Permanent magnet motor, compressor and refrigeration equipment

Abstract

The utility model discloses a permanent magnet motor, a compressor and refrigeration equipment, and relates to the technical field of refrigeration equipment, the maximum distance between two far ends of a permanent magnet under a single magnetic pole of the permanent magnet motor along the edge side of a rotor core is L1; the outer diameter of the rotor core is D; the distance between the two ends of the side, away from the parallel tooth part, of the tooth shoe part is L2, and L1, L2 and D meet the condition that (L1 * L2) / D is larger than or equal to 2.0 and smaller than or equal to 2.6. According to the technical scheme provided by the utility model, the relationship among the maximum distance L1 of the corners of the permanent magnets under the same magnetic pole, the outer diameter D of the rotor core and the length L2 of the tooth boots is adjusted, so that L1, L2 and D meet the condition that (L1 * L2) / D is more than or equal to 2.0 and less than or equal to 2.6, the magnetic field intensity of the permanent magnet motor is balanced, the cogging torque of the permanent magnet motor is reduced, and the torque ripple of the permanent magnet motor is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of refrigeration equipment, and particularly relates to a permanent magnet motor, a compressor and a refrigeration equipment. Background Art

[0002] Permanent magnet motors are widely used in various fields, such as industry, transportation, household appliances, etc. Among them, permanent magnet synchronous motors have received extensive attention due to their advantages such as high efficiency and high power density. In a permanent magnet synchronous motor, the magnetic field distribution has an important influence on the motor performance. Studying the magnetic field distribution law of a permanent magnet synchronous motor is of great significance for improving the motor performance.

[0003] In the prior art, methods such as magnetic field finite element analysis method, analytical method, magnetic circuit method, etc. are often used to study the magnetic field distribution law of permanent magnet synchronous motors. Research shows that the magnetic field distribution of a permanent magnet synchronous motor is closely related to factors such as the shape of the permanent magnet and the stator and rotor core structures. Among them, the shape of the permanent magnet has the most significant influence on the magnetic field distribution. In a permanent magnet synchronous motor, the shape of the permanent magnet is usually rectangular or U-shaped, etc., and different shapes of permanent magnets have different influences on the magnetic field distribution.

[0004] During the manufacturing process of a permanent magnet synchronous motor, due to the existence of factors such as machining errors and assembly errors, there is inevitably a certain degree of non-uniformity in the gap between the permanent magnet and the rotor core, which will lead to non-uniform magnetic field distribution of the permanent magnet synchronous motor, thereby affecting the motor performance. Summary of the Utility Model

[0005] The main object of the utility model is to propose a permanent magnet motor, a compressor and a refrigeration equipment, aiming to reduce the cogging torque of the permanent magnet motor and improve its torque ripple.

[0006] To achieve the above object, the permanent magnet motor proposed by the utility model includes:

[0007] A motor rotor, including a rotor core and a permanent magnet, wherein the rotor core is provided with a plurality of permanent magnet slots at intervals along its circumference, and the permanent magnet is embedded in the permanent magnet slots so that the rotor core forms a plurality of magnetic poles, and the maximum distance between the two distal ends of the permanent magnet under a single magnetic pole along the edge side of the rotor core is L 1 ; the outer diameter of the rotor core is D;

[0008] The motor stator is sleeved on the outer periphery of the motor rotor. The motor stator includes a stator core, and the stator core includes a stator yoke and stator teeth. A plurality of the stator teeth are arranged at intervals along the inner circumference of the stator yoke. A stator slot is formed between two adjacent stator teeth. The stator tooth includes a parallel tooth portion and a tooth boot portion. One end of the parallel tooth portion is connected to the stator yoke, and the other end is connected to the tooth boot portion. The slot opening of the stator slot is formed between two adjacent tooth boot portions. The distance between the two ends on the side of the tooth boot portion away from the parallel tooth portion is L 2 ;

[0009] wherein, L 1 , L 2 and D satisfy: 2.0 ≤ (L 1 ×L 2 ) / D ≤ 2.6.

[0010] In one embodiment, 7 ≤ L 1 ≤ 24.

[0011] In one embodiment, 7 ≤ L 2 ≤ 13.

[0012] In one embodiment, 45 ≤ D ≤ 62.

[0013] In one embodiment, the distance between the two opposite side edges of the slot opening of the stator slot is B, and L 2 and B satisfy: 0.24 ≤ B / L 2 ≤ 0.33.

[0014] In one embodiment, 2.6 ≤ B ≤ 3.5.

[0015] In one embodiment, a plurality of the permanent magnets form 2P magnetic poles in the circumferential direction of the rotor core, and the number of the stator slots is Q. Q and 2P satisfy: 1 < Q / 2P < 3.

[0016] In one embodiment, 15 ≤ Q ≤ 18.

[0017] In one embodiment, 10 ≤ 2P ≤ 12.

[0018] In one embodiment, Q / 2P = 3 / 2.

[0019] In one embodiment, the number of the permanent magnets in each permanent magnet slot is Z, and 1 ≤ Z ≤ 3.

