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 refrigeration equipment technology field, 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 utility model, 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 coercive force requirements while the production cost is controlled.

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 have the advantages of high efficiency, high power density, low noise, etc., and have been widely used in various fields. However, the magnetic field of permanent magnet motors is easily affected by external interference, such as temperature, electromagnetic field, etc., resulting in a decrease in the magnetism of permanent magnets and a reduction in the demagnetization resistance, thus affecting the performance and service life of permanent magnet motors. Therefore, how to improve the demagnetization resistance of permanent magnet motors and reduce the coercivity requirement is a hot and difficult issue in the research of permanent magnet motors.

[0003] The methods to improve the demagnetization resistance of permanent magnets mainly include increasing the thickness of permanent magnets, using permanent magnet materials with high coercivity, using special permanent magnet structures, etc. However, these methods have some disadvantages. For example, increasing the thickness of permanent magnets will increase the volume and weight of permanent magnet motors, using permanent magnet materials with high coercivity will increase the cost, and using special permanent magnet structures will increase the manufacturing difficulty, etc. In short, these existing methods to improve the demagnetization resistance of permanent magnets will ultimately increase the production cost. Summary of the Utility Model

[0004] The main purpose of the utility model is to propose a permanent magnet motor, a compressor and a refrigeration equipment, aiming to improve the demagnetization resistance of the permanent magnet motor and reduce the coercivity requirement while controlling the production cost.

[0005] To achieve the above purpose, the permanent magnet motor proposed by the utility model includes:

[0006] A motor rotor, including a rotor core and permanent magnets. The rotor core is provided with a plurality of permanent magnet slots at intervals 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, sleeved on 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. 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 number of the stator slots is Q, and the stator winding is wound around the stator teeth. The number of turns of the winding on each stator tooth is N; the stator tooth includes a parallel tooth part and a tooth boot part. One end of the parallel tooth part is connected to the stator yoke, and the other end is connected to the tooth boot part. The width of the parallel tooth part 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] Wherein, 850 ≤ (N × Q) / (K × t) ≤ 950, and 0.25 ≤ t / T ≤ 0.33.

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

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

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

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

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

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

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

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

[0018] In one embodiment, the connection mode of the stator winding is delta connection, and the connection coefficient K = 1.

[0019] In one embodiment, the connection mode of the stator winding is star connection, and the connection coefficient K = 1.732.

[0020] The present utility model further provides a compressor, including the permanent magnet motor described above.

[0021] The present utility model further provides a refrigeration device, including the compressor described above.

[0022] The technical solution of the present utility model adjusts the relationship between the winding turns N of the permanent magnet motor, the number of stator slots Q, the width T of the parallel tooth portion of the stator teeth, and the thickness t of the permanent magnets, so that N, Q, T, and t satisfy: 850 ≤ (N × Q) / (K × t) ≤ 950, and 0.25 ≤ t / T ≤ 0.33, thereby while controlling the production cost, the permanent magnet motor can have better anti-demagnetization ability and reduce the coercivity requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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 drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0024] Figure 1 Structural schematic diagram of an embodiment of the permanent magnet motor provided by the present utility model;

[0025] Figure 2 Relationship curve of (N×Q) / (K×t) and demagnetizing current;

[0026] Figure 3 Relationship curve of t / T and demagnetizing current;

[0027] Figure 4 Relationship curves of (N×Q) / (K×t) and t / T respectively with demagnetizing current;

[0028] Figure 5 Relationship curve of Q / t and demagnetizing current;

[0029] Figure 6 Relationship curve of Q / t and magnet cost;

[0030] Figure 7 Structural schematic diagram when the stator winding in the permanent magnet motor is in delta series;

[0031] Figure 8 Structural schematic diagram when the stator winding in the permanent magnet motor is in star series.

[0032] Explanation of the reference numerals in the drawings:

[0033] 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.

[0034] 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

[0035] 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.

