KR102774324B1 - Stator winding with high waterlogging resistance and insulation performance and manufacturing method thereof - Google Patents

Abstract

The stator winding having excellent insulation performance according to the present invention comprises a stator coil and an insulating layer formed on the stator coil, wherein the insulating layer is characterized in that a prepreg tape including: a glass wool tape; a first epoxy composition layer formed on the glass wool tape and containing mica; and a second epoxy composition layer formed on the first epoxy composition layer is formed by spirally winding and curing.

Description

{Stator winding with high waterlogging resistance and insulation performance and manufacturing method thereof}

The present invention relates to a stator winding having excellent immersion resistance and insulation performance and a method for manufacturing the same.

A power plant is a facility that converts mechanical energy produced from energy sources such as thermal power, nuclear power, and hydro power into electrical energy. A generator basically generates electric power by using electromagnetic induction. Such a generator typically comprises a stator assembly formed by winding coils around a stator core, and a rotor located within the stator. A permanent magnet or electromagnet is placed on the rotor so that electrical energy is generated by the rotation of the rotor, and the generated electrical energy can be transmitted to the outside through the stator coil.

These generators generate frictional heat due to the rotation of the rotor, are placed in a high-voltage environment generated by the generator, and are placed in an environment that continuously absorbs vibrations and shocks generated by the physical movement of rotation. Accordingly, it is common to use a stator coil that has an insulating coating formed on it.

It is obvious that the insulating coating of the stator requires high insulation, and it is required to exhibit significantly higher durability and mechanical strength compared to the insulating coating used under normal conditions. In addition, since most insulating materials do not have high resistance to moisture penetration, if the temperature difference between the inside and outside is large or if water is immersed, the insulation of the generator winding deteriorates rapidly and it may be impossible to restore the insulation performance to the original state. Therefore, it is necessary to develop an insulating coating that does not deteriorate the insulation performance of the winding even in environments such as high humidity or flooding, or that quickly restores to the original state if a slight deterioration occurs.

Republic of Korea Patent Publication No. 10-2268610 Republic of Korea Patent Publication No. 10-2015-0027714 Japanese Patent Publication No. 2023-017570

An object of the present invention is to provide a stator winding having excellent insulation performance.

Another object of the present invention is to provide a stator winding having excellent submergence resistance.

The stator winding having excellent insulation performance according to the present invention comprises a stator coil and an insulating layer formed on the stator coil, wherein the insulating layer is characterized in that a prepreg tape including: a glass wool tape; a first epoxy composition layer formed on the glass wool tape and containing mica; and a second epoxy composition layer formed on the first epoxy composition layer is formed by spirally winding and curing.

In a stator winding having excellent insulation performance according to one embodiment of the present invention, the glass wool may have a thickness of 0.05 to 0.5 mm.

In a stator winding having excellent insulation performance according to one embodiment of the present invention, the first epoxy composition layer may be characterized by including bisphenol A epoxy resin.

In a stator winding having excellent insulation performance according to one embodiment of the present invention, the first epoxy composition layer may be characterized by including polyvinyl formal.

In a stator winding having excellent insulation performance according to one embodiment of the present invention, the mica may be characterized in that it is surface-treated with a silane having an amino group at a terminal.

In a stator winding having excellent insulation performance according to one embodiment of the present invention, the stator coil may be characterized in that both ends are bent.

The present invention also provides a method for manufacturing a stator winding having excellent insulation performance, and the method for manufacturing a stator winding according to the present invention comprises: a first step of treating the surface of a glass wool tape with a silane compound containing a terminal amino group;

A second step of coating a first epoxy composition containing mica on glass wool after the first step and partially curing it;

A third step of manufacturing a prepreg tape by coating a second epoxy composition on the first epoxy composition layer after the second step and partially curing it;

A fourth step of winding the prepreg tape onto a stator coil and hot pressing and curing it is included.

