JPH0720361B2 - Rotating electric machine - Google Patents

Description

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 electric machine that reduces cogging torque.

(Prior Art) In a permanent magnet field motor such as a DC motor,
The 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. Since this cogging torque causes the smoothness of rotation to be impaired, it is desirable to keep it small.

As one of conventional methods for reducing cogging torque, the magnetizing condition of the magnet is changed by controlling the voltage and capacity of the magnetizer to determine the best point at which the cogging can be suppressed. For example, unsaturated magnetization is performed by changing the magnetizing conditions so that the magnetization distribution on the magnet surface exhibits a sinusoidal shape. In this case, the best cogging point can be easily determined regardless of the central angle of the salient pole portion of the core.

(Problems to be Solved by the Invention) However, since the magnets are in the unsaturated magnetization state, the magnetization distributions of the individual magnets are slightly different,
There is a problem that the size of cogging varies from motor to motor and stable characteristics cannot be obtained. Further, since the magnet is unsaturatedly 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, the change in the magnetic flux is unsaturatedly magnetized so as to have a sinusoidal change, so that there is a drawback in that the number of magnetic fluxes sufficient to obtain a large output torque cannot be obtained. In addition, since the unsaturated magnetized magnet is demagnetized by the armature reaction magnetic field, there is a problem that the number of magnetic flux decreases and the output torque also decreases.

An object of the present invention is to provide a rotating electric machine having a small cogging torque. A further object of the present invention is to provide a rotating electric machine that can reduce the cogging torque regardless of the central angle of the salient poles of the armature core.

(Means for Solving the Problem) In order to achieve such an object, the rotating electric machine of the present invention is
A magnet having a number of magnetic poles (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) are provided, and one of them rotates with respect to the other. In the rotating electric machine configured as described above, the central angle per magnetic pole of the magnet is 108 ° ± 10 ° in electrical angle, preferably about 108 °, and two types of stationary positions appear when there is no excitation. .

(Operation) Therefore, both the two stationary positions (I) and (II) in the non-excitation of the magnet or the armature core are likely to appear, and the stationary frequency is 7 times, which is more than the conventional 6 times / 360 °.
/ 360 ° or more. Then, at about 108 °, both the stationary positions (I) and (II) are completely established regardless of the size of the central angle of the salient poles of the armature core, and the stationary positions of two types of cogging having different phases are obtained. They appear alternately and have small amplitude and short wavelength.

(Example) Hereinafter, the structure of the present invention will be described in detail based on an example shown in the drawings.

An embodiment in which the present invention is applied to a motor is shown in FIG. This motor is an outer rotor type motor having a structure of four magnetic poles and three salient poles, and four arc-shaped magnets 2 are evenly arranged at equal intervals on the inner peripheral surface of a motor case yoke 1. Each magnet 2 is magnetized in the thickness direction, and one magnet constitutes one magnetic pole. The central angle θ _M of each magnet 2 is set to an electrical angle of 108 ° ± 10 °, preferably about 108 °. A stator core 3 having salient poles 4 is axially supported on the yoke 1 along its central axis, and each salient pole 4 is arranged so as to face the inner peripheral surface of the magnet 2. The yoke 1 and the magnet 2 are rotatably provided around the stator core 3. The salient poles 4 of the core 3 are three, and the coil 5 is wound around each salient pole 4. Each salient pole 4
The central angle θa is about 120 ° to 180 ° in electrical angle
It is set to ゜. In this embodiment, the magnetic pole pair is 2
Therefore, the electrical angle and the mechanical angle do not match, and the central angle θ _M is 1/2 the mechanical angle.

Here, the central angle θ _M per magnetic pole of the magnet 2 is
Both ends and two points on the circumference of a magnetized portion forming one magnetic pole of the magnet mean an angle between which the center O is sandwiched, and a magnetized angle per one magnetic pole. When the central angle θ _M per magnetic pole of the magnet 2 is set to an electrical angle of about 108 °, the armature core 3
The best cogging characteristic is obtained regardless of the central angle θa of the salient pole 4. However, in the case where the cogging torque is simply suppressed within a region smaller than the level (range shown by the chain line in FIG. 4) generally considered to be small for practical use,
It is not necessary to set θ _M strictly to about 108 °, and it may be slightly different depending on the central angle θa of the salient pole 4, but if it is set in the range of 108 ° ± 10 ° at the maximum in proportion to the magnitude of θa, there will be a problem. Absent. For example, when the central angle θa of the salient pole 4 of the armature core 3 is set to an electrical angle of θa = 120 ° or 180 °, in order to obtain a practical level of cogging torque characteristic, the central angle θ _{M of the} magnet is an electrical angle. It is sufficient to set it in the range of at least 108 ° ± 10 °. This value is considered to be well within the manufacturing error.

FIGS. 2A and 2B show an example of the structure of the magnet and the armature core in the case of the outer rotor type motor or the stator magnet type having the four magnetic poles and the three salient poles. The magnets 2 are fixed to the inner peripheral surface of the cylindrical yoke 1 at equal intervals, and the armature core is integrally formed with three arcuate salient poles protruding outward on the peripheral surface of the shaft portion. Center angle θ in this case
_M and θa are as shown.

FIGS. 3A and 3B show an example of the structure of the magnet and the armature core in the case of the inner rotor type motor having the structure of four magnetic poles and three salient poles. Magnet 2 is a spindle-shaped yoke 1
It is fixed to the peripheral surface of the at equal intervals. Further, the armature core 3 has three arcuate salient poles 4 protruding inside the cylindrical core, and an armature coil is wound around each of the salient poles 4. The central angles θ _M and θa in this case are as shown in the figure.

