CONSEQUENT POLE-TYPE INTERIOR PERMANENT MAGNET SYNCHRONOUS MOTOR

A consequent pole type interior permanent magnet synchronous motor includes a stator; a rotor rotatable inside the stator; a plurality of permanent magnets inside the rotor; and a plurality of slits formed along a radial direction of the rotor such that the plurality of slits are each between a respective two adjacent permanent magnets among the plurality of permanent magnets. The number of a plurality of consequent poles formed in the rotor by the plurality of permanent magnets is smaller than the number of the plurality of permanent magnets.

BACKGROUND

Field

The disclosure relates to a consequent poly type interior permanent magnet motor having consequent poles.

Description of Related Art

Generally, in an interior permanent magnet motor, a plurality of permanent magnets are embedded inside a rotor at regular intervals.

A consequent pole type interior permanent magnet motor may be used to reduce the number of permanent magnets used in a rotor of an interior permanent magnet motor.

The consequent pole type interior permanent magnet motor may reduce the number of permanent magnets by replacing some of the permanent magnets of the general interior permanent magnet motor with the consequent poles using a phenomenon in which the iron core of the rotor between two adjacent permanent magnets is magnetized, that is, the phenomenon in which the consequent pole is formed in the rotor.

FIG.1is a view illustrating a consequent pole type interior permanent magnet motor according to the prior art.

Referring toFIG.1, the consequent pole type interior permanent magnet motor100according to the prior art is a 6-pole motor, and a rotor includes three permanent magnets and three consequent poles formed between the three permanent magnets.

The general 6-pole interior permanent magnet motor includes 6 permanent magnets. Therefore, the number of permanent magnets112used in the consequent pole type interior permanent magnet motor100according to the prior art is reduced by half compared to that of the general interior permanent magnet motor.

However, the consequent pole type interior permanent magnet motor100according to the prior art has the advantage of reducing the amount of permanent magnets112used by reducing the number of permanent magnets112by half, but due to the structure in which the permanent magnets having the same polarity are disposed in the rotor, a phenomenon in which a rotating shaft coupled to the rotor is magnetized occurs. At this time, both ends of the rotating shaft are magnetized with the same polarity.

The magnetization of the rotating shaft makes it easy for metal foreign substances to be attached to the rotating shaft in the motor assembly process, and this may adversely affect the quality and reliability of the motor. Therefore, the magnetization of the rotating shaft needs to be minimized as much as possible.

In addition, the consequent pole type interior permanent magnet motor according to the prior art generates a large second harmonic component of back electromotive force EMF due to structural characteristics. The harmonic component of the back EMF is a factor that affects iron loss and increases loss of the motor, thereby reducing the output and efficiency of the motor.

SUMMARY

According to an aspect of the disclosure, a consequent pole type interior permanent magnet motor may include a stator; a rotor rotatable inside the stator; a plurality of permanent magnets inside the rotor; and a plurality of slits formed in a radial direction of the rotor such that the plurality of slits are each between a respective two adjacent permanent magnets among the plurality of permanent magnets. A number of consequent poles formed in the rotor by the plurality of permanent magnets may be less than a number of the plurality of permanent magnets.

Each of the plurality of slits may be centered between the respective two adjacent permanent magnets.

Each of the plurality of slits may be formed so that an end thereof adjacent to an outer circumferential surface of the rotor passes through a region of the rotor between the respective two adjacent permanent magnets.

Each of the plurality of slits may be formed such that a first end adjacent to an outer circumferential surface of the rotor and a second end adjacent to a shaft hole of the rotor are blocked.

The first end of each of the plurality of slits may be located closer to the outer circumferential surface of the rotor than one end of each of the respective two adjacent permanent magnets.

Each of the plurality of slits may be formed in a rectangular cross-section.

An electrical angle of a slit pitch of each of the plurality of slits may satisfy 0°<Ps_elec<34.8°.

A width Wb of a bridge between one end of each of the plurality of slits and the outer circumferential surface of the rotor may satisfy a relationship as follows:

Wherein Ct is a thickness of a rotor core (0.25 mm˜0.35 mm), Wb is the width of the bridge, Sl is a length of the slit, Do is an outer diameter of the rotor core, and Di is an inner diameter of the rotor core.

A width Wr of a rib between one side surface of each of the plurality of slits and one end of a magnet insertion hole of the rotor may satisfy a relationship as follows:

Wherein Ct is a thickness of a rotor core (0.25 mm to 0.35 mm), Wr is a width of the rib, Sl is a length of the slit, Do is an outer diameter of the rotor core, and Di is an inner diameter of the rotor core.

The stator may be a concentrated winding type.

The respective two adjacent permanent magnets may be symmetrically arranged with respect to a corresponding slit among the plurality of slits.

The two adjacent permanent magnets may have different polarities from each other.

A flux barrier may be at both ends of each of the plurality of permanent magnets.

The plurality of permanent magnets may be formed in a plate shape or a C-type.

The plurality of permanent magnets may be formed of ferrite or rear earth element.

According to another aspect of the disclosure, a consequent pole type interior permanent magnet motor may include a stator formed in a concentrated winding type; a rotor rotatable inside the stator; a plurality of permanent magnets inside the rotor; a rotating shaft at a center of the rotor; and a plurality of slits formed in a radial direction of the rotor. The plurality of slits may be formed such that the plurality of slits are each centered between a respective two adjacent permanent magnets among the plurality of permanent magnets.

DETAILED DESCRIPTION

Various embodiments described below are shown by way of example to assist understanding of the disclosure, and it should be understood that the disclosure may be variously modified and implemented differently from the embodiments described herein. However, in the following description of the disclosure, when it is determined that a detailed description of a related known function or components may unnecessarily obscure the gist of the disclosure, the detailed description and specific illustration thereof will be omitted. Further, in the accompanying drawings, the dimensions of some components may be arbitrarily exaggerated and not drawn to scale in order to aid understanding of the disclosure.

