KR102377602B1 - Flat winding wire having corona resistance - Google Patents

Abstract

The present invention relates to corona-resistant square windings. Specifically, the present invention relates to a corona-resistant square winding having an insulating coating layer that not only has excellent corona resistance but also excellent adhesion and flexibility.

Description

Flat winding wire having corona resistance}

The present invention relates to corona-resistant square windings. Specifically, the present invention relates to a corona-resistant square winding having an insulating coating layer that not only has excellent corona resistance but also excellent adhesion and flexibility.

In general, enamel wire is an insulated wire that is wound in the form of a coil inside an electric device and plays the role of mutually converting electrical energy and mechanical energy through a magnetic energy conversion process.

These enamel wires generally consist of a conductor wire such as copper and an insulating coating layer surrounding it. Additionally, the insulating coating layer of the enamel wire is formed by coating an insulating varnish composed of an organic solvent and a polymer resin on the surface of the conductor and drying and curing it at a high temperature of 400°C or higher.

The enamel wire is currently used in various fields such as heavy electrical products, automobile parts, home appliances, medical devices, and core materials in the aerospace industry. However, when applied to motors in a high-voltage environment, if the corona resistance properties are insufficient, an insulating coating layer is formed. A partial discharge occurs due to the corona phenomenon, in which a microscopic gap is created between the insulating films or inside the insulating film, and the electric field is concentrated in that area.

Collision of charged particles generated by the corona discharge causes heat generation and decomposition of the insulating coating layer, resulting in insulation breakdown. Recently, due to energy conservation, systems using inverter motors, etc. have been used, and the number of cases of insulation breakdown due to inverter surge in these systems is increasing. It has been proven that the insulation breakdown caused by the inverter surge is also due to the overvoltage caused by the inverter surge causing corona discharge.

In order to provide sufficient corona resistance to such enamel wire, an enamel wire is known in which inorganic insulating particles such as silica and titanium dioxide are added to the resin forming the insulating coating layer. In addition to providing corona resistance to the enamel wire, the inorganic insulating particles contribute to improving thermal conductivity, reducing thermal expansion, and improving strength.

However, as the content of the inorganic insulating particles increases, the corona resistance improves, but there is a problem in that the adhesion between the conductor and the insulating coating layer and the flexibility of the insulating coating layer deteriorate. Therefore, when an enamel wire containing a large amount of inorganic insulating particles in the insulating coating layer is applied to the coil of an electric device, numerous cracks occur in the insulating coating layer, and as a result, the original purpose of corona resistance cannot be achieved.

Meanwhile, the enamel wire is divided into round enamel wire and square enamel wire depending on the shape of the cross section. Compared to the round enamel wire, the square enamel wire can reduce empty space when wound and can be wound in an aligned manner, thereby increasing electrical conversion efficiency. It has the advantage of being able to increase and reduce operating noise. Due to these advantages, the demand for square enameled wire has recently been increasing significantly.

However, in the case of a square enamel wire, the electric field is structurally concentrated at the edge of the conductor, and when an insulating coating layer is formed on the outer periphery of the conductor, the insulating coating layer at the edge is formed to be relatively thinner than the insulating coating layer at the flat portion. Since it is difficult to control the uniform thickness of the insulating coating layer, such as the longer the length of the flat part, the thinner the coating layer becomes, this can significantly reduce the corona resistance, so the insulating coating layer that can achieve the desired corona resistance There is an extremely difficult problem in designing the thickness, and the problem is even more serious when the insulating coating layer is formed by stacking two or more types of coating layers with different viscosity, surface tension, etc.

Therefore, through precise thickness design of the insulating coating layer, an insulating coating layer that not only has excellent corona resistance but also has excellent adhesion and flexibility even when two or more types of coating layers with different viscosity and surface tension are laminated. There is an urgent need for corona-resistant flat angle windings.

The purpose of the present invention is to provide a rectangular winding having an insulating coating layer with excellent corona resistance.

Additionally, the purpose of the present invention is to provide a rectangular winding having an insulating coating layer with excellent corona resistance and excellent adhesion and flexibility in a trade-off relationship.

In order to solve the above problems, the present invention,

A corona-resistant square winding, comprising a conductor wire having a cross-sectional shape including a flat angle portion and a curved portion, and an insulating coating layer surrounding the conductor wire, wherein the insulating coating layer is coated with one or more anti-surge varnishes containing a polymer resin and nano inorganic particles. It includes one or more insulating varnish layers containing a layer and a polymer resin, and the thickness increase rate of the anti-surge varnish layer defined by Equation 1 below is greater than the thickness increase rate of the insulating varnish layer defined by Equation 1 below. Features a corona-resistant, square-angle winding.

[Equation 1]

Thickness increase rate (%) = {(layer thickness at bent part - layer thickness at flat part)/layer thickness at flat part} ×100

In Equation 1 above,

The layer thickness at the bend is the average value of the thickness of the anti-surge varnish layer or the insulating varnish layer measured at each bend of the conductor wire,

The layer thickness in the flat part is the average value of the thickness of the anti-surge varnish layer or the insulating varnish layer measured in each flat part of the conductor wire.

