JPS5845268B2 - Stator of AC rotating electric machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stator for an AC rotating electrical machine such as a three-phase induction motor, and particularly to an iron core thereof.

Generally, in the stator of an AC rotating electric machine such as a three-phase induction motor, the slot shape or teeth width of the iron core is determined so that the magnetomotive force generated by the stator winding current induces more effective magnetic flux. ing.

In other words, if the width of the teeth where the magnetic flux concentrates is made too narrow,
The tooth width is determined so that the magnetic flux density of the teeth does not exceed, for example, about 15,000 Gauss, since this increases the magnetic flux density and causes magnetic saturation, significantly increases iron loss, and degrades the performance of the machine.

By the way, recent advances in insulators have been remarkable, and insulators with excellent heat resistance have been developed, and the majority of induction motors use class F insulation, which is even more heat resistant than conventional class B insulation. It has come to the point where

If the heat resistance of the insulator is improved in this way, a large amount of current can be passed through the stator windings, so it is expected that machines can be made dramatically smaller and lighter.

However, as described above, when the amount of magnetic flux is increased by increasing the stator winding current, the magnetic flux density of the teeth becomes higher than the limit value, and therefore it becomes necessary to increase the width of the teeth.

In other words, in order to make a machine smaller and lighter, it is necessary not only to improve the heat resistance of the insulator, but also to study the magnetic flux distribution in detail and design the optimal iron core shape to avoid local magnetic flux concentration. There is a need to.

Therefore, the configuration of the conventional stator is as shown in Fig. 1.
A slot 3 is provided on the inner circumferential side of a stator core 1 constructed by laminating thin iron plates, and each coil 2 constituting a three-phase, two-layer, short-pitch stator winding is inserted into the slot 3. , is held by wedge 5.

The stator windings are U phase (indicated by black), ■ phase (indicated by black), and W phase.
It consists of a number of parts (accepted orally), each arranged as shown in the figure.

By the way, in this configuration, when the magnetic flux density and iron loss of each tooth 4 are examined in detail, as shown in the same figure, the circumferential position shows two aspects represented by tl and t2,
42 parts had a higher magnetic flux density and larger iron loss than 41 parts.

This is because the phase of the current flowing through the coils inserted in the slots on both sides of the 41 part does not change, whereas the 42
This is due to an unexpected increase in leakage magnetic flux in the 42nd part because this changes in the 42nd part.

In other words, in the 41st part, the IJ phase flows in the upper layer of the left and right coils, and the V phase flows in the lower layer, and the phase form of the right current does not change in the 41st part, but in contrast to this, In part 42, the U phase flows in the upper layer of the left coil, the ■ phase flows in the lower layer, and the V phase flows in the upper and lower layers of the right coil, and the circumferential position t2
This is due to the fact that the phase of the current in the slot 3 differs across the teeth 4 of the slot.

Now, the fact that the magnetic flux density increases at the boundary teeth 4 where the current phase forms in the slot 3 are different is as follows.
In addition to the fact that the magnetic flux density in the 4th part of the teeth has almost reached its limit value, there will be a point where the magnetic flux density becomes even higher than this, which causes a significant increase in the iron loss in the 4th part of the teeth. It turns out.

In other words, as shown in Figure 2, iron loss is approximately 2 times the magnetic flux density.
The increase is proportional to the power of the magnetic flux, and the increase is particularly significant in areas with high magnetic flux density, which tends to reduce the efficiency of the machine and make it difficult to ensure sufficient performance.

An object of the present invention is to provide a highly efficient stator for a rotating electrical machine by correcting the magnetic flux density of each tooth of the stator core and eliminating teeth that are distributed in the circumferential direction and have a large core loss. There is something to do.

To achieve this objective, the present invention has experimentally confirmed that the magnetic flux density increases in the teeth portions at positions where the phases of the currents flowing in the coils in adjacent slots of the stator winding are different from each other. However, it is characterized in that the cross-sectional area of the radial magnetic path of the tooth at this position is made smaller than the cross-sectional area of the radial magnetic path of the teeth in other parts.

Hereinafter, one embodiment of the present invention will be described with reference to 1 in FIG.

A slot 3 is cut in the stator core 1, and this slot 3
Each coil 2 constituting a stator winding is inserted therein.

The width a of the tooth 4a, represented by the 42 part, is such that the phase form of the current flowing in the slots 3 on both sides of the tooth 4 changes in the circumferential direction. The width of the tooth is wider than that of a normal tooth, typically 41 parts, which do not change in direction.

