Electrical equipment, permanent magnet motors and their rotors

Abstract

The present invention relates to the field of motors, and provides an electrical device, a permanent magnet motor, and a rotor thereof. The rotor includes an iron core and multiple groups of magnetic steel, each group of magnetic steel being arranged in a circumferential array. The number of first and second groups of slots for mounting the magnetic steel is equal, and each group has at least two groups. Each first group of slots and each second group of slots are staggered circumferentially. The first group of slots has a first inner slot and a first outer slot, and the second group of slots has a second inner slot and a second outer slot. Two adjacent groups of magnetic steel are symmetrically distributed on both sides of a symmetry plane. In the circumferentially adjacent first and second groups of slots, the space between the first outer slot and the symmetry plane corresponds to a first central angle, and the space between the second outer slot and the symmetry plane corresponds to a second central angle. The absolute value of the difference between the first and second central angles is greater than 0° and less than 2.5°. This is beneficial for reducing the torque pulsation and harmonic content of the permanent magnet motor, and is beneficial for improving the performance of the permanent magnet motor.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular to an electrical device, a permanent magnet motor and a rotor thereof. Background Art

[0002] The performance of permanent magnet motors is mainly measured by three indicators: torque, torque ripple and harmonic content.

[0003] The stronger the torque pulsation, the stronger the vibration and noise of the permanent magnet motor; the greater the back electromotive force harmonic content, the more magnetic field harmonics the magnet generates in the air gap, and the back electromotive force harmonics will cause additional losses in the motor and generate more heat.

[0004] To improve the torque of a permanent magnet motor, a Chinese utility model patent with publication number CN208423971U proposes a double-layer V-shaped internal permanent magnet synchronous motor rotor. This solution can effectively improve the torque. However, the permanent magnet motor of this solution has strong torque pulsation and back electromotive force harmonics, resulting in strong vibration and noise of the permanent magnet motor, unstable motor operation, high energy consumption and low efficiency. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a rotor for a permanent magnet motor that is beneficial to reducing motor vibration noise and improving operating efficiency.

[0006] To achieve the above-mentioned object, the present invention provides a rotor of a permanent magnet motor comprising an iron core and a plurality of magnetic steels, the iron core having a plurality of mounting slots, each magnetic steel being embedded in each mounting slot in a one-to-one correspondence, the plurality of magnetic steels being divided into at least four groups, each group of magnetic steels being distributed in an array along the circumferential direction; the plurality of mounting slots being divided into a first group of slots and a second group of slots, the first group of slots and the second group of slots being equal in number and each having at least two groups, each first group of slots and each second group of slots being staggered along the circumferential direction, the first group of slots having a first inner slot and a first outer slot located radially outward of the first inner slot, the second group of slots having a second inner slot and a second outer slot located radially outward of the second inner slot; a symmetry plane passing through the motor axis is provided between two circumferentially adjacent groups of magnetic steels, the two groups of magnetic steels being symmetrically distributed on both sides of the symmetry plane, and in the circumferentially adjacent first and second groups of slots, the space between the first outer slot and the symmetry plane corresponds to a first central angle, the space between the second outer slot and the symmetry plane corresponds to a second central angle, and the absolute value of the difference between the first central angle and the second central angle is greater than 0° and less than 2.5°.

[0007] As can be seen from the above, the present invention, through the structural design of the rotor of the permanent magnet motor, sets the absolute value of the difference between the first central angle and the second central angle to be greater than 0° and less than 2.5°, which is beneficial to reducing the torque pulsation and harmonic content of the permanent magnet motor, reducing the vibration noise and energy consumption of the permanent magnet motor, and improving the efficiency of the permanent magnet motor and improving the performance of the permanent magnet motor.

[0008] In existing permanent magnet motors with built-in magnets, the slots for installing the magnets and the magnets are distributed in an array, and the two adjacent groups of magnet slots are also symmetrically arranged. However, the present invention sets the adjacent magnet slots to be asymmetrical, thereby reducing the torque pulsation and harmonic content of the permanent magnet motor.

