A permanent magnet motor

Abstract

The present invention relates to the field of permanent magnet motors and discloses a permanent magnet motor comprising a housing, a stator core, and a rotor core. The stator core is arranged circumferentially along the inner wall of the housing, and the rotor core is mounted within a space enclosed by the stator core. The rotor core comprises at least two fully continuous bridge lamination stacks and at least one semi-continuous bridge lamination stack. The laminations in the fully continuous bridge lamination stacks include a plurality of fully continuous bridge laminations connected to a first central connecting bridge and distributed circumferentially, and the laminations in the semi-continuous bridge lamination stacks include at least one circumferentially separated lamination disconnected from a second central connecting bridge. The fully continuous bridge lamination stacks and the semi-continuous bridge lamination stacks are stacked axially, with each semi-continuous bridge lamination stack located between two fully continuous bridge lamination stacks, so that adjacent sectors of the rotor core are asymmetrical. The present invention can improve the power density of the motor.

Description

[0001] This application is a divisional application with the application date of "2018.11.30", application number "201811459899.8", and application name "A high power density permanent magnet motor". Technical Field

[0002] The present invention relates to the field of permanent magnet motors, and in particular to a permanent magnet motor. Background Art

[0003] Traditional brushless DC motors use surface-mounted magnetic tiles or internal radially magnetized steel structures, resulting in low power density. Due to cost constraints, a tangentially magnetized parallel magnetic circuit structure is used to increase the magnetic flux per pole. However, this existing tangentially magnetized structure still suffers from high magnetic flux leakage, limiting motor performance improvements.

[0004] Patent CN201611226568.0 designs a rotor core with at least one tooth sector disconnected from the rotor collar, and at least one tooth sector connected to the shaft collar. This suppresses magnetic flux leakage near the axis. The rotor core shaft collar is provided with a positioning protrusion on the outside for positioning and supporting the permanent magnet. Analysis shows that since the disconnected tooth sectors of the rotor in this solution have no fixed support components in the axial direction, the axial structural strength is poor, which is not conducive to large-scale production. At the same time, the positioning protrusions used to support and position the permanent magnets will generate self-linkage leakage, reducing the power density of the motor and not conducive to improving performance.

[0005] On the other hand, due to the increased power density of internally tangentially magnetized motors, the stator core is prone to saturation, resulting in high core losses and reduced motor efficiency. At the same time, the enhanced electromagnetic force waves lead to increased vibration and noise. Existing technologies use methods such as slanted poles and skewed slots to suppress vibration and noise, but these methods increase the difficulty of the manufacturing process and increase production time. Patent CN201320738896.4 designs a stator core with a curved bar shape. This solution extends the teeth inward from the stator annular yoke, forming a wire-embedded slot between two adjacent stator teeth. This stator has a balanced magnetic circuit, moderately even magnetic flux density, reduces local saturation, is simple to manufacture, and has high production efficiency. However, the above patent only relies on parameters such as the stator slot width, tooth width, and yoke width to average the magnetic flux density, failing to consider the impact of the stator shape and structure on the motor's magnetic field and losses. It is not suitable for high-power-density motor structures. It also does not consider reducing motor vibration and noise through a combination of the stator core and the housing, but does not provide a structure that can comprehensively consider power density and suppress vibration and reduce noise.

[0006] Therefore, there is an urgent need for a permanent magnet brushless DC motor with simple process, reliable structure, high power density, low vibration and noise that can be suitable for large-scale production. Summary of the Invention

[0007] In order to overcome the deficiencies in the prior art, the present invention aims to provide a permanent magnet motor that can simplify the production process while improving the structural strength and power density.

[0008] In order to solve the above-mentioned technical problems of the present invention, the present invention provides a permanent magnet motor, comprising a casing, a stator core and a rotor core; the stator core is arranged circumferentially along the inner wall of the casing, and the asymmetric hybrid rotor core is installed in the space surrounded by the stator core; the rotor core comprises at least two full-bridge lamination groups and at least one half-bridge lamination group, wherein the laminations in the full-bridge lamination group comprise a first central connecting bridge and a plurality of full-bridge punchings connected to the first central connecting bridge and distributed circumferentially, and the laminations in the half-bridge lamination group comprise a second central connecting bridge and at least one separate punching disconnected from the second central connecting bridge and distributed circumferentially, and the full-bridge lamination group and the half-bridge lamination group are stacked axially so that each half-bridge lamination group is located between two full-bridge lamination groups to make adjacent sectors of the rotor core asymmetric.

