Heavy load high-power high-speed permanent magnet synchronous motor and design method thereof

Abstract

The application provides a heavy-load high-power high-speed permanent magnet synchronous motor and a design method thereof, and belongs to the field of motor design and manufacturing. The application solves the problem of poor overall reliability of the heavy-load high-power high-speed permanent magnet synchronous motor caused by insufficient structural strength, heat dissipation efficiency and operation stability. The motor comprises a base, a stator, a rotor and tiltable bearing, the stator is composed of segmented cores, the radial ventilation channels are formed by tooth pressure strips between the segments, the stator winding adopts Litz coils with unequal edge structures, the rotor comprises a rotating shaft and a plurality of rotor segmented units arranged along the axial direction, the radial ventilation gaps are formed between the units, each unit comprises a rotor core segment, a permanent magnet and a carbon fiber sheath segment wrapped outside, the rotating shaft is provided with an axial ventilation groove, and the rotor is supported by the tiltable bearing. The segmented stator and rotor cores and the multi-path ventilation structure are coordinated, and the heat dissipation capacity, mechanical strength and operation stability are enhanced.

Description

Technical Field

[0001] This invention belongs to the field of electric motor design and manufacturing technology, and in particular relates to a heavy-duty, high-power, high-speed permanent magnet synchronous motor and its design method. Background Technology

[0002] High-power high-speed permanent magnet synchronous motors have shown broad application prospects in high-speed drive, compressed energy storage, and high-end equipment due to their advantages such as high power density, compact structure, and fast dynamic response. High-power high-speed permanent magnet synchronous motors usually refer to motors with power levels reaching megawatt level and speeds up to about 10,000 r / min. Heavy load means that the motor operates continuously near its rated power point for a long time and bears extremely large radial and axial loads. The dynamic load borne by its bearings reaches tens of kilonewtons, and it needs to have the ability to overload or change speed. However, the design of a motor that combines high power, high speed, and heavy load faces a series of interdependent technical challenges, and its overall reliability has become a key bottleneck restricting the development of high-power high-speed permanent magnet synchronous motors.

[0003] The immense centrifugal force generated by high-speed operation poses a major threat to the structural strength of the rotor. The permanent magnets in the rotor experience extremely high centrifugal stress during high-speed rotation, easily leading to magnet detachment, rotor core deformation, and even structural damage. However, as the power rating of the motor increases, the amount and volume of permanent magnets required to generate a sufficient magnetic field increase accordingly, further amplifying the centrifugal force they experience. At this point, simply increasing the thickness of the sheath to improve the tightening effect will have diminishing returns, and a thicker sheath will severely hinder heat dissipation from the rotor, exacerbating rotor temperature rise. This demonstrates a significant trade-off between structural reinforcement and heat dissipation efficiency. Furthermore, high-power operation is accompanied by a significant increase in various losses, including DC copper losses and AC losses in the stator windings, high-frequency iron losses in the core, eddy current losses in the rotor magnets, and wind-induced wear losses at high speeds. These losses ultimately convert into heat. If this heat cannot be dissipated in a timely and efficient manner, it will cause a sharp rise in the temperature of the motor, especially the rotor and stator windings. Excessive temperature rise... This not only accelerates insulation aging, but more importantly, it may cause irreversible high-temperature demagnetization of permanent magnets, resulting in permanent degradation of motor performance. Although existing cooling technologies are widely used, under extreme conditions of heavy load, high power, and high speed, the heat exchange efficiency of traditional cooling structures is insufficient to meet heat dissipation requirements. Insufficient heat dissipation capacity has become a core obstacle limiting further increases in motor power density. At the same time, heavy-load operating conditions place extremely high demands on the shaft dynamics and operational stability of the motor. Heavy loads not only mean that bearings need to withstand greater radial and axial loads, leading to a sharp increase in temperature rise pressure and oil film stiffness requirements, posing a great challenge to bearing selection and design, but also profoundly affect the critical speed distribution and overall mode of the rotor system. If the design is inappropriate, the operating speed may approach or exceed the critical speed, causing severe vibration. At the same time, the excitation under heavy loads may induce harmful structural modes, resulting in excessive vibration and noise, shortened bearing life, and seriously threatening the long-term stable operation and service life of the motor. Summary of the Invention

[0004] In view of this, the present invention aims to propose a heavy-load, high-power, high-speed permanent magnet synchronous motor and its design method, so as to solve the technical problem of poor overall reliability of heavy-load, high-power, high-speed permanent magnet synchronous motors due to insufficient structural strength, heat dissipation efficiency and operational stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a heavy-duty, high-power, high-speed permanent magnet synchronous motor, comprising a frame, a stator, a rotor, and a tilting pad sliding bearing. The stator includes a stator core and a stator winding. The stator core comprises multiple axially arranged core segments, adjacent core segments being spaced apart by toothed strips to form radial ventilation channels. Each core segment is formed by stacking multiple stator laminations. The lamination slots on each stator lamination, after stacking, collectively form the stator slot of the core segment. The stator slot includes a slot body for accommodating the stator winding and a slot extension located radially outward of the slot body. The slot extensions of each stator lamination are axially aligned to form an axial ventilation channel. Stator pressure rings are provided on both sides of the stator core. The stator winding is a coil wound with an unequal side structure using Litz wire. The rotor is disposed inside the stator core. The rotor includes a shaft and multiple rotor segment units spaced apart along the shaft axially. The multiple rotor segment units are arranged along the shaft axially... The shafts are arranged axially at intervals, forming radial ventilation gaps between adjacent units. Each rotor segment unit includes a rotor core segment, permanent magnets, and partitions. Multiple permanent magnets are spaced apart on the outer periphery of the rotor core segment, and partitions are provided between adjacent permanent magnets. Each rotor segment unit is wrapped with a carbon fiber sheath. The outer circumferential surface of the shaft has multiple ventilation slots extending axially. The multiple ventilation slots are distributed circumferentially along the shaft, and the axial extension range of the ventilation slots corresponds to the overall axial range of all rotor segment units. The frame includes a frame body and a support part. The frame body and the support part are welded together. The stator is disposed in the frame body, and the support part is disposed at the bottom of the frame body. The cross-section of the support part is trapezoidal. Tilting pad sliding bearings are installed at both ends of the frame. The shaft is supported by the tilting pad sliding bearings. The radial ventilation duct, axial ventilation channel, radial ventilation gap, and ventilation slots are interconnected, forming the internal cooling air path of the motor. Furthermore, the base body includes a top plate, a front wall plate, a rear wall plate, a base plate, and side wall plates. The top plate, front wall plate, rear wall plate, base plate, and side wall plates enclose to form a cylindrical base body. Multiple axially extending support ribs are evenly arranged along the circumferential direction on the inner wall of the base body. The support ribs are connected to the stator. The base body also has ring stiffener plates and axial steel pipes. The ring stiffener plates are located on both sides of the stator core along the axial direction and are connected to the inner wall of the base body. The multiple axial steel pipes are distributed along the circumferential direction of the center line of the stator core.

