Magnetic steel structure, rotor core, rotor and motor

Abstract

The invention provides a magnetic steel structure, a rotor core, a rotor and a motor, the magnetic steel structure comprises magnetic steel, the magnetic steel is installed in the rotor core, and one end of the magnetic steel facing the peripheral wall of the rotor core is a bevel edge. According to the invention, the technical problem of low magnetic steel utilization rate of the motor in the prior art can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and in particular relates to a magnetic steel structure, a rotor core, a rotor and a motor. Background Art

[0002] The permanent magnet motors currently used in the industry are trending towards miniaturization, while also requiring the improvement of motor performance, not limited to efficiency, but the improvement of various aspects of performance, such as operating stability, noise, life, etc.

[0003] The basic principle of permanent magnet motor drive is to generate a magnetic field that rotates and changes around the rotor by passing three-phase current through the conductor coil winding on the stator, so as to attract the built-in or surface-attached magnetic steel of the rotor to drive the rotor to rotate, thus realizing the energy exchange of converting electrical energy into kinetic energy;

[0004] The built-in magnetic rotor can improve the integrity of the rotor structure, reduce the possibility of magnetic steel falling off, and increase the service life. According to different design requirements, topological structures with different magnetic steel placement positions and magnetic steel usage can be designed. Generally, the built-in rotor magnetic steel structure adopts a rectangular design. The rectangular magnetic steel structure is simple and easy to process and install. The material properties under its structure are stable and the magnetic field is uniform. Its disadvantage is that the magnetic leakage at the ends of adjacent magnetic steel poles is large. In this case, it is necessary to expand the magnetic isolation holes at the ends of the magnetic steel to the stator side to reduce the magnetic leakage, sacrificing the strength of the rotor structure and reducing the space utilization of the magnetic steel in the rotor. Large magnetic leakage will also directly lead to a decrease in the utilization rate of the magnetic steel and reduce the power density of the motor. In order to achieve the design effect, the amount of magnetic steel must be increased to compensate for the reduction in the main magnetic flux caused by the leakage, which increases the production cost. Its advantage is that the processing conditions are mature at this stage and the strength of the magnetic steel is guaranteed.

[0005] At present, how to improve the performance of miniaturized permanent magnet motors while adapting to the development trend of miniaturization, maximize the utilization rate of magnetic steel, increase the magnetic flux and ensure the strength of the rotor structure has become a technical problem that needs to be solved urgently in the industry.

[0006] Since the motor in the prior art has technical problems such as low magnetic steel utilization, the present invention studies and designs a magnetic steel structure, a rotor core, a rotor and a motor. Summary of the invention

[0007] Therefore, the present invention provides a magnetic steel structure, a rotor core, a rotor and a motor, which can solve the technical problem of low magnetic steel utilization rate in the motor in the prior art.

[0008] In order to solve the above problem, the present invention provides a magnetic steel structure, comprising: a magnetic steel, wherein the magnetic steel is installed in a rotor core, and one end of the magnetic steel facing the outer peripheral wall of the rotor core is beveled.

[0009] In some embodiments, taking the cross section of the rotor core as the projection plane, the magnetic steel is in a straight trapezoidal shape, the right-angled side of the magnetic steel faces the center of the rotor core, and an angle A1 is formed between the hypotenuse of the magnetic steel and the base of the magnetic steel, and the range of the angle A1 is 127° to 130°.

[0010] The present invention also provides a rotor core, comprising the above-mentioned magnetic steel structure.

[0011] In some embodiments, a plurality of groups of magnetic steel slot groups are provided on the rotor core along the circumference of the rotor core, and one group of the magnetic steel slot groups includes two magnetic steel slots, and the two magnetic steel slots are arranged in a V-shape, and an opening of one group of the magnetic steel slot groups faces the outer peripheral wall of the rotor core, and the magnets are installed in the magnetic steel slots.

[0012] In some embodiments, in a group of the magnetic steel slot groups, the angle between two adjacent magnetic steels is A2, and the range of the angle A2 is 115° to 125°. In some embodiments, the radius of the rotor core is R1, and the maximum distance between the magnetic steel slot and the center of the rotor core is R2, which satisfies R1-R2≤L, 0.5mm≤L≤0.6mm.

[0013] In some embodiments, the cross section of the rotor core is taken as the projection surface, the area of ​​the magnetic steel slot is S1, the area of ​​the magnetic steel is S2, which satisfies that the range of S2 / S1 is 76-79%, 30mm 2 ≤S2≤32mm 2 .

[0014] In some embodiments, a plurality of first grooves are provided on the outer peripheral wall of the rotor core, and the plurality of first grooves are arranged at intervals along the circumferential direction of the rotor core. The first grooves are located in two adjacent groups of the magnetic steel slots, and along the axial direction of the rotor core, the first grooves penetrate the rotor core, and the minimum distance between the first grooves and the magnetic steel slots is S3, which satisfies S3≤L, 0.5mm≤L≤0.6mm.

