electric machine

Abstract

The motor comprises a rotor pressing plate and a rotor core, the rotor core comprises first silicon steel sheets, and the first silicon steel sheets are provided with magnetic steel grooves with the same layout to accommodate permanent magnets; a pressing plate body of the rotor pressing plate comprises at least one layer of second silicon steel sheets, each layer of second silicon steel sheets is provided with magnetic steel grooves with the same layout as the first silicon steel sheets; and the pressing plate body and the rotor core are staggered by a target angle in the axial direction, so that a partial area of each permanent magnet overlaps with the pressing plate body. In the motor, the pressing plate body of the rotor pressing plate is realized by silicon steel sheets, a special process is not needed to manufacture a stainless steel pressing plate, and manufacturing cost and material cost can be saved.

Description

Technical Field

[0001] This disclosure relates to the field of motor technology, and more particularly to an electric motor. Background Technology

[0002] 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, the permanent magnets are inserted into the magnetic slots inside the rotor core. The rotor plate is fixed to the end of the rotor core by rivets. The rotor plate not only serves to fix the permanent magnets axially but also has a direct impact on the motor's stability, noise control, and thermal management. In existing technologies, the rotor plate of the motor is usually made of stainless steel. The rotor plate includes the plate body, shaft holes, and rivet holes. Specialized processes are required to manufacture the stainless steel plate, resulting in significant manufacturing and material costs. Summary of the Invention

[0003] The technical problem to be solved by this disclosure is to overcome the above-mentioned defects in the prior art and to provide an electric motor.

[0004] This disclosure solves the above-mentioned technical problems through the following technical solution:

[0005] An electric motor includes a rotor pressure plate and a rotor core. The rotor core includes a first silicon steel sheet with identically arranged magnetic slots to accommodate permanent magnets. The rotor pressure plate has a pressure plate body including at least one layer of second silicon steel sheets, each layer of second silicon steel sheets having magnetic slots arranged identically to the first silicon steel sheets. 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.

[0006] 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.

[0007] Optionally, the target angle θ satisfies the following conditions: 0 < θ < 2π and θ = n * π / 2 / p, n = 1, 3…4p-1, where p is the number of pole pairs of the motor.

[0008] Optionally, both the first silicon steel sheet and the second silicon steel sheet are provided with rivet holes and shaft holes. The rivet holes are located between the magnet groove and the shaft hole, and after the target angle is offset, there is at least one rivet hole on the pressure plate body that corresponds to the rivet hole on the rotor core.

[0009] Optionally, the number of rivet holes is even, and each rivet hole is evenly distributed along the circumference of the shaft hole.

[0010] Optionally, at least some of the rivet holes are located on a first target axis of symmetry; the first target axis of symmetry is the axis of symmetry of the two magnet slots closest to the rivet holes;

[0011] And / or, at least part of the rivet hole's center is located on the second target axis of symmetry; the second target axis of symmetry is the axis of symmetry of the magnet groove closest to the rivet hole.

[0012] Optionally, the rotor pressure plate includes six rivet holes, which are evenly distributed along the circumference of the shaft hole, and the centers of two rivet holes are located on a first target axis of symmetry; the first target axis of symmetry is the axis of symmetry of the two magnet slots closest to the rivet holes; the centers of four rivet holes are located on a second target axis of symmetry; the second target axis of symmetry is the axis of symmetry of the magnet slot closest to the rivet holes.

[0013] Optionally, the minimum distance between the rivet hole and its nearest magnet slot satisfies the minimum distance required for the rotor mechanical strength of the motor;

[0014] And / or, the minimum distance between the rivet hole and the shaft hole satisfies the minimum distance required for the rotor's mechanical strength.

[0015] Optionally, the permanent magnet may have at least one of the following shapes: crescent-shaped, straight, V-shaped, double V-shaped, U-shaped, or ▽-shaped.

[0016] Optionally, the magnetic leakage area of ​​the pressure plate body is provided with a magnetic barrier.

[0017] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this disclosure.

