Rotor assembly and electric machine having the same

Abstract

The application provides a rotor assembly and a motor with the same, wherein the rotor assembly comprises a rotor core with adjacent first and second magnetic poles; in the first magnetic pole, a permanent magnet slot located at the most inner side of the rotor core in the radial direction is a first permanent magnet slot; in the second magnetic pole, a permanent magnet slot located at the most inner side of the rotor core in the radial direction is a second permanent magnet slot; the first permanent magnet slot is adjacent to the second permanent magnet slot; and the shape of the end of the first permanent magnet slot is different from the shape of the end of the second permanent magnet slot. According to the application, because the shape of the end of the first permanent magnet slot and the shape of the end of the second permanent magnet slot are different in the adjacent two magnetic poles, the asymmetric structure changes the magnetic resistance distribution at each part of the magnetic circuit of the motor, can reduce the cogging effect of the motor, improve the magnetic flux direction, reduce the harmonic content, reduce the electromagnetic force peak value of the motor, and thus reduce the torque ripple of the motor and the electromagnetic vibration noise of the motor.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a rotor assembly and a motor having the same. Background Technology

[0002] Permanent magnet motors rely on permanent magnets to generate the main magnetic field. They possess advantages such as high air gap magnetic flux density, high efficiency, small size, high power density, simple structure, and high reliability, thus being widely used in various industries. Traditional permanent magnet motors often use rare-earth neodymium iron boron (NdFeB) magnets. However, rare earth elements are important strategic reserves, and their production is restricted by upstream raw material controls. Ferrite, on the other hand, has gained greater development potential due to its high cost-effectiveness. Permanent magnet-assisted reluctance motors are widely used and researched due to their reluctance torque advantage. However, when traditional permanent magnet-assisted reluctance motors use NdFeB or ferrite permanent magnets of fixed grades and materials, their magnetic energy product remains constant. This makes adjusting the air gap magnetic field difficult, and the cogging structure of the motor results in a large harmonic content in the air gap magnetic flux density and back EMF, leading to a large peak electromagnetic force and ultimately, significant torque pulsation and vibration noise. Summary of the Invention

[0003] Therefore, the present invention provides a rotor assembly that can overcome the shortcomings of permanent magnet assisted reluctance motors, which use neodymium iron boron or ferrite permanent magnets of fixed grade and material, resulting in constant magnetic energy product, difficulty in adjusting the air gap magnetic field, and large harmonic content of air gap magnetic flux density and back EMF due to the tooth and cogging structure of the motor, as well as large peak electromagnetic force of the motor, ultimately leading to large torque pulsation and vibration noise of the motor.

[0004] To address the aforementioned problems, the present invention provides a rotor assembly, comprising: a rotor core having adjacent first and second magnetic poles; a first permanent magnet slot group being constructed within the first magnetic pole; and a second permanent magnet slot group being constructed within the second magnetic pole; each of the first and second permanent magnet slot groups includes at least two permanent magnet slots; permanent magnets are assembled in each of the permanent magnet slots in the first and second magnetic poles; and each of the permanent magnet slots in the first and second magnetic poles extends along the rotor core. The permanent magnet slots are radially distributed sequentially, and each permanent magnet slot in the first magnetic pole is symmetrical about the d-axis with respect to the first magnetic pole. Each permanent magnet slot in the second magnetic pole is symmetrical about the d-axis with respect to the second magnetic pole. In the first magnetic pole, the permanent magnet slot located at the innermost radial side of the rotor core is the first permanent magnet slot, and in the second magnetic pole, the permanent magnet slot located at the innermost radial side of the rotor core is the second permanent magnet slot. The first permanent magnet slot and the second permanent magnet slot are adjacent to each other, and the shape of the end of the first permanent magnet slot is different from the shape of the end of the second permanent magnet slot.