[0009] Preferably, the fully connected bridge lamination group includes multiple fully connected bridge laminations, and adjacent fully connected bridge laminations are overlapped and stacked; the semi-connected bridge lamination group includes multiple semi-connected bridge laminations, and adjacent semi-connected bridge laminations are overlapped and stacked.

[0010] Preferably, the stator core is surrounded by a plurality of T-shaped tooth yokes, the outer surface of each T-shaped tooth yoke is parallel to the bottom of the stator slot, the boundary surface between the tooth portion and the yoke portion of the T-shaped tooth yoke is perpendicular, and the number of T-shaped tooth yokes is equal to the number of motor slots.

[0011] Preferably, each of the T-shaped tooth yokes is provided with two inner and outer rivet points of different sizes, and the diameter of the outer rivet point is greater than the diameter of the inner rivet point.

[0012] Preferably, the outer boundary of the stator core is a regular polygonal structure; the stator core and the casing are in contact at the connection points of each T-tooth yoke to form a contact domain, and the gap where the stator core and the casing are not in contact is formed by injecting filling material to form a filling domain.

[0013] Preferably, the fully-connected bridge-type laminations include a plurality of fully-connected bridge punchings, and a support bridge is provided between adjacent fully-connected bridge punchings; among two adjacent fully-connected bridge punchings, one protrudes radially outward to form a wide magnetic bridge, and the other protrudes radially outward to form a narrow magnetic bridge, and the width of the wide magnetic bridge is greater than the width of the narrow magnetic bridge.

[0014] Preferably, the semi-connected bridge type laminations include multiple semi-connected bridge punches and multiple separation punches, and a separation punch is provided between two adjacent semi-connected bridge punches, and the separation punch does not contact the semi-connected bridge punch; multiple semi-connected bridge punches are provided with a partition type support bridge between each two; the semi-connected bridge punches have a narrow magnetic bridge, and a partition type wide magnetic bridge is provided on the first center connecting bridge, and the width of the partition type wide magnetic bridge is greater than the width of the narrow magnetic bridge.

[0015] Preferably, within at least one laminated layer, adjacent wide magnetic bridges and narrow magnetic bridges have different lengths, and each extends radially outward to form a first sector.

[0016] Preferably, permanent magnets are placed in the slots between adjacent sectors, the polarities of the permanent magnets in two adjacent slots are different, and the corresponding first center connecting bridges in the slots protrude radially outward to form the support bridge; the support bridge is in contact with the permanent magnets.

[0017] Preferably, in at least one laminated layer, the second central connecting bridge extends radially outward to form the narrow magnetic bridge;

[0018] Each of the narrow magnetic bridges extends radially outward to form a second sector; the narrow magnetic bridge is connected to the second sector, and the partition-type wide magnetic bridge is disconnected from the second sector.

[0019] Preferably, the areas of two adjacent second sectors are different.

[0020] Preferably, permanent magnets are placed in the slots between adjacent second sectors, the polarities of the permanent magnets in two adjacent slots are different, and the corresponding second center connecting bridges in the slots extend radially outward to form a slot bottom protrusion; the slot bottom protrusion is separated from the permanent magnets.

[0021] Preferably, the outer arc surface of each of the fully connected bridge punching sheets includes multiple segments of splines for reducing torque fluctuations; the splines at least include an arc segment main spline and straight segment splines arranged on both sides of the arc segment main spline.

[0022] Preferably, the splines include a main arc segment spline, arc segment splines arranged on both sides of the main arc segment spline, and straight line segment splines arranged outside the two arc segment splines.

[0023] Preferably, the outer arc surface of each of the semi-bridge punches and each of the separation punches includes multiple segments of splines for reducing torque fluctuations; the splines at least include an arc segment main spline and straight segment splines arranged on both sides of the arc segment main spline; preferably, the splines include an arc segment main spline, arc segment splines arranged on both sides of the arc segment main spline and straight segment splines arranged on the outside of the two arc segment splines.