[0009] A preferred solution is that the first inner groove includes two first grooves spaced apart along the circumferential direction, and in the cross-section with the normal along the axial direction, the cross-sectional shape of the first groove is strip-shaped, and the two first grooves of the same first inner groove are arranged in a V-shape; the first outer groove includes two second grooves spaced apart along the circumferential direction, and in the cross-section with the normal along the axial direction, the cross-sectional shape of the second groove is strip-shaped, and the two second grooves of the same first outer groove are arranged in a V-shape; the second inner groove includes two third grooves spaced apart along the circumferential direction, and in the cross-section with the normal along the axial direction, the cross-sectional shape of the third groove is strip-shaped, and the two third grooves of the same second inner groove are arranged in a V-shape; the second outer groove includes two fourth grooves spaced apart along the circumferential direction, and in the cross-section with the normal along the axial direction, the cross-sectional shape of the fourth groove is strip-shaped, and the two fourth grooves of the same second outer groove are arranged in a V-shape.

[0010] As can be seen from the above, in each group of magnetic steels, the inner magnetic steel and the outer magnetic steel have a V-shaped cross-section along the normal line of the motor axis, which is beneficial to improving the torque of the motor.

[0011] A further solution is that the distance from the first inner slot to the outer periphery of the iron core and the distance from the second inner slot to the outer periphery of the iron core are both the first distance, the distance between the two first slots of the same first inner slot and the distance between the two third slots of the same second inner slot are both the second distance, and the second distance is 1 to 4 times the first distance; and / or the distance from the first outer slot to the outer periphery of the iron core and the distance from the second outer slot to the outer periphery of the iron core are both the third distance, the distance between the two second slots of the same first outer slot and the distance between the two fourth slots of the same second outer slot are both the fourth distance, and the fourth distance is 1 to 4 times the third distance.

[0012] It can be seen from the above that this is beneficial to reducing the torque pulsation of the permanent magnet motor and improving the performance of the permanent magnet motor.

[0013] Another preferred solution is that the space between the first inner groove and the symmetry plane corresponds to the third central angle, the space between the second inner groove and the symmetry plane corresponds to the fourth central angle, and the absolute value of the difference between the third central angle and the fourth central angle is greater than 0° and less than or equal to 1°.

[0014] As can be seen from the above, this is conducive to balancing the harmonic content and torque pulsation of the permanent magnet motor.

[0015] A further solution is that the sum of the central angles of the space between the first outer groove and the second outer groove is 158.4° to 223.2°; and / or the sum of the central angles of the space between the first inner groove and the second inner groove is 36° to 72°.

[0016] Another preferred solution is that the magnetic steel in the first inner slot and the magnetic steel in the second inner slot are both inner magnetic steels, and the magnetic steel in the first outer slot and the magnetic steel in the second outer slot are both outer magnetic steels.

[0017] A further solution is that the thickness of the inner magnetic steel layer is 2 to 3 times the thickness of the outer magnetic steel layer.

[0018] A further solution is that the distance from the inner layer of magnetic steel to the outer periphery of the iron core is 1.5 to 3 times the distance from the outer layer of magnetic steel to the outer periphery of the iron core.

[0019] A further solution is that the pole arc coefficient of the outer magnetic steel layer is 0.27 to 0.3; and / or the pole arc coefficient of the inner magnetic steel layer is 0.63 to 0.68.

[0020] As can be seen from the above, this is beneficial to balancing the torque and torque ripple of the permanent magnet motor.

[0021] A further solution is that the sum of the pole arc coefficient of the inner magnetic steel layer and the pole arc coefficient of the outer magnetic steel layer is 0.9 to 0.95.

[0022] A second object of the present invention is to provide a permanent magnet motor that is beneficial to reducing motor vibration and noise.

[0023] In order to achieve the above-mentioned object, the permanent magnet motor provided by the present invention includes the rotor of the above-mentioned permanent magnet motor.

[0024] A third object of the present invention is to provide an electrical device that is beneficial to reducing motor vibration and noise.

[0025] In order to achieve the above-mentioned object, the electrical equipment provided by the present invention includes the aforementioned permanent magnet motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view of an embodiment of a rotor of a permanent magnet motor of the present invention. DETAILED DESCRIPTION

[0027] Electrical equipment, permanent magnet motor and rotor thereof embodiments:

[0028] The electrical equipment of this embodiment may be, for example, an electric car, a robot, a CNC machine tool, etc.

[0029] Please refer to Figure 1The electrical equipment of this embodiment includes the permanent magnet motor of this embodiment. The permanent magnet motor of this embodiment includes a stator (not shown in the figure) and a rotor of this embodiment. The rotor includes an iron core 1 and a plurality of magnets 2. The iron core 1 is annular and has a plurality of mounting grooves 11. Each magnet 2 is embedded in each mounting groove 11 in a one-to-one correspondence.

