JP2000125490A - Permanent magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the maximum value of the resultant torque of the reluctance torque and the magnet torque of a permanent magnet motor while the magnet torque is maintained, and to realize high torque and high efficiency of the motor. SOLUTION: One permanent magnet 11 with a semicircular cross section is used for one pole of the rotor core 10 of an inner-rotor type permanent magnet motor. A part of the semicircular cross section of the permanent magnet 11 is cut off, so as to have the maximum value peak of magnet torque and the maximum value peak of reluctance torque match with each other. Four permanent magnets 11 with semicircular cross section which are partially chipped off are buried in the circumferential direction of the rotor core 10 at equal intervals. Further, polarities of adjacent permanent magnets 11 are male different.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner rotor type permanent magnet motor used for an air conditioner, a refrigerator and the like, and more particularly to a permanent magnet motor for increasing the maximum value of a combined torque by a magnet torque and a reluctance torque. It is about.

[0002]

2. Description of the Related Art As a permanent magnet motor having an inner rotor, for example, a motor having a configuration shown in FIG. 5 has been proposed.

[0003] In FIG. 5, a magnet-embedded field iron core (rotor core) 2 in a stator core 1 is formed by embedding one permanent magnet 3 having a substantially fan-shaped cross section for each pole, and extending in the circumferential direction by the number of poles. And the permanent magnets 3 adjacent to each other have different polarities. Reference numeral 4 denotes a hole through which the shaft passes (center hole; shaft hole).

[0004] Here, assuming that the magnetic flux distribution in the gap (between the teeth of the stator core and the permanent magnet) formed by the permanent magnet is sinusoidal, the torque T of the permanent magnet motor is T
= Pn ｛Φa ・ Ia ・ cosβ-0.5 (Ld-Lq)
It is represented by I ² · sin 2β｝. Here, T is the output torque, Φa is the armature interlinkage flux by the permanent magnets on the d and q coordinate axes, Ld and Lq are the d and q axis inductances, Ia is the amplitude of the armature current on the d and q coordinate axes, and β is The lead angle of the armature current on the d and q coordinate axes from the q axis, and Pn is the number of pole pairs.

[0005] In the above equation, the first term is the magnet torque by the permanent magnet, and the 22nd term is the reluctance torque generated by the difference between the d-axis inductance and the q-axis inductance. For details, see T.A. IEEE
E Japan, Vol. 117-D, No. 7, 199
See seven papers.

Further, according to the above-mentioned paper, it is described that the reluctance torque is effectively used by forming the permanent magnet of each pole in a multilayer structure. For example, the rotor core in the stator core 1 has two permanent magnets having a circular arc cross section per pole, that is, has a two-layer structure. this is,
The d-axis inductance Ld is smaller and the q-axis inductance Lq is smaller than in the case of one (one layer) per pole described above.
Is greatly increased, thereby increasing the value of the inductance difference (Ld-Lq) of the parameter in the above equation, and as a result, the motor torque T is increased. in this way,
If the reluctance torque is used effectively, the motor torque T
If the permanent magnet per pole has a multilayer structure, the reluctance torque can be more effectively used. For details, see the above-mentioned paper.

[0007]

By the way, in the permanent magnet electric motor, a path (magnetic path) of the magnetic flux from the stator core 1 is generated inside and outside a sector-shaped section, that is, a reluctance torque is generated (broken line in FIG. 6). Curve). In this case, the reluctance torque and the magnet torque (the two-dot chain line curve in FIG. 6) can be used.
The maximum peaks of the reluctance torque and the magnet torque are different (see FIG. 6). Therefore, as shown by the solid curve in FIG. 6, the maximum peak of the combined torque due to the reluctance torque and the magneto torque does not become so high, so that those torques cannot be used to the utmost, and the motor high torque, High efficiency is hindered.

Further, in the case of a rotor core having a permanent magnet having a multilayer structure described in the above-mentioned article, the above-mentioned disadvantages can be solved, but a plurality of permanent magnets are used per pole. Therefore, the manufacturing cost increases.
Therefore, in terms of manufacturing cost, it is preferable to use one permanent magnet per pole.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to maintain the magnet torque by using one permanent magnet per pole while matching the maximum peaks of the magnet torque and the reluctance torque. Accordingly, it is an object of the present invention to provide a permanent magnet electric motor capable of increasing the combined torque to effectively use the magnet torque and the reluctance torque, and thereby realizing high torque and high efficiency of the motor.

[0010]

In order to achieve the above object, the present invention provides a permanent magnet motor in which a magnet-embedded field core (rotor core) is disposed in a stator core, wherein the rotor core has one pole. One permanent magnet having a predetermined cross-sectional shape is used, and a part of the predetermined cross-sectional shape of the permanent magnet is cut out so that the maximum value peak of the magnet torque and the maximum value peak of the reluctance torque match. Are buried at equal intervals in the circumferential direction of the rotor core by the number of poles, and the adjacent permanent magnets have different poles.

