JP2003284274A - Permanent magnet synchronous motor rotor - Google Patents

Abstract

(57) [Problem] To provide a permanent magnet synchronous motor of a type in which permanent magnets are embedded in a rotor body, to further increase the torque in the rotor and to reduce the size and increase the efficiency. SOLUTION: 2n pieces of plate-like permanent magnets are arranged at equal intervals in the circumferential direction inside the vicinity of the outer periphery of a rotor main body formed by laminating punched pieces of unidirectional electromagnetic steel sheets when viewed from the outside of the rotor.
The poles and the S poles are alternately arranged, and the rolling direction of the grain-oriented electrical steel sheet is evenly wound so that the rolling direction is parallel to one of the n low magnetic resistance directions (q axis) of the rotor. Make up the iron core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rotors of various permanent magnet synchronous motors for improving efficiency, and more specifically, to make them parallel to the low magnetic resistance direction (q axis) of the rotor.
The present invention relates to a rotor having laminated unidirectional magnetic steel sheets.

[0002]

2. Description of the Related Art A reluctance motor rotor having a permanent magnet embedded in a rotor body is already widely used. For example, there is a rotor described in JP-A-10-112965. The rotor described in this publication has a plurality of core sheets of a high-permeability material in which concave grooves curved in a direction opposite to the outer circumference circle are arranged in multiple layers at equal intervals in the circumferential direction. It is a permanent magnet embedded in the part. Further, there is a rotor described in Japanese Patent Laid-Open No. 2000-201445 as a permanent magnet synchronous motor in which a laminated body of electromagnetic steel sheets is embedded so as to surround the permanent magnet. Further, as examples of using a unidirectional magnetic steel sheet for the rotor, there are JP-A-10-248220 and JP-A-10-257702.

[0003]

[Patent Document 1] Japanese Patent Application Laid-Open No. 10-1129
The rotor disclosed in Japanese Patent Publication No. 65 has a large ratio of the d-axis inductance Ld and the q-axis inductance Lq, that is, Ld / Lq, due to the above-described configuration, and can obtain a large torque. On the other hand, since permanent magnets are embedded in many curved thin grooves, there is a problem in that manufacturing is time-consuming and costly. Also, Japanese Patent Laid-Open No. 2000-201445.
In the rotor disclosed in the publication, the electromagnetic steel plate is U-shaped for magnetic field line rectification, and the surrounding permanent magnet is rectangular, so that it can be manufactured more easily and the cost is reduced. Also,
An example of using a grain-oriented electrical steel sheet having anisotropic magnetic characteristics also in the rotor of a reluctance motor (Japanese Patent Laid-Open No. 10-2
48220) and an example in which a permanent magnet is arranged on the protrusion of the rotor to increase the torque (JP-A-10-257702). However, higher torque is required to downsize the motor.

In view of the above problems, an object of the present invention is to further increase the torque in the rotor of a permanent magnet synchronous motor of the type in which a permanent magnet is embedded in the rotor body, thereby enabling miniaturization and increasing efficiency. To provide a rotor.

[0005]

The concrete means of the present invention are as follows. (1) 2n plate-shaped permanent magnets are arranged at equal intervals in the circumferential direction on the inner side in the vicinity of the outer circumference of the rotor body formed by stacking punched pieces of unidirectional electromagnetic steel plates at the N pole as viewed from the outside of the rotor, In a rotor of a permanent magnet synchronous motor in which S poles are alternately arranged, the unidirectional magnetic steel sheets are evenly rolled so that the rolling direction is parallel to any of the n low magnetic resistance directions (q axis) of the rotor. A rotor for a permanent magnet synchronous motor, characterized in that (2) To have a stepped gap structure in which the gap between the rotor outer edge of the permanent magnet non-arranged portion and the stator between adjacent permanent magnets of the rotor body is smaller than the gap between the rotor outer edge of the permanent magnet arranged portion and the stator. (1) The rotor of the permanent magnet synchronous motor according to (1).

[0006]

As described above, in order to improve the efficiency of the current motor, increase the output torque, and reduce the size of the motor, the amount of magnetic flux generated from the permanent magnets in the permanent magnet synchronous motor, And Lq / Ld ratio must be increased. The present inventors paid attention to the material of the rotor portion and conducted earnest research to effectively realize the latter method of further increasing the Lq / Ld ratio.

As a result, when considering how to control the direction of the magnetic flux flowing in the rotor body and increase the Lq / Ld ratio, the inventors have selected a material so that a high magnetic permeability characteristic appears in the q-axis direction. We have come to the knowledge that they should be placed. As a result of experiments, it was confirmed that the torque of the laminated rotor was increased with the direction of easy magnetization (rolling direction) of the grain-oriented electrical steel sheet oriented in the q-axis direction. The cause is considered as follows.

The equation representing the motor torque is T = Pn {Ψa iq + (Ld-Lq) id iq} (Equation 1). Here, Pn is the number of pole pairs, Ψa is an armature flux linkage by a permanent magnet, Ld, Lq are d-axis and q-axis inductances, id and iq are d and q components of the armature current. Since id and iq are control factors other than the constituent materials and shape of the motor, and Ψa is determined by the type of permanent magnet, it is not directly related to the iron core of the rotor. In the present invention, the d-axis and q-axis inductances are changed according to the rotor core material and the stacking method, and Lq
In order to maximize the / Ld ratio, a unidirectional electrical steel sheet is used, and Lq is increased by aligning the easy magnetization direction with the q axis, and d
The axis was set to a relatively low value and the Lq / Ld ratio was increased. It is considered that this increases the torque according to the equation (Equation 1). In fact, the salient pole ratio (Lq /
When Ld) was measured, it was 7 or more in this prototype rotor, and a large reluctance torque was obtained.