The terms ‘first’, ‘second’, etc. may be used to describe diverse components, but the components are not limited by the terms. The terms may only be used to distinguish one component from the others. For example, without departing from the scope of the disclosure, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

The terms used in embodiments of the disclosure may be construed as commonly known to those skilled in the art unless otherwise defined.

Further, the terms ‘leading end’, ‘rear end’, ‘upper side’, ‘lower side’, ‘top end’, ‘bottom end’, etc. used in the disclosure are defined with reference to the drawings. However, the shape and position of each component are not limited by the terms.

Hereinafter, a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure will be described in detail with reference to the accompanying drawings.

The disclosure has been developed in order to overcome the above drawbacks and other problems associated with the conventional arrangement. An aspect of the disclosure relates to a consequent pole type interior permanent magnet motor capable of reducing magnetization of a rotating shaft and second harmonics of back electromotive force.

With a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure having the above-described structure, an amount of magnetization of a rotating shaft and a second harmonic component of a back electromotive force may be reduced.

In addition, with a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure, an unbalance between an amount of magnetic flux linked to a stator by a permanent magnet and an amount of magnetic flux linked to the stator by a consequent pole may be resolved and a back electromotive force may be increased.

FIG.2is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure.FIG.3is a cross-sectional view illustrating a rotor of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure.FIG.4is a cross-sectional view illustrating a rotor of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure without permanent magnets.

Referring toFIG.2, a consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure may include a stator10and a rotor20.

The stator10may include a yoke portion11having a cylindrical inner surface and a plurality of teeth13protruding from the inner surface of the yoke portion11toward the center of the stator10.

The plurality of teeth13are disposed at regular intervals in the circumferential direction of the inner surface of the stator10, and a plurality of slots in which coils15are accommodated may be formed between the plurality of teeth13. The coils15are intensively wound around each of the plurality of teeth13. In other words, the stator10may be formed as a concentrated winding type stator.

The rotor20is formed in a cylindrical shape and is rotatably disposed concentrically with the stator10. The rotor20may be disposed to rotate about the center of the stator10at a predetermined distance from the leading ends14of the teeth13of the stator10. To this end, a shaft hole21into which a rotating shaft50(seeFIG.9) is disposed may be formed at the center of the rotor20.

A plurality of permanent magnets30are disposed inside the rotor20. In detail, the plurality of permanent magnets30are disposed between the outer circumferential surface of the rotor20and the shaft hole21.

As illustrated inFIGS.2and3, the plurality of permanent magnets30may be formed in an I-shape, that is, a flat plate shape. In addition, the plurality of permanent magnets30may be formed of a rare earth element, for example, neodymium Nd. In another embodiment, the plurality of permanent magnets may be formed of ferrite.

The rotor20is formed of an iron core, and as illustrated inFIG.4, a plurality of magnet insertion holes23in which the permanent magnets30are disposed may be formed in the iron core of the rotor20in the circumferential direction of the rotor20. The plurality of magnet insertion holes23may be formed in an I-shape to correspond to the shape of the permanent magnets30.

The plurality of permanent magnets30are arranged in the rotor20so that two adjacent permanent magnets30-1and30-2have different polarities. When the plurality of permanent magnets30including a plurality of permanent magnet sets in which two permanent magnets30-1and30-2having different polarities constitute one permanent magnet set are disposed in the rotor20, the iron core portion of the rotor20between the two permanent magnet sets is magnetized to form a plurality of consequent poles (iron core poles)22in the rotor20.

In detail, the iron core portion between two permanent magnets30-1and30-1or30-2and30-2that are far apart from each other and have the same polarity is magnetized to form the consequent pole22. For example, when the plurality of permanent magnets30are arranged in the order of an N-pole permanent magnet30-1, an S-pole permanent magnet30-2, the iron core portion22, an S-pole permanent magnet30-2, an N-pole permanent magnet30-1, and the iron core portion22, the portion22of the rotor20between two permanent magnets30-1and30-1or30-2and30-2having the same polarity, that is, the portion of the iron core is magnetized with a polarity opposite to that of the two permanent magnets30-1and30-1or30-2and30-2. An example in which the rotor20is magnetized is shown inFIG.5.

FIG.5is a view illustrating a magnetized state of a rotor of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure.

In the case of the embodiment shown inFIG.5, two N-pole permanent magnets30-1and two S-pole permanent magnets30-2are inserted into the rotor20. Therefore, the iron core portion22between the N-pole permanent magnet30-1and the N-pole permanent magnet30-1is magnetized to the S-pole to form an S pole consequent pole, and the iron core portion22between the S-pole permanent magnet30-2and the S-pole permanent magnet30-2is magnetized to the N-pole to form an N pole consequent pole. In other words, the iron core portion22between the two permanent magnets30-1and30-1or30-2and30-2that are far apart from each other and have the same polarity may be magnetized with a polarity different from that of the two adjacent permanent magnets, thereby forming the consequent pole.

Therefore, when a permanent magnet having different polarity is not disposed between two permanent magnets30having the same polarity in the rotor20, the same magnetic field as that of the interior permanent magnet motor according to the prior art in which the permanent magnet having different polarity is disposed between two permanent magnets30having the same polarity may be formed.

The number of magnetic poles (or the number of poles) of the rotor20includes the number of permanent magnets30and the number of consequent poles22. For example, as illustrated inFIG.5, when four permanent magnets30are disposed in the rotor20, two consequent poles22are formed between the two permanent magnets30having the same polarity, so that the number of magnetic poles of the rotor20is six (6).

Therefore, in the consequent pole type interior permanent magnet motor1according to this embodiment, the number of consequent poles22is smaller than the number of permanent magnets30disposed in the rotor20. Because the rotor20of the six pole interior permanent magnet motor1illustrated inFIG.5includes four permanent magnets30and two consequent poles22, the number of permanent magnets30is ⅔ of the number of magnetic poles of the rotor20, and the number of consequent poles22is ⅓ of the number of magnetic poles of the rotor20.

In addition, the consequent pole type interior permanent magnet motor1according to this embodiment may be formed so that a pole arc angle satisfies the following relationship.

