JP2000209798A - Permanent magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a permanent magnet motor in which high torque and high efficiency are realized by utilizing reluctance torque furthermore. SOLUTION: In a permanent magnet motor having a rotor 10 on the inside of a stator generating a rotating field, planar magnets 11 are embedded in the rotor 10 along the q-axis and the magnets 11, corresponding in number to that of poles, are embedded in the rotor 10 along the outer circumference thereof at a constant interval. The magnets 11 are magnetized in the direction perpendicular to the q-axis and slits 12 are made at the d-axis parts forming the poles in order to ensure flux at least from one q-axis to the other q-axis. Since the slits 12 extend vertically and reaches the flux from one d-axis to the other q-axis, inductance ratio between d-axis and q-axis is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet motor for a motor used in an air conditioner, an automobile and the like, and more particularly to a permanent magnet motor capable of effectively utilizing reluctance torque.

[0002]

2. Description of the Related Art As shown in FIG. 10, for example, a permanent magnet motor has a rotor 2 in a stator 1 of, for example, 24 slots for generating a rotating magnetic field. Permanent magnets 3 for the number of poles (for example, four poles) of the motor are arranged in the circumferential direction along the outer diameter. Reference numeral 4 denotes a center hole for the shaft.

In the structure of the rotor 2, the permanent magnet 3 has a plate shape along the q axis, and a path for magnetic flux (magnetic flux from the stator 1) from one q axis to the other q axis is secured. And
Further, a permanent magnet 3 is vertically interposed in the path of the magnetic flux (magnetic flux from the stator 1) from one d-axis to the other d-axis. With such a structure, a d-axis / q-axis inductance ratio (a so-called salient pole ratio) can be obtained, and generation of reluctance torque is observed. Therefore, not only magnet torque but also reluctance torque can be expected. The permanent magnet motor provided with the rotor 2 is a three-phase four-pole motor.
Japanese Patent Publication No. 0-66285 describes a six-pole motor, which should be referred to as the above-mentioned conventional example.

[0004]

However, in the above-described permanent magnet motor, the d-axis and q-axis inductance ratios (so-called salient pole ratios) are extremely small, and the reluctance torque hardly contributes to the motor torque. Contributes to the motor torque.If high magnets are used for high torque and high efficiency, a large magnet or a magnet with strong magnetic force will increase the cost, and considering the cost etc., the amount of magnet used will be limited. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a permanent magnet motor capable of increasing reluctance torque and achieving high torque and high efficiency.

[0006]

In order to achieve the above object, the present invention provides a permanent magnet motor having a rotor inside a stator for generating a rotating magnetic field. The magnets are embedded along the axis, and the magnets are embedded at equal intervals along the outer circumference of the rotor by the number of poles, and the magnetization of the magnet is in a direction perpendicular to the q-axis, and the adjacent magnets have the same polarity. A slit is formed in the d-axis portion forming the pole, and a magnetic path (path of magnetic flux) from at least one q-axis to the other q-axis.
And the slits are used to increase the d-axis and q-axis inductance ratios.

The slit of the rotor has a multilayer structure in the d-axis direction, and the slit has an arc-shaped cross-section, a bathtub-shaped cross-section, or a V-shaped cross-section. The apex angles of the shapes may be formed at regular intervals toward the center hole.

[0008] It is preferable that a flux barrier is formed at the end of the magnet of the rotor on the side of the center hole, and the flux barrier extends over the end of the adjacent magnet on the side of the center hole. It is preferable that the flux barrier of the rotor is divided into two at an intermediate portion to form a pair of flux barriers.

[0009] Between the slit of the rotor and the center hole or between the slit and the flux barrier, d
It is preferable that a rivet for caulking the core is passed through the shaft, and the rivet is made of a magnetic material. A rivet for caulking the core may be passed on the d-axis between the slit of the rotor and the outer periphery of the core or between the slit and the flux barrier, and the rivet may be made of a magnetic material.