In this case, it is preferable that a part of the permanent magnet having the predetermined shape is cut out in a fan shape, and the part of the permanent magnet is made of an electromagnetic steel plate.

According to the present invention, there is provided a permanent magnet electric motor in which a magnet-embedded field iron core (rotor core) is arranged in a stator core, wherein the rotor core uses one permanent magnet having a semicylindrical cross section per pole. A part of the permanent magnet cross-section is cut out so that the maximum value peak of the magnet torque and the maximum value peak of the reluctance torque match, and the bottom of the cut-out permanent magnet shape of the permanent magnet is cut to the center. The permanent magnets are buried at equal intervals in the circumferential direction of the rotor core by the number of poles while facing the hole and the curved portion of the cross section of the semicircular shape along the outer periphery of the rotor core. Is characterized as having a different polarity.

According to the present invention, there is provided a three-phase four-pole permanent magnet motor in which a magnet-embedded field iron core (rotor core) is arranged in a stator core, wherein the rotor core has one permanent magnet having a semicylindrical cross section per pole. Used, and cut out a part of the permanent magnet cross section at a position of 22.5 degrees (mechanical angle) from the d axis in the cross section of the permanent magnet, and cut the bottom of the cut semi permanent section of the permanent magnet. Along with facing the center hole, the curved portion of the cross section of the semicircular shape is arranged along the outer periphery of the rotor core, and the permanent magnets having the trapezoidal cross section are buried at equal intervals in the circumferential direction of the rotor core by the number of poles. A permanent magnet motor characterized in that the permanent magnets used are of different polarity.

In this case, it is preferable that a part of the permanent magnet having a semicylindrical cross section is cut out in a fan shape, and the part of the part cut out is made of an electromagnetic steel sheet.

The permanent magnet is preferably a ferrite magnet.

[0016] The rotor core may be incorporated into a DC brushless motor.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIGS. In the figure,
The same parts as those in FIG. 5 are denoted by the same reference numerals, and redundant description will be omitted. FIG. 4 corresponds to FIG.

The permanent magnet motor according to the present invention has one pole per pole.
The two permanent magnets have a predetermined cross section (for example, a semi-cylindrical cross section), generate reluctance torque, shift their phases, and adjust the maximum peak to the maximum peak of the magnet torque (see FIG. 4). It is noted that if a part of the cross section is cut off, the maximum value of the combined torque by the magnet torque and the reluctance torque can be increased without reducing the usage of the permanent magnet.

Therefore, as shown in FIG. 1 and FIG. 2, the rotor core (embedded field core) 10 of this three-phase four-pole permanent magnet motor has one permanent magnet (for example, ferrite) having a semi-cylindrical cross section per pole. Using a magnet 11, a part of this section is cut into a fan shape, and a part of the permanent magnet 11 having the section is cut toward the center hole 4, and the curved part is disposed toward the outer periphery of the core. And four permanent magnets 11 are buried at equal intervals in the circumferential direction, and
Adjacent poles of the permanent magnet 11 have different polarities.

As shown in FIGS. 1 and 3, a part a of the permanent magnet 11 is a curved portion having a semicylindrical cross section centered on a point 22.5 degrees (mechanical angle) from the d axis. (A portion indicated by a solid arrow a in FIG. 3), and is made of an electromagnetic steel plate made of the same material as a core described later.

That is, when a magnetic path region from the stator core 1 is formed around the d-axis as in the conventional example, the reluctance torque shown in FIG. 6 is generated. If the magnetic path region is formed around the axis, the maximum peak of the reluctance torque can be made to coincide with the maximum peak of the magnet torque as shown in FIG.

When the bottom of the permanent magnet 11 having a semicylindrical cross section is brought close to the center hole 4, the permanent magnet 1 is partially cut away.
1 (magnet amount) can be increased, and the magnet torque can be maintained as the total usage amount as in the related art.

As described above, the reluctance torque is generated at the portion where a part of the permanent magnet 11 is cut, and the phase of the reluctance torque is changed according to the cut portion.
When the maximum value peak is matched with the maximum value peak of the magnet torque, the maximum value of the combined torque of the magnet torque and the reluctance torque can be increased, thereby contributing to higher torque and higher efficiency of the motor.

Further, by forming the permanent magnet 11 in a semi-cylindrical cross section so that the bottom side of the semi-cylindrical shape is close to the center hole 4, the amount of the permanent magnet 11 used can be at least approximately the same as that of the prior art. Magnet torque can be maintained. In the above embodiment, the permanent magnet 11 has a semi-cylindrical sectional shape, but it is apparent that the present invention can be applied to other sectional shapes.

