Permanent magnet synchronous motor and rotor pressing plate thereof
By using materials with high magnetic permeability and rotor pressure plates with magnetic barriers, the problems of high rotor pressure plate cost and severe magnetic leakage were solved, achieving cost savings and performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2024-11-07
- Publication Date
- 2026-05-08
AI Technical Summary
The rotor plate material of existing permanent magnet synchronous motors is usually stainless steel, which results in high manufacturing and material costs, and also has the problem of serious magnetic leakage.
The rotor pressure plate is made of a material with a magnetic permeability greater than the threshold, and magnetic barriers are set in the leakage magnetic area of the pressure plate body to block the leakage magnetic flux path and reduce the leakage magnetic flux at the rotor end.
It effectively reduces leakage flux at the rotor end, avoids a significant drop in back EMF, ensures torque output under the same current excitation, and reduces manufacturing and material costs.
Smart Images
Figure CN122001124A_ABST
Abstract
Description
[0001] This application is a divisional application of the Chinese invention patent filed on November 7, 2024, with application number 2024115848680 and titled "Permanent Magnet Synchronous Motor and Rotor Plate Thereof". Technical Field
[0002] This disclosure relates to the field of motor technology, and in particular to a permanent magnet synchronous motor and its rotor pressure plate. Background Technology
[0003] Due to their advantages such as high efficiency, high torque density, and high power factor, permanent magnet synchronous motors are widely used in various fields, including industry and household appliances. In a permanent magnet synchronous motor, magnets are inserted into magnet slots inside the rotor core. The rotor clamping plate is fixed to the end of the rotor core by rivets. The rotor clamping plate not only serves to fix the magnets axially but also directly affects the motor's stability, noise control, and thermal management. In existing technology, the rotor clamping plate is typically made of stainless steel. The rotor clamping plate includes the plate body, shaft holes, and rivet holes, requiring specialized processes to manufacture stainless steel clamping plates, resulting in significant manufacturing and material costs. Summary of the Invention
[0004] The technical problem to be solved by this disclosure is to overcome the above-mentioned defects in the prior art and to provide a permanent magnet synchronous motor and its rotor pressure plate.
[0005] This disclosure solves the above-mentioned technical problems through the following technical solution:
[0006] In a first aspect, a rotor pressure plate is provided for use in an electric motor, the electric motor further including a rotor core, the rotor core having at least two permanent magnets; the pressure plate body of the rotor pressure plate is made of a material with a permeability greater than a permeability threshold, the pressure plate body has through holes corresponding to each permanent magnet, the pressure plate body and the rotor core are offset by a target angle in the axial direction, so that a portion of each permanent magnet has an overlapping area with the pressure plate body; the leakage magnetic area of the pressure plate body is provided with a magnetic barrier, the magnetic barrier being used to block the leakage magnetic flux path of the permanent magnets through the rotor pressure plate.
[0007] Optionally, the through-hole is fan-shaped, and the magnetic leakage region includes:
[0008] The first sub-region is located between two adjacent through holes; the shape of the magnetic barrier in the first sub-region is determined according to the shape of the permanent magnet facing the first sub-region.
[0009] And / or, a second sub-region located on one side of the inner arc of the through hole and directly opposite the permanent magnet; the shape of the magnetic barrier in the second sub-region is determined according to the shape of the permanent magnet directly opposite the second sub-region;
[0010] And / or, a third sub-region located on one side of the inner arc of the through hole and directly opposite the region between the two permanent magnets.
[0011] Optionally, the shape of the first magnetic barrier located in the first sub-region is determined based on a first magnetic barrier arc, a second magnetic barrier arc, a third magnetic barrier arc, and a fourth magnetic barrier arc connected end to end in sequence. The first magnetic barrier arc, the second magnetic barrier arc, the third magnetic barrier arc, and the fourth magnetic barrier arc have the following constraint relationship:
[0012] ; ; ;
[0013] Wherein, R1, R2, R3, and R4 are the radii of the first inner arc, the first outer arc, the first magnetic barrier arc, and the second magnetic barrier arc of the first permanent magnet directly opposite the first magnetic barrier, respectively, and the centers of the first inner arc, the first outer arc, the first magnetic barrier arc, and the second magnetic barrier arc are all the first center; a1 is the minimum distance from the first inner arc to the first magnetic barrier arc, a2 is the minimum distance from the first magnetic barrier arc to the second magnetic barrier arc, and a3 is the minimum distance from the first outer arc to the second magnetic barrier arc; h m R5 and R6 are the radii of the second outer arc and the third magnetic barrier arc, respectively, near the through hole of the third magnetic barrier arc, and the centers of the second outer arc and the third magnetic barrier arc are both the second center; b1 is the minimum distance from the second outer arc to the third magnetic barrier arc; R7 and R8 are the radii of the third outer arc and the fourth magnetic barrier arc, respectively, near the through hole of the fourth magnetic barrier arc, and the centers of the fourth magnetic barrier arc and the third outer arc are both the third center; b2 is the minimum distance from the third outer arc to the fourth magnetic barrier arc.
[0014] Optionally, the center of the pressure plate body is further provided with a shaft hole; the angle formed by the center of the shaft hole and the first center and the second center is 30°; and / or, the angle formed by the center of the shaft hole and the first center and the third center is 30°.