According to the rotary electric machine configured as described above, the cogging torque is reduced as follows.

The characteristic diagram of FIG. 5 is an experimental result, and shows the relationship between θ _M and cogging with θ a as a parameter. As is clear from this experiment, normally, a 4-n-pole magnet and a 3-k salient pole armature core are used.
In the rotating electric machine of three configurations, FIG.
The stationary position (I) shown in FIG. 6 or the stationary position (II) shown in FIG. 6B is taken. This stationary position is taken when the central angle θ _M of the magnet 2 is farther than 108 ° (indicated by in FIG. 4). At that time, the cogging torque characteristic at the stationary position I [FIG. 5 (A)] and the cogging characteristic at the stationary position (II) [FIG. Has a number of rests of °. Then, as θ _M = 108 ° is approached, the conversion of the stationary position occurs at a certain angle. The transient region (in Fig. 4,
As shown in FIGS. 5B and 5F, the amplitude of the cogging torque in FIG. Therefore, when θ _M is further brought close to 108 °, as shown in FIGS. 5 (C) and 5 (E), a characteristic at the stationary position (II) appears slightly in the cogging torque characteristic at the stationary position (I). Or a characteristic at the stationary position (I) starts to appear in the cogging torque characteristic at the stationary position (II), and the amplitude and the wavelength are compressed. That is, a transition phenomenon of the stationary position conversion occurs. Then, at approximately 108 °, the rest positions (I) and (II)
Both are completely satisfied, the stationary positions of two types of cogging torque having different phases appear alternately, and the cogging torque characteristic changes as shown in FIG. 5D with small amplitude and short wavelength. Therefore, when the central angle θ _M per magnetic pole is set to an electrical angle of about 108 °, the cogging is best regardless of the size of the central angle θa of the salient pole 4 of the armature core 3. At this time, the stationary position doubles from 6 times / 360 ° to 12 times / 360 °. Visual check confirms that cogging is reduced 7-12 times.
The stationary position of / 360 ° was confirmed. By the way, the cogging torque at this time is less than half (1.5-3.5g) compared to the conventional cogging torque reduction method (5-3g cm).
Could be reduced to 1.0 g cm). The central angle θ _M of the magnet 2 is not strictly limited to 108 °, and a slight error can be tolerated at a practical level. For example, in the case of θa = 120 ° to 180 °, θ _M is at least 108 ° ± 10 ° from the fourth point.
It fits within the practical level indicated by the chain line in the figure (indicated by in the figure).

It should be noted that the above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the magnet forms one block for each magnetic pole, but the magnet is magnetized so that a predetermined number of magnetic poles having a predetermined electrical angle are formed on a ring-shaped magnet material having one block as a whole. You may form by.

Further, the present invention is not limited to the outer rotor type or the inner rotor type, but can be applied to a surface-opposing (axial) rotary electric machine. In addition, in this embodiment, two poles,
The three-phase motor with three salient poles has been described, but the number of magnetic poles is 2P. The number of salient poles is ka 8 6 12 9 16 12 20 15 24 18 28 21 32 24. It can also be applied to electric machines. The center angle θ _M per magnetic pole is displayed in mechanical angle in parentheses for each magnetic pole number.

Furthermore, although a motor is described in this embodiment, it can also be used as a generator. In this case, since the cogging torque is reduced, noise generation due to vibration is suppressed, and a quiet generator can be provided.

(Effect of the invention) As is apparent from the above description, the rotating electric machine of the present invention is
Since the center angle of the magnet is set to 108 ° ± 10 ° in terms of electrical angle, two types of stationary positions are established when there is no excitation, which is twice the conventional rotating electric machine, that is, the stationary position (I + II), resulting in cogging. Can be kept small. Moreover, in the present invention, the cogging torque is reduced only by setting the center angle and the magnetizing angle of the magnet to constant values, so that each magnetic pole can be saturated and magnetized. Therefore, the rotating electrical machine of the present invention has no decrease in magnetic flux and is less susceptible to demagnetization due to the armature reaction magnetic field,
When used as a motor, the output torque can be made larger than before.

[Brief description 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 having a four-pole and three-salient pole configuration, and FIGS. 2A and 2B are outer rotors constituting the rotating electric machine of the present invention. Type or stator magnet type magnet and front view showing an example of an armature core, FIGS. 3 (A) and 3 (B) show an embodiment of an inner rotor type magnet and armature core of a rotating electric machine according to the present invention. A front view and FIG. 4 are graphs showing the relationship between the magnet central angle and the cogging torque of the rotating electric machine of the present invention, with the central angle of the armature core being a parameter. FIGS. 5A to 5G are cogging torque characteristic diagrams in the states of FIG. 4 to FIG. 6, and FIG. 6 is a front view showing a stationary position of the rotating electric machine of the configuration 4-3 during non-excitation. ) Indicates the rotational position I, and (B) indicates the rotational position II. 2 ... Magnet, 3 ... Armature core, θ _M ...... Central angle per magnetic pole of the magnet.

Claims (2)

[Claims] 1. A magnet having a magnetic pole number of 4n (n is an integer of 1 or more) poles, and an armature core having a salient pole number of 3k (k is an integer of 1 or more) poles, one of which is provided. A rotating electrical machine configured to rotate with respect to the other, wherein a central angle per magnetic pole of the magnet is 108 ° ± 10 ° in electrical angle, and when the magnet and the armature core are not excited. A rotating electric machine characterized by having two stationary positions appear. 2. A rotating electric machine according to claim 1, wherein a central angle per magnetic pole of the magnet according to claim 1 is an electrical angle of about 108 °.