[0030] The mounting slots 11 are divided into eight groups, i.e., the number of poles P of the rotor is 8, of which four groups are first-group slots 11a and the other four groups are second-group slots 11b. The first-group slots 11a and the second-group slots 11b are staggered along the circumferential direction. The magnetic steels 2 in each group of mounting slots 11 form a group, and the magnetic steels 2 in each group are arranged in an array along the circumferential direction.

[0031] Optionally, in other embodiments of the present invention, the rotor technology may also be adjusted.

[0032] Each first group of grooves 11a includes two first grooves 112a and two second grooves 111a. In the same first group of grooves 11a, the two first grooves 112a are distributed at intervals along the circumferential direction, and the two second grooves 111a are distributed at intervals along the circumferential direction. The two first grooves 112a constitute a first inner groove, and the two second grooves 111a constitute a first outer groove. The first outer groove is located radially outside the first inner groove.

[0033] In the cross section along the axial direction, the cross-sectional shapes of the first groove 112a and the second groove 111a are both strip-shaped. The two first grooves 112a in the same first group of grooves 11a are arranged in a V shape, and the two second grooves 111a in the same first group of grooves 11a are arranged in a V shape.

[0034] Each second group of grooves 11b includes two third grooves 112b and two fourth grooves 111b. In the same second group of grooves 11b, the two third grooves 112b are distributed at intervals along the circumferential direction, and the two fourth grooves 111b are distributed at intervals along the circumferential direction. The two third grooves 112b constitute the second inner groove, and the two fourth grooves 111b constitute the second outer groove.

[0035] In the cross section along the axial direction, the cross-sectional shapes of the third groove 112b and the fourth groove 111b are both strip-shaped, the two third grooves 112b in the same second group of grooves 11b are arranged in a V shape, and the two fourth grooves 111b in the same second group of grooves 11b are arranged in a V shape.

[0036] A magnetic steel 2 is provided in each first slot 112a, each second slot 111a, each third slot 112b and each fourth slot 111b. The magnetic steel 2 located in the first slot 112a and the third slot 112b is an inner magnetic steel 22, and the magnetic steel 2 located in the second slot 111a and the fourth slot 111b is an outer magnetic steel 21.

[0037] The magnetic steels 2 in the same group are symmetrically distributed. The symmetric plane of two adjacent groups of magnetic steels 2 is the first plane x, and the symmetric plane of the magnetic steels 2 in the same group is the second plane y. Both the first plane x and the second plane y pass through the motor axis.

[0038] In the first group of grooves 11a and the second group of grooves 11b adjacent to each other in the circumferential direction, the space between the first groove 112a and the first surface x corresponds to the third central angle β3, the space between the second groove 111a and the first surface x corresponds to the first central angle β1, the space between the third groove 112b and the first surface x corresponds to the fourth central angle β4, and the space between the fourth groove 111b and the first surface x corresponds to the second central angle β2. The first central angle β1 is 12°, the second central angle β2 is 14°, the third central angle β3 is 4°, and the fourth central angle β4 is 3°. The difference between the third central angle β3 and the fourth central angle β4 is 1°, and the difference between the second central angle β2 and the first central angle β1 is 2°.

[0039] The sum of each first central angle β1 and each second central angle β2 is (12°+14°)*8=208°, and the sum of each third central angle β3 and each fourth central angle β4 is (4°+3°)*8=56°.

[0040] Optionally, the difference between the third central angle β3 and the fourth central angle β4 is greater than 0° and less than or equal to 1°, and the difference between the second central angle β2 and the first central angle β1 is greater than 0° and less than 2.5°.

[0041] The ratio of the thickness of the inner magnetic steel 22 to the thickness of the outer magnetic steel 21 is 2.5. Optionally, in other embodiments of the present invention, the thickness of the inner magnetic steel 22 is 2 to 3 times the thickness of the outer magnetic steel 21 .

[0042] The distance from the inner magnetic steel 22 to the outer periphery of the core is 1.5 times the distance from the outer magnetic steel 21 to the outer periphery of the core. Optionally, in other embodiments of the present invention, the distance from the inner magnetic steel 22 to the outer periphery of the core is 1.5 to 3 times the distance from the outer magnetic steel 21 to the outer periphery of the core.