Here, θ is the polar arc angle, and P is the number of magnetic poles of the rotor.

Accordingly, the polar arc angle of the 6-pole consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure as illustrated inFIG.5is 60 degrees.

Referring toFIGS.3and4again, the rotor20may include a plurality of slits40.

Each of the plurality of slits40may be formed between two adjacent permanent magnets30-1and30-2among the plurality of permanent magnets30in the radial direction of the rotor20.

Two permanent magnets30-1and30-2having different polarities may be disposed with the slit40interposed therebetween. The distance between the two adjacent permanent magnets30-1and30-2having different polarities and having the slit40interposed therebetween may be shorter than the distance between the two permanent magnets30-1and30-1or30-2and30-2having the same polarity.

The slit40may be formed to be located in the center between two adjacent permanent magnets30-1and30-2. For example, the slit40may be formed between two adjacent magnet insertion holes23. The two magnet insertion holes23may be formed to be line symmetric with respect to the slit40. Accordingly, the two permanent magnets30-1and30-2inserted into the magnet insertion holes23are also line symmetric with respect to the slit40.

A flux barrier24may be provided at both ends of the magnet insertion hole23adjacent to the outer circumferential surface20aof the rotor20. Thus, the flux barrier24may be provided between the slit40and one end of the permanent magnet30.

The flux barrier24may be formed in a void that is adjacent to the outer circumferential surface20aof the rotor20and provided in the circumferential direction of the rotor20. In other words, the flux barrier24may have a predetermined width and length and may be formed along the outer circumferential surface20aof the rotor20. The flux barrier24may be not open toward the leading end of the stator10.

The flux barrier24may be formed to communicate with the magnet insertion hole23. Therefore, when the permanent magnet30is inserted into the magnet insertion hole23, both ends of the permanent magnet30are located in the flux barriers24, respectively.

The slit40is formed in the radial direction of the rotor20, and may include a first end40aadjacent to the outer circumferential surface20aof the rotor20and a second end40badjacent to the shaft hole21of the rotor20. In other words, the first end40aof the slit40may be formed to be located closer to the outer circumferential surface20aof the rotor20than one end of each of the two adjacent permanent magnets.

The first end40aof the slit40may be formed to be blocked without being opened to the outer circumferential surface20aof the rotor20, and the second end40bof the slit40may be formed to be blocked without being opened to the inner circumferential surface20bof the rotor20. Thus, there may be the iron core forming the outer circumferential surface20aof the rotor20between the first end40aof the slit40and the outer circumferential surface20aof the rotor20. In addition, there may be the iron core forming the inner circumferential surface20bof the rotor20between the second end40bof the slit40and the inner circumferential surface20bof the rotor20.

The first end40aof the slit40may be formed to penetrate the rotor region between the two adjacent permanent magnets30-1and30-2. That is, the slit40may be formed to penetrate the iron core region of the rotor20between the two adjacent magnet insertion holes23. In other words, the first end40aof the slit40may be located in the same position as the side surface of the magnet insertion hole23adjacent to the outer circumferential surface20aof the rotor20or may be closer to the outer circumferential surface20aof the rotor20rather than the side surface of the magnet insertion hole23. Therefore, the side surface of the slit40faces one end of the magnet insertion hole23.

When the flux barrier24is provided at one end of the magnet insertion hole23, the side surface of the slit40may face the flux barrier24.

The slit40may be formed in a long and narrow shape. For example, the slit40may be formed in a rectangular cross-section. As another example, the slit40may be formed in a long elliptical shape, track shape, and the like. Here, the length of the slit40refers to the length of the direction facing the outer circumferential surface20aof the rotor20from the shaft hole21of the rotor20.

When the slit40is located at the center between the two adjacent permanent magnets30and formed to have a length that can penetrate the range of the rotor20between the two adjacent permanent magnets30, the magnetic resistance increases so that the magnetic flux leaked between the two adjacent permanent magnets30may be minimized.

Hereinafter, the dimensional relationship between a bridge41and a rib42provided between the slit40and the magnet insertion hole23will be described in detail with reference toFIG.3.

InFIG.3, the iron core region between the first end40aof the slit40and the outer circumferential surface20aof the rotor20is referred to as the bridge41, and the iron core region between one side surface of the slit40and one end of the flux barrier24of the magnet insertion hole23is referred to as the rib42. When the flux barrier24is not provided at one end of the magnet insertion hole23, the iron core region between the one side surface of the slit40and one end of the magnet insertion hole23may be referred to as the rib42.

In order to minimize the magnetic flux leaked between the two adjacent permanent magnets30, the first end40aof the slit40may be formed to be as close as possible to the outer circumferential surface20aof the rotor20, and the length of the slit40may be formed as long as possible.

For example, the first end40aof the slit40adjacent to the outer circumferential surface20aof the rotor20may be formed to be closer to the outer circumferential surface20aof the rotor20than the lower corners P1and P1of the two adjacent permanent magnets30.

In detail, the first end40aof the slit40adjacent to the outer circumferential surface20aof the rotor20may be formed to be located at the same position as a first intersection point Pb where a virtual straight line PL1connecting the lower corners P1and P1of the two adjacent permanent magnets30and a virtual straight line L1dividing the slit40into two halves in the longitudinal direction intersect at right angles, or closer to the outer circumferential surface20aof the rotor20than the first intersection point Pb. Here, the lower corner P1of the permanent magnet30refers to the corner of the permanent magnet30closest to the outer circumferential surface20aof the rotor20among the two corners of the permanent magnet30adjacent to the side surface of the slit40.

Therefore, the width Wb of the bridge41, which is the distance between the first end40aof the slit40and the outer circumferential surface20aof the rotor20, may be formed to satisfy the following relationship.

Here, Lb is the distance between the first intersection point Pb and the outer circumferential surface20aof the rotor20, and Wb is the width of the bridge41.

The width Wb of the bridge41may be formed as narrow as possible in order to maximize efficiency of the motor by minimizing magnetic flux leakage. Therefore, the width Wb of the bridge41may be determined to be as narrow as possible in consideration of the thickness of the material forming the rotor core and the manufacturing process of the rotor core.

