KR20190063361A - Motor - Google Patents

Abstract

The present invention provides a motor capable of reducing cogging torque and torque ripples. The motor comprises: a shaft; a rotor including a hole in which the shaft is arranged; a stator arranged on the outside of the rotor; a first coil and a second coil determining the number of poles of the rotor and the number of slots of the stator to generate two counter electromotive force signals having a first phase difference, individually wound on the stator, and individually receiving separate current; and a control unit supplying the current having a different phase difference to the first coil and the second coil.

Description

Motor {Motor}

An embodiment relates to a motor.

An electric steering system (EPS) is a device that enables the driver to drive safely by ensuring the turning stability of the vehicle and providing quick restoring force. Such an electric steering apparatus drives a motor via an electronic control unit (ECU) according to driving conditions sensed by a vehicle speed sensor, a torque angle sensor, a torque sensor, and the like to control the driving of the steering shaft of the vehicle.

The motor includes a stator and a rotor. The stator may include teeth forming a plurality of slots, and the rotor may include a plurality of magnets facing the teeth. Adjacent teeth are spaced apart from each other to form a slot open. During the rotation of the rotor, a cogging torque may be generated due to a difference in magnetic permeability of the stator, which is a metallic material, and the air of a slot opening, which is an empty space. Since this cogging torque causes noise and vibration, it is important to reduce the cogging torque to improve the quality of the motor. In particular, torque ripple may occur at high speed conditions, such torque ripple causing vibration problems of the steering apparatus.

Therefore, an embodiment of the present invention is intended to solve the above problems, and it is an object of the present invention to provide a motor capable of reducing cogging torque and torque ripple while securing torque. The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned here can be understood by those skilled in the art from the following description.

An embodiment includes a rotor including a shaft, a hole in which the shaft is disposed, and a stator disposed on the outer side of the rotor, wherein the number of poles of the rotor and the number of turns of the stator Wherein the number of slots is determined and the stator includes a first coil and a second coil that are separated in a circuit and supplies a current having a different phase difference to each of the first coil and the second coil .

Preferably, the rotor includes a rotor core and a plurality of magnets disposed on an outer circumferential surface of the rotor core, and the plurality of magnets may have only one of an N pole and an S pole.

Preferably, the rotor core is disposed between the magnet and the magnet, and may include a concavo-convex portion protruding radially from the center of the rotor core.

Preferably, the thickness of the concavo-convex portion is equal to or smaller than the thickness of the magnet in the radial direction with respect to the center of the rotor core, and the thickness of the convexo-concave portion in the circumferential direction with respect to the center of the rotor core is equal to Or smaller.

Preferably, the number of the plurality of magnets is 7, the number of the concave-convex portions is 7, the number of slots of the stator is 12 slots, and when the poles of the magnets are N poles, The protrusions may be N poles of the magnet.

Preferably, the number of the plurality of magnets is 5, the number of the concave-convex portions is 5, the number of slots of the stator is 12 slots, and when the poles of the magnet are N poles, the concave-convex portion is an S pole of the magnet, The protrusions may be N poles of the magnet.

Preferably, the control unit may supply a current having a phase difference equal to the first phase difference to the first coil and the second coil, respectively.

Preferably, the first retardation may be between 20 ° and 40 °.

Preferably, the stator includes a plurality of teeth through which the first coil and the second coil are wound, and a plurality of grooves may be disposed in an end surface of the shoe disposed on the teeth.

Preferably, the plurality of grooves may be disposed symmetrically with respect to a center line passing through the center of width of the tooth and the center of the stator.

Preferably, the plurality of grooves may extend from the upper end to the lower end of the stator.

According to the embodiment, there is provided an advantageous effect of reducing the cogging torque and torque ripple while securing the maximum torque.

1 shows a motor according to an embodiment,
2 is a view showing a stator and a rotor,
3 is a view showing magnitudes of a magnet and a concavo-convex portion of the rotor,
4 is a view showing grooves of teeth of a stator,
5 is a graph showing a counter electromotive force signal having a different phase difference,
6 is a view showing a stator in which a first coil and a second coil are wound,
7 is a graph comparing the torque of the comparative example with the torque of the embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages, and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The terms including ordinal, such as second, first, etc., may be used to describe various elements, but the elements are not limited to these 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 second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

1 is a view showing a motor according to an embodiment.

Referring to FIG. 1, a motor according to an embodiment may include a shaft 100, a rotor 200, and a stator 300.

The shaft 100 may be coupled to the rotor 200. When an electromagnetic interaction occurs between the rotor 200 and the stator 300 through the current supply, the rotor 200 rotates and the shaft 100 rotates in conjunction therewith. The shaft 100 may be connected to the steering shaft of the vehicle to transmit power to the steering shaft. The shaft 100 may be supported by bearings.