[0005] In some embodiments, the first permanent magnet slot is a first arc-shaped slot protruding towards the central axis of the rotor core. Along the radial direction of the rotor core, the first permanent magnet slot has a first arc-shaped surface located radially outside the rotor core. The first permanent magnet slot also has two first inclined surfaces, which are respectively connected to two ends of the first permanent magnet slot, and both first inclined surfaces are also connected to the first arc-shaped surface. The cross-section of any rotor core is a reference plane, and the projection of the first inclined surface onto the reference plane is a first inclined line segment. The length of the second permanent magnet slot is N1; the second permanent magnet slot is a second arc-shaped slot protruding towards the central axis of the rotor core. Along the radial direction of the rotor core, the second permanent magnet slot has a second arc-shaped surface located on the radial outer side of the rotor core. The second permanent magnet slot also has two second inclined surfaces, which are respectively connected to the two ends of the second permanent magnet slot, and both second inclined surfaces are also connected to the second arc-shaped surface. The projection of the second inclined surface on the reference plane is a second inclined line segment, and the length of the second inclined line segment is N2, 1.0≤N2 / N1≤1.4.

[0006] In some embodiments, along the radial direction of the rotor core, the first permanent magnet slot further has a third arcuate surface located radially inside the rotor core, and the third arcuate surface is located inside the first arcuate surface. The first permanent magnet slot also has two first tangential surfaces, which are respectively connected to the two ends of the first permanent magnet slot, and both first tangential surfaces are also connected to the third arcuate surface. The midpoint of the first oblique line segment is point A, and the vertical distance between point A and the first tangential surface is M1. Along the radial direction of the rotor core, the second permanent magnet slot further has a fourth arcuate surface located radially inside the rotor core, and the fourth arcuate surface is located inside the second arcuate surface. The second permanent magnet slot also has two second tangential surfaces, which are respectively connected to the two ends of the second permanent magnet slot, and both second tangential surfaces are also connected to the fourth arcuate surface. The midpoint of the second oblique line segment is point B, and the vertical distance between point B and the second tangential surface is M2, where 1.1 ≤ M2 / M1 ≤ 1.5.

[0007] In some implementations, the adjacent first cut surface is parallel to the second cut surface.

[0008] In some embodiments, the first permanent magnet slot group includes a first permanent magnet slot and a third permanent magnet slot. Along the radial direction of the rotor core, the third permanent magnet slot is located outside the first permanent magnet slot. The d-axis of the first magnetic pole intersects the first permanent magnet slot, the third permanent magnet slot, and the outer wall of the rotor core at points C, D, and E, respectively. The distance between points D and E is S1, and the distance between points C and E is S2, where 1.5 ≤ S2 / S1 ≤ 2.3. And / or, the second permanent magnet slot group includes a second permanent magnet slot and a fourth permanent magnet slot. Along the radial direction of the rotor core, the fourth permanent magnet slot is located outside the second permanent magnet slot. The d-axis of the second magnetic pole intersects the second permanent magnet slot, the fourth permanent magnet slot, and the outer wall of the rotor core at points F, G, and H, respectively. The distance between points G and H is S3, and the distance between points F and H is S4, where 1.5 ≤ S4 / S3 ≤ 2.3.

[0009] In some embodiments, the d-axis of the first magnetic pole and the third permanent magnet slot intersect at point I. Along the radial direction of the rotor core, point I is inside point D, and the distance between point I and point C is L1. The d-axis of the second magnetic pole and the fourth permanent magnet slot intersect at point J. Along the radial direction of the rotor core, point J is inside point G, and the distance between point J and point F is L2, where 0.1mm ≤ L2 - L1 ≤ 0.4mm.

[0010] In some embodiments, a first magnetic isolation hole is further formed in the first magnetic pole, the first magnetic isolation hole being located between the first permanent magnet slot and the third permanent magnet slot, and the first magnetic isolation hole being close to the end of the first permanent magnet slot; and / or, a second magnetic isolation hole is further formed in the second magnetic pole, the second magnetic isolation hole being located between the second permanent magnet slot and the fourth permanent magnet slot, and the second magnetic isolation hole being close to the end of the second permanent magnet slot.

[0011] In some embodiments, the number of the first magnetic isolation holes is two, and the two first magnetic isolation holes are symmetrical about the d-axis with respect to the first magnetic pole; and / or, the number of the second magnetic isolation holes is two, and the two second magnetic isolation holes are symmetrical about the d-axis with respect to the second magnetic pole.