Here, a corona-resistant square winding is provided, characterized in that the thickness increase rate of the anti-surge varnish layer is 10 to 50%.

A corona-resistant square winding, characterized in that the average thickness of the insulating coating layer is 70 to 120 ㎛.

In addition, based on the average thickness of the insulating coating layer, the average thickness of the anti-surge varnish layer accounts for 30 to 50%, and the average thickness of the insulating varnish layer accounts for 50 to 70%. Provides a square winding.

Here, the insulating varnish layer includes a first insulating varnish layer laminated between the conductor wire and the anti-surge varnish layer and a second insulating varnish layer laminated on the anti-surge varnish layer, and the first insulating varnish layer and the anti-surge varnish layer. The second insulating varnish layers each independently have an average thickness of 20 to 40% of the average thickness of the insulating coating layer.

In addition, it provides a corona-resistant square winding, characterized in that the thickness of the insulating coating layer in the bent portion is greater than the thickness of the insulating coating layer in the flat portion.

Meanwhile, a corona-resistant square winding is provided, wherein the radius of curvature (R ₁ ) of the round formed at each bend is larger than the radius of curvature (R ₂ ) of the insulating coating layer formed at each bend.

In addition, the conductor wire provides a corona-resistant square winding, characterized in that it is made of oxygen-free copper.

In addition, the polymer resin included in the insulating coating layer is polyamide imide resin, polyimide resin, polyamide resin, polyvinyl formal resin, polyurethane resin, heat-resistant polyurethane resin, polyester resin, and polyester imide resin. Provided is a corona-resistant square winding, characterized in that it contains at least one resin selected from the group consisting of.

Furthermore, the nano inorganic particles are selected from the group consisting of silica, alumina, titanium dioxide, zirconia, yttria, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandinium oxide and barium oxide. Provided is a corona-resistant square winding, characterized in that it includes at least one type.

Here, the content of the nano inorganic particles is 5 to 15 parts by weight based on 100 parts by weight of the polymer resin included in the anti-surge varnish layer.

In addition, the nano inorganic particles have a size of 5 to 100 nm and provide a corona-resistant square winding, characterized in that the surface is hydrophobically modified.

On the other hand, when the anti-surge varnish layer is formed on the conductor line, the anti-surge varnish layer further includes an adhesion improver, and when the insulating varnish layer includes a first insulating varnish layer formed on the conductor line, The first insulating varnish layer further includes an adhesion improver, and the adhesion improver is one or more adhesives selected from the group consisting of melamine-based adhesives, amine-based adhesives, mercaptan-based adhesives, and polycarboimide adhesives. Provided is a corona-resistant square winding, characterized in that it comprises:

And, as a corona-resistant square winding, it includes a conductor wire having a cross-sectional shape including a flat part and a bent part, and an insulating coating layer surrounding the conductor wire, wherein the insulating coating layer includes one or more anti-corrosive substances including a polymer resin and nano inorganic particles. It includes a surge varnish layer and one or more insulating varnish layers containing a polymer resin, and the thickness increase rate of the anti-surge varnish layer defined by Equation 1 below is greater than the thickness increase rate of the insulating coating layer defined by Equation 1 below. Provides a corona-resistant flat angle winding characterized in that.

[Equation 1]

Thickness increase rate (%) = {(layer thickness at bent part - layer thickness at flat part)/layer thickness at flat part} ×100

In Equation 1 above,

The layer thickness at the bend is the average value of the anti-surge varnish layer or insulating coating layer thickness measured at each bend of the conductor wire,

The layer thickness in the flat part is the average value of the anti-surge varnish layer or insulating coating layer thickness measured in each flat part of the conductor line.

Here, a corona-resistant square winding is provided, characterized in that the thickness increase rate of the anti-surge varnish layer is 10 to 50%.

In addition, a corona-resistant square winding is provided, characterized in that the average thickness of the insulating coating layer is 70 to 120 ㎛.

Here, based on the average thickness of the insulating coating layer, the average thickness of the anti-surge varnish layer occupies 30 to 50%, and the average thickness of the insulating varnish layer occupies 50 to 70%. Provides a square winding.

In addition, the insulating varnish layer includes a first insulating varnish layer laminated between the conductor wire and the anti-surge varnish layer and a second insulating varnish layer laminated on the anti-surge varnish layer, and the first insulating varnish layer and the anti-surge varnish layer. The second insulating varnish layers each independently have an average thickness of 20 to 40% of the average thickness of the insulating coating layer.

In addition, a corona-resistant square winding is provided, wherein the radius of curvature (R ₁ ) of the round formed at each bend is larger than the radius of curvature (R ₂ ) of the insulating coating layer formed at each bend.