The rotor (200) rotates through electrical interaction with the stator (300). The rotor 200 is disposed inside the stator 300. The rotor 200 may include a rotor core and a magnet coupled to the rotor core. The rotor 200 can be classified into the following types according to the coupling method of the rotor core and the magnet.

The rotor 200 may be realized as a type in which the magnet is coupled to the outer circumferential surface of the rotor core. This type of rotor can be coupled to the rotor core by a separate can member to prevent disengagement of the magnet and increase the coupling force. Or the magnet and the rotor core may be integrally formed by double injection.

Meanwhile, the rotor core may be formed by laminating a plurality of plates in the form of a thin steel plate. Alternatively, the rotor core may be implemented in a single bar shape so as not to form a skew angle, and the magnet may be attached to the rotor core so as not to form a skew angle. Meanwhile, the rotor core may be formed by stacking a plurality of pucks (unit cores) forming a skew angle.

The stator 300 may be disposed outside the rotor 200. The stator 300 induces electrical interaction with the rotor 200 to induce rotation of the rotor 200.

The bus bar 400 may be disposed on the stator 300. The bus bar 400 may include a terminal within the bus bar body. The terminal of the bus bar 400 may include a neutral terminal electrically connecting the upper terminal and the upper terminal connected to the power sources of the U, V, and W phases. The terminal of the bus bar 400 is connected to a coil wound around the stator 300.

The housing 500 can house the rotor 200 and the stator 300 therein.

The rotor position sensing device 600 is coupled to the shaft 100 to interlock with the rotor 200 to detect the position of the rotor 200. The rotor position sensing device 600 may include a sensing magnet and a sensing plate. The sensing magnet and the sensing plate may be coupled so as to have a coaxiality. The sensing magnet may include a main magnet disposed in the circumferential direction adjacent to the hole forming the inner peripheral surface and a sub magnet formed at the peripheral edge. The main magnet may be equally arranged in the circumferential direction so as to correspond to the pole of the magnet inserted in the rotor of the motor in the direction of the rotation axis. The submagnet is divided into more poles than the main magnet. Accordingly, it is possible to measure the rotational angle more finely and measure it, and the driving of the motor can be made more smooth. The sensing plate may be formed of a disc-shaped metal material. A sensing magnet may be coupled to the upper surface of the sensing plate. And the sensing plate may be coupled to the shaft 100. A hole through which the shaft 100 passes is formed in the sensing plate.

A sensor for sensing the magnetic force of the sensing magnet may be disposed on the printed circuit board 700. At this time, the sensor may be a Hall IC. The sensor senses changes in the N and S poles of the main magnet or sub-magnet to generate a sensing signal. The printed circuit board 700 may be mounted on the sensing magnet such that the sensor is coupled to the lower surface of the cover of the housing 500 so that the sensor faces the sensing magnet.

FIG. 2 is a view showing a stator and a rotor of 14 poles and 12 slots as a motor according to the first embodiment. FIG. 3 is a view showing a stator and a rotor of 10 poles and 12 slots, to be.

Referring to FIGS. 2 and 3, the rotor 200 may include a rotor core 210 and a plurality of magnets 220 that are attached to the outer circumferential surface of the rotor core 210. The plurality of magnets 220 may be spaced apart from each other at a predetermined interval in the circumferential direction with respect to the center C of the rotor core 210. At this time, the plurality of magnets 220 may have a polarity of one of an N pole and an S pole. For example, the plurality of magnets 220 may all have N-pole magnetism.

The protrusions 211 may be disposed on the outer circumferential surface of the rotor core 210. The concave and convex portion 211 is disposed between the magnet 220 and the magnet 220 to serve as an S pole. The protrusions 211 may protrude from the outer circumferential surface of the rotor core 210 in the radial direction with respect to the center C of the rotor core 210.

As the motor according to the first embodiment, seven magnets 220 may be disposed. In addition, seven concave / convex portions 211 may be disposed. Accordingly, the motor according to the embodiment may be a motor having 14 poles. And twelve slots may be provided between the teeth 320 and the teeth 320.

As the motor according to the second embodiment, five magnets 220 may be disposed. In correspondence with this, five concave portions 211 can also be arranged. Accordingly, the motor according to the embodiment may be a motor having 10 poles. And twelve slots may be provided between the teeth 320 and the teeth 320.

3 is a view showing magnitudes of the magnet and the concave-convex portion of the rotor.

Referring to FIG. 3, the uneven portion 211 may correspond to or smaller than the size of the magnet 220.