In a method for manufacturing a stator winding having excellent insulation performance according to one embodiment of the present invention, it may be characterized in that the partial curing in the second and third steps is a step of processing at 90 to 120° C. for 20 to 100 minutes.

In a method for manufacturing a stator winding having excellent insulation performance according to one embodiment of the present invention, it may be characterized in that the curing agent included in the first epoxy composition and the second epoxy composition is dicyandiamide.

In a method for manufacturing a stator winding having excellent insulation performance according to one embodiment of the present invention, the fourth step may be characterized in that it is performed at 800 to 1,300 psi and 130 to 160°C.

The stator winding according to the present invention has excellent insulation performance, including a stator coil and an insulating layer formed on the stator coil, wherein the insulating layer is formed by spirally winding and curing a prepreg tape including a glass wool tape; a first epoxy composition layer formed on the glass wool tape and containing mica; and a second epoxy composition layer formed on the first epoxy composition layer, thereby having the advantages of excellent insulation performance and water resistance.

FIG. 1 is a schematic diagram illustrating the cross-sectional structure of an epoxy prepreg in a stator winding according to one embodiment of the present invention.
FIG. 2 illustrates a form in which an epoxy prepreg is wound around a stator coil before hot press treatment in a stator winding according to one embodiment of the present invention.
FIG. 3 schematically illustrates a hot press process in a method for manufacturing a stator winding according to one embodiment of the present invention.
FIG. 4 illustrates a process for immersion testing a stator winding according to one embodiment of the present invention.

The advantages and features of the embodiments of the present invention, and the methods for achieving them, will become clear with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and the present embodiments are provided only to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In describing embodiments of the present invention, if it is judged that a detailed description of a known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of functions in the embodiments of the present invention, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification.

The stator winding having excellent insulation performance according to the present invention includes a stator coil and an insulation layer formed on the stator coil,

The above insulating layer

A glass wool tape; a first epoxy composition layer formed on the glass wool tape and containing mica; a second epoxy composition layer formed on the first epoxy composition layer; characterized in that the prepreg tape is formed by being spirally wound and cured.

The stator winding according to the present invention has the advantage of excellent insulation performance as well as excellent resistance to water immersion by including an insulating layer formed by winding an epoxy prepreg having such a multilayer structure. Specifically, the epoxy prepreg tape according to the present invention has the same structure as Fig. 1, and includes a structure in which a glass wool tape (10) is formed in the center, a first epoxy composition layer (20) is formed on both sides of the glass wool tape, and a second epoxy composition layer (30) is formed on both sides of the first epoxy composition layer, and preferably, it may include a shape in which both ends are bent as in Fig. 2.

At this time, the glass wool tape can satisfy a thickness of 0.05 to 0.5 mm, preferably 0.1 to 0.3 mm. If the thickness of the glass wool is thin, the effect of improving the mechanical strength and the insulation effect may be reduced, and if the thickness of the glass wool is thick, the problem of difficulty in winding the stator coil may occur.

The first epoxy composition layer is formed of a first epoxy composition, and the first epoxy composition may include mica, bisphenol A epoxy resin, polyvinyl foam, and a curing agent. The first epoxy composition is described in detail below.

The first epoxy resin may include bisphenol A epoxy resin as a base resin, and by including the bisphenol A epoxy resin, a stable insulating layer can be maintained with high bonding strength with the stator coil and the second epoxy composition layer, and excellent dispersibility of mica can be achieved, thereby exhibiting excellent insulating effects. The bisphenol A epoxy resin used in the first epoxy resin can satisfy an epoxy equivalent weight (EEW) of 1700 to 2100 g/eq.

