Rotor core, motor and household appliance

Abstract

The utility model 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 at the outer sides of the fan-shaped parts, so that the magnetic field distribution can be optimized, the magnetic flux distribution and the magnetic resistance change of the rotor can be changed, and the motor can be effectively protected. 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] The utility model relates to the technical field of motors, in particular to a rotor iron core motor and household electrical appliances. Background Art

[0002] The outer surface of the permanent magnet motor's rotor is arc-shaped, and the gap between it and the stator's winding slots is unevenly distributed. During the motor's rotation, this uneven gap causes the air gap permeability to change periodically, thereby generating harmonics. These harmonic components are superimposed on the fundamental wave, making the magnetic field in the motor complex and increasing the cogging torque. The cogging torque is a periodically changing torque generated by the interaction between the stator and the rotor in the motor. This torque fluctuation can cause vibration and noise in the motor, reducing the motor's performance. Utility Model Content

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

[0004] The utility model also provides a motor and a household appliance having the rotor core.

[0005] The motor according to the first embodiment of the utility model includes:

[0006] A plurality of fan-shaped portions are arranged around the rotation axis, and mounting grooves for mounting permanent magnets are formed between adjacent fan-shaped portions. The fan-shaped portions include a plurality of punching sheet units stacked along the rotation axis, and the outer side wall of at least one punching sheet unit is provided with N arc-shaped protrusions, satisfying: 2≤N≤14.

[0007] The rotor core according to the embodiment of the utility model has at least the following beneficial effects:

[0008] By arranging N arc-shaped convex parts on the outside of the sector, the magnetic field distribution can be optimized, the magnetic flux distribution and magnetic resistance change of the rotor can be changed, the non-uniformity of the magnetic field during the rotation process can be reduced, and the magnetic flux change of the motor during the rotation process can be smoother. It helps to reduce the sudden change of the magnetic field, thereby reducing the pulsation of the torque and the cogging torque. At the same time, the air gap magnetic density distribution of the motor can be changed to make the air gap magnetic density more uniform. It helps to reduce the non-uniformity of the radial electromagnetic force, reduce the vibration and noise of the motor, and make the back electromotive force waveform closer to the sine wave, reduce the total harmonic distortion of the back electromotive force, reduce the electromagnetic interference and loss of the motor, and improve the operating efficiency of the motor. The convex parts are provided with N and are in the range of 2 to 14, ensuring that the fundamental wave amplitude is in a suitable range, so as to suppress the harmonics while minimizing the impact on the fundamental wave magnetic density, thereby improving the performance of the motor.

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

[0010] According to some embodiments of the utility model, along the circumference of the rotor core, the two side walls of the fan-shaped portion respectively protrude outward to form a limiting portion, and the limiting portion is used to abut against one end of the permanent magnet away from the rotation axis. The maximum distance between the outer side wall of the limiting portion and the rotation axis is R2, and the radius of the maximum circumscribed circle of the rotor core is R1, satisfying: 0.93≤R1 / R2≤0.99.

[0011] According to some embodiments of the utility model, the outer side wall of the punching unit is connected by a transitional recess between two adjacent protrusions, the radius of the maximum circumscribed circle of the rotor core is R1, and the shortest distance between the outer side wall of the recess and 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 punching unit are asymmetrically arranged relative to a radial reference plane, and the rotation axis is located within the radial reference plane.

[0013] According to some embodiments of the utility model, N is 2, the two convex portions are transitionally 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 side walls of the fan-shaped portion that are opposite to each other protrude outward to form a limiting portion, wherein the maximum distance between one of the limiting portions and the third endpoint is d1, and the maximum 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 utility model, on a projection plane perpendicular to the rotation axis, the outer contour lines of two adjacent protrusions of the punching unit are connected by a smooth transition of a circular arc recessed toward the rotation axis; or, the outer contour lines of two adjacent protrusions of the punching unit are connected by a straight line; or, the outer contour lines of two adjacent protrusions of the punching unit intersect.

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

[0016] The motor according to the second embodiment of the utility model comprises a stator assembly and the rotor core described in the above embodiment, wherein the stator assembly is wound around the outer side of the rotor core.

