Permanent magnet motor, compressor and refrigeration equipment

Abstract

The invention discloses a permanent magnet motor, a compressor and refrigeration equipment, and relates to the technical field of refrigeration equipment, and 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 invention, 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 by adjusting the relationship among the maximum corner distance L1 of the permanent magnet under the same magnetic pole, the outer diameter D of the rotor core and the length L2 of the tooth boot, so that 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] This invention relates to the technical field of refrigeration equipment, and particularly to a permanent magnet motor, compressor and refrigeration equipment. Background Technology

[0002] Permanent magnet motors are widely used in various fields, such as industry, transportation, and home appliances. Among them, permanent magnet synchronous motors have attracted widespread attention due to their advantages such as high efficiency and high power density. In permanent magnet synchronous motors, the magnetic field distribution has a significant impact on motor performance, and studying the magnetic field distribution law of permanent magnet synchronous motors is of great significance for improving motor performance.

[0003] In existing technologies, finite element analysis, analytical methods, and magnetic circuit methods are commonly used to study the magnetic field distribution of permanent magnet synchronous motors (PMSMs). Research shows that the magnetic field distribution of a PMSM is closely related to factors such as the shape of the permanent magnet and the structure of the stator and rotor cores. Among these factors, the shape of the permanent magnet has the most significant impact on the magnetic field distribution. In PMSMs, the permanent magnet is typically rectangular or U-shaped, and different shapes of permanent magnets have different effects on the magnetic field distribution.

[0004] During the manufacturing process of permanent magnet synchronous motors, due to factors such as processing errors and assembly errors, there will inevitably be some unevenness in the gap between the permanent magnet and the rotor core. This will lead to uneven magnetic field distribution in the permanent magnet synchronous motor, thus affecting the motor performance. Summary of the Invention

[0005] The main objective of this invention is to provide a permanent magnet motor, compressor, and refrigeration equipment, which aims to reduce the cogging torque of the permanent magnet motor and improve its torque fluctuation.

[0006] To achieve the above objectives, the present invention proposes a permanent magnet motor comprising:

[0007] An electric motor rotor includes a rotor core and permanent magnets. The rotor core has multiple permanent magnet slots spaced apart along its circumference. The permanent magnets are embedded in the permanent magnet slots so that the rotor core forms multiple magnetic poles. 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 L1. The outer diameter of the rotor core is D.

[0008] A motor stator is fitted around the outer periphery of the motor rotor. The motor stator includes a stator core, which includes a stator yoke and stator teeth. Multiple stator teeth are spaced apart along the inner periphery of the stator yoke. A stator slot is formed between two adjacent stator teeth. Each stator tooth includes 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 the slot of the stator slot. The distance between the two ends of the tooth shoe portion on the side away from the parallel tooth portion is L2.

[0009] Among them, L1, L2 and D satisfy: 2.0≤(L1×L2) / D≤2.6.

[0010] In one implementation, 7 ≤ L1 ≤ 24.

[0011] In one implementation, 7 ≤ L2 ≤ 13.

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

[0013] In one embodiment, the distance between the two opposite sides of the stator slot opening is B, and L2 and B satisfy: 0.24≤B / L2≤0.33.

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

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

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

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

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

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

[0020] In one embodiment, the permanent magnet slot is arc-shaped or straight, and each permanent magnet slot contains one permanent magnet.

[0021] In one embodiment, the permanent magnet slot includes two first slot segments arranged radially symmetrically about the rotor core and extending away from the axis of symmetry in a direction from the axis of the rotor core toward the edge of the rotor core, and each of the two first slot segments is provided with a permanent magnet.

[0022] In one embodiment, the permanent magnet slot further includes a second slot segment, the two ends of which are respectively connected to the ends of the two first slot segments near the rotor core axis, and a permanent magnet is disposed in the second slot segment.

[0023] The present invention also proposes a compressor comprising the aforementioned permanent magnet motor.

[0024] The present invention also proposes a refrigeration device, including the aforementioned compressor.

