Stator of rotary electric machine

Abstract

To provide a stator of a rotary electric machine which realizes low cost, insulation quality, a high voltage endurance property, coolability, and suppression of motor efficiency deterioration.SOLUTION: A stator of a rotary electric machine comprises: a stator core; a slot provided in the stator core and having a plurality of layers; and a coil wound around the slot. The coil has a plurality of conductors, the plurality of conductors are radially inserted into the plurality of layers, respectively, insulating films of at least two adjacent layers of the conductors at the same potential inserted into the plurality of layers are inserted into other layers and thicker than insulating films of the conductors at a potential lower than the conductors at the same potential.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Electric vehicles are required not only to have high efficiency and high output density of rotating electrical machines but also to have high withstand voltage accompanying rapid charging of batteries. One of the methods for increasing the withstand voltage is, for example, thickening an insulating film such as an enamel coating. Regarding the thickening of the insulating film, Patent Document 1 discloses a technique for insulation design that copes with the delay in voltage propagation by changing the material and thickness of the insulating film according to the voltage sharing ratio.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the resin insulating material used for the insulating film has a low thermal conductivity, the thermal resistance increases when the film is thickened. Therefore, even when the technique described in Patent Document 1 is used, there is a problem that the cooling performance deteriorates and the motor efficiency decreases due to an increase in copper loss.

Means for Solving the Problems

[0005] A stator of a rotating electrical machine including a stator core, a slot provided in the stator core and having a plurality of layers, and a coil wound around the slot, wherein the coil has a plurality of conductors, the plurality of conductors are inserted radially with respect to the plurality of layers, and in the plurality of layers, an insulating film of the conductors of the same potential inserted adjacent to at least two layers is thicker than an insulating film of the conductors of a lower potential than the conductors of the same potential inserted into other layers.

Effects of the Invention

[0006] According to the present invention, it is possible to provide a stator of a rotating electrical machine that realizes low cost, insulation, high withstand voltage, cooling, and suppression of motor efficiency degradation.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments 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 for the sake of clarity of explanation, omissions and simplifications are made as appropriate. The present invention can also be implemented in various other forms. Unless otherwise particularly limited, each component may be singular or plural.

[0009] The positions, sizes, shapes, ranges, etc. of the respective components shown in the drawings may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0010] (One embodiment and overall configuration) (FIG. 1, FIG. 2) In the following description of the present invention, the "axial direction" shall refer to the direction along the rotation axis of the rotating electrical machine 10. Further, the "circumferential direction" shall refer to the direction along the rotation direction of the rotating electrical machine 10. The "radial direction" shall refer to the radial direction (radius direction) when centered on the rotation axis of the rotating electrical machine 10. The "inner peripheral side" refers to the inner side in the radial direction (inner diameter side), and the "outer peripheral side" refers to the opposite direction, i.e., the outer side in the radial direction (outer diameter side).

[0011] The rotating electrical machine 10 uses, for example, an electric motor used in a hybrid vehicle. The rotating electrical 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 peripheral side of the housing 50. The rotor 11 is rotatably supported on the inner peripheral side of the stator 20. The housing 50 is formed into a cylindrical shape by cutting an iron-based material such as carbon steel, or by casting cast steel or an aluminum alloy, or by press working.

[0013] A liquid cooling jacket 130 is fixed to the outer peripheral side of the housing 50. The liquid cooling jacket 130 houses bearings 144, 145.

[0014] The stator 20 has a stator core 21 and a stator coil 60. The stator core 21 is formed by laminating thin silicon steel sheets. The stator coil 60 is wound around slots 15 provided in a large number on the inner peripheral portion of the stator core 21.

[0015] The heat generated from the stator coil 60 is not only radiated to the outside through the cooling channels provided between the coils 60, but also transferred to the housing 50 through the stator core 21, and is radiated by the refrigerant flowing through 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 sheets. 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 the liquid-cooling jacket 130, and rotates at a position facing the stator 20 at a predetermined position within the stator 20. The rotor 11 is provided with permanent magnets 18 and an end ring (not shown).

[0017] For the assembly of the rotating electrical machine 10, the stator 20 is first inserted inside the housing 50 and attached to the inner peripheral wall of the housing 50. Then, the rotor 11 is inserted into the stator 20. And by assembling it to the liquid-cooling jacket 130 such that the bearings 144 and 145 are fitted onto the rotating shaft 13, the rotating electrical machine 10 is assembled.