[0020] In one embodiment, the permanent magnet slot is arc-shaped or linear, and one permanent magnet is arranged in each permanent magnet slot.

[0021] In one embodiment, the permanent magnet slot includes two first slot segments, which are symmetrically arranged with respect to the radial direction of the rotor core and extend away from the symmetry axis in the direction from the axis of the rotor core towards the edge of the rotor core. Each of the two first slot segments is provided with one permanent magnet.

[0022] In one embodiment, the permanent magnet slot further includes a second slot segment. The two ends of the second slot segment are respectively communicated with one ends of the two first slot segments close to the axis of the rotor core, and one permanent magnet is provided in the second slot segment.

[0023] The present utility model further provides a compressor, including the aforementioned permanent magnet motor.

[0024] The present utility model further provides a refrigeration device, including the aforementioned compressor.

[0025] The technical solution of the present utility model balances the magnetic field strength of the permanent magnet motor, reduces the cogging torque of the permanent magnet motor, and improves the torque ripple of the permanent magnet motor by adjusting the relationship among the maximum distance L between the corners of the permanent magnets under the same magnetic pole 1 , the outer diameter D of the rotor core, and the tooth tip length L 2 , such that L 1 , L 2 and D satisfy: 2.0 ≤ (L 1 × L 2 ) / D ≤ 2.6. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model, and those of ordinary skill in the art can obtain other drawings based on the structures shown in these drawings without creative efforts.

[0027] Figure 1 It is a schematic structural diagram of an embodiment of the permanent magnet motor provided by the present utility model;

[0028] Figure 2 It is a schematic structural diagram of another embodiment of the permanent magnet motor provided by the present utility model;

[0029] Figure 3 It is a curve showing the relationship between (L 1 × L 2 ) / D and the torque ripple of the permanent magnet motor;

[0030] Figure 4 It is a curve showing the relationship between (L 1 × L 2) / D vs. cogging torque relationship curve of permanent magnet motor;

[0031] Figure 5 is B / L 2 vs. torque ripple relationship curve of permanent magnet motor;

[0032] Figure 6 is B / L 2 vs. cogging torque relationship curve of permanent magnet motor.

[0033] Explanation of the reference numerals in the attached drawings:

[0034] 10. Permanent magnet motor; 100. Motor rotor; 200. Motor stator; 110. Rotor core; 111. Permanent magnet slot; 111a. First slot section; 120. Permanent magnet; 210. Stator core; 211. Stator yoke; 212. Stator teeth; 2121. Parallel tooth part; 2122. Tooth boot part; 213. Stator slot; 220. Stator winding.

[0035] The realization, functional features and advantages of the purpose of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0037] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) in the embodiments of the present utility model, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0038] In addition, if the embodiments of the present utility model involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0039] The present utility model provides a permanent magnet motor 10.

[0040] Please refer to Figure 1 and Figure 2 , in an embodiment of the present utility model, the permanent magnet motor 10 includes a motor rotor 100 and a motor stator 200. The motor rotor 100 includes a rotor core 110 and a permanent magnet 120. The rotor core 110 is provided with a plurality of permanent magnet slots 111 at intervals along its circumference. The permanent magnet 120 is embedded in the permanent magnet slots 111 so that the rotor core 110 forms a plurality of magnetic poles. The maximum distance between the two distal ends of the permanent magnet 120 under a single magnetic pole along the edge side of the rotor core 110 is L 1 ; the outer diameter of the rotor core 110 is D; the motor stator 200 is sleeved on the outer circumference of the motor rotor 100. The motor stator 200 includes a stator core 210. The stator core 210 includes a stator yoke 211 and stator teeth 212. A plurality of stator teeth 212 are arranged at intervals along the inner circumference of the stator yoke 211. A stator slot 213 is formed between two adjacent stator teeth 212. The stator teeth 212 include a parallel tooth portion 2121 and a tooth boot portion 2122. One end of the parallel tooth portion 2121 is connected to the stator yoke 211, and the other end is connected to the tooth boot portion 2122. The distance between the two ends of the tooth boot portion 2122 on the side away from the parallel tooth portion 2121 is L 2 ; where L 1 、L 2 and D satisfy: 2.0 ≤ (L 1 ×L 2 ) / D ≤ 2.6.

