Electric machine, compressor and refrigeration plant

Abstract

The application discloses a motor, a compressor and a refrigeration device, and relates to the technical field of refrigeration devices, wherein the motor comprises a rotor and a stator, the rotor comprises a rotor core and a permanent magnet, the rotor core is provided with a plurality of mounting grooves in the circumferential direction thereof, two adjacent mounting grooves are symmetrical about a second center line, a harmonic hole is arranged between the two adjacent mounting grooves, and each harmonic hole is symmetrical about the second center line. The technical scheme provided by the application sets the harmonic hole between the two adjacent mounting grooves, and the harmonic hole is limited, and the counter electromotive force harmonic and the torque ripple are effectively inhibited, so that the vibration noise during the operation of the motor is reduced.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment technology, and particularly to a motor, compressor and refrigeration equipment. Background Technology

[0002] Traditional permanent magnet synchronous motors exhibit significant cogging torque due to the interaction between the stator and rotor. Additionally, the back electromotive force waveform of the motor contains numerous harmonic components, resulting in significant torque pulsation and consequently severe vibration and noise. Summary of the Invention

[0003] The main objective of this invention is to provide a motor, compressor, and refrigeration equipment that effectively suppresses back EMF harmonics and torque pulsation to reduce vibration noise during motor operation.

[0004] To achieve the above objectives, the present invention provides a motor comprising:

[0005] The rotor includes a rotor core and a permanent magnet. The rotor core has a first center line and a second center line extending radially therein. The rotor core is provided with a plurality of mounting slots spaced apart along its circumference. The permanent magnet is embedded in the mounting slots and has 2P magnetic poles formed in the circumference of the rotor core. Two adjacent mounting slots are symmetrical about the second center line. A harmonic hole is provided between two adjacent mounting slots. Each harmonic hole is symmetrical about the second center line. The side of the harmonic hole near the edge of the rotor core has two first endpoints away from the second center line. The angle formed by the two first endpoints and the center of the rotor core is α1.

[0006] The mounting slot includes a first slot, a second slot, and a third slot that are connected to each other. The first slot and the third slot are symmetrically arranged about the first center line and extend away from the first center line in the direction from the rotor core axis toward the edge of the rotor core along the extension direction of the first center line. The two ends of the second slot are respectively connected to the ends of the first slot and the third slot that are close to the rotor core axis.

[0007] The second slot has an intersection point with both the first and third slots on one side near the edge of the rotor core, and the angle formed by the two intersection points and the center of the rotor core is α2; the first and third slots each have a second endpoint near the first centerline at their ends away from the second slot, and the angle formed by the two second endpoints and the center of the rotor core is α3; and

[0008] A stator is fitted around the outer periphery of the rotor. The stator includes a stator core and a stator winding. The stator core includes a stator yoke and stator teeth. A plurality of 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 width of the stator slot opening is W. The inner radius of the stator core is R.

[0009] in, ,and .

[0010] In one embodiment, 0.07 ≤ α1 / α3 ≤ 0.11.

[0011] In one embodiment, 0.40 ≤ α2 / α3 ≤ 0.46.

[0012] In one embodiment, the distance from the side of the harmonic aperture closest to the edge of the rotor core to the outer peripheral wall of the rotor core is d1, and the distance from the end of the first slot and the third slot away from the second slot to the outer peripheral wall of the rotor core is d2. d1 and d2 satisfy: d1 > 0, d2 > 0, and 0.45 d1≤d2≤1.38 d1.

[0013] In one implementation, 10 ≤ 2P ≤ 12.

[0014] In one implementation, 15 ≤ Q ≤ 18.

[0015] In one embodiment, the number of phases of the motor is m, and the number of slots per pole per phase of the motor is q, where q = Q / 2mP, and q satisfies: 0 < q < 1.

[0016] In one embodiment, the greatest common divisor of the number of stator slots Q and the number of rotor poles P satisfies: 5 ≤ GCD(Q, P) ≤ 6.

[0017] The present invention also proposes a compressor, including the aforementioned motor.

[0018] The present invention also proposes a refrigeration device, including the aforementioned compressor.

[0019] The technical solution of the present invention provides a harmonic aperture between two adjacent mounting slots and defines... This is achieved by controlling the total magnetic field modulation formed by the harmonic aperture and mounting slot, matching its phase with the magnetic permeability harmonics caused by the stator teeth, and actively canceling the main low-order harmonics such as the 5th and 7th orders, thereby effectively suppressing inter-pole harmonics and reducing motor vibration noise. Simultaneously, by limiting... Further optimization of the magnetic field modulation of each stator tooth by the mounting slot and harmonic apertures on both sides within each pole range ensures a reasonable allocation of circumferential angle resources between the harmonic apertures and the mounting slots within a limited space. This guarantees the main magnetic flux output capability while avoiding a decrease in rotor core strength or magnetic flux leakage due to excessively large mounting slots and harmonic apertures. Through the combined effect of these two constraints, the air gap magnetic flux density waveform becomes closer to sinusoidal, harmonics are effectively suppressed, the back electromotive force distortion rate is reduced, and the torque output is more stable, thereby reducing vibration and noise during motor operation. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the motor provided by the present invention;

[0022] Figure 2 for Figure 1 A magnified view of a section at point A in the middle;

[0023] Figure 3 The proportions of the 5th and 7th harmonics vary with Trend chart of changes;

[0024] Figure 4 The rate of change of motor output power with Trend chart of changes;

[0025] Figure 5 This is a graph showing the trend of torque pulsation and the rate of change of motor output power as a function of α1 / α3.

