KR20150091451A - Permanent magnet motor - Google Patents

Abstract

A permanent magnet motor according to an embodiment of the present invention includes: a rotor which includes a rotor core which is rotatable around a shaft and a permanent magnet which is combined on the surface of the rotor core, and a stator which is formed to surround the rotor and has a winding. The permanent magnet is formed to have a half cycle of a sine wave and has a symmetrical shape to reduce a width thereof gradually in both end directions from the center. According to the embodiment of the present invention, magnetic flux and a counter electromotive force generated from the permanent magnet have sing waves by implementing the shape of the permanent magnet attached on the surface of the rotor with the sine wave. Accordingly, cogging torque and torque ripple which are the causes of a noise and a vibration and make speed control hard are reduced.

Description

[0001] Permanent magnet motor [0002]

A permanent magnet motor is disclosed. More specifically, since the shape of the permanent magnet attached to the surface of the rotor is realized in the form of a sinusoidal wave in a half period region, the magnetic flux and the back electromotive force generated from the permanent magnet can have a sinusoidal shape, A permanent magnet motor capable of reducing torque and torque ripple is disclosed.

Permanent magnet synchronous motor is a synchronous motor using a permanent magnet in a field. It is relatively high efficiency compared with other motors, and it is easy to repair. Moreover, since there is no temperature increase due to field loss, There is an advantage that the protection is not necessary.

Permanent Magnet Motors Permanent Magnet Surface Mount Type Brushless DC Motors are electric motors that use magnetic torque generated by the interaction of permanent magnet and stator current and can be applied to domestic and industrial motors that require speed change and high performance .

However, such conventional permanent magnet surface-mounted type electric motors are limited in that high cogging torque and torque ripple occur because the counter electromotive force generated from the permanent magnet has a square wave as shown in Fig. The cogging torque and torque ripple of the motor are the main causes of noise and vibration, but control is not easy.

In order to minimize the cogging torque and torque ripple, the current waveform control through the drive and the application of the distribution winding method have been considered. However, there is a problem that the motor size increases and the winding method becomes complicated.

Therefore, it is required to develop a permanent magnet motor capable of generating a back electromotive force of a sinusoidal wave with a simple structure.

It is an object of the present invention to provide a permanent magnet which has a shape of a permanent magnet attached to a surface of a rotor in the form of a sinusoidal wave so that a magnetic flux and a back electromotive force generated from the permanent magnet can have a sinusoidal shape, And to reduce the cogging torque and the torque ripple which makes the speed control difficult, and to provide a permanent magnet motor.

It is another object of the present invention to provide a permanent magnet motor in which the volume of the permanent magnet can be reduced and the manufacturing cost can be reduced by providing the permanent magnet in the form of a sinusoidal wave.

A permanent magnet motor according to an embodiment of the present invention includes a rotor having a rotor core that is rotatable about a shaft and a permanent magnet coupled to a surface of the rotor core; And a stator provided to surround the rotor and having a winding, wherein the permanent magnet has a symmetrical shape having a shape of a half period region of a sinusoidal wave and whose width decreases toward both ends with respect to the center, By this configuration, the shape of the permanent magnet attached to the surface of the rotor is realized in the form of a sinusoidal wave, so that the magnetic flux and the back electromotive force generated from the permanent magnet can also have a sinusoidal shape, which causes noise and vibration, It is possible to reduce the cogging torque and the torque ripple which make it difficult.

According to one aspect of the present invention, an N pole and an S pole of the permanent magnet are alternately disposed on an outer surface of the rotor core, and the N pole and the S pole of the permanent magnet are respectively arranged in a height direction, Wherein the width of the unit permanent magnets located in the middle of the plurality of unit permanent magnets is the largest, and the width of the unit permanent magnets is gradually decreased from the unit permanent magnets located in the center toward both ends, The N pole and the S pole may have a sine wave shape.

According to one aspect of the present invention, the N pole and the S pole of the permanent magnet are alternately disposed on the outer surface of the rotor core, and the N pole and the S pole of the permanent magnet are respectively shaped like an upper end symmetric with respect to a virtual center, And the lower ends thereof are each provided in an isosceles trapezoidal shape so as to have a sine wave shape.