[0036] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, then such directional indications are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture. If this specific posture changes, then the directional indications will also change accordingly.

[0037] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, then such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood 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 various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. 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 protection scope required by the present utility model.

[0038] The present utility model provides a permanent magnet motor 10.

[0039] Please refer to Figure 1 , 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 permanent magnets 120. A plurality of permanent magnet slots 111 are provided at intervals along the circumference of the rotor core 110, and the permanent magnets 120 are embedded in the permanent magnet slots 111; the thickness of the permanent magnets 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 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 number of stator slots 213 is Q, and the stator winding 220 is wound around the stator teeth 212. 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 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 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; wherein, 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. 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 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 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 formed by laminating high-permeability materials or silicon steel punching sheets, has high magnetic permeability, 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 outer periphery of the motor rotor 100 in the same polarity, 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. 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 slot 111 is formed by combining and embedding a plurality of linear or arc-shaped permanent magnets 120.

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

[0042] The demagnetizing magnetic field of the thicker permanent magnet 120 is smaller. The demagnetizing magnetic field will cancel out part of the magnetization intensity, so it can better resist the demagnetization effect caused by the external magnetic field. The thicker permanent magnet 120 can better dissipate heat and slow down the rate of temperature rise, so it can maintain magnetism without demagnetization at a higher temperature. Therefore, increasing the thickness of the permanent magnet 120 can significantly improve its demagnetization resistance ability. However, increasing the thickness of the permanent magnet 120 will also bring about an increase in cost and weight.

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

[0044] Among them, when the number of turns N of the winding increases, the inductive reactance of the stator winding 220 increases. Then, at the same frequency and current, the reactance of the permanent magnet motor 10 increases, thus reducing the current passing through the stator winding 220, further reducing the loss in the stator winding 220, reducing the heat accumulation inside the permanent magnet motor 10, and helping to protect the permanent magnet 120 to maintain magnetism without demagnetization at a higher temperature. At the same time, under the condition of the same current, the magnetic field intensity increases, and the permanent magnet motor 10 can generate a stronger magnetic force, so a larger torque can be generated at the same current. However, when the number of turns N of the winding increases to a certain range, the unit magnetic flux of the permanent magnet motor 10 decreases instead, and its demagnetization resistance ability also decreases.

[0045] The number Q of stator slots 213 indirectly affects the demagnetization resistance ability of the permanent magnet 120 by affecting factors such as the cogging torque, magnetic circuit saturation, leakage flux, and thermal management of the permanent magnet motor 10. The number Q of stator slots 213 will affect the cogging torque of the permanent magnet motor 10, resulting in vibration and noise of the permanent magnet motor 10. More stator slots 213 can reduce the magnetic flux density per slot, thus reducing the saturation degree of the magnetic circuit, helping to maintain the magnetic performance of the permanent magnet motor 10, and indirectly improving the demagnetization resistance ability of the permanent magnet 120. More stator slots 213 usually 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 ability of the permanent magnet 120. More stator slots 213 can increase the heat dissipation area, help to improve the heat dissipation efficiency of the permanent magnet motor 10, help to maintain the operating temperature of the permanent magnet 120 within a safe range, and thus indirectly enhance the demagnetization resistance ability.

[0046] The parallel tooth portion 2121 is the main part of the stator tooth 212. Its shape is relatively straight and parallel to the radial direction of the stator core 210, mainly used to increase the effective area of the stator winding 220. The tooth boot portion 2122 is located at the end of the parallel tooth portion 2121. Its shape is usually wider than that of the parallel tooth portion 2121. The tooth boot portion 2122 can improve the magnetic field distribution of the permanent magnet motor 10, reduce eddy current loss, and thus contribute to improving the efficiency and performance of the permanent magnet motor 10. The tooth boot portion 2122 has two opposite sides in the radial direction of the stator core 210. One side is connected to the parallel tooth portion 2121, and the other side forms part of the inner peripheral wall of the stator core 210. Adjacent two tooth boot portions 2122 form the notch of the stator slot 213.

