Rotor core and asynchronous motor

Abstract

The application discloses a rotor core and an asynchronous motor. The rotor core comprises a plurality of rotor slots. The rotor slots are uniformly arranged along the circumference of the rotor core, and a recess is formed at one end of each rotor slot away from the axis of the rotor core. The recesses on the rotor slots are of the same shape. The recesses are not communicated with the outer edge of the rotor core. In the application, the rotor slots adopt a non-conventional slot type. By setting the one end of the rotor slot away from the axis of the rotor core as a recess structure, the top end part of the rotor slot is forked to form two protruding structures. This slot type can not only ensure that the motor has high motor efficiency and power performance, but also greatly reduce the order electromagnetic noise of the motor, so that the balance between power performance and NVH performance is achieved. The application avoids increasing the outer edge of the rotor core or adding acoustic wrapping to increase the size of the asynchronous motor, and improves the application range.

Description

Technical Field

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

[0002] The new energy vehicle industry is booming. Drive motors in new energy vehicles are currently mainly divided into permanent magnet motors and asynchronous induction motors. However, due to the rising price of rare-earth permanent magnet materials used in permanent magnet synchronous motors, the price advantage of asynchronous induction motors is becoming increasingly significant. However, asynchronous induction motors have multiple noise levels, making NVH (noise, vibration, and harshness) issues difficult to control. To address the NVH problems generated by the drive system, two technical approaches are typically adopted: one is to increase the outer edge of the rotor core, and the other is to prioritize power performance while increasing acoustic enclosure. However, both of these approaches increase the overall size and are not suitable for situations with limited space.

[0003] Therefore, it is necessary to provide a new rotor core and asynchronous motor to solve the above-mentioned technical problems. Summary of the Invention

[0004] The main objective of this invention is to provide a rotor core and an asynchronous motor, which aims to solve the problems of existing asynchronous motors having an increased overall size and limited applicability due to the need to control NVH (noise, vibration, and harshness) issues.

[0005] To achieve the above objectives, the present invention proposes a rotor core comprising a plurality of rotor slots; each rotor slot is uniformly arranged along the circumference of the rotor core, and a groove is formed at one end of each rotor slot away from the axis of the rotor core; the grooves on each rotor slot have the same shape; the grooves are not connected to the outer edge of the rotor core.

[0006] Optionally, the groove is a triangular groove or an arc-shaped groove.

[0007] Optionally, the groove has an axisymmetric structure, and the center line of the groove passes through the axis of the rotor core.

[0008] Optionally, the grooves of each rotor slot have a non-axisymmetric structure.

[0009] Optionally, the two ends of the groove are respectively connected to the two sides of the rotor slot by a circular arc transition.

[0010] Optionally, the two ends of the groove are connected to the two sides of the rotor slot, forming an acute angle.

[0011] Optionally, the side of the rotor slot includes a first side and a second side, one end of the first side is connected to one end of the groove, the other end of the first side is connected to the second side, and the first side and the second side form an obtuse angle.

[0012] Optionally, the distance between the endpoints of two adjacent grooves in different grooves is L1, and the distance between the endpoints of two grooves in the same groove is L2, where 0.5 ≤ L2 / L1 ≤ 1.5.

[0013] Optionally, the distance from the apex of the groove to the outer diameter of the rotor core is L3, and the distance from the end point of the groove to the outer diameter of the rotor core is L4, where 2≤L4 / L3≤5.

[0014] In addition, the asynchronous motor includes a stator core, rotor bars, and a rotor core as described above, wherein the stator core and the rotor core are coaxially arranged; the rotor bars are disposed within the rotor slots of the rotor core.

[0015] The rotor guide bars are formed by casting within the rotor slots; or, the rotor guide bars are prefabricated magnetic strips, and the rotor guide bars are inserted into the rotor slots one by one.

[0016] In this invention, the rotor slots extend radially outward along the rotor core. By designing the end of the rotor slot furthest from the rotor core axis as a groove structure, the top of the rotor slot forks into two protruding structures, effectively doubling the number of rotor slots. This increases the number of rotor slots, reduces the generation of low-order electromagnetic forces, and thus lowers the vibration and noise of the asynchronous motor under electromagnetic excitation. This application eliminates the need to increase the outer edge of the rotor core or add acoustic enclosure, thereby effectively controlling the size of the drive motor, solving the NVH problem, and expanding its applicability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the rotor core structure in an embodiment of the present invention;

[0019] Figure 2 This is a partially enlarged schematic diagram of the rotor core in one embodiment of the present invention;

[0020] Figure 3 This is a partially enlarged schematic diagram of the rotor core in another embodiment of the present invention;

[0021] Figure 4 This is a partially enlarged schematic diagram of the rotor core in another embodiment of the present invention;

[0022] Figure 5 This is a partially enlarged schematic diagram of the rotor core in another embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram showing the relationship between the rotor core and the stator structure in an embodiment of the present invention;

[0024] Figure 7 This is an enlarged schematic diagram of the rotor core and stator structure in an embodiment of the present invention.