The first epoxy composition includes polyvinyl foam, and by including such polyvinyl foam, the bonding strength with the stator coil and the second composition layer can be maintained with improved adhesiveness. At this time, the polyvinyl foam can be used having a weight average molecular weight of 50,000 to 100,000, and preferably 55,000 to 80,000, and the polyvinyl foam can be included in an amount of 1 to 5 parts by weight, and preferably 2 to 4.5 parts by weight with respect to 100 parts by weight of the bisphenol A epoxy resin, and by satisfying such a range, excellent bonding strength can be exhibited while also securing excellent mechanical durability.

The first epoxy composition includes a dicyandiamide solution, and dicyandiamide is applied as a hardener to form a prepreg tape in terms of a manufacturing method, and then the prepreg tape is hardened to finally form an insulating layer. Dicyandiamide can be preferably introduced in a form dissolved in a solvent, and the dicyandiamide solution can contain 3 to 6 wt% of dicyandiamide. The first epoxy composition can contain 5 to 10 wt%, preferably 6 to 9 wt%, of the dicyandiamide solution relative to 100 wt% of bisphenol A epoxy resin. At this time, the solvent used in the dicyandiamide solution can include one or two or more selected from benzene, toluene, xylene, and ethylbenzene.

The first epoxy composition may further include an amine-based curing accelerator as an epoxy composition, and preferably, the curing accelerator may be benzyl dimethyl amine. By including such a curing accelerator, rapid curing is possible, enabling rapid production of a stator winding. The first epoxy composition may include 0.5 to 1.5 parts by weight of the curing accelerator relative to 100 parts by weight of the bisphenol A epoxy resin, thereby exhibiting an excellent curing acceleration effect while preventing deterioration of mechanical strength and physical properties.

The first epoxy composition according to the present invention includes mica, and preferably, the mica may be surface-treated with a silane having an amino group at its terminal. The surface treatment may be performed by dispersing mica in a solvent, adding a surface treatment agent and a pH regulator, and irradiating ultrasonic waves. Preferably, the solvent may be a mixed solvent of water and an alcohol having 3 or fewer carbon atoms, and the surface treatment agent may be at least one selected from 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane. The pH regulator is preferably an acidic substance that can adjust the pH of the reactor to 5 to 6.5 during the surface treatment process. In addition, the mica may have an average particle diameter of 100 to 200 ㎛, and by using mica having such an average particle diameter, the mica can be uniformly dispersed in the first epoxy composition layer and excellent insulation can be secured. The first epoxy composition may contain 180 to 220 parts by weight of mica relative to 100 parts by weight of bisphenol A epoxy resin, and excellent immersion stability can be secured within this range. If the content of mica is low, it is difficult to secure insulation, and if the content of mica is high, it may cause a decrease in adhesion.

More specifically, the first epoxy composition may be in a form in which the above-described bisphenol A epoxy resin, polyvinyl foam, dicyandiamide curing agent, amine curing accelerator, and mica are mixed and dispersed with an aromatic solvent. At this time, the aromatic solvent may be mixed so that the solid content of the entire composition is about 55 to 75 wt%. In this range, a first composition layer may be formed to a certain thickness or more, thereby forming a solid first composition layer. Specifically, the aromatic solvent may include one or two or more selected from benzene, toluene, xylene, and ethylbenzene.

In a stator winding having excellent insulation performance according to one embodiment of the present invention, the prepreg tape includes a second epoxy composition layer. The second epoxy composition layer may be formed of a second epoxy composition, and the second epoxy composition will be described in detail below. The second epoxy composition may include a phenol novolac epoxy resin as a base resin, and may secure excellent heat resistance of the surface of the stator winding due to the high surface density and excellent heat resistance by including the phenol novolac resin. Specifically, the phenol novolac resin may satisfy an epoxy equivalent of 160 to 190 g/eq.

The second epoxy composition can also secure excellent bonding strength with the first epoxy composition layer by including polyvinyl foam, and the polyvinyl foam included in the second epoxy composition can be the same as or similar to that of the first epoxy composition. The second epoxy composition can contain 1.2 to 2.5 parts by weight of polyvinyl foam with respect to 100 parts by weight of phenol novolac epoxy resin, and by satisfying this range, excellent heat resistance can be secured while also achieving an excellent adhesion enhancement effect by mixing in polyvinyl foam.