[0015] And / or, b1, b2, a1, a3, and a2 all satisfy the minimum distance required for the rotor mechanical strength of the motor.
[0016] Optionally, the center of the pressure plate body is further provided with a shaft hole; the shape of the second magnetic barrier located in the second sub-region is determined according to the fifth, sixth, seventh, and eighth magnetic barrier arcs connected end to end in sequence; the fifth, sixth, seventh, and eighth magnetic barrier arcs have the following constraint relationship:
[0017] ; ; ;
[0018] Among them, R9, R 10 R 11 and R 12 d1 represents the radii of the second inner arc, fourth outer arc, fifth magnetic barrier arc, and sixth magnetic barrier arc of the permanent magnet directly opposite the second magnetic barrier, respectively. The centers of the second inner arc, the fourth outer arc, the fifth magnetic barrier arc, and the sixth magnetic barrier arc are all the center of the fourth arc; d1 is the minimum distance from the second inner arc to the fifth magnetic barrier arc, d2 is the minimum distance from the fifth magnetic barrier arc to the sixth magnetic barrier arc, and d3 is the minimum distance from the fourth outer arc to the sixth magnetic barrier arc; h m R is the thickness of the permanent magnet; 14 R ro Here, are the radius of the seventh magnetic barrier arc and the outer diameter of the rotor core, respectively; the rotor core and the seventh magnetic barrier arc are concentric with the bore shaft; c1 is the minimum distance from the outer edge of the rotor core to the seventh magnetic barrier arc; R 16 R is the radius of the third inner arc of the through hole near the eighth magnetic barrier arc. 17 c3 is the radius of the eighth magnetic barrier arc, and the center of both the eighth magnetic barrier arc and the third inner arc is the fifth center; c3 is the minimum distance from the third inner arc to the eighth magnetic barrier arc.
[0019] Optionally, the second sub-region includes two second magnetic barriers, which are symmetrically distributed about the target axis of symmetry; the target axis of symmetry is the axis of symmetry of the permanent magnet opposite each of the two second magnetic barriers.
[0020] And / or, the distances from the fourth center and the fifth center to the center of the shaft hole are equal;
[0021] And / or, the angle formed by the center of the shaft hole and the fourth and fifth centers is 30°.
[0022] Optionally, the shape of the third magnetic barrier in the third sub-region is determined based on the sequentially connected ninth, tenth, eleventh, and twelfth magnetic barrier arcs; the ninth, tenth, eleventh, and twelfth magnetic barrier arcs have the following constraint relationships:
[0023] ;
[0024] Among them, R 13 is the radius of the ninth magnetic barrier arc, and the center of the ninth magnetic barrier arc is the center of the fourth arc; g1 is the minimum distance from the ninth magnetic barrier arc to the fourth outer arc; The minimum distance between the eleventh magnetic barrier arc and the twelfth magnetic barrier arc; the eleventh magnetic barrier arc is concentric with the shaft hole; the center of the twelfth magnetic barrier arc is the fifth center. The radial distance from the midpoint of the inner arc of the through hole to the edge of the rotor pressure plate;
[0025] The ninth magnetic barrier arc and the tenth magnetic barrier arc are symmetrically distributed about the target axis of symmetry; the target axis of symmetry is the axis of symmetry of the permanent magnets that are directly opposite each of the two second magnetic barriers.
[0026] Optionally, both c1 and c3 satisfy the minimum distance required for the mechanical strength of the motor rotor.
[0027] Optionally, the target angle θ satisfies the following conditions: 0 < θ < 2π and θ ≠ k*π / p, k = 1, 2, ... 2p-1, where p is the number of pole pairs of the motor;
[0028] And / or, the material of the pressure plate body is silicon steel sheet;
[0029] And / or, a magnetic barrier is provided on the rotor core in the area opposite to the rotor pressure plate.
[0030] In a second aspect, a permanent magnet synchronous motor is provided, the permanent magnet synchronous motor including a rotor, the rotor including the rotor pressure plate as described in any one of the first aspects.
[0031] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this disclosure.
[0032] The positive and progressive effects of this disclosure are as follows: In this disclosure, the pressure plate body can be made of any material with a magnetic permeability greater than the magnetic permeability threshold, eliminating the need for specialized processes to manufacture stainless steel pressure plates, thus saving manufacturing and material costs. To avoid severe magnetic leakage at the rotor end of the motor due to the use of a pressure plate body with high magnetic permeability, this embodiment sets up magnetic barriers in the magnetic leakage area of the pressure plate body, thereby effectively reducing magnetic leakage at the rotor end, preventing a significant drop in back electromotive force, and ensuring the motor's torque output under the same current excitation. Attached Figure Description
[0033] Figure 1 A schematic cross-sectional view of a rotor core provided for an exemplary embodiment of this disclosure;
[0034] Figure 2 A cross-sectional schematic diagram of a rotor pressure plate provided for an exemplary embodiment of this disclosure;
[0035] Figure 3 A partial structural schematic diagram of a rotor pressure plate and a rotor core after being axially offset by a target angle, provided as an exemplary embodiment of this disclosure;
[0036] Figure 4 A schematic diagram illustrating the effect of magnetic field distribution in a rotor pressure plate without magnetic barriers, provided as an exemplary embodiment of this disclosure;
[0037] Figure 5 A schematic diagram illustrating the dimensional relationship of the magnetic barriers in a rotor pressure plate, provided as an exemplary embodiment of this disclosure;
[0038] Figure 6 A schematic diagram illustrating the effect of magnetic field distribution in a rotor pressure plate with a magnetic barrier created in the leakage magnetic region L1, as an exemplary embodiment of this disclosure.