Next, the reasons for limitation of the present invention will be described. The reason why the unidirectional electrical steel sheets are alternately stacked so as to be parallel to the low magnetic resistance direction (q axis) of the rotor is to further increase the value of Lq (Lq / Ld).
Further, when the rotor has 2n poles, there are n q-axes. Therefore, the reason why the unidirectional electrical steel sheets are evenly rotated and stacked is that the easy magnetization direction is uniformly oriented on all q-axes.

The reason why the stepped gap structure is formed by reducing the gap between the adjacent permanent magnets of the rotor body and the stator at the rotor outer edge of the non-permanent magnet arrangement is that the permanent magnets between the adjacent permanent magnets of the rotor are The stepped gap structure is formed by increasing the gap between the rotor outer edge of the permanent magnet arrangement portion and the stator and decreasing the gap between the rotor outer edge of the permanent magnet non-arrangement portion between the adjacent permanent magnets of the rotor and the stator. , Q-axis magnetic force lines around each permanent magnet are converged and rectified. The following is a description based on experiments.

[0011]

EXAMPLES Example 1 An example of the present invention will be described. A laminated rotor body 1 is shown in FIG. Rotor body 1
Has four rectangular notches 2 formed at equal intervals in the circumferential direction, and four permanent magnets 3 are embedded in the notches. These permanent magnets 3 are embedded so that adjacent ones have opposite magnetic poles. The number of permanent magnets is 4
It may be other than the number, but as described above, it is necessary that the numbers are even in order that adjacent magnetic poles have opposite magnetic poles.

The rotor body 1 is laminated in parallel with two q-axis directions orthogonal to each other such that the rolling directions of the unidirectional electrical steel sheets are evenly oriented. Since the first embodiment is configured as described above, the magnetic permeability Lq in the q-axis direction is improved and the magnetic permeability Ld in the d-axis direction is decreased, so that Lq / L
A large torque can be obtained by increasing the ratio of d.

[Embodiment 2] FIG. 2 shows the structure of Embodiment 2, which is a modification of the configuration of Embodiment 1, except that eight rectangles are arranged at equal intervals in the circumferential direction of the rotor. The notch 2 is formed, and eight permanent magnets 3 are embedded in the notch. These permanent magnets 3 are embedded so that adjacent ones have opposite magnetic poles. Similar to the first embodiment, here, the unidirectional electrical steel sheets are laminated parallel to the four q-axis directions so that the rolling directions thereof are evenly oriented. Also in the second embodiment, the magnetic permeability Lq in the q-axis direction is improved and the magnetic permeability Ld in the d-axis direction is decreased, so that Lq /
A large torque can be obtained by increasing the ratio of Ld.

[Third Embodiment] FIG. 3 shows the structure of the third embodiment, which is a modification of the first and second embodiments and realizes the second aspect. By forming the step 5 between the stator 4 and the rotor 1, the magnetic permeability Lq in the q-axis direction is improved, and conversely, by forming the notch, the magnetic permeability Ld in the d-axis direction is decreased, so that Lq / Ld The ratio can be increased and a large torque can be obtained. Further, this rotor body is laminated so that the rolling direction of the unidirectional electrical steel sheet is parallel to the eight q-axis directions, the magnetic permeability Lq in the q-axis direction is improved, and the magnetic permeability Ld in the d-axis direction is decreased. , So Lq /
A large torque can be obtained by increasing the ratio of Ld.

[0015]

According to the invention described in each of the claims, a rotor of the type in which a permanent magnet is embedded in the rotor body is provided, but it is evenly arranged so as to be parallel to the low magnetic resistance direction (q axis) of the rotor. The torque is increased by laminating the unidirectional electrical steel sheets.

[Brief description of drawings]

FIG. 1 is a diagram showing a rotor structure according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a rotor structure according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a rotor structure according to a third embodiment of the present invention.

[Explanation of symbols]

1 rotor body 2 notch 3 Permanent magnet 4 Stator 5 steps

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor openness             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Masao Utanimoto             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division F-term (reference) 5E062 AA06 AC01                 5H002 AA01 AA09 AB08 AC06 AE07                 5H622 AA03 CA02 CA05 CA10 CA11                       CB05 PP11 PP19

Claims (2)

[Claims] 1. A 2n number of plate-shaped permanent magnets are arranged at equal intervals in the circumferential direction inside the rotor body formed by stacking punched pieces of unidirectional electromagnetic steel plates at an equal interval in the circumferential direction, and N
In a rotor of a permanent magnet synchronous motor in which poles and S poles are alternately arranged, the rolling direction of the unidirectional magnetic steel sheet is evenly arranged so as to be parallel to any of the n low magnetic resistance directions (q axis) of the rotor. A rotor for a permanent magnet synchronous motor, which is characterized by being rolled up and stacked. 2. A stepped gap structure in which the gap between the rotor outer edge of the permanent magnet non-arranged portion and the stator between adjacent permanent magnets of the rotor body is smaller than the gap between the rotor outer edge of the permanent magnet arranged portion and the stator. The rotor of the permanent magnet synchronous motor according to claim 1, which has.