[0006] Furthermore, the support includes trapezoidal ring stiffeners on both sides, cross-connected I-beams, a large-diameter steel pipe and steel plate extending axially along the machine base body, the lower ends of the trapezoidal ring stiffeners on both sides expanding outward, the cross-connected I-beams being located at the internal center of the support, the large-diameter steel pipe extending axially along the machine base body, and the trapezoidal ring stiffeners, cross-connected I-beams and side wall plates being welded together by multiple sections of steel plates.

[0007] Furthermore, the top plate is provided with an air inlet and an air outlet, and both ends of the machine base body are provided with wind baffles. The wind baffles are located at the ends of the stator windings. An air guide structure is provided between the air outlet of the top plate and the wind baffles. Ventilation grooves are provided on the ring rib plate.

[0008] Furthermore, a cooler is installed on the top of the base. The cooler is a square box-type air-water cooled structure, and independent centrifugal cooling fans are provided at both ends of the cooler. The air inlet and air outlet of the top plate of the base are connected to the air duct inside the cooler and the base.

[0009] Furthermore, the base is also equipped with multiple junction boxes.

[0010] Furthermore, the portion of the rotating shaft that mates with each rotor core segment is stepped, forming multiple shaft segments connected sequentially with different diameters; two rotor core segments are fitted onto each shaft segment; a keyway extending axially is provided on the rotating shaft, and the rotor core segments are fixedly connected to the rotating shaft by keys and bolts that mate with the keyways; rotor baffles are provided on both axial sides of the rotor core segments, with one rotor baffle abutting against the stepped surface of the rotating shaft, and the other rotor baffle being fixed to the rotating shaft by an arc key.

[0011] Furthermore, the permanent magnet is made of samarium cobalt permanent magnet material, and the permanent magnet corresponding to each magnetic pole is divided into multiple pieces along the circumference, and the surface of each permanent magnet is galvanized; each rotor core section is machined with a magnetic steel groove for accommodating and positioning the permanent magnet corresponding to each magnetic pole.

[0012] Furthermore, a temperature sensing element is installed on the tilting pad sliding bearing.

