Rotor Assemblies, Motors and Compressors

Abstract

The present invention provides a rotor assembly, a motor and a compressor. The rotor assembly comprises a rotor core (1), the rotor core (1) comprises a plurality of magnetic poles, each magnetic pole comprises a first permanent magnet slot (2) and a second permanent magnet slot (3) arranged radially from the inside to the outside, the first permanent magnet slot (2) comprises a first arc segment (4) and a first straight segment (5), the second permanent magnet slot (3) comprises a second arc segment (6) and a second straight segment (7), two first straight segments (5) are connected to the two ends of the first arc segment (4), two second straight segments (7) are connected to the two ends of the second arc segment (6), the width between the first straight segment (5) and the second straight segment (7) remains constant, and the spacing between the first arc segment (4) and the second arc segment (6) gradually increases along the direction from the center line of the magnetic pole to both sides. According to the rotor assembly of the present invention, the quadrature axis inductance can be improved, and the torque density and power density of the motor can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of compressors, and in particular relates to a rotor assembly, a motor and a compressor. Background Art

[0002] In the air-conditioning industry, the matching of compressors and motors requires that the motors have high torque density and low noise, that is, the motors need to have the largest possible torque and the lowest possible harmonic magnetic field.

[0003] Patent No. 201420291774.X discloses a double-layer rotor structure with segmented rectangular rare earth permanent magnets in the slots. Although it can increase the reluctance torque content, the rectangular structure and the small cross-axis magnetic path width result in a small magnetic path area, low cross-axis inductance, and the motor output torque is still limited. At the same time, the ends of the permanent magnets and magnetic steel slots have serious magnetic leakage, local saturation, high motor harmonic content, and high motor noise. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a rotor assembly, a motor and a compressor, which can increase the cross-axis inductance and significantly improve the torque density and power density of the motor.

[0005] In order to solve the above problems, the present invention provides a rotor assembly, including a rotor core, the rotor core including a plurality of magnetic poles, each magnetic pole including a first permanent magnet slot and a second permanent magnet slot arranged in sequence from the inside to the outside in a radial direction, the first permanent magnet slot including a first arc segment and a first straight line segment, the second permanent magnet slot including a second arc segment and a second straight line segment, the two first straight line segments are connected at both ends of the first arc segment, the two second straight line segments are connected at both ends of the second arc segment, the width between the first straight line segment and the second straight line segment remains constant, and the spacing between the first arc segment and the second arc segment gradually increases along the direction from the center line of the magnetic pole to both sides.

[0006] Preferably, the centers of the radially outer arc edges of the first permanent magnet slot and the second permanent magnet slot are both located on the magnetic pole center line.

[0007] Preferably, the radial inner arc edge and the radial outer arc edge of the first permanent magnet slot are both located on the magnetic pole center line.

[0008] Preferably, the second arc segment includes a first radial inner arc edge and a second radial inner arc edge, the first radial inner arc edge intersects with the second radial inner arc edge on the magnetic pole center line, the center of the first radial inner arc edge is located on the side of the second radial inner arc edge of the magnetic pole center line, and the center of the second radial inner arc edge is located on the side of the first radial inner arc edge of the magnetic pole center line.

[0009] Preferably, the width of the first arc segment decreases along the direction from the center line of the magnetic pole to both sides; and / or the width of the second arc segment decreases along the direction from the center line of the magnetic pole to both sides.

[0010] Preferably, the width of the first straight line segment is greater than or equal to the width of the second straight line segment.

[0011] Preferably, the first straight line segment and the second straight line segment located on the same side of the magnetic pole center line are parallel to each other.

[0012] Preferably, a first permanent magnet is arranged in the first permanent magnet slot, and the radial inner side and the radial outer side of the first permanent magnet match the first permanent magnet slot; and / or, a second permanent magnet is arranged in the second permanent magnet slot, and the radial inner side and the radial outer side of the second permanent magnet match the second permanent magnet slot.

[0013] Preferably, the end of the first permanent magnet slot has a first flat edge and a first cut edge, the end of the first permanent magnet has a first protrusion, and the first protrusion is arranged corresponding to the first flat edge and the first cut edge; and / or, the end of the second permanent magnet slot has a second flat edge and a second cut edge, the end of the second permanent magnet has a second protrusion, and the second protrusion is arranged corresponding to the second flat edge and the second cut edge.

[0014] Preferably, the first protrusion has a first side opposite to the first cut edge, and the first side is parallel to the first cut edge; and / or the second protrusion has a second side opposite to the second cut edge, and the intervals between the second side and the second cut edge are unequal.

