JPS61116952A - Synchronous motor - Google Patents

Abstract

PURPOSE:To obtain a stable starting characteristic reducing pulsating torque due to magnetic flux passing stator teeth and rotor teeth, by slanting a rotor pole in the rotational direction. CONSTITUTION:A synchronous motor with squirrel-cage starting windings is provided with a stator core 1 and a rotor pole 4 having the squirrel-cage start ing windings 5. Then, the rotor pole 4 is arranged to be slanted at the angle thetaof inclination in the rotational direction R. And the stator core 1 and the rotor pole 4 are provided with stator teeth 7 and rotor teeth 8. Then, the ampli tude value of pulsating torque due to the relative position between a stator and a rotor in case of the slanted pole 4 is smaller than the value in case of the pole 4 arranged perpendicularly to the diameter, and accordingly, so far as complex torque due to the starting windings 5 is concerned, positive torque is generated at all positions, and a stable starting characteristic can be realized avoiding constrained phenomenon on starting.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a synchronous motor with a squirrel-cage starting winding, and more particularly to the arrangement of rotor poles thereof.

[Technical background of the invention and its problems] A synchronous motor with a squirrel-cage starting winding has been widely used as a self-starting synchronous motor.

A synchronous motor with a squirrel cage starting winding will be explained based on FIGS. 4 to 9. The stator is composed of a stator core 1 made of laminated thin steel plates and coils 3 housed in a large number of stator grooves arranged at equal intervals on the inner diameter side of the stator core 1. Rotor magnetic pole 4
The rotor 1 is constructed of laminated steel plates with all magnetic poles having the same shape, and has squirrel-cage starting windings 5 provided at the same spacing on the magnetic pole heads.
It is placed on 1!6.

The synchronous motor with a squirrel-cage starting winding constructed in this manner is started by the torque generated by the current flowing through the squirrel-cage starting winding 5, that is, the same torque as that of an induction motor, and rotates in the direction of the arrow &. However, if the groove spacing on the stator side is almost equal to the groove spacing on the rotor side, the rotor will be restricted and cannot be started due to the positional relationship between the rotor and stator even if electrical input is applied to the stator side. In some cases, The above-described rotor binding phenomenon at startup often occurs as the ratio of the stator groove spacing to the rotor groove spacing approaches 1.

FIG. 7 shows the change in torque due to the relative positional relationship between the stator and rotor, which was obtained through experiments.

Also, Fig. 8(a)-fd) shows the stator tooth 7 and the rotor tooth 8.
It shows the flow of magnetic flux with respect to changes in the relative positional relationship of. If the stator teeth 7 and rotor teeth 8 are slightly shifted in the rotational direction from the opposing position (FIG. 8(a)) as shown in FIG. Since the magnetic flux due to the tooth 7a is stronger than the magnetic flux due to the stator tooth 7b, the stator tooth 7a
This generates a torque in the opposite direction to the rotor direction, that is, a negative torque. In addition, if the stator teeth 7 and rotor grooves 6 are slightly shifted in the rotational direction from the opposing position (FIG. 8(C)) as shown in FIG. 8(d), the rotor teeth 8a will not be fixed. Child tooth 7
Since the magnetic flux caused by the stator teeth 7C is stronger than the magnetic flux caused by the stator teeth 7C, it is attracted to the stator teeth 7d and generates torque in the rotational direction, that is, positive torque. In the case of Fig. 8(a), stator tooth 7
and is restrained by the magnetic flux of the rotor teeth 8, so neither positive nor negative torque is generated due to the flow of magnetic flux as shown in Figure 8 (bl (di). Also, as shown in Figure 8 (cl) The magnetic fluxes of the stator teeth 7 are balanced as shown in Fig. 8 (bl
(No torque in the positive direction or torque in the negative direction is generated due to the flow of magnetic flux such as di.

If the magnetic poles are perpendicular to the radial direction, the grooves on the stator side are equally spaced, and the ratio of the stator groove spacing to the rotor groove spacing is close to 1), all magnetic poles will rotate with the stator teeth 7. The relative positions of the child teeth 8 are the same, and the positive and negative torque changes of each magnetic pole are added in Figure 8 (al to (di), and the overall relative position of the stator and rotor is as shown in Figure 9 (1). Pulsating torque is generated.

As described above, at the time of starting, the torque similar to that of an induction motor with a squirrel cage starting winding as shown in Fig. 9 (11) can be obtained.
) The pulsating torque generated due to the relative position of the stator and rotor is superimposed, resulting in a torque as shown in Figure 7.Depending on the position of the rotor, a locking phenomenon occurs at the time of starting, for example, between A) and B). It turns out.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to avoid the locked state of the rotor at the time of starting, and to improve the starting characteristics.

[Summary of the invention]

In order to achieve the above object, in the synchronous motor of the present invention, the rotor magnetic poles are installed with an inclination in the rotational direction, so that torque in the rotational direction is applied regardless of the positional relationship between the stator groove and the rotor magnetic pole groove. do.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG.

