WO2019083067A1

WO2019083067A1 - Electric generator for reducing cogging torque

Info

Publication number: WO2019083067A1
Application number: PCT/KR2017/011988
Authority: WO
Inventors: 윤양운
Original assignee: 주식회사 지앤씨에너지
Priority date: 2017-10-27
Filing date: 2017-10-27
Publication date: 2019-05-02

Abstract

The present invention relates to an electric generator for reducing cogging torque and, more specifically, to an electric generator for reducing cogging torque, the electric generator reducing cogging torque and leakage flux generated during driving of the electric generator, thereby enabling generation efficiency of the electric generator to increase. The electric generator for reducing cogging torque, according to the present invention, repeatedly changes, along a circumferential direction, an interval between an end portion of a permanent magnet provided in a rotor and teeth formed in a stator, thereby enabling cogging torque to be remarkably reduced in comparison with a conventional electric generator in which an interval between a permanent magnet and teeth is uniformly fixed.

Description

Generator for cogging torque reduction

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator for reducing cogging torque, and more particularly, to a generator for reducing cogging torque which can increase the power generation efficiency of a generator by reducing cogging torque and leakage magnetic flux generated when the generator starts.

Recently, a lot of research is being done in the field of renewable energy to reduce carbon dioxide emission, which is the main cause of global warming. In particular, the wind power generation sector, where electricity can be obtained by installing a generator at a low cost wherever there is wind, has been growing steadily.

Until now, wind turbines equipped with geared induction generators have been popular in land-based large-scale wind power generation. However, in recent years, there has been a rapid growth of offshore wind power generation market, and a geared synchronous generator having maintenance- The market is being reorganized with wind turbines equipped with generators.

Especially, in the case of a small wind turbine with a large power fluctuation, the majority of the use of a permanent magnet generator requiring low RPM and high torque is required.

However, permanent magnet generators having low revolutions per minute and high torque are disadvantageous in that initial starting is difficult due to high magnetic flux density of the permanent magnet and high magnetic field unbalance between the core and the permanent magnet due to high cogging torque .

Therefore, in order to minimize the starting torque and the cogging torque in a small wind turbine, it is necessary to use a coreless type AFPM (Axial Flux Permanent Magnet) generator in which an iron core is removed in order to enable the blade to start at a low wind speed, Slotless RFPM (Radial Flux Permanent Magnet) generators are on the rise.

However, the coreless type AFPM generator and the slotless RFPM generator have a disadvantage in that the output voltage is lowered and the efficiency is lowered due to the higher flux leakage than the RFPM generator having the slot.

In addition, since the structure is complicated and the number of permanent magnets used increases, the cost increases, and it is not easy to increase the capacity due to the structural problem of the generator itself.

The slotted RFPM generator is simple in structure, high in output voltage and efficiency, small in size and light in weight, but has a disadvantage in that initial starting is difficult due to large cogging torque, and vibration is generated even in rated operation.

Recently, in order to use a RFPM generator with a slot in a wind power generator, BLDC motor technology is applied to an RFPM generator to minimize cogging torque. However, most of them are for high RPM, Have.

The cogging torque can be defined as a pulsating torque generated by a tendency of the magnetic circuit composed of the rotor permanent magnet, the stator core, and the gap to keep the reluctance in the minimum direction. Generally, the permanent magnet generator and permanent magnet The difference between the maximum value and the minimum value of the torque generated by the unbalance of the magnetic field when the rotor is driven in the magnet motor.

Recently, in the field of motors, various methods for reducing the cogging torque, which is the main cause of vibration and noise, have been proposed as the demand of super premium motors using permanent magnets is increasing. Up to now, they have been used as methods for reducing cogging torque To summarize the methods, there are two methods to increase the length of the gap, increase the number of slots and poles, use auxiliary slots, change the shape of the stator, skew the stator or armature, use fraction slots or poles, Shape change of the magnetic pole, magnetization change of the magnetic pole, use of the magnet having a low magnetic flux density, and the like.

However, the above-described conventional methods for reducing the cogging torque are a major factor for reducing the output and efficiency of the permanent magnet motor and the permanent magnet generator, or increasing the manufacturing cost. Therefore, it is urgently required to develop a cogging torque reduction method that does not increase the manufacturing cost while minimizing the reduction of the output and efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems as described above, and it is an object of the present invention to reduce the cogging torque generated during rotation of the rotor, reduce the leakage magnetic flux of the permanent magnet, The present invention has been made to solve the above problems.

