Armature core with semi-closed slot and stacked long direction staggered teeth and permanent magnet linear motor

Abstract

The application discloses an armature core with half-closed slots and staggered teeth in the stacking direction and a permanent magnet linear motor. The core body of the armature core is formed by stacking a plurality of magnetic conductive sheets in the stacking direction; each magnetic conductive sheet has a plurality of tooth structures and tooth slots; the tooth structures of the plurality of magnetic conductive sheets are stacked in the stacking direction to form the tooth structures of the core body, including end teeth and intermediate teeth, the width of the end teeth is smaller than that of the intermediate teeth, and the center pitches of the tooth structures are equal; the tooth slots are half-closed slots, the slot opening width is smaller than the slot body width, and tooth shoes are arranged on both sides of the slot opening; the plurality of magnetic conductive sheets are divided into at least two groups of magnetic conductive sheets in the stacking direction, the tooth structures of each group of magnetic conductive sheets are offset from the reference position in the moving direction by a staggering amount, so that the tooth slot forces generated by the tooth structures of each group of magnetic conductive sheets are offset from each other when the tooth slot forces are superimposed in the stacking direction. The armature core can reduce the tooth slot force, reduce the thrust fluctuation of the permanent magnet linear motor, and improve the running stability and positioning accuracy.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet linear motor technology, and in particular to an armature core with semi-closed slots and staggered teeth in the stacked direction, and a permanent magnet linear motor. Background Technology

[0002] Currently, permanent magnet linear motors, due to their elimination of intermediate transmission mechanisms such as ball screws and gears, offer advantages such as high precision, high response speed, and high acceleration, leading to their increasingly widespread application in high-end equipment fields such as semiconductor manufacturing equipment, high-precision CNC machine tools, flat panel display manufacturing equipment, and precision testing instruments. However, the armature of a permanent magnet linear motor has a finite length in the direction of movement, and the magnetic circuit between the teeth at both ends of its iron core and the magnetic field of the permanent magnet is discontinuous. This results in prominent end effects and cogging forces, causing thrust fluctuations and limiting positioning accuracy and operational stability.

[0003] To reduce cogging force, a known linear motor has an armature with multiple teeth, on which U-phase, V-phase, and W-phase coils are wound. The teeth at both ends of the relative movement direction have a width from root to tip smaller than the width of the other teeth. The center pitch of all teeth is equal, and the tip surfaces of the teeth at both ends are flat. This design reduces cogging force by narrowing the teeth at both ends, making the magnetic attraction forces of each phase tooth approximately equal in peak value and symmetrical in phase.

[0004] However, the above-mentioned solutions have the following shortcomings. On the one hand, armature teeth are usually open-slot structures, with the slot opening width equal to the slot body width. The air gap magnetic permeability is unevenly distributed along the movement direction, and the air gap magnetic field contains many harmonic components. Relying solely on adjusting the end tooth width has limited effect on suppressing cogging forces. On the other hand, armature cores are usually formed by directly stacking multiple layers of magnetic sheets. The tooth structures of each layer of magnetic sheets are completely aligned in space, and the cogging forces generated by each layer are superimposed in phase along the stack length direction, which is not conducive to further reducing cogging forces.

[0005] Existing technologies also include solutions employing semi-closed slot structures to improve air gap magnetic field distribution. In these solutions, the slot opening width is smaller than the slot body width, and toothed shoes extending towards the center of the slot are provided on both sides of the slot opening, making the air gap magnetic permeability change smoother. However, even with the simultaneous use of end tooth width adjustment and semi-closed slot structures, the suppression effect of cogging force is still insufficient for high-end applications requiring extremely low thrust fluctuations. Furthermore, existing technologies also include solutions that offset multiple independent primary components by a certain distance in the direction of movement. However, such solutions require multiple independent primary components, leading to an increase in the number of parts, a larger overall size, and increased difficulty in assembly and magnetic gap control, which is detrimental to the miniaturization and integration of the equipment.

[0006] It is evident that existing technologies, such as end tooth width adjustment, semi-closed slot structure, or macroscopic component misalignment, or combinations thereof, still fall short in meeting the stringent requirements of high-end applications for thrust fluctuation while also ensuring structural compactness and ease of assembly. Summary of the Invention

[0007] To address the problems existing in the prior art, the main objective of this invention is to provide an armature core and a permanent magnet linear motor with semi-closed slots and staggered teeth in the stacked direction. This can effectively reduce cogging force, thereby reducing thrust fluctuation of the permanent magnet linear motor, improving operational stability and positioning accuracy, and facilitating structural compactness to meet the needs of high-end applications such as semiconductor manufacturing equipment and high-precision CNC machine tools.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an armature core having a semi-closed slot and staggered teeth in the stacked length direction, including a core body for a permanent magnet linear motor, the core body being formed by stacking multiple magnetic sheets along the stacked length direction. Each of the magnetic conductive sheets has multiple tooth structures and tooth grooves located between adjacent tooth structures; the tooth structures of the multiple magnetic conductive sheets are stacked along the stacking length direction to form the tooth structure of the iron core body, and the tooth structure of the iron core body includes end teeth located at both ends in the moving direction and intermediate teeth located between the end teeth, the width of the end teeth in the moving direction is smaller than the width of the intermediate teeth in the moving direction, and the center pitch of each tooth structure is equal; The toothed groove of the iron core body is formed as a semi-closed groove, the width of the groove opening is smaller than the width of the groove body, and toothed shoes extending towards the center of the groove are provided on both sides of the groove opening. The plurality of magnetic sheets are sequentially divided into at least two magnetic sheet groups along the stacking length direction, and the magnetic sheets in each magnetic sheet group are adjacent to each other in the stacking length direction; taking the position of the tooth structure of one magnetic sheet group in the moving direction as the reference position, the tooth structure of the other magnetic sheet groups is offset relative to the reference position in the moving direction by a misalignment amount, so that the cogging forces generated by the tooth structures of each magnetic sheet group cancel each other out when superimposed in the stacking length direction.

