JP2001086718A - Self-start type permanent-magnet synchronous motor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly efficient low-noise bipolar self-start type permanent- magnet synchronous motor by adjusting the magnetic flux density distribution in the void section, between the stator and rotor of the motor to a sine wave. SOLUTION: An isotropic ring-like permanent magnet 6 of a self-start type permanent-magnet synchronous motor is magnetized by applying a parallel magnetic field H to the magnet. Consequently, two rotor magnetic poles magnetized in a direction 8, which is parallel to a line A-A' connecting the center of a shaft 9 to a centers 10 of the poles are formed and the magnetic flux density distribution in the void section between the stator, and rotor of the motor becomes a sine wave. In addition, the higher harmonics components of the magnetic flux density distribution in the void section disappear, and the iron loss can be reduced. Consequently, the noise of the motor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-starting permanent magnet type synchronous motor used for electric compressors for refrigeration and air conditioning equipment and other general industries, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A self-starting type permanent magnet synchronous motor operates as an induction motor by a squirrel-cage conductor for starting a rotor at the time of starting, and is synchronized by a rotor magnetic pole created by a permanent magnet when the rotor reaches a speed near a synchronous speed. Although it is drawn into the speed and enters the synchronous speed, it is widely used for general industry and other purposes because of its excellent performance such as constant speed operation and high efficiency. Improvements have been made.

A conventional self-starting type permanent magnet synchronous motor rotor is generally disclosed in Japanese Patent Publication No. 59-23179. Hereinafter, the conventional self-starting type permanent magnet synchronous motor will be described with reference to the drawings.

FIG. 2 shows an example of two poles. 1 is a rotor, 2 is a rotor core, a conductor bar 4 is arranged in a plurality of slots 3 provided near the outer periphery of the rotor core 2, and both ends of the conductor bar 4 are short-circuited by short-circuit rings. A starting cage conductor is formed. Although not shown, the short-circuit ring is made of a ring-shaped conductive material disposed at both axial ends of the rotor core, and is connected to each conductor bar 4. A plurality of holes 5 for embedding permanent magnets are provided inside the conductor bar 4, and permanent magnets 6 are embedded therein. Reference numeral 7 denotes a slit for preventing magnetic flux short-circuiting between different poles of the permanent magnet, and by sufficiently reducing a distance P between the slit 7 for preventing magnetic flux short-circuiting and the hole 5 for embedding the permanent magnet, It is configured to magnetically saturate between the magnetic flux shorting 5 and the magnetic flux short-circuit prevention slit 7 to prevent magnetic flux short-circuiting between different poles by a permanent magnet.

Conventionally, adjacent slots 4 of the rotor core 2
The distance T1 was constant at each location.
Further, the radial length H1 of the slot 4 is also constant, and when the rotor core 2 has such a shape, the distance T between the adjacent slots located near the end of the rotor magnetic pole and the slot 3
Since the distance Y1 between the permanent magnet and the hole 5 for embedding the permanent magnet has a sufficiently wide magnetic path width, the magnetic flux coming out of the permanent magnet 6 causes the outer peripheral surface near the end of the rotor magnetic pole to reach other places. It will flow out to the same extent as the outer peripheral surface. As a result, the magnetic flux density distribution in the air gap between the stator and the rotor when no voltage is applied to the stator winding and the magnetic field generated by the winding is not applied to the rotor has the vertical axis representing the magnetic flux density. Bg, and when the horizontal axis is the angle θ in the rotation direction of the gap when the origin is the distance between the rotor magnetic poles, a rectangular wave is formed as shown in FIG. As a result, the magnetic flux density distribution in the air gap portion contains many harmonic components, so that the iron loss is large and the efficiency of the motor remains at a low value, and the noise of the motor is also high.

[0006]

In the conventional self-starting permanent magnet synchronous motor as described above, the distance between all the slots of the rotor core is constant, and the radial length of all the slots is constant. Since the voltage is not applied to the stator winding and the magnetic field due to the winding is not applied to the rotor, the magnetic flux density distribution in the air gap between the stator and the rotor is Become. Due to this, since the magnetic flux density distribution in the air gap contains many harmonic components, there is a problem that the iron loss is large and the motor cannot obtain high efficiency, and the noise of the motor is high.