[0013] A design method for a heavy-duty, high-power, high-speed permanent magnet synchronous motor includes the following steps: S1: Based on the rated speed of the motor, the number of poles is determined to be 4~8 poles, and the grade and thickness of silicon steel sheets for stator laminations are selected according to the operating frequency; the stator slot shape is designed, and the slot height is raised to not less than 6mm to form a ventilation channel; Litz wire is selected to design a stator winding with an unequal side structure; the electromagnetic air gap is determined, and the thickness of the carbon fiber sheath, i.e., the structural air gap, is determined iteratively based on the sheath stress analysis; samarium cobalt permanent magnet material is selected as the rotor magnet, and the magnetic circuit is designed. S2: The stator core is divided into multiple segments along the axial direction, and radial ventilation channels with toothed pressure bars are set between adjacent segments; the rotor core, permanent magnet and carbon fiber sheath are designed as axial segmented structures corresponding to the number of stator core segments, and radial ventilation gaps are formed between the segments; in the core mating section of the shaft, multiple axially extending ventilation slots are evenly distributed around the circumference; air inlets and outlets are designed on the top plate of the frame; and baffles, air guide structures and ring rib ventilation slots are designed inside the frame to guide and optimize the cooling air path. S3: Design the base so that the base body and the support part are integrally formed, and the cross-section of the support part is trapezoidal; design circumferentially distributed axial support ribs, thickened ring rib plates and axially extending steel pipes in the base body; design cross-shaped I-beams, through large-diameter steel pipes and multi-section support plates welded to them in the support part of the base; design the rotating shaft so that the part that mates with the rotor core section is stepped, and fix the rotor core section by keys and bolts; S4: Based on the rotor dynamics calculation results, iteratively select tilting pad sliding bearings and verify their oil film stiffness, temperature rise and life in heavy load and speed regulation range; S5: Based on the above integrated design results, manufacture and assemble the heavy-duty high-power high-speed permanent magnet synchronous motor.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes an axial ventilation duct formed by aligning the slot extensions of the stator laminations in the axial direction, connected in series with a radial ventilation duct formed by the toothed core segments. Simultaneously, radial ventilation gaps are formed between the rotor segment units and communicate with axially distributed ventilation slots on the rotor shaft, collectively constituting a circulating airflow path within the motor. This circulating airflow path directly guides cooling air to the stator windings, core, and permanent magnets—the core heat-generating areas—effectively reducing the temperature rise of the main heat-generating components. This provides a crucial guarantee for the motor to achieve continuous operation under heavy loads and high power. Furthermore, both the stator and rotor cores adopt an axially segmented design, which facilitates the manufacturing and stacking of the cores. In addition to heat dissipation, it also helps to suppress eddy current losses. The segmented rotor core sections are fixed with the stepped shaft and secured with keys and bolts, ensuring the alignment and connection reliability of each section under high-speed operation. This achieves the unity of modular design and high-performance requirements. Furthermore, the wind baffle, air guide structure, and ring stiffener with ventilation slots are optimized inside the frame to guide the cooling airflow to flow efficiently along the designed air duct through the stator winding ends, the radial ventilation duct of the core, and the rotor surface. This forms a forced, directional, and efficient cooling circulation system that can promptly remove the large amount of heat generated by copper loss, iron loss, eddy current loss, and wind wear loss, effectively controlling the temperature rise of the windings and permanent magnets and avoiding high-temperature demagnetization. 2. The stator winding of the present invention is made of Litz wire, which effectively suppresses the skin effect and proximity effect caused by high-frequency current under high-speed operation, and significantly reduces the AC loss of the stator winding. The Litz wire adopts a coil with an unequal side structure, which shortens the winding end length and reduces the amount of copper used, thereby reducing the DC copper loss and end heating of the winding. The combination of the two significantly improves the operating efficiency and power density of the motor under high-speed conditions. 3. Each rotor segment unit of the present invention is wrapped with a carbon fiber sheath. The carbon fiber sheath provides the rotor with extremely high radial binding force, which can resist the huge centrifugal force generated by high-speed rotation and prevent the permanent magnet from flying away, thus fundamentally solving the core problem of the mechanical strength of the rotor of high-speed permanent magnet motor. 4. The base of the present invention adopts a base structure in which the base body and the support part are welded together and the cross section of the support part is trapezoidal. This greatly enhances the load-bearing rigidity and deformation resistance of the whole machine, provides a stable mechanical foundation for heavy-load operation, increases the bottom support span and the overall bending and torsional rigidity of the structure, optimizes the load distribution, enables the motor to withstand heavy loads and effectively resist vibration and overturning moment during operation, and ensures installation stability. The base is provided with circumferentially distributed axial support ribs, thickened ring rib plates and axially extended steel pipes. The support part is provided with cross-shaped I-beams and through large-diameter steel pipes, forming a high-strength and high-rigidity internal skeleton, ensuring the positioning accuracy of the stator core and the stability of the whole machine structure under complex stress. 5. This invention employs tilting pad sliding bearings as the support for the rotating shaft. These bearings possess excellent oil film formation capability and self-aligning function, providing the necessary high oil film stiffness for heavy-load operation, effectively suppressing vibration, and adapting to a certain range of speed variations. Temperature sensing elements are installed on the tilting pad sliding bearings to facilitate real-time monitoring of the bearing's operating temperature, providing a direct means to assess its operating status and prevent lubrication failure due to excessive temperature rise, thus improving the safety of the bearing system. The segmented rotor design and internal ventilation structure enhance heat dissipation while also optimizing the rotor's mass distribution. Combined with a high-strength, high-rigidity frame and bearing structure, a stable support environment is provided for the entire shaft system, helping to push the critical speed of the rotor system away from the operating speed range and increase the overall modal frequency, thereby suppressing vibration and noise under heavy-load and variable-speed operation, and extending the service life of the motor. Attached Figure Description

[0015] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the shaft side structure of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 2 This is a schematic diagram of the stator shaft side structure of a heavy-duty high-power high-speed permanent magnet synchronous motor according to the present invention. Figure 3 This is a cross-sectional view of the stator structure of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 4 This is a schematic diagram of the axial structure of the stator lamination of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 5 This is a front view schematic diagram of the stator lamination structure of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 6 for Figure 5 Enlarged structural diagram at point A; Figure 7 This is a schematic diagram of the axial structure of the tooth pressure bar of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 8 This is a front view schematic diagram of the rotor structure of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 9 This is a cross-sectional view of the rotor of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 10 This is a schematic diagram of the shaft side structure of the frame of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention. Figure 11 This is a schematic diagram of the shaft side structure of the base of a heavy-duty, high-power, high-speed permanent magnet synchronous motor without a front wall panel, as described in this invention. Figure 12 This is a front view schematic diagram of the frame structure of a heavy-duty, high-power, high-speed permanent magnet synchronous motor without a front wall panel, as described in this invention. Figure 13 This is a front view schematic diagram of the ring stiffener plate of a heavy-duty, high-power, high-speed permanent magnet synchronous motor according to the present invention.