[0009] Preferably, in the aforementioned armature core, the ratio of the width of the semi-closed slot opening to the width of the semi-closed slot body is 0.15~0.4, and the width of the slot opening is 1~5mm, and the width of the slot body is 8~15mm; the depth of the semi-closed slot opening is 0.5~2mm, and the thickness of the toothed shoe is 1~3mm; a transition fillet is provided at the transition between the slot opening and the slot body, and the radius of the transition fillet is 0.2~0.5mm; and the end of the toothed shoe is rounded.

[0010] Preferably, in the armature core described above, each of the magnetic sheet groups adopts a unidirectional misalignment; the misalignment of the tooth structure of each magnetic sheet group relative to the reference position increases sequentially along the stack length direction, the difference between the misalignment of the tooth structure of two adjacent magnetic sheet groups relative to the reference position is equal, and the maximum misalignment of the tooth structure of each magnetic sheet group relative to the reference position is less than the center pitch of the tooth structure. The magnetic sheet group consists of 2 to 6 sheets, and each magnetic sheet group contains an equal or approximately equal number of magnetic sheets; after the magnetic sheets are stacked to form the iron core body, the two end faces of the iron core body in the stacking length direction remain neat.

[0011] Preferably, in the armature core described above, each of the magnetic sheet groups adopts an alternating bidirectional misalignment; a portion of the magnetic sheet groups are offset in the positive direction relative to the reference position along the moving direction, and another portion of the magnetic sheet groups are offset in the negative direction relative to the reference position along the moving direction; the sum of the misalignment amounts of the positively offset magnetic sheet groups is equal to or approximately equal to the sum of the misalignment amounts of the negatively offset magnetic sheet groups, thereby making the overall equivalent offset of the core body approach zero.

[0012] Preferably, in the aforementioned armature core, the plurality of magnetic sheets are sequentially divided into a first magnetic sheet group, a second magnetic sheet group, and a third magnetic sheet group along the stacking length direction; the first and third magnetic sheet groups are offset in the positive direction of movement relative to the reference position, and the second magnetic sheet group is offset in the negative direction of movement relative to the reference position; the stacking length of the first and third magnetic sheet groups is equal to one-quarter of the total stacking length of the core body along the stacking length direction, and the stacking length of the second magnetic sheet group is equal to one-half of the total stacking length; the misalignment of the first and third magnetic sheet groups is equal, and the misalignment of the second magnetic sheet group is equal to the misalignment of the first magnetic sheet group.

[0013] Preferably, in the armature core described above, the misalignment amount is determined based on the center pitch of the tooth structure; the difference in offset of the tooth structure of two adjacent sets of magnetic sheet groups in the direction of movement is the offset step size; the offset step size is equal to the center pitch of the tooth structure divided by the number of magnetic sheet groups.

[0014] Preferably, in the aforementioned armature core, the misalignment is determined based on the cogging force period of the core body; the difference in offset between the tooth structures of two adjacent sets of magnetic sheet groups in the moving direction is the offset step size; the offset step size is equal to the cogging force period divided by the number of magnetic sheet groups; the cogging force period is equal to the number of stator slots of the permanent magnet linear motor multiplied by the center pitch of the tooth structure, and then divided by the least common multiple of the slot poles; the least common multiple of the slot poles is the least common multiple of the number of stator slots of the permanent magnet linear motor and the number of poles of the permanent magnet linear motor.

[0015] Preferably, in the armature core described above, the width of the end teeth in the moving direction is a first width, and the width of the intermediate teeth in the moving direction is a second width; the first width is greater than or equal to 0.7 times the second width, and the first width is less than the second width; the tip surface of the end teeth is a flat surface.

[0016] In a second aspect, the present invention provides a permanent magnet linear motor, comprising a magnetic field portion and an armature, the armature comprising an armature core as described in any one of claims 1 to 8, and U-phase, V-phase and W-phase coils wound on the tooth structure; the armature is disposed opposite to the magnetic field portion through an air gap, and the armature is capable of linear movement along the direction of movement.

