WO2022193592A1

WO2022193592A1 - Electric motor rotor and electric motor

Info

Publication number: WO2022193592A1
Application number: PCT/CN2021/119322
Authority: WO
Inventors: 葛梦; 李文瑞; 兰海; 武谷雨; 龚黎明
Original assignee: 美的威灵电机技术（上海）有限公司
Priority date: 2021-03-15
Filing date: 2021-09-18
Publication date: 2022-09-22
Also published as: JP2024509433A; KR20230133912A; CN112865370A

Abstract

Provided are an electric motor rotor and an electric motor, the electric motor rotor comprising a rotor core and a plurality of permanent magnets, wherein the plurality of permanent magnets are arranged in the circumferential direction of the rotor core so as to form a plurality of magnetic poles in the circumferential direction of the rotor core, the magnetization directions of two adjacent magnetic poles are opposite to each other, an angle between the magnetic domain orientation of the permanent magnet in each magnetic pole and the center line of the magnetic pole is α, and α is not less than 0 degrees and is not more than 40 degrees, so as to form a magnetic characteristic where the magnetic flux density is large at the center of the magnetic pole and gradually decreases towards two ends in the circumferential direction.

Description

Motor rotor and motor

This application claims the priority of the Chinese patent application with application number 202110278645.1 filed on March 15, 2021, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the technical field of motors, and in particular, to a motor rotor and a motor.

Background technique

Permanent magnet motors are widely used in industrial production and household appliances, including stators and rotors. A plurality of stator iron cores are arranged on the rotor of the motor rotor, and three-phase windings are formed by winding on the stator iron cores. In the prior art, the motor rotor motors are mostly surface-mounted permanent magnet motor structures. In this structure, the permanent magnets are usually magnetized radially or in parallel, and the magnetic fields of the formed permanent magnets are uniformly distributed on the rotor side and the stator side. , the power density of the motor is not high, and the output capacity of the motor is limited.

technical problem

The main purpose of the present application is to provide a motor rotor, which aims to solve the problem in the prior art that it is difficult to increase the power density of the motor.

technical solutions

In order to achieve the above purpose, the present application proposes a motor rotor, which includes:

rotor core; and

A plurality of permanent magnets are arranged along the circumferential direction of the rotor iron core to form a plurality of magnetic poles in the circumferential direction of the rotor iron core, and the magnetization directions of two adjacent magnetic poles are opposite. The angle between the orientation of the magnetic domain of the permanent magnet in the magnetic pole and the center line of the magnetic pole is α, and the α is not less than zero degrees and not more than 40 degrees, so that the magnetic flux density is high in the center of the magnetic pole and increases with the direction of the two ends in the circumferential direction. Gradually decreasing magnetic properties.

In one embodiment, there are multiple magnetic domain orientations of the permanent magnets in each of the magnetic poles, and the included angles of the multiple magnetic domain orientations of the permanent magnets in each of the magnetic poles and the centerlines of the magnetic poles are from close to the magnetic poles. The position of the center line gradually increases to the position away from the center line of the magnetic pole.

In one embodiment, when the number of the magnetic poles is greater than or equal to 8 and less than or equal to 20, the maximum value of the α is not less than 18 degrees and not greater than 40 degrees.

In one embodiment, when the number of the magnetic poles is greater than or equal to 20, the maximum value of the α is not less than 15 degrees and not greater than 35 degrees.

In one embodiment, the inner surface and the outer surface of each of the permanent magnets are arc-shaped.

In one embodiment, the diameter of the outer surface arc of each piece of the permanent magnet is between 90 mm and 320 mm, the axial height of each piece of the permanent magnet along the rotor core is less than or equal to 50 mm, and The radial thickness of each of the permanent magnets along the rotor core is less than or equal to 10 mm.

In one embodiment, a plurality of the permanent magnets are attached and fixed on the inner surface of the rotor core.

In one embodiment, each of the permanent magnets is formed with one of the magnetic poles or an even number of the magnetic poles.

In one embodiment, the even number of the poles is 2 or 4.

