KR20220096655A - Permanent Magnet Synchronous Machine - Google Patents

Abstract

Provided is a permanent magnet synchronous machine. The permanent magnet synchronous machine may include: a stator including stator teeth arranged in a circumferential direction and stator windings provided in the stator teeth; and a rotor provided within a radial direction of the stator and having a consequent pole formed by alternatively arranging a first permanent magnet having a first pole, a first metal pole, a second permanent magnet having a second pole opposite to the first pole, and a second metal pole in a circumferential direction.

Description

Permanent Magnet Synchronous Machine

The present invention relates to a permanent magnet synchronizer, and more particularly, to a low-cost permanent magnet synchronizer in which the amount of permanent magnet used is reduced.

An electric motor is a device that converts electrical energy into mechanical energy by using a force applied to a conductor through which an electric current flows in a magnetic field. Among them, a synchronous motor (SM) refers to an electric motor in which a rotor can rotate at a constant speed in synchronization with a rotation field of a stator. The rotor of a synchronous motor has the advantage of being able to maintain a constant rotation speed even in a variable voltage environment.

Such synchronous motors include a permanent magnet synchronous motor (PMSM) and a field winding type synchronous motor (Wound Rotor Synchronous Motor, WRSM).

A permanent magnet synchronous motor may use a permanent magnet to generate a rotor flux. Permanent magnet synchronous motors can provide a fixed speed in synchronization with the frequency of the power source despite fluctuations in load or voltage, and are widely used in various industrial and home applications due to their excellent performance of high efficiency and high torque density. have. In particular, the permanent magnet synchronous motor may be useful in that it can provide a fixed speed in synchronization with the main frequency within a range permitted by the design specifications of the motor. However, since the unit price of rare earth magnets used in permanent magnet synchronous motors is high, it has limitations in application.

One technical problem to be solved by the present invention is to provide a low-cost permanent magnet synchronizer with reduced permanent magnet usage.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problem, the present invention provides a permanent magnet synchronizer.

According to an embodiment, the permanent magnet synchronizer includes: a stator including stator teeth arranged in a circumferential direction and a stator winding provided on the stator teeth; and a first permanent magnet having a first magnetic pole, a first metal pole, a second permanent magnet and a second metal pole having a second magnetic pole opposite to the first magnetic pole provided on the radially inner side of the stator in the circumferential direction It may include a rotor having a sequential pole (Consequent pole) formed by being alternately arranged.

According to an embodiment, the first permanent magnet and the first metal pole are in close contact with each other in the circumferential direction to form a first pole set, and the second permanent magnet and the second metal pole are in close contact with each other in the circumferential direction to form a second pole The set may be formed, and the first set of poles and the second set of poles may be spaced apart from each other in a circumferential direction.

According to an embodiment, it further includes an air gap flux barrier, the air barrier may be provided between the first set of poles and the second set of poles.

According to an embodiment, the first metal pole and the second metal pole may be made of the same metal material, but may be made of a metal material including iron.

According to another embodiment, the rotor further includes a magnetic material, and the magnetic material may be provided between the first permanent magnet and the first metal pole and between the second permanent magnet and the second metal pole, respectively.

According to another embodiment, the magnetic material may be formed of soft ferrite.

According to another embodiment, the magnetic body may have a relatively smaller width than that of the first permanent magnet and the second permanent magnet.

According to embodiments, the first metal pole includes a first step portion, the first step portion is provided on one side of the outer diameter of the first metal pole facing the inner diameter of the stator, the mounting space of the first permanent magnet provided, wherein the second metal pole includes a second step portion, and the second step portion is provided on one side of the outer diameter of the second metal pole facing the inner diameter of the stator to provide a mounting space for the second permanent magnet. can

According to an embodiment of the present invention, there is provided a stator comprising: stator teeth arranged in a circumferential direction and a stator winding provided on the stator teeth; and a first permanent magnet having a first magnetic pole, a first metal pole, a second permanent magnet and a second metal pole having a second magnetic pole opposite to the first magnetic pole provided on the radially inner side of the stator in the circumferential direction It may include a rotor having a sequential pole (Consequent pole) formed by being alternately arranged.

