JP2003284273A - Surface-bonded permanent magnet synchronous dynamo- electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-bonded permanent magnet synchronous dynamo-electric motor that can utilize reluctance torque. <P>SOLUTION: The surface-bonded permanent magnet synchronous dynamo-electric motor is provided on the surface of the rotor 20 with at least one pair consisting of an N pole and an S pole of a first permanent magnet 21 at angled intervals relative to the center of the rotor. At least one slit 22 is formed between the center of the rotor and each first permanent magnet 21 extending in the direction of the axis and intersecting in the radial direction; a second permanent magnet 23 is inserted in the slit 22. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor,
In particular, it relates to a surface-attached permanent magnet synchronous motor configured to have salient pole characteristics.

[0002]

2. Description of the Related Art The structure of a general synchronous motor will be briefly described with reference to FIG. In FIG. 7, the synchronous motor comprises a cylindrical stator 70 and a rotor 80. The stator 70 is provided with a large number of slots 71 on the inner peripheral side,
A stator winding is accommodated in each slot 71.
On the other hand, in the rotor 80, one or more pairs of permanent magnets 81 are arranged on the surface side at angular intervals with respect to the center of the rotor. Here, two pairs of pairs of N poles and S poles, that is, a four pole synchronous motor in which four permanent magnets 81 are arranged are shown. This kind of synchronous motor is SPM
Also called a motor.

In such a synchronous motor, the stator 7
The magnetic path from 0 to a certain permanent magnet 81 in the rotor 80, the rotor 80, and the adjacent permanent magnets 81 to the stator 70 can be called a d-axis magnetic path. On the other hand, there is no magnetic path from the stator 70 to the stator 70 by passing between the adjacent permanent magnets 81 in the rotor 80, passing through the rotor 80, and further passing between the adjacent permanent magnets 81. It can be called an axial magnetic path. And
The current flowing through the stator winding to generate the magnetic flux for the q-axis magnetic path is called the q-axis current, and the current flowing through the stator winding to generate the magnetic flux for the d-axis magnetic path is the d-axis current. Called.

By the way, the above synchronous motor cannot utilize reluctance torque because it does not have salient poles. The principle of reluctance torque generation will be described below.

The voltage equation in the steady state on the d-axis and q-axis coordinates in the synchronous motor is expressed by the following equation 1.

[0006]

[Equation 1]

However, v _d and v _q represent voltages on the d-axis and the q-axis, respectively, R _a is the armature resistance for one phase, ω is the rotational angular velocity, and L _d and L _q are the d-axis and the q-axis, respectively. , I _d , i _q are d-axis and q-axis currents, respectively, and ψ _a is the armature flux linkage by the permanent magnet.

Further, the equation of the torque T is expressed by the following equation: T = Z _p [ψ _a i _q + (L _d −L _q ) i _d i _q ]. However, Z _p is the number of pole pairs.

Here, a lead angle β of the armature current I _{a from} the q axis is introduced. That is, when i _q = I _a cosβ i _d = −I _a sin β, the torque T can be expressed by the following torque equation.

T = Z _p [ψ _a I _a cos β + (1/2)
_{(L q -L d) I a} 2 sin2β] Here, the first term of the torque equation is a magnet torque by the permanent magnets, the second term represents the reluctance torque caused by the difference between the d-axis inductance, q-axis inductance . That is, it means that a positive torque is generated by passing a negative d-axis current. The negative d-axis current is obtained by advancing the current phase angle.

[0011]

[Problems to be Solved by the Invention]
In such a synchronous motor, the rotor shape does not have saliency
Therefore, the difference between the d-axis inductance and the q-axis inductance is
None (that is, L_d= L _q), The second term reluctance
I couldn't use Luk.

On the other hand, when the synchronous motor is driven, a sensor for detecting the magnetic pole position is required. When the rotor shape has a salient pole, sensorless control using this salient pole is possible. Since the magnetic pole position estimation method using such salient poles is well known, its description is omitted here.

Therefore, a main object of the present invention is to provide a surface-attached permanent magnet synchronous motor which can utilize reluctance torque.