[0047] The width T of the parallel tooth portion 2121 in the circumferential direction of the stator core 210, that is, the distance between adjacent two stator slots 213, can be measured using a vernier caliper, micrometer, etc. For example, place the two jaws of the vernier caliper between adjacent two stator slots 213, and the two jaws clamp the side walls of the adjacent two slots to read the measured reading. It is also possible to slide the vernier caliper along the length direction of the parallel tooth portion 2121 (the radial direction of the stator core 210) to measure the maximum and minimum values of the parallel tooth portion 2121, and take their average value.

[0048] A wider parallel tooth portion 2121 will help reduce the cogging torque, the saturation degree of the magnetic circuit, and the magnitude of the leakage magnetic flux, thus helping to maintain the magnetic performance 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 decrease in the number and area of the 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 also decreases, which is not conducive to improving the performance of the permanent magnet motor 10.

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

[0050] Please refer to Table 1 and Figure 2 , as (N×Q) / (K×t) increases, the demagnetization current of the permanent magnet motor 10 decreases accordingly. When (N×Q) / (K×t) ≤ 950, the demagnetization current of the permanent magnet motor 10 is higher than 22 A, and the permanent magnet motor 10 has better demagnetization resistance.

[0051] Please refer to Table 2 and Figure 3, as t / T increases, the demagnetization current of the permanent magnet motor 10 increases accordingly. When t / T ≥ 0.25, the demagnetization current of the permanent magnet motor 10 is higher than 22 A, and the permanent magnet motor 10 has good demagnetization resistance ability. However, as t / T increases, the greater the thickness of the permanent magnet 120, the greater the cost of the permanent magnet 120.

[0052] Please refer to Figure 4 , as the demagnetization current increases, the demagnetization resistance ability of the permanent magnet motor 10 is enhanced. However, since t / T increases accordingly, it means that the thickness of the permanent magnet 120 increases, and then the production cost of the permanent magnet 120 increases. At the same time, (N×Q) / (K×t) decreases as t is affected. Therefore, when 850 ≤ (N×Q) / (K×t) ≤ 950 and 0.25 ≤ t / T ≤ 0.33, the demagnetization resistance ability can be improved while effectively controlling the production cost. It can be understood that the coercivity is the inherent property of the permanent magnet 120. The better the performance of the permanent magnet 120, the greater its coercivity, but it also comes with a higher cost. Therefore, the technical solution of the present utility model improves the demagnetization resistance ability by adjusting the relationship among the winding turns N of the permanent magnet motor 10, the number of stator slots 213 Q, the width T of the parallel tooth part 2121 of the stator tooth 212, and the thickness t of the permanent magnet 120, thereby reducing the requirement for the inherent property of the permanent magnet 120, reducing the coercivity requirement, and thus reducing the cost.

[0053] Table 1: Relationship table of (N×Q) / (K×t) and demagnetization 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 table of t / T and demagnetization 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 an 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-slot of the permanent magnet motor 10, and can affect the cogging torque, magnetic circuit saturation degree, leakage magnetic flux, and thermal management of the permanent magnet motor 10, etc.; while the thickness t of the permanent magnet 120 directly affects its demagnetization resistance ability, 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 the thickness of the thinner permanent magnet 120.

[0059] Please refer to Table 3, Figure 5 and Figure 6, as the Q / t ratio increases, the demagnetization current of the permanent magnet motor 10 decreases, and the cost of the permanent magnet 120 decreases accordingly. When Q / t ≥ 11.5, the demagnetization current has decreased to less than 22 A, and the rate of decrease in the demagnetization current increases, but the cost of the permanent magnet 120 can be controlled below 6.3 yuan. When Q / t ≤ 8.5, although the demagnetization current of the permanent magnet motor 10 reaches more than 42 A, the cost of the permanent magnet 120 also increases to more than 14.7 yuan. Therefore, on the basis of 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, the production cost can be effectively controlled, while improving the demagnetization resistance of the permanent magnet motor 10 and reducing the coercivity requirement.

