JP2003274590A - Rotor of permanent-magnet synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor of various permanent-magnet synchronous motors, wherein reduction in size and increase of output are accomplished and the efficiency is improved. <P>SOLUTION: The rotor core of the motor is constituted of punched pieces from a non-oriented electromagnetic steel sheet which are laminated to form a rotor body. An even number of plate-like permanent magnets are placed inside the rotor body, in proximity to the circumferential surface of the rotor body with an equal interval in the circumferential direction. The permanent magnets are arranged so that the poles thereof alternate as viewed from the outside the rotor. Unidirectional electromagnetic steel sheets are placed as a magnetic force guide means which converges and guides the q-axis lines of magnetic force around the individual permanent magnets in the rotor, the lines of magnetic force going through the individual permanent magnets on the side of the center of the rotor, passing through between the adjacent permanent magnets, and reaching the circumferential portion of the rotor. The ratio of magnetic permeability μ1 of the non-oriented electromagnetic steel sheet to magnetic permeability μ2 of the unidirectional electromagnetic steel sheet is stipulated to lie within a specific range. <P>COPYRIGHT: (C)2003,JPO

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 with improved efficiency. More specifically, the rotor body of the motor is made of non-oriented electrical steel sheet, and the magnetic field line commutator is made of unidirectional one. The present invention relates to a technology using electromagnetic steel sheets.

[0002]

2. Description of the Related Art A rotor of a permanent magnet synchronous motor in which a permanent magnet is embedded in a rotor body is already widely used. For example, there is a rotor (A) 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 a plurality of concave grooves curved in the opposite direction to the outer circumference are arranged at equal intervals in the circumferential direction,
A permanent magnet is embedded in a part of the groove. Also,
There is a rotor (B) described in Japanese Patent Application Laid-Open No. 2000-201445 as a product in which a laminated body of electromagnetic steel plates is embedded so as to surround the permanent magnet.

[0003]

[Problems to be Solved by the Invention] The above rotor (A)
With the above configuration, the ratio of the d-axis inductance Ld and the q-axis inductance Lq, that is, Ld / Lq is large, and a large torque can be obtained. 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. Further, in the rotor (B), the electromagnetic steel plate is formed in a U shape for rectifying the magnetic force lines, and the surrounding permanent magnet is formed in a rectangular shape so that it can be manufactured more easily and the cost is reduced. However,
Higher torque is required for downsizing of motors.

In view of the above problems, an object of the present invention is to further increase the torque by 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) An even number of plate-shaped permanent magnets are arranged at equal intervals in the circumferential direction on the inner side of the outer periphery of the rotor body formed by stacking punched pieces of non-oriented electrical steel plates at the N pole as viewed from the outer side of the rotor, The S poles are alternately arranged, and the q-axis magnetic field lines in the rotor around the permanent magnets that pass through the rotor center side of each permanent magnet, pass through the gap between the adjacent permanent magnets, and reach the outer peripheral portion of the rotor. In a rotor of a permanent magnet synchronous motor in which a unidirectional magnetic steel sheet is arranged as a magnetic force rectifying means for converging and rectifying, when the magnetic permeability of the unidirectional magnetic steel sheet is μ1 and the magnetic permeability of the non-oriented magnetic steel sheet is μ2, , 20 <μ1 / μ2 <40. A rotor for a permanent magnet synchronous motor, characterized in that: (2) As the magnetic force line rectifying means, a U-shaped unidirectional electromagnetic steel plate curved toward the outer side of the rotor and a permanent magnet arranged on the inner side of the curved surface are embedded in the rotor. Magnet synchronous motor rotor. (3) The non-oriented electrical steel sheet of the outer portion of each permanent magnet embedded in the rotor body is cut out along the long side of the permanent magnet to increase the gap between the rotor outer edge and the stator, and the outer edge of the non-permanent magnet arrangement portion. Characterized by having a stepped gap structure with a small gap between the stator and the stator (1)
Alternatively, the rotor of the permanent magnet synchronous motor according to (2).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in order to improve the efficiency of the current motor, increase the output torque, downsize the shape, etc., in the permanent magnet synchronous motor, the amount of magnetic flux generated from the permanent magnet, and The Lq / Ld ratio must be increased. Here, Lq is the inductance in the q-axis direction in which magnetic flux easily flows, and Ld is the inductance in the d-axis direction in which the permanent magnets are arranged. The present inventors paid attention to the material of the rotor portion and conducted earnest research to effectively realize a method of increasing the Lq / Ld ratio.