In addition, the second epoxy composition may also include a dicyandiamide solution and benzyl dimethylamine as an amine curing accelerator. The dicyandiamide solution may be included in an amount of 3 to 7 parts by weight based on 100 parts by weight of the phenol novolac epoxy resin, and the curing accelerator may be included in an amount of 0.3 to 0.8 parts by weight based on 100 parts by weight of the phenol novolac epoxy resin. Excellent curing properties may be exhibited by satisfying these ranges.

More specifically, the second epoxy composition may be in a form in which the above-described phenol novolac epoxy resin, polyvinyl foam, dicyandiamide curing agent, and amine curing accelerator are mixed and dispersed with an aromatic solvent. At this time, the aromatic solvent may be mixed so that the solid content of the entire composition is about 55 to 75 wt%. In this range, a second composition layer may be formed to a certain thickness or more, thereby forming a solid second composition layer. Specifically, the aromatic solvent may include one or two or more selected from benzene, toluene, xylene, and ethylbenzene.

The present invention also provides a method for manufacturing a stator winding having excellent insulation performance, and the method for manufacturing a stator winding according to the present invention comprises: a first step of surface-treating the surface of a glass wool tape with a silane compound containing a terminal amino group;

A second step of coating a first epoxy composition containing mica on glass wool after the first step and partially curing it;

A third step of manufacturing a prepreg tape by coating a second epoxy composition on the first epoxy composition layer after the second step and partially curing it;

A fourth step of winding the prepreg tape onto a stator coil and hot pressing and curing it is included.

The first step is a step of treating the surface of the glass wool tape with a silane compound having a terminal amino group. Specifically, the first step can be performed by spraying a silane compound solution having a terminal amino group onto the surface of the glass wool tape and drying it, or immersing the glass wool tape in a silane compound solution having a terminal amino group and then drying it. Through this surface treatment of the surface of the glass wool tape, the bonding strength with the resin included in the first epoxy composition is significantly improved, so that excellent bonding strength can be maintained even in a harsh environment, which has the advantage of. At this time, the silane compound having a terminal amino group can use at least one selected from 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane.

The second step is a step of coating a first epoxy composition containing mica on the glass wool to the surface of which aminosilane has been introduced through the first step, and partially curing the same. The first epoxy composition may be characterized by having the composition described above. The coating of the first epoxy composition may use various coating methods, but preferably, a roll-to-roll coating method may be used. By using the roll-to-roll coating method, a first epoxy coating layer having a thickness of a certain level or more may be formed, thereby ensuring excellent insulation and durability. After coating the first epoxy composition, the surface may be treated at 90 to 120° C., preferably 95 to 110° C., for 20 to 100 minutes, preferably 25 to 60 minutes, through which the first epoxy composition may be manufactured in a semi-cured state, and a second epoxy composition layer may be formed on the first epoxy composition layer.

The third step is a step of coating a second epoxy composition on the first epoxy composition layer formed in the second step and partially curing it. Here, the second epoxy composition may use the second epoxy composition described above, and a method identical or similar to the heat treatment for coating and partially curing the first epoxy composition may be used.

The fourth step is a step of winding the prepreg tape manufactured through the first to third steps around a stator coil and compressing and curing the same. At this time, the winding around the stator coil can be done without limitation if a means or method that completely covers the stator coil is used, and preferably, the prepreg tape can be wound in multiple layers. The hot press compression and curing of the fourth step can be performed at a pressure of 800 to 1,300 psi, preferably 900 to 1,200 psi, and a temperature range of 130 to 160°C, preferably 135 to 155°C, thereby finally forming an insulating layer on the stator coil. This insulating layer can have a thickness of 0.5 to 5 mm, and within this range, excellent durability and insulation can be secured while preventing performance degradation of the generator.

