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, the permanent magnet motor comprises a motor rotor and a motor stator, the motor rotor comprises a rotor iron core and a permanent magnet, and the thickness of the permanent magnet is t; the periphery of the motor rotor is sleeved with the motor stator, the motor stator comprises a stator iron core and a stator winding, the stator winding is wound in stator grooves, the number of the stator grooves is Q, and the number of winding turns on each stator tooth is N; the width of the parallel tooth parts in the circumferential direction of the stator core is T; the wiring coefficient of the permanent magnet motor is K. According to the technical scheme provided by the invention, by adjusting the relationship among the number N of windings of the permanent magnet motor, the number Q of the stator slots, the width T of the parallel tooth parts of the stator teeth and the thickness t of the permanent magnet, (N * Q) / (K * t) is more than or equal to 850 and less than or equal to 950, and t / T is more than or equal to 0.25 and less than or equal to 0.33, so that the permanent magnet motor can have better demagnetization resistance and reduce the coercive force demand while the production cost is controlled.

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 (PMMs) possess advantages such as high efficiency, high power density, and low noise, and have been widely used in various fields. However, the magnetic field of PMMs is susceptible to external interference, such as temperature and electromagnetic fields, which can lead to a decrease in the magnetism of the permanent magnets and a reduction in their resistance to demagnetization, thereby affecting the performance and lifespan of the PMM. Therefore, improving the demagnetization resistance and reducing the coercivity requirements of PMMs are both hot topics and challenges in PMM research.

[0003] Methods to improve the demagnetization resistance of permanent magnets mainly include increasing the magnet thickness, using high-coercivity permanent magnet materials, and employing special permanent magnet structures. However, these methods have some drawbacks. For example, increasing the magnet thickness increases the size and weight of the permanent magnet motor, using high-coercivity permanent magnet materials increases costs, and using special permanent magnet structures increases manufacturing difficulty. In short, all existing methods for improving the demagnetization resistance of permanent magnets ultimately increase production costs. Summary of the Invention

[0004] The main objective of this invention is to provide a permanent magnet motor, compressor, and refrigeration equipment, which aims to control production costs while improving the demagnetization resistance of the permanent magnet motor and reducing the coercivity requirements.

[0005] To achieve the above objectives, the present invention proposes a permanent magnet motor comprising:

[0006] An electric motor rotor includes a rotor core and permanent magnets. The rotor core has multiple permanent magnet slots spaced apart along its circumference, and the permanent magnets are embedded in the permanent magnet slots. The thickness of the permanent magnets is t.

[0007] A motor stator is fitted around the outer periphery of the motor rotor. The motor stator includes a stator core and a stator winding. The stator core 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. The number of stator slots is Q. The stator winding is wound on the stator teeth, and the number of turns on each stator tooth is N. The stator teeth include 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. The width of the parallel tooth portion in the circumferential direction of the stator core is T.

[0008] The permanent magnet motor is a three-phase permanent magnet motor, and the connection coefficient of the permanent magnet motor is K;

[0009] Among them, 850≤(N×Q) / (K×t)≤950, and 0.25≤t / T≤0.33.

[0010] In one implementation, 8.5 ≤ Q / t ≤ 11.5.

[0011] In one embodiment, 1mm ≤ t ≤ 2.5mm.

[0012] In one embodiment, a plurality of permanent magnets form 2P magnetic poles in the circumferential direction of the rotor core, where 1 < Q / 2P < 3.

[0013] In one implementation, 15 ≤ Q ≤ 18.

[0014] In one implementation, 10 ≤ 2P ≤ 12.

[0015] In one implementation, Q / 2P = 3 / 2.

[0016] In one implementation, 50 ≤ N ≤ 140.

[0017] In one embodiment, 4.5mm ≤ T ≤ 12mm.

[0018] In one embodiment, the stator winding is connected in a delta configuration, and the connection coefficient K = 1.

[0019] In one embodiment, the stator winding is connected in a star configuration, and the connection coefficient K = 1.732.

[0020] The present invention also proposes a compressor comprising the aforementioned permanent magnet motor.

[0021] The present invention also proposes a refrigeration device, including the aforementioned compressor.

