Rotor structure and electric machine

Abstract

The application provides a rotor structure and a motor. The rotor structure comprises: a rotor core comprising a plurality of axially stacked magnetic conductive sheets, a plurality of conductor grooves and a plurality of permanent magnet grooves being arranged below one pole of the rotor core, the conductor grooves being distributed on the outer periphery of the rotor core; a magnetic steel being arranged in the permanent magnet groove; the rotor core comprising a d-axis and a q-axis, the conductor grooves comprising d-axis conductor grooves and q-axis conductor grooves; in a cross section perpendicular to the central axis of the rotor core, the permanent magnet groove comprises a middle part perpendicular to the d-axis and two end parts parallel to the q-axis, the permanent magnet groove at the two ends of the magnetic steel being filled with air; the length of the air part of the permanent magnet groove at one end of the magnetic steel in the direction perpendicular to the d-axis is L3, the length of the q-axis conductor groove in the same layer in the q-axis direction is L2, and the ratio of L3 to L2 decreases along the direction close to the outer circle of the rotor. According to the rotor structure, the application can increase the pull-in torque of the motor, improve the starting ability of the motor and improve the demagnetization resistance of the magnetic steel.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a rotor structure and a motor. Background Technology

[0002] The self-starting permanent magnet assisted synchronous reluctance motor combines the advantages of asynchronous motors with the permanent magnet assisted synchronous reluctance motor. It achieves self-starting through the asynchronous torque generated by the rotor bars and constant speed operation through permanent magnet torque and reluctance torque.

[0003] Compared to asynchronous motors, self-starting permanent magnet assisted reluctance motors operate at synchronous speed during normal operation and have no rotor copper losses, thus having higher efficiency. The magnets can provide a stronger magnetic field, and for the same specifications, they can output higher power, resulting in higher power density. The rotor of the self-starting permanent magnet assisted reluctance motor is equipped with rotor windings, retaining the asynchronous starting capability of asynchronous motors, thus enabling it to functionally replace asynchronous motors.

[0004] However, due to the influence of the negative sequence torque of the reluctance, the pull-in torque of the self-starting permanent magnet assisted synchronous reluctance motor is reduced, which will lead to a decrease in the motor's starting capability. On the other hand, the self-starting permanent magnet assisted synchronous reluctance motor is directly connected to the power grid for starting. During the starting process, the current is large, and the combined magnetic field acting on the permanent magnet is strong, which poses a risk of irreversible demagnetization of the permanent magnet. Summary of the Invention

[0005] The main objective of this invention is to provide a rotor structure and motor that can increase the traction torque of the motor, improve the starting capability of the motor, and enhance the demagnetization resistance of the magnets.

[0006] To achieve the above objectives, according to one aspect of the present invention, a rotor structure is provided, comprising:

[0007] The rotor core includes multiple axially stacked magnetic laminations. Multiple conductor slots and multiple layers of permanent magnet slots are provided under one pole of the rotor core. The conductor slots are distributed on the outer periphery of the rotor core.

[0008] The magnet is placed inside the permanent magnet slot;

[0009] The rotor core includes a d-axis and a q-axis. Under one pole, the d-axis is located on the center line of symmetry of that pole, and the q-axis is located on the center line of symmetry of two adjacent poles. The permanent magnet slots are spaced apart along the d-axis direction. The conductor slots include d-axis conductor slots and q-axis conductor slots. The d-axis conductor slots are located on the side of the rotor outer circle of the magnet close to the rotor core, and the q-axis conductor slots are located at both ends of the permanent magnet slots and extend along the extension direction of the permanent magnet slots near the end of the q-axis conductor slot.

[0010] On a cross-section perpendicular to the central axis of the rotor core, the permanent magnet slot is symmetrical about the d-axis. The permanent magnet slot includes arc segments and / or straight segments. The permanent magnet slot includes a middle part perpendicular to the d-axis and two end parts parallel to the q-axis. The magnet is set in the middle part of the permanent magnet slot, and the permanent magnet slots at both ends of the magnet are filled with air.

[0011] The length of the air portion of the permanent magnet slot located at one end of the magnet in the direction perpendicular to the d-axis is L3, and the length of the q-axis conductor slot in the same layer along the q-axis direction is L2. The ratio of L3 to L2 decreases along the direction closer to the outer circle of the rotor.

[0012] Furthermore, the length L3 of the air portion at one end of the permanent magnet slot located at least in the innermost layer along the d-axis direction is greater than the length L2 of the q-axis conductor slot in the same layer along the q-axis direction.

[0013] Furthermore, the length L3 of the air portion at one end of the permanent magnet slot located along the d-axis is less than the length L2 of the q-axis conductor slot in the same layer along the q-axis.

[0014] Furthermore, 0.35≤L3 / L2≤0.8.

[0015] Furthermore, the length of the air portion of the permanent magnet slot located at one end of the magnet decreases along the direction perpendicular to the d-axis, closer to the outer circle of the rotor.

[0016] Furthermore, the length of the air portion of the permanent magnet slot located at one end of the magnet in the direction perpendicular to the d-axis is L3, and the length of the magnet in the same layer in the direction perpendicular to the d-axis is L1. L3 / L1=k3, and k3 decreases along the direction closer to the outer circle of the rotor.

[0017] Furthermore, at least part of the permanent magnet slot is located in the air portion at one end of the magnet, and the length L3 in the direction perpendicular to the d-axis is greater than the length L1 of the magnet in the same layer in the direction perpendicular to the d-axis.

[0018] Furthermore, the width of the middle portion located at both ends of the magnet increases along the direction away from the magnet to the width at the connection position with the two ends; and / or, the width of the middle portion along the d-axis is w3, the width of the magnet along the d-axis is w1, and w3≥w1.

[0019] Furthermore, the maximum width of the two ends in the direction perpendicular to the q-axis is w6, where the relationship between w2 and w6 satisfies 0.8w2≤w6≤1.1w2.

[0020] Furthermore, 0.9w2≤w6≤w2.

[0021] Furthermore, the length of the q-axis conductor slot along the q-axis direction is L2, and the width along the direction perpendicular to the q-axis direction is w2. Along the direction away from the q-axis, L2 gradually decreases, and the ratio of L2 to w2, L2 / w2, gradually decreases. At least part of the relationship between the length L2 of the q-axis conductor slot along the q-axis direction and the radius R of the rotor outer circle satisfies: 0.15≤L2 / R≤0.35.

