JPH06339239A - Permanent magnet type motor - Google Patents

Abstract

(57) [Abstract] [Purpose] In a permanent magnet motor, the magnetic flux density in the air gap between the stator and the rotor can be increased as much as possible, and the driving torque can be increased. [Structure] Each of the permanent magnets 28 incorporated in the rotor 24 is formed to have an arc-shaped cross section, and each of the permanent magnets 28 is arranged on the rotor core 26 so that the convex portion 28a side faces inward. Further, the permanent magnet 28 is magnetized so that the magnetic flux B of each part thereof is concentrated at one point.
The distance L from the magnetic center C to the average arc line D of the permanent magnet 28 and the average radius R of the permanent magnet 28 are 1.0
It is configured such that × R ≦ L ≦ 7.5 × R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type motor having a rotor constructed by incorporating a plurality of permanent magnets inside a rotor core.

[0002]

2. Description of the Related Art Recently, as a permanent magnet type motor, a motor having a structure shown in FIG. 6 has been developed as a motor having high torque and high efficiency. This product has the following configuration.

That is, the stator 1 has U-phase stator windings 1U and 2U and V-phase stator windings 1V and 2V in twelve slots 3 formed in an annular stator core 2. ,
In addition, the W-phase stator windings 1W and 2W are inserted and arranged.

On the other hand, as shown in FIG. 7, the rotor 4 has a rotor shaft 6 to which a rotor core 6 is fitted and fixed, and a storage portion 7 formed in the rotor core 6 has a cross section. It is configured by inserting and incorporating four arc-shaped permanent magnets 8 from the axial direction, and the stator core 2 is provided inside the stator 1.
It is rotatably arranged in a state where there is a predetermined gap 9 with the inner peripheral portion. Each of the permanent magnets 8 is arranged so that the convex portion 8a side faces the outside (air gap 9 side), and the four permanent magnets 8 have N poles and S poles alternately in FIGS. 6 and 7. Is magnetized so that

8 and 9 show the magnetic anisotropy (magnetic orientation) of a permanent magnet. Of these, FIG. 8 shows the rotor 4
Shows a well-known radial anisotropy in which the center A of the permanent magnet 8 and the center (magnetic center) of the magnetic flux B of each part of the permanent magnet 8 are the same. FIG. 9 shows a magnetic pole axis in which the magnetic center of the permanent magnet 8 is infinity. The directional anisotropy is shown, and these anisotropies are selected and used according to the application.

On the other hand, FIG. 10 shows a so-called inverter power source used for driving a motor. In FIG. 10, the DC power supply 10 includes a switching main circuit 1
1 is connected. This switching main circuit 11 is
The six transistors 12 and the free wheeling diode 13 are configured by three-phase bridge connection. In the switching main circuit 11, the three-phase arm units 11U and 11
The common connection point of the transistors 12 included in V and 11W is
The output lines U, V, W to the corresponding motors are connected. These output lines U, V, W are connected to the stator windings 1U, 2U of each phase of the stator 1, 1V, 2V, and 1W, 2W.

The control circuit 14 includes a switching main circuit 11
By controlling each transistor 12 of, the stator windings 1U, 2U and 1V, 2V, and 1W, 2W corresponding to the adjacent stator windings for two phases, for example, 180 degrees (electrical angle) It is configured to energize by shifting the phase one by one, that is, energize a known 180 degree (electrical angle). Further, the control circuit 14 receives the position signal of the rotor 4 from the rotor position detector 15 and obtains a motor drive signal according to the rotational position of the rotor 4.

[0008]

By the way, in such a permanent magnet type motor, the magnetic flux of the permanent magnet 8 causes a square or trapezoidal magnetic flux distribution in the gap 9 between the stator 1 and the rotor 4. Is obtained. As is well known, the torque of the motor is generated only while the current is flowing through the stator winding, and is expressed by the following equation (1).

T = m × K × B × I (1) where T: motor torque K: constant related to number of turns of stator winding B: magnetic flux density of air gap I: winding current m: motor Number of phases

Therefore, for example, in the method of energizing 180 degrees (electrical angle), the magnetic flux of one pole of the permanent magnet 8 acts as a torque, so that the magnetic flux in the air gap 9 of one pole affects the performance of the motor. .

