Stator for rotary electrical machine

Abstract

This stator for a rotary electric machine comprises a stator core, a slot that is provided in the stator core and has a plurality of layers, and a coil wound around the slot. The coil has a plurality of conductors. The plurality of conductors are respectively inserted into the plurality of layers in a radial direction. An insulating coating of the conductors that are inserted into at least two adjacent layers in the plurality of layers and have the same potential is thicker than the insulating coating of the conductors that are inserted into other layers and have a lower potential than the conductors having the same potential.

Description

Rotating electric machine stator

[0001] The present invention relates to a stator for a rotating electrical machine.

[0002] Electric vehicles require not only high efficiency and high power density of rotating electrical machines, but also high voltage resistance to facilitate rapid charging of batteries. One method for achieving high voltage resistance is to thicken the insulating coating, such as an enamel coating. Regarding thickening the insulating coating, Patent Literature 1 discloses an insulation design technology that addresses voltage propagation delays by changing the material and thickness of the insulating coating depending on the voltage distribution rate.

[0003] Japanese Patent Application Publication No. 11-220848

[0004] The resin insulating material used in the insulating coating has low thermal conductivity, so thickening the coating increases thermal resistance. Therefore, even if the technology described in Patent Document 1 is used, problems arise such as reduced cooling performance and increased copper loss, resulting in reduced motor efficiency.

[0005] A stator for a rotating electric machine comprising: a stator core; slots provided in the stator core and having a plurality of layers; and coils wound around the slots, wherein the coils have a plurality of conductors, which are inserted radially into the plurality of layers, and the insulating coatings of the conductors of the same potential inserted into at least two adjacent layers in the plurality of layers are thicker than the insulating coatings of the conductors of the same potential inserted into other layers.

[0006] According to the present invention, it is possible to provide a stator for a rotating electrical machine that is low cost, has good insulation properties, high voltage resistance, good cooling properties, and prevents a decrease in motor efficiency.

[0007] Schematic diagram of a rotating electric machine Schematic diagram of a stator for a rotating electric machine Configuration diagram of conductors inserted into slots according to one embodiment of the present invention and modified examples Second modified example and third modified example Results of a comparison test between the present invention and a comparative example

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (One embodiment and overall configuration) (FIGS. 1 and 2) In the following description of the present invention, "axial direction" refers to the direction along the rotation axis of the rotating electric machine 10. Furthermore, "circumferential direction" refers to the direction along the rotation direction of the rotating electric machine 10. "Radial direction" refers to the radial direction (radial direction) when the rotation axis of the rotating electric machine 10 is the center. "Inner peripheral side" refers to the radially inside (inner diameter side), and "outer peripheral side" refers to the opposite direction, i.e., the radially outside (outer diameter side).

[0011] The rotating electric machine 10 is an electric motor used in, for example, a hybrid vehicle. The rotating electric machine 10 is composed of a housing 50, a stator 20, a stator core 21, a stator coil 60, and a rotor 11.

[0012] The stator 20 is fixed to the inner periphery of the housing 50. The rotor 11 is rotatably supported on the inner periphery of the stator 20. The housing 50 is formed into a cylindrical shape by cutting an iron-based material such as carbon steel, by casting steel or an aluminum alloy, or by pressing.

[0013] A liquid cooling jacket 130 is fixed to the outer periphery of the housing 50. The liquid cooling jacket 130 houses bearings 144 and 145 therein.

[0014] The stator 20 includes a stator core 21 and a stator coil 60. The stator core 21 is formed by laminating thin silicon steel plates. The stator coil 60 is wound around a number of slots 15 provided on the inner periphery of the stator core 21.

[0015] The heat generated from the stator coil 60 is not only dissipated to the outside through the cooling paths provided between the coils 60, but is also transferred to the housing 50 through the stator core 21, and is dissipated by the refrigerant circulating within the liquid cooling jacket 130.

[0016] The rotor 11 has a rotor core 12 and a rotating shaft 13. The rotor core 12 is formed by laminating thin silicon steel plates. The rotating shaft 13 is fixed to the center of the rotor core 12. The rotating shaft 13 is rotatably held by bearings 144 and 145 attached to a liquid cooling jacket 130, and rotates at a predetermined position within the stator 20 facing the stator 20. The rotor 11 is provided with permanent magnets 18 and end rings (not shown).

[0017] To assemble the rotating electric machine 10, the stator 20 is inserted into the housing 50 and attached to the inner peripheral wall of the housing 50 in advance. Then, the rotor 11 is inserted into the stator 20. Then, the rotating shaft 13 is fitted with the bearings 144, 145 and assembled to the liquid cooling jacket 130, thereby assembling the rotating electric machine 10.