[0017] The motor according to the embodiment of the utility model has at least the following beneficial effects:

[0018] By adopting the rotor core of the embodiment of the first aspect, the rotor core can optimize the magnetic field distribution, change the magnetic flux distribution and magnetic resistance change of the rotor, reduce the non-uniformity of the magnetic field during the rotation process, and make the magnetic flux change of the motor smoother during the rotation process by setting N arc-shaped convex parts on the outer side of the fan-shaped part. It helps to reduce the sudden change of the magnetic field, thereby reducing the pulsation of the torque and the cogging torque. At the same time, the air gap magnetic density distribution of the motor can be changed to make the air gap magnetic density more uniform. It helps to reduce the non-uniformity of the radial electromagnetic force, reduce the vibration and noise of the motor, and can make the back electromotive force waveform closer to the sine wave, reduce the total harmonic distortion of the back electromotive force, reduce the electromagnetic interference and loss of the motor, and improve the operating efficiency of the motor. The convex parts are provided with N and are in the range of 2 to 14, ensuring that the fundamental amplitude is within a suitable range, so as to suppress the harmonics while minimizing the impact on the fundamental magnetic density, thereby improving the performance of the motor.

[0019] According to some embodiments of the present invention, the motor includes X phase lines, one ends of the X phase lines are connected, and the number N of the protrusions of the punching unit satisfies: N=X-1, 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, which is provided with a plurality of winding slots arranged at intervals along the circumference of the rotor core. The number of the winding slots is Ns, and the number of poles of the rotor core is 2P, satisfying: Ns=2P±2.

[0021] According to some embodiments of the present invention, the stator assembly includes a stator core, the stator core is provided with a plurality of winding slots arranged at intervals along the circumference of the rotor core, the number of the winding slots is 12, and the number of poles of the rotor core is 10.

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

[0023] The household appliance according to the embodiment of the third aspect of the utility model includes the motor described in the above embodiment.

[0024] The household appliance according to the embodiment of the utility model has at least the following beneficial effects:

[0025] By adopting the motor of the second aspect embodiment, the rotor core of the motor can optimize the magnetic field distribution, change the magnetic flux distribution and magnetic resistance change of the rotor, reduce the non-uniformity of the magnetic field during the rotation process, and make the magnetic flux change of the motor smoother during the rotation process by setting N arc-shaped convex parts on the outside of the fan-shaped part. It helps to reduce the sudden change of the magnetic field, thereby reducing the pulsation and cogging torque of the torque. At the same time, the air gap magnetic density distribution of the motor can be changed to make the air gap magnetic density more uniform. It helps to reduce the non-uniformity of the radial electromagnetic force, reduce the vibration and noise of the motor, and can make the back electromotive force waveform closer to the sine wave, reduce the total harmonic distortion of the back electromotive force, reduce the electromagnetic interference and loss of the motor, and improve the operating efficiency of the motor. The convex parts are provided with N and are in the range of 2 to 14, ensuring that the fundamental amplitude is within a suitable range, so as to suppress the harmonics while minimizing the impact on the fundamental magnetic density, thereby improving the performance of the motor.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 1 It is a structural schematic diagram of a motor in one embodiment of the utility model;

[0029] Figure 2 It is a structural schematic diagram of a rotor assembly of an embodiment of the utility model;

[0030] Figure 3 It is a structural schematic diagram of a fan-shaped portion of an embodiment of the utility model;

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

[0032] Figure 5 It is a structural schematic diagram of a fan-shaped portion of another embodiment of the utility model;

[0033] Figure 6 It is a structural schematic diagram of a fan-shaped portion of another embodiment of the utility model;

[0034] Figure 7 It is a structural schematic diagram of a fan-shaped portion of another embodiment of the utility model;

[0035] Figure 8 It is a structural schematic diagram of a fan-shaped portion of another embodiment of the utility model;

[0036] Fig. 9A curve diagram comparing the reverse potential of a motor according to an embodiment of the utility model and a motor in the prior art;

[0037] Fig.10 It is a bar graph of the maximum value of the reverse potential FFT of the motor of one embodiment of the utility model and the motor in the prior art;

[0038] Fig.11 It is a curve diagram comparing the line back electromotive force of a motor in one embodiment of the utility model and a motor in the prior art;

[0039] Fig.12 It is a bar graph of the maximum values ​​of the line back electromotive force FFT of the motor in one embodiment of the utility model and the motor in the prior art;

[0040] Fig.13 It is a curve chart comparing the cogging torque of a motor according to an embodiment of the utility model and a motor in the prior art.

