Preparation method of traction motor stator insulation structure

Abstract

The invention relates to the technical field of stator insulation, in particular to a preparation method of a traction motor stator insulation structure, which comprises the following steps of: S1, specifically adopting a polyimide enameled polyether-ether-ketone extruded wire as turn-to-turn insulation, and carrying out hairpin coil forming on an electromagnetic wire; s2, a composite foil composed of aromatic polyamide fiber paper, mica paper and a polyimide film is adopted as ground insulation, the composite foil is preformed to form an O-shaped groove for insulation, then the composite foil is inserted into the iron core groove, the hairpin coil is inserted into the iron core groove, and shaping, head twisting and welding are completed; and S3, preparing interphase insulation of the hairpin winding coil stator, and performing potting treatment on the stator subjected to wire plugging and welding by adopting corona-resistant epoxy resin to serve as the interphase insulation. The insulation structure prepared by the preparation method of the insulation structure in the scheme has excellent electrical aging resistance, extrusion resistance and wear resistance, and the hairpin coil is insulated, extruded and free of damage in the forming process.

Description

A method for preparing a traction motor stator insulation structure Technical Field

[0001] This invention relates to the field of stator insulation technology, and specifically provides a method for preparing a stator insulation structure for a traction motor. Background Technology

[0002] With economic development and social progress, the development of rail transit is shifting from pursuing speed and scale to focusing on quality and efficiency. In order to build a safe, convenient, efficient, green, and economical modern integrated transportation system, higher requirements are being placed on drive motor technology, especially in terms of miniaturization, lightweighting, efficiency, and economy.

[0003] Currently, hairpin winding motors have attracted much attention due to their superior performance. Under the same output power, the flat conductor has a higher space utilization rate and requires less copper conductor filling volume. This allows for a reduction in stator core stack thickness and end height, resulting in a smaller size and lighter weight for the motor. This structural optimization saves raw materials while effectively improving the power density of the motor. The winding method of hairpin motors mainly adopts the hairpin form, which consists of three parts: the crown end (responsible for end connection), the straight section (embedded in the stator slot), and the welded end (connecting each pin wire), forming a complete stator winding structure. The insulation structure of the motor in the hairpin motor mainly includes inter-turn insulation, ground insulation, and phase-to-phase insulation. However, the rated voltage of the currently mainstream hairpin winding motors reaches a maximum of about 800V. For higher voltage levels, especially 1800V applications, no research reports have been found.

[0004] When the traction motor is controlled by a high-frequency PWM (Pulse Width Modulation) inverter and the system DC bus voltage is increased to 1800V, according to the GB / T22720.1 standard "General Rules for Functional Evaluation of Insulation Structure of Rotating Electrical Machines", motors with rated operating voltage (referring to the level corresponding to the highest continuous operating voltage effective value or peak value of the winding to ground) exceeding 700V and operating under frequency conversion conditions are usually classified as Type II insulation structure. The characteristic of this insulation structure is that partial discharge (PD) is allowed during normal operation and within the design life, but its insulation system must have sufficient corona resistance (partial discharge resistance) to ensure that insulation damage caused by partial discharge is controllable and will not lead to failure throughout the entire service life.

[0005] Therefore, for motors operating at extremely high voltages (such as 1800V bus voltage systems), their insulation structure, especially key components such as inter-turn insulation, ground insulation, and phase-to-phase insulation, must possess excellent resistance to corona aging and long-term reliability to meet the severe challenges of steep voltage rise rate (dV / dt) and high-frequency pulse voltage stress generated by high-frequency PWM inverters.