[0018] The stator 20 has a stator core 21 and stator coils 60 wound in a number of slots 15 provided on the inner periphery of the stator core 21. The stator coil 60 has a plurality of coil conductors with insulating coatings having a substantially rectangular cross section. The stator coil 60 also has a voltage applying section 22. The plurality of coil conductors are inserted radially through the plurality of layers of the slots.

[0019] Furthermore, insulating paper 301 is disposed in each slot 15 to ensure electrical insulation and adhesion between the stator core 21 and the stator coil 60. The insulating paper 301 is, for example, a resin composition, and is formed into a rectangular or U-shape so as to wrap the copper wire.

[0020] The stator coils 60 are formed by inserting and welding the segment-shaped coils into the slots 15 in which the insulating paper 301 is arranged. Annular insulating paper 300 is provided between the stator coils 60 in the circumferential direction of the stator core 21, ensuring insulation between the stator coils 60.

[0021] The coil 60 is fixed by impregnating the slot 15 with fixing varnish 70 and heating it. If the insulating paper 301 is foam adhesive insulating paper, the coil 60 is fixed by heating.

[0022] The coil insulation of the rotating electric machine 10 is applicable not only to permanent magnet types but also to induction types, synchronous reluctance types, claw pole types, etc. Also, although the winding type of the rotating electric machine 10 is a wave winding type, any winding type with similar characteristics is applicable. Also, although the rotating electric machine 10 has been described as an internal rotor type, it is equally applicable to an external rotor type.

[0023] (FIGS. 3 and 4) The present invention is applied to a conductor 601 in which adjacent coil conductors 601 with approximately the same potential are inserted in n layers within a slot, where n is an integer equal to or greater than 2. As an example, the present invention will be described using a configuration example in which eight coil conductors 601 are inserted within each slot provided in the stator core 21.

[0024] The slot has a total of eight layers, with the bottom side of the drawing being the outermost diameter side, and the top side of the drawing being the innermost diameter side, with the first layer, second layer, third layer, etc. The thickness of the insulating coating 602 of the coil conductor 601 in the first and second layers is equal. The thickness of the insulating coating 602 of the coil conductor 601 in the third and fourth layers is equal. Note that the thickness of the insulating coating of the connecting wire (not shown) that crosses from the second layer to the third layer, which has approximately unequal potentials, is equal to the thickness of the insulating coating of the coil conductor 601 in the layer with the thicker insulating coating 602.

[0025] The spacing between the coil conductors 601 with approximately the same potential, for example, the spacing between the coil conductor 601 in the first layer and the coil conductor 601 in the second layer, or the spacing between the coil conductor 601 in the third layer and the coil conductor 601 in the fourth layer, is narrower than the spacing between the other coil conductors, thereby improving the space factor of the coil conductor 601 inserted into the slot having multiple layers.

[0026] Between the coil conductors 601 inserted into the slots, a refrigerant flow path 800 is provided between the coil conductors 601 having the same potential inserted in at least two adjacent layers and the conductors 601 having a lower potential inserted in other layers.

[0027] 3(a) shows the configuration in which the output coil of the voltage application unit 22 (FIG. 2), which is the input unit, is arranged on the first layer, and the first and second layers used coil conductors 601 with insulating coating 602 having a thickness of 200 μm. The third and fourth layers, which are close to the neutral point, used coil conductors 601 with insulating coating 602 having a thickness of 140 μm. The fifth to eighth layers used coil conductors 601 with insulating coating 602 having a thickness of 90 μm.

[0028] In this way, the coil conductors 601 inserted in at least two adjacent layers with the same potential at the position where the voltage applying unit 22 is placed in the slot have thick insulating coatings 602, and the voltage sharing rate (potential difference) between the coil conductors 601 inserted in other layers located radially away from that layer and with lower potentials is small, so the insulating coatings 602 are made thin.

[0029] In this way, by thinning the insulating coating 602 of the coil conductor 601 inserted near the neutral point, space within the slot is secured while maintaining insulation, and the cross-sectional area of ​​the cooling passage between the coil conductors 601 within the slot can be increased, resulting in a refrigerant flow path 800 with a sufficient flow path width. Furthermore, space can be secured between coil conductors with different potentials at the coil end (not shown), improving insulation. In other words, the potential propagation delay reduces the potential difference between the multiple coil conductors 601 from the lead wire to the neutral point, providing a stator 20 of a rotating electric machine 10 with high voltage resistance and excellent cooling performance without sacrificing the space factor and voltage resistance of the coil conductors 601 within the slot. The refrigerant flow path 800 is, for example, an oil-cooled cooling oil passage.

