Rotor core, motor and household appliance

Abstract

The invention discloses a rotor iron core, a motor and a household appliance, and relates to the technical field of motors, the rotor iron core comprises a plurality of fan-shaped parts arranged around a rotation axis, and a plurality of arc-shaped convex parts are arranged on the outer sides of the fan-shaped parts, so that the magnetic field distribution can be optimized, and the magnetic flux distribution and magnetic resistance change of a rotor can be changed; and the nonuniformity of the magnetic field in the rotation process is reduced, so that the magnetic flux change of the motor in the rotation process is smoother. The magnetic field abrupt change is reduced, so that the pulsation of the torque and the cogging torque are reduced, the vibration and the noise of the motor are reduced, the waveform of the counter electromotive force is closer to sine waves, the total harmonic distortion of the counter electromotive force is reduced, the electromagnetic interference and the loss of the motor are reduced, and the operation efficiency of the motor is improved. And the number of the convex parts is 2-14, so that the amplitude of the fundamental wave is ensured to be in a proper range, the influence on the magnetic flux density of the fundamental wave is reduced to the minimum extent while harmonic waves are suppressed, and the performance of the motor is improved.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a rotor core motor and household appliances. Background Technology

[0002] The rotor of a permanent magnet motor has an arc-shaped outer surface, and the gap between it and the stator winding slots is unevenly distributed. During motor rotation, this uneven gap causes periodic changes in the air gap magnetic permeability, generating harmonics. These harmonic components superimpose on the fundamental frequency, complicating the magnetic field within the motor and leading to increased cogging torque. Cogging torque is a periodically changing torque generated by the interaction between the stator and rotor. This torque fluctuation causes motor vibration and noise, degrading motor performance. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a rotor core that can reduce the cogging torque, torque pulsation, radial electromagnetic force and back EMF of the motor, reduce noise, and at the same time reduce the equivalent air gap of the motor, thereby improving the performance of the motor.

[0004] The present invention also proposes a motor and a household appliance having the above-mentioned rotor core.

[0005] An electric motor according to a first aspect embodiment of the present invention includes:

[0006] Multiple sector-shaped portions are arranged around the rotation axis, and mounting grooves for mounting permanent magnets are formed between adjacent sector-shaped portions. Each sector-shaped portion includes multiple lamination units stacked along the rotation axis. At least one lamination unit has N arc-shaped protrusions on its outer side wall, satisfying: 2≤N≤14.

[0007] The rotor core according to embodiments of the present invention has at least the following beneficial effects:

[0008] By setting N arc-shaped protrusions on the outer side of the sector section, the magnetic field distribution can be optimized, the magnetic flux distribution and reluctance changes of the rotor can be changed, and the non-uniformity of the magnetic field during rotation can be reduced, making the magnetic flux change of the motor smoother during rotation. This helps to reduce abrupt changes in the magnetic field, thereby reducing torque pulsation and cogging torque. At the same time, it can change the air gap magnetic flux density distribution of the motor, making the air gap magnetic flux density more uniform. This helps to reduce the non-uniformity of radial electromagnetic force, reduce motor vibration and noise, and make the back EMF waveform closer to a sine wave, reducing the total harmonic distortion of the back EMF, reducing electromagnetic interference and losses of the motor, and improving the operating efficiency of the motor. The number of protrusions is N and ranges from 2 to 14, ensuring that the fundamental frequency amplitude is within a suitable range, so as to suppress harmonics while minimizing the impact on the fundamental frequency magnetic flux density, thereby improving the performance of the motor.

[0009] According to some embodiments of the present invention, the radius of the maximum circumscribed circle of the rotor core is R1, the number of the sector portions is 2P, and in two adjacent protrusions, the end of the outer wall of one of the protrusions that is farthest from the rotation axis is the first endpoint, and the end of the outer wall of the other protrusion that is farthest from the rotation axis is the second endpoint. The distance between the first endpoint and the second endpoint is L, which satisfies: L≤0.4πR1 / P.

[0010] According to some embodiments of the present invention, along the circumference of the rotor core, the two opposite side walls of the fan-shaped portion protrude outward to form limiting portions, the limiting portions being used to abut the end of the permanent magnet away from the rotation axis, the farthest distance of the outer side wall of the limiting portion from the rotation axis being R2, and the radius of the largest circumscribed circle of the rotor core being R1, satisfying: 0.93≤R1 / R2≤0.99.

