KR20210120354A - Electric motor and electric vehicle having the same - Google Patents

Abstract

According to the present embodiment, an electric motor and an electric vehicle with the same comprise: a stator having a stator core having a plurality of slots formed along a circumferential direction and a stator coil wound around the slots of the stator core; and a rotor having a rotor core rotatably disposed with a preset gap with respect to the stator and having a plurality of magnet accommodating portions formed along a circumferential direction and a plurality of permanent magnets accommodated in the plurality of magnet accommodating portions. A flux barrier is formed at outer end portions of the plurality of magnet accommodating portions. At least a portion of the flux barrier may be formed differently depending on an axial position of the rotor core. Through this, it is possible to reduce torque ripples while minimizing an output loss of the electric motor.

Description

Electric motor and electric vehicle equipped therewith

The present invention relates to an electric motor and an electric vehicle having the same.

In general, motors can be divided into DC motors and AC motors according to the power used. AC motors can be divided into synchronous motors and induction motors according to their structure.

Synchronous motors are highly efficient and easy to control, but they are difficult to manufacture and have a relatively high price. Induction motors are widely used because of their simple structure, strong resistance to external shocks, and low price.

Recently, as the research and development of electric vehicles accelerated, the demand for electric motors is also increasing significantly. Motors used as driving sources for electric vehicles are usually high-speed and high-output motors.

However, high-speed and high-output motors may generate vibration noise due to a torque ripple or decrease in output due to a decrease in motor torque depending on operating conditions.

Accordingly, conventionally, a skew structure or a flux barrier for reducing torque ripple of an electric motor has been proposed. These are known to form magnetoresistance so as not to cause abrupt magnetic flux change, thereby reducing torque fluctuation and reducing torque ripple.

For example, in Patent Document 1 (US 9,906,082 B2), a skew structure is applied while forming a plurality of “V”-shaped magnetic flux walls to overlap in the radial direction, thereby reducing torque ripple and thrust in the axial direction.

However, in the conventional electric motor as described above, torque ripple can be reduced by applying a skew structure to the rotor to generate a phase difference of flux linkage, but this may cause torque loss due to leakage flux.

Furthermore, in the conventional electric motor, an output decrease due to a torque loss occurs, and thus the size of the electric motor may be enlarged. If the size of the electric motor becomes enlarged, the weight of the electric motor increases accordingly, which may deteriorate the performance of the vehicle when applied to a vehicle. In addition, as the size of the motor becomes enlarged, the material used increases, which may increase the manufacturing cost.

US 9,906,082 B2 (Registration Date: 2018.02.27)

An object of the present invention is to provide an electric motor capable of reducing vibration noise while maintaining high efficiency and an electric vehicle having the same.

Furthermore, an object of the present invention is to provide an electric motor capable of reducing torque ripple while suppressing a decrease in output and an electric vehicle having the same.

Furthermore, an object of the present invention is to provide an electric motor capable of applying a skew structure while suppressing leakage flux by securing an extreme arc angle of a magnetic flux wall, and an electric vehicle having the same.

Furthermore, an object of the present invention is to provide an electric motor capable of reducing the manufacturing cost compared to efficiency through miniaturization and reducing the weight of a means equipped with the same through weight reduction and an electric vehicle having the same.

In order to achieve the object of the present invention, a stator having a stator core having a plurality of slots formed along the circumferential direction, and a stator coil wound around the slots of the stator core; and a rotor core rotatably disposed with a predetermined gap with respect to the stator and having a magnet accommodating portion formed along a circumferential direction, and a rotor having a permanent magnet accommodated in the magnet accommodating portion, wherein the rotor core comprises, An electric motor may be provided in which a magnetic flux barrier is formed at at least one end of the magnet accommodating part, and the magnetic flux wall is twisted along an axial direction.

Here, the magnet accommodating part is formed to be inclined in opposite directions to the first magnet accommodating part and the second magnet accommodating part from both sides with respect to the radial center line, and at the outer end of the first magnet accommodating part, the first magnetic flux wall is in the first direction and a second magnetic flux wall extending in a second direction opposite to the first direction from an outer end of the second magnet accommodating part, and the rotor core is formed by the first magnetic flux wall of the first magnetic flux wall along the axial direction. The arc length in the direction or the arc length in the second direction of the second magnetic flux wall may be formed to have a different section.

The arc length of the first magnetic flux wall in the first direction and the arc length of the second magnetic flux wall in the second direction on the same layer may be symmetric with respect to the axial direction of the rotor core.

The rotor core may include: a first section in which the arc length of the first magnetic flux wall in the first direction and the arc length of the second magnetic flux wall in the second direction have a first length on the same layer; and a second section in which the arc length in the first direction of the first magnetic flux wall and the arc length in the second direction of the second magnetic flux wall have a second length different from the first length, respectively, on the same layer; The first section and the second section may be alternately arranged along the axial direction.

In addition, it may include a section in which the arc length in the first direction of the first magnetic flux wall and the arc length in the second direction of the second magnetic flux wall on the same layer are asymmetric with respect to the axial direction of the rotor core.

The rotor core may include: a first section in which the arc length of the first magnetic flux wall in the first direction is greater than the arc length of the second magnetic flux wall in the second direction on the same layer; a second section in which the arc length in the first direction of the first magnetic flux wall and the arc length in the second direction of the second magnetic flux wall are the same on the same layer; and a third section in which the arc length of the first magnetic flux wall in the first direction is smaller than the arc length of the second magnetic flux wall in the second direction on the same layer, wherein the first section, the second section, and the third section The sections may be sequentially arranged along the axial direction.

In addition, in order to achieve the object of the present invention, a stator having a stator core having a plurality of slots formed along the circumferential direction, and a stator coil wound around the slots of the stator core; and a rotor having a rotor core rotatably disposed with a predetermined gap with respect to the stator and having a plurality of magnet accommodating portions formed along a circumferential direction, and a plurality of permanent magnets accommodated in the plurality of magnet accommodating portions, and , A magnetic flux barrier is formed at the outer axial end of the plurality of magnet accommodating parts, and the magnetic flux wall may be provided with an electric motor in which at least a portion is formed differently depending on the axial position of the rotor core.

Here, the arc length of the magnetic flux wall extending in the circumferential direction with respect to one side of the permanent magnet may be at least partially different depending on the axial position of the rotor core.

Here, the inclination angle of the magnetic flux wall, which is defined as an angle between one side of the permanent magnet and the magnetic flux wall facing the same, may be formed to be at least partially different depending on the axial position of the rotor core.

Here, the rotor core is divided into a plurality of stages along the axial direction, and at least one first symmetrical stage in which both magnetic flux walls facing each other are symmetrical with respect to the radial center line may be included.

In addition, the other end adjacent to the first symmetrical end forms a second symmetrical end in which both magnetic flux walls facing each other with respect to the radial center line are symmetrical to each other, and the magnetic flux wall of the second symmetrical end is the first symmetrical. It may be formed differently from the magnetic flux wall of the stage.

In addition, the flux barrier pole arc angle defined as the shortest distance between the magnetic flux walls facing each other may be the same in the same stage and different in different stages.

