A new energy locomotive low-speed large-torque permanent magnet direct-drive traction motor

Abstract

The application discloses a novel new energy locomotive low-speed large-torque permanent magnet direct-drive traction motor, and relates to the technical field of permanent magnet traction motors.The motor comprises a base, an end cover, a stator assembly, a rotor assembly, a rotating shaft and a cooling system; the stator core adopts a 40-pole 48-slot fractional-slot concentrated winding structure, the three-phase armature winding is a flat wire formed winding, the slot fill factor is greater than or equal to 75%, the H-grade insulation is adopted, and the end length is less than or equal to 40 mm; the rotor permanent magnet adopts an embedded V-shaped or a one-character array, non-uniform magnetic separation grooves are formed on the outer periphery of the rotor core, the adjacent magnetic poles are arranged in a circumferential offset manner, the periodic symmetry of the inter-pole permeance is broken, and torque pulsation is inhibited; the cooling system comprises a base water cooling flow channel and a rotor axial air cooling channel, and forms bidirectional composite cooling of the stator and the rotor.The application cancels a reduction gearbox to realize direct drive, has the advantages of high efficiency, low torque pulsation, excellent heat dissipation, high reliability and the like, and is suitable for low-speed heavy-load direct-drive working conditions such as rail transit, mine heavy load and port traction.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous traction motor technology, specifically to a new type of low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives. Background Technology

[0002] Under heavy-load traction conditions, traditional traction drive systems generally employ a transmission scheme of high-speed motor paired with a mechanical gearbox. This scheme has the following technical drawbacks: First, the mechanical gearbox has a complex structure and is prone to failures such as gear wear, lubricating oil leakage, and bearing damage during operation, resulting in high equipment maintenance frequency and costs, and low overall transmission efficiency, typically below 85%. Second, the high-speed motor needs to achieve low-speed, high-torque output through a reduction mechanism, generating significant noise and vibration in the transmission process, affecting the smooth operation of the traction equipment. Third, the presence of the gearbox increases the size and weight of the entire transmission system, limiting space layout and failing to meet the requirements for lightweight and compact installation.

[0003] Existing low-speed permanent magnet traction motors generally suffer from the following technical shortcomings: First, the motor pole-slot matching is unreasonable, the stator winding ends are too long, copper losses are high, and torque pulsation generally exceeds 15% during low-speed operation, causing jitter during traction. Second, the rotor permanent magnet topology design is simple, with a large leakage coefficient, low reluctance torque utilization, and insufficient torque density, making it difficult to meet the high torque output requirements of heavy-load traction. Third, the heat dissipation structure design is imperfect, the heat generation is concentrated under low-speed heavy-load conditions, the permanent magnet is prone to high-temperature demagnetization, and the stability and service life of the motor are difficult to guarantee. Fourth, the overall structural strength is insufficient, and it cannot adapt to complex working conditions such as vibration and impact under traction conditions, and the reliability does not meet the standards for heavy-load industrial use.

[0004] In summary, there is an urgent need in the existing technology for a novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives that can simultaneously solve the problems of pole-slot matching optimization, rotor magnetic circuit optimization, efficient heat dissipation, and structural reliability. It should be noted that the above statements are only used to provide background information related to this invention and do not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a new type of low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives, in order to solve the technical problems of large torque pulsation, low torque density, insufficient heat dissipation, and poor structural reliability of existing permanent magnet direct-drive traction motors.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives includes a frame, a front cover, a rear cover, a stator assembly, a rotor assembly, a shaft, and a cooling system. The front cover and the rear cover are respectively fixedly installed at both axial ends of the frame to form a closed motor housing. The stator assembly is fixed to the inner wall of the frame and includes a stator core and a three-phase armature winding. The rotor assembly is fixedly assembled in the middle of the shaft and includes a rotor core and a permanent magnet. A uniform air gap is maintained between the rotor assembly and the stator assembly. The shaft is rotatably connected to the front cover and the rear cover via bearings. The cooling system includes a frame water-cooling channel and a rotor axial air-cooling channel. The frame water-cooling channel is located inside the frame wall, and the rotor axial air-cooling channel is located at the axial end of the rotor core.

[0007] According to some embodiments of the present invention, the tooth width of the stator core is 14.5 mm, and the yoke thickness of the stator core is 7.5 mm; the stator core is an integral structure and is fixed to the fasteners by welding through fastener slots.

[0008] According to some embodiments of the present invention, the non-uniform magnetic isolation groove has a width of 4.6 mm and a depth of 22 mm.