For example, the width Wb of the bridge41may be formed to be greater than the thickness of the material and less than 0.4 mm in consideration of the thickness of the material forming the rotor core and the workability of the punching (pressing) process of the rotor core. In this case, Lb is 0.4 mm or more.

In other words, the width Wb of the bridge41may be formed to satisfy the following relationship.

Here, Ct is the thickness of the rotor core sheet, and Wb is the width of the bridge41.

Because an electrical steel sheet may be used as the rotor core, the rotor core sheet may have a thickness Ct of 0.25 mm to 0.35 mm.

As an example, when the thickness Ct of the rotor core sheet is 0.35 mm, the bridge width Wb may be 0.4 mm in consideration of the press process of the rotor core.

However, when the bridge width Wb is 0.4 mm, the thickness of the rotor core sheet is 0.35 mm. When the thickness of the rotor core sheet is 0.35 mm or more, the bridge width Wb may exceed 0.4 mm. For example, when the thickness of the rotor core sheet is 0.5 mm, the bridge width Wb may be 0.55 mm.

Meanwhile, when the width Wb of the bridge41is determined as described above, the upper limit of the slit length Sl may be determined as follows.

Here, Sl is the length of the slit40, Do is the outer diameter of the rotor core, Di is the inner diameter of the rotor core, and Wb is the width of the bridge41.

In addition, in order for the slit40to block magnetic flux leaking between two adjacent permanent magnets30, the slit40may be formed to have a predetermined length or more.

For example, the second end40bof the slit40adjacent to the inner circumferential surface20bof the rotor20may be formed to be located at the same position as a second intersection point Ps where a virtual straight line PL2connecting the upper corners P2and P2of the two adjacent permanent magnets30and the virtual straight line L1dividing the slit40into two halves in the longitudinal direction intersect at a right angle, or closer to the center O of the rotor20than the second intersection point Ps. Here, the upper corner P2of the permanent magnet30refers to the corner of the permanent magnet30farthest from the outer circumferential surface20aof the rotor20among the two corners of the permanent magnet30farthest from the side surface of the slit40.

Therefore, the lower limit of the slit length may be determined as follows.

Here, Sl is the length of the slit40, Ds is the distance from the center O of the rotor to the second intersection point Ps, and Wb is the width of the bridge41.

Therefore, the length of the slit40may be determined as follows.

When the bridge width Wb and the slit length Sl are determined as described above, the magnetic flux leaking between two adjacent permanent magnets30may be minimized, thereby increasing the efficiency of the motor.

The length Sl of the above-described slit40may be appropriately determined according to the size of the rotor core.

As an example, when the outer diameter Do of the rotor core is 61.8 mm, the inner diameter Di of the rotor core is 24.5 mm, and the bridge width Wb is 0.4 mm, the length Sl of the slit may be 17.85 mm.

In addition, the width Wr of the rib42between the one side surface of the slit40and one end of the magnet insertion hole23of the rotor20may be formed to satisfy the following relationship.

Here, Ct is the thickness of the rotor core sheet (0.25 mm to 0.35 mm), and Wr is the width of the rib42.

The width Wr of the rib may be equal to or wider than the width Wb of the bridge. As an example, when the bridge width Wb is 0.4 mm, the rib width Wr may be 0.4 mm.

When the width Wr of the rib42is determined as described above, the upper limit of the slit length may be determined as follows.

Here, Sl is the length of the slit40, Do is the outer diameter of the rotor core, Di is the inner diameter of the rotor core, and Wr is the width of the rib42.

When the width W of the slit40increases beyond a certain value in the limited area of the rotor20, the length of the permanent magnet30decreases, so the amount of the magnet decreases. Accordingly, the amount of magnetic flux linking from the magnetic poles to the void may decrease, and the back electromotive force may decrease due to the decrease in the total amount of magnetic flux in the void. Therefore, the width W of the slit40may be limited.

The rotor20may have a circular cross-section. Alternatively, the cross-section of the rotor20may have a shape deformed from circular. Hereinafter, the relationship between the width W of the slit40and the permanent magnet30will be described in detail with reference toFIG.6.

FIG.6is a view for explaining a relationship between a slit width and a magnet pole pitch of a rotor of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure.

InFIG.6, an angle between a first straight line L1connecting the center O of the rotor20and the center of the width W of the slit40and a second straight line L2connecting the center O of the rotor20and the corner of the first end40aof the slit40is referred to as a slit pitch Ps, and an angle between the first straight line L1and a third straight line L3connecting the center O of the rotor20and the second end23bof the magnet insertion hole23is referred to as a magnetic pole pitch Pm. Here, the first end23aof the magnet insertion hole23refers to one end of the magnet insertion hole23that is located closest to the slit40, and the second end23brefers to the other end of the magnet insertion hole23that is located farthest from the slit40.

Because the mechanical angle of the slit pitch Ps and the mechanical angle of the magnetic pole pitch Pm change when the number of poles of the motor is changed, the mechanical angles of the slit pitch Ps and the magnetic pole pitch Pm may be converted into electrical angles, respectively, so that they are not related to changes in the number of poles of the motor.

FIG.7is a table showing results obtained by simulating a change in back electromotive force according to a slit pitch of a rotor in a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure by using a finite element method.

InFIG.7, Ps_mech and Pm_mech represent the mechanical angles of the slit pitch Ps and the magnetic pole pitch Pm, respectively. Ps_elec is a conversion of the mechanical angle of the slit pitch Ps into an electrical angle, and Pm_elec is a conversion of the mechanical angle of the magnetic pole pitch Pm into an electrical angle.

Referring toFIG.7, when there is no slit40, that is, when the mechanical angle Ps_mech and the Ps_elec of the slit pitch Ps are zero degrees (0°), the back electromotive force is 46.45V. As the slit pitch Ps increases, the back electromotive force increases, and the back electromotive force becomes maximum when the electrical angle of the slit pitch Ps is 14.1°.