The rotor is a core formed by punching out an electromagnetic steel sheet by an automatic press and automatically laminating in a mold.
When burying holes of the magnet, holes of slits, holes of rivets, and holes of flux barrier are punched out during the automatic pressing, and the distance between these holes and between these holes and the outer periphery of the core is at least larger than the thickness of the core sheet. Good.

The magnet embedded in the rotor is preferably a ferrite magnet or a rare earth magnet. Further, the rotor is suitable as a rotor of a DC brushless motor.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described in detail with reference to FIG. In the drawing, the same parts as those in FIG. 10 are denoted by the same reference numerals, and the duplicate description will be omitted.

As shown in FIGS. 1 to 3, a rotor 10 of this permanent magnet motor has a thin (plate-like) magnet 11 embedded in the q-axis direction by an IPM method and the number of poles corresponding to the number of poles. Embedded at equal intervals along the
While a magnetic path from the front (from one q-axis to the other q-axis) is secured (see the dashed arrow in FIG. 3), a slit 12 for increasing the reluctance torque is formed in this secured area. The magnet 11 is magnetized and magnetized in a direction perpendicular to the q-axis (the thickness direction of the plate-shaped magnet 11), and the adjacent magnets 11 have the same polarity, and the pole of the motor is formed on the d-axis side.

An inverted arc-shaped slit 12 whose apex is directed toward the center hole 4 is formed in the d-axis portion on which the poles of the motor are formed, and this slit 12 extends from one d-axis to the other d-axis. It intervenes almost perpendicularly to the magnetic flux (magnetic flux from the stator 1) and exhibits the function of the flux barrier, while the other q
A sufficient path for the magnetic flux (magnetic flux from the stator 1) from the axis to the other q-axis is secured. Therefore, the inductance ratio of the d-axis and the q-axis is increased (the salient pole ratio is increased), whereby the reluctance torque is increased.

Although the slit 12 has a three-layer structure in the d-axis direction, it is sufficient that at least one slit is provided. Further, in the stator 1, for example, the outer-side winding is a U-phase, the inner-side winding is a W-phase, and an intermediate winding is a V-phase.
Further, although the three-phase (U-phase, V-phase and W-phase) armature windings are applied to the 24-slot stator 1, the number of slots and the armature windings may be different.

By the way, the magnet 11 embedded along the q-axis generates a pole (N pole or S pole) on the d-axis side, and the poles are alternately generated in the circumferential direction. Occurs. Also, rotor 1
The interval between the outer peripheral edge of 0 and the end of the magnet 11 is a value larger than the thickness t (for example, t to 3t), where t is the thickness of a core sheet 10a described later. Thereby, the leakage and short circuit of the magnetic flux of the magnet 11 can be prevented, that is, it contributes to the improvement of the magnet torque, and moreover, the core can be accurately manufactured without generating burrs and the like when the core is manufactured by an automatic press described later. Can be.

The cost of the motor depends on the size of the magnet 11. Therefore, by reducing the amount of the magnet 11 used, the cost can be reduced, while the width of the magnetic path from one q-axis to the other q-axis is increased. The inductance ratio can be increased. Thus, the magnet 1
1 makes it possible to compensate for the decrease in magnet torque due to the decrease in the amount of use by reluctance torque. As the magnet 11, a ferrite magnet or a rare earth magnet is used. In this case, the ferrite magnet is effective in reducing the cost, and the rare earth magnet is effective in increasing the torque.

Further, in the manufacture of the rotor 10, a core laminating method (automatic laminating method) in which an electromagnetic steel sheet is punched out by an automatic press using a core press die and integrally formed in the die is adopted. As shown in FIGS. 2 and 3,
In this press working step, the core of the rotor 10 is punched out.
The core sheet 10a in which the hole for burying the magnet 11 and the hole of the slit 12 are punched is laminated.

Then, the magnet 11 is buried by the IPM method into the hole of the core of the rotor 10 obtained by automatically pressing and laminating. As described above, the magnet 11 is magnetized and magnetized in a direction perpendicular to the q axis, and
Are of the same polarity.