[0026] Figure 6 This is a graph showing the trend of torque pulsation and the rate of change of motor output power as a function of α2 / α3.

[0027] Explanation of icon numbers:

[0028] 100, Rotor core; 200, Stator core; 110, Mounting slot; 111, First slot; 112, Second slot; 113, Third slot; 114, Intersection point; 115, Second end point; 120, Harmonic hole; 121, First end point; 210, Stator yoke; 220, Stator tooth; 230, Stator slot; q1, First center line; q2, Second center line; O, Center.

[0029] 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

[0030] 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.

[0031] 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.

[0032] 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.

[0033] This invention proposes an electric motor.

[0034] Please see Figure 1 and Figure 2 In one embodiment of the present invention, the motor includes a rotor and a stator. The rotor includes a rotor core 100 and a permanent magnet. The rotor core 100 has a first center line q1 and a second center line q2 extending radially therefrom. The rotor core 100 is provided with a plurality of mounting slots 110 spaced apart along its circumference. The permanent magnet is embedded in the mounting slots 110 and has 2P magnetic poles formed in the circumference of the rotor core 100. Two adjacent mounting slots 110 are symmetrical about the second center line q2. A harmonic hole 120 is provided between two adjacent mounting slots 110. Each harmonic hole 120 is symmetrical about the second center line q2. The side of the harmonic hole 120 near the edge of the rotor core 100 has two first endpoints 121 away from the second center line q2. The angle formed by the two first endpoints 121 and the center O of the rotor core 100 is α1.

[0035] The mounting slot 110 includes a first slot 111, a second slot 112, and a third slot 113 that are connected to each other. The first slot 111 and the third slot 113 are symmetrically arranged about the first center line q1 and extend away from the first center line q1 in the direction from the axis of the rotor core 100 toward the edge of the rotor core 100 along the extension direction of the first center line q1. The two ends of the second slot 112 are respectively connected to the ends of the first slot 111 and the third slot 113 that are close to the axis of the rotor core 100.

[0036] The second slot 112 has an intersection point 114 with the first slot 111 and the third slot 113 on one side near the edge of the rotor core 100. The angle formed by the two intersection points 114 and the center O of the rotor core 100 is α2. The ends of the first slot 111 and the third slot 113 away from the second slot 112 have second endpoints 115 near the first center line q1. The angle formed by the two second endpoints 115 and the center O of the rotor core 100 is α3.

[0037] The stator is sleeved on the outer periphery of the rotor. The stator includes a stator core 200 and a stator winding. The stator core 200 includes a stator yoke 210 and stator teeth 220. Multiple stator teeth 220 are spaced along the inner periphery of the stator yoke 210. A stator slot 230 is formed between two adjacent stator teeth 220. The number of stator slots 230 is Q, the width of the slot opening of the stator slot 230 is W, and the inner radius of the stator core 200 is R.

[0038] in, ,and .

[0039] Specifically, the rotor includes a rotor core 100 and permanent magnets embedded therein. The rotor core 100 has 2P magnetic poles along its circumference, where P is the number of pole pairs. Each magnetic pole corresponds to a mounting slot 110 for mounting a permanent magnet. The first center line q1 and the second center line q2 serve as geometric reference lines for the rotor core 100, extending radially along the rotor core 100 respectively, and are used to define the symmetrical relationship between the mounting slot 110 and the harmonic aperture 120.

[0040] Each mounting slot 110 includes a first slot 111, a second slot 112, and a third slot 113. The first slot 111 and the third slot 113 are symmetrical about a first center line q1 and extend along the direction of the first center line q1 from a position close to the axis of the rotor core 100 towards the outer edge of the rotor core 100, gradually moving away from the first center line q1, forming an outwardly flared structure. This helps improve the symmetry of the magnetic field distribution and reduce local magnetic saturation. The second slot 112 serves as a connecting channel between the first slot 111 and the third slot 113. Its position is closer to the axis of the rotor core 100 than the first slot 111 and the third slot 113. The magnetic path length in the area near the second slot 112 is shorter, and the magnetic reluctance is lower. The second slot 112 effectively widens the initial path of magnetic flux from the permanent magnet to the air gap, helping to evenly distribute the magnetic flux to the first slot 111 and the third slot 113 on both sides, avoiding excessive concentration of magnetic flux, thereby reducing local magnetic saturation and improving magnetic energy utilization.

[0041] α1 reflects the circumferential angular range occupied by the harmonic aperture 120 on the outer edge of the rotor. Its size directly affects the air gap permeability. The greater the distance between the two sides of the harmonic aperture 120 near the edge of the rotor core 100, the larger α1 is. By controlling α1, spatial harmonics of a specific order can be effectively weakened, thereby reducing the cogging torque caused by changes in permeability. α1 is measured as follows: find two first endpoints 121 on one side of the harmonic aperture 120 near the edge of the rotor core 100, and measure the angle between the two first endpoints 121 and the line connecting them to the center O of the rotor core 100 using a protractor or optical measuring instrument to obtain α1.