[0018] The stator 20 has a stator core 21 and a stator coil 60 wound around a number of slots 15 provided in the inner peripheral portion of the stator core 21. The stator coil 60 has a plurality of coil conductors having an insulating coating with a substantially rectangular cross-section. Also, the stator coil 60 has a power supply portion 22. The plurality of coil conductors are inserted radially through the plurality of layers of the slots respectively.

[0019] Also, 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 square shape, a U-shape, etc. so as to wrap the copper wire.

[0020] The stator coil 60 is formed by inserting and welding segment-shaped coils into the slots 15 in which the insulating paper 301 is disposed. In the circumferential direction of the stator core 21, annular insulating paper 300 is provided between the stator coils 60 to ensure insulation between the stator coils 60.

[0021] By impregnating the fixing varnish 70 into the slot 15 and heating it, the coil 60 is fixed. Also, in the case of the foamed adhesive insulating paper, the coil 60 is fixed by heating the insulating paper 301.

[0022] Note that the coil insulation of the rotating electrical machine 10 is applicable not only to the permanent magnet type but also to the induction type, synchronous reluctance, claw pole type, etc. Also, in the winding method of the rotating electrical machine 10, although it is the wave winding method, any winding method having the same characteristics is applicable. Further, although the rotating electrical machine 10 is described as an inner-rotating type, it is similarly applicable to an outer-rotating type.

[0023] (Figs. 3, 4) The present invention is applied to the conductor 601 in which adjacent coil conductors 601 having substantially equal potentials are inserted in n layers in the slot. Note that n is an integer of 2 or more. As an example, the present invention will be described using a configuration example having eight coil conductors 601 in each slot provided in the stator core 21.

[0024] In the slot, with the lower side of the drawing being the outermost diameter side, the first layer, the second layer, the third layer... are provided, and with the upper side of the drawing being the innermost diameter side, there are a total of eight layers. The thicknesses of the insulating coatings 602 of the coil conductors 601 in the first layer and the second layer are equal. The thicknesses of the insulating coatings 602 of the coil conductors 601 in the third layer and the fourth layer are equal. Note that the insulating coating thickness of a non-illustrated crossover wire from the second layer to the third layer where the potentials are not substantially equal is equivalent to the insulating coating thickness of the coil conductor 601 in the layer with the thicker insulating coating 602.

[0025] The intervals between the coil conductors 601 having substantially equal potentials, for example, the interval between the coil conductor 601 in the first layer and the coil conductor 601 in the second layer, and the interval between the coil conductor 601 in the third layer and the coil conductor 601 in the fourth layer, are made narrower than the intervals between the other coil conductors. By doing so, the occupation ratio of the coil conductors 601 inserted into the slot having a plurality of layers can be improved.

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

[0027] The configuration of FIG. 3(a) is a state in which the outlet coil of the charging unit 22 (FIG. 2), which is the input unit, is arranged in the first layer. For the first layer and the second layer, coil conductors 601 with an insulating film 602 having a thickness of 200 μm were used. In the third layer and the fourth layer close to the position of the neutral point, coil conductors 601 with an insulating film 602 having a thickness of 140 μm were used. From the fifth layer to the eighth layer, coil conductors 601 with an insulating film 602 having a thickness of 90 μm were used.

[0028] In this way, for at least two adjacent coil conductors 601 inserted in the layer where the charging unit 22 is arranged in the slot and having the same potential, the insulating film 602 is thickened, and the voltage sharing ratio (potential difference) between the coil conductors 601 inserted into other layers provided far from that layer in the radial direction and having a lower potential is reduced, so the insulating film 602 is made thin.

[0029] In this way, by making the insulating film 602 of the coil conductor 601 inserted near the neutral point thin, while maintaining insulation, a space in the slot can be secured, the cross-sectional area of the cooling path provided between the coil conductors 601 in the slot can be widened, and a refrigerant flow path 800 with a secured flow path width can be provided. Also, since a space between coil conductors with different potentials in the coil end portion (not shown) can be secured, the insulation is improved. That is, by delaying the propagation of the potential, the potential difference between a plurality of coil conductors 601 from the outlet line to the neutral point is reduced, and without sacrificing the occupancy rate and withstand voltage of the coil conductors 601 in the slot, a stator 20 of a rotating electrical machine 10 with high withstand voltage and high cooling performance can be provided. Note that the refrigerant flow path 800 is, for example, an oil-cooling oil flow path.