The present application also proposes a motor, the motor includes a stator, a rotating shaft and the motor rotor according to any one of the above, the rotating shaft is fixed on a rotor iron core rotated by the motor, the stator and the rotor are concentric, and sleeved on the inner side of the rotor.

beneficial effect

The technical solution of the present application is to arrange a plurality of permanent magnets along the circumferential direction of the rotor core to form a plurality of magnetic poles in the circumferential direction of the rotor core. The magnetization directions of two adjacent magnetic poles are opposite, and the magnetic The angle between the domain orientation and the center line of the magnetic pole is α, and α is not less than zero degrees and not more than 40 degrees, so as to form a magnetic characteristic that the magnetic flux density is high in the center of the magnetic pole and gradually decreases as it goes to both ends in the circumferential direction. Under this configuration of magnetic domain direction, when the motor rotor is used in the motor, the magnetic flux interlinked with the stator will increase, (as can be seen from the magnetic field lines) because the magnetic field lines converge to the center line of the magnetic pole, so the magnetic density close to the center line of the magnetic pole will increase. High, the two ends along the circumferential direction are low, so that the magnetic field close to the inner side of the rotor is strengthened, and the magnetic field outside the rotor is weakened, so that the magnetic field strength of the air gap between the stator and the rotor is increased, and the saturation degree of the rotor core is reduced, so that the motor output rotates. The torque increases and the power density of the motor is improved.

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without any creative effort.

1 is a schematic diagram of the assembly structure of the stator and the rotor of the motor of the application;

2 is a schematic diagram of the assembly structure of the rotor and the connecting frame of the motor of the application;

3 is a schematic diagram of the configuration of the magnetization directions of a pair of magnetic poles in the rotor of the motor of the present application;

Fig. 4 is the schematic diagram that each permanent magnet of the motor rotor of the application is distributed with a magnetic pole;

FIG. 5 is a schematic diagram showing that each permanent magnet of the motor rotor of the present application has two magnetic poles distributed

6 is a schematic diagram showing that each permanent magnet of the motor rotor of the application is distributed with four magnetic poles;

FIG. 7 is a schematic diagram of the comparison of the motor back EMF FFT formed by the permanent magnet of the motor rotor of the application and the conventional permanent magnet;

FIG. 8 is a schematic diagram showing the comparison of the proportion of harmonics of each order of the motor back EMF formed by the permanent magnet of the motor rotor of the application and the conventional permanent magnet;

9 is a schematic diagram of an embodiment of a stator punch of the motor of the application;

10 is a schematic diagram of another embodiment of the stator punch of the motor of the application;

11 is a schematic diagram of another embodiment of the stator punch of the motor of the application;

12 is a schematic diagram of still another embodiment of the stator punch of the motor of the application;

13 is a schematic structural diagram of the stator of the motor of the application;

FIG. 14 is a schematic diagram of the arrangement and connection of the coils of the rotor of the motor of the present application on the stator teeth.

Description of reference numbers:

标号 label	名称 name	标号 label	名称 name
1 1	电机转子 motor rotor	222 222	内定子轭 inner stator yoke
11 11	永磁体 Permanent magnets	25 25	定子槽 stator slot
12 12	转子铁芯 rotor core	26 26	凸起 bulge
2 2	定子 stator	27 27	凹槽 groove
21 twenty one	定子齿 stator teeth	3 3	线圈 coil
22 twenty two	定子轭 stator yoke	4 4	连接架 connection frame
221 221	外定子轭 outer stator yoke

The realization, functional characteristics and advantages of the purpose of the present application will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Embodiments of the present invention

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relationship between various components under a certain posture (as shown in the accompanying drawings). The relative positional relationship, the movement situation, etc., if the specific posture changes, the directional indication also changes accordingly.

In addition, descriptions involving "first", "second", etc. in this application are only for descriptive purposes, and should not be construed as indicating or implying their relative importance or implicitly indicating the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist. , is not within the scope of protection claimed in this application.

In order to achieve the above purpose, the present application proposes a motor rotor, as shown in FIG. 1 , the motor rotor is sleeved on the outer side of the stator 2 and is concentric with the stator 2, and cooperates with the stator 2 to form a motor, as shown in FIG. The motor rotor 1 includes: a rotor iron core 12, the rotor iron core 12 is an annular structure; a plurality of permanent magnets 11, a plurality of the permanent magnets 11 are arranged along the circumferential direction of the rotor iron core 12, so as to A plurality of magnetic poles are formed in the circumferential direction of the rotor core 12 (Fig. 3 shows a schematic diagram of the configuration of the magnetization direction under a pair of magnetic poles, and each permanent magnet 11 in the figure has only one magnetic pole), and the magnetization of two adjacent magnetic poles In the opposite direction, the magnetic domain orientation of the permanent magnet 11 in each of the magnetic poles is sandwiched by its magnetic pole centerline (the magnetic pole centerline is shown by the dotted line in Figure 3, and the magnetic domain is shown by the arrow in Figure 3-6). The angle is α, which is not less than zero degrees and not more than 40 degrees to form a magnetic characteristic in which the magnetic flux density is high in the center of the magnetic pole and gradually decreases toward both ends in the circumferential direction. The magnetic field close to the inner side of the rotor core is strengthened and the magnetic field outside the rotor core is weakened (as shown by the dashed arc in the figure).