[0011] According to some embodiments of the present invention, the outer wall of the lamination unit is connected by a recess between two adjacent protrusions, the radius of the maximum circumscribed circle of the rotor core is R1, and the shortest distance from the outer wall of the recess to the rotation axis is R3, satisfying: 0.8≤R3 / R1<1.

[0012] According to some embodiments of the present invention, the N protrusions of the lamination unit are asymmetrically arranged with respect to the radial reference surface, and the rotation axis is located within the radial reference surface.

[0013] According to some embodiments of the present invention, N is 2, the two protrusions are connected by a concave portion, the end of the concave portion closest to the rotation axis is the third endpoint, and along the circumference of the rotor core, the two opposite side walls of the fan-shaped portion protrude outward to form limiting portions, the farthest distance between one of the limiting portions and the third endpoint is d1, and the farthest distance between the other limiting portion and the third endpoint is d2, satisfying: 0.1≤d1 / d2<1.

[0014] According to some embodiments of the present invention, on a projection plane perpendicular to the axis of rotation, the outer contour lines of two adjacent protrusions of the lamination unit are smoothly connected by an arc concave towards the axis of rotation; or, the outer contour lines of two adjacent protrusions of the lamination unit are connected by a straight line; or, the outer contour lines of two adjacent protrusions of the lamination unit intersect.

[0015] According to some embodiments of the present invention, the circumscribed circles of the N protrusions of the lamination unit coincide.

[0016] According to a second aspect of the present invention, an electric motor includes a stator assembly and a rotor core as described in the above embodiments, wherein the stator assembly is wound around the outside of the rotor core.

[0017] The motor according to embodiments of the present invention has at least the following beneficial effects:

[0018] By employing the rotor core of the first aspect embodiment, the rotor core, through the arrangement of N arc-shaped protrusions on the outer side of the sector portion, can optimize the magnetic field distribution, alter the magnetic flux distribution and reluctance changes of the rotor, and reduce the non-uniformity of the magnetic field during rotation, resulting in smoother magnetic flux changes during motor rotation. This helps reduce abrupt changes in the magnetic field, thereby reducing torque pulsation and cogging torque. Simultaneously, it can alter the air gap magnetic flux density distribution of the motor, making the air gap magnetic flux density more uniform. This helps reduce the non-uniformity of radial electromagnetic force, reducing motor vibration and noise, and can make the back EMF waveform closer to a sine wave, reducing total harmonic distortion of the back EMF, reducing electromagnetic interference and losses of the motor, and improving motor operating efficiency. The N protrusions, ranging from 2 to 14, ensure that the fundamental amplitude is within a suitable range, suppressing harmonics while minimizing the impact on the fundamental magnetic flux density, thereby improving motor performance.

[0019] According to some embodiments of the present invention, the motor includes X phase lines, one end of the X phase lines is connected to each other, and the number N of the protrusions of the lamination unit satisfies: N = X - 1, where X is an integer greater than or equal to 3.

[0020] According to some embodiments of the present invention, the stator assembly includes a stator core, the stator core having a plurality of winding slots arranged at intervals along the circumference of the rotor core, the number of winding slots being Ns, and the number of poles of the rotor core being 2P, satisfying: Ns=2P±2.

[0021] According to some embodiments of the present invention, the stator assembly includes a stator core, the stator core having a plurality of winding slots arranged circumferentially along the rotor core, the number of winding slots being 12, and the number of poles of the rotor core being 10.

[0022] According to some embodiments of the present invention, the stator assembly includes a stator core, the stator core having a plurality of winding slots arranged at intervals along the circumference of the rotor core, the number of winding slots being Ns, and the number of poles of the rotor core being 2P, satisfying: Ns=2P±4.

[0023] According to a third aspect of the present invention, a household appliance includes the motor described in the above embodiments.