However, in the conventional structure described above,
Due to the structure, the magnetic flux in the air gap 9 cannot be increased so much that the driving torque of the motor is relatively low. For this reason, there is a limit to downsizing the motor and improving the driving efficiency, and the equipment that uses the motor becomes large.Therefore, further downsizing of the motor is required, and the driving efficiency is improved from the viewpoint of energy saving. More demanded.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotor including a rotor core with a plurality of permanent magnets incorporated therein. It is an object of the present invention to provide a permanent magnet type motor that can increase the magnetic flux density in the air gap between the child and the drive torque as much as possible, thereby reducing the size and improving the drive efficiency.

[0013]

According to a first aspect of the present invention, there is provided a stator having stator windings of a plurality of phases, and a rotor core having a plurality of permanent magnets incorporated therein. A permanent magnet type motor comprising a stator and a rotor rotatably disposed in a state of having a predetermined gap therein, and rotating the rotor by sequentially energizing the stator winding. The permanent magnets of the rotor are formed to have an arc-shaped cross section, and the permanent magnets are arranged on the rotor core so that the convex side faces inward, and the permanent magnet has a single magnetic flux at each part. The relationship between the average radius R of the permanent magnet and the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet is
It is characterized in that 1.0 × R ≦ L ≦ 7.5 × R.

The invention of claim 2 is a 3n phase (n is a natural number)
And a stator having a stator winding, and a plurality of permanent magnets incorporated in a rotor core. The stator is rotatably arranged in the stator with a predetermined gap. In a permanent magnet motor for rotating and driving the rotor by sequentially energizing the stator winding, each permanent magnet of the rotor is formed to have an arc-shaped cross section, Each of these permanent magnets is arranged on the rotor core so that the convex side faces inward, and the permanent magnet is magnetized so that the magnetic flux of each part thereof is concentrated at one point,
The relationship between the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet and the average radius R of the permanent magnet is 0.5
The feature is that xR ≦ L ≦ 7.0 × R.

[0015]

According to the invention of claim 1, the permanent magnets of the rotor are formed so that their cross sections are arcuate, and the permanent magnets are arranged on the rotor core so that the convex side faces inward. Moreover, the permanent magnet is magnetized so that the magnetic flux of each part thereof is concentrated at one point, and the relationship between the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet and the average radius R of the permanent magnet is By setting such that 1.0 × R ≦ L ≦ 7.5 × R, as will be apparent from the experimental result (relationship between L / R and magnetic flux in the air gap) described later, the stator and the rotor The magnetic flux density in the air gap between and can be increased.

[0016] The invention of claim 2 is particularly directed to the 3n phase (n
Is a natural number), each permanent magnet of the rotor is formed to have an arc-shaped cross section, and each permanent magnet is arranged on the rotor core so that the convex side faces inward. In addition, the permanent magnet is magnetized so that the magnetic flux of each part thereof is concentrated at one point, and the relationship between the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet and the average radius R of the permanent magnet. By setting so that 0.5 × R ≦ L ≦ 7.0 × R, the experimental result (L /
As is clear from the relationship between R and the magnetic flux in the air gap), the magnetic flux density in the air gap between the stator and the rotor can be increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a three-phase, four-pole permanent magnet type motor will be described below with reference to FIGS. First, in FIG. 2, the stator 21 has the same configuration as that of the conventional structure, and the U-phase stator winding 1U, is inserted into the twelve slots 23 formed in the annular stator core 22.
2U and V-phase stator windings 1V and 2V, and W-phase stator windings 1W and 2W are inserted and arranged.

On the other hand, the rotor 24 has a rotary shaft 25.
The rotor core 26 is fitted and fixed to the rotor core 26, and four permanent magnets 28 made of ferrite having an arc-shaped cross section in this case are inserted in the housing 27 formed in the rotor core 26 from the axial direction. Stator 2 which is constructed by incorporating
It is rotatably arranged in the inside of the stator 1 with the inner peripheral portion of the stator core 22 and a predetermined gap 29. The rotor core 26 is formed by laminating a large number of silicon steel plates having holes for forming the storage portion 27.