In addition, a magnetic flux wall inclination angle defined as an angle between one side of the permanent magnet and one side of the magnetic flux wall facing the permanent magnet may be the same at the same stage and different at different stages.

Here, the rotor core is divided into a plurality of stages along the axial direction, and both magnetic flux walls have at least one asymmetrical first asymmetric end at the same stage based on a radial center line passing between the two facing magnetic flux walls. may be included.

In addition, the other end adjacent to the first asymmetric end forms a symmetric end in which both magnetic flux walls facing each other with respect to the radial center line are symmetric to each other, and the opposite end of the first asymmetric end with the symmetric end interposed therebetween forms a second asymmetric end at which both magnetic flux walls facing each other with respect to the radial center line are asymmetric to each other, and the magnetic flux wall of the first asymmetric end and the magnetic flux wall of the second asymmetric end are formed with respect to the radial center line. can be symmetrical.

In addition, the flux barrier pole arc angle defined as the shortest distance between the magnetic flux walls facing each other may be equally formed in all stages.

Here, the rotor core may be divided into even-numbered stages along the axial direction, and the even-numbered stages may have magnetic flux walls facing each other with respect to a radial center line symmetrical at the same stage.

In addition, different stages among the even-numbered stages may have different circumferential distances between the magnetic flux walls.

In addition, the lengths in the circumferential direction of the magnetic flux walls between the different stages may be different.

Here, the rotor core may be divided into odd-numbered stages along the axial direction, and the odd-numbered stages may include stages in which magnetic flux walls facing each other with respect to a radial centerline are asymmetrical at the same stage.

In addition, symmetrical and asymmetrical ends of magnetic flux walls facing each other with respect to the radial centerline may be alternately provided along the axial direction at the same end.

Here, it is defined as the angle between the first end line connecting the end of the magnetic flux wall at the center of the rotor core and the second end line connecting the edge of the permanent magnet facing the end of the magnetic flux wall at the center of the rotor core. The magnetic flux wall barrier angle θ may be formed to satisfy {(opening angle of slot×0.5 times) ≤ θ ≤ (360/number of slots/2)}.

Here, when the polar arc between the permanent magnets facing each other is a first pole arc angle (α), and the polar arc angle between the magnetic flux walls facing each other is a second pole arc angle (β), the second polar arc angle is, It may be formed to satisfy β={(0.75~1.0)×α}.

In addition, in order to achieve the object of the present invention, vehicle body; a plurality of wheels operably provided on the vehicle body; a battery provided in the vehicle body; and an electric motor connected to the battery and providing driving force to the plurality of wheels, wherein the electric motor may be provided with an electric vehicle including the electric motor described above.

In the electric motor and electric vehicle having the same according to the present embodiment, the magnetic flux walls extending from the plurality of magnet accommodating parts are formed to be at least partially different depending on the axial position of the rotor core, so that the output loss of the motor is minimized and torque ripple can be reduced. Through this, a low-vibration high-efficiency electric motor can be realized.

In addition, the present embodiment may be divided into a plurality of stages along the axial direction of the rotor core and formed in an asymmetric shape in which the magnetic flux wall arc length (polar arc angle) or inclination angle at each stage is formed differently. Through this, it is possible to reduce the torque ripple while suppressing the output decrease of the motor.

In addition, the present embodiment is divided into a plurality of stages along the axial direction of the rotor core, the magnetic flux wall arc length (polar arc angle) or inclination angle for each stage can be formed differently. Through this, it is possible to reduce the torque ripple by forming the rotor core in a skew structure while suppressing leakage flux by securing the extreme arc of the magnetic flux wall. .

In addition, as described above, in this embodiment, the torque ripple can be reduced while minimizing the output loss by forming the rotor core in an asymmetrical shape. Through this, it is possible to reduce the manufacturing cost and increase the performance of a vehicle equipped with the electric motor by reducing the size and weight of the electric motor.

1 is a perspective view of an electric vehicle having an electric motor according to the present embodiment;
Figure 2 is a cross-sectional view showing the inside of the electric motor of Figure 1,
3 is an enlarged cross-sectional view of the main part of FIG. 2;
4 is a schematic diagram showing a change in the shape of the magnetic flux wall along the axial direction;
5A and 5B are a cross-sectional view showing an example in which the rotor core is composed of two stages in the rotor and a schematic view showing a magnetic flux wall at each stage;
6A to 6C are a cross-sectional view showing an example in which the rotor core is composed of three stages in the rotor and a schematic view showing a magnetic flux wall at each stage;
7 is a schematic diagram showing the specification of a magnetic flux wall according to the present embodiment;
8 is a graph showing changes in torque and torque ripple according to the barrier angle in this embodiment;
9 is a graph showing changes in torque and torque ripple according to the polar arc ratio in this embodiment;
10 is a schematic view showing the inclination angle of the magnetic flux wall in FIG. 7;
11 and 12 are graphs showing the torque change and the torque ripple change of the electric motor to which the rotor core is applied according to the present embodiment, respectively;
13 is a schematic diagram showing another example of a rotor core according to the present embodiment;
14 is a schematic diagram showing another example of a rotor core according to the present embodiment;

Hereinafter, embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings. In this specification, the same or similar reference numbers are assigned to the same and similar components even in different embodiments, and the description is replaced with the first description.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted.

In addition, it should be noted that the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical ideas disclosed in the present specification by the accompanying drawings.

1 is a perspective view of an electric vehicle having an electric motor according to the present embodiment. As shown in FIG. 1 , the electric vehicle according to the present embodiment includes a vehicle body 11 , a battery 12 , and an electric motor 100 .

The vehicle body 11 may be configured to enable driving and boarding. Although not shown in the drawings, a cabin forming a boarding space may be provided above the vehicle body 11 . In addition, a plurality of wheels 13 may be provided on the vehicle body 11 . The plurality of wheels 13 may be disposed to be spaced apart from each other in the left-right direction and the front-rear direction.

The battery 12 may be provided in the vehicle body 11 . As is well known, the battery 12 may be formed of a rechargeable battery.

The electric motor 100 may be provided in the vehicle body 11 , and the electric motor 100 may be provided to provide a driving force to the wheel 13 . Also, the electric motor 100 may be configured to receive power from the battery 12 .

An inverter device 14 may be provided between the battery 12 and the electric motor 100 . The inverter device 14 may receive DC power from the battery 12 , convert it into AC power, and then supply it to the electric motor 100 .

For example, the inverter device 14 may include an input cable 14a and an output cable 14b. The input cable 14a may be connected to the battery 12 . The output cable 14b may be connected to the electric motor 100 .

FIG. 2 is a cross-sectional view showing the inside of the electric motor of FIG. 1 . As shown in FIG. 2, the electric motor 100 is rotatable with respect to the case (refer to FIG. 1) 110 forming the exterior, the stator 120 and the stator 120 provided in the case 110. and a rotor 130 disposed thereon.

The case 110 may be formed in a cylindrical shape having an accommodating space therein. The stator 120 and the rotor 130 may be accommodated in the accommodating space of the case 110 .

