JP2024509433A - Electric motor rotor and electric motor - Google Patents

Abstract

The present application provides an electric motor rotor and an electric motor, the electric motor rotor having a rotor core and a plurality of magnetic poles installed along the circumferential direction of the rotor core, and having a plurality of magnetic poles in the circumferential direction of the rotor core. When a plurality of permanent magnets are formed, in which two adjacent magnetic poles have opposite magnetization directions, and the included angle between the magnetic domain orientation of the permanent magnet in each magnetic pole and the magnetic pole center line is α, then a plurality of permanent magnets having a magnetic characteristic in which α is greater than or equal to 0 degrees and less than or equal to 40 degrees, and the magnetic flux density is high at the center of the magnetic pole, and the magnetic flux density gradually decreases toward both ends in the circumferential direction; Equipped with.
[Selection diagram] Figure 1

Description

This application claims priority to the Chinese patent application with application number 202110278645.1, filed on March 15, 2021, and the entire contents thereof are incorporated by reference into this application.

TECHNICAL FIELD This application relates to the technical field of electric motors, and more particularly to electric motor rotors and electric motors.

Permanent magnet electric motors, widely used in industrial production and household appliances, include a rotor and a stator. A rotor of an electric motor is provided with a plurality of stator cores, and windings are wound around the stator core to form a three-phase winding. In the prior art, most of the rotor electric motors of electric motors are surface magnet type permanent magnet electric motor structures. In this structure, the permanent magnets are usually radially magnetized or parallel magnetized, and the magnetic fields on the rotor side and stator side due to the formed permanent magnets are uniformly distributed, and the power density of the electric motor is not high. Electric motor output capacity is limited.

The main object of the present invention is to provide an electric motor rotor to solve the problem that it is difficult to improve the power density of electric motors in the prior art.

To achieve the above objective, this application proposes an electric motor rotor, the electric motor rotor comprising:
rotor core,
A plurality of permanent magnets are installed along the circumferential direction of the rotor core and 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 each of the permanent magnets When α is the included angle between the magnetic domain orientation of the permanent magnet in the magnetic pole and the center line of the magnetic pole, α is greater than or equal to 0 degrees and less than 40 degrees, and the magnetic flux density is high at the center of the magnetic pole, and the magnetic flux density is high at the center of the magnetic pole. A plurality of permanent magnets are formed with magnetic characteristics in which the magnetic flux density gradually decreases toward both ends.

In one embodiment, there are a plurality of magnetic domain orientations of the permanent magnets in each of the magnetic poles, and an included angle between the plurality of magnetic domain orientations of the permanent magnets in each of the magnetic poles and the magnetic pole center line is at a position close to the magnetic pole center line. It gradually becomes larger toward the position away from the magnetic pole center line.

In one embodiment, when the number of magnetic poles is 8 or more and 20 or less, the maximum value of α is 18 degrees or more and 40 degrees or less.

In one embodiment, when the number of magnetic poles is 20 or more, the maximum value of α is 15 degrees or more and 35 degrees or less.

In one embodiment, both the inner and outer surfaces of each permanent magnet are arcuate.

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

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

In one embodiment, each permanent magnet is formed with one said magnetic pole or an even number of said magnetic poles.

In one embodiment, the even number of said magnetic poles is two or four.

The present application further proposes an electric motor comprising a stator, a rotating shaft, and the electric motor rotor according to any one of the above, wherein the rotating shaft is fixed to a rotating rotor core of the electric motor. The stator is concentric with the rotor and is fitted inside the rotor.
beneficial effects

According to the technical proposal of the present application, by installing a plurality of permanent magnets along the circumferential direction of the rotor core, a plurality of magnetic poles are formed in the circumferential direction of the rotor core, and two adjacent magnetic poles are magnetized. The directions are opposite, and when α is the included angle between the magnetic domain orientation of the permanent magnet in each magnetic pole and the center line of the magnetic pole, α is greater than or equal to 0 degrees and less than 40 degrees, and the magnetic flux density at the center of the magnetic pole is A magnetic property is formed in which the magnetic flux density is high and the magnetic flux density gradually decreases toward both ends in the circumferential direction. Due to this arrangement of magnetic domain directions, when the electric motor rotor is applied to an electric motor, the magnetic flux interlinking with the stator increases, and the magnetic field lines converge toward the magnetic pole center line (as seen from the magnetic field lines), so the magnetic poles The magnetic flux density is high near the centerline and low at both ends in the circumferential direction, so the magnetic field becomes stronger near the inside of the rotor and weaker outside the rotor, resulting in a magnetic field in the air gap between the stator and rotor. The strength is increased, the saturation of the rotor core is reduced, the output torque of the electric motor is increased, and the power density of the electric motor is improved.

