Corona-resistant enameled round wire and preparation method thereof

Abstract

The invention discloses a corona-resistant enameled round wire and a preparation method thereof. The corona-resistant enameled round wire is suitable for electric vehicle motors and comprises a copper conductor and an insulating layer. The insulating layer covers the copper conductor and comprises, from the inside to the outside, a corona-resistant polyamide-imide coating, a corona-resistant special resin coating, a corona-resistant polyimide coating, a corona-resistant modified silicone resin coating, and a corona-resistant polyamide-imide coating.

Description

Technical Field

[0001] The invention belongs to the technical field of corona-resistant enameled round wires, and in particular relates to a corona-resistant enameled round wire suitable for an electric vehicle motor and a preparation method thereof. Background Art

[0002] Introduction to the existing technology With the application of SiC and GaN high-power components, higher technical requirements are put forward for the insulation materials and systems for electric vehicle motors: the frequency is increased and ultra-high frequency occurs, resulting in serious partial discharge and corona corrosion, increasing dielectric loss and heat generation, and accelerating the electrical and thermal aging of insulation; the voltage is increased, the rated voltage is ≥800V, and the high-frequency pulse peak voltage generated is much higher than the existing voltage value. It is urgent to improve the ability of insulation materials and systems to resist high-frequency spike voltages, and have higher partial discharge initial voltage values ​​(Partial Discharge Inception Voltage, PDIV) and partial discharge extinction voltage values ​​(Partial Discharge Extinction Voltage, PDEV).

[0003] As the main insulating material for electric vehicle drive motors, the performance of corona-resistant enameled round wire plays a decisive role in the service life of the drive motor. As the rated voltage of the drive motor increases, the key is to improve the PDIV / PDEV value of the enameled round wire. The existing PDIV value of the corona-resistant enameled round wire is basically around 900V, and the PDEV value is around 500V, which cannot meet the technical requirements for the use of high-voltage drive motors. In addition, with the development of ultra-high frequency drive motors, the corona resistance life of the enameled round wire needs to be further improved. Therefore, it is urgent to develop a corona-resistant enameled round wire with a high PDIV / PDEV value and a preparation method thereof to meet the development and application technical requirements of high-voltage electric vehicle drive motors. Summary of the invention

[0004] (I) Purpose of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a corona-resistant enameled round wire suitable for electric vehicle motors and a preparation method thereof.

[0006] According to one embodiment, the present invention provides a corona-resistant enameled round wire, which is suitable for electric vehicle motors, and the corona-resistant enameled round wire comprises a copper conductor and an insulating layer. The insulating layer covers the copper conductor and comprises, from inside to outside, a first corona-resistant polyamide-imide coating, a corona-resistant special resin coating, a corona-resistant polyimide coating, a corona-resistant modified silicone resin coating, and a second corona-resistant polyamide-imide coating.

[0007] Furthermore, the thickness ratios of the first corona-resistant polyamide-imide coating, the corona-resistant special resin coating, the corona-resistant polyimide coating, the corona-resistant modified silicone resin coating, and the second corona-resistant polyamide-imide coating may be 10%-20%, 10%-25%, 5%-15%, 25%-35%, and 10%-25%, respectively.

[0008] Furthermore, the first corona-resistant polyamide-imide coating, the corona-resistant polyamide-imide coating and the second corona-resistant polyamide-imide coating can be formed by coating with a corona-resistant polyamide-imide / polyimide paint prepared by modifying nano-silicon dioxide, aluminum oxide or a combination thereof.

[0009] Furthermore, the corona-resistant special resin coating can be formed by coating a corona-resistant special resin paint liquid prepared by modifying nano-silicon dioxide, aluminum oxide or a combination thereof.

[0010] Furthermore, the corona-resistant special resin paint liquid can be selected from benzoxazine, polyarylether nitrile, polyarylether nitrile sulfone, polyether sulfone, modified polyetheretherketone, cyanate prepolymer or a combination thereof.

[0011] Furthermore, the corona-resistant modified silicone resin coating is prepared by the following preparation method: adding a certain amount of ethyl orthosilicate or butyl orthosilicate into a reaction bottle, starting stirring, adding 30%-100% of ethyl orthosilicate or butyl orthosilicate, a hydroxyl-containing polysiloxane and 0.01%-0.2% of the total mass fraction of the material, starting to heat to 140°C-150°C, keeping the temperature for reaction, and when no alcohol solvent is distilled out, evacuating to above -0.09MPa, keeping the vacuum for 1-2 hours, cooling and standby; The material is discharged into a sealed homogenizing emulsification kettle, and butyl acetate is added to adjust the solid content to 50%-60%. A certain amount of nano powder is added into the homogenizing emulsification kettle, and the stirring speed is increased to 8000-12000r / min to homogenize and disperse until D50 is less than 100nm, and the jacket cooling water in the kettle is turned on to cool the material temperature in the kettle below 60°C. After cooling to below 40°C, a certain amount of phenolic epoxy resin and accelerator are added and stirred evenly, and a 10000 mesh filter bag is used to filter under pressure into a clean barrel and sealed for packaging.