[0025]

[0026] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0029] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0032] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the rotor core 1 includes a plurality of rotor slots 11; each rotor slot 11 is uniformly arranged along the circumference of the rotor core 1, and a groove 111 is formed at one end of each rotor slot 11 away from the axis of the rotor core 1; the grooves 111 on each rotor slot 11 have the same shape; the grooves 111 are not connected to the outer edge of the rotor core 1.

[0033] In the above embodiment, the end of the rotor slot 11 closest to the outer edge of the rotor core is the top of the rotor slot. The two ends of the rotor slot 11 extend radially outward along the rotor core 1 to form two interconnected protrusions 112. A groove 111 is formed between the two protrusions 112. That is, the two protrusions 112 set the top portion of the rotor slot 11 as a groove 111, causing the top portion to form two protrusions 112. For rotors using conventional slot types, when saturation exists, the magnetic reluctance is large at the narrowest point of the magnetic circuit at the top of the rotor slot, forming magnetic permeability harmonics with a spatial order equal to the number of rotor slots along the circumference. However, with the rotor using the scheme of this application, each... The rotor slot has two protruding structures 112 at its top. Taking the end of the protruding structure closest to the outer edge of the rotor core as the top of the protruding structure, the distance between the top of the two protruding structures 112 and the outer edge of the rotor core is the shortest. When saturation exists, a large magnetic reluctance will be generated at the top of the two protruding structures 112, thus forming a spatial order equal to the number of protruding structures on the rotor. That is, in this application, there are two locations in one rotor slot 11 that generate large magnetic reluctance, thereby obtaining magnetic permeability harmonics twice the number of rotor slots. Without considering the influence of non-ideal factors such as saturation and stator-rotor eccentricity, the spatial order of the radial electromagnetic force acting on the surface of the stator teeth of the asynchronous motor is: ,in: This represents the number of pole pairs of the motor. The number of stator slots The number of rotor slots, , Let be any natural number. To reduce the vibration noise of an asynchronous motor under electromagnetic excitation, it is necessary to minimize the generation of low-order radial electromagnetic forces in space, i.e., increase the value of the spatial order. This application achieves the effect of effectively increasing the number of rotor slots 11 by setting a groove at the top of the rotor slot 11, thereby reducing the generation of low-order electromagnetic forces in space and thus reducing the vibration noise of the asynchronous motor under electromagnetic excitation. That is, in this embodiment, neither an increase in air gap nor the addition of acoustic enclosure is required, thus effectively controlling the volume of the asynchronous motor, solving the NVH problem, and improving its applicability.

[0034] For small radial flux motors, the main excitation source causing electromagnetic vibration noise is the low-order radial electromagnetic force in space. According to Maxwell's equations, the radial electromagnetic force density can be calculated from the radial flux density.

[0035]

[0036] Among them, radial magnetic flux density It can be represented as the fundamental wave. Stator harmonics Rotor harmonics The sum of the rotor magnetic flux density. This can be represented as the sum of a series of harmonics:

[0037]

[0038] In typical asynchronous motors, the noise level is most pronounced by the rotor's first-order harmonic. Relatedly, the solution proposed in the above embodiments can convert some of the rotor's first-order tooth harmonics into second-order or other higher-order tooth harmonics, thereby reducing the vibration noise generated by the rotor's first-order tooth harmonics.

[0039] Furthermore, in this application, the groove 111 is not connected to the outer edge of the rotor core 1, meaning that the open groove form is not used in this application. When the rotor groove 11 is an open groove, a large magnetic resistance will be generated at the entire opening 1, thereby weakening the NVH optimization effect.