[0022] The technical solution of this invention adjusts the relationship between the number of winding turns N, the number of stator slots Q, the width T of the parallel teeth of the stator teeth, and the thickness t of the permanent magnet in the permanent magnet motor, so that N, Q, T, and t satisfy: 850≤(N×Q) / (K×t)≤950, and 0.25≤t / T≤0.33. Thus, while controlling production costs, the permanent magnet motor can have better anti-demagnetization ability and reduce the coercivity requirement. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is a schematic diagram of a permanent magnet motor according to an embodiment of the present invention;

[0025] Figure 2 The curve showing the relationship between (N×Q) / (K×t) and demagnetizing current;

[0026] Figure 3 The curve showing the relationship between t / T and demagnetizing current;

[0027] Figure 4 The curves showing the relationship between (N×Q) / (K×t) and t / T and the demagnetizing current are shown.

[0028] Figure 5 The curve showing the relationship between Q / t and demagnetizing current;

[0029] Figure 6 The curve showing the relationship between Q / t and magnet cost;

[0030] Figure 7 This is a schematic diagram of the structure of a permanent magnet motor when the stator windings are connected in a delta series.

[0031] Figure 8 This is a schematic diagram of the structure of a permanent magnet motor when the stator windings are connected in a star configuration.

[0032] Explanation of icon numbers:

[0033] 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.

[0034] 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

[0035] 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.

[0036] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators 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 indicators will also change accordingly.

[0037] 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.

[0038] This invention proposes a permanent magnet motor 10.

[0039] Please see Figure 1 In 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 a permanent magnet 120. The rotor core 110 is provided with a plurality of permanent magnet slots 111 spaced apart along its circumference, and the permanent magnet 120 is embedded in the permanent magnet slots 111. The thickness of the permanent magnet 120 is t. 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. The stator core 210 includes a stator yoke 211 and stator teeth 212. A plurality of stator teeth 212 are spaced apart along the inner periphery of the stator yoke 211. Two adjacent stator teeth are spaced apart. Stator slots 213 are formed between the sub-teeth 212, and the number of stator slots 213 is Q. The stator winding 220 is wound on the stator teeth 212, and the number of turns of the winding on each stator tooth 212 is N. 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. The width of the parallel tooth portion 2121 in the circumferential direction of the stator core 210 is T. The permanent magnet motor 10 is a three-phase permanent magnet motor 10, and the connection coefficient of the permanent magnet motor 10 is K. Among them, 850≤(N×Q) / (K×t)≤950, and 0.25≤t / T≤0.33.

[0040] 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 permeability, 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. 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.

[0041] The permanent magnet 120 has two sides extending axially along the rotor core 110, and the distance between the two sides is the thickness t of the permanent magnet 120. The thickness of the permanent magnet 120 can be measured using a vernier caliper, micrometer, ultrasonic thickness gauge, etc. For example, the permanent magnet 120 can be placed between the two jaws of a vernier caliper, so that the two jaws grip the two sides of the permanent magnet 120 along the axial direction of the rotor core 110, to read the measurement. To ensure measurement accuracy, the vernier caliper can be gently slid along the axial direction of the rotor core 110, and multiple measurements can be taken at multiple points.

[0042] A thicker permanent magnet 120 produces a smaller demagnetizing magnetic field, which partially cancels out the magnetization, thus better resisting demagnetization caused by external magnetic fields. A thicker permanent magnet 120 also better dissipates heat, slowing the rate of temperature rise and allowing it to maintain magnetism at higher temperatures without demagnetizing. Therefore, increasing the thickness of the permanent magnet 120 significantly improves its resistance to demagnetization. However, increasing the thickness of the permanent magnet 120 also increases cost and weight.

[0043] The number of winding turns N on each stator tooth 212 and the number of stator slots 213 Q can be directly observed. The number of winding turns N, the number of stator slots 213 Q, and the width T of the parallel tooth portion 2121 do not directly affect the demagnetization resistance of the permanent magnet 120, but rather affect other performance parameters of the permanent magnet motor 10, which in turn indirectly affect the demagnetization resistance of the permanent magnet 120.