[0012] In some embodiments, the cross-section of the first magnetic isolation hole is a first triangle, the first triangle having a first side facing the first permanent magnet slot, the projection of the first tangent plane onto the reference plane being a first tangent line, and within the first magnetic pole, the extensions of the two first tangent lines intersect to form an included angle X1, the vertex of the included angle X1 being close to the central axis of the rotor core, and the extensions of the two first sides intersect to form an included angle Q1, the vertex of the included angle Q1 being close to the central axis of the rotor core, 0.6≤X1 / Q1≤0.9; and / or, the cross-section of the second magnetic isolation hole is a second triangle, the second triangle having a second side facing the second permanent magnet slot, the projection of the second tangent plane onto the reference plane being a second tangent line, and within the second magnetic pole, the extensions of the two second tangent lines intersect to form an included angle X2, the vertex of the included angle X2 being close to the central axis of the rotor core, and the extensions of the two second sides intersect to form an included angle Q2, the vertex of the included angle Q2 being close to the central axis of the rotor core, 0.6≤X2 / Q2≤1.2.

[0013] The present invention also provides an electric motor, including the rotor assembly described above.

[0014] The present invention provides a rotor assembly and a motor having the same. Because the shapes of the ends of the first permanent magnet slot and the second permanent magnet slot are different in two adjacent magnetic poles, this asymmetrical structure changes the magnetic reluctance distribution at various points in the motor's magnetic circuit, which can reduce the cogging effect of the motor, improve the magnetic flux direction, reduce the harmonic content, reduce the peak electromagnetic force of the motor, thereby reducing the torque pulsation and electromagnetic vibration noise of the motor. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the rotor assembly according to an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the rotor assembly according to an embodiment of the present invention;

[0017] Figure 3 for Figure 1 An enlarged schematic diagram of the rotor assembly at point K in an embodiment of the present invention;

[0018] Figure 4 for Figure 1 An enlarged schematic diagram of the rotor assembly at point K in an embodiment of the present invention;

[0019] Figure 5 This is a schematic diagram of a traditional rotor assembly.

[0020] Figure 6 This is a schematic diagram comparing the torque pulsation of a conventional motor and the motor of this embodiment.

[0021] Figure 7 This is a schematic diagram comparing the peak electromagnetic force density of a conventional motor and the motor of this embodiment.

[0022] Figure 8 This is a schematic diagram comparing the total noise levels of a compressor using a conventional electric motor and a compressor using the electric motor of this embodiment.

[0023] The reference numerals in the attached figures are as follows:

[0024] 1. Rotor core; 2. Permanent magnet; 3. First permanent magnet slot; 4. Second permanent magnet slot; 5. First inclined surface; 6. Second inclined surface; 7. First cross-section; 8. Second cross-section; 9. Third permanent magnet slot; 10. Fourth permanent magnet slot; 11. First magnetic isolation hole; 12. Second magnetic isolation hole. Detailed Implementation

