Rotor Assemblies and Permanent Magnet Motors

Abstract

The present application provides a rotor assembly and a permanent magnet motor. The rotor assembly comprises a rotor core (1), a mounting groove (2) is arranged circumferentially on the rotor core (1), a permanent magnet (3) is installed in the mounting groove (2), first air grooves (4) are arranged at both ends of the mounting groove (2), a second air groove (5) is arranged between the magnetic pole center line and the first air groove (4) and on one side close to the first air groove (4), the first air groove (4) extends a first extension portion (8) toward the magnetic pole center line, and the first extension portion (8) and the second air groove (5) are arranged at intervals. According to the rotor assembly of the present application, the torque fluctuation of the permanent magnet motor during operation can be greatly reduced under the premise of ensuring the electromagnetic torque of the motor.

Description

Technical Field

[0001] The present application relates to the technical field of motors, and in particular to a rotor assembly and a permanent magnet motor. Background Art

[0002] Torque fluctuation is an inherent characteristic of the motor, which increases the torque fluctuation during the operation of the motor, thereby causing the vibration and operating noise of the motor to increase. The rotor main pole magnetic field is generally a non-strictly sinusoidal magnetic field, containing some harmonics, and when the motor is running under load, due to the armature reaction, the magnetic flux waveform will further deteriorate, the harmonic distortion rate will increase, and the motor torque fluctuation will increase. How to weaken the torque fluctuation of the permanent magnet motor is an industry problem. An effective measure is to open some narrow slots in the pole shoe part of the rotor to weaken the armature reaction of the motor, thereby reducing the air gap magnetic flux distortion rate.

[0003] However, research has found that although the existing technology can reduce torque fluctuations, the large number of air gaps on the pole shoes will weaken the amplitude of the air gap magnetic flux, resulting in a significant decrease in the output torque of the motor and a decrease in the motor's operating performance. On the other hand, the number, shape, and position of the slots are closely related to the structure of the rotor. When the rotor structure of the motor changes, its effect will be reduced or even counterproductive. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present application is to provide a rotor assembly and a permanent magnet motor, which can significantly reduce the torque fluctuation of the permanent magnet motor during operation while ensuring that the electromagnetic torque of the motor is not affected.

[0005] In order to solve the above problems, the present application provides a rotor assembly, including a rotor core, a mounting groove is circumferentially arranged on the rotor core, a permanent magnet is installed in the mounting groove, a first air groove is respectively arranged at both ends of the mounting groove, a second air groove is arranged between the magnetic pole center line and the first air groove on the side close to the first air groove, the first air groove extends a first extension portion toward the magnetic pole center line, and the first extension portion is spaced apart from the second air groove.

[0006] Preferably, the first extension portion is disposed on a side of the first air groove that is radially away from the mounting groove.

[0007] Preferably, the first air groove and the first extension portion are arc-shaped, the central angle of the first air groove is ar22, and the central angle of the first extension portion is ar21, wherein ar21 / ar22=0.1-0.2.

[0008] Preferably, the radial thickness of the first extension portion is w21, and the radial thickness of a side of the first air slot close to the first extension portion is w22, wherein w21 / w22=0.29-0.5.

[0009] Preferably, in a plane perpendicular to the central axis of the rotor core, the angle formed by the line connecting the two endpoints of the radial outer edges of the two first extensions and the center of the rotor core is ar2, and the angle formed by the line connecting the two endpoints of the radial outer edges of the permanent magnet and the center of the rotor core is ar3, where ar2 / ar3=0.7~0.9.

[0010] Preferably, the second air slot extends a second extension portion toward the center line of the magnetic pole, and the second extension portion is spaced apart.

[0011] Preferably, the second air slot and the second extension portion are arc-shaped, the central angle of the second air slot is ar12, and the central angle of the second extension portion is ar11, wherein ar11 / ar12=0.2-0.4.

[0012] Preferably, in a plane perpendicular to the central axis of the rotor core, the angle formed by the line connecting the two endpoints of the radial outer edges of the two second extensions and the center of the rotor core is ar1, and the angle formed by the line connecting the two endpoints of the radial outer edges of the permanent magnet and the center of the rotor core is ar3, where ar1 / ar3=0.3~0.6.