[0040] In one embodiment, please refer to [reference needed]. Figure 2 and Figure 3The groove 111 can be a triangular groove, forming a sharp corner structure at the connection between the two protruding structures 112, thereby achieving a more defined magnetic reluctance change and better NVH optimization. The groove 111 can also be an arc-shaped groove, which allows the distance between the edge of the rotor slot 11 and the outer edge of the rotor core to change smoothly, thus ensuring the structural strength of the rotor core 1 and avoiding the formation of sharp edges, i.e., avoiding defects at the apex of the groove (the apex of the groove 111 is the point closest to the rotor core axis), ensuring NVH optimization. In this application, it is sufficient to divide the top of the rotor slot 11 into two protruding structures 112, thereby achieving an effect equivalent to increasing the number of rotor slots 11. The shape of the groove 111 is not limited in this application.

[0041] In actual production and processing, in order to balance the NVH optimization effect and the difficulty of the processing technology, the groove 11 can be a triangular groove with rounded corners at the vertices of the triangular shape.

[0042] In the above embodiment, since the groove 111 is recessed inward toward the axis of the rotor core 1, the distance from the top of the two protruding structures to the outer edge of the rotor core is less than the distance from the bottom of the groove 111 to the outer edge of the rotor core. Compared with the traditional rotor slot 11 structure, while ensuring that the distance between the rotor slot 11 and the outer edge of the rotor core is the same, the presence of the groove 111 structure is equivalent to having a solid structure protruding toward the axis of the rotor core at the top of the rotor slot, thereby increasing the proportion of solid structure of the rotor core 1 and obtaining better structural strength.

[0043] In one embodiment, the groove 111 is an axisymmetric structure, and the center line of symmetry of the groove 111 passes through the axis of the rotor core 1. That is, the two protrusions 112 are symmetrically arranged, thereby forming a ring of evenly spaced protrusions 112. When the rotor guide bar 2 is inserted, the corresponding rotor guide bar 2 is a symmetrical structure, and no distinction is needed during assembly.

[0044] In other embodiments, the grooves 111 of each rotor slot 11 can be non-axisymmetric structures. Since the NVH optimization effect of this solution is mainly related to the magnetic harmonics formed at the top of the rotor slot and the protrusions 112 at the top of the rotor slot, the two protrusions 112 at the top of the rotor slot are arranged symmetrically or asymmetrically with respect to the centerline of the rotor slot 11 to achieve the NVH optimization effect; that is, whether the overall structure of the rotor slot 11 is symmetrical or asymmetrical does not affect the realization of its function.

[0045] In one embodiment, the two ends of the groove 111 are connected to the two sides of the rotor slot 11, forming an acute angle. That is, the top of the protrusion 112 is a sharp-angled structure. The sharp-angled structure can reduce the first-order harmonics of the rotor while reducing the adverse effects on the motor output performance. Of course, in other embodiments, the top of the protrusion 112 can also be a rounded corner, that is, the two ends of the groove 111 are connected to the two sides of the rotor slot 11 with a rounded transition, which facilitates the machining of the rotor slot 11. In practical applications, the top of the protrusion 112 can also be other chamfered structures. It is only necessary to set the protrusion 112 to taper away from the axis. The shape or diameter of the top of the protrusion 112 can be selected according to the requirements.

[0046] In one embodiment, please refer to [reference needed]. Figure 4 The rotor slot 11 has a first side and a second side. One end of the first side is connected to one end of the groove 111, and the other end of the first side is connected to the second side, forming an obtuse angle. When the sidewall of the rotor slot 11 is a bent structure, it can increase the solid structure of the rotor core 1 and increase the distance between two adjacent rotor slots 11, that is, increase the size of the magnetic conductive area between two adjacent rotor slots 11. This avoids the increase in magnetic circuit saturation caused by excessively narrow rotor teeth, which is beneficial to improving the output torque and efficiency of the motor. In specific use, a bending point 123 is formed at the connection between the first side and the second side. The bending point 123 is closer to the outer side of the rotor, and the position of the bending point 123 can be adjusted according to different needs such as processing technology or electromagnetic performance. In other embodiments, the sidewall of the rotor slot 11 can also be straight, making the structure of the rotor slot 11 simpler and simplifying the processing technology.

[0047] The endpoint corresponding to the shortest distance between rotor slot 11 and rotor core 1 is defined as the groove endpoint. The structure protruding towards the rotor core axis corresponding to the two groove endpoints is defined as groove 100. The distance between two adjacent groove endpoints in different grooves 111 is L1, and the distance between two groove endpoints in the same groove 111 is L2, where 0.5 ≤ L2 / L1 ≤ 1.5. The outer tangent is defined as the circle centered on the axis of rotor core 1. The tops of the two protruding structures 112 of each rotor slot 11 are tangent to the outer tangent, ensuring that the vertices of grooves 111 tend to be evenly distributed, regardless of whether the grooves 111 are symmetrical structures.