As described above, the reluctance torque can be increased by forming the slits 12, the total torque can be improved by the magnet torque and the reluctance torque, and a high torque and high efficiency motor can be realized. An appropriate motor can be realized by selecting the amount (size) of the magnet to be used in consideration of cost and torque.

FIG. 4 is a schematic plan view of a rotor for explaining another embodiment of the present invention. In the figure, the same parts as those in FIG. See FIG. 1 for the stator 1. In this example,
Short-circuit of magnetic flux at the end of the magnet 11 on the side of the center hole 4
In order to prevent leakage, a flux barrier 21 is formed at the end of the magnet 11 on the side of the center hole 4.

The rotor 20 shown in FIG.
From the end (the end on the side of the center hole 4) of the magnet 11
Has a flux barrier 21 formed by a pair of elongated holes 21a and 21b extending in the direction of. In addition,
The distance between the magnet 11 and the elongated hole 21a, the distance between the magnet 11 and the elongated hole 21b, the distance between the elongated hole 21a and the elongated hole 21b, the distance between the center hole 4 and the elongated hole 21a, and the distance between the center hole 4 and the elongated hole 21b. The interval is larger than the thickness t of the core sheet 10a. Accordingly, short-circuit and leakage of the magnetic flux of the magnet 11 can be prevented, and magnet torque can be effectively generated. On the other hand, generation of burrs and the like during core manufacturing can be prevented, and the gap between the holes 21a and 21b can be prevented. Becomes a bridging portion, and the core strength can be increased.

FIGS. 5 and 6 are schematic plan views of a rotor for explaining a modified embodiment of the present invention. In FIG. 4, FIG.
The same reference numerals are given to the same parts and corresponding parts, and the repeated description will be omitted. FIG. 1 is referred to for the stator 1. In the rotor 20 shown in FIG. 5, a rivet 22 for caulking the core is passed between the slit 12 and the center hole 4 on the d axis, that is, in the middle of the adjacent magnet 11.

In this case, the distance between the center hole 4 and the rivet 22 and the distance between the rivet 22 and the end of the magnet 11 are made larger than the thickness t of the core sheet 10a. Thus, in the manufacture of the rotor 20, the occurrence of burrs and the like during press working can be prevented, and the yield can be improved.
As a material of the rivet 22, a magnetic material having good magnetic permeability is used. Thereby, the influence on the magnetic flux from one q-axis to the other q-axis can be reduced, and the d-axis / q-axis inductance ratio can be increased.

In the rotor 20 shown in FIG. 6, the rivet 23 is passed on the d-axis between the outermost slit 12 and the outer periphery of the core. In this case, the distance between the outermost slit 12 and the rivet 23 and the outer circumference of the rotor 20 and the rivet 2
The distance from the core sheet 10a is set larger than the thickness t of the core sheet 10a for the same reason as described above. The holes through which the rivets 22 and 23 shown in FIGS. 5 and 6 pass are formed at the time of the above-described press working. That is, when the center hole 4, the hole of the magnet 11, the slit 12, and the hole of the flux barrier 21 are punched, the through holes of the rivet 22 or the rivet 23 can be punched at the same time.

FIG. 7 is a schematic plan view of a rotor having a flux barrier different from the embodiment shown in FIGS. In the drawings, the same parts as those in FIGS. 4 to 6 and corresponding parts are denoted by the same reference numerals, and redundant description will be omitted.
This rotor 20 is provided with an elongated hole 21 shown in FIGS. 4 to 6 for preventing the leakage and short circuit of the magnetic flux of the magnet 11.
Instead of the flux barriers 21 a and 21 b, one flux barrier 24 is formed between the ends of the magnet 11 on the side of the center hole 4.

The above-mentioned flux barriers 21 and
2 is a linearly elongated hole, but may be a curved hole,
For example, the shape of the flux barriers 21 and 22 is one inverted arc-shaped slit, the center hole 4 side of the slit is an arc curve along the center hole 4, and the core outer peripheral side of the slit is an inverted arc curve. . As a result, leakage of magnetic flux,
Not only short-circuit prevention, but also a magnetic flux path from one q-axis to the other q-axis can be secured.