[0042] α2 characterizes the circumferential angle range occupied by the second slot 112 on the outer edge of the rotor. Controlling α2 helps to adjust the concentration of the magnetic flux path, optimize the main magnetic flux distribution, and suppress leakage flux. The positions of the second endpoints 115 of the first slot 111 and the third slot 113 remain unchanged. The closer the second slot 112 is to the edge of the rotor core 100 along the extension direction of the first center line q1, the greater the distance between the two intersection points 114, and thus the larger α2 is. α2 is measured as follows: Locate the two intersection points 114 of the second slot 112 near the edge of the rotor core 100 with the first slot 111 and the third slot 113 in the mounting slot 110. Measure the angle between these two intersection points 114 and the line connecting the center O of the rotor core 100 using a protractor or optical measuring instrument to obtain α2.

[0043] α3 reflects the circumferential angular range occupied by the entire mounting slot 110 on the outer edge of the rotor, directly affecting the width of the permanent magnet's external magnetomotive force distribution and the fundamental amplitude and harmonic proportion of the air gap magnetic flux density waveform. The intersection point 114 of the first slot 111, the third slot 113, and the second slot 112 remains unchanged. The greater the distance between the end of the first slot 111 and the third slot 113 furthest from the second slot 112 and the first center line q1, the larger α3 becomes. α3 is measured as follows: Find two second endpoints 115 near the first center line q1 at the ends of the first slot 111 and the third slot 113 furthest from the second slot 112. Measure the angles between the two second endpoints 115 and the lines connecting them to the center O of the rotor core 100 using a protractor or optical measuring instrument. By rationally designing the relative relationships of the three angles α1, α2, and α3, the air gap magnetic field waveform can be shaped to be closer to a sinusoidal distribution, thereby reducing the high-order harmonic components in the back electromotive force.

[0044] Q represents the number of stator slots 230, which can be obtained by counting directly.

[0045] W is the width of the stator slot 230 opening, which can be measured using calipers or a microscope to determine the distance between opposite sides of the stator slot 230 opening. For example, when measuring the width of the stator slot 230 opening using calipers, the slot opening must be cleaned and a knife-edge external measuring jaw should be selected. The tip of the measuring jaw should be vertically inserted into the bottom of the slot opening, ensuring contact with the stator cores 200 on both sides. At least three points (upper, middle, and lower) along the axial direction of the stator cores 200 should be selected for measurement; the average of these stable readings is the width W of the stator slot 230 opening.

[0046] R is the inner radius of the stator core 200, which can be obtained by measuring the inner diameter of the stator core 200 and taking half of that value. For example, when measuring the inner radius of the stator core 200 using vernier calipers, insert the inner measuring jaws into the inner circle of the stator core 200 and measure the diameter multiple times at different axial positions and in mutually perpendicular directions on the same cross section; take the average of all the measured diameter values, and then divide by 2 to obtain the accurate inner radius value R of the stator core 200. π is the mathematical constant pi.

[0047] make , This is a dimensionless ratio, representing the sum of the pole arcs of the rotor-side harmonic aperture 120 and the permanent magnet, to the sum of the pole arcs of the stator-side armature magnetic field stator teeth 220. Limiting this ratio within a certain range ensures effective harmonic suppression. Specifically, 2πR is the inner circumference of the stator core 200. It is the total width of all 230 stator slots; It is the ratio of the sum of the widths of all stator slots 230 to the inner circumference of the stator core 200; It is the ratio of the sum of the widths of all stator teeth 220 to the inner circumference of the stator core 200. The stator teeth 220 are the part that actually passes through the magnetic flux, that is, this parameter reflects the magnetic flux throughput of the stator. It is the proportion of the pole arc of all stator teeth 220 in the circumferential direction of the stator core 200, reflecting the effective angle at which magnetic flux can actually pass through the stator side.

[0048] The equivalent magnetic pole curvature under the combined action of the harmonic aperture 120, the first slot 111, and the third slot 113 is characterized. It is worth noting that the rotor's magnetic flux mainly passes through the region near the harmonic aperture 120, the first slot 111, and the third slot 113. Therefore, by optimizing and controlling the pole curvature ratio of the harmonic aperture 120, the first slot 111, and the third slot 113, harmonics can be effectively suppressed. This reflects the total effective harmonic modulation angle determined by the harmonic aperture 120, the first slot 111, and the third slot 113 under each magnetic pole, demonstrating the rotor structure's ability to spatially modulate the air gap magnetic field. In the field of electrical engineering, "modulation" specifically refers to the process of altering the spatial distribution of air gap permeability or magnetomotive force through structural design, thereby affecting the waveform of the air gap magnetic field. Specifically, in this invention, "modulation" involves actively intervening in the magnetic field distribution through structural design (mounting slot 110 and harmonic aperture 120), adjusting the original back electromotive force containing more high-order harmonics to a waveform closer to a sine wave.

[0049] By controlling To optimize the magnetic pole arc length, concentrate the main magnetic flux and reduce leakage flux; in conjunction with the harmonic aperture 120 to weaken specific spatial harmonics (such as the 5th and 7th), the suppression of low-order magnetomotive force harmonics is achieved, thereby reducing back electromotive force distortion, reducing the peak value of tooth cogging torque, and thus reducing vibration noise.

[0050] Please refer to Table 1 and Figure 3 Table 1 shows the proportions of the 5th and 7th harmonics as a function of... The table of changing relationships Figure 3 The proportions of the 5th and 7th harmonics vary with A trend chart showing the changes.

