JPH07118895B2 - 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 is a cause of impairing the smoothness of rotation, 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 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 magnet.

(Means for Solving the Problems) In order to achieve such an object, the present invention provides a magnet having a magnetic pole number of 4n (n is an integer of 1 or more) and 3k (k is 1).
And an armature core having a salient pole number of
A rotary electric machine configured to rotate one of them with respect to the other, wherein the central angle of each salient pole of the armature core facing the magnet is an electrical angle of 159 ° ± 10 ° or 2
01 ° ± 10 °, preferably about 159 ° or about 201 °, so that two types of stationary positions of the magnet and the armature core when the terminals of the armature coil wound around the armature core are opened are displayed. I have to.

(Operation) Therefore, by setting the central angle of each salient pole of the armature core to an electrical angle of 159 ° ± 10 ° or 201 ° ± 10 °, the above-mentioned two types of stationary of the magnet and the armature core are set. Both the positions (I) and (II) are likely to appear, and the number of stationary times is 7 times / 360 ° or more, which is larger than the conventional 6 times / 360 °. Then, at about 159 ° or about 201 °, both the stationary positions (I) and (II) are completely established regardless of the magnitude of the central angle of the magnet, and the stationary positions (I) and (II) are shown in FIGS. 6A and 6B. The stationary positions of the two types of cogging with different phases shown in () alternately appear, and the cogging has the smallest amplitude and the shortest wavelength, that is, changes to the minimum cogging torque.

(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, in which two arc-shaped magnets 2 are evenly or substantially evenly arranged at substantially equal intervals on the inner peripheral surface of a motor case yoke 1. There is. Each magnet 2 is magnetized in the thickness direction, and one magnet constitutes one magnetic pole. Second
The central angle θ of each magnet 2 shown in the drawing or FIG.
_M is set to an arbitrary angle, for example, an electrical angle of 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. Central angle θ of each salient pole 4
_a is an electrical angle of 159 ° ± 10 ° or 201 ° ± 10 °, preferably about 159 ° or about 201 °. In the case of the present embodiment, since the magnetic pole pair is 2, the electrical angle and the mechanical angle do not match,
The central angle θ _a becomes about 79.5 ° or about 100.5 °, which is 1/2 of the mechanical angle.

Here, the central angle θ _a of each salient pole 4 of the armature core 3 is
The two points on the circumference of the salient pole 4 are the angles sandwiching the center O, and are the angles per salient pole. When the central angle θ _a of each salient pole 4 is set to an electrical angle of about 159 ° or about 201 °,
The best cogging characteristic can be obtained regardless of the central angle θ _M of the magnet 2. However, if the cogging torque is simply kept within a region smaller than the level generally considered to be small for practical use (the range shown by the chain line in FIG. 4), θ _a is strictly about 159 ° or about It is not necessary to set the angle to 201 °, and it may be slightly different depending on the central angle θ _M of the salient pole 4,
_The maximum electrical angle is 159 ° ± 10 ° or 201 in proportion to the size of _M
There is no problem if it is set in the range of ± 10 °. Further, the central angle θ _M per magnetic pole of the magnet 2 is 90 to 180 in electrical angle.
It is taken at around 90 °, preferably around 108 °. In order to obtain a practical level of cogging torque characteristic, the central angle θ _M of the magnet 2 is set to
If it is set to 180 °, it cannot be manufactured unless the condition is good in terms of accuracy, but if it is set in the range of 90 ° to 120 °, the cogging torque can be kept at a practical level even if the condition is not good in terms of accuracy. That is, θ _a is 159 ° ± 10 ° in electrical angle
Alternatively, the range of 201 ° ± 10 ° is considered to be 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 θ _a are as illustrated.

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 four magnetic poles and the 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 projecting inside the cylindrical core, and each armature coil is wound. The central angles θ _M and θ _{a in} this case are as illustrated.