[0017] Preferably, in the above-mentioned permanent magnet linear motor, the magnetic field portion includes a yoke and a plurality of permanent magnets; the plurality of permanent magnets are disposed on the yoke and arranged linearly along the direction of movement; the polarities of two adjacent permanent magnets are opposite, and the permanent magnets are inclined relative to the direction of movement.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, the core body is formed by stacking multiple magnetic sheets along the stacking length direction. These magnetic sheets are sequentially divided into at least two magnetic sheet groups along the stacking length direction. The tooth structure of each magnetic sheet group is offset relative to a reference position by a misalignment amount in the moving direction. The tooth grooves of the core body are formed as semi-closed grooves, with toothed shoes extending towards the center of the groove on both sides. The width of the end teeth in the moving direction is smaller than that of the middle teeth, and the center pitch of each tooth structure is equal. The difference in end tooth width and the equal pitch make the magnetic circuit distribution more balanced. The semi-closed grooves and toothed shoes smooth the change in air gap magnetic permeability along the moving direction and reduce the harmonic content in the air gap magnetic field. The misalignment of the magnetic sheet groups causes the cogging forces generated by the tooth structures of each magnetic sheet group to cancel each other out when superimposed in the stacking length direction. Therefore, the cogging force of the armature core is reduced, the thrust fluctuation of the permanent magnet linear motor is reduced, and the running stability and positioning accuracy are improved. This invention is suitable for linear motor applications with high requirements for running stability, such as semiconductor manufacturing equipment and high-precision CNC machine tools. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of a permanent magnet linear motor according to an embodiment of this application; Figure 2 This is a schematic diagram of the front view structure of a permanent magnet linear motor according to an embodiment of this application; Figure 3 This is a top view of the permanent magnet linear motor according to an embodiment of this application; Figure 4 This is a front view structural schematic diagram of the armature core according to an embodiment of this application; Figure 5This is a partially enlarged structural diagram of the semi-closed slot of the armature core according to an embodiment of this application; Figure 6 This is a top view of the armature core according to an embodiment of this application; Figure 7 This is a three-dimensional structural diagram of the magnetic sheet group when the number of groups of the armature core in this application is 2; Figure 8 This is a schematic diagram of the magnetic field structure of the permanent magnet linear motor according to an embodiment of this application; Figure 9 This is a top view of the magnetic field section of the permanent magnet linear motor according to an embodiment of this application; Figure 10 This is a top view schematic diagram of the magnetic field section of the permanent magnet linear motor of this application.

[0020] Reference numerals: 10. Core body; 11. Magnetic sheet; 12. End tooth; 13. Middle tooth; 14. Tooth groove; 15. Tooth shoe; 21. First magnetic sheet group 21; 22. Second magnetic sheet group 22; 23. Third magnetic sheet group 23; 31. Magnetic yoke; 32. Permanent magnet; 33. Coil; 34. Air gap. Detailed Implementation

[0021] To better illustrate the objectives, technical solutions, and advantages of the present invention, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] like Figure 1 As shown, this embodiment of the invention provides a permanent magnet linear motor, including a magnetic field section and an armature. The armature includes an armature core and U-phase, V-phase, and W-phase coils 33 wound on a toothed structure around the armature core. The armature is disposed opposite to the magnetic field section through an air gap 34, and the armature is capable of linear movement along the direction of movement. (In conjunction with...) Figures 1 to 3 as well as Figure 8 The magnetic field part is fixedly set, and an air gap 34 is left between the armature and the magnetic field part. Under the action of electromagnetic force, the armature moves in a straight line relative to the magnetic field part along the direction of movement.

[0023] like Figure 8 As shown, the magnetic field section includes a yoke 31 and multiple permanent magnets 32. The multiple permanent magnets 32 are disposed on the yoke 31 and arranged linearly along the direction of movement. The polarities of adjacent permanent magnets 32 are opposite, as shown below. Figure 9 As shown. Combined with Figures 8 to 10 The magnetic yoke 31 has a long, strip-shaped plate structure, with multiple permanent magnets 32 arranged sequentially along the length of the yoke 31. The polarities of adjacent permanent magnets 32 are opposite, thus alternately forming N and S poles on the surface of the yoke 31. Figure 10As shown, the permanent magnet 32 ​​is tilted relative to the direction of movement, with an tilt angle of 1 to 5 degrees. This tilt creates a phase difference in the magnetic field distribution along the direction of movement, which, in conjunction with the semi-closed slots and staggered tooth structure of the armature core, further reduces cogging force and thrust fluctuations. The permanent magnet 32 ​​can be made of rare-earth permanent magnet materials, such as neodymium iron boron permanent magnets, with grades ranging from N48 to N52. The pole spacing between adjacent permanent magnets 32 can be 12 to 20 mm. It is understood that the number and size of the permanent magnets 32, as well as the length of the yoke 31, can be selected according to the stroke and thrust requirements of the actual application scenario. The permanent magnets 32 and the yoke 31 can be connected by bonding or mechanical fixing.

[0024] like Figure 4 and Figure 7 As shown, an embodiment of the present invention provides an armature core with semi-closed slots and staggered teeth in the stacked length direction, comprising a core body 10 for a permanent magnet linear motor. The core body 10 is formed by stacking a plurality of magnetic sheets 11 along the stacked length direction. Figure 4 As shown, each magnetic sheet 11 has multiple tooth structures and tooth grooves 14 located between adjacent tooth structures. The tooth structures of multiple magnetic sheets 11 are stacked along the stacking length direction to form the tooth structure of the iron core body 10. The tooth structure of the iron core body 10 includes end teeth 12 located at both ends in the moving direction and intermediate teeth 13 located between the end teeth 12. The width of the end teeth 12 in the moving direction is smaller than the width of the intermediate teeth 13 in the moving direction, and the center pitch of each tooth structure is equal. Figure 5 As shown, the toothed groove 14 of the iron core body 10 is formed as a semi-closed groove. The groove opening width W0 is smaller than the groove body width, and toothed shoes 15 extending towards the center of the groove are provided on both sides of the groove opening. Figure 6 As shown, multiple magnetic sheets 11 are sequentially divided into at least two magnetic sheet groups along the stacking length direction, and the magnetic sheets 11 in each magnetic sheet group are adjacent to each other in the stacking length direction. Taking the position of the tooth structure in the movement direction of one magnetic sheet group as the reference position, the tooth structure of the remaining magnetic sheet groups is offset relative to the reference position by a misalignment amount in the movement direction, such as... Figure 6 and Figure 7 As shown, this is to ensure that the cogging forces generated by the tooth structure of each magnetic sheet group cancel each other out when they are superimposed in the stacking direction.