[0018] The positive and progressive effects of this disclosure are as follows: In this disclosure, the pressure plate body of the rotor pressure plate is made of silicon steel sheet, eliminating the need for a special process to manufacture stainless steel pressure plates, which can save manufacturing and material costs. Attached Figure Description

[0019] Figure 1 A schematic diagram of a rotor core with a crescent-shaped permanent magnet provided as an exemplary embodiment of this disclosure;

[0020] Figure 2 A schematic diagram of a rotor pressure plate with a crescent-shaped magnet slot provided as an exemplary embodiment of this disclosure;

[0021] Figure 3 A schematic diagram of the structure of a rotor core and a rotor pressure plate after being stacked in an exemplary embodiment of this disclosure;

[0022] Figure 4 A schematic diagram of the structure of an electric motor provided as an exemplary embodiment of this disclosure;

[0023] Figure 5 A schematic diagram of another structure with a rotor core and rotor pressure plate overlapping, provided as an exemplary embodiment of this disclosure;

[0024] Figure 6 A schematic diagram of a rotor core with a linear permanent magnet provided as an exemplary embodiment of this disclosure;

[0025] Figure 7 A schematic diagram of a rotor pressure plate with a straight magnetic groove provided as an exemplary embodiment of this disclosure;

[0026] Figure 8 A schematic diagram of another structure with a rotor core and rotor pressure plate overlapping, provided as an exemplary embodiment of this disclosure;

[0027] Figure 9 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;

[0028] Figure 10 A schematic diagram of the magnetic barrier structure of a rotor pressure plate provided as an exemplary embodiment of this disclosure;

[0029] Figure 11 A schematic diagram illustrating the dimensional relationship of the magnetic barriers in a rotor pressure plate, provided as an exemplary embodiment of this disclosure;

[0030] Figure 12 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.

[0031] Figure 13 A schematic diagram of the magnetic barrier structure of another rotor pressure plate provided as an exemplary embodiment of this disclosure;

[0032] Figure 14 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;

[0033] Figure 15 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;

[0034] Figure 16 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.

[0035] Figure 17A 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;

[0036] Figure 18 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;

[0037] Figure 19 A schematic diagram of the magnetic barrier structure of another rotor pressure plate provided as an exemplary embodiment of this disclosure;

[0038] Figure 20 A schematic diagram of the magnetic barrier structure of another rotor pressure plate provided as an exemplary embodiment of this disclosure. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] This disclosure provides an embodiment of a motor, see [link to embodiment]. Figure 1 and Figure 2 The motor includes a rotor core 11 and a rotor pressure plate 21. The rotor core 11 includes a first silicon steel sheet with identically arranged magnetic slots to accommodate permanent magnets 12. The polarities of adjacent permanent magnets are opposite. In the figure, the blue permanent magnets are N-polarity and the red permanent magnets are S-polarity. The pressure plate 21 includes at least one layer of second silicon steel sheets, each layer of which has magnetic slots 211 arranged identically to the first silicon steel sheets. 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, thereby allowing the pressure plate body to fix the permanent magnets.

[0042] from Figure 1 and Figure 2 As can be seen from the diagram, the rotor core and rotor pressure plate are completely identical in this embodiment, including structural parameters and materials. Both the rotor pressure plate and the rotor core are made of silicon steel sheets, and both are manufactured by stamping using rotor core molds, which saves on the stamping molds for the rotor pressure plate.

[0043] It should be noted that the number of silicon steel sheets contained in the rotor pressure plate can be set according to actual needs, and can be set to 1 layer, 2 layers, 3 layers, or even more.

[0044] In this embodiment, the rotor pressure plate body is made of silicon steel sheet, eliminating the need for a special process to manufacture stainless steel pressure plates, thus saving manufacturing and material costs.

[0045] In one embodiment, both the rotor pressure plate and the rotor core are provided with shaft holes 212, magnet slots 211 and rivet holes 213, and the magnet slots 211 are evenly distributed on the circumference of the rotor pressure plate / rotor core.

[0046] The permanent magnet included in the motor of this embodiment can be a permanent magnet of different shapes. The shape of the permanent magnet includes at least one of the following: crescent / fan-shaped, straight, V-shaped, double V-shaped, U-shaped, and ▽-shaped.

[0047] In one embodiment, the target angle θ in which the pressure plate body and the rotor core are axially staggered 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.

[0048] Preferably, θ = n*π / 2 / p, n = 1, 3…4p-1, where p is the number of pole pairs of the motor.

