JP5890698B2 - Stator and segment coil - Google Patents

Description

  The present invention relates to a stator and a segment coil. Specifically, the present invention relates to a stator including a segment coil that can effectively prevent partial discharge between adjacent coils and the like.

  For example, a stator constituting an electric motor is configured by providing a coil on an annular core. The annular core is provided with a plurality of slots that open to the inside at predetermined intervals, and the coils are mounted in the slots. Conventional coils are provided by winding a bendable wire around the slot. However, there is a problem that it is difficult to wind the winding wire without damaging the slot that opens to the inside, and workability is poor.

  Moreover, in the winding which can be bent, since the cross-sectional diameter of a conductor cannot be set large, a large electric current cannot be sent. For this reason, it is difficult to increase the output of the electric motor. Moreover, in order to meet the demand for improvement in output and miniaturization of the motor, it is necessary to increase the space factor of the coil. However, in the configuration in which the winding is wound, it is difficult to improve the space factor.

  In order to solve the above-described problem, a plurality of segment coils that are formed in advance in a form that allows a coil material having a large cross-sectional area to be mounted in the slot are mounted in the slot, and a connection end extending from the slot is welded or the like Thus, it is possible to adopt a method of connecting and configuring the coil. Since the cross-sectional area can be set large by making the cross-section of the segment coil correspond to the cross-sectional shape of the slot, a large current can flow and the space factor can be set large, and the output of the motor Can be increased.

JP 2004-254457 A

  The segment coil is provided with an insulating coating layer for performing insulation between the adjacent segment coil and the core. The insulating coating layer needs to be configured so that partial discharge does not occur between the members. The partial discharge is likely to occur in a portion where the voltage difference is large. For example, when a segment coil is employed in the stator of a three-phase AC motor, the voltage difference between the segment coils belonging to different phases is the largest. Therefore, partial discharge is likely to occur at a portion where segment coils belonging to different phases are close to or in contact with each other.

  In particular, there is a great demand for higher voltage and smaller motors used in electric vehicles and hybrid vehicles. On the other hand, in an inverter drive motor having a high-speed switching circuit, a surge overvoltage is often applied. When a surge overvoltage is applied, the voltage between coils belonging to different phases becomes very large, and when these coils are close to each other, the risk of partial discharge between these coils increases. Also, since a large current flows through this type of motor, if a partial discharge occurs, the coil insulation film and the like will be seriously damaged.

  On the other hand, the voltage difference between the segment coils belonging to the same phase or between the core and the segment coil is smaller than the voltage difference between the segment coils belonging to different phases.

  The conventional segment coil is configured to prevent the partial discharge by providing an insulation coating layer that can cope with a voltage difference between segment coils belonging to different phases over the entire area of the segment coil.

  However, since the insulating coating layer that can cope with a large potential difference is provided over the entire area of the segment coil, the space factor in the slot is lowered, resulting in a problem that the motor is enlarged and the amount of heat generation is increased.

  As described in the above patent document, there has been proposed a surge-resistant motor configured to form a conductive film on the insulating film of the conductor wire so as to alleviate the potential difference between the insulating coating layers of adjacent windings. ing.

  However, since the conductive film is formed by mixing a conductive powder material such as carbon in a resin, the degree of expansion and contraction is low, and film cracking is likely to occur in coil processing or the like. For this reason, it has been difficult to apply to the bending process in the segment coil.

  Further, when the conductive film is provided over the entire area of the segment coil, when the conductor wire is exposed and connected at the terminal, the conductive film is easily brought into contact with the conductive film to cause a short circuit and the terminal processing is difficult.

  The present invention solves the above-mentioned conventional problems, can set a large cross-sectional area of the coil, can flow a large current and can effectively prevent partial discharge, and can also increase the space factor to improve the performance of the motor. It is an object to provide a stator that can be improved.

The invention described in claim 1 of the present application is a stator including a plurality of slots formed in an inner peripheral portion of an annular core, and a plurality of segment coils mounted in the plurality of slots, wherein an insulating coating layer is provided. A semiconducting layer continuous over a predetermined length range is provided on the outer periphery of each coil end portion extending from the slot of each provided segment coil, and the plurality of segment coils include a first segment coil belonging to a first phase A second segment coil belonging to a second phase different from the first phase and disposed in proximity to the first segment coil, the semiconductive layer of the first segment coil and the second segment coil The semiconductive layer is configured to contact at least one point.

