Rotor core, permanent magnet motor and compressor

Abstract

The application relates to a rotor core, a permanent magnet motor and a compressor. The rotor core is arranged on the inner circumferential side of a stator of the permanent magnet motor. The rotor core comprises a plurality of rotor laminations arranged in the axial direction of the permanent magnet motor. Each rotor lamination comprises a plurality of permanent magnet grooves distributed at intervals in the circumferential direction of the rotor lamination. A first magnetic isolation hole, a second magnetic isolation hole and a rotor groove are symmetrically arranged with respect to the pole axis between each two adjacent permanent magnet grooves. The first magnetic isolation hole is arranged close to the end of the corresponding permanent magnet groove. The rotor groove is recessed radially inward from the outer circle of the rotor lamination. The minimum width of the rotor groove in the circumferential direction is greater than the distance between the symmetrically arranged first magnetic isolation holes. The air gap width at the pole axis of the rotor core is optimized, so that the magnetic flux density waveform of the air gap tends to be more sinusoidal, thereby reducing the noise caused by the harmonics and improving the operation stability of the permanent magnet motor.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to a rotor core, a permanent magnet motor and a compressor. Background Art

[0002] Due to its own structure, such as magnetic flux saturation and slotting, the waveform of the air gap flux density of the permanent magnet motor cannot be completely sinusoidal. The non-sinusoidal waveform contains various harmonics. These harmonics not only cause motor noise problems, but also increase motor losses and heat, resulting in high motor power consumption and low energy efficiency. Summary of the Invention

[0003] The purpose of this application is to provide a rotor core, a permanent magnet motor and a compressor, which can make the waveform of the air gap flux density of the permanent magnet motor close to sine, so as to reduce the noise caused by various harmonics and improve the operating stability of the permanent magnet motor.

[0004] In the first aspect, an embodiment of the present application provides a rotor core, which is arranged on the inner circumferential side of the stator of a permanent magnet motor. The rotor core includes a plurality of rotor punchings stacked along the axial direction of the permanent magnet motor. Each rotor punching includes a plurality of permanent magnet slots spaced apart along its own circumferential direction. A first magnetic isolation hole, a second magnetic isolation hole and a rotor slot are correspondingly arranged between each two adjacent permanent magnet slots, and the first magnetic isolation hole is arranged near the end of the corresponding permanent magnet slot. The rotor slot is formed by radially inwardly recessing the outer circle of the rotor punching, and the minimum width of the rotor slot along the circumferential direction is greater than the distance between the symmetrically distributed first magnetic isolation holes.

[0005] In a possible implementation, there are two first magnetic isolation holes, one second magnetic isolation hole, and one rotor slot. The two first magnetic isolation holes, one second magnetic isolation hole, and one rotor slot are symmetrically distributed relative to the polar axis.

[0006] In a possible implementation, the rotor slot includes two oblique side portions and two recessed portions symmetrically distributed relative to the polar axis, and a connecting portion connecting the two recessed portions, wherein the bottom of the recessed portion is lower than the connecting portion.

[0007] In one possible implementation, the central angle formed between the two intersection points of the two oblique sides on the outer circle of the rotor punching and the center of the circle is a, and the number of poles of the permanent magnet motor is 2P, then the central angle a satisfies the following conditions: 0.08×(360 / 2P)≤a≤0.36×(360 / 2P); and / or, the distance between the two oblique sides gradually decreases in the radial direction toward the center of the circle.

[0008] In one possible implementation, the maximum distance between the connection portion and the outer circle of the rotor punching is H1, the width of the connection portion is L1, and the inner diameter of the stator is D, wherein 0≤H1≤0.024×D, 0≤L1≤2×sin(0.5×a).

[0009] In a possible implementation, the minimum distance between the bottom of the recess and the connecting portion is L2, the bottom width of the recess is L3, and the inner diameter of the stator is D, wherein 0<L2≤0.07×D, 0≤L3≤0.5×L2.

