Motor rotor and permanent magnet synchronous motor

Abstract

This invention relates to the field of electric motors, specifically to an electric motor rotor and a permanent magnet synchronous motor. The electric motor rotor includes a rotor core with multiple magnetic poles. Each magnetic pole has a first magnetic slot unit and a magnetic pole centerline d-axis corresponding to the first magnetic slot unit. The first magnetic slot unit is filled with a first permanent magnet, which forms a first magnetic flux. On a cross-section perpendicular to the centerline of the rotor core, the first magnetic flux has a concave side and a convex side opposite to the concave side in the d-axis direction. The concave side of the first magnetic flux is close to the center of the rotor core. This improves magnetic flux, increases motor efficiency, reduces motor harmonics, and reduces motor operating noise.

Description

Technical Field

[0001] This invention relates to the field of electric motors, and more specifically to an electric motor rotor and a permanent magnet synchronous motor. Background Technology

[0002] Permanent magnet synchronous motors include components such as stator and rotor. The rotor excitation of permanent magnet synchronous motors is mostly permanent magnet excitation. Common rotor core magnet structures include linear structures. This type of structure uses less magnet and the pole arc coefficient is easy to control and has high mechanical strength. However, during motor operation, it will cause the motor to form a non-sinusoidal magnetic flux density, which will not only generate greater electromagnetic noise, but also reduce the efficiency of the motor.

[0003] There is currently no good solution to the above-mentioned technical problems. Summary of the Invention

[0004] This invention improves magnetic flux, increases motor efficiency, reduces motor harmonics, and lowers motor operating noise by redesigning the rotor magnet slot structure and magnet material.

[0005] On one hand, the present invention provides an electric motor rotor, including a rotor core, the rotor core having multiple magnetic poles, each magnetic pole having a first magnetic steel slot unit and a magnetic pole center line d-axis corresponding to the magnetic pole, the first magnetic steel slot unit being filled with a first permanent magnet, the first permanent magnet forming a first magnetic flux.

[0006] On a cross-section perpendicular to the centerline of the rotor core, the first magnetic flux has a recessed side and a raised side opposite to the recessed side in the d-axis direction; the recessed side of the first magnetic flux is close to the center of the rotor core.

[0007] Preferably, the first magnet slot unit includes a plurality of magnet slots, the plurality of magnet slots forming a curved chain structure, and the notch formed by the curved chain structure faces the center of the rotor core.

[0008] Preferably, the plurality of magnetic slots are divided into N layers of magnetic slots from the outer circle of the rotor core to the center of the rotor core, and are sequentially arranged from the outer circle near the rotor core to the center of the rotor core as the first layer of magnetic slots, the second layer of magnetic slots, ..., the nth layer of magnetic slots;

[0009] The first layer of magnetic steel slots intersects the d-axis of the magnetic pole center line of the rotor core. From the second layer to the nth layer of magnetic steel slots, the number of magnetic steel slots in each layer is greater than 2 and they are distributed on both sides of the d-axis. The magnetic steel slots from the first layer to the nth layer are in a stepped shape.

[0010] Preferably, each of the plurality of magnetic slots is rectangular, the long side of the magnetic slot is perpendicular to the d-axis, and the short sides of two adjacent magnetic slots overlap.

[0011] Preferably, the width of the magnetic steel groove decreases from the first layer to the nth layer; the length of the first layer of magnetic steel groove is L1, the total length of the first magnetic steel groove unit is L, and 1 / 3L≤L1≤1 / 2L.

[0012] Preferably, the first magnet is a rare earth magnet 301; the remanence of the rare earth magnets 301 filling the magnet slots from the first layer to the nth layer decreases sequentially.

[0013] Preferably, the pole pitch of the rotor core corresponds to the rotor central angle θ1, and the effective pole angle of the inner magnetic flux is θ2.

[0014] Preferably, the second magnet slot unit is an arc-shaped magnet slot, and the concave side of the arc-shaped magnet slot faces the center of the rotor core.

[0015] Preferably, the arc-shaped magnet groove is filled with ferrite magnets, and the effective pole angle of the ferrite magnets is θ3.

[0016] Preferably, the second magnet slot unit is symmetrical about the d-axis, and the first magnet slot unit is also symmetrical about the d-axis.

[0017] On the other hand, the present invention also provides a permanent magnet synchronous motor, including the aforementioned motor rotor.