For example, the width W1 of the concave / convex portion 211 may be equal to or smaller than the width W2 of the magnet 220. [ The width W1 of the concave and convex portion 211 corresponds to the shortest straight line distance or arc length of the inner side ends P1 and P2 of the concave and convex portions 211 in the circumferential direction at the center C of the rotor core 210 can do. The width W2 of the magnet 220 corresponds to the shortest straight line distance or arc length of the inner ends P3 and P4 of the magnet 220 in the circumferential direction at the center C of the rotor core 210 .

The thickness t1 of the concave and convex portions 211 may be equal to or smaller than the thickness t2 of the magnet 220. [ The thickness t1 of the concave and convex portion 211 is the distance from the center of width C 1 of the concave and convex portion 211 to the outside of the concave and convex portion 211 in the radial direction from the center C of the rotor core 210 It may correspond to a straight line distance. The thickness t2 of the magnet 220 refers to the distance from the center C2 of the magnet 220 in the radial direction at the center C of the rotor core 210 to the straight distance from the inside to the outside of the magnet 220 .

This size of the concave and convex portion 211 is determined by considering the space between the magnet 220 and the magnet 220 and the distance between the outside of the concave and convex portion 211 and the stator.

When the unipolar magnet 220 is applied, there is an advantage that the manufacturing cost of the motor is greatly reduced. However, the characteristics of the cogging torque and torque ripple characteristics may be deteriorated due to the difference in polarity energy.

Fig. 4 is a view showing a groove of the tooth of the stator. Fig.

To complement the characteristics of the cogging torque and the characteristics of the torque ripple, it is desirable to form the groove 322 in the stator 300. [

The stator 300 is provided with an annular yoke portion 310 and a tooth 320 protruding from the yoke toward the center may be provided. A coil is wound on the tooth 320. A plurality of teeth 320 may be disposed at regular intervals along the inner circumferential surface of the annular yoke. The number of teeth 320 corresponds to the number of slots of the motor. For example, as shown in the figure, when the number of teeth 320 is 12, the number of slots is 12. A shoe 321 is disposed at an end of the tooth 320. The shoe 321 is disposed such that its end surface faces the magnet 220.

The space between the adjacent teeth 320 and the teeth 320 is formed as a winding space P of the coil. The shoe 321 and the shoe 321 of the adjacent tooth 320 are disposed apart from each other to form a slot opening S. [ The slot opening S is an inlet of the winding space P where the nozzle for winding the coil is inserted.

The inner circumferential surface of the shoe 321 may include a groove 322. The groove 322 may be concave on the inner circumferential surface of the shoe 321. Although the shape of the groove 322 is shown as a square, the present invention is not limited to this. The grooves 322 may be disposed along the axial direction of the stator 300. In other words, the grooves 322 may be long along the height direction of the stator 300 from the upper end to the lower end of the stator 300. Two grooves 322 may be disposed. The two grooves 322 may be symmetrically arranged with respect to a reference line L passing through the center of width of the body 321 of the tooth 320 and the center of the stator 300. [ The grooves 322 correspond to the slot openings S that cause variations in the magnetic flux density, thereby increasing the frequency of the waveform of the cogging torque per unit period and greatly reducing the cogging torque.

5 is a graph showing a counter electromotive force signal with a different phase difference.

Referring to FIG. 5, the motor according to the embodiment may determine that the number of poles of the rotor 200 and the number of slots of the stator 300 are two counter electromotive force signals A and B having a first phase difference. For example, the motor according to the embodiment may be 14 poles and 12 slots. In the case of a motor of 14 poles and 12 slots, as shown in Fig. 5, two counter electromotive force signals having a phase difference of 30 degrees are generated. The torque value of the motor is the product of the counter electromotive force and the current. Therefore, in order to obtain the maximum torque value, the current must be supplied so that the phase of the counter electromotive force becomes equal to the phase of the current. However, as shown in FIG. 5E, when currents of the same phase are supplied to the two counter electromotive force signals, the torque is lost.

In this way, in the motor in which the counter electromotive force having the phase difference is generated, two coils with different currents are wound around the stator 300 in order to reduce cogging torque and torque ripple while securing the torque as much as possible.

6 is a view showing a stator in which a first coil and a second coil are wound.

Referring to FIG. 6, the first coil 330 and the second coil 340, which are separated from each other, can be sensed in the teeth 320 of the stator 300. The controller 800 can supply a current having a different phase difference to the first coil 330 and the second coil 340, respectively. The control unit 800 may be an electronic device mounted on the printed circuit board 700.

The first coil 330 and the second coil 340 may be alternately arranged with respect to the circumferential direction of the stator 300. Specifically, the first coil 330 is wound on one of the teeth 320 of the plurality of teeth 320, and the second coil 340 is wound on the tooth 320 adjacent to the tooth 320.

If the first phase difference of the two counter electromotive force signals is 30 degrees, the control unit 800 can supply a current having a phase difference of 30 degrees to the first coil 330 and the second coil 340, thereby securing the maximum torque .

