Electric machine and compressor

Abstract

This application discloses an electric motor and a compressor. The compressor includes an electric motor, which comprises a rotor, a permanent magnet, and a stator. The rotor has multiple circumferentially spaced magnet slots that extend through the rotor's axis. In a cross-section obtained by cutting the rotor perpendicular to its axis, each magnet slot includes a first, second, and third straight segment. The perpendicular bisector of the first straight segment passes through the rotor's axis. The second and third straight segments are symmetrically positioned at the ends of the first straight segment and extend along the outer periphery of the rotor. The permanent magnet is embedded within the magnet slot. The angle A between the second and first straight segments satisfies the relationship: 140° ≤ A ≤ 147.5°, and the angle B between the third and first straight segments satisfies the relationship: 140° ≤ B ≤ 147.5°. This application solves the problem of sinusoidal difference in back electromotive force in existing electric motors.

Description

Technical Field

[0001] This application relates to the field of refrigeration equipment technology, and more specifically, to an electric motor and a compressor. Background Technology

[0002] In existing compressor motors, the magnet slots are usually in the shape of a straight line or a V-shape. The V-shaped magnet slot can make the motor more resistant to demagnetization and reduce the thickness of the magnet, thereby reducing the motor production cost. However, because the magnetic density distribution in the air gap of the motor with the V-shaped magnet slot tends to be zero-one distribution, the back electromotive force of the motor is poorly sinusoidal, which affects the overall performance of the motor. Summary of the Invention

[0003] The main objective of this application is to provide an electric motor and a compressor that at least solves the problem of back electromotive force sine difference in the prior art.

[0004] According to one aspect of this application, an electric motor is provided, comprising:

[0005] The rotor has multiple magnet slots spaced apart along its circumference. The magnet slots extend through the rotor along its axial direction. In a cross-section obtained by cutting the rotor perpendicular to its axial direction, each magnet slot includes a first straight segment, a second straight segment, and a third straight segment. The perpendicular bisector of the first straight segment passes through the rotor's axial direction. The second and third straight segments are symmetrically arranged at both ends of the first straight segment, and the second and third straight segments extend along a direction close to the outer periphery of the rotor.

[0006] The permanent magnet includes multiple permanent magnets, which are respectively embedded in the first straight segment, the second straight segment and the third straight segment;

[0007] The stator has a first through hole, and the stator is sleeved on the outer periphery of the rotor through the first through hole;

[0008] The angle A between the second line segment and the first line segment satisfies the relationship: 140°≤A≤147.5°, and the angle B between the third line segment and the first line segment satisfies the relationship: 140°≤B≤147.5°.

[0009] Furthermore, the outer periphery of the rotor is provided with a plurality of first rotor slots and a plurality of second rotor slots, the plurality of first rotor slots being spaced apart, and the plurality of second rotor slots being spaced apart;

[0010] In this configuration, a second rotor slot is provided between two adjacent magnet slots, and the first rotor slots are provided on both sides of the second rotor slot. The maximum depth of the second rotor slot is greater than the maximum depth of the first rotor slot.

[0011] Furthermore, the second rotor slot includes an outwardly expanding portion and an inwardly contracting portion. The outwardly expanding portion expands outward in a direction away from the axis, and the first rotor slot is respectively provided at both ends of the outwardly expanding portion. The inwardly contracting portion is disposed inside the outwardly expanding portion, and the inwardly contracting portion contracts inward in a direction close to the axis.

[0012] The maximum distance from the inward-retracting portion to the outer circumferential surface of the rotor is greater than the maximum distance from the outward-expanding portion to the outer circumferential surface of the rotor.

[0013] Furthermore, the minimum distance g1 between the outer peripheral surface of the rotor and the inner wall surface of the first through hole and the maximum distance g2 between the outer expansion portion and the inner wall surface of the first through hole satisfy the following relationship: 3≤g2 / g1≤4; where 0.45mm≤g1≤0.55mm.

[0014] Furthermore, two first rotor slots are spaced apart between two adjacent second rotor slots, and there is an arc-shaped surface between the two first rotor slots. The central angle C corresponding to the arc-shaped surface satisfies the relationship: 19°≤C≤21°.

[0015] Furthermore, the second rotor slot extends to the outer circumferential surface of the rotor, and the central angle D of the corresponding arc length of the two opposite sidewalls of the second rotor slot across the outer circumferential surface of the rotor satisfies the relationship: 14°≤D≤16°.

[0016] Furthermore, the rotor also includes a plurality of second through holes, which penetrate the rotor along the axial direction of the rotor, and each of the magnet slots is provided with at least two second through holes at intervals on the side near the outer peripheral surface of the rotor.