[0015] Preferably, the projection length of the first flat edge on the width cross-section of the first straight line segment on its side is b1, and the projection length of the first cut edge on the width cross-section of the first straight line segment on its side is b2, wherein b1≤b2≤2.38b1; and / or, the projection length of the second flat edge on the width cross-section of the second straight line segment on its side is b1, and the projection length of the second cut edge on the width cross-section of the second straight line segment on its side is b2, wherein b1≤b2≤2.38b1.

[0016] Preferably, the relationship between the first flat edge and the first cut edge satisfies b2=2.38b1; and / or the relationship between the second flat edge and the second cut edge satisfies b2=b1.

[0017] Preferably, the angle between the side of the first protrusion opposite to the first flat edge and the side opposite to the first cut edge is de, 100deg≤de≤130deg; and / or the angle between the side of the second protrusion opposite to the second flat edge and the side opposite to the second cut edge is de, 100deg≤de≤130deg.

[0018] Preferably, the cross-axis magnetic circuit between the first permanent magnet slot and the second permanent magnet slot satisfies:

[0019] bw 2 =ec

[0020] Wherein bw is the distance between the first straight line segment and the second straight line segment, e is the distance between the inflection point of the radial outer arc edge of the first permanent magnet slot and the inflection point of the radial inner arc edge of the second permanent magnet slot located on the same side, and c is the distance between the radial outer arc edge of the first permanent magnet slot and the radial inner arc edge of the second permanent magnet slot on the permanent magnet center line.

[0021] Preferably, it is characterized in that c≤e≤1.23c.

[0022] Preferably, f≤d≤2c, where f is the maximum width of the first permanent magnet slot on the magnetic pole centerline, d is the maximum width of the second permanent magnet slot on the magnetic pole centerline, and c is the distance between the radial outer arc edge of the first permanent magnet slot and the radial inner arc edge of the second permanent magnet slot on the permanent magnet centerline.

[0023] Preferably, a first permanent magnet is arranged in the first permanent magnet slot, and the radial magnetization point of the first permanent magnet is the center of the radial outer arc edge of the first permanent magnet; and / or, a second permanent magnet is arranged in the second permanent magnet slot, and the radial magnetization point of the second permanent magnet is the intersection of the line connecting the centers of the two radial inner arc edges of the second permanent magnet and the center line of the magnetic pole.

[0024] Preferably, the minimum distance between the first permanent magnet slot and the central axis of the rotor core is a, the length of the first straight line segment is b, 0.38﹤(a+b) / r﹤0.63, where r is the radius of the rotor core.

[0025] Preferably, a width change rate of the second permanent magnet slot from the magnetic pole center line to both sides is greater than a width change rate of the first permanent magnet slot from the magnetic pole center line to both sides.

[0026] Preferably, a circulation hole is also provided on the rotor core, and the circulation hole is arranged on the radial inner side of the first permanent magnet slot. The circulation hole is symmetrical about the magnetic pole center line. The circulation hole includes circular portions at both ends and a bridge portion connected between the circular portions at both ends. The width of the bridge portion gradually changes along the direction from the magnetic pole center line to both sides.

[0027] Preferably, the side line of the bridge portion is in an arc shape, and the width of the bridge portion increases gradually along the direction from the center line of the magnetic pole to both sides.

[0028] Preferably, S1 / (S2+S3)≤0.26, wherein S1 is the area of ​​the bridge portion, S2 is the area of ​​the circular portion at one end, and S3 is the area of ​​the circular portion at the other end.

[0029] Preferably, the inflection point of the first permanent magnet slot and the inflection point of the second permanent magnet slot located on the same side of the magnetic pole centerline are located on the same straight line, and the straight line passes through the center of the radial inner arc edge of the first arc segment of the first permanent magnet slot.

[0030] According to another aspect of the present invention, a motor is provided, including a rotor assembly, wherein the rotor assembly is the above-mentioned rotor assembly.

[0031] According to yet another aspect of the present invention, a compressor is provided, comprising a rotor assembly, wherein the rotor assembly is the above-mentioned rotor assembly.