[0025] The technical solution of the present invention adjusts the relationship between the maximum distance L1 of the corner of the permanent magnet under the same magnetic pole, the outer diameter D of the rotor core and the length L2 of the tooth shoe, so that L1, L2 and D satisfy: 2.0≤(L1×L2) / D≤2.6, so as to balance the magnetic field strength of the permanent magnet motor, reduce the cogging torque of the permanent magnet motor and improve the torque fluctuation of the permanent magnet motor. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a permanent magnet motor according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of another embodiment of the permanent magnet motor provided by the present invention;

[0029] Figure 3 The curve showing the relationship between (L1×L2) / D and the torque fluctuation of the permanent magnet motor;

[0030] Figure 4 The curve showing the relationship between (L1×L2) / D and the cogging torque of the permanent magnet motor;

[0031] Figure 5 The curve showing the relationship between B / L2 and the torque fluctuation of the permanent magnet motor;

[0032] Figure 6 The curve showing the relationship between B / L2 and the cogging torque of the permanent magnet motor is shown.

[0033] Explanation of icon numbers:

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

[0035] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

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

[0038] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0039] This invention proposes a permanent magnet motor 10.

[0040] Please see Figure 1 and Figure 2In one embodiment of the present invention, 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 permanent magnets 120. The rotor core 110 is provided with a plurality of permanent magnet slots 111 spaced apart along its circumference. The permanent magnets 120 are 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 L1. The outer diameter of the rotor core 110 is D. The motor stator 200 is sleeved on the outer periphery of the motor rotor 100 and includes a stator core 210. The stator core 210 includes a stator yoke 211 and stator teeth 212. Multiple stator teeth 212 are spaced 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 shoe 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 shoe portion 2122. Two adjacent tooth shoe portions 2122 form the slot of the stator slot 213. The distance between the two ends of the tooth shoe portion 2122 on the side away from the parallel tooth portion 2121 is L2. Wherein, L1, L2 and D satisfy: 2.0≤(L1×L2) / D≤2.6.

[0041] Specifically, the permanent magnet motor 10 includes a motor rotor 100 and a motor stator 200, with the stator 200 fitted around 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 stacking silicon steel plates. The stator core 210 includes a stator yoke 211 and stator teeth 212. The stator yoke 211 is annular, and multiple stator teeth 212 are spaced circumferentially along the inner side of the stator yoke 211. Stator slots 213 are defined between adjacent stator teeth 212, and 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. The permanent magnets 120 on the motor rotor 100 interact with this rotating magnetic field to generate torque, thereby driving the permanent magnet motor 10 to rotate. The motor rotor 100 includes a rotor core 110 and permanent magnets 120. The permanent magnets 120 can generate a constant magnetic field and interact with the rotating magnetic field to generate torque. The motor rotor 100 can rotate relative to the motor stator 200 to achieve the normal operation of the permanent magnet motor 10. The rotor core 110 is made of high-permeability material or silicon steel laminations, which has high magnetic flux, high structural strength, and is easy to process. The permanent magnets 120 are embedded in the permanent magnet slots 111. When embedding, the permanent magnets 120 under the same magnetic pole are required to have the same polarity in the direction of the outer periphery of the motor rotor 100. At the same time, the permanent magnets 120 of adjacent magnetic poles are required to have opposite magnetism. Multiple magnetic poles are distributed alternately with N poles and S poles in the circumferential direction of the rotor core 110.

[0042] The permanent magnet slot 111 can be straight, arc-shaped, "U"-shaped, "V"-shaped, or "W"-shaped. The straight or arc-shaped permanent magnet slot 111 is embedded with a corresponding straight or arc-shaped permanent magnet 120. The "U"-shaped, "V"-shaped, or "W"-shaped permanent magnet slot 111 is composed of multiple straight or arc-shaped permanent magnets 120.

[0043] Please see Figure 1 For permanent magnets 120 in straight or arc-shaped permanent magnet slots 111, during measurement, vernier calipers can be used to directly clamp the outermost edges of the permanent magnets 120 at both ends of the rotor core 110 in the circumferential direction. The vertical distance between the two outermost edges is the maximum distance L1 between the two far ends of the permanent magnets 120 along the edge of the rotor core 110, which is also the maximum distance between the corners of the permanent magnets 120.

[0044] Please see Figure 2 For permanent magnets 120 in U-shaped, V-shaped or W-shaped permanent magnet slots 111, during measurement, vernier calipers can be used to directly clamp the two ends furthest from the edge of the rotor core 110 and clamp them on the outermost edge of the two ends, so that the maximum distance L1 between the corners of the permanent magnets 120 can be measured.