[0025] Specifically, the core body 10 is used to support multiple magnetic sheets 11 and form an armature magnetic circuit. The core body 10 can be in the form of a plate or strip, and is made of multiple magnetic sheets 11 stacked along the length direction and fixed together by riveting, welding or casting. The magnetic sheets 11 are used to conduct magnetism and form tooth structures and tooth grooves 14. They can be made of silicon steel sheets by punching or other materials with magnetic properties. The tooth structure is used to wind the coil 33 and form a magnetic circuit, wherein the end teeth 12 are located at both ends in the direction of movement, the middle teeth 13 are located between the end teeth 12, and the tooth structures are arranged along the direction of movement, such as... Figure 4 As shown. The slot 14 is used to accommodate the coil 33 and form the air gap magnetic circuit, with slots 14 formed between adjacent tooth structures. The semi-closed slot is used to improve the air gap magnetic permeability distribution; its slot opening width W0 is smaller than the slot body width, and toothed shoes 15 are provided on both sides of the slot opening, extending towards the center of the slot. The toothed shoes 15 are used to smooth the air gap magnetic permeability and reduce harmonic content; their shape can be rectangular, trapezoidal, or arc-shaped. The magnetic sheet group is used to achieve grouped staggered teeth, dividing multiple magnetic sheets 11 sequentially into at least two groups along the stack length direction, each group containing several layers of magnetic sheets 11. The reference position is used to provide a reference for the misalignment amount, with the position of the tooth structure of one of the magnetic sheet groups in the movement direction as the reference. The misalignment amount is used to offset the phase of the cogging forces in each group, and the tooth structures of the remaining magnetic sheet groups are offset by their respective misalignment amounts relative to the reference position in the movement direction.

[0026] A coil 33 is wound on the tooth structure of the armature core. When alternating current is applied to the coil 33, a traveling wave magnetic field is generated in the air gap 34. The traveling wave magnetic field interacts with the magnetic field of the magnetic field section, generating an electromagnetic thrust that propels the armature in the direction of movement. The coil 33 can be wound on the tooth structure using a concentrated winding method or a distributed winding method. When using a concentrated winding method, one coil 33 is wound on each tooth structure individually; when using a distributed winding method, each coil 33 is wound across multiple tooth structures. The coil 33 includes a U-phase coil, a V-phase coil, and a W-phase coil, with at least one of the U-phase coil, V-phase coil, and W-phase coil wound on the end teeth 12 and the middle teeth 13, respectively.

[0027] To reduce cogging force, the tooth structure of the core body 10 works synergistically in the following ways: During assembly, multiple magnetic sheets 11 are stacked along the stacking length direction to form the core body 10. The tooth structure of each magnetic sheet group is offset relative to the reference position by its respective misalignment amount in the moving direction. During operation, the difference in width of the end teeth 12 and the equal pitch make the magnetic circuit distribution of the core body 10 tend to be balanced along the moving direction, and the phase relationship of the magnetic attraction force of each tooth structure is improved. The semi-closed slot and tooth shoe 15 make the change of air gap magnetic permeability along the moving direction tend to be smooth, reducing the harmonic content in the air gap magnetic field. The misalignment of the magnetic sheet groups causes the cogging force generated by the tooth structure of each magnetic sheet group to have a phase difference. When the cogging forces of each magnetic sheet group are superimposed in the stacking length direction, the different phases cancel each other out. Through the combined effect of the above three aspects, the cogging force of the armature core is reduced, the thrust fluctuation of the permanent magnet linear motor is reduced, and the running stability and positioning accuracy are improved.

[0028] like Figure 5 As shown, the ratio W0 / Ws of the opening width W0 of the semi-closed slot to the width Ws of the slot body is 0.15 to 0.4, with the opening width W0 being 1~5mm and the slot body width Ws being 8~15mm. The opening depth h0 of the semi-closed slot is 0.5~2mm, and the thickness h1 of the toothed shoe 15 is 1~3mm. A transition fillet is provided at the transition between the opening and the slot body, with a radius of 0.2~0.5mm, and the end of the toothed shoe 15 is rounded. The ratio of the opening width W0 to the slot body width Ws within the above range ensures a sufficiently smooth change in the air gap magnetic permeability along the moving direction, effectively filtering out higher harmonics in the air gap magnetic field while avoiding local magnetic saturation due to an excessively narrow opening. The selection of the opening depth h0 and the toothed shoe 15 thickness h1 balances the smoothness of the magnetic circuit transition with the mechanical strength of the toothed shoe 15. The rounded corners at the transition and the rounded corners at the ends of the toothed shoe 15 further smooth the magnetic field distribution, reduce stress concentration, and help reduce iron loss.

[0029] In some implementation examples, each magnetic sheet group employs unidirectional misalignment. The misalignment of the tooth structure of each magnetic sheet group relative to the reference position increases sequentially along the stacking length direction. The difference between the misalignment of the tooth structure of two adjacent magnetic sheet groups relative to the reference position is equal, and the maximum misalignment among the misalignments of the tooth structure of each magnetic sheet group relative to the reference position is less than the center pitch P1 of the tooth structure. There are 2 to 6 magnetic sheet groups, and each magnetic sheet group contains an equal or approximately equal number of magnetic sheets 11. After the magnetic sheets 11 are stacked to form the iron core body 10, the two end faces of the iron core body 10 remain aligned along the stacking length direction. Unidirectional misalignment causes the cogging forces of each magnetic sheet group to be sequentially staggered in spatial phase. When the cogging forces of each magnetic sheet group are superimposed along the stacking length direction, the harmonic components of orders that are integer multiples of the number of non-magnetic sheet groups cancel each other out, retaining only the higher-order harmonics that are integer multiples of the number of magnetic sheet groups, thereby significantly reducing the total cogging force. The maximum misalignment is less than the center pitch P1, ensuring that the misalignment is within one tooth pitch range and preventing excessive misalignment from causing magnetic circuit disorder. The number of magnetic sheets 11 in each group is equal or approximately equal, which helps ensure that the cogging force amplitude generated by each group of magnetic sheets is similar, thereby improving the cancellation effect. The two end faces of the core body 10 in the stacking direction remain neat, ensuring the flatness of the core's outer contour, facilitating assembly, and not affecting the uniformity of the air gap. Specifically, a special positioning fixture can be used for stacking the magnetic sheets 11, achieving a misalignment accuracy of ±0.05mm.