In order to accommodate the stator 120 and the rotor 130 in the accommodating space of the case 110 , one end of both ends of the case 110 may be opened or both ends of the case 110 may be opened.

When both ends of the case 110 are opened, end covers (shown in FIG. 1 ) 111 may be mounted on both ends of the case 110 . The end cover 111 may cover both ends of the case 110 and be fastened to the case 110 by a fastening member such as a bolt.

The stator 120 includes a stator core 122 and a stator coil 124 wound around the stator core 122 . The stator core 122 is formed by insulating and stacking a plurality of electrical steel plates made of a magnetic material, and may be fixedly coupled to the inner circumferential surface of the case 110 .

The stator core 122 may be provided with a rotor accommodating part 126 so that the rotor 130 can be rotatably accommodated with a preset air gap G therein. The rotor accommodating part 126 may be formed through the axial direction.

Further, the stator core 122 includes a plurality of slots 122a and a plurality of teeth 122b alternately arranged around the rotor accommodating portion 126 . The stator coil 124 is wound via the inside of the plurality of slots 122a.

In addition, the stator core 122 may include a slit (not shown) that is formed through the axial direction so that the width of the magnetic body of the teeth 122b can be reduced. Thereby, the magnetic flux density passing through the teeth 122b is increased, so that the harmonic magnetic flux passing through the teeth 122b can be suppressed.

In addition, since the leakage magnetic flux passing through the inside of the slot 122a is suppressed, copper loss of the stator coil 124 due to the leakage magnetic flux can be reduced. In addition, by moving the cooling fluid through the slit 350, cooling of the slit (not shown) around (the stator 120 and the rotor 130) can be promoted.

Meanwhile, the rotor 130 may include a rotor core 132 and a plurality of permanent magnets 134 coupled to the rotor core 132 .

The rotor core 132 may be formed by insulating and stacking a plurality of electrical steel sheets made of a magnetic material. A rotation shaft coupling part 1322 is formed in the center of the rotor core 132 so that the rotation shaft 136 can be inserted, and a plurality of magnet accommodating parts into which the permanent magnets 134 are inserted along the circumference of the rotation shaft coupling part 1322 . 1324 may be formed. The rotation shaft coupling part 1322 and the plurality of magnet accommodating parts 1324 may be formed to penetrate the rotor core 132 in the axial direction, respectively.

The rotating shaft 136 may be hot press-fitted to the rotating shaft coupling part 1322 . The rotating shaft 136 may protrude by extending to both sides of the rotor core 132 in the axial direction. At least a portion of both ends of the rotation shaft 136 may be exposed to the outside through the case 110 . The rotating shaft 136 may be rotatably supported by a bearing (not shown) on the case 110 .

One (in some cases, a plurality of) permanent magnets 134 may be inserted into and coupled to the magnet accommodating part 1324 . In the permanent magnet 134 , different magnetic poles (N pole, S pole) may be alternately disposed along the circumferential direction of the rotor core 132 . Accordingly, the rotor 130 may include a plurality of permanent magnets 134 for each one pole (N pole, S pole), respectively.

In the rotor 130 according to the present embodiment, two permanent magnets 134 per each pole may be respectively arranged in a “V” shape so that the end (outer end) close to the circumference is widened. However, this is only an example and is not limited thereto.

For example, in the rotor 130, four permanent magnets 134 provided for each one pole may form two pairs of "V" shapes, and may be arranged one pair in the radial direction, and three permanent magnets are "▽" “It can be arranged in a shape. In addition, the permanent magnet 134 may be variously disposed in the rotor 130 . However, hereinafter, an example in which the permanent magnet 134 is disposed in a single “V” shape in the rotor core 132 will be described as a representative example.

The plurality of magnet accommodating portions 1324 may be formed to correspond to the arrangement of the permanent magnets 132 . For example, the magnet accommodating part 1324 according to the present embodiment may be formed in a “V” shape like the permanent magnet 134 .

Specifically, when the two magnet accommodating parts 1324 facing each other are referred to as one magnet accommodating part set, the entire magnet accommodating part set is formed in the same pattern along the circumferential direction, and one magnetic flux accommodating part set is previously It can be formed into a "V" shape as described. Therefore, hereinafter, for convenience of description, a set of one magnet accommodating part having a "V" shape will be described as a representative example.

Figure 3 is an enlarged cross-sectional view showing the main part of Figure 2 in order to explain the magnet accommodating part set. Hereinafter, for convenience of explanation, the left side of the drawing is defined as the first magnet accommodating part 1324a and the right side of the drawing is defined as the second magnet accommodating part 1324b, respectively.

Accordingly, the permanent magnet located on the left side of the drawing is defined as the first permanent magnet 134a, the permanent magnet located on the right side of the drawing is defined as the second permanent magnet 134b, and the magnetic flux wall located on the left side of the drawing is defined as the first magnetic flux wall. (1326a), the magnetic flux wall located on the right side of the drawing will be described by defining the second magnetic flux wall 1326b.

Referring to FIG. 3 , the plurality of magnet accommodating parts 1324 may include a first magnet accommodating part 1324a and a second magnet accommodating part 1324b facing the first magnet accommodating part 1324a in the circumferential direction. have.

The first magnet accommodating part 1324a and the second magnet accommodating part 1324b are formed symmetrically on both sides of the radial center line CL as a center, respectively. For example, the first magnet accommodating part 1324a is on the left side of the drawing with respect to the radial center line CL, and the second magnet accommodating part 1324b is on the right side of the drawing with respect to the radial center line CL, respectively. will be located The radial center line CL means a line passing through the center O of the rotor core 132 in a radial direction.

The first magnet accommodating part 1324a and the second magnet accommodating part 1324b may be inclined in opposite directions with respect to the radial center line CL.

For example, the first magnet accommodating part 1324a is inclined by a predetermined angle in a direction away from the radial center line CL from the inner peripheral side to the outer peripheral side by a predetermined angle, and the second magnet accommodating part 1324b is the inner peripheral side It is formed to be inclined by a predetermined angle in a direction away from the radial center line CL toward the outer periphery. Accordingly, the first magnet accommodating part 1324a and the second magnet accommodating part 1324b form a "V" shape.

However, the inner peripheral end of the first magnet accommodating part 1324a and the inner peripheral end of the second magnet accommodating part 1324b are not connected to each other and are spaced apart to form the inner peripheral bridge part 1328a. Of course, the outer peripheral end of the first magnet accommodating portion 1324a and the outer peripheral end of the second magnet accommodating portion 1324b are also spaced apart from each other to form the outer peripheral side bridge portion 1328b.

In addition, the first magnet accommodating part 1324a and the second magnet accommodating part 1324b may be formed in an elongated rectangular shape from the inner peripheral end to the outer peripheral end, respectively. For example, the first magnet accommodating part 1324a and the second magnet accommodating part 1324b may each be formed in a substantially rectangular shape when projected in the axial direction.