Due to this, the magnetic flux density of the 42 part is reduced, the magnetic flux density of each tooth is made uniform, and the iron loss occurring in the 42 part can be significantly reduced, resulting in a highly efficient machine.

For example, in an example conducted on a 700KW machine, a conventional machine with the same tooth width (a, -b=]-2 cylinder) had a magnetic flux density of 41 parts, which was the limit of 15,000 Gauss, compared to , the 42nd part actually reached 17,000 gauss, but by making it slightly wider by 1.6mm to a=13.6mm, the magnetic flux density of the 42nd part was reduced to 15,000 gauss, which is the same as the 41st part, and the total The magnetic flux densities of the teeth can be maintained at the same limit, and the iron loss of the 42 parts can be reduced to about 70 times the conventional value.

As a result, the efficiency of the machine increases by approximately one factor, resulting in a machine with good performance.

Further, FIG. 4 shows another embodiment of the present invention.
In order to make the width a of the tooth 4a represented by the part 41 wider than the width of a normal tooth represented by the part 41, the width C of the slot 3a adjacent to the tooth 4a of the part 42 is set to the width d of the other slots. It is narrower than.

Note that the depth of the narrow slots 3a is increased by a proportion of the narrow width, so that the current density flowing through the coil 2 is made uniform in each slot.

Furthermore, in each of the above embodiments, the width of the teeth at the position where the phases of the currents flowing in the coils in adjacent slots of the stator winding are different from each other is made wider than the width of the teeth at other parts, The cross-sectional area of the radial magnetic path is set to be larger than the cross-sectional area of the radial magnetic path of the teeth in other parts, but as a means to increase the magnetic paper flow cross-sectional area of the teeth,
In addition, a structure as shown in FIG. 5 or 6 can also be adopted.

That is, in the embodiment shown in FIG. 5, the wedge 5 of the slot 3a adjacent to the tooth 4a, represented by the section t2, is not provided over the entire length of the slot, but is provided, for example, only at both ends of the slot 7.

Therefore, there is no need to provide a groove for supporting the wedge over almost the entire length of the thrower 3a, and the cross-sectional area of the radial magnetic path of the teeth 4a adjacent to the slot 3a is reduced to the radial magnetic path of the other teeth. can be made larger than the cross-sectional area of

In addition, in the embodiment shown in FIG. 6, the seventh wedge is used as a wedge of the slot 3a adjacent to the tooth 4a represented by the t2 portion.
Magnetic wedges 5b and 5c made of a magnetic material 6 and a non-magnetic material 7 as shown in FIG. It is something.

Note that wedges 5a made of a normal non-magnetic material 7 as shown in FIG. 7a are used for slots in other parts.

As explained above, according to the present invention, the magnetic flux density of each tooth portion can be made equal to its limit value, and the increase in iron loss can be prevented and the efficiency of the machine can be improved.

[Brief explanation of drawings]

Figure 1 shows the relationship between the circumferential position of the teeth of the stator core and the circumferential position where the current phase of the stator winding coil changes in a conventional three-phase induction motor, and the magnetic flux density and iron loss of each tooth in the circumferential direction. FIG. 2 is a characteristic diagram showing the relationship between magnetic flux density and iron loss. FIG. 3 is an explanatory diagram similar to FIG. 4 to 6 are explanatory diagrams of a stator for a three-phase induction motor showing other embodiments of the present invention, respectively, and FIGS. It is a schematic sectional view showing a wedge. 1... Stator core, 2... Coil of stator winding, 3.3a... Slot, 4, 4a...
...Teeth.

Claims (1)

[Scope of Claims] 1. In a stator for an AC rotating electrical machine in which each coil of a stator winding is inserted into a slot of a stator core having a large number of slots and teeth, each coil of the stator winding is inserted between adjacent slots of the stator winding. An alternating current characterized in that the cross-sectional area of the radial magnetic path of the teeth at positions where the phases of the currents flowing through the coils are different from each other is made smaller than the cross-sectional area of the radial magnetic path of the teeth at other parts. Stator of rotating electric machine. 2. In claim 1, the width of the teeth at positions where the phases of the currents flowing through the coils in adjacent slots of the stator winding are different from each other is set to be wider than the width of the teeth at other portions. A stator for an AC rotating electric machine, which is characterized by the fact that it is also a dog. 3. In claim 2, the width of the slots adjacent to the teeth at positions such that the phases of the currents flowing through the coils in adjacent slots of the stator winding are different from each other is determined by the width of the slots in other parts. A stator for an AC rotating electric machine, characterized in that the width of the teeth at positions where the phases of the currents are different from each other is narrower than the width of the teeth at other parts.