Motor, compressor and refrigeration equipment

Abstract

The invention discloses a motor, a compressor and refrigeration equipment, and relates to the technical field of refrigeration equipment, the motor comprises a rotor and a stator, the rotor comprises a rotor iron core and a permanent magnet, the rotor iron core is provided with a plurality of mounting grooves at intervals along the circumferential direction, and every two adjacent mounting grooves are symmetrical about a second center line; the outer peripheral wall of the rotor core is provided with inter-polar harmonic grooves corresponding to an inter-polar area between two adjacent mounting grooves. According to the technical scheme of the invention, the inter-polar harmonic slots are arranged in the inter-polar region between the corresponding two adjacent magnetic poles on the outer peripheral wall of the rotor core, and the limit is 0.550.61, so that back electromotive force harmonic waves and cogging torque pulsation are effectively suppressed, and the vibration noise during the operation of the motor is reduced.

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: A rotor comprising a rotor core and permanent magnets, 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 magnets are 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; 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 rotor core axis towards the edge of the rotor core, and the two ends of the second clamping groove are respectively communicated with the first end of the first clamping groove and the third clamping groove close to the rotor core axis; the first end of the first clamping groove and the third clamping groove away from the second clamping groove has a first end point close to the first center line, 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, and the included angle formed by the two intersection points and the center of the rotor core is A3; and A 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 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.

[0005] In an embodiment, the outer circumferential wall of the rotor core is provided with two first harmonic grooves and two second harmonic grooves corresponding to the area jointly defined by the mounting groove and the edge of the rotor core, the two first harmonic grooves are respectively distributed outside the two second harmonic grooves along the circumferential direction of the rotor core, and the two first harmonic grooves and the two second harmonic grooves are symmetric about the first center line. The included angle between the side edge of the slot opening of the first harmonic groove away from the first center line and the connection line between the center of the rotor core and the first center line is α1, the included angle between the side edge of the slot opening of the first harmonic groove close to the first center line and the connection line between the center of the rotor core and the first center line is α2; the included angle between the side edge of the slot opening of the second harmonic groove away from the first center line and the connection line between the center of the rotor core and the first center line is α3, and the included angle between the side edge of the slot opening of the second harmonic groove close to the first center line and the connection line between the center of the rotor core and the first center line is α4. The minimum distance from the first harmonic groove to the center of the rotor core is W1, the minimum distance from the second harmonic groove to the center of the rotor core is W2, and the outer circle radius of the rotor core is R2. Wherein, .

[0006] In an embodiment, 0.80≤ ≤0.86.

[0007] In an embodiment, 0.84≤ ≤0.89.

[0008] In an embodiment, 10≤2P≤12.

[0009] In an embodiment, 15≤Q≤18.

[0010] In an embodiment, the number of phases of the motor is m, the number of slots per pole per phase of the motor is q, q=Q / 2mP, q satisfies: 0

[0011] In an embodiment, the greatest common divisor of the number of slots Q of the stator and the number of poles P of the rotor satisfies: 5≤GCD(Q, P)≤6.

[0012] The application also provides a compressor comprising the motor.

[0013] The application also provides a refrigeration device comprising the compressor.

[0014] The technical scheme of the present application changes the air gap permeance between the stator and the rotor by arranging the inter-pole harmonic slot corresponding to the inter-pole region between the adjacent two magnetic poles on the outer peripheral wall of the rotor core, introduces the reverse harmonic magnetic field to offset the specific order tooth slot torque harmonic caused by the stator side tooth slot effect, thereby effectively suppressing the tooth slot torque fluctuation. 0.61, controls the total amount of the magnetic field modulation formed by the inter-pole harmonic slot and the mounting slot, and matches the permeance harmonic phase caused by the stator tooth, effectively suppresses the inter-pole harmonic and the tooth slot torque fluctuation, and reduces the vibration noise during the operation of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 The structural schematic diagram of an embodiment of the motor provided by the present application is shown in the figure. Figure 2 The partial schematic diagram of the rotor provided by the present application is shown in the figure. Figure 3 The partial schematic diagram of the rotor provided by the present application is shown in the figure. Figure 4 Another partial schematic diagram of the rotor provided by the present application is shown in the figure. Figure 5 The trend graph of the tooth slot torque change rate changing with is shown in the figure. Figure 6 The trend graph of the torque ripple changing with is shown in the figure. Figure 7 The trend graph of the 5th and 7th harmonic proportion changing with is shown in the figure. Figure 8 The trend graph of the 5th and 7th harmonic proportion changing with is shown in the figure.

[0017] Explanation of reference numerals: 100, rotor core; 200, stator core; 110, mounting slot; 111, first clamping slot; 112, second clamping slot; 113, third clamping slot; 114, intersection; 115, first end point; 120, inter-pole 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.

[0018] The objectives, functional characteristics and advantages of the present application will be further described with reference to the embodiments in combination with the accompanying drawings. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0020] It should be noted that if the embodiments of the present application involve directionality indication (such as up, down, left, right, front, back, etc.), the directionality indication is only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directionality indication also changes accordingly.