[0010] In one possible implementation, the minimum distance between the second magnetic isolation hole and the connecting portion is L4, the minimum distance between the first magnetic isolation hole and the recess is L5, and the inner diameter of the stator is D, wherein 0.0004×D≤L4≤0.0009×D, 0.0004×D≤L5≤0.0009×D, and L4≠L5.

[0011] In one possible implementation, the maximum width of the second magnetic isolation hole is La, the radial length of the second magnetic isolation hole is L6, the minimum distance between the ends of two adjacent permanent magnet slots is Lb, and the inner diameter of the stator is D, then the following conditions are met: 0.015×D≤(Lb-La)≤0.03×D, L6≥3×L4.

[0012] In a possible implementation, the connecting portion is a straight line or an arc.

[0013] In a possible implementation, the first magnetic isolation hole is connected to an end of the permanent magnet slot.

[0014] In a second aspect, an embodiment of the present application provides a permanent magnet motor, comprising: a rotor, comprising the rotor core as described above and a plurality of permanent magnets arranged in a plurality of permanent magnet slots of the rotor core; and a stator, arranged on the outer peripheral side of the rotor.

[0015] In a third aspect, an embodiment of the present application provides a compressor comprising the permanent magnet motor as described above.

[0016] According to the rotor core, permanent magnet motor and compressor provided by the embodiment of the present application, the rotor core includes a plurality of rotor punchings stacked along the axial direction of the permanent magnet motor, each rotor punching includes a plurality of permanent magnet slots spaced apart along its own circumferential direction, and a first magnetic isolation hole, a second magnetic isolation hole and a rotor slot are correspondingly provided between each two adjacent permanent magnet slots, and the minimum width of the rotor slot in the direction perpendicular to the polar axis is greater than the distance between the symmetrically distributed first magnetic isolation holes; by optimizing the air gap width at the polar axis of the rotor core, the magnetic flux density waveform of the air gap is closer to sinusoidal, thereby reducing the noise caused by each harmonic. In addition, due to the reduction of the total harmonic content, the harmonic loss of the permanent magnet motor is reduced, the efficiency is improved, the motor temperature rise is lower, the demagnetization risk of the permanent magnet of the permanent magnet motor is reduced, and the operating stability of the permanent magnet motor is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. In addition, in the drawings, the same reference numerals are used for the same components, and the drawings are not drawn according to the actual scale.

[0018] Figure 1 A schematic diagram of the planar structure of a permanent magnet motor provided in an embodiment of the present application is shown;

[0019] Figure 2 A schematic structural diagram of a rotor punching of a rotor core provided by an embodiment of the present application is shown;

[0020] Figure 3 Show Figure 2 A partial enlarged view of the middle area A;

[0021] Figure 4 Show Figure 2 A dimensional relationship diagram of the rotor punching shown;

[0022] Figure 5 Show Figure 2 Another size relationship diagram of the rotor punching shown;

[0023] Figure 6 A schematic structural diagram of a rotor punching of another rotor core provided in an embodiment of the present application is shown;

[0024] Figure 7 Show Figure 6 A partial enlarged view of the middle area B;

[0025] Figure 8A harmonic comparison diagram of the permanent magnet motor according to the embodiment of the present application and the permanent magnet motor in the related art is shown.

[0026] Description of reference numerals:

[0027] 1. Rotor punching; 10. Permanent magnet slot; 11. First magnetic isolation hole; 12. Second magnetic isolation hole; 13. Rotor slot; 131. Bevel portion; 132. Concave portion; 133. Connecting portion; q, Pole axis;

[0028] 100, rotor; 200, stator. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] Due to its own structure, such as magnetic flux saturation and slotting, the waveform of the air gap flux density of the permanent magnet motor cannot be completely sinusoidal. The non-sinusoidal waveform contains various harmonics. These harmonics not only cause motor noise problems, but also increase motor losses and heat, resulting in high motor power consumption and low energy efficiency, affecting various performance aspects of the permanent magnet motor, such as operating stability.