[0039] Figure 7 A schematic diagram of the magnetic barrier structure of another rotor pressure plate provided as an exemplary embodiment of this disclosure;
[0040] Figure 8 A schematic diagram of the dimensional relationship of the magnetic barriers of another rotor pressure plate provided for an exemplary embodiment of this disclosure;
[0041] Figure 9 A schematic diagram illustrating the effect of magnetic field distribution in a rotor pressure plate with a magnetic barrier created in the leakage magnetic region L2, provided as an exemplary embodiment of this disclosure;
[0042] Figure 10 A schematic diagram of the structure of a motor including a rotor pressure plate with magnetic barriers in both the leakage magnetic region L1 and the leakage magnetic region L2, provided as an exemplary embodiment of the present disclosure;
[0043] Figure 11 An exemplary embodiment of this disclosure is provided. Figure 9 A comparative schematic diagram showing the no-load back EMF of a motor, a motor including a rotor pressure plate without magnetic barriers, and a motor including a stainless steel rotor pressure plate.
[0044] Figure 12 A schematic diagram of the structure of an electric motor including a rotor pressure plate without magnetic barriers, provided as an exemplary embodiment of this disclosure;
[0045] Figure 13 A schematic diagram of the structure of an electric motor including a rotor pressure plate that creates magnetic barriers, provided as an exemplary embodiment of this disclosure;
[0046] Figure 14 A schematic diagram of the dimensional relationship of the magnetic barriers of another rotor pressure plate provided for an exemplary embodiment of this disclosure;
[0047] Figure 15 A schematic diagram of the dimensional relationship of the magnetic barriers of another rotor plate provided for an exemplary embodiment of this disclosure. Detailed Implementation
[0048] The present disclosure is further illustrated below by way of embodiments, but the present disclosure is not limited to the scope of the embodiments described herein.
[0049] The prefixes such as "first" and "second" used in this disclosure are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this disclosure does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not be construed as an unnecessary limitation. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.
[0050] This disclosure provides a rotor clamping plate applied to a motor. In addition to the rotor clamping plate, the motor also includes a rotor core; see [link to relevant documentation]. Figure 1 The rotor core 11 has at least two magnetic slots, each containing a permanent magnet 12, with adjacent permanent magnets having opposite polarities. In the figure, the blue permanent magnets are N-polarized, and the red permanent magnets are S-polarized.
[0051] In this embodiment, the rotor pressure plate body is made of a material with a magnetic permeability greater than the magnetic permeability threshold. See [link / reference needed]. Figure 2 and Figure 3 The pressure plate body 21 is provided with through holes 22 corresponding to each permanent magnet. The pressure plate body and the rotor core are offset by a target angle in the axial direction so that a part of the permanent magnet overlaps with the pressure plate body, that is, a part of the permanent magnet is blocked by the pressure plate body. The leakage magnetic area of the pressure plate body is provided with a magnetic barrier 23. The magnetic barrier can block the leakage magnetic flux path of the permanent magnet through the rotor pressure plate, thereby suppressing the leakage magnetic flux of the rotor pressure plate.
[0052] Among these, a permeability greater than the permeability threshold, i.e., a higher permeability, is defined. The permeability threshold can be set according to actual needs and will not be elaborated here. The leakage magnetic field region can be determined through experiments and simulations.
[0053] In this embodiment, the pressure plate body can be made of any material with a permeability greater than the permeability threshold, eliminating the need for specialized processes to manufacture stainless steel pressure plates, thus saving manufacturing and material costs. To prevent severe magnetic leakage at the rotor end of the motor due to the use of a pressure plate body with high permeability, this embodiment offsets the pressure plate body and the rotor core by a target angle in the axial direction, and sets magnetic barriers in the magnetic leakage area of the pressure plate body. This effectively reduces magnetic leakage at the rotor end, prevents a significant drop in back EMF, and ensures the motor's torque output under the same current excitation.
[0054] In one embodiment, the pressure plate body is further provided with a shaft hole 24 and a rivet hole 25. The pressure plate body is installed on the rotating shaft of the rotor core through the shaft hole 24 and fixed to the end of the rotor core through the rivet hole 25, thereby playing the role of fixing the permanent magnet in the axial direction, and thus realizing the assembly of the pressure plate body.
[0055] In one embodiment, the same magnetic barriers are provided on the rotor core in the area opposite to the rotor pressure plate. This further improves the effectiveness of suppressing magnetic leakage from the rotor pressure plate.
[0056] The shape of the magnetic barrier can be circular, rectangular, trapezoidal, etc. To achieve the best effect of suppressing magnetic leakage of the rotor pressure plate, the optimal magnetic barrier shape is determined based on the axial overlap area of the permanent magnet and the rotor pressure plate and / or the shape of the permanent magnet.