[0012] According to another embodiment, the present invention provides a method for preparing a corona-resistant enameled round wire, which includes providing a copper conductor and sequentially coating a first corona-resistant polyamide-imide coating, a corona-resistant special resin coating, a corona-resistant polyimide coating, a corona-resistant modified silicone resin coating, and a second corona-resistant polyamide-imide coating on the copper conductor to form an insulating layer to cover the copper conductor to obtain the corona-resistant enameled round wire.

[0013] The above technical solution of the present invention has the following beneficial technical effects:

[0014] Compared with the prior art, the present invention has the following advantages: the PDIV / PDEV value of the enameled round wire is significantly improved, which is more than 20% compared with the conventional technology. The corona resistance life is excellent, and the corona resistance life is greater than 80 hours. The paint film has good high temperature resistance and meets the temperature resistance grade requirements above 220°C. The paint film has excellent adhesion, bending resistance, and good ductility, which is convenient for high slot full rate drive motor winding wire embedding. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. 1 is a schematic cross-sectional view of a corona-resistant enameled round wire according to an embodiment of the present invention.

[0016] Figure 2 The present invention is a flowchart of a method for preparing a corona-resistant modified silicone coating of a corona-resistant enameled round wire according to an embodiment of the present invention.

[0017] Figure 3 The present invention is a flowchart of a method for preparing a corona-resistant modified silicone coating for a corona-resistant enameled round wire according to another embodiment of the present invention.

[0018] Figure 4 The present invention is a flowchart of a method for preparing a corona-resistant modified silicone coating for a corona-resistant enameled round wire according to another embodiment of the present invention.

[0019] Reference numerals:

[0020] 1: Copper conductor; 2: Insulation layer; 3: Corona-resistant polyamide-imide coating; 4: Corona-resistant special resin coating; 5: Corona-resistant polyimide coating; 6: Corona-resistant modified silicone resin coating; 7: Corona-resistant polyamide-imide coating. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0022] The accompanying drawings show schematic diagrams of layer structures according to embodiments of the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clarity. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0023] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as there is no conflict between them.

[0025] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0026] In Example 1, the present invention provides a corona-resistant enameled round wire suitable for electric vehicle motors and having a high PDIV / PDEV value, see Figure 1 , which is a cross-sectional schematic diagram of a corona-resistant enameled round wire provided according to one embodiment of the present invention, such as Figure 1 The corona-resistant enameled round wire shown includes a copper conductor 1 and an insulating layer 2 and is prepared through the following steps.

[0027] In the horizontal enameled round wire production line, a polycrystalline material coating mold is used to prepare corona-resistant enameled round wire, wherein the copper wire annealing temperature is 500℃ / 470℃, the oven curing temperature is 550℃, and the production DV value is 53. The wire gauge is 0.8mm, and the corona-resistant polyamide-imide coating 3, the corona-resistant special resin coating 4, the corona-resistant polyimide coating 5, the corona-resistant modified silicone resin coating 6, and the corona-resistant polyamide-imide coating 7 are sequentially coated to form an insulating layer 2 covering the copper conductor 1, and the coating thickness ratios are 18%, 19%, 11%, 30%, and 22%, respectively, and the total thickness of the paint film on both sides is 0.13mm. The corona-resistant polyamide-imide coating 3, the corona-resistant polyimide coating 5 and the corona-resistant polyamide-imide coating 7 can be coated with a corona-resistant polyamide-imide / polyimide paint prepared by modifying nano-silicon dioxide, aluminum oxide or a combination thereof; the corona-resistant special resin coating 4 can be a nano-silicon dioxide-modified polyethersulfone coating; the preparation method of the corona-resistant modified silicone resin coating 6 is as follows Figure 2 As shown, step S20 can preferably be adding 30%-100% of ethyl orthosilicate or butyl orthosilicate mass fraction of hydroxyl-containing polysiloxane and 0.01%-0.2% of the total mass fraction of the material catalyst (but not limited thereto):

[0028] Step S20: Add 5000 g of tetraethyl orthosilicate into a reaction bottle, start stirring, add 3150 g of a hyperbranched polysiloxane containing a hydroxyl group and 2.5 g of stannous chloride, start heating to 145° C., and when no alcohol solvent is distilled out, evacuate to -0.09 MPa, maintain the vacuum for 2 hours, cool, and set aside;