[0013] Preferably, the second air groove has a radial thickness w12, and the second extension portion has a radial thickness w11, wherein w11 / w12=0.5-0.8.

[0014] Preferably, a third air slot is provided on the center line of the magnetic pole, the third air slot is in a concave shape, and the opening of the third air slot is away from the mounting slot.

[0015] Preferably, the bottom wall and the side wall of the third air slot are connected via an inclined section, and the spacing between the inclined sections on both sides of the bottom wall increases radially away from the central axis of the rotor core.

[0016] Preferably, the maximum distance between the radial outer edge of the third air slot and the mounting slot is tr01, and the thickness of the pole shoe located on the center line of the magnetic pole is trs0, wherein tr01 / trs0=0.5-0.7.

[0017] Preferably, in a plane perpendicular to the central axis of the rotor core, the angle formed by the line connecting the two end points of the radial outer edge of the recess of the third air slot and the center of the rotor core is ar01, and the third air slot includes two circumferential side walls located on the circumferential outside, and the angle formed by the line connecting the radial outer end points of the two circumferential side walls and the center of the rotor core is ar02, wherein ar01 / ar02=0.2~0.4.

[0018] Preferably, in a plane perpendicular to the central axis of the rotor core, a magnetic isolation bridge is formed between two first air slots belonging to different magnetic poles, the minimum width of the magnetic isolation bridge is wb1, and the maximum width of the magnetic isolation bridge is wb2, wherein wb1 / wb2=0.2~0.4.

[0019] Preferably, the permanent magnet is in the shape of a straight line.

[0020] According to another aspect of the present application, a permanent magnet motor is provided, comprising a rotor assembly and a stator assembly, wherein the rotor assembly is the above-mentioned rotor assembly.

[0021] Preferably, the stator assembly comprises a stator tooth shoe, the middle part of the inner circumference of the stator tooth shoe is an arc surface, and both ends of the stator tooth shoe in the circumferential direction are flat surfaces.

[0022] Preferably, in a plane perpendicular to the central axis of the rotor core, the angle formed by the line connecting the two endpoints of the arc surface and the center of the rotor core is as1, and the angle formed by the line connecting the outer endpoints on both sides of the stator tooth shoe on the circumferential direction and the center of the rotor core is as2, where as1 / as2=0.52~0.72.

[0023] The rotor assembly provided by the present application includes a rotor core, a mounting groove is arranged circumferentially on the rotor core, a permanent magnet is installed in the mounting groove, a first air groove is arranged at both ends of the mounting groove, a second air groove is arranged between the magnetic pole center line and the first air groove on the side close to the first air groove, the first air groove extends a first extension portion toward the magnetic pole center line, and the first extension portion is arranged at intervals with the second air groove. The rotor assembly of the present application is respectively provided with a first air groove and a second air groove in the pole shoe part, and the first air groove and the second air groove are arranged at intervals, and the first air groove and the second air groove can be used to shunt the magnetic lines of force emitted by the permanent magnet, and a first extension portion is arranged on the first air groove, the first extension portion is used to sort out the magnetic flux of the pole shoe part, the first extension portion extends toward the magnetic pole center line, and the air gap magnetic density waveform is more effectively adjusted, and the first extension portion has a small effect on the torque amplitude, so that the torque fluctuation of the permanent magnet motor during operation can be greatly reduced under the premise of ensuring that the electromagnetic torque of the motor is not affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a rotor assembly according to a first embodiment of the present application;

[0025] Figure 2 A first dimension structure diagram of a rotor assembly according to a first embodiment of the present application;

[0026] Figure 3 A second dimension structure diagram of the rotor assembly of the first embodiment of the present application;

[0027] Figure 4A third dimension structure diagram of the rotor assembly of the first embodiment of the present application;

[0028] Figure 5 A magnetic field line distribution diagram of the rotor assembly of the first embodiment of the present application when the second air slot has a second extension portion;