According to one aspect of the present invention, the N pole and the S pole of the permanent magnet are each formed to have a width of three times the width of the upper and lower ends of the permanent magnet, and the N pole and the S pole The N and S poles corresponding to the N and S poles of the permanent magnet can be manufactured.

According to one aspect of the present invention, the N pole and the S pole of the permanent magnet may be provided in the same shape and may be alternately coupled to the outer surface of the rotor core.

According to an aspect of the present invention, each of the N and S poles of the permanent magnets is provided in alternation with each other, and the stator may have six slots in which the windings are respectively disposed.

According to one aspect, the N pole and the S pole of the permanent magnet can be integrally manufactured so that a plurality of unit permanent magnets individually manufactured are laminated in the height direction or have a sine wave shape in a half period region.

According to one aspect, the N pole S poles of the permanent magnets arranged alternately may be spaced apart from the outer surface of the rotor core.

According to the embodiment of the present invention, since the shape of the permanent magnet attached to the surface of the rotor is realized in the form of a sinusoidal wave, the magnetic flux and the back electromotive force generated from the permanent magnet can have a sinusoidal shape, It is possible to reduce cogging torque and torque ripple which makes control difficult.

In addition, according to the embodiment of the present invention, since the permanent magnets are provided in the form of a sinusoidal wave, the volume of the permanent magnets can be reduced as compared with the prior art, thereby reducing the manufacturing cost.

1 is a schematic view illustrating a counter electromotive force of a permanent magnet motor according to an embodiment of the present invention.
2 is a perspective view of a permanent magnet motor according to an embodiment of the present invention.
FIG. 3 is a plan view of the permanent magnet coupled to the outer surface of the rotor core shown in FIG. 2. FIG.
4 is a diagram schematically showing the counter electromotive force of the permanent magnet motor of FIG.
FIG. 5 is a graph comparing changes in back electromotive force according to a rotation angle of a permanent magnet motor according to an embodiment of the present invention and a conventional permanent magnet motor according to an embodiment of the present invention.
6 is a graph comparing amplitudes according to harmonics of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor according to a conventional example.
7 is a graph comparing changes in cogging torque according to rotation angles of the permanent magnet motor according to an embodiment of the present invention and the permanent magnet motor according to the related art.
8 is a graph comparing changes in electromagnetic torque according to a rotation angle of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor according to a conventional example.
9 is a perspective view of a permanent magnet coupled to an outer surface of a rotor core according to another embodiment of the present invention.
FIG. 10 is a view schematically showing a manufacturing process of the permanent magnet shown in FIG.

Hereinafter, configurations and applications according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION The following description is one of many aspects of the claimed invention and the following description forms part of a detailed description of the present invention.

In the following description, well-known functions or constructions are not described in detail for the sake of clarity and conciseness.

FIG. 2 is a perspective view of a permanent magnet motor according to an embodiment of the present invention, and FIG. 3 is a plan view of a permanent magnet coupled to an outer surface of the rotor core shown in FIG.

As shown in these drawings, a permanent magnet motor 100 according to an embodiment of the present invention is a permanent magnet surface-mounted brushless DC motor. The permanent magnet motor 100 includes a rotor 130 having a structure in which a permanent magnet 130 is attached to a surface And a stator 150 having a plurality of slots 155 on which windings (not shown) that electromagnetically interact with the permanent magnets 130 are mounted.

First, the rotor 110 of the present embodiment includes a shaft (not shown) forming a rotation center, a rotor core (not shown) having a hole 111 formed at the center thereof, And a plurality of permanent magnets 130 attached to the surface of the rotor core 115 and bonded to the surface of the rotor core 115.

The permanent magnets 130 coupled to the rotor core 115 are formed of N poles 131 and S poles 135. These poles are formed in a sinusoidal shape in the half period region, And the counter electromotive force can be made to have a sinusoidal form, thereby reducing the cogging torque and torque ripple, which cause noise and vibration of the permanent magnet motor 100. The specific configuration of the permanent magnet 130 will be described later in detail.