[0022] Furthermore, 3 ≤ L2 / w2 ≤ 7.

[0023] Furthermore, the length of the magnet in the direction perpendicular to the d-axis is L1, and the ratio between the length L2 of the q-axis conductor slot in the q-axis direction and the length L1 of the magnet in the same layer in the direction perpendicular to the d-axis is L2 / L1=k2. Along the d-axis, k2 gradually decreases in the direction close to the outer circle of the rotor.

[0024] Furthermore, at least part of the length L2 of the q-axis conductor groove along the q-axis direction is more than 0.8 times the length L1 of the magnet located in the same layer in the direction perpendicular to the d-axis.

[0025] Furthermore, the width of the magnet along the d-axis is w1, and the relationship between the width w2 of the q-axis conductor groove along the direction perpendicular to the q-axis and the width w1 of the magnet in the same layer along the d-axis satisfies w2 > w1.

[0026] Furthermore, the relationship between w1 and w2 satisfies 1.2≤w2 / w1≤2.

[0027] Furthermore, the minimum width of the magnetic channel between two adjacent q-axis conductor slots in the direction perpendicular to the q-axis is q1, and the minimum width of the magnetic channel between all adjacent q-axis conductor slots on the same side of the q-axis in the direction perpendicular to the q-axis is qz, where q1 < qz.

[0028] Furthermore, under the same pole, the minimum width of the magnetic channel between adjacent q-axis conductor slots in the direction perpendicular to the q-axis is qn, and the minimum width of the magnetic channel between adjacent permanent magnet slots corresponding to adjacent q-axis conductor slots in the direction of the d-axis is dz, where 0.9qn≤dz≤1.35qn.

[0029] Furthermore, under the same pole, the number of d-axis conductor slots located on the side of the magnet near the outer circle of the rotor is at least two, and the total length L5 of the d-axis conductor slots in the direction perpendicular to the d-axis is greater than the length L1 of the magnet in the direction perpendicular to the d-axis.

[0030] Furthermore, 1.2≤L5 / L1≤2.

[0031] Furthermore, the minimum width of the spacing between adjacent d-axis conductor slots perpendicular to the d-axis direction is w4, the width of the magnet along the d-axis direction is w1, and w4≥2w1; and / or, the relationship between the maximum width w5 of the d-axis conductor slot in the d-axis direction and the width w1 of the magnet along the d-axis direction satisfies w5≥2w1.

[0032] Furthermore, the distance between the side of the conductor slot closest to the rotor's outer circumference and the rotor's outer circumference is d4, and the distance between the side of the q-axis conductor slot closest to the permanent magnet slot and the permanent magnet slot in the same layer is d5, where 0 < d4 ≤ 1.75. d, 0 < d⁵ ≤ 1.75 d, where d is the thickness of the air gap between the inner circle of the stator and the outer circle of the rotor.

[0033] Furthermore, the rotor structure also includes a short-circuit end ring, which covers the conductor slots and short-circuits them. The outer circumference of the short-circuit end ring is circular, and the short-circuit end ring includes an inner hole. The inner hole is a polygon formed by straight line segments or a polygon formed by straight line segments and arc segments. Under the same pole, the radial width of the short-circuit end ring is different at different positions in the d-axis to q-axis region. The relationship between the minimum radial width r2 of the short-circuit end ring and the radius R of the rotor outer circle satisfies: 0.14≤r2 / R≤0.3.

[0034] According to another aspect of the present invention, an electric motor is provided, comprising a stator structure and a rotor structure, wherein the rotor structure is the rotor structure described above, and the stator structure is sleeved outside the rotor structure.

[0035] The rotor structure, applying the technical solution of this invention, includes: a rotor core comprising multiple axially stacked magnetic laminations; multiple conductor slots and multiple permanent magnet slots are provided under one pole of the rotor core, the conductor slots being distributed on the outer periphery of the rotor core; magnets are disposed within the permanent magnet slots; the rotor core includes a d-axis and a q-axis, under one pole, the d-axis is located on the center line of symmetry of that pole, the q-axis is located on the center line of symmetry of two adjacent poles, the permanent magnet slots are spaced apart along the d-axis direction, the conductor slots include d-axis conductor slots and q-axis conductor slots, the d-axis conductor slots are located on the side of the magnets near the outer circumference of the rotor core, and the q-axis conductor slots are located within the permanent magnet slots. The permanent magnet slot extends along the d-axis and the direction of extension of the permanent magnet slot near the q-axis conductor slot. In a cross-section perpendicular to the central axis of the rotor core, the permanent magnet slot is symmetrical about the d-axis. The permanent magnet slot includes arc segments and / or straight segments. The permanent magnet slot includes a middle part perpendicular to the d-axis and two end parts parallel to the q-axis. The magnet is disposed in the middle part of the permanent magnet slot. The permanent magnet slots at both ends of the magnet are filled with air. The length of the air portion of the permanent magnet slot at the end of the magnet in the direction perpendicular to the d-axis is L3. The length of the q-axis conductor slot in the same layer along the q-axis is L2. The ratio of L3 to L2 decreases along the direction close to the outer circle of the rotor. Setting the length relationship between the air portion of the permanent magnet slot and the q-axis conductor slot in the same layer can make reasonable use of the space on the rotor core and ensure a conductor slot with a sufficient area. A conductor slot with a sufficient area can increase the pull torque and improve the starting capability of the motor. On the other hand, the squirrel-cage asynchronous magnetic field generated by the conductor slot has a shielding effect on the demagnetizing magnetic field of the armature winding. That is, the squirrel-cage asynchronous magnetic field has a protective effect on the magnet, protecting the magnet from demagnetization and improving the magnet's resistance to demagnetization. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 A structural dimension diagram of the rotor structure according to an embodiment of the present invention is shown;

[0038] Figure 2 The graph showing the relationship between L2 / w2 and pull-in torque of the rotor structure according to an embodiment of the present invention is shown.