In the corona-resistant square winding according to the present invention, the electric field is structurally concentrated at the corner, the thickness of the insulating coating layer formed for each coating area is different, and two or more types of insulating films with different viscosity, surface tension, etc. are stacked to form an insulating coating layer. Therefore, even in cases where it is extremely difficult to design the thickness of the insulating coating layer, it has an excellent effect in achieving the desired corona resistance.

In addition, although the corona-resistant square winding according to the present invention has excellent corona resistance, it exhibits excellent effects in terms of adhesion and flexibility of the insulating coating layer, which are in conflict with this.

Figure 1 schematically shows the cross-sectional structure of one embodiment of a corona-resistant square winding according to the present invention.
Figure 2 schematically shows the cross-sectional structure of another embodiment of the corona-resistant square winding according to the present invention.
FIG. 3 shows a method for measuring the thickness of the insulating coating layer of each of the curved and flat sections in the cross section of the corona-resistant square winding shown in FIG. 1.
FIG. 4 shows a method for measuring the thickness of the insulating coating layer of each of the curved and flat sections in the cross section of the corona-resistant square winding shown in FIG. 2.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure will be thorough and complete, and so that the spirit of the invention can be sufficiently conveyed to those skilled in the art. Like reference numerals refer to like elements throughout the specification.

1 and 2 schematically show the cross-sectional structure of embodiments of the corona-resistant square winding according to the present invention.

As shown in Figures 1 and 2, the corona-resistant square winding according to the present invention has conductor wires (10, 10') that serve as passages through which current flows, and current flowing along the conductor wires (10, 10'). It includes insulating coating layers (20, 20') surrounding the conductor wires (10, 10') to prevent leakage to the outside.

The conductor wires 10 and 10' are made of a metal with high conductivity and can be mainly made of copper, copper alloy, aluminum, aluminum alloy, etc., and considering solderability, they can preferably be made of oxygen-free copper. The conductor wires 10, 10' have a rectangular cross-sectional shape, and as shown in FIG. 1, there are four flat portions (p ₁ , p ₂ , p ₃ , p ₄ ) on the top, bottom, left, and right sides, and 4 on the corners. It has two curved parts (r ₁ , r ₂ , r ₃ , r ₄ ), or, as shown in Figure 2, two flat parts (p ₁ ', p ₂ ') at the top and bottom and two curved parts at the corners. It has (r ₁ ',r ₂ ').

In addition, in the conductor line 10 shown in FIG. 1, each of the bent portions (r ₁ , r ₂ , r ₃ , r ₄ ) may be formed into a round with a specific radius of curvature (R ₁ ), and the radius of curvature (R ₁ ) may be larger than the radius of curvature (R ₂ ) of the insulating coating layers 20 and 20' formed on the bent portions (r ₁ , r ₂ , r ₃ , r ₄ ). The insulating coating layers 20, 20' surrounding the conductor wire 10, as well as the anti-surge varnish layer and the insulating varnish layer described below, have flat and curved parts corresponding to the flat and curved parts of the conductor wire. When the radius of curvature (R ₂ ) of the insulating coating layer (20, 20') is larger than the radius of curvature (R ₁ ) of the conductor wire, the insulating coating layer (20) at the bending portion (r ₁ , r ₂ , r ₃ , r ₄ ) ,20') Insufficient thickness may make insulation vulnerable.

The insulating coating layers 20, 20' are made of polyamide imide resin, polyimide resin, polyamide resin, polyvinyl formal resin, polyurethane resin, heat-resistant polyurethane resin, polyester resin, polyester imide resin, etc. It may contain one or more selected resins, and in particular, when the corona-resistant square winding is for an electric vehicle or a hybrid vehicle, the insulating coating layer (20, 20') preferably contains a polyamide imide resin with excellent heat resistance. do.

Specifically, electric vehicle or hybrid vehicle motors are required to be miniaturized and have higher output. When the current is increased to meet the demand for high output, the volume of the square winding applied to the motor increases, thereby failing to satisfy the demand for miniaturization.

Therefore, it may be considered to increase the applied voltage to meet the demand for high output without increasing the volume of the square winding. In this case, the surge voltage generated when the inverter generates the sine wave required to drive the motor increases and the partial voltage increases. Insulation breakdown may occur due to discharge.

Therefore, in order to prevent the occurrence of partial discharge itself, the thickness of the insulating coating layer constituting the rectangular winding can be formed thick, but in this case, the adhesion and film scratch resistance of the winding deteriorates, thereby increasing the size of the motor and reducing the space factor. Deterioration may result in reduced motor efficiency.

As a result, while satisfying the partial discharge initiation voltage (PDIV) required for the square winding, high anti-surge characteristics are secured while minimizing the thickness of the insulating coating layer of the square winding for miniaturization and high output of the motor to which the square winding is applied. Needs to be.

In this situation, the average thickness of the insulating coating layers 20 and 20' may be 70 to 120 ㎛. If the average thickness of the insulating coating layer (20, 20') is less than 70 ㎛, the dielectric breakdown voltage (BDV) of the rectangular winding may decrease, whereas if it is more than 120 ㎛, the rectangular winding may be distorted or bent when applied to a motor, etc. As a result, the insulating coating layers 20 and 20' may be cracked and the space factor may be lowered, thereby deteriorating the function of the motor, etc.

