JPS6277840A - Rotary electric machine - Google Patents

Abstract

PURPOSE:To reduce the slot ripple without increasing the volume of skew or number of slots by providing one and over recesses on the surface opposite to the gap of teeth of an armature core. CONSTITUTION:An AC servomotor is composed of a rotor where magnetic poles are formed by sticking multiple permanent magnets 2 on the outside peripheral surface of a cylindrical iron core 1 fitted to the rotating shaft and of a stator where an armature core 4 is housed to the semienclosed grooved iron core 3 provided around the rotor hereof. On the opposite surface of the gap of iron core teeth a recess 5 is formed. This recess 5 separates the magnetic flux coming in and going out to the teeth, so that 12 slot core seemingly shows the same permeance change as 24 slot core. With the skew of 0.5 slot the influence of slot ripples can therefore be removed.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a servo motor, for example, in which the armature winding is housed in a semi-closed groove electric core, and the electric conductor core or the electric core is skewed. Permanent [a 5 rotations 7IIi] used in motors
This is related to rotating electric currents such as the following.

[Technical background of the invention and its problems] Conventional cores with semi-closed grooves, which are easy to store and fix coils, have been used in small and medium capacity induction machines, synchronous machines, etc. ing. When such a semi-closed groove iron core is used, the permeance of the magnetic circuit pulsates due to the influence of the opening. , so-called slot ripple occurs. This throttle ripple appears as a harmonic component of cogging torque or induced voltage, and is a cause of deteriorating the performance of the rotating electric machine.

Therefore, in recent years, this type of AC servo motor has
Considering that it has come to be used as a drive device for robots and mechanical acupuncture, the reduction of rotational ripple and 1 to 1 ripple ripple is an important factor, and a reduction in slot ripple is particularly desirable. .

In this AC servo motor, synchronous type motors using permanent magnets are mainstream, and as shown in Fig. 5, there are usually multiple A permanent magnet 2 is attached to a rotor forming magnetic poles, and an electric coil 4 is attached to an iron core 3 with a semi-closed groove provided around the rotor.
It consists of a stator containing a

In servo motors with this type of configuration, the type core is usually skewed to reduce slot ripple.
Skew causes the following unfortunate problem. That is, ■
The inner surface of the slot in the laminated core gradually rises and the slot area decreases. As a result, the space factor of the coil increases, and the coil must be inserted in an involute curve, which impairs the workability of storing the coil.

■ Armature copper loss also increases as the winding length increases. Furthermore, in the case of skewing the permanent magnet of the field, a large amount of magnet molding is required, and in a flat motor with a medium length in the axial direction, the skew angle is large and it is difficult to manufacture the magnet.

Due to the above-mentioned problems, it is desirable to suppress the amount of skew as small as possible and eliminate slot ripple, but for this purpose it is better to increase the number of slots. That is, when the number of slots is increased, the frequency of the slot ripple increases and the width of the pulsation decreases, and even if the amount of skew is small, the ripple reduction effect can be achieved.

FIG. 6 shows the relationship between the number of slots, slot ripple harmonics, and skew winding coefficient with respect to the amount of skew. From FIG. 6, it can be seen that in order to eliminate the influence of slot ripple harmonics, a skew of at least 1 to 1 slot is required.

Naturally, the greater the number of slots, the smaller the one-slot skew angle.

However, if the number of slots is increased, the distributed winding coefficient becomes smaller, resulting in problems such as an insufficient number of windings for the armature, and the method cannot actually be used in small motors due to workability and cost considerations.

[Object of the Invention J] The present invention was made in view of the above circumstances, and an object thereof is to provide an N-rotation machine that can reduce slot ripple without increasing the amount of skew or the number of slots.