[0030] (First Modified Example) In Fig. 3(b), in the stator 20 where the conductor 601 of the output coil connected to the charging unit 22 is arranged in the first layer and the eighth layer, coils with an insulating film 602 having a thickness of 200 μm were used for the coil conductors 601 in the first layer and the second layer, and the coil conductors 601 in the seventh layer and the eighth layer. For the coil conductors 601 in the third layer and the fourth layer close to the neutral point, and the coil conductors 601 in the fifth layer and the sixth layer, coil conductors 601 with an insulating film 602 having a thickness of 140 μm were used. 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 output coil of the charging unit 22 (Fig. 2), it is preferably provided in the outermost diameter side layer from the viewpoint of cooling. As described above, the coil conductors 601 of the same potential inserted adjacent to at least two layers in a plurality of layers are provided closer to the charging unit 22 than the coil conductors 601 of a lower potential inserted in other layers, but it may also be provided at the position of the innermost diameter side layer.

[0032] (Second Modified Example) In Fig. 4(a), in the stator 20 where an output coil (not shown) is arranged in the first layer, coil conductors 601 with an insulating film 602 having a thickness of 200 μm were used for the coil conductors 601 in the first layer and the second layer. For the coil conductors 601 in the third layer and the fourth layer close to the neutral point, coil conductors 601 with an insulating film 602 having a thickness of 140 μm were used. For the coil conductors 601 from the fifth layer to the eighth layer, coil conductors 601 with an insulating film 602 having a thickness of 90 μm were used respectively. These coil conductors 601 are fixed by a resin composition 700 of an epoxy resin containing silica and alumina as fillers, for example.

[0033] (Third Modified Example) In Fig. 4(b), in the stator 20 where the outlet coils (not shown) are arranged in the first layer and the eighth layer, the coil conductors 601 in the first layer and the second layer, and the coil conductors 601 in the seventh layer and the eighth layer use the coil conductors 601 with an insulating coating 602 having a thickness of 200 μm. In the third layer and the fourth layer, and the fifth layer and the sixth layer close to the neutral point, the coil conductors 601 with an insulating coating 602 having a thickness of 140 μm are used. These coil conductors 601 are fixed by a resin composition 700 of an epoxy resin containing silica and alumina as fillers.

[0034] Note that the material of the insulating coating 602 used in the configuration of the present invention is not particularly limited as long as it is a resin having electrical insulation properties. Examples of the resin used for the insulating coating 602 include so-called enamel resins such as polyvinyl formal, polyester, polyester imide, polyamide imide, and polyimide, engineering plastics such as nylon and polyoxymethylene, and super engineering plastics such as polyphenylene sulfide, polyether ether ketone, and polytetrafluoroethylene. Among these, from the viewpoints of heat resistance, processability, and withstand voltage, enamel resins such as polyamide imide and polyimide, and engineering plastics such as polyphenylene sulfide and polyether ether ketone are desirable. Further, the resin used for the insulating coating 602 may be used alone or in multiple layers. Also, the means for forming the insulating coating 602 in multiple layers may be existing methods such as baking coating and multilayer extrusion. Also, although it has been described above that the coil conductors 601 having the same potential are adjacent to each other, it may be the case where the potentials are substantially equal.

[0035] Also, as a method for fixing the coil conductor 601 in the slot, for example, when using the space between the coil conductors 601 as the refrigerant flow path 800, it is preferable to use a foam adhesive. Specifically, examples include insulating paper having a multilayer structure with a foam adhesive layer on the surface or between layers, and bobbins coated with a foam adhesive on the surface. These are arranged between the stator core 21 and the coil conductor 601 and have a structure that does not block the gap between the coil conductors 601.

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

[0037] (Fig. 5) For the configuration of the present invention shown in Figs. 3 and 4 and Comparative Examples 1 and 2, an interphase voltage endurance test was carried out to verify the effects of the present invention. 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, in the stator 20 in which the outgoing coil conductors are arranged in the first layer, all the coil conductors have an insulating coating thickness of 200 μm, and the coil conductors are fixed with foam adhesive insulating paper. Also, in Comparative Example 2, in the stator 20 in which the outgoing coil conductors are arranged in the first layer, all the coil conductors have an insulating coating thickness of 90 μm, a refrigerant flow path is provided between the coil conductors, and the coil conductors are fixed with foam adhesive insulating paper. In this verification test, 5 kV was applied to the U-phase outgoing line at 500 Hz, and the V-phase was grounded. Also, the neutral point was cut off in advance.