The present invention is achieved by arranging the magnetic poles of the rotor so as to be inclined by a certain angle of inclination θ in the direction of rotation.

At startup, the squirrel-cage starting winding 5 generates a constant torque that does not depend on the position of the rotor, similar to an induction motor, but in addition to the torque generated by the squirrel-cage starting winding 5, stator teeth 7 and rotor teeth 8 A pulsating torque is generated due to changes in the flow of magnetic flux between. At startup, magnetic flux is generated by voltage input on the stator side, and the magnetic flux flows between stator teeth 7 and rotor teeth 8.

FIG. 2 (at-(di) shows the flow of magnetic flux with respect to changes in the relative positional relationship between the stator teeth 7 and the rotor teeth 8.

When the leftmost stator groove and rotor groove are in opposing positions as shown in Figure 8 (al), an attractive force is generated in the negative direction on the right side of the magnetic pole, producing negative torque, but the magnetic flux is balanced on the pressure side. Because it is connected, no torque is generated.

The magnitude thereof is smaller than that in the case where negative torque is generated in the entire magnetic pole (FIG. 8(b)). As shown in Figure 2 (b), if the leftmost stator groove and rotor groove are slightly deviated in the rotational direction from the position where they face each other, an attractive force will be generated in the positive direction on the left side of the magnetic pole and a positive torque will be generated, but on the right side Since the magnetic fluxes are balanced, no torque is generated. The magnitude thereof is smaller than that in the case where positive torque is generated in the entire magnetic pole (FIG. 8(d)). Figure 2 (When the leftmost stator teeth and rotor grooves are in opposing positions as shown in C1, an attractive force is generated in the positive direction on the right side of the magnetic poles and a positive torque is generated, but the magnetic flux is balanced on the left side. Therefore, no torque is generated.The magnitude is smaller than when positive torque is generated across the entire magnetic pole (Fig. 8(d)).Second
As shown in figure fdl, if the leftmost stator tooth and rotor groove are slightly shifted in the rotational direction from the opposing position, an attractive force is generated in the negative direction on the left side of the magnetic pole and a negative torque is generated, but on the right side, the magnetic flux is Because they are balanced, no torque is generated. The magnitude is when negative torque is generated in the entire magnetic pole (Fig. 8 (b))
becomes smaller than . Although positive and negative torques are generated at any position in FIG. 2 fal-(d), the amplitude of the entire magnetic pole is smaller than that in FIG. 8(at-(d)).

Therefore, as shown in Figure 3, when the magnetic poles are tilted by the angle θ, the amplitude of the pulsating torque due to the relative position of the stator and rotor is smaller than when the magnetic poles are arranged perpendicular to the radial direction. Therefore, the torque generated by the squirrel-cage starting winding is superimposed to generate a positive torque at position f, thereby making it possible to avoid the binding phenomenon at the time of starting and realize stable starting characteristics.

The angle of inclination of the magnetic poles is selected to minimize torque pulsation based on the ratio of the stator groove spacing to the rotor groove spacing.

〔Effect of the invention〕

In the present invention, since the rotor magnetic poles are tilted in the rotation direction, the pulsating torque due to the magnetic flux passing through the stator teeth and rotor teeth is reduced, and the squirrel cage starting winding has stable starting characteristics that avoids a locked state during starting. A synchronous motor can be realized.

Also, since the rotor magnetic poles are tilted in the direction of rotation, the gap length between the stator and rotor on the side in the direction of rotation is wider than on the opposite side.
The fan effect of the magnetic poles itself makes it easier for cooling air to circulate toward the stator, thereby increasing the cooling effect of the solid electronic coil and stator core.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of essential parts of a synchronous motor according to an embodiment of the present invention, Fig. 2 is a diagram showing the state of magnetic flux depending on the rotor position in the synchronous motor of Fig. 1, and Fig. 3 is a sectional view of the main parts of a synchronous motor according to an embodiment of the present invention.・Diagrams showing the torque in the electric motor. Figures 4 to 9 show conventional synchronous motors. Figure 4 is a cross-sectional view of the motor. Figure 5 is a plan view of a steel machine with a rotor magnetic field. Figure 6 is a diagram showing the main points. Partial sectional views, Figures 7 and 9 are diagrams showing the relationship between rotor position and torque, and Figure 8 is a diagram showing the relationship between rotor position and torque.
The figure shows how magnetic nests are generated depending on the rotor position. 1... Stator core 2... Stator groove 4 - Rotor magnetic pole 5... Squirrel cage starting winding 6... Rotor groove 7... Stator tooth 8 Rotor tooth 9...
・Magnetic flux R...Rotation direction Agent Patent attorney Kensuke Chika (and 1 other person)
Figure 1 Figure 3 One turn 2 [No 4 standing i Figure 2 (α)
(C) (6)
ut) Fig. 4 Fig. 6wi □ Recommendation of rotation J Fig. 8

Claims (1)

[Claims] A synchronous motor characterized in that rotor magnetic poles having squirrel-cage starting windings are mounted at an angle in the direction of rotation.