[0041] Specifically, the permanent magnet motor 10 includes a motor rotor 100 and a motor stator 200. The motor stator 200 is sleeved on the outer periphery of the motor rotor 100. The motor stator 200 includes a stator core 210 and a stator winding 220 for generating a rotating magnetic field. The stator core 210 is formed by laminating silicon steel sheets. The stator core 210 includes a stator yoke 211 and stator teeth 212. The stator yoke 211 is annular, and a plurality of stator teeth 212 are arranged at intervals along the circumferential direction of the stator yoke 211 on the inner side of the stator yoke 211. A stator slot 213 is defined between adjacent stator teeth 212. The number of stator slots 213 is the same as the number of stator teeth 212. The stator winding 220 passes through the stator slots 213 and is directly wound around the stator teeth 212. When three-phase alternating current is applied to the stator winding 220, a rotating magnetic field is generated, and the permanent magnet 120 on the motor rotor 100 interacts with the rotating magnetic field to generate a torque, thereby driving the permanent magnet motor 10 to rotate. The motor rotor 100 includes a rotor core 110 and a permanent magnet 120. The permanent magnet 120 can generate a constant magnetic field and interact with the rotating magnetic field to generate a torque. The motor rotor 100 can rotate relative to the motor stator 200 to realize the normal operation of the permanent magnet motor 10. The rotor core 110 is made of a high-permeability material or laminated silicon steel sheets, has a high magnetic flux rate, and has high structural strength, which is convenient for processing. The permanent magnet 120 is embedded in the permanent magnet slot 111. When embedding, it is required that the permanent magnets 120 under the same magnetic pole face the same polarity in the direction of the outer periphery of the motor rotor 100, and at the same time, it is required that the magnetic properties of the permanent magnets 120 of adjacent magnetic poles are opposite. A plurality of magnetic poles are alternately distributed in the circumferential direction of the rotor core 110 according to N poles and S poles.

[0042] The permanent magnet slot 111 can be linear, arc-shaped, "U"-shaped, "V"-shaped or "W"-shaped. Among them, a corresponding linear or arc-shaped permanent magnet 120 is embedded in the linear or arc-shaped permanent magnet slot 111; the "U"-shaped, "V"-shaped or "W"-shaped permanent magnet slots 111 are formed by combining and embedding a plurality of linear or arc-shaped permanent magnets 120.

[0043] Please refer to Figure 1 , for the permanent magnet 120 in the linear or arc-shaped permanent magnet slot 111, when measuring, a vernier caliper can be selected to directly clamp the outermost edges of both ends of the permanent magnet 120 in the circumferential direction of the rotor core 110. The vertical distance between the two outermost edges is the maximum distance L between the two distal ends of the permanent magnet 120 along the edge side of the rotor core 110 1 , that is, the maximum distance of the corners of the permanent magnet 120.

[0044] Please refer to Figure 2For the permanent magnet 120 in the permanent magnet slot 111 in the shape of "U", "V" or "W", during measurement, a vernier caliper can be selected to directly clamp the two end parts with the farthest distance close to the edge side of the rotor core 110, and clamp on the outermost edges of the two end parts, so that the maximum distance L of the corners of the permanent magnet 120 can be measured 1 。

[0045] The outer diameter D of the rotor core 110 is the diameter of the outer periphery of the rotor core 110, which can be directly measured by a measuring tool. For example, open the outer jaws of a vernier caliper and gently clamp the outer surface of the rotor core 110, and slide along the tangent direction of the outer periphery of the rotor core 110, and measure multiple points at multiple times to ensure accuracy

[0046] The parallel tooth part 2121 is the main part of the stator tooth 212, its shape is relatively straight, parallel to the radial direction of the stator core 210, and is mainly used to increase the effective area of the stator winding 220. The tooth tip part 2122 is located at the end of the parallel tooth part 2121, and its shape is usually wider than that of the parallel tooth part 2121. The tooth tip part 2122 can improve the magnetic field distribution of the permanent magnet motor 10, reduce the eddy current loss, and thus help to improve the efficiency and performance of the permanent magnet motor 10. The tooth tip part 2122 has two opposite side surfaces in the radial direction of the stator core 210, one side surface is connected to the parallel tooth part 2121, and the other side surface forms part of the inner peripheral wall of the stator core 210. During measurement, the jaws of a vernier caliper can be placed at the openings of two adjacent stator slots 213, and clamped at both ends of the side of the tooth tip part 2122 away from the parallel tooth part 2121, so as to measure the tooth tip length L 2 。

[0047] The cogging torque is the torque generated by the interaction between the permanent magnet 120 and the stator core 210 when the winding of the permanent magnet motor 10 is not energized, and is caused by the pulsation of the tangential component of the interaction force between the permanent magnet 120 and the stator tooth 212. When the motor rotor 100 rotates, the magnetic conductance changes greatly within a small range of the stator tooth 212 slots corresponding to both sides of the permanent magnet 120. The magnetic conductance (magnetic conductance formula Λ m =1 / R m =(μ·A) / L 0 ,where R m is the magnetic resistance, μ is the magnetic permeability, and L 0 is the straight-line length of the permanent magnet 120 from the stator core 210) causes the magnetic field energy storage to change, thereby generating the cogging torque. The tooth tip length L 2 and the outer diameter D of the rotor core 110 can affect the change of the straight-line length L 0 of the permanent magnet 120 from the stator core 210, so it can affect the change of the magnetic conductance, and finally affect the cogging torque and torque ripple