Accordingly, a low-cost permanent magnet synchronizer with reduced permanent magnet usage can be provided, thereby reducing manufacturing cost.

According to an embodiment of the present invention, there can be provided a permanent magnet synchronizer capable of completely replacing an existing surface permanent magnet synchronizer without changing a controller and using a small amount of permanent magnets.

That is, according to an embodiment of the present invention, even if the amount of permanent magnet is reduced, a permanent magnet synchronizer capable of obtaining almost the same torque and torque ripple as that of an existing surface permanent magnet synchronizer can be provided.

1 is a schematic cross-sectional view showing a permanent magnet synchronizer according to an embodiment of the present invention.
2 is a magnetic circuit diagram of a permanent magnet synchronizer according to an embodiment of the present invention.
3 is a simplified magnetic circuit diagram of a permanent magnet synchronizer according to an embodiment of the present invention when R _b is sufficiently large in FIG. 2 .
4 is a dq-axis diagram of a permanent magnet (PM) torque and a reluctance torque in a permanent magnet synchronizer according to an embodiment of the present invention.
5 is a schematic cross-sectional view showing a permanent magnet synchronizer according to another embodiment of the present invention.
6 is a pole magnetic flux distribution diagram of a permanent magnet synchronizer according to an embodiment of the present invention.
7 is a pole magnetic flux distribution diagram of a permanent magnet synchronizer according to another embodiment of the present invention.
8 is a simulation image showing a slot-free magnetic flux density distribution of a permanent magnet synchronizer according to an embodiment of the present invention.
9 is a simulation image showing a slot-free magnetic flux density distribution of a permanent magnet synchronizer according to another embodiment of the present invention.
10 is a graph showing a change in cogging torque according to a rotor position in Examples and Comparative Examples of the present invention.
11 is a graph showing the electromagnetic torque change according to the rotor position of the embodiment and the comparative example of the present invention.
12 is a schematic cross-sectional view showing a permanent magnet synchronizer according to Comparative Example 1 of the present invention.
13 is a schematic cross-sectional view showing a permanent magnet synchronizer according to Comparative Example 2 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In this specification, when a component is referred to as being on another component, it means that it may be directly formed on the other component or a third component may be interposed therebetween. In addition, in the drawings, the shape and size are exaggerated for effective description of technical content.

In addition, in various embodiments of the present specification, terms such as first, second, third, etc. are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another. Accordingly, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes a complementary embodiment thereof. In addition, in this specification, 'and/or' is used in the sense of including at least one of the components listed before and after.

In the specification, the singular expression includes the plural expression unless the context clearly dictates otherwise. In addition, terms such as “comprise” or “have” are intended to designate that a feature, number, step, component, or a combination thereof described in the specification is present, and one or more other features, numbers, steps, or configurations It should not be construed as excluding the possibility of the presence or addition of elements or combinations thereof. In addition, in this specification, "connection" is used in a sense including both indirectly connecting a plurality of components and directly connecting a plurality of components.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a schematic cross-sectional view showing a permanent magnet synchronizer according to an embodiment of the present invention.

As shown in FIG. 1 , the permanent magnet synchronizer 100 according to an embodiment of the present invention is formed to include a stator 110 and a rotor 120 .

The stator 110 may be provided on one side of the rotor 120 , for example, radially outside the rotor 120 . The stator 110 may provide rotational force to the rotor 120 . To this end, the stator 110 may be provided in a cylindrical shape including a hollow inside. Accordingly, the rotor 120 may be rotated by the rotational force provided from the stator 110 in a state that is drawn into the hollow of the stator 110 .

According to an embodiment, the stator 110 may include stator teeth 111 . The stator teeth 111 may be provided in plurality, and may be arranged in the circumferential direction of the inner diameter side of the stator 110 . In this case, a space between the stator teeth 111 adjacent to each other may be defined as a stator slot.

The stator 110 may further include a stator winding. The stator windings may create a magnetic field or stator field to cause the rotor 120 to rotate. Such stator windings may be provided on each stator tooth 111 .