[0029] Step S22: weigh 3500 g of the above reaction material and discharge it into a sealed homogenizing emulsification kettle, add 3340 g of butyl acetate and stir evenly to adjust the solid content to 50%-60%;

[0030] Step S24: Add 1104g of nano-aluminum trioxide with an average particle size of 50nm into a sealed homogenizing emulsification kettle, start the stirring speed to 8000r / min (start cooling the jacket cooling water in the kettle to ensure that the material temperature in the kettle is lower than 60°C), homogenize and disperse until D50 is less than 100nm, cool to below 40°C, add 1300g of F51 phenolic epoxy resin and 1.44g of boron trifluoride ether and stir evenly, use a 10000 mesh filter bag, filter under pressure into a clean barrel, and seal and package.

[0031] In Example 2, the present invention provides a corona-resistant enameled round wire suitable for electric vehicle motors and having a high PDIV / PDEV value, which is prepared by the following steps.

[0032] In the horizontal enameled round wire production line, a polycrystalline material coating mold is used to prepare corona-resistant enameled round wire, wherein the copper wire annealing temperature is 500℃ / 470℃, the drying oven curing temperature is 550℃, and the production DV value is 53. The wire gauge is 0.8mm, and the corona-resistant polyamide-imide coating 3, the corona-resistant special resin coating 4, the corona-resistant polyimide coating 5, the corona-resistant modified silicone resin coating 6, and the corona-resistant polyamide-imide coating 7 are sequentially coated to form an insulating layer 2 to cover the copper conductor 1, and the coating thickness ratios are 15%, 22%, 13%, 31%, and 19%, respectively, and the total thickness of the paint film on both sides is 0.13mm. The corona-resistant polyamide-imide coating 3, the corona-resistant polyamide-imide coating 5 and the corona-resistant polyamide-imide coating 7 can be coated with a corona-resistant polyamide-imide / polyimide paint prepared by modification of nano-silicon dioxide, aluminum oxide or a combination thereof; the corona-resistant special resin coating 4 can be a nano-aluminum oxide-modified poly(naphthalene biphenyl) ether nitrile sulfone coating; the preparation method of the corona-resistant modified silicone resin coating 6 is as follows: Figure 3 As shown, step S30 can preferably be adding 30%-100% of ethyl orthosilicate or butyl orthosilicate mass fraction of hydroxyl-containing polysiloxane and 0.01%-0.2% of the total mass fraction of the material catalyst (but not limited to this):

[0033] Step S30: Add 6200 g of butyl orthosilicate into a reaction bottle, start stirring, add 4530 g of polyhedral oligomeric silsesquioxane (POSS) structured polysiloxane containing hydroxyl groups and 3.2 g of stannous chloride, start heating to 146° C., and when no alcohol solvent is distilled out, evacuate to -0.09 MPa, maintain vacuum for 2 hours, cool, and set aside;

[0034] Step S32: weigh 5000 g of the above reaction material and discharge it into a sealed homogenizing emulsification kettle, add 4890 g of butyl acetate and stir evenly to adjust the solid content to 50%-60%;

[0035] Step S34: Add 1570g of nanosilica with an average particle size of 45nm into a sealed homogenizing emulsification kettle, start the stirring speed to 8500r / min (start cooling the jacket cooling water in the kettle to ensure that the material temperature in the kettle is lower than 60°C), homogenize and disperse until D50 is less than 100nm, cool to below 40°C, add 2200g of F44 phenolic epoxy resin and 2.16g of boron trifluoride ethylamine, stir evenly, use a 10000 mesh filter bag, filter under pressure into a clean barrel, and seal and package.

[0036] In Example 3, the present invention provides a corona-resistant enameled round wire suitable for electric vehicle motors and having a high PDIV / PDEV value, which is prepared by the following steps.