[0031] To this end, the embodiments of the present application provide a rotor core, rotor sheets and permanent magnet motor, which can make the waveform of the air gap flux density of the permanent magnet motor close to sine, so as to reduce the noise caused by various harmonics and improve the operating stability of the permanent magnet motor.

[0032] Figure 1 A schematic diagram of the planar structure of a permanent magnet motor provided in an embodiment of the present application is shown; Figure 2 A schematic structural diagram of a rotor punching of a rotor core provided by an embodiment of the present application is shown. Figure 3 Show Figure 2 A partial enlarged view of area A in the middle.

[0033] An embodiment of the present application provides a permanent magnet motor, comprising a rotor 100 and a stator 200 disposed on the outer periphery of the rotor 100. The rotor 100 comprises a rotor core and a plurality of permanent magnets spaced apart along the circumference of the rotor core, wherein the plurality of permanent magnets are arranged in a staggered arrangement with N poles and S poles along the circumference. The permanent magnet motor may be a sinusoidal permanent magnet synchronous motor driven by a frequency converter, i.e., a sinusoidal motor that applies sinusoidal current excitation to produce a smooth torque output. The permanent magnet motor may also be a permanent magnet synchronous motor using vector control.

[0034] like Figures 1 to 3 As shown, the rotor core includes a plurality of rotor punchings 1 stacked along the axial direction of the permanent magnet motor. Each rotor punching 1 includes a plurality of permanent magnet slots 10 spaced apart along its own circumferential direction. A first magnetic isolation hole 11, a second magnetic isolation hole 12, and a rotor slot 13 are correspondingly provided between each two adjacent permanent magnet slots 10, and are symmetrically distributed relative to the polar axis q. The first magnetic isolation hole 11 is provided near the end of the corresponding permanent magnet slot 10. The rotor slot 13 is formed by radially inwardly recessing the outer circle of the rotor punching 1, and the minimum width L0 of the rotor slot 13 along the circumferential direction is greater than the distance between the symmetrically distributed first magnetic isolation holes 11. The permanent magnet slots 10 are used to place permanent magnets, so that the plurality of permanent magnets are arranged in the plurality of permanent magnet slots 10 in a staggered distribution of N poles and S poles along the circumferential direction.

[0035] In this embodiment, the first magnetic isolation hole 11 and the second magnetic isolation hole 12 are symmetrically distributed relative to the polar axis q, which can reduce the blocking effect of the magnetic isolation hole on the fundamental magnetic field, adjust the rotor magnetic circuit to block the low-order harmonic magnetic field from entering the rotor core, and basically have no effect on the fundamental magnetic field, thereby ensuring that the rotor iron loss and permanent magnet eddy current loss generated by the harmonic magnetic field are reduced while the output of the permanent magnet motor remains basically unchanged, thereby improving the motor efficiency; at the same time, the design of the first magnetic isolation hole 11 and the second magnetic isolation hole 12 can also reduce the heat generation and temperature rise of the permanent magnet caused by the rotor iron loss and the eddy current loss of the permanent magnet, thereby avoiding the possibility of demagnetization of the permanent magnet due to heat generation, and improving the operating reliability of the permanent magnet motor.

[0036] In addition, the radial outer walls of the permanent magnet slots 10, the first magnetic isolation holes 11, and the second magnetic isolation holes 12 are basically on the same circle, which can ensure that the magnetic circuits between the radial outer walls of the permanent magnet slots 10, the first magnetic isolation holes 11, and the second magnetic isolation holes 12 and the outer circle of the rotor core are consistent, and the structural strength close to the outer circle of the rotor core is consistent.

