WO2016035534A1

WO2016035534A1 - Stator for rotary electric machine and rotary electric machine provided with same

Info

Publication number: WO2016035534A1
Application number: PCT/JP2015/072983
Authority: WO
Inventors: 源三岩城; 萩原　修哉
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2014-09-05
Filing date: 2015-08-17
Publication date: 2016-03-10
Also published as: JP2016059090A

Abstract

Provided are: a stator for a rotary electric machine comprising a highly reliable insulation system which is capable of maintaining a high voltage resistance characteristic, and in which a crack is not easily generated on a fixing varnish even when the temperature of a stator coil rises and a high voltage is applied; and a rotary electric machine provided with said stator. For a stator for a rotary electric machine comprising a coil 3 having an insulation coating; and a core 1 provided with a plurality of slots 4 in which the coil is disposed, a composite resin in which a thermoplastic resin 52 is contained in a thermosetting resin 51 is used for the slot fixing varnish.

Description

A stator for a rotating electrical machine and a rotating electrical machine including the stator.

The present invention relates to a stator of a high-voltage rotating electrical machine that is operated with a driving voltage in the vicinity of 1 kV, and a rotating electrical machine including the stator.

Rotating electric machines closely related to industry and life are basic equipment that supports modern society. In particular, in hybrid vehicles and electric vehicles that are spreading from the viewpoint of protecting the global environment, the motor of the power source is required to be smaller and lighter from the viewpoint of securing the posting space and improving fuel efficiency by reducing the weight.

Stator insulation of power motors for hybrid vehicles and electric vehicles is an insulating paper (slot liner) inserted between the stator core / coil and between the different phase coils and a fixed varnish that fills the gaps and fixes the coil and slot liner to the core. (For example, refer patent document 1).

As a means to reduce the size of the power motor, it is conceivable to increase the driving voltage or increase the coil current density. However, both of these means lead to an increase in the load of coil insulation in the stator, and it is essential to design an insulation system corresponding to the size reduction. Become.

JP 2013-9493 A

In order to cope with the increase in voltage on the extension line of the prior art, the thickness of the slot liner is increased, and an insulation distance corresponding to the working voltage is secured. In this method, the coil space factor in the slot is increased. The coil current decreases due to a decrease. In order to compensate for this point, it is necessary to increase the coil current density, and an increase in coil temperature is inevitable.

Another method, increasing the coil current density, is accompanied by an increase in coil temperature as described above, and an increase in coil temperature is unavoidable in miniaturization of power motors for hybrid vehicles and electric vehicles.

On the other hand, a thermosetting resin is used for the fixing varnish used in the conventional stator insulation system in order to prevent the fixing force from being lowered even when the temperature rises during motor operation. There is a problem that the embrittlement of the resin is accelerated, cracks are generated in the fixed varnish layer, and the insulation reliability is lowered.

In view of the above prior art, the present invention provides a stator for a rotating electrical machine equipped with a highly reliable insulation system capable of maintaining a high withstand voltage characteristic in which cracks are not easily generated in a fixed varnish even when a stator coil temperature rises and a high voltage is applied. It is an object to provide a rotating electrical machine including

In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. For example, a stator for a rotating electrical machine including a coil having an insulating coating and a core provided with a plurality of slots in which the coils are arranged. In the present invention, a composite resin containing a thermoplastic resin in a thermosetting resin is used for the slot fixing varnish.

According to the present invention, it is possible to provide a stator for a rotating electrical machine that can reduce the deterioration of insulation reliability due to acceleration of embrittlement of the slot insulating fixed varnish accompanying the rise in stator coil temperature and crack generation, and a rotating electrical machine including the stator. It becomes possible.

Issues, configurations, and effects other than those described above will be clarified by the following description of embodiments.

Status lot configuration in the embodiment. The stator perspective view manufactured by the Example and the comparative example. The structure schematic diagram of the composite resin fixed varnish of an Example.