2, the stator 150 includes a stator core 151 that surrounds the rotor 110, six stator cores 151 that form a space in the stator core 151, And may have slots 155 in which windings that electromagnetically interact with magnets 130 are disposed, respectively.

When current is applied to the winding of the stator 150 having such a configuration, mutual electromagnetic action with respect to the permanent magnet 130 is generated, so that the rotor 110 can rotate relative to the stator 150.

However, in order to generate a desired torque at this time, the air gap magnetic flux density must be good. To this end, the magnetic flux generated from the permanent magnet 130 must have a sinusoidal shape instead of a square wave, To reduce torque and torque ripple, the back electromotive force must also have a sinusoidal shape, not a square wave.

However, as described above, in the conventional case, a high cogging torque and torque ripple are generated because of the back electromotive force of a square wave, so that noise and vibration are generated.

In order to solve these problems, the permanent magnet motor 100 of the present embodiment includes a permanent magnet 130 having a sine wave shape in a half period so as to generate a sine wave magnetic flux and counter electromotive force.

Referring to FIG. 3, the N pole 131 and the S pole 135 of the permanent magnet 130 of this embodiment have a sine wave shape in a half period region for generating a sine wave magnetic flux and a sinusoidal wave counter electromotive force. More specifically, the N pole 131 and the S pole 135 have a shape in which the width becomes narrower stepwise from the center toward both sides. Therefore, the magnetic flux from the permanent magnet 130 generated when current flows through the stator 150 can have a sinusoidal waveform, and the back electromotive force can also have a sinusoidal waveform.

The N poles 131 and the S poles 135 of the permanent magnets of the present embodiment may be provided at two positions and may be alternately attached to the surface of the rotor core 115.

The N poles 131 and the S poles 135 of the permanent magnets have a height corresponding to the height of the rotor core 115 and may have a laminated structure. For example, the N pole 131 includes a plurality of unit permanent magnets 131a through 131g, and the unit permanent magnets 131a through 131g have different widths.

3, the unit permanent magnet 131a located at the center of the N pole 131, that is, the first unit permanent magnet 131a has the largest width as compared with the unit permanent magnets 131b through 131g, The unit permanent magnets 131b to 131g are stacked on both sides of the first unit permanent magnet 131a. The second unit permanent magnets 131b having a width shorter than that of the first unit permanent magnets 131a are stacked symmetrically with respect to the first unit permanent magnets 131a on both sides of the first unit permanent magnets 131a And a third unit permanent magnet 131c having a width shorter than that of the second unit permanent magnet 131b may be disposed on the outer surface of the second unit permanent magnet 131b. The fourth through seventh unit permanent magnets 131d through 131g may be stacked in this stacked structure. That is, a total of 13 unit permanent magnets 131a to 131g may be stacked in a symmetrical shape with respect to the center as shown in FIGS.

However, the number of unit permanent magnets of the N pole 131 and the S pole 135 to be described later is not limited to thirteen, and it is natural that the number of unit permanent magnets may be more or less.

Meanwhile, the S poles 135 may have the same lamination structure as the N poles 131, and may have a plurality of unit permanent magnets 135a through 135g corresponding to each other.

 Here, a plurality of unit permanent magnets 131a to 131g, 135a to 135g forming the N pole 131 and the S pole 135 are individually manufactured, and the N pole 131 and the S pole 135 are formed by lamination . However, the present invention is not limited thereto, and the N pole 131 and the S pole 135 may be integrally formed.

Since the permanent magnet 130 having the N poles 131 and the S poles 135 is formed to have a sinusoidal shape in the half period region as a whole, the magnetic flux and the back electromotive force can also have a sinusoidal shape, There is an advantage that the cogging torque and torque ripple can be reduced.

Hereinafter, an experiment for comparing the performance of a permanent magnet motor according to an embodiment of the present invention and a conventional permanent magnet motor will be described with reference to Table 1 and FIGS. 4 to 8. FIG.

Table 1 is a table comparing the design parameters of the conventional permanent magnet motor, the permanent magnet motor of the embodiment of the present invention and other embodiments.