FIG. 7 is a graph comparing the torque of Comparative Example 1 with that of the first embodiment, and FIG. 2 is a graph comparing the torque of Comparative Example 2 and the torque of the second embodiment.

Comparative Example 1 is a 14 pole, 12 slot motor in which a single coil is wound in a circuit. Comparative Example 2 is a 10 pole 12 slot motor in which a single coil is wound in a circuit.

Referring to FIGS. 7 and 8, in the case of Comparative Example 1 and Comparative Example 2, two counter electromotive force signals having different phases in two coils having different electric angles in the same phase (U phase, V phase, W phase) However, since current of the same phase is supplied to the coil, a loss is generated in the torque. As a result, the comparative example 1 and the comparative example 2 show relatively lower torque than the embodiment. On the other hand, in the case of the first and second embodiments, a current having a phase difference of the phase difference of two counter electromotive force signals is supplied to two coils that are separated in a circuit, so that a maximum torque can be secured without loss of torque have. As a result, the torques of the first embodiment and the second embodiment are higher than those of the comparative example 1 and the comparative example 2, respectively.

The torque ripple Ml of the first embodiment and the torque ripple M3 of the second embodiment are lower than the torque ripple M2 of the first comparative example and the torque ratio M4 of the second comparative example. This is because, when two torques having different phase differences are synthesized, the torque ripple is canceled. As a result, it is possible to secure the effect of reducing the torque ripple while securing the maximum torque.

As we have seen, if you apply a unipolar magnet to a motor, the manufacturing cost can be greatly reduced. There has been a problem that output decrease, cogging torque, and torque ripple increase. In the case of the motor according to the embodiment, the cogging torque is reduced through the groove 322 disposed in the shoe 321, and a current having a phase difference of the phase difference of the counter electromotive force signal is supplied to the two coils respectively, thereby securing the maximum torque And torque ripple at the same time.

As described above, the motor according to one preferred embodiment of the present invention has been specifically described with reference to the accompanying drawings.

It is to be understood that one embodiment of the invention described above is to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description. It is intended that all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

100: Shaft
200: Rotor
210: rotor core
211: concave /
220: Magnet
300:
310: York
320: Tees
321: Shoe
322: Home
400: bus bar
500: housing
600: Rotor position sensing device
700: printed circuit board
800:

Claims (11)

shaft;
A rotor including a hole in which the shaft is disposed;
And a stator disposed outside the rotor,
The number of poles of the rotor and the number of slots of the stator are determined so that two counter electromotive force signals having a first phase difference are generated,
Wherein the stator includes a first coil and a second coil that are separated in a circuit,
And a controller for supplying a current having a different phase difference to each of the first coil and the second coil. The method according to claim 1,
Wherein the rotor includes a rotor core and a plurality of magnets disposed on an outer circumferential surface of the rotor core, and the plurality of magnets have only one of an N pole and an S pole. 3. The method of claim 2,
Wherein the rotor core is disposed between the magnet and the magnet and includes a concavo-convex portion protruding in a radial direction with respect to a center of the rotor core. The method of claim 3,
Wherein the thickness of the concavo-convex portion is equal to or smaller than the thickness of the magnet in the radial direction with respect to the center of the rotor core, and the width of the concave-convex portion in the circumferential direction with respect to the center of the rotor core is equal to or smaller than the width of the magnet . The method of claim 3,
Wherein the number of the plurality of magnets is seven, the number of the concave-convex portions is seven,
The number of slots of the stator is 12 slots,
When the pole of the magnet is an N pole, the concavo-convex portion is an S pole of the magnet,
And when the pole of the magnet is an S pole, the concavo-convex portion is an N pole of the magnet. The method of claim 3,
The number of the plurality of magnets is 5, the number of the concave-convex portions is 5,
The number of slots of the stator is 12 slots,
When the pole of the magnet is an N pole, the concavo-convex portion is an S pole of the magnet,
And when the pole of the magnet is an S pole, the concavo-convex portion is an N pole of the magnet. The method according to claim 5 or 6,
Wherein the controller supplies a current having a phase difference equal to the first phase difference to the first coil and the second coil, respectively. 8. The method of claim 7,
Wherein the first phase difference is 20 DEG to 40 DEG. The method according to claim 1,
Wherein the stator includes a plurality of teeth through which the first coil and the second coil are wound,
And a plurality of grooves are disposed in an end surface of the shoe disposed on the tooth. 10. The method of claim 9,
Wherein the plurality of grooves are arranged symmetrically with respect to a center line passing through the center of width of the tooth and the center line of the stator. 11. The method of claim 10,
And the plurality of grooves extend from an upper end to a lower end of the stator.

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