Motor assemblies, permanent magnet synchronous motors and compressors

Abstract

The present application provides a motor assembly, a permanent magnet synchronous motor, and a compressor. The motor assembly includes a stator and a rotor. In the radial direction of the stator, the thickness of the first pole shoe is greater than the thickness of the second pole shoe. The rotor is provided with circumferentially extending magnetic steel slots. The outer periphery of the rotor corresponding to the magnetic steel slots is provided with a cut edge. The cut edge is located on the same side of the outer periphery as the second side. The present application forms an uneven air gap structure between the stator and the rotor by providing a partially cut-off cut edge structure on the outer periphery of the rotor and increasing the thickness of the pole shoe on one side of the stator teeth. This effectively improves the air gap magnetic field waveform of the motor, weakens the uneven air gap caused by the crankshaft eccentricity, and improves the sinusoidal degree of the air gap magnetic resistance to obtain the desired sinusoidal air gap magnetic density, thereby greatly reducing the torque pulsation of the motor, effectively reducing the cogging torque, thereby reducing the electromagnetic vibration and electromagnetic noise of the motor, and improving the performance of the motor.

Description

Technical Field

[0001] The present application belongs to the technical field of compressors, and specifically relates to a motor assembly, a permanent magnet synchronous motor and a compressor. Background Art

[0002] Permanent magnet synchronous motors have advantages such as small size and simple structure and are widely used in the industry. However, like traditional motors, they also have problems with vibration and noise. In particular, motors in the compressor field are usually connected to the crankshaft structure. The crankshaft itself is eccentric, and the eccentricity will cause the motor to form a non-sinusoidal air gap magnetic density, causing the motor to generate large electromagnetic vibrations and electromagnetic noise. This will not only affect the service life of the motor, especially in some special working environments and fields with strict noise requirements, the noise problem will cause great trouble and also have a great impact on the performance of the motor. Summary of the Invention

[0003] Therefore, the present application provides a motor assembly, a permanent magnet synchronous motor and a compressor, which can solve the problem in the prior art that the motor forms a non-sinusoidal air gap magnetic flux density, causing the motor to generate large electromagnetic vibration and electromagnetic noise.

[0004] In order to solve the above problems, the present application provides a motor assembly, comprising:

[0005] A stator and a rotor, wherein the rotor is inserted into the stator;

[0006] The stator includes stator teeth, each of which is provided with a first pole shoe and a second pole shoe, wherein the first pole shoe is provided on a first side of the stator tooth, and the second pole shoe is provided on a second side of the stator tooth; in a radial direction along the stator, a thickness of the first pole shoe is greater than a thickness of the second pole shoe;

[0007] A circumferentially extending magnetic steel slot is provided in the rotor; when the center line of the magnetic steel slot coincides with the radial extension direction of the stator tooth, a cut edge is provided on the outer periphery of the rotor corresponding to the magnetic steel slot; the cut edge is located on the same side of the outer periphery as the second side.

[0008] Optionally, in the radial direction of the stator, the difference in thickness between the first pole shoe and the second pole shoe ranges from 1.5 to 2.5 mm.

[0009] Optionally, the first pole shoe includes a portion having the same thickness as that of the second pole shoe and a protrusion provided on the shoe surface of the first pole shoe.

[0010] Optionally, a recess is provided on the surface of the second pole shoe.

[0011] Optionally, the cut edge is located on one side of the center line of the magnetic steel slot, and the cut edge and the outer periphery of the rotor are arranged in a circular arc transition.

[0012] Optionally, the cut edge is set to a crescent-shaped arc area, or an arc-shaped groove recessed into the outer periphery of the rotor.

[0013] Optionally, in the cross section of the motor assembly, the area of the first pole shoe is set to S4, the area of the second pole shoe is set to S3, and the area of the cut edge is set to S1, satisfying S4-S3≤S1.

[0014] According to another aspect of the present application, a permanent magnet synchronous motor is provided, comprising the motor assembly as described above.