[0021] In addition, if the embodiments of the present application involve the description of “first”, “second” and the like, the description of “first”, “second” and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first”, “second” can explicitly or implicitly include at least one of the features. In addition, “and / or” or “and / or” appearing throughout the text means that the three parallel solutions are included, for example, “A and / or B” includes A solution, or B solution, or A and B solutions are satisfied at the same time. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the protection scope required by the present application.

[0022] The present application provides an electric machine.

[0023] Please refer to Figure 1 and Figure 2 In an embodiment of the present application, the electric machine comprises a rotor and a stator, the rotor comprises 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 along the radial direction thereof, a plurality of mounting grooves 110 are arranged at intervals along the circumferential direction of the rotor core 100, the permanent magnet is embedded in the mounting grooves 110, and 2P magnetic poles are formed in the circumferential direction of the rotor core 100; the two adjacent mounting grooves 110 are symmetrical about the second center line q2, the inter-pole region between the two adjacent mounting grooves 110 is provided with an inter-pole harmonic groove 120 on the outer circumferential wall of the rotor core 100, and the included angle formed by the inter-pole harmonic groove 120 and the center O of the rotor core 100 in the circumferential direction of the rotor core 100 is A1; 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. 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. Among them, 0.55 0.61.

[0024] 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.

[0025] Each mounting groove 110 includes a first clamping groove 111, a second clamping groove 112 and a third clamping groove 113. The first clamping groove 111 and the third clamping groove 113 are symmetrical about the first center line q1, and extend from a position close to the rotor axis to the direction of the rotor outer edge and gradually away from the first center line q1, forming an outwardly opening structure, which is conducive to improving the symmetry of the magnetic field distribution and reducing local magnetic saturation. The second clamping groove 112 serves as a connecting channel of the first clamping groove 111 and the third clamping groove 113, and its position is closer to the axis of the rotor core 100 than that of the first clamping groove 111 and the third clamping groove 113. The magnetic path length of the area near the second clamping groove 112 is shorter, and the magnetic resistance is lower. The second clamping groove 112 effectively widens the initial path of the magnetic flux from the permanent magnet to the air gap, which helps to evenly distribute the magnetic flux to the first clamping groove 111 and the third clamping groove 113 on both sides, avoiding the concentration of magnetic flux, thereby reducing local magnetic saturation and improving magnetic energy utilization.

[0026] Cogging torque is a periodic pulsating torque generated by the interaction between the permanent magnet magnetic field and the stator side tooth slot. The inter-pole harmonic slot 120 is arranged on the outer wall of the rotor core 100 corresponding to the inter-pole region between the adjacent two magnetic poles. The inter-pole harmonic slot 120 locally changes the air gap permeance and introduces a reverse harmonic magnetic field to offset the specific order of the cogging torque harmonic caused by the stator side tooth slot effect, thereby effectively suppressing the cogging torque fluctuation. The inter-pole harmonic slot 120 forms an angle A1 with the center O of the rotor core 100 in the circumferential direction.

[0027] It can be understood that the size of the inter-pole harmonic slot 120 can directly affect the air gap width between the rotor and the stator, thereby achieving suppression of harmonics. Specifically, by increasing the width or depth of the inter-pole harmonic slot 120 to increase the inter-pole harmonic slot 120, thereby increasing the air gap to achieve suppression of harmonics; but the increase of the inter-pole harmonic slot 120 will lead to the decrease of the motor output power, in order to ensure the output of the same motor output power, the current needs to be increased, thereby the magnetic field is increased, and then the harmonic is increased. Therefore, it is necessary to optimize and balance the size and position of the inter-pole harmonic slot 120.

[0028] A1 reflects the circumferential angular range occupied by the inter-pole harmonic slot 120 at the rotor outer edge, which directly affects the effect of air gap permeance (the greater the distance between the two side edges of the slot opening of the inter-pole harmonic slot 120, the greater A1), by controlling A1, the spatial harmonics of specific orders can be effectively weakened, thereby reducing the cogging torque caused by the change of permeance. The measurement method of A1 is: taking the center O of the rotor core 100 as the vertex, connecting the center O to the two edges of the inter-pole harmonic slot 120 to form two rays, the two rays are on the same cross section intersected by the plane perpendicular to the axial direction of the rotor core 100, and the included angle between the two rays is A1.

[0029] A2 is the circumferential angular range occupied by the entire mounting slot 110 at the rotor outer edge, reflecting the coverage angle of the permanent magnet in the magnetic pole area, which can affect the main magnetic flux density distribution. The larger A2 (the positions of the two intersection points 114 of the first clamping slot 111 and the third clamping slot 113 with the second clamping slot 112 remain unchanged, the distance between the ends of the first clamping slot 111 and the third clamping slot 113 away from the second clamping slot 112 and the first center line q1 is greater, then A2 is greater), the larger the pole width, the stronger the main magnetic flux. Therefore, A2 directly affects the magnetic potential distribution width of the permanent magnet to the outside and the fundamental amplitude and harmonic proportion of the air gap magnetic flux waveform. The measurement method of A2 is: find two first endpoints 115 near the first center line q1 at the ends of the first clamping slot 111 and the third clamping slot 113 away from the second clamping slot 112, respectively, and measure the included angle of the connecting line of the two first endpoints 115 and the center O of the rotor core 100 with an angle gauge or an optical measuring instrument to obtain A2.