[0032] The rotor assembly provided by the present invention comprises a rotor core, the rotor core comprises a plurality of magnetic poles, each magnetic pole comprises a first permanent magnet slot and a second permanent magnet slot arranged in sequence from the inside to the outside in the radial direction, the first permanent magnet slot comprises a first arc segment and a first straight line segment, the second permanent magnet slot comprises a second arc segment and a second straight line segment, the two first straight line segments are connected at both ends of the first arc segment, the two second straight line segments are connected at both ends of the second arc segment, the width between the first straight line segment and the second straight line segment remains constant, and the spacing between the first arc segment and the second arc segment gradually increases along the direction from the center line of the magnetic pole to both sides. Since the width between the first straight line segment and the second straight line segment remains constant, and the spacing between the first arc segment and the second arc segment gradually increases along the direction from the center line of the magnetic pole to both sides, the structure of the rotor assembly can be improved, the quadrature axis inductance of the rotor assembly can be increased, and the torque density and power density of the motor can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of a rotor assembly according to an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the size structure of a rotor assembly according to an embodiment of the present invention;

[0035] Figure 3 It is an enlarged structural schematic diagram of the matching position of the permanent magnet and the permanent magnet slot of the rotor assembly of an embodiment of the present invention;

[0036] Figure 4 is an enlarged structural schematic diagram of a flow hole of a rotor assembly according to an embodiment of the present invention;

[0037] Figure 5 A comparison diagram of the back electromotive force of the rotor assembly of the prior art and the embodiment of the present invention;

[0038] Figure 6 A comparison diagram of the air gap magnetic field harmonic content of the rotor assembly of the prior art and the embodiment of the present invention;

[0039] Figure 7 It is a comparison diagram of the torque waveforms of the rotor assembly under rated current between the prior art and the embodiment of the present invention.

[0040] The reference numerals are:

[0041] 1. Rotor core; 2. First permanent magnet slot; 3. Second permanent magnet slot; 4. First circular arc segment; 5. First straight line segment; 6. Second circular arc segment; 7. Second straight line segment; 8. First radial inner arc edge; 9. Second radial inner arc edge; 10. First permanent magnet; 11. Second permanent magnet; 12. First flat edge; 13. First cut edge; 14. Second flat edge; 15. Second cut edge; 16. First protrusion; 17. Second protrusion; 18. Flow hole; 19. Round part; 20. Bridge part. DETAILED DESCRIPTION

[0042] In the various figures of this embodiment, 01-05 are the centers of the corresponding permanent magnet arc edges, 06 is the radial magnetization point of the permanent magnet, and 07-010 are the inflection points of the radial inner arc edge, the radial outer arc edge and the side of the straight line segment.

[0043] In order to more conveniently and clearly express the technical solution of the present application, the following embodiments in the present application are all described by taking the structure of the rotor assembly in a cross section perpendicular to the central axis of the rotor core as an example.

[0044] See also Figures 1 to 7 As shown, according to an embodiment of the present invention, the rotor assembly includes a rotor core 1, the rotor core 1 includes a plurality of magnetic poles, each magnetic pole includes a first permanent magnet slot 2 and a second permanent magnet slot 3 arranged radially from the inside to the outside, the first permanent magnet slot 2 includes a first arc segment 4 and a first straight line segment 5, the second permanent magnet slot 3 includes a second arc segment 6 and a second straight line segment 7, the two first straight line segments 5 are connected at both ends of the first arc segment 4, the two second straight line segments 7 are connected at both ends of the second arc segment 6, the width between the first straight line segment 5 and the second straight line segment 7 remains constant, and the spacing between the first arc segment 4 and the second arc segment 6 gradually increases along the direction from the center line of the magnetic pole to both sides.

[0045] Since the permanent magnet slot includes arc segments and straight segments, and the width between the first straight segment 7 and the second straight segment 8 remains constant, the spacing between the first arc segment 4 and the second arc segment 6 gradually increases from the center line of the magnetic pole to both sides. Therefore, the structure of the rotor assembly can be improved, the cross-axis inductance of the rotor assembly is increased, the torque generated per unit current is increased, and the torque density and power density of the motor are greatly improved.

[0046] Preferably, the permanent magnet slots of the rotor assembly in this embodiment are of a double-layer structure, which can obtain the maximum output torque per unit cost and improve the energy efficiency ratio of the electronic assembly.

[0047] The centers of the radial outer arc edges of the first permanent magnet slot 2 and the second permanent magnet slot 3 are both located on the magnetic pole centerline, and the diameter of the radial outer arc edge of the first permanent magnet slot 2 is greater than the diameter of the radial outer arc edge of the second permanent magnet slot 3, which can form a cross-axis magnetic circuit width that gradually increases from the magnetic pole centerline to both sides, thereby increasing the cross-axis inductance of the rotor assembly, increasing the torque generated by unit current, and effectively improving the torque density and power density of the motor. Since the centers of the radial outer arc edges of the first permanent magnet slot 2 and the second permanent magnet slot 3 are both located on the magnetic pole centerline, the radial outer arc edges of the first permanent magnet slot 2 and the second permanent magnet slot 3 can be made symmetrical about the magnetic pole centerline, thereby forming a balanced magnetic circuit structure on both sides of the magnetic pole centerline, and improving the stability of the magnetic circuit.