[0049] In one embodiment, the rivet hole is located between the magnet slot and the shaft hole, and after the target angle is offset, there is at least one rivet hole on the pressure plate body that corresponds to the rivet hole on the rotor core, so that the rotor pressure plate can be fixed to the end of the rotor core through the rivet hole and rivet, thereby playing the role of fixing the permanent magnet in the axial direction.

[0050] For example, after the rotor platen rotates by an angle θ, at least q rivet holes on the rotor platen and rotor core will completely coincide in the axial direction, allowing at least q rivets to secure the rotor platen and rotor core. Specifically, when the rotor platen rotates by 90°, the number of pole pairs p of the motor is odd, and q is 2, the four rivet holes on the rotor core coincide with the four rivet holes on the rotor platen, allowing four rivets to connect the rotor core and rotor platen.

[0051] In one embodiment, the number of rivet holes is an even number, and each rivet hole is evenly distributed along the circumference of the shaft hole.

[0052] For example, the number of rivet holes is 2q, where q ≥ 2. Two rotor cores are rotated axially clockwise or counterclockwise by θ (0 < θ < 2π and θ ≠ k*π / p, k = 1, 2, ... 2p-1) as rotor pressure plates. In this case, the rotor pressure plates and rotor cores have at least q rivet holes that completely overlap, and the rotor pressure plates and rotor cores can be fixed by at least q rivets.

[0053] In one embodiment, the number of rivet holes is 2q, where the minimum distance from each of the q rivet holes to its two nearest magnet slots must be no less than d1, and the minimum distance from each rivet hole to the shaft hole must be no less than d2, where d1 and d2 are the minimum distances required to satisfy the rotor's mechanical strength. The positions of the remaining q rivet holes are obtained by rotating the aforementioned q rivet holes counterclockwise or clockwise by a mechanical angle θ along the circumference, where the preferred value of θ is n*π / 2 / p, n=1,3…4p-1. Similarly, the minimum distance from the remaining q rivet holes to their two nearest magnet slots must be no less than d3, and the minimum distance from the remaining q rivet holes to the shaft hole must be no less than d4, where d3 and d4 are the minimum distances required to satisfy the rotor's mechanical strength.

[0054] In one embodiment, at least some of the rivet holes are centered on a first target axis of symmetry; the first target axis of symmetry is the axis of symmetry of the two magnet slots closest to the rivet holes.

[0055] In one embodiment, at least part of the rivet hole's center is located on a second target axis of symmetry; the second target axis of symmetry is the axis of symmetry of the magnet groove closest to the rivet hole.

[0056] From the perspective of the symmetry of the motor rotor magnetic circuit, the center position of the q rivet holes is preferably between two magnetic steel slots corresponding to adjacent permanent magnets of different polarities (the first target symmetry axis). Furthermore, based on this, the remaining q rivet holes are obtained by rotating the aforementioned q rivet holes counterclockwise or clockwise by a mechanical angle θ along the circumferential direction, and the center position of the remaining q rivet holes is on the center line of the magnetic steel slot (the second target symmetry axis).

[0057] by Figure 1 Taking the rotor core shown as an example, M1, M2, and M3 are rivet holes, located on the center line (first target symmetry axis) of the magnetic steel slots where adjacent permanent magnets of different polarities are located. Their minimum distance from the adjacent magnetic steel slots is d1, and their minimum distance from the shaft hole is d2. M1, M2, and M3 are obtained by rotating the rotor core and rotor pressure plate counterclockwise by 30° (n=1). They are located on the center line (second target symmetry axis) of the magnetic steel slots, with their minimum distance from the magnetic steel slots being d3 and their minimum distance from the shaft hole being d4.

[0058] and Figure 1 Correspondingly, see Figure 2 The rivet holes M1, M2, and M3 on the rotor pressure plate correspond exactly to the rivet holes m1, m2, and m3 on the rotor core, respectively. At this point, the rotor pressure plate overlaps with the permanent magnet in the axial direction, meaning the rotor pressure plate can block part of the permanent magnet, thus fixing it in place. (See also...) Figure 3The rotor pressure plate and rotor core can be axially fixed by three rivets 31, thus fixing the permanent magnet axially. Understandably, q and its target angle can also take other values.

