Motors, compressors and refrigeration equipment

Abstract

This invention discloses an electric motor, a compressor, and a refrigeration device, relating to the field of refrigeration equipment technology. The electric motor includes a rotor and a stator. The rotor includes a rotor core and permanent magnets. The rotor core has multiple mounting slots spaced circumferentially, with adjacent mounting slots symmetrical about a second center line. Inter-pole harmonic slots are provided on the outer peripheral wall of the rotor core corresponding to the inter-pole region between adjacent mounting slots. The technical solution of this invention effectively suppresses back electromotive force harmonics and cogging torque pulsation by providing inter-pole harmonic slots on the outer peripheral wall of the rotor core corresponding to the inter-pole region between adjacent magnetic poles, and limiting them to 0.55-0.61, thereby reducing vibration noise during motor operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration equipment, in particular to a motor, a compressor and a refrigeration equipment. BACKGROUND

[0002] The conventional permanent magnet synchronous motor has obvious tooth slot torque due to the interaction between the stator and the rotor, and the motor back electromotive force waveform contains many harmonic components, which leads to significant torque ripple, thereby causing serious vibration and noise of the motor. SUMMARY

[0003] The main purpose of the present application is to provide a motor, a compressor and a refrigeration equipment, which aims to effectively suppress the back electromotive force harmonic and torque ripple to reduce the vibration and noise of the motor during operation.

[0004] To achieve the above purpose, the motor provided by the present application comprises:

[0005] The rotor comprises a rotor core and a permanent magnet, the rotor core has a first center line and a second center line extending in its radial direction, a plurality of mounting grooves are arranged at intervals in the circumferential direction of the rotor core, the permanent magnet is embedded in the mounting grooves, and 2P magnetic poles are formed in the circumferential direction of the rotor core; the two adjacent mounting grooves are symmetrical about the second center line, the outer peripheral wall of the rotor core is provided with an inter-pole harmonic groove corresponding to the inter-pole region between the two adjacent mounting grooves, and the included angle formed by the inter-pole harmonic groove in the circumferential direction of the rotor core and the center of the rotor core is A1;

[0006] The mounting groove comprises a first clamping groove, a second clamping groove and a third clamping groove connected in series, the first clamping groove and the third clamping groove are symmetrically arranged about the first center line and extend away from the first center line in the direction of the edge of the rotor core along the rotor core axis, and the two ends of the second clamping groove are connected to the end of the first clamping groove and the end of the third clamping groove close to the rotor core axis respectively; the first end point close to the first center line is arranged at the end of the first clamping groove and the third clamping groove away from the second clamping groove, and the included angle formed by the two first end points and the center of the rotor core is A2; the side edge of the second clamping groove close to the edge of the rotor core has intersection points with the first clamping groove and the third clamping groove respectively, and the included angle formed by the two intersection points and the center of the rotor core is A3; and

[0007] The stator is sleeved on the outer periphery of the rotor, the stator comprises a stator core and a stator winding, the stator core comprises a stator yoke and a stator tooth, a plurality of stator teeth are arranged at intervals along the inner periphery of the stator yoke, a stator slot is formed between the two adjacent stator teeth, the number of the stator slots is Q, the width of the stator slot opening is L, and the inner circle radius of the stator core is R1;

[0008] Among them, 0.55 0.61.

[0009] In one embodiment, the outer peripheral wall of the rotor core is provided with two first harmonic slots and two second harmonic slots in the area jointly defined by the mounting slot and the edge of the rotor core. The two first harmonic slots are distributed on the outside of the two second harmonic slots along the circumference of the rotor core, and the two first harmonic slots and the two second harmonic slots are symmetrical about the first center line.

[0010] The angle between the line connecting the edge of the first harmonic slot away from the first center line and the center of the rotor core, and the first center line, is α1; the angle between the line connecting the edge of the first harmonic slot close to the first center line and the center of the rotor core, and the first center line, is α2; the angle between the line connecting the edge of the second harmonic slot away from the first center line and the center of the rotor core, and the first center line, is α3; the angle between the line connecting the edge of the second harmonic slot close to the first center line and the center of the rotor core, and the first center line, is α4.

[0011] The minimum distance from the first harmonic slot to the center of the rotor core is W1, the minimum distance from the second harmonic slot to the center of the rotor core is W2, and the outer radius of the rotor core is R2.

[0012] in, .

[0013] In one embodiment, 0.80 ≤ ≤0.86.

[0014] In one embodiment, 0.84 ≤ ≤0.89.

[0015] In one implementation, 10 ≤ 2P ≤ 12.

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

[0017] 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.

[0018] 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.

[0019] The present invention also proposes a compressor, including the aforementioned motor.

[0020] The present invention also proposes a refrigeration device, including the aforementioned compressor.

