A single-piece two-stage skew-pole permanent magnet synchronous motor rotor structure

Abstract

The application discloses a single-punch two-section skew-pole permanent magnet synchronous motor rotor structure, which comprises a rotating shaft, a rotor core, magnetic steel sheets and an end plate. The rotor core is formed into a two-section structure by stacking the same rotor punch. The first section is formed by stacking the rotor punch in a normal direction, and the second section is formed by stacking the same rotor punch after being flipped by 180 degrees. The rotating shaft mounting hole is arranged at the center of the rotor punch. A plurality of groups of magnetic steel grooves are arranged on the rotor punch. The auxiliary through holes are arranged in a circumferential distribution. The center of the auxiliary through hole is located on the axis which is deviated from the horizontal reference line of the rotor axis by a preset angle. The total skew-pole angle is formed after the two-section rotor core is assembled. The single-punch normal direction and the flipped 180-degree stacking design are adopted. Only one set of punch mold is needed, and the single-key groove rotating shaft is matched, so that the processing cost is reduced, the assembly process is simplified, the eccentricity of the auxiliary through hole is 2.5 degrees, the 5-degree accurate skew-pole is formed by matching the flat key positioning, the harmonic can be effectively weakened, and the motor control precision and operation reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, and in particular to a rotor structure for a two-stage skewed permanent magnet synchronous motor with a single lamination. Background Technology

[0002] A permanent magnet synchronous motor is a high-efficiency AC motor in which the rotor is provided with a magnetic field by permanent magnets and its rotational speed is strictly synchronized with the rotating magnetic field of the stator. It is the mainstream drive solution in the fields of new energy vehicles, industrial servo motors, and high-efficiency home appliances.

[0003] In existing technologies, permanent magnet rotors mostly do not employ a segmented skewed pole structure for ease of assembly and manufacturing. While this structure simplifies the production process, it has significant drawbacks, leading to higher motor noise and vibration. Furthermore, harmonic interference can affect motor control accuracy, making it difficult to meet the operational stability and control precision requirements of high-end equipment. On the other hand, the few permanent magnet rotors that do employ a segmented skewed pole structure face numerous technical and cost challenges, specifically as follows: From an assembly process perspective, the segmented skewed-pole rotor is technically challenging and costly. Whether using a keyed or interference fit to connect the core assembly's inner bore to the shaft, each core assembly segment requires bonding – either bonded before shaft insertion or inserted before bonding – significantly increasing process complexity. Furthermore, to prevent axial movement of the segmented core assemblies, additional limiting and locking components are needed, making the rotor structure more complex and significantly increasing the requirements for preventing loosening. If a keyed connection is used, the keyway positions in each core assembly's inner bore differ. Even with only one keyway machined on the shaft, two sets of stamping dies are required to offset the keyway positions of each core assembly segment by a skewed-pole angle, further increasing die costs.

[0004] Existing segmented skewed permanent magnet rotors, in addition to being complex to assemble, costly, and structurally cumbersome, also suffer from problems such as poor consistency of skewed pole angles, discontinuous magnetic circuits, weak rotor rigidity, and easy failure of bonding at high temperatures. This results in large motor torque pulsation, poor vibration and noise suppression, and high-speed operation is prone to rotor slippage, deformation, and permanent magnet demagnetization. Back EMF waveform distortion affects control accuracy, making it difficult for existing segmented skewed rotor technology to simultaneously meet the requirements of noise reduction, control accuracy, and large-scale production. It cannot meet the high-performance and high-reliability requirements of motors in fields such as new energy vehicles and high-end servo motors.

[0005] Patent search revealed that CN114024384A uses an eccentric keyway combined with positive and negative laminations to achieve skewed poles. Although this structure can achieve segmented skewed poles, the skewed pole angle is achieved by keyway mating. The keyway mating has gaps, which can easily lead to large deviations in the angles of the two iron core sections and poor consistency of the skewed pole angles, affecting the noise reduction and vibration damping effect of the motor. At the same time, it relies on a multi-keyway shaft structure, which makes the shaft machining complex and costly. During assembly, multiple sets of keyways need to be aligned, which can easily lead to assembly misalignment and is not conducive to mass production.