[0051] Table 1: Proportion of 5th and 7th harmonics Relationship table of changes

[0052]

[0053] Figure 3 The vertical axis represents the combined content of the 5th and 7th harmonics relative to the fundamental frequency. This chart shows the percentage of the 5th and 7th harmonics in the motor (expressed as a percentage of the fundamental frequency amplitude) as... The trend of change. The curve in the graph shows a clear monotonically decreasing trend, indicating that as... With the increase of [the number of harmonics], the proportion of the 5th and 7th harmonics decreased significantly.

[0054] when When the value increased from 0.43 to 0.55, the proportion of harmonics decreased significantly from approximately 6.43% to approximately 2.73%, a reduction of over 57%, indicating that the harmonic suppression effect was most significant during this stage. When the value is increased from 0.55 to 0.61, the proportion of harmonics tends to stabilize, fluctuating between 2.72% and 2.73%, with very small changes, indicating that it is close to the saturation zone of harmonic suppression.

[0055] Understandably, increase It can be increased and or reduce .when When the value is below 0.45, the proportion of harmonics is relatively high (e.g., 6.43% at 0.43), indicating that the modulation capability of the rotor structure is insufficient and the suppression effect on the 5th and 7th harmonics is poor; when When the value is above 0.60, although the proportion of harmonics is already very low, it continues to increase. The harmonic suppression benefit (if it exceeds 0.60) approaches zero, and may lead to weakening of the main magnetic flux, increased core loss, or increased manufacturing difficulty due to overmodulation. Furthermore, increasing... and To increase The increased size of the harmonic hole 120 and the mounting groove 110 will reduce the mechanical strength of the rotor.

[0056] The 5th and 7th harmonics are the main causes of cogging torque and torque pulsation in permanent magnet synchronous motors. This can be addressed by precisely controlling the ratio of rotor structural parameters to stator structural parameters. This can effectively optimize the spatial distribution of the air gap magnetic field, causing the rotor to generate reverse harmonic components with opposite phase and similar amplitude to the harmonics generated by the stator at specific positions. This achieves mutual cancellation of spatial harmonics, effectively suppressing harmonics and reducing the cogging torque and torque pulsation of the motor, thereby reducing the vibration noise during motor operation.

[0057] During motor operation, each stator tooth 220 sequentially passes through different magnetic pole regions of the rotor. When a stator tooth 220 is directly facing a rotor magnetic pole, it corresponds to the rotor structure within that magnetic pole range, including the mounting slot 110, harmonic aperture 120, etc. When a stator tooth 220 crosses the boundary region between two magnetic poles, the rotor magnetic circuit it faces actually includes the harmonic aperture 120 of the left magnetic pole, the mounting slot 110 of the current magnetic pole, and a portion of the harmonic aperture 120 of the right magnetic pole. However, since the rotor and stator move relative to each other during operation, it can be simplified to understand that the equivalent magnetic circuit corresponding to each stator tooth 220 includes a mounting slot 110 and the harmonic aperture 120 structures located on both sides of it.

[0058] make , It is a dimensionless ratio. It reflects the pole arc of a stator tooth 220 modulated by the structure of the mounting slot 110 and the harmonic aperture 120 located on both sides of the unit magnetic pole. This represents the angle of effective magnetic flux passing through a stator tooth 220 on the stator circumference.

[0059] By incorporating harmonic holes 120 on the rotor and optimizing the structure of the mounting slot 110, both main magnetic flux utilization and electromagnetic harmonic suppression can be improved. This optimization effect can be expressed as a dimensionless ratio. To quantify this, the harmonic aperture 120, acting as a magnetic reluctance barrier, can locally alter the air gap magnetic permeability distribution, generating reverse harmonic components to counteract the 5th and 7th order spatial harmonics caused by stator slotting. Increasing α1 and α3 helps optimize the magnetic flux path, reduce leakage flux, allow more magnetic flux to effectively pass through the air gap, and improve the utilization rate of the main magnetic flux. The larger the value, the more complete the modulation structure and the stronger the harmonic cancellation capability. However, it is limited by the physical space and mechanical strength of each pole of the rotor and cannot be increased indefinitely. Otherwise, the rotor may be damaged due to insufficient mechanical strength caused by an excessively narrow iron core bridge, or the main magnetic flux may decrease due to a reduction in the volume of the permanent magnet, or the magnetic circuit may become too complex, potentially introducing new higher-order harmonics or increasing iron losses. However, if... If the value is too small, the harmonic suppression effect will be poor, and the motor performance will decrease.

[0060] By controlling This allows for optimal matching between the rotor's harmonic modulation capability and the 220-tooth distribution of a single stator tooth. Within this range, sufficient main magnetic flux output is guaranteed while effectively reducing air gap magnetic field distortion, lowering cogging torque and torque pulsation, improving motor running stability and efficiency, and balancing electromagnetic performance and structural reliability.

[0061] Please refer to Table 2 and Figure 4 Table 2 shows the rate of change of motor output power as a function of... The table of changing relationships Figure 4 The rate of change of motor output power with A trend chart showing the changes.

[0062] Table 2: Rate of change of motor output power with... Relationship table of changes

[0063]

[0064] Figure 4 The vertical axis in the figure represents the rate of change of motor output power, where is the value of . The motor's output power at a value of 7.3 was used as the optimization benchmark. Figure 4 Showing different The change in the output power of the lower motor relative to the reference value.