It should be noted that, each permanent magnet 11 may be distributed with one magnetic pole or multiple magnetic poles. When there are multiple magnetic poles distributed, the number of magnetic poles on each permanent magnet 11 is an even number, such as 2, 4, 8, etc., FIG. 4 shows a schematic diagram of one magnetic pole distributed on each permanent magnet 11, FIG. 5 shows a schematic diagram of two magnetic poles distributed on each permanent magnet 11, and FIG. 6 shows A schematic diagram of four magnetic poles distributed on each permanent magnet 11 is shown. The magnetization directions of two adjacent magnetic poles are opposite. Figures 3 and 5 show the configuration diagrams of the magnetization directions under a pair of magnetic poles, forming a permanent magnetic field that can generate an interaction force with the current magnetic field formed by the stator 2 .

It should be noted that the magnetic domains are shown by the arrows in Figures 3-6, and each permanent magnet 11 has multiple magnetic domains. The permanent magnet 11 uses the method of filling or pressing to manufacture a complete magnet, and then in a special Magnetization is performed in the fixture of the mold, or the direction of the flow channel of the material is controlled to form a magnetic domain in a specific direction during the mold filling process. The processing efficiency is high, and it is relatively easy to achieve mass production. The magnetic domains in each permanent magnet 11 have multiple orientations (the directions indicated by the arrows in FIG. 3-6 are indicated as magnetic domain orientations), but from the perspective of a single permanent magnet 11 formed by multiple magnetic domains, The magnetization directions shown on the two adjacent permanent magnets 11 are still opposite, and each permanent magnet 11 has an arc-shaped inner surface and an arc-shaped outer surface (for example, a circular arc segment with the same radius, or an arc in the middle). shape, the combination of straight lines at both ends, or the combination of two arcs with different radii, etc.), in this embodiment, the outer surface of each permanent magnet 11 is arranged in contact with the inner side of the rotor core 12. Of course, in other embodiments Among them, the rotor core 12 can also be slotted to fix the permanent magnets 11 in the slots. The diameter of the outer surface arc of each permanent magnet 11 is between 90 mm and 320 mm, the axial height of each permanent magnet 11 along the rotor core 12 is less than 50 mm, and each permanent magnet 11 is less than 50 mm in diameter. The thickness of the magnets 11 along the radial direction of the rotor core 12 is less than 10 mm, so that when the motor rotor is used in the motor, the output torque of the motor is high, the performance requirements are met, and the cost is low. The motor rotor proposed in this embodiment can be applied to the motor of the washing machine. Due to the higher output torque of the motor, the power of the washing machine can be ensured, and the cost can be reduced.

In this embodiment, the angle between the orientation of the magnetic domain of the permanent magnet 11 in each magnetic pole and the center line of the magnetic pole is α, and the α is not less than zero degrees and not greater than 40 degrees, corresponding to the inner direction of the permanent magnet 11 of each magnetic pole. There is a certain magnetic domain orientation change law in the magnetic domain. As shown in Figure 3-6, in the ring direction of the rotor core 12, the angle α within the same magnetic pole gradually decreases from one side to the other and then gradually increases. The magnetic domain orientation of each magnetic domain can be rotated by a specific angle in turn, so that the magnetic domain orientation in each magnetic pole is generally radial. Magnetic properties that gradually decrease toward both ends in the circumferential direction. When the motor rotor is used in the motor, the magnetic flux interlinked with the stator will increase, (as can be seen from the magnetic field lines) because the magnetic field lines converge to the center line of the magnetic pole, so the magnetic density near the center line of the magnetic pole is high, and the two ends along the circumferential direction Low, so that the magnetic field close to the inner side of the rotor core is strengthened, the magnetic field outside the rotor core is weakened, and the magnetic field is sinusoidally distributed. It is beneficial to reduce cogging torque, reduce torque ripple, and reduce the noise of motor operation. Of course, the orientation of the magnetic domains may not be set according to the same rotation angle, as long as the magnetic lines of force are concentrated toward the inner side of the rotor. The value range of the maximum value of α is related to the number of magnetic poles. In a further embodiment, when the number of magnetic poles is greater than or equal to 20, the maximum value of α is not less than 15 degrees and not greater than 35 degrees, so that the rotor The inner magnetic field of the iron core is strengthened, and the outer magnetic field is weakened, so that the magnetic field strength of the air gap between the stator and the rotor is enhanced, and the magnetic field saturation degree on the rotor side is reduced, the output performance of the motor is improved, and the power density is increased, and the magnetic field distribution is more sinusoidal and harmonic. With less wave content, it is beneficial to reduce cogging torque and torque ripple, thereby reducing motor vibration and noise. In another embodiment, when the number of the magnetic poles is greater than or equal to 8 and less than or equal to 20, the maximum value of the α is not less than 18 degrees and not greater than 40 degrees, and any value within this range is acceptable , for example, 30 degrees, which can be set as required.