[0057] Without magnetic barriers, the magnetic fields of the rotor pressure plates are as follows: Figure 4 As shown, due to the high permeability of the rotor pressure plate, the motor exhibits significant magnetic leakage, specifically leakage regions L1 and L2. For leakage region L1, the magnetic flux path is: N pole of the permanent magnet – rotor core – rotor pressure plate – rotor core – S pole of the permanent magnet – N pole of the permanent magnet. For leakage region L2, the magnetic flux path is: N pole permanent magnet – rotor core – rotor pressure plate – rotor core – S pole permanent magnet – rotor core – N pole permanent magnet and N pole permanent magnet – rotor pressure plate – S pole permanent magnet – rotor core – N pole permanent magnet.
[0058] In one embodiment, the magnetic leakage region includes: a first sub-region located between two adjacent through holes and directly opposite the permanent magnet, i.e. Figure 4 The shape of the first magnetic barrier in the first sub-region L1 is determined according to the shape of the permanent magnet facing the first sub-region.
[0059] The first magnetic barrier can suppress the leakage magnetic flux of a single permanent magnet through the rotor pressure plate. The leakage magnetic flux path is: N pole of a single permanent magnet - rotor core - rotor pressure plate - rotor core - S pole of a single permanent magnet - N pole of a single permanent magnet.
[0060] In one embodiment, see Figure 3 and Figure 5 The shape of the first magnetic barrier is determined by the sequentially connected first magnetic barrier arc l1, second magnetic barrier arc l2, third magnetic barrier arc l3, and fourth magnetic barrier arc l4. The first, second, third, and fourth magnetic barrier arcs have the following constraint relationships:
[0061] ; ; ;
[0062] Wherein, R1, R2, R3, and R4 are the radii of the first inner arc, the first outer arc, the first magnetic barrier arc l1, and the second magnetic barrier arc l2 of the first permanent magnet directly opposite the first magnetic barrier, respectively; the centers of the first inner arc, the first outer arc, the first magnetic barrier arc l1, and the second magnetic barrier arc l2 are all the first center O1; a1 is the minimum distance from the first inner arc to the first magnetic barrier arc l1, a2 is the minimum distance from the first magnetic barrier arc l1 to the second magnetic barrier arc l2, and a3 is the minimum distance from the first outer arc to the second magnetic barrier arc l2; h m R5 and R6 are the radii of the second outer arc and the third magnetic barrier arc l3, respectively, which are the through holes near the third magnetic barrier arc. The center of the second outer arc and the third magnetic barrier arc is the second center O2. b1 is the minimum distance from the second outer arc to the third magnetic barrier arc l3. R7 and R8 are the radii of the third outer arc and the fourth magnetic barrier arc l4, respectively, which are the through holes near the fourth magnetic barrier arc l4. The center of the fourth magnetic barrier arc l4 and the third outer arc is the third center O3. b2 is the minimum distance from the third outer arc to the fourth magnetic barrier arc l4.
[0063] Since magnetic leakage mainly occurs at the width h of the magnet. m Within the range, therefore, constraints are set. In other implementations, it is also possible to set... Setting constraints b1>0 and b2>0 ensures that the entire rotor pressure plate is connected and has a certain structural strength, preventing deformation caused by centrifugal force after the rotor rotates.
[0064] Figure 3 , Figure 5 The structure of the rotor pressure plate is illustrated by taking the rotor pressure plate as an example of rotating 90° (target angle) axially upward relative to the rotor core. In actual applications, the target angle can be set according to actual needs.
[0065] In one embodiment, the distances from the first center O1, the second center O2, and the third center O3 to the center O of the shaft hole are equal.
[0066] If the distances from the center of each arc to the center of the shaft hole are not the same, there will be an asymmetrical stress distribution between b1 and b2, which can easily cause deformation of the rotor pressure plate. In this embodiment, the distances from the center of each arc to the center of the shaft hole are set to be the same, so the widths of b1 and b2 are the same. This helps to distribute the stress evenly between b1 and b2 after the rotor starts to rotate, thereby reducing or even avoiding deformation of the rotor pressure plate.
[0067] In one embodiment, ∠O1OO2 = 30°; and / or, ∠O1OO3 = 30°. These angles can be determined according to 360° / number of poles / 2. Setting the two angles equal ensures the symmetry of the left and right magnetic barriers.
[0068] It should be noted that the values of b1, b2, a1, a3, and a2 cannot be too small and must meet the mechanical strength requirements of the rotor. In one embodiment, b1, b2, a1, a3, and a2 all meet the minimum distance required for the mechanical strength of the motor rotor.
[0069] See Figure 6 The figure shows the magnetic field distribution of the rotor pressure plate with the first magnetic barrier when the motor has 9 stator slots, 6 permanent magnet poles, crescent-shaped permanent magnets, 4 rivets, and the rotor pressure plate is rotated 90° counterclockwise relative to the rotor core axis (target angle), and b1=b2=0.5mm, a1=a3=0.5mm, a2=4mm. It can be seen that the leakage magnetic field in the leakage magnetic region L1 is significantly suppressed.
[0070] In one embodiment, the magnetic leakage region includes a second sub-region located on one side of the inner arc of the through-hole and directly opposite the permanent magnet, i.e. Figure 7 In the leakage magnetic region L2, the region L directly opposite the permanent magnet 21 The shape of the second magnetic barrier in the second sub-region is determined based on the shape of the permanent magnet directly opposite the second sub-region.
[0071] The second magnetic barrier can suppress the leakage flux of a single permanent magnet through the rotor pressure plate. The leakage flux path is: N pole of the single permanent magnet - rotor core - rotor pressure plate - rotor core - S pole of the single permanent magnet - N pole of the single permanent magnet.