[0006] In hairpin motors, inter-turn insulation is usually achieved by the insulation layer of the electromagnetic wire. Variable frequency traction motors widely use PWM modulation drive, and their output is a pulse waveform (square wave). However, after voltage modulation, the motor winding current is close to a sine wave. The insulation of the variable frequency motor needs to withstand high-frequency PWM voltage impacts with different pulse widths, which produces the following effects: 1) High-frequency PWM causes skin effect (mainly in the winding conductor), which increases resistance and copper loss, thereby aggravating winding heating. This not only reduces motor efficiency but also accelerates insulation aging; 2) High-frequency harmonics also increase flux-related stray losses and frequently impact inter-turn insulation (especially steep wavefront voltages with short rise times, commonly seen in starting and high-order harmonic situations). Therefore, the damage to inter-turn insulation directly depends on the insulation performance of the winding wire.

[0007] For 1800V variable frequency motors, the inter-turn insulation often uses corona-resistant polyimide film electromagnetic wire. However, the filler affects the mechanical toughness and is prone to damage to the insulation layer when the hairpin coil is formed and bent. Another material, such as corona-resistant enameled wire, has good coil forming processability, but it cannot completely avoid pinhole defects, making it difficult to meet the requirements of high reliability applications such as rail.

[0008] The ground insulation (slot insulation) of hairpin motors generally uses composite foil materials, such as a composite of aromatic polyamide fiber paper (NOMEX 464) and polyimide film, or a composite of mica-coated aromatic polyamide fiber paper (NOMEX 864) and polyimide film. However, under the high-frequency pulse environment of 1800V voltage level, the electrical aging resistance (partial discharge resistance) of these materials is insufficient. Therefore, in order to avoid the above problems, a new type of traction motor insulation structure needs to be designed. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a method for preparing a stator insulation structure for a traction motor. The prepared insulation structure exhibits excellent resistance to electrical aging and resistance to compression and wear, meeting the insulation requirements of an 1800V variable frequency motor.

[0010] This invention provides a method for preparing the stator insulation structure of a traction motor, comprising the following steps: S1: Preparing the inter-turn insulation of the hairpin winding coil stator; specifically, using polyimide enameled polyetheretherketone extrusion wire as the inter-turn insulation, and forming the electromagnetic wire into a hairpin coil; polyimide forming a polyimide resin layer, and polyetheretherketone forming a polyetheretherketone resin layer; S2: Preparing the ground insulation of the hairpin winding coil stator; specifically, using a composite foil composed of aromatic polyamide fiber paper, mica paper, and polyimide film as the ground insulation; pre-forming the composite foil into an O-shaped groove for insulation, then inserting it into the iron core groove, and then inserting the hairpin coil into the iron core groove to complete the shaping, twisting, and welding; S3: Preparing the phase-to-phase insulation of the hairpin winding coil stator; using corona-resistant epoxy resin to pot the stator after insertion and welding as phase-to-phase insulation.

[0011] Furthermore, both the polyimide resin layer and the polyetheretherketone resin layer in S1 contain corona-resistant fillers, which are selected from one or more of alumina, silicon oxide, and boron nitride.

[0012] Furthermore, the manufacturing steps for the inter-turn insulation in S1 are as follows: First, a layer of corona-resistant polyimide varnish is coated onto the copper conductor using a vertical enameling machine to form a polyimide resin layer. Then, a layer of corona-resistant polyetheretherketone is extruded onto the enameled wire using an extruder to form a polyetheretherketone resin layer, thereby forming the inter-turn insulation of the hairpin winding coil stator.

[0013] Furthermore, the copper conductor is precision rolled from oxygen-free copper rod.

[0014] Furthermore, the thickness of the polyimide resin layer in S1 ranges from 0.15 to 0.30 mm, and the thickness of the polyetheretherketone resin layer ranges from 0.10 to 0.30 mm.

[0015] Furthermore, the thickness of the polyimide resin layer is preferably 0.20 mm, and the thickness of the polyetheretherketone resin layer is preferably 0.16 mm.

[0016] Furthermore, the composite foil in S2 is formed by using a coating machine to bond aromatic polyamide fiber paper, mica paper, and polyimide film together with an adhesive to form a composite foil for ground insulation.