The present invention has been made to solve the above-mentioned problems, and the magnetic flux density distribution in the air gap between the stator and the rotor is made to be a sine wave so that harmonic components of the magnetic flux density distribution in the air gap can be eliminated. It is an object of the present invention to provide a self-starting permanent magnet type synchronous motor that achieves high efficiency by reducing loss and has low noise, and a method of manufacturing the same.

[0008]

SUMMARY OF THE INVENTION In order to achieve this object, the present invention provides an isotropic ring-shaped permanent magnet having an easy axis of magnetization in an arbitrary direction and arranged on the outer periphery of a rotor core. A parallel magnetic field is applied to the two poles so that the magnetization directions in the inside are all parallel to a line connecting the center of the pole and the center of the rotor axis in a cross section perpendicular to the axis of the rotor.

The distribution of the magnetic flux density in the air gap when no voltage is applied to the winding of the stator and no magnetic field is applied to the rotor will be described with reference to FIGS. 4 and 5. FIG.

In FIG. 4, 1 is a rotor, and 2 is a rotor core. An isotropic ring-shaped permanent magnet 6 is arranged so as to cover the outer periphery of the rotor core 2. Slot 3 for disposing a plurality of conductor bars 4 near the outer periphery of rotor core 2
The conductor bar 4 and short-circuit rings (not shown) at both ends in the axial direction of the rotor core are integrally formed by aluminum die casting to form a starting cage conductor. If the point between the poles on the surface of the rotor is the origin and the point where the angle in the rotation direction is θ is the point P, the magnetic flux density B at the point P on the surface of the rotor is the center 10 of the poles and the axis of the rotor. 9 is parallel to a line AA ′ connecting the centers of the nine components, and is divided into a radial component Br and a θ component Bθ. Br is represented by equation (1).

Br = Bsin θ (1) Since the gap is very narrow because the gap is very narrow from the surface of the rotor, the magnetic flux density Bg of the gap is
(Θ) is a value close to the magnetic flux density on the surface of the rotor. Therefore, the magnetic flux density Bg (θ) of the air gap is expressed by equation (2).

Bg (θ) ≒ Br (2) Here, when equation (1) is substituted, Bg (θ) ｓBsinθ (3), so that B is constant regardless of θ. When the permanent magnet is magnetized with a parallel magnetic field in the radial direction as shown in FIG. 5, the magnetic flux density distribution in the gap becomes a sine wave when the vertical axis is the magnetic flux density in the gap and the horizontal axis is θ.

As a result, higher harmonic components of the magnetic flux density distribution in the air gap can be eliminated and iron loss can be reduced as compared with the conventional example, so that a highly efficient, low noise, two-pole self-starting type permanent magnet type synchronous motor can be obtained. It can be.

On the other hand, when a radially anisotropic permanent magnet is used, Br is constant irrespective of θ except for the gap, so that the magnetic flux density distribution on the rotor surface is a rectangular wave. As a result, the magnetic flux density distribution in the gap also becomes a rectangular wave. Therefore, when a radially anisotropic permanent magnet is used, the harmonic component of the magnetic flux density in the air gap is large, the efficiency of the motor remains at a low value, and the noise of the motor is high.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention is directed to a stator in which a winding is wound around a stator core, and a stator which is rotatably rotatably opposed to an inner cylindrical surface of the stator core. An isotropic ring-shaped permanent magnet is arranged on the outer periphery of the rotor core, and conductor bars are arranged in a plurality of slots provided near the outer periphery of the rotor core, and both ends of the conductor bar are short-circuited. A rotor having a starting cage conductor formed by short-circuiting with a ring, wherein the permanent magnet is magnetized in the same pole in a cross section perpendicular to the rotor axis and the center of the pole and the rotor. Since the magnetic flux density in the radial direction on the surface of the rotor is distributed as a sine wave by having two rotor magnetic poles that are all parallel to the line connecting the centers of the Becomes As a result, since there is no harmonic component in the magnetic flux density distribution in the air gap and iron loss can be reduced, there is an effect that a highly efficient, low-noise, 2-pole self-starting permanent magnet type synchronous motor can be obtained.