In addition, magnetic flux walls may be formed at the inner and outer peripheral ends of the first magnet accommodating portion 1324a and the inner and outer peripheral ends of the second magnet accommodating portion 1324b, respectively. The magnetic flux wall 1326 is a space filled with air, and serves as a magnetic path barrier that blocks the flow of leakage flux from the permanent magnet 134 through the bridge portions 1328a and 1328b. Accordingly, the magnetic flux wall 1326 is referred to as a flux wall or a flux barrier. Hereinafter, it is collectively referred to as a magnetic flux wall for convenience. The magnetic flux wall will be described in detail later.

A first permanent magnet 134a may be inserted into the first magnet accommodating part 1324a, and a second permanent magnet 134b may be inserted into the second magnet accommodating part 1324b to be fixed. As described above, the first permanent magnet 134a is formed to have substantially the same shape as the first magnet accommodating part 1324a, and the second permanent magnet 134b has substantially the same shape as the second magnet accommodating part 1324b. can be formed.

The first permanent magnet 134a and the second permanent magnet 134b may be formed symmetrically about the radial center line CL as in the case of the first magnet accommodating part 1324a and the second magnet accommodating part 1324b. can Accordingly, the first permanent magnet 134a and the second permanent magnet 134b may be formed in the same manner. Hereinafter, the first permanent magnet 134a will be described as a representative example, and the second permanent magnet 134b is symmetrical with respect to the radial center line CL only in the inclination direction with the first permanent magnet 134a, and the rest are the same. A detailed description thereof will be omitted.

For example, the first permanent magnet 134a may have a rectangular cross-sectional shape. The cross-section of the first permanent magnet 134a may have a horizontal length (major axis length) longer than a vertical length (short axis length) and may be formed in a flat shape. The axial length of the first permanent magnet 134a may be formed to correspond to the axial length of the rotor core 132 .

The first permanent magnet 134a may be configured to form a plurality of poles (N poles or S poles) along the outer periphery of the rotor core 132. Accordingly, the magnetic poles of the permanent magnet 134 are N along the circumferential direction. A plurality of permanent magnets may be disposed so that the poles or the S poles are alternately positioned.

As described above, the first permanent magnets 134a may be disposed to be inclined at a predetermined angle from the radial center line CL. The second permanent magnet 134b may be inclined in a direction opposite to that of the first permanent magnet 134a. The absolute slope of the first permanent magnet 134a and the second permanent magnet 134b may be the same.

As described above, as the permanent magnet 134 is inclined, the magnetic field area of the permanent magnet 134 accommodated in the rotor core 132 can be increased, and through this, the permanent magnet 134 is generated from the stator ( 120) can be increased.

A plurality of first permanent magnets 134a may be disposed to overlap in a radial direction of the rotor core 132 . The plurality of first permanent magnets 134a may be formed to have different lengths. This will be described later with reference to FIGS. 11 and 12 .

On the other hand, the first inner peripheral side magnetic flux wall is formed on the inner peripheral end of the first magnet accommodating portion (1324a), the first outer peripheral side magnetic flux wall is formed to extend to the outer peripheral end, respectively, the inner peripheral end of the second magnet receiving portion (1324b) The second inner peripheral side magnetic flux wall may be formed by extending the second outer peripheral side magnetic flux wall at the outer peripheral end, respectively.

The first inner circumferential side magnetic flux wall and the second inner circumferential side magnetic flux wall may be symmetrically formed over the entire axial direction of the rotor core with respect to a radial center line. Since this is a structure already known in the field of electric motors, a description thereof will be omitted.

The first outer peripheral side magnetic flux wall (hereinafter abbreviated as first magnetic flux wall) 1326a and the second outer peripheral side magnetic flux wall (hereinafter abbreviated as second magnetic flux wall) 1326b respectively extend in the circumferential direction, It may be formed to extend to the opposite side.

For example, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b may be formed to extend in a direction toward the radial center line CL, that is, to face each other. In other words, the first magnetic flux wall 1326a may extend in the clockwise direction (hereinafter, the first direction) of the drawing, and the second magnetic flux wall 1326b may extend in the counterclockwise direction (hereinafter, the second direction) of the drawing. have.

However, at least a portion of the first magnetic flux wall 1326a and the second magnetic flux wall 1326b according to the present embodiment is asymmetrically formed over the entire axial direction of the rotor core 132 with respect to the radial center line CL. can

Referring back to FIG. 3 , the circumferential length of the first magnetic flux wall 1326a (hereinafter, the first arc length) L1 and the circumferential length of the second magnetic flux wall 1326b (hereinafter, the second arc length) ( L2) may be formed differently in at least a certain section along the axial direction. The arc length L1 (2) of the magnetic flux wall is the length from the edge of the permanent magnet 134 facing the radial center line O to the circumferential end of the magnetic flux wall. This is also referred to as the barrier angle θ of the magnetic flux wall, which will be described later.

That is, referring to FIGS. 3 and 4 , the first axial center line CL11 ′ (CL11″) and the second magnetic flux wall (CL11″) extending in the axial direction from the geometric center O′ of the first magnetic flux wall 1326a The second axial centerlines CL12' (CL12") extending axially through the geometric center O" of 1326b are respectively parallel to the axial centerline (ie, the axial centerline) CL11 of the rotor core 132 . is formed

However, the first axial center lines CL11' (CL11") and the second axial center lines CL12' (CL12") are not formed on the same axis line, but are formed parallel to each other on different axis lines. For example, if the rotor 130 is divided into two stages along the axial direction as shown in FIG. 4, the first magnetic flux wall 1326a' located at the upper end and the first magnetic flux wall 1326a" located at the lower end are the axial center line ( The second magnetic flux wall 1326b' located at the upper end and the second magnetic flux wall 1326b″ located at the lower end are located on the left side with respect to the axial center line CL11, respectively.

At this time, the axial center line CL11' of the first magnetic flux wall 1326a' located at the upper end and the axial center line CL11" of the first magnetic flux wall 1326a" located at the lower end are radially spaced apart and formed in parallel. and the axial center line CL12' of the second magnetic flux wall 1326b' located at the upper end and the axial center line CL12" of the second magnetic flux wall 1326b" located at the lower end are radially spaced apart and formed in parallel do.

Accordingly, at least one of the magnetic flux walls 1326a and 1326b is formed to have a plurality of axial centerlines [(CL11')(CL11")][(CL12')(CL12")] when viewed as a whole in the axial direction. . Accordingly, referring to FIGS. 3 and 4 , at least a portion of the first magnetic flux wall 1326a and the second magnetic flux wall 1326b when viewed with respect to the radial center line CL is asymmetrically formed on a plane when projected in the axial direction. can be

Although this may be asymmetrically formed in each of the core sheets constituting the rotor core 132 , it may not be practically useful in consideration of the fact that the rotor core 132 is formed by stacking the sheet core sheets. Therefore, it is realistic to form the core block by laminating a plurality of core sheets in the axial direction, and to form the rotor core 132 by laminating the core blocks again in the axial direction. In this case, the number of each core block forms the number of stages or the number of sections constituting the rotor core 132 .