[0016] In the picture: 1. Frame; 2. Tilting pad sliding bearing; 3. Stator core; 4. Stator winding; 5. Toothed bar; 6. Shaft; 7. Rotor core section; 8. Permanent magnet; 9. Carbon fiber sheath; 10. Top plate; 11. Front wall plate; 12. Rear wall plate; 13. Support rib; 14. Ring rib plate; 15. Axial steel pipe; 16. Trapezoidal ring rib plate; 17. Cross-connected I-beams; 18. Large-diameter steel pipe; 19. Steel plate; 20. Wind baffle; 21. Cooler; 22. Junction box; 23. Rotor baffle; 24. Foot plate; 25. Side wall plate; 26. Stator pressure ring; 27. Slot extension. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0018] Detailed implementation method: See Figure 1-10This embodiment includes a frame 1, a stator, a rotor, and a tilting pad bearing 2. The frame 1 is used to improve the structural strength and stability of the permanent magnet synchronous motor, thereby coping with the effects of heavy loads and axial forces. The stator is used to generate a rotating magnetic field and realize the electromagnetic energy conversion of the motor. The rotor is used to rotate under the drive of the stator's rotating magnetic field and output torque. The tilting pad bearing 2 is used to support the rotor's shaft 6. The stator includes a stator core 3 and a stator winding 4. The stator core 3 includes multiple axially arranged core segments, and adjacent core segments are spaced apart by toothed strips 5 to form radial ventilation channels. Each core segment is constructed by stacking multiple stator laminations. The stator laminations constitute the magnetic conductor of the stator core. These laminations are typically made of silicon steel sheets with a thickness of 0.2mm or 0.3mm. One side of the toothed pressure bar 5 is wedge-shaped and is inserted into the mounting hole of the corresponding stator lamination for fixation, dividing the stator core into multiple segments. This provides more heat dissipation surface area and airflow channels. The lamination slots on each stator lamination, after being stacked, form stator slots for the core segment. Each stator slot includes a slot body accommodating the stator winding 4 and a slot extension 27 located radially outward of the slot body. The slot extensions 27 of each stator lamination are axially aligned, forming an axial ventilation channel. The slot extensions 27 are used to form ventilation channels and are of considerable length. The 6mm diameter is used for ventilation, which helps dissipate heat from the stator winding 4. The stator winding 4 is used to pass in the rotating magnetic field generated by the current. The stator winding 4 is a coil with an unequal side structure wound from Litz wire. The unequal side structure coil is a trapezoidal coil. Litz wire can effectively suppress the skin effect and proximity effect at high frequencies, greatly reducing AC losses. The unequal side structure coil can effectively reduce the length of the stator winding 4 at the end, thereby reducing copper loss and controlling the temperature rise of the stator winding 4. The rotor is located inside the stator core 3, and an air gap is formed between the stator core 3 and the rotor, including an electromagnetic air gap and a structural air gap. The electromagnetic air gap is mainly used to optimize electromagnetic performance, and the structural air gap is mainly used to optimize electromagnetic performance. This is intended to address the issues of rotor mechanical strength and permanent magnet fixation at high speeds. The rotor includes a shaft 6 and multiple rotor segment units spaced apart along the axial direction of the shaft 6. These rotor segment units are arranged at intervals along the axial direction of the shaft 6 and form radial ventilation gaps between adjacent units. The shaft 6 supports rotor rotation and transmits torque. One end of the shaft 6 has end face teeth, and the other end has a double key. The axial space reserved between adjacent rotor segment units constitutes the radial ventilation gap. The radial ventilation gap and the radial ventilation duct on the stator together form a continuous cooling air path, allowing the cooling airflow to directly penetrate the rotor area, greatly improving the heat dissipation conditions of the permanent magnet 8 and reducing temperature rise.Each rotor segment unit includes a rotor core segment 7, permanent magnets 8, and partitions. Multiple permanent magnets 8 are spaced apart on the outer periphery of the rotor core segment 7, with partitions between adjacent permanent magnets 8. To reduce eddy current losses, each permanent magnet 8 corresponding to a magnetic pole is divided into multiple equal segments circumferentially for precise positioning and physical isolation of each permanent magnet 8, preventing displacement or collision under centrifugal force or thermal stress. Each rotor segment unit is externally wrapped with a carbon fiber sheath 9. The rotor core segment 7 is used to mount the permanent magnets 8 and form the rotor magnetic circuit. The carbon fiber sheath 9 provides the binding force required for high-speed rotation, preventing the permanent magnets 8 from... The cooling air is dispersed; the outer circumferential surface of the rotating shaft 6 is provided with multiple ventilation slots extending axially along it. These ventilation slots are distributed circumferentially along the rotating shaft 6, and their axial extension range corresponds to the overall axial range of all rotor segment units. Cooling air can enter each segment of the rotor segment unit through the ventilation slots, and combined with radial ventilation gaps, form an axial and radial ventilation structure, thereby achieving direct cooling of the rotor's interior; the base 1 includes a base body and a support portion. The base body and the support portion are welded together. The center of the base body is raised and reinforced by the support portion. The stator is disposed within the base body, and the support portion is disposed at the bottom of the base body. In the elevated position, the cross-section of the support is trapezoidal, which can significantly increase the support span and stability at the bottom, optimize load distribution, and thus improve the overall machine's anti-overturning and anti-torsion capabilities and overall modal performance. The tilting pad bearings 2 are installed at both ends of the base 1, and the rotating shaft 6 is supported by the tilting pad bearings 2. Each pad of the tilting pad bearing 2 can adaptively deflect to form an optimal oil wedge, thereby providing stable and high-rigidity oil film support over a wide speed range, effectively suppressing oil film oscillation, and meeting the requirements of high stability, high load-bearing capacity, and good damping characteristics of the shaft system under heavy-load and high-speed conditions. The radial ventilation channel, axial ventilation channel, radial ventilation gap, and ventilation slot are interconnected. The internal cooling airflow of the motor is formed by the frame 1. The cooling airflow enters the motor through the frame 1, first flowing through the ends of the stator windings 4 and cooling them via the axial ventilation channels. Then, the airflow flows from both ends towards the center of the shaft, splitting into two paths. One path enters the radial ventilation channels formed by the toothed bars 5 between the stator cores 3; the other path enters the rotor through the axial ventilation grooves on the surface of the shaft 6, and then flows out through the radial ventilation gaps between the rotor segments. These two airflows cool the stator and rotor respectively, then converge in the axial center of the stator cores 3, finally exiting upwards from the outlet in the middle of the frame 1, returning to the cooler 21 to complete heat exchange.

[0019] The base body includes a top plate 10, a front wall plate 11, a rear wall plate 12, a base plate 24, and a side wall plate 25. These components together form a cylindrical base body. Multiple axially extending support ribs 13 are evenly arranged along the circumferential direction on the inner wall of the base body. These support ribs 13 are connected to the stator and mate with the outer circle of the stator core 3, serving for radial positioning and fixation of the stator, determining assembly dimensions during stator assembly, and simultaneously reinforcing the base body. Function: The machine base body is also provided with ring stiffening plates 14 and axial steel pipes 15. The ring stiffening plates 14 are located on both sides of the stator core 3 and are connected to the inner wall of the machine base body. The ring stiffening plates 14 are used to enhance the local strength of the machine base 1 in the stator and rotor mounting areas. Ventilation slots are opened on the ring stiffening plates 14 to optimize the air path. Multiple axial steel pipes 15 are distributed along the circumferential direction of the center line of the stator core 3. The axial steel pipes 15 are used as reinforcing beams to further improve the overall structural rigidity and strength of the machine base 1 and improve the vibration mode of the machine base 1.