[0030] A3 is the circumferential angular range occupied by the second clamping slot 112 at the rotor outer edge, reflecting the width of the second clamping slot 112 extending outward, used to control the magnetic bridge thickness and leakage magnetic path. A3 is smaller, the magnetic bridge is thicker, the mechanical strength is high but the leakage is more; A3 is larger, the magnetic bridge is thinner, easy to saturate but beneficial to the modulation of the magnetic field waveform (the positions of the first endpoints 115 of the first clamping slot 111 and the third clamping slot 113 remain unchanged, the closer the second clamping slot 112 extends along the extension direction of the first center line q1 to the edge of the rotor core 100, the greater the distance between the two intersection points 114, the larger A3, the thinner the magnetic bridge). By controlling A3, it is helpful to adjust the concentration degree of the magnetic flux path, optimize the main magnetic flux distribution and suppress the leakage. The measurement method of A3 is: find the two intersection points 114 of the first clamping slot 111 and the third clamping slot 113 on the side of the second clamping slot 112 near the edge of the rotor core 100, and measure the included angle of the connecting line of the two intersection points 114 and the center O of the rotor core 100 with an angle gauge or an optical measuring instrument to obtain A3. Among them, A2>A3, therefore A2-A3 represents the circumferential span corresponding to the first clamping slot 111 and the third clamping slot 113. By reasonably designing the relative relationship of the three angles A1, A2 and A3, the air gap magnetic field waveform can be shaped to be closer to the sine distribution, thereby reducing the high harmonic component in the back electromotive force.

[0031] Q is the number of stator slots 230, which can be directly counted.

[0032] L is the width of the slot opening of the stator slot 230, which can be measured by using a vernier caliper or a microscope to measure the distance between the opposite two sides of the slot opening of the stator slot 230. For example, when measuring the slot opening width of the stator slot 230 using a vernier caliper, the slot opening is cleaned and a knife-edge shaped outer measuring jaw is selected; the tip of the measuring jaw is vertically inserted into the bottom of the slot opening, ensuring contact with the two sides of the stator core 200; at least three points are selected on the stator core 200 in the axial direction for measurement, and the average of the stable readings is the slot opening width L of the stator slot 230.

[0033] R1 is the inner circle radius of the stator core 200, which can be obtained by measuring the inner diameter of the stator core 200 and taking half of the value. For example, when measuring the inner circle radius of the stator core 200 using a vernier caliper, the inner measuring jaw is inserted into the inner circle of the stator core 200, and the diameter is measured multiple times at different positions in the axial direction and perpendicular to each other in the same cross section; the average of all measured diameter values is taken and divided by 2 to obtain the accurate inner circle radius R1 of the stator core 200. π is the circular constant.

[0034] Let , be a dimensionless ratio, which is the ratio of the sum of the pole arc of the rotor side inter-pole harmonic slot 120 and the pole arc of the permanent magnet to the sum of the pole arc of the stator side armature magnetic field stator tooth 220. By limiting this ratio within a certain range, the harmonic suppression effect can be ensured. Specifically, is the inner circumference of the stator core 200, is the total width of all stator slots 230 openings; 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 rate; is the ratio of the sum of the widths of all stator teeth 220 to the inner circumference of the stator core 200, i.e. the slotting rate; is the proportion of the pole arc of all stator teeth 220 in the circumferential direction of the stator core 200, which reflects the effective angle of the stator side that can actually pass through the magnetic flux.

[0035] characterizes the equivalent magnetic pole arc under the cooperative action of one magnetic pole, the inter-pole harmonic slot 120, the first clamping slot 111 and the third clamping slot 113. It is worth mentioning that the magnetic flux of the rotor mainly passes through the area near the inter-pole harmonic slot 120, the first clamping slot 111 and the third clamping slot 113, so by optimizing and controlling the pole arc proportion of the inter-pole harmonic slot 120, the first clamping slot 111 and the third clamping slot 113, the harmonic can be effectively suppressed. The total amount of effective harmonic modulation angle determined by the inter-pole harmonic slot 120, the first clamping slot 111 and the third clamping slot 113 under each magnetic pole reflects the ability of the rotor structure to spatially modulate the air gap magnetic field. In the field of motor engineering, "modulation" specifically refers to the process of changing the spatial distribution of air gap permeance or magnetic potential through structural design, thereby affecting the air gap magnetic field waveform. In the context of the present invention, "modulation" refers to the active intervention in the magnetic field distribution through structural design (installation of slots 110, inter-pole harmonic slots 120, first harmonic slots 130 and second harmonic slots 140) to counteract the magnetic field harmonics introduced by the rotor side and the introduced magnetic field, thereby suppressing the cogging torque ripple.