[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 using measuring tools. For example, the outer jaws of a vernier caliper can be opened and gently clamped on the outer surface of the rotor core 110, and slid along the tangent direction of the outer periphery of the rotor core 110. Multiple measurements at multiple points should be taken to ensure accuracy.

[0046] The parallel tooth portion 2121 is the main body of the stator tooth 212. Its shape is relatively straight and parallel to the radial direction of the stator core 210, primarily used to increase the effective area of ​​the stator winding 220. The tooth shoe portion 2122 is located at the end of the parallel tooth portion 2121. Its shape is generally wider than the parallel tooth portion 2121. The tooth shoe portion 2122 can improve the magnetic field distribution of the permanent magnet motor 10 and reduce eddy current losses, thereby contributing to improved efficiency and performance of the permanent magnet motor 10. The tooth shoe portion 2122 has two opposing sides in the radial direction of the stator core 210. One side connects to the parallel tooth portion 2121, and the other side forms part of the inner circumferential wall of the stator core 210. During measurement, a vernier caliper jaw can be placed at the openings of two adjacent stator slots 213 and clamped at both ends of the tooth shoe portion 2122 on the side away from the parallel tooth portion 2121 to measure the tooth shoe length L2.

[0047] 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. It is caused by the pulsation of the tangential component of the interaction force between the permanent magnet 120 and the stator teeth 212. When the motor rotor 100 rotates, the magnetic permeability changes significantly within a small range corresponding to the slots of the stator teeth 212 on both sides of the permanent magnet 120. (Magnetic permeability formula Λ) m =1 / R m = (μ·A) / L0, where R m The magnetic reluctance (μ is the permeability, and L0 is the linear length of the permanent magnet 120 from the stator core 210) causes a change in the stored magnetic field energy, thereby generating cogging torque. The tooth shoe length L2 and the outer diameter D of the rotor core 110 can affect the change in the linear length L0 of the permanent magnet 120 from the stator core 210, thus affecting the change in permeability, and ultimately affecting the cogging torque and torque fluctuation.

[0048] Cogging torque causes torque fluctuations in the permanent magnet motor 10. These fluctuations also cause vibration and noise in the motor. When the frequency of the torque fluctuation coincides with the armature current resonant frequency, resonance occurs, inevitably amplifying the vibration and noise of the cogging torque. The torque fluctuations originate from the resultant tangential force between the permanent magnet 120 and the stator teeth 212. This 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 tend to be positioned at a certain location. This can be simply understood as the principle that when the magnetic reluctance distribution in the magnetic circuit is uneven, the magnetic lines of force will always close along the magnetic path with the least magnetic reluctance. From an energy perspective, the cogging torque is caused by changes in the magnetic field energy generated by the permanent magnet 120. The maximum distance L1 between the two far ends of the permanent magnet 120 along the edge of the rotor core 110 affects the arrangement of the permanent magnet 120, thereby affecting the magnetic field distribution.

[0049] According to experimental results, by adjusting the relationship between the maximum distance L1 of the corner of the permanent magnet 120 under the same magnetic pole, the outer diameter D of the rotor core 110 and the length L2 of the tooth shoe, so that L1, L2 and D satisfy: 2.0≤(L1×L2) / D≤2.6, the magnetic field strength of the permanent magnet motor 10 can be balanced, the cogging torque of the permanent magnet motor 10 can be reduced, and the torque fluctuation of the permanent magnet motor 10 can be improved.

[0050] Please refer to Table 1 and Figure 3As (L1×L2) / D increases, the torque fluctuation of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 2.0≤(L1×L2) / D≤2.6, the torque fluctuation of the permanent magnet motor 10 is less than 10%, meaning that the change in output torque during operation is less than 10% of the average torque. This lower torque fluctuation reduces vibration and noise during motor operation, resulting in smoother operation. It also reduces internal energy loss, thus improving overall efficiency. Furthermore, the lower torque fluctuation minimizes stress and load variations within the permanent magnet motor, helping to reduce wear on bearings and other mechanical components and extending its service life. The torque fluctuation reaches its lowest point, at only 8%, when (L1×L2) / D=2.3.