[0072] In one embodiment, see Figure 7 , Figure 8 The shape of the second magnetic barrier located in the second sub-region is determined by the sequentially connected fifth magnetic barrier arc l5, sixth magnetic barrier arc l6, seventh magnetic barrier arc l7, and eighth magnetic barrier arc l8; the fifth magnetic barrier arc l5, sixth magnetic barrier arc l6, seventh magnetic barrier arc l7, and eighth magnetic barrier arc l8 have the following constraint relationship:
[0073] ; ; ;
[0074] Among them, R9, R 10 R 11 and R 12 d1 represents the radii of the second inner arc, fourth outer arc, fifth magnetic barrier arc l5, and sixth magnetic barrier arc l6 of the permanent magnet directly opposite the second magnetic barrier. The centers of the second inner arc, fourth outer arc, fifth magnetic barrier arc l5, and sixth magnetic barrier arc l6 are all the fourth center O4; d1 is the minimum distance from the second inner arc to the fifth magnetic barrier arc, d2 is the minimum distance from the fifth magnetic barrier arc l5 to the sixth magnetic barrier arc l6, and d3 is the minimum distance from the fourth outer arc to the sixth magnetic barrier arc l6; h mR is the thickness of the permanent magnet; 14 R ro R represents the radius of the seventh magnetic barrier arc l7 and the outer diameter of the rotor core, respectively. The rotor core and the seventh magnetic barrier arc l7 are concentric with the bore shaft at point O; c1 is the minimum distance from the outer edge of the rotor core to the seventh magnetic barrier arc l7; 16 R is the radius of the third inner arc of the through-hole closest to the eighth magnetic barrier arc. 17 c is the radius of the eighth magnetic barrier arc l8, and the center of both the eighth magnetic barrier arc l8 and the third inner arc is the fifth center O5; c3 is the minimum distance from the third inner arc to the eighth magnetic barrier arc l8.
[0075] Since magnetic leakage mainly occurs at the width h of the magnet. m Within the range, therefore, constraints are set. In other implementations, it is also possible to set... Setting constraints c1>0 and c3>0 ensures that the entire rotor pressure plate is connected and has a certain structural strength, preventing deformation caused by centrifugal force after the rotor rotates.
[0076] In one embodiment, the second sub-region includes two second magnetic barriers that are symmetrically distributed about a target axis of symmetry; the target axis of symmetry is the axis of symmetry of the permanent magnet that each of the two second magnetic barriers faces. Figure 7 The middle is composed of the fifth magnetic barrier arc l9 and the sixth magnetic barrier arc l 10 The seventh magnetic barrier arc l 11 And the eighth magnetic barrier arc l 12 The resulting magnetic barrier is another symmetrical magnetic barrier. The two second magnetic barriers in the second sub-region have the same parameters and constraints, differing only in their centers: the fifth magnetic barrier arc l9 and the sixth magnetic barrier arc l. 10 The center of the circle is O6.
[0077] In one embodiment, the magnetic leakage region includes a third sub-region located on one side of the inner arc of the through-hole and directly opposite the region between the two permanent magnets, i.e. Figure 7 In the leakage magnetic region L2, the region L that is not facing the permanent magnet 22 .
[0078] The third magnetic barrier in the third sub-region can suppress the leakage flux of adjacent permanent magnets through the rotor pressure plate. The leakage flux path is N-pole permanent magnet - rotor core - rotor pressure plate - rotor core - S-pole permanent magnet - rotor core - N-pole permanent magnet and N-pole permanent magnet - rotor pressure plate - S-pole permanent magnet - rotor core - N-pole permanent magnet.
[0079] In one embodiment, the shape of the third magnetic barrier is based on the arcs of the ninth magnetic barrier connected end to end. 13 The tenth magnetic barrier arc l 14 Eleventh Magnetic Barrier Arc15 And the twelfth magnetic barrier arc l 16 Confirmed; Ninth magnetic barrier arc l 13 The tenth magnetic barrier arc l 14 Eleventh Magnetic Barrier Arc 15 And the twelfth magnetic barrier arc l 16 It has the following constraints:
[0080] ;
[0081] Among them, R 13 The ninth magnetic barrier arc l 13 The radius of the ninth magnetic barrier arc l 13 The center of the circle is the fourth center; g1 is the ninth magnetic barrier arc l. 13 The minimum distance to the fourth outer arc; For the eleventh magnetic barrier arc l 15 To the twelfth magnetic barrier arc l 16 Minimum distance; Eleventh magnetic barrier arc l 15 Concentric with the shaft hole; Twelfth magnetic barrier arc l 16 The center of each circle is the fifth center O5. It is the radial distance from the midpoint of the inner arc of the through hole to the edge of the rotor pressure plate.
[0082] Ninth Magnetic Barrier Arc l 13 With the tenth magnetic barrier arc l 14 Symmetrical distribution about the target axis of symmetry; the target axis of symmetry is the axis of symmetry of the permanent magnets that are directly opposite each of the two second magnetic barriers.
[0083] In one embodiment, the distances from the fourth center O4 and the fifth center O5 to the center O of the shaft hole are equal. In this embodiment, setting the distance from the center of each arc to the center of the shaft hole to be the same helps to evenly distribute the stress after the rotor starts rotating, thereby reducing or even avoiding deformation of the rotor pressure plate.
