KR102468303B1 - Stator and motor having the same - Google Patents

Abstract

The present invention is a stator core having a plurality of teeth; It includes a coil wound around the teeth, the teeth include a body around which the coil is wound and a shoe connected to the body, the shoe includes a plurality of grooves, and a center of curvature of an inner circumferential surface of the shoe is the stator Provide a stator equal to the center of the core.

Description

Stator and motor including the same {Stator and motor having the same}

The embodiment relates to a stator and a motor including the same.

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

A 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. At this time, cogging torque may occur due to a difference in air permeability between the metal stator and the slot open, which is an empty space, during the rotation of the rotor. Since this cogging torque causes noise and vibration, reducing the cogging torque is of paramount importance in improving the quality of the motor.

Accordingly, the embodiment is intended to solve the above problems, and an object thereof is to provide a motor capable of reducing cogging torque.

The problems to be solved by the embodiments are not limited to the problems mentioned above, and other problems not mentioned herein will be clearly understood by those skilled in the art from the description below.

An embodiment for achieving the above object includes a stator core having a plurality of teeth and a coil wound on the teeth, wherein the teeth include a body around which the coil is wound and a shoe connected to the body, wherein the The shoe may include a plurality of grooves, and a center of curvature of an inner circumferential surface of the shoe may be the same as a center of the stator core.

Preferably, the number of grooves may be two.

Preferably, the width of the groove based on the circumferential direction of the stator core may be within 90% to 110% of the width of the slot open of the tooth.

The embodiment includes a rotating shaft, a rotor including a hole into which the rotating shaft is inserted, and a stator disposed outside the rotor, wherein the stator includes a stator core having a plurality of teeth and a coil wound on the teeth The tooth includes a body around which the coil is wound and a shoe connected to the body, the shoe includes a plurality of grooves, and a center of curvature of an inner circumferential surface of the shoe is the same as a center of curvature of the stator core. , The rotor includes a cylindrical rotor core and a plurality of magnets disposed surrounding the outer circumferential surface of the rotor core, the magnets having an inner circumferential surface in contact with the outer circumferential surface of the rotor core, the outer circumferential surface of the rotor core When an angle obtained by dividing an angle by the number of magnets is referred to as a first angle, the first and second extension lines extending from both end points of the inner circumferential surface of the magnet to the center point of the rotor core on the cross section of the rotor core and the magnet are formed. A motor having a second angle and a ratio of the second angle to the first angle of 0.92 to 0.95 may be provided.

Preferably, in the rotor, when the radius of curvature of the outer circumferential surface of the magnet is referred to as a first radius and the radius of curvature of the inner circumferential surface of the magnet is referred to as a second radius on a cross section of the rotor core and the magnet, A ratio of the first radius to the second radius may be 0.5 to 0.7.

Preferably, the number of grooves may be two.

Preferably, the two grooves may be symmetrically disposed with respect to a reference line passing through a center of width of the shoe based on a circumferential direction and a center of the stator core.

Preferably, the number of oscillations of the cogging torque waveform during unit rotation may be three times the least common multiple of the number of magnets and the number of teeth.

Preferably, the width of the groove based on the circumferential direction of the stator core may be within 90% to 110% of the width of the slot open of the tooth.

Preferably, the plurality of magnets are disposed in one stage on the outer circumferential surface of the rotor core, and the plurality of magnets may be arranged spaced apart from each other at a predetermined interval.

According to the embodiment, by forming grooves on the teeth of the stator to increase the cogging main order, an advantageous effect of significantly reducing cogging torque is provided.

According to the embodiment, in a 6-pole 9-slot motor, when grooves are arranged on stator teeth, an advantageous effect of preventing a large increase in cogging torque in a state where the cogging main order is “9th order” is provided.

