JPH07222385A - Reverse salient cylindrical magnet synchronous motor - Google Patents

Abstract

PURPOSE:To obtain a reverse salient cylindrical magnet synchronous motor which can be manufactured easily by fitting a cylindrical permanent magnet having protrusions and recesses over a rotor core having recesses and protrusions and providing a rotor magnetized alternately with N and S in the radial direction at the protrusion of the magnet. CONSTITUTION:Arcuate core recesses 1a are made at positions dividing the circumference of a rotor core 1 equally into four and core protrusions 1b are formed between respective recesses 1a. Magnet protrusions 3a having profile reverse to that of the core recess 1a are formed on the inner periphery of a cylindrical permanent magnet 3 and magnet recesses 3b having profile reverse to that of the core protrusion 1b are made between respective magnet protrusions 3a. The magnet protrusions 3a are fitted to the core recesses 1a and the core protrusions 1b are fitted to the magnet recesses 3b before the cylindrical permanent magnet 3 is bonded through adhesive to the outer diametral part of the rotor core 1. Furthermore, the magnet protrusions 3a are magnetized alternately with N and S in the radial direction. The rotor is then fixed to the inside of the stator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse saliency cylindrical magnet synchronous motor having a cylindrical permanent magnet and having a reverse saliency.

[0002]

2. Description of the Related Art In a synchronous motor, a DC field is required, and therefore a DC power supply is indispensable as well as an AC power supply. Since then, with the advent of magnetic materials and the advent of inexpensive ferrite magnets with large coercive force, the applications of permanent magnet synchronous motors using permanent magnets have expanded. The torque of the salient pole type synchronous motor includes torque due to Lorentz force and reluctance torque. The reluctance torque is a torque generated by magnetic attraction between the magnetic flux generated from the stator winding current and the rotor core. When considering the action of the armature current of the synchronous motor, the reactance by the two-reaction method is used. Here, in general, the direct-axis reactance with respect to the direct-axis current is larger than the horizontal-axis reactance with respect to the horizontal-axis current, and the reactance torque is opposite to the torque due to the Lorentz force. However, if the horizontal axis reactance has a so-called reverse saliency larger than the direct axis reactance, the reactance torque works in the same direction as the Lorentz force, and the torque characteristic of the synchronous motor can be improved.

In the three-phase permanent magnet synchronous motor, it is necessary to detect the position of the rotor, and there are the following methods for utilizing the reverse salient polarity for detecting the rotor position. The change in the inductance of the armature winding due to the change in the rotor angle with reference to the winding axis of the specific phase winding shows that the inductance of each phase differs depending on the position of the rotor. The position of the rotor can be known from the change in the relative value depending on the rotational position of. Further, there is a method of knowing the position of the rotor by converting the instantaneous values of the voltages and currents of each phase into three phases and two phases and obtaining the deviation angle between the direct axis and the horizontal axis.

There is a method of operating a permanent magnet synchronous motor with high efficiency by utilizing reverse salient polarity. It effectively utilizes the reluctance torque generated by the difference between the direct-axis reactance and the horizontal-axis reactance to control the current vector,
It is intended to always operate at maximum efficiency.

In the conventional permanent magnet synchronous motor, slots having opening portions are formed at equal intervals on the inner peripheral side of a substantially annular stator core, and the stator winding is housed therein. A rotor having a permanent magnet attached to a rotor core is arranged inside the stator. The structure of a conventional rotor will be described with reference to FIGS. FIG. 3 is a vertical sectional view of a rotor of a conventional reverse salient pole permanent magnet synchronous motor. The permanent magnet 2 has a trapezoidal cross section, is inserted into a hole formed in the rotor iron core 1 in the axial direction, and four permanent magnets 2 in which magnetic poles N and S are alternately magnetized in the radial direction are symmetrical. It is located in. FIG. 4 is a vertical sectional view of a rotor of another conventional reverse salient pole permanent magnet synchronous motor. In the example of FIG. 4, four arc-shaped core concave portions 1a are provided on the outer diameter side of the rotor core 1, and four arc-shaped permanent magnets 2 in which magnetic poles N and S are alternately magnetized in the radial direction are provided. Is the core recess 1
It is attached to a and arranged symmetrically. 3 and 4
In the structure of, the horizontal axis reactance is larger than the direct axis reactance and the reverse salient polarity is obtained.