[0025] See also Figures 1 to 8 As shown, according to an embodiment of the present invention, a rotor assembly is provided, comprising: a rotor core 1, the rotor core 1 having adjacent first magnetic poles and second magnetic poles, a first permanent magnet slot group being constructed within the first magnetic pole, and a second permanent magnet slot group being constructed within the second magnetic pole, each of the first and second permanent magnet slot groups including at least two permanent magnet slots, and a permanent magnet 2 being assembled in each permanent magnet slot in the first and second magnetic poles, the permanent magnet slots in the first and second magnetic poles being along the radial direction of the rotor core 1. The permanent magnet slots are distributed sequentially, and each permanent magnet slot in the first magnetic pole is symmetrical about the d-axis with respect to the first magnetic pole. Each permanent magnet slot in the second magnetic pole is symmetrical about the d-axis with respect to the second magnetic pole. In the first magnetic pole, the permanent magnet slot located at the innermost radial side of the rotor core 1 is the first permanent magnet slot 3, and in the second magnetic pole, the permanent magnet slot located at the innermost radial side of the rotor core 1 is the second permanent magnet slot 4. The first permanent magnet slot 3 and the second permanent magnet slot 4 are adjacent, and the shape of the end of the first permanent magnet slot 3 is different from the shape of the end of the second permanent magnet slot 4. In this technical solution, in the first magnetic pole, the first permanent magnet slot 3 surrounds the other permanent magnet slots, and in the second magnetic pole, the second permanent magnet slot 4 also surrounds the other permanent magnet slots. Therefore, in adjacent first and second magnetic poles, only the first permanent magnet slot 3 and the second permanent magnet slot 4 are adjacent. Taking a rotor with six magnetic poles as an example, three first magnetic poles and three second magnetic poles are alternately distributed along the circumference of the rotor core 1. Because the shapes of the ends of the first permanent magnet slot 3 and the second permanent magnet slot 4 are different in two adjacent magnetic poles, this asymmetrical structure changes the magnetic resistance distribution at various points in the motor's magnetic circuit, which can reduce the cogging effect of the motor, improve the magnetic flux direction, reduce the harmonic content, reduce the peak electromagnetic force of the motor, thereby reducing the torque pulsation and electromagnetic vibration noise of the motor.

[0026] See also Figure 1and Figure 4 As shown, the first permanent magnet slot 3 is a first arc-shaped slot protruding towards the central axis of the rotor core 1. Along the radial direction of the rotor core 1, the first permanent magnet slot 3 has a first arc-shaped surface located radially outside the rotor core 1. The first permanent magnet slot 3 also has two first inclined surfaces 5, which are respectively connected to the two ends of the first permanent magnet slot 3, and both first inclined surfaces 5 are also connected to the first arc-shaped surface. The cross-section of any rotor core 1 is a reference plane, and the projection of the first inclined surface 5 onto the reference plane is a first inclined line segment, the length of which is... N1; The second permanent magnet slot 4 is a second arc-shaped slot protruding towards the central axis of the rotor core 1. Along the radial direction of the rotor core 1, the second permanent magnet slot 4 has a second arc-shaped surface located radially outside the rotor core 1. The second permanent magnet slot 4 also has two second inclined surfaces 6, which are respectively connected to the two ends of the second permanent magnet slot 4, and both second inclined surfaces 6 are also connected to the second arc-shaped surface. The projection of the second inclined surface 6 onto the reference plane is a second inclined line segment, the length of which is N2, 1.0≤N2 / N1≤1.4. The first inclined surface 5 in the first permanent magnet slot 3 and the second inclined surface 6 in the second permanent magnet slot 4 are important factors that cause the shape of the ends of the first permanent magnet slot 3 and the ends of the second permanent magnet slot 4 to be inconsistent within adjacent first and second magnetic poles. Since permanent magnets need to be installed in both the first permanent magnet slot 3 and the second permanent magnet slot 4, due to the limitations of the permanent magnets, if the size of the first inclined surface 5 or the second inclined surface 6 is increased, the first inclined surface 5 or the second inclined surface 6 cannot expand radially inward towards the rotor core 1, but must expand radially outward towards the rotor core 1. This requires that the ends of the first permanent magnet slot 3 and the ends of the second permanent magnet slot 4 be as close as possible to the outer peripheral wall of the rotor core 1. In adjacent first and second magnetic poles, if the ratio of N2 to N1 is too large, the width of the magnetic isolation bridge formed between the end of the second permanent magnet slot 4 and the outer peripheral wall of the rotor will be too small, resulting in insufficient mechanical strength. If the ratio of N2 to N1 is too small, the magnetic isolation bridge formed between the end of the second permanent magnet slot 4 and the outer peripheral wall of the rotor will be too wide, resulting in poor magnetic isolation effect and serious magnetic leakage. A ratio of 1.0 ≤ N2 / N1 ≤ 1.4 is more suitable. Preferably, 1.0 ≤ N2 / N1 ≤ 1.25.