[0044] As the number of turns N increases, the inductive reactance of the stator winding 220 increases. Therefore, at the same frequency and current, the reactance of the permanent magnet motor 10 increases, thereby reducing the current flowing through the stator winding 220. This reduces losses in the stator winding 220 and decreases heat accumulation inside the permanent magnet motor 10, helping to protect the permanent magnet 120 so it can maintain its magnetism at higher temperatures without demagnetizing. Simultaneously, the increased magnetic field strength under the same current allows the permanent magnet motor 10 to generate a stronger magnetic force, resulting in greater torque at the same current. However, when the number of turns N increases to a certain range, the unit magnetic flux of the permanent magnet motor 10 decreases, and its resistance to demagnetization also decreases.

[0045] The number Q of stator slots 213 indirectly affects the demagnetization resistance of the permanent magnet 120 by influencing factors such as cogging torque, magnetic circuit saturation, leakage flux, and thermal management of the permanent magnet motor 10. The number Q of stator slots 213 affects the cogging torque of the permanent magnet motor 10, leading to vibration and noise. More stator slots 213 can reduce the magnetic flux density per slot, thereby reducing the degree of magnetic circuit saturation and helping to maintain the magnetic properties of the permanent magnet motor 10, thus indirectly improving the demagnetization resistance of the permanent magnet 120. More stator slots 213 generally mean lower leakage flux, which helps to improve the efficiency of the permanent magnet motor 10 and reduce heat generation, thus indirectly benefiting the demagnetization resistance of the permanent magnet 120. More stator slots 213 can increase the heat dissipation area, helping to improve the heat dissipation efficiency of the permanent magnet motor 10 and helping to maintain the operating temperature of the permanent magnet 120 within a safe range, thus indirectly enhancing the demagnetization resistance.

[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. Adjacent tooth shoe portions 2122 form the slot opening of the stator slot 213.

[0047] The width T of the parallel teeth 2121 in the circumferential direction of the stator core 210, which is also the distance between two adjacent stator slots 213, can be measured using vernier calipers, micrometers, etc. For example, the two jaws of the vernier caliper can be placed between two adjacent stator slots 213, with the two jaws gripping the sidewalls of the two adjacent slots, to read the measurement. Alternatively, the maximum and minimum values ​​of the parallel teeth 2121 can be measured by sliding the vernier caliper along the length direction of the parallel teeth 2121 (radial direction of the stator core 210), and the average value can be taken.

[0048] A wider parallel tooth portion 2121 helps reduce cogging torque, magnetic circuit saturation, and leakage flux, thereby helping to maintain the magnetic properties of the permanent magnet motor 10 and indirectly improving the demagnetization resistance of the permanent magnet 120. However, a wider parallel tooth portion 2121 means a reduction in the number and area of ​​stator slots 213, which is not conducive to increasing the number of winding turns. At the same time, the slot fill factor of the permanent magnet motor 10 is also reduced, which is not conducive to improving the performance of the permanent magnet motor 10.

[0049] According to experimental results, by adjusting the relationship between the number of winding turns N, the number of stator slots 213 Q, the width T of the parallel tooth portion 2121 of the stator tooth 212, and the thickness t of the permanent magnet 120 of the permanent magnet motor 10, N, Q, T, and t can satisfy: 850≤(N×Q) / (K×t)≤950, and 0.25≤t / T≤0.33. Thus, while controlling production costs, the permanent magnet motor 10 can have better anti-demagnetization ability and reduce the coercivity requirement.

[0050] Please refer to Table 1 and Figure 2 As (N×Q) / (K×t) increases, the demagnetizing current of the permanent magnet motor 10 decreases. When (N×Q) / (K×t)≤950, the demagnetizing current of the permanent magnet motor 10 is higher than 22A, and the permanent magnet motor 10 has good anti-demagnetizing ability.

[0051] Please refer to Table 2 and Figure 3As t / T increases, the demagnetizing current of the permanent magnet motor 10 also increases. When t / T ≥ 0.25, the demagnetizing current of the permanent magnet motor 10 is higher than 22A, indicating that the permanent magnet motor 10 has good anti-demagnetizing capability. However, as t / T increases, the thickness of the permanent magnet 120 also increases, leading to a higher cost for the permanent magnet 120.