[0015] The present invention also provides a rotor, comprising the above-mentioned rotor core.

[0016] The present invention also provides a motor, comprising the above-mentioned rotor.

[0017] The magnetic steel structure, rotor core, rotor and motor provided by the present invention have the following beneficial effects:

[0018] One end of the magnetic steel facing the outer peripheral wall of the rotor core is beveled, so that the magnetic steel is trapezoidal. By designing the rectangular bottom surface as a trapezoidal bottom surface while ensuring that the bottom area and the overall mass of the rectangular magnetic steel remain unchanged, and installing the beveled side toward the stator and rotor air gap, the motor efficiency can be improved; the rotor design space of the magnetic steel thickness is saved, and the lateral space utilization of the rotor is improved; because the thickness of the magnetic steel end is thinned, the main magnetic flux magnetic circuit path is optimized, and the peak-to-peak value of the tooth slot torque is reduced, which can prevent the motor starting current peak from being too high, resulting in discontinuous motor operation and increased starting loss; the magnetic flux of the adjacent two-pole magnetic steel in the leakage magnetic flux can be reduced; the sinusoidal degree of the back electromotive force waveform can be optimized, so that the harmonic content of the back electromotive force waveform can be reduced during motor operation, the torque pulsation can be reduced, and the smoothness of the motor operation can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0020] Figure 1 The structure of the magnetic steel structure of the present invention is schematically shown in FIG. Figure 1 ;

[0021] Figure 2 The structure of the magnetic steel structure of the present invention is schematically shown in FIG. Figure 2 ;

[0022] Figure 3 is a schematic structural diagram of a rotor core according to another embodiment of the present invention;

[0023] Figure 4 This is a comparison diagram of the cogging torque between the magnetic steel structure of the present invention and conventional magnetic steel;

[0024] Figure 5 This is a comparison chart of torque pulsation data between the magnetic steel structure of the present invention and conventional magnetic steel;

[0025] Figure 6 This is a comparative analysis diagram of the back electromotive force harmonic content of the magnetic steel structure of the present invention and conventional magnetic steel;

[0026] Figure 7 It is a comparative analysis of the magnetic density cloud diagram of the magnetic steel structure of the present invention and the conventional magnetic steel;

[0027] Figure 8 This is a comparison chart of the efficiency of the magnetic steel structure of the present invention and a conventional magnetic steel motor.

[0028] The accompanying drawings are marked as follows:

[0029] 1. Magnetic steel groove; 2. First groove; 3. Second groove. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0032] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0033] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0034] See also Figure 1-8 As shown, according to an embodiment of the present invention, a magnetic steel structure is provided, comprising: a magnetic steel, wherein the magnetic steel is installed in a rotor core, and one end of the magnetic steel is beveled toward the outer peripheral wall of the rotor core.

[0035] In this technical solution, one end of the magnetic steel facing the outer peripheral wall of the rotor core is beveled, so that the magnetic steel is trapezoidal. By designing the rectangular bottom surface as a trapezoidal bottom surface while ensuring that the bottom area and the overall mass of the rectangular magnetic steel remain unchanged, and installing the beveled side toward the stator and rotor air gap, the motor efficiency can be improved; the rotor design space of the magnetic steel thickness is saved, and the lateral space utilization of the rotor is improved; because the thickness of the magnetic steel end is thinned, the main magnetic flux magnetic circuit path is optimized, and the peak-to-peak value of the tooth slot torque is reduced, which can prevent the motor starting current peak from being too high, resulting in discontinuous motor operation and increased starting loss; the magnetic flux of the adjacent two-pole magnetic steel in the leakage magnetic flux can be reduced; the sinusoidal degree of the back electromotive force waveform can be optimized, so that the harmonic content of the back electromotive force waveform can be reduced during motor operation, the torque pulsation can be reduced, and the smoothness of the motor operation can be improved.

[0036] In some embodiments, taking the cross section of the rotor core as the projection plane, the magnetic steel is in a straight trapezoidal shape, the right-angled side of the magnetic steel faces the center of the rotor core, and an angle A1 is formed between the hypotenuse of the magnetic steel and the base of the magnetic steel, and the range of the angle A1 is 127° to 130°.

[0037] In this technical solution, the rectangular side of the rectangular magnetic steel is designed as a trapezoidal side while ensuring that the bottom area and the overall mass remain unchanged, and the inclined surface is installed toward the stator and rotor air gap. This design can improve the space utilization of the motor rotor.

[0038] The present invention also provides a rotor core, comprising the above-mentioned magnetic steel structure.