Hereinafter, the present invention will be specifically described by examples and comparative examples. The examples below are only intended to help understanding the present invention, and the scope of the present invention is not limited by the examples below.

[Manufacturing Example 1]

1. Preparation of the first epoxy composition

A first epoxy composition was prepared by adding 50 g of bisphenol A epoxy resin having an epoxy equivalent weight (EEW) of about 1900 g/eq, 1.5 g of polyvinyl foam having a weight average molecular weight of about 65,000, 5 g of a dicyandiamide solution (toluene solvent, 4 wt%) as a hardener, 0.5 g of benzyldimethylamine, and 100 g of surface-modified mica to toluene. At this time, the first epoxy composition was adjusted to have a solid content of 60 wt%.

At this time, surface-modified mica was used by adding 15 g of mica with an average particle size of 150 ㎛ and 1 g of 3-aminopropyl triethoxysilane to a mixed solvent of water and ethanol in a weight ratio of 1:1, then adding acetic acid until the pH became 6, ultrasonicating for 5 hours, and drying.

2. Preparation of the second epoxy composition

A second epoxy composition was prepared by adding 80 g of a phenol novolac epoxy resin having an epoxy equivalent of about 175 g/eq, 1.5 g of polyvinyl foam having a weight average molecular weight of about 65,000, 4 g of a dicyandiamide solution (toluene solvent, 4 wt%) as a hardener, and 0.5 g of benzyldimethylamine to toluene. At this time, the solid content of the second epoxy composition was set to be 60 wt%.

3. Manufacturing of prepreg tapes and stator windings

A glass wool tape modifier solution was prepared by adding 5 g of trimethoxy-3-aminopropyl silane to 100 g of a mixed solvent containing water and ethanol in a 1:1 weight ratio. A glass wool tape having a thickness of 0.2 mm and a width of 25 mm was prepared, and then impregnated in the modifier solution and ultrasonically treated for 2 hours. Thereafter, the glass wool tape was dried at room temperature and pressure for more than 12 hours to prepare a surface-treated glass wool tape.

A first epoxy composition was coated on both sides of a surface-treated glass wool tape through a roll-to-roll process, and then treated at 100°C for 30 minutes to form a semi-cured state. After cooling to room temperature, a second epoxy composition was coated on both sides of the glass wool tape coated with the first epoxy composition through a roll-to-roll process, treated at 100°C for 30 minutes, and cooled to room temperature to finally manufacture a prepreg tape.

The manufactured prepreg tape was spirally wound around the entire surface of the stator coil, and then heated to 150°C while applying pressure of 1000 psi using a hot press jig manufactured in the shape of a stator coil to harden the partially cured first epoxy composition and the second epoxy composition, thereby finally manufacturing a stator winding.

[Manufacturing Example 2]

The stator winding was manufactured using the same method as Manufacturing Example 1, except that the mica was introduced without any separate treatment.

[Comparative Example 1]

A prepreg tape was manufactured by the same method as Manufacturing Example 1, but by repeatedly coating only the first epoxy composition twice without using the second epoxy composition, and this was applied to a stator coil to manufacture a stator winding.

[Comparative Example 2]

A prepreg tape was manufactured by the same method as Manufacturing Example 1, but without using the first epoxy composition, only the second epoxy composition was repeatedly coated twice to manufacture a prepreg tape, which was then applied to a stator coil to manufacture a stator winding.

Insulation performance evaluation of stator windings

The insulation performance of the stator windings manufactured in each Manufacturing Example and Comparative Example was evaluated, and the results are shown in Table 1. Their evaluation methods were also based on the methods described in Table 1. In addition, the partial discharge test was based on the phase voltage, and in the case of the immersion test, the manufactured stator windings were immersed in water for 1 month, and then the 1-minute insulation resistance test, AC withstand voltage test, dielectric loss tangent test, and partial discharge test were performed. If the result value showed a change of 5% or less compared to the initial value, it was marked with ◎, if it showed a change of more than 5% but less than 7%, it was marked with ○, and if it showed a change of more than 7% but less than 10%, it was marked with △.