[0015] Optionally, in a cross section of the motor assembly, the area of the first pole shoe is set to S4, the area of the second pole shoe is set to S3, and the area of the cut edge is set to S1, satisfying: Among them, R3 is the outer peripheral radius of the rotor, R4 is the radius of the circle where the crescent-shaped cut edge is located, a is the angle between two adjacent Q axes; and P is the number of pole pairs of the motor.

[0016] According to another aspect of the present application, a compressor is provided, comprising the motor assembly as described above or the permanent magnet synchronous motor as described above.

[0017] A motor assembly provided in the present application includes: a stator and a rotor, the rotor being inserted into the stator; the stator including stator teeth, the stator teeth being provided with a first pole shoe and a second pole shoe, the first pole shoe being provided on a first side of the stator tooth, and the second pole shoe being provided on a second side of the stator tooth; in a radial direction along the stator, the thickness of the first pole shoe is greater than the thickness of the second pole shoe; the rotor is provided with a circumferentially extending magnetic steel slot; when the center line of the magnetic steel slot coincides with the radial extension direction of the stator tooth, a cut edge is provided on the outer periphery of the rotor corresponding to the magnetic steel slot; the cut edge is located on the same side of the outer periphery as the second side.

[0018] The present application forms an uneven air gap structure between the stator and the rotor by providing a partially cut-off edge structure on the outer periphery of the rotor and increasing the thickness of the pole shoe on one side of the stator teeth, thereby effectively improving the air gap magnetic field waveform of the motor, weakening the uneven air gap caused by the eccentricity of the crankshaft, and improving the sinusoidal degree of the air gap magnetic resistance to obtain the desired sinusoidal air gap magnetic density, thereby greatly reducing the torque pulsation of the motor and effectively reducing the cogging torque, thereby reducing the electromagnetic vibration and electromagnetic noise of the motor, improving the performance of the motor, and increasing the service life of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic cross-sectional view of a motor assembly according to an embodiment of the present application;

[0020] Figure 2 This is a schematic structural diagram of a stator according to an embodiment of the present application;

[0021] Figure 3 This is a schematic structural diagram of a rotor according to an embodiment of the present application;

[0022] Figure 4 Two other structural schematic diagrams of the stator according to the embodiment of the present application;

[0023] Figure 5 This is another schematic structural diagram of the rotor according to an embodiment of the present application;

[0024] Figure 6 This is a comparison diagram of the cogging torque of the motor according to the embodiment of the present application and the motor before improvement;

[0025] Figure 7 This is a comparison diagram of the no-load back EMF harmonic difference between the motor according to the embodiment of the present application and the motor before improvement;

[0026] Figure 8 This is a comparison diagram of the difference in no-load air gap magnetic density harmonic content between the motor according to the embodiment of the present application and the motor before improvement;

[0027] Figure 9 This is a comparison chart of the total vibration values of the motor according to the embodiment of the present application and the motor before improvement;

[0028] Figure 10 This is a comparison chart of the MAX vibration peak values of the motor according to the embodiment of the present application and the motor before improvement.

[0029] The reference numerals indicate:

[0030] 1. Stator; 11. Stator teeth; 111. First pole shoe; 112. Second pole shoe; 2. Rotor; 21. Magnetic steel slot; 22. Cutting edge. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] See also Figures 1 to 5 As shown, according to an embodiment of the present application, a motor assembly includes:

[0034] A stator 1 and a rotor 2, wherein the rotor 2 is disposed in the stator 1;

[0035] The stator 1 includes a stator tooth 11, and a first pole shoe 111 and a second pole shoe 112 are provided on the stator tooth 11. The first pole shoe 111 is provided on a first side of the stator tooth 11, and the second pole shoe 112 is provided on a second side of the stator tooth 11. In the radial direction of the stator 1, the thickness of the first pole shoe 111 is greater than the thickness of the second pole shoe 112.