[0037] Furthermore, according to the Fourier expansion formula of the air gap magnetic flux density waveform, it can be known that the amplitude of each harmonic of the permanent magnet motor is directly proportional to the air gap magnetic field there. When the minimum width of the rotor slot 13 set on the rotor surface in the direction perpendicular to the polar axis q is greater than the distance between the symmetrically distributed first magnetic isolation holes 11, the air gap width here increases, resulting in a decrease in the amplitude of the air gap magnetic field strength. Since the amplitude of each harmonic is directly proportional to the amplitude of the air gap magnetic field strength, when the width of the rotor slot 13 is increased, it helps to reduce the amplitude of each harmonic, optimize the air gap magnetic flux density, make the waveform of the air gap magnetic flux density close to a sine wave, reduce the amplitude of each harmonic, and at the same time reduce the harmonic content of the air gap magnetic field of the permanent magnet motor, reduce the motor noise caused by harmonics, and improve the various performance aspects of the permanent magnet motor such as running stability.

[0038] According to the rotor core, rotor 100 and permanent magnet motor provided by the embodiment of the present application, the rotor core includes a plurality of rotor punchings 1 stacked along the axial direction of the permanent magnet motor, each rotor punching 1 includes a plurality of permanent magnet slots 10 spaced apart along its own circumferential direction, and a first magnetic isolation hole 11, a second magnetic isolation hole 12 and a rotor slot 13 symmetrically distributed relative to the polar axis q are correspondingly provided between each adjacent permanent magnet slot 10, and the minimum width of the rotor slot 13 in the direction perpendicular to the polar axis q is greater than the distance between the symmetrically distributed first magnetic isolation holes 11, and by optimizing the air gap width at the polar axis q of the rotor core, the magnetic flux density waveform of the air gap is closer to sinusoidal, thereby reducing the noise caused by each harmonic and improving the operating stability of the permanent magnet motor. In addition, due to the reduction of the total harmonic content, the harmonic loss of the permanent magnet motor is reduced, the efficiency is improved, the motor temperature rise is lower, the demagnetization risk of the permanent magnet of the permanent magnet motor is reduced, and the operating stability of the permanent magnet motor is improved.

[0039] In order to further optimize the design parameters of the rotor core, the simulation analysis results of the electromagnetic software can be combined to obtain the specific structure of the rotor core including multiple rotor punchings provided in the embodiment of the present application.

[0040] In one example, there are two first magnetic isolation holes 11, one second magnetic isolation hole 12, and one rotor slot 13. The two first magnetic isolation holes 11, one second magnetic isolation hole 12, and one rotor slot 13 are symmetrically distributed relative to the polar axis.

[0041] like Figures 1 to 3 As shown, each first magnetic isolation hole 11 is arranged near the end of the corresponding permanent magnet slot 10, and the minimum width L0 of the rotor slot 13 along the circumferential direction is greater than the distance between the two symmetrically distributed first magnetic isolation holes 11. Since the two first magnetic isolation holes 11 and the one second magnetic isolation hole 12 are symmetrically distributed relative to the polar axis q, the blocking effect of the magnetic isolation holes on the fundamental magnetic field can be reduced, and the rotor magnetic circuit can be adjusted to block the low-order harmonic magnetic field from entering the rotor core, while having little effect on the fundamental magnetic field. This can ensure that the rotor iron loss and permanent magnet eddy current loss generated by the harmonic magnetic field are reduced while the output of the permanent magnet motor remains basically unchanged, thereby improving the motor efficiency. At the same time, the design of the two first magnetic isolation holes 11 and the one second magnetic isolation hole 12 can also reduce the heating and temperature rise of the permanent magnet caused by the rotor iron loss and the permanent magnet eddy current loss, thereby avoiding the possibility of permanent magnet heating and demagnetization, and improving the operating reliability of the permanent magnet motor.

[0042] Figure 4 Show Figure 2 A dimensional relationship diagram of the rotor punching shown in FIG. Figure 5 Show Figure 2 Another dimensional relationship diagram of the rotor punching is shown.