[0017] Furthermore, in S2, the thickness of the aromatic polyamide fiber paper in the composite foil is 0.05~0.125mm, the thickness of the mica paper is 0.05~0.125mm, and the thickness of the polyimide film is 0.05~0.125mm.

[0018] Furthermore, the thickness of the aromatic polyamide fiber paper is preferably 0.05 mm, the thickness of the mica paper is preferably 0.075 mm, and the thickness of the polyimide film is preferably 0.125 mm.

[0019] Furthermore, when potting the stator in S3, corona-resistant filler is added to the potting resin. The corona-resistant filler is selected from one or more of alumina, silicon dioxide, and boron nitride. The thickness of the epoxy resin potting layer in S3 is 10mm to 50mm.

[0020] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. The traction motor insulation structure in this solution can overcome the problem that the existing hairpin winding coil motor insulation structure cannot meet the 1800V voltage level requirements. The inter-turn insulation of this insulation structure is corona-resistant polyimide enameled polyether ether ketone extrusion wire, and the ground insulation (slot insulation) is a composite foil composed of aromatic polyamide fiber paper, mica paper, and polyimide film. The phase insulation uses corona-resistant epoxy resin to pot the stator. The 1800V voltage level hairpin winding coil motor made with this insulation structure has excellent anti-electric aging life, the corona resistance time of the inter-turn insulation is higher than 500h, and the PDIV value is higher than 2000V.

[0021] 2. In this solution, the ground insulation (slot insulation) is a composite foil composed of aromatic polyamide fiber paper, mica paper, and polyimide film. Its corona resistance time is higher than 100h, and its PDIV value is higher than 1500V. It has excellent hot pressing processability and wear resistance. The slot insulation is undamaged during the coil slotting process. The phase-to-phase insulation is encapsulated with epoxy resin. The thermal conductivity of this epoxy resin is 1.2w / mK, which has excellent thermal conductivity.

[0022] 3. The insulation structure in this solution has excellent mechanical properties, especially excellent resistance to extrusion and wear. It can effectively avoid the problem of insulation layer damage caused by extrusion during coil forming, and can effectively prevent mechanical damage to the slot insulation during the hairpin coil insertion process. At the same time, it can also solve the problem that traditional polyetheretherketone electromagnetic wire does not have corona resistance. The insulation is not damaged by extrusion during the hairpin coil forming process. Attached Figure Description

[0023] Figure 1 is a schematic diagram of the inter-turn insulation provided according to Embodiment 1 of the present invention; Figure 2 is a schematic diagram of the ground insulation provided according to Embodiment 1 of the present invention.

[0024] The reference numerals in the figures include: copper conductor 1, polyimide resin layer 2, polyetheretherketone resin layer 3, aromatic polyamide fiber paper 4, adhesive 5, mica paper 6, and polyimide film 7. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to Figures 1-2 and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof. Embodiment 1

[0026] A method for preparing a stator insulation structure for a traction motor includes the following steps: S1: Preparing inter-turn insulation for a hairpin winding coil stator; specifically, using polyimide enameled polyetheretherketone extrusion wire as inter-turn insulation, and forming the electromagnetic wire into a hairpin coil; polyimide forming a polyimide resin layer 2, polyetheretherketone forming a polyetheretherketone resin layer 3, both polyimide resin layer 2 and polyetheretherketone resin layer 3 containing corona-resistant filler, the corona-resistant filler being selected from one or more of alumina, silicon oxide, and boron nitride, wherein alumina includes α-alumina, γ-alumina and other crystal forms, silicon oxide includes fumed silica, precipitated silica and other types, boron nitride includes hexagonal boron nitride, cubic boron nitride and other crystal forms, and the particle size range of the above corona-resistant filler is 10nm-100μm.