[0018] This invention improves the utilization rate of magnets per unit space by bringing the concave side of the magnetic flux closer to the center of the rotor core, thus ensuring the amount of magnets used. On the other hand, this structure also improves the air gap magnetic flux density and sinusoidal properties, resulting in a better sinusoidal back EMF waveform and lower harmonic content. As the harmonic content is lower, the torque pulsation generated by the rotor core also decreases. Attached Figure Description

[0019] Figure 1 This is a view of the rotor core end face according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram showing the asymmetry of the first magnet slot unit of the rotor core about the d-axis in an embodiment of the present invention.

[0021] The reference numerals in the attached figures are as follows:

[0022] 1. Rotor core; 2. Second magnet slot unit; 3. First magnet slot unit; 301. First layer magnet slot; 302. Second layer magnet slot; 4. Ferrite magnet; 5. Rare earth magnet. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in the embodiments of this invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. “Multiple” generally includes at least two, but does not exclude the inclusion of at least one.

[0025] It should be understood that the term "and / or" used in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship. The terms "inner layer" and "outer layer" are merely to distinguish different technical features, not to indicate a sequential order. The terms "upper," "lower," "front," and "rear" are only used to more conveniently illustrate the positional relationship of technical features and only have meaning when combined with actual usage or the specific location descriptions in the preceding text; they are not absolute positional relationships. The terms "reverse side" and "front side" are only used to distinguish two different surfaces of the baffle and have no other meaning.

[0026] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0027] This invention relates to the field of electric motors, specifically to an electric motor rotor and a permanent magnet synchronous motor. A permanent magnet synchronous motor includes components such as a stator and a rotor. The rotor excitation of a permanent magnet synchronous motor is mostly achieved through permanent magnet excitation. Common rotor core magnet structures include a linear structure, which uses fewer magnets, has easily controllable pole arc coefficients, and high mechanical strength. However, during motor operation, this results in a non-sinusoidal magnetic flux density, which not only generates significant electromagnetic noise but also reduces motor efficiency.

[0028] To address the aforementioned technical problems, the present invention provides a motor rotor and a permanent magnet synchronous motor.

[0029] On the one hand, the present invention provides a motor rotor, such as Figure 1-2 As shown, the rotor core 1 has multiple magnetic poles, and each magnetic pole has a first magnetic steel slot unit 3. The first magnetic steel slot unit 3 is filled with a first permanent magnet, and the first permanent magnet forms a magnetic flux. On a cross-section perpendicular to the center line of the rotor core 1, the magnetic flux forms a concave side and a convex side opposite to the concave side in the radial direction of the rotor core 1. The concave side of the magnetic flux is close to the center of the rotor core 1.

[0030] By bringing the concave side of the magnetic flux closer to the center of the rotor core 1, the distribution utilization rate of the magnets in a unit space is improved, thus ensuring the amount of magnets used. On the other hand, this structure can also improve the air gap magnetic flux density and sinusoidal properties, resulting in a better sinusoidal back EMF waveform and a lower harmonic content. As the harmonic content is higher, the torque pulsation generated by the rotor core 1 also decreases.

[0031] Preferably, the first magnet slot unit 3 includes multiple magnet slots, which form a curved chain structure, with the notches formed by the curved chain structure facing the center of the rotor core 1. By setting the first magnet slot unit 3 to multiple magnet slots, on the one hand, the processing difficulty of the magnet slots can be reduced, and the structural strength of the rotor core 1 can be improved; on the other hand, it is beneficial to fill the magnet slots with the first permanent magnet, further improving the air gap density and sinusoidal property.

[0032] Preferably, the multiple magnetic slots are divided into N layers from the outer circle of the rotor core 1 to the center of the rotor core 1. From the outer circle of the rotor core 1 to the center of the rotor core 1, they are sequentially the first layer of magnetic slots 301, the second layer of magnetic slots 302, ..., the nth layer of magnetic slots. The first layer of magnetic slots 301 intersects the d-axis of the magnetic pole center line of the rotor core 1. In the second layer of magnetic slots 302 to the nth layer of magnetic slots, the number of slots in each layer is greater than 2 and they are distributed on both sides of the d-axis. The first layer of magnetic slots 301 to the nth layer of magnetic slots are in a stepped shape.

[0033] The first permanent magnet filled in the stepped magnetic steel groove also presents a stepped shape. Compared with the straight magnetic steel motor, the stepped first permanent magnet is closer to the sides, and the magnetic circuit is shorter. According to the magnetic reluctance formula Zm=L / uS (where Zm=L / uS is the magnetic reluctance, L is the length of the magnetic circuit, u is the permeability, and S is the cross-sectional area of ​​the magnetic circuit), it can be seen that the magnetic reluctance is proportional to the length of the magnetic circuit. The magnetic reluctance is smaller closer to the outer layer. According to Ohm's law for magnetic circuits φ=F / Rm (where φ=F / Rm is the magnetic flux, F is the magnetomotive force, and Rm is the magnetic reluctance), it can be seen that when the magnetomotive force is constant, the smaller the magnetic reluctance, the larger the magnetic flux. Correspondingly, since magnetic density = magnetic flux / magnetic circuit cross-sectional area, the magnetic density is also larger, and the waveform is more sinusoidal.