[0041] Reference numerals:

[0042] Rotor assembly 100; sector 110; punching unit 111; convex portion 112; concave portion 113; stopper 114; mounting groove 115; permanent magnet 120; rotor core 130;

[0043] Stator assembly 200 ; stator core 210 ; teeth 211 ; yoke 212 ; winding slots 213 . DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0045] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] In the description of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0047] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0048] There are fundamental waves and harmonic waves in the motor. The fundamental wave is also called the fundamental frequency, which refers to the basic frequency of the AC motor rotor, that is, the power supply frequency. Harmonics refer to electrical signals whose frequencies are integer multiples of the fundamental frequency. In AC motors, the main reasons for the generation of harmonics are the nonlinear characteristics of magnetic flux and the filtering effect of the capacitors and inductors inside the motor on the AC signal. When the frequencies of the capacitors and inductors are equal to the signal frequency, harmonics are generated. Each component is usually called a higher harmonic, such as a wave that is 3 times the fundamental frequency is called a third harmonic, and a wave that is 5 times the fundamental frequency is called a fifth harmonic.

[0049] In motors, it is generally necessary to suppress harmonics and retain the fundamental wave as much as possible. This is because the fundamental wave is the basic frequency on which the normal operation of the motor depends, while harmonics may have a negative impact on the performance and stability of the motor, such as causing unstable motor operation, generating additional heat and loss, and reducing the efficiency and service life of the motor. Harmonics may also cause vibration and noise, interfering with the normal operation of the motor and the working environment. Therefore, in order to reduce these negative effects, measures are usually taken to suppress the generation and propagation of harmonics.

[0050] For this purpose, refer to Figure 1 and Figure 2 As shown, a rotor core 130 of an embodiment of the present invention can be used in a motor, such as a permanent magnet motor. The rotor core 130 of the embodiment of the present invention includes a plurality of sector portions 110, which are arranged around the rotation axis, and a mounting groove 115 for mounting the permanent magnet 120 is formed between two adjacent sector portions 110. The sector portion 110 includes a plurality of punching sheet units 111, which are stacked along the axial direction of the rotation axis. Figure 3 and Figure 4 As shown, the outer side wall of at least one punching unit 111 is provided with N arc-shaped protrusions 112, which satisfy: 2≤N≤14, for example, N can be 3, 4, 5, 6, etc., wherein Figure 3 The punching unit 111 is provided with two convex parts 112. Figure 5 The punching unit 111 is provided with three convex parts 112 .

[0051] By arranging N arc-shaped convex portions 112 on the outside of the sector portion 110, the magnetic field distribution can be optimized, the magnetic flux distribution and magnetic resistance change of the rotor can be changed, and the non-uniformity of the magnetic field during the rotation process can be reduced, so that the magnetic flux change of the motor during the rotation process is smoother. It helps to reduce the sudden change of the magnetic field, thereby reducing the pulsation of the torque and the cogging torque. At the same time, the air gap magnetic density distribution of the motor can be changed to make the air gap magnetic density more uniform. It helps to reduce the non-uniformity of the radial electromagnetic force, reduce the vibration and noise of the motor, and make the back electromotive force waveform closer to the sine wave, reduce the total harmonic distortion of the back electromotive force, reduce the electromagnetic interference and loss of the motor, and improve the operating efficiency of the motor.

[0052] When N is less than 2, that is, when N is 1, in order to suppress harmonics, a larger fundamental amplitude needs to be sacrificed, and the larger the fundamental amplitude, the higher the operating efficiency of the motor. Therefore, when N is less than 2, the operating efficiency of the motor will be reduced. When N is greater than 14, only high-order harmonics can be suppressed, and the suppression effect on low-order harmonics is limited. For example, the suppression effect on the 3rd, 5th, 7th, and 9th harmonics is very small. Even if the fundamental wave of the motor is large at this time, the presence of harmonics will cause the vibration of the motor to intensify and generate greater noise. Therefore, the number of protrusions 112 is set within the range of 2 to 14, and different numbers of protrusions 112 are set according to different types of motors to suppress harmonics while minimizing the impact on the fundamental magnetic flux density, thereby improving the performance of the motor.