As the slit pitch Ps continues to increase, the length of the permanent magnet30decreases, so that the back electromotive force gradually decreases. When the electrical angle Ps_elec of the slit pitch Ps is 34.8°, the back electromotive force becomes the same as that of the case without the slit. When the electrical angle Ps_elec of the slit pitch Ps exceeds 34.8°, the back electromotive force is smaller than that of the case without the slit40.

The change in the back electromotive force depending on a change in the electrical angle Ps_elec of the slit pitch Ps is shown inFIG.8.

FIG.8is a graph illustrating a relationship between a slit pitch of a rotor and back electromotive force in a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure.

The range of the slit pitch Ps in which the back electromotive force is greater than the back electromotive force when the rotor20does not have the slit40can be seen fromFIGS.7and8. In other words, when the electrical angle Ps_elec of the slit pitch Ps satisfies the following condition, the back electromotive force of the rotor20with slits40is greater than the back electromotive force of the rotor20without slits.

Therefore, the slit40of the rotor20may be formed to have a width W that can satisfy the range of the electrical angle Ps_elec of the slit pitch Ps as described above.

With the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure having the above structure, the amount of magnetization of the rotating shaft50may be reduced.

For example, as illustrated inFIGS.2and3, when two permanent magnets30-1and30-2having different polarities are disposed adjacent to each other, that is, when the plurality of permanent magnets30are arranged around the shaft hole21of the rotor20in order of N-pole permanent magnet30-1—S-pole permanent magnet30-2—iron core22—S-pole permanent magnet30-2—N-pole permanent magnet30-1—iron core22, a flux path is formed between two adjacent permanent magnets30-1and30-2having different polarities, so that the magnetic flux density inside the rotor20is reduced. Therefore, the magnetic flux leaked to the rotating shaft50(seeFIG.9) may be reduced.

A result in which the magnetic flux leaked to the rotating shaft50of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure is reduced compared to the consequent pole type interior permanent magnet motor according to the prior art is shown inFIG.9.

FIG.9is a graph comparing the amount of magnetization of a rotating shaft of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure and the amount of magnetization of a rotating shaft of a consequent pole type interior permanent magnet motor according to the prior art.

FIG.9shows a result of comparing magnetization amounts (surface Gauss) of both ends A and B of the rotating shaft50using a finite element method (FEM).

InFIG.9, the horizontal axis represents the length of the rotating shaft50, the vertical axis represents the surface Gauss, and its unit is Tesla T. Curve {circle around (1)} represents the amount of magnetization of the rotating shaft50of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure, and curve {circle around (2)} represents the amount of magnetization of the rotating shaft of the consequent pole type interior permanent magnet motor according to the prior art.

Referring toFIG.9, it can be seen that the magnetization amount of the rotating shaft50of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure is lower than the magnetization amount of the rotating shaft of the consequent pole type interior permanent magnet motor according to the prior art.

Table 1 below is a table showing the rate at which the surface Gauss at points A and B of the rotating shaft50of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure is reduced compared to the surface Gauss of the rotating shaft of the consequent pole type interior permanent magnet motor according to the prior art.

Referring toFIG.9and Table 1, it can be seen that the surface Gauss at both ends of the rotating shaft50of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure, that is, at points A and B is reduced by 85.3% and 81.3% compared to the surface Gauss at both ends of the rotating shaft of the consequent pole type interior permanent magnet motor according to the prior art, that is, at points A and B. Therefore, in the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure, the magnetization amount of the rotating shaft50may be lower than that of the rotating shaft of the consequent pole type interior permanent magnet motor according to the prior art.

In addition, in the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure having the structure shown inFIGS.2and3, the second harmonic component of the back electromotive force may be greatly reduced compared to the consequent pole type interior permanent magnet motor according to the prior art. The results are shown inFIG.10.

FIG.10is a view illustrating a second harmonic component of back electromotive force of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure and a second harmonic component of back electromotive force of a consequent pole type interior permanent magnet motor according to the prior art.

InFIG.10, the back electromotive force FFT refers to a frequency analysis of the back electromotive force using Fast Fourier Transform (FFT). The horizontal axis represents frequency and its unit is Hz, and the vertical axis represents amplitude and its unit is voltage (V).

Referring toFIG.10, in the case of the consequent pole type interior permanent magnet motor according to the prior art having a rotor110in which a plurality of permanent magnets112having the same polarity are arranged at regular intervals, the second harmonic component of the back electromotive force is present at about 15V (region C).

However, in the case of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure, there is almost no second harmonic component of the back electromotive force (region D). In other words, when two permanent magnets30having different polarities are disposed adjacent to each other, as in one embodiment of the disclosure, the second harmonic component of the back electromotive force may be greatly reduced.

In addition, as in the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure shown inFIGS.2and3, when the magnetic resistance of the iron core portion between the two adjacent permanent magnets30-1and30-2is increased by providing the slit40inside the rotor20, that is, between the two adjacent permanent magnets30-1and30-2, some of the magnetic flux generated inside the rotor20by the permanent magnets30is induced more in the direction of the consequent pole with low magnetic resistance, so that the amount of magnetic flux linking from the iron core portion where the consequent pole22is formed to the void may be increased. As a result, a magnetic unbalance between the amount of magnetic flux linked to the stator10by the permanent magnet30and the amount of magnetic flux linked to the stator10by the consequent pole22may be reduced.

In addition, in the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure, because the amount of magnetic flux linking from the consequent pole22to the stator10through the void increases, the total amount of magnetic flux in the void may increase. As a result, the back electromotive force may increase. Here, the total amount of magnetic flux in the void refers to the sum of the amount of magnetic flux linking from the permanent magnet30to the stator10through the void and the amount of magnetic flux linking from the consequent pole22to the stator10through the void.

FIG.11is a graph comparing back electromotive force of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure with back electromotive force of a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure in which slits are removed from a rotor.