[0060] Table 3: Relationship table of Q / t with the demagnetization current of the permanent magnet motor and the cost of the 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, and 1 mm ≤ t ≤ 2.5 mm.

[0063] When t ≤ 1 mm, the thickness of the permanent magnet 120 is too thin, and the demagnetization resistance of the permanent magnet 120 is low. At the same time, the number of stator slots 213 Q is too large, resulting in a decrease in the slot area of a single stator slot 213 and a decrease in the slot fill factor, which is not conducive to improving the overall performance of the permanent magnet motor 10. When t ≥ 2.5 mm, the thickness of the permanent magnet 120 is too thick, not only increasing the cost of the permanent magnet 120, but also resulting in too few stator slots 213 Q, which is not conducive to reducing the cogging torque, magnetic circuit saturation, and leakage flux of the permanent magnet motor 10, nor is it conducive to improving the overall performance of the permanent magnet motor 10. When 1 mm ≤ t ≤ 2.5 mm, it helps to reduce the cogging torque, the degree of magnetic circuit saturation, the magnitude of the leakage flux, and control the cost of the permanent magnet 120, and can also ensure the number and area of the stator slots 213, thereby indirectly improving 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, and 1 < Q / 2P < 3.

[0065] 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. Different ratios of Q / 2P can have different effects on the waveform quality of the back electromotive force and torque ripple, thus having an important impact on the back electromotive force characteristics and energy efficiency of the permanent magnet motor 10. Therefore, in order to reduce the tooth harmonic magnetic field and reduce 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 wave flux density distribution of the permanent magnet motor 10, and thus affect the performance of the motor. When there is no good cooperation between them, higher tooth harmonics may be generated, resulting in additional losses and torque fluctuations, 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, helps to improve the symmetry of the magnetic circuit, reduces the cogging torque, and helps to better utilize the magnetic flux, thereby improving the demagnetization resistance. When 1 < Q / 2P < 3, there is a better 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 fluctuations, thereby improving the demagnetization resistance, 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, and 15 ≤ Q ≤ 18.

[0067] 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 waveform quality of the back electromotive force and make it closer to the ideal sine waveform; it can improve the magnetic flux distribution, reduce the torque ripple caused by the interaction between magnetic poles, and improve the demagnetization resistance. However, at the same time, it may also require a larger space due to more slots, thereby increasing the volume or weight of the permanent magnet motor 10, 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, improving the waveform quality of the back electromotive force, reducing the cogging torque and torque ripple, and improving the demagnetization resistance.

[0068] 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.

[0069] 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 waveform quality of the back electromotive force and make it closer to the ideal sine wave; it can improve the magnetic flux distribution, reduce the torque ripple caused by the interaction between magnetic poles, and improve the demagnetization resistance. However, at the same time, it may require more space for a larger number of slots, thus increasing the volume or weight of the permanent magnet motor 10, and further reducing the power density. At the same time, a larger number of magnetic poles will also increase the production cost. 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, improving the waveform quality of the back electromotive force, reducing the cogging torque and torque ripple, and improving the demagnetization resistance.

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

[0071] By limiting the ratio of the number of stator slots 213 to the number of magnetic poles of the motor rotor 100 to 3 / 2, it is possible to control the volume and manufacturing cost of the permanent magnet motor 10 while optimizing the magnetic flux distribution, improving the waveform quality of the back electromotive force, reducing the cogging torque and torque ripple, and improving the demagnetization resistance. 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.