[0024] This invention simplifies the motor production process and improves its structural strength. By designing a partitioned support bridge and a partitioned wide magnetic bridge, the motor rotor's structural strength is significantly enhanced. Furthermore, the semi-connected bridge laminations ensure that at least half of each rotor core lamination is connected to the sleeve, facilitating positioning during large-scale production.

[0025] The present invention significantly reduces self-linkage magnetic flux leakage at the bottom of the rotor slots, thereby increasing the air gap flux. The T-tooth yoke stator structure reduces motor saturation and maximizes the flux per pole. A comparison of the back EMF coefficient of the motor structure of the present invention with that of a conventional full-bridge motor structure shows a significant improvement. When the motor is running under heavy load, the torque-current curve exhibits excellent linearity and avoids saturation, thereby improving motor performance.

[0026] The five-segment spline rotor structure reduces back-EMF harmonic distortion and enhances the sinusoidality of the air-gap magnetic field, thereby reducing tangential torque pulsation and radial vibration. Furthermore, a T-shaped tooth yoke structure with a filler region between the stator and the housing reduces vibration transmission between the stator and the housing, ultimately reducing vibration and noise.

[0027] Reducing self-linkage magnetic flux leakage at the bottom of the rotor slots, thereby increasing power density, ensures high sinusoidality of the air gap magnetic field, and significantly improves the back EMF coefficient. This invention can simplify the motor's production process and improve its structural strength. As can be seen from the motor structure, reducing self-linkage magnetic flux leakage at the bottom of the rotor slots, thereby increasing power density, ensures high sinusoidality of the air gap magnetic field, and significantly improves the back EMF coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0029] Figure 2 is a schematic structural diagram of a rotor core in one embodiment of the present invention;

[0030] Figure 3 1 is a schematic structural diagram of a T-shaped tooth yoke according to an embodiment of the present invention;

[0031] Figure 4 1 is a schematic diagram of the structure of a stator assembly in one embodiment of the present invention;

[0032] Figure 5 1 is a schematic structural diagram of a semi-connected bridge-type lamination according to an embodiment of the present invention;

[0033] Figure 6 1 is a schematic structural diagram of a fully connected bridge-type lamination according to an embodiment of the present invention;

[0034] FIG7( a ) is a diagram showing the self-linkage leakage magnetic field distribution of the slot bottom of a full-bridge-connected rotor in the prior art;

[0035] FIG7 (b) is a partial enlarged view of the portion circled in FIG7 (a);

[0036] FIG8( a ) is a diagram showing the self-linkage magnetic flux leakage distribution at the bottom of a slot of a bridge-type rotor without partition support in the prior art;

[0037] FIG8 (b) is a partial enlarged view of the circled portion in FIG8 (a);

[0038] FIG9( a ) is a diagram showing the self-linkage magnetic flux leakage distribution at the bottom of the slot of the partition support bridge rotor of the present invention;

[0039] FIG9 (b) is a partial enlarged view of the portion circled in FIG9 (a);

[0040] Figure 10 This is a comparison curve of the self-linkage leakage coefficient at the bottom of the slot near the axis of three motors with different structures;

[0041] Figure 11 Schematic diagram of the space inside the stator slot of a regular polygonal T-shaped tooth yoke according to one embodiment of the present invention;

[0042] Figure 12 This is a schematic diagram of the space inside the stator slot of the traditional structure;

[0043] Figure 13 Schematic diagram of the distribution of the splines of each segment of a five-segment spline rotor punching in one embodiment of the present invention;

[0044] Figure 14 is the no-load back EMF harmonic content of an embodiment of the present invention;

[0045] Figure 15 is a schematic diagram of the exploded structure of the rotor core in one embodiment of the present invention;

[0046] Figure 16 Schematic diagram of the structure of a semi-connected bridge-type lamination stack in one embodiment of the present invention.