As a result of diligent examination of the above-mentioned problems, in the insulation system composed of a conventional thermosetting resin single phase, the insulation reliability decreases with the increase in the temperature of experience of the insulation system, and the degree of the decrease is the thermosetting property of the fixed varnish. The present inventors have found that it is strongly influenced by the resin and have reached the present invention.

In the present invention, it is necessary to provide ductility to the fixed varnish in order to construct a high-reliability insulation system corresponding to miniaturization of high-voltage motors for driving hybrid vehicles and electric vehicles by increasing drive voltage and coil current density. As a means for this, a composite resin in which a thermoplastic resin is contained in a thermosetting resin is used for the fixing varnish, thereby enabling miniaturization of a high-voltage motor such as a hybrid motor or a power motor for an electric vehicle.

The composite resin is composed of a sea-like matrix phase and an island-like dispersed phase, wherein the matrix phase is made of a thermosetting resin and the island-like dispersed phase is made of a thermoplastic resin.

In the composite resin, when a thermoplastic resin having poor ductility is combined with the thermosetting resin in the matrix phase, the effect of the present invention cannot be obtained. In the present invention, the thermoplastic resin in the composite resin is not It is necessary that the ductility is higher than that of the thermosetting resin of the matrix phase. A guideline for ductility can be represented by tensile elongation at break. In the present invention, a thermoplastic resin having a tensile elongation at break larger than that of the thermosetting resin of the matrix phase is used.

Further, by using a thermoplastic resin having a dielectric constant lower than that of the thermosetting resin in the matrix phase as the dispersed phase in the composite resin in the present invention, the dielectric constant of the fixed varnish is lowered and the partial discharge start voltage in the status lot is increased. Therefore, the motor drive voltage can be increased.

In addition, the use of a thermoplastic resin having a thermal expansion coefficient larger than that of the matrix phase thermosetting resin in the dispersed phase allows the fixed varnish layer to be formed only from the thermosetting resin as the coil temperature rises during motor operation. As a result of swelling from the fixed varnish and less void due to thermal shrinkage when the fixed varnish is cured, the thermal resistance from the coil to the core is reduced, that is, the coil cooling property is improved, and the coil temperature can be prevented from rising.

In the present invention, a thermoplastic resin satisfying at least one of the above properties (tensile elongation at break, dielectric constant, coefficient of linear expansion) is used as a composite resin for status lot insulating fixed varnish.

The following applies to a stator composed of a laminated core of a punched electromagnetic steel plate equivalent to 35A300 with a rated driving voltage of 300Vdc and current of 400 Arms, a three-phase 12-pole hybrid vehicle drive motor with an outer diameter of 245mm, an inner diameter of 200mm, and 72 slots. The present invention will be described with reference to Examples and Comparative Examples.

FIG. 1 shows a slot cross-sectional configuration of a stator core of a hybrid vehicle drive motor used in Examples and Comparative Examples. Four stator coils 3 formed of a flat enamel insulated wire are accommodated in the slot 4, and each stator coil 3 is electrically insulated by the slot liner 2. The slot liner 2 is a slot liner having a B-shaped cross section, which insulates each stator coil and insulates the stator coil 3 from the stator core 1 as described above.

The stator coil used was a rectangular enamel insulated wire in which a 0.05 mm thick polyamideimide insulating layer was coated on a rectangular conductor having a short side of 2.4 mm, a long side of 3.3 mm, and a corner chamfer radius of 0.5 mm.

For the slot liner, a three-layer laminated insulating paper of aramid paper / PET / aramid paper with a nominal thickness of 0.18 mm was used. Each layer of the slot liner is bonded with a urethane-based adhesive. The slot liner length was 100 mm, and a 3 mm slot liner was protruded from both end faces of the core slot to prevent creeping discharge between the stator core and the segment coil.

The slot has a substantially rectangular shape with a constant width in order to store the flat coil closely, and the width and the parallel part depth are 4.18 mm and 12.2 mm, respectively.

The stator is assembled by inserting a segment coil in which a flat enamel insulated wire is formed into a generally U shape after the slot liner is installed in the status lot. In consideration of assembly workability, the stator core / slot liner and slot liner / stator coil are assembled. There are gaps between them, as can be seen from the dimensional relationship of each member described above.