[0036] A circumferentially extending magnetic steel slot 21 is provided in the rotor 2; when the center line of the magnetic steel slot 21 coincides with the radial extension direction of the stator tooth 11, a cut edge 22 is provided on the outer periphery of the rotor 2 corresponding to the magnetic steel slot 21; the cut edge 22 is located on the same side of the outer periphery as the second side.

[0037] The present application provides a partially cut-off edge 22 structure on the outer periphery of the rotor 2 and increases the thickness of the single-sided pole shoe of the stator tooth 11, so that an uneven air gap structure is formed between the stator and rotor 2, effectively improving the air gap magnetic field waveform of the motor, weakening the uneven air gap caused by the crankshaft eccentricity, and improving the sinusoidal degree of the air gap magnetic resistance to obtain the desired sinusoidal air gap magnetic density, so that the torque pulsation of the motor is greatly reduced, and the cogging torque can be effectively reduced, thereby reducing the electromagnetic vibration and electromagnetic noise of the motor, improving the performance of the motor, and increasing the service life of the motor.

[0038] Here, the magnetic steel slot 21 is provided in the rotor 2 , and its extension direction is mainly the circumferential direction of the rotor 2 , and its center line is a line passing through the center of the rotor 2 and the center of the magnetic steel slot 21 .

[0039] In some embodiments, in the radial direction of the stator 1 , a thickness difference between the first pole shoe 111 and the second pole shoe 112 ranges from 1.5 to 2.5 mm.

[0040] For the two pole shoes at the same stator slot opening, setting the thickness difference within the above range can effectively reduce the slot torque. If the difference is too small, the effect of reducing the slot torque is not obvious. If it is too large, the manufacturability of the motor is relatively poor.

[0041] In some embodiments, the first pole shoe 111 includes a portion having the same thickness as the second pole shoe 112 and a protrusion provided on the surface of the first pole shoe 111 , or a depression is provided on the surface of the second pole shoe 112 .

[0042] The first pole shoe 111 can be provided with a protrusion on the portion having the same thickness as the second pole shoe 112, or the thickness of the two pole shoes can be substantially the same, but the surface of the second pole shoe 112 can be provided with a depression, so as to form a structure as follows: Figure 4 The two pole shoe structures, combined with the partially cut edge 22 structure set on the outer periphery of the rotor 2, form an uneven air gap structure between the stator and rotor 2, which greatly reduces the torque pulsation of the motor and can effectively reduce the cogging torque, thereby reducing the electromagnetic vibration and electromagnetic noise of the motor.

[0043] In some embodiments, the cut edge 22 is located on one side of the center line of the magnetic steel slot 21 , and the cut edge 22 and the outer periphery of the rotor 2 are arranged in an arc transition.

[0044] The main body of the cutting edge 22 is located on one side of the center line of the magnetic steel slot 21 and is arranged to form an arc transition with the outer periphery of the rotor 2, making the outer periphery smooth and reducing noise.

[0045] In some embodiments, the cutting edge 22 is configured as a crescent-shaped arc region, or an arc-shaped groove recessed toward the inner portion of the outer periphery of the rotor 2 .

[0046] The cutting edge 22 may be a crescent-shaped arc-shaped area structure, such as Figure 3 As shown, it is surrounded by two arcs of different radii, the outer arc is located on the outer circumference of the rotor 2, and the inner arc is set in transition with the arc of the outer peripheral edge of the rotor 2; or it can be set as an arc groove recessed into the inner periphery of the rotor 2, such as Figure 5 As shown, both situations can effectively improve the air gap magnetic field waveform of the motor, weaken the non-uniform air gap caused by the crankshaft eccentricity, and improve the sinusoidal degree of the air gap magnetic resistance to obtain the desired sinusoidal air gap magnetic density, so that the torque pulsation of the motor is greatly reduced, and the cogging torque can be effectively reduced, thereby reducing the electromagnetic vibration and electromagnetic noise of the motor.