[0024] The household appliances according to embodiments of the present invention have at least the following beneficial effects:

[0025] By employing the motor of the second aspect embodiment, the rotor core of the motor, through the arrangement of N arc-shaped protrusions on the outer side of the sector portion, can optimize the magnetic field distribution, alter the magnetic flux distribution and reluctance changes of the rotor, and reduce the non-uniformity of the magnetic field during rotation, resulting in smoother magnetic flux changes during motor rotation. This helps reduce abrupt changes in the magnetic field, thereby reducing torque pulsation and cogging torque. Simultaneously, it can alter the air gap magnetic flux density distribution of the motor, making the air gap magnetic flux density more uniform. This helps reduce the non-uniformity of radial electromagnetic force, lowering motor vibration and noise, and making the back EMF waveform closer to a sine wave, reducing total harmonic distortion of the back EMF, reducing electromagnetic interference and losses of the motor, and improving motor operating efficiency. The presence of N protrusions within the range of 2 to 14 ensures that the fundamental frequency amplitude is within a suitable range, suppressing harmonics while minimizing the impact on the fundamental magnetic flux density, thereby improving motor performance.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 This is a schematic diagram of the structure of a motor according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of a rotor assembly according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of the sector-shaped portion according to an embodiment of the present invention;

[0031] Figure 4 yes Figure 3 Enlarged view of point A in the middle;

[0032] Figure 5 This is a schematic diagram of the structure of the sector-shaped portion according to another embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the structure of the sector-shaped portion according to another embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the structure of the sector-shaped portion according to another embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of the structure of the sector-shaped portion according to another embodiment of the present invention;

[0036] Figure 9 A graph comparing the back potential of a motor according to an embodiment of the present invention and a motor in the prior art;

[0037] Figure 10 This is a bar chart showing the maximum value of the back potential FFT of a motor according to an embodiment of the present invention and a motor in the prior art;

[0038] Figure 11 This is a graph comparing the line back electromotive force of a motor according to an embodiment of the present invention and a motor in the prior art.

[0039] Figure 12 This is a bar chart showing the maximum value of the line back electromotive force (FFT) of a motor according to an embodiment of the present invention and a motor in the prior art.

[0040] Figure 13 This is a graph comparing the cogging torque of a motor according to an embodiment of the present invention with that of a motor in the prior art.

[0041] Figure label:

[0042] Rotor assembly 100; sector-shaped part 110; lamination unit 111; protrusion 112; recess 113; limiting part 114; mounting groove 115; permanent magnet 120; rotor core 130;

[0043] Stator assembly 200; stator core 210; toothed section 211; yoke 212; winding slot 213. Detailed Implementation

[0044] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0045] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0046] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0047] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0048] Motors contain fundamental and harmonic frequencies. The fundamental frequency, also known as the fundamental frequency, refers to the basic frequency at which the rotor of an AC motor rotates, which is also the power supply frequency. Harmonics refer to electrical signals whose frequencies are integer multiples of the fundamental frequency. In AC motors, harmonics are mainly generated by the nonlinear characteristics of magnetic flux and the filtering effect of the capacitors and inductors inside the motor on the AC signal. Harmonics are generated when the frequencies of the capacitors and inductors are equal to the signal frequency. These components are usually called higher harmonics; for example, a wave three times the fundamental frequency is called the third harmonic, and a wave five times the fundamental frequency is called the fifth harmonic.

[0049] In electric motors, it is generally necessary to suppress harmonics and retain the fundamental frequency as much as possible. This is because the fundamental frequency is the essential frequency upon which the motor relies for normal operation, while harmonics can negatively impact the motor's performance and stability. For example, they can cause unstable operation, generate additional heat and losses, and reduce the motor's efficiency and lifespan. Harmonics can also induce vibration and noise, interfering with the motor's normal operation and the working environment. Therefore, to reduce these negative impacts, measures are typically taken to suppress the generation and propagation of harmonics.

[0050] Therefore, referring to Figure 1 and Figure 2 As shown, the rotor core 130 of one embodiment of the present invention can be used in a motor, such as a permanent magnet motor. The rotor core 130 of this embodiment includes a plurality of sector-shaped portions 110, which are arranged around a rotation axis. A mounting groove 115 for mounting a permanent magnet 120 is formed between adjacent sector-shaped portions 110. Each sector-shaped portion 110 includes a plurality of lamination units 111, which are stacked axially along the rotation axis. (Refer to...) Figure 3 and Figure 4 As shown, at least one lamination unit 111 has N arc-shaped protrusions 112 on its outer wall, satisfying the following condition: 2 ≤ N ≤ 14, for example, N can be 3, 4, 5, 6, etc. Figure 3 The lamination unit 111 in the middle is provided with two protrusions 112. Figure 5 The lamination unit 111 in the middle has three protrusions 112.