[0039] Figure 3 A schematic diagram of the asynchronous magnetic field improvement and demagnetization of the magnet in the rotor structure of an embodiment of the present invention is shown;

[0040] Figure 4 The graph shows the relationship between the remanence of the magnets in the rotor structure of an embodiment of the present invention and the variation of w2 / w1;

[0041] Figure 5The graph shows the relationship between the magnetic flux density of each layer of magnets in the rotor structure of an embodiment of the present invention and the variation of L5 / L1.

[0042] Figure 6 A comparison diagram showing different magnetic flux densities of the magnets in an electric motor according to an embodiment of the present invention and in an electric motor of the related art is shown.

[0043] Figure 7 The graph shows the relationship between the utilization rate of each layer of magnets in the rotor structure of an embodiment of the present invention and the L3 / L1 ratio.

[0044] Figure 8 A comparison diagram of the temperature rise of the magnets of the motor of an embodiment of the present invention and a motor of the related art under different operating conditions is shown.

[0045] Figure 9 The diagram shows the magnetic density cloud of the magnets in the rotor structure of an embodiment of the present invention under heavy load;

[0046] Figure 10 This shows a magnetic density cloud diagram of the outermost magnet of a prior art rotor structure under heavy load;

[0047] Figure 11 A schematic diagram of the coverless short-circuit end ring structure of the rotor structure according to an embodiment of the present invention is shown;

[0048] Figure 12 An exploded structural diagram of the coverless short-circuit end ring of the rotor structure according to an embodiment of the present invention is shown;

[0049] Figure 13 This diagram illustrates a first mating structure of the cover plate and rotor core of the rotor structure according to an embodiment of the present invention.

[0050] Figure 14 A diagram showing a second mating structure of the cover plate and rotor core of an embodiment of the present invention is provided.

[0051] Figure 15 The diagram shows the mating structure of the first cover plate, the first end ring, and the rotor core of the rotor structure according to an embodiment of the present invention.

[0052] Figure 16 The diagram shows the mating structure of the second cover plate, the second end ring, and the rotor core of the rotor structure according to an embodiment of the present invention.

[0053] Figure 17 An exploded structural diagram of the rotor structure with a covered plate short-circuit end ring according to an embodiment of the present invention is shown;

[0054] Figure 18 A schematic diagram of the rotor structure according to another embodiment of the present invention is shown;

[0055] Figure 19 The graphs showing the relationship between the minimum torque and the pull torque of the rotor structure according to an embodiment of the present invention as a function of r1 / R are shown.

[0056] Figure 20 A schematic diagram of the cooperation structure between the rotor structure and the stator structure of the motor according to an embodiment of the present invention is shown;

[0057] Figure 21 A graph showing the speed comparison between a motor according to an embodiment of the present invention and a motor of related technologies during the starting process is provided.

[0058] Figure 22 A comparison diagram of the magnetic flux density of the magnets in the motor of an embodiment of the present invention and a motor of related technologies is shown during the starting process;

[0059] Figure 23 A torque comparison diagram is shown between the motor of an embodiment of the present invention and a motor of related technologies;

[0060] Figure 24 A comparison diagram of the back EMF waveforms of a motor according to an embodiment of the present invention and a motor of related technologies is shown;

[0061] Figure 25 A comparison diagram of the current waveforms of a motor according to an embodiment of the present invention and a motor of related technologies is shown;

[0062] Figure 26 A comparison diagram of the harmonic amplitudes of a motor according to an embodiment of the present invention and a motor of related technologies is shown.

[0063] The above figures include the following reference numerals:

[0064] 1. Rotor structure; 2. Rotor core; 3. Magnetic laminations; 4. Conductor slots; 41. q-axis conductor slot; 42. d-axis conductor slot; 5. Permanent magnet slot; 6. Magnet; 7. Rotor shaft hole; 8. Stator structure; 9. Short-circuit end ring; 101. First cover plate; 102. Second cover plate; 111. First end ring; 112. Second end ring. Detailed Implementation

[0065] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0066] See also Figures 1 to 26As shown, according to an embodiment of the present invention, the rotor structure includes: a rotor core 2, the rotor core 2 including a plurality of axially stacked magnetic laminations 3, a plurality of conductor slots 4 and a plurality of permanent magnet slots 5 disposed under one pole of the rotor core 2, the conductor slots 4 being distributed on the outer periphery of the rotor core 2; a magnet 6 disposed within the permanent magnet slots 5; the rotor core 2 including a d-axis and a q-axis, under one pole, the d-axis being located on the symmetry center line of that pole, the q-axis being located on the symmetry center line of two adjacent poles, the permanent magnet slots 5 being spaced apart along the d-axis direction, the conductor slots 4 including d-axis conductor slots 42 and q-axis conductor slots 41, the d-axis conductor slots 42 being located within the magnet 6. On one side of the outer circle of the rotor near the rotor core 2, the q-axis conductor slot 41 is located at both ends of the permanent magnet slot 5 and extends along the extension direction of the permanent magnet slot 5 near the end of the q-axis conductor slot 41; in a section perpendicular to the central axis of the rotor core, the length of the q-axis conductor slot 41 along the q-axis direction is L2, and the width along the perpendicular q-axis direction is w2. Along the direction away from the q-axis, L2 gradually decreases, and the ratio of L2 to w2, L2 / w2, gradually decreases; at least part of the q-axis conductor slot 41 has a relationship between the length L2 along the q-axis direction and the radius R of the outer circle of the rotor that satisfies: 0.15≤L2 / R≤0.35.

[0067] The squirrel-cage asynchronous magnetic field generated by the conductor slots shields the demagnetizing magnetic field of the armature windings, meaning the squirrel-cage magnetic field protects the magnets. By defining the ratio between the conductor slot length and the rotor's outer radius, the area of ​​the conductor slots can be increased without affecting the arrangement of the magnetic guide channels, thereby increasing the motor's pull torque and starting capability. Simultaneously, the protective effect of the squirrel-cage magnetic field on the magnets is enhanced, improving their resistance to demagnetization. This rotor structure, by defining the ratio between the conductor slot length and width, and between the conductor slot length and the rotor's outer radius, ensures both a sufficient conductor slot area and a reasonable arrangement of the magnetic guide channels. A conductor slot area increases the motor's pull torque and starting capability, while a reasonable arrangement of the magnetic guide channels prevents rotor magnetic saturation, increases the motor's permanent magnet torque and reluctance torque, and improves motor efficiency.

