfone by mass. The modified polystyrene resin contains 80% to 90% syndiotactic polystyrene by mass and 10% to 20% atactic polystyrene by mass. At 25°C, the dielectric constant of the modified polyetheretherketone resin is 3.1, and the dielectric constant of the modified polystyrene resin is 2.6. Therefore, the first insulating layer formed by blending the modified polyetheretherketone resin and the modified polystyrene resin will have a lower dielectric constant, thereby effectively avoiding the problem of breakdown caused by partial discharge in the cable due to the surge voltage of the inverter.

[0099] At the same time, at room temperature, the apparent viscosity of the modified polyetheretherketone resin is 1000Pa.s at room temperature, the apparent viscosity at 400℃ is 150Pa.s, the Tg is 143℃, and the storage elastic modulus is 2-3GPa. The apparent viscosity of the modified polystyrene resin at room temperature is 200Pa.s, the glass transition temperature is 280℃, and the storage elastic modulus is 2200MPa. This material property is conducive to improving the heat resistance, partial discharge starting voltage and breakdown voltage of the cable, and makes the first insulating layer have suitable softness and wear resistance, which is conducive to improving the performance of the winding coil.

[0100] Furthermore, the mass ratio of the modified polyetheretherketone resin to the modified polystyrene resin affects the heat resistance and dielectric constant of the first insulating layer. When the mass ratio of the modified polyetheretherketone resin to the modified polystyrene resin is too small, it is not conducive to improving the heat resistance, and when the mass ratio of the modified polyetheretherketone resin to the modified polystyrene resin is too large, it is not conducive to reducing the dielectric constant of the first insulating layer. When the mass ratio of the modified polyetheretherketone resin to the modified polystyrene resin is 35:60 to 60:35, the first insulating layer can have both excellent heat resistance and a lower dielectric constant.

[0101] Since the first insulating layer of the present embodiment includes at least a two-phase structure, a stabilizer may be added to further improve the stability of different phases when blended. The mass of the stabilizer is 2% to 6% of the total mass of the material of the first insulating layer. Preferably, the stabilizer may be an ethylene copolymer, such as E-GMA ethylene / glycidyl methacrylate copolymer. The use of an ethylene copolymer can improve the blending stability of the continuous phase resin and the dispersed phase resin, thereby improving the quality of the first insulating layer, thereby better improving the heat resistance and partial discharge inception voltage of the cable, and at the same time improving the adhesion of the first insulating layer to the conductor surface.

[0102] The first insulating layer of this embodiment is introduced above, and the second insulating layer of this embodiment will be described in detail below.

[0103] The storage elastic modulus of the second insulating layer of this embodiment at 25°C is not less than 3GPa, and the storage elastic modulus at 300°C is not less than 130MPa. When the elastic modulus of the second insulating layer at 25°C is less than 3GPa, the wear characteristics are reduced, and the cable needs to be wound into a coil under low load conditions. When the elastic modulus of the second insulating layer at 300°C is less than 130MPa, the partial discharge inception voltage may be greatly reduced.

[0104] At 25°C, the tensile modulus of the material of the second insulating layer is less than the tensile modulus of the material of the first insulating layer, and the difference between the two is not less than 500 MPa, wherein the tensile modulus of the material of the second insulating layer is greater than 2500 MPa. When the tensile modulus of the material of the second insulating layer is greater than the tensile modulus of the material of the first insulating layer, the stress during cable winding will be concentrated on the second insulating layer, which will increase the probability of cracks at the arc of the cable corner due to bending.

[0105] In this embodiment, polyetheretherketone resin is selected as the material of the second insulating layer, which can better meet the above requirements on the one hand, and also has the following advantages on the other hand.

[0106] Choosing polyetheretherketone resin as the material for the second insulation layer can prevent the corona discharge effect and improve the electrical performance of the cable. The corona discharge effect refers to the ionization of the air around the conductor when current flows through the conductor. The corona discharge effect is particularly significant when the distance between adjacent cables is close. Over time, the insulation layer of the cable will lose its ability to prevent discharge, affecting the electrical performance of the cable.

[0107] PEEK resin also has higher heat resistance and higher dielectric constant, which can ensure that the insulation layer maintains excellent insulation performance for a long time. PEEK resin can be made into a film layer by extrusion molding. Compared with traditional enamel coatings such as PAI, PEEK resin can make the second insulation layer thinner and have better flexibility. The thinner second insulation layer can more easily release the heat of the conductor in the cable. PEEK resin also has excellent resistance to cooling oil (such as ATF oil), which can reduce the overall temperature of electrical or electronic equipment and minimize the energy lost by heat dissipation.