[0021] The technical solution of this invention involves setting inter-pole harmonic slots on the outer peripheral wall of the rotor core, corresponding to the inter-pole region between two adjacent magnetic poles. This alters the air gap permeability between the stator and rotor, introducing a reverse harmonic magnetic field to counteract specific-order cogging torque harmonics caused by the stator-side cogging effect, thereby effectively suppressing cogging torque fluctuations. Simultaneously, by limiting the range to 0.55... The value is 0.61, which controls the total magnetic field modulation formed by the inter-pole harmonic slot and the mounting slot, so that it matches the phase of the magnetic permeability harmonic caused by the stator teeth, effectively suppressing the inter-pole harmonics and cogging torque fluctuations, thereby reducing the vibration and noise of the motor during operation. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the structure of an embodiment of the motor provided by the present invention;

[0024] Figure 2 A partial schematic diagram of the rotor provided by the present invention;

[0025] Figure 3 A partial schematic diagram of the rotor provided by the present invention;

[0026] Figure 4 This is another partial schematic diagram of the rotor provided by the present invention;

[0027] Figure 5 The rate of change of cogging torque with Trend chart of changes;

[0028] Figure 6 Torque pulsation Trend chart of changes;

[0029] Figure 7 The proportions of the 5th and 7th harmonics vary with Trend chart of changes;

[0030] Figure 8 The proportions of the 5th and 7th harmonics vary with A trend chart showing the changes.

[0031] Explanation of icon numbers:

[0032] 100, Rotor core; 200, Stator core; 110, Mounting slot; 111, First slot; 112, Second slot; 113, Third slot; 114, Intersection point; 115, First end point; 120, Interpole harmonic slot; 130, First harmonic slot; 140, Second harmonic slot; 210, Stator yoke; 220, Stator tooth; 230, Stator slot; q1, First center line; q2, Second center line; O, Center.

[0033] 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

[0034] 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.

[0035] 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.

[0036] 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.

[0037] This invention proposes an electric motor.

[0038] Please see Figure 1 and Figure 2In 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. The outer peripheral wall of the rotor core 100 is provided with an inter-pole harmonic slot 120 corresponding to the inter-pole region between two adjacent mounting slots 110. The angle between the inter-pole harmonic slot 120 and the center O of the rotor core 100 in the circumference of the rotor core 100 is A1.

[0039] 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 a first center line q1 and extend away from the first center line q1 in the direction of the rotor core 100 axis toward the edge of the rotor core 100. The two ends of the second slot 112 are respectively connected to the ends of the first slot 111 and the third slot 113 near the axis of the rotor core 100. The ends of the first slot 111 and the third slot 113 away from the second slot 112 have first endpoints 115 near the first center line q1. The angle formed by the two first endpoints 115 and the center O of the rotor core 100 is A2. The side of the second slot 112 near the edge of the rotor core 100 has intersection points 114 with the first slot 111 and the third slot 113. The angle formed by the two intersection points 114 and the center O of the rotor core 100 is A3.

[0040] 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 L, and the inner radius of the stator core 200 is R1.

[0041] Among them, 0.55 0.61.

[0042] Specifically, the rotor includes a rotor core 100 and permanent magnets embedded therein. The rotor core 100 has 2P magnetic poles (P being the number of pole pairs) along its circumference, and 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, the inter-pole harmonic slot 120, the first harmonic slot 130, and the second harmonic slot 140.

[0043] 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 the first center line q1 and extend from near the rotor axis towards the outer edge of the rotor, 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 magnetic flux concentration, thereby reducing local magnetic saturation and improving magnetic energy utilization.

[0044] Cogging torque is a periodic pulsating torque generated by the interaction between the magnetic field of the permanent magnet and the cogging teeth on the stator side. The inter-pole harmonic slot 120, corresponding to the inter-pole region between two adjacent magnetic poles, is disposed on the outer peripheral wall of the rotor core 100. The function of the inter-pole harmonic slot 120 is to locally change the air gap permeability and introduce a reverse harmonic magnetic field to counteract specific-order cogging torque harmonics caused by the cogging effect on the stator side, thereby effectively suppressing cogging torque fluctuations. The inter-pole harmonic slot 120 forms an angle A1 with respect to the center O of the rotor core 100 in the circumferential direction.

[0045] Understandably, the size of the inter-pole harmonic slot 120 directly affects the air gap width between the rotor and stator, thereby suppressing harmonics. Specifically, increasing the width or depth of the inter-pole harmonic slot 120 increases the air gap and thus suppresses harmonics; however, increasing the size of the inter-pole harmonic slot 120 leads to a decrease in motor output power. To maintain the same motor output power, the current needs to be increased, resulting in an increased magnetic field, which in turn increases harmonics. Therefore, it is necessary to optimize and balance the size and position of the inter-pole harmonic slot 120.