[0051] Table 1: Relationship between (L1×L2) / D and torque fluctuation of permanent magnet motor

[0052] <![CDATA[(L1×L2) / 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 (L1×L2) / D increases, the cogging torque of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 2.0≤(L1×L2) / D≤2.6, the cogging torque of the permanent magnet motor 10 is less than 0.37 N*m. That is, when the permanent magnet motor 10 is not energized, the maximum torque fluctuation caused by the uneven magnetic flux density distribution between the motor stator 200 and the motor rotor 100 does not exceed 0.37 N*m. This reduces the impact during the start-up of the permanent magnet motor 10, making the permanent magnet motor 10 run more smoothly, and thus helping to reduce vibration and noise during the operation of the permanent magnet motor 10. At the same time, it also reduces the energy loss inside the permanent magnet motor 10, 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 bearings and other mechanical parts, and extend the service life of the permanent magnet motor 10. Among them, when (L1×L2) / D=2.3, the cogging torque of the permanent magnet motor 10 reaches its minimum, which is only 0.3N*m.

[0054] Table 2: Relationship between (L1×L2) / D and cogging torque of permanent magnet motor

[0055] <![CDATA[(L1×L2) / 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 one implementation, please refer to Figure 1 and Figure 2 The maximum distance between the two far ends of the permanent magnet 120 under a single magnetic pole along the edge side of the rotor core 110 is L1, where 7≤L1≤24.

[0057] When the maximum distance L1 between the two distal ends of the permanent magnet 120 under a single magnetic pole along the edge of the rotor core 110 is large, it increases the cross-sectional area of ​​the magnetic circuit, thereby increasing the magnetic flux. This allows for a more uniform distribution of magnetic flux, reducing abrupt changes in flux density and lowering cogging torque. It also improves flux distribution and reduces torque fluctuations caused by inter-pole interactions. However, if L1 is too large, the number of magnetic poles formed on the rotor core 110 decreases, leading to larger abrupt changes in flux density, increasing cogging torque, and uneven flux distribution, resulting in increased torque fluctuations. When 7 ≤ L1 ≤ 24, a certain amount of magnetic flux can be guaranteed while reducing cogging torque and torque fluctuations. Simultaneously, combined with 2.0 ≤ (L1 × L2) / D ≤ 2.6, the cogging torque of the permanent magnet motor 10 can be effectively reduced, improving its torque fluctuations.

[0058] In one implementation, please refer to Figure 1 and Figure 2 The distance between the two ends of the toothed shoe portion 2122 on the side away from the parallel tooth portion 2121 is L2, where 7≤L2≤13.

[0059] A longer toothed shoe portion 2122 increases the length of the magnetic circuit, thereby increasing magnetic reluctance and reducing magnetic flux; it can better disperse magnetic flux, thus reducing abrupt changes in magnetic flux density and helping to reduce cogging torque; it can improve magnetic flux distribution and reduce torque fluctuations caused by inter-pole interactions. Therefore, when L2≥13, although it can reduce cogging torque and torque fluctuations, it increases magnetic reluctance and reduces magnetic flux. When L2≤7, although it can reduce magnetic reluctance and help increase magnetic flux, it exacerbates the cogging effect, increases cogging torque, and increases torque fluctuations. When 7≤L2≤13, it can ensure a certain magnetic flux while reducing cogging torque and torque fluctuations. At the same time, combined with 2.0≤(L1×L2) / D≤2.6, it can effectively reduce the cogging torque of the permanent magnet motor 10 and improve its torque fluctuations.

[0060] In one implementation, 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 machining of the permanent magnet slots 111 becomes more difficult, and the number and size of the permanent magnets 120 cannot 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 fitted around the motor rotor 100 is also larger, making the permanent magnet motor 10 larger, which is not only detrimental to the lightweight design of the permanent magnet motor 10, but also increases manufacturing costs. At the same time, the outer diameter D of the rotor core 110 can affect the change in the linear length L0 between the permanent magnets 120 and the stator core 210, thus affecting the change in magnetic permeability, and ultimately affecting the cogging torque and torque ripple. By limiting the size of the outer diameter D of the rotor core 110, the magnetic flux distribution of the permanent magnet motor 10 can be optimized, reducing cogging torque and torque ripple, ensuring the performance of the permanent magnet motor 10, while achieving lightweight design and reducing its manufacturing cost.