[0006] CN210053261U uses multiple sets of offset keyways to achieve skewed pole switching. This solution achieves skewed pole by setting multiple sets of keyways with different angles on the shaft or lamination. The structure is complex and the number of parts is large. This not only increases the processing difficulty of the lamination and shaft, but also causes a decrease in the overall strength of the rotor. Moreover, the angle adjustment of the multi-keyway positioning method is inflexible. Changing the skewed pole angle requires redesigning the keyway position, which is costly. During assembly, the corresponding keyway must be selected for assembly, which is cumbersome and prone to incorrect angle installation, resulting in low production efficiency.

[0007] In summary, existing two-stage skewed pole rotor structures generally suffer from low skew angle accuracy, poor consistency, complex machining of shafts and laminations, cumbersome assembly, and high modification costs, making it difficult to simultaneously meet the requirements of low vibration, low noise, low cost, and high efficiency in motor production. Therefore, a two-stage skewed pole permanent magnet synchronous motor rotor structure with a single type of lamination was designed. Summary of the Invention

[0008] The purpose of this invention is to solve the above-mentioned problems by designing a rotor structure for a two-stage skewed permanent magnet synchronous motor with a single lamination.

[0009] The technical solution of the present invention to achieve the above objectives is a rotor structure for a two-section skew-pole permanent magnet synchronous motor with a single type of lamination, comprising a shaft, a rotor core, magnetic steel sheets, and end plates; the shaft is a single keyway structure shaft; The rotor core is formed by stacking and splicing rotor laminations of the same specification to form a two-section core structure. The two core sections are the first core section and the second core section. The first core section is formed by stacking rotor laminations in the forward direction, and the second core section is formed by stacking rotor laminations of the same type after rotating them 180° around their own central plane. The rotor lamination has a shaft mounting hole at its center, which is adapted to the installation of the shaft. The inner wall of the shaft mounting hole has a positioning keyway. The rotor lamination has multiple sets of magnetic slots evenly arranged along the circumferential direction. The magnetic slots are used to embed and fix permanent magnets. The rotor lamination also has several auxiliary through holes distributed along the circumference. The auxiliary through holes are eccentrically deflected by a preset angle α relative to the horizontal reference line of the rotor axis. Locking fasteners are installed inside the auxiliary through holes. After the first core segment and the second core segment are assembled, they form an integral two-segment skew pole structure and constitute a total skew pole angle of 2α; the magnet is embedded and fixed inside the magnet slot, and the rotor core is equipped with end plates at both ends of the axial direction, and the end plates are locked and fixed to the rotor core by fasteners to realize the axial positioning and fixing of each structural component.

[0010] As a further description of this technical solution, a flat key is fixedly mounted on the outer side of the rotating shaft. The flat key is in clearance fit with the keyway inside the mounting hole of the rotating shaft. Each rotor lamination is circumferentially positioned with the rotating shaft by the flat key, so that the rotor lamination and the rotating shaft rotate synchronously, preventing circumferential relative slippage between the stacked laminations and between the laminations and the rotating shaft.

[0011] As a further description of this technical solution, the two rotor cores are constrained by a flat key to form a reverse eccentric structure, and the total skew pole angle ranges from 4° to 6°, specifically 5°.

[0012] As a further description of this technical solution, the single set of magnet slots adopts a symmetrical inclined arrangement structure, specifically an "eight" shaped arrangement; multiple sets of magnet slots are distributed in an array along the circumference of the rotor laminations, the internal contour of the magnet slots is adapted to the shape of the magnet sheet, and the magnet sheet is assembled by interference fit or adhesive fixing.

[0013] As a further description of this technical solution, the fastener includes a fastening bolt, a locking nut, and an elastic anti-loosening washer; the fastening bolt passes through the auxiliary through hole, the locking nut is threaded onto the end of the fastening bolt, and the elastic anti-loosening washer is sandwiched between the locking nut and the contact surface of the end plate, for locking and fixing the two sections of rotor core and the two end plates, while preventing the fastener from loosening during long-term operation.