[0051] By providing N arc-shaped protrusions 112 on the outer side of the sector 110, the magnetic field distribution can be optimized, the magnetic flux distribution and reluctance changes of the rotor can be changed, and the non-uniformity of the magnetic field during rotation can be reduced, making the magnetic flux change of the motor smoother during rotation. This helps to reduce abrupt changes in the magnetic field, thereby reducing torque pulsation and cogging torque. At the same time, it can change the air gap magnetic flux density distribution of the motor, making the air gap magnetic flux density more uniform. This helps to reduce the non-uniformity of radial electromagnetic force, reduce motor vibration and noise, and make the back EMF waveform closer to a sine wave, reducing the total harmonic distortion of the back EMF, reducing electromagnetic interference and losses of the motor, and improving the operating efficiency of the motor.

[0052] When N is less than 2 (i.e., N = 1), a larger fundamental frequency amplitude needs to be sacrificed to suppress harmonics. Since a larger fundamental frequency amplitude results in higher motor efficiency, N less than 2 leads to reduced motor efficiency. When N is greater than 14, only higher-order harmonics can be suppressed, with limited effect on lower-order harmonics. For example, the suppression effect on the 3rd, 5th, 7th, and 9th harmonics is minimal. Even if the fundamental frequency of the motor is high at this time, the presence of harmonics will cause increased motor vibration and generate greater noise. Therefore, the number of protrusions 112 is set within the range of 2 to 14, with different numbers of protrusions 112 depending on the type of motor, to suppress harmonics while minimizing the impact on the fundamental magnetic flux density, thereby improving motor performance.

[0053] Reference Figure 3 and Figure 4 As shown, Figure 3 The dotted line in the middle represents the maximum circumscribed circle S1 of the rotor core 130. In this embodiment of the invention, the radius of the maximum circumscribed circle S1 of the rotor core 130 is R1, the number of sector portions 110 is 2P, and the number of sector portions 110 is the same as the number of permanent magnets 120. In two adjacent protrusions 112, the end of the outer wall of one protrusion 112 that is farthest from the rotation axis is the first endpoint, and the end of the outer wall of the other protrusion 112 that is farthest from the rotation axis is the second endpoint. The distance between the first endpoint and the second endpoint is L, which satisfies: L≤0.4*2*π*R1 / (2P). It should be noted that the above formula can be simplified to L≤0.4*π*R1 / P. Here, 2π*R1 refers to the circumference of the circumscribed circle S1, and 2π*R1 / (2P) refers to the pole pitch occupied by each pole in the motor. When L > π*R1*0.4 / P, the distance between two adjacent protrusions 112 is too large, making it difficult to suppress harmonics. Furthermore, the space on the lamination unit 111 is limited, making it difficult to infinitely expand the distance between adjacent protrusions 112. Therefore, a reasonable design of the value of L can suppress harmonics while ensuring that the distance between the protrusions 112 is designed reasonably and reliably.

[0054] Reference Figure 3As shown, in an embodiment of the present invention, along the circumference of the rotor core 130, the two opposite side walls of the fan-shaped portion 110 protrude outward to form limiting portions 114. The limiting portions 114 are used to abut against the end of the permanent magnet 120 furthest from the rotation axis. The furthest distance from the outer side wall of the limiting portion 114 to the rotation axis is R2, and the radius of the maximum circumscribed circle S1 of the rotor core 130 is R1, satisfying: 0.93 ≤ R1 / R2 ≤ 0.99. For example, R1 / R2 can be 0.94, 0.95, 0.96, 0.97, 0.98, etc. When R1 / R2 is less than 0.93, although unwanted harmonics can be better suppressed, the fundamental frequency loss is relatively large, resulting in significant performance loss of the motor. When R1 / R2 is greater than 0.99, it is difficult to suppress unwanted harmonics, leading to torque pulsation, increased cogging torque, and consequently increased noise. Therefore, by properly designing the values ​​of R1 / R2, unwanted harmonics can be suppressed while ensuring that the amplitude of the fundamental wave is at an appropriate level, thereby reducing the performance loss of the motor.