[0048] Cogging torque can cause torque ripple in the permanent magnet motor 10. Torque ripple can also cause the motor to vibrate and generate noise. When the frequency of torque ripple is consistent with the resonance frequency of the armature current, resonance will occur, which will inevitably amplify the vibration and noise of the cogging torque. Torque ripple is generated from the resultant tangential force between the permanent magnet 120 and the stator teeth 212. The tangential force always attempts to align the magnetic field axis of the permanent magnet 120 with the axis of the stator teeth 212, thus causing the rotor to have a tendency to be positioned at a certain position. It can also be simply understood that when the magnetic reluctance distribution of the magnetic circuit is uneven, the magnetic lines of force will always close along the magnetic circuit with the least magnetic reluctance, that is, the "principle of the least magnetic reluctance of the magnetic circuit". From an energy perspective, cogging torque is caused by the change in magnetic field energy generated by the permanent magnet 120, and the maximum distance L between the two far ends of the permanent magnet 120 along the edge side of the rotor core 110 for each magnetic pole 1 will affect the arrangement of the permanent magnet 120, and thus affect the magnetic field distribution.

[0049] According to the verification of experimental results, by adjusting the maximum distance L between the corners of the permanent magnet 120 under the same magnetic pole 1 , the outer diameter D of the rotor core 110, and the tooth tip length L 2 relationship, such that L 1 , L 2 and D satisfy: 2.0 ≤ (L 1 × L 2 ) / D ≤ 2.6, the magnetic field intensity of the permanent magnet motor 10 can be balanced, the cogging torque of the permanent magnet motor 10 can be reduced, and the torque ripple of the permanent magnet motor 10 can be improved.

[0050] Please refer to Table 1 and Figure 3 , as (L 1 × L 2 ) / D increases, the torque ripple of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 2.0 ≤ (L 1 × L 2 ) / D ≤ 2.6, the torque ripple of the permanent magnet motor 10 is lower than 10%, that is, the change range of the output torque of the permanent magnet motor 10 during operation is less than 10% of the average torque. Thus, the permanent magnet motor 10 reduces the vibration and noise during motor operation with a lower torque ripple, making the permanent magnet motor 10 operate more smoothly; reduces the energy loss inside the permanent magnet motor 10, thereby improving the overall efficiency of the permanent magnet motor 10; at the same time, the lower torque ripple makes the stress and load changes inside the permanent magnet motor 10 smaller, which helps to reduce the wear of bearings and other mechanical components and extend the service life of the permanent magnet motor 10. Among them, when (L 1 × L 2 ) / D = 2.3, the torque ripple of the permanent magnet motor 10 reaches the lowest, only 8%.

[0051] Table 1: (L 1 × L2 ) / D and Torque Ripple Relationship Table of Permanent Magnet Motor

[0052] <![CDATA[(L 1 ×L 2 ) / D]]> 1.4 1.7 2 2.3 2.6 2.9 3.2 Torque ripple 18％ 12％ 9％ 8％ 9％ 13％ 20％

[0053] Please refer to Table 2 and Figure 4 , as (L 1 ×L 2 ) / D increases, the cogging torque of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 2.0 ≤ (L 1 ×L 2 ) / D ≤ 2.6, the cogging torque of the permanent magnet motor 10 is lower than 0.37 N*m. That is, when the permanent magnet motor 10 is not energized, the maximum value of the torque ripple generated due to the uneven distribution of the magnetic flux density between the motor stator 200 and the motor rotor 100 does not exceed 0.37 N*m. Thus, the impact during the start-up of the permanent magnet motor 10 can be reduced, making the operation of the permanent magnet motor 10 more stable, and further helping to reduce the vibration and noise during the operation of the permanent magnet motor 10. At the same time, the energy loss inside the permanent magnet motor 10 is also reduced, thereby improving the overall efficiency of the permanent magnet motor 10. The lower cogging torque results in smaller stress and load changes inside the permanent magnet motor 10, which helps to reduce the wear of the bearings and other mechanical components and extend the service life of the permanent magnet motor 10. Among them, when (L 1 ×L 2 ) / D = 2.3, the cogging torque of the permanent magnet motor 10 reaches the lowest, only 0.3 N*m.

[0054] Table 2: (L 1 ×L 2 ) / D and Cogging Torque Relationship Table of Permanent Magnet Motor

[0055] <![CDATA[(L 1 ×L 2 ) / D]]> 1.4 1.7 2 2.3 2.6 2.9 3.2 Cogging torque / N*m 0.69 0.45 0.36 0.3 0.37 0.52 0.81

[0056] In an embodiment, please refer to Figure 1 and Figure 2 , the maximum distance L between the two distal ends of the permanent magnet 120 under a single magnetic pole along the edge side of the rotor core 110 1 , 7 ≤ L 1 ≤ 24.