In order to more clearly explain the embodiments of the present application and the technical solutions of the prior art, the accompanying drawings necessary for explaining the embodiments or the prior art will be briefly introduced below. It is clear that the attached drawings in the following description are only some embodiments of the present application, and it is possible for a person skilled in the art to obtain other attached drawings according to the structure shown in these attached drawings without any creative effort. be able to.

FIG. 2 is a schematic diagram of an assembly structure of a stator and a rotor of the electric motor of the present application. FIG. 2 is a schematic diagram of an assembly structure of an electric motor rotor and a connection bracket according to the present application. FIG. 2 is a schematic diagram illustrating the arrangement of the magnetization directions of a pair of magnetic poles in the rotor of the electric motor of the present application. 1 is a schematic diagram in which each permanent magnet of the rotor of the electric motor of the present application is provided with one magnetic pole; FIG. 1 is a schematic diagram in which each permanent magnet of the rotor of the electric motor of the present application is provided with two magnetic poles; FIG. FIG. 2 is a schematic diagram in which each permanent magnet of the rotor of the electric motor of the present application is provided with four magnetic poles; FIG. 2 is a schematic comparison diagram of back electromotive force FFT of an electric motor formed by a permanent magnet of the electric motor rotor of the present application and a conventional permanent magnet. FIG. 2 is a schematic diagram comparing the ratio of harmonics of each order of reverse potential of an electric motor formed by a permanent magnet of the electric motor rotor of the present application and a conventional permanent magnet. FIG. 1 is a schematic diagram of an embodiment of a stator plate of an electric motor according to the present application. 3 is a schematic diagram of another embodiment of a stator plate of an electric motor according to the present application; FIG. FIG. 3 is a schematic diagram of yet another embodiment of a stator plate of an electric motor according to the present application. FIG. 3 is a schematic diagram of yet another embodiment of a stator plate of an electric motor according to the present application. FIG. 2 is a schematic structural diagram of a stator of an electric motor according to the present application. FIG. 2 is a schematic diagram illustrating the arrangement and connection of coils of the electric motor rotor of the present application on stator teeth.

1 Electric motor rotor 11 Permanent magnet 12 Rotor core 2 Stator 21 Stator teeth 22 Stator yoke 221 Outer stator yoke 222 Inner stator yoke 25 Stator slot 26 Convex 27 Concave groove 3 Coil 4 Connection bracket

The realization of the objects, functional features and advantages of the present invention will be further explained in conjunction with the embodiments with reference to the accompanying drawings.

In the following, the technical solutions in the embodiments of the present application will be clearly and completely explained in combination with the drawings in the embodiments of the present application. It is clear that the described embodiments are not all embodiments of the present application, but only some embodiments of the present application. Based on the embodiments in this application, all other embodiments that can be obtained by a person skilled in the art without any creative effort fall within the protection scope of this application.

All directional indications (for example, up, down, left, right, front, back...) in the embodiments of the present application are defined as It is necessary to explain that this is used only to explain the positional relationship, movement status, etc., and that if the specific posture changes, the directional instruction will also change accordingly.

Furthermore, in the Examples of the present application, explanations such as "first", "second", etc. are used only for explanation, and do not indicate or imply their relative importance, or are technical features to be presented. should not be understood as implicitly specifying the number of . Accordingly, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. Moreover, the technical solutions of each embodiment can be combined with each other. However, it is assumed that this can be realized by a person skilled in the art. If a combination of technical solutions is inconsistent or cannot be realized, it should be understood that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

To achieve the above objective, the present application proposes an electric motor rotor, as shown in FIG. 1, the electric motor rotor is fitted outside the stator 2 and is concentric with the stator 2. In cooperation with the stator 2, an electric motor is formed. As shown in FIG. 2, the electric motor rotor 1 includes a rotor core 12 having an annular structure, and a plurality of rotor cores installed along the circumferential direction of the rotor core 12. A plurality of permanent magnets 11 forming magnetic poles (FIG. 3 shows a schematic diagram of the arrangement of magnetization directions in a pair of magnetic poles, and in the figure, each permanent magnet 11 is provided with only one magnetic pole). , the magnetization directions of two adjacent magnetic poles are opposite, and the magnetic domain orientation of the permanent magnet 11 in each magnetic pole and its magnetic pole center line (the magnetic pole center line is shown by the dotted straight line in FIG. 3, and the magnetic domains are shown in FIGS. 3 to 6 The included angle between the magnetic poles (indicated by arrows in ) is α, and the above-mentioned A plurality of permanent magnets whose α is greater than or equal to 0 degrees and less than or equal to 40 degrees. As shown by the dotted arc line in the figure, the magnetic field becomes stronger near the inner side of the rotor core, and becomes weaker near the outer side of the rotor core.