[0029] Figure 6 This is a magnetic field line distribution diagram of the rotor assembly of the first embodiment of the present application when the second air slot has no second extension portion;

[0030] Figure 7 The air gap magnetic flux density diagram of the second air slot of the rotor assembly of the first embodiment of the present application when the second extension portion is present and when the second extension portion is not present;

[0031] Figure 8 This is a curve diagram showing the influence of ar11 / ar12 on torque fluctuation of the rotor assembly of the first embodiment of the present application;

[0032] Fig. 9 This is a curve diagram showing the influence of w11 / w12 on torque fluctuation of the rotor assembly of the first embodiment of the present application;

[0033] Fig.10 A comparison diagram of electromagnetic torque curves of the rotor assembly of the first embodiment of the present application and the prior art;

[0034] Fig.11 This is a schematic structural diagram of a rotor assembly according to a second embodiment of the present application;

[0035] Fig.12 A first dimension structure diagram of a rotor assembly according to a second embodiment of the present application;

[0036] Fig.13 A second dimension structure diagram of a rotor assembly according to a second embodiment of the present application;

[0037] Fig.14 is a magnetic force line distribution diagram of the rotor assembly when the third air slot has no concave portion;

[0038] Fig.15 A magnetic field line distribution diagram of the rotor assembly of the second embodiment of the present application when the third air slot is in a concave shape;

[0039] Fig.16 This is a curve diagram showing the influence of tr01 / trs0 on torque fluctuation of the rotor assembly of the second embodiment of the present application;

[0040] Fig.17 This is a graph showing the influence of ar01 / ar02 on harmonic content of the rotor assembly of the second embodiment of the present application.

[0041] The reference numerals are as follows:

[0042] 1. Rotor core; 2. Mounting slot; 3. Permanent magnet; 4. First air slot; 5. Second air slot; 6. Third air slot; 7. Magnetic isolation bridge; 8. First extension part; 9. Second extension part; 10. Stator tooth shoe. DETAILED DESCRIPTION

[0043] See also Figures 1 to 10 As shown, according to the first embodiment of the present application, the rotor assembly includes a rotor core 1, a mounting groove 2 is circumferentially arranged on the rotor core 1, a permanent magnet 3 is installed in the mounting groove 2, first air grooves 4 are respectively arranged at both ends of the mounting groove 2, a second air groove 5 is arranged between the magnetic pole center line and the first air groove 4 on one side close to the first air groove 4, the first air groove 4 extends a first extension portion 8 toward the magnetic pole center line, and the first extension portion 8 is spaced apart from the second air groove 5.

[0044] The rotor assembly of the present application is provided with a first air slot 4 and a second air slot 5 in the pole shoe part, and the first air slot 4 and the second air slot 5 are arranged at intervals, so that the first air slot 4 and the second air slot 5 can be used to shunt the magnetic lines of force emitted by the permanent magnet 3. At the same time, a first extension portion 8 is provided on the first air slot 4, and the first extension portion 8 is used to organize the magnetic flux of the pole shoe part. The first extension portion 8 extends toward the center line of the magnetic pole, which more effectively adjusts the air gap magnetic flux waveform, and the first extension portion 8 has little effect on the torque amplitude. Therefore, the torque fluctuation of the permanent magnet motor during operation can be greatly reduced while ensuring that the electromagnetic torque of the motor is not affected.

[0045] The simulation shows that, compared with the prior art, the electromagnetic torque of the motor of the present application is increased by 10% and the torque fluctuation is reduced by 10%.

[0046] Preferably, the first extension portion 8 is arranged on the side of the first air slot 4 radially away from the mounting slot 2, that is, the first extension portion 8 is arranged on the side of the first air slot 4 close to the outer circle of the rotor core. The first extension portion 8 is a part of the first air slot 4 and is arranged close to the outer circle of the rotor core, which makes it easier to adjust the distribution of magnetic lines of force in the air gap, making the air gap distribution more uniform and the torque fluctuation smaller. And because the radial thickness of the first extension portion 8 is smaller than the overall radial thickness of the first air slot 4, it has little effect on the amplitude of the torque, thereby effectively ensuring the torque capacity of the motor.

