JPH0398445A - Rotary electric machine - Google Patents

Abstract

PURPOSE:To reduce cogging regardless of the central angle of the salient pole of an armature core by a method wherein a central angle per one pole of the magnets of 4n poles is determined as a specified electric angle and two kinds of stop positions upon non-exciting are realized. CONSTITUTION:Respective central angles thetaM of four pieces of magnets 2, arranged equally on a yoke 1, are set so as to be 108 deg.+ or -10 deg. or about 108 deg. preferably in electric angle. The central angle thetaa of the salient pole 4 of an armature core 3 is set so as to be 120 deg.+ or -180 deg. in electric angle. According to this method, both of two kinds of stopping positions I, II in non-exciting of the armature core becomes easy to be appeared while the number of stops becomes more than 7 times/360 deg., which is larger than 6 times/360 deg. of so far. Both of the stop positions I, II are established at about 108 deg. regardless of the value of the central angle of the salient poles of the armature core whereby the stopping positions of cogging of two poles, which are provided with different phases, are realized alternately and the cogging is changed into another cogging having smaller amplitude and shorter wave length. According to this method, the cogging of a motor can be suppressed.

Description

Detailed Description of the Invention (Industrial field in Icheon) The present invention relates to a rotating electric machine used as an electric motor or a generator. More specifically, the present invention relates to a rotating electrical machine that reduces cogging torque. (Prior art) In a permanent magnet field motor such as a DC motor,
Cogging torque generated by the correlation between the reluctance change due to the iron core and the magnetic field distribution of the permanent magnet becomes a problem. It is desirable to keep this cogging torque to a small level as it can impair the smoothness of rotation. One of the conventional methods of reducing cogging torque is to change the magnetization conditions of the magnet by controlling the voltage and capacity of the porcelain to determine the best point where cogging can be kept small. For example, unsaturated magnetization is performed by changing the magnetization conditions so that the magnetization distribution on the magnet surface exhibits a sinusoidal waveform. In this case, the best point for cogging can be easily determined regardless of the central angle of the core salient pole. (Section B that the invention attempts to solve) However, since the magnets are in an unsaturated magnetized state, the magnetization distribution of each individual magnet is slightly different.
This causes the problem that stable characteristics cannot be obtained because the magnitude of cogging varies from motor to motor. In addition, since the magnet is unsaturated and magnetized, there is a problem that the number of magnetic fluxes used is small and the output torque is low. In other words, in order to reduce the cogging torque, a large output torque is required to achieve unsaturated magnetization so that the change in magnetic flux becomes sinusoidal. The drawback is that you cannot obtain as much magnetic flux as you want. In addition, since unsaturated magnetized magnets are demagnetized by the armature reaction magnetic field, there is a problem that the number of magnetic fluxes decreases and the output torque also decreases. An object of the present invention is to provide a rotating electrical machine with small cogging torque. A further object of the present invention is to provide a rotating electrical machine that can reduce cogging torque regardless of the central angle of the salient pole of the armature core. (Means for Solving the Problem) In order to achieve the above object, the rotating electric machine of the present invention has a 4n
(n is an integer of 1 or more) poles and an armature core with 3k (k is an integer of 1 or more) salient poles, one of which rotates relative to the other. It is a rotating electrical machine configured as follows: the center angle of each magnetic pole of the magnet is 108°±10@, preferably about 1084 in electrical angle, and the rest position when not energized is 2! l! I am trying to make it appear like this. (Function) Therefore, there are two types of rest positions (I) of the magnet or armature core when the magnet or armature core is not energized. (II) both become more likely to appear, and the number of stops becomes 7 times/360' or more, which is higher than the conventional 6 times/360°. Then, at approximately 108°, both resting positions (I) and (II) are completely established regardless of the size of the central angle of the salient pole of the armature core, and the resting positions of two types of cogging with different phases are obtained. It appears alternately and changes to cogging with small amplitude and short wavelength. (Example) Hereinafter, the configuration of the present invention will be explained in detail based on an example shown in the drawings. An example in which the present invention is applied to a motor is shown in Figure 1. This motor has 4 magnetic [! It is an outer rotor type motor with three salient poles and an oval structure, and four arcuate magnets 2 are evenly spaced on the inner peripheral surface of a motor case/yoke 1. Each magnet 2 is magnetized in the thickness direction, and one magnet forms one magnetic pole. The central angle θ of each magnet 2 is 108°±104 in electrical angle, preferably about 108