[0043] like Figure 4 and Figure 5 As shown, in some embodiments, the rotor slot 13 includes two oblique sides 131 and two recesses 132 symmetrically distributed relative to the polar axis q, and a connecting portion 133 connecting the two recesses 132 , wherein the bottom of the recess 132 is lower than the connecting portion 133 .

[0044] According to simulation analysis, when the bottom of the concave portion 132 of the rotor slot 13 is lower than the distance of the connecting portion 133 , the harmonic content in the air gap waveform can be reduced, thereby improving the vibration noise of the permanent magnet motor.

[0045] Furthermore, the central angle a formed between the two intersection points of the two oblique sides 131 on the outer circle of the rotor punching 1 and the center of the circle is a, and the number of poles of the permanent magnet motor is 2P. The central angle a satisfies the following condition: 0.08×(360 / 2P)≤a≤0.36×(360 / 2P).

[0046] like Figure 1 As shown, the number of rotor poles of the permanent magnet motor is 2P = 8, and the number of rotor slots 13 is 8. Therefore, the central angle a formed between the two intersection points of the two oblique sides 131 of the rotor slot 13 on the outer circle of the rotor punching 1 and the center of the circle has a value range of 3.6 rad ≤ a ≤ 16.2 rad. In this embodiment, the value of P is actually half of the number of magnetic poles, that is, P = 4 in this embodiment. Of course, in other embodiments, P can also have other values, which will not be repeated here.

[0047] Furthermore, the distance between the two oblique side portions 131 gradually decreases along the radial direction toward the center of the circle.

[0048] like Figure 3 As shown, the minimum width L0 of the rotor slot 13 along the circumferential direction is greater than the distance between the two first magnetic isolation holes 11. Since the angle between the two oblique sides 131 is an acute angle, the distance between the two oblique sides 131 gradually decreases along the radial direction toward the center of the circle. Therefore, the minimum width L0 of the rotor slot 13 along the circumferential direction is the bottom width of the rotor slot 13.

[0049] Therefore, by setting the rotor slots 13 on the rotor punching 1 and reasonably setting the width size of the rotor slots 13, the multiple rotor slots 13 can be evenly distributed along the circumferential direction of the rotor core, which is conducive to making the waveform of the air gap flux density of the permanent magnet motor tend to be sinusoidal, thereby reducing the harmonic content in the air gap waveform, improving the vibration noise of the permanent magnet motor, and improving user comfort.

[0050] In some embodiments, as Figure 4As shown, the minimum distance between the connecting portion 133 and the outer circle of the rotor punching 1 is H1, the width of the connecting portion 133 is L1, and the inner diameter of the stator 200 is D, wherein 0≤H1≤0.024×D, 0≤L1≤2×sin(0.5×a).

[0051] Optionally, the connecting portion 133 is a straight line or an arc. The arc can be a radially outward convex arc or a radially inward concave arc. When the connecting portion 133 is a radially outward convex arc, the minimum distance H1 between the connecting portion 133 and the outer circumference of the rotor punching 1 is the distance between the vertex of the arc and the outer circumference of the rotor punching 1.

[0052] Therefore, by reasonably optimizing the dimensional relationship between the radial depth dimension and the width dimension of the connecting portion 133 of the rotor slot 13 and the inner diameter of the stator 200, the shape and size of the air gap between the rotor and the stator 200 can be limited, and the waveform of the magnetic flux density of the air gap can be made sinusoidal, thereby reducing the harmonic content in the air gap waveform, improving the vibration noise of the permanent magnet motor, and improving user comfort.

[0053] In some embodiments, the maximum distance between the bottom of the recess 132 and the connecting portion 133 is L2, the bottom width of the recess 132 is L3, and the inner diameter of the stator 200 is D, wherein 0<L2≤0.07×D, 0≤L3≤0.5×L2.

