JP2003274593A - Stator coil for rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent abrasion due to electromagnetic vibrations on the surface of a coil by suppressing vibration of the coil and control the thermal distortions generated in an insulating layer, when carrying out an insulation processing by integrally injecting a thermosetting resin into a stator coil and a stator core. <P>SOLUTION: The stator coil is integrated with the stator core, by impregnating and hardening the thermosetting resin, after being incorporated into the slot of the stator core at the stage of winding a ground insulating layer and a semiconducting layer around a stator conductor. A leaf spring whose surface is unbonded is provided between the stator coil and the wedge for holding the stator coil, or between the stator coil and the slot bottom, thereby suppressing the vibration by electromagnetic force of the coil in the slot. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator coil for a rotating electric machine, which is subjected to a full impregnation insulation treatment in which a stator coil is inserted into a slot and then impregnated and cured with a resin.

[0002]

2. Description of the Related Art In the prior art for insulating a stator coil of a rotating electric machine from ground, there is a ground insulating tape around the stator conductor.
After winding a semi-conductive tape, impregnate and harden a thermosetting resin for insulation, install it in the slot of the stator core and fix it with a wedge, and the ground insulation around the stator conductor. There is a second conventional technique in which a tape or a semi-conductive tape is incorporated into a slot of a core at the stage of winding and is pressed by a wedge, then a thermosetting resin is impregnated and cured to insulate.

In the first prior art, the relative thermal displacement generated between the stator coil and the stator core due to the temperature change caused by the operation and stop of the rotating electric machine is slid between the stator coil and the stator core. You can open it with. At this time, a leaf spring is sandwiched between the stator coil and a wedge that holds the stator coil to suppress the vibration of the stator coil due to the electromagnetic force applied to the stator coil.

Further, in the second prior art, since the stator coil and the slot of the stator core are in close contact with each other, heat generation of the coil conductor can be promptly guided to the core, but between the stator coil and the stator core. Failure to release the relative thermal displacements that occur will result in damage to the insulation.

[0005]

In the second prior art described above, when the stator coil and the stator core are manufactured by non-bonding treatment, the wire between the stator coil and the stator core is not provided. Relative displacement due to expansion coefficient difference as well as temperature difference occurs. This displacement occurs not only in the lengthwise direction of the stator coil but also in the direction perpendicular to it. In particular, the height of the stator coil corresponding to the direction perpendicular to the rotation axis of the rotating electric machine, that is, the radial direction of the stator core may exceed 200 mm for the upper coil and the lower coil in two stages. There may be a gap ΔH in the radial direction of the stator core between the stator coils. The gap ΔH widens as the temperature decreases from the temperature at which the thermosetting resin is impregnated and cured, and the size thereof can be approximated by the following formula (Formula 1). Further, the relative axial displacement ΔL of the stator core between the stator coil and the stator core, which occurs at the slot outlet of the end of the stator core, can be approximated by the following equation (2).

ΔH = H × {(T _O −Tc) × αc− (T _O −Ts) × αs} (Equation 1) ΔL = L × {(T _O −Tc) × α c − (T _O −Ts ) × αs} / 2 (Equation 2) where H is the height of the upper and lower coils of the stator coil combined, L is the stacking length of the stator core, and T _O is for insulation treatment. Curing temperature of injected thermosetting resin, Tc and T
s is the temperature of the conductor and core when calculating the gap, α
c and αs are linear expansion coefficients of the stator coil and the stator core, respectively.

[0007]

[Table 1]

In Table 1, H = 200 mm, L = 5000 mm,
T _o = 155 ° C., Tc = 17 × 10 ⁻⁶ 1 / ° C., Ts = 11
The calculated values are shown under the condition of × 10 ^-6 1 / ° C. A gap ΔH of 0.18 mm to 0.08 mm is generated from the time of stop to the time of low output, and decreases as the conductor temperature rises as the output increases. When the coil is energized and electromagnetic force is applied with this gap, the stator coil vibrates and wears the coil surface, and the stator coil is damaged by damage to the semiconductive layer provided on the stator coil. There is concern about corona discharge between the stator core and the stator core.

When the core stacking length is long, relative displacement of about 2 mm occurs between the stator coil and the stator core at the outlet of the slot as shown in Table 1 when the generator is stopped.

The structure of the prior art in which the bending direction of the leaf spring is parallel to the axis of the coil will be described with reference to FIG.
A leaf spring 11 whose bending direction is the axial direction of the coil indicated by the arrow in FIG. 1 is sandwiched between the wedge 1 and the wedge lower insulating plate 7 laid on the stator upper coil 3 to form a thermosetting resin. The thermosetting resin 12 is filled in the gap formed between the two and solidifies. In this state, as shown in FIG. 3, even if the wedge 1 and the insulating plate 7 under the wedge are subject to relative displacement as indicated by an arrow, the uneven portion of the thermosetting resin 12 and the unevenness of the leaf spring 11 are Relative displacement does not occur due to meshing, excessive strain occurs in the insulating layer,
May cause shear failure.