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

[0073] The larger the number of turns N of the winding, the greater the back electromotive force, and the winding resistance also increases accordingly, thereby reducing the current of the permanent magnet motor 10 under a given voltage, which helps to reduce the copper loss and improve the efficiency of the permanent magnet motor 10. However, when the number of turns N of the winding increases to a certain value, the unit magnetic flux of the permanent magnet motor 10 decreases instead, and its demagnetization resistance also decreases. When 50 ≤ N ≤ 140, it is possible to increase the back electromotive force of the permanent magnet motor 10, improve the energy efficiency of the permanent magnet motor 10, and at the same time ensure the demagnetization resistance of the permanent magnet motor 10.

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

[0075] When T ≤ 4.5 mm, the too narrow parallel tooth part 2121 may increase the saturation degree of the magnetic circuit, leakage magnetic flux and cogging torque, which is not only disadvantageous to improving the demagnetization resistance ability of the permanent magnet 120, but also causes more vibrations and noises during the operation of the permanent magnet motor 10, reducing the efficiency of the permanent magnet motor 10. When T ≥ 12 mm, the too wide parallel tooth part 2121 causes the reduction of the number and area of the 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 also decreases, thus being not conducive to improving the performance of the permanent magnet motor 10. When 4.5 mm ≤ T ≤ 12 mm, it helps to reduce the cogging torque, the saturation degree of the magnetic circuit and the magnitude of the leakage magnetic flux, and can also ensure the number and area of the stator slots 213, thereby indirectly improving the demagnetization resistance ability of the permanent magnet 120 and the performance of the permanent magnet motor 10.

[0076] In one embodiment, please refer to Figure 7 , the wiring method of the stator winding 220 is delta connection, and the wiring coefficient 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 line voltage and current. The wiring coefficient K is a coefficient used to describe the influence of the three-phase winding connection method on the line 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 start end of each winding serves as the access point of the power supply. When the delta connection wiring method is adopted, the phase voltage is equal to the line voltage, and the delta connection method has almost no influence on the line voltage, so the value of the wiring coefficient K is 1.

[0078] In one embodiment, please refer to Figure 8 , the wiring method of the stator winding 220 is star connection, and the wiring coefficient 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), and the other end of each winding serves as the access point of the power supply. When the star connection wiring method is adopted, the phase current is equal to the line current, but the phase voltage is not equal to the line voltage. Therefore, in star connection, due to the unequal relationship between the phase voltage and the line voltage, the line voltage is 1.732 times the phase voltage. The value of the wiring coefficient K is set to 1.732 to eliminate the influence of the star connection method on the line voltage and ensure the accuracy of the experimental results.

[0080] 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 embodiments. Since the compressor in the technical solution of the present utility model adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.

[0081] The present utility model also provides a refrigeration device, which includes a compressor. The specific structure of the compressor refers to the above embodiments. Refrigeration devices can be divided into compression refrigeration devices, absorption refrigeration devices, steam jet refrigeration devices, heat pump refrigeration devices, electrothermal refrigeration devices, etc. Refrigeration devices mainly consist 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 all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.

[0082] The above are only exemplary embodiments of the present utility model, and do not limit the patent scope of the present utility model accordingly. 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 direct / indirect application 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: The motor rotor comprises a rotor core and a permanent magnet, wherein the rotor core is provided with a plurality of 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 sleeved on the outer circumference of the motor rotor, the motor stator comprises a stator core and a stator winding, 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 number of the stator slots is Q, the stator winding is wound on the stator teeth, and the number of winding turns on each stator tooth is N; 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, and 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 according to claim 1, characterized in that: 8.5≤Q / t≤11.

5.

3. The permanent magnet motor according to claim 2, characterized in that: 1mm≤t≤2.5mm.

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

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

8. The permanent magnet motor according to 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 connection mode of the stator winding is a triangle connection, and the connection coefficient K=1.

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

732.

11. A compressor, characterized in that: It comprises a permanent magnet motor as claimed in any one of claims 1 to 10.

12. A refrigeration device, characterized in that: Comprising the compressor of claim 11.

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