Note that each permanent magnet 11 may be provided with one magnetic pole or may be provided with a plurality of magnetic poles. When a plurality of magnetic poles are provided, the number of magnetic poles of each permanent magnet 11 is an even number such as 2, 4, or 8. 4 is a schematic diagram in which each permanent magnet 11 is provided with one magnetic pole, FIG. 5 is a schematic diagram in which each permanent magnet 11 is provided with two magnetic poles, and FIG. 6 is a schematic diagram in which each permanent magnet 11 is provided with two magnetic poles. A schematic diagram in which four magnetic poles are provided is shown. The magnetization directions of two adjacent magnetic poles are opposite. As shown in FIGS. 3 and 5, a schematic diagram of the arrangement of the magnetization direction in a pair of magnetic poles is shown, and a magnetic field is formed by a permanent magnet that can generate an interaction force with the magnetic field caused by the current generated by the stator 2. be done.

The magnetic domains are as shown by the arrows in FIGS. 3 to 6, and each permanent magnet 11 has a plurality of magnetic domains, and the permanent magnet 11 is specially manufactured after manufacturing a completed magnet by injection molding or press molding. Because magnetic domains are formed in a specific direction by magnetizing within a jig or by controlling the runner direction of the material during injection molding, processing efficiency is high and lot production is relatively easy. The magnetic domains within each permanent magnet 11 have multiple orientations (the directions indicated by arrows in FIGS. 3 to 6 indicate the magnetic domain orientations), but when viewed from a single permanent magnet 11 consisting of multiple magnetic domains, two adjacent The magnetization directions appearing in the two permanent magnets 11 are also opposite. Each permanent magnet 11 has an arcuate inner surface and an arcuate outer surface (for example, an arcuate line segment with the same radius, a combination of an arcuate middle and a straight line at both ends, or a combination of two arcuate line segments with different radii). have In this embodiment, the outer surface of each permanent magnet 11 is attached to the inside of the rotor core 12, but of course, in other embodiments, slots are provided in the rotor core 12 so that the permanent magnets 11 may be fixed within the slot. The diameter of the circular arc of the outer surface of each permanent magnet 11 is between 90 mm and 320 mm, the height of each permanent magnet 11 along the axial direction of the rotor core 12 is less than 50 mm, and the height of each permanent magnet 11 along the axial direction of the rotor core 12 is less than 50 mm. The thickness of the rotor core 12 along the radial direction is less than 10 mm. Therefore, when applied to the electric motor rotor electric motor, the output torque is high, meets the performance requirements, and the cost is low. The electric motor rotor proposed in this embodiment can be applied to an electric motor of a washing machine. Since the electric motor has a high output torque, it can ensure strong power of the washing machine, which is advantageous for cost reduction.

In this embodiment, the included angle α between the magnetic domain orientation of the permanent magnet 11 in each magnetic pole and the center line of the magnetic pole is 0 degrees or more and 40 degrees or less, and the magnetic domain in the permanent magnet 11 corresponding to each magnetic pole is , there exists a certain rule of magnetic domain orientation change. As shown in FIGS. 3 to 6, in the circumferential direction of the rotor core 12, the angle α within the same magnetic pole gradually decreases and then increases from one side to the other, and the magnetic domain orientation within each magnetic pole is generally The magnetic domain orientation of each magnetic domain may be sequentially rotated by a certain angle so as to be radial. In such a magnetic domain orientation arrangement, a magnetic characteristic is formed in which the magnetic flux density is high at the center of the magnetic pole and the magnetic flux density gradually decreases toward both ends in the circumferential direction. When the electric motor rotor is applied to an electric motor, the magnetic flux interlinking with the stator increases and the magnetic field lines converge toward the magnetic pole center line (as seen from the magnetic field lines), so the magnetic flux decreases near the magnetic pole center line. Since the density is high and the magnetic flux density is low at both ends in the circumferential direction, the magnetic field is strong near the inner side of the rotor core, and weaker near the outer side of the rotor core, and the magnetic field exhibits a sinusoidal distribution. Compared to the conventional magnetization method, when the above magnetization method is used, the magnetic field distribution becomes closer to a sinusoidal distribution and the harmonic content is lower, which reduces cogging torque and torque ripple, and improves the electric motor. This is advantageous in reducing noise during operation. Of course, it is only necessary to converge the lines of magnetic force to the inside of the rotor, and it is not necessary to set the magnetic domain orientation according to the same rotation angle. The range of the maximum value of α correlates with the number of magnetic poles. In yet another embodiment, when the number of magnetic poles is 20 or more, the maximum value of α is 15 degrees or more and 35 degrees or less. Therefore, the magnetic field becomes stronger near the inner side of the rotor core and weaker near the outer side, increasing the air gap magnetic field strength between the stator and rotor, and reducing the degree of saturation of the magnetic field on the rotor side. The output performance of electric motors is improved and the power density is increased. Furthermore, the magnetic field distribution becomes closer to a sine distribution and the harmonic content becomes lower, which is advantageous in reducing the vibration noise of the electric motor by reducing cogging torque and torque ripple. In another embodiment, when the number of magnetic poles is 8 or more and 20 or less, the maximum value of α is 18 degrees or more and 40 degrees or less, and may be any value within this range, such as 30 degrees. Specifically, it can be set as necessary.