[0059] Figure 4 The diagram shows the structure of a motor with q=2, 4 rivet holes, and 2 rivets.

[0060] Figure 5 The diagram shows a partial structural schematic of a motor with a target angle of 90° and a crescent-shaped permanent magnet. The target angle of 90° means that the pressure plate body and the rotor core are offset by 90° axially. At this angle, the rivet holes M1 and M2 on the pressure plate body correspond exactly to the rivet holes m1 and m2 on the rotor core, respectively. In this configuration, the pressure plate body can partially obstruct the permanent magnet in the axial direction. The rotor pressure plate and rotor core are axially fixed using two rivets, thus fixing the permanent magnet in the axial direction.

[0061] In other implementations, to enhance the fixing effect of the rotor pressure plate, two or more rivets can be added to fix the rotor pressure plate and the rotor core.

[0062] In one embodiment, the rotor pressure plate includes six rivet holes, which are evenly distributed along the circumference of the shaft hole, and the centers of two rivet holes are located on a first target axis of symmetry; the first target axis of symmetry is the axis of symmetry of the two magnet slots closest to the rivet holes; the centers of four rivet holes are located on a second target axis of symmetry; the second target axis of symmetry is the axis of symmetry of the magnet slot closest to the rivet holes.

[0063] In one embodiment, if p is an odd number, the rotor pressure plate includes four rivet holes, which are evenly distributed around the circumference. The center of two rivet holes is located between two adjacent magnetic slots corresponding to permanent magnets of different polarities (first target axis of symmetry). The center of two rivet holes is preferably located on the center line of the magnetic slot (second target axis of symmetry).

[0064] Figure 6-8 The diagram shows a partial structure of a motor with a rotor core in the shape of a straight line for permanent magnets, a rotor pressure plate in the shape of a straight line for magnetic steel slots, and the pressure plate body and the rotor core being offset by 90° in the axial direction. The motor in the diagram has 4 poles and 6 slots, i.e., p=2, and the number of rivet holes is 4, i.e., q=2, and the number of rivets is 2. Figure 6 M1 and M2 are rivet holes, located on the center line of the magnetic steel grooves where adjacent permanent magnets of different polarities are located. The minimum distance between them and the adjacent magnetic steel groove is d1, and the minimum distance from them and the shaft hole is d2. m1 and m2 are obtained by rotating M1 and M2 counterclockwise by 45° (n=1) mechanical angle. They are located on the center line of the magnetic steel groove, and the minimum distance between them and the magnetic steel groove is d3, and the minimum distance from them and the shaft hole is d4. Figure 7 The rotor pressure plate and Figure 6 The rotor core shown is 45° out of axial direction. The rivet holes M1 and M2 correspond exactly to the rivet holes m1 and m2 of the rotor core, respectively. At this time, the rotor pressure plate can block the permanent magnet in the axial direction. The rotor pressure plate and the rotor core can be fixed in the axial direction by two rivets, thereby fixing the permanent magnet in the axial direction.

[0065] In one embodiment, the leakage magnetic region of the pressure plate body is provided with a magnetic barrier, which 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.

[0066] In this embodiment, a magnetic barrier is set in the leakage magnetic area of ​​the pressure plate body, which can effectively reduce the leakage magnetic field at the rotor end, avoid a significant drop in back electromotive force, and ensure the torque output of the motor under the same current excitation.

[0067] 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.

[0068] Without magnetic barriers, the magnetic fields of the rotor pressure plates are as follows: Figure 15 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.

[0069] 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 15 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.

[0070] 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.

[0071] In one embodiment, see Figure 16 and Figure 17The 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:

[0072] ; ; ;

[0073] 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.

[0074] 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.

[0075] Figure 16 , Figure 17 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.

[0076] 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.

[0077] 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 on 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.

[0078] In one embodiment, ∠O1OO2 = 30°; and / or ∠O1OO3 = 30°; the above angles can be determined according to 360° / number of poles / 2, and setting the two angles to be equal can make the left and right magnetic barriers symmetrical.

[0079] 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.

[0080] See Figure 18 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.

[0081] 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 19 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.

[0082] 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.

[0083] In one embodiment, see Figure 19 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:

[0084] ; ; ;

[0085] 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 m R 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.