1 is a view showing a motor according to an embodiment;
2 is a view showing a first angle and a second angle;
3 is a view showing a first angle;
4 is a diagram showing a comparison of torque and torque ripple values corresponding to a reduction rate of a magnet width;
5 is a view showing the optimal shape of the outer circumferential surface of the magnet for reducing torque ripple;
6 and 7 are graphs showing torque ripple generated under high-speed rotation conditions;
8 is a table comparing the cogging torque and torque ripple of Comparative Example and the cogging torque and torque ripple of Example;
9 is a graph showing the torque ripple of the motor according to the embodiment in high-speed rotation conditions;
Figure 10 shows the groove of the teeth;
11 is a table showing the cogging main order increased by the motor according to the embodiment;
12 is a diagram showing the width of a groove;
13 is a table showing changes in cogging torque waveforms according to groove widths;
14 is a view showing a shoe whose inner circumferential surface is made of a curved surface;
15 is a drawing comparing the cogging torque of a motor in which the inner circumferential surface of the shoe is flat and the cogging torque of a motor in which the center of curvature of the inner circumferential surface of the shoe coincides with the center of the stator core of the stator core;
16 is a drawing comparing the deviation and output of the cogging torque of the motor in which the inner circumferential surface of the shoe is flat, and the deviation and output of the cogging torque of the motor in which the center of curvature of the inner circumferential surface of the shoe coincides with the center of the stator core,
17 is a diagram illustrating a cogging torque improvement state corresponding to a cogging main order in a motor according to an embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. And, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a view showing a motor according to an embodiment, FIG. 2 is a view showing a first angle and a second angle, and FIG. 3 is a view showing a first angle.

1 to 3 , the motor according to the embodiment may include a rotating shaft 100, a rotor 200, and a stator 300.

The rotating shaft 100 may be coupled to the rotor 200 . When electromagnetic interaction occurs between the rotor 200 and the stator 300 through current supply, the rotor 200 rotates and the rotation shaft 100 rotates in conjunction with this rotation shaft 100 is connected to the steering shaft of the vehicle Power can be transmitted to the steering shaft. The rotating 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 210 and a magnet 220 coupled to the rotor core 210 . The rotor 200 may be implemented in a type in which the magnet 220 is coupled to the outer circumferential surface of the rotor core 210 . In this type of rotor 200, a separate can member 1 may be coupled to the rotor core 210 in order to prevent the magnet 220 from being separated and to increase coupling force. Alternatively, the magnet and the rotor core may be integrally formed by double injection.

The rotor 200 may be implemented in a type in which a magnet is coupled to the inside of a rotor core. This type of rotor may be provided with pockets in the rotor core into which magnets are inserted.

Meanwhile, in the rotor 200, the magnets 220 may be disposed in one stage in the rotor core, which is a single cylindrical unit. Here, the first stage means a structure in which the magnet 220 can be disposed so that there is no skew on the outer circumferential surface of the rotor 200 . Therefore, when the longitudinal cross-section of the rotor core 210 and the longitudinal cross-section of the magnet 220 are referenced, the height of the rotor core 210 and the height of the magnet 220 may be formed to be the same. That is, based on the height direction, the magnet 220 may cover the entire rotor core.

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

The sensing magnet 2 is a device for detecting the position of the rotor 200 by being coupled to the rotating shaft 100 so as to interlock with the rotor 200 . This sensing magnet may include a magnet and a sensing plate. The magnet and the sensing plate may be coaxially coupled. The sensing magnet 2 may include a main magnet disposed in a circumferential direction adjacent to a hole forming an inner circumferential surface and a sub magnet formed at an edge. The main magnet may be arranged identically to the drive magnet inserted into the rotor of the motor. The sub-magnet is more subdivided than the main magnet and consists of many poles. Accordingly, it is possible to divide and measure the rotation angle more minutely, and the driving of the motor can be smoother.

The sensing plate may be formed of a disc-shaped metal material. A sensing magnet may be coupled to an upper surface of the sensing plate. And the sensing plate may be coupled to the shaft. A hole through which a shaft 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 3 . In this case, the sensor may be a Hall IC. The sensor generates a sensing signal by detecting a change in the N pole and S pole of the main magnet or sub magnet. The printed circuit board 3 may be coupled to the lower surface of the cover of the housing and installed on the sensing magnet so that the sensor faces the sensing magnet.

The motor according to the embodiment attempts to reduce cogging torque and torque ripple by increasing the frequency of the cogging torque waveform per unit period by reducing the width of the magnet 220 . A detailed explanation of this is as follows. In describing the embodiment, the width of the magnet 220 may be defined as the length of an arc formed by the inner circumferential surface of the magnet 220 in contact with the rotor core 210 .