As a result, when it is considered to control the direction of the magnetic flux flowing in the rotor body to increase the Lq / Ld ratio, the inventors locally change the magnetic permeability in the rotor,
We have come to the knowledge that it suffices to guide the magnetic flux to the part with high magnetic permeability. As a result of experiments, when the unidirectional electrical steel sheet was incorporated into the non-oriented electrical steel sheet, the magnetic flux was concentrated in the easy magnetization direction (rolling direction) of the unidirectional electrical steel sheet. Therefore,
Among the unidirectional electrical steel sheets, one having a high magnetic permeability was used as a commutator, and the surrounding non-oriented electrical steel sheet having a low magnetic permeability was selected to construct the rotor, and a high torque was obtained. It is considered that the salient pole ratio (Lq / Ld) of the motor was 8 or more in this rotor, and a large reluctance torque was obtained.

Next, the reasons for limitation of the present invention will be described. The reason why the rotor body is a non-oriented electrical steel sheet and the magnetic field line commutator is a unidirectional electrical steel sheet is due to such material selection.
This is because it becomes easier for the magnetic flux to flow along the magnetic field line commutator in which the unidirectional magnetic steel sheets having high magnetic permeability are laminated, and the torque can be increased. In addition, the ratio of the magnetic permeability of the unidirectional magnetic steel sheet in the q-axis direction of the rotor to the magnetic permeability of the non-oriented magnetic steel sheet is 2
The reason why the value is more than 0 and less than 40 is that when it exceeds 20, the salient pole ratio (Lq / Ld) of the motor becomes 8 or more, and a large reluctance torque is obtained. On the other hand, when it is 40 or more, cogging occurs, so it is set to less than 40.

The reason why the permanent magnets are arranged inside by using a curved unidirectional magnetic steel plate as the magnetic force line rectifying means is that the magnetic flux from the permanent magnets can be efficiently flowed to the stator teeth and the reluctance torque is generated. Axis L
This is because q becomes large.

Also, the radially outer portion of each permanent magnet in the rotor body is cut out along the long side of the permanent magnet to widen the gap with the stator on the outer edge of the rotor, and with the stator on the outer edge of the permanent magnet non-arranged portion. The reason for adopting the stepped gap structure with a small gap is that the reluctance torque is positively used rather than the torque generated by the magnetic flux from the permanent magnet to have the effect of suppressing the cogging.

[0011]

EXAMPLES Examples will be described below. [First Embodiment] FIG. 1 is a diagram showing a first embodiment of the present invention.
In FIG. 1, a rotor body 2 that is stacked inside to form a rotor is shown inside the stator 1. Eight rectangular notches 3 are formed on the rotor body 2 at equal intervals in the circumferential direction,
Eight permanent magnets 4 are embedded in the notch 3. These permanent magnets 4 are embedded so that adjacent ones have opposite magnetic poles. The number of permanent magnets may be other than eight, but it is necessary that the number of permanent magnets is even in order that adjacent magnets have opposite magnetic poles as described above.

A U-shaped cutout 5 is formed in the rotor body 2 so as to surround each of the permanent magnets 4 embedded as described above, and each cutout 5 has a unidirectional electrical steel sheet. The laminated body 6 is embedded. In this case, μ in the rolling direction is 0.115 H / m for grain-oriented electrical steel sheets (0.
23mm thick) for commutator, L + C μ is 0.004H /
Since the non-oriented electrical steel sheet of m (0.5 mm thickness) is used for the rotor body, the Lq / Ld ratio is increased and a large torque can be obtained. Ferrite is used for the permanent magnet, and the shape is simple rectangle, so it is easy to form. On the other hand, the unidirectional electrical steel sheet laminate for the magnetic commutator is also easy to manufacture because it is simply laminated electromagnetic steel sheets. .