The stator windings may be grouped according to a phase of an applied current. For example, when three phases of A, B, and C having two pole pairs are applied to the stator winding, the stator winding is a first stator winding (A+, A-) and a second stator winding (B-, B+). ) and the third stator winding (C+, C-).

In this case, different groups of stator windings may be formed on a specific stator tooth 111 , or stator windings of the same group may be formed on the specific stator teeth 111 .

The rotor 120 may rotate with respect to the stator 110 by the generated rotor field and the stator field generated by the stator 110 .

The rotor 120 may be provided radially inside the stator 110 . The rotor 120 may be drawn into the hollow inside of the stator 110 .

The rotor 120 according to an embodiment of the present invention may include a sequential pole.

The continuous pole may be formed by alternately arranging the first permanent magnet 121 , the first metal pole 122 , the second permanent magnet 123 , and the second metal pole 124 in the circumferential direction.

Here, the first permanent magnet 121 may have a first magnetic pole. For example, the first permanent magnet 121 may have an N pole. Also, the second permanent magnet 123 may have a second magnetic pole opposite to the first magnetic pole. For example, the second permanent magnet 123 may have an S pole.

The number of the first metal poles 122 may correspond to the number of the first permanent magnets 121 formed. The first metal pole 122 may have a shape that increases in width from the center of the rotor 120 toward the outside in a radial direction. For example, the first metal pole 122 may have a sector-shaped cross-section.

The first metal pole 122 may be in close contact with the first permanent magnet 121 in a circumferential direction. In this case, the first metal pole 122 may support the first permanent magnet 121 . To this end, the first metal pole 122 may include a first stepped portion 122a.

The first step portion 122a may be provided on one side of the outer diameter of the first metal pole 122 facing the inner diameter of the stator 110 . Specifically, the first step portion 122a may be provided on one side of the edge in the width direction in the outer diameter of the first metal pole 122 .

For example, the first step portion 122a may be provided in the shape of a groove concave radially inward from one side of the outer diameter width direction edge of the first metal pole 122 . Through this, the first step portion 122a may provide a mounting space for the first permanent magnet 121 .

The first permanent magnet 121 is mounted to be fitted in the first stepped portion 122a, thereby forming a structure in close contact with the first metal pole 122 in the circumferential direction. And through this, the first permanent magnet 121 faces the inner diameter of the stator 110 in the radial direction.

In one embodiment of the present invention, as described above, the first permanent magnet 121 and the first metal pole 122 that are in close contact with each other in the circumferential direction may form a first pole set PS1.

According to an embodiment of the present invention, the first metal pole 122 may be made of a metal material. For example, the first metal pole 122 may be made of a metal material including iron.

The number of the second metal poles 124 may correspond to the number of the formation of the second permanent magnets 123 . The second metal pole 124 may have the same shape as the first metal pole 122 . That is, the second metal pole 124 may have a shape in which the width increases from the center of the rotor 120 toward the outside in a radial direction. For example, the second metal pole 124 may have a sector-shaped cross-section.

The second metal pole 124 may be in close contact with the second permanent magnet 123 in the circumferential direction. In this case, the second metal pole 124 may support the second permanent magnet 123 . To this end, the second metal pole 124 may include a second step portion 124a.

The second step portion 124a may be provided on one side of the outer diameter of the second metal pole 124 facing the inner diameter of the stator 110 . Specifically, the second step portion 124a may be provided on one side of the edge in the width direction in the outer diameter of the second metal pole 124 .

For example, the second step portion 124a may be provided in a groove shape concave radially inward from one side of the outer diameter width direction edge of the second metal pole 124 . Through this, the second step portion 124a may provide a mounting space for the second permanent magnet 123 .

The second permanent magnet 123 is mounted to be fitted in the second stepped portion 124a, thereby forming a structure in close contact with the second metal pole 124 in the circumferential direction. And through this, the second permanent magnet 123 faces the inner diameter of the stator 110 in the radial direction.