Referring to FIGS. 2 and 3 , a plurality of magnets 220 are attached to the outer circumferential surface of the rotor core 210 . Also, the stator 300 may include a plurality of teeth 320 . The magnet 220 and the teeth 320 may be disposed to face each other.

For example, the number of magnets 220 may be 6, and a 6-pole, 9-slot motor having 9 teeth 320 may be provided. The number of teeth 320 corresponds to the number of slots. Also, N poles and S poles of the magnets 220 may be alternately disposed along the circumferential direction of the rotor core 210 .

The inner circumferential surface 211 of the magnet 220 contacts the outer circumferential surface of the rotor core 210 . The width of the magnet 220 of the motor according to the embodiment can be explained through a first angle R1 and a second angle R2.

First, what is the first angle R1? It represents an angle obtained by dividing 360 degrees, which is an angle formed by the outer circumferential surface of the rotor core 210, by the number of magnets 220. For example, when the number of magnets 220 is 6, the first angle R1 is 60 degrees. The length of the arc of the rotor core 210 corresponding to the first angle R1 becomes a criterion for setting the width of the magnet 220. At this time, the width of the actual magnet 220 may be adjusted in consideration of the width of the protrusion formed on the outer circumferential surface of the rotor core 210 to guide the magnet 220 .

Next, the second angle R2 means an angle formed by the first extension line L1 and the second extension line L2. Here, the first extension line L1 means a virtual line extending from one end point of the inner circumferential surface 210 to the center point C of the rotor core 210 on the cross section of the magnet 220 . Here, the cross section of the magnet 220 means a cross section of the magnet 220 cut in a direction perpendicular to the axial direction of the motor.

The length of the arc of the rotor core 210 corresponding to the second angle R2, which is the angle between the first extension line L1 and the second extension line L2, is another criterion for setting the width of the magnet 220.

The first angle R1 is a reference angle for setting the width of the conventional magnet 220, and the second angle R2 is a width smaller than the width of the magnet 220 based on the first angle R1. It is an angle that is a criterion for setting the width of the magnet 220 to have.

4 is a diagram illustrating a comparison between torque and torque ripple values corresponding to a reduction rate of a magnet width.

Referring to FIG. 4 , in the case of a 6-pole 9-slot motor, the ratio of the first angle R1 to the second angle R2 is 0.92 to 0.95 than the reference line B indicating the torque ripple that is the target standard. It can be seen that low torque ripple is measured.

In addition, at a point where the ratio of the second angle R2 to the first angle R1 is 0.92 to 0.95, the torque is measured higher than the reference line A representing the target torque, indicating that the required torque is also satisfied. .

5 is a diagram showing an optimal shape of an outer circumferential surface of a magnet for reducing torque ripple.

Referring to FIG. 5 , a point on the outer circumferential surface of the magnet 220 farthest from the center C of the rotor core 210 to the outer circumferential surface of the magnet 220 is referred to as P in FIG. 5 . Also, a virtual reference line connecting the center C of the rotor core 210 and P in FIG. 5 is referred to as Z in FIG.

In general, the outer circumferential surface of the magnet 220 is designed to be disposed along S1 in FIG. 5 . S1 in FIG. 5 is a line representing a circumference whose radius F1 is the distance from the first origin point P1 away from the center C on the reference line Z in FIG. 5 to P in FIG. 5 .

On the other hand, the outer circumferential surface of the magnet 220 of the rotor according to the embodiment is designed to be disposed along S2 in FIG. 5 . S2 in FIG. 5 is a line representing the circumference of which the first radius F2 is the distance from the second origin point P2 away from the center C on the reference line Z in FIG. 5 to P in FIG. 5 . Here, the second origin point P2 is disposed outside the first origin point P1 in the radial direction of the rotor core 210 .

The shape of the outer circumferential surface of the magnet 220 is to reduce torque ripple under high-speed conditions.

6 and 7 are graphs showing torque ripple generated under high-speed rotation conditions.

Referring to FIGS. 6 and 7, in the case of a motor including a magnet whose outer circumferential surface is formed along S1 in FIG. 5, as shown in A and A of FIG. 6, noise increases significantly in the 800hz region. You can check. 800hz is a state in which the motor rotates at 2900rpm, and it can be seen that the torque ripple greatly increases in high-speed rotation.