[0057] When the maximum distance L between the two distal ends of the permanent magnet 120 under a single magnetic pole along the edge side of the rotor core 110 1 is relatively large, it will increase the cross-sectional area of the magnetic circuit, thereby increasing the magnetic flux; it can evenly distribute the magnetic flux, thereby reducing the sudden change of the magnetic flux density and reducing the cogging torque; it can improve the magnetic flux distribution and reduce the torque ripple caused by the interaction between magnetic poles. However, L 1When it is too large, the number of magnetic poles formed on the rotor core 110 decreases, which will instead cause a large mutation in the magnetic flux density, increase the cogging torque, and the magnetic flux distribution is uneven, resulting in an increase in torque ripple. When 7 ≤ L 1 ≤ 24, it can not only ensure a certain magnetic flux, but also reduce the cogging torque and torque ripple. At the same time, combined with 2.0 ≤ (L 1 × L 2 ) / D ≤ 2.6, the cogging torque of the permanent magnet motor 10 can be effectively reduced, and its torque ripple can be improved.

[0058] In an embodiment, please refer to Figure 1 and Figure 2 , the distance between the two ends on the side of the tooth boot part 2122 far from the parallel tooth part 2121 is L 2 , 7 ≤ L 2 ≤ 13.

[0059] A longer tooth boot part 2122 will increase the length of the magnetic circuit, thereby increasing the magnetic resistance and reducing the magnetic flux; it can better disperse the magnetic flux, thereby reducing the mutation of the magnetic flux density, which helps to reduce the cogging torque; it can improve the magnetic flux distribution and reduce the torque ripple caused by the interaction between magnetic poles. Therefore, when L 2 ≥ 13, although the cogging torque can be reduced and the torque ripple can be reduced, the magnetic resistance will be increased and the magnetic flux will be reduced. When L 2 ≤ 7, although the magnetic resistance can be reduced, which helps to increase the magnetic flux, the cogging effect will be aggravated, the cogging torque will be increased, and the torque ripple will be increased. When 7 ≤ L 2 ≤ 13, it can not only ensure a certain magnetic flux, but also reduce the cogging torque and torque ripple. At the same time, combined with 2.0 ≤ (L 1 × L 2 ) / D ≤ 2.6, the cogging torque of the permanent magnet motor 10 can be effectively reduced, and its torque ripple can be improved.

[0060] In an embodiment, please refer to Figure 1 and Figure 2 , 45 ≤ D ≤ 62.

[0061] If the outer diameter D of the rotor core 110 is too small, the processing difficulty of the permanent magnet slot 111 is relatively large, and the quantity and size of the set permanent magnets 120 are difficult to meet the requirements, thus affecting the performance of the permanent magnet motor 10; if the outer diameter D of the rotor core 110 is too large, the size of the motor stator 200 sleeved on the outer periphery of the motor rotor 100 is also larger, making the size of the permanent magnet motor 10 larger, which is not only not conducive to the light weight of the permanent magnet motor 10, but also increases the manufacturing cost. At the same time, the outer diameter D of the rotor core 110 can affect the straight-line length L 0The change can thus affect the change in magnetic conductance, ultimately affecting the cogging torque and torque ripple. By restricting the size of the outer diameter D of the rotor core 110, the magnetic flux distribution of the permanent magnet motor 10 is optimized, achieving the light weight of the permanent magnet motor 10 and reducing its manufacturing cost while reducing the cogging torque and torque ripple and ensuring the performance of the permanent magnet motor 10.

[0062] In one embodiment, please refer to Figure 1 and Figure 2 , the distance between the two opposite sides of the notch of the stator slot 213 is B, and L 2 and B satisfy: 0.24 ≤ B / L 2 ≤ 0.33.

[0063] The tooth tip length L 2 and the width B of the notch of the stator slot 213 can affect the straight-line length L 0 of the permanent magnet 120 from the stator core 210, so the change can affect the change in magnetic conductance; at the same time, the width B of the notch of the stator slot 213 can also affect the magnetic flux distribution, and the width B of the notch of the stator slot 213 can ultimately affect the cogging torque and torque ripple.

[0064] According to the verification of experimental results, by adjusting the relationship between the width B of the notch of the stator slot 213 and the tooth tip length L 2 such that L 2 and B satisfy: 0.24 ≤ B / L 2 ≤ 0.33, the magnetic field strength of the permanent magnet motor 10 can be optimized, the cogging torque of the permanent magnet motor 10 can be reduced, and the torque ripple of the permanent magnet motor 10 can be improved.

[0065] Please refer to Table 3 and Figure 5 , as B / L 2 increases, the torque ripple of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 0.24 ≤ B / L 2 ≤ 0.33, the torque ripple of the permanent magnet motor 10 is less than 15%, that is, the change amplitude of the output torque during the operation of the permanent magnet motor 10 is less than 15% of the average torque. Thus, the permanent magnet motor 10 reduces the vibration and noise during the operation of the motor with a lower torque ripple, making the permanent magnet motor 10 operate more smoothly; reducing the energy loss inside the permanent magnet motor 10, thereby improving the overall efficiency of the permanent magnet motor 10; at the same time, the lower torque ripple makes the stress and load change inside the permanent magnet motor 10 smaller, helping to reduce the wear of bearings and other mechanical components and extending the service life of the permanent magnet motor 10. Among them, when B / L 2 = 0.27 and B / L 2 = 0.3, the torque ripple of the permanent magnet motor 10 reaches the lowest, only 14%.