The application also proposes a motor, the motor includes a stator 2, a rotating shaft and the above-mentioned motor rotor, the rotating shaft is fixed on the rotor iron core 11 of the motor rotor, the stator and the rotor are concentric, and sleeved on the inner side of the rotor.

An air gap is formed between the stator 2 and the motor rotor 1 (not marked in the figure). Since the magnetic field inside the rotor core 12 is enhanced, the magnetic induction intensity at the air gap increases. When the coil 3 on the stator 2 is energized , the interaction force between the strengthened permanent magnet field and the current magnetic field on the motor rotor 1 increases, which improves the power density of the motor. As shown in FIG. 7 , the permanent magnet 11 proposed in this embodiment forms an enhanced inner magnetic field of the rotor and an outer magnetic field. When the magnetic field distribution is weakened and the magnetic field is uniformly distributed inside and outside, the back EMF FFT diagram of the motor is compared. It can be seen that after using the permanent magnet 11 in this application, the amplitude of the no-load back EMF fundamental wave is larger, indicating that the output capacity of the motor is better. strong, which is beneficial to improve the power density of the motor. As shown in FIG. 8 , when the permanent magnet 11 proposed in the present embodiment forms the magnetic field distribution inside the rotor with enhanced magnetic field, the magnetic field distribution of the external magnetic field weakened and the magnetic field distributed uniformly inside and outside, the comparison diagram of the proportion of each harmonic of the back EMF of the motor can be seen. It is found that after using the permanent magnet 11 in the present application, the 5th and 7th harmonics in the back EMF are significantly reduced, indicating that the magnetic field distribution towards the inner side of the rotor core 12 is more sinusoidal, which is conducive to reducing cogging torque and torque ripple, reducing Vibration noise. In addition, since the rotor iron core 12 is generally made of magnetically conductive material, in this embodiment, since the magnetic field toward the outside of the rotor iron core 12 is very small, the magnetic circuit saturation of the rotor 1 is avoided, which can not only improve the output capacity of the motor, but also reduce the The loss of the rotor core 12 is reduced, and the motor efficiency is further improved. In the case of the same number of unit motors, the number of rotor poles proposed in this embodiment has higher motor output efficiency, so that the number of teeth can be reduced without relying on increasing the number of unit motors. The slot torque can reduce the winding time during the manufacturing process and reduce the manufacturing and processing difficulty of the motor.

The stator 2 includes a stator punch formed of a magnetically conductive material. As shown in FIGS. 9-12 , the stator punch has an annular stator yoke 22 , and the stator teeth 21 are formed by extending outward from the outer diameter of the stator yoke 22 .