[0068] In one embodiment, 3 ≤ L2 / w2 ≤ 7. By limiting the range of L2 / w2, the ratio between the length and width of the q-axis conductor slot 41 can be optimized, making the relationship between the length and width of the q-axis conductor slot 41 reasonable. While ensuring a sufficient area conductor slot, the design of the length and width of the q-axis conductor slot 41 can achieve a magnetically conductive channel with better dimensional design, resulting in optimal overall performance of the motor's pull torque and the magnetic conductivity of the magnetically conductive channel, and thus better motor efficiency.

[0069] See also Figure 2The figure shows the relationship between L2 / w2 and pull torque in the rotor structure of an embodiment of the present invention. Under the same operating conditions, when w2 remains constant, the pull torque gradually increases with the increase of L2. When L2 increases to a certain extent, the rate of increase of the pull torque decreases significantly. When the ratio of L2 to w2 satisfies 3≤L2 / w2≤7, a larger pull torque can be obtained while reasonably arranging the conductor slots, thus more effectively improving the motor's starting capability. (See also...) Figure 2 As shown, the motor in this embodiment of the invention is easier to pull into synchronous and stable operation.

[0070] In one embodiment, the length of the magnet 6 in the direction perpendicular to the d-axis is L1, and the ratio of the length L2 of the q-axis conductor groove 41 along the q-axis direction to the length L1 of the magnet 6 in the same layer in the direction perpendicular to the d-axis is L2 / L1=k2. Along the d-axis, k2 gradually decreases in the direction close to the outer circle of the rotor.

[0071] In one embodiment, at least a portion of the length L2 of the q-axis conductor groove 41 along the q-axis direction is greater than 0.8 times the length L1 of the magnet 6 located in the same layer in the direction perpendicular to the d-axis. This arrangement can increase the protective effect of the squirrel cage magnetic field on the magnet 6, utilizing the magnetic field generated by the conductor groove structure to protect the magnet 6 and prevent the magnet 6 from demagnetizing during startup.

[0072] In one embodiment, the width of the magnet 6 along the d-axis is w1, and the relationship between the width w2 of the q-axis conductor groove 41 along the direction perpendicular to the q-axis and the width w1 of the magnet 6 in the same layer along the d-axis satisfies w2 > w1.

[0073] In one embodiment, the relationship between w1 and w2 satisfies 1.2≤w2 / w1≤2.

[0074] The thickness of the q-axis conductor groove 41 is optimized so that the thickness of the q-axis conductor groove 41 and the thickness of the permanent magnet groove 5 are within a set range. While ensuring that the conductor groove of a certain area increases the pull torque of the motor, the protective effect of the squirrel cage magnetic field generated by the conductor groove on the magnet 6 is further strengthened.

[0075] See also Figure 3 The diagram shown is a schematic of the asynchronous magnetic field used in an embodiment of the present invention to improve the demagnetization of the magnets; see also [link to previous section]. Figure 4 The figure shows the relationship between the magnetic flux density of the magnet and w2 / w1 in the rotor structure of the embodiment of the present invention. Under the same working conditions, when w1 is constant, the remanence of the magnet increases with the increase of w2. When w2 / w1 satisfies 1.2≤w2 / w1≤2, the utilization rate of the magnet can be improved while avoiding irreversible demagnetization of the magnet during the start-up process.

[0076] In one embodiment, the minimum width of the magnetic channel between two adjacent q-axis conductor slots 41 in the direction perpendicular to the q-axis is q1, and the minimum width of the magnetic channel between all adjacent q-axis conductor slots 41 on the same side of the q-axis in the direction perpendicular to the q-axis is qz, where q1 < qz.

[0077] In this embodiment, the dimension of the magnetic channel in the direction perpendicular to the q-axis is the width dimension. Taking three magnetic channels as an example, the minimum widths of the three magnetic channels along the direction away from the q-axis are q1, q2 and q3, respectively, where q1 is smaller than the smaller of the minimum widths of the other two magnetic channels, i.e., q1 < min(q2, q3).

[0078] At the same pole, along the direction away from the q-axis, the width of the magnetic channel decreases in the direction perpendicular to the q-axis.

[0079] Taking three magnetic channels as an example, they are distinguished by their distance from the q-axis: the first, second, and third magnetic channels. The q-axis passes through the first magnetic channel, which has the smallest minimum width q1. Among the other two magnetic channels, the minimum width q2 of the second magnetic channel (closer to the q-axis) is greater than or equal to the minimum width q3 of the third magnetic channel (furthest from the q-axis), i.e., q2 ≥ q3. This arrangement prevents overload of the magnetic channels between the magnets 6, avoids rotor saturation, maximizes permanent magnet torque and reluctance torque, and reduces motor harmonics.

[0080] In one embodiment, under the same pole, the minimum width of the magnetic channel between adjacent q-axis conductor slots 41 in the direction perpendicular to the q-axis is qn, and the minimum width of the magnetic channel between adjacent permanent magnet slots 5 corresponding to adjacent q-axis conductor slots 41 in the direction of the d-axis is dz, where 0.9qn≤dz≤1.35qn.

[0081] In this embodiment, taking three magnetically conductive channels as an example, the relationship between the minimum width q2 of the second magnetically conductive channel and the minimum width d2 of the magnetically conductive channel between the two permanent magnet slots 5 corresponding to the q-axis conductor slots 41 on both sides of the second magnetically conductive channel satisfies 0.9. q²≤d²≤1.35 The relationship between the minimum width q3 of the third magnetic channel and the minimum width d3 of the magnetic channel between the two permanent magnet slots 5 corresponding to the q-axis conductor slots 41 on both sides of the third magnetic channel satisfies 0.9. q3≤d3≤1.35 q3. The purpose of this setting is to ensure that there is sufficient width between the permanent magnet slots 5 to avoid magnetic field saturation, which would affect the magnetic flux flow and permanent magnet torque output in the channels between the permanent magnet slots 5.

[0082] In one embodiment, the conductor groove 4 is a closed groove, and the conductor groove 4 is filled with a conductive but non-magnetic material; and / or, on a cross-section perpendicular to the central axis of the rotor core 2, the conductor groove 4 includes arc segments and / or straight segments. The shape of the conductor groove 4 can be rectangular, quasi-rectangular, or irregular polygonal. The purpose of the conductor groove 4 is to fill it with a conductive but non-magnetic material to form a squirrel cage structure, thereby enabling the motor to start automatically.