[0027] The thickness of the polyimide resin layer 2 ranges from 0.15 to 0.30 mm, and the thickness of the polyetheretherketone resin layer 3 ranges from 0.10 to 0.30 mm. In this embodiment, the thickness of the polyimide resin layer 2 is preferably 0.20 mm, and the thickness of the polyetheretherketone resin layer 3 is preferably 0.16 mm.

[0028] The steps for manufacturing inter-turn insulation are as follows: First, a layer of corona-resistant polyimide varnish is coated onto the copper conductor 1 using a vertical enameling machine to form a polyimide resin layer 2. Then, a layer of corona-resistant polyetheretherketone is extruded onto the enameled wire using an extruder to form a polyetheretherketone resin layer 3. This forms the inter-turn insulation of the hairpin winding coil stator. The copper conductor 1 is precision rolled from oxygen-free copper rod, and the dimensions of the copper conductor 1 are 2.84 × 3.10 mm.

[0029] The 1800V hairpin winding coil motor made using the insulation structure in this embodiment has excellent anti-electric aging life, with a corona resistance time of more than 500 hours between turns, a PDIV value of more than 2000V, and excellent extrusion and wear resistance. The insulation is not damaged by extrusion during the hairpin coil forming process.

[0030] S2: Prepare the ground insulation of the hairpin winding coil stator; specifically, use a composite foil composed of aromatic polyamide fiber paper 4, mica paper 6, and polyimide film 7 as ground insulation; pre-form the composite foil into an O-shaped groove for insulation, then insert it into the iron core groove, and then insert the hairpin coil into the iron core groove to complete the shaping, twisting, and welding.

[0031] The composite foil is formed by using a coating machine to bond aromatic polyamide fiber paper 4, mica paper 6, and polyimide film 7 together with adhesive 5 to form a composite foil for ground insulation.

[0032] In this composite foil, the thickness of the aromatic polyamide fiber paper 4 is 0.05~0.125mm, the thickness of the mica paper 6 is 0.05~0.125mm, and the thickness of the polyimide film 7 is 0.05~0.125mm. In this embodiment, the thickness of the aromatic polyamide fiber paper 4 is preferably 0.05mm, the thickness of the mica paper 6 is preferably 0.075mm, and the thickness of the polyimide film 7 is preferably 0.125mm.

[0033] The 1800V voltage level hairpin winding coil motor made with the insulation structure in this embodiment has a corona resistance time of more than 100h and a PDIV value of more than 1500V to ground. It has excellent hot pressing processability and wear resistance, and the slot insulation is not damaged during the coil slotting process.

[0034] S3: Prepare interphase insulation for the stator of the hairpin winding coil; use corona-resistant epoxy resin to pot the stator after wiring and welding as interphase insulation. The thermal conductivity of this epoxy resin is 1.2 W / mK. When potting the stator, the corona-resistant filler in the potting resin is selected from one or more of alumina, silicon oxide, and boron nitride. Among them, alumina includes α-alumina, γ-alumina, etc., silicon oxide includes fumed silica, precipitated silica, etc., and boron nitride includes hexagonal boron nitride, cubic boron nitride, etc. The particle size range of the above corona-resistant filler is 10 nm-100 μm. In this embodiment, α-alumina with a particle size of 20 μm is added to the potting resin; the thickness of the epoxy resin potting layer in S3 is 10 mm to 50 mm, preferably 12 mm. Example 2

[0035] The difference between this embodiment and Embodiment 1 is that the thickness of the polyimide resin layer 2 is 0.3 mm, the thickness of the polyetheretherketone resin layer 3 is preferably 0.3 mm, the thickness of the aromatic polyamide fiber paper 4 is preferably 0.1 mm, the thickness of the mica paper 6 is preferably 0.05 mm, and the thickness of the polyimide film 7 is preferably 0.1 mm. Embodiment 3

[0036] The difference between this embodiment and Embodiment 1 is that the thickness of the polyimide resin layer 2 is 0.15 mm, the thickness of the polyetheretherketone resin layer 3 is preferably 0.1 mm, the thickness of the aromatic polyamide fiber paper 4 is preferably 0.125 mm, the thickness of the mica paper 6 is preferably 0.125 mm, and the thickness of the polyimide film 7 is preferably 0.05 mm.