In the core block constituting each step (or section), the axial center line forms the same axial center line, and in the core block constituting the other adjacent steps (or sections), the axial center line of the preceding core block (for example, the second 1 axial center line) and another axial center line (eg, a second axial center line).

In other words, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b may be formed symmetrically or asymmetrically on the same layer along the axial direction. However, when the rotor core is viewed as a whole, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b are asymmetrical along the axial direction. This may be determined by the number of stages or the number of sections of the rotor core 132 .

5A and 5B are cross-sectional views illustrating an example in which the rotor core is configured in two stages in the rotor and schematic views showing magnetic flux walls at each stage.

Referring to FIG. 5A , in the first stage S1 , the arc length L11 of the first magnetic flux wall 1326a and the arc length L12 of the second magnetic flux wall 1326b may be the same. For example, in the rotor core forming the first stage S1 , the first magnetic flux wall 1326a and the second magnetic flux wall 1326b are formed to have the same first arc length L1 . Accordingly, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b at the first end S1 form a symmetrical end symmetrical with respect to the radial center line CL.

Referring to FIG. 5B , in the second stage S2 , the arc length L21 of the first magnetic flux wall 1326a and the arc length L22 of the second magnetic flux wall 1326b may be the same. For example, in the rotor core forming the second stage S2, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b are formed to have the same second arc length L2. Accordingly, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b at the second end S2 form a symmetrical end symmetrical with respect to the radial center line CL.

However, the first arc length L1 at the first end S1 is longer than the second arc length L2 at the second end S2. Accordingly, the pole arc angle β1 between the magnetic flux walls at the first stage S1 may be greater than the pole arc angle β2 between the magnetic flux walls at the second stage S2. Accordingly, the first end S1 and the second end S2 each form a symmetric end, but when the first end S1 and the second end S2 are compared with each other, they form an asymmetric end.

Here, the polar arc angle β between the magnetic flux walls is defined as the circumferential shortest distance between the circumferential end of the first magnetic flux wall 1326a facing the radial center line CL and the circumferential end of the second magnetic flux wall 1326b. For convenience, it is defined as the second pole whistle, and the appropriate range of the second pole whistle will be described later along with the first pole whistle and the barrier angle of the magnetic flux wall.

As described above, when the rotor core 132 is formed in two stages, the second pole arc angles β1 and β2 may be formed in a shape in which both sides are enlarged along the axial direction. This may be similarly formed even when the rotor core 132 is formed in an even number of stages such as 2 stages, 4 stages, 6 stages, and the like.

However, if the second pole arc β is continuously expanded or decreased along the axial direction, it is in the form of excessively decreasing or increasing from the viewpoint of the magnetic flux wall 1326, which is not preferable in terms of motor output or reliability. may not be Therefore, when the rotor core 132 is formed in even-numbered stages, it may be preferable to repeatedly form two stages at a time.

In this way, the first imaginary line connecting the ends of the first magnetic flux wall 1326a at each stage S1 and S2 and the second imaginary line connecting the ends of the second magnetic flux wall 1326b are formed from the front. If you look at it, it will form a "V" shape. Then, in the first stage S1, the first arc length L1 of the magnetic flux wall 1326 is increased, so that leakage magnetic flux is suppressed by that amount, so that the output loss can be reduced.

In addition, since the end of the magnetic flux wall 1326 at each stage S1 and S2 is twisted in the circumferential direction along the axial direction, the magnetic flux wall 1326 of the rotor core 132 is a kind of skew. will form a structure. Due to this, a phase difference of the flux linkage may be generated, and torque ripple may be reduced.

Meanwhile, FIGS. 6A to 6C are cross-sectional views illustrating an example in which the rotor core is formed in three stages in the rotor and schematic views showing magnetic flux walls at each stage.

Referring to FIG. 6A , in the first stage S1 , the arc length L11 of the first magnetic flux wall 1326a may be longer than the arc length L12 of the second magnetic flux wall 1326b. For example, in the rotor core forming the first stage S1, the first magnetic flux wall 1326a has a first arc length L1, and the second magnetic flux wall 1326b has a second arc length L2, respectively. is formed to Accordingly, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b at the first end S1 form a first asymmetric end that is asymmetric with respect to the radial center line CL.

Referring to FIG. 6B , in the second stage S2 , the arc length L21 of the first magnetic flux wall 1326a and the arc length L22 of the second magnetic flux wall 1326b may be the same. For example, in the rotor core forming the second stage S2, the arc length L21 of the first magnetic flux wall 1326a and the arc length L22 of the second magnetic flux wall 1326b are respectively the third arc length L3 ) is formed to have Accordingly, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b at the second end S2 form a symmetrical end symmetrical with respect to the radial center line CL.

Referring to FIG. 6C , in the third stage S3 , the arc length L31 of the first magnetic flux wall 1326a may be shorter than the arc length L32 of the second magnetic flux wall 1326b. For example, in the rotor core forming the third stage S3, the first magnetic flux wall 1326a has a second arc length L2, and the second magnetic flux wall 1326b has a first arc length L1, respectively. is formed to Accordingly, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b at the third end S3 are asymmetrical with respect to the radial center line CL opposite to the first end S1. will form

However, the third arc length L3 may be shorter than the first arc length L1 but longer than the second arc length L2. That is, the third arc length L3 may be an intermediate length between the first arc length L1 and the second arc length L2.

Accordingly, assuming that the first polar arc angles α1, α2, and α3 in the first stage S1 to the third stage S3 are the same, in each stage S1, S2, and S3, The second extreme arc angles β1, β2, and β3 of each may be identically formed.

Here, the first pole arc angle α is the longest distance between the first magnetic flux wall 1326a and the second magnetic flux wall 1326b or the outer periphery of the first permanent magnet 134a and the second permanent magnet 134b on the same layer. The shortest distance between side edges, which can be defined as a polar arc.

Although not shown in the drawings, the third arc length L3 is shorter than the first arc length L1, but may be formed to be the same as the second arc length L2.

As described above, when the rotor core 132 is formed in three stages, the second pole arc angles β1, β2, and β3 are the same along the axial direction and the center moves from left to right when viewed from the front. can be formed with This may be similarly formed even when the rotor core 132 is formed in an odd number of stages, such as 3 stages, 5 stages, 7 stages, and the like. That is, when the rotor core 132 has an odd number of stages, the center of the second polar arc β may be formed to move in the circumferential direction along the axial direction.

In this way, the first imaginary line connecting the ends of the first magnetic flux wall 1326a at each stage S1, S2, and S3 and the second magnetic flux wall at each stage S1, S2, and S3. The second virtual line connecting the ends of (1326b) forms an oblique line and forms a “V” shape when viewed from the front. Then, in the first stage S1 and the third stage S3 , the first arc length L1 of the magnetic flux wall 1326 becomes longer, so that the leakage magnetic flux is suppressed so that the output loss can be reduced.

In addition, since the end of the magnetic flux wall 1326 at each stage S1, S2, and S3 is twisted in the circumferential direction along the axial direction, the magnetic flux wall 1326 of the rotor core 132 is a kind of skew. (skew) structure is formed. Due to this, a phase difference of the flux linkage may be generated, and torque ripple may be reduced.