[0017] Furthermore, the stator includes a plurality of stator teeth, which are spaced apart on the side of the stator near the rotor. Each magnet slot is provided with two second through holes between it and the outer peripheral surface of the rotor. The two second through holes are symmetrically arranged along the perpendicular bisector of the first straight line segment.

[0018] Wherein, the maximum distance W1 between the two second through holes and the minimum width T of the stator tooth satisfy the relationship: T-W1≤1mm; and / or,

[0019] The permanent magnet includes a first magnet, which is embedded in the first straight segment. The length W2 of the first magnet and the maximum distance W1 between the two second through holes satisfy the relationship: W2 = W1.

[0020] Furthermore, the permanent magnet includes a plurality of first magnets, a plurality of second magnets and a plurality of third magnets, each of the first magnets being embedded in each of the first straight segments, each of the second magnets being embedded in each of the second straight segments, and each of the third magnets being embedded in each of the third straight segments.

[0021] The lengths of the first magnet along the length of the first straight segment (W2), the second magnet along the length of the second straight segment (W3), and the third magnet along the length of the third straight segment (W4) satisfy the following relationship: W2 ≤ W3 = W4 or W2 ≥ W3 = W4.

[0022] On the other hand, this application also provides a compressor that includes the aforementioned motor.

[0023] Compared to existing technologies, in this application, the magnet slot includes a first straight segment, a second straight segment, and a third straight segment. The perpendicular bisector of the first straight segment passes through the rotor's axis. The second and third straight segments are symmetrically arranged at both ends of the first straight segment, and extend along the outer periphery of the rotor. Multiple permanent magnets are included, each embedded within one of the first, second, and third straight segments. Furthermore, the angle A between the second and first straight segments satisfies the formula: 140° ≤ A ≤ 147.5°, and the angle B between the third and first straight segments satisfies the formula: 140° ≤ B ≤ 147.5°. In other words, the angle E between the extension lines of the first and second straight segments should satisfy the formula: 100° ≤ E ≤ 115°. The magnetic field lines emitted by the permanent magnets in the first, second, and third straight segments are perpendicular to the direction of the permanent magnets. When E satisfies the above relationship, the magnetic field lines emitted by the first and third straight segments are emitted into the air gaps perpendicular to the outer periphery of the first straight segment. There are fewer magnetic field lines in the air gaps perpendicular to the first and third straight segments, meaning the magnetic induction intensity of the magnetic field is greatest in the air gap corresponding to the first straight segment. Furthermore, the magnetic field lines extend along the direction from the air gap corresponding to the first straight segment to the air gap corresponding to the second straight segment, and from the air gap corresponding to the first straight segment to... In the air gap direction corresponding to the third straight segment, the magnetic induction intensity of the magnetic field in the air gap gradually decreases. Then, after passing the next magnet slot, the intensity of the magnetic field in the air gap gradually increases. This cycle repeats, eventually causing the intensity of the magnetic field in the air gap to first decrease and then increase in the circumferential direction in a cyclical manner. That is, the magnetic induction intensity of the magnetic field in the air gap conforms to a sinusoidal distribution. When the magnetic induction intensity in the magnetic field conforms to a sinusoidal distribution, the fluctuation of the magnetic field decreases, thereby reducing the harmonic peak value in the back electromotive force on stator 20. Ultimately, this makes the waveform of the back electromotive force more sinusoidal, thereby improving the overall performance of the motor. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0025] Figure 1 This is a schematic cross-sectional view of the motor disclosed in this application.

[0026] Figure 2 for Figure 1 Enlarged schematic diagram of region I;

[0027] Figure 3 This is a schematic diagram showing the relationship between angle E and the peak value of the back electromotive force.

[0028] Figure 4 This is a schematic diagram showing the relationship between the g2 / g1 ratio and the back electromotive force waveform distortion rate.

[0029] The above figures include the following reference numerals:

[0030] 10. Rotor; 11. Magnet slot; 12. Second through hole; 13. First rotor slot; 14. Second rotor slot; 20. Stator; 21. Stator tooth; 22. First through hole; 30. Permanent magnet; 31. First magnet; 32. Second magnet; 33. Third magnet; 40. Air gap; 111. First straight segment; 112. Second straight segment; 113. Third straight segment; 141. Outward expansion; 142. Inward contraction. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0034] See Figures 1 to 4 As shown, according to an embodiment of this application, a compressor is provided, which includes a motor, the motor including: a rotor 10, a permanent magnet 30 and a stator 20.