[0014] As a further description of this technical solution, the outer contour of the rotor lamination is composed of multiple segments of evenly distributed arc surfaces at equal angles, specifically 6 segments of arc surfaces; the radius of a single arc segment ranges from 35.10mm to 35.20mm, and the included angle between the centers of two adjacent arc surfaces is 60°, forming an irregular rotor outer circle structure that is not perfectly circular; the irregular outer contour optimizes the air gap magnetic field waveform of the motor, reduces the harmonic distortion rate, and suppresses torque pulsation.

[0015] As a further description of this technical solution, the end plate has a central mounting hole, and the inner side of the central mounting hole is also provided with a keyway that is compatible with the rotating shaft and the flat key; the end plate has a number of connecting holes distributed in a circumferential array, and the number and position of the connecting holes correspond one-to-one with the auxiliary through holes on the rotor laminations. Fasteners pass through the connecting holes and the auxiliary through holes to achieve axial locking between the end plate and the rotor core.

[0016] As a further description of this technical solution, the center of the connecting hole on the end plate is located on the horizontal reference line of the rotor axis, and the auxiliary through hole of the rotor lamination is eccentrically deflected relative to the horizontal reference line. The eccentric deflection angle α ranges from 2° to 3°, specifically 2.5°. The connecting hole and the auxiliary through hole form a misaligned fitting structure to match the eccentric position of the iron core after flipping, ensuring smooth assembly of the fasteners without interference.

[0017] As a further description of this technical solution, the rotor laminations are formed by stamping cold-rolled silicon steel sheets, and the lamination surfaces are treated with an insulating coating; the stacking thickness of the two rotor core sections is equal or proportionally differentiated, and the stacking thickness ratio of the two core sections can be adjusted according to the motor power and speed requirements.

[0018] As a further description of this technical solution, the magnetic steel sheet is made of neodymium iron boron permanent magnet material, and an anti-corrosion coating is provided on the surface of the magnetic steel sheet; an anti-detachment limiting step is provided at the end of the magnetic steel groove to limit the axial and radial displacement of the magnetic steel sheet and improve the assembly stability of the magnetic steel sheet.

[0019] As a further description of this technical solution, the auxiliary through holes and connecting holes are all smooth through holes, and the hole diameter is 0.2-0.5mm larger than the outer diameter of the fastening bolt screw, with a reserved assembly gap; the end plate is made of high-strength alloy sheet by stamping, and the thickness of the end plate ranges from 2mm to 5mm.

[0020] A permanent magnet synchronous motor includes a stator assembly and a two-stage skewed permanent magnet synchronous motor rotor structure as described in any one of claims 1-11.

[0021] Its beneficial effects are as follows: 1. The rotor core of this technical solution is formed by stacking the same type of laminations to form a two-section structure, which can be achieved with only one set of rotor lamination molds. There is no need to open multiple sets of lamination molds of different specifications, which completely solves the problem of traditional segmented skewed pole rotors requiring multiple sets of lamination molds and high mold opening costs. At the same time, the shaft adopts a single keyway shaft, which is different from the traditional multi-keyway shaft. There is no need to open multiple sets of angular keyways on the shaft, which greatly reduces the processing difficulty and manufacturing cost of the shaft. The auxiliary through holes on the laminations are precisely matched with the connecting holes on the end plate, and the fasteners are directly inserted and locked. There is no need to add additional bonding structures or complex positioning parts, which further reduces the input of parts and assembly costs and is suitable for large-scale mass production.