Referring to FIG. 5 , in order to reduce the torque ripple, the rotor according to the embodiment changes the shape of the outer circumferential surface of the magnet 220 to have a smaller curvature radius than the outer circumferential surface of a general magnet, as shown in S2 of FIG. 5 .

Specifically, when the second radius F3 is 1, the magnet 220 may be designed such that the first radius F2 is 0.5 to 0.7. Here, the first radius F2 is the radius of curvature of the outer circumferential surface of the magnet 220, and is the distance from the second origin point P2 to P in FIG. 5, and the second radius F3 is the inner circumferential surface of the magnet 220. corresponds to the radius of curvature of

For example, if the distance from the center C of the rotor core 210 to P in FIG. 5 is 20 mm, the first radius F2 may be 11.2 mm and the second radius F3 may be 17.2 mm. . Accordingly, the distance from the center C of the rotor core 210 to the second origin P2 corresponds to 8.8 mm.

The results of measuring cogging torque and torque ripple of a motor with 6 poles and 9 slots under the above conditions are as follows.

8 is a table comparing cogging torque and torque ripple of a comparative example and cogging torque and torque ripple of an embodiment.

Referring to FIG. 8, MW of FIG. 13 represents the ratio of the second angle R2 to the first angle R1, and the MOF of FIG. 8 is the second origin point P2 at the center C of the rotor core 210. ) is the distance to

In the case of Comparative Example, the ratio of the second angle R2 to the first angle R1 is 0.885, and the condition is that the second origin point P2 is 5.3 mm from the center C of the rotor core 210.

In the case of the embodiment, the ratio of the second angle R2 to the first angle R1 is 0.93, and the condition is that the second origin point P2 is 8.8 mm from the center C of the rotor core 210.

Under these conditions, the results of measuring the cogging torque, torque ripple, and torque of Comparative Examples and Examples are as follows.

First, it appears that there is no significant difference between the maximum torque of the comparative example and the maximum torque of the embodiment. However, cogging torque and torque ripple appear to be greatly reduced. In particular, the high-speed torque ripple appears to be greatly reduced from 0.1758 Nm (comparative example) to 0.0054 Nm (example). This is significantly lower than the torque ripple reduction target.

9 is a graph showing torque ripple of a motor according to an embodiment in a high-speed rotation condition.

Referring to FIG. 9 , unlike A of FIG. 7 , noise is greatly reduced in the 800 hz region and thus torque ripple is reduced.

Fig. 10 is a diagram showing the groove of a tooth.

The stator 300 shown in FIGS. 1 and 10 may include a stator core 300a and a coil 330.

The stator core 300a may be formed by stacking a plurality of plates in the form of thin steel plates. In addition, the stator core 300a may be formed by combining or connecting a plurality of split cores.

The stator core 300a may be provided with an annular yoke 310 portion and a tooth 320 protruding from the yoke 310 toward the center. A coil 330 is wound around the teeth 320 . A plurality of teeth 320 may be disposed at regular intervals along the inner circumferential surface of the annular yoke 310 . Although a total of 12 teeth 320 are shown in FIG. 3 , the present invention is not limited thereto and may be variously changed according to the number of poles of the magnet 220 .

A magnet 220 may be attached to an outer circumferential surface of the rotor core 210 . The ends of the teeth 320 are disposed to face the magnet 220 .

Referring to FIG. 10 , a tooth 320 may include a body 321 and a shoe 322 . The body 321 is where the coil (330 in FIG. 1) is wound. The shoe 322 is disposed at the end of the body 321. The end surface of the shoe 322 is disposed to face the magnet 220 . Between adjacent teeth 320 and teeth 320, a winding space P of a coil (330 in FIG. 1) is formed. The shoes 322 of adjacent teeth 320 and the shoes 322 are spaced apart from each other to form a slot open (S). Slot open (S) is the entrance of the winding space (P), where the nozzle winding the coil is inserted.

An inner circumferential surface of the shoe 322 may include a groove 323 . The groove 323 may be concavely formed on the inner circumferential surface of the shoe 322 . Although the shape of the groove 323 is shown as an angular shape, the present invention is not limited thereto. Also, the groove 323 may be disposed along the axial direction of the stator core 310 . In other words, the grooves 323 may be disposed along the height direction of the stator core 310 from the top to the bottom of the stator core 310 .