[0083] In one embodiment, under the same pole, there are at least two d-axis conductor slots 42 located on the side of the magnet 6 near the outer circle of the rotor. The total length L5 of the d-axis conductor slots 42 in the direction perpendicular to the d-axis is greater than the length L1 of the magnet 6 in the direction perpendicular to the d-axis. The side of the d-axis conductor slot 42 furthest from the d-axis on the first side is called the first side, and the side of the d-axis conductor slot 42 furthest from the d-axis on the second side is called the second side. The total length L5 is the maximum distance between the first side and the second side in the direction perpendicular to the d-axis.

[0084] In one embodiment, 1.2 ≤ L5 / L1 ≤ 2.

[0085] See also Figure 5 The figure shows the relationship between the magnetic flux density of each layer of magnets in the rotor structure of an embodiment of the present invention and the change of L5 / L1. Under the same operating conditions, when L1 remains constant, the remanence of the magnets increases with the increase of L5. When L5 / L1 satisfies 1.2≤L5 / L1≤2, the utilization rate of the magnets can be improved while avoiding irreversible demagnetization of the magnets during the starting process, thus improving the starting demagnetization of the motor; see also [reference]. Figure 6 The diagram shows a comparison of different magnetic flux densities of the magnets in the motor of the embodiment of the present invention and the motor of the related art. Under the same working conditions, the motor of the embodiment of the present invention can increase the maximum and minimum magnetic flux densities of the magnets during the starting process and reduce the gap between the maximum and minimum magnetic flux densities, thereby improving the stability of the magnets during the starting process.

[0086] In one embodiment, the minimum width of the spacing between adjacent d-axis conductor slots 42 in the direction perpendicular to the d-axis is w4, the width of the magnet 6 in the direction of the d-axis is w1, and w4≥2w1; and / or, the relationship between the maximum width w5 of the d-axis conductor slot 42 in the direction of the d-axis and the width w1 of the magnet 6 in the direction of the d-axis satisfies w5≥2w1.

[0087] A d-axis conductor slot 42 of a certain size can improve the starting capability of the motor and enhance the protection capability of the magnet 6. The width of the d-axis conductor slot 42 ensures a certain magnetic channel width, allowing part of the magnetic field of the magnet 6 to enter the d-axis and increase the permanent magnet torque.

[0088] In one embodiment, each permanent magnet slot 5 extends to the q-axis conductor slot 41 on both sides of the d-axis with the d-axis as the center of symmetry. The permanent magnet slot 5 is composed of arc segments and / or straight segments. On the cross-section perpendicular to the central axis of the rotor core 2, the permanent magnet slot 5 is symmetrical about the d-axis. The permanent magnet slot 5 includes arc segments and / or straight segments. The permanent magnet slot 5 includes a middle part perpendicular to the d-axis and two end parts parallel to the q-axis. The magnet 6 is disposed in the middle part of the permanent magnet slot 5, and the permanent magnet slots 5 at both ends of the magnet 6 are filled with air.

[0089] In one embodiment, the width of the middle portion located at both ends of the magnet 6 increases along the direction away from the magnet 6 to the width at the junction with the two end portions.

[0090] In one embodiment, the minimum width of the middle portion located at both ends of the magnet 6 along the d-axis is w3, and the width of the magnet 6 along the d-axis is w1, where w3 ≥ w1.

[0091] The above configuration can reasonably arrange the magnets and permanent magnet slots, and can make the maximum use of the area of ​​the magnetic conductive laminations. This can avoid magnetic field saturation, reduce the amount of magnets used, improve the utilization rate of magnets, increase the permanent magnet torque and reluctance torque, and improve the torque output capability.

[0092] In one embodiment, the maximum width of the two ends in the direction perpendicular to the q-axis is w6, which is also the maximum thickness of the air portion of the permanent magnet slot 5 is w6, wherein the relationship between w2 and w6 satisfies 0.8w2≤w6≤1.1w2.

[0093] In one embodiment, 0.9w2≤w6≤w2.

[0094] This design avoids the problem of excessively narrow magnetic channels between permanent magnet slots 5, which could lead to reduced motor output and decreased motor efficiency.

[0095] In one embodiment, the length of the air portion of the permanent magnet slot 5 located at one end of the magnet 6 decreases along the direction perpendicular to the d-axis in a direction close to the outer circle of the rotor.

[0096] In one embodiment, the length of the air portion of the permanent magnet slot 5 located at one end of the magnet 6 in the direction perpendicular to the d-axis is L3, and the length of the magnet 6 in the same layer in the direction perpendicular to the d-axis is L1, L3 / L1=k3, and k3 decreases along the direction closer to the outer circle of the rotor.

[0097] See also Figure 7 The figure shows the relationship between the utilization rate of each layer of magnets in the rotor structure of an embodiment of the present invention and the change of L3 / L1. Under the same working condition, when L1 is constant, the utilization rate of the magnets decreases as L3 decreases. Compared with multi-layer magnets under a single pole, the utilization rate of the outer layer is relatively the highest.

[0098] In one embodiment, at least a portion of the permanent magnet slot 5 is located in the air portion at one end of the magnet 6. The length L3 in the direction perpendicular to the d-axis is greater than the length L1 of the magnet 6 in the same layer in the direction perpendicular to the d-axis.

[0099] By limiting the amount of magnets used, the utilization rate of magnets can be increased.

[0100] In one embodiment, the length of the air portion of the permanent magnet slot 5 located at one end of the magnet 6 in the direction perpendicular to the d-axis is L3, and the length of the q-axis conductor slot 41 in the same layer along the q-axis direction is L2. The ratio of L3 to L2 decreases along the direction closer to the outer circle of the rotor.

[0101] In one embodiment, at least the length L3 of the air portion of the innermost permanent magnet slot 5 located at one end of the magnet 6 is greater than the length L2 of the q-axis conductor slot 41 in the same layer along the q-axis direction.

[0102] In one embodiment, the length L3 of the air portion of the outermost permanent magnet slot 5 located at one end of the magnet 6 along the d-axis direction is less than the length L2 of the q-axis conductor slot 41 in the same layer along the q-axis direction.