[0030] 3(b), in a stator 20 in which lead coil conductors 601 connected to the voltage supply unit 22 are arranged on the first and eighth layers, coils with an insulating coating 602 having a thickness of 200 μm are used for the coil conductors 601 on the first and second layers and the coil conductors 601 on the seventh and eighth layers. Coil conductors 601 on the third and fourth layers, which are close to the neutral point, and the coil conductors 601 on the fifth and sixth layers, which are close to the neutral point, are used for the coil conductors 601. A refrigerant flow path 800 is provided in the gap between each coil conductor 601.

[0031] Regarding the position of the conductor 601 of the lead coil of the voltage supply unit 22 (Figure 2), it is preferable to provide it in the outermost layer from the viewpoint of cooling, and as mentioned above, the coil conductors 601 of the same potential inserted in at least two adjacent layers in a plurality of layers are provided in a position closer to the voltage supply unit 22 than the coil conductors 601 of lower potential inserted in the other layers, but they may also be provided in the innermost layer.

[0032] 4(a), in a stator 20 in which lead coils (not shown) are arranged on the first layer, the coil conductors 601 in the first and second layers have an insulating coating 602 with a thickness of 200 μm. The coil conductors 601 in the third and fourth layers, which are close to the neutral point, have an insulating coating 602 with a thickness of 140 μm. The coil conductors 601 in the fifth to eighth layers each have an insulating coating 602 with a thickness of 90 μm. These coil conductors 601 are fixed in place by a resin composition 700, for example, an epoxy resin containing silica and alumina as fillers.

[0033] 4(b), in a stator 20 in which lead coils (not shown) are arranged in the first and eighth layers, the coil conductors 601 in the first and second layers and the coil conductors 601 in the seventh and eighth layers have insulating coatings 602 with a thickness of 200 μm. The coil conductors 601 in the third and fourth layers, and the fifth and sixth layers, which are close to the neutral point, have insulating coatings 602 with a thickness of 140 μm. These coil conductors 601 are fixed in place by a resin composition 700 made of an epoxy resin containing silica and alumina as fillers.

[0034] The insulating coating 602 used in the configuration of the present invention may be made of any suitable material, as long as it is a resin with electrical insulating properties. Examples of resins that can be used for the insulating coating 602 include so-called enamel resins such as polyvinyl formal, polyester, polyesterimide, polyamideimide, and polyimide; engineering plastics such as nylon and polyoxymethylene; and super-engineering plastics such as polyphenylene sulfide, polyetheretherketone, and polytetrafluoroethylene. Among these, enamel resins such as polyamideimide and polyimide, and engineering plastics such as polyphenylene sulfide and polyetheretherketone are preferred from the viewpoints of heat resistance, processability, and voltage resistance. The resin used for the insulating coating 602 may be a single resin or multiple resins may be used in layers. The resin used for the insulating coating 602 may be multi-layered using conventional techniques such as baking coating or multi-layer extrusion. While coil conductors 601 with the same potential are described as being adjacent to each other, the potentials may also be substantially equal.

[0035] Furthermore, when the space between the coil conductors 601 is used as the refrigerant flow path 800, it is preferable to use a foam adhesive to fix the coil conductors 601 in the slots. Specific examples include insulating paper with a multilayer structure having a foam adhesive layer on the surface or between layers, and bobbins with a foam adhesive applied to the surface. These are arranged between the stator core 21 and the coil conductors 601 and have a structure that does not block the gaps between the coil conductors 601.

[0036] Furthermore, a resin composition 700 containing a thermosetting resin and a ceramic filler may be used as a heat transfer medium between the coil conductors 601. Examples of thermosetting resins include epoxy resin, unsaturated polyester resin, and vinyl ester resin. Among these, epoxy resin and vinyl ester resin are more preferable from the viewpoint of heat resistance. The ceramic filler is not particularly limited, and examples include talc, silica, alumina, titania, boron nitride, and aluminum nitride. Among these, silica, alumina, and boron nitride are preferable from the viewpoint of thermal conductivity and stability. Furthermore, a mixture of these ceramic fillers may be used.

[0037] (Fig. 5) A line voltage life test was carried out to verify the effects of the present invention for the configurations of the present invention shown in Fig. 3 and Fig. 4 and for Comparative Examples 1 and 2. Example 1 has the configuration shown in Fig. 3(a), Example 2 has the configuration shown in Fig. 3(b), Example 3 has the configuration shown in Fig. 4(a), and Example 4 has the configuration shown in Fig. 4(b).