  In a stator employing a segment coil, coils belonging to the same phase are mounted in one slot, so that partial discharge between the coils in the slot rarely becomes a problem. On the other hand, in a coil end part, since a coil with a large cross-sectional area is arranged in a complicated manner, segment coils belonging to different phases cannot often be arranged separately. Therefore, when segment coils belonging to different phases are arranged in contact or close to each other, the risk of partial discharge between these segment coils increases.

  In many cases, the partial discharge is triggered by a potential difference due to static electricity accumulated on the coil surface. In the present invention, a semiconducting layer continuous over a predetermined length range is provided on the outer periphery of the coil end portion extending from the slot of the segment coil. In the coil end portion, the semiconductive layers of the segment coils that are arranged close to each other and belong to different phases are configured to contact at least one point. In the minimal gap in the vicinity of the contact point, even when the electric field strength is usually increased, by providing the semiconductive layer on the surface, the electric charge on the coil surface is dispersed and the electric field strength is reduced. When the electric field strength decreases, even if a voltage exceeding the partial discharge start voltage in the case where the semiconductive layer is not provided is generated, the occurrence of partial discharge is suppressed. That is, even when segment coils belonging to different phases are arranged adjacent to each other, the potential difference due to charge accumulation does not increase between the segment coils, and it is possible to effectively prevent partial discharge from occurring in these portions. Can do.

  In other words, in the present invention, by configuring the semiconductive layer provided in the segment coils belonging to different phases so as to contact at least one point, partial discharge between these segment coils can be effectively prevented. . If it is comprised so that it may contact in at least 1 point, the contact form of the said contact point will not be limited. For example, not only point contact but also line contact or surface contact may be used. In addition, the semiconductive layer can exert its effect even if the thickness is set thin. For this reason, the weight of the stator can be reduced and the manufacturing cost can be reduced as compared with the conventional method of increasing the thickness of the insulating coating layer.

  It is sufficient that the semiconductive layer is disposed so as to be continuous and provided continuously over a length range in which partial discharge may occur. For this reason, it becomes possible to provide the said semiconductive layer in the part which a partial discharge tends to produce after the bending process of a coil, and even if the compounding quantity of the filler which provides electroconductivity increases, a film crack layer does not arise. Furthermore, in the present invention, since the semiconductive layer is provided in the coil end portion extending from the slot, the thickness of the coil in the slot does not increase and the space factor does not decrease.

  Furthermore, if the semiconductive layer is provided only in the portion where the segment coils belonging to different phases are arranged close to each other, the effect can be exhibited. Therefore, since it is not necessary to provide even the terminal of a segment coil, the terminal process which peels a semiconductive layer is not needed.

As in the invention described in claim 2, the semiconductivity is set to be 5 μm or more and the surface resistivity is set to 1 × 10 ³ to 1 × 10 ⁹ Ω / sq, and is arranged close to each other. Each of the semiconductive layers of the segment coil is preferably formed so as to face each other in both directions along the axis of the segment coil, at least in a region greater than the maximum cross-sectional width of the segment coil, with the contact point as the center.

When the thickness of the semiconductive layer is less than 5 μm, the potential difference between adjacent segment coils cannot be sufficiently reduced. For this reason, it is preferable to set the thickness of the semiconductive layer to 5 μm or more. Moreover, in order to ensure the required potential difference reduction effect between the adjacent segment coils, it is preferable to set the surface resistivity of the semiconductive layer to 1 × 10 ³ to 1 × 10 ⁹ Ω / sq. By adopting the above configuration, the surface resistivity of the input side coil where the applied voltage is increased in one stator is lowered, and the partial discharge start voltage in the opposing region of the semiconductive layer is set to 1000 V or more. It becomes possible to set.

  The range in which the semiconductive layer is provided is sufficient as long as partial discharge can be effectively prevented. For example, the effect can be expected by providing at least a region equal to or larger than the maximum sectional width of the segment coil in both directions along the axis of the segment coil with the contact point as the center. With the above configuration, it is possible to prevent a potential difference between the segment coils facing each other through the minute gap, and to effectively prevent partial discharge in these gaps.

  In addition, when providing a semiconductive layer continuously in the area | region 200 mm or more, it is desirable to comprise so that a semiconductive layer may be made to oppose in the area | region within 100 mm from all the contact points. That is, when there are two contact points, by setting the distance between these contact points within 200 mm, partial discharge between adjacent segment coils can be reliably prevented in these regions.