[Table 1]

As shown in the above table, the permanent magnet motor according to the embodiment of the present invention has the same design variables as those of the conventional permanent magnet motor, such as the size of the stator and the rotor, but the volume of the permanent magnet is reduced by about 30.8%. In addition, the conventional permanent magnet motor has a square wave permanent magnet, whereas the permanent magnet motor of the present embodiment has a sinusoidal permanent magnet. As a result, it is possible to reduce the cost of manufacturing permanent magnets and suppress noise and vibration due to the sinusoidal permanent magnet.

Meanwhile, FIG. 5 is a graph comparing changes in back electromotive force according to the rotation angle of the permanent magnet motor according to an embodiment of the present invention and the permanent magnet motor according to the related art.

As shown in the figure, a conventional permanent magnet motor has a graph of a back electromotive force close to a square wave, whereas a permanent magnet motor according to embodiments of the present invention has a graph of a back electromotive force close to a sinusoidal wave. In other words, the conventional permanent magnet motor has a back electromotive force of 99 Vrms in the form of a square wave, whereas the permanent magnet motor of this embodiment has a back electromotive force of 99 Vrms which is equal to the back electromotive force value of the conventional permanent magnet motor by increasing the number of turns. It can be seen that the embodiment and the conventional permanent magnet motor can be easily compared, and the distortion of the counter electromotive force waveform of the permanent magnet motor of this embodiment is very small at the tail of the waveform due to the lamination structure of the permanent magnets. In other words, torque ripple and cogging torque can be minimized, thereby reducing the noise and vibration that can be generated from the motor.

Meanwhile, FIG. 6 is a graph comparing amplitudes according to harmonics of the permanent magnet motor according to an embodiment of the present invention and the permanent magnet motor according to the conventional example.

Accordingly, although the counter electromotive force of the conventional permanent magnet motor includes a very high harmonic element, the permanent magnet motor of the present embodiment has several harmonic elements, but it can be confirmed that the waveform is close to the sinusoidal waveform.

Meanwhile, FIG. 7 is a graph comparing changes in cogging torque according to rotation angles of the permanent magnet motor according to an embodiment of the present invention and the conventional permanent magnet motor according to an embodiment of the present invention.

As shown in the figure, the conventional permanent magnet motor has a high cogging torque of 0.12 Nm at most, but the cogging torque of the permanent magnet motor of this embodiment has a value of 0.011 Nm, It can be seen that the torque reduction is achieved.

Meanwhile, FIG. 8 is a graph comparing changes in electromagnetic torque according to rotation angles of the permanent magnet motor according to an embodiment of the present invention and the permanent magnet motor according to the related art.

As shown in the figure, the conventional permanent magnet motor includes a high torque ripple and has an average electromagnetic torque of 0.638 Nm, whereas the permanent magnet motor of the present embodiment has a sinusoidal shape of the permanent magnet, and the torque ripple is reduced by 74.5% And the average electromagnetic torque can be maintained at a level of 0.656 Nm. It can also be seen that the torque of the rotor volume of the present embodiment is increased by 12% from 0.0068 N-m / cm3 to 0.0076 N-m / cm3 as compared with the conventional permanent magnet motor.

Although not shown, the N pole and the S pole of the permanent magnet of this embodiment can be coupled to the outer surface of the rotor core so as to be spaced apart from each other. More precisely, the N pole and the S pole can be attached to the outer surface of the rotor core such that the gap between the first unit permanent magnets of the N poles and the S poles spreads. By the spacing structure of the permanent magnets, the sinusoidal shape of the counter electromotive force can be more easily realized, and torque pulsation, which causes vibration and noise of the permanent magnet motor, can be reduced. Further, the output (TRV) per unit volume and the increase in efficiency can be expected.

Hereinafter, a permanent magnet motor according to another embodiment of the present invention will be described, but a description of parts that are substantially the same as those of the permanent magnet motor of the above embodiment will be omitted.

FIG. 9 is a perspective view of a permanent magnet coupled to an outer surface of a rotor core according to another embodiment of the present invention, and FIG. 10 is a view schematically illustrating a manufacturing process of the permanent magnet shown in FIG.

9, the rotor 210 of the permanent magnet motor of the present embodiment includes a cylindrical rotor core 215 and a plurality of permanent magnets 230 attached to the surface of the rotor core 215 The shape of the N pole 231 and the S pole 235 of the permanent magnet 230 is different from the above-described embodiment.