[0054] Optionally, the connecting portion 133 is a straight line or an arc that protrudes radially outward. Figure 4 As shown, when the connecting portion 133 is an arc convex radially outward, the maximum distance H2 between the connecting portion 133 and the bottom of the recess 132 is the distance between the apex of the arc and the bottom of the recess 132. Therefore, by rationally optimizing the dimensional relationship between the connecting portion 133 and the recess 132 of the rotor slot 13, the harmonics in the waveform of the magnetic flux density in the air gap can be reduced, making the waveform of the magnetic flux density in the air gap more sinusoidal, thereby improving the vibration noise of the permanent magnet motor and enhancing user comfort.

[0055] In some embodiments, the minimum distance between the second magnetic isolation hole 12 and the connecting portion 133 is L4, the minimum distance between the first magnetic isolation hole 11 and the recess 132 is L5, and the inner diameter of the stator 200 is D, wherein 0.0004×D≤L4≤0.0009×D, 0.0004×D≤L5≤0.0009×D, and L4≠L5.

[0056] As mentioned above, the concave portion 132 of the rotor slot 13 is arranged close to the first magnetic isolation hole 11, and the connecting portion 133 of the rotor slot 13 is arranged close to the second magnetic isolation hole 12. By limiting the minimum distance L4 between the second magnetic isolation hole 12 and the connecting portion 133 and the minimum distance L5 between the first magnetic isolation hole 11 and the concave portion 132 and the inner diameter of the stator 200, it is possible to ensure that the radial outer walls of the first magnetic isolation hole 11 and the second magnetic isolation hole 12 are basically on the same circle, thereby ensuring that the magnetic circuit between the radial outer walls of the first magnetic isolation hole 11 and the second magnetic isolation hole 12 and the outer circle of the rotor core is consistent, and making the structural strength close to the outer circle of the rotor core consistent. In addition, by reasonably setting the relative position and size of the first magnetic isolation hole 11, the magnetic circuit of the polar axis q can be improved, achieving the effect of blocking the low-order harmonic magnetic field from entering the rotor core.

[0057] In some embodiments, the maximum width of the second magnetic isolation hole 12 is La, the radial length of the second magnetic isolation hole 12 is L6, the minimum distance between the ends of two adjacent permanent magnet slots 10 is Lb, and the inner diameter of the stator 200 is D, where: 0.015×D≤(Lb-La)≤0.03×D, L6≥3×L4.

[0058] Alternatively, as Figure 5 As shown, the shape of the second magnetic isolation hole 12 can be rectangular, and its long side dimension L6 extends radially. The shape of the second magnetic isolation hole 12 can also be a barbell shape, that is, wide on both sides and narrow in the middle, and its long side dimension L6 extends radially. By reasonably setting the minimum distance Lb between the ends of two adjacent permanent magnet slots 10, the maximum width La of the second magnetic isolation hole 12 and the inner diameter of the stator 200, it can be ensured that the second magnetic isolation hole 12 can effectively block low-order harmonics without blocking the passage of the fundamental magnetic field. In addition, by reasonably setting the minimum distance L4 between the second magnetic isolation hole 12 and the connecting portion 133 and the radial length of the second magnetic isolation hole 12, the magnetic circuit and magnetic line distribution of the rotor can be optimized, the magnetic circuit of the permanent magnet motor along the polar axis q can be improved, the possibility of low-order harmonic magnetic fields entering the rotor core can be reduced, the radial electromagnetic force of the permanent magnet motor can be reduced, and the vibration noise of the permanent magnet motor can be improved, further improving the user's comfort.

[0059] In addition, the first magnetic isolation holes 11, the second magnetic isolation holes 12, and the rotor slots 13 can also reduce the weight of the rotor core, increase the power density of the permanent magnet motor, and ensure stable operation of the permanent magnet motor at high speeds. The arrangement of the permanent magnet slots 10 can increase the motor output. Due to the high proportion of reluctance torque, it can also avoid excessive power drop at high speeds and when weak magnetic saturation occurs, thereby achieving weak magnetic speed expansion.