[0035] The rotor 10 has multiple magnet slots 11 spaced circumferentially along its axis. These slots extend through the rotor 10. In a cross-section obtained by cutting the rotor 10 perpendicular to its axis, each magnet slot 11 includes a first straight segment 111, a second straight segment 112, and a third straight segment 113. The perpendicular bisector of the first straight segment 111 passes through the axis of the rotor 10. The second and third straight segments 112 and 113 are symmetrically positioned at both ends of the first straight segment 111, extending along the outer periphery of the rotor 10. Multiple permanent magnets 30 are embedded within the first, second, and third straight segments 111 and 112, respectively. The stator 20 has a first through hole 22, through which it is fitted onto the outer periphery of the rotor 10. Among them, the angle A between the second line segment 112 and the first line segment 111 satisfies the relationship: 140°≤A≤147.5°, and the angle B between the third line segment 113 and the first line segment 111 satisfies the relationship: 140°≤B≤147.5°.

[0036] In existing motors, the magnet slots 11 are mostly arranged in a straight line or a V-shape. In a straight magnet slot 11, the magnetic lines of force of the permanent magnets 30 are evenly distributed in the air gap 40 between the stator 20 and the rotor 10, resulting in large harmonics in the back electromotive force on the stator 20, ultimately causing a high waveform distortion rate of the back electromotive force. In a V-shaped magnet slot 11, the magnetic lines of force between the permanent magnets 30 are more numerous in the middle and fewer at both ends, and the magnetic lines of force in the air gap 40 tend to be distributed at zero or one, which makes the waveform of the back electromotive force resemble a trapezoid, ultimately resulting in poor motor efficiency, large vibration, and large torque fluctuation.

[0037] In this embodiment, the magnet slot 11 includes a first straight segment 111, a second straight segment 112, and a third straight segment 113. The perpendicular bisector of the first straight segment 111 passes through the axis of the rotor 10. The second straight segment 112 and the third straight segment 113 are symmetrically arranged at both ends of the first straight segment 111, and the second straight segment 112 and the third straight segment 113 extend along the outer periphery of the rotor 10. Multiple permanent magnets 30 are included, and each permanent magnet 30 is embedded within the first straight segment 111, the second straight segment 112, and the third straight segment 113. Furthermore, the included angle A between the second straight segment 112 and the first straight segment 111 satisfies the relationship: 140°≤A≤147.5°, and the included angle B between the third straight segment 113 and the first straight segment 111 satisfies the relationship: 140°≤B≤147.5°. In other words, the angle E between the extension lines of the first straight segment 111 and the second straight segment 112 should satisfy the relationship: 100°≤E≤115°. The magnetic field lines emitted by the permanent magnet 30 in the first straight segment 111, the second straight segment 112, and the third straight segment 113 are perpendicular to the direction of the permanent magnet 30. When E satisfies the above relationship, the magnetic field lines emitted by the first straight segment 111 and the third straight segment 113 are emitted into the air gap 40 corresponding to the outer periphery of the first straight segment 111. There are fewer magnetic field lines in the air gap 40 perpendicular to the first straight segment 111 and the third straight segment 113. That is to say, the magnetic induction intensity of the magnetic field in the air gap 40 corresponding to the first straight segment 111 is the largest, and the magnetic field line extends from the air gap 40 corresponding to the first straight segment 111 to the air gap 40 corresponding to the second straight segment 112. From the air gap 40 corresponding to the first straight segment 111 to the air gap 40 corresponding to the third straight segment 113, the magnetic induction intensity of the magnetic field in the air gap 40 gradually decreases. Then, after passing through the next magnet slot 11, the intensity of the magnetic field in the air gap 40 gradually increases. This cycle repeats, ultimately causing the intensity of the magnetic field in the air gap 40 to first decrease and then increase in the circumferential direction in a cyclical manner. That is, the magnetic induction intensity of the magnetic field in the air gap 40 conforms to a sinusoidal distribution. When the magnetic induction intensity in the magnetic field conforms to a sinusoidal distribution, the fluctuation of the magnetic field decreases, thereby reducing the harmonic peak value in the back electromotive force on the stator 20. Ultimately, this makes the waveform of the back electromotive force more sinusoidal, thereby improving the overall performance of the motor. If E is greater than 115°, due to the excessive angle between the permanent magnets 30, the magnetic field lines are difficult to converge at the air gap 40 corresponding to the first straight segment 111, resulting in a smaller magnetic density in the air gap 40 corresponding to the first straight segment 111. Furthermore, the magnetic induction intensity of the magnetic field in the air gap 40 corresponding to the second straight segment 112 and the third straight segment 113 is even lower, ultimately resulting in a smaller peak value of the back electromotive force generated on the stator 20, thereby affecting the performance of the motor.If E is less than 100°, the magnetic field lines converge. The magnetic density in the air gap 40 corresponding to the first straight segment 111, the second straight segment 112, and the third straight segment 113 is relatively large and similar. This results in a large back EMF peak, causing the motor to heat up too quickly. Furthermore, the back EMF contains large harmonics, which reduces the motor's performance.