[0039] In some embodiments, along the circumference of the rotor core, a plurality of groups of magnetic steel slot groups are provided on the rotor core, one group of the magnetic steel slot groups includes two magnetic steel slots 1, the two magnetic steel slots 1 are arranged in a V shape, and the opening of one group of the magnetic steel slot groups faces the outer peripheral wall of the rotor core, and the magnetic steel is installed in the magnetic steel slot 1. In this technical solution, the first groove 2 and the second groove 3 are respectively provided on both sides of the magnetic steel slot, and the first groove 2 and the second groove 3 are located on the magnetic steel slot 1 near the oblique edge of the magnetic steel, and the first groove 2 and the second groove 3 can be set to an arc shape or an irregular shape, and the first groove and the second groove form an air groove, and the air has the characteristic of high magnetic resistance. Therefore, the first groove and the second groove are used to reduce the leakage magnetic flux between adjacent poles and improve the utilization rate of the magnetic steel.

[0040] The purpose of the first groove 2 and the second groove 3 is to reduce magnetic leakage. The magnetic lines of force between two adjacent poles that should originally follow the stator main magnetic flux path may follow the closest route of the rotor to the other pole, increasing the leakage flux. Slotting is equivalent to increasing the air gap magnetic resistance, forcing the magnetic lines of force to follow the designed main flux path. The design of the slot shape is based on subjective design factors while effectively achieving the above purpose. In fact, as long as it is effective in reducing leakage flux, it can be called a useful slot design.

[0041] In some embodiments, in a group of magnetic steel slot groups, the angle between two adjacent magnetic steels is A2, and the range of the angle A2 is 115°~125°. In this technical solution, the angle A2 of each pair of V-shaped magnetic steels between the same poles meets the angle requirement of 115~125°, and the angle A1 of the magnetic steel cutting angle of each pole is specified to be in the range of 127~130°. Under this design requirement, the shape structure of the magnetic steel cutting angle and the position of the magnetic steel hole of the rotor punching sheet can be fixed, the magnetic flux leakage is reduced, the magnetic circuit flow direction is optimized, the air gap magnetic density waveform is optimized, and the sine waveform of the induced voltage can be optimized, so that the harmonic content of the induced voltage is reduced during the operation of the motor, thereby achieving the effect of reducing torque pulsation, improving the smoothness of the motor operation, and improving the efficiency of the motor.

[0042] In some embodiments, the radius of the rotor core is R1, and the maximum distance between the magnetic steel slot 1 and the center of the rotor core is R2, which satisfies R1-R2≤L, 0.5mm≤L≤0.6mm. Taking the cross section of the rotor core as the projection surface, the area of ​​the magnetic steel slot 1 is S1, and the area of ​​the magnetic steel is S2, which satisfies the range of S2 / S1 is 76-79%, 30mm 2 ≤S2≤32mm 2 . A plurality of first grooves are arranged on the outer peripheral wall of the rotor core, and the plurality of first grooves are arranged at intervals along the circumferential direction of the rotor core. The first grooves are located in two adjacent groups of the magnetic steel slots, and the first grooves penetrate the rotor core along the axial direction of the rotor core. The minimum distance between the first groove and the magnetic steel slot 1 is S3, which satisfies S3≤L, 0.5mm≤L≤0.6mm. In this technical solution, the rotor radius R1 and the outer ring radius R2 of the magnetic steel hole are required to remain concentric with the rotor, and the distance between the magnetic steel hole and the excavated hole is S3≤L. This limits the size requirements of the magnetic steel and limits the size range of the rotor punching. The tangible effect is that the thickness of the magnetic steel end is thinned, the main magnetic flux magnetic circuit path is optimized, the cogging torque is reduced, and the starting torque of the motor is reduced, which can prevent the peak value of the motor starting current from being too high, resulting in discontinuous operation of the motor and increased starting losses.

[0043] The present invention also provides a rotor, comprising the above-mentioned rotor core.

[0044] The rotor of the present invention comprises a rotor core and a rare earth magnet. In practical applications, the permanent magnet synchronous motor comprises five major parts: a stator core, a rotor core, a magnet, an excitation winding and a rotating shaft. The excitation winding on the stator generates a magnetic field rotating along the rotating shaft through three-phase alternating current, and the permanent magnet installed on the rotor is driven by the rotating magnetic field to rotate the connected rotating shaft. This patent is mainly for reducing the magnetic leakage between the poles of the magnet, optimizing the air gap magnetic density waveform, and reducing the harmonic content of the line-to-line back electromotive force by matching the rotor core and the magnet topological structure size, thereby improving the performance of the motor.

[0045] The present invention also provides a motor, comprising the above-mentioned rotor.