FIGS. 8 and 9 are schematic plan views of a rotor showing still another modification of the present invention. In the drawing, the same parts as those in FIG. 3 and the parts regarded as the same are denoted by the same reference numerals, and redundant description will be omitted. Rotor 10 shown in FIG.
Is provided with a slit 25 having a bathtub-shaped cross section instead of the slit 12 shown in FIG. The cross-section bathtub shape of the slit 25 refers to a shape along both sides and an upper side of the trapezoid except for the bottom side.

In this case, the bottom of the bathtub is formed in a plurality of layers with the bottom side facing the center hole 4. Thereby, the magnetic flux from the stator 1 (magnetic flux from one q-axis to the other q-axis)
And the d-axis and q-axis inductance ratios can be increased as described above.

The rotor 10 shown in FIG. 9 has a V-shaped slit 26 instead of the slit 12 shown in FIG. In this case, the opening angle of the V-shape is an obtuse angle, and the apex angle is formed in a plurality of layers toward the center hole 4. As a result, a path for the magnetic flux from the stator 1 (magnetic flux from one q-axis to the other q-axis) can be secured, and the d-axis and the
The q-axis inductance ratio can be increased.

Although not shown in FIGS. 8 and 9, a flux barrier 21 shown in FIG. 4 or a flux barrier 24 shown in FIG. Good. The rivet for caulking the core is located at the same position as the rivet 22 shown in FIG.
Or the slit 25, or at the same position as the rivet 23 shown in FIG. 6, that is, between the core outer periphery and the slit 25 on the d-axis.

Further, if the rotors 10 and 20 described above are incorporated in a DC brushless motor, if they are used as, for example, a compressor motor of an air conditioner, the operating efficiency of the air conditioner can be increased without increasing the cost. Can be achieved.

[0033]

According to the present invention described above, the following effects can be obtained. Since the present invention forms a slit for increasing the reluctance torque in the rotor, it is possible to realize sufficient utilization of the reluctance torque.
There is an effect that a high-efficiency motor can be realized, and there is an effect that an applicable motor can be realized by selecting the usage amount (size) of the magnet in consideration of cost and torque.

In the present invention, since the rotor has a multi-layered slit structure for increasing the reluctance torque in the d-axis direction, a magnetic flux path from one q-axis to the other q-axis is secured, while one d-axis is secured. The effect of the flux barrier is effectively exerted on the magnetic flux from the shaft to the other d-axis, so that the reluctance torque can be further increased, and as a result, a high torque and high efficiency motor can be obtained.

According to the present invention, a flux barrier is formed at the end of the magnet embedded in the rotor on the side of the center hole, and the flux barrier extends over the end of the magnet adjacent to the center hole. There is an effect that short circuit and leakage of magnetic flux can be prevented and magnet torque can be generated effectively.

According to the present invention, the flux barrier formed on the rotor is divided into two at the intermediate portion to form a pair of flux barriers. There is an effect that it can be increased.

According to the present invention, a rivet for caulking the core is passed on the d-axis, and the rivet is made of a magnetic material, so that the strength of the rotor is improved, and the magnetic flux from one q-axis to the other q-axis is reduced. It is possible to eliminate the influence, that is, without reducing the d-axis / q-axis inductance ratio.

According to the present invention, when a rotor is obtained by punching out an electromagnetic steel sheet by an automatic press and automatically laminating the rotor in a mold,
Since the buried hole of the magnet, the hole of the slit, the hole of the rivet and the hole of the flux barrier were punched out, and the distance between these holes and between these holes and the outer periphery of the core was made at least larger than the thickness of the core sheet. Pressing technology can be used, that is, it can be realized without increasing the manufacturing cost, and it is possible to prevent the occurrence of burrs and the like at the time of manufacturing the core, increase the yield of core manufacturing, and thereby reduce the manufacturing cost. This has the effect.