[0038] In Comparative Example 1, the lead coil conductors of the stator 20 were arranged on the first layer, and all of the coil conductors had an insulation coating thickness of 200 μm, and the coil conductors were secured with foam adhesive insulating paper. In Comparative Example 2, the lead coil conductors of the stator 20 were arranged on the first layer, and all of the coil conductors had an insulation coating thickness of 90 μm, refrigerant channels were provided between the coil conductors, and the coil conductors were secured with foam adhesive insulating paper. In this verification test, 5 kV at 500 Hz was applied to the U-phase lead wire, and the V-phase was grounded. The neutral point was also disconnected beforehand.

[0039] 5 showing the results, it was confirmed that in a long-term voltage application test to verify the time required for dielectric breakdown, the stators 20 of Examples 1 to 4 had a longer life than Comparative Example 2, although there was no difference from Comparative Example 1. Furthermore, while it was possible to flow cooling oil between the coil conductors in Examples 1 and 2, the spacing between the coil conductors in Comparative Example 1 was so narrow that cooling oil could not flow, making cooling by cooling oil difficult.

[0040] Furthermore, although not shown, regarding the cooling of the coil conductor 601 after energization, it took 30 minutes for the temperature to drop from 200°C to 25°C in Examples 3 and 4, whereas it took 50 minutes under the same conditions in Comparative Example 1. Therefore, it was confirmed that in Examples 3 and 4, the placement of a thermosetting resin containing ceramic filler between the coil conductors provides a heat dissipation effect.

[0041] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0042] (1) A stator 20 for a rotating electric machine 10 includes a stator core 21, slots 15 provided in the stator core 21 and having multiple layers, and coils 60 wound around the slots 15, wherein the coils 60 have multiple conductors 601, each of which is inserted radially through the multiple layers, and the insulating coating of the conductors of the same potential inserted in at least two adjacent layers in the multiple layers is thicker than the insulating coating of the conductors of a lower potential inserted in the other layers. This configuration makes it possible to provide a stator 20 for a rotating electric machine 10 with excellent insulation and cooling properties.

[0043] (2) The conductors 601 inserted into the slots are each provided with a coolant flow path 800. This configuration improves cooling performance.

[0044] (3) The coolant flow path 800 is provided between conductors of the same potential that are inserted through at least two adjacent layers of the plurality of layers and conductors of a lower potential that are inserted through other layers, thereby forming a wide flow path.

[0045] (4) The coil 60 includes a voltage applying unit 22, and the conductors 601 of the same potential inserted through at least two adjacent layers among the plurality of layers are located closer to the voltage applying unit 22 than the conductors 601 of the same potential inserted through the other layers. In this way, a conductor with a thick insulating coating corresponds to the voltage applying unit 22, ensuring high voltage resistance.

[0046] (5) A resin composition 700 is provided between the conductors 601 that are inserted through the layers, and the resin composition 700 contains a thermosetting resin and a ceramic filler. By doing so, even if the refrigerant flow path 800 is not formed, the configuration of the present invention can ensure heat dissipation.

[0047] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted.

[0048] REFERENCE SIGNS LIST 10 Rotating electric machine 11 Rotor 12 Rotor core 13 Rotating shaft 15 Slot 18 Permanent magnet 20 Stator 21 Stator core 22 Power supply unit 50 Housing 60 Stator coil 61 Anti-welding side coil end 62 Welding side coil end 70 Fixing varnish 130 Liquid cooling jacket 144 Bearing 145 Bearing 210 Stainless steel 300 Annular insulating paper 301 Insulating paper 601 Coil conductor 602 Coil insulating coating 700 Resin composition 800 Refrigerant flow path

Claims

1. A stator for a rotating electric machine comprising: a stator core; slots having a plurality of layers provided in the stator core; and coils wound in the slots, wherein the coils have a plurality of conductors, the plurality of conductors are inserted radially into the plurality of layers, and the insulating coating of the conductors of the same potential inserted in at least two adjacent layers in the plurality of layers is thicker than the insulating coating of the conductors of the same potential inserted in other layers.

2. A stator for a rotating electric machine according to claim 1, wherein a coolant flow passage is provided between each of the plurality of conductors inserted into the slots.

3. A stator for a rotating electric machine as described in claim 2, wherein the coolant flow path is provided between the conductors of the same potential that are inserted through at least two adjacent layers of the plurality of layers, and the conductors of a lower potential than the conductors of the same potential that are inserted through the other layers.

4. A stator for a rotating electric machine as described in claim 1, wherein the coil is provided with a voltage supply section, and the conductors of the same potential inserted through at least two adjacent layers in the plurality of layers are located closer to the voltage supply section than the conductors of a lower potential than the conductors of the same potential inserted through the other layers.

5. A rotating electric machine stator according to claim 1, wherein a resin composition is provided between the plurality of conductors inserted into the plurality of layers, the resin composition including a thermosetting resin and a ceramic filler.

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