[0046] A1 reflects the circumferential angular range occupied by the inter-pole harmonic slot 120 on the outer edge of the rotor. Its size directly affects the effect of air gap magnetic permeability (the greater the distance between the two opposite edges of the slot opening of the inter-pole harmonic slot 120, the larger A1 is). By controlling A1, spatial harmonics of a specific order can be effectively weakened, thereby reducing the cogging torque caused by changes in magnetic permeability. A1 is measured as follows: taking the center O of the rotor core 100 as the vertex, two rays are formed by connecting the center O to the two edges of the inter-pole harmonic slot 120. The included angle between the two rays on the same cross-section cut by a plane perpendicular to the axial direction of the rotor core 100 is A1.

[0047] A2 is the circumferential angular range occupied by the entire mounting slot 110 on the outer edge of the rotor, reflecting the coverage angle of the permanent magnet in the magnetic pole region, and can affect the distribution of the main magnetic flux density. The larger A2 is (the position of the intersection point 114 of the first slot 111, the third slot 113 and the second slot 112 remains unchanged, and the greater the distance of the end of the first slot 111 and the third slot 113 away from the second slot 112 from the first center line q1, then A2 is larger), the wider the magnetic pole, and the stronger the main magnetic flux. Therefore, A2 directly affects the width of the magnetomotive force distribution of the permanent magnet and the fundamental amplitude and harmonic ratio of the air gap magnetic flux density waveform. The measurement method of A2 is as follows: find two first endpoints 115 close to the first center line q1 at the ends of the first slot 111 and the third slot 113 away from the second slot 112, and measure the angle between the two first endpoints 115 and the line connecting them to the center O of the rotor core 100 using a protractor or optical measuring instrument to obtain A2.

[0048] A3 represents the circumferential angular range occupied by the second slot 112 on the outer edge of the rotor, reflecting the width of the outward expansion of the second slot 112. It is used to control the thickness of the magnetic bridge and the leakage magnetic path. A smaller A3 results in a thicker magnetic bridge, higher mechanical strength, but more leakage magnetic field; a larger A3 results in a thinner magnetic bridge, which is prone to saturation but is beneficial for modulating the magnetic field waveform (with the positions of the first endpoints 115 of the first slot 111 and the third slot 113 remaining 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 the larger A3 is, and the thinner the magnetic bridge). Controlling A3 helps to adjust the concentration of the magnetic flux path, optimize the main magnetic flux distribution, and suppress leakage magnetic field. The measurement method for A3 is 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 them to the center O of the rotor core 100 using a protractor or optical measuring instrument. A3 is obtained by this angle. Since A2 > A3, A2 - A3 represents the circumferential span corresponding to the first slot 111 and the third slot 113. By rationally designing the relative relationships of the three angles A1, A2, and A3, 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.

[0049] Q represents the number of stator slots 230, which can be obtained by counting directly.

[0050] L 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, and the average of the stable readings is the width L of the stator slot 230 opening.

[0051] R1 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 R1 of the stator core 200. π is the mathematical constant pi.

[0052] make , This is a dimensionless ratio, representing the sum of the pole arcs of the rotor-side inter-pole harmonic slots 120 and the permanent magnet pole arcs, to the sum of the pole arcs of the stator-side armature magnetic field stator teeth 220. By limiting this ratio within a certain range, harmonic suppression effectiveness is ensured. Specifically, It 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, i.e., the slotting ratio; 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 magnetic flux, that is, this parameter reflects the magnetic flux density 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.

[0053] This characterizes the equivalent magnetic pole curvature under the combined action of the inter-pole harmonic slot 120, the first slot 111, and the third slot 113. It is worth noting that the rotor's magnetic flux mainly passes through the regions near the inter-pole harmonic slot 120, the first slot 111, and the third slot 113. Therefore, by optimizing and controlling the pole curvature ratio of the inter-pole harmonic slot 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 inter-pole harmonic slot 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 air gap magnetic field waveform. Specifically, in this invention, "modulation" refers to actively intervening in the magnetic field distribution through structural design (mounting slot 110, inter-pole harmonic slot 120, first harmonic slot 130, and second harmonic slot 140) to cancel out the magnetic field harmonics introduced on the rotor side with the introduced magnetic field, thereby suppressing cogging torque pulsation.

[0054] Essentially, it is the normalized ratio of the rotor-side harmonic modulation effect intensity to the stator-side cogging modulation effect intensity. This is achieved by controlling... In the range of 0.55 to 0.61, it indicates that the magnetic field harmonics introduced by the rotor through the inter-pole harmonic slot 120 and mounting slot 110 structure can achieve optimal phase matching and amplitude cancellation with the harmonics caused by the stator side tooth slots, thereby maximally weakening the main harmonic components of the tooth cogging torque, and thus suppressing tooth cogging torque pulsation and reducing vibration noise during motor operation.

[0055] Please refer to Table 1 and Figure 5 Table 1 shows the rate of change of cogging torque as a function of... The table of changing relationships Figure 5 The rate of change of cogging torque with A trend chart showing the changes.