[0048] In one embodiment, the rotor slot 11 is formed by connecting the bottom section 121, a side wall section 122 (equivalent to the second side), a second side wall section 124 (equivalent to the first side), a second top section 125, a connecting section 126, a first top section 128, a first side wall section 127 (equivalent to the first side), and another side wall section 122 (equivalent to the second side) in sequence. The connecting section 126 is recessed inward toward the axis of the rotor core 1 to form a groove 111. The first top section 128 and the second top section 125 both bulge outward away from the axis of the rotor core 1, and the first top section 128 and the second top section 125 are tangent to the connecting section 126. The bottom section 121, two side wall sections 122, the second slot side section 124, the second slot top section 125, the connecting section 126, the first slot top section 128, and the first slot side section 127 form the outline of the rotor slot 11. The left portion of the first slot side section 127, the first slot top section 128, and the connecting section 126 forms a raised structure 112, and the right portion of the second slot side section 124, the second slot top section 125, and the connecting section 126 forms another raised structure 112. By designing the outline of the rotor slot 11, especially by designing the first slot top section 128 and the second slot top section 125 as outwardly convex outlines, some electromagnetic force harmonics related to the first-order tooth harmonics of the rotor can be effectively suppressed.

[0049] Wherein, the connecting segment 126 can be an arc segment that is simultaneously tangent to the first slot top segment 128 and the second slot top segment 125 (e.g., Figure 4 As shown), in other embodiments, the connecting segment 126 can also be a broken line, which can be divided into two segments, left and right, and the two segments are tangent to the first slot top segment 128 and the second slot top segment 125 respectively (e.g. Figure 3 As shown), the two segments can also be connected to the first groove side segment 127 and the second groove side segment 124 respectively, and the connection is at the top of the protruding structure 112 (as shown). Figure 5 (As shown). The inward concavity of the connecting section 126 and the outward extension of the two protruding structures 112 can be adjusted according to the requirements of the processing technology and structural strength.

[0050] In one embodiment, the inscribed circle of the first slot top section 128 of any rotor slot 11 with the axis of the rotor core 1 as the center is the outer tangent line, and the first slot top section 128 and the second slot top section 125 of each rotor slot 11 are tangent to the outer tangent line.

[0051] The distance between the first top section 128 of a rotor slot 11 and the tangent point of the second top section 125 of the adjacent rotor slot 11 with the outer tangent is L1; the distance between the first top section 128 and the second top section 125 of the same rotor slot 11 with the tangent point of the outer tangent is L2, wherein the relationship between L1 and L2 is 0.5≤L2 / L1≤1.5, so as to ensure the uniformity of the distribution of the protrusion structure 112.

[0052] In one embodiment, the left side of the bottom section 121 of a rotor slot 11 is directly connected to the top section 128 of the first slot by a tangent, and the right side of the bottom section 121 is directly connected to the top section 125 of the second slot by a tangent. That is, the left sidewall section 122 is collinear with the side section 127 of the first slot, and the right sidewall section 122 is collinear with the side section 124 of the second slot.

[0053] When the side wall sections 122 on both sides are collinear with the side edge section 124 of the second slot and the side edge section 127 of the first slot, respectively, the structure of the rotor slot 11 can be simplified, and the manufacturing process can be streamlined. When there are bending points 123 between the side wall sections 122 on both sides and the side edge section 124 of the second slot and the side edge section 127 of the first slot, respectively, the solid structure of the rotor core 1 can be strengthened, and the spacing between two adjacent rotor slots 11 can be increased, thereby ensuring the strength of the rotor core 1. In actual use, the position of the bending point 123 can be adjusted according to different needs such as manufacturing process or electromagnetic performance.

[0054] In one embodiment, the distance from the apex of the groove 111 to the outer diameter of the rotor core 1 is L3, and the distance from the end point of the groove to the outer diameter of the rotor core 1 is L4, where 2 ≤ L4 / L3 ≤ 5. There is a significant height difference between the apex of the groove 111 and the two end points of the groove, that is, the distance between the edge of the top of the rotor groove and the outer edge of the rotor core 1 first increases and then decreases, thereby ensuring that there is a significant change in magnetic reluctance along the axial direction of the rotor core 1, and the magnetic reluctance is the greatest at the two end points of the groove.