[0036] Essentially, it is the normalized ratio of the strength of the rotor-side harmonic modulation effect to the strength of the stator-side slot modulation effect. By controlling In the interval 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 the installation slot 110 structure can achieve optimal phase matching and amplitude cancellation with the harmonics caused by the stator-side slot, thereby maximizing the weakening of the main harmonic components of the cogging torque, and further achieving the suppression of the cogging torque ripple and reducing the vibration and noise of the motor during operation.

[0037] Please refer to Table 1 and Figure 5 Table 1 is a relationship table of cogging torque change rate with , and Figure 5 is a trend chart of cogging torque change rate with .

[0038] Table 1: Relationship table of cogging torque change rate with

[0039] Cogging Torque is the non-driving torque fluctuation of a permanent magnet motor when it is not powered (i.e. no current in the winding), caused by the periodic change of magnetic attraction force between the permanent magnet and the stator core with the rotor position.

[0040] Figure 5 The ordinate in the figure is the cogging torque change rate, where the cogging torque of the motor at =0.53 is taken as the optimization reference, Figure 5 shows the change of the cogging torque of the motor relative to the reference value under different . As can be seen from the figure, the cogging torque change rate of the motor (expressed in percentage) changes with . The curve in the figure shows a trend of first decreasing and then rising with the increase of .

[0041] With​ The cogging torque change rate continues to decrease from 0.53 to 0.59, and reaches 82% at 0.59, indicating that the cogging torque fluctuation at this time is only 82% of the reference state, that is, it is reduced by 18%; then when continues to increase to 0.63, the torque fluctuation quickly rises back, and finally returns to close to or even slightly higher than the reference level (100.57%). When is too small (such as less than 0.53), the rotor cannot effectively compensate for the periodic change in magnetic resistance caused by the stator side tooth slot due to insufficient harmonic modulation of the magnetic field by the rotor, resulting in high cogging torque; when is too large (such as greater than 0.63), the harmonic modulation of the magnetic field by the rotor is too strong, which may result in harmonic superposition instead of cancellation, or excite other orders of resonance components, thereby exacerbating torque pulsation. When 0.55≤ ≤0.61, the cogging torque change rate is always lower than 88.34%, which is significantly better than the reference design. It shows that the phase alignment and amplitude matching of the reverse harmonic generated by the inter-pole harmonic slot 120 and the mounting slot 110 of the rotor and the harmonic of the stator side tooth slot are achieved, and the mutual cancellation is achieved. Among them, when =0.59, the electromagnetic matching between the rotor structure (inter-pole harmonic slot 120, mounting slot 110) and the stator side tooth slot effect reaches a more optimal state, so that the cogging torque harmonic caused by air gap permeance modulation is maximally cancelled.

[0042] The technical scheme of the present application changes the air gap permeance between the stator and the rotor by providing an inter-pole harmonic slot 120 on the outer peripheral wall of the rotor core 100 corresponding to the inter-pole region between the adjacent two magnetic poles, introduces a reverse harmonic magnetic field to cancel the specific order cogging torque harmonic caused by the stator side tooth slot effect, thereby effectively suppressing the cogging torque fluctuation. At the same time, by limiting 0.55 0.61, the total amount of magnetic field modulation composed of the inter-pole harmonic slot 120 and the mounting slot 110 is controlled, so that it is phase matched with the permeance harmonic caused by the stator tooth 220, and the inter-pole harmonic and the cogging torque fluctuation are effectively suppressed, thereby reducing the vibration and noise of the motor during operation.

[0043] In an embodiment, 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 corresponding to the region jointly defined by the mounting slot 110 and the edge of the rotor core 100, the two first harmonic slots 130 are respectively distributed outside the two second harmonic slots 140 along the circumferential direction of the rotor core 100, and the two first harmonic slots 130 and the two second harmonic slots 140 are both symmetrical about the first center line q1; An angle between the line connecting the side edge of the slot opening 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 a1, and an angle between the line connecting the side edge of the slot opening 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 a2; an angle between the line connecting the side edge of the slot opening 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 a3, and an angle between the line connecting the side edge of the slot opening 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 a4; The minimum distance of the first harmonic slot 130 to the center O of the rotor core 100 is W1, the minimum distance of the second harmonic slot 140 to the center O of the rotor core 100 is W2, and the outer circle radius of the rotor core 100 is R2; Wherein, .