The present application further proposes an electric motor comprising a stator 2, a rotating shaft, and the above-mentioned electric motor rotor, the rotating shaft being fixed to the rotor core 11 of the electric motor rotor, and the rotating shaft being fixed to the rotor core 11 of the electric motor rotor. is concentric with the rotor and fitted inside the rotor.

An air gap (not shown) is formed at a distance between the stator 2 and the electric motor rotor 1, and the magnetic field inside the rotor core 12 is strengthened, so that the magnetic induction strength in the air gap increases. . When the coil 3 on the stator 2 is energized, the interaction force between the magnetic field due to the reinforced permanent magnets on the electric motor rotor 1 and the magnetic field due to the current increases, and the power density of the electric motor increases. improves. FIG. 7 shows a case where the permanent magnet 11 proposed in this embodiment forms a magnetic field distribution in which the magnetic field is strong near the inside of the rotor and weak near the outside, and a case where the magnetic field is distributed evenly between the inside and outside of the rotor. FIG. 2 is a schematic diagram comparing FFT of a back electromotive force of an electric motor with a case where a magnetic field is formed. It can be seen that when the permanent magnet 11 in this application is adopted, the amplitude of the back electromotive force fundamental wave under no load is larger, which indicates that the output ability of the electric motor is stronger, and the power density of the electric motor is improved. advantageous to FIG. 8 shows a case where the permanent magnet 11 proposed in this embodiment forms a magnetic field distribution in which the magnetic field is strong near the inside of the rotor and weak near the outside, and a case where the magnetic field is distributed evenly between the inside and outside of the rotor. FIG. 4 is a schematic diagram comparing the content of harmonics of each order of the back electromotive force of the electric motor with a case where a magnetic field is formed. It was found that when the permanent magnet 11 of the present application is employed, the 5th and 7th harmonics of the back electromotive force are clearly reduced, and this is because the magnetic field distribution toward the inside of the rotor core 12 is sinusoidal. This is advantageous in reducing vibration noise by reducing cogging torque and torque ripple. Further, although the rotor core 12 is normally made of a magnetically permeable material, in this embodiment, since the magnetic field directed to the outside of the rotor core 12 is small, saturation of the magnetic circuit of the rotor 1 is avoided, and the electric motor output capacity is increased. In addition, the loss of the rotor core 12 is reduced, further improving the electric motor efficiency. For the same number of unit electric motors, the number of rotor poles proposed in this example can achieve higher electric motor output efficiency, so the cogging torque can be reduced without relying on an increase in the number of unit electric motors. In the manufacturing process, the winding time can be shortened, reducing the difficulty of manufacturing and processing electric motors.

The stator 2 includes a stator plate made of a magnetically permeable material, and as shown in FIGS. 9 to 12, the stator plate is provided with an annular stator yoke 22, and the stator teeth 21 are connected to the stator yoke. It extends outward at the outer diameter of 22.