[0048] Preferably, the width of the first arc segment 4 decreases along the direction from the magnetic pole centerline to both sides; and / or, the width of the second arc segment 6 decreases along the direction from the magnetic pole centerline to both sides. When both conditions are met at the same time, the width of the cross-axis magnetic path that increases from the magnetic pole centerline to both sides can be formed between the first arc segment 4 and the second arc segment 6 by decreasing the width from the magnetic pole centerline to both sides, thereby more effectively increasing the cross-axis inductance of the rotor assembly and increasing the torque generated by the unit current.

[0049] Preferably, the radial inner arc edge and the radial outer arc edge of the first permanent magnet slot 2 are both located on the magnetic pole center line, so that the width of the middle part of the first arc segment 4 of the first permanent magnet slot 2 is the largest at the magnetic pole center line and gradually narrows toward both sides, thereby making the distance between the first arc segment 4 and the second arc segment 6 the smallest at the magnetic pole center line and gradually widens toward both sides, thereby increasing the cross-axis magnetic circuit width between the first permanent magnet slot 2 and the second permanent magnet slot 3 and increasing the cross-axis inductance.

[0050] Preferably, the second arc segment 6 includes a first radial inner arc edge 8 and a second radial inner arc edge 9, the first radial inner arc edge 8 and the second radial inner arc edge 9 intersect on the magnetic pole center line, the center of the first radial inner arc edge 8 is located on the side of the second radial inner arc edge 9 of the magnetic pole center line, and the center of the second radial inner arc edge 9 is located on the side of the first radial inner arc edge 8 of the magnetic pole center line. Since the radial inner arc edge of the second arc segment 6 is divided into two parts, and the radial inner arc edges of the two parts are inclined in the direction away from the radial outer arc edge of the first arc segment 4, the distance between the radial inner arc edge of the second arc segment 6 and the radial outer arc edge of the first arc segment 4 can be further increased, and the cross-axis magnetic circuit width can be effectively increased. The second arc segment 6 in this embodiment adopts an unconventional design, and the radial inner arc edge is segmented, which can not only obtain a circular arc structure that meets the requirements, but also overcome the problem that the permanent magnet slot in the prior art is limited by the arc structure and cannot significantly increase the cross-axis magnetic circuit width, so it can significantly increase the torque density and power density of the motor and improve the working performance of the motor.

[0051] The width of the first straight line segment 5 is greater than or equal to the width of the second straight line segment 7. The first straight line segment 5 and the second straight line segment 7 located on the same side of the magnetic pole centerline are parallel to each other. Generally speaking, the permanent magnets in the first permanent magnet slot 2 are more susceptible to demagnetization than the permanent magnets in the second permanent magnet slot 3. Therefore, designing the width of the first straight line segment 5 to be greater than or equal to the width of the second straight line segment 7 can effectively increase the difficulty of demagnetization of the first straight line segment 5, so that the difficulty of demagnetization of the first straight line segment 5 can be kept consistent with the difficulty of demagnetization of the second straight line segment 7 as much as possible, thereby improving the working performance of the motor.

[0052] A first permanent magnet 10 is arranged in the first permanent magnet slot 2. The radial inner side and the radial outer side of the first permanent magnet 10 match the first permanent magnet slot 2, which can ensure a good fit between the first permanent magnet 10 and the first permanent magnet slot 2, thereby improving the stability and reliability of the installation structure of the first permanent magnet 10 in the first permanent magnet slot 2, and further improving the stability and reliability of the working performance of the motor.

[0053] A second permanent magnet 11 is arranged in the second permanent magnet slot 3. The radial inner side and the radial outer side of the second permanent magnet 11 match the second permanent magnet slot 3, which can ensure a good fit between the second permanent magnet 11 and the second permanent magnet slot 3, thereby improving the stability and reliability of the installation structure of the second permanent magnet 11 in the second permanent magnet slot 3, and further improving the stability and reliability of the working performance of the motor.

[0054] The end of the first permanent magnet slot 2 has a first flat edge 12 and a first cut edge 13, the end of the first permanent magnet 10 has a first protrusion 16, and the first protrusion 16 is arranged corresponding to the first flat edge 12 and the first cut edge 13; and / or, the end of the second permanent magnet slot 3 has a second flat edge 14 and a second cut edge 15, the end of the second permanent magnet 11 has a second protrusion 17, and the second protrusion 17 is arranged corresponding to the second flat edge 14 and the second cut edge 15.

[0055] The edge shape of the first convex edge 16 is different from the edge shape of the end of the first permanent magnet slot 2, and a certain distance is reserved between the edge of the first convex edge 16 and the edge of the end of the first permanent magnet slot 2. The edge shape of the second convex edge 17 is different from the edge shape of the end of the second permanent magnet slot 3, and a certain distance is reserved between the edge of the second convex edge 17 and the edge of the end of the second permanent magnet slot 3.