In one embodiment of the present invention, as described above, the second permanent magnet 123 and the second metal pole 124 that are in close contact with each other in the circumferential direction may form the second pole set PS2.

According to an embodiment of the present invention, the second metal pole 124 may be made of the same material as the first metal pole 122 . For example, like the first metal pole 122 , the second metal pole 124 may be made of a metal material including iron.

According to an embodiment of the present invention, the rotor 120 is a first permanent magnet 121, a first metal pole 122, a second permanent magnet 123 and a second metal pole that are alternately arranged in the circumferential direction. It may include a sequential pole made of (124).

That is, according to an embodiment of the present invention, the first metal pole 122 is provided between the first permanent magnet 121 and the second permanent magnet 123, and the second permanent magnet 123 and the first permanent magnet 123 are provided. As the second metal pole 124 is provided between the magnets 121 , the amount of use of the first permanent magnet 121 and the second permanent magnet 123 is reduced. Accordingly, according to an embodiment of the present invention, a low-cost permanent magnet synchronizer 100 with reduced manufacturing cost can be provided.

At this time, in an embodiment of the present invention, even if the amount of the permanent magnets 121 and 123 is reduced, it is possible to obtain torque and torque ripple almost equal to that of the existing surface permanent magnet synchronizer, which will be described below. It will be described in more detail.

Meanwhile, the permanent magnet synchronizer 100 according to an embodiment of the present invention may further include an air gap flux barrier 130 .

The air gap flux barrier 130 includes the first pole set PS1 formed by the first permanent magnet 121 and the first metal pole 122 in close contact, the second permanent magnet 123 and the second metal pole 124 . ) may be provided in a space formed by being spaced apart from each other in the circumferential direction of the second pole set PS2 formed in close contact with each other. The air gap flux barrier 130 serves to prevent flux from flowing from the first permanent magnet 121 having an N pole to the second permanent magnet 123 having an S pole, for example.

The permanent magnet synchronizer 100 according to an embodiment of the present invention may reduce a large torque ripple generated by a continuous pole by providing such an air gap flux barrier.

Hereinafter, characteristics of a permanent magnet synchronizer according to an embodiment of the present invention will be described with reference to FIGS. 2 to 4 .

2 is a magnetic circuit diagram of a permanent magnet synchronizer according to an embodiment of the present invention, and FIG. 3 is a simplified magnetic circuit diagram of a permanent magnet synchronizer according to an embodiment of the present invention when R _b is sufficiently large in FIG. , FIG. 4 is a dq-axis diagram of a permanent magnet (PM) torque and a reluctance torque in a permanent magnet synchronizer according to an embodiment of the present invention.

2 and 3, R _b represents the reluctux of the air gap flux barrier, Φ _pm and Φ _ip are, respectively, the air positioned on the first permanent magnet 121 and the first metal pole 122 The gap fluxes, Φ′ _pm and Φ′ _ip represent air gap fluxes positioned on the second permanent magnet 123 and the second metal pole 124 , respectively.

When R _b is large enough, Φ _pm , Φ _ip , Φ' _pm and Φ' _ip are the same, and may be expressed by Equation 1 below.

[Equation 1]

The magnetic reluctance of the air gap flux barrier can be calculated through Equation 2 below.

[Equation 2]

where μ ₀ is the magnetic permeability of vacuum, μ _r is the relative permeability of air, A _b is the cross-sectional area of the air gap flux barrier, and l _b is the width of the air gap flux barrier.

Therefore, when the air gap flux barrier is sufficiently wide, the air gap flux of the permanent magnet synchronizer according to the embodiment of the present invention may coincide with the air gap plus of the existing permanent magnet synchronizer. This indicates that the permanent magnet torque of the permanent magnet synchronizer according to an embodiment of the present invention is the same as that of the existing permanent magnet synchronizer.

However, if the air gap flux barrier is too wide, the equivalent working air gap length increases, reducing the output torque.

In this regard, as a key parameter, the width of the air gap flux barrier should be set.