The insulating coating layers 20 and 20' may have a multi-layer structure containing the same or different resins, as shown in FIGS. 1 and 2. Specifically, the insulating coating layer (20, 20') includes one or more anti-surge varnish layers (21, 21') in which nano inorganic particles are uniformly dispersed in the resin to implement corona resistance, and the anti-surge varnish layer (21, 21') First insulating varnish layers (22a, 22a') that are formed by being laminated under the varnish layers (21, 21') to realize excellent adhesion to the conductor lines (10, 10') and/or the anti-surge varnish layer ( A second insulating varnish that is formed by being laminated on top of the anti-surge varnish layer (21, 21') to protect the anti-surge varnish layer (21, 21') from external shock or pressure and to realize smooth surface characteristics of the insulating coating layer (20, 20'). It may include layers 22b and 22b'.

Here, based on the average thickness of the insulating coating layers (20, 20'), the average thickness of the anti-surge varnish layers (21, 21') accounts for 30 to 50%, and the insulating varnish layers (22, 22') The average thickness may account for 50 to 70%. In addition, the insulating varnish layers 22, 22' include first insulating varnish layers 22a, 22a' stacked under the anti-surge varnish layers 21, 21' and the anti-surge varnish layers 21, 21'. ) When including all of the second insulating varnish layers (22b, 22b') laminated on top, the first insulating varnish layers (22a, 22a') and the second insulating varnish layers (22b, 22b') are each insulated It may have an average thickness of 20 to 40% of the average thickness of the coating layers 20 and 20'.

If the average thickness of the anti-surge varnish layers (21, 21') is less than 30% of the average thickness of the insulating coating layers (20, 20'), the partial discharge initiation voltage (PDIV) of the square winding may decrease. If it exceeds 50%, the film-damaging properties of the insulating coating layers 20 and 20' may be reduced.

The nano-inorganic particles prevent insulation breakdown due to corona discharge caused by inverter surge, improve thermal conductivity, reduce thermal expansion, and improve enamel wire strength. For example, silica, alumina, and dioxide It may contain one or more nano inorganic particles selected from titanium, zirconia, yttria, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandinium oxide, barium oxide, etc.

Methods for producing a resin in which the nano-inorganic particles are dispersed are already known, for example, ball-milling disclosed in U.S. Patent No. 6,403,890, high shear force mixing disclosed in U.S. Patent No. 4,493,873. A mechanical method of shear mixing, simple stirring disclosed in US Patent No. 6,180,888, a sol-gel method disclosed in Japanese Patent Publication No. 2003-36731, etc. may be used.

In addition, in order for the nano inorganic particles to effectively exhibit corona resistance, they have excellent dispersion characteristics, an extremely fine particle size, preferably a nano size of 4 to 100 nm, and a high specific surface area (BET), preferably 100 to 300. A specific surface area of ㎡/g, high purity, preferably 95% or more, spherical particle shape, absence of pores, etc. are required, and various methods for improving these properties are already known.

For example, German Patent No. 4209964 discloses surface-modified nano inorganic particles to facilitate dispersion in a resin, for example, nano inorganic particles whose surfaces are silanized. Since the nano inorganic particles generally have a hydrophilic surface, there is a problem of agglomeration and dispersion in the hydrophobic resin. Therefore, in order to improve the dispersibility of the nano inorganic particles in the resin, they are placed on the surface of the nano inorganic particles. The surface of the nano-inorganic particles can be modified to be hydrophobic by coating a surface modifier having a functional group capable of forming a covalent or non-covalent bond with the resin.

Specifically, the surface-modified nano-inorganic particles are prepared by adding the nano-inorganic particles to a solvent such as toluene, xylene, ethanol, or cresol to create a mixed solution, and adding amine, epoxy, thiol, carboxylic acid, sulfonic acid, phosphoric acid, It can be prepared by adding and reacting one or more surface modifiers selected from the group consisting of phosphinic acid, cyanic acid, and silane.

The content of the nano inorganic particles may be 5 to 15 parts by weight based on 100 parts by weight of the resin. If the content of the nano inorganic particles is less than 5 parts by weight, the corona resistance may be insufficient, whereas if it is more than 15 parts by weight, the adhesion between the conductor wires (10, 10') and the insulating coating layer (20, 20') , the flexibility, etc. of the insulating coating layers 20 and 20' may be reduced.

In addition, the nano inorganic particles may exist as a single particle or as two or more particles aggregated, and may exist in a size of about 4 to 100 nm. If the size of the nano-inorganic particles is less than 4 nm, the effect of improving the corona resistance of the square winding may be minimal, whereas if the size is more than 100 nm, the insulating coating layer (20, Adhesion, film-damaging properties, flexibility, etc. of 20') may be reduced, and the insulating coating layers 20 and 20' produced may be deteriorated when charged particles generated by corona discharge collide with the nano-inorganic particles.