[0053] Reference Figure 3 and Figure 4 As shown, Figure 3The arc-shaped dotted line in the figure is the maximum circumscribed circle S1 of the rotor core 130. In an embodiment of the present invention, the radius of the maximum circumscribed circle S1 of the rotor core 130 is R1, the number of the sector portions 110 is 2P, and the number of the sector portions 110 is the same as the number of the permanent magnets 120. Among the two adjacent protrusions 112, the end of the outer wall of one protrusion 112 farthest from the axis of rotation is the first endpoint, and the end of the outer wall of the other protrusion 112 farthest from the axis of rotation 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. Among them, 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 convex parts 112 is too large to suppress harmonics, and the space on the punching unit 111 is limited, so it is difficult to infinitely expand the distance between adjacent convex parts 112. Therefore, a reasonable design of the size of L can suppress harmonics while ensuring that the distance between the convex parts 112 is reasonably designed and reliable.

[0054] Reference Figure 3 As shown, in the embodiment of the utility model, along the circumference of the rotor core 130, the two side walls of the sector 110 that are opposite to each other protrude outward to form a limiting portion 114, and the limiting portion 114 is used to abut against one end of the permanent magnet 120 away from the rotation axis. The outer wall of the limiting portion 114 is at a maximum distance from the rotation axis R2, and the radius of the maximum circumscribed circle S1 of the rotor core 130 is R1, which satisfies: 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 the unnecessary harmonics can be better suppressed, the fundamental wave loss is large, and the performance loss of the motor is large. When R1 / R2 is greater than 0.99, it is difficult to suppress the unnecessary harmonics, resulting in increased torque pulsation and cogging torque, and then increased noise. Therefore, by reasonably designing the size of R1 / R2, it is possible to suppress unnecessary harmonics while ensuring that the amplitude of the fundamental wave is at an appropriate size to reduce the performance loss of the motor.

[0055] Reference Figure 4As shown, in the embodiment of the utility model, the outer wall of the punching unit 111 is transitionally connected between two adjacent convex parts 112 through the concave part 113, and the shortest distance between the outer wall of the concave part 113 and the rotation axis is R3, which satisfies: 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 depth of the concave part 113 in the radial direction 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 of suppressing harmonics. Therefore, by reasonably designing the size of R3 / R1, it can be ensured that the equivalent air gap will not increase significantly, so as to increase the fundamental magnetic flux density, and at the same time, it can suppress harmonics to reduce the cogging torque, thereby reducing the noise during the operation of the motor.

[0056] Reference Figure 4 As shown, in the embodiment of the utility model, on the projection plane perpendicular to the rotation axis, the outer contours of two adjacent convex parts 112 of the punching unit 111 are smoothly connected by an arc line S3 that is concave 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. Or, refer to Figure 6 As shown, the outer contours of two adjacent convex portions 112 of the punching unit 111 are connected by a straight line S4, and the straight line S4 connection has the advantages of simple structure and convenient processing, which can reduce the manufacturing cost. Figure 7 As shown, the outer contour lines of two adjacent convex portions 112 of the punching unit 111 intersect, which can make the structure of the punching unit 111 more compact and reduce space occupation. The appropriate solution is selected according to the actual situation.

[0057] Reference Figure 8 As shown, Figure 8The dotted line in is the symmetry line S2. In the embodiment of the utility model, the N convex parts 112 of the punching unit 111 are asymmetrically arranged relative to the radial reference plane, and the rotation axis is located in the radial reference plane, that is, the N convex parts 112 of the punching unit 111 are asymmetrically arranged relative to the symmetry line S2. For example, the rotor core 130 rotates in the counterclockwise direction during operation, and there are two convex parts 112, and a concave part 113 is formed between the two convex parts 112. The end of the concave part 113 closest to the rotation axis is the third endpoint, and the farthest distance between the left limit part 114 and the third endpoint is d1, and the farthest distance between the right limit part 114 and the third endpoint is d2, which satisfies: 0.1≤d1 / d2<1, for example, d1 / d2 can be 0.3, 0.4, 0.5, 0.6, 0.8. Generally speaking, in the no-load state of the motor, the harmonics of the motor air gap flux density are symmetrical. However, since the armature reaction is unilaterally asymmetric, under load conditions, the air gap magnetic flux density of the motor will become asymmetric. Therefore, by providing an asymmetric convex portion 112 on the outer surface of the punching unit 111, the asymmetry caused by the armature reaction under load conditions can be improved, the asymmetry degree can be reduced, and the stability of the motor operation can be improved. In another embodiment, the N convex portions 112 of the punching unit 111 can also be symmetrical relative to the radial reference plane, and a suitable solution can be selected according to the actual situation.