[0037] In the horizontal enameled round wire production line, a polycrystalline material coating mold is used to prepare corona-resistant enameled round wire, wherein the copper wire annealing temperature is 500℃ / 470℃, the drying oven curing temperature is 550℃, and the production DV value is 53. The wire gauge is 0.8mm, and the corona-resistant polyamide-imide coating 3, the corona-resistant special resin coating 4, the corona-resistant polyimide coating 5, the corona-resistant modified silicone resin coating 6, and the corona-resistant polyamide-imide coating 7 are sequentially coated to form an insulating layer 2 covering the copper conductor 1, and the coating thickness ratios are 16%, 23%, 12%, 30%, and 19%, respectively, and the total thickness of the paint film on both sides is 0.13mm. The corona-resistant polyamide-imide coating 3, the corona-resistant polyamide-imide coating 5 and the corona-resistant polyamide-imide coating 7 can be coated with a corona-resistant polyamide-imide / polyimide paint prepared by modifying nano-silicon dioxide, aluminum oxide or a combination thereof; the corona-resistant special resin coating 4 is a polyethersulfone coating modified by nano-aluminum oxide; the preparation method of the corona-resistant modified silicone resin coating 6 is as follows Figure 4 As shown, step S40 can preferably be adding 30%-100% of ethyl orthosilicate or butyl orthosilicate mass fraction of hydroxyl-containing polysiloxane and 0.01%-0.2% of the total mass fraction of the material catalyst (but not limited to this):

[0038] Step S40: Add 4500 g of tetraethyl orthosilicate into a reaction bottle, start stirring, add 3600 g of a hyperbranched polysiloxane containing a hydroxyl group and 2.3 g of stannous chloride, start heating to 150° C., and when no alcohol solvent is distilled out, evacuate to -0.09 MPa, maintain the vacuum for 2 hours, cool, and set aside;

[0039] Step S42: weigh 3000 g of the above reaction material and discharge it into a sealed homogenizing emulsification kettle, add 2172 g of butyl acetate and stir evenly to adjust the solid content to 50%-60%;

[0040] Step S44: Add 890 g of nanosilica with an average particle size of 52 nm into a sealed homogenizing emulsification kettle, start the stirring speed to 9500 r / min (start cooling the jacket cooling water in the kettle to ensure that the material temperature in the kettle is lower than 60°C), homogenize and disperse until D50 is less than 100 nm, cool to below 40°C, add 1280 g of F51 phenolic epoxy resin and 1.2 g of epoxy resin curing accelerator (DMP-30), stir evenly, use a 10000 mesh filter bag, filter under pressure into a clean barrel, and seal and package.

[0041] In comparative example 1, a corona-resistant enameled round wire was prepared by using a polycrystalline material coating mold on a horizontal enameled round wire production line, wherein the copper wire annealing temperature was 500°C / 470°C, the oven curing temperature was 550°C, and the production DV value was 53. The wire gauge was 0.8 mm, and the corona-resistant polyesterimide coating and the polyamideimide coating were coated in sequence, with the coating thickness ratios of 85% and 15% respectively (conventional composite coating corona-resistant enameled round wire on the market), and the total thickness of the paint film on both sides was 0.13 mm.

[0042] In Comparative Example 2, a corona-resistant enameled round wire was prepared using a polycrystalline material coating mold on a horizontal enameled round wire production line, wherein the copper wire annealing temperature was 500°C / 470°C, the oven curing temperature was 550°C, and the production DV value was 53. The wire gauge was 0.8 mm, and a corona-resistant polyamide-imide single coating (corona-resistant single-coating polyamide-imide paint coating) was applied, and the total thickness of the paint film on both sides was 0.13 mm.

[0043] Various properties of the corona resistant enameled round wires of Examples 1-3 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0044] Table 1 Comparison of the performance of the impregnated resins of Examples 1-3 and Comparative Examples 1-2

[0045]

[0046]

[0047] Among them, for the PDIV value test, the background noise is <5pc; the corona resistance life test conditions are: testing on a high-frequency pulse test, with a square wave waveform, a temperature of 155°C, a frequency of 20kHz, a pulse time of 100ns, and a voltage of 3000V.

[0048] Due to the implementation of the above-mentioned embodiments 1-3, the present invention has the following advantages compared with the prior art: the PDIV / PDEV value of the enameled round wire is significantly improved, which is more than 20% higher than that of the conventional technology. The corona resistance life is excellent, and the corona resistance life is greater than 80 hours. The paint film has good high temperature resistance and meets the temperature resistance grade requirements above 220°C. The paint film has excellent adhesion, bending resistance, and good ductility, which is convenient for high slot full rate drive motor winding embedding.