[0020] The support section includes trapezoidal ring stiffener plates 16 on both sides, cross-connected I-beams 17, a large-diameter steel pipe 18 and a steel plate 19 that run through the machine base body axially. The lower ends of the trapezoidal ring stiffener plates 16 on both sides expand outward. The cross-connected I-beams 17 are located at the internal center of the support section and are usually arranged along the axial direction of the machine base 1. The large-diameter steel pipe 18 runs through the machine base body axially. The trapezoidal ring stiffener plates 16, the cross-connected I-beams 17 and the side wall plates 25 are welded together by multiple sections of steel plate 19. Through dense cross-support and welding, the support section is transformed into a high-rigidity, high-strength integral frame, which can effectively resist deformation caused by heavy loads and complex axial forces. It is the core internal skeleton that ensures the structural stability of the machine base 1.

[0021] The top plate 10 has an air inlet and an air outlet. The air inlet is usually located near the end of the stator winding 4, and the air outlet is located in the center area of ​​the armature axial length, thus ensuring a reasonable distribution of air pressure and air volume. Both ends of the base body are provided with baffles 20, which are located at the ends of the stator winding 4, thereby guiding the cooling airflow to flow concentratedly over the end surface of the stator winding 4, achieving effective forced cooling of the ends of the stator winding 4 and preventing airflow short-circuiting or dissipation. The air outlet of the top plate 10... An air guide structure is provided between the air baffle 20 and the air guide structure. The air guide structure can optimize the airflow direction, so that the hot air flowing out from the radial ventilation channel can be smoothly guided to the air outlet of the top plate 10, reducing wind resistance and eddies and improving cooling efficiency. A ventilation groove is provided on the ring rib plate 14. The ventilation groove is an annular groove that communicates with the inner cavity of the base body 1. The ventilation groove allows the airflow cooling the end of the stator winding 4 to pass through and enter the next cycle or merge into the main air path, ensuring the smooth circulation of the air path, thereby optimizing the overall air path structure of the motor.

[0022] A cooler 21 is installed on the top of the base 1. The cooler 21 is an air-water cooler. Cooling water flows inside the cooler 21. When the circulating hot air inside the motor flows through the cooler, it is cooled, thus achieving heat exchange. Independent centrifugal cooling fans are provided at both ends of the cooler 21 to drive the air inside the motor to circulate in a closed loop, forming a double-circulation radial ventilation. The air inlet and air outlet of the top plate 10 of the base 1 are connected to the cooler 21 and the air passage inside the base 1.

[0023] The base 1 is also equipped with multiple junction boxes 22, including a main junction box, a temperature measuring junction box, and a heater junction box. The main junction box is used to connect and lead out the neutral point of the stator winding 4 to achieve reliable electrical connection and protection. The temperature measuring junction box is used to centrally connect the leads of the temperature sensor embedded in the stator core 3 or the stator winding 4 so as to monitor the internal temperature of the motor in real time. The heater junction box is used to provide a power input port for the moisture-proof heater installed in the base 1, so as to provide power for heating during motor shutdown to prevent the stator winding 4 from getting damp. Each junction box 22 together provides the necessary and fully protected electrical interface for the motor.

[0024] The portion of the rotating shaft 6 that mates with each rotor core segment 7 is stepped, forming multiple sequentially connected shaft segments of different diameters. The section where the rotating shaft 6 mates with the rotor core segment 7 is machined into multiple shaft segments with progressively varying diameters. Each shaft segment is fitted with two rotor core segments 7, facilitating the axial positioning and assembly of the rotor core segments 7. Two rotor core segments 7 are fitted onto each shaft segment. The rotating shaft 6 has a keyway extending axially. The rotor core segments 7 are fixedly connected to the rotating shaft 6 by keys and bolts that mate with the keyways. The inner hole of the rotor core segment 7 is equipped with a corresponding keyway. Torque is transmitted through the keys, and the rotor core segments 7 are tightly fixed to the rotating shaft 6 by axial bolts to prevent circumferential and axial displacement during high-speed operation. Rotor baffles 23 are provided on both axial sides of the rotor core segment 7. One side of the rotor baffle 23 abuts against the stepped surface of the rotating shaft 6, and the other side of the rotor baffle 23 is fixed to the rotating shaft 6 by an arc key, avoiding the difficulty of welding on the high-strength forged steel rotating shaft 6.

[0025] The permanent magnet 8 is made of samarium cobalt permanent magnet material. Samarium cobalt material has a high Curie temperature and operating temperature, and can better withstand the high temperature rise that may occur in the rotor of a high-speed, high-power motor, thereby significantly reducing the risk of high-temperature demagnetization. The permanent magnet 8 corresponding to each magnetic pole is divided into multiple pieces along the circumference. In order to reduce the volume of a single permanent magnet 8 and block large eddy current loops, thereby significantly reducing the eddy current loss induced in the permanent magnet 8 during high-speed rotation and reducing heat generation from the source, the surface of each permanent magnet 8 is galvanized to prevent corrosion of the permanent magnet 8 surface. Each rotor core section 7 is machined with a magnetic steel groove for accommodating and positioning the permanent magnet 8 corresponding to each magnetic pole. The magnetic steel groove is used to accurately accommodate and position the permanent magnet 8 and prevent its radial and tangential movement.

[0026] The tilting pad sliding bearing 2 is equipped with a temperature sensing element for real-time monitoring of the operating temperature of the tilting pad sliding bearing 2. Under heavy load and high speed operation, the temperature rise of the tilting pad sliding bearing 2 is a key parameter. Real-time temperature measurement can monitor the operating status of the tilting pad sliding bearing 2 and prevent overheating damage caused by lubrication failure or abnormal friction.