[0056] Preferably, the first protrusion 16 has a first side edge opposite to the first cutting edge 13 , and the first side edge is parallel to the first cutting edge 13 .

[0057] The second protrusion 17 has a second side edge opposite to the second cutting edge 15 , and the distances between the second side edge and the second cutting edge 15 are unequal.

[0058] Preferably, the projected length of the first flat edge 12 on the width direction cross section of the first straight line segment 5 on its side is b1, and the projected length of the first trimmed edge 13 on the width direction cross section of the first straight line segment 5 on its side is b2, wherein b1≤b2≤2.38b1. The first flat edge 12 here extends along the width direction of the first permanent magnet slot 2, and there is a certain angle between the first trimmed edge 13 and the width direction of the first permanent magnet slot 2. b1 is the length of the first flat edge 12, b2 is the component of the first trimmed edge 13 in the width direction of the first permanent magnet slot 2, and the sum of b1 and b2 is the width of the first straight line segment 5 of the first permanent magnet slot 2. By limiting b1 and b2, the sinusoidality of the air gap magnetic density waveform can be effectively improved, so that the harmonic content is significantly reduced.

[0059] The projection length of the second flat edge 14 on the width direction cross section of the second straight line segment 7 on its side is b1, and the projection length of the second cut edge 15 on the width direction cross section of the second straight line segment 7 on its side is b2, where b1≤b2≤2.38b1. Here, b1 and b2 are used to define the structure of the sideline of the second permanent magnet slot 3, and their role is the same as that of the sideline structure of the first permanent magnet slot 2, which will not be described in detail here.

[0060] Preferably, the relationship between the first flat edge 12 and the first cut edge 13 satisfies b2=2.38b1; and / or, the relationship between the second flat edge 14 and the second cut edge 15 satisfies b2=b1, which can significantly improve the harmonic content of the rotor assembly during operation, so that the air gap magnetic flux density of the rotor assembly has a high fundamental wave content, a low harmonic content, and good sinusoidality, and the 11th harmonic content of the magnetic field is greatly reduced, the electromagnetic force wave is effectively reduced, the electromagnetic noise caused by the 11th harmonic magnetic field in the air gap is reduced, and the cost of the motor is reduced.

[0061] Preferably, the angle between the side of the first protrusion 16 opposite to the first flat edge 12 and the side opposite to the first cut edge 13 is de, 100deg≤de≤130deg; and / or the angle between the side of the second protrusion 17 opposite to the second flat edge 14 and the side opposite to the second cut edge 15 is de,

[0062] 100deg≤de≤130deg.

[0063] The cross-axis magnetic circuit between the first permanent magnet slot 2 and the second permanent magnet slot 3 satisfies:

[0064] bw 2 =ec

[0065] Wherein bw is the distance between the first straight line segment 5 and the second straight line segment 7, e is the distance between the inflection point of the radial outer arc edge of the first permanent magnet slot 2 and the inflection point of the radial inner arc edge of the second permanent magnet slot 3 located on the same side, and c is the distance between the radial outer arc edge of the first permanent magnet slot 2 and the radial inner arc edge of the second permanent magnet slot 3 on the permanent magnet center line. By limiting the cross-axis magnetic circuit between the first permanent magnet slot 2 and the second permanent magnet slot 3, a higher reluctance torque content and a more sinusoidal back electromotive force waveform can be formed, thereby improving the working performance of the motor.

[0066] Preferably, c≤e≤1.23c, which can ensure that the harmonic content of the magnetic field caused by the cross-axis magnetic circuit is greatly suppressed, especially the 11th harmonic content is significantly reduced.

[0067] Preferably, f≤d≤2c, where f is the maximum width of the first permanent magnet slot 2 on the magnetic pole centerline, d is the maximum width of the second permanent magnet slot 3 on the magnetic pole centerline, and c is the distance between the radial outer arc edge of the first permanent magnet slot 2 and the radial inner arc edge of the second permanent magnet slot 3 on the permanent magnet centerline. If the maximum width d of the second permanent magnet slot 3 at the magnetic pole centerline is too small, the demagnetization ability decays too quickly, and the back electromotive force has a large amount of harmonic content. If it is too large, the reluctance torque cannot be fully utilized. When f≤d≤2c, a better balance can be achieved, the working performance of the motor can be improved, and the working noise of the motor can be reduced.