[0014]

SUMMARY OF THE INVENTION According to the present invention, the surface of the rotor is spaced N angularly with respect to the center of the rotor.
A surface-bonded permanent magnet synchronous motor comprising a pair of first permanent magnets having a pair of poles and S poles.
One or more slits are formed between the permanent magnet and the center of the rotor so as to extend in the axial direction and intersect in the radial direction, and the second permanent magnet is inserted and arranged in the slit. A surface-attached permanent magnet synchronous motor is provided.

In the surface-attached permanent magnet synchronous motor of the present invention, the shape of the slit also extends in the axial direction and in the radial direction from the both ends of the linear portion intersecting the radial direction toward the rotor surface. It may be composed of parts.

In the surface-attached permanent magnet synchronous motor of the present invention, the slit may have a V-shape that is convex toward the center of the rotor.

In the present surface-bonded permanent magnet synchronous motor, in addition to the V-shaped slit, a linear slit extending axially and intersecting the radial direction is formed near the rotor surface side. A permanent magnet may be inserted and arranged in the linear slit.

In the surface-attached permanent magnet synchronous motor of the present invention, the slit may have an arcuate shape that is convex toward the center of the rotor.

In the surface-attached permanent magnet synchronous motor of the present invention, in addition to the arcuate slit, a linear slit extending axially and intersecting the radial direction is formed near the rotor surface side. A permanent magnet may also be inserted and arranged in the linear slit.

In this surface-attached permanent magnet synchronous motor, the magnetic poles of the second permanent magnets are oriented in the same direction as the magnetic poles of the corresponding first permanent magnets.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is applied to a surface-bonded permanent magnet synchronous motor, in which a permanent magnet is arranged on the surface of a rotor, a so-called SPM motor.

A synchronous motor according to a first embodiment of the present invention will be described with reference to FIG. The synchronous motor according to the present embodiment includes a cylindrical stator 10 and a rotor 20, and the surface of the rotor 20 has a pair of N poles and S poles with a pair of N poles and S poles at angular intervals with respect to the center of the rotor. A first permanent magnet 21 is provided. Here, a 6-pole synchronous motor including three pairs of first permanent magnets 21 at an angular interval of 60 degrees is shown.

In the present embodiment, in particular, one linear slit 22 extending in the axial direction and intersecting at a right angle in the radial direction is provided in each of the rotor cores between the first permanent magnets 21 and the center of the rotor. Is formed, and the second permanent magnet 23 is inserted and arranged in the slit 22. The magnetic poles of the second permanent magnets 23 are oriented so as not to interfere with the magnetic flux, that is, the same direction as the magnetic poles of the corresponding first permanent magnets 21. That is, if the first permanent magnet 21 has the N pole toward the center of the rotor, the corresponding second permanent magnet 23 also has the N pole toward the center of the rotor.
The first permanent magnet 21 adjacent to the first permanent magnet 21 has the S pole toward the center of the rotor, and therefore the second permanent magnet 21 corresponding thereto is
The permanent magnet 23 also has an S pole toward the center of the rotor.

According to such a structure, from the stator 10, the first permanent magnet 21 and the second permanent magnet 23 of the rotor 20 are passed, the rotor 20 is passed through, and the second permanent magnet adjacent thereto is further passed. A d-axis magnetic path is formed so as to reach the stator 10 through the magnet 23 and the first permanent magnet 21. on the other hand,
Another permanent magnet 2 that passes between the adjacent first permanent magnets 21 in the rotor 20 from the stator 10 and passes through the rotor 20 without passing through the second permanent magnets 23, and further adjacent to each other.
A q-axis magnetic path is formed so as to reach the stator 10 through the gaps 1 between them. Since the structure of the stator 10 may be the same as that of the conventional surface-attached permanent magnet synchronous motor, the description thereof will be omitted.