[Embodiment 2] FIG. 2 shows the structure of the embodiment 2, which is a slight modification of the embodiment 1, but a unidirectional electromagnetic steel sheet laminate formed on a rotor. It is intended to improve the strength of the rotor by reducing the notch 5 in which 6 is embedded. The notches 5 are each divided into two, and the unidirectional electrical steel sheet laminate 6 embedded in the notches 5 is formed.
Is also divided into two. Here, by providing the stepped gap 7 on the rotor body side, the magnetic permeability Lq on the q-axis side is improved, and conversely by forming the notch, the magnetic permeability Ld on the d-axis side is reduced, and this shape effect Further increased Lq / Ld ratio

[0014]

According to the present invention described in each claim, a rotor of the type in which a permanent magnet is embedded in the rotor body is provided, but the shape of the permanent magnet embedded in the rotor body is different from the shape of the magnetic force line rectifying means. Since it is a simple rectangle, it is easy to manufacture. Since the magnetic force line rectifying means is formed by embedding an electromagnetic steel plate, it is not necessary to bend the rotor plate or form a groove, and the manufacture is simple.

In particular, as in claim 2, the magnetic field line commutator and the rotor body are made of a unidirectional magnetic steel sheet and a non-oriented magnetic steel sheet, respectively, and the torque is increased by determining the magnetic permeability ratio.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a form of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a form of a second embodiment of the present invention.

[Explanation of symbols]

1 Stator 2 Rotor body 3 Notch (for permanent magnet) 4 Permanent magnet 5 Notch (for unidirectional electrical steel sheet) 6 Unidirectional electrical steel sheet laminate 7 Stepped gap

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) H02K 19/10 H02K 19/10 A 21/16 21/16 M (72) Inventor Kaido Michi Futtsu City, Chiba Prefecture 20-1 Shintomi Nippon Steel Co., Ltd. Technology Development Headquarters (72) Inventor Masao Washimoto 20-1 Shintomi, Futtsu City, Chiba F-Term (Technical Reference Section), Technology Development Headquarters, Nippon Steel Co., Ltd. 5H002 AA06 AB07 AC06 AC08 AE08 5H615 AA01 BB01 BB07 BB14 PP02 PP07 SS05 SS10 SS15 TT04 TT05 5H619 AA01 BB01 BB13 BB15 BB24 PP02 PP05 PP06 5H621 BB07 GA01 GA04 HH01 JK03 JK05 5H622 AA03 CA02 CA10 CB01 CB05 PP07 PP10 QA

Claims (3)

[Claims] 1. An even number of plate-shaped permanent magnets inside the rotor main body, which is formed by stacking punched pieces of non-oriented electrical steel sheets, at equal intervals in the circumferential direction when viewed from the outside of the rotor.
The q-axis in the rotor around the permanent magnets, in which the poles and the S poles are arranged alternately, pass through the rotor center side of each permanent magnet, pass through the gap between the adjacent permanent magnets, and reach the outer periphery of the rotor. In a rotor of a permanent magnet synchronous motor in which a unidirectional magnetic steel sheet is arranged as magnetic force rectifying means for converging and rectifying the magnetic force lines, the magnetic permeability of the unidirectional magnetic steel sheet is μ1, and the magnetic permeability of the non-oriented magnetic steel sheet is μ2. A rotor for a permanent magnet synchronous motor, which satisfies 20 <μ1 / μ2 <40 when 2. The magnetic force line rectifying means, wherein a U-shaped unidirectional electromagnetic steel plate curved toward the outside of the rotor and a permanent magnet arranged inside the curved surface are embedded in the rotor. Permanent magnet synchronous motor rotor. 3. The non-oriented electrical steel sheet on the outer side of each permanent magnet embedded in the rotor body is cut out along the long side of the permanent magnet to increase the gap between the outer edge of the rotor and the stator so that no permanent magnet is arranged. The rotor for a permanent magnet synchronous motor according to claim 1 or 2, wherein the rotor has a stepped gap structure in which a gap between the outer edge of the part and the stator is reduced.