In manufacturing the rotor core 10, a core laminating system (automatic laminating system) is used in which an electromagnetic steel sheet is punched out by an automatic press using a core press die and caulked in the die to be integrally formed.

In this press working step, at least the center hole 4 and the buried hole of the permanent magnet 11 are punched out and, as shown in FIG. 2, are automatically pressed and laminated while caulking the core sheet 10a to form the rotor core 10. . At this time, it is preferable to form a hole or a caulked portion through which rivets are passed.

Thereafter, the permanent magnet 11 is formed in a semi-cylindrical cross-section which is partially cut off by the cutout a, and the permanent magnet 11 formed of a low-cost ferrite magnet is buried in the hole formed by the press. Is magnetized and magnetized in the thickness direction (radial direction of the rotor core 10). Further, after covering both ends of the rotor core 10, the rotor core 10 is caulked through rivets, and the production of the rotor core 10 is completed. Therefore,
The manufacturing cost of the rotor core 10 is almost the same as the conventional one.

Referring additionally to FIG. 1, this is the case where the permanent magnet motor is a three-phase four-pole motor, and the stator core 10 having 24 slots has U-phase, V-phase and W-phase armature windings. The outer diameter side armature winding is U-phase, the inner diameter side armature winding is W-phase, and the intermediate armature winding is V-phase. The number of lines may be different.

If the rotor core 10 is used for a DC brushless motor and is applied to, for example, a compressor of an air conditioner, the performance and reliability of the air conditioner can be improved.

[0030]

As described above, according to the first aspect of the present invention, in the permanent magnet motor in which the magnet-embedded field core (rotor core) is disposed in the stator core, the rotor core is provided. Is a method in which one permanent magnet having a predetermined cross-sectional shape is used for one pole, and a part of the predetermined cross-sectional shape of the permanent magnet is cut off so that the maximum value peak of the magnet torque and the maximum value peak of the reluctance torque match. Since a part of the permanent magnet is cut off and buried at equal intervals in the circumferential direction of the rotor core by the number of poles, and the adjacent permanent magnet is made to have a different polarity,
Cost reduction can be expected by using one permanent magnet per pole, and the amount of use (magnet amount) can be reduced by the shape of the permanent magnet. Therefore, while maintaining the magnet torque, the path (magnetic path) of the magnetic flux from the stator core is secured, and the maximum peak of the reluctance torque is matched with the maximum peak of the magnet torque to raise the maximum value of the combined torque. Therefore, there is an effect that high torque and high efficiency of the motor can be realized.

According to the second aspect of the present invention, the shape of the permanent magnet having a predetermined shape in the first aspect is a fan shape, and the partially cut portion is made of an electromagnetic steel sheet. In addition to the effect of item 1, there is an effect that the magnetic flux from the stator core partially follows the cutout portion, thereby contributing to the generation of reluctance torque and increasing the maximum value of the combined torque.

According to the third aspect of the present invention, in the permanent magnet motor having the magnet core embedded in the stator core (rotor core), the rotor core includes one permanent magnet having a semicylindrical cross section per pole. Used, and cut out a part of the semicircular shape of the permanent magnet so that the maximum value peak of the magnet torque and the maximum value peak of the reluctance torque match, and the semicylindrical shape of the cutaway permanent magnet Of the rotor core is oriented along the outer periphery of the rotor core, and the permanent magnets are buried at equal intervals in the circumferential direction of the rotor core by the number of poles. Since the permanent magnets used are of different polarity, cost reduction can be expected by using one permanent magnet per pole. While the magnet torque can be maintained without reducing the stone usage (magnet amount), the path of magnetic flux from the stator core (magnetic path) is secured, and the maximum peak of the reluctance torque becomes the maximum peak of the magnet torque. In addition, since the maximum value of the combined torque can be increased, there is an effect that high torque and high efficiency of the motor can be realized.

According to a fourth aspect of the present invention, in a three-phase four-pole permanent magnet motor in which a magnet-embedded field core (rotor core) is disposed in a stator core, the rotor core has a semi-cylindrical cross section per pole. One permanent magnet is used, and a part is cut off at a position of 22.5 degrees (mechanical angle) from the d-axis in the semicylindrical cross section of the permanent magnet,
The bottom of the semicircular section of the permanent magnet whose part is cut out is directed toward the center hole, and the curved portion of the semicircular section is arranged along the outer periphery of the rotor core. Since the permanent magnets are buried at equal intervals in the direction and the adjacent permanent magnets are made of different poles, cost reduction can be expected by using one permanent magnet per pole, While the magnet torque can be maintained without reducing the usage amount (magnet amount) of the permanent magnet, the path of the magnetic flux from the stator core (magnetic path) is secured, and the phase of the maximum value peak of the reluctance torque is 45 degrees (electricity). The maximum value of the combined torque can be raised in accordance with the peak value of the magnet torque by shifting the angle) to realize high torque and high efficiency of the motor. There is an effect that it is Rukoto.