Generally, for permanent magnet (PM) torque, the d-axis is aligned with the rotor flux linkage phasor according to the direction of magnetic flux of the entire rotor. The q-axis is perpendicular to the d-axis in a counterclockwise direction.

Referring to Figure 4, the d-q axis of the reluctance torque should be changed to the dr-qr axis due to the double protruding ferromagnetic iron poles. The angular difference between the d-q axis and the dr-qr axis is 45 degrees, but in the general torque equation it should be 90 degrees.

Therefore, the torque equation of the permanent magnet synchronizer according to an embodiment of the present invention may be expressed as follows.

[Equation 3]

When the phase current is zero, the magnetic and reluctance torques can be fully used to maximize the output torque. When the permanent magnet synchronizer according to an embodiment of the present invention uses id = 0 control, the torque equation 3 shows that the permanent magnet and reluctance torque can be utilized to the maximum.

Hereinafter, a permanent magnet synchronizer according to another embodiment of the present invention will be described with reference to FIG. 5 .

5 is a schematic cross-sectional view showing a permanent magnet synchronizer according to another embodiment of the present invention.

Referring to FIG. 5 , the permanent magnet synchronizer 200 according to another embodiment of the present invention may include a stator 110 and a rotor 220 .

In another embodiment of the present invention, compared with an embodiment of the present invention, there is only a difference in that the rotor further includes a magnetic material, so the same reference numerals are given to the remaining identical components and detailed descriptions thereof is to be omitted.

According to another embodiment of the present invention, the rotor 220 may further include a magnetic body 225 .

In this case, any one magnetic material 225 may be provided between the first permanent magnet 121 and the first metal pole 122 in the circumferential direction. Like the first permanent magnet 121 , the magnetic body 225 is mounted on the first step portion 122a provided on one side of the outer diameter of the first metal pole 122 to be supported by the first metal pole 122 . can

In addition, the other magnetic material 225 may be provided between the second permanent magnet 123 and the second metal pole 124 in the circumferential direction. Like the second permanent magnet 123 , the magnetic body 225 is mounted on the second step portion 124a provided on one side of the outer diameter of the second metal pole 124 to be supported by the second metal pole 124 . can

The magnetic body 225 may have a relatively smaller width than that of the first permanent magnet 121 and the second permanent magnet 123 . In addition, the magnetic material 225 may be formed of soft ferrite having a low magnetic saturation point.

Hereinafter, characteristics of a permanent magnet synchronizer according to embodiments of the present invention will be described with reference to FIGS. 6 to 9 .

6 is a pole flux distribution diagram of a permanent magnet synchronizer according to an embodiment of the present invention, FIG. 7 is a pole magnetic flux distribution diagram of a permanent magnet synchronizer according to another embodiment of the present invention, and FIG. 8 is an embodiment of the present invention It is a simulation image showing the slot-free magnetic flux density distribution of the permanent magnet synchronizer according to the example, and FIG. 9 is a simulation image showing the slot-free magnetic flux density distribution of the permanent magnet synchronizer according to another embodiment of the present invention.

Referring to FIG. 6 , the permanent magnet synchronizer according to an embodiment of the present invention suffers from the same magnetic imbalance problem as the existing permanent magnet synchronizer.

The flux can no longer increase when the material's saturation point is reached.

Referring to FIG. 7 , in the case of a permanent magnet synchronizer according to another embodiment of the present invention, in the sequential pole, as a part of iron is replaced with soft ferrite, the magnetic flux close to the permanent magnet is magnetic saturation of the flexible ferrite. Limited to the point, the extra magnetic flux can be dispersed away from the permanent magnet to make the flux density distribution uniform.

Accordingly, the permanent magnet synchronizer according to another embodiment of the present invention can alleviate magnetic imbalance compared to the permanent magnet synchronizer according to the embodiment of the present invention, thereby further improving the output performance.

8 and 9 , a permanent magnet synchronizer having flexible ferrite according to another embodiment of the present invention, without flexible ferrite, asymmetric air gap flux than a permanent magnet synchronizer according to an embodiment of the present invention It was confirmed that the density was effectively suppressed.