[0060] Figure 6 A schematic structural diagram of a rotor punching of another rotor core provided in an embodiment of the present application is shown;

[0061] Figure 7 Show Figure 6 A partial enlarged view of area B in the middle.

[0062] like Figure 6 and Figure 7 As shown, the embodiment of the present application also provides a rotor core of a permanent magnet motor, which is Figures 1 to 5 The structure of the rotor core shown is similar, except that the first magnetic isolation holes 11 of the rotor punching 1 are connected to the ends of the permanent magnet slots 10 .

[0063] In order to facilitate processing and reduce manufacturing difficulty, when the size of the first magnetic isolation hole 11 of the rotor punching 1 is small, after electromagnetic software simulation analysis, the first magnetic isolation hole 11 of the rotor punching 1 can be connected to the end of the permanent magnet slot 10 without increasing the harmonic content in the air gap waveform, thereby reducing the manufacturing cost of the permanent magnet motor.

[0064] In addition, if Figure 7 As shown, the second magnetic isolation hole 12 can be shaped like a barbell, that is, wide at both sides and narrow in the middle, with its long side dimension L6 extending radially. The shape of the second magnetic isolation hole 12 can also be rectangular, depending on the simulation analysis results and the manufacturing process, which will not be repeated here.

[0065] Figure 8 A harmonic comparison diagram of the permanent magnet motor according to the embodiment of the present application and the permanent magnet motor in the related art is shown.

[0066] like Figure 8 As shown, the horizontal axis represents the harmonic order, the vertical axis represents the harmonic content, the light-colored rectangular box is the air gap magnetic flux density waveform of the permanent magnet motor in the related art, and the dark-colored rectangular box is the air gap magnetic flux density waveform of the permanent magnet motor in this application. It can be seen that the harmonic content in the related art has a certain advantage as a whole, but its 5th harmonic and 7th harmonic are relatively high, especially the 5th harmonic. The rotor core provided in the embodiment of the present application is optimized as described above for the rotor punching 1, and the harmonic content of the 5th harmonic is reduced from the original 6.8% to 2%, and the 7th harmonic is reduced from the original 1.6% to 1.1%. Both are reduced to a certain extent, especially the reduction in the harmonic content of the 5th harmonic is the most obvious.

[0067] Therefore, the embodiment of the present application optimizes the air gap width at the polar axis q of the rotor core so that the magnetic flux density waveform of the air gap is closer to sinusoidal, thereby reducing the noise caused by each harmonic and improving the operating stability of the permanent magnet motor. Furthermore, by optimizing the shape and size of the rotor slot 13, the first magnetic isolation hole 11 and the second magnetic isolation hole 12 at the polar axis q of the rotor core, it is possible to significantly block the low-order harmonic magnetic field, thereby significantly reducing the rotor iron loss and permanent magnet eddy current loss generated by the low-order harmonic magnetic field, making the overall structure of the permanent magnet motor the most efficient; at the same time, due to the reduction in total harmonic content, the harmonic loss of the permanent magnet motor is reduced, the efficiency is improved, the motor temperature rise is lower, the demagnetization risk of the permanent magnet of the permanent magnet motor is reduced, and the operating stability and reliability of the permanent magnet motor are improved.

[0068] In addition, an embodiment of the present application also provides a compressor, comprising any permanent magnet motor as described above.

[0069] It is understandable that the technical solutions of the permanent magnet motor and its rotor core and rotor punching 1 provided in the embodiments of the present application can be applied to electronic devices such as, but not limited to, compressors, air conditioners, wind turbines, etc., and will not be repeated here.

[0070] It should be noted that references in this specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not necessarily every embodiment includes that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not.