  The material constituting the semiconductive layer is not particularly limited. As in the invention described in claim 3, the semiconductive layer can be constituted by blending conductive particles in a resin material. For example, the resin material which comprises the semiconductive layer which has the said function by mix | blending carbon powder 10%-40% with thermosetting resins, such as a polyamide-imide resin, can be obtained. Usually, when the amount of filler such as carbon powder increases, the elongation at break of the resin material decreases. For this reason, it has been difficult to apply a semiconductive layer having a high partial discharge prevention effect to a conventional coil wound around a core. In the present invention, since the semiconductive layer can be formed by post-processing on a segmented coil that has been bent, the elongation at break of the semiconductive layer does not become a problem.

According to a fourth aspect of the present invention, the semiconductive layer can be composed of a conductive resin provided on the outer periphery of the segment coil .

Further, as in the invention described in claim 5, the semiconductive layer can be made of a semiconductive tape material or tube material provided on the outer peripheral portion of each segment coil .

  For example, a tape material such as Kapton adhesive tape having semiconductivity (registered trademark of DuPont, USA), aramid non-woven fabric (Nikkan Kogyo Co., Ltd., # 5183, 65 μm) can be used. Further, a heat shrinkable tube in which a conductive material is blended with a fluorine-based resin such as PFA or FEP can be employed.

  As in the invention described in claim 6, it is preferable that the semiconductive layer is not provided near the connection end of each segment coil. That is, the connection ends of the segment coils are formed apart from the semiconductive layer. This is because the current leaks through the semiconductive layer and the loss increases. For example, by providing a region in which only the insulating coating layer is formed in the vicinity of the connection end, the connection end of each segment coil and the semiconductive layer can be provided apart from each other.

  In a stator formed using segment coils, partial discharge can be effectively prevented without lowering the space factor.

It is a perspective view of the principal part which shows the state which assembled | attached the segment coil to the core. It is a front view which shows an example of a segment coil. It is sectional drawing which follows the III-III line in FIG. It is a figure which shows the relationship between a partial discharge start voltage and surface resistivity. It is sectional drawing which shows typically the state which made the semiconductive layer provided in the coil contact.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a perspective view of a main part of a stator 1 in which segment coils 4 and 5 are attached to a core 2. FIG. 2 is a front view showing one embodiment of the segment coils 4 and 5. In the present embodiment, the present invention is applied to a stator 1 of a three-phase AC motor.

  The core 2 has a thick annular structure made of a magnetic material, and slots 3 are formed at predetermined intervals in the inner peripheral portion so as to penetrate in the axial direction and open to the inner peripheral surface. The slot 3 is formed substantially corresponding to the width of the segment coils 4 and 5, and the segment coils 4 and 5 are assembled to the core 2 by accommodating the straight portions of the segment coils 4 and 5 in the slot 3. It is done.

  The material which comprises the said core 2 is not specifically limited. For example, a core formed by compacting magnetic powder or a core formed by stacking magnetic steel plates can be employed.

  For example, in a three-phase induction motor, a plurality of segment coils each grouped into a U phase, a V phase, and a W phase are assembled at predetermined intervals in the slot. Hereinafter, the segment coils 4 and 5 belonging to different phases will be described.

  As shown in FIG. 2, the segment coils 4 and 5 have a pair of linear portions 4b and 5b accommodated in the slot 3 and a pair of chevron shapes that extend from both axial ends of the slot. Coil end portions 4a, 4c and 5a, 5c are provided. One of the coil end portions 4a and 5a is provided so as to connect the pair of linear portions 4b and 5b accommodated in a predetermined slot in a spanning manner. At the ends of the other coil end portions 4c and 5c, connection portions 4d and 5d for connecting to the segment coils accommodated in other slots are provided. The other coil end portions 4c and 5c are prepared in a plurality of forms according to the connection pattern of the segment coils.

  The segment coils 4 and 5 are formed with an insulating coating layer 9 having a thickness of about 15 μm over the entire outer peripheral surface excluding the connection portions 4d and 5d, and provide insulation between adjacent segment coils and cores. It is configured so that it can be secured.

  FIG. 3 shows a cross section of the segment coils 4 and 5 according to the first embodiment of the present invention.

  As shown in FIG. 3, the segment coils 4 and 5 according to the present embodiment are configured by providing an insulating coating layer 9 on the outer peripheral surface of a conductive coil material 8 having a rectangular cross section.

  Furthermore, in this embodiment, while providing the semiconductive layer 6 in the outer peripheral part of the coil end part 4a, 5a, 4c, 5c extended from the said slot 3 of each segment coil 4 and 5 which provided the insulating coating layer 9, The semiconductive layers 6 and 6 of the segment coils 4 and 5 which are arranged close to each other and belong to different phases are configured to contact at least at one point P.