[0055] Reference Figure 4 As shown, in an embodiment of the present invention, the outer wall of the lamination unit 111 is transitionally connected between two adjacent protrusions 112 via a recess 113. The shortest distance from the outer wall of the recess 113 to the rotation axis is R3, satisfying: 0.8 ≤ R3 / R1 < 1, for example, R3 / R1 is 0.83, 0.85, 0.9, 0.93, 0.95, 0.99, etc. When R3 / R1 is less than 0.8, that is, the radial depth of the recess 113 is too deep, resulting in an increase in the equivalent air gap and a decrease in the fundamental magnetic flux density. When R3 / R1 is equal to 1, there is no effect on suppressing harmonics. Therefore, by reasonably designing the size of R3 / R1, it can be ensured that the equivalent air gap will not increase significantly, thereby improving the fundamental magnetic flux density, while suppressing harmonics to reduce cogging torque, and thus reducing the noise during motor operation.

[0056] Reference Figure 4 As shown, in an embodiment of the present invention, on a projection plane perpendicular to the rotation axis, the outer contour lines of two adjacent protrusions 112 of the lamination unit 111 are smoothly connected by an arc line S3 that is recessed toward the rotation axis. Due to the smoothness and continuity of the arc line itself, it helps to reduce electromagnetic interference during current commutation, thereby suppressing the generation of harmonics. Alternatively, refer to... Figure 6 As shown, the outer contour lines of two adjacent protrusions 112 in the lamination unit 111 are connected by a straight line S4. The straight line S4 connection has the advantages of simple structure and convenient processing, which can reduce manufacturing costs. Alternatively, refer to... Figure 7 As shown, the outer contour lines of two adjacent protrusions 112 of the lamination unit 111 intersect, which can make the structure of the lamination unit 111 more compact and reduce space occupation. The appropriate solution should be selected according to the actual situation.

[0057] Reference Figure 8 As shown, Figure 8 The dashed line in the diagram represents the symmetry line S2. In this embodiment of the invention, the N protrusions 112 of the lamination unit 111 are asymmetrically arranged relative to the radial reference plane, and the rotation axis is located within the radial reference plane. That is, the N protrusions 112 of the lamination unit 111 are asymmetrically arranged relative to the symmetry line S2. For example, when the rotor core 130 operates, it rotates counterclockwise. There are two protrusions 112, and a recess 113 is formed between the two protrusions 112. The end of the recess 113 closest to the rotation axis is the third endpoint. The farthest distance between the left limiting part 114 and the third endpoint is d1, and the farthest distance between the right limiting part 114 and the third endpoint is d2, satisfying: 0.1 ≤ d1 / d2 < 1. For example, d1 / d2 can be 0.3, 0.4, 0.5, 0.6, or 0.8. Generally, under the no-load condition of the motor, the harmonics of the air gap magnetic flux density of the motor are symmetrical. However, since the armature reaction is unilaterally asymmetrical, under load conditions, it can lead to asymmetrical air gap magnetic flux density in the motor. Therefore, by providing asymmetrical protrusions 112 on the outer surface of the lamination unit 111, the asymmetry caused by the armature reaction under load conditions can be mitigated, the asymmetry degree reduced, and the smoothness of motor operation improved. In another embodiment, the N protrusions 112 of the lamination unit 111 can also be symmetrical relative to the radial reference plane, with the appropriate scheme selected based on the actual situation.

[0058] Reference Figure 4 As shown, in the embodiment of the present invention, the circumscribed circles of the N protrusions 112 of the lamination unit 111 coincide, meaning that the farthest distance between the N protrusions 112 and the rotation axis is the same. Therefore, the overall weight of the rotor core 130 can be balanced, avoiding instability caused by uneven weight distribution, and improving the smoothness of the rotor core 130 during rotation. The protrusions 112 can change the electromagnetic field distribution on the rotor surface, thereby optimizing the magnetic flux path and electromagnetic conversion efficiency of the motor. This helps reduce energy loss and improve the efficiency of the motor.