[0062] In one implementation, please refer to Figure 1 and Figure 2 The distance between the two opposite sides of the slot opening of stator slot 213 is B, and L2 and B satisfy: 0.24≤B / L2≤0.33.

[0063] The length L2 of the tooth shoe and the width B of the slot 213 can affect the change of the linear length L0 of the permanent magnet 120 from the stator core 210, thus affecting the change of magnetic permeability; at the same time, the width B of the slot 213 can also affect the magnetic flux distribution, and the width B of the slot 213 can ultimately affect the tooth cogging torque and torque fluctuation.

[0064] According to experimental results, by adjusting the relationship between the slot width B and the tooth shoe length L2 of the stator slot 213, so that L2 and B satisfy: 0.24≤B / L2≤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 fluctuation of the permanent magnet motor 10 can be improved.

[0065] Please refer to Table 3 and Figure 5As the ratio of B / L2 increases, the torque fluctuation of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 0.24 ≤ B / L2 ≤ 0.33, the torque fluctuation of the permanent magnet motor 10 is less than 15%, meaning that the change in output torque during operation is less than 15% of the average torque. This lower torque fluctuation reduces vibration and noise during motor operation, resulting in smoother operation. It also reduces internal energy loss, thus improving overall efficiency. Furthermore, the lower torque fluctuation minimizes stress and load variations within the motor, helping to reduce wear on bearings and other mechanical components and extending the motor's lifespan. The torque fluctuation reaches its lowest point, at only 14%, when B / L2 = 0.27 and B / L2 = 0.3.

[0066] Table 3: Relationship between B / L2 and torque fluctuation of permanent magnet motor

[0067] <![CDATA[B / L2]]> 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 / L2 increases, the cogging torque of the permanent magnet motor 10 first gradually decreases and then gradually increases. When 0.24 ≤ B / L2 ≤ 0.33, the cogging torque of the permanent magnet motor 10 is below 0.6 N*m. This means that when the permanent magnet motor 10 is not energized, the maximum torque fluctuation caused by the uneven magnetic flux density distribution between the stator 200 and rotor 100 does not exceed 0.6 N*m. This reduces the impact during startup, making the permanent magnet motor 10 run more smoothly and thus helping to reduce vibration and noise during operation. Simultaneously, it reduces internal energy loss, thereby improving the overall efficiency of the permanent magnet motor 10. The lower cogging torque results in smaller stress and load variations within the permanent magnet motor 10, helping to reduce wear on bearings and other mechanical components and extend the service life of the permanent magnet motor 10. Specifically, when B / L2 = 0.27, the cogging torque of the permanent magnet motor 10 reaches its lowest point, at only 0.55 N*m.

[0069] Table 4: Relationship between B / L2 and cogging torque of permanent magnet motor

[0070] <![CDATA[B / L2]]> 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 implementation, please refer to Figure 1 and Figure 2 The distance between the two opposite sides of the slot opening of stator slot 213 is B, where 2.6 ≤ B ≤ 3.5.

[0072] The presence of the slot opening in stator slot 213 is the main cause of cogging torque. It is generally believed that the smaller the width of the slot opening in stator slot 213, the better. However, a slot opening that is too small affects the arrangement of the stator winding 220 and also increases the probability of collision between the winding tip and the stator core 210. When 2.6≤B≤3.5, it can effectively reduce cogging torque and torque fluctuation, and also facilitate the arrangement of the stator winding 220.

[0073] In one implementation, please refer to Figure 1 and Figure 2 Multiple 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, where Q and 2P satisfy: 1 ​​< Q / 2P < 3.

[0074] 2P represents the number of circumferential magnetic poles formed in the rotor core 110, and P represents the number of pole pairs in the motor rotor 100. To reduce tooth harmonic magnetic fields and torque ripple, the number of stator slots 213 and the number of pole pairs are typically optimized. The ratio Q / 2P determines the magnetic field interaction between the motor stator 200 and the motor rotor 100. Different slot ratios affect the fundamental magnetic flux density distribution of the permanent magnet motor 10, thus impacting motor performance. When there is no good match between the two, high tooth harmonics may be generated, leading to 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 magnetic flux density distribution, improving the motor's output capacity and reducing iron losses. When 1 < Q / 2P < 3, there is a good ratio between the number of stator slots 213 and the number of pole pairs, which optimizes the magnetic flux density distribution, reduces losses and torque ripple, thereby reducing the noise of the permanent magnet motor 10 and improving its performance.