InFIG.11, the horizontal axis represents time (s), and the vertical axis represents voltage (V). In addition, curve {circle around (1)} represents the back electromotive force of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure, and curve {circle around (2)} represents the back electromotive force of the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure without the slits.

Referring toFIG.11, the maximum back electromotive force of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure having the slit40is greater than the maximum back electromotive force of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure without the slit40. For example, inFIG.11, the back electromotive force of V1indicating the maximum back electromotive force when the slit40is present is 54.01V, and the back electromotive force of V2indicating the maximum back electromotive force when the slit40is not present is 48.39V.

In the above description, the permanent magnets30of the rotor20have an I-shape. However, the shape of the permanent magnets30is not limited thereto. Hereinafter, a consequent pole type interior permanent magnet motor using permanent magnets having different shapes according to an embodiment of the disclosure will be described with reference toFIGS.12and13.

FIG.12is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to another embodiment of the disclosure in which permanent magnets are V-shaped.

Referring toFIG.12, the rotor20′ of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure may include a plurality of permanent magnets30′, slits40, and a shaft hole21.

The plurality of permanent magnets30′ are disposed between the outer circumferential surface of the rotor20′ and the shaft hole21, and two adjacent permanent magnets30′ may be arranged symmetrically with respect to the slit40inside the rotor20′.

Each of the plurality of permanent magnets30′ may be formed in a V shape as illustrated inFIG.12. For example, two bar-shaped permanent magnets30′ may be arranged in a V shape. The bar-shaped permanent magnets30′ disposed in a V shape may have a width smaller than that of the I-shaped permanent magnets30of the motor1according to the above-described embodiment. The two bar-shaped permanent magnets30′ arranged in a V shape have the same polarity.

The plurality of permanent magnets30′ may be formed of a rare earth element. For example, the plurality of permanent magnets30′ may be formed neodymium Nd.

The rotor20′ is formed of an iron core, and a plurality of magnet insertion holes23′ in which the permanent magnets30′ are disposed may be formed in the iron core of the rotor20′ in the circumferential direction of the rotor20′. Each of the plurality of magnet insertion holes23′ may be formed in a V shape to correspond to the shape of the permanent magnets30′.

In the plurality of permanent magnets30′ disposed in the rotor20′, two adjacent permanent magnets30′ with a slit40interposed therebetween have different polarities. When the plurality of permanent magnets30′ including two permanent magnets30′ having different polarities as one set are disposed in the rotor20′, the iron core portions of the rotor20′ between the two sets is magnetized to form a plurality of consequent poles (iron core poles)22in the rotor20′. In other words, the iron core portion between two permanent magnets30′ that are spaced far apart from each other and have the same polarity is magnetized to form the consequent pole22.

The distance between the two permanent magnets30′ having different polarities with the slit40interposed therebetween is shorter than the distance between the two permanent magnets30′ having the same polarity.

The slits40and the shaft hole21of the rotor20′ according to this embodiment are the same as or similar to the slits40and the shaft hole21of the rotor20of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, detailed descriptions thereof are omitted.

FIG.13is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to another embodiment of the disclosure in which permanent magnets are U-shaped.

Referring toFIG.13, the rotor20″ of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure may include a plurality of permanent magnets30″, slits40, and a shaft hole21.

The plurality of permanent magnets30″ are disposed between the outer circumferential surface of the rotor20″ and the shaft hole21, and two adjacent permanent magnets30″ may be arranged symmetrically with respect to the slit40inside the rotor20″.

Each of the plurality of permanent magnets30″ may be formed in a U shape as illustrated inFIG.13. For example, three bar-type permanent magnets30″ may be arranged in a U shape. That is, two bar-shaped permanent magnets30″bmay be inclinedly disposed on the left and right sides of the central permanent magnet30″a. The bar-shaped permanent magnets30″ disposed in a U shape may have a width narrower than the width of the I-shaped permanent magnets30of the consequent pole type interior permanent magnet motor1according to the above-described embodiment. The three bar-shaped permanent magnets30″ arranged in a U shape have the same polarity.

The plurality of permanent magnets30″ may be formed of a rare earth element. For example, the plurality of permanent magnets30″ may be formed of neodymium Nd.

The rotor20″ is formed of an iron core, and a plurality of magnet insertion holes23″ in which the permanent magnets30″ are disposed may be formed in the iron core of the rotor20″ in the circumferential direction of the rotor20″. Each of the plurality of magnet insertion holes23″ may be formed in a substantially U shape to correspond to the shape of the permanent magnets30″.

In the plurality of permanent magnets30″ disposed in the rotor20″, two adjacent permanent magnets30″ with the slit40interposed therebetween have different polarities. When the plurality of permanent magnets30″ including two permanent magnets30″ having different polarities as one set are disposed in the rotor20″, the iron core portions of the rotor20″ between the two sets are magnetized to form a plurality of consequent poles (iron core poles)22in the rotor20″. In other words, the iron core portion between two permanent magnets30″ that are spaced far apart from each other and have the same polarity is magnetized to form the consequent pole22.

The distance between the two permanent magnets30″ having different polarities with the slit40interposed therebetween is shorter than the distance between the two permanent magnets30″ having the same polarity.

The slits40and the shaft hole21of the rotor20″ according to this embodiment are the same as or similar to them of the rotor20of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, detailed descriptions thereof are omitted.

In the above description, the consequent pole type interior permanent magnet motor1has six magnetic poles, that is, four permanent magnets30and two consequent poles22. However, the number of magnetic poles of the consequent pole type interior permanent magnet motor1according to an embodiment of the disclosure is not limited thereto. Hereinafter, a consequent pole type interior permanent magnet motor having a different number of magnetic poles will be described with reference toFIGS.14and15.

FIG.14is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure having eight magnetic poles.

Referring toFIG.14, the rotor220of the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure may include six permanent magnets230, two consequent poles222, and four slits240.

Therefore, the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure includes a total of eight magnetic poles including two consequent poles222and six magnetic poles formed of six permanent magnets230.