[0034] Preferred, such as Figure 2 As shown, each of the multiple magnetic slots is rectangular, with the long side of the slot perpendicular to the d-axis, and the short sides of two adjacent slots overlapping.

[0035] The rectangular design not only facilitates processing, but also improves the continuity of the magnetic flux and the stability of the electromagnetic force of the rotor core 1 by overlapping the short sides, which is more conducive to increasing the length of the magnetic circuit.

[0036] Preferably, the width of the magnetic steel groove decreases from the first layer of magnetic steel groove 301 to the nth layer of magnetic steel groove; the length of the first layer of magnetic steel groove 301 is L1, the total length of the first magnetic steel groove unit 3 is L, and 1 / 3L≤L1≤1 / 2L.

[0037] The variation in the width of the magnet slots results in the widest width of the first layer magnet slot 301, which is the widest magnet slot in the middle of the first magnet slot unit 3 in the circumferential direction. This maximizes the amount of the first permanent magnet in the first magnet slot. When the amount of the first permanent magnet in the first layer magnet slot 301 is maximized, the magnetomotive force of the magnet in the first magnet slot is maximized. With a fixed magnetic circuit, the greater the magnetomotive force, the greater the corresponding magnetic flux and magnetic density.

[0038] Considering the actual processing and the diameter of the rotor core 1, the value of N can be adjusted. When N = 2, that is, the first magnetic slot unit 3 includes two layers of magnetic slots, the width of the first layer of magnetic slot 301 is t2, and the width of the second layer of magnetic slot 302 is t3, t2 > t3. Further, 0.5t2 < t3 < 0.8t2 can be made, and with 1 / 3L ≤ L1 ≤ 1 / 2L, the magnetomotive force generated by the first permanent magnet in the first layer of magnetic slot 301 is maximized while ensuring the structural strength and production efficiency of the rotor core 1. The corresponding rated magnetic flux is also larger, and the magnetic density is also larger.

[0039] Preferably, the first magnet is a rare earth magnet 5; the remanence of the rare earth magnets 5 filling the first layer of magnet slots 301 to the nth layer of magnet slots decreases sequentially.

[0040] The rare earth magnets 5 filled in the first layer of magnet slot 301 have the largest remanence. Generally, high-grade magnets, such as 52SH, can be selected. The rare earth magnets 5 in the second layer are of grade 42SH, and the rare earth magnets 5 in the third layer are of grade 39SH, and so on. The larger the magnet grade, the larger the remanence, the larger the magnetic energy product, and the larger the magnetomotive force. The rare earth magnets 5 with larger magnet grades are filled in the first layer of magnet slot 301 (that is, the rare earth magnets 5 with larger magnet grades are filled in the middle of the first magnet slot unit 3). The magnetomotive force in the middle part increases accordingly, while the magnetic reluctance does not change. At this time, the magnetic flux increases accordingly, the corresponding air gap magnetic density increases, and thus the sinusoidal nature of the air gap magnetic density is improved.

[0041] Preferred, such as Figure 1 and Figure 2 As shown, the magnetic pole also has a second magnetic slot unit 2. In the radial direction of the rotor core 1, the second magnetic slot unit 2 is arranged radially outside the first magnetic slot unit 3. The second magnetic slot unit 2 is an arc-shaped magnetic slot, with the concave side of the arc-shaped magnetic slot facing the center of the rotor core 1. The arc-shaped magnetic slot is filled with ferrite magnet 4201. The arrangement of the second magnetic slot unit 2 on the outer layer of the first magnetic slot unit 3, and its arc-shaped design with ferrite magnet 4 filling the arc-shaped magnetic slot, results in a larger magnetomotive force near the d-axis of the magnetic pole centerline, further optimizing the sinusoidal nature of the air gap magnetic flux density.

[0042] Furthermore, the widest part of the arc-shaped magnet groove in the radial direction is t1, such that t1 > t2 > t3; furthermore, the effective pole angle of the ferrite magnet 4201 is θ3, then... The rotor central angle corresponding to the pole pitch of rotor core 1 is θ1, then θ1 = 360° / 2p, where p is the number of rotor pole pairs and p ≥ 1; the effective pole angle of the flux linkage is θ2, then...