[0047] Preferably, the circumferential width of the first air slot 4 close to the permanent magnet is smaller than the circumferential width of the first air slot 4 close to the outer circumference of the rotor core 1 .

[0048] Preferably, the first air groove 4 and the second air groove 5 are both connected to the mounting groove 2, which can shunt the magnetic lines of force of the permanent magnet from the position where the magnetic lines of force of the permanent magnet are emitted, more effectively avoid magnetic leakage, form a better and more effective regularization effect on the magnetic lines of force, and more effectively adjust the air gap magnetic density waveform.

[0049] The first air slot 4 and the first extension 8 are arc-shaped, and the sum of the central angles of the first air slot 4 and the first extension 8 is ar22, and the central angle of the first extension 8 is ar21, wherein ar21 / ar22=0.1-0.2. The portion of the first air slot 4 close to the permanent magnet 3 shunts the magnetic lines of force of the permanent magnet 3, performs primary guidance of the distribution of the magnetic lines of force, and then the first extension 8 performs secondary guidance. Since the permanent magnet 3 is a straight line, and the outer circle of the rotor core 1 is an arc, the length is greater than the straight line of equal arc, so the present application is provided with the first extension 8, further reducing the angle of the first air slot 4, so that the guided magnetic lines of force are evenly distributed, and the torque fluctuation is reduced. If the first extension 8 is too long, the first extension 8 will block the magnetic lines of force too strongly, and magnetic saturation is easily formed. If the first extension part 8 is too small or even does not exist, although the magnetic lines of force are well distributed near the permanent magnet 3, the part near the outer circle of the rotor core 1 will be diluted, causing increased torque fluctuations. Studies have shown that the best effect is achieved when the ratio of the two is 0.1 to 0.2.

[0050] The radial thickness of the first extension portion 8 is w21, and the radial thickness of the first air slot 4 on the side close to the first extension portion 8 is w22, wherein w21 / w22=0.29-0.5. When the ratio of the two is small, the effective magnetic resistance formed by the first extension portion 8 is small, and the flow direction of the magnetic lines of force cannot be effectively adjusted. When the ratio of the two is large, the first extension portion 8 blocks the magnetic lines of force too much, causing a decrease in the electromagnetic torque. Studies have shown that the effect is better when the ratio of the two is 0.3-0.5.

[0051] In a plane perpendicular to the central axis of the rotor core 1, the angle formed by the two ends of the radial outer edges of the two first extensions 8 and the line connecting the center of the rotor core 1 is ar2, and the angle formed by the two ends of the radial outer edges of the permanent magnet 3 and the line connecting the center of the rotor core 1 is ar3, where ar2 / ar3=0.7-0.9. ar2 represents the total width of the permanent magnet 3 facing the air gap, and ar3 represents the maximum magnetic flux area that the permanent magnet can provide. If the ratio of the two is small, the circumferential width of the first air slot 4 including the first extension 8 is small, the magnetic bridge at both ends of the permanent magnet is short, and the leakage magnetic flux increases. If the ratio of the two is large, the first air slot 4 including the first extension 8 blocks more of the magnetic flux surface of the permanent magnet 3, the effective magnetic flux surface is reduced, and the electromagnetic torque decreases. Studies have shown that it is best to control the ratio of the two to 0.7-0.9.

[0052] The second air slot 5 extends a second extension portion 9 toward the center line of the magnetic pole, and the second extension portion 9 is arranged at intervals. The second extension portion 9 extends circumferentially toward the first air slot 4, which can further improve the distribution of magnetic lines of force between the first air slot 4 and the second air slot 5, improve the uniformity of the distribution of magnetic lines of force, and reduce torque fluctuations. The second extension portion 9 is a part of the second air slot 5, and the radial thickness is less than the maximum radial thickness of the second air slot 5. Preferably, the second extension portion 9 is arranged on a side of the second air slot 5 away from the mounting slot 2.