[0108] When polyetheretherketone resin is used as the material for making the second insulating layer, no organic solvent is required, thus avoiding the generation of volatile organic compounds (VOC) when making the second insulating layer. At the same time, due to its good thermoplasticity, it can be easily recycled without causing environmental pollution.

[0109] In some specific embodiments, the first insulating layer includes modified polyetheretherketone resin, modified polystyrene resin and E-GMA ethylene / glycidyl methacrylate copolymer, and the second insulating layer includes polyetheretherketone resin, wherein the first insulating layer not only has a strong bonding force with the conductor surface, but also forms a common compatible bond with the second insulating layer, thereby improving the heat resistance, partial discharge initiation voltage and breakdown voltage of the cable.

[0110] Example 6

[0111] Embodiment 6 of the present application further improves the structure of the cable. Fig.12 and Fig.13 The cable of this embodiment may further include a flexible composite material layer and a protective film layer, wherein the flexible composite material layer is arranged around the insulating layer, and the protective film layer is spirally wound on the flexible composite material layer in the form of a multi-layer film layer.

[0112] The flexible composite material layer is composited by polyaramid fiber paper and polyimide film. Specifically, the flexible composite material layer is a polyimide film dipped in a heat-resistant adhesive, which is prepared by a heating precuring method. Polyaramid fiber paper and polyimide film have excellent corona resistance and partial discharge characteristics. Providing a flexible composite material layer can save the step of laying interlayer insulating paper in the stator core groove, simplify the cable manufacturing process, and also realize slot automation. The thickness of the flexible composite material layer is preferably 50 to 100 microns.

[0113] There is a risk of damaging the soft composite material layer and causing it to fluff during the U-shaped bending of the cable and the insertion of the formed U-shaped line segment into the slot of the stator core groove. Therefore, a protective film layer can be set on the flexible composite material layer to protect the flexible composite material layer from damage. Based on the needs of high elastic modulus, long-term heat resistance and high extrusion resistance, polyphenylene sulfide (PPS) is selected as the material for making the protective film layer. The thickness of the protective film layer is preferably 50 to 80 microns. When the thickness of the protective film layer is too thick, it is not conducive to improving the full slot rate; when the protective film layer is too thin, it is easy to break during the bending process.

[0114] Finally, it should be noted that those skilled in the art can understand that in order to enable readers to better understand the present application, the embodiments of the present application provide many technical details. However, even without these technical details and various changes and modifications based on the above-mentioned embodiments, the technical solutions claimed for protection by the claims of the present application can be basically realized. Therefore, in practical applications, various changes can be made to the above-mentioned embodiments in form and detail without departing from the spirit and scope of the present application.

Claims

1. A cable comprising a conductor and an insulating layer surrounding the conductor, characterized in that: The outer contour of the cross section of the conductor is enclosed by four adjacent sides, wherein the sides include a long side and a short side, and two adjacent sides are connected by a conductor fillet structure; The outer contour of the cross section of the insulating layer has insulating layer rounded corner structures that are the same in number and correspond one to one with the conductor rounded corner structures, and the maximum thickness of the insulating layer rounded corner structures is greater than the average thickness of the remaining parts of the insulating layer except the insulating layer rounded corner structures; The long side of the cross section of the conductor forms a smooth conductor protrusion structure outwardly, and the curvature radius of the conductor protrusion structure is greater than or equal to three times the thickness of the cross section of the conductor in the short side direction.

2. The cable according to claim 1, characterized in that: The maximum thickness of the rounded corner structure of the insulating layer is between 0.003 mm and 0.01 mm thicker than the average thickness of the remaining parts of the insulating layer except the rounded corner structure of the insulating layer.

3. The cable according to claim 1, characterized in that: The maximum curvature radius of the insulating layer rounded corner structure is smaller than the sum of the maximum curvature radius of the conductor rounded corner structure corresponding to the insulating layer rounded corner structure and the minimum thickness of the insulating layer.

4. The cable according to claim 3, characterized in that: The maximum curvature radius of the insulating layer rounded corner structure is 0.003 mm to 0.02 mm smaller than the sum of the maximum curvature radius of the conductor rounded corner structure corresponding to the insulating layer rounded corner structure and the minimum thickness of the insulating layer.