[0059] An embodiment of the present invention provides a motor comprising a rotor assembly 100 and a stator assembly 200. The rotor assembly 100 includes a permanent magnet 120 and a rotor core 130 as described in the previous embodiment. The permanent magnet 120 is mounted in a mounting groove 115, and the stator assembly 200 is wound around the outside of the rotor core 130. The stator assembly 200 includes a stator core 210, which is annular and includes a yoke 212 and a plurality of teeth 211. The plurality of teeth 211 are spaced apart on the inner wall of the yoke 212, and a winding groove 213 is formed between adjacent teeth 211. The winding can be wound on the teeth 211 through the winding groove 213. When the winding is energized, it can generate a magnetic field. By changing the direction of the current, an alternating magnetic field is generated, which interacts with the magnetic field of the permanent magnet 120 to drive the rotor assembly 100 to rotate.

[0060] The motor of this embodiment uses the stator core 210 of the above embodiment. The stator core 210, by providing N arc-shaped protrusions 112 on the outer side of the sector-shaped portion 110, can optimize the magnetic field distribution, change the rotor's magnetic flux distribution and reluctance changes, reduce the non-uniformity of the magnetic field during rotation, and make the magnetic flux change smoother during motor rotation. This helps reduce abrupt changes in the magnetic field, thereby reducing torque pulsation and cogging torque. Simultaneously, it can change the air gap magnetic flux density distribution of the motor, making the air gap magnetic flux density more uniform. This helps reduce the non-uniformity of radial electromagnetic force, reduce motor vibration and noise, and make the back EMF waveform closer to a sine wave, reducing the total harmonic distortion of the back EMF, reducing electromagnetic interference and losses of the motor, and improving the motor's operating efficiency. The N protrusions 112, ranging from 2 to 14, ensure that the fundamental frequency amplitude is within a suitable range, suppressing harmonics while minimizing the impact on the fundamental frequency magnetic flux density, thereby improving motor performance.

[0061] In related technologies, arc cutting can be used, such as significantly cutting the outer surface of the rotor core and the inner surface of the stator assembly. Although this can reduce the torque pulsation, cogging torque, radial electromagnetic force and noise of the permanent magnet motor, it will lead to a significant increase in the equivalent air gap of the motor, which will significantly reduce the performance of the motor.

[0062] In an embodiment of the present invention, the motor includes X phase lines, one end of which is connected. The number N of protrusions 112 in the lamination unit 111 satisfies: N = X - 1, where X is an integer greater than or equal to 3. For example, when X is 3 and N is 2, the motor is a three-phase motor, and one lamination unit 111 has two protrusions 112. During operation, the rotor core 130 of this embodiment cannot effectively suppress the 3rd harmonic and multiples of 3, but it can suppress other harmonics. That is, a portion of the 3rd harmonic and multiples of 3 is retained, and the presence of harmonics can increase the amplitude of the fundamental wave. However, the 3rd harmonic and multiples of 3 still need to be suppressed. By applying the rotor core 130 of this embodiment to a three-phase motor, and the three-phase motor adopting a star connection, the three-phase motor with a star connection does not have the 3rd harmonic and multiples of 3.

[0063] For example, refer to Figure 9 and Figure 10 As shown, Figure 9 The horizontal axis represents the electric period, and the vertical axis represents the opposite potential. Figure 9 The curves in the figure reflect the waveforms of opposite potentials. The curves with square symbols are the waveforms of solutions in related technologies, and the curves with diamond symbols are the waveforms when N is 2 in the embodiments of the present invention. Figure 10The horizontal axis represents the order of harmonics, such as the 1st harmonic, which is the fundamental wave, and 3 represents the 3rd harmonic. The vertical axis represents the maximum value of the reverse potential FFT. The lighter colors represent the solutions in related technologies, and the darker colors represent the solutions in this embodiment where N is 2.

[0064] It should be noted that the back potential measures the potential from a single phase to the center point of connection. For example, a three-phase motor includes phases A, B, and C, and the ends of phases A, B, and C are connected together to form a common point. The back potential measures the potential between any one of phases A, B, or C and this common point. Therefore, in Figure 10 You can still see the third harmonic and its multiples, while other harmonics are basically suppressed.