[0027] See also Figure 1 and Figure 3As shown, along the radial direction of the rotor core 1, the first permanent magnet slot 3 also has a third arc-shaped surface located radially inside the rotor core 1, and the third arc-shaped surface is located inside the first arc-shaped surface. The first permanent magnet slot 3 also has two first tangent surfaces 7, which are respectively connected to the two ends of the first permanent magnet slot 3, and both first tangent surfaces 7 are also connected to the third arc-shaped surface. The midpoint of the first oblique line segment is point A, and the vertical distance between point A and the first tangent surface 7 is M1; along the rotor core... In the radial direction of 1, the second permanent magnet slot 4 also has a fourth arc-shaped surface located radially inside the rotor core 1, and the fourth arc-shaped surface is located inside the second arc-shaped surface. The second permanent magnet slot 4 also has two second tangents 8, which are respectively connected to the two ends of the second permanent magnet slot 4, and both second tangents 8 are also connected to the fourth arc-shaped surface. The midpoint of the second oblique line segment is point B, and the vertical distance between point B and the second tangent 8 is M2, 1.1≤M2 / M1≤1.5. The first tangent 7 in the first permanent magnet slot 3 and the second tangent 8 in the second permanent magnet slot 4 are another important factor contributing to the inconsistency in the shapes of the ends of the first permanent magnet slot 3 and the ends of the second permanent magnet slot 4 within adjacent first and second magnetic poles. Within adjacent first and second magnetic poles, if the ratio of M2 to M1 is too large, the connection between the two poles will be too small, resulting in excessively high magnetic flux density and insufficient structural strength. Conversely, if the ratio is too small, the connection between the two poles will be too large, leading to poor magnetic isolation and excessive magnetic leakage. A ratio of 1.1 ≤ M2 / M1 ≤ 1.5 yields the best results. Preferably, 1.1 ≤ M2 / M1 ≤ 1.35. Within adjacent first and second magnetic poles, if the shape and dimensions of the ends of adjacent first permanent magnet slot 3 and second permanent magnet slot 4 satisfy 1.0 ≤ N2 / N1 ≤ 1.4, and also satisfy 1.1 ≤ M2 / M1 ≤ 1.5, this asymmetry is more conducive to the distribution of magnetic flux throughout the rotor circumference, improving the air gap magnetic field distribution, improving the magnetic flux direction, reducing the peak value of the 2np harmonic electromagnetic force, and reducing the electromagnetic vibration noise of the motor. Here, n is a positive integer, and p is the number of pole pairs of the motor.

[0028] Specifically, the adjacent first cut surface 7 and second cut surface 8 are parallel, which can effectively reduce the amplitude and torque pulsation of the 18th harmonic electromagnetic force. At the same time, when 1.1≤M2 / M1≤1.5 is satisfied, the distance S between two adjacent first cut surfaces 7 and second cut surfaces 8 is between 0.6mm and 1mm.

[0029] See also Figure 1As shown, the first permanent magnet slot group includes a first permanent magnet slot 3 and a third permanent magnet slot 9. Along the radial direction of the rotor core 1, the third permanent magnet slot 9 is located outside the first permanent magnet slot 3. The d-axis of the first magnetic pole intersects the outer walls of the first permanent magnet slot 3, the third permanent magnet slot 9, and the rotor core 1 at points C, D, and E, respectively. The distance between points D and E is S1, and the distance between points C and E is S2, where 1.5 ≤ S2 / S1 ≤ 2.3; and / Alternatively, the second permanent magnet slot group includes a second permanent magnet slot 4 and a fourth permanent magnet slot 10. Along the radial direction of the rotor core 1, the fourth permanent magnet slot 10 is located outside the second permanent magnet slot 4. The d-axis of the second magnetic pole intersects the outer walls of the second permanent magnet slot 4, the fourth permanent magnet slot 10, and the rotor core 1 at points F, G, and H, respectively. The distance between points G and H is S3, and the distance between points F and H is S4, where 1.5 ≤ S4 / S3 ≤ 2.3. When the ratio of S2 to S1 is between 1.5 and 2.3, and the ratio of S4 to S3 is between 1.5 and 2.3, torque pulsation can be effectively reduced.