[0030] In some implementation examples, the magnetic sheet groups are staggered bidirectionally offset. One group of magnetic sheet groups is offset forward relative to a reference position along the direction of movement, while another group is offset backward relative to a reference position along the direction of movement. The sum of the offsets of the forward-offset magnetic sheet groups is equal to or approximately equal to the sum of the offsets of the backward-offset magnetic sheet groups, thus making the overall equivalent offset of the core body 10 approach zero. Figure 6 and Figure 7 As shown. Unidirectional misalignment causes an equivalent unidirectional offset of the entire iron core, resulting in lateral magnetic pull, increasing the load on the guide rail and potentially causing vibration. Interleaved bidirectional misalignment, by shifting one part of the magnetic sheet group forward and the other part in reverse, and making the sum of the forward and reverse offsets equal, cancels out the equivalent offset of the entire iron core, thereby eliminating the lateral magnetic pull and the inherent bias magnetic force at zero position, and improving the control accuracy of low-speed, small displacement.

[0031] like Figure 7As shown, multiple magnetic sheets 11 are sequentially divided into a first magnetic sheet group 2121, a second magnetic sheet group 2222, and a third magnetic sheet group 2323 along the stacking length direction. The first magnetic sheet group 2121 and the third magnetic sheet group 2323 are offset in the positive direction of movement relative to the reference position, while the second magnetic sheet group 2222 is offset in the negative direction of movement relative to the reference position. The stacking length of the first magnetic sheet group 2121 and the third magnetic sheet group 2323 is equal to one-quarter of the total stacking length of the iron core body 10 along the stacking length direction, and the stacking length of the second magnetic sheet group 2222 is equal to one-half of the total stacking length. The misalignment amounts of the first magnetic sheet group 2121 and the third magnetic sheet group 2323 are equal, and the misalignment amount of the second magnetic sheet group 2222 is twice the misalignment amount of the first magnetic sheet group 2121. When the number of magnetic sheet groups is two, the above-mentioned three-group structure is adopted. The first magnetic sheet group 21 and the third magnetic sheet group 23 are forward offset, each accounting for one-quarter of the total stack length. The second magnetic sheet group 22 is reverse offset, with a stack length accounting for half of the total stack length. Simultaneously, the misalignment of the second magnetic sheet group 22 is twice that of the first magnetic sheet group 21. This ensures that the sum of the forward offsets equals the sum of the reverse offsets, thus achieving an overall equivalent offset of the core approaching zero. This structure, while ensuring the cogging force cancellation effect, achieves a balance between left and right offsets and helps disperse internal stress within the laminates, reducing the risk of core warping and deformation.

[0032] In some implementation examples, the misalignment is determined based on the center pitch P1 of the tooth structure. The difference in offset between two adjacent sets of magnetic sheet groups in the direction of movement is the offset step size, which is equal to the center pitch P1 of the tooth structure divided by the number of magnetic sheet groups. For an integer-slot linear motor, the period of the cogging force is equal to the center pitch P1 of the tooth structure. Therefore, calculating the offset step size based on the center pitch P1 allows the phases of the cogging forces in each magnetic sheet group to be staggered sequentially, thereby achieving harmonic cancellation. This method is simple to calculate and suitable for integer-slot motors.

[0033] In some implementation examples, the misalignment is based on the period of the cogging force of the core body 10 X. cog Confirmed. The difference in offset of the tooth structure between two adjacent sets of magnetic sheets in the direction of movement is the offset step size, which is equal to the period of the cogging force X. cog Divide by the number of magnetic sheet assemblies. Cogging force period X cog This refers to the displacement corresponding to one complete cycle of cogging force along the direction of movement. The period of the cogging force is X. cog The periodicity of the cogging force is equal to the number of stator slots Q of the permanent magnet linear motor multiplied by the center pitch P1 of the tooth structure, and then divided by the least common multiple of the slot poles LCM(Q, 2p). The least common multiple of the slot poles is the least common multiple of the number of stator slots Q and the number of poles 2p of the permanent magnet linear motor. For fractional slot linear motors, the periodicity of the cogging force X is... cogBy using the above formula to calculate the offset step size, which is smaller than the center pitch P1 of the tooth structure, the tooth cogging force phase of each magnetic sheet group can be offset with a smaller misalignment, thereby reducing the average thrust loss caused by misalignment while achieving harmonic cancellation.

[0034] The following theoretical derivation further explains the principle of cogging force cancellation. For linear motors, the cogging force fluctuation period is obtained based on the slot-pole coordination. Using this as a benchmark, a staggered tooth design is implemented using M groups of magnetic sheets within a single iron core to achieve harmonic cancellation. The symbols are defined as follows: Q is the number of stator slots, 2p is the number of poles, LCM(Q,2p) is the least common multiple of slots and poles, P1 is the armature tooth pitch, M is the number of physical groups of magnetic sheets stacked within the same iron core, and k is the magnetic sheet group number. .

[0035] The repetitive periodic displacement of the cogging force is: .