[0065] As can be seen from the figure, As the value gradually increases from 7.3 to 7.9, the motor's output power shows an upward trend. The peak value (102.80%) was reached at 7.9, indicating that the magnetic field modulation effect of the rotor structure was optimal at this point, with high main magnetic flux utilization and good harmonic suppression, and the electromagnetic performance was fully released. As the power continues to increase, the output power of the motor shows a decreasing trend. When the value is increased to 8.5, the motor's output power drops to 99.3%, indicating that the value is too high. This can lead to insufficient width of the rotor core bridge or a reduction in the effective volume of the permanent magnet, resulting in magnetic circuit saturation or weakening of the main magnetic flux, thereby reducing output capacity.

[0066] when Between 7.5 and 8.2, the motor output power is higher than the reference value, which ensures good harmonic suppression effect and avoids performance loss caused by over-optimization of structure, thus achieving the best balance between electromagnetic performance and structural feasibility.

[0067] The technical solution of the present invention provides a harmonic aperture 120 between two adjacent mounting slots 110 and defines... This is achieved by controlling the total magnetic field modulation formed by the harmonic aperture 120 and the mounting slot 110, making it phase-matched with the magnetic permeability harmonics caused by the stator teeth 220, thus actively canceling the main low-order harmonics such as the 5th and 7th orders, effectively suppressing inter-pole harmonics and reducing motor vibration noise. Simultaneously, by limiting... Further optimization of the magnetic field modulation of each stator tooth 220 corresponding to the mounting slot 110 and the harmonic apertures 120 on both sides within each pole range ensures a reasonable allocation of the circumferential angle resources of the harmonic apertures 120 and the mounting slot 110 within a limited space. This guarantees the main magnetic flux output capability while avoiding a decrease in the strength of the rotor core 100 or magnetic flux leakage due to excessively large mounting slots 110 and harmonic apertures. Through the combined effect of these two constraints, the air gap magnetic flux density waveform becomes closer to sinusoidal, harmonics are effectively suppressed, the back electromotive force distortion rate is reduced, and the torque output is more stable, thereby reducing the vibration and noise during motor operation.

[0068] In one implementation, please refer to Figure 2 , 0.07≤α1 / α3≤0.11.

[0069] Please refer to Table 3 and Figure 5 Table 3 shows the relationship between torque ripple and the rate of change of motor output power as a function of α1 / α3. Figure 5 This is a trend graph showing the torque pulsation and the rate of change of motor output power as a function of α1 / α3.

[0070] Table 3: Relationship between torque ripple and motor output power change rate as a function of α1 / α3

[0071]

[0072] By limiting 0.07≤α1 / α3≤0.11, the relative dimensional relationship between the harmonic hole 120 and the mounting slot 110 in the rotor structure is optimized to achieve more efficient harmonic suppression and magnetic field balance.

[0073] from Figure 5 As can be seen, one of the curves represents torque ripple. Torque ripple refers to the periodic fluctuations or undulations in the output torque of an electric motor or other rotating machinery around its average value during operation. Torque ripple is quantified as a percentage: Torque Ripple (%) = . It is the maximum torque within one cycle. It is the minimum torque within one cycle. This is the average torque within that cycle. The torque pulsation first decreases and then increases as α1 / α3 increases; the other curve represents the rate of change of the motor output power relative to the reference value, and the rate of change of the motor output power first increases and then decreases as α1 / α3 increases.

[0074] When α1 / α3 is less than 0.07, the harmonic aperture 120 is relatively small, resulting in insufficient modulation capability and severe distortion of the air gap magnetic field. This leads to ineffective suppression of cogging torque, with torque ripple reaching approximately 15.30%. Simultaneously, the output power is low due to the unoptimized main flux path. As α1 / α3 increases to between 0.07 and 0.11, the size of the harmonic aperture 120 increases moderately, significantly enhancing its spatial modulation effect. This effectively suppresses low-order harmonics, reducing torque ripple to 9.4% when α1 / α3 = 0.11. Simultaneously, the motor output power continuously increases within this range, reaching 102.1% when α1 / α3 = 0.11, indicating that the harmonic suppression effect and main flux utilization efficiency are optimally balanced at this point. When α1 / α3 exceeds 0.11, the harmonic aperture 120 becomes too large, weakening the mechanical strength of the rotor core 100 and potentially causing magnetic circuit saturation or increased leakage flux, leading to a decrease in main flux utilization and consequently, a reduction in output power.

[0075] Therefore, by limiting 0.07≤α1 / α3≤0.11, while ensuring the effective output of the permanent magnet, the harmonic aperture 120 is endowed with appropriate and precise modulation capability. This ensures that the harmonic aperture 120 can effectively participate in the periodic modulation of the air gap magnetic permeability to effectively suppress harmonics, while not damaging the structural strength of the rotor and the integrity of the main magnetic circuit due to excessive aperture. This achieves the triple goals of weakening harmful harmonics, strengthening the main magnetic flux, and ensuring structural strength, ensuring that the motor operates efficiently while improving the smoothness of motor operation and effectively reducing motor vibration and noise.

[0076] In one implementation, please refer to Figure 2 , 0.40≤α2 / α3≤0.46.

[0077] Please refer to Table 4 and Figure 6 Table 4 shows the relationship between torque ripple and the rate of change of motor output power as a function of α1 / α3. Figure 6 This is a trend graph showing the torque pulsation and the rate of change of motor output power as a function of α2 / α3.