[0038] Furthermore, based on the above analysis, this application obtains the attached [parameter] by simulating the motor. Figure 3 The graph shows the relationship between angle E and the peak value of the back EMF. It can be observed that as the angle E increases, the peak value of the back EMF gradually decreases. To ensure that the peak value of the back EMF is within a moderate range, i.e., between 72V and 78V, and to avoid the back EMF being too large or too small and affecting the motor, the value of E in this application should be between 100° and 115°. The value of E can be 100°, 105°, 110°, or 115°.

[0039] Furthermore, a plurality of first rotor slots 13 and a plurality of second rotor slots 14 are provided on the outer periphery of the rotor 10. The plurality of first rotor slots 13 are spaced apart, and the plurality of second rotor slots 14 are spaced apart. A second rotor slot 14 is provided between two adjacent magnet slots 11. The first rotor slots 13 are provided on both sides of the second rotor slot 14, and the maximum slot depth of the second rotor slot 14 is greater than the maximum slot depth of the first rotor slot 13.

[0040] Specifically, in some current motors, rotor slots are typically not provided on the outer periphery of the rotor 10. When magnetic lines of force pass through the permanent magnet 30 into the air gap 40 between the rotor 10 and the stator 20, the magnetic induction intensity is uniformly distributed throughout the air gap 40. At this time, the harmonic peak value in the back electromotive force generated on the stator 20 is relatively large, ultimately causing the waveform of the back electromotive force to tend towards a trapezoidal wave. However, in this embodiment, the outer periphery of the rotor 10 is provided with not only multiple first rotor slots 13, but also multiple second rotor slots 14, and the depth of the second rotor slots 14 is greater than that of the first rotor slots 13. It can be understood that when the magnetic lines of force pass through the rotor 10 and reach the first rotor slot 13, since the first rotor slot 13 is a groove, the direction of some magnetic lines of force changes, and the magnetic field generated by these magnetic lines of force in the air gap 40 cannot induce an electromotive force in the stator 20. Ultimately, the magnetic induction intensity of the magnetic field in the first rotor slot 13 that can affect the stator 20 is reduced. Similarly, when the magnetic field lines enter the second rotor slot 14, their direction changes, causing a decrease in the magnetic flux density of the magnetic field that induces an electromotive force in the stator 20 within the second rotor slot 14. Since the maximum depth of the second rotor slot 14 is greater than the maximum depth of the first rotor slot 13, more magnetic field lines change direction at the second rotor slot 14 during their exit from the rotor 10, compared to fewer at the first rotor slot 13. This results in a lower effective magnetic flux density at the second rotor slot 14 compared to the first rotor slot 13. Conversely, the magnetic flux density is highest at the air gap 40 corresponding to the unslotted rotor 10. The magnetic flux density within the air gap 40 decreases and then increases circumferentially, ultimately resulting in a sinusoidal distribution. This reduces harmonics in the back electromotive force of the stator 20, making the back electromotive force more sinusoidal and improving the overall performance of the motor.

[0041] Furthermore, the second rotor slot 14 includes an outwardly expanding portion 141 and an inwardly contracting portion 142. The outwardly expanding portion 141 expands outward in a direction away from the axis, and the two ends of the outwardly expanding portion 141 are respectively provided with the first rotor slot 13. The inwardly contracting portion 142 is disposed inside the outwardly expanding portion 141, and the inwardly contracting portion 142 contracts inward in a direction close to the axis. The maximum distance from the inwardly contracting portion 142 to the outer peripheral surface of the rotor 10 is greater than the maximum distance from the outwardly expanding portion 141 to the outer peripheral surface of the rotor 10.

[0042] Specifically, since the maximum distance from the concave portion 142 to the outer circumferential surface of the rotor 10 is greater than the maximum distance from the convex portion 141 to the outer circumferential surface of the rotor 10, the magnetic induction intensity in the air gap 40 corresponding to the concave portion 142 is the lowest, corresponding to the lowest point in the sine wave. Meanwhile, as the convex portion 141 gradually expands outward in a direction away from the axis, the magnetic induction intensity in the air gap 40 corresponding to the convex portion 141 changes uniformly; that is, the magnetic density gradually decreases from the outer end of the convex portion 141 to the concave portion 142, and gradually increases from the inner end of the concave portion 142 to the outer end of the convex portion 141.