[0058] Reference Figure 4 As shown, in the embodiment of the utility model, the circumscribed circles of the N protrusions 112 of the punching unit 111 coincide, that is, the maximum distances between the N protrusions 112 and the axis of rotation are the same. Therefore, the overall weight of the rotor core 130 can be balanced, and the instability caused by uneven weight distribution can be avoided, and the smoothness of the rotor core 130 during rotation can be improved. The setting of the protrusion 112 can change the electromagnetic field distribution on the rotor surface, thereby optimizing the magnetic flux path and electromagnetic conversion efficiency of the motor. It helps to reduce energy loss and improve the efficiency of the motor.

[0059] The motor of one embodiment of the utility model comprises a rotor assembly 100 and a stator assembly 200. The rotor assembly 100 comprises a permanent magnet 120 and a rotor core 130 of the above embodiment. The permanent magnet 120 is installed in the installation groove 115, and the stator assembly 200 is wound on the outer side of the rotor core 130. The stator assembly 200 comprises a stator core 210, which is annular and comprises a yoke 212 and a plurality of teeth 211. The plurality of teeth 211 are arranged at intervals on the inner wall of the yoke 212. A winding groove 213 is formed between two adjacent teeth 211, and the winding can be wound on the teeth 211 through the winding groove 213. The winding can generate a magnetic field after being energized, and an alternating magnetic field is generated by changing the direction of the current, and interacts with the magnetic field of the permanent magnet 120 to drive the rotor assembly 100 to rotate.

[0060] The motor of the utility model embodiment adopts the stator core 210 of the above embodiment. The stator core 210 can optimize the magnetic field distribution, change the magnetic flux distribution and magnetic resistance change of the rotor, reduce the non-uniformity of the magnetic field during the rotation process, and make the magnetic flux change of the motor smoother during the rotation process by setting N arc-shaped protrusions 112 on the outside of the sector 110. It helps to reduce the sudden change of the magnetic field, thereby reducing the pulsation of the torque and the cogging torque. At the same time, the air gap magnetic density distribution of the motor can be changed to make the air gap magnetic density more uniform. It helps to reduce the non-uniformity of the radial electromagnetic force, reduce the vibration and noise of the motor, and make the back electromotive force waveform closer to the sine wave, reduce the total harmonic distortion of the back electromotive force, reduce the electromagnetic interference and loss of the motor, and improve the operating efficiency of the motor. The protrusions 112 are provided with N and are in the range of 2 to 14, ensuring that the fundamental wave amplitude is in a suitable range, so as to suppress the harmonics while minimizing the impact on the fundamental wave magnetic density, thereby improving the performance of the motor.

[0061] In the related technology, arc cutting can be adopted, such as significantly cutting the arc on 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 cause the equivalent air gap of the motor to increase significantly, greatly reducing the performance of the motor.

[0062] In an embodiment of the utility model, the motor includes X phase lines, one end of the X phase lines is connected, and the number N of the protrusions 112 of the punching unit 111 satisfies: N=X-1, and X is an integer greater than or equal to 3. For example, when X is 3 and N is 2, that is, the motor is a three-phase motor, and one punching unit 111 is provided with two protrusions 112. During the operation of the motor, the rotor core 130 of this embodiment cannot effectively suppress the harmonics of the third order and multiples of 3, but can suppress harmonics of other orders. That is, the harmonics of the third order and multiples of 3 retain a part of them, and the existence of harmonics can increase the amplitude of the fundamental wave. However, the harmonics of the third order and multiples of 3 still need to be suppressed in the end. By applying the rotor core 130 of this embodiment to the three-phase motor, and the three-phase motor adopts a star connection method, the three-phase motor with a star connection method does not have the harmonics of the third order and multiples of 3.

[0063] For example, refer to Fig. 9 and Fig.10 As shown, Fig. 9 The horizontal axis represents the electrical period, and the vertical axis represents the opposite potential. Fig. 9 The curves in the figure reflect the waveforms of opposite potentials, wherein the curve with square symbols is the waveform of the solution in the related art, and the curve with diamond symbols is the waveform when N is 2 in the embodiment of the utility model. Fig.10The horizontal axis represents the order of harmonics, for example, the 1st harmonic is the fundamental wave, and 3 represents the 3rd harmonic. The vertical axis represents the maximum value of the opposite potential FFT. The lighter color is the solution in the related art, and the darker color is the solution when N is 2 in the embodiment of the utility model.