[0044] Two first harmonic slots 130 and two second harmonic slots 140 are arranged in the same magnetic pole region, the two second harmonic slots 140 are arranged close to the first center line q1 and symmetrically arranged about the first center line q1; the second harmonic slot 140 mainly affects the main magnetic flux path, is used for smoothing the main magnetic field gradient, and improves the sine nature of the back electromotive force waveform. The two first harmonic slots 130 are located outside the second harmonic slots 140 (that is, compared with the second harmonic slots 140 in the same magnetic pole region, the first harmonic slots 130 are farther away from the first center line q1), and are symmetrically arranged about the first center line q1; the first harmonic slot 130 is mainly used for adjusting the air gap edge permeance and weakening the high frequency harmonics caused by the stator tooth 220 slot. The two first harmonic slots 130 and the two second harmonic slots 140 are symmetrically designed to ensure that the magnetic field distribution on both sides of the magnetic pole is consistent, and to avoid magnetic bias or single-sided magnetic pulling force.

[0045] The first center line q1 is taken as a reference, and a polar coordinate mode is adopted.

[0046] a1 is an angle between the line connecting the side edge of the slot opening of the first harmonic slot 130 away from the first center line q1 and the center O of the rotor and the first center line q1. The angle determines the position of the outer side boundary of the first harmonic slot 130. The measurement method of a1 is that the center O of the rotor core 100 is taken as a vertex, the line connecting the center O to the side edge of the slot opening of the first harmonic slot 130 away from the first center line q1 is obtained, the line and the first center line q1 are in the same cross section intersected by the plane perpendicular to the axial direction of the rotor core 100, and the angle between the line and the first center line q1 is a1.

[0047] a2 is the angle between the line connecting the center of the rotor core 100 O to the edge of the slot opening of the first harmonic slot 130 near the first center line q1 and the first center line q1 in the same cross section taken by a plane perpendicular to the axial direction of the rotor core 100. The angle a2 is measured as follows: taking the center of the rotor core 100 O as the vertex, connecting the center of the rotor core 100 O to the edge of the slot opening of the first harmonic slot 130 near the first center line q1 to obtain a line, the line and the first center line q1 are in the same cross section taken by a plane perpendicular to the axial direction of the rotor core 100, and the angle between the line and the first center line q1 is a2. a4 represents the central angle corresponding to the circumferential opening width of the second harmonic slot 140, reflecting its modulation width.

[0048] a3 is the angle between the line connecting the center of the rotor core 100 O to the edge of the slot opening of the second harmonic slot 140 away from the first center line q1 and the first center line q1 in the same cross section taken by a plane perpendicular to the axial direction of the rotor core 100. The angle a3 is measured as follows: taking the center of the rotor core 100 O as the vertex, connecting the center of the rotor core 100 O to the edge of the slot opening of the second harmonic slot 140 away from the first center line q1 to obtain a line, the line and the first center line q1 are in the same cross section taken by a plane perpendicular to the axial direction of the rotor core 100, and the angle between the line and the first center line q1 is a3.

[0049] a4 is the angle between the line connecting the center of the rotor core 100 O to the edge of the slot opening of the second harmonic slot 140 near the first center line q1 and the first center line q1 in the same cross section taken by a plane perpendicular to the axial direction of the rotor core 100. The angle a4 determines the inner boundary position of the second harmonic slot 140. The angle a4 is measured as follows: taking the center of the rotor core 100 O as the vertex, connecting the center of the rotor core 100 O to the edge of the slot opening of the second harmonic slot 140 near the first center line q1 to obtain a line, the line and the first center line q1 are in the same cross section taken by a plane perpendicular to the axial direction of the rotor core 100, and the angle between the line and the first center line q1 is a4. a4 represents the central angle corresponding to the circumferential opening width of the second harmonic slot 140, reflecting its modulation width.

[0050] R2 is the outer radius of the rotor core 100, that is, the radius of the unslotted area of the rotor core 100. It can be obtained by measuring the diameter of the outer circle of the rotor core 100 and taking half of the value. For example, when using a vernier caliper to measure the outer radius of the rotor core 100, the measuring jaws are attached to the unslotted area of the outer circle of the rotor core 100, and the diameter is measured multiple times at different axial positions and in the same cross section perpendicular to each other; the average of all measured diameter values is taken and then divided by 2 to obtain the accurate outer radius R2 of the rotor core 100. π is the circular constant.

[0051] W1 is the minimum distance from the first harmonic slot 130 to the center O of the rotor core 100. A height gauge can be used to measure W1: the rotor core 100 is placed flat on a reference platform, with the platform as the reference zero point; the height gauge probe contacts the lowest point of the bottom of the first harmonic slot 130 closest to the center O of the rotor core 100, and the reading W1 is recorded.

[0052] 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 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.

[0053] represents the radial depth of the first harmonic slot 130, representing its modulation strength. is the "width-depth ratio" of the first harmonic slot 130, representing the circumferential modulation density of the first harmonic slot 130, i.e. the circumferential angular span corresponding to a unit radial depth. The larger, the greater the range of magnetic guide modulation that the first harmonic slot 130 can achieve at a shallower depth, and the higher the efficiency. represents the radial depth of the second harmonic slot 140, representing its modulation strength. is the "width-depth ratio" of the second harmonic slot 140, representing the circumferential modulation density of the second harmonic slot 140, i.e. the circumferential angular span corresponding to a unit radial depth. The larger, the greater the range of magnetic guide modulation that the second harmonic slot 140 can achieve at a shallower depth, and the higher the efficiency. The modulation effects of the first harmonic slot 130 and the second harmonic slot 140 are synergistic and interrelated, reflecting the total modulation capability under the synergistic action of the inner and outer two-layer 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.