[0047] In some embodiments, on the cross section of the motor assembly, the area of the first pole shoe 111 is set to S4, the area of the second pole shoe 112 is set to S3, and the area of the cut edge 22 is set to S1, satisfying S4-S3≤S1.

[0048] In order to ensure that the cogging torque can be effectively improved, the area occupied by the cutting edge 22 and the area of the two pole shoes are limited as described above.

[0049] According to another aspect of the present application, a permanent magnet synchronous motor is provided, comprising the motor assembly as described above.

[0050] The present application adds a cut edge 22 structure to the outer circumference of the rotor 2 and increases the thickness of the pole shoe of the stator 1 on one side, so that an uneven air gap structure is formed between the stator and rotor 2, thereby improving the air gap magnetic field waveform of the motor and weakening the uneven air gap caused by the eccentricity of the crankshaft. The sinusoidal distribution of the magnetic resistance of the motor rotor 2 can be formed. By changing the outer circle structure of the rotor 2, the sinusoidal degree of the air gap magnetic resistance can be controlled to obtain the more sinusoidal air gap magnetic density we want, which greatly reduces the torque pulsation of the motor, can effectively improve the noise and vibration problems of the permanent magnet synchronous motor, and mainly solve the electromagnetic noise of the motor during operation.

[0051] In some embodiments, in a cross section of the motor assembly, the area of the first pole shoe 111 is set to S4, the area of the second pole shoe 112 is set to S3, and the area of the cut edge 22 is set to S1, satisfying: Wherein, R3 is the outer peripheral radius of the rotor 2, R4 is the radius of the circle where the crescent-shaped cutting edge 22 is located, a is the angle between two adjacent Q axes; and P is the number of pole pairs of the motor.

[0052] like Figure 3 As shown, the crescent-shaped cutting edge 22 structure forms multiple arcs on the outer circumference of the rotor 2. The outer radius of the rotor 2 is R3, and the radius of the circle where the inner arc line of the crescent-shaped cutting edge 22 is located is R4, satisfying R4>R3; the relationship between the total area of the cutting edge 22, the area of the first pole shoe 111 and the area of the second pole shoe 112 is specifically defined, which can further ensure that the cutting edge 22 can effectively improve the effect of the slot torque.

[0053] In this application, the stator 1 punching sheets and the rotor 2 punching sheets are used correspondingly. The stator 1 can adopt the same punching sheet structure, or the front and back sides can be staggered and stacked. The back side of the stator 1 is a mirror-image sheet structure symmetrical to the front Y axis. At the same time, the rotor 2 can also adopt the same punching sheet structure, and the back side of the rotor 2 is a mirror-image sheet structure symmetrical to the front Y axis. It can also be staggered and stacked. It can be single-piece staggered or multiple-piece staggered. For example: two front pieces and two back pieces are staggered and stacked, or N front pieces and N back pieces are staggered and stacked. The number N of front and back sides must be the same. When the stator and rotor 2 are matched, the number N of stator and rotor 2 staggered and stacked must be the same. In spatial position, the front sides of N stator 1 pieces must correspond to the back sides of N rotor 2 pieces, and the back sides of N stator 1 pieces must correspond to the front sides of N rotor 2 pieces, thereby ensuring the sinusoidality of the air gap magnetic field.

[0054] Theoretical calculations and sample test data show that adding rotor 2 cut edge 22 and thickening pole shoes can significantly reduce the vibration of the motor. Taking the following scheme as an example, the values of R1, R3 and R4 are 26mm, 26mm and 52mm. The prototype motor has been tested and the cogging standard has been significantly reduced after the improvement, which is about 30% or more. Figure 6 As shown in the figure, reducing the cogging torque can significantly reduce the vibration noise of the motor.