[0036] The distance X that the mover moves relative to the stator cog The cogging force completes one full cycle of oscillation.

[0037] The coarse electrical angle is: , Where x is the linear displacement of the mover relative to the stator; moving one x... cog The electrical angle of the tooth groove changes by 2π. The design conditions are M groups of magnetic plates, with the phase of the tooth groove harmonics between adjacent groups being staggered by an equal difference of 2π / M.

[0038] The phase step size is: .

[0039] The optimal adjacent group offset step size is: .

[0040] The total offset of group k relative to group 0 is: .

[0041] The phase shift of the cogging harmonics corresponding to the k-th group is: .

[0042] The offset reference uses the actual tooth cogging period X. cog Instead of stator tooth pitch P1; under fractional slot conditions Therefore, the offset step size is smaller.

[0043] Integer slot linear motors are a special case of this formula. , The formula degenerates into .

[0044] The periodic function of the cogging force of a single-layer magnetic sheet is: , Where, n cFor the period X relative to the tooth cogging period cog The harmonic order, n c =1 corresponds to the fundamental frequency of the tooth cogging of this machine. The amplitude of the first harmonic. For n c The initial phase of the first harmonic.

[0045] The k-th group of offset magnetic plates undergoes phase translation. The expression for cogging force is: .

[0046] The total cogging force of the iron core is the sum of the cogging forces of all M groups of magnetic plates: .

[0047] Change the order of summation: .

[0048] Using Euler's formula for complex numbers The inner layer is a geometric series summation.

[0049] When nc is an integer multiple of M, S(nc) equals M; When nc is not an integer multiple of M, S(nc) equals 0. The total cogging force after superposition is: .

[0050] The original coarse tooth force spatial period is: .

[0051] After M sets of micro-stacked teeth with misalignment, only the mM-order higher-order cogging harmonics are retained, and the equivalent cogging force period is... .

[0052] The conclusions are as follows: Cogging harmonics of orders other than integer multiples of M are theoretically completely canceled; only higher-order cogging harmonics of integer multiples of M are retained; fractional-slot linear motors, due to X... cog Smaller size allows for smaller group offsets while achieving harmonic cancellation.

[0053] The following is a specific implementation example of a staggered lamination and staggered tooth structure for a 12-slot, 10-pole fractional-slot linear motor. The linear motor has 12 stator slots (Q=12), 2p poles (2p=10), a pole pitch (τ=18mm), and an armature stator tooth pitch (P1=15mm). The magnetic laminations within the same primary core are divided into M=2 physical groups. Step 1: Calculate the least common multiple of slot-pole ratio: Step 2, original spatial periodic displacement of cogging force: This 12-slot, 10-pole fractional-slot linear motor has a complete cogging force oscillation cycle displacement of 3mm, not an armature tooth pitch of 15mm; the cogging force completes one complete cycle oscillation for every 3mm movement of the mover relative to the stator. Step 3, Calculation of the optimal offset step size: The optimal offset step size for adjacent magnetic sheet groups is 1.5 mm. The offset sequence for the two magnetic sheet groups is as follows: , The drawback of shifting both groups in the same direction of motion in stages is the generation of unidirectional axial magnetic pull, an overall positive equivalent shift of the iron core, an inherent bias magnetic force at the zero position, increased lateral load on the guide rail, and a tendency to induce vibration and noise. This invention employs an interleaved bidirectional offset implementation, with the two sets of magnetic sheets arranged in a bidirectional interleaved manner, and the offset sequence being... , The maximum absolute offset is... The offset is small, reducing the average thrust loss caused by misalignment. Simultaneously, a grouped structure is adopted, with the armature length La divided into three groups. The first magnetic sheet group 21 and the third magnetic sheet group 23 have a stack length of La / 2 / M, and are offset to the right by a small amount. The second magnetic sheet group 22 has a stack length of La / M and is offset to the left by an amount of... That is, the left and right offsets are balanced, the magnetic pull generated by the groups offset to the right and left cancels each other out, and the overall equivalent offset of the iron core approaches 0.

[0054] In some implementation examples, the width of the end tooth 12 in the moving direction is a first width TW1, and the width of the intermediate tooth 13 in the moving direction is a second width TW2. The first width TW1 is greater than or equal to 0.7 times the second width TW2, and the first width TW1 is less than the second width TW2. The tip surface of the end tooth 12 is a flat surface, such as... Figure 4 As shown. The width of the end tooth 12 is set to be greater than or equal to 0.7 times the width of the middle tooth 13 but less than the width of the middle tooth 13. This ensures that the end tooth 12 is effectively narrowed to balance the phase of the magnetic attraction between phases, while avoiding excessive narrowing of the end tooth 12 which could lead to magnetic saturation or excessive reduction in induced voltage. The tip surface of the end tooth 12 is a flat surface, which helps to suppress the reduction in induced voltage caused by the narrowing of the end tooth 12, ensuring the thrust output of the motor. Through the combination of the width ratio of the end tooth 12 and the flat end surface, thrust density can be maintained while suppressing cogging force.

[0055] The following are several specific implementation examples to further illustrate the technical solutions and effects of the present invention.

[0056] Example 1 employs a staggered tooth structure with four groups of magnetic sheets and a semi-closed slot. The total number of teeth is six, with a pitch P1 of 18 mm. The width TW2 of the middle tooth 13 is 9.5 mm, and the width TW1 of the end tooth 12 is 8.5 mm. The semi-closed slot has a slot opening width W0 of 3 mm, a slot body width of 10 mm, a slot opening depth h0 of 1 mm, and a tooth shoe thickness h1 of 2 mm. The magnetic sheets 11 are divided into four groups with misalignment amounts of 0, 4.5 mm, 9.0 mm, and 13.5 mm, respectively. Test results show a peak cogging force of 5.2 N, a 65.3% reduction compared to the 15 N of the traditional open-slot straight-stack structure, a thrust fluctuation of 1.3%, a rated thrust of 180 N, and a motor efficiency of 94.8%.