5. The cable according to claim 1, characterized in that: The insulating layer comprises: A first insulating layer, disposed around the conductor; a second insulating layer, arranged around the first insulating layer; The thickness ratio of the first insulating layer to the second insulating layer is greater than 2:1, and the thickness of the first insulating layer is between 65 and 80 micrometers.

6. The cable according to claim 1, characterized in that: Among the sides of the cross section of the conductor, the middle section of at least one side is recessed inwards, so as to form a conductor strip groove on the conductor which is arranged along the length direction of the conductor and recessed inwards.

7. The cable according to claim 6, characterized in that: The depth of the strip groove is in the range of 1.2 to 2 times the radius of curvature of the rounded corner of the conductor, and the width of the strip groove is in the range of 1 / 4 to 1 / 3 of the length of the side where the strip groove is located; The width of the strip-shaped groove at a side away from the insulating layer is smaller than the width of the strip-shaped groove at a side close to the insulating layer.

8. The cable according to claim 1, characterized in that: The cable also includes: A flexible composite material layer is arranged around the insulating layer; the flexible composite material layer is prepared by compounding polyaramid fiber paper and polyimide film, and the thickness of the flexible composite material layer is 50 to 100 microns; The protective film layer is formed by spirally winding a PPS polyphenylene sulfide film on the flexible composite material layer in the form of a multi-layer film layer, and the thickness of the protective film layer is 50 to 80 microns.

9. The cable according to claim 5, characterized in that: The material of the first insulating layer includes a continuous phase resin having different dielectric constants and at least one dispersed phase resin.

10. The cable according to claim 9, characterized in that: At 25° C., the dielectric constants of the continuous phase resin and the dispersed phase resin are no higher than 3.2, and the dielectric constant of the dispersed phase resin is lower than the dielectric constant of the continuous phase resin.

11. The cable according to claim 9, characterized in that: The continuous phase resin and the dispersed phase resin are crystalline resins having a melting point of 300° C. or higher, or the continuous phase resin and the dispersed phase resin are non-crystalline resins having a glass transition temperature of 130° C. or higher.

12. The cable according to claim 9, characterized in that: The glass transition temperature of the dispersed phase resin is higher than the glass transition temperature of the continuous phase resin, and the temperature difference of the glass transition temperature is not less than 100°C.

13. The cable according to claim 9, characterized in that: The storage elastic modulus of the continuous phase resin and the dispersed phase resin at 25° C. is 1 GPa to 6 GPa.

14. The cable according to claim 9, characterized in that At 25° C., the apparent viscosity of the dispersed phase resin is lower than the apparent viscosity of the continuous phase resin; at 380° C., the apparent viscosity of the dispersed phase resin is higher than the apparent viscosity of the continuous phase resin.

15. The cable according to any one of claims 9 to 14, characterized in that: The continuous phase resin includes a modified polyetheretherketone resin, the dispersed phase resin includes a modified syndiotactic polystyrene resin, and the mass ratio of the modified polyetheretherketone resin to the modified polystyrene resin is 35:60 to 60:35, wherein the modified polyetheretherketone resin includes 80% to 90% of polyetheretherketone by mass and 10% to 20% of polyphenylene sulfone by mass, and the modified polystyrene resin includes 80% to 90% of syndiotactic polystyrene by mass and 10% to 20% of atactic polystyrene by mass.

16. The cable according to claim 9, characterized in that The material of the first insulating layer further includes a stabilizer, and the mass of the stabilizer is 2% to 6% of the total mass of the material of the first insulating layer.

17. The cable according to claim 5, characterized in that The second insulating layer has a storage elastic modulus of not less than 3 GPa at 25° C., and a storage elastic modulus of not less than 130 MPa at 300° C.

18. The cable according to claim 5, characterized in that At 25° C., the tensile modulus of the material of the first insulating layer is greater than the tensile modulus of the material of the second insulating layer, and the difference between the two is not less than 500 MPa, wherein the tensile modulus of the material of the second insulating layer is greater than 2500 MPa.

19. The cable according to claim 5, 17 or 18, characterized in that: The material of the second insulating layer includes polyetheretherketone resin.

20. A coil, characterized in that: The cable according to any one of claims 1 to 19 is wound around the stator of the coil.

21. A motor, characterized in that: The motor comprises the coil as claimed in claim 20.

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