[0052] Please refer to Figure 4 As the demagnetizing current increases, the demagnetizing resistance of the permanent magnet motor 10 is enhanced. However, since t / T increases accordingly, the thickness of the permanent magnet 120 increases, thus increasing the production cost of the permanent magnet 120. Simultaneously, (N×Q) / (K×t) decreases under the influence of t. Therefore, when 850≤(N×Q) / (K×t)≤950 and 0.25≤t / T≤0.33, the demagnetizing resistance can be improved while effectively controlling production costs. Understandably, coercivity is an inherent property of the permanent magnet 120; a better-performing permanent magnet 120 naturally has greater coercivity, but this also comes with higher costs. Therefore, the technical solution of the present invention improves the anti-demagnetization capability by adjusting the relationship between the number of winding turns N of the permanent magnet motor 10, the number of stator slots 213 Q, the width T of the parallel tooth portion 2121 of the stator tooth 212 and the thickness t of the permanent magnet 120, thereby reducing the requirements on the performance of the permanent magnet 120 itself, reducing the coercivity requirement, and thus reducing the cost.

[0053] Table 1: Relationship between (N×Q) / (K×t) and demagnetizing current of permanent magnet motor

[0054] (N×Q) / (K×t) 700 750 800 850 900 950 1000 1050 1100 Demagnetizing current / A 48 40 34 30 26 22 18 12 6

[0055] Table 2: Relationship between t / T and demagnetizing current of permanent magnet motor

[0056] t / T 0.18 0.20 0.22 0.25 0.29 0.33 0.40 0.50 0.67 Demagnetizing current / A 4 11 17 22 26 30 35 41 48

[0057] In one embodiment, the number of stator slots 213 is Q, the thickness of the permanent magnet 120 is t, and 8.5≤Q / t≤11.5.

[0058] The number of stator slots 213, Q, determines the number of tooth slots in the permanent magnet motor 10, which affects the cogging torque, magnetic circuit saturation, leakage flux, and thermal management of the motor. The thickness t of the permanent magnet 120 directly affects its demagnetization resistance, thermal stability, and the overall size and cost of the permanent magnet motor 10. A higher Q / t ratio means more stator slots 213 relative to a thinner permanent magnet 120 thickness.

[0059] Please refer to Table 3. Figure 5 and Figure 6As the Q / t ratio increases, the demagnetizing current of the permanent magnet motor 10 decreases, and the cost of the permanent magnet 120 decreases accordingly. When Q / t ≥ 11.5, the demagnetizing current has decreased to below 22A, and the rate of decrease is greater, but the cost of the permanent magnet 120 can be controlled below 6.3 yuan. When Q / t ≤ 8.5, although the demagnetizing current of the permanent magnet motor 10 reaches above 42A, the cost of the permanent magnet 120 also increases to above 14.7 yuan. Therefore, based on satisfying 850 ≤ (N×Q) / (K×t) ≤ 950 and 0.25 ≤ t / T ≤ 0.33, by further adjusting the relationship between the number of stator slots 213 Q of the permanent magnet motor 10 and the thickness t of the permanent magnet 120, so that Q and t satisfy: 8.5 ≤ Q / t ≤ 11.5, production costs can be effectively controlled, while improving the demagnetizing resistance of the permanent magnet motor 10 and reducing the coercivity requirement.

[0060] Table 3: Relationship between Q / t and demagnetizing current of permanent magnet motor and cost of permanent magnet.

[0061] Q / t 6.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5 Demagnetizing current / A 50 46 42 39 36 22 12 5 Permanent magnet cost 17.8 16.5 14.7 12.6 8.4 6.3 4.8 3.2

[0062] In one embodiment, the thickness of the permanent magnet 120 is t, where 1 mm ≤ t ≤ 2.5 mm.