[0043] Furthermore, the minimum distance g1 between the outer peripheral surface of the rotor 10 and the inner wall surface of the first through hole 22 and the maximum distance g2 between the outer expansion portion 141 and the inner wall surface of the first through hole 22 satisfy the following relationship: 3≤g2 / g1≤4; where 0.45mm≤g1≤0.55mm.

[0044] In this embodiment, if the maximum distance from the expansion portion 141 to the outer peripheral surface of the rotor 10 is too large, such as g2 / g1 being greater than 4, the magnetic density in the air gap 40 corresponding to the expansion portion 141 will decrease excessively compared to the magnetic density in the air gap 40 corresponding to the first rotor slot 13. This will result in a lower peak value of the back electromotive force at a certain moment, thus affecting the performance of the motor. Simultaneously, if the maximum distance from the expansion portion 141 to the outer peripheral surface of the rotor is too large, the second rotor slot 14 will be opened too deeply, thus affecting the rigidity of the rotor 10. Conversely, if g2 / g1 is small, such as g2 / g1 being less than 3, the difference between the magnetic density in the air gap 40 corresponding to the first rotor slot 13 and the magnetic density in the air gap 40 corresponding to the second rotor slot 14 will be small. In this case, the peak value of the harmonics in the back electromotive force will be large, and the probability of waveform distortion of the back electromotive force will be high. Furthermore, to ensure that the peak value of the back electromotive force is moderate, the value of g1 in this embodiment should be set between 0.45 mm and 0.55 mm. The value of g1 determines the peak value of the back electromotive force (EMF). When g1 is small, the back EMF generated on stator 20 is large, while when g1 is large, the back EMF generated on stator 20 is small. If the back EMF is too large, the motor temperature will rise too high, leading to overheating. If the back EMF is too low, the motor efficiency will be low, and the motor's lifespan will be reduced. Therefore, when the value of g1 is set between 0.45mm and 0.55mm, the peak value of the back EMF in the motor is moderate. The possible values ​​of g1 are 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, and 0.55mm. The possible values ​​of g2 / g1 are 3, 3.2, 3.4, 3.6, 3.8, and 4.

[0045] This application also provides the following specific embodiments to illustrate the effect of g2 / g1 on the sinusoidalization of the back electromotive force waveform:

[0046] Example 1:

[0047] When g2 / g1 is 3, the waveform distortion rate of the back electromotive force is 3.9%.

[0048] Example 2:

[0049] When g2 / g1 is 3.5, the waveform distortion rate of the back electromotive force is 3.83%.

[0050] Example 3:

[0051] When g2 / g1 is 4, the waveform distortion rate of the back electromotive force is 3.76%.

[0052] Comparative Example 1:

[0053] When g2 / g1 is 1, the waveform distortion rate of the back electromotive force is 11.1%.

[0054] Comparative Example 2:

[0055] When g2 / g1 is 1.5, the waveform distortion rate of the back electromotive force is 8.3%.

[0056] Comparative Example 3:

[0057] When g2 / g1 is 2, the waveform distortion rate of the back electromotive force is 6.4%.

[0058] Comparative Example 4:

[0059] When g2 / g1 is 2.5, the waveform distortion rate of the back electromotive force is 5.2%.

[0060] According to the appendix Figure 4 As can be seen from the above comparative examples and embodiments, as the ratio of g2 / g1 increases, the waveform distortion rate of the back electromotive force gradually decreases. When g2 / g1 is 3, the waveform distortion rate decreases to 3.9%, meaning that the harmonic peak values ​​in the back electromotive force are low, and the interference to the fundamental wave is minimal. At this point, the waveform of the back electromotive force tends to be sinusoidal. To avoid excessively high waveform distortion of the back electromotive force, it should generally be controlled within 5%. Therefore, in this embodiment, the preferred value of g2 / g1 is between 3 and 4.

[0061] Furthermore, two first rotor slots 13 are provided at intervals between two adjacent second rotor slots 14. There is an arc-shaped surface between the two first rotor slots 13, and the central angle C corresponding to the arc-shaped surface satisfies the relationship: 19°≤C≤21°.