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 _a and cogging with θ _M 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, the stationary position (I) shown in FIG. 6 (A) or the stationary position (II) shown in FIG. 6 (B).
Take one of. Here, the two types of stationary positions generally mean that the armature core and the magnet rotor are stably attracted by magnetic attraction when the magnet rotor is rotated in a state where the armature coil is not excited. It refers to the stop position in the state shown in A) or (B). The cogging torque means the torque required to escape from the stopped position. In general, the number of cogging torques generated is 6 electrical angles / 3
It has been experimentally confirmed to be 60 °. This state is typically represented by the stationary position (I) or the stationary position (II) in FIG. 4, and the cogging torque characteristic at that time is represented by the cogging torque (A) (B) or (F) in FIG. )
(G) is representative. More specifically, (I), (I
Fourth, the rest position of I) is
The central angle θ _a of each salient pole 4 of the armature core 3 is 159 ° or 2
Appears when the distance is larger than 01 °. At that time, the cogging torque characteristic of the stationary position (I) in the region of [I] and the stationary position (I
The cogging characteristic of I) [Fig. 5 (G)] is different only in the phase and has the number of rests of 6 times / 360 °. At this time, the cogging torque has a relatively large value. And θ _a
As one approaches = 159 ° or 201 °, at some angle the transition of the rest position occurs. The cogging torque in the region shown by and in FIG. 4 which is the transition region has a small amplitude as shown in FIGS. 5 (B) and 5 (F). Therefore, when θ _a is further brought close to 159 ° or 201 ° as in the region shown by and in FIG. 4, the corresponding cogging torque characteristics are as shown in FIG. 5 (C) and FIG. 5 (E). Some characteristics of the stationary position (II) start to appear in the cogging torque characteristic of the stationary position (I), or some characteristics of the stationary position (I) start to appear in the cogging torque characteristic of the stationary position (II), and amplitude and wavelength Compression occurs. That is, a transition phenomenon of the stationary position conversion occurs. Then, when θ _{a is set} to about 159 ° or 201 ° as in the region shown by in FIG. 4, both the stationary positions (I) and (II) are completely established, and two types of cogging torque of different phases are obtained. The stationary positions appear alternately, the amplitude changes and the wavelength changes to the cogging torque characteristic as shown in FIG. 5 (D). That is, the cogging torque becomes the minimum. Therefore, the central angle per magnetic pole θ
_{When a} is set to an electrical angle of about 159 ° or 201 °, cogging becomes the best regardless of the size of the central angle θ _M per magnetic pole of the magnet 2. At this time, the stationary position is 6 times / 360 °
From 12 times / 360 °, it doubles. Visual inspection confirmed that the cogging was reduced, and a stationary position of 7 to 12 times / 360 ° was confirmed. By the way, the cogging torque at this time is in the case of the conventional method of reducing the cogging torque by the magnetization control (5 to 3 gcm).
It was possible to reduce it to less than half (1.5 to 1.0 gcm) compared to. The central angle θ _a of each salient pole 4 of the armature core 3 is not strictly limited to 159 ° or 201 ° (electrical angle), and a slight error can be allowed at a practical level. For example, in the case of θ _M = 90 ° to 180 °, θ _a is at least 159 ° ± 10 ° or 201 in electrical angle.
From around ± 10 °, it falls within the practical level (indicated by in the figure) indicated by the chain line in Fig. 4.

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. Further, in this embodiment, four poles,
The three-phase motor with three salient poles has been explained, but the number of magnetic poles is 2P, and 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.

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
The central angle of each salient pole of the armature core is an electrical angle of 159 ° ± 10
Or 201 ° ± 10 °, preferably about 159 ° or about 201 °, the stationary position (I) shown in FIG. 6 (A)
And two stationary positions (II) shown in FIG. 6 (B) are alternately established as shown in FIG. 4 (D), which is twice the conventional rotating electric machine, that is, the stationary position (I + II). As a result, the cogging of the pulsating flow is suppressed to the minimum. Moreover, according to the present invention, the cogging torque is reduced only by setting the central angle of each salient pole of the armature core to a constant value, so that each magnetic pole can be saturated and magnetized. Therefore, the rotating electric machine of the present invention does not reduce the magnetic flux, is less susceptible to demagnetization due to the armature reaction magnetic field, and when used as a motor, the output torque can be made larger than before.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing an embodiment in which the rotary electric machine of the present invention is applied to a motor having four magnetic poles and three salient poles, and FIGS. 2 (A) and 2 (B) show the present invention. FIG. 3A and FIG. 3B are front views showing an example of an outer rotor type or stator magnet type magnet and an armature core constituting a rotating electric machine, and FIGS. 3A and 3B are inner rotor type magnets and armatures of the rotating electric machine of the present invention. FIG. 4 is a front view showing an embodiment of the core, and FIG. 4 is a graph showing the relationship between the central angle of the armature core of the rotating electric machine of the present invention and cogging with the central angle of the magnet as a parameter. 5 (A) to (G) are cogging torque characteristic diagrams in the states of FIG. 4 to, and FIG. 6 is a front view showing a stationary position when the terminals of the armature coil of the rotating electric machine of 4 to 3 configuration are opened. (A) is the rest position (I), (B) is the rest position (II)
Indicates. 2 ... magnet, 3 ... armature core, 4 ... salient pole, the central angle of each of the salient poles of theta _{a ...} armature core.

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 electric machine configured to rotate with respect to the other, the central angle of each salient pole of the armature core facing the magnet is an electrical angle of 159 ° ± 10 ° or 201 ° ± 10 °, A rotating electric machine, wherein two types of stationary positions of the magnet and the armature core when the terminals of the armature coil wound around the armature core are opened are made to appear. 2. A rotating electric machine according to claim 1, wherein a central angle of each salient pole of the armature core is about 159 ° or about 201 ° in electrical angle.