Three adjacent permanent magnets230may form one permanent magnet set, and two permanent magnet sets may be symmetrically disposed with respect to two consequent poles222.

The three permanent magnets230constituting the permanent magnet set may be disposed adjacent to each other with two slits240interposed therebetween in the rotor220. For example, as illustrated inFIG.14, the permanent magnet set may be arranged in the order of the S-pole permanent magnet230, the slit240, the N-pole permanent magnet230, the slit240, and the S-pole permanent magnet230.

Accordingly, the two adjacent permanent magnets230with the slit240interposed therebetween have different polarities. In addition, the two adjacent permanent magnets230are arranged to be symmetrical to each other with respect to the slit240. Accordingly, one permanent magnet230may be positioned between the two slits240.

The distance between the two permanent magnets230having the same polarity is greater than the distance between the two permanent magnets230having different polarities. A consequent pole222is formed by the two permanent magnets230having the same polarity in the iron core portion of the rotor between the two permanent magnets230having the same polarity. In addition, the slit240is not formed in the iron core portion between the two permanent magnets230having the same polarity.

In the case of the embodiment shown inFIG.14, because the two permanent magnets230having the same polarity far apart have an S pole, a consequent pole222having an N pole is formed in the iron core portion between the two permanent magnets230having the same polarity.

Each of the plurality of slits240may be formed adjacent to the outer circumferential surface of the rotor220across the width of two adjacent magnet insertion holes223into which the permanent magnets230are inserted. The shape of the slit240is the same as or similar to that of the slit40of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, a detailed description thereof is omitted.

FIG.15is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure having ten magnetic poles.

Referring toFIG.15, the rotor320of the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure may include six permanent magnets330, four consequent poles322, and two slits340.

Therefore, the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure includes a total of ten magnetic poles including four consequent poles322and six magnetic poles formed of six permanent magnets330.

The two slits340may be provided in the rotor320at intervals of 180 degrees. In other words, the two slits340may be provided to form a straight line in the rotor320.

In the embodiment show inFIG.15, as for the six permanent magnets330, three permanent magnets330are disposed on each of the upper and lower portions of the rotor320based on the two slits340.

The three permanent magnets330disposed on the upper portion have the same polarity and are spaced apart at regular intervals. The three permanent magnets330disposed on the lower portion have the same polarity and are spaced apart at regular intervals. Polarities of the three permanent magnets330disposed on the upper portion are different from those of the three permanent magnets330disposed on the lower portion. Accordingly, the two adjacent permanent magnets330with the slit340interposed therebetween have different polarities. In addition, the two adjacent permanent magnets330are arranged to be symmetrical to each other with respect to the slit340.

The distance between the two permanent magnets330having the same polarity is greater than the distance between the two permanent magnets330having different polarities. A consequent pole322is formed by the two permanent magnets330having the same polarity in the iron core portion of the rotor between the two permanent magnets330having the same polarity. In addition, the slit340is not formed in the iron core portion between the two permanent magnets330having the same polarity.

For example, as illustrated inFIG.15, three N-pole permanent magnets330may be disposed at regular intervals on the upper portion of the rotor320. An S-pole consequent pole322may be formed by the two N-pole permanent magnets330in the iron core portion between the two N-pole permanent magnets330. Accordingly, two consequent poles322having the S pole may be formed at the upper portion of the rotor320.

In addition, three S-pole permanent magnets330may be disposed at regular intervals on the lower portion of the rotor320. An N-pole consequent pole322may be formed by the two S-pole permanent magnets330in the iron core portion between the two S-pole permanent magnets330. Accordingly, two consequent poles322having the N pole may be formed at the lower portion of the rotor320.

Each of the plurality of slits340may be formed adjacent to the outer circumferential surface of the rotor320across the width of two adjacent magnet insertion holes323into which the permanent magnets330are inserted. The shape of the slit340is the same as or similar to that of the slit40of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, a detailed description thereof is omitted.

In the above description, the consequent pole type interior permanent magnet motor1uses permanent magnets30,30′, and30″ formed of rare earth element, for example, neodymium Nd. However, the disclosure is not limited thereto. The consequent pole type interior permanent magnet motor according to an embodiment of the disclosure may use permanent magnets formed of ferrite.

Hereinafter, a consequent pole type interior permanent magnet motor using ferrite magnets according to an embodiment of the disclosure will be described with reference toFIGS.16to18.

FIG.16is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure using ferrite magnets and having six magnetic poles.

Referring toFIG.16, a plurality of permanent magnets430are disposed inside the rotor420of the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure. In detail, the plurality of permanent magnets430are disposed between the outer circumferential surface of the rotor420and the shaft hole421.

Because the motor according to this embodiment is a six poles consequent pole type interior permanent magnet motor, in the rotor420, four permanent magnets430are disposed and two consequent poles422are formed.

The permanent magnets430may be formed in a C-shape, which is a magnetic flux concentration type. Also, the permanent magnets430may be formed of ferrite.

The rotor420is formed of an iron core, and four magnet insertion holes423in which the permanent magnets430are disposed may be formed in the circumferential direction of the rotor420. The four magnet insertion holes423may be formed in a C-shape to correspond to the shape of the permanent magnet430.

As for four permanent magnets430disposed in the rotor420, two adjacent permanent magnets430with the slit440interposed therebetween have different polarities. When the four permanent magnets430including two permanent magnets430having different polarities as one set are disposed in the rotor420, the iron core portions of the rotor420between the two permanent magnet sets are magnetized to form a plurality of consequent poles (iron core poles)422in the rotor420. In other words, the iron core portion between two permanent magnets430that are spaced far apart from each other and have the same polarity is magnetized to form the consequent pole422.

For example, when the plurality of permanent magnets430are arranged in the order of N-pole permanent magnet, S-pole permanent magnet, iron core, S-pole permanent magnet, N-pole permanent magnet, and iron core in the rotor420, portions of the rotor420, that is, portions of the iron core between the two permanent magnets430having the same polarity are magnetized with a polarity opposite to that of the two permanent magnets430.