[0049] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A corona-resistant enameled round wire, which is suitable for electric vehicle motors, and the corona-resistant enameled round wire comprises: a copper conductor; and an insulating layer, which covers the copper conductor and comprises, from the inside to the outside, a first corona-resistant polyamide-imide coating, a corona-resistant special resin coating, a corona-resistant polyimide coating, a corona-resistant modified silicone resin coating, and a second corona-resistant polyamide-imide coating, The corona-resistant special resin coating is formed by coating a corona-resistant special resin paint liquid prepared by modifying nano-silicon dioxide, aluminum oxide or a combination thereof; The corona-resistant special resin paint liquid is selected from benzoxazine, polyarylether nitrile, polyarylether nitrile sulfone, polyether sulfone, modified polyetheretherketone, cyanate prepolymer or a combination thereof; The corona-resistant modified silicone resin coating is prepared by the following preparation method: Add a certain amount of ethyl orthosilicate or butyl orthosilicate into a reaction bottle, start stirring, add 30%-100% of hydroxyl-containing polysiloxane by mass fraction of ethyl orthosilicate or butyl orthosilicate and 0.01%-0.2% of the total mass fraction of the catalyst, start heating to 140°C-150°C, keep the temperature for reaction, and when no alcohol solvent is distilled out, evacuate to above -0.09MPa, keep the vacuum for 1-2 hours, cool and set aside; Discharging the above materials into a sealed homogenizing emulsifying kettle, adding butyl acetate to adjust the solid content to 50%-60%; and Add a certain amount of nano powder into the homogenizing emulsification kettle, start the stirring speed to 8000-12000r / min to disperse homogenously until D50 is less than 100nm, and start the cooling water cooling in the jacket of the kettle to make the temperature of the material in the kettle lower than 60℃. After cooling to below 40℃, add a certain amount of phenolic epoxy resin and accelerator and stir evenly. Use a 10000 mesh filter bag to filter under pressure into a clean barrel and seal it.

2. The corona-resistant enameled round wire according to claim 1, wherein the thickness ratios of the first corona-resistant polyamide-imide coating, the corona-resistant special resin coating, the corona-resistant polyimide coating, the corona-resistant modified silicone resin coating, and the second corona-resistant polyamide-imide coating are 10%-20%, 10%-25%, 5%-15%, 25%-35%, and 10%-25%, respectively.

3. The corona-resistant enameled round wire according to claim 1 or 2, wherein the first corona-resistant polyamide-imide coating, the corona-resistant polyimide coating and the second corona-resistant polyamide-imide coating are coated with a corona-resistant polyamide-imide / polyimide paint prepared by modifying nanosilicon dioxide, aluminum oxide or a combination thereof.

4. A method for preparing a corona-resistant enameled round wire, comprising: providing a copper conductor; and A first corona-resistant polyamide-imide coating, a corona-resistant special resin coating, a corona-resistant polyimide coating, a corona-resistant modified silicone resin coating, and a second corona-resistant polyamide-imide coating are sequentially coated on the copper conductor to form an insulating layer to cover the copper conductor to obtain the corona-resistant enameled round wire; The corona-resistant special resin coating is formed by coating a corona-resistant special resin paint liquid prepared by modifying nano-silicon dioxide, aluminum oxide or a combination thereof; The corona-resistant special resin paint liquid is selected from benzoxazine, polyarylether nitrile, polyarylether nitrile sulfone, polyether sulfone, modified polyetheretherketone, cyanate prepolymer or a combination thereof; The corona-resistant modified silicone resin coating is prepared by the following preparation method: Add a certain amount of ethyl orthosilicate or butyl orthosilicate into the reaction bottle, start stirring, add a certain amount of polysiloxane containing hydroxyl groups and catalyst, start heating to 140℃-150℃, keep warm for reaction, and when no alcohol solvent is distilled out, evacuate to above -0.09MPa, keep vacuum for 1-2 hours, cool and set aside; Discharging the above materials into a sealed homogenizing emulsifying kettle, adding butyl acetate to adjust the solid content to 50%-60%; and Add a certain amount of nano powder into the homogenizing emulsification kettle, start the stirring speed to 8000-12000r / min to disperse homogenously until D50 is less than 100nm, and start the cooling water cooling in the jacket of the kettle to make the temperature of the material in the kettle lower than 60℃. After cooling to below 40℃, add a certain amount of phenolic epoxy resin and accelerator and stir evenly. Use a 10000 mesh filter bag to filter under pressure into a clean barrel and seal it.

5. The method for preparing a corona-resistant enameled round wire according to claim 4, wherein the thickness ratios of the first corona-resistant polyamide-imide coating, the corona-resistant special resin coating, the corona-resistant polyimide coating, the corona-resistant modified silicone resin coating, and the second corona-resistant polyamide-imide coating are 10%-20%, 10%-25%, 5%-15%, 25%-35%, and 10%-25%, respectively.

6. The method for preparing a corona-resistant enameled round wire according to claim 4 or 5, wherein the first corona-resistant polyamide-imide coating, the corona-resistant polyimide coating and the second corona-resistant polyamide-imide coating are coated with a corona-resistant polyamide-imide / polyimide paint prepared by modifying nanosilicon dioxide, aluminum oxide or a combination thereof.

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