According to a second aspect of the present invention, there is provided an electric motor comprising a stator having a winding wound around a stator core, and a rotor rotatably rotatably opposed to an inner cylindrical surface of the stator core. A conductor bar is provided in a plurality of slots provided near the outer periphery of a rotor core, and both ends of the conductor bar are short-circuited by short-circuit rings to form a starting cage conductor, and the rotor A two-pole self-starting method comprising: applying a parallel magnetic field in a direction perpendicular to an axis of the rotor to a rotor having a ring-shaped isotropic permanent magnet mounted on an outer periphery of an iron core to magnetize the rotor. The method of manufacturing a permanent magnet type synchronous motor employs a method of manufacturing a permanent magnet. Therefore, the permanent magnet can be magnetized freely in any direction by applying a magnetic field. No need to assemble while aligning the position with the magnetic pole of the permanent magnet It has the effect of assembly work becomes easy.

According to a third aspect of the present invention, there is provided an electric motor comprising a stator having a winding wound around a stator core, and a rotor rotatably rotatably opposed to the inner cylindrical surface of the stator core. Wherein a conductor bar is provided in a plurality of slots provided near the outer periphery of the rotor core, and both ends of the conductor bar are short-circuited with a short-circuit ring to form a starting cage conductor. A two-pole self-starting permanent magnet synchronous motor, comprising: a rotor having an isotropic ring-shaped permanent magnet magnetized by applying a parallel magnetic field in a radial direction to an outer periphery thereof. Since the manufacturing method is adopted, the magnetizing can be performed only with the permanent magnet, so that the productivity of the magnetizing step can be improved.

Further, since the permanent magnet is made of a rare earth magnet, a strong magnetic force can be obtained, so that the rotor and the motor as a whole can be reduced in size and weight.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a self-starting permanent magnet synchronous motor according to the present invention will be described below with reference to the drawings. The same components as those in the related art are denoted by the same reference numerals, and the detailed description is omitted. Since the stator has the same configuration as a general self-starting permanent magnet type synchronous motor, description of the stator is omitted.

(Embodiment 1) A description will be given with reference to FIG. FIG.
1 is a longitudinal sectional view of a rotor of a self-starting permanent magnet type synchronous motor according to Embodiment 1 of the present invention. In FIG. 1, 1 is a rotor, and 2 is a rotor core. An isotropic ring-shaped permanent magnet 6 is arranged on the outer periphery of the rotor core 2. Slots 3 for disposing a plurality of conductor bars 4 are provided in the vicinity of the outer periphery of the rotor core 2, and short-circuit rings (not shown) at both ends of the conductor bars 4 and the rotor core in the axial direction are formed by aluminum die casting.
Are integrally molded to form a starting cage conductor.

Here, in FIG. 1, by magnetizing with the parallel magnetic field H, the magnetization direction 8 of the isotropic ring-shaped permanent magnet 6 is a line AA 'connecting the center of the axis 9 and the center 10 of the pole. To form two rotor magnetic poles parallel to. Since the magnet is magnetized so that the magnitude of the magnetic flux in the magnetization direction 8 of the permanent magnet 6 is constant, the distribution of the magnetic flux density in the radial direction on the surface of the rotor is a sine wave, so that the magnetic flux density distribution in the air gap is provided. Is a sine wave as shown in FIG. As a result, there is no harmonic component in the magnetic flux density distribution in the air gap, so that iron loss can be reduced, high efficiency can be obtained, and noise of the motor can be reduced.

(Embodiment 2) In the method of manufacturing a rotor of a two-pole self-starting type permanent magnet synchronous motor described in Embodiment 1 above, a starting cage conductor is formed on a rotor core 2 by aluminum die casting. A method of forming a two-pole rotor magnetic pole by applying a parallel magnetic field in a direction perpendicular to the axis to a rotor 1 having an isotropic ring-shaped permanent magnet mounted on the outer periphery of the rotor. Can be formed freely by applying a magnetic field in any direction, so assemble while aligning the radial position of the rotor core with the magnetic pole of the permanent magnet. There is no necessity, and the assembling work can be easily performed.

First, the isotropic ring-shaped permanent magnet is
It is also conceivable to use a method in which the magnet is magnetized to two poles by applying a parallel magnetic field in the radial direction, and then mounted on the outer periphery of the rotor core formed with a starting cage conductor by aluminum die casting. As a result, the productivity of the magnetization step can be increased.

Which of the two is to be selected may be determined from a comprehensive aspect such as equipment and method of construction.