[0053] The second air slot 5 and the second extension 9 are arc-shaped, the sum of the central angles of the second air slot 5 and the second extension 9 is ar12, the central angle of the second extension 9 is ar11, wherein ar11 / ar12=0.2-0.4. Studies have shown that setting the air slots at the pole shoe along the direction of the magnetic field line can avoid the decrease of the motor output torque, such as Figure 5 As shown, the second air slot 5 is arranged along the direction of the magnetic lines of force. The portion of the second air slot 5 close to the permanent magnet 3 shunts the magnetic lines of force of the permanent magnet 3, and performs primary guidance of the distribution of the magnetic lines of force. Then the second extension portion 9 performs secondary guidance. Since the permanent magnet 3 is a straight line, and the outer circle of the rotor core 1 is an arc, and the length is greater than the straight line of equal arc, the second extension portion 9 is provided in the present application to further reduce the angle of the second air slot 5, so that the guided magnetic lines of force are evenly distributed, thereby reducing torque fluctuations. If the second extension portion 9 is too long, the second extension portion 9 will block the magnetic lines of force too strongly, and magnetic saturation will be formed. If the second extension portion 9 is too small, or even does not exist, although the magnetic lines of force are better distributed near the permanent magnet 3, the portion close to the outer circle of the rotor core 1 will be diluted, such as Figures 5 to 7 As shown, it is easy to cause torque fluctuation to increase. Studies have shown that the best ratio between the two is 0.2 to 0.4. Figure 8 shown.

[0054] In a plane perpendicular to the central axis of the rotor core 1, the angle formed by the two end points of the radial outer edges of the two second extensions 9 and the line connecting the center of the rotor core 1 is ar1, and the angle formed by the two end points of the radial outer edges of the permanent magnet 3 and the line connecting the center of the rotor core 1 is ar3, where ar1 / ar3=0.3~0.6. ar3 represents the maximum magnetic flux area that the permanent magnet can provide, and ar1 represents the width of the center of the magnetic pole. The larger the ratio of the two, the more saturated the magnetic flux in the center of the magnetic pole, and the higher the back electromotive force distortion rate. The smaller the ratio of the two, the fewer magnetic lines of force in the center of the magnetic pole, the smaller the amplitude of the fundamental wave of the magnetic flux, and the lower the motor torque. Studies have shown that it is best to limit the ratio of the two to 0.3~0.6.

[0055] The second air slot 5 has a radial thickness w12, and the second extension portion 9 has a radial thickness w11, wherein w11 / w12=0.5-0.8. w12 is the overall radial thickness of the second air slot 5, and w11 is the radial thickness of the second extension portion 9. If the ratio between the two is too small, the effective magnetic resistance formed by the second extension portion 9 will be small, and the flow direction of the magnetic lines of force cannot be effectively adjusted. If the ratio between the two is too large, the second extension portion 9 will block the magnetic lines of force too much, causing a decrease in the electromagnetic torque. Studies have shown that a better ratio between the two is 0.5-0.8, and the torque fluctuation within this range is small, such as Fig. 9 shown.

[0056] Preferably, the permanent magnet 3 in this embodiment is in a straight line shape. The permanent magnet 3 may also be in other shapes, such as a V-shape.

[0057] In this embodiment, the rotor core 1 is formed by laminating thin sheets of soft magnetic material and adopts a disc-type slotted structure. An array of mounting slots 2 is provided on the rotor core 1, and a permanent magnet 3 is provided in each mounting slot 2. The plurality of mounting slots 2 are evenly distributed along the circumference of the rotor core 1. A permanent magnet 3 is provided on each magnetic pole of the rotor core in this embodiment, so that each magnetic pole can form a permanent magnetic pole. The mounting slot 2 is, for example, rectangular or other shapes. The shape of the mounting slot 2 is adapted to the shape of the permanent magnet 3, and the number is consistent with the number of the permanent magnet 3.

[0058] The permanent magnets 3 are installed in the installation slots 2 on the rotor yoke. A plurality of permanent magnets 3 are distributed on the rotor yoke at intervals along the circumferential direction, and adjacent permanent magnets of the same polarity are arranged opposite to each other.