[0078] Table 4: Relationship between torque ripple and motor output power change rate with α2 / α3

[0079]

[0080] By limiting 0.40≤α2 / α3≤0.46, the relative size relationship between the second slot 112 and the overall mounting slot 110 in the rotor structure is optimized to achieve more efficient harmonic suppression and magnetic field balance.

[0081] from Figure 6As can be seen, one curve represents torque pulsation (expressed as a percentage), which first decreases and then increases with the increase of α2 / α3; the other curve represents the rate of change of motor output power relative to the reference value, which first increases and then decreases with the increase of α2 / α3.

[0082] When α2 / α3 is less than 0.40 (e.g., 0.38), the second slot 112 is relatively narrow, resulting in an obstructed path for magnetic flux during its distribution to both sides. This leads to localized magnetic circuit concentration, which can easily cause rotor core 100 saturation and magnetic field distortion, resulting in torque pulsation as high as 13.2%. Simultaneously, the main magnetic flux utilization rate is low, with output power at only 97%. As α2 / α3 increases to between 0.40 and 0.46, the width of the second slot 112 adapts to the total opening of the mounting slot 110, allowing magnetic flux to be distributed more evenly to the first slot 111 and the third slot 113. This effectively reduces harmonic disturbances caused by uneven magnetic reluctance, significantly decreasing torque pulsation to 8.46% when α2 / α3 = 0.42. At the same time, the motor output power continuously increases within this range. When α2 / α3 = 0.44, the rate of change in motor output power reaches 101.13%, indicating that the magnetic flux path is optimized, the main magnetic flux utilization efficiency is highest, and the electromagnetic performance is optimal. When α2 / α3 exceeds 0.46 (e.g., 0.5), the second slot 112 becomes relatively too wide. Although this further improves the magnetic flux distribution, it leads to a reduction in material in the bridge region of the rotor core 100, a decrease in mechanical strength, and may introduce additional leakage flux or magnetic circuit nonlinearity, which weakens the main magnetic flux and causes the motor output power change rate to drop to 97.42%.

[0083] Therefore, by limiting 0.40≤α2 / α3≤0.46, the second slot 112 can effectively guide the magnetic flux generated by the permanent magnet to be evenly distributed to the first slot 111 and the third slot 113 on both sides, avoiding the occurrence of local magnetic saturation and improving the magnetic energy utilization rate; it can also ensure that the magnetic flux maintains a relatively consistent distribution during the transmission of magnetic flux from the inside to the outside, which helps to form a smoother air gap magnetic field waveform; it can also effectively reduce the lateral leakage magnetic flux at the end of the permanent magnet, allowing more magnetic flux to be guided to the air gap through the first slot 111 and the third slot 113, enhancing the strength and stability of the main magnetic flux, thereby improving the overall output capability of the motor; in addition, it can ensure that the rotor has sufficient mechanical strength to prevent deformation or damage caused by centrifugal force during high-speed rotation, while maintaining good electromagnetic performance, thus achieving a balance between magnetic flux uniformity, main magnetic flux strength and structural reliability, effectively reducing cogging torque and vibration noise, and improving the output capability of the motor.

[0084] In one implementation, please refer to Figure 2The distance from one side of the harmonic aperture 120 near the edge of the rotor core 100 to the outer peripheral wall of the rotor core 100 is d1. The distance from the end of the first slot 111 and the third slot 113 away from the second slot 112 to the outer peripheral wall of the rotor core 100 is d2. d1 and d2 satisfy: d1 > 0, d2 > 0, and 0.45 d1≤d2≤1.38 d1.

[0085] d1 is the radial distance from the harmonic aperture 120 to the outer circle of the rotor core 100. The distance from any point on the side of the harmonic aperture 120 closest to the edge of the rotor core 100 to the outer peripheral wall of the rotor core 100 is the same. d1 is essentially the material thickness of the rotor core 100 retained between the harmonic aperture 120 and the air gap, also known as the "magnetic bridge thickness" or "shielding layer thickness," which directly affects the mechanical reliability of the rotor under high-speed rotation.

[0086] d1 can be measured using a height gauge: Place the rotor core 100 flat on a reference platform, using the platform as the reference zero point. First, use the height gauge probe to contact the highest point of the rotor's outer peripheral wall and record the reading H1; then move the probe to the lowest point of the edge of the harmonic aperture 120 closest to the outer peripheral wall of the rotor core 100 and record the reading H2. The difference between the two readings is the required distance: d1 = H1 - H2.

[0087] d2 is the radial distance from the end of the mounting groove 110 to the outer circle of the rotor core 100. The distance from any point on the side of the end of the mounting groove 110 near the edge of the rotor core 100 to the outer peripheral wall of the rotor core 100 is the same. In essence, d2 is the thickness of the material of the rotor core 100 between the outermost end of the mounting groove 110 and the air gap, which is related to the installation depth of the permanent magnet and the main magnetic flux path.

[0088] d2 can be measured using a height gauge: Place the rotor core 100 flat on the reference platform and set the zero point. First, use a probe to measure the highest point reading H1 on the outer periphery of the rotor; then locate the lowest point at the bottom of the end of the first slot 111 or the third slot 113 furthest from the second slot 112, and record the reading H3. The difference between the two readings is the distance from the end of the corresponding slot to the outer periphery of the rotor core 100: d2 = H1 - H3.

