KR20150034348A - Axially aligned stator for reducing noise and vibration and Electric motor having the same - Google Patents

Abstract

According to an embodiment of the present invention, there is provided a magnet rotor comprising: a first rotor core in which magnets of a first plurality are arranged and attached at regular intervals; And a second rotor core in which magnets of a second plurality of magnets are disposed at regular intervals so as to be twisted at a specific skew angle with the first plurality of magnets.
According to the present invention, the spatial harmonics are reduced to reduce the cogging torque and the torque ripple, which is the most effective way to reduce the motor noise / vibration, and also the fundamental wave component of the counter electromotive force increases to increase the output.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial rotor for reducing noise and vibration, and an electric motor having the same.

The present invention relates to an electric motor, and more particularly, to a rotor having improved noise and / or vibration by applying a skew in the axial direction.

The present invention also relates to an electric motor having such a motor rotor.

The motor generates force by the force of the permanent magnet and the force of the stator current through the interaction. Torque is the driving force for generating driving force and is the cause of motor noise / vibration.

There are many causes of motor noise / vibration, but the most important contributing factor is the electromagnetic excitation force. The excitation force is divided into a radial force and a tangential force. The tangential force is a force for generating a torque and a force not related to a radial force torque.

Both of these forces are sources of noise and / or vibration. Another cause is torque ripple and cogging torque. Torque ripple is caused by spatial harmonics and time harmonics, which is caused by non-linear characteristics of each part of the motor when loaded and the current applied to the motor is not sinusoidal.

Cogging torque is an inherent characteristic of a permanent magnet motor. It is a torque generated when a force by a permanent magnet is applied to a stator in a direction in which energy is minimum.

Such motor noise / vibration adversely affects the system. Noise / vibration in the drive motor generates a joint that people do not like to hear. In addition, in the case of a motor for MDPS (Motor Driven Power Steering), the vibration generated by the motor is transmitted to the driver's handle as it is, so the driver easily senses the vibration even in a slight vibration and makes the driver uncomfortable.

In addition, the existing inverter does not have external noise such as vibration, but when the product is developed by integrating the motor and the inverter, the vibration from the motor is directly transmitted to the inverter, which adversely affects the inverter.

There are various ways to solve this noise / vibration, but the most obvious solution is to skew the rotor or stator. These skewing methods include a rotor skew method and a stator skew method.

Generally, because the coil is wound on the stator, it skews the rotor and solves the problem of motor noise / vibration. The rotor skew can be applied in various ways such as skew skew, V skew, and W skew.

In the case of the stator skew, the winding operation is not easy and the mass productivity is lowered. The normal skew angle is about one pitch angle of the slot.

However, in the case of AFPM (Axial Flux Permanent Magnet), it is impossible to apply a skew to the rotor, so there is a limitation in designing to reduce noise / vibration. In other words, even if a permanent magnet is skewed, the angle at which the skew can be imparted is limited, and skew is not applied when viewed from the air gap even if the skew is applied.

1. Korean Published Patent No. 10-2011-0008749 2. Korean Patent No. 10-1240591

The present invention has been proposed in order to solve the problem of the above-mentioned background art, and it is an object of the present invention to provide an axial rotor for reducing noise and vibration and an electric motor having the same, which can obtain a skew effect even in the structure of an AFPM (Axial Flux Permanent Magnet) There are other purposes to provide.

It is a further object of the present invention to provide an axial rotor and an electric motor having the same, which considerably reduce the torque ripple which causes actual noise / vibration.

In order to accomplish the above-described problems, the present invention provides an axial rotor for noise and vibration reduction that can achieve the effect of skew in the structure of an AFPM (Axial Flux Permanent Magnet).

Wherein the axial rotor comprises:

A first rotor core in which magnets of a first plurality are arranged and attached at regular intervals; And

And a second rotor core in which a plurality of magnets of the second plurality are disposed at predetermined intervals so as to be twisted at a specific skew angle with the first plurality of magnets.

Here, the first and second plurality of magnets may be AFPM (Axial Flux Permanent Magnet).

The poles of the first plurality of magnets and the poles of the second plurality of magnets may face the same poles.

The first and second rotor cores may have a flat donut shape.

In addition, if the first and second plurality of magnets are respectively four, the angle of one of the magnets is fixed, and the angle of the remaining three magnets is divided.

On the other hand, another embodiment of the present invention relates to an axial rotor as described above; A stator core positioned between the first rotor core and the second rotor core; And a coil wound around the stator core; The present invention provides an electric motor having an axial rotor.

According to the present invention, the spatial harmonics are reduced to reduce the cogging torque and the torque ripple, which is the most effective way to reduce the motor noise / vibration, and also the fundamental wave component of the counter electromotive force increases to increase the output.

As another effect of the present invention, when skew is applied to a general motor rotor, it takes a lot of time and cost to accumulate electric steel plates having the same shape by a certain angle. However, in the present invention, And the additional time and cost are not incurred because it is changed.

1 is an assembled view of an electric motor having an axial rotor for noise and vibration reduction according to an embodiment of the present invention.
2 is a view showing an example in which skew is applied to the permanent magnets 30 and 40 shown in FIG.
3 is a partial perspective view showing a state where the skew-applied permanent magnets 30 and 40 shown in FIG. 1 are assembled to the coil 20. FIG.
FIG. 4 is a graph comparing the counter electromotive force according to an embodiment of the present invention with the total harmonic distortion (THD) of a general structure.
5 is a graph comparing the torque ripple rate according to an embodiment of the present invention with the torque ripple rate of a general structure.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be construed as ideal or overly formal in meaning unless explicitly defined in the present application Should not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an axial rotor for reducing noise and vibration according to an embodiment of the present invention and an electric motor having the same will be described in detail with reference to the accompanying drawings.