It is set to @. Further, a stator core 3 having salient poles 4 is supported along the central axis of the yoke 1, and each salient pole 4 is arranged to face the inner peripheral surface of the magnet 2. The yoke 1 and the magnets 1 and 2 are rotatably provided around the stator core 3. salient pole 4 of core 3
There are three poles, and a coil 5 is wound around each salient pole 4.
The central angle θa of each salient pole 4 is an arbitrary angle, for example, approximately 1 in electrical angle.
It is set between 20° and 180°. In the case of this embodiment, since there are two magnetic pole pairs, the electrical angle and the mechanical angle do not match, and the central angle θyo is 172 in mechanical angle. Here, the central angle θ per magnetic pole of the magnet 2. means that two points on the circumference of the magnetized part that constitute one magnetic pole of the magnet are at the center O
It means the angle between the two, and it means the angle of magnetization per magnetic pole.
Central angle θ per magnetic pole of magnet 2. is approximately 1 in electrical angle
When set to 08°, the best cogging characteristics can be obtained regardless of the central angle θa of the protrusion 4 of the armature core 3. However, if the cogging torque is simply kept within a range smaller than the level that is generally considered to be small for practical use (the range shown by the chain line in Figure 4), θ is strictly about 1.
There is no need to set it to 08°, and it varies slightly depending on the central angle θa of the salient pole 4, but it can be set at a maximum of 10° in proportion to the size of θa.
There is no problem if you set it within the range of 8°±10°. for example,
The central angle θa of the salient pole 4 of the armature core 3 is expressed as electrical angle θa=1
20' or 180°, in order to obtain practical level cogging torque characteristics, the center angle of the magnet θ. It is sufficient to set it within the range of at least 108＠±106 in electrical angle. This value is considered to be well within the manufacturing error. Figure 2 (A). (B) shows an example of the ellipse of the magnet and tea child core in the case of a 41iI one-pole, three-salient-pole outer rotor type motor or stator magnet type. The magnets 2 are fixed to the inner circumferential surface of the cylindrical yoke 1 at equal intervals, and the '4 II child core has three salient arc-shaped poles that protrude outward on the circumferential surface of the shaft part. Become. In this case, the central angle θ. , θa are as shown. Figure 3 (A). (B) shows an example of the elliptical arrangement of the magnet and armature core for an inner rotor type motor with 4 magnetic poles and 3 salient poles. Magnet 2 is spindle-shaped yoke 1
are fixed at equal intervals on the circumferential surface of the Further, the armature core 3 has three arc-shaped salient poles 4 protruding inside the cylindrical core, and an armature coil is wound around each of the salient poles 4. In this case, the central angle θ. , θa are as shown. According to the rotating electric machine configured as above, cogging torque is reduced as follows. The characteristic diagram in Figure 5 is the experimental result, and shows the relationship between θyo and cogging, with θa as a parameter. As is clear from this experiment, normally in a rotating electrical machine with a 4-3 configuration consisting of a magnet with a 4nW magnetic pole and an armature core with a 3k salient pole, when not energized, the
Take either the rest position (I) shown in A) or the rest position (II) shown in Figure 6 (B). This resting position is
This is used when the center angle θ of the magnet 2 is separated by more than 108° (indicated by ■ and ■ in Figure 4). At that time, the cogging torque characteristics at rest position II [Fig. 5 (A) 1
and the cogging characteristics of the rest position (f[) [Figure 5 (G)]
Both have a number of stops of 6 times/360°, only the phase is different. Then, as θM approaches 108°, the rest position changes at a certain angle. The amplitude of the cogging torque in the transient region (indicated by ■ and ■ in FIG. 4) becomes small as shown in FIGS. 5(B) and 5(F). Therefore, further θ. When the angle approaches 108°, as shown in Figures 5(C) and 5(E), the characteristics of the static position (n) begin to appear slightly in the cogging torque characteristics of the static position (I), or The characteristics of the stationary position (I) begin to appear slightly in the cogging torque characteristics of position (II), and compression of amplitude and wavelength occurs. In other words, a transient phenomenon of change in rest position is occurring. Then, at about 108 degrees, the rest positions (I) and (IF) are both completely established, and the rest positions of two types of cogging torques with different phases appear alternately, and the amplitude is small and the wavelength is large. The cogging torque characteristics change as shown in (D). Therefore, the central angle θ per liii pole. When is set to about 108 degrees in electrical angle, cogging is best regardless of the size of the central angle θa of the salient pole 4 of the ta-child core 3. At this time, the rest position is 6 times/