[0064] It should be noted that the reverse potential measures the potential from a certain phase to the center point of the connection. For example, a three-phase motor includes phase A, phase B and phase C. The ends of phase A, phase B and phase C are connected together to form a common point. The reverse potential measures the potential from any phase of phase A, phase B and phase C to the common point. Fig.10 The third harmonic and its multiples can still be seen, while other harmonics are basically suppressed.

[0065] And refer to Fig.11 and Fig.12 As shown, Fig.11 The horizontal axis represents the electrical period, and the vertical axis represents the line back electromotive force. Fig.11 The curves in the figure reflect the waveforms of the line back electromotive force, wherein the curve with square symbols is the waveform of the solution in the related art, and the curve with triangle symbols is the waveform when N is 2 in the embodiment of the utility model. Fig.12 The horizontal axis represents the order of harmonics, for example, the 1st harmonic is the fundamental wave, and 3 represents the 3rd harmonic. The vertical axis represents the maximum value of the line back electromotive force FFT. The lighter colors are the solutions in the related art, and the darker colors are the solutions when N is 2 in the embodiment of the utility model.

[0066] It should be noted that the line back EMF measures the potential between two phases. For example, a three-phase motor includes phase A, phase B and phase C. The ends of phase A, phase B and phase C are connected together to form a common point. The line back EMF measures the potential between any two phases of phase A, phase B and phase C. That is, in the star connection of a three-phase motor, Fig.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 electromotive force of the embodiment of the utility model is greater than the fundamental amplitude in the related art, which is increased by about 5.8%.

[0067] At the same time, refer to Fig.13 As shown, Fig.13 The horizontal axis represents the electrical period, and the vertical axis represents the cogging torque. Fig.13The curve with a square pattern is a solution in the related art, and the curve with a diamond symbol is a solution of the embodiment of the utility model. It can be seen from the figure that by adopting the solution of the embodiment, the peak value of the cogging torque is reduced from 4.9mNm to 0.9mNm, a decrease of 81.6%. Therefore, by adopting the solution of the embodiment of the utility model, the fundamental amplitude can be increased, and the torque ripple, cogging torque, radial electromagnetic force, and back electromotive force THD can be reduced, and the equivalent air gap of the motor will not increase significantly, reducing the impact on the motor performance.

[0068] When N is 3, the rotor core 130 of this embodiment cannot effectively suppress the 4th harmonic and its multiples, but can suppress harmonics of other orders. The rotor core 130 of this embodiment can be applied to a four-phase motor. One end of the four phase lines of the four-phase motor are connected, and the connection method is similar to the star connection method. The motor of this embodiment does not have the 4th harmonic and its multiples. By adopting the above scheme, it is also possible to increase the fundamental wave amplitude while reducing the impact of harmonics on motor performance. Other numbers of protrusions 112 and applicable motors are similar, and will not be repeated here.

[0069] In an embodiment of the utility model, the stator assembly 200 includes a stator core 210, and the stator core 210 is provided with a plurality of winding slots 213 arranged at intervals along the circumference of the rotor core 130, the number of the winding slots 213 is NS, and the number of poles of the rotor core 130 is 2P, which satisfies: NS = 2P ± 2, or satisfies: NS = 2P ± 4. For example, the number of the winding slots 213 is 12, and the number of poles of the rotor core 130 is 10; or the number of the 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, so that the motor is more stable during operation, torque pulsation and vibration are reduced, 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] A household appliance of an embodiment of the utility model includes the motor of the above embodiment, and the household appliance can be a fan, an air conditioner, a refrigerator, a drum washing machine, etc. The household appliance of the utility model embodiment adopts the motor of the above embodiment, and the stator core 210 of the motor can optimize the magnetic field distribution, change the magnetic flux distribution and magnetic resistance change of the rotor by setting N arc-shaped protrusions 112 on the outside of the fan-shaped portion 110, reduce the non-uniformity of the magnetic field during the rotation process, and make the magnetic flux change of the motor smoother during the rotation process. It helps to reduce the sudden change of the magnetic field, thereby reducing the pulsation and cogging torque of the torque. At the same time, the air gap magnetic density distribution of the motor can be changed to make the air gap magnetic density more uniform. It helps to reduce the non-uniformity of the radial electromagnetic force, reduce the vibration and noise of the motor, and make the back electromotive force waveform closer to the sine wave, reduce the total harmonic distortion of the back electromotive force, reduce the electromagnetic interference and loss of the motor, and improve the operating efficiency of the motor. The number of convex portions 112 is N and is in the range of 2 to 14, ensuring that the fundamental wave amplitude is in a suitable range, so as to suppress harmonics while minimizing the impact on the fundamental wave magnetic flux density, thereby improving the performance of the motor.