According to an aspect of the present invention, there is provided a generator for reducing cogging torque, comprising: a rotor having a cylindrical shape and having a plurality of permanent magnets spaced apart from each other along a circumferential direction; A plurality of teeth protruding toward the outer circumferential surface of the rotor are formed on the inner circumferential surface of the hollow portion facing the outer circumferential surface of the rotor at predetermined intervals along the circumferential direction, A permanent magnet which is arranged to be spaced apart from the end of the tooth by a predetermined first interval, and a permanent magnet which is spaced apart from the end of the tooth by a predetermined second interval, And the magnets are arranged alternately with each other.

Wherein the permanent magnet includes a plurality of first permanent magnets having a first predetermined thickness and a plurality of second permanent magnets having a second thickness thinner than the first permanent magnets, As shown in Fig.

Wherein the permanent magnet includes a plurality of first permanent magnets having a first predetermined thickness and a plurality of second permanent magnets having a second thickness thinner than the first permanent magnet, And a fixing groove drawn to a predetermined depth toward the inside of the rotor so as to be inserted and fixed is formed to be spaced apart along the circumferential direction of the rotor.

Wherein the permanent magnet has the same thickness and has a first fixing groove that is drawn in a first depth toward the inside of the rotor so as to be able to insert and fix the permanent magnet on the outer circumferential surface of the rotor, And the second fixing groove is formed to be alternately formed along the circumferential direction of the rotor.

And guide grooves are formed between the permanent magnets and the rotation centers of the rotors so as to guide the permanent magnets and the interdigitator to each other.

And the magnetic guide groove is formed in a triangular shape so that the width gradually decreases from the rotation center of the rotor to the edge side of the rotor.

The generator for reducing cogging torque according to the present invention repeatedly changes the distance between the end of the permanent magnet installed on the rotor and the tooth formed on the stator along the circumferential direction, thereby making the gap between the permanent magnet and the teeth uniformly fixed There is an advantage that the cogging torque can be remarkably reduced as compared with the generator of FIG.

In addition, the generator for reducing the cogging torque according to the present invention is advantageous in that the leakage flux can be minimized and the power generation efficiency can be improved by inducing the magnetic flux path of the permanent magnet, that is, the magnetic path to be connected with the magnetic flux path of the permanent magnet on both sides.

1 is a sectional view of a generator for reducing cogging torque according to a first embodiment of the present invention;

2 is a cross-sectional view illustrating a portion of a generator for reducing cogging torque shown in FIG. 1;

3 is a sectional view of a generator for reducing cogging torque according to a second embodiment of the present invention;

4 is a cross-sectional view illustrating a portion of a generator for reducing the cogging torque shown in FIG.

5 is a sectional view of a generator for reducing cogging torque according to a third embodiment of the present invention.

6 is a cross-sectional view illustrating a portion of a generator for reducing cogging torque shown in Fig. 5;

Hereinafter, a generator for reducing cogging torque according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a generator for cogging torque reduction according to a first embodiment of the present invention. Referring to FIGS. 1 and 2, a generator for reducing cogging torque according to a first embodiment of the present invention includes a rotor 100 and a stator 200.

A mounting hole 101 is formed at an inner center of the rotor 100 so that a shaft can be inserted into the mounting hole 101. A plurality of permanent magnets 110 are formed on the peripheral side circumferential surface of the rotor 100 along a circumferential direction at predetermined intervals Are spaced apart.

The rotor 100 is connected to the permanent magnets 110 and the inner center, that is, between the rotation center of the rotor 100 and the surrounding permanent magnets 110 with respect to the permanent magnets 110 on one side, Guide grooves 102 are formed for guiding the magnetic fluxes to the mutual arms.

The magnetic induction groove 102 is formed at a position spaced apart from the rotation center of the rotor 100 and the rear side of the permanent magnet 110 so as to be in a straight line with the permanent magnet 110, Is formed in a triangular shape so that the width gradually decreases from the center of rotation of the rotor 100 toward the edge of the rotor 100 so as to prevent leakage of the generated magnetic flux to the center of rotation of the rotor 100. Preferably, the magnetic guide groove 102 is formed so that the side nearest to the center of rotation of the rotor 100 or the side farthest from the permanent magnet 110 is separated from the permanent magnet 110 by 11.1 mm.