1 is an assembled view of an electric motor having an axial rotor for noise and vibration reduction according to an embodiment of the present invention. 1, the electric motor includes a stator core 10, a coil 20 wound around the stator core 10, a first rotor core 50 coupled to a lower end of the stator core 10, A second rotor core 60 coupled to the upper end of the core 10, a first plurality of magnets 30 disposed and attached to the inner surface side of the first rotor core 50, And a second plurality of magnets 40 disposed on the inner surface side of the magnet 40. [

The stator core 10 is composed of twelve slots, but this is only an example for explanation, and it is also possible to constitute more or less than twelve slots.

The first and second plurality of magnets 30 and 40 use permanent magnets of AFPM (Axial Flux Permanent Magnet).

In the case of AFPM, the first and second rotor cores 50 and 60 take a circular shape. In other words, a flat donut shape can be mentioned. In addition, in the case of AFPM, the first and second magnets 30 and 40, which are permanent magnets, are attached to the circular rotor cores 50 and 60.

In FIG. 1, the plurality of magnets 30 and 40 are composed of 10 poles, but the present invention is not limited thereto. Further, there are two rotor cores 50, 60 with the stator core 10 therebetween. That is, the first rotor core 50 is assembled to the lower end of the stator core 10, and the second rotor core 60 is assembled to the upper end of the stator core 10.

The first plurality of magnets 30 attached to the first rotor core 50 and the second plurality of magnets 40 attached to the second rotor core 60 are structured so that the same poles face each other . In other words, the poles of the first plurality of magnets 30 and the poles of the second plurality of magnets 40 are opposed to each other at the same polarity.

FIG. 1 shows the configuration of two 10-pole, 12-slot configurations. That is, the plurality of magnets 30 and 40 are alternately arranged to form 10 poles, and the stator core 10 is composed of 12 slots, and the magnets 30 and 40 of the second plurality The magnet 40 has two stages.

2 is a view showing an example in which skew is applied to the permanent magnets 30 and 40 shown in FIG. Referring to FIG. 2, the first plurality of magnets 30 and the second plurality of magnets 40 are arranged in two tiers and arranged at regular intervals.

At this time, the first plurality of magnets 30 and the second plurality of magnets 40 are arranged to be twisted by a specific skew angle 250. The first magnet 31 of the first plurality of magnets 30 and the second one 41 of the second plurality of magnets 40 are arranged to face each other as the same pole, 2 magnet 41 is arranged to be twisted by the skew angle 250 from the first magnet 31. [ Of course, other magnets are arranged similarly to the positions of the first magnet 31 and the second magnet 41. [

As shown in Fig. 2, when the upper and lower permanent magnets of the AFPM are twisted, the same effect as that of the general skew application can be obtained. That is, the permanent magnet attached to the lower rotor is twisted and fixed by a certain angle. This structure is quite different from the general skew method, but the effect of reducing spatial harmonics is the same.

In addition, since a general motor needs to be stacked while twisting the rotor core by a certain skew angle to provide skew, additional time and cost are incurred. However, the structure shown in Fig. 2 does not require additional time and / or cost because only the position of attachment of the permanent magnet is changed.

As another embodiment, if the upper and lower permanent magnets of the AFPM are four, the same effect can be obtained by fixing the angle to one permanent magnet and dividing the angles of the remaining three permanent magnets.

3 is a partial perspective view showing a state where the skew-applied permanent magnets 30 and 40 shown in FIG. 1 are assembled to the coil 20. FIG. Referring to FIG. 3, skew is given to about 3 deg.

FIG. 4 is a graph comparing the counter electromotive force according to an embodiment of the present invention with the total harmonic distortion (THD) of a general structure. Referring to FIG. 4, the conventional structure has a skew angle (0 deg), which indicates a back electromotive force (EMF) distortion of 1.84%. In contrast, the back electromotive force THD according to an embodiment of the present invention is 1.03%. Therefore, the torque ripple rate is improved to 44%.

5 is a graph comparing the torque ripple rate according to an embodiment of the present invention with the torque ripple rate of a general structure. Referring to FIG. 5, the conventional general inventive concept shows a torque ripple ratio of 3.1%. In contrast, the torque ripple rate according to an embodiment of the present invention is 2.27%. Therefore, the torque ripple rate is improved to 27%.

10:
20: Coil
30: the first plurality of magnets
40: the second plurality of magnets
50: first electromagnetic coil
60: second electromagnetic coil
25: Skew angle
31: first magnet
41: second magnet

Claims (6)

A first rotor core in which magnets of a first plurality are arranged and attached at regular intervals; And
A second rotor core in which a plurality of magnets of the second plurality are arranged and attached at regular intervals so as to be twisted at a specific skew angle with the first plurality of magnets;
And an axial rotor for noise and vibration reduction.
The method according to claim 1,
Wherein the first and second plurality of magnets are AFPM (Axial Flux Permanent Magnet).
3. The method of claim 2,
Wherein the poles of the first plurality of magnets and the poles of the second plurality of magnets face each other at the same poles.
The method according to claim 1,
Wherein the first and second rotor cores are flat donut-shaped.
The method according to claim 1,
Wherein when the first and second plurality of magnets are respectively four, the angles of one of the magnets are fixed and the angles of the remaining three magnets are divided.
An axial rotor according to any one of claims 1 to 5;
A stator core positioned between the first rotor core and the second rotor core; And
A coil wound around the stator core;
And an axial rotor.

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