[0062] Specifically, the magnetic field lines emitted by the permanent magnet 30 in the magnet slot 11 converge on the arc-shaped surface, and there are more magnetic field lines at the arc-shaped surface than at the first rotor slot 13. Simultaneously, there are more magnetic field lines at the first rotor slot 13 than at the second rotor slot 14. At this time, the magnetic density at the air gap 40 on the outer periphery of the arc-shaped surface is higher than that at the first rotor slot 13, and the magnetic density at the first rotor slot 13 is higher than that at the second rotor slot 14. That is, along the arc-shaped surface, the first rotor slot 13, and the second rotor slot 14, the magnetic density of the air gap 40 decreases sequentially. Then, along the second rotor slot 14, the first rotor slot 13, and the arc-shaped surface, the magnetic density within the air gap 40 increases sequentially, thus making the magnetic density within the air gap 40 conform to a sinusoidal distribution. Simultaneously, it can be understood that the magnetic density within the air gap 40 corresponding to the arc-shaped surface is at its maximum. If the central angle C of the arc-shaped surface is large, such as C greater than 21°, then the arc-shaped surface is large, and the magnetic density within the air gap 40 corresponding to the arc-shaped surface is almost uniform, ultimately causing the magnetic density distribution of the entire air gap 40 to deviate from a sinusoidal distribution. When C is less than 19°, the arc-shaped surface is small, and the magnetic density distribution of the entire air gap 40 is trapezoidal, ultimately leading to a high waveform distortion rate in the back electromotive force. The value of C can be 19°, 19.5°, 20°, 20.5°, or 21°.

[0063] Furthermore, the second rotor slot 14 extends to the outer peripheral surface of the rotor 10, and the central angle D of the corresponding arc length of the two opposite sidewalls of the second rotor slot 14 across the outer peripheral surface of the rotor 10 satisfies the relationship: 14°≤D≤16°.

[0064] In other words, the area occupied by the second rotor slot 14 on the outer periphery of the rotor 10 slot should not be too large. Specifically, when D is greater than 16°, the second rotor slot 14 is too large, which reduces the structural strength of the rotor 10 and consequently shortens the motor's lifespan. Conversely, if D is less than 14°, the second rotor slot 14 is too small, resulting in a smaller decrease in magnetic density in the air gap 40 corresponding to the second rotor slot 14, thus preventing a sinusoidal magnetic density distribution throughout the air gap 40. The value of D can be 14°, 14.5°, 15°, 15.5°, or 16°.

[0065] As attached Figure 2 As shown, the rotor 10 also includes a plurality of second through holes 12, which penetrate the rotor 10 along the axial direction of the rotor 10. Each magnet slot 11 is provided with at least two second through holes 12 at intervals on the side near the outer peripheral surface of the rotor 10.

[0066] In this embodiment, the second through hole 12 is used to isolate magnetic field lines. That is, when the magnetic field lines emitted by the permanent magnets 30 at the second straight segment 112 and the third straight segment 113 encounter the second through hole 12, the magnetic field lines will not pass through the second through hole 12 and reach the air gap 40. The design of this application can avoid too many magnetic field lines passing through the arc-shaped surface, which would lead to an excessively high magnetic density at the air gap 40 corresponding to the arc-shaped surface, and consequently, an excessively large peak value of the back electromotive force.

[0067] Furthermore, compared to the straight-line magnet slot 11, if the magnet slot 11 of this application is equipped with the same permanent magnet 30 as the straight-line magnet slot 11, the magnetic field variation within the air gap 40 of this application is uniform, resulting in smaller magnetic field fluctuations and thus improving the motor's anti-demagnetization effect. Therefore, when using permanent magnets 30 of the same size, the anti-demagnetization effect of this application is better. In one specific embodiment, the thickness of the permanent magnet 30 in the motor of this application is 1.6mm, while the thickness of the permanent magnet 30 in the motor using the straight-line magnet slot 11 is 1.8mm. The anti-demagnetization effect of the motor of this application is the same as that of the motor using the straight-line magnet slot 11. On the other hand, compared with the existing motors using V-shaped magnet slots 11, the arrangement of magnet slots 11 in this application makes the magnetic density distribution of the magnetic field formed by the permanent magnet 30 in the air gap 40 tend to be sinusoidal. Since the magnetic lines of force of the permanent magnet 30 in the V-shaped magnet slot 11 are relatively concentrated, at least four second through holes 12 need to be arranged between the magnet slot 11 and the outer peripheral surface of the rotor 10 to make the magnetic density of the magnetic field in the air gap 40 sinusoidal. However, in this embodiment, only two second through holes 12 need to be provided.

[0068] Furthermore, the stator 20 includes a plurality of stator teeth 21, which are spaced apart on the side of the stator 20 near the rotor 10. Each magnet slot 11 is provided with two second through holes 12 between it and the outer peripheral surface of the rotor 10. The two second through holes 12 are symmetrically arranged along the perpendicular bisector of the first straight line segment 111. The maximum distance W1 between the two second through holes 12 and the minimum width T of the stator teeth 21 satisfy the following relationship: T-W1≤1mm.