[0066] Table 3: B / L2 Table of relationship with torque ripple of permanent magnet motor

[0067] <![CDATA[B / L 2 > 0.18 0.21 0.24 0.27 0.3 0.33 0.36 0.39 Torque ripple 22％ 17％ 15％ 14％ 14％ 15％ 18％ 20％

[0068] Please refer to Table 4 and Figure 6 , as B / L 2 increases, the cogging torque of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 0.24 ≤ B / L 2 ≤ 0.33, the cogging torque of the permanent magnet motor 10 is lower than 0.6 N*m. That is, when the permanent magnet motor 10 is not powered on, the maximum value of the torque ripple generated due to the uneven distribution of the magnetic flux density between the motor stator 200 and the motor rotor 100 does not exceed 0.6 N*m. Thus, the impact during the startup of the permanent magnet motor 10 can be reduced, making the operation of the permanent magnet motor 10 more stable, and further helping to reduce the vibration and noise during the operation of the permanent magnet motor 10. At the same time, the energy loss inside the permanent magnet motor 10 is also reduced, thereby improving the overall efficiency of the permanent magnet motor 10. The lower cogging torque results in smaller stress and load changes inside the permanent magnet motor 10, helping to reduce the wear of bearings and other mechanical components and extending the service life of the permanent magnet motor 10. Among them, when B / L 2 = 0.27, the cogging torque of the permanent magnet motor 10 reaches the lowest, only 0.55 N*m.

[0069] Table 4: Table of relationship between B / L 2 and cogging torque of permanent magnet motor

[0070] <![CDATA[B / L 2 > 0.18 0.21 0.24 0.27 0.3 0.33 0.36 0.39 Cogging torque / N*m 0.81 0.72 0.6 0.55 0.56 0.58 0.66 0.73

[0071] In one embodiment, please refer to Figure 1 and Figure 2 , the distance between the two opposite sides of the notch of the stator slot 213 is B, and 2.6 ≤ B ≤ 3.5.

[0072] The existence of the notch of the stator slot 213 is the main cause of cogging torque. Generally, it is considered that the smaller the width of the notch of the stator slot 213, the better. However, too small a notch affects the arrangement of the stator winding 220 and also increases the probability of collision between the winding mouth and the stator core 210. When 2.6 ≤ B ≤ 3.5, it can effectively reduce the cogging torque and torque ripple and is also convenient for the arrangement of the stator winding 220.

[0073] In one embodiment, please refer to Figure 1 and Figure 2 , a plurality of permanent magnets 120 form 2P magnetic poles in the circumferential direction of the rotor core 110, and the number of stator slots 213 is Q, and Q and 2P satisfy: 1 < Q / 2P < 3.

[0074] 2P is the number of magnetic poles formed in the circumferential direction of the rotor core 110, and P is the number of pole pairs of the motor rotor 100. To reduce the tooth harmonic magnetic field and torque ripple, the number of stator slots 213 and the number of pole pairs are usually optimized. The ratio of Q / 2P determines the magnetic field interaction between the motor stator 200 and the motor rotor 100. Different slot ratios will affect the fundamental flux density distribution of the permanent magnet motor 10, and thus affect the performance of the motor. When there is no good match between the two, higher tooth harmonics may be generated, resulting in additional losses and torque ripple, thereby affecting the efficiency and noise level of the permanent magnet motor 10. A suitable slot ratio helps to obtain a more uniform flux density distribution to improve the output capacity of the motor and reduce iron loss. When 1 < Q / 2P < 3, there is a good ratio between the number of stator slots 213 and the number of pole pairs, which can optimize the flux density distribution, reduce losses and torque ripple, thereby reducing the noise of the permanent magnet motor 10 and improving the performance of the permanent magnet motor 10.

[0075] In one embodiment, the number of stator slots 213 is Q, and 15 ≤ Q ≤ 18.

[0076] A larger number of stator slots 213 can reduce the reluctance, increase the magnetic flux, and help improve the efficiency of the permanent magnet motor 10; it can evenly distribute the magnetic flux, reduce the cogging effect, and help reduce the cogging torque; it can improve the magnetic flux distribution and reduce the torque ripple caused by the interaction between magnetic poles. However, at the same time, it may require more space due to the larger number of slots, thus increasing the volume or weight of the permanent magnet motor 10, further reducing the power density, and increasing the manufacturing cost. When 15 ≤ Q ≤ 18, it is possible to control the volume and manufacturing cost of the permanent magnet motor 10 while optimizing the magnetic flux distribution, reducing the cogging torque and torque ripple.

[0077] In one embodiment, a plurality of permanent magnets 120 form 2P magnetic poles in the circumferential direction of the rotor core 110, and 10 ≤ 2P ≤ 12.