The distance between the two permanent magnets430having different polarities with the slit440interposed therebetween is shorter than the distance between the two permanent magnets430having the same polarity.

The slits440and the shaft hole421of the rotor420according to this embodiment are the same as or similar to those of the rotor20of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, detailed descriptions thereof are omitted.

FIG.17is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure using ferrite magnets and having eight magnetic poles.

Referring toFIG.17, a plurality of permanent magnets530are disposed inside the rotor520of the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure. In detail, the plurality of permanent magnets530are disposed between the outer circumferential surface of the rotor520and the shaft hole521.

Because the motor according to this embodiment is an eight poles consequent pole type interior permanent magnet motor, in the rotor520, six permanent magnets530are disposed and two consequent poles522are formed.

The permanent magnets530may be formed in a C-shape, which is a magnetic flux concentration type. Also, the permanent magnets530may be formed of ferrite.

The rotor520is formed of an iron core, and six magnet insertion holes523in which the permanent magnets530are disposed may be formed in the circumferential direction of the rotor520. The six magnet insertion holes523may be formed in a C-shape to correspond to the shape of the permanent magnet530.

Three adjacent permanent magnets530may form one permanent magnet set, and two permanent magnet sets may be symmetrically disposed with respect to two consequent poles522.

The three permanent magnets530constituting the permanent magnet set may be arranged in the order of an S-pole permanent magnet530, a slit540, an N-pole permanent magnet530, a slit540, and an S-pole permanent magnet530with two slits540interposed therebetween.

Accordingly, the two adjacent permanent magnets530with the slit540interposed therebetween have different polarities. In addition, the two adjacent permanent magnets530are arranged to be symmetrical to each other with respect to the slit540. Accordingly, one permanent magnet530may be positioned between the two slits540.

The distance between the two permanent magnets530having the same polarity is greater than the distance between the two permanent magnets530having different polarities. A consequent pole522is formed by the two permanent magnets530having the same polarity in the iron core portion of the rotor between the two permanent magnets530having the same polarity. In addition, the slit540is not formed in the iron core portion between the two permanent magnets530having the same polarity.

In the case of the embodiment shown inFIG.17, because the two permanent magnets530having the same polarity far apart have S poles, a consequent pole522having an N pole is formed in the iron core portion between the two permanent magnets530having the same polarity.

The slits540and the shaft hole521of the rotor520according to this embodiment are the same as or similar to those of the rotor20of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, detailed descriptions thereof are omitted.

FIG.18is a cross-sectional view illustrating a consequent pole type interior permanent magnet motor according to an embodiment of the disclosure using ferrite magnets and having ten magnetic poles.

Referring toFIG.18, a plurality of permanent magnets630are disposed inside the rotor620of the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure. In detail, the plurality of permanent magnets630are disposed between the outer circumferential surface of the rotor620and the shaft hole621.

Because the motor according to this embodiment is a ten poles consequent pole type interior permanent magnet motor, in the rotor620, six permanent magnets630are disposed and four consequent poles622are formed.

The permanent magnets630may be formed in a C-shape, which is a magnetic flux concentration type. Also, the permanent magnets630may be formed of ferrite.

The rotor620is formed of an iron core, and six magnet insertion holes623in which the permanent magnets630are disposed may be formed in the circumferential direction of the rotor620. The six magnet insertion holes623may be formed in a C-shape to correspond to the shape of the permanent magnet630.

The two slits640may be provided in the rotor620at intervals of 180 degrees. In other words, the two slits640may be provided to form a straight line in the rotor620.

In the embodiment show inFIG.18, as for the six permanent magnets630, three permanent magnets630are disposed on each of the upper and lower portions of the rotor620based on the two slits640.

The three permanent magnets630disposed on the upper portion have the same polarity and are spaced apart at regular intervals. The three permanent magnets630disposed on the lower portion also have the same polarity and are spaced apart at regular intervals. Polarities of the three permanent magnets630disposed on the upper portion are different from those of the three permanent magnets630disposed on the lower portion. Accordingly, the two adjacent permanent magnets630with the slit640interposed therebetween have different polarities. In addition, the two adjacent permanent magnets630are arranged to be symmetrical to each other with respect to the slit640.

The distance between the two permanent magnets630having the same polarity is greater than the distance between the two permanent magnets630having different polarities. A consequent pole622is formed by the two permanent magnets630having the same polarity in the iron core portion of the rotor between the two permanent magnets630having the same polarity. In addition, the slit640is not formed in the iron core portion between the two permanent magnets630having the same polarity.

For example, as illustrated inFIG.18, three N-pole permanent magnets630may be disposed at regular intervals on the upper portion of the rotor620. An S-pole consequent pole622may be formed by the two N-pole permanent magnets630in the iron core portion between the two N-pole permanent magnets630. Accordingly, two consequent poles622having the S pole may be formed at the upper portion of the rotor620.

In addition, three S-pole permanent magnets630may be disposed at regular intervals on the lower portion of the rotor620. An N-pole consequent pole622may be formed by the two S-pole permanent magnets630in the iron core portion between the two S-pole permanent magnets630. Accordingly, two consequent poles622having the N pole may be formed at the lower portion of the rotor620.

The slits640and the shaft hole621of the rotor620according to this embodiment are the same as or similar to those of the rotor20of the consequent pole type interior permanent magnet motor1according to the above-described embodiment; therefore, detailed descriptions thereof are omitted.

With the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure having the above-described structure, the amount of magnetization of the rotating shaft and the second harmonic component of the back electromotive force may be reduced.

In addition, with the consequent pole type interior permanent magnet motor according to an embodiment of the disclosure, the unbalance between the amount of magnetic flux linked to the stator by the permanent magnet and the amount of magnetic flux linked to the stator by the consequent pole may be eliminated and the back electromotive force may be increased.

The disclosure has been described above in an exemplary manner. The terms used herein are for the purpose of description and should not be construed in a limiting sense. Various modifications and variations of the disclosure are possible according to the above contents. Accordingly, unless otherwise stated, the disclosure may be practiced freely within the scope of the claims.