[0057] Example 2 employs a grouped staggered tooth structure with two magnetic sheet groups and a semi-closed slot. The magnetic sheet 11 is divided into two groups with a misalignment of 9mm. The slot width W0 is 2mm, and the end tooth 12 is 8mm wide. Test results show a 58% reduction in cogging force and a thrust fluctuation of 1.6%, making it suitable for cost-sensitive general automation scenarios.

[0058] Example 3 employs a structure with six groups of magnetic sheets, staggered teeth, semi-closed slots, and slanted poles. The magnetic sheets 11 are divided into six groups with a stagger of 3mm. The slot width W0 is 1.5mm, and the end teeth 12 are 7.5mm wide. The permanent magnet 32 ​​uses a slanted pole design with an inclination angle of 3 degrees. Figure 10 As shown in the figure, the test results show a 72% reduction in cogging force and a thrust fluctuation of 1.0%, making it suitable for high-precision applications such as semiconductor die bonders and bonding machines.

[0059] Example 4 employs a 12-slot, 10-pole fractional-slot motor with an interleaved bidirectional staggered structure. The stator has 12 slots, 10 poles, and a tooth pitch P1 of 15mm. The magnetic conductor 11 is divided into two groups, and the cogging force period X... cog The offset is 3mm, with an offset step size of 1.5mm. The first group of magnetic sheets 11 is offset 1.5mm in the forward direction, and the second group of magnetic sheets 11 is offset 1.5mm in the reverse direction. The overall equivalent offset of the iron core approaches zero. Figure 7 As shown in the figure, this structure can balance cogging harmonic suppression and lateral force balance, and reduce the average thrust loss caused by misaligned teeth.

[0060] In summary, this embodiment achieves the following beneficial effects through the above technical solution: Since the width of the end teeth 12 in the moving direction is smaller than that of the middle teeth 13 and the center pitch P1 of each tooth structure is equal, the magnetic circuit distribution of the core body 10 along the moving direction tends to be balanced; since the tooth grooves 14 of the core body 10 are formed as semi-closed grooves and toothed shoes 15 extending towards the center of the groove are provided on both sides of the groove opening, the change in air gap magnetic permeability along the moving direction tends to be smooth, and the harmonic content in the air gap magnetic field is reduced; since multiple magnetic sheets 11 are sequentially divided into at least two magnetic sheet groups 20 along the stacking length direction, and the tooth structure of each magnetic sheet group 20 is offset relative to the reference position by a misalignment amount in the moving direction, the cogging forces generated by each magnetic sheet group 20 cancel each other out when superimposed in the stacking length direction. Therefore, the cogging force of the armature core is reduced, the thrust fluctuation of the permanent magnet linear motor is reduced, and the running stability and positioning accuracy are improved. Through the synergistic effect of these three factors, the cogging force of the armature core can be reduced by approximately 60% to 70%, and the thrust fluctuation of the permanent magnet linear motor can be reduced to approximately 1.0% to 1.5%. Furthermore, this staggered tooth structure does not require complex inclined slot molds; stacking can be achieved using specialized positioning tooling, resulting in only a limited increase in manufacturing costs. The additional technical features defined in the dependent claims further optimize the slot width W0, slot body width, slot depth h0, tooth shoe thickness h1, and transition radius of the semi-closed slot, as well as the specific forms of unidirectional and staggered bidirectional staggering. The amount of staggering is based on the center pitch P1 or the cogging force period X. cog The specific method and the proportional range of the end tooth 12 width are determined to obtain better tooth cogging force suppression effect and running stability in different application scenarios.

[0061] According to the implementation examples of the invention, it has the following advantages compared to the prior art: By dividing the magnetic sheets into multiple groups and setting the offset of each group based on the actual cogging force cycle of the motor, the non-M integer multiple order cogging harmonics cancel each other out through Fourier superposition, retaining only the lower amplitude mM order higher order harmonics, thereby reducing cogging force and thrust fluctuations. The use of staggered bidirectional misalignment balances the positive and negative offsets, counteracting the unidirectional axial magnetic pull, reducing lateral offset force and guide rail load, and lowering vibration and noise. The staggered bidirectional offset makes the overall equivalent offset of the iron core approach zero, eliminating the inherent bias magnetic force at zero position and improving the control accuracy of low-speed, small displacement. Using the cogging force cycle as the offset design benchmark, rather than directly using the stator tooth pitch, especially for fractional slot linear motors, allows the offset to be minimized, reducing the average thrust loss caused by misalignment. The misalignment is achieved at the micro-stacking level within a single iron core, without adding external components, keeping the motor's external size unchanged, which is beneficial for equipment miniaturization and integration. The staggered bidirectional offset disperses the internal stress of the laminates in both directions, reducing the risk of core warping and deformation, and improving the machining yield and dimensional stability of long cores. The design formula is universal and applicable to both integer-slot linear motors and fractional-slot linear motors. The number of groups can be flexibly selected according to harmonic suppression requirements.

[0062] The armature core and permanent magnet linear motor provided in this embodiment are suitable for linear motor applications that require high operational stability, such as semiconductor manufacturing equipment, high-precision CNC machine tools, flat panel display manufacturing equipment, and precision testing instruments.