The N pole 231 and the S pole 235 of the permanent magnet 230 are symmetrical with respect to the imaginary center 230a so that the upper and lower ends of the N pole 231 and the S pole 235 are symmetrical with respect to the imaginary center 230a, Therefore, cogging torque and torque ripple, which cause noise and vibration of the permanent magnet motor, can be reduced. In addition, the manufacturing can be facilitated and the manufacturing cost can be reduced.

Referring to FIG. 9, for example, there are two rectangular N poles 231a, through which three N poles 231 of the permanent magnet 230 of this embodiment can be manufactured. The width A of the center of the N pole 231 of this embodiment can be set to be three times the width B of the upper and lower ends so that the four corner regions of the two permanent magnets 231a are cut A total of eight right-angled triangular N poles 231b can be obtained.

When this right triangular N pole 231b is coupled in the shape shown in the lower side of FIG. 9, a shape corresponding to the N pole 231 of the present embodiment can be obtained, It can be applied to the surface-attached permanent magnet 230 by attaching it to the outer surface.

As described above, the N pole 231 and the S pole 235 of the permanent magnet 230 of the present embodiment can be easily recycled without being discarded, and thus the manufacturing cost can be remarkably reduced .

Also, as described above, the N pole 231 and the S pole 235 of the permanent magnet 230 of this embodiment have a sinusoidal shape in the half period region, thereby reducing cogging torque and torque ripple. For example, in the case of a conventional permanent magnet motor, the cogging torque can be 0.118 Nm and the torque ripple can have a value of 23.5%. In this embodiment, the cogging torque is 0.014 Nm and the torque ripple has a value of 16.8% It is possible to have significantly lower cogging torque and torque ripple than in the prior art.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

100: permanent magnet motor
110: rotor
130: permanent magnet
131: N pole
131a to 131g: unit permanent magnet
135: S pole
150: stator

Claims (7)

A rotor having a rotor core axially rotatable about a shaft, and a permanent magnet coupled to a surface of the rotor core; And
A stator for winding the rotor and having a winding;
/ RTI >
An N pole and an S pole of the permanent magnet are alternately disposed on the outer surface of the rotor core,
The N-pole and the S-pole of the permanent magnet are, respectively,
And a plurality of unit permanent magnets stacked in a height direction,
Wherein a width of the unit permanent magnet located at the center of the plurality of unit permanent magnets is the largest, and a width of the unit permanent magnet is gradually decreased from the unit permanent magnet located at the center to the both ends, S pole is a sinusoidal wave.
The method according to claim 1,
And the N pole and the S pole of the permanent magnet are provided in the same shape and are alternately coupled to the outer surface of the rotor core.
The method according to claim 1,
Wherein each of the N and S poles of the permanent magnets is provided in alternation with each other, and the stator has six slots in which the windings are respectively disposed.
The method according to claim 1,
Wherein the N permanent magnets and the S permanent magnets are integrally manufactured so that a plurality of unit permanent magnets manufactured individually are stacked in a height direction or have a sine wave shape in a half period region.
The method according to claim 1,
Wherein the N pole S poles of the permanent magnets arranged alternately are spaced apart from the outer surface of the rotor core.
A rotor having a rotor core axially rotatable about a shaft, and a permanent magnet coupled to a surface of the rotor core; And
A stator for winding the rotor and having a winding;
/ RTI >
An N pole and an S pole of the permanent magnet are alternately disposed on the outer surface of the rotor core,
The N-pole and the S-pole of the permanent magnet are, respectively,
Wherein each of the upper and lower ends symmetrically symmetrical with respect to an imaginary center is provided in an isosceles trapezoidal shape so that the permanent magnet motor has a sine wave shape.
The method according to claim 6,
The N pole and the S pole of the permanent magnet are each formed to have a width of three times the width of the upper and lower ends,
A permanent magnet motor for producing N poles and S poles corresponding to N poles and S poles of said permanent magnets by mutually joining portions of rectangular N poles and S poles so as to have the shape of N poles and S poles of said permanent magnets; .

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