[0089] When d2 When d1 is small, it means that d2 is very small. The mounting slot 110 is very close to the outer circle of the rotor core 100. Although it seems to enhance the surface magnetic pole effect, it actually causes the magnetic flux to be highly concentrated at the pole tip, which in turn leads to an increase in local iron loss, a spike in the air gap magnetic flux waveform, and an increase in higher harmonics. At the same time, since d1 is relatively larger, the harmonic aperture 120 is far from the air gap, and the modulation effect of the harmonic aperture 120 is shielded, resulting in severe back electromotive force distortion and an increase in noise.

[0090] When d2 When d1 is large, it means d2 is very large, resulting in a shallow embedding of the permanent magnet and a short main magnetic circuit. However, if d1 is very small, the harmonic aperture 120 will be almost close to the outer circumference of the rotor core 100, meaning the magnetic bridge is extremely thin. Consequently, the rotor core 100 around the harmonic aperture 120 is prone to magnetic saturation, and the harmonic aperture 120 will lose its modulation capability. It may even form an unexpected magnetic short-circuit path, causing stray field coupling between adjacent magnetic poles. Furthermore, the thin magnetic bridge is prone to breakage under high-speed rotation, leading to decreased motor reliability and increased vibration and noise instead of decreased performance.

[0091] Therefore, by limiting d1 > 0, d2 > 0, and 0.45 d1≤d2≤1.38 To avoid an excessive difference between d1 and d2, the harmonic aperture 120 and the mounting slot 110 are radially coordinated, maintaining sufficient mechanical bridge strength to ensure rotor safety while optimizing the magnetic circuit path, improving main magnetic flux output, and enhancing harmonic suppression capability. Experiments show that this design effectively reduces torque ripple and improves motor operating stability, making it suitable for compressor applications requiring high speed and high reliability.

[0092] In one implementation, please refer to Figure 1 , 10≤2P≤12.

[0093] The total number of magnetic poles in a permanent magnet synchronous motor is limited to 10 ≤ 2P ≤ 12, meaning the motor can have 10, 11, or 12 poles. In permanent magnet synchronous motors, the number of poles affects the spatial distribution frequency of the air gap magnetic field, the back electromotive force waveform, torque density, and cogging torque characteristics. When 2P < 10, the pole pitch is large, the magnetic field changes slowly, resulting in a lower back electromotive force frequency. This limits the motor's output power at the same speed, and a low pole number easily leads to larger torque pulsations and vibration noise. Conversely, when 2P > 12, the pole pitch is too small, and the interaction between the stator teeth and the rotor structure becomes more frequent. While this improves torque smoothness, it increases rotor core losses, manufacturing difficulty, and high-frequency harmonic content, while also requiring a faster controller response.

[0094] By limiting 10≤2P≤12, on the one hand, it helps to refine the magnetic field modulation period, making the air gap magnetic flux density distribution more sinusoidal, effectively suppressing low-order harmonics such as the 5th and 7th, and reducing cogging torque and operating noise; on the other hand, it can ensure reasonable slot-pole matching, reduce the risk of harmonic resonance, reduce winding leakage inductance and copper loss, and improve motor efficiency and power density.

[0095] In one implementation, please refer to Figure 1 , 15≤Q≤18.

[0096] The number of stator slots 230 in the motor is limited to satisfy 15 ≤ Q ≤ 18, meaning that 15 to 18 stator slots 230 are evenly arranged along the inner circumference of the stator core 200 for housing the stator windings. In a permanent magnet synchronous motor, the number of stator slots 230 Q and the rotor pole number 2P together determine the number of slots per pole per phase, thus affecting the magnetic field modulation effect and winding distribution characteristics. Combining the preferred pole number combination of 10 ≤ 2P ≤ 12, a good slot-pole match can be achieved when 15 ≤ Q ≤ 18. For example, Q = 18 and 2P = 12 form an integer slot winding, which has good winding symmetry and a mature manufacturing process; Q = 15 or 18 and 2P = 10 form a fractional slot winding, which helps to disperse magnetomotive force harmonics and reduce cogging torque. If Q < 15, the slot spacing of stator slot 230 is too large, leading to discontinuous changes in air gap magnetic permeability, severe distortion of the back electromotive force waveform, high harmonic content, and a significant increase in vibration and noise. If Q > 18, the slot density of stator slot 230 is too high, which not only increases the difficulty of the stator core 200 lamination process but may also trigger high-frequency electromagnetic resonance. Simultaneously, the slot leakage inductance increases, affecting motor efficiency and dynamic response. By limiting Q to 15 ≤ Q ≤ 18, the spatial matching relationship with the rotor harmonic aperture 120 and mounting slot 110 structure can be optimized while ensuring good electromagnetic performance.

[0097] In one embodiment, the number of phases of the motor is m, and the number of slots per pole per phase of the motor is q, where q = Q / 2mP, and q satisfies: 0 < q < 1.

[0098] The motor has m phases, Q stator slots (230), and P pole pairs. The number of slots per pole per phase is defined as q = Q / 2mP, where q satisfies 0 < q < 1. This means the motor uses a fractional-slot winding structure, and the number of slots per pole per phase is less than one slot. The number of slots per pole per phase, q, is one of the core indicators in the motor's electromagnetic design, directly affecting the harmonic content of the air gap magnetomotive force, cogging torque, winding distribution factor, and electromagnetic noise characteristics. When q ≥ 1, it is an integer-slot winding, which has good winding symmetry and is simple to manufacture, but it easily generates strong low-order magnetomotive force harmonics, and the cogging period is fixed in relation to the pole pitch, which is not conducive to harmonic suppression. When 0 < q < 1, it is a typical fractional-slot winding.