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

[0076] A greater number of stator slots 213 can reduce magnetic reluctance and increase magnetic flux, thus improving the efficiency of the permanent magnet motor 10. It can also distribute magnetic flux more evenly, reducing cogging effect and thus reducing cogging torque. Furthermore, it can improve flux distribution and reduce torque ripple caused by inter-pole interaction. However, more slots may require more space, increasing the size or weight of the permanent magnet motor 10, thereby reducing power density and increasing manufacturing costs. When 15 ≤ Q ≤ 18, it is possible to optimize flux distribution, reduce cogging torque and torque ripple, while controlling the size and manufacturing cost of the permanent magnet motor 10.

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

[0078] A larger number of magnetic poles increases the complexity of the magnetic circuit, but also increases the total cross-sectional area of ​​the circuit, which helps increase the magnetic flux. It also helps to better distribute the magnetic flux, reducing abrupt changes in flux density, decreasing cogging effect, and helping to reduce cogging torque. Furthermore, it improves flux distribution and reduces torque ripple caused by inter-pole interaction. However, more slots may require more space, increasing the size or weight of the permanent magnet motor 10, thus reducing power density and increasing manufacturing costs. Moreover, as the number of magnetic poles increases, the synchronous speed of the permanent magnet motor 10 decreases, resulting in a lower maximum speed. When 10 ≤ 2P ≤ 12, it is possible to optimize flux distribution, reduce cogging torque and torque ripple, control the size and manufacturing cost of the permanent magnet motor 10, and ensure the synchronous speed of the permanent magnet motor 10.

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

[0080] By limiting the ratio of the number of stator slots 213 to the number of magnetic poles in the motor rotor 100 to 3 / 2, the size and manufacturing cost of the permanent magnet motor 10 can be controlled while optimizing magnetic flux distribution, reducing cogging torque and torque ripple, and ensuring the synchronous speed of the permanent magnet motor 10. In one embodiment, the number of stator slots 213 is 15, and the number of magnetic poles in the motor rotor 100 is 10. In another embodiment, the number of stator slots 213 is 18, and the number of magnetic poles in 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 installed in each permanent magnet slot 111.

[0083] In one implementation, please refer to Figure 1 The permanent magnet slot 111 is linear, and a linear permanent magnet 120 is 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 in the plane perpendicular to the axial direction of the rotor core 110 is rectangular, and the maximum distance L1 between the two far ends of the permanent magnet 120 under a single magnetic pole along the edge side of the rotor core 110 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 in the plane perpendicular to the axial direction of the rotor core 110 is arc-shaped, and the maximum distance L1 between the two far ends of the permanent magnet 120 under a single magnetic pole along the edge side of the rotor core 110 is the chord length of this arc segment.

[0085] In another implementation, please refer to Figure 2 The permanent magnet slot 111 is V-shaped, and two straight permanent magnets 120 are embedded in the V-shaped permanent magnet slot 111. The two permanent magnets 120 are V-shaped and correspond to the permanent magnet slot 111.

[0086] In another embodiment, the permanent magnet slot 111 is U-shaped, and two straight permanent magnets 120 and one arc-shaped permanent magnet 120 are embedded within the U-shaped slot 111, so that the three permanent magnets 120 correspond to the U-shape of the slot 111. Alternatively, the permanent magnet slot 111 can be inverted trapezoidal, with three straight permanent magnets 120 embedded within it, also forming an inverted trapezoidal shape. In other embodiments, the permanent magnet slot 111 can also be W-shaped or other irregular shapes, with multiple permanent magnets 120 embedded within it.

[0087] For an embodiment in which multiple permanent magnets 120 are provided in the permanent magnet slot 111, without loss of generality, the distance between the two outermost sides of the two permanent magnets 120 that are furthest apart under the same magnetic pole, distributed along the circumference of the rotor core 110 at the end closest to the edge of the rotor core 110, is the maximum distance L1 between the two far ends of the permanent magnets 120 under a single magnetic pole along the edge side of the rotor core 110.