[0103] In one embodiment, 0.35 ≤ L3 / L2 ≤ 0.8.

[0104] This configuration ensures sufficient conductor slot area, improves the motor's starting capability, and protects the magnets from demagnetization.

[0105] In one embodiment, the length of the magnet 6 in the direction perpendicular to the d-axis is L1, and the total length of the permanent magnet slot 5 located in the same layer as the magnet 6 in the direction perpendicular to the d-axis is L4. The ratio k4 between L1 and L4 increases along the direction closer to the outer circle of the rotor.

[0106] In one embodiment, the ratio k4 between the length L1 of the innermost magnet 6 along the d-axis and the length L4 of the permanent magnet slot 5 in the same layer satisfies 0.2≤k4≤0.4, and along the direction close to the outer circle of the rotor, the increase ratio of k4 of adjacent layers is greater than or equal to 1.25.

[0107] The purpose of this design is to reduce the amount of magnets used and improve the utilization rate of magnets.

[0108] In one embodiment, under the same pole, the magnets 6 are arranged in two or more layers. The width of the outermost magnet 6 along the d-axis is greater than or equal to the width of each of the other magnet layers 6 along the d-axis, and the difference in length L1 between each magnet layer 6 in the direction perpendicular to the d-axis is within 30%. The purpose of this arrangement is to ensure that the magnets do not demagnetize, while ensuring the amount of magnets used in each layer, avoiding local protection and low magnet utilization.

[0109] In one embodiment, the minimum distance between the outermost magnet 6 closest to the outer circle of the rotor and the outer circle of the rotor is r1, and the radius of the outer circle of the rotor is R, where 0.18≤r1 / R≤0.33.

[0110] In one embodiment, the length of the q-axis conductor groove 41 along the q-axis direction is L2, and the length L2 of the outermost q-axis conductor groove 41 near the outer circle of the rotor satisfies 1 < r1 / L2 < 2.

[0111] The minimum distance between the outermost magnet and the outer circle of the rotor determines the size of the rotor end ring. Ensuring a certain size rotor end ring can reduce the pressure deformation of the rotor end ring and rotor core during manufacturing. The rotor end ring covers the conductor slot to achieve short circuit. When the motor starts, the conductor slot generates asynchronous torque to start the motor.

[0112] See also Figure 19 The figure shows the relationship between the minimum torque and the pull-in torque of the rotor structure in an embodiment of the present invention and r1 / R. Under the same operating conditions, when R is constant, the minimum torque decreases and the pull-in torque increases as r1 increases. If the minimum torque is too small, it cannot drive the load. If the pull-in torque is too small, it is difficult for the motor to be pulled into synchronous speed operation. When r1 / R satisfies the condition 0.18≤r1 / R≤0.33, the motor starting and smooth operation can be improved, and the risk of demagnetization of the magnets during the starting process can be reduced.

[0113] In one embodiment, the middle part of the outermost magnet 6, which is closer to the outer circle of the rotor, protrudes towards the outer circle of the rotor. In this embodiment, the magnet is rectangular or rectangular in shape, and the outermost magnet near the outer circumference of the rotor can be set as an arch or an inverted V-shape to increase the minimum distance r1 between the outermost magnet and the outer circumference of the rotor, thereby further ensuring the motor manufacturing process and the motor's starting capability.

[0114] In one embodiment, the distance between the side of the conductor slot 4 closest to the outer circle of the rotor and the outer circle of the rotor is d4, and the distance between the side of the q-axis conductor slot 41 closest to the permanent magnet slot 5 and the permanent magnet slot 5 in the same layer is d5, where 0 < d4 ≤ 1.75 d, 0 < d⁵ ≤ 1.75 d, where d is the thickness of the air gap between the inner circle of the stator and the outer circle of the rotor. This design not only ensures the mechanical strength of the rotor structure but also reduces magnetic leakage between the conductor slots and the magnets, thereby improving motor efficiency.

[0115] In one embodiment, cover plates are provided at both ends of the rotor core 2. The cover plates are made of the same material as the magnetic laminations 3 of the rotor core 2, but have a different structure. The cover plates have connecting slots that are adapted to the structure of the conductor slots 4. The cover plates cover both ends of the permanent magnet slots 5. The cover plate at at least one end of the rotor core 2 covers the portion of the outermost magnet 6 near the outer circle of the rotor. The cover plates can increase the minimum distance from the outermost magnet to the outer circle of the rotor, thereby increasing the area of ​​the rotor end ring, improving the starting of the motor, and preventing the magnets from demagnetizing.

[0116] In one embodiment, the rotor structure further includes a short-circuit end ring 9, which covers the conductor slots 4 and short-circuit-connects them. The short-circuit end ring 9 has a circular outer circumference and includes an inner hole. The inner hole is a polygon formed by straight line segments or a polygon formed by straight line segments and arc segments. Under the same pole, the radial width of the short-circuit end ring 9 is different at different positions in the d-axis to q-axis region. The relationship between the minimum radial width r2 of the short-circuit end ring 9 and the radius R of the rotor outer circle satisfies: 0.14 ≤ r2 / R ≤ 0.3. This setting can ensure a certain radial width of the end ring, improving the motor's starting capability; at the same time, the end ring located in the d-axis direction also helps to improve the motor's anti-demagnetization capability.

[0117] In one embodiment, the rotor structure further includes a short-circuit end ring 9. Cover plates are provided at both ends of the rotor core 2. Each cover plate has a connecting groove corresponding to the conductor groove 4, which is adapted to the structure of the conductor groove 4. The cover plates cover both ends of the permanent magnet groove 5. One end of the cover plate covers the portion of the outermost magnet 6 near the outer circle of the rotor, while the other end of the cover plate is located radially outside the outermost magnet 6 of the rotor's outer circle. The short-circuit end ring 9 is disposed on the cover plate and covers the connecting groove. The structure of the short-circuit end ring 9 is adapted to the structure of the cover plate at its end. The relationship between the minimum radial width r2 of the short-circuit end ring 9 and the radius R of the rotor's outer circle satisfies: 0.14 ≤ r2 / R ≤ 0.3, thereby ensuring that the rotor structure has an end ring of a certain area, which helps improve the motor's starting capability and prevents magnet demagnetization.