The stator 200 has a hollow portion 211 for accommodating the rotor 100 therein and an inner circumferential surface of the hollow portion 211 facing the outer circumferential surface of the rotor 100, A plurality of teeth 220 protruding toward the outer circumferential surface are formed to be spaced apart from each other along the circumferential direction. A coil (not shown) is wound around the teeth 220 of the stator 200.

The stator 200 includes a cylindrical body 210 having a hollow portion 211 formed therein to be spaced apart from the rotor 100 by a predetermined distance and a cylindrical body 210 protruding toward the center of the stator 200 from the inner peripheral surface of the body 210 A plurality of teeth 220 can be distinguished. The thickness L1 between the inside and the outside of the body 210 may be 18.6 mm and the length L2 of the teeth 220 may be 45.2 mm.

The rotor 100 of the generator for reducing the cogging torque according to the present invention is provided with a first permanent magnet 111 spaced apart from the end of the tooth 220 by a predetermined first distance L3 (for example, 2.4 mm) And a second permanent magnet 112 spaced apart from the end of the tooth 220 by a predetermined second gap L4 (for example, 3.4 mm) are alternately disposed along the circumferential surface of the rotor 100 do.

The first permanent magnet 111 is formed thicker than the second permanent magnet 112. For example, the thickness of the first permanent magnet 111 may be 9 mm, and the thickness of the second permanent magnet 112 may be 8 mm. Here, the thickness of the first permanent magnet 111 and the second permanent magnet 112 is the length between the N-pole end and the S-pole end of each permanent magnet 110.

Each of the permanent magnets 110 is installed and fixed at one side end, that is, a pole of either the N pole or the S pole is in contact with the circumferential surface of the rotor 100.

The first permanent magnets 111 are thicker than the second permanent magnets 112 and protrude more in the radial direction of the rotor 100 than the second permanent magnets 112 when installed on the circumferential surface of the rotor 100, Accordingly, the gap between the second permanent magnet 112 and the tooth 220 is narrowed at a first interval. In contrast, the second permanent magnets 112 are thinner than the first permanent magnets 111 and are spaced apart from the teeth 220 by a second interval that is longer than the first interval.

The generator for reducing the cogging torque according to the present invention as described above is configured such that the first permanent magnets 111 which are part of the permanent magnets 110 installed in the rotor 100 maintain a first gap with the teeth 220, Since the second permanent magnets 112 which are a part of the rotor 200 maintain a second gap from the teeth 220 and the first permanent magnets 111 and the second permanent magnets 112 are arranged alternately in the rotor 100, The interval between the permanent magnets 110 and the teeth 220 is wider than that of the permanent magnets 110 when the rotor 100 is rotated with respect to the permanent magnet 200, There is an advantage that the cogging torque can be reduced as compared with the conventional generator structure arranged to maintain the same interval.

3 and 4 show a generator for cogging torque reduction according to a second embodiment of the present invention. 3 and 4, the generator for reducing cogging torque according to the second embodiment of the present invention includes a plurality of permanent magnets 110 spaced apart along the circumferential direction and having a plurality of magnetic guide grooves 102 And a stator 200 in which a plurality of teeth 220 are formed along a circumferential direction on the inner side.

The rotor 100 and the stator 200 described below are the same as those applied and described in the generator for cogging torque reduction according to the first embodiment of the present invention described with reference to Figs. 1 and 2, Is omitted.

The rotor 100 of the generator for reducing the cogging torque according to the present embodiment further includes a fixing groove 120 for inserting and fixing the permanent magnet 110. The fixing grooves 120 are drawn from the outer circumferential surface of the rotor 100 to a predetermined depth toward the center of rotation of the rotor 100 and are formed to be spaced along the circumferential direction of the rotor 100.

The permanent magnet 110 inserted and fixed in the fixing groove 120 of the rotor 100 includes a plurality of first permanent magnets 111 having a first predetermined thickness and a plurality of first permanent magnets 111 And a plurality of second permanent magnets 112 having a second thin thickness. The first permanent magnet 111 and the second permanent magnet 112 are alternately inserted and fixed in the fixing groove 120, respectively.

The first permanent magnet 111 is thicker than the second permanent magnet 112 and protrudes more toward the teeth 220 of the stator 200 than the second

permanent magnet

112, 112 are formed to be thinner than the first permanent magnets 111 and protrude less toward the teeth 220 of the stator 200 than the first permanent magnets 111.