The stator 2 is formed by laminating a plurality of stator plates, a stator plate is formed by a plurality of fan-shaped units butted against each other, and grooves 27 and protrusions 25 are provided at both ends of the fan-shaped units, respectively. A stator plate is formed by inserting a protrusion 25 into a groove 27 at one end of an adjacent fan-shaped unit. Alternatively, the lamination unit is formed by spirally winding a belt-shaped stator teeth belt having a stator yoke 22 and a plurality of stator teeth 21. As shown in FIG. 12, the stator yoke 22 is provided with a plurality of notches 28 at intervals, and the stator teeth 21 and the notches 28 are located on opposite sides of the stator teeth 21 belt, respectively. By providing the notch 27, it becomes easy to wind the belt-shaped stator teeth belt in a spiral shape. The broken lines and solid lines in FIG. 12 each indicate two stator teeth belts. In practical applications, the purchased material for processing the stator is usually a belt-shaped press-formed plate, and the method of spirally winding such a stator teeth belt to form the stator is It is advantageous to save the material and reduce the amount of scrap from the press-formed plate, which is advantageous for cost reduction. A stator slot 25 is formed between two adjacent stator teeth 21. In one possible embodiment, the ratio between the stator slots 25 and the number of rotor poles is 3:4, and the coils 3 are wound around the stator teeth 21 to form windings. The stator teeth 21 are provided with an insulating layer (not shown) that wraps around the surfaces of the stator teeth 21. The insulating layer is an insulating thin film or a structure in which two insulating sockets are covered together, and insulates the coil 3 and the stator teeth 21. As shown in FIG. 14, the arrangement of the coils 3 on the stator teeth 21 is such that currents having phases different by 120° are applied to the windings on three stator teeth 21 adjacent in the circumferential direction of the stator yoke 22. It is passed through to form a three-phase winding. Since the ratio of the stator slots 25 to the number of rotor poles is 3:4, the number of windings in each phase is exactly one third of the number of stator teeth 21. Here, the number of rotor poles is the total number of magnetic poles that the rotor 1 has. For example, if one magnetic pole is formed on each permanent magnet 11, the number of rotor poles is equal to the number of permanent magnets 11, and when two magnetic poles are formed on each permanent magnet 11, the number of rotor poles is equal to the number of permanent magnets 11. If each permanent magnet 11 is formed with four magnetic poles, 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, magnetic flux leakage between adjacent magnetic poles increases and electric motor output torque decreases. When the number of rotor magnetic poles is small, the magnetic domain orientation at different positions inside the permanent magnet changes significantly, making processing and manufacturing difficult. Therefore, as an example, if the number of stator slots 25 is 30, the number of rotor poles is 40, and the number of unit electric motors is 10, the cogging torque is low and the winding time is short.

What has been described above are merely preferred embodiments of the present application and do not limit the scope of the patent herein. Equivalent structural transformations made using the contents of the specification and attached drawings of the present application under the invention concept of the present application, or direct/indirect applications to other related technical fields, are all covered by the patent of the present application. Included in the scope of protection.

Claims (10)

rotor core,
A plurality of permanent magnets are installed along the circumferential direction of the rotor core and form a plurality of magnetic poles in the circumferential direction of the rotor core, the magnetization direction of two adjacent magnetic poles being opposite, When α is the included angle between the magnetic domain orientation of each magnetic pole and the magnetic pole center line, α is greater than or equal to 0 degrees and less than 40 degrees, and the magnetic flux density is high at the center of the magnetic pole, and a plurality of permanent magnets forming a magnetic characteristic in which the magnetic flux density gradually decreases toward both ends;
An electric motor rotor comprising: There are multiple magnetic domain orientations within each magnetic pole, and the included angle between the multiple magnetic domain orientations within each magnetic pole and the magnetic pole center line increases from a position close to the magnetic pole center line to a position away from the magnetic pole center line. The electric motor rotor according to claim 1, wherein the electric motor rotor gradually increases in size. The electric motor rotor according to claim 1 or 2, wherein when the number of magnetic poles is 8 or more and 20 or less, the maximum value of α is 18 degrees or more and 40 degrees or less. The electric motor rotor according to claim 1 or 2, wherein when the number of magnetic poles is 20 or more, the maximum value of α is 15 degrees or more and 35 degrees or less. The electric motor rotor according to claim 1, wherein both the inner and outer surfaces of each of the permanent magnets are arcuate. The diameter of the circular arc on the outer surface of each permanent magnet is between 90 mm and 320 mm, the height along the axial direction of the rotor core of each permanent magnet is 50 mm or less, and the rotor of each permanent magnet is The electric motor rotor according to claim 5, wherein the thickness of the iron core along the radial direction is 10 mm or less. The electric motor rotor according to claim 6, wherein the plurality of permanent magnets are affixed and fixed to the inner surface of the rotor core. The electric motor rotor according to claim 1, wherein each of the permanent magnets is formed with one magnetic pole or an even number of magnetic poles. The electric motor rotor according to claim 7, wherein the even number of magnetic poles is two or four. An electric motor,
The electric motor rotor includes a stator, a rotating shaft, and an electric motor rotor according to any one of claims 1 to 9, wherein the rotating shaft is fixed to a rotating rotor core of the electric motor, and the rotating shaft is fixed to a rotating rotor core of the electric motor. The stator is concentric with the electric motor rotor and is fitted inside the electric motor rotor.

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