5A and 5B described above, the electric motor according to this embodiment can reduce the torque ripple while minimizing the output loss, so that a low-vibration high-efficiency electric motor can be realized. The experimental results for this will be explained again later.

In the electric motor according to these embodiments, when the torque ripple is reduced while the output loss is minimized, there is no need to enlarge the size of the electric motor. Then, the material cost applied to the motor can be reduced, thereby reducing the manufacturing cost, and the motor can be miniaturized compared to the output, so that the performance of the electric vehicle equipped with it can be improved.

In addition, although not shown in the drawings, the first magnetic flux wall or the second magnetic flux wall may not extend in the circumferential direction at all, that is, the barrier pole arc (arc length) may be formed to be 0 degrees. In this case, the barrier pole arc (arc length) of the opposite magnetic flux wall may be formed longer than in the above-described embodiments.

On the other hand, the magnetic flux wall 136 according to the present embodiment serves as a flux barrier that blocks the flow of leakage magnetic flux flowing through the bridge portions 1328a and 1328b from the corresponding permanent magnet 134 as described above. will do Accordingly, in order for the magnetic flux wall 136 to prevent leakage of magnetic flux from the rotor core 132 , the magnetic flux wall 136 preferably has an appropriate arc length or inclination angle.

The arc length of the magnetic flux wall 136 may be defined as a barrier angle of the magnetic flux wall. That is, the barrier angle θ of the magnetic flux wall 136 is defined as a barrier angle of a circular arc connecting the end of the magnetic flux wall 136 and the edge of the permanent magnet 134 facing it at the center O of the rotor, respectively. can

7 is a schematic diagram showing the specification of a magnetic flux wall according to the present embodiment, FIG. 8 is a graph showing changes in torque and torque ripple according to a barrier angle in this embodiment, and FIG. 9 is a pole in this embodiment It is a graph showing the change of torque and torque ripple according to the whistle ratio.

Referring to FIG. 7 , the circumferential angle θ of the magnetic flux wall may be smaller than or equal to the opening angle δ of the slot. For example, the circumferential angle θ of the magnetic flux wall is a first imaginary line IL1 connecting the ends of the magnetic flux wall 1326 from the center O of the rotor core 132 and the center O of the rotor core 132 . ) may be defined as an angle between the second imaginary line IL2 connecting the edges of the permanent magnets 134 facing the ends of the magnetic flux walls 1326 in the second imaginary line IL2. Accordingly, the barrier angle θ of the magnetic flux wall 1326 may be defined as the following [Equation 1] related to the opening angle δ of the slot 122a or the number of slots 122a.

[Formula 1]

{(Slot opening angle × 0.5 times) ≤ θ ≤ (360/number of slots/2)}

In other words, the barrier angle θ of the magnetic flux wall 1326 is greater than or equal to at least 0.5 times the opening angle δ of the slot 122a, and smaller than or equal to the value obtained by dividing the angle of the slot 12a by 2 per each. can be formed.

For example, if there are 48 slots and the opening angle δ of the slots is 2 degrees, the minimum barrier angle θ of the magnetic flux wall 1326 is 2×0.5, which is 1 degree. On the other hand, the maximum barrier angle θ of the magnetic flux wall 1326 becomes (360÷48)/2, which is 3.75 degrees.

Accordingly, in the above case, the barrier angle θ of the magnetic flux wall 1326 may be preferably formed to be at least 1 degree and at most 3.75 degrees. That is, referring to FIG. 7 , the barrier angle θ of the first magnetic flux wall 1326a may be about 3.75 degrees, and the barrier angle θ of the second magnetic flux wall 1326b may be about 1 degree. This may also be expressed as the arc length of the magnetic flux wall 1326 .

This can be seen more clearly with reference to FIG. 8 . That is, the torque ripple decreases as the barrier angle θ increases, and the slope gradually changes when the barrier angle θ is approximately 2 degrees. And the torque ripple starts to increase again around 3 degrees. And the torque ripple increases rapidly around 3.75 degrees. It can be seen that even in this case, the average torque does not significantly decrease regardless of the change in the barrier angle θ. Accordingly, the barrier angle θ may be preferably formed to be approximately 1 degree to 3.75 degrees.

In addition, the arc length between the first magnetic flux wall 1326a and the second magnetic flux wall 1326b according to the present embodiment (polar arc angle or second polar arc angle between magnetic flux walls) (β) is also related to motor efficiency. For example, if the arc length (second pole arc angle) β between the first magnetic flux wall 1326a and the second magnetic flux wall 1326b is too large, the arc length (barrier angle) θ of the magnetic flux wall 1326 is that much. is short, which makes it impossible to faithfully fulfill the role of the magnetic flux wall 1326 .

On the other hand, if the arc length (second pole arc angle) β between the first magnetic flux wall 1326a and the second magnetic flux wall 1326b is too small, the arc length (barrier angle) of the magnetic flux wall 1326 (θ) is long, and the width of the bridge portion 1328b may be narrowed, thereby reducing reliability.

Accordingly, the second polar arc β may be defined as a ratio (polar arc ratio = β/α) to the first polar arc α as shown in [Equation 2] below.

[Formula 2]

β={(0.75~1.0)×α}

For example, if the polar arc between the permanent magnets (the first polar arc) α is 32 degrees, the polar arc between the magnetic flux walls (the second polar arc) β is 0.75×32=24, 1× Since 32 = 32, it is preferable that the second polar arc is eventually formed to be greater than or equal to 24 degrees and less than or equal to 32 degrees.

This can be seen more clearly with reference to FIG. 9 . That is, the torque ripple is remarkably reduced from the point where the polar whistle angle ratio is 0.75, and then rises again at the pole whistle angle ratio around 0.86. Even in this case, it can be seen that the torque is maintained almost constant or slightly increased regardless of the change in the barrier angle θ. Accordingly, the polar arc ratio θ may be preferably formed to be in the range of approximately 0.75 to 1.

As described above, as the rotor core 132 is divided into a plurality of stages along the axial direction, and the first magnetic flux wall 1326a and the second magnetic flux wall 1326b of each stage are formed in an asymmetric shape, leakage magnets are effectively prevented. By suppressing the torque, the torque ripple can be reduced because the magnetic flux wall of each stage is arranged to be twisted while the torque is hardly reduced.

This can also be defined by the inclination angle of the magnetic flux wall. FIG. 10 is a schematic diagram illustrating an inclination angle of a magnetic flux wall in FIG. 7 .

Referring to FIG. 10 , the first magnetic flux wall 1326a is formed to be inclined by the first inclination angle ω1 with respect to the first permanent magnet 134a, and the second magnetic flux wall 1326b is the second permanent magnet 134b. It may be formed inclined by the second inclination angle ω2 with respect to the .

The first inclination angle ω1 is defined as an angle between one side of the first permanent magnet 134a and one side of the first magnetic flux wall 1326a facing the one side of the first permanent magnet 134a, The second inclination angle ω2 is defined as an angle between one side of the second permanent magnet 134b and one side of the second magnetic flux wall 1326b facing the one side of the second permanent magnet 134b.