[0071] It should be readily understood that “on,” “above,” and “over” in this disclosure should be interpreted in the broadest manner, such that “on” means not only “directly on something,” but also includes “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above” or “over,” but also includes “above” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0072] Additionally, spatially relative terms, such as "below," "beneath," "beneath," "above," and the like, may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be in other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0073] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A rotor core, arranged on the inner circumference side of a stator of a permanent magnet motor, characterized in that: The rotor core includes a plurality of rotor punchings stacked along the axial direction of the permanent magnet motor, each of the rotor punchings includes a plurality of permanent magnet slots spaced apart along its own circumferential direction, and a first magnetic isolation hole, a second magnetic isolation hole and a rotor slot are correspondingly arranged between each two adjacent permanent magnet slots and are symmetrically distributed relative to the polar axis. The first magnetic isolation hole is arranged near the end of the corresponding permanent magnet slot, and the rotor slot is formed by radially inwardly recessing the outer circle of the rotor punching, and the minimum width of the rotor slot along the circumferential direction is greater than the distance between the symmetrically distributed first magnetic isolation holes.

2. The rotor core according to claim 1, characterized in that There are two first magnetic isolation holes, one second magnetic isolation hole, and one rotor slot. The two first magnetic isolation holes, one second magnetic isolation hole, and one rotor slot are symmetrically distributed relative to the polar axis.

3. The rotor core according to claim 1 or 2, characterized in that: The rotor slot includes two oblique side portions and two recessed portions symmetrically distributed relative to the polar axis, and a connecting portion connecting the two recessed portions, wherein the bottom of the recessed portion is lower than the connecting portion.

4. The rotor core according to claim 3, characterized in that: The central angle formed by the two intersection points of the two oblique sides on the outer circle of the rotor punching and the center of the circle is a, and the number of poles of the permanent magnet motor is 2P, then the central angle a satisfies the following conditions: 0.08×(360 / 2P)≤a≤0.36×(360 / 2P); and / or, the distance between the two oblique sides gradually decreases in the radial direction toward the center of the circle.

5. The rotor core according to claim 4, characterized in that: The maximum distance between the connecting portion and the outer circle of the rotor punching is H1, the width of the connecting portion is L1, and the inner diameter of the stator is D, wherein 0≤H1≤0.024×D, 0≤L1≤2×sin(0.5×a).

6. The rotor core according to claim 3, characterized in that The minimum distance between the bottom of the recess and the connecting portion is L2, the bottom width of the recess is L3, and the inner diameter of the stator is D, wherein 0<L2≤0.07×D, 0≤L3≤0.5×L2.

7. The rotor core according to claim 3, characterized in that The minimum distance between the second magnetic isolation hole and the connecting portion is L4, the minimum distance between the first magnetic isolation hole and the recess is L5, and the inner diameter of the stator is D, wherein 0.0004×D≤L4≤0.0009×D, 0.0004×D≤L5≤0.0009×D, and L4≠L5.

8. The rotor core according to claim 7, characterized in that: The maximum width of the second magnetic isolation hole is La, the radial length of the second magnetic isolation hole is L6, the minimum distance between the ends of two adjacent permanent magnet slots is Lb, and the inner diameter of the stator is D, wherein 0.015×D≤(Lb-La)≤0.03×D, and L6≥3×L4.

9. The rotor core according to claim 3, wherein: The connecting portion is a straight line or an arc.

10. The rotor core according to claim 1, wherein: The first magnetic isolation hole is communicated with an end of the permanent magnet slot.

11. A permanent magnet motor, characterized in that: include: A rotor comprising a rotor core according to any one of claims 1 to 10 and a plurality of permanent magnets disposed in a plurality of permanent magnet slots of the rotor core; and The stator is arranged on the outer circumference of the rotor.

12. A compressor, characterized in that: It comprises the permanent magnet motor as claimed in claim 11.

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