[0065] And reference Figure 11 and Figure 12 As shown, Figure 11 The horizontal axis represents the electric period, and the vertical axis represents the line back electromotive force. Figure 11 The curves in the figure reflect the waveform of the line back potential. The curves with square symbols are the waveforms of the solutions in related technologies, and the curves with triangle symbols are the waveforms when N is 2 in the embodiments of this invention. Figure 12 The horizontal axis represents the order of harmonics, such as the 1st harmonic, which is the fundamental wave, and 3 represents the 3rd harmonic. The vertical axis represents the maximum value of the line back potential FFT. The lighter colors represent the solutions in related technologies, and the darker colors represent the solutions in this embodiment where N is 2.

[0066] It should be noted that line back EMF measures the potential between two phases. For example, in a three-phase motor consisting of phases A, B, and C, with the ends of phases A, B, and C connected together to form a common point, line back EMF measures the potential between any two of phases A, B, and C. That is, in a star connection of a three-phase motor, in... Figure 12 The third harmonic and its multiples are almost invisible, while other harmonics are basically suppressed. It can also be seen that the fundamental amplitude of the line back EMF of the embodiment of the present invention is greater than that of the fundamental amplitude in the related art, by about 5.8%.

[0067] At the same time, refer to Figure 13 As shown, Figure 13 The horizontal axis represents the electrical cycle, and the vertical axis represents the cogging torque. Figure 13The curves with square patterns represent solutions in related technologies, while the curves with diamond symbols represent solutions from embodiments of the present invention. As can be seen from the figures, using the solution of this embodiment, the peak value of the cogging torque is reduced from 4.9 mNm to 0.9 mNm, a reduction of 81.6%. Therefore, using the solution of this embodiment can improve the fundamental amplitude while reducing torque ripple, cogging torque, radial electromagnetic force, and improving back EMF (THD), without significantly increasing the equivalent air gap of the motor, thus reducing the impact on motor performance.

[0068] When N is 3, the rotor core 130 of this embodiment cannot effectively suppress the 4th harmonic and its multiples thereof, but it can suppress other harmonics. The rotor core 130 of this embodiment can be applied to a four-phase motor, where one end of each of the four phase lines is connected, similar to a star connection. This embodiment of the motor does not have the 4th harmonic and its multiples thereof. Using the above solution, the fundamental amplitude can be increased while simultaneously reducing the impact of harmonics on motor performance. The other numbers of protrusions 112 and their applicable motors are analogous and will not be elaborated further here.

[0069] In embodiments of the present invention, the stator assembly 200 includes a stator core 210, which has a plurality of winding slots 213 arranged circumferentially along the rotor core 130. The number of winding slots 213 is NS, and the number of poles of the rotor core 130 is 2P, satisfying: NS = 2P ± 2, or satisfying: NS = 2P ± 4. For example, the number of winding slots 213 is 12, and the number of poles of the rotor core 130 is 10; or the number of winding slots 213 is 12, and the number of poles of the rotor core 130 is 8. By adjusting the relationship between the number of winding slots 213 and the number of rotor poles, the torque characteristics of the motor can be optimized, making the motor run more smoothly, reducing torque pulsation and vibration, which helps to improve the operating efficiency of the motor, reduce energy loss, and make the motor have lower energy consumption under the same power output.

[0070] This invention discloses a household appliance according to one embodiment, including the motor described in the above embodiments. The appliance can be a fan, air conditioner, refrigerator, drum washing machine, etc. The household appliance of this embodiment uses the motor described in the above embodiments. The stator core 210 of the motor, by providing N arc-shaped protrusions 112 on the outer side of the sector-shaped portion 110, can optimize the magnetic field distribution, change the magnetic flux distribution and reluctance changes of the rotor, reduce the non-uniformity of the magnetic field during rotation, and make the magnetic flux change during motor rotation smoother. This helps reduce abrupt changes in the magnetic field, thereby reducing torque pulsation and cogging torque. Simultaneously, it can change the air gap magnetic flux density distribution of the motor, making the air gap magnetic flux density more uniform. This helps reduce the non-uniformity of the radial electromagnetic force, reduce motor vibration and noise, and make the back EMF waveform closer to a sine wave, reducing the total harmonic distortion of the back EMF, reducing electromagnetic interference and losses of the motor, and improving the operating efficiency of the motor. The N protrusions 112, ranging from 2 to 14, ensure that the fundamental frequency amplitude is within a suitable range, suppressing harmonics while minimizing the impact on the fundamental magnetic flux density, thereby improving motor performance.