[0059] The torque curve of the motor designed by this application is compared with the prior art. Fig.10 As shown, it is obvious that the technical solution of the present application has a larger average torque and smaller torque fluctuation compared with the prior art.

[0060] See also Figures 11 to 17 As shown, according to the second embodiment of the present application, it is basically the same as the first embodiment, except that, in this embodiment, a third air groove 6 is arranged on the center line of the magnetic pole, the third air groove 6 is concave in shape, and the opening of the third air groove 6 is away from the mounting groove 2.

[0061] In this embodiment, adjacent third air slots 6 belonging to different magnetic poles are not connected to each other, and a magnetic isolation bridge 7 is formed between them.

[0062] Research shows that, affected by the rotor position, the magnetic lines of force at the center of the magnetic poles are distributed differently at different times, resulting in large torque fluctuations during operation. In order to make the distribution of magnetic lines of force near the center of the magnetic poles less affected by the rotor position, a third air slot 6 is provided. The portion of the third air slot 6 close to the permanent magnet 3 is used to shunt the magnetic lines of force emitted by the permanent magnet 3, so the side close to the permanent magnet 3 is designed to be multi-segment linear to guide the magnetic lines of force more smoothly. At the same time, in order to avoid forming a large air slot in the rotor pole shoe to increase the magnetic resistance of the main magnetic circuit, the center of the third air slot 6 is hollowed out and turned into a concave shape, so that a small amount of magnetic lines of force can pass through, such as Fig.15 shown.

[0063] The third air slot 6 is close to one side of the permanent magnet 3, and its multi-segment line structure is specifically that the bottom wall and the side wall of the third air slot 6 are connected by an inclined segment, and the spacing between the inclined segments on both sides of the bottom wall increases radially away from the central axis of the rotor core 1. The bottom wall of the third air slot is arc-shaped, and the center of the arc is located on the central axis of the rotor core 1. The two inclined segments are both planes, which is equivalent to cutting the two corners of the concave structure flat, shortening the overall length of the bottom wall, and increasing the spacing between the inclined segments at both ends of the bottom wall and the permanent magnet 3, which can better regularize the magnetic lines of force and make the distribution of the magnetic lines of force more uniform. Fig.14 and Fig.15 shown.

[0064] The maximum distance between the radial outer edge of the third air slot 6 and the mounting slot 2 is tr01, and the thickness of the pole shoe located on the center line of the magnetic pole is trs0, wherein tr01 / trs0=0.5~0.7. If the ratio between the two is too small, the effective magnetic resistance formed by the third air slot 6 is small, and the third air slot 6 is far away from the outer circle of the rotor core 1, and the flow direction of the magnetic lines of force cannot be effectively adjusted. If the ratio between the two is too large, the third air slot 6 will block too much magnetic lines of force, causing a decrease in electromagnetic torque. Studies have shown that a ratio of 0.5 to 0.7 has a better effect, such as Fig.16 shown.

[0065] In a plane perpendicular to the central axis of the rotor core 1, the angle formed by the two endpoints of the radial outer edge of the concave portion of the third air slot 6 and the line connecting the center of the rotor core 1 is ar01. The third air slot 6 includes two circumferential side walls located on the circumferential outside, and the angle formed by the line connecting the radial outer endpoints of the two circumferential side walls and the center of the rotor core 1 is ar02, wherein ar01 / ar02=0.2~0.4. The larger the ratio of the two, the thinner the wall thickness of the third air slot 6, the smaller the effective magnetic resistance that can be formed, and the weaker the modulation effect on the magnetic lines of force; the smaller the ratio of the two, the greater the effective magnetic resistance formed by the third air slot 6. Although the torque fluctuation can be reduced, the output torque is also reduced. Therefore, it is better to control the ratio within 0.2~0.4, such as Fig.17 shown.