[0022] 2. During assembly, this technical solution eliminates the need to distinguish between multiple sets of rotor laminations. Simply stack the same type of rotor laminations in the forward direction and then flip them 180° to form two core segments with opposite eccentric directions. This eliminates the need to align multiple keyways, completely solving the problems of cumbersome and error-prone assembly in traditional segmented skew-pole rotors. The keyway-equipped shaft mounting hole at the center of the rotor lamination precisely matches the flat key on the shaft, enabling rapid circumferential positioning of the rotor lamination and shaft, preventing rotor lamination misalignment during stacking. The connecting holes on the end plate correspond one-to-one with the auxiliary through holes on the rotor laminations, and the center of the connecting hole matches the eccentric position of the auxiliary through hole, ensuring smooth fastener insertion without assembly interference. This further simplifies the assembly process, improves assembly efficiency, and reduces assembly errors.

[0023] 3. In this technical solution, the center of the auxiliary through hole on the rotor lamination is located on the axis deflected by 2.5° from the horizontal baseline of the rotor axis. Combined with the forward and 180° flipping stacking method of the rotor laminations, and the precise fit between the shaft key and the lamination keyway, the eccentricity directions of the two rotor core segments are opposite, ultimately forming a two-segment skew pole structure with a total skew pole angle of 5°. The skew pole angle is directly determined by the eccentricity structure and flipping method of the rotor laminations themselves, without the need for adjustment by keyway fit, thus completely solving the problems of poor skew pole angle consistency and large angle deviation in traditional segmented skew pole rotors. At the same time, the magnet slots are distributed in a figure-eight shape, which can ensure the permanent magnet is firmly embedded and the magnetic field is evenly distributed. Combined with the segmented skew pole structure, it effectively reduces motor harmonic interference, reduces back EMF waveform distortion, improves motor control accuracy, and solves the problems of large torque pulsation and poor vibration and noise suppression in traditional rotors. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the rotor core structure of the present invention; Figure 3 This is a cross-sectional structural schematic diagram of the present invention; Figure 4 This is a schematic diagram of the structure of the lamination of the present invention; Figure 5 This is a schematic diagram of the end plate of the present invention.

[0025] In the diagram, 1 is the rotating shaft; 2 is the rotor core; 3 is the magnet; 4 is the end plate; 5 is the rotor lamination; 6 is the rotating shaft mounting hole; 7 is the magnet slot; 8 is the auxiliary through hole; 9 is the fastener; 10 is the flat key; 11 is the fastening bolt; 12 is the lock nut; 13 is the connecting hole; and 14 is the center mounting hole. Detailed Implementation

[0026] First, let me explain the design intent of this invention. Existing segmented skew-pole permanent magnet rotors, besides being complex to assemble, costly, and structurally cumbersome, also suffer from poor skew angle consistency, discontinuous magnetic circuits, weak rotor rigidity, and susceptibility to high-temperature bonding failure. This results in large motor torque pulsation, poor vibration and noise suppression, and high-speed operation prone to rotor slippage, deformation, and permanent magnet demagnetization. Back EMF waveform distortion also affects control accuracy. Therefore, existing segmented skew-pole rotor technology struggles to simultaneously address noise reduction, control accuracy, and the demands of large-scale production, failing to meet the high-performance and high-reliability requirements of new energy vehicles, high-end servo applications, and other fields. Therefore, this invention designs a single-laminated, two-segment skew-pole permanent magnet synchronous motor rotor structure. The technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] Please see Figures 1-5 The present invention discloses a rotor structure for a two-segment skew-pole permanent magnet synchronous motor with a single lamination, including a shaft 1, a rotor core 2, a magnetic steel sheet 3 and an end plate 4; the shaft 1 is a single keyway structure shaft, used to realize the circumferential positioning and torque transmission of the rotor core 2.

[0028] The rotor core 2 is formed by stacking and splicing rotor laminations 5 of the same specification to form a two-section core structure. The two core sections are arranged axially and are designated as the first core section and the second core section, respectively. The first core section is formed by stacking rotor laminations 5 in a forward direction, while the second core section is formed by stacking rotor laminations 5 of the same type after rotating them 180° around their central plane. In this embodiment, the stacking thickness of the two core sections is equal. In actual production, the stacking thickness ratio of the two core sections can be adjusted according to the motor power and speed requirements to adapt to different operating conditions. The rotor laminations 5 are made of cold-rolled silicon steel sheets and are coated with an insulating coating to reduce eddy current losses and improve motor efficiency.