[0118] In this embodiment, the cover plate includes a first cover plate 101 and a second cover plate 102, and the short-circuit end ring 9 includes a first end ring 111 and a second end ring 112. The first cover plate 101 covers both ends of the permanent magnet slot 5 but does not cover the outermost magnet 6, so that the magnet 6 is completely located outside the first cover plate 101. The second cover plate 102 covers the permanent magnet slot 5 and part of the outermost magnet 6, thereby increasing the minimum distance from the outermost magnet to the outer circle of the rotor, increasing the area of ​​the rotor end ring, improving the starting of the motor, and preventing the magnet from demagnetizing. The structure of the first end ring 111 is adapted to the first cover plate 101 and completely covers the first cover plate 101, and the structure of the second end ring 112 is adapted to the second cover plate 102 and completely covers the second cover plate 102.

[0119] The above method allows for different structures to be used for the cover plates and end rings at both ends of the rotor core 2, thereby improving the design flexibility and applicability of the rotor structure.

[0120] According to an embodiment of the present invention, the motor includes a stator structure 8 and a rotor structure 1, wherein the rotor structure 1 is the rotor structure described above, and the stator structure is sleeved outside the rotor structure.

[0121] In one embodiment, a plurality of stator teeth and stator slots are evenly distributed on the stator core. When any d-axis centerline of the rotor structure 1 is aligned with the stator tooth centerline of the stator structure 8, the d-axis centerline adjacent to the d-axis centerline is aligned with the stator slot centerline, and the q-axis centerline adjacent to the d-axis centerline is misaligned with either the stator tooth centerline or the stator slot centerline.

[0122] By setting the relationship between the d-axis centerline, the stator slot centerline, and the stator tooth centerline, the positional relationship between the q-axis conductor slot and the stator tooth slot can be changed, reducing tooth and slot harmonics, improving the sinusoidality of the current waveform, reducing noise and harmonic losses, and improving motor efficiency.

[0123] See also Figure 8 The diagram shows a comparison of the temperature rise of the magnets in the motor of this invention and motors of related technologies under different operating conditions. Under the same operating conditions, compared to existing technologies, the technology of this invention can reduce the temperature rise by at least 20%, thereby improving the demagnetization problem that may occur in the permanent magnets of the motor under heavy load and high temperature. See also... Figures 9-10 As shown, the technology of this invention can improve problems such as temperature rise and easy demagnetization under heavy load. See also... Figure 9 As shown, the present invention has fewer magnetic field harmonics, lower eddy current losses, better heat dissipation, higher magnetic flux density of permanent magnets during motor operation, and improved resistance to demagnetization of permanent magnets.

[0124] See also Figure 21 The figure shows a comparison of the starting speeds of the motor in the embodiment of the present invention and the motor in related technologies. As can be seen from the figure, compared with the motor in related technologies, the motor in the embodiment of the present invention can be better pulled into synchronization and run stably, and has a stronger starting synchronization capability.

[0125] See also Figure 22 The figure shows the change in magnetic flux density of the magnet in the motor of the embodiment of the present invention and the motor of the related technology during the starting process. As can be seen from the figure, compared with the motor of the related technology, the motor of the embodiment of the present invention has a higher magnetic flux density and stronger anti-demagnetization ability.

[0126] See also Figure 23The diagram shows a comparison of the torques of the motor in the embodiment of the present invention with those of motors in related technologies. Under the same operating conditions, compared with the prior art, the motor of the present invention has increased torque in all aspects, resulting in a larger total torque and stronger output capability.

[0127] See also Figure 20 The diagram shown is a schematic diagram of the cooperation structure between the rotor structure and the stator structure of the motor according to an embodiment of the present invention. Figures 24-26 The figures show a comparison of the back EMF waveform, current waveform, and harmonic amplitude of the motor in the embodiment of the present invention with those of motors in related technologies. The back EMF waveform and current waveform of the present invention both exhibit superior sinusoidal characteristics and lower harmonic amplitude, which can improve motor harmonics and reduce motor vibration noise.

[0128] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0129] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rotor structure, characterized in that, include: The rotor core (2) includes multiple axially stacked magnetic laminations (3). Multiple conductor slots (4) and multilayer permanent magnet slots (5) are provided under one pole of the rotor core (2). The conductor slots (4) are distributed on the outer periphery of the rotor core (2). A magnet (6) is disposed in the permanent magnet groove (5); The rotor core (2) includes a d-axis and a q-axis. Under one pole, the d-axis is located on the center line of symmetry of that pole, and the q-axis is located on the center line of symmetry of two adjacent poles. The permanent magnet slots (5) are spaced apart along the d-axis direction. The conductor slots (4) include a d-axis conductor slot (42) and a q-axis conductor slot (41). The d-axis conductor slot (42) is located on the side of the magnet (6) near the outer circle of the rotor core (2). The q-axis conductor slot (41) is located at both ends of the permanent magnet slots (5) and extends along the extension direction of the permanent magnet slots (5) near the end of the q-axis conductor slot (41). On a cross section perpendicular to the central axis of the rotor core (2), the permanent magnet slot (5) is symmetrical about the d-axis. The permanent magnet slot (5) includes arc segments and / or straight segments. The permanent magnet slot (5) includes a middle part perpendicular to the d-axis and two end parts parallel to the q-axis. The magnet (6) is disposed in the middle part of the permanent magnet slot (5). The permanent magnet slots (5) at both ends of the magnet (6) are filled with air. The length of the air portion of the permanent magnet slot (5) located at one end of the magnet (6) in the direction perpendicular to the d-axis is L3, and the length of the q-axis conductor slot (41) in the same layer along the q-axis direction is L2. The ratio of L3 to L2 decreases along the direction closer to the outer circle of the rotor. 0.35≤L3 / L2≤0.

8.

2. The rotor structure according to claim 1, characterized in that, The length L3 of the air portion of the permanent magnet groove (5) located at least in the innermost layer along the d-axis direction is greater than the length L2 of the q-axis conductor groove (41) in the same layer along the q-axis direction.

3. The rotor structure according to claim 2, characterized in that, The length L3 of the air portion of the permanent magnet groove (5) located at one end of the magnet (6) along the d-axis direction is less than the length L2 of the q-axis conductor groove (41) in the same layer along the q-axis direction.