Two grooves 323 may be disposed. Referring to FIG. 10, based on the reference line L passing through the center of width of the body 321 of the tooth 320 and the center C of the stator core 310, the two grooves 323 are arranged symmetrically. can The groove 323 plays a role corresponding to the slot opening S that causes a change in magnetic flux density, thereby greatly reducing the cogging torque by increasing the frequency of the cogging torque waveform per unit period.

11 is a table showing a cogging main order increased by a motor according to an embodiment.

Referring to FIG. 11 , in the case of a 6-pole 9-slot motor, the cogging main order corresponds to 18, which is the least common multiple of 6, which is the number of magnets 220, and 9, which is the number of slots. Here, the cogging main order means the number of oscillations of the cogging torque waveform per unit rotation (one rotation) of the motor. Here, the number of vibrations represents the number of repetitions of the cogging torque waveform forming the peak. And the number of slots corresponds to the number of teeth 320 .

In the case of a 6-pole 9-slot motor with two grooves 323, since the number of slots can be considered to increase from 9 to 27 by the grooves 323, the cogging main order triples from 18 to 54. do. Since increasing the cogging main order three times through the two grooves 323 means that the number of vibrations of the cogging torque waveform increases three times, the cogging torque can be greatly reduced.

12 is a diagram showing the width of a groove, and FIG. 13 is a table showing a change in a cogging torque waveform according to the width of a groove.

Referring to FIGS. 12 and 13 , the width W1 of the groove 323 is set within 90% to 110% of the width W2 of the slot open S. Here, the width W1 of the groove 323 means a distance from one side end of the inlet of the groove 323 to the other side end based on the circumferential direction of the stator core 310 . Also, the width W2 of the slot opening S means the distance from one side end of the entrance of the slot opening S to the other side end based on the circumferential direction of the stator core 310 .

As shown in (a) of FIG. 13, when the width W1 of the groove 323 deviates from 90% to 110% of the width W2 of the slot open S, the cogging torque waveform shows the stator component, that is, , the same cogging main order as the number of poles of the magnet 220 is included.

However, as shown in (b) of FIG. 13, when the width W1 of the groove 323 is within 90% to 110% of the width W2 of the slot opening S, the cogging main order “54” It can be confirmed that only the cogging torque waveform corresponding to is detected.

When the shoe 322 includes the groove 323, there is a problem in that the magnitude and distribution of the cogging torque increase in the state where the rotor 200 has no skew and the cogging main order is “9”.

14 is a view showing a shoe having a curved inner circumferential surface.

Referring to FIG. 14 , in the motor according to the embodiment, the center of curvature of the inner circumferential surface of the shoe 322 is formed to coincide with the center C of the stator core (310 in FIG. 2 ). Specifically, the center of an imaginary circle (O) connecting the inner circumferential surfaces of the plurality of shoes 322 coincides with the center (C) of the stator core (310 in FIG. 2 ) of the stator core.

15 compares the cogging torque of a motor in which the inner circumferential surface of the shoe is flat and the cogging torque of a motor in which the center of curvature of the inner circumferential surface of the shoe 322 coincides with the center C of the stator core 310 of the stator core. It is a picture.

A of FIG. 15 is a case in which the inner circumferential surface of the shoe is flat in a motor including a 6-pole 9-slot rotor without a skew. 15B is a case in which the center of curvature of the inner circumferential surface of the shoe coincides with the center C of the stator core 310 in a motor including a 6-pole 9-slot rotor without skew.

Referring to A of FIG. 15, there is an effect of greatly reducing the cogging torque in the 18th cogging main order. At the ninth cogging main order, a problem arises in which the cogging torque greatly increases than the reference value.

Looking at B of FIG. 15, it can be seen that there is an effect of reducing the cogging torque than the reference value (Reference) at the 18th cogging main order, and even at the 9th cogging main order, the cogging torque is reduced than the reference value (Reference).

16 shows the deviation and output of the cogging torque of the motor in which the inner circumferential surface of the shoe is flat, and the deviation and output of the cogging torque of the motor in which the center of curvature of the inner circumferential surface of the shoe 322 coincides with the center C of the stator core 310, and Here is a picture comparing the output.