[0055] like Figure 7 The no-load back EMF harmonics shown and Figure 8 The no-load air gap flux density test results shown are as follows. After the improvement, the no-load back EMF harmonics have greater advantages than before the improvement, especially the 5th harmonic, and the optimization is more obvious. After the improvement, the no-load air gap flux density has greater advantages than before the improvement in the 2nd, 3rd and 4th harmonics. It can be seen that the improved scheme has more obvious optimization of harmonics than before the improvement. Reducing the harmonic content of the motor can not only reduce the vibration noise of the motor, but also reduce the iron loss content of the motor and improve the efficiency of the motor.

[0056] like Figure 9 and 10 The motor vibration test shown in the figure shows that the total value of vibration acceleration is significantly reduced after the improvement compared with before the improvement, and the peak values of each torque vibration are also significantly reduced. It can be seen that the noise reduction effect after the improvement is significant.

[0057] According to another aspect of the present application, a compressor is provided, comprising the motor assembly as described above or the permanent magnet synchronous motor as described above.

[0058] It is easy for those skilled in the art to understand that the above embodiments can be freely combined and superimposed without conflict.

[0059] The above description is merely a preferred embodiment of the present application and is 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 within the scope of protection of the present application. The above description is merely a preferred embodiment of the present application. It should be noted that those skilled in the art can make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. A motor assembly, characterized in that: include: A stator (1) and a rotor (2), wherein the rotor (2) is inserted into the stator (1); The stator (1) comprises a stator tooth (11), wherein a first pole shoe (111) and a second pole shoe (112) are provided on the stator tooth (11), wherein the first pole shoe (111) is provided on a first side of the stator tooth (11), and the second pole shoe (112) is provided on a second side of the stator tooth (11); in a radial direction along the stator (1), the thickness of the first pole shoe (111) is greater than the thickness of the second pole shoe (112); A circumferentially extending magnetic steel slot (21) is provided in the rotor (2), and a cutting edge (22) is provided on the outer periphery of the rotor (2) corresponding to the magnetic steel slot (21); when the center line of the magnetic steel slot (21) coincides with the radial extension direction of the stator tooth (11), the cutting edge (22) is located on the same side of the outer periphery as the second side.

2. The motor assembly according to claim 1, wherein: In the radial direction of the stator (1), the difference in thickness between the first pole shoe (111) and the second pole shoe (112) ranges from 1.5 to 2.5 mm.

3. The motor assembly according to claim 1 or 2, characterized in that: The first pole shoe (111) comprises a portion having the same thickness as the second pole shoe (112) and a protrusion provided on the shoe surface of the first pole shoe (111).

4. The motor assembly according to claim 1 or 2, characterized in that: A recess is provided on the shoe surface of the second pole shoe (112).

5. The motor assembly according to claim 1 or 2, characterized in that: The cutting edge (22) is located on one side of the center line of the magnetic steel slot (21), and the cutting edge (22) and the outer periphery of the rotor (2) are arranged in a circular arc transition.

6. The motor assembly according to claim 5, characterized in that The cutting edge (22) is configured as a crescent-shaped arc region, or an arc-shaped groove recessed into the outer periphery of the rotor (2).

7. The motor assembly according to claim 1, wherein: On the cross section of the motor assembly, the area of the first pole shoe (111) is set to S4, the area of the second pole shoe (112) is set to S3, and the area of the cut edge (22) is set to S1, satisfying S4-S3≤S1.

8. A permanent magnet synchronous motor, characterized in that: The motor assembly comprises the motor assembly according to any one of claims 1 to 7.

9. The permanent magnet synchronous motor according to claim 8, characterized in that: On the cross section of the motor assembly, the area of the first pole shoe (111) is set to S4, the area of the second pole shoe (112) is set to S3, and the area of the cut edge (22) is set to S1, satisfying: Wherein, R3 is the outer peripheral radius of the rotor (2), R4 is the radius of the circle where the crescent-shaped cutting edge (22) is located, a is the angle between two adjacent Q axes; and P is the number of pole pairs of the motor.

10. A compressor, characterized in that: It comprises the motor assembly according to any one of claims 1 to 7 or the permanent magnet synchronous motor according to any one of claims 8 to 9.

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