[0084] In one embodiment, ∠O4OO5 = 30°; and / or ∠O5OO6 = 30°. These angles can be determined according to 360° / number of poles / 2. Setting the two angles equal ensures the symmetry of the left and right magnetic barriers.
[0085] It should be noted that the values of c1 and c3 cannot be too small and must meet the mechanical strength requirements of the rotor. In one embodiment, both c1 and c3 meet the minimum distance required for the mechanical strength of the motor rotor.
[0086] See Figure 9The figure shows the magnetic field distribution of the rotor pressure plate with the second and third magnetic barriers when the motor has 9 stator slots, 6 permanent magnet poles, crescent-shaped permanent magnets, 4 rivets, and the rotor pressure plate is rotated 90° counterclockwise relative to the rotor core axis (target angle), and d1=d3=0.5mm, d2=4mm, c1=c3=0.6mm, c2=7.5mm, g1=0.2mm. It can be seen that the leakage magnetic field in the leakage magnetic region L2 is significantly suppressed.
[0087] In one embodiment, the magnetic leakage region includes at least two of the first sub-region, the second sub-region, and the third sub-region.
[0088] Figure 10 A schematic diagram of a motor structure is shown. The motor includes a rotor pressure plate that simultaneously opens magnetic barriers in the leakage magnetic regions L1 and L2, and suppresses the leakage magnetic field in the leakage magnetic regions L1 and L2. The magnetic barrier parameters are b1=b2=0.6mm, a1=a3=0.5mm, a2=4mm, d1=d3=0.5mm, d2=4mm, c1=c3=0.6mm, c2=7.5mm, and g1=0.2mm. Figure 11 The figure shows a comparison of the no-load back EMF of the motor under different schemes. Using the open magnetic barrier rotor pressure plate of this embodiment, the effective value of the no-load back EMF of the motor is 54V at a motor speed of 1500rpm. Compared with the rotor pressure plate without magnetic barriers, the effective value of the motor's no-load back EMF is increased by 9.53%; compared with the stainless steel rotor pressure plate, the effective value of the motor's no-load back EMF is reduced by 3.57%.
[0089] In one embodiment, when the rotor pressure plate and the rotor core are offset by an angle in the axial direction, if the magnetic isolation bridge of the rotor pressure plate and the magnetic isolation bridge of the rotor core coincide in the axial direction, then the magnetic isolation bridge of the rotor pressure plate can act as a third magnetic barrier. At this time, the rotor pressure plate can open the first magnetic barrier and / or the second magnetic barrier to suppress the leakage flux path of a single permanent magnet.
[0090] In one embodiment, the pressure plate body is made of silicon steel sheet. Preferably, the silicon steel sheet of the rotor core is used as the pressure plate body, in which case the rotor core and the pressure plate body have the same shape and size. This solution can eliminate the mold cost of the rotor pressure plate, thereby further reducing the cost of the motor.
[0091] It should be noted that the number of silicon steel sheets contained in the pressure plate body can be set according to actual needs. When multiple layers of silicon steel sheets are used, the corresponding magnetic barrier is a multi-layer structure, which can control the distribution of magnetic flux without affecting the direction of magnetic lines of force on other axes, thereby improving the performance of the motor.
[0092] In one embodiment, the target angle θ satisfies the following conditions: 0 < θ < 2π and θ ≠ k*π / p, k = 1, 2, ..., 2p-1, where p is the number of pole pairs of the motor.
[0093] It should be noted that when the target angle is different, the overlap area between the rotor pressure plate and the permanent magnet in the axial direction is also different, and the shape and size of the magnetic barrier also change. However, the shape and size of the magnetic barrier can still be designed according to the magnetic barrier constraint conditions provided in the above embodiments.
[0094] When the rotor pressure plate rotates 72.5° (target angle) axially upwards relative to the rotor core, the motor containing a rotor pressure plate structure without magnetic barriers, as shown... Figure 12 As shown. To suppress rotor end magnetic leakage caused by the rotor pressure plate, a motor containing a rotor pressure plate structure with magnetic barriers is used, such as... Figure 13 As shown. Figure 13 The parameters of the magnetic barrier are b1=b2=0.6mm, a1=a3=1mm, a2=3mm, d1=d3=1mm, d2=3mm, c1=c3=0.6mm, and c2=7.5mm.
[0095] Figure 13 In the diagram, magnetic barrier A is used to suppress leakage flux through the rotor pressure plate on the right side of a single permanent magnet, and magnetic barrier B is used to suppress leakage flux through the rotor pressure plate on the left side of a single permanent magnet. Since the rotor pressure plate rotates 72.5° axially upward relative to the rotor core, the magnetic isolation bridges of the rotor pressure plate and the rotor core overlap axially, so the third magnetic barrier can be omitted. Furthermore, since the magnetic slots of the rotor pressure plate and the right side of the single permanent magnet correspond axially, the magnetic barrier symmetrical to magnetic barrier A can also be omitted.