[0068] A first permanent magnet 10 is arranged in the first permanent magnet slot 2, and the radial magnetization point of the first permanent magnet 10 is the center of the radial outer arc edge of the first permanent magnet 10; and / or, a second permanent magnet 11 is arranged in the second permanent magnet slot 3, and the radial magnetization point of the second permanent magnet 11 is the intersection of the line connecting the centers of the two radial inner arc edges of the second permanent magnet 11 and the center line of the magnetic pole, so as to obtain a better magnetic concentration effect.

[0069] Preferably, the permanent magnet is a ferrite permanent magnet with weak magnetism.

[0070] Each layer of the permanent magnets mentioned above can be a whole or can be formed by splicing together sections.

[0071] The minimum distance between the first permanent magnet slot 2 and the central axis of the rotor core 1 is a, the length of the first straight line segment 5 is b, 0.38﹤(a+b) / r﹤0.63, where r is the radius of the rotor core 1, thereby increasing the content of the reluctance torque and saving costs.

[0072] Preferably, the rate of change of the width of the second permanent magnet slot 3 from thick to thin from the magnetic pole center line to both sides is greater than the rate of change of the width of the first permanent magnet slot 2 from thick to thin from the magnetic pole center line to both sides, which can increase the width contraction amplitude of the second permanent magnet slot 3 from the magnetic pole center line to both sides, thereby further increasing the distance between the second permanent magnet slot 3 and the first permanent magnet slot 2, and increasing the width of the cross-axis magnetic circuit.

[0073] Preferably, the inflection point of the first permanent magnet slot 2 and the inflection point of the second permanent magnet slot 3 located on the same side of the magnetic pole centerline are located on the same straight line, and the straight line passes through the center of the radial inner arc edge of the first arc segment 4 of the first permanent magnet slot 2. The inflection point of the first permanent magnet slot 2 refers to the intersection of the radial inner arc edge of the first arc segment 4 and the radial inner side edge of the first straight line segment 5 and the intersection of the radial outer arc edge of the first arc segment 4 and the radial outer side edge of the first straight line segment 5. The inflection point of the second permanent magnet slot 3 refers to the intersection of the radial inner arc edge of the second arc segment 6 and the radial inner side edge of the second straight line segment 7 and the intersection of the radial outer arc edge of the second arc segment 6 and the radial outer side edge of the second straight line segment 7. These intersection points are collinear, and the straight line passes through the center of the radial inner arc edge of the first permanent magnet slot 2, which can weaken the magnetic flux harmonic content caused by the bending of the magnetic field lines on the edge line of the double-layer magnetic steel slot.

[0074] A flow hole 18 is also provided on the rotor core 1. The flow hole 18 is provided on the radial inner circumferential side of the first permanent magnet slot 2. The flow hole 18 is symmetrical about the magnetic pole center line. The flow hole 18 includes circular portions 19 at both ends and a bridge portion 20 connected between the circular portions 19 at both ends. The width of the bridge portion 20 gradually changes along the direction from the magnetic pole center line to both sides.

[0075] Preferably, the side line of the bridge portion 20 is in an arc shape, and the width of the bridge portion 20 increases gradually from the center line of the magnetic pole to both sides, and the width of the bridge portion has a minimum value at the center line of the magnetic pole.

[0076] Preferably, S1 / (S2+S3)≤0.26, where S1 is the bridge area, S2 is the circular area at one end, and S3 is the circular area at the other end. This can not only ensure that the rotor assembly meets a certain structural strength, but also increase the oil return volume of high-pressure gas circulation.

[0077] See also Figure 5 As shown, it is a back electromotive force comparison diagram, the horizontal axis is the simulation time, and the vertical axis is the amplitude. Among them, the dotted line represents the back electromotive force waveform of the prior art solution, and the effective value in one cycle is 42.8V; the solid line represents the back electromotive force waveform of the patent solution, and the effective value in one cycle is 45.4V. Overall, the permanent magnet flux is increased by 6%.

[0078] See also Figure 6 As shown, it is a comparison chart of the harmonic content of the air gap magnetic field, the horizontal axis is the harmonic number, and the vertical axis is the harmonic amplitude of the magnetic field. Among them, the white is the harmonic of the existing technology solution; the black is the harmonic of the patent solution. The fundamental amplitude of the patent technology is increased by 7.3%, and the 11th harmonic is reduced by 25.5%, and the improvement effect is obvious.

[0079] See also Figure 7The figure shows the torque waveform comparison under rated current, with the horizontal axis representing the simulation time and the vertical axis representing the torque amplitude. The dotted line represents the prior art, with an average torque of 8N.m and a pulsation of 21.98%; the solid line represents the patented technology, with an average torque of 8.65Nm and a pulsation of 22.91%. The average torque of the patented technology has been greatly improved, increasing by about 8.12%. Figure 5 It can be seen that the reluctance torque of the rotor structure of this patented technology is increased by about 2%.