According to the present invention, since the magnet embedded in the rotor is a farite magnet or a rare earth magnet, a farite magnet or a rare earth magnet is selected in consideration of the motor cost and torque to realize a motor with an adaptive torque and cost. There is an effect that can be.

According to the present invention, if the rotor is incorporated into a DC brushless motor and is used, for example, as a compressor motor of an air conditioner, the operating efficiency of the air conditioner can be increased without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a permanent magnet motor showing one embodiment of the present invention.

FIG. 2 is a schematic sectional side view of a rotor for explaining the permanent magnet electric motor shown in FIG. 1;

FIG. 3 is a schematic plan view of a rotor for explaining the permanent magnet electric motor shown in FIG. 1;

FIG. 4 is a schematic plan view for explaining another embodiment of the rotor shown in FIG. 3;

FIG. 5 is a schematic plan view for explaining another embodiment of the rotor shown in FIG. 4;

FIG. 6 is a schematic plan view for explaining a modification of the rotor shown in FIG. 5;

FIG. 7 is a schematic plan view for explaining a modified example of the rotor shown in FIG. 4;

FIG. 8 is a schematic plan view of a rotor showing another modified embodiment of the present invention.

FIG. 9 is a schematic plan view of a rotor showing another embodiment of the present invention.

FIG. 10 is a schematic plan view of a conventional permanent magnet motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 4 Center hole (for shaft) 10, 20 Rotor 10a Core sheet 11 Magnet (plate-shaped permanent magnet) 12 Slit (arc shape) 21, 24 Flux barrier 21a, 21b Hole (flux barrier) 22, 23 Rivet 25 Slit (bath shape in cross section) 26 Slit (V shape) t Thickness of core sheet

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (9)

[Claims] 1. A permanent magnet motor having a rotor inside a stator that generates a rotating magnetic field, wherein a plate-shaped magnet is embedded in the rotor along the q axis, and the magnet is attached to the outer periphery of the rotor. Along with the number of the poles at equal intervals, the magnetization of the magnet is in a direction perpendicular to the q-axis, and the adjacent magnets have the same polarity, and a slit is formed in the d-axis portion forming the pole. And a magnetic path (path of magnetic flux) from at least one q-axis to the other q-axis is secured.
A permanent magnet motor characterized by having a large shaft inductance ratio. 2. A slit of the rotor has a multilayer structure in a d-axis direction, and the slit has an arc-shaped cross section, a bathtub-shaped cross section, or a V-shape, and a vertex of the arc-shaped cross section or a base of a buster-shaped cross section. The permanent magnet motor according to claim 1, wherein the V-shaped apex angles are formed at regular intervals toward the center hole. 3. The rotor according to claim 1, wherein a flux barrier is formed at the end of the magnet of the rotor on the side of the center hole, and the flux barrier extends over the end of the magnet adjacent to the center hole. Permanent magnet motor. 4. The permanent magnet motor according to claim 3, wherein a flux barrier of the rotor is divided into two at an intermediate portion to form a pair of flux barriers. 5. Between the slit of the rotor and the center hole or between the slit and a flux barrier,
4. The permanent magnet motor according to claim 1, wherein a rivet for caulking a core is passed through the d-axis, and the rivet is made of a magnetic material. 6. A rivet for caulking a core on a d-axis between a slit of the rotor and an outer periphery of the core or between the slit and a flux barrier, and the rivet is made of a magnetic material. , 2 or 3. 7. The rotor is a core formed by stamping out an electromagnetic steel sheet by an automatic press and automatically laminating in a mold, and embeds holes of the magnet, holes of slits, holes of rivets, and flux during the automatic pressing. 7. The permanent magnet motor according to claim 1, wherein holes in the barrier are punched out, and a gap between the holes and a gap between the holes and the outer periphery of the core are larger than at least a thickness of the core sheet. 8. The magnet embedded in the rotor is a ferrite magnet or a rare earth magnet.
The permanent magnet motor according to 3, 4, 5, 6 or 7. 9. The permanent magnet motor according to claim 1, wherein said rotor is incorporated in a DC brushless motor.