¡Elimination of this gap, and a fixed varnish is filled in the gap to fix the slot liner and stator coil to the slot.

Fig. 2 shows a perspective view of the stator after assembly. As described above, the stator 41 is manufactured by a rectangular wire segment winding method. FIG. 2 is a perspective view of the stator 41 after the housing 44 is fitted. A state in which the segment coil connecting portion that is straight when the slot liner is inserted for connecting the segment coil 42 is bent into a predetermined shape is shown.

Before segment coil welding, interlayer insulation paper was sandwiched between the stator coil layers on the weld side to ensure insulation between the stator coils. As the interlayer insulating paper, two sheets of the same insulating paper as the slot liner were used.

After welding and joining the segment coil ends, the stator is inverted so that the flanges of the segment coils are on the top, and the fixed varnish is poured into the slots from the upper end of the stator core slot, and the stator is heated to a predetermined temperature, held, and fixed The varnish was cured, and the slot liner and the stator coil were fixed to the slot, and the stators of Examples and Comparative Examples of the present invention were manufactured.

In filling the fixed varnish, a sufficient amount was poured so that no unfilled voids remained, and the work was performed while visually controlling the fixed varnish from the bottom end of the slot.

Using the above-mentioned stator manufacturing method as common conditions, composite resins having different dispersed phases and stators using them were made as prototypes.

Table 1 shows the thermoplastic resins used for the dispersed phases in the composite resins of Examples and Comparative Examples. Comparative Example 1 is a conventional epoxy-based thermosetting resin that does not contain a dispersed phase. The two-component mixed type has a viscosity after mixing of 0.9 mPa · s, a curing condition of 150 ° C. × 1 hour, and a glass transition temperature. It is an epoxy resin at 125 ° C. In Examples 1 to 3 and Comparative Example 2, each thermoplastic resin was combined with the epoxy resin of Comparative Example 1.

The composite ratios of the thermoplastic resin dispersed phases in the composite resins of Examples 1 to 3 and Comparative Example 2 were all kept constant at 15% (% by weight). The thermoplastic resins used in the composite resins of Examples 1 to 3 and Comparative Example 2 were 10 μm or less obtained by mechanically pulverizing and sieving bulk thermoplastic resins having the initial characteristics shown in Table 1 in liquid nitrogen. The fine resin powder was used.

The composite resin was depressurized and degassed with a rotary pump after mixing to prevent the formation of voids during curing, and then dropped and poured from the end of the slot using a dropper as described above. The fixed phase varnish of the thermosetting resin of Comparative Example 1 was also depressurized and degassed in the same manner as the composite resin.

The dripping and pouring of the fixed varnish was performed by preheating the stator to about 70 ° C., and the flow of the fixed varnish in the slot and the gap filling property were improved. After dropping the fixed varnish to all the slots, the stator was put into a heating furnace and heated in the atmosphere at 150 ° C. for 1 hour to cure the fixed varnish, and the stators of Examples and Comparative Examples were manufactured. In the fixed varnish curing process, a thermocouple for monitoring the actual temperature is attached to an arbitrary core tooth located in the axial center of each stator inner surface (one point), and the temperature is controlled, and the furnace is heated for 1 hour after the actual temperature reaches 150 ° C. After the inner holding, the stator with the fixed varnish cured was taken out of the furnace and air-cooled.

Separately from the production of the stator, only the composite resin obtained by mixing and vacuum degassing in Examples 1 to 3 and Comparative Example 2 was cured at 150 ° C. for 1 hour, and the structure was observed by polishing the cured resin. A schematic diagram of the observed composite resin structure is shown in FIG. In any composite resin, it was confirmed that the thermoplastic resin was uniformly dispersed as the dispersed phase 52 in the matrix phase 51 formed of the thermosetting resin.