FIG. 5 is a vertical sectional view of a conventional synchronous motor using a cylindrical permanent magnet. A cylindrical permanent magnet 2 is attached to the outer diameter side of the rotor core 1 with an adhesive, and magnetic poles N and S are alternately magnetized in the radial direction and arranged continuously. In this structure, the reverse salient polarity hardly appears, but the rotor core 1 and the permanent magnet 2 can be easily attached, and the magnet core can be magnetized after being attached to the rotor core.

[0007]

In the conventional permanent magnet synchronous motor, it is difficult to magnetize the permanent magnet 2 after it is mounted on the rotor core 1 in the structure shown in FIGS. 3 and 4, so that it is magnetized in advance. Therefore, there is a problem that it takes time to store and handle the magnetized permanent magnet 2. Further, it takes time and effort to embed the magnetized permanent magnet 2 in the rotor core 1 or to mount it on the rotor core 1 via a mounting member, resulting in poor productivity. Conventional cylindrical permanent magnet 3
Then, it is easy to attach the permanent magnet to the rotor core 1, but
Since there is no reverse salient polarity, there is a problem that reactance torque is not generated.

An object of the present invention is to provide a reverse saliency cylindrical magnet synchronous motor which has a reverse saliency and is easy to manufacture.

[0009]

[Means for Solving the Problems] A stator obtained by winding a plurality of phases of stator windings around a substantially annular stator core, and an outer diameter side of a rotor core concentric with the inner peripheral surface of the stator. In a cylindrical magnet synchronous motor comprising a rotor provided with a cylindrical permanent magnet that is arranged in a radial direction in which N and S are alternately magnetized for each magnetic pole, the rotor is arranged at positions that equally divide the outer circumference of the rotor core. Arc-shaped even-numbered core recesses, core protrusions formed between the core recesses, and arc-shaped magnet protrusions projecting to the inner circumference of the cylindrical permanent magnet and having an inverse shape to the core recesses, and the magnet protrusions. The rotor is provided with a magnet concave portion having a shape opposite to that of the iron core convex portion, the cylindrical permanent magnet is fitted on the outer diameter side of the rotor iron core, and N and S are alternately attached to the iron core convex portion in the radial direction. The above object is achieved by providing a magnetized rotor.

[0010]

According to the present invention, even-numbered arc-shaped core recesses arranged at positions that equally divide the outer periphery of the rotor core, the core protrusions formed between the core recesses, and the inner periphery of the cylindrical permanent magnet. A cylindrical permanent magnet is fitted to the outer diameter side of the rotor iron core, which is provided with an arcuate magnet convex portion having a shape reverse to that of the protruding core concave portion and a magnetic core concave portion formed between the magnet convex portions and having a shape opposite to the core convex portion. , N and S are alternately magnetized in the radial direction on the convex portion of the iron core, and the magnetic permeability of the permanent magnet is almost equal to the magnetic permeability of air. Therefore, the gap between the permanent magnet and the stator is It is equal to be narrower than the magnetic pole. Therefore, the magnetic resistance of the direct-axis magnetic path with respect to the direct-axis magnetic flux becomes smaller than the magnetic resistance of the horizontal-axis magnetic path with respect to the horizontal-axis magnetic flux, and the horizontal-axis reactance becomes larger than the direct-axis reactance, exhibiting so-called reverse saliency.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of a reverse salient-polarity cylindrical magnet synchronous motor according to an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. In FIG. 1, the rotor core 1 is provided with four arcuate core recesses 1a arranged at positions that divide the outer circumference of the rotor core 1 into four equal parts, and a core protrusion 1b formed between the core recesses 1a. The cylindrical permanent magnet 3 is provided with an arc-shaped magnet protrusion 3a having a shape reverse to that of the iron core recess 1a and a magnet recess 3b having a shape reverse to that of the iron core protrusion 1b formed between the magnet protrusions 3a. The magnet convex portion 3a is fitted in the iron core concave portion 1a, the iron core convex portion 1b and the magnet concave portion 3b are fitted, and the cylindrical permanent magnet 3 is bonded to the outer diameter side of the rotor iron core 1 with an adhesive. In addition, N, S on the magnet protrusion 3a
Are alternately magnetized in the radial direction. The rotor thus configured is attached to the inside of the stator. Since the cylindrical permanent magnet 2 is integrated, it can be easily attached to the rotor core 1. Further, it is possible to magnetize the magnet iron core after it is attached to the rotor iron core 1, and the handling of the magnet iron core does not take time.