4. The rotor structure according to claim 1, characterized in that, The length of the air portion of the permanent magnet slot (5) located at one end of the magnet (6) decreases along the direction of the d-axis in a direction perpendicular to the d-axis, close to the outer circle of the rotor.

5. The rotor structure according to claim 4, characterized in that, The length of the air portion of the permanent magnet slot (5) located at one end of the magnet (6) in the direction perpendicular to the d-axis is L3, and the length of the magnet (6) in the same layer in the direction perpendicular to the d-axis is L1. L3 / L1=k3, and k3 decreases along the direction close to the outer circle of the rotor.

6. The rotor structure according to claim 5, characterized in that, At least part of the permanent magnet slot (5) has an air portion at one end of the magnet (6) with a length L3 in the direction perpendicular to the d-axis that is greater than the length L1 of the magnet (6) in the same layer in the direction perpendicular to the d-axis.

7. The rotor structure according to claim 1, characterized in that, The width of the middle portion located at both ends of the magnet (6) increases along the direction away from the magnet (6) to the width at the connection position with the two ends; And / or, the width of the middle portion along the d-axis is w3, and the width of the magnet (6) along the d-axis is w1, where w3 ≥ w1.

8. The rotor structure according to claim 1, characterized in that, The maximum width of the two ends in the direction perpendicular to the q-axis is w6, where the relationship between w2 and w6 satisfies 0.8w2≤w6≤1.1w2.

9. The rotor structure according to claim 8, characterized in that, 0.9w2≤w6≤w2.

10. The rotor structure according to claim 5, characterized in that, The length of the q-axis conductor groove (41) along the q-axis direction is L2, and the width along the direction perpendicular to the q-axis direction is w2. Along the direction away from the q-axis, L2 gradually decreases, and the ratio of L2 to w2, L2 / w2, gradually decreases. At least part of the relationship between the length L2 of the q-axis conductor groove (41) along the q-axis direction and the radius R of the outer circle of the rotor satisfies: 0.15≤L2 / R≤0.

35.

11. The rotor structure according to claim 10, characterized in that, 3≤L2 / w2≤7.

12. The rotor structure according to claim 5, characterized in that, The length of the magnet (6) in the direction perpendicular to the d-axis is L1. The ratio of the length L2 of the q-axis conductor groove (41) in the q-axis direction to the length L1 of the magnet (6) in the same layer in the direction perpendicular to the d-axis is L2 / L1=k2. k2 gradually decreases along the d-axis in the direction close to the outer circle of the rotor.

13. The rotor structure according to claim 12, characterized in that, At least part of the length L2 of the q-axis conductor groove (41) along the q-axis direction is more than 0.8 times the length L1 of the magnet (6) located in the same layer in the direction perpendicular to the d-axis.

14. The rotor structure according to claim 1, characterized in that, The width of the magnet (6) along the d-axis is w1, and the relationship between the width w2 of the q-axis conductor groove (41) along the direction perpendicular to the q-axis and the width w1 of the magnet (6) in the same layer along the d-axis is w2 > w1.

15. The rotor structure according to claim 14, characterized in that, The relationship between w1 and w2 satisfies 1.2≤w2 / w1≤2.

16. The rotor structure according to claim 1, characterized in that, The minimum width of the magnetic channel between two adjacent q-axis conductor slots (41) is q1 in the direction perpendicular to the q-axis, and the minimum width of the magnetic channel between all adjacent q-axis conductor slots (41) on the same side of the q-axis in the direction perpendicular to the q-axis is qz, where q1 < qz.

17. The rotor structure according to claim 1, characterized in that, Under the same pole, the minimum width of the magnetic channel between adjacent q-axis conductor slots (41) in the direction perpendicular to the q-axis is qn, and the minimum width of the magnetic channel between adjacent permanent magnet slots (5) corresponding to the adjacent q-axis conductor slots (41) in the direction of the d-axis is dz, 0.9qn≤dz≤1.35qn.

18. The rotor structure according to claim 1, characterized in that, Under the same pole, the number of the d-axis conductor grooves (42) located on the side of the magnet (6) near the outer circle of the rotor is at least two, and the total length L5 of the d-axis conductor grooves (42) in the direction perpendicular to the d-axis is greater than the length L1 of the magnet (6) in the direction perpendicular to the d-axis.

19. The rotor structure according to claim 18, characterized in that, 1.2≤L5 / L1≤2.

20. The rotor structure according to claim 1, characterized in that, The minimum width of the spacing between adjacent d-axis conductor slots (42) in the direction perpendicular to the d-axis is w4, and the width of the magnet (6) in the direction of the d-axis is w1, where w4 ≥ 2w1; And / or, the relationship between the maximum width w5 of the d-axis conductor groove (42) in the d-axis direction and the width w1 of the magnet (6) in the d-axis direction satisfies w5≥2w1.

21. The rotor structure according to claim 1, characterized in that, The distance between the side of the conductor groove (4) near the outer circle of the rotor and the outer circle of the rotor is d4, and the distance between the side of the q-axis conductor groove (41) near the permanent magnet groove (5) and the permanent magnet groove (5) in the same layer is d5, where 0 < d4 ≤ 1.75 * d, 0 < d5 ≤ 1.75 * d, and d is the thickness of the air gap between the inner circle of the stator and the outer circle of the rotor.

22. The rotor structure according to claim 1, characterized in that, The rotor structure also includes a short-circuit end ring (9), which covers the conductor groove (4) and short-circuit-connects the conductor groove (4). The outer circumference of the short-circuit end ring (9) is circular. The short-circuit end ring (9) includes an inner hole. The inner hole is a polygon formed by straight line segments or a polygon formed by straight line segments and arc segments. Under the same pole, the radial width of the short-circuit end ring (9) is different at different positions in the d-axis to q-axis region. The relationship between the minimum radial width r2 of the short-circuit end ring (9) and the radius R of the outer circle of the rotor satisfies: 0.14≤r2 / R≤0.

3.

23. An electric motor comprising a stator structure (8) and a rotor structure (1), wherein the rotor structure (1) is the rotor structure according to any one of claims 1 to 22, and the stator structure is sleeved outside the rotor structure.

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