[0063] When t ≤ 1 mm, the permanent magnet 120 is too thin, resulting in low demagnetization resistance and an excessive number of stator slots 213 (Q). This reduces the area of ​​each slot and decreases the slot fill factor, negatively impacting the overall performance of the permanent magnet motor 10. When t ≥ 2.5 mm, the permanent magnet 120 is too thick, increasing its cost and reducing the number of stator slots 213 (Q). This negatively impacts the reduction of cogging torque, magnetic circuit saturation, and leakage flux, further hindering the overall performance improvement of the permanent magnet motor 10. When 1 mm ≤ t ≤ 2.5 mm, the thickness of the permanent magnet 120 is optimal. This balance helps reduce cogging torque, magnetic circuit saturation, leakage flux, and control the cost of the permanent magnet 120, while ensuring the number and area of ​​stator slots 213. This indirectly improves the demagnetization resistance of the permanent magnet 120 and the performance of the permanent magnet motor 10.

[0064] In one embodiment, a plurality of permanent magnets 120 form 2P magnetic poles in the circumferential direction of the rotor core 110, where 1 < Q / 2P < 3.

[0065] 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. Different ratios of Q / 2P can have different effects on the waveform quality of the back EMF and torque ripple, thus significantly impacting the back EMF characteristics and energy efficiency of the permanent magnet motor 10. Therefore, to reduce tooth harmonic magnetic fields and torque ripple, the number of stator slots 213 and the number of pole pairs are usually optimized. The Q / 2P ratio 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, thereby affecting the motor's performance. When there is no good match between the two, high tooth harmonics may be generated, leading to additional losses and torque ripples, thus 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, improves the symmetry of the magnetic circuit, reduces cogging torque, and helps to better utilize magnetic flux, thereby improving demagnetization resistance. 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 magnetic flux density distribution, reduce losses and torque fluctuations, thereby improving the anti-demagnetization capability, reducing the noise of the permanent magnet motor 10, and improving the performance of the permanent magnet motor 10.

[0066] In one embodiment, the number of stator slots 213 is Q, where 15 ≤ Q ≤ 18.

[0067] 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 the waveform quality of the back EMF, making it closer to an ideal sinusoidal waveform. It can also improve magnetic flux distribution, reducing torque ripple caused by inter-pole interaction and improving demagnetization resistance. However, a larger number of 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 magnetic flux distribution, improve the waveform quality of the back EMF, reduce cogging torque and torque ripple, and improve demagnetization resistance while controlling the size and manufacturing cost of the permanent magnet motor 10.

[0068] 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.

[0069] 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 can better distribute the magnetic flux, thus reducing abrupt changes in flux density, reducing cogging effect, and helping to reduce cogging torque. It can improve the waveform quality of the back EMF, making it closer to an ideal sinusoidal waveform. It can improve the magnetic flux distribution, reduce torque ripple caused by inter-pole interaction, and improve demagnetization resistance. However, a larger number of poles may require more space, increasing the size or weight of the permanent magnet motor 10, thereby reducing power density. A larger number of poles also increases production costs. When 10 ≤ 2P ≤ 12, it is possible to optimize the magnetic flux distribution, improve the waveform quality of the back EMF, reduce cogging torque and torque ripple, and improve demagnetization resistance while controlling the size and manufacturing cost of the permanent magnet motor 10.

[0070] In one implementation, Q / 2P = 3 / 2.

[0071] 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, improving the waveform quality of back EMF, reducing cogging torque and torque ripple, and improving demagnetization resistance. 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.

[0072] In one implementation, 50 ≤ N ≤ 140.

[0073] A larger number of turns N increases the back electromotive force (EMF) and winding resistance, thereby reducing the current of the permanent magnet motor 10 at a given voltage. This helps reduce copper losses and improve the efficiency of the permanent magnet motor 10. However, when the number of turns N increases to a certain value, the unit magnetic flux of the permanent magnet motor 10 decreases, and its demagnetization resistance also decreases. When 50 ≤ N ≤ 140, the back EMF of the permanent magnet motor 10 can be increased, improving its energy efficiency while ensuring its demagnetization resistance.

[0074] In one embodiment, the width of the parallel tooth portion 2121 in the circumferential direction of the stator core 210 is T, where 4.5 mm ≤ T ≤ 12 mm.