FIG. 2 is a diagram showing a magnetic path of an armature current of a reverse salient-polarity cylindrical magnet synchronous motor equipped with the rotor of FIG.
Straight axis magnetic path 4d, which is the magnetic path of the straight axis magnetic flux passing through the center of the magnetic pole
Means that the magnetic permeability of the permanent magnet 3 passes through the magnet convex portion 3a of the cylindrical permanent magnet 3 and is the same as the magnetic permeability of air. Therefore, this portion means that the gap between the stator and the rotor is large. The magnetic resistance of the magnetic path 4d is large. On the other hand, the horizontal magnetic path 4q, which is the magnetic path of the horizontal magnetic flux passing through the inter-pole portion 3b of the magnetic pole, has a small thickness in the radial direction of the iron core, so that the air gap between the stator and the rotor is narrow in this portion. This means that the magnetic resistance of the horizontal magnetic path 4q is small. As a result, the horizontal axis reactance becomes larger than the direct axis reactance, and reverse saliency is obtained. In this way, the cylindrical synchronous motor according to the present invention can improve the torque characteristics.

[0013]

According to the present invention, a cylindrical permanent magnet having a convex portion and a concave portion is fitted on the outer diameter side of a rotor core having a concave portion and a convex portion, and the magnet convex portion has a radius of N and S alternately. Since a rotor magnetized in the direction is provided, the magnetic resistance is large because the direct-axis magnetic path passes through the thick magnet convex portion, and the magnetic resistance is small because the horizontal-axis magnetic path passes through the thin inter-pole portion. Is obtained, and the torque characteristic can be improved. Further, since the integral cylindrical permanent magnet is attached to the rotor core, the rotor can be easily manufactured. Furthermore, the magnet core can be magnetized after it is attached to the rotor core, and the handling of the magnet core does not take much effort.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotor of a reverse salient-polarity cylindrical magnet synchronous motor according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a magnetic path of a magnetic flux due to an armature current of the reverse salient-polarity cylindrical magnet synchronous motor of FIG.

FIG. 3 is a vertical sectional view of a rotor of a conventional reverse salient pole permanent magnet synchronous motor.

FIG. 4 is a vertical sectional view of a rotor of another conventional reverse salient pole permanent magnet synchronous motor.

FIG. 5 is a vertical sectional view of a rotor of a conventional cylindrical magnet synchronous motor.

[Explanation of symbols]

 1 Rotor Iron Core 1a Iron Core Recess 1b Iron Core Convex 2 Permanent Magnet 3 Cylindrical Permanent Magnet 3a Magnet Convex 3b Magnet Recess 4 Stator 4d Straight Axis Magnetic Path 4q Horizontal Axis Magnetic Path

Claims (1)

[Claims] 1. A stator in which a plurality of phases of stator windings are wound around a substantially annular stator core, and a stator magnetic core is disposed on the outer diameter side of a rotor core concentric with the inner peripheral surface of the stator, and magnetic poles are provided. A cylindrical magnet synchronous motor consisting of a rotor provided with a cylindrical permanent magnet magnetized in the N and S alternately in the radial direction for each, in a circular arc shape arranged at a position equally dividing the outer circumference of the rotor core. Even-numbered core recesses, core protrusions formed between the core recesses, arc-shaped magnet protrusions projecting to the inner circumference of the cylindrical permanent magnet and having an inverse shape to the core recesses, and formed between the magnet protrusions. Rotation in which the convex portion of the iron core and the concave portion of the magnet having the opposite shape are provided, the cylindrical permanent magnet is fitted to the outer diameter side of the rotor iron core, and the convex portion of the iron core is alternately magnetized in the radial direction in N and S directions. A reverse salient-polarity cylindrical magnet synchronous motor characterized by having a child.