[0080] By adopting the rotor magnetic circuit structure, magnetic steel shape, magnetizing method and the end matching method of the permanent magnet and the magnetic steel slot of the present invention, the cross-axis inductance is improved, the air gap magnetic flux density is improved, the torque generated by the unit current is increased, and the electromagnetic noise caused by the 11th harmonic magnetic field in the air gap is effectively reduced, thereby reducing the cost of the motor.

[0081] After adopting the above scheme of the present application, compared with the rotor assembly of the prior art, the torque density is increased by 6.8%, the back electromotive force fundamental content is increased by 6.1%, the 11th harmonic is reduced by 25.5%, the area is reduced by 10.5%, and the cost is reduced by 4.8%.

[0082] According to an embodiment of the present invention, the motor includes a rotor assembly, which is the above-mentioned rotor assembly.

[0083] According to an embodiment of the present invention, a compressor includes a rotor assembly, which is the rotor assembly described above.

[0084] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0085] The above are only 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 shall be included in the protection scope of the present invention. The above are only preferred embodiments 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, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A rotor assembly, characterized in that: The invention comprises a rotor core (1), wherein the rotor core (1) comprises a plurality of magnetic poles, each magnetic pole comprises a first permanent magnet slot (2) and a second permanent magnet slot (3) which are arranged in sequence from the inside to the outside in a radial direction, the first permanent magnet slot (2) comprises a first arc segment (4) and a first straight segment (5), the second permanent magnet slot (3) comprises a second arc segment (6) and a second straight segment (7), two first straight segments (5) are connected to the two ends of the first arc segment (4), and two second straight segments (7) are connected to the two ends of the second arc segment (6), the width between the first straight segment (5) and the second straight segment (7) remains constant, and the spacing between the first arc segment (4) and the second arc segment (6) gradually increases along the direction from the center line of the magnetic pole to both sides.

2. The rotor assembly according to claim 1, characterized in that The centers of the radial outer arc edges of the first permanent magnet slot (2) and the second permanent magnet slot (3) are both located on the magnetic pole center line.

3. The rotor assembly according to claim 2, characterized in that: The radial inner arc edge and the radial outer arc edge of the first permanent magnet slot (2) are both located on the magnetic pole center line.

4. The rotor assembly according to claim 3, characterized in that: The second circular arc segment (6) comprises a first radial inner arc edge (8) and a second radial inner arc edge (9), wherein the first radial inner arc edge (8) and the second radial inner arc edge (9) intersect on the magnetic pole center line, the center of the first radial inner arc edge (8) is located on the side of the magnetic pole center line where the second radial inner arc edge (9) is located, and the center of the second radial inner arc edge (9) is located on the side of the magnetic pole center line where the first radial inner arc edge (8) is located.

5. The rotor assembly according to claim 1, characterized in that: The width of the first arc segment (4) decreases gradually along the direction from the center line of the magnetic pole to both sides; and / or the width of the second arc segment (6) decreases gradually along the direction from the center line of the magnetic pole to both sides.

6. The rotor assembly according to claim 1, characterized in that The width of the first straight line segment (5) is greater than or equal to the width of the second straight line segment (7).

7. The rotor assembly according to claim 1, characterized in that A first permanent magnet (10) is arranged in the first permanent magnet slot (2), and a radial inner side edge and a radial outer side edge of the first permanent magnet (10) match the first permanent magnet slot (2); and / or a second permanent magnet (11) is arranged in the second permanent magnet slot (3), and a radial inner side edge and a radial outer side edge of the second permanent magnet (11) match the second permanent magnet slot (3).

8. The rotor assembly according to claim 7, characterized in that The end of the first permanent magnet slot (2) has a first flat edge (12) and a first cut edge (13), the end of the first permanent magnet (10) has a first protrusion (16), and the first protrusion (16) is arranged corresponding to the first flat edge (12) and the first cut edge (13); and / or the end of the second permanent magnet slot (3) has a second flat edge (14) and a second cut edge (15), the end of the second permanent magnet (11) has a second protrusion (17), and the second protrusion (17) is arranged corresponding to the second flat edge (14) and the second cut edge (15).

9. The rotor assembly according to claim 8, characterized in that The first protrusion (16) has a first side edge opposite to the first cutting edge (13), and the first side edge is parallel to the first cutting edge (13); and / or the second protrusion (17) has a second side edge opposite to the second cutting edge (15), and the spacing between the second side edge and the second cutting edge (15) is unequal.