[0099] The fractional slot structure allows for a non-common multiple slot-pole match between the number of stator slots 230 and the number of rotor poles, effectively dispersing the spatial harmonic energy of the air gap magnetic field and preventing harmonic concentration and superposition, thereby significantly reducing cogging torque and torque pulsation. Secondly, such windings typically have shorter end lengths, reducing copper losses and improving motor efficiency and power density. Furthermore, the q<1 structure helps achieve more uniform magnetic field modulation, working synergistically with the rotor topology features such as the harmonic aperture 120 and multi-segment mounting slot 110 to further optimize the air gap magnetic flux density waveform, making it closer to a sinusoidal distribution and suppressing the 5th and 7th harmonic components in the back electromotive force. Simultaneously, q>0 ensures that each phase has a conductor participating in operation under each magnetic pole, maintaining basic electromagnetic conversion capability.

[0100] In one embodiment, the greatest common divisor of the number of stator slots 230 Q and the number of rotor poles P satisfies: 5≤GCD(Q, P)≤6.

[0101] In permanent magnet synchronous motors, the relative motion between the stator slots and the rotor poles generates periodic changes in magnetic permeability, whose harmonic characteristics are closely related to the common divisor of Q and P. GCD(Q, P) reflects the minimum repetition period of the electromagnetic interaction between the stator and rotor. When GCD(Q, P) is too small (e.g., 1 or 2), it indicates a short engagement period between the stator slot 230 and the pole, resulting in a low cogging effect repetition frequency, which easily excites low-order mechanical resonance, leading to significant vibration and noise. When GCD(Q, P) is too large (e.g., ≥7), it indicates a long engagement period between the stator slot 230 and the pole, which complicates the winding design or introduces new low-frequency disturbances. By limiting GCD(Q, P) to 5 ≤ GCD(Q, P) ≤ 6, the motor has a longer and more stable electromagnetic periodic structure, enhancing the spatial symmetry of electromagnetic force waves and effectively dispersing harmonic energy, which helps reduce cogging torque and torque pulsation.

[0102] The present invention also proposes a compressor, which includes a motor. The specific structure of the motor is as described in the above embodiments. Since the compressor 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.

[0103] The present invention also proposes a refrigeration device, which includes a compressor. The specific structure of the compressor is as described in the above embodiments. Since the refrigeration device 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.

[0104] 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. An electric motor, characterized in that, include: The rotor includes a rotor core and a permanent magnet. The rotor core has a first center line and a second center line extending radially therein. The rotor core is provided with a plurality of mounting slots spaced apart along its circumference. The permanent magnet is embedded in the mounting slots and has 2P magnetic poles formed in the circumference of the rotor core. Two adjacent mounting slots are symmetrical about the second center line. A harmonic hole is provided between two adjacent mounting slots. Each harmonic hole is symmetrical about the second center line. The side of the harmonic hole near the edge of the rotor core has two first endpoints away from the second center line. The angle formed by the two first endpoints and the center of the rotor core is α1. The mounting slot includes a first slot, a second slot, and a third slot that are connected to each other. The first slot and the third slot are symmetrically arranged about the first center line and extend away from the first center line in the direction from the rotor core axis toward the edge of the rotor core along the extension direction of the first center line. The two ends of the second slot are respectively connected to the ends of the first slot and the third slot that are close to the rotor core axis. The second slot has an intersection point with both the first and third slots on one side near the edge of the rotor core, and the angle formed by the two intersection points and the center of the rotor core is α2; the first and third slots each have a second endpoint near the first centerline at their ends away from the second slot, and the angle formed by the two second endpoints and the center of the rotor core is α3; and A stator is fitted around the outer periphery of the rotor. The stator includes a stator core and a stator winding. The stator core includes a stator yoke and stator teeth. A plurality of 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 width of the stator slot opening is W. The inner radius of the stator core is R. in, ,and .

2. The motor as described in claim 1, characterized in that, 0.07≤α1 / α3≤0.11。 3. The motor as described in claim 1, characterized in that, 0.40≤α2 / α3≤0.46。 4. The motor as described in claim 1, characterized in that, The distance from the edge of the harmonic aperture closest to the rotor core to the outer peripheral wall of the rotor core is d1, and the distance from the end of the first slot and the third slot away from the second slot to the outer peripheral wall of the rotor core is d2. d1 and d2 satisfy: d1 > 0, d2 > 0, and 0.45 d1≤d2≤1.38 d1.

5. The motor as described in claim 1, characterized in that, 10≤2P≤12。 6. The motor as described in claim 5, characterized in that, 15≤Q≤18。 7. The motor as described in claim 6, characterized in that, The number of phases of the motor is m, and the number of slots per pole per phase of the motor is q, where q = Q / 2mP, and q satisfies: 0 < q < 1.

8. The motor as described in claim 6, characterized in that, The greatest common divisor of the number of stator slots Q and the number of rotor poles P satisfies: 5≤GCD(Q, P)≤6.

9. A compressor, characterized in that, Including the motor as described in any one of claims 1 to 8.

10. A refrigeration device, characterized in that, Includes the compressor as described in claim 9.

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