The first inclination angle ω1 may be smaller than the second inclination angle ω2. For example, as shown in FIG. 10 , the barrier angle (or the first arc length) θ1 of the first magnetic flux wall 1326a is greater than the barrier angle (or the second arc length) θ2 of the second magnetic flux wall 1326b. When formed to be large, the first inclination angle ω1 is formed to be smaller than the second inclination angle ω2.

This means that the distance t1 between the outer surface of the first magnetic flux wall 1236a and the outer peripheral surface of the rotor core 132 is the distance t2 between the outer surface of the second magnetic flux wall 1326b and the outer peripheral surface of the rotor core 132 . ) and, consequently, if the barrier angle θ1 of the first magnetic flux wall 1326a is greater than the barrier angle θ2 of the second magnetic flux wall 1326b, the first inclination angle ω1 is the second inclination angle ω2 ) should be smaller than

As described above, when the first inclination angle ω1 is greater than the second inclination angle ω2 or the second inclination angle ω2 is greater than the first inclination angle ω1 on the same layer of the rotor core, as described above, The first magnetic flux wall 1326a and the second magnetic flux wall 1326b are formed in an asymmetrical shape. Accordingly, the torque ripple can be reduced because the magnetic flux wall of each stage is arranged to be twisted while the torque is hardly reduced by effectively suppressing the leakage magnet.

11 and 12 are graphs showing the torque change and the torque ripple change of the electric motor to which the rotor core is applied according to the present embodiment. 11 and 12 show that in the embodiment of FIGS. 5A and 5B described above, the barrier angle of the first magnetic flux wall is 3.75 degrees, the barrier angle of the second magnetic flux wall is 1 degree, and the arc angle ratio (β/α) is 0.85. It is the data of the experiment of torque change and torque ripple change for each case.

Referring to FIG. 11 , even if the rotor core 132 according to the present embodiment is applied, it can be seen that almost no torque change occurs.

That is, when the torque in the case where the first magnetic flux wall 1326a and the second magnetic flux wall 1326b of the rotor core 132 are all symmetrical along the axial direction (structure before application) is 100%, the rotor core It can be seen that when the first magnetic flux wall 1326a and the second magnetic flux wall 1326b of (132) are partially asymmetric along the axial direction (structure after application), the torque is almost 100%.

This is the arc length of the entire first magnetic flux wall 1326a and the second magnetic flux wall 1326b even though the first magnetic flux wall 1326a and the second magnetic flux wall 1326b of the rotor core 132 are asymmetric as in the present embodiment. (Barrier angle) L1 is formed in the same way.

That is, when the rotor core 132 is formed in two stages and the arc length L2 of the magnetic flux wall 1326 located at the second stage S2 is shortened, the arc of the magnetic flux wall 1326 located at the first stage S1 is shortened. As the length L1 increases, the arc length of the total magnetic flux wall 1326 is secured to be substantially the same as that of the conventional rotor core. In the conventional rotor core, the arc length of the entire magnetic flux wall is uniformly formed. Accordingly, the leakage magnetic flux in the rotor core 1326 can be suppressed in the same manner as in the prior art, so that the torque is not reduced.

On the other hand, when the first magnetic flux wall 1326a and the second magnetic flux wall 1326b of the rotor core 132 are asymmetrically formed as in the present embodiment, the torque ripple is reduced while forming a structure such as a kind of skew. . 12 , this can be confirmed. When the torque ripple in the structure before application is 100%, it can be seen that the torque ripple in the structure after application is reduced to about 87%. Accordingly, the torque ripple can be reduced by approximately 13% in the structure after application.

On the other hand, if there is another embodiment of the arrangement of the magnet accommodating portion including the permanent magnet is as follows.

That is, in the above-described embodiment, the magnet accommodating part to which the permanent magnet is coupled is formed in a "V" shape by a set of two pairs. "It may be formed into a shape.

13 is a schematic diagram showing another example of a rotor core according to the present embodiment. Referring to FIG. 13 , the magnet accommodating part of this embodiment may be divided into a first group (A) and a second group (B), and the first group (A) and the second group (B) may be arranged in a radial direction. . In the first group (A), the first magnet accommodating part 1324a and the second magnet accommodating part 1324b are arranged in a "V" shape, and in the second group (B), the third magnet accommodating part 1324c and the second magnet accommodating part 1324c The four magnet accommodating part 1324d may also be arranged in a “V” shape.

The first magnet accommodating part 1324a and the second magnet accommodating part 1324b constituting the first group A are provided symmetrically about the radial center line CL as in the above-described embodiment, and the second group ( The third magnet accommodating part 1324c and the fourth magnet accommodating part 1324d constituting B) may also be provided symmetrically with respect to the radial center line CL.

However, the first magnet accommodating part 1324a and the second magnet accommodating part 1324b constituting the first group (A) are disposed on the inner periphery, and the third magnet accommodating part 1324c constituting the second group (B). And the fourth magnet accommodating portion (1324d) is disposed on the outer peripheral side. Accordingly, the first group (A) and the second group (B) may be disposed in the radial direction as described above.

In addition, a first magnetic flux wall 1326a may extend to an outer peripheral end of the first magnet accommodating portion 1324a, and a second magnetic flux wall 1326b may extend to an outer peripheral end of the second magnet accommodating portion 1324b. . The first magnetic flux wall 1326a and the second magnetic flux wall 1326b may be formed to extend in a direction toward the radial center line CL, respectively, as in the above-described embodiment.

Also in this embodiment, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b may be formed symmetrically or asymmetrically with respect to the radial center line CL on the same layer. However, along the axial direction, at least a portion may be formed asymmetrically.

For example, when the rotor core 132 is divided into an even number of stages along the axial direction, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b are formed in a symmetrical shape on the same layer, but in the axial direction Accordingly, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b at both ends may be formed in an asymmetrical shape. This may refer to FIGS. 5A and 5B .

In addition, when the rotor core 132 is divided into an odd number of stages, the first magnetic flux wall 1326a and the second magnetic flux wall 1326b are at least partially formed in an asymmetrical shape on the same layer, and each The first magnetic flux wall 1326a and the second magnetic flux wall 1326b at the end may be formed in an asymmetrical shape. This may refer to FIGS. 6A to 6C .

Since the specific shapes of the first magnetic flux wall 1326a and the second magnetic flux wall 1326b as described above and their effects are similar to those of the above-described embodiment, a description thereof is as described above in FIGS. 5A and 5B or It is replaced with the description in Figs. 6A to 6C.

On the other hand, if there is another embodiment of the arrangement of the magnet accommodating portion including the permanent magnet is as follows.

That is, in the above embodiment, the magnet accommodating part to which the permanent magnet is coupled is formed in a "V" shape, but in some cases, the magnet accommodating part may be formed in a "▽" shape.

14 is a schematic diagram showing another example of a rotor core according to the present embodiment. 14, in the rotor core 132 according to this embodiment, three magnet accommodating parts 1324a, 1324b, and 1324e may be arranged in a ▽" shape. Each magnet accommodating part 1324a ( Permanent magnets 134a, 134b, and 134c may be respectively inserted into 1324b and 1324e.