An object of the present invention is to provide an insulating treatment by injecting a thermosetting resin into the stator coil and the stator core integrally.
It is an object of the present invention to provide a structure in which vibration of a coil is suppressed, wear of the coil surface due to electromagnetic vibration is suppressed, and at the same time, thermal strain generated in an insulating layer is released.

[0012]

In the stator coil for a rotating electric machine according to the present invention, after the ground insulating layer and the semiconductive layer are wound around the stator conductor, the stator coil is assembled in the slot of the stator core. , A stator coil that is impregnated and cured with a thermosetting resin and is integrated with the stator core, and the surface of the stator coil is kept between the wedge holding the stator coil and the stator coil or between the stator coil and the slot bottom. Equipped with a bonded leaf spring, it suppresses vibrations due to electromagnetic force of the coil inside the slot.

In the stator coil for a rotating electric machine according to the present invention, a main ground insulating layer covering the coil conductor and a stator coil having a semiconductive layer formed on the outside thereof are provided in slots provided in the stator core. After assembly, place a leaf spring with a non-adhesive surface between the stator coil and the wedge that holds the stator coil, or between the stator coil and the slot bottom, inject and harden the thermosetting varnish, and fix it. The stator coil and the stator core are not bonded to each other, and the stator coil can freely expand and contract with respect to the stator core, and at the same time suppresses vibration of the stator coil due to electromagnetic force applied to the stator coil by the force of the leaf spring.

In the stator coil for a rotating electric machine according to the present invention, the bending direction of the leaf spring is set to the circumferential direction of the stator coil, so that the thermosetting resin is hardened between the leaf spring and the wedge or the wedge lower material. Even if a deposit is formed, it does not hinder the axial relative displacement that occurs between the stator coil and the stator core, and it is too large between the insulating layers sandwiched between the stator conductor and the stator core. Distortion does not occur.

The stator conductor is installed in the slot of the stator core at the stage of winding the ground insulating tape and the semiconductive tape around the stator conductor, and between the stator coil and the wedge holding the stator coil or When sandwiching a leaf spring with a non-adhesive surface between the stator coil and the bottom of the slot and pressing it with a wedge, when thermosetting resin is impregnated and cured for insulation treatment, the glass transition of the resin portion of the leaf spring It is necessary that the temperature be higher than the temperature at which the thermosetting pouring varnish is cured. When the glass transition temperature is lower than the curing temperature, the spring force of the leaf spring is relaxed when the varnish is cured, and the repulsive force that suppresses the coil is lost. By setting the glass transition temperature of the resin part of the leaf spring higher than the temperature at which the thermosetting injection varnish is cured, even if the temperature of the entire stator is raised to the temperature at which the injection varnish is cured, the spring force of the leaf spring is The vibration of the stator coil can be suppressed against the electromagnetic force that is held and applied to the stator coil.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

(Embodiment) FIG. 4 is a partial sectional view showing a situation in which the leaf spring of this embodiment is compression-molded. The surface in the width direction of the mold was made into a sin curve shape, and a resin mixture prepared by mixing a bisphenol A type epoxy resin, an acid anhydride, and an imidazole-based curing accelerator was impregnated into a glass cloth, and the material was laminated at 170 ° C. After curing for 15 hours and further at 230 ° C. for 5 hours, the leaf spring 2 was formed which was not bent in the direction parallel to the axis of the coil but was bent in the circumferential direction of the coil. The temperature dependence of the thermal expansion amount in the thickness direction of the leaf spring 2 was measured by a thermomechanical property measuring device (TMA), and the glass transition temperature was determined from the change point of the thermal expansion amount, and was 196 ° C. . A silicone-based release agent was applied to the leaf spring 2, and then heated at 170 ° C. for 1 hour to release the surface.

Next, the stator of this embodiment will be described with reference to FIG. Half a piece of glass-backed laminated mica insulation tape around the stator conductor with a core stack length of 4600 mm 1
On the slot bottom insulating plate (not shown) of the slot 6 in which the stator core coil 5 is provided with the stator core coil 5 in which the stator core coil 5 is wound twice, and the outermost layer is half wound with a semiconductive insulating tape. Built in. Next, sandwiching the FRP bottom insulating plate 8 between the coil layers, the stator upper coil 3 wound with an insulating tape in the same manner as the stator bottom coil is installed in the slot 6, and the wedge upper insulating plate 7 is laid on the stator upper coil 3. Then, the wedge 1 is incorporated while sandwiching the leaf spring 2 thereon, and the stator upper coil 3 and the stator bottom coil 4 are fixed. Thereafter, the mica insulating tape is dried under reduced pressure at 80 ° C. to remove moisture absorption, and a thermosetting resin containing a bisphenol A type epoxy resin, an alicyclic epoxy resin, an acid anhydride and an imidazole type curing accelerator is placed in a varnish injection tank. Insulating tape, under pressure 0.5MPa
The varnish was impregnated into the space such as between the slot and the insulating material.
After that, it was cured at 155 ° C. for 15 hours to obtain an insulation-treated stator.