[0056] Table 1: Rate of change of cogging torque with Relationship table of changes

[0057]

[0058] Cogging torque is the non-driving torque fluctuation of a permanent magnet motor when it is not energized (i.e., there is no current in the windings), caused by the periodic change in the magnetic attraction between the permanent magnet and the stator core as the rotor position changes.

[0059] Figure 5 The vertical axis in the figure represents the rate of change of cogging torque, where is the ratio of the change of cogging torque to the change of cogging torque. The cogging torque of the motor at a value of 0.53 is used as the optimization benchmark. Figure 5 Showing different The graph shows the change in the cogging torque of the lower motor relative to a reference value. As can be seen from the graph, the rate of change of the motor's cogging torque (expressed as a percentage) increases with... The trend of change. The curve in the figure changes with... The increase shows a trend of first decreasing and then increasing.

[0060] along with As the value increased from 0.53 to 0.59, the rate of change of cogging torque continued to decrease. When the value is 0.59, the cogging torque fluctuation reaches 82%, indicating that it is only 82% of the baseline value, a reduction of 18%. Subsequently, when... As it continues to increase to 0.63, torque fluctuations rapidly rebound, eventually returning to levels close to or even slightly above the baseline (100.57%). When the value is too small (e.g., less than 0.53), the rotor's harmonic modulation of the magnetic field is insufficient, failing to effectively compensate for the periodic magnetic reluctance changes caused by the stator-side cogging, resulting in high cogging torque; when When the value is too large (e.g., greater than 0.63), the rotor's harmonic modulation of the magnetic field is too strong, which may lead to harmonic superposition rather than cancellation, or excite other orders of resonant components, thus exacerbating torque ripple. When 0.55 ≤ When the value is ≤0.61, the cogging torque variation rate is consistently below 88.34%, significantly better than the baseline design. This indicates that the reverse harmonics generated by the rotor through the inter-pole harmonic slot 120 and mounting slot 110 are phase-aligned and amplitude-matched with the stator-side cogging harmonics, achieving mutual cancellation. Specifically, when... When the value is 0.59, the electromagnetic matching between the rotor structure (inter-pole harmonic slot 120, mounting slot 110) and the stator side cogging effect reaches a better state, so that the cogging torque harmonics caused by air gap magnetic permeability modulation are canceled to the greatest extent.

[0061] The technical solution of this invention involves setting inter-pole harmonic slots 120 on the outer peripheral wall of the rotor core 100 corresponding to the inter-pole region between two adjacent magnetic poles. This alters the air gap permeability between the stator and rotor, introducing a reverse harmonic magnetic field to counteract specific-order cogging torque harmonics caused by the stator-side cogging effect, thereby effectively suppressing cogging torque fluctuations. Simultaneously, by limiting the range to 0.55... The value is 0.61, which controls the total magnetic field modulation formed by the inter-pole harmonic slot 120 and the mounting slot 110, so that it matches the phase of the magnetic permeation harmonic caused by the stator teeth 220, effectively suppressing the inter-pole harmonics and cogging torque fluctuations, thereby reducing the vibration noise during motor operation.

[0062] In one implementation, please refer to Figures 1 to 4 The outer peripheral wall of the rotor core 100 is provided with two first harmonic slots 130 and two second harmonic slots 140 in the area jointly defined by the mounting slot 110 and the edge of the rotor core 100. The two first harmonic slots 130 are distributed on the outside of the two second harmonic slots 140 along the circumference of the rotor core 100, and the two first harmonic slots 130 and the two second harmonic slots 140 are symmetrical about the first center line q1.

[0063] The angle between the line connecting the edge of the first harmonic slot 130 away from the first center line q1 and the center O of the rotor core 100, and the first center line q1, is α1; the angle between the line connecting the edge of the first harmonic slot 130 close to the first center line q1 and the center O of the rotor core 100, and the first center line q1, is α2; the angle between the line connecting the edge of the second harmonic slot 140 away from the first center line q1 and the center O of the rotor core 100, and the first center line q1, is α3; the angle between the line connecting the edge of the second harmonic slot 140 close to the first center line q1 and the center O of the rotor core 100, and the first center line q1, is α4.

[0064] The minimum distance from the first harmonic slot 130 to the center O of the rotor core 100 is W1, the minimum distance from the second harmonic slot 140 to the center O of the rotor core 100 is W2, and the outer radius of the rotor core 100 is R2.

[0065] in, .

[0066] Two first harmonic slots 130 and two second harmonic slots 140 are provided within the same magnetic pole region. The two second harmonic slots 140 are arranged close to the first center line q1 and symmetrically about the first center line q1. The second harmonic slots 140 mainly affect the main magnetic flux path, used to smooth the main magnetic field gradient and improve the sinusoidal nature of the back electromotive force waveform. The two first harmonic slots 130 are located outside the second harmonic slots 140 (i.e., farther from the first center line q1 than the second harmonic slots 140 within the same magnetic pole region) and symmetrically about the first center line q1. The first harmonic slots 130 are mainly used to adjust the magnetic permeability at the air gap edge and weaken the high-frequency harmonics caused by the stator tooth slot 220. The two first harmonic slots 130 and the two second harmonic slots 140 are designed symmetrically to ensure that the magnetic field distribution on both sides of the magnetic pole is consistent, avoiding biased magnetization or unilateral magnetic pull.