[0096] Taking the magnetic barrier above the y-axis as an example, the geometric parameter relationship of the magnetic barrier B is as follows: Figure 14 As shown, the constraint relationships are as follows:
[0097] ; ; ;
[0098] Wherein, R1, R2, R3, and R4 are the inner arc, outer arc, and arc l of the permanent magnet, respectively. 17 and arc l 18 The radii of these circles are all centered at O1. a1 is the radius of the arc within the permanent magnet, extending from arc l. 17 The minimum distance, a2 is the arc l 17 to the arc l 18 The minimum distance, a3 is the distance from the outer arc of the permanent magnet to the arc l. 18 The minimum distance. R5 and R6 are the outer arc and arc l of the magnet groove on the left side of the magnetic barrier, respectively. 19The radii of these circles are all centered at O2. b1 is the radius of the outer arc of the magnetic groove on the left side of the magnetic barrier to the arc l. 19 The minimum distance. R7 and R8 are the outer arc and arc l of the magnet slot on the right side of the magnetic barrier on the rotor pressure plate, respectively. 20 The radius of each circle is O3. b2 is the radius of the outer arc of the magnetic groove on the right side of the magnetic barrier to the arc l. 20 The minimum distance.
[0099] Furthermore, the distances from the centers O1, O2, and O3 to the center O are equal. It should be noted that the values of b1 and b2 cannot be too small; they must meet the mechanical strength requirements of the rotor. ∠O1OO2 = 12.5°, ∠O1OO3 = 47.5°. It should be noted that these angles are only illustrative; other angles can be used in other implementations.
[0100] Taking the magnetic barrier above the y-axis as an example, the geometric parameter relationship of magnetic barrier A is as follows: Figure 15 As shown, the constraint relationships are as follows:
[0101] ; ; ;
[0102] Among them, R 18 R 19 R 20 and R 21 These are respectively the inner arc of the permanent magnet, the outer arc of the permanent magnet, and the arc l. 21 and arc l 22 The radius of each circle is O1. d1 is the radius of the arc within the permanent magnet, and the center of each circle is O1. 21 The minimum distance, d2 is the arc l 21 to the arc l 22 The minimum distance, d3, is the distance from the outer arc of the permanent magnet to the arc l. 22 The minimum distance. R 14 For the arc l 23 The radius, R ro Let c1 be the outer diameter of the rotor, and the center of each circle is O. c1 is the distance from the outer diameter of the rotor to the arc l. 23 The minimum distance. R 16 R is the radius of the inner arc of the magnet groove. 17 For the arc l 24 The radius of each circle is O2. c3 is the radius of the inner arc of the magnetic groove to the arc l. 24 The minimum distance.
[0103] use Figure 13The motor shown, which includes a rotor plate with open magnetic barriers, has an effective value of 54V for its no-load back EMF at a motor speed of 1500 rpm. Compared to a rotor plate without open magnetic barriers, the effective value of the motor's no-load back EMF is increased by 9.53%; compared to a stainless steel rotor plate, the effective value of the motor's no-load back EMF is reduced by 3.57%.
[0104] This disclosure also provides a permanent magnet synchronous motor, which includes a stator and a rotor. The rotor includes the rotor pressure plate provided in any of the above embodiments. Specifically, the rotor includes two rotor pressure plates and a rotor core sandwiched between the two rotor pressure plates. The stator includes a stator core and windings disposed on the stator core.
[0105] While specific embodiments of this disclosure have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this disclosure is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this disclosure, but all such changes and modifications fall within the scope of protection of this disclosure.
Claims
1. A rotor pressure plate, characterized in that, The invention is applied to an electric motor, which further includes a rotor core on which at least two permanent magnets are provided; the pressure plate body of the rotor pressure plate is made of a material with a magnetic permeability greater than a magnetic permeability threshold; the leakage magnetic area of the pressure plate body is provided with a magnetic barrier, which is used to block the leakage magnetic flux path of the permanent magnets through the rotor pressure plate; The magnetic barrier comprises multiple magnetic barrier arcs connected end to end, and the multiple magnetic barrier arcs have a constraint relationship; the constraint relationship is determined according to at least one of the following: the range of leakage magnetic field occurrence, the structural strength requirements of the rotor pressure plate, and the mechanical strength of the rotor.
2. The rotor pressure plate according to claim 1, characterized in that, The pressure plate body is provided with through holes corresponding to each permanent magnet, the through holes being fan-shaped, and the magnetic leakage area includes: The first sub-region is located between two adjacent through holes; the shape of the magnetic barrier in the first sub-region is determined according to the shape of the permanent magnet facing the first sub-region. And / or, a second sub-region located on one side of the inner arc of the through hole and directly opposite the permanent magnet; the shape of the magnetic barrier in the second sub-region is determined according to the shape of the permanent magnet directly opposite the second sub-region; And / or, a third sub-region located on one side of the inner arc of the through hole and directly opposite the region between the two permanent magnets.