[0027] A design method for a heavy-duty, high-power, high-speed permanent magnet synchronous motor includes the following steps: S1: Based on the rated speed of the motor, the number of poles is determined to be 4 poles, and the grade and thickness of the silicon steel sheet for the stator laminations are selected according to the operating frequency; the stator slot shape is designed, and the slot height is raised to not less than 6mm to form a ventilation channel; Litz wire is selected to design a stator winding with an unequal side structure; the electromagnetic air gap is determined, and the structural air gap including the thickness of the carbon fiber sheath is determined based on the sheath stress analysis iteration; Samarium cobalt permanent magnet material is selected as the rotor magnet, and the magnetic circuit is designed; this step is the electromagnetic and material selection design. First, according to the correspondence between high speed and frequency, the motor adopts a 4-pole design. Based on the operating frequency, thin silicon steel sheets are selected, usually 0.2mm or 0.3mm thick, to reduce high-frequency iron loss. When designing the stator slot shape, the slot height is specifically raised to 10mm, the main purpose of which is to form An auxiliary ventilation channel is formed to enhance heat dissipation in the stator winding 4 area. The winding is made of Litz wire and designed with an unequal side structure, which can effectively reduce the length of the winding ends to reduce copper loss. At the same time, the characteristic of the parallel connection of multiple strands of insulated fine wires of Litz wire is used to suppress the skin effect and proximity effect at high frequencies, and significantly reduce AC loss. The air gap size needs to be determined comprehensively, including the electromagnetic air gap based on electromagnetic performance optimization and the structural air gap formed by the thickness of the carbon fiber sheath. The structural air gap needs to be determined by iterative calculation through the force analysis of the carbon fiber sheath 9 under high-speed centrifugal force. In order to cope with the high heat load at high speed, the permanent magnet 8 is made of samarium cobalt material with high temperature resistance to reduce the risk of high-temperature demagnetization. Detailed magnetic circuit design and loss calculation are carried out. Through mutual verification and iteration of calculation results and design parameters, the optimized electromagnetic scheme is obtained. S2: The stator core 3 is divided into multiple segments along the axial direction, and radial ventilation channels spaced by toothed bars 5 are set between adjacent segments; the rotor core, permanent magnet 8, and carbon fiber sheath are designed as axially segmented structures corresponding to the number of segments of the stator core 3, forming radial ventilation gaps between segments; in the core mating section of the shaft 6, multiple axially extending ventilation slots are evenly distributed around the circumference; air inlets and outlets are designed on the top plate 10 of the base 1, and wind baffles 20, air guiding structures, and ventilation slots of ring stiffeners 14 are designed inside the base 1 to guide and optimize the cooling airflow; this step is the integrated design of the core cooling system and ventilation structure. The stator core 3 adopts a radial ventilation structure, dividing the stator core into n segments, with radial ventilation channels of axial length s between each segment. The segment lengths of the stator core 3 are designed according to the principle of ventilation at both ends of the core and decreasing air pressure and air velocity in the middle, where the middle segment has a constant and equidistant length. The length of a single segment of the iron core gradually increases from the center outwards to both ends. If, excluding the equal-length iron core, a single side is divided into m segments of different lengths, such as... , … The entire iron core exists The axial length is similar to that of an axially symmetrical core, and the equivalent core length obtained by electromagnetic calculation is... ,but: ; The actual length L of the stator core 3 is: ; Among them The ventilation ducts can be used for heat dissipation of the stator core 3, and the stator ventilation ducts are spaced by a toothed bar structure. The rotor section adopts an axial segmented design corresponding to the stator, meaning the rotor core section 7, permanent magnet 8, and external carbon fiber sheath 9 are all segmented. Radial ventilation gaps of equal width to the stator ventilation ducts are reserved between the segments to align with the stator air ducts, forming a continuous radial cooling path that runs through the stator and rotor. In the mating section of the rotor core section 7 on the shaft 6, multiple axial ventilation slots are evenly machined circumferentially, with a depth of not less than 50mm and an axial length that extends through the core area and outwards to both sides, thus forming an axial ventilation path inside the rotor for cooling. The cooling system is based on a box-type air-water cooling system. The cooler 21 incorporates a dual-circulation ventilation scheme with the airflow design. Each end of the cooler 21 is equipped with an independent centrifugal fan. On the top plate 10 of the base, air inlets and outlets of specific positions and sizes are opened according to the airflow design. Inside the base 1, a baffle plate 20 is installed at the end of the stator winding 4 to guide end cooling. An air guide structure is set between the top plate outlet and the baffle plate 20 to optimize airflow. Annular ventilation slots are opened on the ring stiffener plate 14 that cooperates with the stator to ensure smooth airflow. S3: Design the base 1, making the base body and support part integrally formed, and the cross-section of the support part is trapezoidal; design circumferentially distributed axial support ribs 13, thickened ring rib plates 14, and axially extending steel pipes within the base body; design a through large-diameter steel pipe 18, cross-shaped I-beams, and multi-section support plates welded to the cross-shaped I-beams within the support part of the base 1; design the rotating shaft 6, making the part where the rotating shaft 6 mates with the rotor core section 7 stepped, and fixing the rotor core section 7 with keys and bolts; to solve the requirements of heavy load and installation height, the base 1 adopts a design of welded structure between the base body and the bottom support part, and the cross-section of the support part is a trapezoidal structure with outward expansion of the two side plates to improve overall stability and modal characteristics. Multiple circumferentially distributed axial support ribs 13 are required inside the base body for positioning and fixing the stator core 3. Thickened ring rib plates 14 are set on both axial sides of the stator core 3 to enhance local support and along the stator core 3. Multiple axial steel pipes 18 are arranged circumferentially along the center line of the sub-core 3, penetrating the inner cavity of the base body as reinforcing beams. Two cross-connected I-beams 17 are designed in the center of the support part, and large-diameter steel pipes 18 are designed axially through the bottom on both sides. The diameter of the large-diameter steel pipes 18 is not less than 150mm. The trapezoidal ring stiffening plates 16 on both sides of the support part, the cross-connected I-beams 17 and the side wall plates 25 of the base are fully penetrated by multiple steel plates 19 to form a high-strength spatial truss inner skeleton. The rotating shaft 6 is a double shaft extension. The part that mates with the rotor core section 7 is processed into multiple stepped shaft sections with varying diameters to facilitate the installation of rotor core sections 7 of corresponding lengths. A keyway with an axial length is required on the rotating shaft 6. The rotor core section 7 transmits torque through the key and is fastened to the rotating shaft 6 with bolts. The axial sides of the rotor core section 7 are finally pressed and fixed by the rotor baffle 23 and the arc key. S4: Based on the rotor dynamics calculation results, iteratively select the tilting pad bearing 2 and verify its oil film stiffness, temperature rise, and lifespan under heavy load and speed regulation range. This step is for bearing selection and shaft dynamics verification. Tilting pad bearings 2 are selected at both ends of the motor. First, based on the preliminary rotor structure, load weight, thrust, and other parameters, the oil film stiffness, damping, operating temperature rise, and lifespan of the tilting pad bearing 2 are calculated in detail. Then, rotor dynamics calculations must be performed based on these bearing parameters to check whether the critical speed of the shaft system avoids the operating speed regulation range and to evaluate the vibration modes. If the calculation results do not meet the requirements, the rotor structure or bearing parameters need to be adjusted, and then the bearing calculation and dynamics calculation are repeated to form an iterative optimization process until the stiffness, temperature rise, lifespan, and shaft dynamics stability of the tilting pad bearing 2 meet the requirements of heavy load and high-speed operation. The tilting pad bearing 2 needs to be equipped with multiple sets of temperature measuring elements for real-time monitoring of the tilting pad bearing 2, thrust surface, and oil inlet temperature. S5: Based on the above integrated design results, manufacture and assemble the heavy-duty high-power high-speed permanent magnet synchronous motor. According to the drawings, parameters and process requirements finally determined in the aforementioned integrated design steps, complete the processing and preparation of all parts, and assemble the motor as a whole according to the design specifications. This includes, but is not limited to, the stamping of stator laminations, the stacking and welding of stator core 3; the winding and embedding of Litz wire windings; the forging and precision machining of shaft 6; the processing and assembly of rotor core section 7 and permanent magnet 8; the segmented winding and curing of carbon fiber sheath 9; the welding and processing of frame 1; the installation and alignment of tilting pad sliding bearing 2; the installation of cooler 21 and air duct components; and the final assembly and commissioning.