[0037] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0038] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a stator insulation structure for a traction motor, characterized in that, The process includes the following steps: S1: Prepare the inter-turn insulation of the hairpin winding coil stator; specifically, use polyimide enameled polyether ether ketone extruded wire as the inter-turn insulation, and shape the electromagnetic wire into a hairpin coil; polyimide forms a polyimide resin layer (2), and polyether ether ketone forms a polyether ether ketone resin layer (3); S2: Prepare the ground insulation of the hairpin winding coil stator; specifically, use a composite foil composed of aromatic polyamide fiber paper (4), mica paper (6), and polyimide film (7) as the ground insulation; pre-form the composite foil into an O-shaped groove for insulation, then insert it into the iron core groove, and then insert the hairpin coil into the iron core groove to complete the shaping, twisting, and welding; S3: Prepare the phase-to-phase insulation of the hairpin winding coil stator; use corona-resistant epoxy resin to pot the stator after insertion and welding as phase-to-phase insulation.

2. The method for preparing the stator insulation structure of the traction motor according to claim 1, characterized in that, Both the polyimide resin layer (2) and the polyether ether ketone resin layer (3) in S1 contain corona-resistant fillers, which are selected from one or more of alumina, silicon oxide, and boron nitride.

3. The method for preparing the stator insulation structure of the traction motor according to claim 2, characterized in that, The steps for making the inter-turn insulation in S1 are as follows: First, a layer of corona-resistant polyimide varnish is coated on the copper conductor (1) using a vertical enameling machine to form a polyimide resin layer (2). Then, a layer of corona-resistant polyether ether ketone is extruded onto the enameled wire using an extruder to form a polyether ether ketone resin layer (3), thereby forming the inter-turn insulation of the hairpin winding coil stator.

4. The method for preparing the stator insulation structure of the traction motor according to claim 3, characterized in that, The copper conductor (1) is made by precision rolling of oxygen-free copper rod.

5. The method for preparing the stator insulation structure of the traction motor according to claim 1, characterized in that, The thickness of the polyimide resin layer (2) in S1 ranges from 0.15 to 0.30 mm, and the thickness of the polyether ether ketone resin layer (3) ranges from 0.10 to 0.30 mm.

6. The method for preparing the stator insulation structure of the traction motor according to claim 5, characterized in that, The thickness of the polyimide resin layer (2) is preferably 0.20 mm, and the thickness of the polyether ether ketone resin layer (3) is preferably 0.16 mm.

7. The method for preparing the stator insulation structure of the traction motor according to claim 1, characterized in that, The composite foil in S2 is formed by using a coating machine to bond aromatic polyamide fiber paper (4), mica paper (6), and polyimide film (7) together with adhesive (5) to form a composite foil for ground insulation.

8. The method for preparing the stator insulation structure of the traction motor according to claim 1, characterized in that, In S2, the thickness of the aromatic polyamide fiber paper (4) in the composite foil is 0.05~0.125mm, the thickness of the mica paper (6) is 0.05~0.125mm, and the thickness of the polyimide film (7) is 0.05~0.125mm.

9. The method for preparing the stator insulation structure of the traction motor according to claim 8, characterized in that, The thickness of the aromatic polyamide fiber paper (4) is preferably 0.05 mm, the thickness of the mica paper (6) is preferably 0.075 mm, and the thickness of the polyimide film (7) is preferably 0.125 mm.

10. The method for preparing the stator insulation structure of the traction motor according to claim 1, characterized in that, When potting the stator in S3, corona-resistant filler is added to the potting resin. The corona-resistant filler is selected from one or more of alumina, silicon dioxide, and boron nitride. The thickness of the epoxy resin potting layer in S3 is 10mm to 50mm.

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