[Summary of the Invention 1 In the rotating electrical machine of the present invention, one or more recesses are provided on the surface of the armature core facing the teeth gap, thereby reducing slot ripple without increasing the amount of skew or the number of slots. It is designed to reduce the

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a part of a cross section of an embodiment in which the present invention is applied to one example of rotating permanent magnets. Contains winding 4. A recess 5 is formed on the face of the iron core facing the gap between the teeth. 'The recess 5 divides the magnetic flux entering and exiting the teeth into two, so that the 12-slot iron core appears to have the same permeance change as the 24-slot iron core. Not shown. Therefore, since there are 12 slots, the order of the slot ripple is the same as 24 slots 1~, and as is clear from FIG. 6, the ill of the slot ripple can be removed with a skew of 0.5 slots. Also, if one slot is skewed from 1 to 1, the effect will be the same as that of 2 slots with 24 slots i-. This case can be thought of as the same as a conventional 12-slot 1-slot skew without recesses, but in reality, slot ripples are completely eliminated due to misalignment of the permanent magnets on the rotor, misalignment in the direction of the rotation axis, etc. The present invention, which has 24 slots and 2 slots, is more advantageous than the skew of 12 slots and 1 slot, which cannot be completed.

Fig. 2 shows an embodiment in which two recesses 5 are provided on the teeth facing the gap, and a 12-slot iron core has 3
It shows the same permeance change as the 6-slot core. Therefore, the slot ripple can be eliminated by the 1/3 slot skew, and the 1 slot skew is equivalent to the 3 slot skew of 36 slots, making it possible to absorb imbalances during machining and assembly such as magnet mounting accuracy. However, as the number of recesses increases, the equivalent gap length increases.

Next, when a power source containing harmonics, such as an inverter power source, is connected to the armature winding, the magnetic flux density in the gap can be averaged by slightly changing the above-mentioned recess. Regarding this, as shown in [Improvement of stator structure for reducing gap harmonic magnetic flux in three-phase induction motors] Ito et al. This is because the magnetic flux concentrates on the teeth located at .

Therefore, if the recesses of the present invention are made larger than the other recesses in the teeth of the phase change portion, the equivalent gap length will be increased and the magnetic flux density will be averaged.

Fig. 3 shows an example in which the number of slots per phase per pole is 2, and the recesses 5a and 5c between the U phase band, V phase band, and W phase band are larger than 5b, and the equivalent gap length is large. , the magnetic flux density is averaged.

Figure 4 shows an example in which there is no boundary between the phase bands at the center of the teeth due to short-pitch winding, and the recesses 5d and 5e are on the U■ phase zone boundary side, and the recesses 5f and 5g are on the UW phase zone boundary side. I'm leaning on it. For this reason, the equivalent gap length at the phase zone boundary expands and the magnetic flux density is averaged.

In the above embodiment, an example was shown in which the present invention was applied to a four-pole permanent magnet rotating electrical machine, but of course it can also be applied to a non-permanent magnet type machine.

[Effect of the invention 1] According to the present invention, one or more recesses are provided on the surface facing the teeth gap of the armature core, so that the skew base and the number of slots are not increased.
1 that can reduce slot ripple and include harmonics! Even if the power source is connected, ripples can be reduced by just slightly changing the recess, and therefore a high-performance rotating machine with less cogging torque and less harmonic components of the induced voltage can be provided. −

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing an embodiment of a rotating electric machine according to the present invention, FIGS. 3 and 4 are diagrams respectively showing other embodiments of the present invention, and FIG. 5 is an illustration of a conventional permanent magnet. FIG. 6, which is a diagram showing a rotating electrical machine, is a diagram showing characteristics of a skew winding coefficient with respect to a slot ripple harmonic and a skew amount. DESCRIPTION OF SYMBOLS 1... Rotor core, 2... Permanent magnet, 3... Armature core, 4... Armature winding, 5... Recessed part, 5a-5
g...concavity. Applicant's agent Patent attorney Takehiko Suzue jII Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) In a rotating electrical machine in which the armature winding is housed in an armature core with a semi-closed groove, and the armature core or field magnetic pole is skewed, on the surface of the armature core facing the tooth gap, A rotating electrical machine characterized by having one or more recesses. (2) The rotating electric machine according to claim 1, wherein the recessed portion of the tooth serving as the boundary between the phase bands of the armature winding is larger than the recessed portion of the other teeth. (3) The rotating electrical machine according to claim 1, wherein the recessed portions of the teeth that form the boundaries of the phase bands of the armature winding are shifted from the center portions of the teeth toward the boundaries of the phase bands.