3. The rotor pressure plate according to claim 2, characterized in that, The shape of the first magnetic barrier located in the first sub-region is determined by a first magnetic barrier arc, a second magnetic barrier arc, a third magnetic barrier arc, and a fourth magnetic barrier arc connected end to end in sequence. The first magnetic barrier arc, the second magnetic barrier arc, the third magnetic barrier arc, and the fourth magnetic barrier arc have the following constraint relationship: ； ； ； Wherein, R1, R2, R3, and R4 are the radii of the first inner arc, the first outer arc, the first magnetic barrier arc, and the second magnetic barrier arc of the first permanent magnet directly opposite the first magnetic barrier, respectively, and the centers of the first inner arc, the first outer arc, the first magnetic barrier arc, and the second magnetic barrier arc are all the first center; a1 is the minimum distance from the first inner arc to the first magnetic barrier arc, a2 is the minimum distance from the first magnetic barrier arc to the second magnetic barrier arc, and a3 is the minimum distance from the first outer arc to the second magnetic barrier arc; h m R5 and R6 are the radii of the second outer arc and the third magnetic barrier arc, respectively, near the through hole of the third magnetic barrier arc, and the centers of the second outer arc and the third magnetic barrier arc are both the second center; b1 is the minimum distance from the second outer arc to the third magnetic barrier arc; R7 and R8 are the radii of the third outer arc and the fourth magnetic barrier arc, respectively, near the through hole of the fourth magnetic barrier arc, and the centers of the fourth magnetic barrier arc and the third outer arc are both the third center; b2 is the minimum distance from the third outer arc to the fourth magnetic barrier arc.
4. The rotor pressure plate according to claim 3, characterized in that, The center of the pressure plate body is also provided with a shaft hole; the angle formed by the center of the shaft hole and the first center and the second center is 30°; and / or, the angle formed by the center of the shaft hole and the first center and the third center is 30°. And / or, b1, b2, a1, a3, and a2 all satisfy the minimum distance required for the rotor mechanical strength of the motor.
5. The rotor pressure plate according to claim 2, characterized in that, The pressure plate body is also provided with a shaft hole at its center; the shape of the second magnetic barrier located in the second sub-region is determined according to the fifth, sixth, seventh, and eighth magnetic barrier arcs connected end to end in sequence; the fifth, sixth, seventh, and eighth magnetic barrier arcs have the following constraint relationship: ； ； ； Among them, R9, R 10 R 11 and R 12 d1 represents the radii of the second inner arc, fourth outer arc, fifth magnetic barrier arc, and sixth magnetic barrier arc of the permanent magnet directly opposite the second magnetic barrier, respectively. The centers of the second inner arc, the fourth outer arc, the fifth magnetic barrier arc, and the sixth magnetic barrier arc are all the center of the fourth arc; d1 is the minimum distance from the second inner arc to the fifth magnetic barrier arc, d2 is the minimum distance from the fifth magnetic barrier arc to the sixth magnetic barrier arc, and d3 is the minimum distance from the fourth outer arc to the sixth magnetic barrier arc; h m R is the thickness of the permanent magnet; 14 R ro Here, R represents the radius of the seventh magnetic barrier arc and the outer diameter of the rotor core, respectively. The rotor core and the seventh magnetic barrier arc are concentric with the hole axis of the rotor pressure plate; c1 is the minimum distance from the outer edge of the rotor core to the seventh magnetic barrier arc; 16 R is the radius of the third inner arc of the through hole near the eighth magnetic barrier arc. 17 c3 is the radius of the eighth magnetic barrier arc, and the center of both the eighth magnetic barrier arc and the third inner arc is the fifth center; c3 is the minimum distance from the third inner arc to the eighth magnetic barrier arc.
6. The rotor pressure plate according to claim 5, characterized in that, The second sub-region includes two second magnetic barriers, which are symmetrically distributed about the target axis of symmetry; the target axis of symmetry is the axis of symmetry of the permanent magnet directly opposite each of the two second magnetic barriers. And / or, the distances from the fourth center and the fifth center to the center of the shaft hole are equal; And / or, the angle formed by the center of the shaft hole and the fourth and fifth centers is 30°.
7. The rotor pressure plate according to claim 5, characterized in that, The shape of the third magnetic barrier in the third sub-region is determined by the sequentially connected ninth, tenth, eleventh, and twelfth magnetic barrier arcs; the ninth, tenth, eleventh, and twelfth magnetic barrier arcs have the following constraint relationships: ； Among them, R 13 is the radius of the ninth magnetic barrier arc, and the center of the ninth magnetic barrier arc is the center of the fourth arc; g1 is the minimum distance from the ninth magnetic barrier arc to the fourth outer arc; The minimum distance between the eleventh magnetic barrier arc and the twelfth magnetic barrier arc; the eleventh magnetic barrier arc is concentric with the shaft hole; the center of the twelfth magnetic barrier arc is the fifth center. The radial distance from the midpoint of the inner arc of the through hole to the edge of the rotor pressure plate; The ninth magnetic barrier arc and the tenth magnetic barrier arc are symmetrically distributed about the target axis of symmetry; the target axis of symmetry is the axis of symmetry of the permanent magnets that are directly opposite each of the two second magnetic barriers.
8. The rotor pressure plate according to claim 7, characterized in that, Both c1 and c3 satisfy the minimum distance required for the mechanical strength of the motor rotor.
9. The rotor pressure plate according to any one of claims 1-8, characterized in that, The pressure plate body and the rotor core are offset by a target angle in the axial direction so that a portion of each permanent magnet overlaps with the pressure plate body. And / or, the target angle θ satisfies the following conditions: 0 < θ < 2π and θ ≠ k*π / p, k = 1, 2, ... 2p-1, p is the number of pole pairs of the motor; And / or, the material of the pressure plate body is silicon steel sheet.
10. A permanent magnet synchronous motor, characterized in that, The permanent magnet synchronous motor includes a rotor, and the rotor includes a rotor pressure plate as described in any one of claims 1-9.