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

[0072] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. Rotor core, It is characterized in that include: A plurality of fan-shaped portions are arranged around the rotation axis, and mounting grooves for mounting permanent magnets are formed between adjacent fan-shaped portions. The fan-shaped portions include a plurality of punching sheet units stacked along the rotation axis, and the outer side wall of at least one punching sheet unit is provided with N arc-shaped protrusions, satisfying: 2≤N≤14.

2. The rotor core according to claim 1, Features: The radius of the maximum circumscribed circle of the rotor core is R 1 , the number of the fan-shaped portions is 2P, and among the two adjacent convex portions, the end of the outer wall of one of the convex portions farthest from the rotation axis is the first endpoint, and the end of the outer wall of the other convex portion farthest from the rotation axis is the second endpoint, and the distance between the first endpoint and the second endpoint is L, satisfying: L≤0.4πR 1 / P.

3. The rotor core according to claim 1, Features: Along the circumference of the rotor core, the two side walls of the sector portion that are opposite to each other protrude outward to form a limiting portion, and the limiting portion is used to abut against one end of the permanent magnet away from the rotation axis. The maximum distance between the outer side wall of the limiting portion and the rotation axis is R 2 , the radius of the maximum circumscribed circle of the rotor core is R 1 , satisfying: 0.93≤R 1 / R 2 ≤0.

99.

4. The rotor core according to claim 1, Features: The outer side wall of the punching unit is connected between two adjacent convex parts through a concave part, and the radius of the maximum circumscribed circle of the rotor core is R 1 The shortest distance between the outer wall of the recess and the rotation axis is R 3 , satisfying: 0.8≤R 3 / R 1 <1.

5. The rotor core according to claim 1, Features: The N protrusions of the punching unit are asymmetrically arranged relative to a radial reference plane, and the rotation axis is located in the radial reference plane.

6. The rotor core according to claim 5, Features: N is 2, the two convex parts are connected by a concave part, the end of the concave part closest to the rotation axis is the third end point, and along the circumference of the rotor core, the two side walls of the fan-shaped part that are separated from each other protrude outward to form a limited position, and the farthest distance between one of the limited positions and the third end point is d 1 The maximum distance between the other limiting portion and the third endpoint is d 2 , satisfying: 0.1≤d 1 / d 2 <1.

7. The rotor core according to claim 1, Features: On the projection plane perpendicular to the rotation axis, the outer contour lines of two adjacent protrusions of the punching unit are connected by a smooth transition of a circular arc recessed toward the rotation axis; or, the outer contour lines of two adjacent protrusions of the punching unit are connected by a straight line; or, the outer contour lines of two adjacent protrusions of the punching unit intersect.

8. The rotor core according to claim 1, Features: The circumscribed circles of the N protrusions of the punching unit overlap.

9. Motor, It is characterized in that include: The rotor core according to any one of claims 1 to 8; The stator assembly is wound around the outer side of the rotor core.

10. The electric machine according to claim 9, Features: The motor includes X phase lines, one ends of the X phase lines are connected, and the number N of the protrusions of the punching unit satisfies: N=X-1, where X is an integer greater than or equal to 3.

11. The electric machine according to claim 9, Features: The stator assembly includes a stator core, which is provided with a plurality of winding slots spaced apart along the circumference of the rotor core. The number of the winding slots is Ns, and the number of poles of the rotor core is 2P, satisfying: Ns=2P±2.

12. The electric machine according to claim 11, Features: The stator assembly includes a stator core, the stator core is provided with a plurality of winding slots arranged at intervals along the circumferential direction of the rotor core, the number of the winding slots is 12, and the number of poles of the rotor core is 10.

13. The electric machine according to claim 9, Features: The stator assembly includes a stator core, and the stator core is provided with a plurality of winding slots arranged at intervals along the circumferential direction of the rotor core. The number of the winding slots is Ns, and the number of poles of the rotor core is 2P, satisfying: Ns=2P±4.

14. Household appliances, Features: Comprising the electric machine as claimed in any one of claims 9 to 13.

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