(Embodiment 3) Although not shown, if the permanent magnet is formed of a rare earth magnet, a strong magnetic force can be obtained, so that the rotor and the motor can be reduced in size and weight.

[0026]

As described above, according to the first aspect of the present invention, the stator in which the winding is wound around the stator core, and the stator core is rotatably rotated facing the inner cylindrical surface of the stator core. Then, place an isotropic ring-shaped permanent magnet around the rotor core,
An electric motor comprising a rotor having a starting cage-shaped conductor formed by disposing conductor bars in a plurality of slots provided near the outer periphery in a rotor core and short-circuiting both ends of the conductor bar with a short-circuit ring; Wherein the permanent magnet has two rotor magnetic poles whose magnetization directions within the same pole are all parallel to a line connecting the center of the pole and the center of the rotor axis in a cross section perpendicular to the rotor axis. Accordingly, the magnetic flux density distribution in the gap becomes a sine wave. This eliminates the harmonic components of the magnetic flux density distribution in the air gap, thereby reducing iron loss, achieving high efficiency and realizing a low-noise, 2-pole self-starting permanent magnet synchronous motor. it can.

According to the second aspect of the present invention, the permanent magnet is mounted on the rotor core and then magnetized. Therefore, the radial position of the rotor core is set to the magnetic pole of the permanent magnet. It is not necessary to assemble while adjusting the positions of the components, and the assembling work can be easily performed.

According to the third aspect of the present invention, a method is provided in which a permanent magnet previously magnetized is mounted on a rotor iron core. Since only the permanent magnet is magnetized, the production of the magnetizing step is performed. Can be enhanced.

According to the fourth aspect of the present invention, since the permanent magnet is formed of a rare earth magnet, a strong magnetic force can be obtained, so that the size of the rotor and the entire motor can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a rotor according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a rotor of a conventional self-starting permanent magnet synchronous motor.

FIG. 3 is a diagram showing a magnetic flux density distribution in a gap portion according to a conventional example.

FIG. 4 is a view showing a magnetic flux on a surface of a rotor.

FIG. 5 is a diagram showing a magnetic flux density distribution in a gap portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotor core 3 Slot 4 Conductor bar 6 Permanent magnet 9 Axis 10 Center of pole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H621 AA01 AA03 GA01 GA04 HH01 HH03 HH10 JK02 5H622 AA01 CA01 CA02 CA05 CA12 DD02 PP03 PP10 PP11 PP20 QA04 QB04

Claims (4)

[Claims] A stator having a winding wound around a stator core;
The stator core is rotatably rotated in opposition to the inner cylindrical surface of the stator core, an isotropic ring-shaped permanent magnet is arranged on the outer periphery of the rotor core, and a plurality of magnets are provided near the outer periphery in the rotor core. A rotor having a starting cage conductor formed by arranging a conductor bar in a slot and short-circuiting both ends of the conductor bar with a short-circuit ring, wherein the permanent magnet is magnetized in the same pole. A self-starting permanent magnet synchronous motor having two rotor magnetic poles, all of which are parallel to a line connecting the center of the pole and the center of the rotor axis in a cross section perpendicular to the rotor axis; . 2. A stator having windings wound around a stator core,
A rotor rotatably rotatably opposed to the inner diameter cylindrical surface of the stator core, wherein a conductor bar is disposed in a plurality of slots provided near the outer periphery of the rotor core,
The rotor is formed by short-circuiting both ends of the conductor bar with a short-circuit ring to form a starting cage conductor, and a rotor having an isotropic ring-shaped permanent magnet mounted on the outer periphery of the rotor core. And magnetizing by applying a parallel magnetic field in a direction perpendicular to the axis of the permanent magnet type. 3. A stator having windings wound around a stator core,
A rotor rotatably rotatably opposed to the inner diameter cylindrical surface of the stator core, wherein a conductor bar is disposed in a plurality of slots provided near the outer periphery of the rotor core,
An isotropic ring-shaped permanent magnet, magnetized by applying a parallel magnetic field in the radial direction, is mounted on the outer periphery of the rotor core, in which both ends of the conductor bar are short-circuited with a short-circuit ring to form a starting cage conductor. A method for manufacturing a two-pole self-starting permanent magnet type synchronous motor, comprising: 4. The two-pole self-starting permanent magnet synchronous motor according to claim 1, wherein the permanent magnet is made of a rare earth magnet.