5 and 6 illustrate a generator for cogging torque reduction according to a third embodiment of the present invention. 5 and 6, a generator for reducing cogging torque according to a third embodiment of the present invention includes a plurality of permanent magnet magnets 113 spaced apart along a circumferential direction and having a plurality of magnetic guide grooves 102 And a stator 200 in which a plurality of teeth 220 are formed along a circumferential direction on the inner side.

The rotor 100 of the generator for reducing the cogging torque according to the present embodiment further includes a first fixing groove 121 and a second fixing groove 122 so that the permanent magnet 113 can be inserted and fixed.

The first fixing groove 121 and the second fixing groove 122 are alternately formed in the circumferential direction of the rotor 100 and the first fixing groove 121 is formed in a shape that can insert and fix the permanent magnet 113 And the second fixing groove 122 is extended from the circumferential surface of the rotor 100 toward the first depth set toward the center of rotation of the rotor 100, And the second depth is set toward the center of rotation. At this time, the second depth is set deeper than the first depth.

The permanent magnet 113 inserted into and fixed to the first fixing groove 121 and the second fixing groove 122 of the rotor 100 may be replaced with a cogging torque according to the first and second embodiments of the present invention, A generator having the same thickness as the generator for reduction is applied.

The generator for reducing the cogging torque according to the present embodiment is formed such that all of the permanent magnets 113 have the same thickness but the first fixing groove 121 and the second fixing groove 122 are formed to have the same thickness, The permanent magnets 113 inserted and fixed in the first fixing groove 121 are spaced apart from the teeth 220 of the stator 200 by a first distance and the permanent magnets 113 inserted and fixed in the second fixing groove 122 are fixed to the stator 200 Spaced apart from the teeth 220 at a second interval that is wider than the first interval.

That is, in order to fix the permanent magnet 113 having the same thickness, the generator for reducing the cogging torque according to the present embodiment has a different depth of the stator 200 formed on the rotor 100, so that the permanent magnets 111 1 to 4 shown in Figs. 1 to 4 having a structure in which the interval between the teeth 112 and the teeth 220 is relatively narrowed and lengthened or elongated and narrowed along the circumferential direction of the rotor 100, A structure similar to that of the generator for cogging torque reduction according to the first and second embodiments of the present invention can be realized.

As described above, the generator for reducing the cogging torque according to the present invention has been described with reference to the accompanying drawings. However, those skilled in the art will appreciate that various modifications and equivalent implementations You will understand that an example is possible. Accordingly, the true scope of protection of the present invention should be determined only by the technical idea of the appended claims.

Claims

A rotor formed in a cylindrical shape and having a plurality of permanent magnets spaced apart from each other along a circumferential direction at a peripheral side;

A plurality of teeth protruding toward the outer circumferential surface of the rotor are formed on the inner circumferential surface of the hollow portion facing the outer circumferential surface of the rotor at predetermined intervals along the circumferential direction, And a stator having a coil wound around the tooth,

Wherein the rotor has a permanent magnet disposed to be spaced apart from the end of the tooth by a predetermined first distance and a permanent magnet spaced apart from the end of the tooth by a predetermined second interval alternately, Generator.
The method according to claim 1,

Wherein the permanent magnet includes a plurality of first permanent magnets having a first predetermined thickness and a plurality of second permanent magnets having a second thickness thinner than the first permanent magnet,

Wherein the permanent magnet is fixed to a circumferential surface of the rotor.
The method according to claim 1,

Wherein the permanent magnet includes a plurality of first permanent magnets having a first predetermined thickness and a plurality of second permanent magnets having a second thickness thinner than the first permanent magnet,

Wherein a fixing groove, which is drawn in a predetermined depth toward the inside of the rotor, is formed on the outer circumferential surface of the rotor so as to be spaced along the circumferential direction of the rotor so that the permanent magnet can be inserted and fixed. Generator.
The method according to claim 1,

The permanent magnets have the same thickness,

A first fixing groove which is drawn to a first depth set toward the inside of the rotor so as to insert and fix the permanent magnet on the outer circumferential surface of the rotor; And the second fixing groove is alternately formed along the circumferential direction of the rotor.
The method according to claim 1,

And an induction groove is formed between the permanent magnet and the rotation center of the rotor so as to guide the permanent magnet and the interdigitator to each other.
6. The method of claim 5,

Wherein the magnetic guide groove is formed in a triangular shape such that the width gradually decreases from the rotation center of the rotor to the edge side of the rotor.