With such a structure, the magnetic resistance of the q-axis magnetic path is the same as that before the second permanent magnet 23 is inserted and arranged. On the other hand, the magnetic resistance of the d-axis magnetic path is large because the magnetic permeability has an area having a smaller magnetic permeability than that of the iron core. Therefore, the magnetic resistances of the d-axis magnetic path and the q-axis magnetic path are different from each other, and the d-axis inductance L _d and the q-axis inductance L _q are different from each other. . The second permanent magnet 23 may have a multi-layer structure in which the slits 22 are formed in multiple layers in the radial direction so as to have layers in the radial direction.

In any case, according to the rotor structure as in this embodiment, the reluctance torque can be utilized in addition to the magnet torque which is the torque of the permanent magnet alone. Further, by having the saliency, the magnetic pole detection sensor required for the sensorless control becomes unnecessary, and the maintainability can be improved and the cost can be reduced. Further, by the field weakening control by the optimal advance control of the current vector, the operating range can be expanded even if the current / voltage of the drive circuit or the main body is limited.

The expansion of the operating region by the field weakening will be described below with reference to FIGS. 8 and 9.

The voltage equation in the steady state of the PM motor represented on the d-axis-q axis coordinates rotating at the electrical angular velocity ω is given by the above-mentioned equation 1.

From Equation 1, the basic vector diagram of the PM motor is as shown in FIG.

Since the characteristics of the PM motor in the high speed region are examined, it is considered that the influence of the voltage drop Vd of the armature resistance R is small. Therefore, this will be ignored in the following calculation formula.

From the equation (1), the d-axis and q-axis voltages can be obtained by the following equation (2).

[0032]

[Equation 2]

Here, since the PM motor characteristic in the high speed region is examined as described above, the voltage drop in the resistor is ignored.

Further, the maximum values of the armature current and the terminal voltage of the PM motor are limited, and their relationship is expressed by the following mathematical formula 3.
Shown in.

[0035]

[Equation 3]

The following equation 4 considers only the voltage limitation.

[0037]

[Equation 4]

Using the solution formula in Equation 4, the following Equation 5 is obtained.

[0039]

[Equation 5]

Here, the maximum torque is output when the armature current I matches the rated current I _{am of the} inverter.

As described above, when the armature current I is input, the maximum torque is always output by causing the maximum torque to be output. Therefore, the maximum torque is output with the minimum current. The control takes into account copper loss.

[0042] Here, the terminal voltage V with increasing speed reaches _{V max} is a limit value of the terminal voltage in are increased speed omega _base. This speed ω _base becomes the maximum speed at which constant torque control is possible, and is given by Equation 4 as in Equation 6 below.

[0043]

[Equation 6]

Further, when the speed ω becomes larger than ω _base , the voltage is saturated and the motor cannot be controlled. Therefore, voltage saturation is eliminated by applying a current to the d-axis in the direction of canceling the magnetic flux. However, even if this weakening magnetic flux control is performed, there is an output limit and the speed is when all of the maximum value I _am of the input current is applied to the d axis. ω _ma
x is given by the following Equation 7.

[0045]

[Equation 7]

FIG. 9 shows the characteristics of the PM motor.

Next, a second embodiment of the present invention will be described with reference to FIG. This form can be said to be a modification of the first embodiment. That is, the shape of the slit formed in the rotor 20 is the linear slit 22 that intersects the radial direction at a right angle, and the linear slit 2
It is formed so as to be composed of extension slits 22-1 extending in the axial direction and in the radial direction from the both ends toward the rotor surface side. Of course, the second permanent magnets 23, 23- are provided in the slit 22 and the extension slit 22-1, respectively.
1 is inserted and arranged. The second permanent magnet 23-1 also has
It also acts to concentrate the magnetic flux on the d-axis magnetic path. Therefore, the orientation of the magnetic poles of the second permanent magnets 23-1 is made substantially the same as the orientation of the magnetic poles of the corresponding second permanent magnets 23. That is,
If the N pole of the second permanent magnet 23 faces the center of the rotor, the magnetic pole of the corresponding second permanent magnet 23-1 is made such that the N pole faces the inside of the rotor.