Test name 1 minute insulation resistance/PI AC withstand voltage Insulation breakdown voltage Genetic linkage Partial Welding Immersion test Evaluation method IEEE 43 IEC 60034-1 ASTM D 149 IEC 60034-27-3
IEEE 286 IEC 60034-27-1
IEEE 1434 - Manufacturing example 1 10,000MΩ
/6.0 1.7×(2E+1)kV 6 E 2% 5,000 pC ◎ Manufacturing example 2 8,500MΩ
/5.0 1.4×(2E+1)kV 5 E 2.2% 8,000 pC ◎ Comparative Example 1 11,000MΩ
/6.5 1.8×(2E+1)kV 6 E 2% 4,000 pC △ Comparative Example 2 7,000MΩ
/5.0 1.1×(2E+1)kV 5 E 2.3% 10,000 pC ◎

Referring to Table 1, when only the first epoxy composition containing mica was repeatedly coated twice, as in Comparative Example 1, it can be confirmed that excellent insulating performance was exhibited before immersion, but a rapid decrease in performance occurred after the immersion test. When only the second epoxy composition not containing mica was repeatedly coated twice, as in Comparative Example 2, it can be confirmed that the insulating performance was relatively low, whereas Manufacturing Examples 1 and 2 exhibited excellent insulating performance and immersion resistance performance, and furthermore, it can be confirmed that Manufacturing Example 1, in which mica was modified, exhibited the best insulating performance and immersion resistance performance.

10 glass wool
20. 1st layer of epoxy composition
30 Second epoxy composition layer
100 prepreg tape
200 stator coils
300 stator windings
400 hot press mold
410 upper mold
420 lower mold

Claims (10)

It comprises a stator coil and an insulating layer formed on the stator coil,
The above insulating layer
A prepreg tape comprising: a glass wool tape; a first epoxy composition layer formed on the glass wool tape and containing mica; a second epoxy composition layer formed on the first epoxy composition layer; formed by spirally winding and curing,
A stator winding having excellent insulating performance, characterized in that the first epoxy composition layer comprises polyvinyl formal.
In paragraph 1,
A stator winding having excellent insulating performance, characterized in that the glass wool has a thickness of 0.05 to 0.5 mm.
In paragraph 1,
A stator winding having excellent insulating performance, characterized in that the first epoxy composition layer comprises bisphenol A epoxy resin.
delete In paragraph 1,
A stator winding having excellent insulating performance, characterized in that the above mica is surface-treated with a silane containing an amino group at the terminal.
In paragraph 1,
The above stator coil is a stator winding having excellent insulation performance, characterized in that both ends are bent.
A first step of treating the surface of a glass wool tape with a silane compound containing a terminal amino group;
A second step of coating a first epoxy composition containing mica on glass wool after the first step and partially curing it;
A third step of manufacturing a prepreg tape by coating a second epoxy composition on the first epoxy composition layer after the second step and partially curing it;
A method for manufacturing a stator winding having excellent insulation performance, comprising a fourth step of winding the prepreg tape onto a stator coil and performing hot press compression and curing.
In Article 7,
A method for manufacturing a stator winding having excellent insulation performance, characterized in that the second and third stages of hardening are performed at a temperature of 90 to 120° C. for 20 to 100 minutes.
In Article 7,
A method for manufacturing a stator winding having excellent insulating performance, characterized in that the curing agent included in the first epoxy composition and the second epoxy composition is dicyandiamide.
In Article 7,
A method for manufacturing a stator winding having excellent insulation performance, characterized in that the fourth step is performed at 800 to 1,300 psi and 130 to 160°C.