[0054] represents 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), which is a key parameter determining the magnetic resistance and magnetic flux density. The smaller the air gap, the lower the magnetic resistance, but the more sensitive the harmonic modulation effect. A2 is the coverage angle of the permanent magnet in the center region of the magnetic pole, reflecting the magnetic flux concentration degree of the main magnetic pole. is the spatial characteristic dimension of the main magnetic circuit, representing the basic magnetic field strength level without modulation.

[0055] Let , be a dimensionless ratio. represents the comprehensive strength of the magnetic field disturbance (harmonic) introduced by the double-layer harmonic slot (first harmonic slot 130 and second harmonic slot 140) under a unit main magnetic flux strength. When controlled in the interval of 3.8 to 4.3, it indicates that the harmonic modulation can effectively offset the specific order harmonics caused by the cogging effect, and can avoid triggering new harmonic resonance or weakening the main magnetic flux output capability, thereby achieving effective suppression of the cogging torque fluctuation.

[0056] In addition, by limiting the ratio of the number of rotor poles to the number of stator slots, the rotor and the stator are optimally matched, ensuring that the rotor magnetic poles as a whole are optimally matched with the stator slots; and by limiting the ratio of the number of rotor poles to the number of rotor slots, the rotor itself is optimally structured. In addition, by limiting the ratio of the number of rotor poles to the number of stator slots, the rotor and the stator are optimally matched, ensuring that the rotor magnetic poles as a whole are optimally matched with the stator slots; and by limiting the ratio of the number of rotor poles to the number of rotor slots, the rotor itself is optimally structured. and together ensure that the motor is in an optimal electromagnetic design state from the whole to the part, so that the motor can extremely effectively suppress the cogging torque and the back electromotive force harmonic, thereby effectively reducing the vibration and noise of the motor during operation.

[0057] See Table 2 and Figure 6 Table 2 is a relationship table of torque ripple with , and Figure 6 is a trend chart of torque ripple with .

[0058] Table 2: Relationship table of torque ripple with

[0059] Torque ripple refers to the periodic fluctuation or fluctuation of the output torque of a motor or other rotating machinery around its average value during operation. Torque ripple is quantified by percentage, and torque ripple (%) = (Tmax-Tmin) / Tavg. . Tmax is the maximum torque in a period, Tmin is the minimum torque in a period, and Tavg is the average torque in the period.

[0060] Torque ripple decreases first and then increases with the increase of . With the increase of from 3.6 to 4.2, the torque ripple continues to decrease, indicating that the harmonic suppression effect is enhanced with the increase of . When continues to increase, the torque ripple rises sharply, even exceeding the initial value at 4.4, indicating that the depth or angle of the first harmonic slot 130 and the second harmonic slot 140 is too large, which may cause an increase in magnetic flux leakage; or cause resonance of electromagnetic waves of a specific order, thereby generating additional torque fluctuations.

[0061] As can be seen, when <3.8, the modulation is insufficient, and the harmonic suppression effect is limited; when >4.3, the modulation is too strong, which may introduce new harmonic resonance or destroy the original magnetic field balance, thereby exacerbating torque fluctuations; and when ​​When between 3.8 and 4.3, the torque ripple is kept below 4.31%, indicating that the modulation effect of the first harmonic slot 130 and the second harmonic slot 140 reaches an optimal matching state, effectively offsetting the torque fluctuation caused by the stator side tooth slot and the back electromotive force harmonic.

[0062] In an embodiment, referring to Figure 2 and Figure 3 , 0.80≤ ≤0.86.

[0063] α1 is the angle between the edge of the slot of the first harmonic slot 130 away from the first center line q1 and the line connecting the center of the rotor core 100 and the first center line q1, representing the outer boundary position thereof; and A2 is the coverage angle of the permanent magnet in the central region of the magnetic pole, reflecting the effective magnetic field distribution width of the main magnetic pole; represents the proportion of the modulation region formed by the two first harmonic slots 130 to the entire magnetic pole angle.

[0064] From an electromagnetic perspective, the 5th and 7th harmonics are common main spatial harmonic orders in permanent magnet synchronous motors, which are usually excited by the tooth slot effect of the stator and the unevenness of the rotor permanent magnet, leading to back electromotive force distortion, torque ripple aggravation, and electromagnetic noise increase. By setting the first harmonic slot 130 on the outer periphery of the rotor core 100 and reasonably controlling the position thereof away from the first center line q1 (i.e., adjusting ), a specific phase reverse magnetic field harmonic can be introduced in the air gap, thereby achieving the cancellation of the 5th and 7th harmonics.