[0067] Defined using polar coordinates with the first center line q1 as the reference.

[0068] α1 is the angle between the line connecting the edge of the first harmonic slot 130 opening away from the first center line q1 and the rotor center O, and the first center line q1. This angle determines the position of the outer boundary of the first harmonic slot 130. α1 is measured as follows: taking the center O of the rotor core 100 as the vertex, connect the center O to the edge of the first harmonic slot 130 opening away from the first center line q1. This line and the first center line q1 lie on the same cross-section cut by a plane perpendicular to the axial direction of the rotor core 100. The angle between this line and the first center line q1 is α1.

[0069] α2 is the angle between the line connecting the edge of the first harmonic slot 130 opening near the first center line q1 and the rotor center O, and the first center line q1. α2 is measured as follows: taking the center O of the rotor core 100 as the vertex, connect the center O to the edge of the first harmonic slot 130 opening near the first center line q1. This line and the first center line q1 lie on the same cross-section cut by a plane perpendicular to the axial direction of the rotor core 100. The angle between this line and the first center line q1 is α2. The central angle represents the circumferential opening width of the first harmonic slot 130, reflecting its modulation width.

[0070] α3 is the angle between the line connecting the edge of the second harmonic slot 140 opening away from the first center line q1 and the center O, relative to the first center line q1. α3 is measured as follows: taking the center O of the rotor core 100 as the vertex, connect the center O to the edge of the second harmonic slot 140 opening away from the first center line q1. This line and the first center line q1 lie on the same cross-section cut by a plane perpendicular to the axial direction of the rotor core 100. The angle between this line and the first center line q1 is α3.

[0071] α4 is the angle between the line connecting the edge of the second harmonic slot 140 opening near the first center line q1 and the center O, relative to the first center line q1. This angle determines the position of the inner boundary of the second harmonic slot 140. α4 is measured as follows: taking the center O of the rotor core 100 as the vertex, connect the center O to the edge of the second harmonic slot 140 opening near the first center line q1. This line and the first center line q1 lie on the same cross-section cut by a plane perpendicular to the axial direction of the rotor core 100. The angle between this line and the first center line q1 is α4. The central angle represents the circumferential opening width of the second harmonic slot 140, reflecting its modulation width.

[0072] R2 is the outer radius of the rotor core 100, which is also the radius of the unslotted area of ​​the rotor core 100. It can be obtained by measuring the outer diameter of the rotor core 100 and taking half of that value. For example, when using vernier calipers to measure the outer radius of the rotor core 100, place the measuring jaws against the unslotted area of ​​the outer circle of the rotor core 100 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 measured diameter values ​​and then divide by 2 to obtain the accurate outer radius value R2 of the rotor core 100. π is the mathematical constant pi.

[0073] W1 is the minimum distance from the first harmonic slot 130 to the center O of the rotor core 100. W1 can be measured using a height gauge: place the rotor core 100 flat on a reference platform, with the platform as the reference zero point; use the height gauge probe to contact the lowest point of the bottom of the first harmonic slot 130 closest to the center O of the rotor core 100, and record the reading W1.

[0074] W2 is the minimum distance from the second harmonic slot 140 to the center O of the rotor core 100. W2 can be measured using a height gauge: place the rotor core 100 flat on a reference platform, with the platform as the reference zero point; use the height gauge probe to contact the lowest point of the bottom of the second harmonic slot 140 closest to the center O of the rotor core 100, and record the reading W2.

[0075] The radial depth of the first harmonic slot 130 represents its modulation intensity. It is the "width-to-depth ratio" of the first harmonic slot 130, which represents the circumferential modulation density of the first harmonic slot 130, that is, the circumferential angular span corresponding to a unit radial depth. The larger the value, the more efficient the first harmonic slot 130 is, as it can achieve a wider range of magnetic permeability modulation at a shallower depth. The radial depth of the second harmonic slot 140 represents its modulation intensity. It is the "width-to-depth ratio" of the second harmonic slot 140, which represents the circumferential modulation density of the second harmonic slot 140, that is, the circumferential angular span corresponding to a unit radial depth. The larger the value, the more efficient the second harmonic slot 140 is, as it can achieve a wider range of magnetic permeability modulation at a shallower depth. This indicates that the modulation effects of the first harmonic slot 130 and the second harmonic slot 140 are synergistic and interconnected, reflecting the overall modulation capability under the synergistic effect of the inner and outer harmonic slots. The larger this product value, the stronger the modulation effect of the first harmonic slot 130 and the second harmonic slot 140 on the air gap magnetic field.