[0069] Specifically, the magnetic lines of force emitted by the permanent magnet 30 within the first straight segment 111 can pass through the two second through holes 12 and exit along the arc-shaped surface. When the maximum distance W1 between the two second through holes 12 and the minimum width T of the stator tooth 21 satisfy the above relationship, the width of the stator tooth 21 is close to the maximum distance between the two second through holes 12. At this time, most of the magnetic lines of force exiting from the arc-shaped surface can penetrate into the stator tooth 21, thereby generating a back electromotive force within the stator 20. If T-W1 > 1mm, the difference between the maximum width of the stator tooth 21 and the maximum spacing between the two second through holes 12 is large. This may be because the minimum width T of the stator tooth 21 is set too large, which will reduce the number of stator slots opened on the stator and ultimately affect the output stability of the motor. Alternatively, it may be because the maximum spacing W1 between the two second through holes 12 is set too small. If W1 is set too small, most of the magnetic lines of force on the first straight segment 111, the second straight segment 112 and the third straight segment 113 will be shielded by the second through holes 12, which will ultimately result in a small magnetic field density in the air gap corresponding to the arc surface, and thus a low back electromotive force.

[0070] Optionally, the permanent magnet 30 includes a first magnet 31, which is embedded in the first straight segment 111. The length W2 of the first magnet 31 and the maximum distance W1 between the two second through holes 12 satisfy the relationship: W2 = W1. In this embodiment, the length W2 of the first magnet 31 should be as close as possible to the maximum gap W1 between the two second through holes 12, that is, the magnetic lines of force generated by the first magnet 31 can all pass through the maximum gap between the two second through holes 12 and be emitted from the arc-shaped surface.

[0071] Furthermore, the permanent magnet 30 includes a plurality of first magnets 31, a plurality of second magnets 32, and a plurality of third magnets 33. Each first magnet 31 is embedded in a corresponding first straight segment 111, each second magnet is embedded in a corresponding second straight segment 112, and each third magnet 33 is embedded in a corresponding third straight segment 113. The lengths W2 of the first magnet 31 along the length of the first straight segment 111, W3 of the second magnet 32 ​​along the length of the second straight segment 112, and W4 of the third magnet 33 along the length of the third straight segment 113 satisfy the following relationships: W2 ≤ W3 = W4 or W2 ≥ W3 = W4.

[0072] In some embodiments, W2, W3, and W4 are identical, meaning the first magnet 31, second magnet 32, and third magnet 33 all have the same specifications, facilitating manufacturing. In other embodiments, W2 is smaller than W3 and W4, meaning the first magnet 31 has a smaller size. This facilitates the design of the first straight segment 111, second straight segment 112, and third straight segment 113, preventing the first straight segment 111 from being too large, which would make it difficult to create the second and third straight segments 112 and 113. Alternatively, W2 can be larger than W3 and W4, meaning the first magnet 31 can have a larger size, increasing the number of magnetic lines of force penetrating the curved surface.

[0073] In summary, the magnet slot 11 in the motor of this application includes a first straight segment 111, a second straight segment 112, and a third straight segment 113. By limiting the included angle A between the first straight segment 111 and the second straight segment 112, and the included angle B between the first straight segment 111 and the third straight segment 113, the magnetic density distribution in the air gap 40 tends to be sinusoidal, thereby reducing the magnitude of harmonics in the back electromotive force on the stator 20, and making the waveform of the back electromotive force tend to be sinusoidal, thus improving the overall performance of the motor. In addition, the rotor 10 in the motor of this application has a first rotor slot 13 and a second rotor slot 14 on its outer periphery. The depth of the second rotor slot 14 is greater than that of the first rotor slot 13. One advantage of this arrangement is that the magnetic density in the air gap 40 has a smooth decreasing trend along the arc surface, the first rotor slot 13, and the second rotor slot 14, thereby making the magnetic density distribution in the air gap 40 more sinusoidal. On the other hand, this embodiment reduces the peak value of harmonics in the back electromotive force by limiting the value of g2 / g1, thereby avoiding excessive interference of harmonics on the fundamental wave and thus preventing excessive waveform distortion of the back electromotive force. Furthermore, this application also prevents uneven changes in the air gap 40 along the axial direction by limiting the central angle C corresponding to the arc surface and the central angle D corresponding to the arc length of the two opposite sidewalls of the second rotor slot 14 across the outer periphery of the rotor 10, which would ultimately lead to excessive waveform distortion of the back electromotive force.