[0065] Referring to Table 3 and Figure 7 , Table 3 is a table of the proportion of the 5th and 7th harmonics with , Figure 7 is a trend chart of the proportion of the 5th and 7th harmonics with .

[0066] Table 3: Relationship table of the proportion of the 5th and 7th harmonics with

[0067] Figure 7 The ordinate in Table 3 is the proportion of the 5th and 7th harmonics, i.e., the proportion of the combined content of the 5th and 7th harmonics to the fundamental. The table shows the trend of the proportion of the 5th and 7th harmonics (expressed as a percentage of the fundamental amplitude) in the motor with . The curve in the figure shows a downward trend first and then an upward trend, indicating that as increases, the proportion of the 5th and 7th harmonics significantly decreases first and then increases.

[0068] When ​When increasing from 0.74 to 0.84, the harmonic ratio decreases from about 6.3% to about 4.6%; when When continuously increasing from 0.84, the harmonic ratio increases instead. Specifically, when When less than 0.80, the first harmonic slot 130 is too close to the first center line q1, and the modulation capacity of the first harmonic slot 130 is insufficient to effectively cancel the target harmonic; when When greater than 0.86, the first harmonic slot 130 is too far from the first center line q1, and is too close to the edge of the magnetic pole, which may interfere with the main magnetic flux path, even introduce new harmonic components, and cause the harmonic ratio to rise again; when When in the range of 0.80 to 0.86, the combined content of 5th and 7th harmonics is reduced to below 5%, which is better than other value intervals. In this interval, the first harmonic slot 130 can accurately match the spatial period characteristics of the 5th and 7th harmonics, achieve the best phase alignment and amplitude cancellation, thereby improving the quality of the back electromotive force waveform, reducing the total harmonic distortion, and reducing the torque ripple of the motor to reduce the vibration and noise of the motor during operation.

[0069] In an embodiment, please refer to Figure 2 and Figure 3 , 0.84≤ ≤0.89.

[0070] α4 is the angle between the edge of the second harmonic slot 140 close to the first center line q1 and the line connecting the center O of the rotor core 100 and the first center line q1, reflecting the position of the inner side boundary of the second harmonic slot 140; A3 is the angle formed by the intersection 114 of the outer side of the second clamping slot 112 and the first and third clamping slots 113 and the center O of the rotor core 100, representing the width of the mounting slot 110 close to the rotor shaft end; represents the proportional relationship between the position of the second harmonic slot 140 close to the first center line q1 and the internal magnetic circuit width of the second clamping slot 112, and its physical meaning is to coordinate the spatial matching relationship between the second harmonic slot 140 and the second clamping slot 112, to adjust the permeance 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 edge concentration of the permanent magnet.

[0071] Please refer to Table 4 and Figure 8 Table 4 is a relationship table of the 5th and 7th harmonic ratios with , and Figure 8 is a trend chart of the 5th and 7th harmonic ratios with .

[0072] Table 4: Relationship table of 5th and 7th harmonic ratios with

[0073] ​Figure 8 The ordinate in the figure is the ratio of the 5th and 7th harmonic, i.e., the ratio of the 5th and 7th harmonic content to the fundamental. The figure shows the trend of the ratio of the 5th and 7th harmonic (expressed as a percentage of the fundamental amplitude) in the motor with the increase of The curve in the figure shows a downward trend first and then an upward trend, indicating that with the increase of , the ratio of the 5th and 7th harmonic decreases significantly first and then increases.

[0074] When increases from 0.82 to 0.87, the harmonic ratio decreases from about 5.35% to about 4.64%; when continues to increase, the harmonic ratio instead increases. Specifically, 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, which cannot sufficiently weaken the magnetic flux concentration effect at the edge of the permanent magnet, resulting in a high ratio of the 5th and 7th harmonic; when >0.89, the second harmonic slot 140 is farther away from the first center line q1, which may cause an increase in the leakage of the main magnetic flux or a sudden change in the local magnetic resistance, thereby exciting new harmonic components and causing the harmonic ratio to increase. When between 0.84 and 0.88, the second harmonic slot 140 is located at an optimal position, which can effectively adjust the air gap permeance distribution, improve the sinusoidal nature of the back electromotive force waveform, reduce the total harmonic distortion rate and torque ripple, so that the motor runs more smoothly and has lower vibration and noise.

[0075] In an embodiment, please refer to Figure 1 , 10≤2P≤12.

[0076] The total number of magnetic poles of the motor is limited to satisfy 10≤2P≤12, i.e., the motor is a 10-pole, 11-pole or 12-pole structure (P is the number of pole pairs). In a permanent magnet synchronous motor, the number of poles affects the spatial distribution frequency of the air gap magnetic field, the back electromotive force waveform, the torque density and the cogging torque characteristics. When 2P<10, the pole pitch is large, the magnetic field changes slowly, resulting in a low frequency of the back electromotive force, which limits the output power of the motor at the same speed, and a large torque ripple and vibration noise are easily caused by the low number of poles; when 2P>12, the pole pitch is too small, the interaction between the stator teeth 220 and the rotor structure is more frequent, which can improve the torque smoothness, but increases the rotor core 100 loss, manufacturing difficulty and high-frequency harmonic ratio, and requires a higher response speed of the controller.