The insulating coating layer (20, 20') is located below the anti-surge varnish layer (21, 21') to further improve adhesion between the conductor wire (10, 10') and the insulating coating layer (20, 20'). may include first insulating varnish layers 22a and 22a'. The first insulating varnish layers 22a and 22a' may have better adhesion to the conductor lines 10 and 10' than the anti-surge varnish layers 21 and 21' containing nano inorganic particles.

Among the insulating coating layers 20 and 20', the first insulating varnish layers 22a and 22a', the anti-surge varnish layers 21 and 21', or both are insulated from the conductor wires 10 and 10'. In order to improve the adhesion between the coating layers 20 and 20', an adhesion agent, that is, an adhesion enhancer, may be additionally included. The adhesive is one or more adhesives selected from the group consisting of melamine-based alkoxy melamine resins such as butoxy, amine-based such as trialkyl amine, mercaptan-based such as mercaptobenzimidazole, polycarbodiimide, etc. It can be included. The content of the adhesive may be 1 to 3 parts by weight based on 100 parts by weight of the resin constituting each varnish layer.

In the corona-resistant square winding of the present invention, the electric field is structurally concentrated on the corner portion (r ₁ , r ₂ , r ₃ , r ₄ , r ₁ ', r ₂ '), and the conductor wire (10) is formed using a coating die. , 10') When forming the insulating coating layer (20, 20') on the surface, the thickness of the insulating coating layer (20, 20') formed for each part of the conductor wire (10, 10') is different, and in particular, the insulating coating layer (20, 20') is different. When (20,20') includes two or more varnish layers with different viscosity, surface tension, etc., that is, the first insulating varnish layer, the anti-surge varnish layer, and the second insulating varnish layer, due to their different physical properties By having different thickness ratios of each varnish layer for each part of the conductor wires 10 and 10', the insulating coating layer 20 is designed to achieve the desired corona resistance and at the same time maintain adhesion and flexibility, which are in conflict with this. Design for a thickness of 20') is extremely difficult.

In this regard, the present inventors have implemented the desired corona resistance by performing excessively repetitive simulations while controlling the shape of the coating die, while maintaining the adhesion and flexibility that are in conflict with the above insulating coating layer (20, 20'), specifically, the thickness and correlation between parts of the insulating coating layers 20, 20', the thickness ratio of two or more different insulating layers included in the insulating coating layers 20, 20', etc. By deriving the present invention, the present invention was completed.

Specifically, in the corona-resistant square winding according to the present invention, the thickness increase rate of the anti-surge varnish layers (21, 21') defined by Equation 1 below is the insulating coating layer (20, 20') defined by Equation 1 below: ), especially compared to the thickness increase rate of the insulating varnish layers 22 and 22'.

[Equation 1]

Thickness increase rate (%) = {(layer thickness at the bent part - layer thickness at the flat part)/layer thickness at the flat part} x 100

In Equation 1 above,

The layer thickness at the bent portion is determined by the reference points ( _a1 , _a3 , _a5 , _a7 , _a1 ' _, Thickness of anti-surge varnish layer, insulating varnish layer or insulating coating layer (e1, e2, e3, e4, e1 ',e2') is the average value,

The layer thickness in the flat part is determined by the reference points (a2, a4, a6, a8, a2) of each of the flat parts (p ₁ , p ₂ , p ₃ , p ₄ , p ₁ ', p ₂ ') shown in Figure 3 or 4. Thickness (t1, t2, t3, t4) of the anti-surge varnish layer, insulating varnish layer or insulating coating layer measured by the straight line distance from ',a4') to the measurement point (b2,b4,b6,b8,b2',b4'). ,t1',t2').

Here, the reference points (a1, a3, a5, a7) of each of the bent portions shown in FIG. 3 may be a conductor line, a surge-resistant varnish layer, or an insulating varnish layer formed directly below the thickness measurement layer 200, which is the object of layer thickness measurement. Assuming that the cross-section of the base layer 100 is a rectangle indicated by a broken line, the line connecting the center point and each corner of the rectangle forming the cross-section of the base layer 100 is defined as the point where the outline of the curved portion of the base layer 100 meets the outline. It can be, and the measurement points (b1, b3, b4, b7) are the center point and each corner of the rectangle forming the cross section of the thickness measurement layer 200, assuming that the thickness measurement layer 200 has a rectangular cross section. It may be defined as a point where the connected line meets the outline of the curved portion of the thickness measurement layer 200.

In addition, the reference points (a2, a4, a6, and a8) of each of the flat parts shown in FIG. 3 are the lines connecting the center point of the rectangle forming the cross-section of the base layer 100 and the center of each side, and It can be defined as a point that meets the outline of each part, and the measurement points (b2, b4, b6, b8) form the cross section of the thickness measurement layer 200, assuming that the cross section of the thickness measurement layer 200 is rectangular. It may be defined as the point where the line connecting the center point of the rectangle and each corner meets the outline of the flat portion of the thickness measurement layer 200.