[0028] The design method of the heavy-duty high-power high-speed permanent magnet synchronous motor of the present invention mainly includes electromagnetic design, cooling structure design, and structural strength design. In the electromagnetic design, silicon steel sheets of appropriate thickness and grade are selected for high-speed and high-frequency operating conditions to reduce high-frequency iron loss, and the optimized form and structure of the stator winding 3 are applied to significantly reduce AC loss. The motor efficiency is improved and the heat generation of the stator winding 3 is reduced through iterative design. In terms of cooling structure, the motor adopts a square box-type air-water cooling structure. The stator core 3 is provided with a radial ventilation structure. The rotor core section 7, permanent magnet 8, and carbon fiber protection section 9 form a radial ventilation structure corresponding to the stator. At the same time, multiple ventilation slots are machined in the circumferential direction of the shaft 6, and the axial length of the ventilation slots extends from the position of the rotor core section 7 to... Extending to both sides, an axial ventilation structure for the rotor is formed, thereby improving the airflow and enhancing the cooling effect. In terms of structural strength, the motor adopts a support structure with a high center height. The frame is a trapezoidal structure with its bottom sides opening at a certain angle. Internally, it is reinforced by multiple supporting ribs 13, axial steel pipes 18, and cross-connected I-beams 17 welded to the ring stiffener plates 14, thus improving the overall strength and modal characteristics of the motor. This method addresses the challenges of loss, temperature rise, rotor dynamics, strength, and modal characteristics in heavy-duty, high-power, high-speed permanent magnet motors. Through targeted design, it effectively improves efficiency, mitigates temperature rise, meets speed regulation range requirements, enhances structural strength and modal characteristics, satisfies design requirements and safety margins, ensures motor efficiency and safety factor, and improves the stability of the drive system. The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A heavy-duty, high-power, high-speed permanent magnet synchronous motor, characterized in that: The machine includes a frame (1), a stator, a rotor, and a tilting pad sliding bearing (2). The stator includes a stator core (3) and a stator winding (4). The stator core (3) includes multiple axially arranged core segments, which are spaced apart by toothed strips (5) to form radial ventilation channels. Each core segment is formed by stacking multiple stator laminations. The lamination slots on each stator lamination, after being stacked, together form the stator slot of the core segment. The stator slot includes a slot body for accommodating the stator winding (4) and a radially outer side of the slot body. The slot extensions (27) of each stator lamination are aligned axially to form an axial ventilation channel; stator pressure rings (26) are provided on both sides of the stator core (3); the stator winding (4) is a coil wound with an unequal side structure by Litz wire; the rotor is located inside the stator core (3); the rotor includes a rotating shaft (6) and a plurality of rotor segment units spaced apart axially along the rotating shaft (6), the plurality of rotor segment units being arranged at intervals along the rotating shaft (6) and adjacent to each other. Radial ventilation gaps are formed between the units. Each rotor segment unit includes a rotor core segment (7), permanent magnets (8), and partitions. Multiple permanent magnets (8) are spaced apart on the outer periphery of the rotor core segment (7), and partitions are provided between adjacent permanent magnets (8). Each rotor segment unit is wrapped with a carbon fiber sheath (9). The outer circumferential surface of the rotating shaft (6) is provided with multiple ventilation slots extending along its axial direction. The multiple ventilation slots are distributed along the circumference of the rotating shaft (6), and the axial extension range of the ventilation slots is the same as that of all rotor segment units. The overall axial range of the element corresponds to the base (1); the base (1) includes a base body and a support part, the base body and the support part are welded together, the stator is set in the base body, the support part is set at the bottom of the base body, and the cross section of the support part is trapezoidal; the tilting pad sliding bearing (2) is installed at both ends of the base (1), the rotating shaft (6) is supported by the tilting pad sliding bearing (2), and the radial ventilation channel, axial ventilation channel, radial ventilation gap and ventilation groove are interconnected to form the internal cooling air path of the motor.