[0078] A larger number of magnetic poles can increase the complexity of the magnetic circuit, but at the same time increase the total cross-sectional area of the magnetic circuit, which helps to increase the magnetic flux; it can better disperse the magnetic flux, thereby reducing the sudden change of the magnetic flux density, reducing the cogging effect, and helping to reduce the cogging torque; it can improve the magnetic flux distribution and reduce the torque ripple caused by the interaction between magnetic poles. However, at the same time, it may require more space due to the larger number of slots, thus increasing the volume or weight of the permanent magnet motor 10, further reducing the power density, and increasing the manufacturing cost. Moreover, as the number of magnetic poles increases, the synchronous speed of the permanent magnet motor 10 will decrease, resulting in a lower maximum speed of the permanent magnet motor 10. When 10 ≤ 2P ≤ 12, it is possible to control the volume and manufacturing cost of the permanent magnet motor 10 while optimizing the magnetic flux distribution, reducing the cogging torque and torque ripple, and ensuring the synchronous speed of the permanent magnet motor 10.

[0079] In one embodiment, Q / 2P = 3 / 2.

[0080] By defining the ratio of the number of stator slots 213 to the number of magnetic poles of the motor rotor 100 as 3 / 2, while optimizing the magnetic flux distribution, reducing the cogging torque and torque ripple, the volume and manufacturing cost of the permanent magnet motor 10 can be controlled, and the synchronous speed of the permanent magnet motor 10 can be ensured. In one embodiment, the number of stator slots 213 is 15, and the number of magnetic poles of the motor rotor 100 is 10. In another embodiment, the number of stator slots 213 is 18, and the number of magnetic poles of the motor rotor 100 is 12.

[0081] In one embodiment, the number of permanent magnets 120 in each permanent magnet slot 111 is Z, where 1 ≤ Z ≤ 3.

[0082] At least one permanent magnet 120 can be arranged in each permanent magnet slot 111.

[0083] In one embodiment, referring to Figure 1 , the permanent magnet slot 111 is linear, and a linear permanent magnet 120 is correspondingly embedded in the linear permanent magnet slot 111. For the linear permanent magnet 120, without loss of generality, the cross-section of the permanent magnet 120 intercepted by the plane perpendicular to the axial direction of the rotor core 110 is rectangular, and the maximum distance L 1 between the two far ends along the edge side of the rotor core 110 under a single magnetic pole is the length of the rectangle.

[0084] Of course, the permanent magnet slot 111 can also be arc-shaped, and an arc-shaped permanent magnet 120 is correspondingly embedded in the arc-shaped permanent magnet slot 111. For the arc-shaped permanent magnet 120, without loss of generality, the cross-section of the permanent magnet 120 intercepted by the plane perpendicular to the axial direction of the rotor core 110 is arc-shaped, and the maximum distance L 1 between the two far ends along the edge side of the rotor core 110 under a single magnetic pole is the chord length of the arc segment.

[0085] In another embodiment, referring to Figure 2 , the permanent magnet slot 111 is "V"-shaped, and two linear permanent magnets 120 are embedded in the "V"-shaped permanent magnet slot 111, and the two permanent magnets 120 correspond to the "V" shape of the permanent magnet slot 111.

[0086] In yet another embodiment, the permanent magnet slot 111 is in a "U" shape. Two linear permanent magnets 120 and one arc-shaped permanent magnet 120 are embedded in the "U"-shaped permanent magnet slot 111, such that the three permanent magnets 120 correspond to the "U" shape of the permanent magnet slot 111. Of course, the permanent magnet slot 111 can be in an inverted trapezoid shape, and three linear permanent magnets 120 are embedded in the inverted trapezoid-shaped permanent magnet slot 111, such that the three permanent magnets 120 correspond to the inverted trapezoid shape of the permanent magnet slot 111. In other embodiments, the permanent magnet slot 111 can also be in a "W" shape or other special shapes, and multiple permanent magnets 120 are embedded therein.

[0087] For the embodiments in which multiple permanent magnets 120 are arranged in the permanent magnet slot 111, without loss of generality, for the two permanent magnets 120 that are farthest apart under the same magnetic pole at one end close to the edge of the rotor core 110, the distance between the outermost two sides in the circumferential direction of the rotor core 110 is the maximum distance L between the two distal ends of the permanent magnet 120 along the edge side of the rotor core 110 under a single magnetic pole. 1 。

[0088] In one embodiment, referring to Figure 2 , the permanent magnet slot 111 includes two first slot segments 111a, which are symmetrically arranged with respect to the radial direction of the rotor core 110 and extend away from the axis of symmetry in the direction from the axis of the rotor core 110 towards the edge of the rotor core 110. One permanent magnet 120 is arranged in each of the two first slot segments 111a.

[0089] The permanent magnet slot 111 includes two first slot segments 111a, that is, the permanent magnet slot 111 is generally in a "V" shape, and the two permanent magnets 120 embedded therein are also generally in a "V" shape, so as to optimize the magnetic flux path, reduce unnecessary magnetic flux leakage, and generate a larger starting torque and continuous torque using reluctance torque, further enhancing the performance of the permanent magnet motor 10.