[0071] Since the home appliance adopts all the technical solutions of the motor in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments, which will not be repeated here.

[0072] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A rotor core, characterized in that, include: Multiple sector-shaped portions are arranged around the rotation axis, and mounting grooves for mounting permanent magnets are formed between adjacent sector-shaped portions. Each sector-shaped portion includes multiple lamination units stacked along the rotation axis. At least one lamination unit has N arc-shaped protrusions on its outer side wall, satisfying: 2≤N≤14.

2. The rotor core according to claim 1, characterized in that: The radius of the maximum circumscribed circle of the rotor core is R1, the number of sector portions is 2P, and among two adjacent protrusions, the end of the outer wall of one protrusion that is farthest from the rotation axis is the first endpoint, and the end of the outer wall of the other protrusion that is farthest from the rotation axis is the second endpoint. The distance between the first endpoint and the second endpoint is L, which satisfies: L≤0.4πR1 / P.

3. The rotor core according to claim 1, characterized in that: Along the circumference of the rotor core, the two opposite side walls of the fan-shaped portion protrude outward to form limiting portions. The limiting portions are used to abut against the end of the permanent magnet away from the rotation axis. The farthest distance between the outer side wall of the limiting portion and the rotation axis is R2. The radius of the largest circumscribed circle of the rotor core is R1, satisfying: 0.93≤R1 / R2≤0.

99.

4. The rotor core according to claim 1, characterized in that: The outer wall of the lamination unit is connected by a concave portion between two adjacent protrusions. The radius of the maximum circumscribed circle of the rotor core is R1, and the shortest distance from the outer wall of the concave portion to the rotation axis is R3, satisfying: 0.8≤R3 / R1<1.

5. The rotor core according to claim 1, characterized in that: The N protrusions of the lamination unit are asymmetrically arranged relative to the radial reference surface, and the rotation axis is located within the radial reference surface.

6. The rotor core according to claim 5, characterized in that: N is 2. The two protrusions are connected by a concave portion. The end of the concave portion closest to the rotation axis is the third endpoint. Along the circumference of the rotor core, the two opposite side walls of the fan-shaped portion protrude outward to form limiting portions. The farthest distance between one of the limiting portions and the third endpoint is d1, and the farthest distance between the other limiting portion and the third endpoint is d2, satisfying: 0.1≤d1 / d2<1.

7. The rotor core according to claim 1, characterized in that: On a projection plane perpendicular to the axis of rotation, the outer contour lines of two adjacent protrusions of the lamination unit are smoothly connected by an arc that is concave toward the axis of rotation; or, the outer contour lines of two adjacent protrusions of the lamination unit are connected by a straight line; or, the outer contour lines of two adjacent protrusions of the lamination unit intersect.

8. The rotor core according to claim 1, characterized in that: The outer tangent circles of the N protrusions of the lamination unit coincide.

9. An electric motor, characterized in that, include: Rotor core according to any one of claims 1 to 8; The stator assembly is wound around the outside of the rotor core.

10. The motor according to claim 9, characterized in that: The motor includes X phase lines, one end of which is connected to each other. The number N of the protrusions in the lamination unit satisfies: N = X - 1, where X is an integer greater than or equal to 3.

11. The motor according to claim 9, characterized in that: The stator assembly includes a stator core, which has a plurality of winding slots arranged circumferentially along the rotor core. The number of winding slots is Ns, and the number of poles of the rotor core is 2P, satisfying: Ns=2P±2.

12. The motor according to claim 11, characterized in that: The stator assembly includes a stator core, which has a plurality of winding slots arranged circumferentially along the rotor core. The number of winding slots is 12, and the number of poles of the rotor core is 10.

13. The motor according to claim 9, characterized in that: The stator assembly includes a stator core, which has a plurality of winding slots arranged at intervals along the circumference of the rotor core. The number of winding slots is Ns, and the number of poles of the rotor core is 2P, satisfying: Ns=2P±4.

14. A household appliance, characterized in that: Includes the motor as described in any one of claims 9 to 13.

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