[0076] The effective air gap length of the motor (excluding the influence of the inter-pole harmonic slot 120, the first harmonic slot 130, and the second harmonic slot 140) is a key parameter determining the reluctance and flux density. A smaller air gap results in lower reluctance, but also greater sensitivity to harmonic modulation effects. A2 is the coverage angle of the permanent magnet in the center region of the magnetic poles, reflecting the degree of flux concentration at the main poles. It is the spatial characteristic scale of the main magnetic circuit, representing the level of the basic magnetic field strength when it is not modulated.

[0077] make , It is a dimensionless ratio. This represents the combined intensity of magnetic field disturbances (harmonics) introduced by the double-layer harmonic slots (first harmonic slot 130 and second harmonic slot 140) under a unit main magnetic flux intensity. When When the value is controlled within the range of 3.8 to 4.3, it indicates that the harmonic modulation can effectively cancel the specific order harmonics caused by the cogging effect, and can also avoid triggering new harmonic resonances or weakening the main magnetic flux output capability, thereby achieving effective suppression of cogging torque fluctuations.

[0078] In addition, through the The limitations are used to achieve optimal matching between the rotor and stator, ensuring that the rotor magnetic poles as a whole and the stator teeth and slots achieve the best match; through the constraints of The limitations enable the optimization of the rotor's own magnetic pole structure. and Together, they ensure that the motor is in the optimal electromagnetic design state from the whole to the parts, which enables the motor to suppress cogging torque and back EMF harmonics extremely effectively, thereby effectively reducing the vibration and noise of the motor during operation.

[0079] Please refer to Table 2 and Figure 6 Table 2 shows the torque pulsation as a function of... The table of changing relationships Figure 6 Torque pulsation A trend chart showing the changes.

[0080] Table 2: Torque ripple as Relationship table of changes

[0081]

[0082] Torque ripple refers to the periodic fluctuations or undulations in the output torque of an electric motor or other rotating machinery during operation, around its average value. 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. It is the average torque within that cycle.

[0083] Torque pulsation The increase shows a trend of first decreasing and then increasing. With... As the value increased from 3.6 to 4.2, the torque ripple continued to decrease, indicating that the harmonic suppression effect improved with increasing torque. It increases with the increase of [something]. When [something] increases, it strengthens. As the value continues to increase, the torque pulsation rises sharply, even exceeding the initial value at 4.4, indicating that the depth of the first harmonic slot 130 and the second harmonic slot 140 are too large or the angle is too wide, which may lead to an increase in magnetic flux leakage; or trigger electromagnetic wave resonance of a specific order, thereby generating additional torque fluctuations.

[0084] It can be seen that when When the value is less than 3.8, the modulation is insufficient, and the harmonic suppression effect is limited; when... When the value is greater than 4.3, excessive modulation may introduce new harmonic resonances or disrupt the original magnetic field balance, thereby exacerbating torque fluctuations; when Between 3.8 and 4.3, the torque ripple remained below 4.31%, indicating that the modulation effect of the first harmonic slot 130 and the second harmonic slot 140 reached a better matching state, effectively offsetting the torque fluctuations caused by stator side slots and back EMF harmonics.

[0085] In one implementation, please refer to Figure 2 and Figure 3 , 0.80≤ ≤0.86.

[0086] α1 is the angle between the edge of the first harmonic slot 130 away from the first center line q1 and the line connecting the center O of the rotor core 100 with respect to the first center line q1, representing the position of its outer boundary; while A2 is the coverage angle of the permanent magnet in the center region of the magnetic pole, reflecting the effective magnetic field distribution width of the main magnetic pole. This indicates the proportion of the modulation region formed by the two first harmonic slots 130 to the entire magnetic pole angle.

[0087] From an electromagnetic perspective, the 5th and 7th harmonics are common and predominant spatial harmonic orders in permanent magnet synchronous motors. They are typically excited by the cogging effect of the stator and the non-uniformity of the rotor's permanent magnets, leading to back electromotive force distortion, increased torque pulsation, and elevated electromagnetic noise. By setting a first harmonic slot 130 on the outer periphery of the rotor core 100 and appropriately controlling its distance from the first centerline q1 (i.e., adjusting...),... This allows the introduction of a reverse magnetic field harmonic of a specific phase into the air gap, thereby achieving the cancellation of the 5th and 7th harmonics.

[0088] Please refer to Table 3 and Figure 7 Table 3 shows the proportions of the 5th and 7th harmonics as a function of... The table of changing relationships Figure 7 The proportions of the 5th and 7th harmonics vary with A trend chart showing the changes.