[0055] In addition, such as Figure 6 and Figure 7 As shown, the present invention also provides an asynchronous motor, which includes a stator core 3, a rotor guide bar 2, and a rotor core 1 as described above. The stator core 3 and the rotor core 1 are coaxially arranged. The rotor guide bar 2 is arranged in the rotor slot 11 of the rotor core 1. Since the asynchronous motor includes the rotor core 1 as described above, the asynchronous motor has all the beneficial effects of the rotor core 1, which will not be elaborated here.

[0056] The rotor guide bar 2 is formed by casting within the rotor slot 11; or, the rotor guide bar 2 is a prefabricated magnetic strip, and the rotor guide bars 2 are inserted one-to-one into the rotor slot 11. Due to the different materials and processing methods of the rotor guide bars 2, the rotor guide bars 2 can be cast by pouring molten aluminum into the rotor slot 11. When using such casting processing, the shape of the rotor guide bar 2 is usually the same as the shape of the rotor slot 11.

[0057] The rotor core 1 comprises multiple silicon steel sheets stacked together. The silicon steel sheets can be made from conventional finished silicon steel sheets, or they can be made by surface treatment of conventional silicon steel sheets to achieve the required properties, followed by coating with an insulating layer and sintering to form the silicon steel sheets in the core. This achieves lower iron losses under the same magnetic density.

[0058] The stator structure 3 includes a stator core 31 and a plurality of stator windings 32. The stator core 31 is coaxially arranged with the rotor core 1. The inner wall of the stator core 31 has a plurality of slots 311 arranged equidistantly along the circumference of the stator core 31 to accommodate the stator windings 32. The opening of each slot 311 faces the center of the stator core 31.

[0059] In one embodiment, the electromagnetic force harmonics generated by the combined action of higher-order rotor harmonics and higher-order stator harmonics are suppressed by optimizing the tooth profile of the stator core 31. Specifically, the edge of the opening of the slot 311 is chamfered. The rotor core 1 converts some of the first-order rotor tooth harmonics into second-order or other higher-order tooth harmonics, thereby reducing the vibration noise generated by the first-order rotor tooth harmonics. The vibration noise generated by the second-order tooth harmonics can be reduced by... Figure 7 The stator chamfer 312 and other methods shown in the figure are used to suppress vibration and noise, thereby reducing the vibration and noise of the asynchronous motor.

[0060] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An asynchronous motor rotor, characterized in that, The asynchronous motor rotor has a rotor core, and the rotor core includes: a plurality of rotor slots; Each of the rotor slots is evenly arranged along the circumference of the rotor core, and a groove is formed at the end of each rotor slot away from the axis of the rotor core; the grooves on each rotor slot have the same shape. The groove is not connected to the outer edge of the rotor core; The distance between the endpoints of two adjacent grooves in different grooves is L1, and the distance between the endpoints of two grooves in the same groove is L2, where 0.5 ≤ L2 / L1 ≤ 1.

5.

2. The asynchronous motor rotor as described in claim 1, characterized in that, The groove is a triangular groove or an arc-shaped groove.

3. The asynchronous motor rotor as described in claim 1, characterized in that, The groove has an axisymmetric structure, and the center line of the groove passes through the axis of the rotor core.

4. The asynchronous motor rotor as described in claim 1, characterized in that, The grooves of each rotor slot have a non-axisymmetric structure.

5. The asynchronous motor rotor as described in claim 1, characterized in that, The two ends of the groove are respectively connected to the two sides of the rotor slot by a circular arc transition.

6. The asynchronous motor rotor as described in claim 1, characterized in that, The two ends of the groove are connected to the two sides of the rotor slot, forming an acute angle.

7. The asynchronous motor rotor as described in any one of claims 1 to 6, characterized in that, The rotor slot has a first side and a second side. One end of the first side is connected to one end of the groove, and the other end of the first side is connected to the second side. The first side and the second side form an obtuse angle.

8. The asynchronous motor rotor as described in any one of claims 1-6, characterized in that, The distance from the apex of the groove to the outer diameter of the rotor core is L3, and the distance from the end point of the groove to the outer diameter of the rotor core is L4, where 2≤L4 / L3≤5.

9. An asynchronous motor, characterized in that, The asynchronous motor includes: Stator core; The rotor of the asynchronous motor as described in any one of claims 1 to 8, wherein the stator core and the rotor core are coaxially arranged; Rotor guide bars, which are disposed in the rotor slots of the rotor core; The rotor guide bars are formed by casting within the rotor slots; or, the rotor guide bars are prefabricated magnetic strips, and the rotor guide bars are inserted into the rotor slots one by one.

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