Of course, also in this embodiment, the second permanent magnets 23 and 23-1 have a multi-layer structure in which a plurality of layers are formed in the radial direction of the slits 22 and 22-1 to give a hierarchy in the radial direction. Is also good.

Operation of the rotor according to the second embodiment,
Since the effect is the same as that of the first embodiment, the description is omitted, and this is the same in the third to sixth embodiments described below. In addition, the third described below
In all of the sixth embodiments, it is assumed that the slit also extends in the axial direction.

A third embodiment of the present invention will be described with reference to FIG. In this embodiment, the shape of the slit is
V-shaped slit 32 convex toward the center of the rotor
And a plurality of layers (here, three layers) are formed in the radial direction. Since each slit 32 is V-shaped, the slit 32 near the center of the rotor is the largest. Of course, the second permanent magnets 33 are inserted and arranged in all the slits 32. Then, adjacent V-shaped slits 32
Is not applied to the q-axis magnetic path. Further, the slit 32 may be formed in one or more layers. Further, the orientation of the magnetic poles of the second permanent magnets 33 is made substantially the same as the orientation of the magnetic poles of the corresponding first permanent magnet 21. That is, if the N pole of the first permanent magnet 21 faces the center of the rotor, the corresponding second pole
The magnetic poles of the permanent magnets 33 are such that the N pole faces the inside of the rotor.

A fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, in addition to the V-shaped plural layers of slits 32 described in FIG. 3, linear slits 35 that intersect the radial direction at right angles are provided toward the rotor surface side.
Is formed, and the second permanent magnet 36 is also inserted and arranged in this linear slit 35. The direction of the magnetic pole of the second permanent magnet 33 inserted and arranged in the slit 32 is the third direction.
In the same manner as in the first embodiment, the orientation of the magnetic pole of the second permanent magnet 36 inserted into the slit 35 is also the same as the orientation of the corresponding first permanent magnet 21. That is, if the first permanent magnet 21 has the N pole toward the center of the rotor,
The corresponding second permanent magnet 36 also has an N pole toward the center of the rotor. Also in this embodiment, one or more layers of the slit 32 may be formed.

A fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, the shape of the slit is
Slit 42 having an arc shape convex toward the rotor center side
And a plurality of layers (here, three layers) are formed in the radial direction. Since each slit 42 has a circular arc shape, the slit 42 near the center of the rotor has the largest size. Of course, the second permanent magnets 43 are inserted and arranged in all the slits 42. Then, adjacent arc-shaped slits 42
Is not applied to the q-axis magnetic path. Further, the slit 42 may be formed in one or more layers. Further, the orientation of the magnetic poles of the second permanent magnets 43 is made substantially the same as the orientation of the magnetic poles of the corresponding first permanent magnet 21. That is, if the N pole of the first permanent magnet 21 faces the center of the rotor, the corresponding second pole
The magnetic poles of the permanent magnets 43 in the above are arranged such that the N pole faces the inside of the rotor.

A sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, in addition to the arc-shaped plural layers of slits 42 described with reference to FIG. 5, linear slits 45 that intersect the radial direction at right angles are provided toward the rotor surface side.
Is formed so that the second permanent magnet 46 is also inserted and arranged in the linear slit 45. The direction of the magnetic pole of the second permanent magnet 43 inserted and arranged in the slit 42 is the fifth direction.
In the same manner as in the first embodiment, the orientation of the magnetic pole of the second permanent magnet 46 inserted and arranged in the slit 45 is also made the same as the orientation of the corresponding first permanent magnet 21. That is, if the first permanent magnet 21 has the N pole toward the center of the rotor,
The corresponding second permanent magnet 46 also has an N pole toward the center of the rotor. Also in this embodiment, the slit 42 may be formed in one or more layers.

In any of the forms, the second permanent magnets 23, 33, 43, etc. act as an auxiliary to the magnetic force of the first permanent magnet 21, and moreover, as compared with the case of only the slit, the rotor. It also contributes to the improvement of the mechanical strength of 20.

[0055]

As described above, according to the surface-attached permanent magnet synchronous motor of the present invention, the following effects can be obtained.