In addition, the reference points (a1', a2', a3', and a4') of each of the curved portion and the flat portion shown in FIG. 4 are conductor lines formed directly below the thickness measurement layer 200', which is the object of layer thickness measurement, and the anti-surge Assuming that the cross-section of the base layer 100', which may be a varnish layer or an insulating varnish layer, is a rectangle indicated by a broken line, the line connecting the center point of the rectangle forming the cross-section of the base layer 100' and the center of each side is the base layer 100. ') It may be defined as a point that meets the outline of the curved portion or the flat portion, and the measurement points (b1', b2', b3', and b4') of each of the bent portion and the flat portion are the cross sections of the thickness measurement layer 200'. Assuming that it is a rectangle, the line connecting the center point of the rectangle forming the cross-section of the thickness measurement layer 200' and the center of each side may be defined as the point where the outline of the curved or flat portion of the thickness measurement layer 200 meets the outline. there is.

Specifically, when the thickness increase rate of the anti-surge varnish layers (21, 21') is lower than the thickness increase rate of the insulating varnish layers (22, 22'), partial discharge of the rectangular winding occurs due to an electric field concentrated in a bend of the rectangular winding. The onset voltage (PDIV) may decrease and adhesion between the anti-surge varnish layers (21, 21') and the conductor wire (10.10') may be insufficient.

In particular, the thickness increase rate of the anti-surge varnish layers 21 and 21' may be 10 to 50%. That is, the thickness of the anti-surge varnish layers 21 and 21' of the curved portion may be 10 to 50% thicker than the thickness of the anti-surge varnish layers 21 and 21' of the flat portion.

When the thickness of the anti-surge varnish layer (21, 21') of the curved portion is less than 10% based on the thickness of the anti-surge varnish layer (21, 21') of the flat portion, the partial discharge initiation voltage (PDIV) of the square winding ), etc. may decrease, while if it exceeds 50%, the thickness of the anti-surge varnish layers 21 and 21' of the flat portion is formed excessively thin, and the partial discharge initiation voltage (PDIV) of the flat angle winding decreases. and the adhesion between the conductor wires (10, 10') and the insulating coating layers (20, 20') is reduced, and the thickness of the insulating coating layers (20, 20') at the bends is excessively thick, reducing the flexibility of the square winding. This may be lowered, and the thickness of the insulating varnish layers 22 and 22' in the bent portion may be formed relatively thin, resulting in reduced film flaw resistance.

In addition, in the corona-resistant square winding according to the present invention, the thickness of the insulating coating layer (20, 20') at the bent portion (r ₁ , r ₂ , r ₃ , r ₄ , r ₁ ', r ₂ ') is It may be greater than the thickness of the insulating coating layers 20 and 20' in the flat angle parts (p ₁ , p ₂ , p ₃ , p ₄ , p ₁ ', p ₂ '). The bent portions (r ₁ , r ₂ , r ₃ , r ₄ , r ₁ ', r ₂ ') are vulnerable to insulation breakdown or partial discharge due to electric field concentration, and the insulating coating layers 20 and 20' are formed into a flat portion ( Insulating performance can be strengthened by forming thicker than (p ₁ , p ₂ , p ₃ , p ₄ , p ₁ ', p ₂ ').

Specifically, the thickness of the insulating coating layer (20, 20') in the curved portion (r ₁ , r ₂ , r ₃ , r ₄ , r ₁ ', r ₂ ') is the thickness of the flat portion (p ₁ , p ₂ , p ₃ , p ₄ , p ₁ ', p ₂ ') may be 100 to 150% of the thickness of the insulating coating layer (20, 20'), and if it is less than 100%, the insulation breakdown performance and corona resistance are reduced, and if it exceeds 150% In this case, problems such as a decrease in adhesion between the insulating coating layer (20, 20') and the conductor wire (10, 10'), an increase in the coating material cost, and an increase in the thickness of the coating at the bend may cause problems such as difficulty in winding the square winding in an aligned manner. It is not desirable.

[Example]

1. Manufacturing example

A square winding specimen was prepared having the thicknesses of the anti-surge varnish layer and the insulating varnish layer as shown in Table 1 below. Here, the insulating varnish layer includes a first insulating varnish layer disposed between the anti-surge varnish layer and the square conductor and a second insulating varnish layer laminated on the anti-surge varnish layer, and the thickness of the insulating varnish layer is The thickness is the sum of the thickness of the first insulating varnish layer and the thickness of the second insulating varnish layer.

In addition, the square winding specimen has a coating flatness (=thickness of the thickest part of the insulating coating layer/thickness of the thinnest part of the insulating coating layer), which indicates the thickness deviation of the insulating coating layer coated on the conductor wire, of 1.5 or less.

The unit of thickness listed in Table 1 below is ㎛.