[0086] 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.

[0087] 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 19 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.

[0088] 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 19 In the leakage magnetic region L2, the region L that is not facing the permanent magnet 22 .

[0089] 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.

[0090] 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 Arc 15 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:

[0091] ;

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] See Figure 20 The 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.

[0098] 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.

[0099] Figure 15 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 16 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%.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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. Preferably, θ = n*π / 2 / p, n = 1, 3, ..., 4p-1.

[0104] 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.

[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. An electric motor, characterized in that, The motor includes a rotor pressure plate and a rotor core. The rotor core includes a first silicon steel sheet with identically arranged magnetic slots to accommodate permanent magnets. The rotor pressure plate body includes at least one layer of second silicon steel sheets, each layer of second silicon steel sheets having magnetic slots arranged identically to the first silicon steel sheets. 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. The leakage magnetic area of ​​the pressure plate body is provided with a first magnetic barrier, which is used to suppress leakage magnetic flux from a single permanent magnet passing through the rotor pressure plate. The shape of the first magnetic barrier is determined by the sequentially connected first, second, third, and fourth magnetic barrier arcs. The first, second, third, and fourth magnetic barrier arcs have the following constraint relationships: ； ； ； 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 permanent magnet directly opposite the first magnetic barrier, respectively; the center of the first inner arc, the first outer arc, the first magnetic barrier arc, and the second magnetic barrier arc is the first center O1; 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, of the through hole 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. R7 and R8 are the radii of the third outer arc and the fourth magnetic barrier arc, respectively, of the through hole near the fourth magnetic barrier arc. The center of the fourth magnetic barrier arc 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.

2. The motor according to claim 1, characterized in that, 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.

3. The motor according to claim 1, characterized in that, The target angle θ satisfies the following conditions: 0 < θ < 2π and θ = n * π / 2 / p, n = 1, 3…4p-1, where p is the number of pole pairs of the motor.

4. The motor according to any one of claims 1-3, characterized in that, Both the first silicon steel sheet and the second silicon steel sheet are provided with rivet holes and shaft holes. The rivet holes are located between the magnet groove and the shaft hole. After the target angle is offset, there is at least one rivet hole on the pressure plate body that corresponds to the rivet hole on the rotor core.

5. The motor according to claim 4, characterized in that, Both the first silicon steel sheet and the second silicon steel sheet include a first set of rivet holes and a second set of rivet holes. The first set of rivet holes and the second set of rivet holes contain the same number of rivet holes. At least two rivet holes in the first set of rivet holes are evenly distributed along the circumference, and at least two rivet holes in the second set of rivet holes are evenly distributed along the circumference. After the first silicon steel sheet and the second silicon steel sheet are overlapped by a target angle, the first set of rivet holes on the first silicon steel sheet coincides with the second set of rivet holes on the second silicon steel sheet.

6. The motor according to claim 4, characterized in that, At least some of the rivet holes are centered on the first target axis of symmetry; the first target axis of symmetry is the axis of symmetry of the two magnetic grooves closest to the rivet holes; And / or, at least part of the rivet hole's center is located on the second target axis of symmetry; the second target axis of symmetry is the axis of symmetry of the magnet groove closest to the rivet hole.

7. The motor according to claim 4, characterized in that, The rotor pressure plate includes 6 rivet holes, of which 3 rivet holes are evenly distributed along the circumference of the shaft hole, and the center of the 3 rivet holes is located on a first target axis of symmetry; the first target axis of symmetry is the axis of symmetry of the two magnet slots closest to the rivet holes; the center of the 3 rivet holes is located on a second target axis of symmetry; the second target axis of symmetry is the axis of symmetry of the magnet slot closest to the rivet holes.

8. The motor according to claim 4, characterized in that, The minimum distance between the rivet hole and its nearest magnet slot satisfies the minimum distance required for the mechanical strength of the motor rotor; And / or, the minimum distance between the rivet hole and the shaft hole satisfies the minimum distance required for the rotor's mechanical strength.

9. The motor according to any one of claims 1-3 and 5-8, characterized in that, The permanent magnet has at least one of the following shapes: crescent-shaped, straight, V-shaped, double V-shaped, U-shaped, and ▽-shaped.

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