[0030] In one specific implementation, the d-axis of the first magnetic pole and the third permanent magnet slot 9 intersect at point I. Along the radial direction of the rotor core 1, point I is inside point D, and the distance between point I and point C is L1. The d-axis of the second magnetic pole and the fourth permanent magnet slot 10 intersect at point J. Along the radial direction of the rotor core 1, point J is inside point G, and the distance between point J and point F is L2. 0.1mm ≤ L2 - L1 ≤ 0.4mm. When the value of L2 minus L1 is between 0.1mm and 0.4mm, the peak electromagnetic force of the motor can be further reduced, and the electromagnetic vibration noise of the motor can be further reduced.

[0031] See also Figure 2 As shown, a first magnetic isolation hole 11 is also constructed within the first magnetic pole, located between the first permanent magnet slot 3 and the third permanent magnet slot 9, and close to the end of the first permanent magnet slot 3; and / or, a second magnetic isolation hole 12 is also constructed within the second magnetic pole, located between the second permanent magnet slot 4 and the fourth permanent magnet slot 10, and close to the end of the second permanent magnet slot 4. The first magnetic isolation hole 11 and the second magnetic isolation hole 12 are filled with non-magnetic material or air, thereby making the air gap magnetic flux density waveform more sinusoidal, further reducing harmonics, reducing the electromagnetic force amplitude, reducing the 18th harmonic electromagnetic force, and reducing vibration noise.

[0032] Specifically, there are two first magnetic isolation holes 11, which are symmetrical about the d-axis with respect to the first magnetic pole; and / or, there are two second magnetic isolation holes 12, which are symmetrical about the d-axis with respect to the second magnetic pole. This improves the air gap magnetic field of the motor while ensuring rotor pole symmetry, further reducing motor torque pulsation and motor vibration.

[0033] See also Figure 2 As shown, the cross-section of the first magnetic isolation hole 11 is a first triangle, the first triangle has a first side facing the first permanent magnet slot 3, the projection of the first tangent 7 onto the reference plane is a first tangent, in the first magnetic pole, when the extensions of the two first tangents intersect, they form an included angle X1, the vertex of the included angle X1 is close to the central axis of the rotor core 1, when the extensions of the two first sides intersect, they form an included angle Q1, the vertex of the included angle Q1 is close to the central axis of the rotor core 1, 0.6≤X1 / Q1≤0.9; and / or, the cross-section of the second magnetic isolation hole 12 is a second triangle, the second triangle has a second side facing the second permanent magnet slot 4, the projection of the second tangent 8 onto the reference plane is a second tangent, in the second magnetic pole, when the extensions of the two second tangents intersect, they form an included angle X2, the vertex of the included angle X2 is close to the central axis of the rotor core 1, when the extensions of the two second sides intersect, they form an included angle Q2, the vertex of the included angle Q2 is close to the central axis of the rotor core 1, 0.6≤X2 / Q2≤1.2. The first side is the longest side of the first triangle, and the second side is the longest side of the second triangle. When the ratio of the included angle X1 to the included angle Q1 is between 0.6 and 0.9 and the ratio of the included angle X2 to the included angle Q2 is between 0.6 and 1.2, the magnetic field distribution can be improved, and the amplitude of the 18th harmonic electromagnetic force can be further reduced.

[0034] Figure 1 Because there are many parameters labeled, the first magnetic isolation hole 11 and the second magnetic isolation hole 12 are not shown. The first magnetic isolation hole 11 and the second magnetic isolation hole 12 are mainly reflected in... Figure 2 middle.

[0035] Figure 5 The image shows the rotor of a traditional permanent magnet assisted reluctance motor, where the permanent magnet slots in adjacent magnetic poles on the rotor have completely identical shapes.

[0036] Figure 6 The diagram shows a comparison of torque ripple between a conventional motor and a motor according to an embodiment of the present invention. As can be seen from the diagram, the torque ripple of the motor according to the present invention is significantly reduced compared to that of a conventional motor.

[0037] Figure 7 The figure shows a comparison of the peak electromagnetic force density of a conventional motor and a motor according to an embodiment of the present invention. As can be seen from the figure, the electromagnetic force of the motor of the present invention at 18 times the frequency is significantly lower than that of the conventional motor at 18 times the frequency.