  As shown in FIG. 5, the semiconductive layer 6 is provided in both directions along the axis of the segment coil with the contact point as the center, at least in a region greater than the maximum cross-sectional width of the segment coil. For example, when a coil having a rectangular cross section is employed, it is preferable to provide the semiconductive layer 6 in a region that is longer than the diagonal length of the rectangular cross section with the contact point as the center. In the present embodiment, the semiconductive layer 6 is provided in the range of not less than the maximum sectional width of the segment coil and not more than 100 mm. The thickness of the semiconductive layer 6 is not particularly limited, and can be formed with a thickness of 5 to 100 μm, for example.

As shown in FIG. 4, the semiconductive layer 6 has a surface resistivity of 1 × 10 ³ to 1 × 10 ⁹ Ω / sq, and a conductive material applied to a fluorine-based resin such as PFA or FEP. The blended heat-shrinkable tube is mounted in a range of 200 mm with the contact point P as the center. Moreover, tape materials, such as a semiconductive Kapton adhesive tape (registered trademark of DuPont, USA) and an aramid nonwoven fabric (Nikkan Kogyo Co., Ltd., # 5183, 65 μm), can be used.

Since the semiconductive layer 6 has a surface resistance of 1 × 10 ³ to 1 × 10 ⁹ Ω / sq as shown in FIG. 4, the partial discharge start voltage can be increased to 1000 V or more. In this embodiment, in the range of 100 mm before and after the contact point P, the semiconductive layers 6 and 6 of the segment coils 4 and 5 are opposed to each other, and the partial discharge start voltage between the semiconductive layers 6 and 6 is set. Is set to be 1000 V or higher. For this reason, it has comprised so that the partial discharge prevention effect in the vicinity of the contact point P can be acquired.

  In addition, when providing a semiconductive layer in the area | region 200 mm or more, in order to acquire a reliable effect, it is preferable to set the contact point P for every 200 mm. By setting the semiconductive layer 6 as described above, the partial discharge start voltage between the adjacent segment coils 4 and 5 in these regions can be increased to 1000 V or more.

  The semiconductive layer 6 can be set very thin as compared with a conventional insulating coating layer provided to prevent partial discharge. For this reason, partial discharge can be effectively prevented without increasing the weight and cost of the stator.

  In the above-described embodiment, the segment coils 4, 5 or 24, 25 belonging to different phases of the electric motor have been described. However, in reality, segment coils belonging to three phases are mounted in each slot, and between these segment coils belonging to different phases. The embodiment described above is applied to each structure.

  The scope of the present invention is not limited to the embodiment described above. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  The partial discharge between the coils can be effectively prevented without reducing the space factor of the stator employing the segment coil.

DESCRIPTION OF SYMBOLS 1 Stator 2 Annular core 3 Slot 4 Segment coil 4a Coil end part 4c Coil end part 5 Segment coil 5a Coil end part 5c Coil end part 6 Semiconductive layer 9 Insulation coating layer P Contact point

Claims (7)

A stator comprising a plurality of slots formed in the inner peripheral portion of the annular core, and a plurality of segment coils mounted in the plurality of slots,
On the outer periphery of each coil end portion extending from the slot of each segment coil provided with an insulating coating layer, a semiconductive layer continuous over a predetermined length range is provided,
The plurality of segment coils include a first segment coil belonging to a first phase and a second segment coil belonging to a second phase different from the first phase and disposed in proximity to the first segment coil. ,
The stator configured to contact the semiconductive layer of the first segment coil and the semiconductive layer of the second segment coil at at least one point. The semiconductive layer has a thickness of 5 μm or more and a surface resistivity of 1 × 10 ³ to 1 × 10 ⁹ Ω / sq.
The semiconductive layers of the segment coils arranged close to each other are formed so as to face each other in both directions along the axis of the segment coil at least in the region equal to or larger than the maximum sectional width of the segment coil with the contact point as the center. The stator according to claim 1.   The stator according to claim 1, wherein the semiconductive layer is configured by mixing conductive particles in a resin material. The stator according to any one of claims 1 to 3, wherein the semiconductive layer is made of a conductive resin provided on an outer peripheral portion of the segment coil . The stator according to any one of claims 1 to 3, wherein the semiconductive layer is formed of a tape material or a tube material having semiconductivity provided on an outer peripheral portion of each segment coil .   The stator according to any one of claims 1 to 5, wherein the semiconductive layer is not provided near a connection end of each segment coil.   The segment coil used for the stator of any one of Claims 1-6.

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