Each of the permanent magnets 28 is arranged so that the convex portion 28a side faces inward, and the four permanent magnets 28 are attached so that the N poles and the S poles alternate in FIG. It is magnetized. Further, as shown in FIG. 1, each permanent magnet 28 is magnetized so that the magnetic flux B of each portion is concentrated at one point, that is, the magnetic center C. And this permanent magnet 2
When the distance from the magnetic center C of 8 to the average arc line D of the permanent magnet 28 is L and the average radius of the permanent magnet 28 is R,
The distance L and the average radius R are 1.0 × R ≦ L ≦ 7.
The relationship of 5 × R is set.

The motor thus constructed is supplied with electric power from the inverter power source (see FIG. 10) as in the conventional case, and the stator windings 1U, 2U and 1V, 2 are provided.
Corresponding to V and stator windings for two adjacent phases of 1 W and 2 W, for example, the current is shifted by 180 degrees (electrical angle), that is, it is fixed by energizing 180 degrees (electrical angle). A rotating magnetic field is generated by the child 21, and the rotor 24 is rotated by the magnetic attractive force and repulsive force that accompany this.

Here, in FIG. 3, in the permanent magnet 28 of the rotor 24, the average arc line D from the magnetic center C is shown.
The experimental result of the relationship between L / R which is the ratio of the distance L to the average radius R and the magnetic flux in the air gap 29 of one pole is shown.

As is apparent from FIG. 3, when the L / R value is in the range of 1.0 to 7.5, the magnetic flux in the air gap 29 can be increased. As a result, L / R
By setting the value of 1.0 within the range of 1.0 to 7.5, that is, by setting L and R so that the relationship of 1.0 × R ≦ L ≦ 7.5 × R is established. The magnetic flux in the air gap 29 can be increased and the drive torque can be increased, whereby the motor can be downsized or the drive efficiency can be improved. In this case, even when compared with the case of magnetic pole axis direction anisotropy where the magnetic center is infinity (L / R is infinity),
It can be seen that the magnetic flux in the air gap 29 can be increased.

On the other hand, FIG. 4 shows a second embodiment of the present invention. In the second embodiment, the stator winding of the stator 21 is applied especially when it has 3n phases (n is a natural number). It was done. When the stator winding of the stator 21 is of the 3n phase, among the magnetic fluxes in the air gap 29, the third, ninth, and fifteenth fluxes are included.
Next, because the magnetic flux of higher harmonics does not work effectively on the stator winding, FIG. 4 shows the result of removing those higher harmonic components by calculation based on the data of the experimental results of FIG. It is a thing.

As is apparent from FIG. 4, when the stator winding has a 3n phase, the value of L / R is 0.5 to 7.0.
It can be seen that the magnetic flux in the air gap 29 can be increased when it is within the range. As a result, the value of L / R is 0.5 to
By setting it within the range of 7.0, that is, by setting L and R so that the relationship of 0.5 × R ≦ L ≦ 7.0 × R is satisfied, the magnetic flux in the air gap 29 is set. You can make it bigger,
The driving torque can be increased, and thereby the motor can be downsized or the driving efficiency can be improved. Also in this case, it can be seen that the magnetic flux in the air gap 29 can be increased as compared with the case of magnetic pole axial anisotropy in which the magnetic center is at infinity.

FIG. 5 shows a third embodiment of the present invention. In the third embodiment, the permanent magnet 30 of the rotor 24 is formed in an arc shape having a semi-cylindrical cross section, and such a permanent magnet 30 is arranged so that the convex portion 30a side is the inner side. .

In this case as well, the magnetic center C of the permanent magnet 30 is used.
, Average arc line D, and average radius R are set, and the relationship between the distance L from the magnetic center C to the average arc line D and the average radius R is set as in the first or second embodiment. By doing so, the same effect can be obtained.