After repeating the heating and cooling of the conductor by energization with this stator for 500 cycles, the electrical characteristics were measured, and it was confirmed that the insulation discharge characteristics did not change significantly. It was also confirmed that the relative displacement between the stator coil and the stator core at the slot outlet of the stator was 1.4 mm, which allowed almost free displacement and low shear strain applied to the insulating layer.

A force 9 is applied to the wedge 1 of the stator of this embodiment in the slot bottom direction at a temperature of 20 ° C., and the load at which the wedge 1 and the notch 10 on the side surface of the slot that stops the wedge are separated from each other is measured. It was 150 N per cm length. Since the electromagnetic force applied to the stator coil is 50 N per 1 cm of the length of the stator coil, it was confirmed that the reaction force of the leaf spring 2 sufficiently pressed the stator coil. Further, after the operation test, the wedge of the stator was pulled out, and the coil periphery was visually observed. As a result, there was no friction mark due to vibration.

Comparative Example 1 This comparative example will be described with reference to FIG. In this comparative example, a stator was made with the same size and material as in Example 1 except that the leaf spring 11 was bent in the direction parallel to the coil axis. When the electric characteristics of this stator were repeatedly heated and cooled by energizing the conductor for 500 cycles, the electric characteristics were measured. This is presumed to be peeling inside the insulating layer. The relative displacement of the coil and core at the slot outlet was measured and found to be 0.6 mm. It is estimated that the surface of the coil insulation layer was constrained by the slot of the core and shear strain occurred in the insulation layer. To do.

Comparative Example 2 This comparative example will be described with reference to FIG. In this comparative example, a stator was made with the same size and material as in Example 1 except that the leaf spring 11 was bent in the direction parallel to the coil axis and the glass transition temperature was 150 ° C.

A force 9 was applied to the wedge of this stator in the direction of the bottom of the slot at 20 ° C., and the load at which the wedge 1 and the notch 10 on the side surface of the slot that stops the wedge were separated was measured. It was 35N. The electromagnetic force applied to the stator coil was 50 N per 1 cm of the stator coil length, and the stator coil could not be pressed by the reaction force of the leaf spring.

[0024]

According to the present invention, it is possible to provide a stator coil fixing method for a rotating electric machine, which is highly effective in preventing excessive distortion in the insulating layer of the stator coil and suppressing vibration of the stator coil.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional bird's-eye view showing a method for fixing a stator coil for a rotary electric machine according to an embodiment.

FIG. 2 is a schematic sectional view showing a method of fixing a stator coil for a rotary electric machine according to a conventional technique.

FIG. 3 is a schematic cross-sectional view of a method of fixing a stator coil for a rotating electric machine according to a conventional technique.

FIG. 4 is a cross-sectional view showing the method of manufacturing the leaf spring of the first embodiment according to the present invention.

FIG. 5 is a partial cross-sectional bird's-eye view showing a fixing method of the rotating electric machine stator of Comparative Example 1.

FIG. 6 is a partial cross-sectional bird's-eye view showing a fixing method of a rotating electrical machine stator of Comparative Example 2.

[Explanation of symbols]

1 ... Wedge, 2 ... Leaf spring, 3 ... Stator upper coil, 4 ... Stator bottom coil, 5 ... Stator core, 6 ... Slot, 7 ... Wedge lower insulating plate, 8 ... FRP bottom insulating plate, 9 ... Force 10 ... Cut, 1
1 ... Leaf spring, 12 ... Thermosetting resin, 20 ... Upper mold, 21
… Lower mold.

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Claims (2)

[Claims] 1. A stator coil for a rotating electric machine, comprising a ground insulating layer covering a periphery of a stator conductor, which is incorporated in a slot provided in the stator core, and then integrated with the stator core by a thermosetting impregnating resin. In the above, the bending direction of the leaf spring whose surface is not adhered is the circumferential direction of the stator coil, and the leaf spring is provided between the stator coil and the wedge that holds the stator coil, or between the stator coil and the slot bottom. A stator coil for a rotating electric machine, characterized by being provided between the two. 2. A stator coil for a rotating electric machine, comprising a ground insulating layer covering a periphery of a stator conductor, which is incorporated in a slot provided in the stator core, and then integrated with the stator core by a thermosetting impregnating resin. In the above, the glass transition temperature of the leaf spring whose surface is not adhered is equal to or higher than the temperature at which the thermosetting impregnating resin is cured, and the bending direction of the leaf spring is the circumferential direction of the stator coil. A stator coil for a rotating electric machine, comprising a spring between the stator coil and a wedge that holds the stator coil, or between the stator coil and the slot bottom.