[0029] The rotor lamination 5 has a shaft mounting hole 6 at its center, which is adapted to the installation of the shaft 1. The inner side wall of the shaft mounting hole 6 is provided with a positioning keyway. A flat key 10 is fixedly mounted on the outer side of the shaft 1. The flat key 10 is clearance-fitted with the keyway, so that each rotor lamination 5 can be circumferentially positioned with the shaft 1, ensuring that the rotor lamination 5 and the shaft 1 rotate synchronously. This effectively prevents circumferential relative slippage between the stacked laminations and between the laminations and the shaft 1, and improves the overall structural strength and operational stability of the rotor.

[0030] The rotor lamination 5 has multiple sets of magnet slots 7 evenly arranged along the circumference. Each set of magnet slots 7 adopts a symmetrical inclined arrangement structure, specifically a figure-eight arrangement. The internal contour of the magnet slots 7 matches the shape of the magnet sheet 3. The magnet sheet 3 is made of neodymium iron boron permanent magnet material, and the surface of the magnet sheet 3 is provided with an anti-corrosion coating to delay oxidation corrosion and extend its service life. The magnet sheet 3 is assembled into the magnet slot 7 by interference fit or adhesive fixing, and the end of the magnet slot 7 is provided with an anti-detachment limiting step, which can limit the axial and radial displacement of the magnet sheet 3, prevent the magnet sheet 3 from loosening or falling off during high-speed operation, and improve assembly stability.

[0031] The rotor lamination 5 also has several auxiliary through holes 8 distributed circumferentially. These auxiliary through holes 8 are eccentrically deflected by a preset angle α relative to the horizontal baseline of the rotor axis. In this embodiment, the eccentric deflection angle α is specifically 2.5°, with a range of 2°-3°. This invention, through the lamination's own eccentric structure combined with the circumferential limiting of the flat key, creates a circumferentially reversed eccentric arrangement between the first iron core segment stacked in the forward direction and the second iron core segment stacked after being flipped 180°. The magnet offset angles of the two iron core segments are superimposed, ultimately forming a total skew pole angle 2α. In this embodiment, the total skew pole angle is specifically 5°, with a range controlled between 4°-6°. The eccentrically set auxiliary through holes are only used to adapt to the assembly position after flipping, serving to avoid interference and do not determine the skew pole angle. Using this structure, there is no need to process laminations of various specifications; simply using the same type of lamination stacked in both directions can accurately achieve the skew pole effect, resulting in high consistency of the skew pole angle, convenient assembly, and significantly reduced mold development costs.

[0032] The outer contour of the rotor lamination 5 is composed of six evenly distributed arc surfaces at equal angles. The included angle between the centers of two adjacent arc surfaces is 60°, and the radius of a single arc is controlled within the range of 35.10mm-35.20mm, forming an irregular rotor outer circle that is not perfectly circular. This structure can effectively optimize the air gap magnetic field waveform of the motor, weaken air gap harmonics, reduce harmonic distortion rate, suppress motor torque pulsation, improve motor operating vibration and noise, and enhance motor control accuracy.

[0033] Both ends of the rotor core 2 are equipped with end plates 4. The end plates 4 are made of high-strength alloy sheet material and are stamped. The thickness of the end plates ranges from 2mm to 5mm, resulting in high structural strength and strong resistance to deformation. A central mounting hole 14 is provided in the center of the end plate 4. A keyway is also provided on the inner side of the central mounting hole 14, which is adapted to the rotating shaft 1 and the flat key 10. Several connecting holes 13 are also provided on the end plate 4 in a circumferential array. The number and position of the connecting holes 13 correspond one-to-one with the auxiliary through holes 8 on the rotor lamination 5.

[0034] The auxiliary through hole 8 and the connecting hole 13 are both smooth through holes, and the hole diameter is 0.2-0.5mm larger than the outer diameter of the fastening bolt 11 screw, leaving a reasonable assembly gap to facilitate the insertion and installation of parts; the center of the connecting hole 13 on the end plate 4 is located on the horizontal reference line of the rotor axis, forming a misaligned adaptation structure with the eccentrically set auxiliary through hole 8, accurately matching the eccentric position of the iron core after flipping, ensuring smooth assembly of the fastener 9 without interference.