Example Comparative example One 2 3 4 One 2 3 Resistant varnish layer Flat angle part 29.13 31.13 30.13 28.13 30.05 29.58 31.13 bend 34.65 39.66 40.68 40.8 30.27 31.64 48.70 Thickness increase rate (%) 18.95 27.40 35.01 45.04 0.73 6.96 56.44 Isolation
Varnish layer Flat angle part 51.20 46.92 49.64 49.50 48.48 49.90 47.40 bend 59.92 53.80 58.42 58.02 60.33 59.40 50.12 Thickness increase rate (%) 17.03 14.66 17.69 17.21 24.44 19.04 5.74 Isolation
coating layer Flat angle part 80.33 78.05 79.77 77.63 78.53 79.48 78.53 bend 94.57 93.46 99.1 98.82 90.60 91.04 98.82 Thickness increase rate (%) 17.73 19.74 24.23 27.30 15.37 14.54 25.84

2. Physical property evaluation

1) Dielectric breakdown voltage (BDV) evaluation

The dielectric breakdown voltage was measured at room temperature for five square winding specimens from each of the examples and comparative examples, and the average value of the measured values was calculated. Specifically, the metal shot method is a method of measuring the insulation breakdown voltage after placing a winding specimen bent with a mandrel with a radius of 25 mm in a container filled with steel beads at room temperature and applying voltage.

2) Partial discharge onset voltage (PDIV) evaluation

A voltage with a 60 Hz sine wave was applied to the square winding specimens according to each of the examples and comparative examples at room temperature, and the voltage at which partial discharge was initiated was measured. Here, if the voltage at which a charge of 100 pC or more is detected when increasing the applied voltage is less than 1,000 V, it is a failure.

3) Pulse immunity evaluation

A voltage of 1,000 V (10 kHz sine wave) was applied to the square winding specimens according to each of the examples and comparative examples, and the time until a leakage current of 50 mA or more was detected was measured.

4) Adhesion evaluation

In the square winding specimens according to each of the examples and comparative examples, the insulating coating layer was cut in the circumferential direction, stretched to an elongation rate of 15%, and then the length of the insulating coating layer peeled from the conductor was measured and recorded as a multiple of the width (W) of the conductor. did. If the measurement result is 1W or more, it fails.

5) Evaluation of film defects

According to the standard JIS C 3003, section 7.1.2, film flaw evaluation was performed on the square curved specimens according to each of the Examples and Comparative Examples. Specifically, cracks occurred among three specimens bent with a mandrel with a diameter (3W) three times the conductor width (W) and three specimens bent with a mandrel with a diameter (3T) three times the conductor height (T). If it does not meet the standard (fail).

The evaluation results of the above physical properties are shown in Table 2 below.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative example 2 Comparative example 3 Insulation breakdown voltage (V) 9900 9200 10600 11000 9000 8600 10000 Partial discharge onset voltage pass pass pass pass fail fail pass Pulse tolerance (hour) 10↑ 10↑ 10↑ 10↑ 3 5 10↑ Adhesion pass pass pass pass pass pass fail Film flaw: 3T mandrel pass pass pass pass pass pass fail Film resistance: 3W mandrel pass pass pass pass pass pass fail

As shown in Table 2, in the corona-resistant square windings of Examples 1 to 4 according to the present invention, the thickness of the insulating coating layer, especially the anti-surge varnish layer, and the thickness increase rate at the bend are precisely controlled, so that the dielectric breakdown voltage and partial It was confirmed that the characteristics such as discharge start voltage and pulse resistance were excellent, as well as the adhesion between the conductor and the anti-surge varnish layer and the film flaw resistance of the insulating coating layer.

On the other hand, the flat angle windings of Comparative Examples 1 and 2 were found to have insufficient corona resistance, such as partial discharge initiation voltage and pulse resistance, due to the reason that the thickness increase rate of the anti-surge varnish layer at the bend was below the standard, whereas the flat angle windings of Comparative Example 3 were confirmed to have insufficient corona resistance such as partial discharge initiation voltage and pulse resistance. It was confirmed that the winding had an excessive rate of increase in the thickness of the anti-surge varnish layer at the bending portion, resulting in an excessively thin insulating varnish layer at the bending portion, resulting in reduced film scratch resistance and decreased adhesion between the conductor and the anti-surge varnish layer. .

Although this specification has been described with reference to preferred embodiments of the present invention, those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims described below. It will be possible to implement it. Therefore, if the modified implementation basically includes the elements of the claims of the present invention, it should be considered to be included in the technical scope of the present invention.