[0038] Figure 8This is a schematic diagram comparing the total noise levels of a compressor using a conventional motor and a compressor using the motor of this invention. As can be seen from the diagram, the total noise level of the compressor using the motor of this invention is significantly lower than that of the compressor using a conventional motor.

[0039] The present invention also provides an electric motor, including the rotor assembly described above.

[0040] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0041] The above are merely preferred embodiments of the present invention and are 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 are merely preferred embodiments 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 rotor assembly, characterized in that, The rotor core (1) includes a rotor core (1) having adjacent first and second magnetic poles. A first permanent magnet slot group is constructed within the first magnetic pole, and a second permanent magnet slot group is constructed within the second magnetic pole. Both the first and second permanent magnet slot groups include at least two permanent magnet slots. Each permanent magnet slot in the first magnetic pole and each permanent magnet slot in the second magnetic pole is equipped with a permanent magnet (2). Each permanent magnet slot in the first magnetic pole and each permanent magnet slot in the second magnetic pole are sequentially distributed radially along the rotor core (1), and each permanent magnet slot in the first magnetic pole... The permanent magnet slots are symmetrical about the d-axis with respect to the first magnetic pole, and each permanent magnet slot in the second magnetic pole is symmetrical about the d-axis with respect to the second magnetic pole. In the first magnetic pole, the permanent magnet slot located at the innermost radial side of the rotor core (1) is the first permanent magnet slot (3), and in the second magnetic pole, the permanent magnet slot located at the innermost radial side of the rotor core (1) is the second permanent magnet slot (4). The first permanent magnet slot (3) and the second permanent magnet slot (4) are adjacent, and the shape of the end of the first permanent magnet slot (3) is different from the shape of the end of the second permanent magnet slot (4). The first permanent magnet slot (3) is a first arc-shaped slot protruding towards the central axis of the rotor core (1). Along the radial direction of the rotor core (1), the first permanent magnet slot (3) has a first arc-shaped surface located on the radial outer side of the rotor core (1). The first permanent magnet slot (3) also has two first inclined surfaces (5). The two first inclined surfaces (5) are respectively connected to the two ends of the first permanent magnet slot (3), and both first inclined surfaces (5) are also connected to the first arc-shaped surface. The cross-section of any rotor core (1) is a reference plane, and the projection of the first inclined surface (5) in the reference plane is a first inclined line segment. The length of the first inclined line segment is... N1; the second permanent magnet slot (4) is a second arc-shaped slot protruding towards the central axis of the rotor core (1). Along the radial direction of the rotor core (1), the second permanent magnet slot (4) has a second arc-shaped surface located on the radial outer side of the rotor core (1). The second permanent magnet slot (4) also has two second inclined surfaces (6). The two second inclined surfaces (6) are respectively connected to the two ends of the second permanent magnet slot (4), and the two second inclined surfaces (6) are also connected to the second arc-shaped surface. The projection of the second inclined surface (6) on the reference plane is a second inclined line segment. The length of the second inclined line segment is N2, 1.0≤N2 / N1≤1.

4.

2. The rotor assembly according to claim 1, characterized in that, Along the radial direction of the rotor core (1), the first permanent magnet slot (3) also has a third arc-shaped surface located radially inside the rotor core (1), and the third arc-shaped surface is located inside the first arc-shaped surface. The first permanent magnet slot (3) also has two first tangents (7), which are respectively connected to the two ends of the first permanent magnet slot (3), and both first tangents (7) are also connected to the third arc-shaped surface. The midpoint of the first oblique line segment is point A, and the vertical distance between point A and the first tangent (7) is M1. Along the rotor core (1) In the radial direction, the second permanent magnet slot (4) also has a fourth arc-shaped surface located on the radial inner side of the rotor core (1), and the fourth arc-shaped surface is located on the inner side of the second arc-shaped surface. The second permanent magnet slot (4) also has two second cut surfaces (8), which are respectively connected to the two ends of the second permanent magnet slot (4), and both second cut surfaces (8) are also connected to the fourth arc-shaped surface. The midpoint of the second oblique line segment is point B, and the vertical distance between point B and the second cut surface (8) is M2, 1.1≤M2 / M1≤1.