Also in this case, the first magnet accommodating part 1324a and the second magnet accommodating part 1324b provided on both left and right sides of the radial center line CL may be formed symmetrically with respect to the radial center line CL.

In addition, a first magnetic flux wall 1326a may be formed on an outer peripheral end of the first magnet accommodating portion 1324a and a second magnetic flux wall 1326b may be formed on an outer peripheral end of the second magnet accommodating portion 1324b. The arrangement of the first magnetic flux wall 1326a and the second magnetic flux wall 1326b may be formed symmetrically or asymmetrically on the same layer as in the above-described embodiments, and may be formed to be at least partially asymmetrical along the axial direction.

The arrangement of the first magnetic flux wall 1326a and the second magnetic flux wall 1326b may be different depending on the number of stages of the rotor core. Since this is similar to the other embodiments described above, the description thereof is replaced with the description in FIGS. 5A and 5B or 6A to 6C as described above.

In the foregoing, specific embodiments of the present invention have been shown and described. However, since the present invention can be embodied in various forms without departing from the spirit or essential characteristics thereof, the embodiments described above should not be limited by the content of the detailed description.

In addition, even the embodiments not listed in the detailed description described above should be broadly interpreted within the scope of the technical spirit defined in the appended claims. And, all changes and modifications included within the technical scope of the claims and their equivalents should be included by the appended claims.

11: Vehicle body 12: Battery
13: wheel 100: electric motor
110: case 111: end cover
120: stator 122: stator core
122a: slot 122b: teeth
124: stator coil 126: rotor receiving part
130: rotor 132: rotor core
1322: rotation shaft coupling portion 1324: magnet receiving portion
1324a: first magnet accommodating part 1324b: second magnet accommodating part
1326: magnetic flux wall 1326a: first magnetic flux wall
1326b: second magnetic flux wall 1328a: inner peripheral side bridge portion
1328b: outer periphery bridge portion 134: permanent magnet
134a: first permanent magnet 134b: second permanent magnet
136: axis of rotation CL: radial centerline
CL11: axial center line CL11', CL11": first axial center line
CL12', CL12": 2nd axial centerline O: Rotor center
O': center of the first magnetic flux wall O": center of the second magnetic flux wall
α: first extreme whistle angle β: second extreme whistle angle
θ1: barrier angle (arc length) of the first magnetic flux wall
θ1: barrier angle (arc length) of the second magnetic flux wall
δ: slit opening angle ω1: inclination angle of the first magnetic flux wall
ω2: angle of inclination of the second magnetic flux wall

Claims (18)

a stator having a stator core having a plurality of slots formed along a circumferential direction, and a stator coil wound around the slots of the stator core; and
A rotor having a rotor core rotatably disposed with a predetermined gap with respect to the stator and having a plurality of magnet accommodating portions formed along a circumferential direction, and a plurality of permanent magnets accommodated in the plurality of magnet accommodating portions; includes,
A magnetic flux barrier is formed at an outer end of the plurality of magnet accommodating parts, and the magnetic flux wall is at least partially formed differently according to an axial position of the rotor core. According to claim 1,
The arc length of the magnetic flux wall extending in the circumferential direction with respect to one side of the permanent magnet is,
An electric motor in which at least a part is formed differently according to an axial position of the rotor core. According to claim 1,
The inclination angle of the magnetic flux wall defined as the angle between one side of the permanent magnet and the magnetic flux wall facing it is,
An electric motor in which at least a part is formed differently according to an axial position of the rotor core. According to claim 1,
The rotor core is divided into a plurality of stages along the axial direction, and at least one first symmetrical stage in which both magnetic flux walls facing each other are symmetrical with respect to a radial center line are included. 5. The method of claim 4,
The other end adjacent to the first symmetrical end forms a second symmetrical end in which both magnetic flux walls facing each other with respect to the radial center line are symmetrical to each other,
The magnetic flux wall of the second symmetrical stage is formed differently from the magnetic flux wall of the first symmetrical stage. 6. The method of claim 5,
The flux barrier pole angle, defined as the shortest distance between the opposite magnetic flux walls, is
Motors that are identical in the same stage and are formed differently in different stages. 6. The method of claim 5,
The magnetic flux wall inclination angle defined as the angle between one side of the permanent magnet and the one side of the magnetic flux wall facing it is,
Motors that are identical in the same stage and are formed differently in different stages. According to claim 1,
The rotor core is divided into a plurality of stages along the axial direction, and includes at least one first asymmetric stage in which both magnetic flux walls are asymmetric at the same stage based on a radial center line passing between the two facing magnetic flux walls. electric motor. 9. The method of claim 8,
The other end adjacent to the first asymmetric end forms a symmetric end in which both magnetic flux walls facing each other with respect to the radial center line are symmetrical to each other,
The opposite end of the first asymmetric end with the symmetric end therebetween forms a second asymmetric end in which both magnetic flux walls facing each other with respect to the radial center line are asymmetric,
The magnetic flux wall of the first asymmetric end and the magnetic flux wall of the second asymmetric end are symmetrical with respect to the radial center line. 10. The method of claim 9,
An electric motor in which the flux barrier pole arc angle, defined as the shortest distance between the opposite magnetic flux walls, is formed equally across all stages. According to claim 1,
The rotor core is divided into even-numbered stages along the axial direction, and in the even-numbered stages, magnetic flux walls facing each other with respect to a radial center line are symmetrical at the same stage. 12. The method of claim 11,
In the even-numbered stages, different stages have different circumferential distances between the magnetic flux walls. 13. The method of claim 12,
An electric motor in which the length in the circumferential direction of the magnetic flux wall of the different stages is different from each other. According to claim 1,
The rotor core is divided into odd-numbered stages along the axial direction, and the odd-numbered stages have stages in which magnetic flux walls facing each other with respect to a radial centerline are asymmetrical at the same stage. 15. The method of claim 14,
An electric motor in which magnetic flux walls facing each other with respect to a radial centerline are alternately provided with symmetrical and asymmetrical ends along the axial direction at the same stage. According to claim 1,
Magnetic flux defined as an angle between a first end line connecting the end of the magnetic flux wall at the center of the rotor core and a second end line connecting the edge of the permanent magnet facing the end of the magnetic flux wall at the center of the rotor core The wall barrier angle θ is,
An electric motor that satisfies {(opening angle of slot × 0.5 times) ≤ θ ≤ (360/number of slots/2)}. According to claim 1,
When the polar arc between the permanent magnets facing each other is a first pole arc angle (α), and the polar arc angle between the magnetic flux walls facing each other is a second pole arc angle (β), the second polar arc angle is,
A motor that satisfies β={(0.75~1.0)×α}. vehicle body;
a plurality of wheels operably provided on the vehicle body;
a battery provided in the vehicle body; and
Including; an electric motor connected to the battery and providing a driving force to the plurality of wheels,
The electric vehicle is an electric vehicle comprising the electric motor according to any one of claims 1 to 17.

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