According to the fifth aspect of the present invention, the permanent magnet having a semi-cylindrical cross section according to the third or fourth aspect has a fan shape, and the partially cut portion is made of an electromagnetic steel plate. Therefore, in addition to the effects of the third and fourth aspects, the magnetic flux from the stator core partially follows the cutout portion, thereby contributing to the generation of reluctance torque and increasing the maximum value of the combined torque.

According to the invention of claim 6, according to claim 1,
Since the permanent magnet in 2, 3, 4 or 5 is a ferrite magnet, in addition to the effects of claims 1, 2, 3, 4 or 5, the required magnet torque can be achieved without using expensive materials such as rare earth magnets. And a reluctance torque can be obtained, that is, there is an effect that a low-cost and high-efficiency motor can be realized.

According to the invention described in claim 7, according to claim 1,
A DC brushless motor is obtained by incorporating the rotor core of 2, 3, 4, 5 or 6,
In addition to the effects of 2, 3, 4, 5 or 6, when applied to a motor such as a compressor of an air conditioner, the performance and reliability of the air conditioner can be improved, and the cost can be reduced. This has the effect.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a permanent magnet electric motor for describing an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a rotor core constituting the permanent magnet motor shown in FIG.

FIG. 3 is a schematic plan view of the rotor core shown in FIG. 1;

FIG. 4 is a schematic graph for explaining torque generation by the permanent magnet motor shown in FIG. 1;

FIG. 5 is a schematic plan view illustrating a conventional permanent magnet motor.

FIG. 6 is a schematic graph for explaining torque generation by the permanent magnet electric motor shown in FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 Stator core 4 Center hole (shaft hole for shaft) 10 Rotor core (magnet embedded field iron core) 11 Permanent magnet (ferrite magnet)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshifumi Fukuda 1116, Suenaga, Takatsu-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu General Limited (Reference) 5H622 AA03 CA02 CA07 CA10 CA13 CB04 CB05 DD01 PP03 PP10 PP16 PP18 PP19

Claims (7)

[Claims] In a permanent magnet electric motor having a magnet core embedded in a stator core (rotor core), the rotor co uses one permanent magnet having a predetermined cross-sectional shape per pole and the magnet torque. A part of the predetermined cross-sectional shape of the permanent magnet is cut out so that the maximum value peak of the permanent magnet matches the maximum value peak of the reluctance torque, and the permanent magnet having the part cut out is cut into the number of poles in the circumferential direction of the rotor core. A permanent magnet motor, wherein the permanent magnets are buried at equal intervals and the adjacent permanent magnets have different polarities. 2. The permanent magnet electric motor according to claim 1, wherein a shape of a part of the permanent magnet of a predetermined shape is a fan shape, and the part of the permanent magnet is made of an electromagnetic steel plate. 3. A permanent magnet motor in which a magnet-embedded field core (rotor core) is arranged in a stator core, wherein the rotor core uses one permanent magnet having a semi-cylindrical cross section for each pole and the magnet torque. A part of the cross section of the permanent magnet is cut out so as to match the maximum peak of the maximum value and the maximum value peak of the reluctance torque, and the bottom of the cross section of the permanent magnet whose part is cut off is formed in the center hole. At the same time, the curved portion of the semicircular section is made to follow the outer periphery of the rotor core, the permanent magnets are buried at equal intervals in the circumferential direction of the rotor core by the number of poles, and the adjacent permanent magnets are different. A permanent magnet electric motor characterized by becoming a pole. 4. A three-phase four-pole permanent magnet motor in which a magnet-embedded field iron core (rotor core) is disposed in a stator core, wherein the rotor core uses one permanent magnet having a semi-cylindrical cross section for each pole. In addition, a part of the permanent magnet section is cut out at a position of 22.5 degrees (mechanical angle) from the d axis in the cross section of the permanent magnet, and the bottom of the cut section of the permanent magnet is cut to the center. Along with facing the hole, the curved portion of the cross section of the semicircular shape is along the outer periphery of the rotor core, and the permanent magnets of the trapezoidal cross section are buried at equal intervals in the circumferential direction of the rotor core by the number of poles, and the adjacent magnets A permanent magnet motor characterized in that the permanent magnets have different polarities. 5. The permanent magnet electric motor according to claim 3, wherein a shape of a part of the permanent magnet having a semicylindrical cross-section is a fan shape, and the part of the permanent magnet is made of an electromagnetic steel plate. 6. The permanent magnet motor according to claim 1, wherein the permanent magnet is a ferrite magnet. 7. The permanent magnet motor according to claim 1, wherein said rotor core is incorporated to form a DC brushless motor.