[0077] By limiting 10≤2P≤12, on the one hand, the magnetic field modulation period is refined, the air gap magnetic flux density distribution tends to be sinusoidal, low-order harmonics such as 5th and 7th order are effectively suppressed, and the cogging torque and operating noise are reduced; on the other hand, a reasonable slot-pole combination can be ensured, the risk of harmonic resonance is reduced, the winding leakage inductance and copper loss are reduced, and the motor efficiency and power density are improved.

[0078] In an embodiment, please refer to Figure 1 15≤Q≤18.

[0079] The number of stator slots of the motor is limited to 15≤Q≤18, that is, 15 to 18 stator slots 230 are uniformly arranged along the inner periphery of the stator core 200 for embedding the stator winding. 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, and further affect the magnetic field modulation effect and winding distribution characteristics. In combination with the preferred pole combination 10≤2P≤12 of the application, when 15≤Q≤18, a good slot-pole combination can be achieved. For example, Q=18 and 2P=12 form an integer-slot winding, which has good symmetry and mature manufacturing process; Q=15 or 18 and 2P=10 form a fractional-slot winding, which helps to disperse the magnetic motive force harmonics and reduce the cogging torque. If Q<15, the slot pitch of the stator slot 230 is too large, resulting in discontinuous variation of air gap permeance, serious distortion of back electromotive force waveform, high harmonic proportion, and significant increase in vibration and noise; if Q>18, the slot opening density of the stator slot 230 is too high, which not only increases the difficulty of lamination process of the stator core 200, but also may cause high-frequency electromagnetic resonance, and the slot opening leakage inductance increases, affecting the motor efficiency and dynamic response. By limiting 15≤Q≤18, the spatial matching relationship of the rotor harmonic slots (including the inter-pole harmonic slots 120, the first harmonic slots 130, and the second harmonic slots 140) and the installation slots 110 structure can be optimized while ensuring good electromagnetic performance.

[0080] In an embodiment, 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

[0081] The number of phases of the motor is m, the number of stator slots is Q, and the number of pole pairs is P. The number of slots per pole per phase q is defined as Q / 2mP, and q satisfies: 0

[0082] The fractional slot structure can form a non-common multiple slot-pole matching between the number of stator slots and the number of rotor poles, effectively dispersing the spatial harmonic energy of the air gap magnetic field, avoiding harmonic concentration and superposition, thereby significantly reducing the cogging torque and torque ripple. Secondly, such a winding generally has a shorter end length, reducing copper loss and improving motor efficiency and power density. In addition, the structure of q<1 helps to achieve a more uniform magnetic field modulation, which cooperates with the rotor topology structure such as the inter-pole harmonic slot 120, the first harmonic slot 130 and the second harmonic slot 140, and the multi-section mounting slot 110 provided in the application, further optimizes the air gap flux waveform, making it more close to sinusoidal distribution, and suppressing the 5th, 7th, etc. Main harmonic components in back electromotive force. At the same time, q>0 ensures that each phase has conductors working under each magnetic pole, maintaining the basic electromagnetic conversion capability.

[0083] In an embodiment, the greatest common divisor of the number Q of stator slots 230 and the number P of poles of the rotor satisfies: 5≤GCD(Q, P)≤6.

[0084] In a permanent magnet synchronous motor, the relative motion of stator slotting and rotor magnetic pole will produce periodic magnetic guide change, and its harmonic characteristics are closely related to the common divisor of Q and P. GCD(Q, P) reflects the minimum repetition period of electromagnetic interaction between the stator and the rotor. When GCD(Q, P) is too small (such as 1 or 2), it means that the matching period of the stator slot 230 and the magnetic pole is short, the repetition frequency of the cogging effect is low, and it is easy to excite low-order mechanical resonance, resulting in obvious vibration and noise; when GCD(Q, P) is too large (such as ≥7), it means that the matching period of the stator slot 230 and the magnetic pole is long, thereby causing the winding design to be complicated or introducing new low-frequency disturbance. By limiting 5≤GCD(Q, P)≤6, the motor has a longer and stable electromagnetic period structure, the spatial symmetry of electromagnetic force wave is enhanced, the harmonic energy is effectively dispersed, which helps to reduce the cogging torque and torque ripple.

[0085] The application also provides a compressor comprising the motor, the specific structure of which is referred to the above embodiments. Since the compressor adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0086] The application also provides a refrigeration equipment comprising the compressor, the specific structure of which is referred to the above embodiments. Since the refrigeration equipment adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0087] The above merely illustrates the embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like, within the technical concept of the present application, and based on the content of the present application specification and drawings, are included in the patent protection scope of the present application.

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.

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