[0039] According to the table of FIG. 5 showing the results, although there was no difference between the stators 20 of Example 1 to Example 4 and Comparative Example 1 in the long-term voltage application test for verifying the time required for dielectric breakdown, it was confirmed that they had a longer lifespan than Comparative Example 2. Further, in Example 1 and Example 2, cooling oil can flow between the coil conductors, but in Comparative Example 1, the interval between the coil conductors is narrow from the start and the cooling oil does not flow, making it difficult to cool with the cooling oil.

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

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

[0042] (1) A stator 20 of a rotating electrical machine 10 including a stator core 21, a slot 15 provided in the stator core 21 and having a plurality of layers, and a coil 60 wound around the slot 15, wherein the coil 60 has a plurality of conductors 601, the plurality of conductors 601 are respectively inserted in the radial direction with respect to the plurality of layers, and in the plurality of layers, the insulating films of the conductors of the same potential inserted adjacent to at least two layers are thicker than the insulating films of the conductors of a potential lower than that of the conductors of the same potential inserted in other layers. By doing so, it is possible to provide a stator 20 of a rotating electrical machine 10 excellent in insulation and cooling properties.

[0043] (2) Refrigerant flow paths 800 are respectively provided between the plurality of conductors 601 inserted into the slot. By doing so, the cooling performance can be improved.

[0044] (3) The refrigerant flow path 800 is provided between a conductor of the same potential inserted through at least two adjacent layers among a plurality of layers and a conductor of a potential lower than that of the conductor of the same potential inserted through other layers. By doing so, a wide flow path can be formed.

[0045] (4) The coil 60 includes a charging unit 22. Among a plurality of layers, the conductors 601 of the same potential inserted through at least two adjacent layers are provided closer to the charging unit 22 than the conductors 601 of a potential lower than that of the conductors of the same potential inserted through other layers. By doing so, a conductor with a thick insulating coating can be made to correspond to the charging unit 22, and high withstand voltage performance can be ensured.

[0046] (5) A resin composition 700 is provided between the plurality of conductors 601 inserted through the plurality of layers, and the resin composition 700 includes a thermosetting resin and a ceramic filler. By doing so, heat dissipation performance can be ensured with the configuration of the present invention even when the refrigerant flow path 800 is not formed.

[0047] Note that the present invention is not limited to the above-described embodiments, and various modifications and combinations with other configurations can be made without departing from the gist thereof. Further, the present invention is not limited to those having all the configurations described in the above embodiments, and also includes those in which a part of the configuration is deleted.

Explanation of Reference Numerals

[0048] 10 Rotating Electric Machine 11 Rotor 12 Rotor Core 13 Rotating Shaft 15 Slot 18 Permanent Magnet 20 Stator 21 Stator Core 22 Charging Unit 50 Housing 60 Stator Coil 61 Anti-Welding Side Coil End 62 Welding Side Coil End 70 Adhesive Varnish 130 Liquid Cooling Jacket 144 bearings 145 bearings 210 stainless steel 300 annular insulating paper 301 insulating paper 601 coil conductor 602 coil insulation coating 700 resin composition 800 refrigerant flow path

Claims

1. A stator core; a slot provided in the stator core and having a plurality of layers; A stator of a rotating electric machine comprising: The coil has a plurality of conductors. The plurality of conductors are inserted radially through the plurality of layers, In the plurality of layers, the insulating coating of the conductors having the same potential that are inserted in at least two adjacent layers is thicker than the insulating coating of the conductors having a lower potential than the conductors having the same potential that are inserted in the other layers. Stator of a rotating electric machine.

2. 2. The stator of a rotating electric machine according to claim 1, A coolant flow path is provided between each of the conductors inserted into the slot. Stator of a rotating electric machine.

3. 3. The stator of a rotating electric machine according to claim 2, The coolant flow path is provided between the conductors having the same potential that are inserted through at least two adjacent layers of the plurality of layers, and the conductors having a lower potential than the conductors having the same potential that are inserted through the other layers. Stator of a rotating electric machine.

4. 2. The stator of a rotating electric machine according to claim 1, The coil includes a voltage applying unit, The conductors having the same potential, which are inserted through at least two adjacent layers among the plurality of layers, are provided at a position closer to the voltage application unit than the conductors having a lower potential than the conductors having the same potential, which are inserted through the other layers. Stator of a rotating electric machine.

5. 2. The rotating electric machine according to claim 1, A resin composition is provided between the plurality of conductors that are inserted through the plurality of layers, The resin composition contains a thermosetting resin and a ceramic filler. Stator of a rotating electric machine.

Images