In the present invention, the number of permanent magnets (number of poles)
May be other than 4 poles, and the number of slots in the stator is 12
It may be other than individual pieces. Further, the permanent magnet may be other than ferrite, or may be a part of an ellipse if it has an arc shape. The present invention can be variously modified and implemented without departing from the scope of the invention.

[0028]

According to the permanent magnet type motor according to the first aspect of the present invention, the permanent magnets of the rotor are formed so as to have an arc-shaped cross section, and the permanent magnets of the permanent magnets are located inside the rotor core on the convex side. The permanent magnet is magnetized so that the magnetic flux of each part of the permanent magnet is concentrated at one point, and the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet and the average The relationship with the radius R is 1.0 × R ≦ L ≦ 7.
By setting it to be 5 × R, it is possible to increase the magnetic flux density in the gap between the stator and the rotor and increase the driving torque, which can reduce the size or improve the driving efficiency. It has an excellent effect.

According to the second aspect of the present invention, the permanent magnet type motor has a stator winding of 3n phase (n is a natural number), so that each permanent magnet of the rotor has an arc-shaped cross section. In addition to forming the permanent magnets, the permanent magnets are arranged on the rotor core so that the convex side faces inward, and the permanent magnets are magnetized so that the magnetic flux of each part concentrates at one point. From the average arc line of the permanent magnet to L
And the average radius R of the permanent magnet is 0.5 × R ≦ L
By setting so that ≦ 7.0 × R, the magnetic flux density in the gap between the stator and the rotor can be increased, and the drive torque can be increased, thereby reducing the size or driving efficiency. It has an excellent effect that it can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention and showing a dimensional relationship of essential parts.

FIG. 2 is a sectional view of a motor

FIG. 3 is a diagram showing a relationship between L / R and magnetic flux in a gap.

FIG. 4 is a view corresponding to FIG. 3 showing a second embodiment of the present invention.

FIG. 5 is a side view of a rotor showing a third embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 2 showing a conventional configuration.

FIG. 7: Side view of rotor

FIG. 8 is an explanatory diagram showing a case where the magnetic arrangement of the permanent magnets is radial anisotropy.

FIG. 9 is an explanatory diagram showing a case where the magnetic arrangement of the permanent magnets is magnetic pole axis direction anisotropy.

FIG. 10 is an electrical configuration diagram.

[Explanation of symbols]

1U, 2U, 1V, 2V, 1W and 2W are stator windings, 21 is a stator, 24 is a rotor, 26 is a rotor core, 28 is a permanent magnet, 28a is a convex portion, 29 is a gap, 30
Is a permanent magnet, and 30a is a convex portion.

Claims (2)

[Claims] 1. A stator having stator windings of a plurality of phases,
The rotor core is configured by incorporating a plurality of permanent magnets inside, and the stator includes a stator and a rotor rotatably disposed in a state in which a predetermined gap is present. In a permanent magnet type motor for rotating and driving the rotor by sequentially energizing the wires, each permanent magnet of the rotor is formed to have an arc-shaped cross section, and each of the permanent magnets is projected on the rotor core. And the permanent magnet is magnetized so that the magnetic flux of each part thereof is concentrated at one point, and the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet,
A permanent magnet motor, wherein the relationship with the average radius R of the permanent magnet is 1.0 × R ≦ L ≦ 7.5 × R. 2. A stator having a stator winding of 3n phases (n is a natural number), and a plurality of permanent magnets incorporated in a rotor core, wherein the stator and the predetermined stator are provided. And a rotor that is rotatably disposed in a state where there is a gap between the rotor and the permanent magnet motor that drives the rotor by sequentially energizing the stator winding. Is formed so that the cross section has an arcuate shape, and each of these permanent magnets is arranged on the rotor core so that the convex side faces inward, and the permanent magnet is attached so that the magnetic flux of each part thereof is concentrated at one point. And the distance L from the magnetic center of the permanent magnet to the average arc line of the permanent magnet,
A permanent magnet type motor characterized in that the relationship with the average radius R of the permanent magnet is 0.5 × R ≦ L ≦ 7.0 × R.