[0063] The above embodiments merely illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application's patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An armature core having semi-closed slots and staggered teeth in a stacked direction, comprising a core body for a permanent magnet linear motor, characterized in that, The iron core body is formed by stacking multiple magnetic sheets along the stacking length direction; Each of the magnetic conductive sheets has multiple tooth structures and tooth grooves located between adjacent tooth structures; the tooth structures of the multiple magnetic conductive sheets are stacked along the stacking length direction to form the tooth structure of the iron core body, and the tooth structure of the iron core body includes end teeth located at both ends in the moving direction and intermediate teeth located between the end teeth, the width of the end teeth in the moving direction is smaller than the width of the intermediate teeth in the moving direction, and the center pitch of each tooth structure is equal; The toothed groove of the iron core body is formed as a semi-closed groove, the width of the groove opening is smaller than the width of the groove body, and toothed shoes extending towards the center of the groove are provided on both sides of the groove opening. The plurality of magnetic sheets are sequentially divided into at least two magnetic sheet groups along the stacking length direction, and the magnetic sheets in each magnetic sheet group are adjacent to each other in the stacking length direction; taking the position of the tooth structure of one magnetic sheet group in the moving direction as the reference position, the tooth structure of the other magnetic sheet groups is offset relative to the reference position in the moving direction by a misalignment amount, so that the cogging forces generated by the tooth structures of each magnetic sheet group cancel each other out when superimposed in the stacking length direction.

2. The armature core according to claim 1, characterized in that, The ratio of the opening width to the body width of the semi-closed groove is 0.15~0.4, and the opening width is 1~5mm, while the body width is 8~15mm; the opening depth is 0.5~2mm, and the toothed shoe thickness is 1~3mm; a transition fillet is provided at the transition between the opening and the body, with a radius of 0.2~0.5mm; and the end of the toothed shoe is rounded.

3. The armature core according to claim 1, characterized in that, Each of the magnetic sheet groups adopts unidirectional misalignment; the misalignment of the tooth structure of each magnetic sheet group relative to the reference position increases sequentially along the stack length direction, the difference between the misalignment of the tooth structure of two adjacent magnetic sheet groups relative to the reference position is equal, and the maximum misalignment of the tooth structure of each magnetic sheet group relative to the reference position is less than the center pitch of the tooth structure. The magnetic sheet group consists of 2 to 6 sheets, and each magnetic sheet group contains an equal or approximately equal number of magnetic sheets; after the magnetic sheets are stacked to form the iron core body, the two end faces of the iron core body in the stacking length direction remain neat.

4. The armature core according to claim 1, characterized in that, Each of the magnetic sheet groups adopts an interleaved bidirectional misalignment; a portion of the magnetic sheet groups are offset in the positive direction relative to the reference position along the moving direction, and another portion of the magnetic sheet groups are offset in the negative direction relative to the reference position along the moving direction; the sum of the misalignment amounts of the positively offset magnetic sheet groups is equal to or approximately equal to the sum of the misalignment amounts of the negatively offset magnetic sheet groups, thereby making the overall equivalent offset of the iron core body approach zero.

5. The armature core according to claim 4, characterized in that, The plurality of magnetic sheets are sequentially divided into a first magnetic sheet group, a second magnetic sheet group, and a third magnetic sheet group along the stacking length direction; the first magnetic sheet group and the third magnetic sheet group are offset in the positive direction of the movement relative to the reference position, and the second magnetic sheet group is offset in the negative direction of the movement relative to the reference position. The stack lengths of the first and third magnetic sheet groups are both equal to one-quarter of the total stack length of the iron core body along the stack length direction, and the stack length of the second magnetic sheet group is equal to one-half of the total stack length; the misalignment amounts of the first and third magnetic sheet groups are equal, and the misalignment amount of the second magnetic sheet group is equal to the misalignment amount of the first magnetic sheet group.

6. The armature core according to claim 1, characterized in that, The misalignment amount is determined based on the center pitch of the tooth structure; the difference in offset of the tooth structure of two adjacent sets of magnetic sheet groups in the moving direction is the offset step size; the offset step size is equal to the center pitch of the tooth structure divided by the number of magnetic sheet groups.

7. The armature core according to claim 1, characterized in that, The misalignment amount is determined based on the cogging force period of the core body; the difference in the offset of the tooth structure of two adjacent sets of magnetic sheet groups in the moving direction is the offset step size; the offset step size is equal to the cogging force period divided by the number of magnetic sheet groups; the cogging force period is equal to the number of stator slots of the permanent magnet linear motor multiplied by the center pitch of the tooth structure, and then divided by the least common multiple of the slot poles; the least common multiple of the slot poles is the least common multiple of the number of stator slots of the permanent magnet linear motor and the number of poles of the permanent magnet linear motor.

8. The armature core according to claim 1, characterized in that, The width of the end tooth in the moving direction is a first width, and the width of the middle tooth in the moving direction is a second width; the first width is greater than or equal to 0.7 times the second width, and the first width is less than the second width; the tip surface of the end tooth is a flat surface.

9. A permanent magnet linear motor, comprising a magnetic field section and an armature, characterized in that, The armature includes an armature core as described in any one of claims 1 to 8, and U-phase, V-phase, and W-phase coils wound on the tooth structure; the armature is disposed opposite to the magnetic field portion through an air gap, and the armature is capable of linear movement along the direction of movement.

10. The permanent magnet linear motor according to claim 9, characterized in that, The magnetic field section includes a yoke and a plurality of permanent magnets; the plurality of permanent magnets are disposed on the yoke and arranged linearly along the direction of movement; the polarities of two adjacent permanent magnets are opposite, and the permanent magnets are tilted relative to the direction of movement.

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