[0075] When T ≤ 4.5 mm, an excessively narrow parallel tooth portion 2121 may increase the saturation of the magnetic circuit, leakage flux, and cogging torque. This not only hinders the improvement of the permanent magnet 120's demagnetization resistance but also leads to increased vibration and noise during operation of the permanent magnet motor 10, reducing its efficiency. When T ≥ 12 mm, an excessively wide parallel tooth portion 2121 reduces the number and area of ​​stator slots 213, which is detrimental to increasing the number of winding turns. Simultaneously, the slot fill factor of the permanent magnet motor 10 also decreases, thus negatively impacting its performance. When 4.5 mm ≤ T ≤ 12 mm, this balance helps reduce cogging torque, magnetic circuit saturation, and leakage flux while ensuring the number and area of ​​stator slots 213, thereby indirectly improving the demagnetization resistance of the permanent magnet 120 and the performance of the permanent magnet motor 10.

[0076] In one implementation, please refer to Figure 7 The stator winding 220 is connected in a delta configuration with a connection factor K = 1.

[0077] The permanent magnet motor 10 is configured as a three-phase permanent magnet motor 10. Different connection methods of the three-phase windings have different effects on the connection voltage and current. The connection factor K is a coefficient used to describe the influence of the three-phase winding connection method on the connection voltage and current. Delta connection is a common three-phase winding connection method, in which the ends of the three windings are connected in sequence to form a closed loop, and the beginning of each winding serves as the power supply connection point. When the delta connection method is used, the phase voltage equals the line voltage, and the delta connection method has almost no effect on the connection voltage, so the value of the connection factor K is 1.

[0078] In one implementation, please refer to Figure 8 The stator winding 220 is connected in a star configuration with a connection factor K = 1.732.

[0079] Star connection is another common three-phase winding connection method, in which one end of the three windings is connected together to form a common point (called the neutral point), while the other end of each winding serves as the power supply connection point. When using a star connection, the phase current equals the line current, but the phase voltage is not equal to the line voltage. Therefore, in a star connection, due to the unequal relationship between phase voltage and line voltage, the line voltage is 1.732 times the phase voltage. The connection factor K is set to 1.732 to eliminate the influence of the star connection on the connection voltage, ensuring the accuracy of the experimental results.

[0080] 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.

[0081] 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.

[0082] 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, and the permanent magnets are embedded in the permanent magnet slots. The thickness of the permanent magnets is t. A motor stator is fitted around the outer periphery of the motor rotor. The motor stator includes a stator core and a stator winding. The stator core includes a stator yoke and stator teeth. Multiple stator teeth are spaced apart along the inner periphery of the stator yoke, and stator slots are formed between adjacent stator teeth. The number of stator slots is Q. The stator winding is wound on the stator teeth, and the number of turns on each stator tooth is N. The stator teeth include parallel tooth portions and tooth shoe portions. One end of the parallel tooth portion is connected to the stator yoke, and the other end is connected to the tooth shoe portion. The width of the parallel tooth portion in the circumferential direction of the stator core is T. The permanent magnet motor is a three-phase permanent magnet motor, and the connection coefficient of the permanent magnet motor is K; Among them, 850≤(N×Q) / (K×t)≤950, and 0.25≤t / T≤0.

33.

2. The permanent magnet motor as described in claim 1, characterized in that, 8.5≤Q / t≤11.

5.

3. The permanent magnet motor as described in claim 2, characterized in that, 1mm≤t≤2.5mm.

4. 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, where 1 < Q / 2P < 3.

5. The permanent magnet motor as described in claim 4, characterized in that, 15≤Q≤18。 6. The permanent magnet motor as described in claim 4, characterized in that, 10≤2P≤12。 7. The permanent magnet motor as described in claim 4, characterized in that, Q / 2P = 3 / 2.

8. The permanent magnet motor as described in claim 1, characterized in that, 50≤N≤140； And / or, 4.5mm≤T≤12mm.

9. The permanent magnet motor according to any one of claims 1 to 8, characterized in that, The stator winding is connected in a delta configuration, and the connection coefficient K = 1.

10. The permanent magnet motor according to any one of claims 1 to 8, characterized in that, The stator winding is connected in a star configuration, and the connection coefficient K = 1.

732.

11. A compressor, characterized in that, Includes the permanent magnet motor as described in any one of claims 1 to 10.

12. A refrigeration device, characterized in that, Includes the compressor as described in claim 11.

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