[0043] The pole arc angle of the inner magnetic steel 22 is α2 = 28.8°, and the pole arc angle of the outer magnetic steel 21 is α1 = 12.6°; the pole arc coefficient of the inner magnetic steel 22 is α2 / (360° / P) = 0.64, and the pole arc coefficient of the outer magnetic steel 21 is α1 / (360° / P) = 0.28.

[0044] The distance from the first slot 112a to the outer periphery of the iron core and the distance from the third slot 112b to the outer periphery of the iron core are both the first distance d1, the first distance d1 is the distance between the two first slots 112a of the same first inner slot and the distance between the two third slots 112b of the same second inner slot are both the second distance d2, and the second distance d2 is 1.3 times the first distance d1.

[0045] Alternatively, in other embodiments of the present invention, the second distance d2 is 1 to 4 times the first distance d1.

[0046] The distance from the first outer slot to the outer periphery of the iron core and the distance from the second outer slot to the outer periphery of the iron core are both the third distance d3, the distance between the two second slots 111a of the same first outer slot and the distance between the two fourth slots 111b of the same second outer slot are both the fourth distance d4, and the third distance d3 is equal to the fourth distance d4.

[0047] Alternatively, in other embodiments of the present invention, the fourth distance d4 is 1 to 4 times the third distance d3.

[0048] In order to illustrate the technical effect of the technical solution of this embodiment, a comparative example is introduced, and the torque, torque pulsation and harmonic content of each example are obtained through simulation experiments. The relevant parameters of this embodiment and the comparative example are shown in Table 1.

[0049] Table 1: Parameter comparison table of this embodiment and comparative example

[0050] Comparative Example This embodiment Outer magnetic steel 21 pole arc coefficient 0.28 0.28 Inner magnetic steel 22 pole arc coefficient 0.64 0.64 Thickness ratio of inner and outer magnetic steel 2.5 2.5 The distance ratio between the inner and outer magnetic steel layers and the outer periphery of the core 1.5 1.5 First central angle β1 13° 12° The second central angle β2 13° 14° The third central angle β3 3.5° 4° Fourth central angle β4 3.5° 3° Torque 275.9Nm 275Nm Torque ripple 3.8％ 3.3％ Harmonic content 6.4％ 5.2％

[0051] By comparing the relevant parameters of the present embodiment and the comparative example in the above table, it can be seen that the difference between the comparative example and the present embodiment is only that the values ​​of the third central angle β3, the first central angle β1, the fourth central angle β4, and the second central angle β2 are different. The third central angle and the fourth central angle of the comparative example are both 3.5°, and the first central angle and the second central angle are both 13°. In addition, compared with the comparative example, the torque of the present embodiment is reduced by (275.9-275) / 275.9=3.26%, the torque pulsation of the present embodiment is reduced by (3.8-3.3) / 3.8=13.16%, and the harmonic content of the present embodiment is reduced by (6.4-5.2) / 6.4=18.75%. That is, by changing the numerical relationship between the third central angle β3, the first central angle β1, the fourth central angle β4, and the second central angle β2, the torque pulsation of the present embodiment is significantly weakened, the harmonic content is significantly reduced, and the impact on the torque is small.

[0052] In this embodiment and the comparative example, the total amount of the inner magnetic steel 22 and the outer magnetic steel 21 remains unchanged.

[0053] In addition, in order to further clarify the technical effect of changing the numerical values ​​of the third central angle β3, the first central angle β1, the fourth central angle β4, and the second central angle β2, on the basis of the outer layer magnetic steel 21 having a pole arc coefficient of 0.28, the inner layer magnetic steel 22 having a pole arc coefficient of 0.64, the inner and outer layer magnetic steel thickness ratio = 2.5, the inner and outer layer magnetic steel distance ratio from the outer periphery of the iron core = 1.5, (β2+β4) / (360° / P) = 0.58, (β1+β3) / (360° / P) = 0.16, by changing the specific numerical values ​​of the third central angle β3, the first central angle β1, the fourth central angle β4 and the second central angle β2, the changes in torque, torque pulsation and harmonic content are detected.

[0054] Table 2: Torque variation table

[0055]

[0056] Table 3: Harmonic content changes

[0057]

[0058] Table 4: Torque ripple change table

[0059]

[0060] It can be seen from Table 2 that although setting the first central angle β1 and the second central angle β2 to be unequal and setting the third central angle β3 and the fourth central angle β4 to be unequal will cause the torque of the permanent magnet motor to decrease, the magnitude of the torque reduction of the permanent magnet motor is small.