[0090] In one embodiment, the permanent magnet slot 111 further includes a second slot segment, and both ends of the second slot segment are respectively connected to the ends of the two first slot segments 111a close to the axis of the rotor core 110. One permanent magnet 120 is arranged in the second slot segment.

[0091] The second slot segment can be linear or arc-shaped, so that the permanent magnet slot 111 is generally in an inverted trapezoid shape. By arranging multiple slot segments in the permanent magnet slot 111, the arrangement of the permanent magnets 120 under multiple magnetic poles is optimized, thereby optimizing the magnetic flux path, reducing unnecessary magnetic flux leakage, and generating a larger starting torque and continuous torque using reluctance torque, further enhancing the performance of the permanent magnet motor 10.

[0092] The present utility model also provides a compressor, which includes a permanent magnet motor 10. The specific structure of the permanent magnet motor 10 refers to the above-mentioned embodiments. Since the compressor in the technical solution of the present utility model adopts all the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be elaborated herein one by one.

[0093] The present utility model also provides a refrigeration device, which includes a compressor. The specific structure of the compressor refers to the above-mentioned embodiments. Refrigeration devices can be divided into compression refrigeration devices, absorption refrigeration devices, steam jet refrigeration devices, heat pump refrigeration devices, electro-thermal refrigeration devices, etc. The refrigeration device mainly consists of a compressor, an expansion valve, an evaporator, a condenser and accessories, pipelines. Such as refrigerators, air conditioners, etc. Since the compressor in the technical solution of the present utility model adopts all the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be elaborated herein one by one.

[0094] The above is only an exemplary embodiment of the present utility model, and does not limit the patent scope of the present utility model. Any equivalent structural transformation made under the technical concept of the present utility model by using the content of the specification and drawings of the present utility model, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present utility model.

Claims

1. A permanent magnet motor, characterized in that: include: A motor rotor comprises a rotor core and permanent magnets, wherein the rotor core is provided with a plurality of permanent magnet slots spaced apart along its circumference, the permanent magnets are embedded in the permanent magnet slots, so that the rotor core forms a plurality of magnetic poles, and the maximum distance between two distal ends of the permanent magnet under a single magnetic pole along the edge side of the rotor core is L1; the outer diameter of the rotor core is D; A motor stator, sleeved on the outer circumference of the motor rotor, the motor stator comprises a stator core, the stator core comprises a stator yoke and stator teeth, a plurality of stator teeth are arranged at intervals along the inner circumference of the stator yoke, a stator slot is formed between two adjacent stator teeth, the stator teeth comprise a parallel tooth portion and a tooth shoe portion, one end of the parallel tooth portion is connected to the stator yoke, and the other end is connected to the tooth shoe portion, two adjacent tooth shoe portions form a notch of the stator slot, and the distance between the two ends of the tooth shoe portion away from the parallel tooth portion is L2; Among them, L1, L2 and D satisfy: 2.0≤(L1×L2) / D≤2.

6.

2. The permanent magnet motor according to claim 1, characterized in that: 7≤L1≤24； and / or, 7≤L2≤13; And / or, 45≤D≤62.

3. The permanent magnet motor according to claim 1, characterized in that: The distance between the two opposite sides of the slot opening of the stator slot is B, and L2 and B satisfy: 0.24≤B / L2≤0.

33.

4. The permanent magnet motor according to claim 3, characterized in that: 2.6≤B≤3.5。 5. The permanent magnet motor according to claim 1, characterized in that: The plurality of permanent magnets form 2P magnetic poles in the circumferential direction of the rotor core, the number of the stator slots is Q, and Q and 2P satisfy: 1<Q / 2P<3.

6. The permanent magnet motor according to claim 5, characterized in that: 15≤Q≤18。 7. The permanent magnet motor according to claim 5, characterized in that: 10≤2P≤12。 8. The permanent magnet motor according to claim 5, characterized in that: Q / 2P=3 / 2.

9. The permanent magnet motor according to claim 1, characterized in that: The number of the permanent magnets in each permanent magnet slot is Z, 1≤Z≤3.

10. The permanent magnet motor according to claim 9, characterized in that: The permanent magnet slots are arc-shaped or straight-line-shaped, and one permanent magnet is arranged in each of the permanent magnet slots.

11. The permanent magnet motor according to claim 9, characterized in that: The permanent magnet slot includes two first slot segments, which are symmetrically arranged with respect to the radial direction of the rotor core and extend away from the symmetry axis in the direction of the axis of the rotor core toward the edge of the rotor core, and each of the two first slot segments is provided with one permanent magnet.

12. The permanent magnet motor according to claim 11, characterized in that: The permanent magnet slot also includes a second slot segment, both ends of which are respectively connected to one end of the two first slot segments close to the axis of the rotor core, and a permanent magnet is arranged in the second slot segment.

13. A compressor, characterized in that: It comprises a permanent magnet motor as claimed in any one of claims 1 to 12.

14. A refrigeration device, characterized in that: Comprising the compressor of claim 13.

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