The stator 2 is formed by stacking a plurality of stator punching sheets, and a plurality of sector-shaped units are butted against each other to form a stator punching sheet. The two ends of the sector-shaped units are respectively provided with grooves 27 and protrusions 25, and the protrusions 25 are inserted into the grooves at one end of the adjacent fan-shaped units. 27 to form stator punches. Alternatively, the lamination unit is formed by a bar-shaped stator tooth belt having a stator yoke 22 and a plurality of stator teeth 21 in a spiral shape. As shown in FIG. 12 , a plurality of notches 28 are spaced apart on the stator yoke 22 , and the stator teeth 21 and the grooves The openings 28 are located on opposite sides of the stator tooth 21, respectively. The existence of the slot 27 facilitates the helical winding of the strip stator tooth belt. The dotted line and the realization in Figure 12 show two stator tooth belts, respectively. In practical applications , The incoming material for processing the stator is generally a strip-shaped stamping plate. This way of forming the stator by spirally wrapping the stator tooth belt can save the material of the stamping plate, make the stamping plate form less waste, and help save costs. A stator slot 25 is formed between two adjacent stator teeth 21 . In an optional embodiment, as shown in FIG. 13 , the ratio of the stator slot 25 to the number of rotor poles is 3:4, and a coil 3 is wound around the stator teeth 21 . To form a winding, the stator teeth 21 are provided with an insulating layer (not marked in the figure), the insulating layer is wrapped around the surface of the stator teeth 21, and the insulating layer is an insulating film or two pieces of insulation slots to insulate the coil 3 from the stator teeth 21 . The arrangement of the coil 3 on the stator teeth 21 is shown in Figure 14. The windings on the adjacent three stator teeth 21 along the circumferential direction of the stator yoke 22 are respectively connected to currents with a phase difference of 120° to form three-phase windings. The ratio of 25 to the number of rotor poles is 3:4, so the number of windings per phase is exactly one-third of the number of stator teeth 21, where the number of rotor poles is the total number of magnetic poles on rotor 1, such as when each When one magnetic pole is formed on the permanent magnet 11, the number of rotor poles is equal to the number of permanent magnets 11. When two magnetic poles are formed on each permanent magnet 11, the number of rotor poles is equal to twice the number of permanent magnets 11. When four magnetic poles are formed on 11, the number of rotor poles is equal to four times the number of permanent magnets 11.

When the number of rotor magnetic poles is large, the leakage flux between adjacent magnetic poles will increase, thereby reducing the motor output torque. , as an example, the number of stator slots 25 is 30, the number of rotor poles is 40, the number of unit motors is 10, the cogging torque is low, and the winding time is relatively short.

The above descriptions are only optional embodiments of the present application, and are not intended to limit the patent scope of the present application. Under the conception of the present application, any equivalent structural transformations made by the contents of the description and drawings of the present application, or direct/indirect application Other related technical fields are included in the scope of patent protection of this application.

Claims

A motor rotor, wherein the motor rotor comprises:

rotor core; and

A plurality of permanent magnets are arranged along the circumferential direction of the rotor iron core to form a plurality of magnetic poles in the circumferential direction of the rotor iron core, and the magnetization directions of two adjacent magnetic poles are opposite, forming each The angle between the orientation of the magnetic domain of the magnetic pole and the center line of the magnetic pole is α, and the α is not less than zero degrees and not more than 40 degrees, so that the magnetic flux density is high in the center of the magnetic pole and gradually increases as it goes to both ends in the circumferential direction. Reduced magnetic properties.
The motor rotor according to claim 1 , wherein there are multiple magnetic domain orientations in each of the magnetic poles, and the included angles between the orientations of the plurality of magnetic domains in each of the magnetic poles and the centerlines of the magnetic poles are from close to the magnetic pole. The position of the center line gradually increases to the position away from the center line of the magnetic pole.
The motor rotor according to claim 1 or 2, wherein when the number of the magnetic poles is greater than or equal to 8 and less than or equal to 20, the maximum value of the α is not less than 18 degrees and not greater than 40 degrees.
The motor rotor according to claim 1 or 2, wherein when the number of the magnetic poles is greater than or equal to 20, the maximum value of the α is not less than 15 degrees and not more than 35 degrees.
The motor rotor according to claim 1, wherein the inner surface and the outer surface of each of the permanent magnets are arc-shaped.
The motor rotor according to claim 5, wherein the diameter of the outer surface arc of each of the permanent magnets is 90 Between mm and 320 mm, the axial height of each permanent magnet along the rotor core is less than or equal to 50 mm, and the radial thickness of each permanent magnet along the rotor core is less than or equal to 10mm.
The motor rotor according to claim 6, wherein a plurality of the permanent magnets are attached and fixed on the inner surface of the rotor iron core.
The motor rotor of claim 1, wherein each of the permanent magnets is formed with one of the magnetic poles or an even number of the magnetic poles.
The motor rotor according to claim 7, wherein the even number of the magnetic poles is 2 or 4.
A motor, wherein the motor comprises a stator, a rotating shaft, and a motor rotor according to any one of claims 1-9, the rotating shaft is fixed on a rotor iron core rotated by the motor, and the stator is connected to the rotor of the motor. The rotor is concentric, and the stator is sleeved on the inner side of the rotor.