(1) Reluctance torque can be utilized in addition to magnet torque which is the torque of the permanent magnet alone.

(2) By having the salient pole, the magnetic pole detecting sensor, which was required for the sensorless control, becomes unnecessary, and the maintainability can be improved and the cost can be reduced.

(3) By the field weakening control by the optimum advance control of the current vector, the operating range can be expanded even if the current and voltage of the drive circuit and the main body are limited.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view of a surface-bonded permanent magnet synchronous motor according to a first embodiment of the present invention.

FIG. 2 is a half cross-sectional view of a surface-bonded permanent magnet synchronous motor according to a second embodiment of the present invention.

FIG. 3 is a half cross-sectional view of a surface-bonded permanent magnet synchronous motor according to a third embodiment of the present invention.

FIG. 4 is a half sectional view of a surface-bonded permanent magnet synchronous motor according to a fourth embodiment of the present invention.

FIG. 5 is a half cross-sectional view of a surface-bonded permanent magnet synchronous motor according to a fifth embodiment of the present invention.

FIG. 6 is a half cross-sectional view of a surface-bonded permanent magnet synchronous motor according to a sixth embodiment of the present invention.

FIG. 7 is a half sectional view for explaining the structure of a conventional general synchronous motor.

FIG. 8 is a basic vector diagram of a synchronous motor.

FIG. 9 is a characteristic diagram for explaining expansion of an operating region due to field weakening in a synchronous motor.

[Explanation of symbols]

10, 70 Stator 20, 80 Rotor 21 First permanent magnet 22, 22-1, 32, 35, 42, 45 Slit 23, 23-1, 33, 36, 43, 46 Second permanent magnet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02K 19/10 H02K 19/10 A 21/14 21/14 MF term (reference) 5H002 AA09 AB07 AC04 AC06 AE08 5H619 AA01 BB01 BB06 BB24 PP02 PP06 PP08 5H621 HH01 HH08 HH09 JK02 JK05 PP10 5H622 AA03 CA02 CA03 CA05 CB02 CB03 CB04 CB05 CB06 PP11 PP19

Claims (7)

[Claims] 1. A first and a plurality of pairs of a north pole and a south pole formed on the surface of the rotor at angular intervals with respect to the center of the rotor.
In the surface-attached permanent magnet synchronous motor provided with the permanent magnet of, each of the first permanent magnets and the rotor center,
A surface-bonded permanent magnet synchronous motor, comprising one or more slits formed so as to extend in the axial direction and intersect in the radial direction, and a second permanent magnet is inserted and arranged in the slits. 2. The surface-attached permanent magnet synchronous motor according to claim 1, wherein the slit has a shape in which a straight line portion intersecting the radial direction and both ends of the straight line portion are directed in the axial direction and toward the rotor surface side, respectively. And a surface-attached permanent magnet synchronous motor. 3. The surface-attached permanent magnet synchronous motor according to claim 1, wherein the shape of the slit is a V-shape that is convex toward the center of the rotor. . 4. The surface-attached permanent magnet synchronous motor according to claim 3, wherein, in addition to the V-shaped slit, a linear shape extending in the axial direction and intersecting the radial direction is provided closer to the rotor surface side. A surface-attached permanent magnet synchronous motor, characterized in that a slit is formed and a permanent magnet is inserted and arranged in the linear slit. 5. The surface-attached permanent magnet synchronous motor according to claim 1, wherein the slit has a shape of an arc that is convex toward the center of the rotor. 6. The surface-attached permanent magnet synchronous motor according to claim 5, wherein, in addition to the arc-shaped slit, a linear slit that extends axially and intersects the radial direction is provided closer to the rotor surface side. And a permanent magnet is inserted and arranged in the linear slit. 7. The surface-attached permanent magnet synchronous motor according to claim 1, wherein the magnetic poles of the second permanent magnets are oriented in the same direction as the magnetic poles of the corresponding first permanent magnets. A surface-attached permanent magnet synchronous motor characterized by being applied.