[0047] Description of Reference Numerals

[0048] Housing 1;

[0049] stator core 2; contact area 22; filling area 23;

[0050] T-shaped tooth yoke 21; yoke portion 211; stator slot bottom 2111; bending point 2112; tooth portion 212; oblique shoulder tooth crown slot 2121; outer rivet point 213; inner rivet point 214;

[0051] Rotor core 3;

[0052] Fully connected bridge lamination set 31; fully connected bridge punching 311; outer arc surface 3111; plastic-coated through hole 3112; rivet point 3113; first central connecting bridge H1; support bridge 312; wide magnetic bridge 313; narrow magnetic bridge 314;

[0053] Semi-connected bridge lamination set 32; semi-connected bridge punch 321; outer arc surface 3211 of semi-connected bridge punch; plastic-coated through hole 3212 of semi-connected bridge punch; rivet point 3213 of semi-connected bridge punch; separation punch 322; outer arc surface 3221 of separation punch; plastic-coated through hole 3222 of separation punch; rivet point 3223 of separation punch; second center connecting bridge H2; partition support bridge 323; partition wide magnetic bridge 324; narrow magnetic bridge 325;

[0054] Permanent magnet 4; shaft 5; winding 6; insulating frame 7. DETAILED DESCRIPTION

[0055] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0056] It should be noted in advance that, in the description of this application, “axial direction” generally refers to the axial direction of the motor, that is, the extending direction along the rotation axis of the motor.

[0057] like Figure 1 As shown, one embodiment of the present invention is a permanent magnet brushless DC motor, which includes a housing 1, a stator core 2, a rotor core 3, a permanent magnet 4, a shaft 5, a winding 6 and an insulating frame 7.

[0058] like Figure 3 and 4 As shown, the stator core 2 is enclosed by twelve T-shaped tooth yokes 21. The stator core 2 and the housing 1 are connected at the connection points between adjacent T-shaped tooth yokes 21, forming a contact region 22. The outer surface or top surface of the yoke portion 211 of each T-shaped tooth yoke 21 is flat, and the gap between it and the inner wall of the circular housing 1 forms a filling region 23. Filling region 23 can be filled with a variety of materials. In this example, the housing 1 is made of bulk molding compound, so the bulk molding compound is also injected into filling region 23. That is, the housing 1 and the filling material are made of the same material. The mixture of the two enhances the motor's stiffness, improves damping, and absorbs vibration. The winding 6 uses flying fork winding. The designed stator slot pattern effectively avoids flying fork winding interference, improving mass production efficiency.

[0059] like Figure 3As shown, the outer surface of the yoke portion 211 of the T-shaped tooth yoke 21 is parallel to the stator slot bottom 2111. The T-shaped tooth yoke 21 is provided with two inner and outer rivet points of different sizes. The size of the outer rivet point 213 is larger than that of the inner rivet point 214. In this embodiment, the diameter of the outer rivet point 213 is 1.2 mm and the diameter of the inner rivet point 214 is 1.0 mm; the outer rivet point 213 is located at the center of the yoke 211, and the inner rivet point 214 is located in the middle of the tooth crown of the tooth portion 212; the tooth crown of the tooth portion 212 is in the shape of an oblique shoulder type, and the angle between the inner inclined surface of the oblique shoulder tooth crown groove 2121 and the radial boundary of the tooth portion 212 is an obtuse angle, preferably 120°, and the tooth portion 212 is perpendicular to the outer surface of the yoke 211 or the stator slot bottom 2111, and the slope of the straight section of the oblique shoulder tooth crown groove 2121 is 30°. The width of the narrowest part of the tooth portion 212 is 5.2 mm, and the height of the yoke 211 is 3.5 mm. Combined with the production process calculation, in this embodiment, Figure 11 As shown, the theoretical slot area of ​​the stator core 2 is compared with Figure 12 The slot area of ​​the conventional circular stator core punching sheet shown is increased by 8.5%. The bending point 2112 mainly serves to release stress when bending the stator core 2.

[0060] like Figure 2 、 15 As shown in Figure 16, in this embodiment, the rotor core 3 includes two fully connected bridge-type lamination groups 31 and one half-connected bridge-type lamination group 32, which are stacked axially so that the half-connected bridge-type lamination group 32 is located between the two fully connected bridge-type lamination groups 31, that is, the two fully connected bridge-type lamination groups 31 are respectively located at both ends of the rotor core 3, and the half-connected bridge-type lamination group 32 is located in the middle of the rotor core 3. This rotor core structure can make adjacent sectors asymmetric, thereby greatly reducing the self-linkage leakage flux at the bottom of the permanent magnet slot near the axis, so as to improve the power density.