From 360°, it doubles to 12 times/360°. Visual confirmation showed that cogging was reduced, and a stationary position of 7 to 12 times/360° was confirmed. Incidentally, the cogging torque at this time is less than half that of the conventional cogging torque reduction method using magnetization control (5 to 3 gcm) {1.
5 to 1.0 gcm). Note that the central angle θ of this magnet 2 is θ. is not limited to 108゛ in a strict sense, and some errors may be allowed on a practical level. For example, to explain the case where θa=120° to 180°, θ. is at least 10 packages゜±
From around 10° to the practical level (shown by the chain line in Figure 4)
(indicated by ■ and ■ in the figure). It should be noted that although the above-described embodiment is an example of a preferred embodiment of the present invention, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in this embodiment, the magnet is formed so that one block is formed for each magnetic pole, but it is arranged so that a predetermined number of 81 poles of a predetermined electrical angle are formed on a ring-shaped magnet material that makes the entire block into one block. It may also be formed by magnetism. Further, the present invention is not limited to outer rotor type or inner rotor type, but can also be applied to surface-facing (accurial) type rotating electric machines. In addition, in this example, two poles,
Although a three-phase motor with three salient poles has been described, the motor is not limited to this; 8l Number of poles: 2P Number of salient poles: k
It can also be applied to so-called multi-pole rotations ta such as a 86 12 9 16 12 20 15 24 18 28 21 32 24. In addition, the central angle θ per magnetic pole is shown in parentheses for each number of magnetic poles. is displayed in mechanical angles. Furthermore, although this embodiment is described as a motor, it can also be used as a generator. In this case, since the cogging torque is reduced, the generation of noise due to vibration is suppressed, and quiet generation can be provided. <<Effects of the Invention>> As is clear from the above explanation, the rotating electric machine of the present invention has the following effects:
Since the center angle of the magnet is set to 108° ± 10° in electrical angle, two types of static positions are established when not energized.
The position is twice that of a conventional rotating electric machine, that is, the stationary position (I+[), and cogging can be suppressed to a small level. Furthermore, the present invention reduces the cogging torque simply by setting the center angle and magnetization angle of the magnet to constant values, so each magnetic pole can be magnetized to saturation. Therefore, the rotating electric machine of the present invention has no decrease in magnetic flux, is less susceptible to Δ demagnetization due to the armature reaction magnetic field, and when used as a motor, can output torque larger than that of the conventional machine.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment in which the rotating electric machine of the present invention is applied to a motor with 4 magnetic poles and 3 protrusions, and Fig. 2 (A) and (B) are outer rollers constituting the rotating electric machine of the present invention. FIGS. 3A and 3B are front views showing an example of an evening type or stator magnet type magnet and an armature core, and FIGS. The front view shown in FIG. 4 shows rIlitx of the magnet center angle and cogging torque of the rotating electric machine of the present invention.
This is a graph showing the central angle of the armature core as a parameter. Figures 5 (A) to (G) are cogging torque characteristic diagrams in the states of ■ to ■ in Figure 4, and Figure 6 is a front view showing the stationary position of the rotary t-machine with a 4-3 configuration when not energized. ,(
A) shows the rotational position I, and (B) shows the rotational position ■.

Claims (2)

[Claims] (1) Equipped with a magnet having a number of magnetic poles of 4n (n is an integer of 1 or more) and an armature core having a number of salient poles of 3k (k is an integer of 1 or more) poles, one of which is connected to the other. A rotating electrical machine configured to rotate relative to the magnet, the central angle of each magnetic pole of the magnet being 108°±10 in electrical angle.
A rotating electric machine characterized in that the magnet and the armature core have two types of resting positions when not energized. (2) A rotating electrical machine characterized in that the central angle of each magnetic pole of the magnet according to claim 1 is approximately 108 degrees in electrical angle.