[0061] As can be seen from Table 3, setting the first central angle β1 and the second central angle β2 to be unequal and setting the third central angle β3 and the fourth central angle β4 to be unequal will cause the harmonic content of the motor to fluctuate greatly, and the difference between the third central angle β3 and the fourth central angle β4 is in the range of -1° to 1° and the difference between the first central angle β1 and the second central angle β2 is in the range of -2°.

[0062] When the angle is within the range of -1 to 2°, the harmonic content is small, especially when the difference between the third central angle β3 and the fourth central angle β4 is about -1° and the difference between the second central angle β2 and the first central angle β1 is about 2° (or β3-β4=about 1°, and β1-β2=about-2°), the harmonic content is reduced to the lowest.

[0063] As can be seen from Table 4, setting the first central angle β1 and the second central angle β2 to be unequal, and setting the third central angle β3 and the fourth central angle β4 to be unequal, will cause the magnitude of the motor torque ripple to fluctuate greatly. When the difference between the third central angle β3 and the fourth central angle β4 is in the range of -1° to 1° and the difference between the first central angle β1 and the second central angle β2 is in the range of -2° to 2°, the torque ripple is small. In particular, when the difference between the third central angle β3 and the fourth central angle β4 is about 1° and the difference between the second central angle β2 and the first central angle β1 is about 2° (or when β3 - β4 = about -1° and β1 - β2 = about -2°), the torque ripple is reduced to a minimum.

[0064] Combining Table 3 and Table 4, it can be seen that when the value of β3-β4 remains unchanged, as the absolute value of β1-β2 increases from 0° to 2°, the harmonic content and torque ripple gradually decrease. Therefore, in this embodiment, the absolute value of β1-β2 is preferably 2°.

[0065] Moreover, when the value of β1-β2 remains unchanged, the harmonic content and torque pulsation both have minimum values, and the minimum value of torque pulsation and the minimum value of torque pulsation are respectively located on the positive and negative sides of β3-β4=0°. Therefore, it is necessary to select the specific value of β3-β4 according to the motor's requirements for harmonic content and torque pulsation. Of course, it is preferred that the absolute value of β3-β4 is less than or equal to 1°.

[0066] To illustrate the technical effect of the inner and outer magnetic steel pole arc coefficients of this embodiment, the following experiment was conducted. In this experiment, the ratio of the inner and outer magnetic steel thicknesses was 2.5, the ratio of the distances of the inner and outer magnetic steels from the outer periphery of the core was 1.5, β3 = β4 = 3.5°, β1 = β2 = 13°, and the torque and torque ripple were measured under different inner and outer magnetic steel pole arc coefficients, resulting in the following Tables 5 and 6.

[0067] Table 5:

[0068]

[0069] Table 6:

[0070]

[0071] Table 5 shows the torque variation under different inner layer magnetic steel pole arc coefficients and different outer layer magnetic steel pole arc coefficients, and Table 6 shows the torque ripple variation under different inner layer magnetic steel pole arc coefficients and different outer layer magnetic steel pole arc coefficients.

[0072] It can be seen from Table 5 that the change of the pole arc coefficient of the inner and outer magnetic steel has little effect on the torque of the permanent magnet motor.

[0073] It can be seen from Table 6 that when the pole arc coefficient of the inner magnetic steel is small, the torque ripple of the permanent magnet motor decreases as the pole arc coefficient of the outer magnetic steel increases; when the pole arc coefficient of the inner magnetic steel is large, the torque ripple of the permanent magnet motor increases as the pole arc coefficient of the outer magnetic steel increases.

[0074] Therefore, in this embodiment, the pole arc coefficient of the inner magnetic steel 22 is preferably 0.63 to 0.68, and the pole arc coefficient of the outer magnetic steel 21 is preferably 0.27 to 0.3. More preferably, the sum of the pole arc coefficients of the inner magnetic steel 22 and the outer magnetic steel 21 is 0.9 to 0.95.