5.

3. The rotor assembly according to claim 2, characterized in that, The adjacent first cut surface (7) is parallel to the second cut surface (8).

4. The rotor assembly according to claim 2, characterized in that, The first permanent magnet slot group includes a first permanent magnet slot (3) and a third permanent magnet slot (9). Along the radial direction of the rotor core (1), the third permanent magnet slot (9) is located outside the first permanent magnet slot (3). The d-axis of the first magnetic pole intersects the outer walls of the first permanent magnet slot (3), the third permanent magnet slot (9), and the rotor core (1) at points C, D, and E, respectively. The distance between points D and E is S1, and the distance between points C and E is S2. 1.5 ≤ S2 / S1 ≤ 2.3; and / or The second permanent magnet slot group includes the second permanent magnet slot (4) and the fourth permanent magnet slot (10). Along the radial direction of the rotor core (1), the fourth permanent magnet slot (10) is located outside the second permanent magnet slot (4). The d-axis of the second magnetic pole intersects the outer walls of the second permanent magnet slot (4), the fourth permanent magnet slot (10), and the rotor core (1) at points F, G, and H, respectively. The distance between points G and H is S3, and the distance between points F and H is S4. 1.5≤S4 / S3≤2.

3.

5. The rotor assembly according to claim 4, characterized in that, The d-axis of the first magnetic pole and the third permanent magnet slot (9) intersect at point I. Along the radial direction of the rotor core (1), point I is inside point D, and the distance between point I and point C is L1. The d-axis of the second magnetic pole and the fourth permanent magnet slot (10) intersect at point J. Along the radial direction of the rotor core (1), point J is inside point G, and the distance between point J and point F is L2, 0.1mm≤L2-L1≤0.4mm.

6. The rotor assembly according to claim 4, characterized in that, The first magnetic pole is further provided with a first magnetic isolation hole (11), which is located between the first permanent magnet groove (3) and the third permanent magnet groove (9), and the first magnetic isolation hole (11) is close to the end of the first permanent magnet groove (3); and / or, the second magnetic pole is further provided with a second magnetic isolation hole (12), which is located between the second permanent magnet groove (4) and the fourth permanent magnet groove (10), and the second magnetic isolation hole (12) is close to the end of the second permanent magnet groove (4).

7. The rotor assembly according to claim 6, characterized in that, The number of the first magnetic isolation holes (11) is two, and the two first magnetic isolation holes (11) are symmetrical about the d-axis with respect to the first magnetic pole; and / or, the number of the second magnetic isolation holes (12) is two, and the two second magnetic isolation holes (12) are symmetrical about the d-axis with respect to the second magnetic pole.

8. The rotor assembly according to claim 6, characterized in that, The cross-section of the first magnetic isolation hole (11) is a first triangle, the first triangle has a first side facing the first permanent magnet slot (3), the projection of the first tangent (7) in the reference plane is a first tangent line, in the first magnetic pole, when the extensions of the two first tangent lines intersect, they form an included angle X1, the vertex of the included angle X1 is close to the central axis of the rotor core (1), when the extensions of the two first sides intersect, they form an included angle Q1, the vertex of the included angle Q1 is close to the central axis of the rotor core (1), 0.6≤X1 / Q1≤0.9; and / Alternatively, the cross-section of the second magnetic isolation hole (12) is a second triangle, the second triangle has a second side, the second side faces the second permanent magnet slot (4), the projection of the second tangent (8) in the reference plane is a second tangent, in the second magnetic pole, when the extensions of the two second tangents intersect, they form an included angle X2, the vertex of the included angle X2 is close to the central axis of the rotor core (1), when the extensions of the two second sides intersect, they form an included angle Q2, the vertex of the included angle Q2 is close to the central axis of the rotor core (1), 0.6≤X2 / Q2≤1.

2.

9. An electric motor, characterized in that, The rotor assembly includes any one of claims 1 to 8.

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