10. The rotor assembly according to claim 8, characterized in that The projection length of the first flat edge (12) on the width cross section of the first straight line segment (5) on its side is b1, and the projection length of the first cut edge (13) on the width cross section of the first straight line segment (5) on its side is b2, wherein b1≤b2≤2.38b1; and / or the projection length of the second flat edge (14) on the width cross section of the second straight line segment (7) on its side is b1, and the projection length of the second cut edge (15) on the width cross section of the second straight line segment (7) on its side is b2, wherein b1≤b2≤2.38b1.

11. The rotor assembly according to claim 10, characterized in that The relationship between the first flat edge (12) and the first cut edge (13) satisfies b2=2.38b1; and / or the relationship between the second flat edge (14) and the second cut edge (15) satisfies b2=b1.

12. The rotor assembly according to claim 8, characterized in that The angle between the side of the first protrusion (16) opposite to the first flat edge (12) and the side opposite to the first cut edge (13) is de, 100deg≤de≤130deg; and / or the angle between the side of the second protrusion (17) opposite to the second flat edge (14) and the side opposite to the second cut edge (15) is de, 100deg≤de≤130deg.

13. The rotor assembly according to claim 1, characterized in that The cross-axis magnetic circuit between the first permanent magnet slot (2) and the second permanent magnet slot (3) satisfies: bw 2 =ec Wherein bw is the distance between the first straight line segment (5) and the second straight line segment (7), e is the distance between the inflection point of the radial outer arc edge of the first permanent magnet slot (2) and the inflection point of the radial inner arc edge of the second permanent magnet slot (3) located on the same side, and c is the distance between the radial outer arc edge of the first permanent magnet slot (2) and the radial inner arc edge of the second permanent magnet slot (3) on the permanent magnet center line.

14. The rotor assembly according to claim 13, characterized in that c≤e≤1.23c.

15. The rotor assembly according to claim 1, characterized in that f≤d≤2c, wherein f is the maximum width of the first permanent magnet slot (2) on the magnetic pole center line, d is the maximum width of the second permanent magnet slot (3) on the magnetic pole center line, and c is the distance between the radial outer arc edge of the first permanent magnet slot (2) and the radial inner arc edge of the second permanent magnet slot (3) on the permanent magnet center line.

16. The rotor assembly according to claim 4, characterized in that A first permanent magnet (10) is arranged in the first permanent magnet slot (2), and the radial magnetization point of the first permanent magnet (10) is the center of the radial outer arc edge of the first permanent magnet (10); and / or a second permanent magnet (11) is arranged in the second permanent magnet slot (3), and the radial magnetization point of the second permanent magnet (11) is the intersection of a line connecting the centers of two radial inner arc edges of the second permanent magnet (11) and a magnetic pole center line.

17. The rotor assembly according to claim 1, characterized in that The minimum distance between the first permanent magnet slot (2) and the central axis of the rotor core (1) is a, the length of the first straight line segment (5) is b, 0.38﹤(a+b) / r﹤0.63, where r is the radius of the rotor core (1).

18. The rotor assembly according to claim 1, wherein: The width change rate of the second permanent magnet slot (3) from the magnetic pole center line to both sides is greater than the width change rate of the first permanent magnet slot (2) from the magnetic pole center line to both sides.

19. The rotor assembly according to claim 1, characterized in that The rotor core (1) is also provided with a circulation hole (18), the circulation hole (18) is arranged on the radial inner peripheral side of the first permanent magnet slot (2), the circulation hole (18) is symmetrical about the magnetic pole center line, the circulation hole (18) includes circular parts (19) at both ends and a bridge part (20) connected between the circular parts (19) at both ends, and the width of the bridge part (20) gradually changes along the direction from the magnetic pole center line to both sides.

20. The rotor assembly according to claim 19, characterized in that The edge line of the bridge portion (20) is in an arc shape, and the width of the bridge portion (20) increases gradually along the direction from the center line of the magnetic pole to both sides.

21. The rotor assembly according to claim 20, characterized in that S1 / (S2+S3)≤0.26, where S1 is the area of ​​the bridge, S2 is the area of ​​the circular portion at one end, and S3 is the area of ​​the circular portion at the other end.

22. The rotor assembly according to claim 1, characterized in that The inflection point of the first permanent magnet slot (2) and the inflection point of the second permanent magnet slot (3) located on the same side of the magnetic pole centerline are located on the same straight line, and the straight line passes through the center of the radial inner arc edge of the first circular arc segment (4) of the first permanent magnet slot (2).

23. An electric machine, comprising a rotor assembly, characterized in that: The rotor assembly is the rotor assembly according to any one of claims 1 to 22.

24. A compressor, comprising a rotor assembly, characterized in that: The rotor assembly is the rotor assembly according to any one of claims 1 to 22.

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