[0035] The auxiliary through hole 8 is equipped with a locking fastener 9, which includes a fastening bolt 11, a locking nut 12, and an elastic anti-loosening washer. The fastening bolt 11 passes through the connecting hole 13 and the auxiliary through hole 8 in sequence. The locking nut 12 is threaded onto the end of the fastening bolt 11. The elastic anti-loosening washer is sandwiched between the contact surface of the locking nut 12 and the end plate 4. The two sections of rotor core 2 and the two end plates 4 are locked and fixed by the fastener 9, realizing the axial limiting and fixing of each structural component. At the same time, the elastic compression of the elastic anti-loosening washer prevents the fastener 9 from loosening and falling off under long-term vibration of the motor, ensuring the overall assembly firmness of the rotor.

[0036] The present invention also discloses a permanent magnet synchronous motor, which includes a stator assembly and the aforementioned two-section skewed permanent magnet synchronous motor rotor structure. Relying on the advantages of low cost, low harmonics and high stability of this rotor structure, the overall performance of the motor is effectively optimized, and it is suitable for permanent magnet synchronous motor applications in various fields such as household and industrial applications.

[0037] In summary, this invention employs a single lamination design with a single keyway shaft, requiring only one lamination die to complete the machining and assembly of two skewed rotor sections. This simplifies the machining process and reduces manufacturing costs. By relying on the eccentric arrangement of auxiliary through holes and the positioning of flat keys, a precise and stable skewed pole effect is achieved. Combined with the optimization of the air gap magnetic field by the irregular rotor outer circle, harmonics are significantly reduced and torque pulsation is suppressed, effectively improving the motor's control accuracy, operational stability, and reliability. This invention is highly practical and suitable for large-scale industrial production.

[0038] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A rotor structure for a two-stage skewed permanent magnet synchronous motor with a single type of lamination, characterized in that, It includes a rotating shaft (1), a rotor core (2), magnetic steel sheets (3), and an end plate (4); the rotating shaft (1) is a single keyway structure rotating shaft (1); The rotor core (2) is formed by stacking and splicing rotor laminations (5) of the same specification to form a two-section core structure. The two sections are the first core section and the second core section. The first core section is formed by stacking rotor laminations (5) in the forward direction, and the second core section is formed by stacking rotor laminations (5) of the same type after rotating them 180° around their own central plane. The rotor lamination (5) has a shaft mounting hole (6) at its center for mounting the shaft (1), and the inner wall of the shaft mounting hole (6) has a positioning keyway; the rotor lamination (5) has multiple sets of magnet slots (7) evenly arranged along the circumference, and the magnet slots (7) are used to embed and fix permanent magnets; the rotor lamination (5) also has several auxiliary through holes (8) distributed along the circumference, and the auxiliary through holes (8) are eccentrically deflected by a preset angle α relative to the horizontal reference line of the rotor axis, and the auxiliary through holes (8) are fitted with locking fasteners (9) inside; After the first iron core segment and the second iron core segment are assembled and combined, they form an integral two-segment skew pole structure and constitute a total skew pole angle 2α; the magnetic steel sheet (3) is embedded and fixed inside the magnetic steel groove (7), and the rotor iron core (2) is equipped with end plates (4) at both ends of the axial direction, and the end plates (4) are locked and fixed to the rotor iron core (2) by fasteners (9) to realize the axial positioning and fixing of each structural component.

2. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, A flat key (10) is fixedly mounted on the outside of the rotating shaft (1). The flat key (10) is in clearance fit with the keyway inside the mounting hole of the rotating shaft (1). Each rotor lamination (5) is circumferentially positioned with the rotating shaft (1) by the flat key (10), so that the rotor lamination (5) and the rotating shaft (1) rotate synchronously, preventing circumferential relative slippage between the stacked laminations and between the laminations and the rotating shaft (1).

3. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 2, characterized in that, The two rotor cores (2) are constrained by a flat key (10) to form a reverse eccentric structure. The total skew pole angle ranges from 4° to 6°, specifically 5°.

4. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, The single set of magnetic steel slots (7) adopts a symmetrical inclined arrangement structure, specifically an "eight" shaped arrangement; multiple sets of magnetic steel slots (7) are distributed in a circumferential array along the rotor laminations (5), the internal contour of the magnetic steel slots (7) is adapted to the shape of the magnetic steel sheet (3), and the magnetic steel sheet (3) is assembled by interference fitting or adhesive fixing.

5. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, The fastener (9) includes a fastening bolt (11), a locking nut (12), and an elastic anti-loosening washer; the fastening bolt (11) passes through the auxiliary through hole (8), the locking nut (12) is threaded onto the end of the fastening bolt (11), and the elastic anti-loosening washer is sandwiched between the contact surface of the locking nut (12) and the end plate (4) to lock and fix the two sections of rotor core (2) and the two end plates (4) at the same time to prevent the fastener (9) from loosening during long-term operation.

6. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, The outer contour of the rotor lamination (5) is composed of multiple segments of evenly distributed arc surfaces at equal angles, specifically 6 segments of arc surfaces; the radius of a single arc segment ranges from 35.10mm to 35.20mm, and the included angle between the centers of two adjacent arc surfaces is 60°, forming an irregular rotor outer circle structure that is not perfectly circular; the irregular outer contour optimizes the air gap magnetic field waveform of the motor, reduces the harmonic distortion rate, and suppresses torque pulsation.

7. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, The end plate (4) has a central mounting hole (14) in the center. The inner side of the central mounting hole (14) is also provided with a keyway that is compatible with the rotating shaft (1) and the flat key (10). The end plate (4) has a number of connecting holes (13) arranged in a circumferential array. The number and position of the connecting holes (13) correspond one-to-one with the auxiliary through holes (8) on the rotor lamination (5). The fastener (9) passes through the connecting holes (13) and the auxiliary through holes (8) to achieve axial locking between the end plate (4) and the rotor core (2).

8. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 7, characterized in that, The center of the connecting hole (13) on the end plate (4) is located on the horizontal reference line of the rotor axis. The auxiliary through hole (8) of the rotor lamination (5) is eccentrically deflected relative to the horizontal reference line. The eccentric deflection angle α ranges from 2° to 3°, specifically 2.5°. The connecting hole (13) and the auxiliary through hole (8) form a misaligned fitting structure to match the eccentric position of the iron core after flipping, ensuring that the fastener (9) is assembled smoothly without interference.

9. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, The rotor lamination (5) is formed by stamping cold-rolled silicon steel sheet, and the surface of the lamination is treated with an insulating coating. The stacking thickness of the two rotor cores (2) is equal or set differently according to a ratio. The stacking thickness ratio of the two cores can be adjusted according to the motor power and speed requirements.

10. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 1, characterized in that, The magnetic steel sheet (3) is made of neodymium iron boron permanent magnet material, and the surface of the magnetic steel sheet (3) is provided with an anti-corrosion coating; the end of the magnetic steel groove (7) is provided with an anti-detachment limiting step to limit the axial and radial displacement of the magnetic steel sheet (3) and improve the assembly stability of the magnetic steel sheet (3).

11. The rotor structure of a two-stage skewed permanent magnet synchronous motor with a single lamination as described in claim 5, characterized in that, The auxiliary through hole (8) and the connecting hole (13) are both smooth through holes, and the hole diameter is 0.2-0.5mm larger than the outer diameter of the fastening bolt (11) screw, with a reserved assembly gap; the end plate (4) is made of high-strength alloy plate by stamping, and the thickness of the end plate (4) is in the range of 2mm-5mm.

12. A permanent magnet synchronous motor, characterized in that, It includes the stator assembly and the rotor structure of the two-segment skew-pole permanent magnet synchronous motor as described in any one of claims 1-11.

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