10,10': Conductor 20,20': Insulating coating layer

Claims (19)

As a corona-resistant square winding,
It includes a conductor wire having a cross-sectional shape with a flat portion and a curved portion, and an insulating coating layer surrounding the conductor wire,
The insulating coating layer includes one or more anti-surge varnish layers containing a polymer resin and nano inorganic particles, a polymer resin and no nano inorganic particles, and is laminated between the conductor wire and the anti-surge varnish layer and adheres to the conductor wire. comprising at least one layer of insulating varnish,
The average thickness of the insulating coating layer is 70 to 120 ㎛,
The coating flatness obtained by dividing the thickness of the thickest part of the insulating coating layer by the thickness of the thinnest part of the insulating coating layer is 1.5 or less,
Based on the average thickness of the insulating coating layer, the average thickness of the anti-surge varnish layer accounts for 30 to 50%, and the average thickness of the insulating varnish layer accounts for 50 to 70%,
The insulating varnish layer laminated between the conductor wire and the anti-surge varnish layer is a first insulating varnish layer, and the insulating coating layer includes a second insulating varnish layer laminated on the anti-surge varnish layer, and the first insulating varnish layer and the second insulating varnish layer each independently has an average thickness of 20 to 40% of the average thickness of the insulating coating layer,
A corona-resistant square winding, characterized in that the thickness increase rate of the anti-surge varnish layer defined by Equation 1 below is greater than the thickness increase rate of the insulating varnish layer defined by Equation 1 below.
[Equation 1]
Thickness increase rate (%) = {(layer thickness at bent part - layer thickness at flat part)/layer thickness at flat part} ×100
In Equation 1 above,
The layer thickness at the bend is the average value of the thickness of the anti-surge varnish layer or the insulating varnish layer measured at each bend of the conductor wire,
The layer thickness in the flat part is the average value of the thickness of the anti-surge varnish layer or the insulating varnish layer measured in each flat part of the conductor wire. delete delete delete delete According to paragraph 1,
A corona-resistant square winding, characterized in that the thickness of the insulating coating layer in the bent portion is greater than the thickness of the insulating coating layer in the flat portion. According to paragraph 1,
A corona-resistant square winding, characterized in that the radius of curvature (R ₁ ) of each bend of the conductor wire is larger than the radius of curvature (R ₂ ) of the insulating coating layer formed at each bend. According to paragraph 1,
A corona-resistant square winding, characterized in that the conductor wire is made of oxygen-free copper. According to paragraph 1,
The polymer resin included in the insulating coating layer consists of polyamide imide resin, polyimide resin, polyamide resin, polyvinyl formal resin, polyurethane resin, heat-resistant polyurethane resin, polyester resin, and polyester imide resin. A corona-resistant square winding, characterized in that it comprises at least one resin selected from the group. According to paragraph 1,
The nano inorganic particle is one selected from the group consisting of silica, alumina, titanium dioxide, zirconia, yttria, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandinium oxide and barium oxide. A corona-resistant square winding, characterized in that it includes the above. According to clause 10,
A corona-resistant square winding, characterized in that the content of the nano inorganic particles is 5 to 15 parts by weight based on 100 parts by weight of the polymer resin included in the anti-surge varnish layer. According to clause 10,
The nano-inorganic particles have a size of 5 to 100 nm, and the surface is hydrophobically modified. A corona-resistant square winding. According to paragraph 1,
The insulating varnish layer further includes an adhesion enhancer,
The adhesion improver is a corona-resistant square winding, characterized in that it includes at least one adhesive selected from the group consisting of a melamine-based adhesive, an amine-based adhesive, a mercaptan-based adhesive, and a polycarboimide adhesive. As a corona-resistant square winding,
It includes a conductor wire having a cross-sectional shape with a flat portion and a curved portion, and an insulating coating layer surrounding the conductor wire,
The insulating coating layer includes one or more anti-surge varnish layers containing a polymer resin and nano inorganic particles, a polymer resin and no nano inorganic particles, and is laminated between the conductor wire and the anti-surge varnish layer and adheres to the conductor wire. comprising at least one layer of insulating varnish,
The average thickness of the insulating coating layer is 70 to 120 ㎛,
The coating flatness obtained by dividing the thickness of the thickest part of the insulating coating layer by the thickness of the thinnest part of the insulating coating layer is 1.5 or less,
Based on the average thickness of the insulating coating layer, the average thickness of the anti-surge varnish layer accounts for 30 to 50%, and the average thickness of the insulating varnish layer accounts for 50 to 70%,
The insulating varnish layer laminated between the conductor wire and the anti-surge varnish layer is a first insulating varnish layer, and the insulating coating layer includes a second insulating varnish layer laminated on the anti-surge varnish layer, and the first insulating varnish layer and the second insulating varnish layer each independently has an average thickness of 20 to 40% of the average thickness of the insulating coating layer,
A corona-resistant square winding, characterized in that the thickness increase rate of the anti-surge varnish layer defined by Equation 1 below is greater than the thickness increase rate of the insulating coating layer defined by Equation 1 below.
[Equation 1]
Thickness increase rate (%) = {(layer thickness at bent part - layer thickness at flat part)/layer thickness at flat part} ×100
In Equation 1 above,
The layer thickness at the bend is the average value of the anti-surge varnish layer or insulating coating layer measured at each bend of the conductor wire,
The layer thickness in the flat part is the average value of the anti-surge varnish layer or insulating coating layer thickness measured in each flat part of the conductor line. delete delete delete delete According to clause 14,
A corona-resistant square winding, characterized in that the radius of curvature (R ₁ ) of each bend of the conductor wire is larger than the radius of curvature (R ₂ ) of the insulating coating layer formed at each bend.

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