A of FIG. 16 is a case in which the inner circumferential surface of the shoe is flat in a motor including a 6-pole 9-slot rotor without a skew. 16B is a case in which the center of curvature of the inner circumferential surface of the shoe coincides with the center C of the stator core 310 in a motor including a 6-pole 9-slot rotor without skew.

Looking at A in FIG. 16, as a result of the three sample experiments, it can be seen that the deviation between the maximum value (0.0107 N/m) and the minimum value (0.0028 N/m) of the cogging torque is very large in the ninth cogging main order.

On the other hand, looking at B in FIG. 16, as a result of the three sample experiments, it can be seen that the deviation between the maximum value (0.0012 N/m) and minimum value (0.0003 N/m) of the cogging torque in the 9th cogging main order is not relatively large. can

In addition. In B of FIG. 16 , it can be seen that the output is increased by about 1% compared to A in FIG. 16 .

17 is a diagram illustrating a cogging torque improvement state corresponding to a cogging main order in a motor according to an embodiment.

The red bar in FIG. 17 is the torque when the inner circumferential surface of the shoe is flat in a motor including a 6-pole, 9-slot, non-skew rotor, and the blue bar in FIG. 17 is a 6-pole, 9-slot, non-skew rotor. This is the cogging torque when the center of curvature of the inner circumferential surface of the shoe coincides with the center (C) of the stator core 310 in the included motor.

Referring to FIG. 17, in the 6th and 18th cogging main orders, the cogging torque indicated by the red bar and the coating torque indicated by the blue bar are not significantly different. on the other side. In the ninth cogging main order, it can be seen that the coating torque indicated by the blue bar is greatly reduced compared to the cogging torque indicated by the red bar, and thus the cogging torque reduction performance is greatly improved.

In the above, a stator and a motor including the stator according to one preferred embodiment of the present invention have been examined in detail with reference to the accompanying drawings.

The above description is merely an example of the technical idea of the present invention, and those skilled in the art can make various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings. . The protection scope of the present invention should be construed according to the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: axis of rotation
200: rotor
210: rotor core
220: magnet
300: stator
310: stator core
320: teeth
321: body
322: shoe
323 Home
330: coil

Claims (10)

axis of rotation;
a rotor including a hole into which the rotating shaft is inserted; and
Including a stator disposed outside the rotor,
The stator is
A stator core having a plurality of teeth and a coil wound on the teeth, wherein the teeth include a body around which the coil is wound and a shoe connected to the body, the shoe including a plurality of grooves, The center of curvature of the inner circumferential surface of the shoe is the same as the center of curvature of the stator core,
The rotor includes a cylindrical rotor core and a plurality of magnets disposed surrounding an outer circumferential surface of the rotor core,
The number of magnets is 6, the number of teeth is 9,
The magnet has an inner circumferential surface in contact with the outer circumferential surface of the rotor core,
When an angle formed by dividing an angle formed by the outer circumferential surface of the rotor core by the number of magnets is referred to as a first angle R1, from both end points of the inner circumferential surface of the magnet to the center point of the rotor core on a cross section between the rotor core and the magnets. It has a second angle (R2) formed by the extended first and second extension lines, and the ratio of the second angle (R2) to the first angle (R1) is 0.92 to 0.95,
the rotor,
On the cross section of the rotor core and the magnet,
The radius of curvature of the outer circumferential surface of the magnet is referred to as the first radius,
When the radius of curvature of the inner circumferential surface of the magnet is referred to as the second radius,
A motor in which the ratio of the first radius to the second radius is 0.5 to 0.7. delete According to claim 1,
The groove is two,
The width of the groove based on the circumferential direction of the stator core is within 90% to 110% of the width of the slot open of the tooth. According to claim 1,
A motor whose cogging main order, which is the number of oscillations of the cogging torque waveform during unit rotation, is three times the least common multiple of the number of magnets and the number of teeth. According to claim 4,
When the width of the groove based on the circumferential direction of the stator core is within 90% to 110% of the width of the slot open of the tooth, the cogging main order is 54 due to the groove. According to claim 1,
The plurality of magnets are arranged in one stage on the outer circumferential surface of the rotor core, and the plurality of magnets are spaced apart from each other at a predetermined interval and arranged. delete delete delete delete

Images