[0043] Through formula It is beneficial to utilize the sinusoidal nature of the opposite electromotive force during motor operation to reduce cogging torque pulsation.

[0044] Furthermore, the amount of rare earth magnets 5 in the first layer of magnet slot 301 is not less than 1 / 3 of the total amount of rare earth magnets 5 in the first magnet slot unit 3. In this way, leakage flux is effectively reduced, motor harmonics are reduced, and the noise of motor operation is reduced.

[0045] When both the first magnet slot unit 3 and the second magnet slot unit 2 are asymmetrical about the d-axis, it is beneficial to improve the sinusoidal utilization of the opposite electromotive force during motor operation and reduce the cogging torque pulsation.

[0046] When the second magnet slot unit 2 is symmetrical about the d-axis, and the first magnet slot unit 3 is symmetrical about the d-axis, the stability of the rotor core 1 under force during rotation is improved. Of course, it is also possible to make neither the second magnet slot unit 2 nor the first magnet slot unit 3 symmetrical about the d-axis, in which case the cogging torque of the motor can be reduced, and the generation of harmonics can be reduced.

[0047] Secondly, the present invention provides a permanent magnet synchronous motor, including the aforementioned motor rotor. When the permanent magnet synchronous motor using the aforementioned motor rotor is in operation, the motor operates stably, with reduced pulsation and noise; effectively reducing the operating cost of the permanent magnet synchronous motor and improving its working efficiency.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A motor rotor, characterized in that, Includes a rotor core (1), the rotor core (1) has multiple magnetic poles, each magnetic pole has a first magnetic steel slot unit (3) and a magnetic pole center line d axis corresponding to the magnetic pole, the first magnetic steel slot unit (3) is filled with a first permanent magnet, the first permanent magnet forms a magnetic chain; On a cross section perpendicular to the center line of the rotor core (1), the magnetic flux has a recessed side and a raised side opposite to the recessed side in the d-axis direction; the recessed side of the magnetic flux is close to the center of the rotor core (1). The first magnet slot unit (3) includes multiple magnet slots, which form a curved chain structure, and the notch formed by the curved chain structure faces the center of the rotor core (1). The plurality of magnetic steel slots are divided into N layers from the outer circle of the rotor core (1) to the center of the rotor core (1). The layers from the outer circle near the rotor core (1) to the center of the rotor core (1) are the first layer of magnetic steel slots (301), the second layer of magnetic steel slots (302) ... the nth layer of magnetic steel slots. The first layer of magnetic steel slots (301) intersects the magnetic pole center line d-axis of the rotor core (1). From the second layer of magnetic steel slots (302) to the nth layer of magnetic steel slots, the number of magnetic steel slots in each layer is greater than 2 and they are located on both sides of the d-axis. The first layer of magnetic steel slots (301) to the nth layer of magnetic steel slots are in a stepped shape.

2. The motor rotor according to claim 1, characterized in that, Each of the plurality of magnetic steel slots is rectangular, with the long side of the magnetic steel slot perpendicular to the d-axis, and the short sides of two adjacent magnetic steel slots overlapping.

3. The motor rotor according to claim 2, characterized in that, From the first layer of magnetic steel groove (301) to the nth layer of magnetic steel groove, the width of the magnetic steel groove decreases; the length of the first layer of magnetic steel groove (301) is L1, and the total length of the first magnetic steel groove unit (3) is L, 1 / 3L≤L1≤1 / 2L.

4. The motor rotor according to claim 3, characterized in that, The first magnet is a rare earth magnet (5); the remanence of the rare earth magnets (5) filled in the first layer magnet groove (301) to the nth layer magnet groove decreases sequentially.

5. The motor rotor according to any one of claims 1-4, characterized in that, The pole distance of the rotor core (1) is the corresponding rotor center angle θ1, and the effective angle of the magnetic pole of the magnetic flux is θ2, then 0.7≤θ2 / θ1≤0.

8.

6. The motor rotor according to claim 5, characterized in that, The magnetic pole also has a second magnetic slot unit (2), which is located outside the first magnetic slot unit in the radial direction of the rotor core (1).

7. The motor rotor according to claim 6, characterized in that, The second magnet slot unit (2) is an arc-shaped magnet slot, and the concave side of the arc-shaped magnet slot faces the center of the rotor core (1).

8. The motor rotor according to claim 7, characterized in that, The arc-shaped magnetic groove is filled with ferrite magnet (4), and the effective angle of the magnetic pole of the ferrite magnet (4) is θ3, then 0.6≤θ3 / θ2≤0.

8.

9. A permanent magnet synchronous motor, characterized in that, Includes an electric motor rotor as described in any one of claims 1-8.

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