Meanwhile, FIG. 10 is a cogging torque according to the rotor position of an embodiment (ICP-PMSM), another embodiment (ISCP-PMSM), Comparative Example 1 (SPMSM) and Comparative Example 2 (CP-PMSM) of the present invention. It is a graph showing the change of cogging torque).

Here, as shown in FIG. 12 , the permanent magnet synchronizer according to Comparative Example 1 (SPMSM) has a rotor structure in which permanent magnets PMs having different polarities are closely adhered in the circumferential direction.

In addition, as shown in FIG. 13 , the permanent magnet synchronizer according to Comparative Example 2 (CP-PMSM) has a rotor structure including a continuous pole without an air gap flux barrier.

Referring to FIG. 10 , while the peak-to-peak value of the cogging torque of Comparative Example 2 is the largest, the permanent magnet synchronizer according to an embodiment (ICP-PMSM) and another embodiment (ISCP-PMSM) of the present invention The peak-to-peak value of the cogging torque was measured to be much smaller.

11 is an electromagnetic torque according to the rotor position of an embodiment (ICP-PMSM), another embodiment (ISCP-PMSM), Comparative Example 1 (SPMSM) and Comparative Example 2 (CP-PMSM) of the present invention ( It is a graph showing the change in electromagnetic torque).

Referring to FIG. 11 , another embodiment (ISCP-PMSM) can achieve similar average output torque and torque ripple as Comparative Example 1 (SPMSM), whereas Comparative Example 2 (CP-PMSM) can achieve similar average output torque and torque ripple as Comparative Example 1 (SPMSM) It was confirmed that it was impossible to achieve an average output torque and torque ripple similar to ), and an embodiment (ICP-PMSM) achieved only an average output torque similar to Comparative Example 1 (SPMSM) and had a higher torque ripple.

As mentioned above, although the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to specific embodiments and should be construed according to the appended claims. In addition, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the present invention.

100, 200; Permanent Magnet Synchronizer
110; stator
111; stator teeth
120, 220; rotor
121; 1st permanent magnet
122; first metal pole
122a; first step
123; 2nd permanent magnet
124; second metal pole
124a; second step
130; Air Gap Flux Barrier
225; magnetic material

Claims (8)

a stator comprising circumferentially arranged stator teeth and stator windings provided on the stator teeth; and
A first permanent magnet, a first metal pole, and a second permanent magnet and a second metal pole having a second magnetic pole opposite to the first magnetic pole are provided in the radial direction of the stator in the circumferential direction. Including, a permanent magnet synchronizer; a rotor having a sequential pole (Consequent pole) formed by being alternately arranged.
According to claim 1,
The first permanent magnet and the first metal pole are in close contact with each other in the circumferential direction to form a first pole set, the second permanent magnet and the second metal pole are in close contact with each other in the circumferential direction to form a second pole set,
The first set of poles and the second set of poles are circumferentially spaced apart from each other.
3. The method of claim 2,
Further comprising an air gap flux barrier,
and the air gap flux barrier is provided between the first set of poles and the second set of poles.
According to claim 1,
The first metal pole and the second metal pole are made of the same metal material, and made of a metal material including iron, a permanent magnet synchronizer.
According to claim 1,
The rotor further comprises a magnetic material,
The magnetic body is provided between the first permanent magnet and the first metal pole and between the second permanent magnet and the second metal pole, respectively, a permanent magnet synchronizer.
6. The method of claim 5,
The magnetic body is provided with soft ferrite (soft ferrite), a permanent magnet synchronizer.
6. The method of claim 5,
The magnetic body has a relatively smaller width than the first permanent magnet and the second permanent magnet, a permanent magnet synchronizer.
According to claim 1,
The first metal pole includes a first stepped portion,
The first step portion is provided on one side of the outer diameter of the first metal pole facing the inner diameter of the stator to provide a mounting space for the first permanent magnet,
The second metal pole includes a second step,
The second step portion is provided on one side of the outer diameter of the second metal pole facing the inner diameter of the stator to provide a mounting space for the second permanent magnet, a permanent magnet synchronizer.

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