[0088] In one implementation, please refer to Figure 2 The permanent magnet slot 111 includes two first slot segments 111a, which are radially symmetrical about the rotor core 110 and extend away from the axis of symmetry in the direction of the axis of the rotor core 110 toward the edge of the rotor core 110. Each of the two first slot segments 111a contains a permanent magnet 120.

[0089] The permanent magnet slot 111 includes two first slot segments 111a, that is, the permanent magnet slot 111 is roughly "V" shaped, and the two permanent magnets 120 embedded therein are also roughly "V" shaped, thereby optimizing the magnetic flux path, reducing unnecessary magnetic flux leakage, and using magnetic reluctance torque to generate greater starting torque and continuous torque, further enhancing the performance of the permanent magnet motor 10.

[0090] In one embodiment, the permanent magnet slot 111 includes a second slot section, the two ends of which are respectively connected to the ends of the two first slot sections 111a near the axis of the rotor core 110, and a permanent magnet 120 is provided in the second slot section.

[0091] The second slot segment can be straight or curved, so that the permanent magnet slot 111 is roughly inverted trapezoidal in shape. By setting multiple slot segments, the arrangement of permanent magnets 120 under multiple magnetic poles is optimized, thereby optimizing the magnetic flux path, reducing unnecessary magnetic flux leakage, and using reluctance torque to generate greater starting torque and continuous torque, further enhancing the performance of the permanent magnet motor 10.

[0092] The present invention also proposes a compressor, which includes a permanent magnet motor 10. The specific structure of the permanent magnet motor 10 is as described in the above embodiments. Since the compressor in the technical solution of the present invention adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0093] This invention also proposes a refrigeration device, which includes a compressor. The specific structure of the compressor is as described in the above embodiments. Refrigeration devices can be classified into compression refrigeration devices, absorption refrigeration devices, vapor jet refrigeration devices, heat pump refrigeration devices, and electric heating refrigeration devices, etc. Refrigeration devices mainly consist of a compressor, expansion valve, evaporator, condenser, accessories, and piping. Examples include refrigerators and air conditioners. Since the compressor in this invention adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated further here.

[0094] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A permanent magnet motor, characterized in that, include: An electric motor rotor includes a rotor core and permanent magnets. The rotor core has multiple permanent magnet slots spaced apart along its circumference. The permanent magnets are embedded in the permanent magnet slots so that the rotor core forms multiple magnetic poles. 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 L1. The outer diameter of the rotor core is D. A motor stator is fitted around the outer periphery of the motor rotor. The motor stator includes a stator core, which includes a stator yoke and stator teeth. Multiple stator teeth are spaced apart along the inner periphery of the stator yoke. A stator slot is formed between two adjacent stator teeth. Each stator tooth includes 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 the slot of the stator slot. The distance between the two ends of the tooth shoe portion on the side 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 as described in claim 1, characterized in that, 7≤L1≤24； And / or, 7≤L2≤13; And / or, 45≤D≤62.

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

33.

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

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

9. The permanent magnet motor as described in claim 1, characterized in that, The number of permanent magnets in each permanent magnet slot is Z, where 1 ≤ Z ≤ 3.

10. The permanent magnet motor as described in claim 9, characterized in that, The permanent magnet slot is arc-shaped or straight, and each permanent magnet slot contains one permanent magnet.

11. The permanent magnet motor as described in claim 9, characterized in that, The permanent magnet slot includes two first slot segments, which are radially symmetrical about the rotor core and extend away from the axis of symmetry in a direction from the axis of the rotor core toward the edge of the rotor core. Each of the two first slot segments is provided with a permanent magnet.

12. The permanent magnet motor as described in claim 11, characterized in that, The permanent magnet slot also includes a second slot section, the two ends of which are respectively connected to the ends of the two first slot sections near the rotor core axis, and a permanent magnet is provided in the second slot section.

13. A compressor, characterized in that, Includes the permanent magnet motor as described in any one of claims 1 to 12.

14. A refrigeration device, characterized in that, Includes the compressor as described in claim 13.

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