[0046] See also Figure 2 As shown, the magnetic steel is cut at an angle of A1, and then Figure 3 For rotor design and magnet installation, when the above size restrictions are met, there is a performance comparison data chart of rectangular magnets and cut-angle magnets. Figure 4 As shown in Figure 8, except for the different magnet shapes, all other parameters of the two motors are exactly the same. When they are set to have the same output torque, the same speed is compared. Figure 4 As shown, the cogging torque of the angled magnetic steel motor is reduced by 40% compared with the rectangular magnetic steel motor, which can reduce the motor starting torque and prevent the motor starting current peak from being too high, causing the motor to work discontinuously and increase the starting loss; Figure 5 This is a comparison chart of motor torque pulsation. The torque pulsation of the angled magnetic steel rotor motor is reduced by nearly 37.5% compared with the rectangular magnetic steel rotor motor, which can make the motor work more smoothly and more stable at low frequency. Figure 6 It is the induced voltage generated when the magnetic field of the rotor cuts the stator winding coil during the operation of the motor. However, since the magnetic field of the rotor is not a completely sinusoidal ideal magnetic field strength distribution, harmonics will appear on the coil winding. The level of harmonic content can affect the stability of the torque output capacity of a motor when it is running to convert electrical energy into kinetic energy, and reduce the service life of the motor. Figure 7 By comparing the effects of angled magnets and rectangular magnets on the rotor, it is found that the magnetic circuit of the angled magnets is optimized, and the magnetic field lines in the rotor and stator boots are observed to be more uniform, which also helps to make the air gap flux waveform more sinusoidal.

[0047] See also Figure 7As shown, by using the cut-angle magnetic steel, the magnetic flux of the magnetic steel on the leakage flux magnetic path in the rotor is reduced. The leakage flux at the end of the rectangular magnetic steel has reached about 3.5T, and it is reduced to about 3.03T after using the cut-angle magnetic steel. The field calculator calculates that the leakage flux coefficient of the cut-angle magnetic steel is 1.2, while the leakage flux coefficient of the rectangular magnetic steel is 1.24. Therefore, by cutting the rectangular magnetic steel structure at a certain angle and matching the rotor size specified in this patent, the leakage flux can be reduced and the magnetic energy loss can be reduced.

[0048] Cutting angle magnets can also improve motor efficiency. Figure 8 As shown, compared with the difference in efficiency of motor models with the same parameters except for the magnetic steel structure mentioned in the patent, the corner magnetic steel motor is 0.15% higher than the rectangular magnetic steel motor.

[0049] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0050] The above description is only 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 principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A magnetic steel structure, characterized in that: include: The magnetic steel is installed in the rotor core, and one end of the magnetic steel facing the outer peripheral wall of the rotor core is beveled.

2. The magnetic steel structure according to claim 1, characterized in that: Taking the cross section of the rotor core as the projection plane, the magnetic steel is in a straight trapezoidal shape, the right-angled side of the magnetic steel faces the center of the rotor core, and there is an angle A1 between the hypotenuse of the magnetic steel and the bottom side of the magnetic steel, and the range of the angle A1 is 127° to 130°.

3. A rotor core, characterized in that: A magnetic steel structure comprising any one of claims 1 to 2.

4. The rotor core according to claim 1, characterized in that: Along the circumference of the rotor core, a plurality of groups of magnetic steel slot groups are arranged on the rotor core, one group of the magnetic steel slot groups comprises two magnetic steel slots (1), the two magnetic steel slots (1) are arranged in a V-shape, and the opening of one group of the magnetic steel slot groups faces the outer peripheral wall of the rotor core, and the magnetic steel is installed in the magnetic steel slots (1).

5. The rotor core according to claim 4, characterized in that: In a group of the magnetic steel slot groups, the angle between two adjacent magnetic steels is A2, and the range of the angle A2 is 115° to 125°.

6. The rotor core according to claim 4, characterized in that: The radius of the rotor core is R1, and the maximum distance between the magnetic steel slot (1) and the center of the rotor core is R2, which satisfies R1-R2≤L, 0.5mm≤L≤0.6mm.

7. The rotor core according to claim 4, characterized in that: Taking the cross section of the rotor core as the projection surface, the area of ​​the magnetic steel slot (1) is S1, and the area of ​​the magnetic steel is S2, which satisfies that the range of S2 / S1 is 76-79%, 30mm 2 ≤S2≤32mm 2 .

8. The rotor core according to claim 4, characterized in that: A plurality of first grooves are arranged on the outer peripheral wall of the rotor core, and the plurality of first grooves are arranged at intervals along the circumferential direction of the rotor core. The first grooves are located in two adjacent groups of magnetic steel slots, and the first grooves penetrate the rotor core along the axial direction of the rotor core. The minimum distance between the first groove and the magnetic steel slot (1) is S3, which satisfies S3≤L, 0.5mm≤L≤0.6mm.

9. A rotor, characterized in that: A rotor core comprising the rotor core according to any one of claims 3 to 8.

10. A motor, characterized in that: Comprising the rotor as claimed in claim 9.

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