2. The heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 1, characterized in that: The base body includes a top plate (10), a front wall plate (11), a rear wall plate (12), a base plate (24), and a side wall plate (25). The top plate (10), the front wall plate (11), the rear wall plate (12), the base plate (24), and the side wall plate (25) enclose to form a cylindrical base body. Multiple axially extending support ribs (13) are evenly arranged along the circumferential direction on the inner wall of the base body. The support ribs (13) are connected to the stator. The base body is also provided with a ring rib plate (14) and an axial steel pipe (15). The ring rib plate (14) is located on both sides of the stator core (3) and is connected to the inner wall of the base body. The multiple axial steel pipes (15) are distributed along the circumferential direction of the center line of the stator core (3).

3. The heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 2, characterized in that: The support includes trapezoidal ring stiffeners (16) on both sides, cross-connected I-beams (17), a large-diameter steel pipe (18) and a steel plate (19) that run through the machine base body axially. The lower ends of the trapezoidal ring stiffeners (16) on both sides expand outward. The cross-connected I-beams (17) are located at the center of the support. The large-diameter steel pipe (18) runs through the machine base body axially. The trapezoidal ring stiffeners (16), the cross-connected I-beams (17) and the side wall plate (25) are welded together by multiple sections of steel plate (19).

4. A heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 2, characterized in that: The top plate (10) is provided with an air inlet and an air outlet. Both ends of the base body are provided with baffles (20). The baffles (20) are located at the ends of the stator winding (4). A wind guide structure is provided between the air outlet of the top plate (10) and the baffles (20). A ventilation groove is provided on the ring rib plate (14).

5. A heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 4, characterized in that: A cooler (21) is installed on the top of the base (1). The cooler (21) is a square box-type air-water cooling structure. Independent centrifugal cooling fans are provided at both ends of the cooler (21). The air inlet and air outlet of the top plate (10) of the base (1) are connected to the air passage inside the cooler (21) and the base (1).

6. A heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 1, characterized in that: Multiple junction boxes (22) are also installed on the base (1).

7. A heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 1, characterized in that: The part of the rotating shaft (6) that cooperates with each rotor core segment (7) is stepped, forming multiple shaft segments connected in sequence with different diameters; two rotor core segments (7) are sleeved on each shaft segment; a keyway extending along its axial direction is opened on the rotating shaft (6), and the rotor core segment (7) is fixedly connected to the rotating shaft (6) by a key and a bolt that cooperates with the keyway; rotor baffles (23) are provided on both sides of the axial direction of the rotor core segment (7), one side of the rotor baffle (23) abuts against the stepped surface of the rotating shaft (6), and the other side of the rotor baffle (23) is fixed to the rotating shaft (6) by an arc key.

8. A heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 1, characterized in that: The permanent magnet (8) is made of samarium cobalt permanent magnet material. The permanent magnet (8) corresponding to each magnetic pole is divided into multiple pieces along the circumference. The surface of each permanent magnet (8) is galvanized. Each rotor core section (7) has a magnetic steel groove processed for accommodating and positioning the permanent magnet (8) corresponding to each magnetic pole.

9. A heavy-duty, high-power, high-speed permanent magnet synchronous motor according to claim 1, characterized in that: A temperature measuring element is installed on the tilting pad sliding bearing (2).

10. A design method for a heavy-duty, high-power, high-speed permanent magnet synchronous motor as described in claim 1, characterized in that, Includes the following steps: S1: The number of poles is determined to be 4 to 8 based on the rated speed of the motor, and the grade and thickness of the silicon steel sheet for the stator laminations are selected according to the working frequency; Design the stator slot shape and raise the slot height to not less than 6mm to form a ventilation channel; select Litz wire to design a stator winding with an unequal side structure (4); determine the electromagnetic air gap and iteratively determine the thickness of the carbon fiber sheath, i.e., the structural air gap, based on the sheath stress analysis; select samarium cobalt permanent magnet material as rotor magnet and design the magnetic circuit. S2: The stator core (3) is divided into multiple segments along the axial direction, and radial ventilation channels are set between adjacent segments by toothed pressure bars (5); the rotor core, permanent magnet (8) and carbon fiber sheath are designed as axial segmented structures corresponding to the number of segments of the stator core (3), and radial ventilation gaps are formed between segments; in the core mating section of the rotating shaft (6), multiple axially extended ventilation slots are evenly distributed around the circumference; the air inlet and air outlet are designed on the top plate (10) of the base (1), and the wind baffle (20), air guide structure and ring rib plate (14) ventilation slots are designed inside the base (1) to guide and optimize the cooling air path; S3: Design the base (1) so that the base body and the support part are integrally formed and the cross section of the support part is trapezoidal; design circumferentially distributed axial support ribs (13), thickened ring rib plates (14) and axially extended steel pipes in the base body; design cross-shaped I-beams, through large-diameter steel pipes (18) and multi-section support plates welded to them in the support part of the base (1); design the rotating shaft (6) so that the part that cooperates with the rotor core section (7) is stepped, and the rotor core section (7) is fixed by keys and bolts; S4: Based on the rotor dynamics calculation results, iteratively select tilting pad sliding bearings (2), and calculate their oil film stiffness, temperature rise and life in heavy load and speed regulation range; S5: Based on the above integrated design results, manufacture and assemble the heavy-duty high-power high-speed permanent magnet synchronous motor.

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