[0066] In a plane perpendicular to the central axis of the rotor core 1, a magnetic isolation bridge 7 is formed between two first air slots 4 belonging to different magnetic poles, the minimum width of the magnetic isolation bridge 7 is wb1, and the maximum width of the magnetic isolation bridge 7 is wb2, wherein wb1 / wb2=0.2~0.4. The width of the magnetic isolation bridge 7 gradually increases radially outward, which can increase the strength of the rotor structure on the one hand, and increase the magnetic permeability of the q-axis magnetic circuit on the other hand, which is the main magnetic circuit of the armature magnetic lines of force, thereby improving the electromagnetic torque of the motor. However, if the width is too wide, the leakage magnetic flux at the ends of the permanent magnets and between adjacent permanent magnets will increase, and the electromagnetic torque will decrease. Therefore, it is necessary to limit the ratio of the minimum width and the maximum width of the magnetic isolation bridge to wb1 / wb2=0.2~0.4, so as to ensure that the motor has better working performance.

[0067] According to an embodiment of the present application, the permanent magnet motor includes a stator assembly and a rotor assembly, and the rotor assembly is the above-mentioned rotor assembly.

[0068] Preferably, the stator assembly includes a stator tooth shoe 10, the middle part of the inner circumference of the stator tooth shoe 10 is an arc surface, and the two circumferential ends of the stator tooth shoe 10 are planes. Both ends of the stator tooth shoe 10 in the circumferential direction form a trapezoidal structure, and the inner circumference of both ends form an upwardly inclined plane, which can increase the air gap between the two ends of the inner circumference of the stator tooth shoe 10 and the rotor assembly. By forming a larger air gap on both sides of the stator tooth shoe 10, the amplitude of the harmonic can be weakened, and a smaller air gap is formed in the center of the stator tooth shoe 10, which can ensure the amplitude of the fundamental wave.

[0069] Preferably, in a plane perpendicular to the central axis of the rotor core 1, the angle formed by the two endpoints of the arc surface and the line connecting the center of the rotor core 1 is as1, and the angle formed by the outer endpoints on both sides of the stator tooth shoe 10 and the line connecting the center of the rotor core 1 is as2, where as1 / as2=0.52~0.72. as1 represents the size of the middle part of the stator tooth shoe 10, and as2 represents the size of the circumferential width of the entire stator tooth shoe 10. The amplitude of the harmonics is weakened by forming a larger air gap on both sides of the stator tooth shoe 10, and the amplitude of the fundamental wave is ensured by forming a smaller air gap in the center of the stator tooth shoe 10. If the ratio of the two is too large, the air gap of the tooth attachment is relatively uniform, and the amplitudes of the magnetic flux fundamental wave and the magnetic flux harmonic are both large, which cannot play a role in weakening the magnetic flux harmonics. If the ratio of the two is too small, the length of the equivalent air gap will increase significantly, the amplitude of the fundamental wave will drop significantly, and the motor torque will drop. Studies have shown that the ratio of the two is best between 0.52 and 0.72.

[0070] It is easy for those skilled in the art to understand that the above-mentioned advantageous methods can be freely combined and superimposed without conflict.

[0071] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. 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 application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A rotor assembly, characterized in that: The invention comprises a rotor core (1), wherein a mounting groove (2) is arranged on the rotor core (1) along the circumferential direction, a permanent magnet (3) is installed in the mounting groove (2), first air grooves (4) are arranged at both ends of the mounting groove (2), a second air groove (5) is arranged between a magnetic pole center line and the first air groove (4) and on a side close to the first air groove (4), the first air groove (4) extends a first extension portion (8) toward the magnetic pole center line, and the first extension portion (8) is arranged at a distance from the second air groove (5); A third air slot (6) is arranged on the center line of the magnetic pole, the third air slot (6) is in a concave shape, the opening of the third air slot (6) is away from the mounting slot (2), the maximum distance between the radial outer edge of the third air slot (6) and the mounting slot (2) is tr01, and the thickness of the pole shoe located on the center line of the magnetic pole is trs0, wherein tr01 / trs0=0.5-0.

7.

2. The rotor assembly according to claim 1, characterized in that: The first extension portion (8) is arranged on a side of the first air groove (4) that is radially away from the mounting groove (2).