[0061] The semi-bridge type lamination stack 32 is composed of Figure 5 The multiple semi-connected bridge laminations shown are stacked and formed, and the semi-connected bridge laminations include multiple semi-connected bridge punches 321 and multiple separation punches 322. A separation punch 322 is provided between two adjacent semi-connected bridge punches 321, and the separation punch 322 does not contact the semi-connected bridge punch 321; a plurality of semi-connected bridge punches 321 are provided with a partition type support bridge 323 between each two; the semi-connected bridge punches 321 have a narrow magnetic bridge 325, and a partition type wide magnetic bridge 324 is provided on the second center connecting bridge H2, and the width of the partition type wide magnetic bridge 324 is greater than the width of the narrow magnetic bridge 325.

[0062] The full bridge type lamination group 31 is composed of Figure 6The fully connected bridge type laminations shown are stacked and formed, and the fully connected bridge type laminations include multiple fully connected bridge punches 311 with support bridges 312 between adjacent ones; one of the two adjacent fully connected bridge punches 311 protrudes radially outward to form a wide magnetic bridge 313, and the other protrudes radially outward to form a narrow magnetic bridge 314. The width of the wide magnetic bridge 313 is greater than the width of the narrow magnetic bridge 314. The fully connected bridge type laminations are axially opened with a plastic-coated through hole 3112, and the semi-connected bridge type laminations are axially opened with a plastic-coated through hole 3212. Plastic material is used to pass through the plastic-coated through hole 3112 and 3212 are passed through to wrap and reinforce the rotor core 3, and are positioned and connected through rivet points 3113, 3213, and 3223. The distance between the edge of the through hole of the punching sheet and the boundary of the adjacent permanent magnet slot is 2.6 mm. The axial stacking structure is A+B+A. A group of fully connected bridge laminations 31 includes 10 fully connected bridge laminations, and a group of half-connected bridge laminations 32 includes 30 half-connected bridge laminations. Compared with the motor whose rotor is formed entirely by half-connected bridge laminations, the back electromotive force coefficient of the motor in this embodiment is increased by 34.4%.

[0063] like Figure 6 As shown, the fully connected bridge lamination structure comprises ten fully connected bridge laminations 311, all connected together by a first central connecting bridge H1. This first central connecting bridge H1 comprises multiple support bridges 312, multiple wide magnetic bridges 313, and multiple narrow magnetic bridges 314, forming a continuous, integral whole. In this embodiment, the permanent magnets 4 are 5 mm thick, the narrow magnetic bridges 314 are 0.8 mm wide, the wide magnetic bridges 313 are 1.5 mm wide, the magnetic bridge length is 2.8 mm, and the support bridges 312 are 1.2 mm wide.

[0064] like Figure 5 As shown, the semi-connected bridge lamination is a semi-connected bridge structure, in which the five separated punches 322 included therein are all disconnected from the second center connection bridge H2, that is, the five separated punches 322 are not connected to the second center connection bridge H2, and are in a separated state from the second center connection bridge H2. The second center connection bridge H2 includes a plurality of partitioned support bridges 323, a plurality of partitioned wide magnetic bridges 324 and a plurality of narrow magnetic bridges 325. The second center connection bridge H2 is a continuous whole. Of course, the number of separated punches 322 is not limited to 5, and can be 1-4, or other numbers. The narrow magnetic bridge 325 has a width of 0.8 mm, and the distance between the partitioned support bridge 323 and the permanent magnet 4 is 2.5 mm. Through the optimization of the above parameters, the self-linkage leakage magnetic flux at the bottom of the permanent magnet slot near the axis of the rotor core 3 is greatly reduced, ensuring that other parameters remain unchanged. The magnetic field distributions of the full-bridge connected rotor structure, the non-partitioned support bridge structure and the present embodiment are compared, and the self-linkage leakage magnetic flux coefficient is calculated, see. Figure 10It can be obtained that the slot bottom self-linkage leakage coefficients of the three types of motors, namely A full-connected bridge type, B non-partition support bridge type and C hybrid bridge type of the present invention, are 0.207, 0.065 and 0.018 respectively, which proves that this embodiment can greatly reduce the slot bottom self-linkage leakage coefficient, thereby greatly improving the power density of the motor.