Table 2 shows the evaluation results of the stator manufactured by applying the composite resin shown in Table 1. Here, the stators of the manufactured examples and comparative examples were thermally deteriorated under conditions simulating the rise in the coil temperature, and the partial discharge start voltage, the charging time until the dielectric breakdown at 1.2 kV charging were measured, and the insulation reliability was measured. Sex was compared and evaluated. The coil cooling performance was evaluated by measuring the coil temperature after cooling the stator coil to about 200 ° C. for 10 minutes.

For heat deterioration, heat treatment of 220 ° C. × 1,250 hours was applied. The partial discharge start voltage and dielectric breakdown test after thermal degradation were performed between the stator coil and the housing, and the U, V, and W phase coils of the prototype stator were connected in series.

The definition of the partial discharge start voltage is that the rising voltage of the charge amount is the partial discharge start voltage, and in the dielectric breakdown test, the dielectric breakdown detection current is 10 mA.

In the coil cooling performance evaluation, U, V, and W phase coils of the prototype stator were connected in series as in the insulation reliability evaluation, and a DC current was energized and heated by a DC power source to rapidly heat only the stator coil. The stator coil temperature was measured by being attached to an arbitrary slot opening at the center in the axial direction of the inner surface of the stator.

The evaluation results in Table 2 showed good partial discharge initiation voltage and dielectric breakdown characteristics corresponding to the initial tensile breaking elongation of the dispersed phase thermoplastic resin. The dielectric breakdown time of the PPS composite resin of Comparative Example 2 resulted in dielectric breakdown before reaching 1.2 kV, resulting in lower insulation reliability than Comparative Example 1 using only the thermosetting resin as the fixed varnish. . This can be attributed to the fact that the embrittlement of the fixed varnish during thermal degradation was accelerated due to the composite of PPS having a tensile elongation at break that is lower than that of the epoxy thermosetting resin in the matrix phase.

In Examples 1 to 3, the dielectric breakdown time at 1.2 kV charging was 168 hours (7 days) or more, and superiority or inferiority could not be determined in this respect, but the partial discharge start voltages were compared. Then, it can be seen that Example 2 using a PTFE composite resin having a low dielectric constant for the fixing varnish has a higher value than the other examples. When comparing the coil cooling performance, Example 2 shows that the coil is rapidly cooled, and the effect of combining PTFE having a high linear expansion coefficient is clearly shown.

From the above examples and comparative examples, the effects of the present invention can be understood. That is, according to the present invention, acceleration of embrittlement of the slot insulation fixing varnish accompanying the rise in the stator coil temperature and prevention of deterioration of insulation reliability due to generation of cracks can be prevented, and a more compact stator and hybrid vehicle, electric vehicle power motor and It becomes possible to provide a rotating electrical machine using the same. The present invention is particularly suitable for a high-voltage rotating electrical machine that is operated at a driving voltage in the vicinity of 1 kV.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1 Stator Core 2 Slot Liner 3 Stator Coil 4 Slot 41 Stator 42 Segment Coil 43 Stator Core 44 Housing 51 Matrix Phase of Composite Resin 52 Dispersed Phase of Composite Resin

Claims

In a stator of a rotating electrical machine comprising a coil having an insulating coating and a core provided with a plurality of slots in which the coils are arranged.
A stator for a rotating electrical machine using a composite resin in which a thermoplastic resin is contained in a thermosetting resin as a slot fixing varnish.
In the stator of the rotating electrical machine according to claim 1,
The composite resin is a composite resin composed of a matrix phase and an island-like dispersed phase,
A stator for a rotating electrical machine, wherein the matrix phase is a thermosetting resin and the island-shaped dispersed phase is a thermoplastic resin.
In the stator of the rotating electrical machine according to claim 1 or 2,
The thermoplastic resin is
Is the tensile elongation at break larger than the thermosetting resin,
The dielectric constant is lower than the thermosetting resin, or
A stator for a rotating electrical machine having a thermal expansion coefficient larger than that of the thermosetting resin.
A rotating electrical machine comprising the stator of the rotating electrical machine according to any one of claims 1 to 3.