[0089] Table 3: Proportion of 5th and 7th harmonics Relationship table of changes

[0090]

[0091] Figure 7 The vertical axis represents the proportion of the 5th and 7th harmonics, that is, the combined content of the 5th and 7th harmonics relative to the fundamental frequency. This chart shows the proportion 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 trend of first decreasing and then increasing, indicating that as... As the number of harmonics increases, the proportions of the 5th and 7th harmonics decrease significantly first and then increase.

[0092] when When the value increased from 0.74 to 0.84, the proportion of harmonics decreased significantly from approximately 6.3% to approximately 4.6%; when As the value continues to increase from 0.84, the proportion of harmonics actually rises. Specifically, when... When the value is less than 0.80, the first harmonic slot 130 is too close to the first center line q1, and the modulation capability of the first harmonic slot 130 is insufficient, failing to effectively cancel the target harmonic; when When the value is greater than 0.86, the first harmonic slot 130 is too far from the first center line q1, too close to the edge of the magnetic pole, which may interfere with the main magnetic flux path and even introduce new harmonic components, causing the harmonic proportion to rise again; when Within the range of 0.80 to 0.86, the combined content of the 5th and 7th harmonics is reduced to below 5%, which is better than other value ranges. Within this range, the first harmonic slot 130 can accurately match the spatial periodic characteristics of the 5th and 7th harmonics, achieving optimal phase alignment and amplitude cancellation, thereby improving the back EMF waveform quality, reducing the total harmonic distortion rate, reducing the torque ripple of the motor, and thus reducing the vibration noise during motor operation.

[0093] In one implementation, please refer to Figure 2 and Figure 3 0.84≤ ≤0.89.

[0094] α4 is the angle between the edge of the second harmonic slot 140 near the first center line q1 and the line connecting the center O of the rotor core 100 with respect to the first center line q1, reflecting the position of the inner boundary of the second harmonic slot 140; A3 is the angle formed by the intersection point 114 of the outer side of the second slot 112 and the first and third slots 113 and the center O of the rotor core 100, representing the width of the mounting slot 110 near the rotor shaft end; This indicates the proportional relationship between the position of the second harmonic slot 140 near the first center line q1 and the width of the magnetic circuit inside the second slot 112. Its physical significance lies in coordinating the spatial matching relationship between the second harmonic slot 140 and the second slot 112 to adjust the magnetic permeability distribution of the main magnetic flux path, smooth the magnetic field gradient, and suppress the low-order harmonics and local magnetic saturation effects caused by the concentrated magnetic flux at the edge of the permanent magnet.

[0095] Please refer to Table 4 and Figure 8 Table 4 shows the proportions of the 5th and 7th harmonics as a function of... The table of changing relationships Figure 8 The proportions of the 5th and 7th harmonics vary with A trend chart showing the changes.

[0096] Table 4: Proportion of 5th and 7th harmonics Relationship table of changes

[0097]

[0098] Figure 8 The vertical axis represents the proportion of the 5th and 7th harmonics, that is, the combined content of the 5th and 7th harmonics relative to the fundamental frequency. This chart shows the proportion 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 trend of first decreasing and then increasing, indicating that as... As the number of harmonics increases, the proportions of the 5th and 7th harmonics decrease significantly first and then increase.

[0099] when When the harmonic content increases from 0.82 to 0.87, the proportion of harmonics decreases from approximately 5.35% to approximately 4.64%; when As the value continues to increase from 0.87, the proportion of harmonics actually rises. Specifically, when... When <0.84, the second harmonic slot 140 is closer to the first center line q1, and its modulation effect on the main magnetic field is weaker, failing to sufficiently weaken the flux concentration effect at the edge of the permanent magnet, resulting in a higher proportion of the 5th and 7th harmonics; when When the value is greater than 0.89, the second harmonic slot 140 is further away from the first center line q1, which may cause an increase in main magnetic flux leakage or a sudden change in local magnetic reluctance, thereby exciting new harmonic components and leading to an increase in the proportion of harmonics. When the value is between 0.84 and 0.88, the second harmonic slot 140 is in a better position, which can effectively adjust the air gap magnetic permeability distribution, improve the sinusoidal nature of the back EMF waveform, reduce the total harmonic distortion rate, and reduce torque pulsation, thereby making the motor run more smoothly and with lower vibration and noise.

[0100] In one implementation, please refer to Figure 1 , 10≤2P≤12.

[0101] The total number of magnetic poles in a permanent magnet synchronous motor is limited to 10 ≤ 2P ≤ 12, meaning the motor can have a 10-pole, 11-pole, or 12-pole structure (P being the number of pole pairs). 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 can improve torque smoothness, it increases rotor core losses, manufacturing difficulty, and the proportion of high-frequency harmonics, while also requiring a faster response speed from the controller.

[0102] 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.

[0103] In one implementation, please refer to Figure 1 , 15≤Q≤18.