3. The rotor assembly according to claim 2, characterized in that: The first air groove (4) and the first extension portion (8) are arc-shaped, the center angle of the first air groove (4) is ar22, and the center angle of the first extension portion (8) is ar21, wherein ar21 / ar22=0.1-0.

2.

4. The rotor assembly according to claim 2, characterized in that: The radial thickness of the first extension portion (8) is w21, and the radial thickness of the first air groove (4) on a side close to the first extension portion (8) is w22, wherein w21 / w22=0.29-0.

5.

5. The rotor assembly according to claim 2, characterized in that: In a plane perpendicular to the central axis of the rotor core (1), the angle formed by the line connecting the two end points of the radial outer edges of the two first extensions (8) and the center of the rotor core (1) is ar2, and the angle formed by the line connecting the two end points of the radial outer edges of the permanent magnet (3) and the center of the rotor core (1) is ar3, where ar2 / ar3=0.7~0.

9.

6. The rotor assembly according to claim 1, characterized in that The second air slot (5) extends a second extension portion (9) toward the magnetic pole center line, and the second extension portion (9) is spaced apart from the first air slot (4).

7. The rotor assembly according to claim 6, characterized in that The second air groove (5) and the second extension portion (9) are arc-shaped, the center angle of the second air groove (5) is ar12, and the center angle of the second extension portion (9) is ar11, wherein ar11 / ar12=0.2-0.

4.

8. The rotor assembly according to claim 6, characterized in that In a plane perpendicular to the central axis of the rotor core (1), the angle formed by the line connecting the two end points of the radial outer edges of the two second extensions (9) and the center of the rotor core (1) is ar1, and the angle formed by the line connecting the two end points of the radial outer edges of the permanent magnet (3) and the center of the rotor core (1) is ar3, where ar1 / ar3=0.3~0.

6.

9. The rotor assembly according to claim 6, characterized in that: The second air groove (5) has a radial thickness w12, and the second extension portion (9) has a radial thickness w11, wherein w11 / w12=0.5-0.

8.

10. The rotor assembly according to claim 1, characterized in that The bottom wall and the side wall of the third air slot (6) are connected via an inclined section, and the spacing between the inclined sections on both sides of the bottom wall increases radially away from the central axis of the rotor core (1).

11. The rotor assembly according to claim 1, characterized in that In a plane perpendicular to the central axis of the rotor core (1), the angle formed by the line connecting the two end points of the radial outer edge of the concave portion of the third air slot (6) and the center of the rotor core (1) is ar01, and the third air slot (6) includes two circumferential side walls located on the circumferential outer side, and the angle formed by the line connecting the radial outer end points of the two circumferential side walls and the center of the rotor core (1) is ar02, wherein ar01 / ar02=0.2~0.

4.

12. The rotor assembly according to any one of claims 1 to 9, characterized in that: In a plane perpendicular to the central axis of the rotor core (1), a magnetic isolation bridge (7) is formed between two first air slots (4) belonging to different magnetic poles, the minimum width of the magnetic isolation bridge (7) is wb1, and the maximum width of the magnetic isolation bridge (7) is wb2, wherein wb1 / wb2=0.2-0.

4.

13. The rotor assembly according to any one of claims 1 to 9, characterized in that: The permanent magnet (3) is in the shape of a straight line.

14. A permanent magnet motor, comprising a stator assembly and a rotor assembly, characterized in that: The rotor assembly is the rotor assembly according to any one of claims 1 to 13.

15. The permanent magnet motor according to claim 14, characterized in that: The stator assembly comprises a stator tooth shoe (10), the middle part of the inner circumference of the stator tooth shoe (10) is an arc surface, and the two circumferential ends of the stator tooth shoe (10) are flat surfaces.

16. The permanent magnet motor according to claim 15, characterized in that: In a plane perpendicular to the central axis of the rotor core (1), the angle formed by the line connecting the two end points of the arc surface and the center of the rotor core (1) is as1, and the angle formed by the line connecting the outer end points on both sides of the stator tooth shoe (10) in the circumferential direction and the center of the rotor core (1) is as2, wherein as1 / as2=0.52~0.72.

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