[0075] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rotor for a permanent magnet motor, comprising an iron core and a plurality of magnets, wherein the iron core has a plurality of mounting slots, wherein the magnets are embedded in the mounting slots in a one-to-one correspondence, and wherein the magnets are divided into at least four groups, wherein the magnets in each group are arranged in a circumferential array; Its characteristics are: The plurality of mounting grooves are divided into a first group of grooves and a second group of grooves, the first group of grooves and the second group of grooves are equal in number and each group has at least two groups, the first group of grooves and the second group of grooves are staggered along the circumferential direction, the first group of grooves includes a first inner groove and a first outer groove located radially outward of the first inner groove, and the second group of grooves includes a second inner groove and a second outer groove located radially outward of the second inner groove; A symmetry plane passing through the motor axis is defined between two circumferentially adjacent groups of magnetic steels. The two groups of magnetic steels are symmetrically distributed on both sides of the symmetry plane. In circumferentially adjacent first and second groups of slots, the space between the first outer slot and the symmetry plane corresponds to a first central angle, the space between the second outer slot and the symmetry plane corresponds to a second central angle, and the absolute value of the difference between the first and second central angles is greater than 0° and less than 2.5°. The space between the first inner groove and the symmetry plane corresponds to a third central angle, the space between the second inner groove and the symmetry plane corresponds to a fourth central angle, and the absolute value of the difference between the third central angle and the fourth central angle is greater than 0° and less than or equal to 1°, so as to reduce torque pulsation and harmonic content.

2. The rotor according to claim 1, characterized in that: The first inner groove includes two first grooves spaced apart along the circumferential direction, wherein in a cross section with a normal line along the axial direction, the cross section of the first groove is strip-shaped, and the two first grooves of the same first inner groove are arranged in a V shape; The first outer groove includes two second grooves spaced apart along the circumferential direction, and in a cross section with a normal line along the axial direction, the cross section of the second groove is strip-shaped, and the two second grooves of the same first outer groove are arranged in a V shape; The second inner groove includes two third grooves spaced apart along the circumferential direction, wherein in a cross section with a normal line along the axial direction, the cross section of the third groove is strip-shaped, and the two third grooves of the same second inner groove are arranged in a V shape; The second outer groove includes two fourth grooves spaced apart along the circumferential direction. In a cross section with a normal line along the axial direction, the cross section of the fourth groove is strip-shaped. The two fourth grooves of the same second outer groove are arranged in a V shape.

3. The rotor according to claim 2, wherein: The distance from the first inner slot to the outer periphery of the iron core and the distance from the second inner slot to the outer periphery of the iron core are both first distances, the distance between the two first slots of the same first inner slot and the distance between the two third slots of the same second inner slot are both second distances, and the second distance is 1 to 4 times the first distance; and / or The distance from the first outer slot to the outer periphery of the iron core and the distance from the second outer slot to the outer periphery of the iron core are both third distances, the distance between the two second slots of the same first outer slot and the distance between the two fourth slots of the same second outer slot are both fourth distances, and the fourth distance is 1 to 4 times the third distance.

4. The rotor according to claim 1, wherein: The sum of the central angles of the space between the first outer groove and the second outer groove is 158.4° to 223.2°; And / or the sum of the central angles corresponding to the space between the first inner groove and the second inner groove is 36° to 72°.

5. The rotor according to any one of claims 1 to 4, characterized in that: The magnetic steel in the first inner slot and the magnetic steel in the second inner slot are both inner magnetic steels, and the magnetic steel in the first outer slot and the magnetic steel in the second outer slot are both outer magnetic steels.

6. The rotor according to claim 5, characterized in that: The thickness of the inner magnetic steel layer is 2 to 3 times the thickness of the outer magnetic steel layer.

7. The rotor according to claim 5, characterized in that: The distance from the inner magnetic steel layer to the outer periphery of the iron core is 1.5 to 3 times the distance from the outer magnetic steel layer to the outer periphery of the iron core.

8. The rotor according to claim 5, characterized in that: The pole arc coefficient of the outer layer magnetic steel is 0.27 to 0.3; and / or the pole arc coefficient of the inner layer magnetic steel is 0.63 to 0.

68.

9. The rotor according to claim 5, characterized in that: The sum of the pole arc coefficient of the inner magnetic steel layer and the pole arc coefficient of the outer magnetic steel layer is 0.9 to 0.

95.

10. Permanent magnet motor, characterized in that: A rotor comprising a permanent magnet motor according to any one of claims 1 to 9.

11. Electrical equipment, characterized in that: It comprises the permanent magnet motor as claimed in claim 10.

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