[0104] The number of stator slots 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 Q and the number of rotor poles 2P jointly determine the number of slots per pole per phase, thus affecting the magnetic field modulation effect and winding distribution characteristics. Combining the preferred pole 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 pitch 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. At the same time, 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 slots (including inter-pole harmonic slot 120, first harmonic slot 130, and second harmonic slot 140) and mounting slot 110 structure can be optimized while ensuring good electromagnetic performance.

[0105] 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.

[0106] The motor has m phases, Q stator slots, 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 electromagnetic design of the motor, directly affecting the harmonic proportion 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 is prone to generating strong low-order magnetomotive force harmonics, and the relationship between the cogging period and the pole pitch is fixed, which is not conducive to harmonic suppression. When 0 < q < 1, it is a typical fractional-slot winding.

[0107] The fractional slot structure allows for a non-common multiple of the stator slot number and rotor pole number to be matched, effectively dispersing the spatial harmonic energy of the air gap magnetic field and avoiding the concentrated superposition of harmonics, 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 structure of the inter-pole harmonic slot 120, the first harmonic slot 130, the second harmonic slot 140, and the multi-segment mounting slot 110, further optimizing the air gap magnetic flux density waveform to a more 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 operating under each magnetic pole, maintaining basic electromagnetic conversion capability.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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 machine characterized in that, Comprise: The rotor comprises a rotor core and a permanent magnet, the rotor core has a first center line and a second center line extending radially along it, a plurality of mounting grooves are spaced apart along the circumferential direction of the rotor core, the permanent magnet is embedded in the mounting groove, and 2P magnetic poles are formed in the circumferential direction of the rotor core; two adjacent mounting grooves are symmetrical about the second center line, the outer wall of the rotor core is provided with an inter-pole harmonic slot corresponding to the inter-pole region between the two adjacent mounting grooves, and the included angle between the inter-pole harmonic slot and the center of the rotor core in the circumferential direction of the rotor core is A1; The mounting groove comprises a first clamping groove, a second clamping groove and a third clamping groove connected in communication, the first clamping groove and the third clamping groove are symmetrically arranged about the first center line and extend away from the first center line in the direction of the rotor core axis towards the edge of the rotor core, and the two ends of the second clamping groove are respectively communicated with the end of the first clamping groove and the end of the third clamping groove close to the rotor core axis; the first clamping groove and the third clamping groove have a first end point close to the first center line at the end away from the second clamping groove, and the included angle between the two first end points and the center of the rotor core is A2; the side edge of the second clamping groove close to the edge of the rotor core has an intersection with the first clamping groove and the third clamping groove, respectively, and the included angle between the two intersections and the center of the rotor core is A3; and The stator is sleeved on the outer periphery of the rotor, and the stator comprises a stator core and a stator winding, the stator core comprises a stator yoke and a stator tooth, a plurality of stator teeth are spaced apart along the inner periphery of the stator yoke, and a stator slot is formed between two adjacent stator teeth, the number of the stator slot is Q, the width of the stator slot opening is L, and the inner circle radius of the stator core is R1; wherein 0.55 0.

61.

2. The electric machine of claim 1, wherein, The outer wall of the rotor core is provided with two first harmonic slots and two second harmonic slots corresponding to the region defined by the mounting groove and the edge of the rotor core, the two first harmonic slots are respectively distributed on the outer side of the two second harmonic slots along the circumferential direction of the rotor core, and the two first harmonic slots and the two second harmonic slots are symmetrical about the first center line; The included angle between the line connecting the side edge of the opening of the first harmonic slot away from the first center line and the center of the rotor core and the first center line is α1, the included angle between the line connecting the side edge of the opening of the first harmonic slot close to the first center line and the center of the rotor core and the first center line is α2, the included angle between the line connecting the side edge of the opening of the second harmonic slot away from the first center line and the center of the rotor core and the first center line is α3, and the included angle between the line connecting the side edge of the opening of the second harmonic slot close to the first center line and the center of the rotor core and the first center line is α4; The minimum distance from the first harmonic slot to the center of the rotor core is W1, the minimum distance from the second harmonic slot to the center of the rotor core is W2, and the outer circle radius of the rotor core is R2; wherein .

3. The electric machine of claim 2, wherein, 0.80≤ ≤0.86。 4. The electric machine of claim 2, wherein, 0.84≤ ≤0.89。 5. The electric machine of claim 1, wherein, 10≤2P≤12。 6. The electric machine of claim 5, wherein, 15≤Q≤18。 7. The electric machine of claim 6, wherein, The number of phases of the motor is m, and the number of slots per pole per phase of the motor is q, q = Q / 2mP, q satisfies: 0 < q < 1.

8. The electric machine of claim 6, wherein, The greatest common divisor of the number Q of the stator slots and the number P of the rotor poles satisfies: 5 ≤ GCD(Q, P) ≤ 6.

9. A compressor characterized by, The motor comprises the motor as claimed in any one of claims 1 to 8.

10. A refrigeration appliance characterized in that, The compressor comprises the motor as claimed in claim 9.

Images