[0065] like Figure 5 、 Figure 6 and Figure 13 As shown in the figure, the outer arc surface of both the full-bridge lamination and the semi-bridge lamination adopts a five-segment spline structure to reduce torque fluctuation and improve motor vibration noise. Each rotor sector adopts this structure, namely, a middle arc segment main spline D with a central angle of α that is concentric with the stator, two eccentric arc line splines E with a central angle of β1 adjacent to the arc segment main spline D on the left and right, and two straight line segment splines F with a central angle of β2 on the edge, which should satisfy α+2β1+2β2=36°.

[0066] By comparing and analyzing the full-circle rotor, the traditional three-segment arc rotor, and the five-segment spline rotor of this embodiment, the optimized no-load back EMF distortion rate is only 1.18%, and the corresponding harmonic components are as follows: Figure 14 In this embodiment, the rotor surface is overmolded with bulk molding compound, and the maximum speed at which the motor fails structurally is 19,000 rpm, which is more than six times the actual operating speed of the motor. This demonstrates that the rotor surface structure design of this embodiment can ensure high sinusoidality of the air gap magnetic field and sufficient structural strength.

[0067] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0068] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0069] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A permanent magnet motor comprising a housing, a stator core, and a rotor core; the rotor core is mounted in a space enclosed by the stator core; and characterized in that: The rotor core includes at least two full-bridge lamination stacks and at least one half-bridge lamination stack, wherein the laminations in the full-bridge lamination stack include a first central connecting bridge and a plurality of full-bridge punchings connected to the first central connecting bridge and distributed circumferentially, and the laminations in the half-bridge lamination stack include a second central connecting bridge and at least one separate punching disconnected from the second central connecting bridge and distributed circumferentially, and adjacent sectors of the rotor core are not symmetrical along the radial centerline of the slots between the adjacent sectors; The stator core is surrounded by a plurality of T-shaped tooth yokes, the outer surface of each T-shaped tooth yoke is parallel to the bottom of the stator slot, the boundary surface between the tooth portion and the yoke portion of the T-shaped tooth yoke is perpendicular, and the number of the T-shaped tooth yokes is equal to the number of motor slots.

2. The permanent magnet motor according to claim 1, characterized in that The fully connected bridge lamination group includes multiple fully connected bridge laminations, and the semi-connected bridge lamination group includes multiple semi-connected bridge laminations. The fully connected bridge lamination group and the semi-connected bridge lamination group are stacked axially so that each semi-connected bridge lamination group is located between two fully connected bridge lamination groups.

3. The permanent magnet motor according to claim 2, characterized in that: The fully connected bridge laminations include a plurality of fully connected bridge punches, and support bridges are provided between adjacent fully connected bridge punches.

4. The permanent magnet motor according to claim 3, characterized in that The fully connected bridge punching sheet has a first narrow magnetic bridge, which extends radially outward to form a first sector; permanent magnets are placed in the slots between adjacent first sectors, and the first center connecting bridge protrudes radially outward along the corresponding slot to form the support bridge, which is in contact with the permanent magnet.

5. The permanent magnet motor according to claim 3, characterized in that: The fully connected bridge punching sheet has a first narrow magnetic bridge, and the width of the first narrow magnetic bridge is smaller than the width of the supporting bridge.

6. The permanent magnet motor according to claim 2, characterized in that: The semi-connected bridge type laminations include multiple semi-connected bridge punches and multiple separation punches. A separation punch is provided between two adjacent semi-connected bridge punches, and the separation punch does not contact the semi-connected bridge punches; and a partition-type support bridge is provided between adjacent semi-connected bridge punches and the separation punches.

7. The permanent magnet motor according to claim 6, characterized in that: The half-bridge punching sheet has a second narrow magnetic bridge, and the second narrow magnetic bridge extends radially outward to form a second sector.

8. The permanent magnet motor according to claim 7, characterized in that: Permanent magnets are placed in the slots between adjacent second sectors, and the second central connecting bridge extends radially outward along the corresponding slot to form the partition type support bridge; the partition type support bridge is separated from the permanent magnets.

9. The permanent magnet motor according to claim 8, characterized in that: The distance between the partitioned support bridge and the permanent magnet is smaller than the length of the magnetic bridge of the fully connected bridge punching sheet.

10. The permanent magnet motor according to claim 6, characterized in that: The outer arc surface of each of the semi-bridge punching pieces and each of the separation punching pieces includes multiple splines; The spline at least includes a circular arc segment main spline and straight line segment splines arranged on both sides of the circular arc segment main spline.

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