[0074] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0075] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0076] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An electric motor, characterized in that, include: A rotor (10) is provided with a plurality of magnet slots (11) spaced apart circumferentially along the rotor (10). The magnet slots (11) are arranged through the rotor (10) along the axial direction. In a cross section obtained by cutting the rotor (10) along the axial direction perpendicular to the rotor (10), the magnet slots (11) include a first straight segment (111), a second straight segment (112) and a third straight segment (113). The perpendicular bisector of the first straight segment (111) passes through the axis of the rotor (10). The second straight segment (112) and the third straight segment (113) are symmetrically arranged at both ends of the first straight segment (111), and the second straight segment (112) and the third straight segment (113) extend along the outer periphery of the rotor (10). Permanent magnet (30), the permanent magnet (30) includes a plurality of permanent magnets (30), and the plurality of permanent magnets (30) are respectively embedded in the first straight line segment (111), the second straight line segment (112) and the third straight line segment (113); A stator (20) is provided with a first through hole (22), and the stator (20) is sleeved on the outer periphery of the rotor (10) through the first through hole (22); The angle A between the second line segment (112) and the first line segment (111) satisfies the relationship: 140°≤A≤147.5°, and the angle B between the third line segment (113) and the first line segment (111) satisfies the relationship: 140°≤B≤147.5°.

2. The motor according to claim 1, characterized in that, The rotor (10) has a plurality of first rotor slots (13) and a plurality of second rotor slots (14) on its outer periphery, the plurality of first rotor slots (13) being spaced apart, and the plurality of second rotor slots (14) being spaced apart; Among them, a second rotor groove (14) is provided between two adjacent magnet grooves (11), and the first rotor groove (13) is provided on both sides of the second rotor groove (14), and the maximum groove depth of the second rotor groove (14) is greater than the maximum groove depth of the first rotor groove (13).

3. The motor according to claim 2, characterized in that, The second rotor slot (14) includes an outwardly expanding portion (141) and an inwardly contracting portion (142). The outwardly expanding portion (141) expands outward in a direction away from the axis. The first rotor slot (13) is provided at both ends of the outwardly expanding portion (141). The inwardly contracting portion (142) is disposed inside the outwardly expanding portion (141) and the inwardly contracting portion (142) contracts inward in a direction close to the axis. The maximum distance from the inner portion (142) to the outer peripheral surface of the rotor (10) is greater than the maximum distance from the outer portion (141) to the outer peripheral surface of the rotor (10).

4. The motor according to claim 3, characterized in that, The minimum distance g1 between the outer peripheral surface of the rotor (10) and the inner wall surface of the first through hole (22) and the maximum distance g2 between the outer expansion portion (141) and the inner wall surface of the first through hole (22) satisfy the following relationship: 3≤g2 / g1≤4; where 0.45mm≤g1≤0.55mm.

5. The motor according to claim 2, characterized in that, Two first rotor slots (13) are spaced apart between two adjacent second rotor slots (14). There is an arc-shaped surface between the two first rotor slots (13), and the central angle C corresponding to the arc-shaped surface satisfies the relationship: 19°≤C≤21°.

6. The motor according to claim 2, characterized in that, The second rotor slot (14) extends to the outer peripheral surface of the rotor (10), and the central angle D of the corresponding arc length of the two opposite sidewalls of the second rotor slot (14) across the outer peripheral surface of the rotor (10) satisfies the relationship: 14°≤D≤16°.

7. The motor according to any one of claims 1 to 6, characterized in that, The rotor (10) also includes a plurality of second through holes (12), which penetrate the rotor (10) along the axial direction of the rotor (10). Each magnet slot (11) is provided with at least two second through holes (12) at intervals on the side of the outer peripheral surface of the rotor (10).

8. The motor according to claim 7, characterized in that, The stator (20) includes a plurality of stator teeth (21), which are spaced apart on the side of the stator (20) near the rotor (10). Each magnet slot (11) is provided with two second through holes (12) between it and the outer peripheral surface of the rotor (10). The two second through holes (12) are symmetrically arranged along the perpendicular bisector of the first straight line segment (111). The maximum distance W1 between the two second through holes (12) and the minimum width T of the stator tooth (21) satisfy the following relationship: T-W1≤1mm; and / or, The permanent magnet (30) includes a first magnet (31), which is embedded in the first straight segment (111). The length W2 of the first magnet (31) and the maximum distance W1 between the two second through holes (12) satisfy the relationship: W2 = W1.

9. The motor according to any one of claims 1 to 6, characterized in that, The permanent magnet (30) includes a plurality of first magnets (31), a plurality of second magnets (32) and a plurality of third magnets (33). Each first magnet (31) is embedded in each of the first straight segments (111), each second magnet is embedded in each of the second straight segments (112), and each of the third magnets (33) is embedded in each of the third straight segments (113). The lengths of the first magnet (31) along the length of the first straight segment (111), the second magnet (32) along the length of the second straight segment (112), and the third magnet (33) along the length of the third straight segment (113) satisfy the following relationship: W2≤W3=W4 or W2≥W3=W4.

10. A compressor, characterized in that, The compressor includes the motor according to any one of claims 1 to 9.

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