[0009] According to some embodiments of the present invention, the permanent magnet is a neodymium iron boron permanent magnet material, and the remanence of the permanent magnet Br≥1.2T and the coercivity Hc≥950kA / m.

[0010] According to some embodiments of the present invention, the base adopts a welded steel plate structure, the inner wall of the base is provided with water channel ribs, the water channel ribs are welded and fixed to the base, and the coolant flow path of the water cooling channel of the base is formed between the water channel ribs and the inner wall of the base.

[0011] According to some embodiments of the present invention, the rotating shaft is made of 42CrMo alloy structural steel and is heat-treated. Sealed cylindrical roller bearings and ball bearings are assembled at both ends of the rotating shaft.

[0012] According to some embodiments of the present invention, the coolant flow rate in the water-cooled channel of the base is 35 L / min.

[0013] According to some embodiments of the present invention, the stator core adopts a multi-pole, multi-slot fractional-slot concentrated winding structure, the stator core has 40 poles and 48 slots; the three-phase armature winding is a flat wire forming winding, the slot fill factor of the three-phase armature winding is ≥75%, the insulation class is H, and the end length of the three-phase armature winding is ≤40mm.

[0014] According to some embodiments of the present invention, the permanent magnets are embedded in the rotor core in a built-in V-shaped or straight array structure, with ≥2 permanent magnets per pole; the outer circumferential edge of the rotor core is provided with non-uniform magnetic isolation grooves, and the magnetic isolation grooves of adjacent magnetic poles are staggered in the circumferential direction.

[0015] This invention discloses a novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives, which has the following advantages: By eliminating the mechanical gearbox and achieving direct-drive traction, the potential for gearbox failure is completely eliminated, reducing the overall motor failure rate by over 90% and equipment maintenance costs by 80%. Simultaneously, transmission noise is reduced by over 15dB, and the overall system transmission efficiency is improved by over 10%. The 40-pole, 48-slot fractional-slot concentrated winding combined with flat-wire formed windings achieves q=0.4 slots per pole per phase, a winding pitch of 1, and extremely short end lengths, significantly reducing copper losses, increasing slot fill factor to over 75%, increasing the effective conductor area, and significantly enhancing low-speed, high-torque output capabilities.

[0016] The non-uniform magnetic isolation grooves with adjacent magnetic poles staggered are fundamentally different from the helical structures with axial laminations in existing technologies. This invention achieves circumferential misalignment of the magnetic isolation grooves between adjacent poles on the same circumferential cross-section, directly breaking the periodic symmetry of the inter-pole magnetic permeability. This results in controlled differences in the air gap magnetic flux density waveform under each pole, thereby weakening the low-order harmonic components that cause torque pulsation at the source. Compared to helical magnetic isolation grooves that only produce gradually varying magnetic permeability across the axial cross-section, the circumferential misalignment method of this invention achieves magnetic permeability modulation within the same cross-section, resulting in a more direct and efficient torque pulsation suppression effect. Furthermore, it eliminates the need for piece-by-piece rotation assembly, simplifying the manufacturing process.

[0017] The design employs a built-in V-shaped or straight-line permanent magnet array and a staggered non-uniform magnetic isolation slot. The V-shaped structure generates a significant reluctance torque component, which, when superimposed with the permanent magnet torque, increases the torque density to over 20 N·m / kg, a 30% improvement compared to similar low-speed motors. The staggered arrangement of the non-uniform magnetic isolation slot further optimizes the magnetic circuit distribution, reduces permanent magnet leakage, and lowers rotor eddy current losses. Together, these two factors keep torque ripple below 5%.

[0018] The water-cooled flow channel in the frame and the axial air-cooled channel in the rotor form a bidirectional composite cooling structure for the stator and rotor. On the stator side, the water-cooled flow channel within the frame wall efficiently removes heat from the copper and iron losses of the stator windings. On the rotor side, the axial air-cooled channel utilizes the airflow generated by the rotor's rotation to carry away heat from the permanent magnets and rotor core, forming a dual-path heat dissipation system from the stator to the frame and from the rotor to the air gap. Compared to solutions using only water cooling of the casing or only natural heat dissipation, the composite cooling structure of this invention ensures that the motor temperature rise is ≤80K, the permanent magnet operating temperature remains stable within a safe range, completely solving the problem of high-temperature demagnetization and extending the motor's service life to over 20 years.

[0019] With its modular stator, high-strength frame, and reinforced shaft design, the overall structure is compact, exhibiting excellent vibration and impact resistance. It can adapt to harsh and heavy-duty working conditions such as rail transit, mining, and ports, requiring little installation space, and is highly adaptable to a wide range of applications.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, specific embodiments of the present invention are described below. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0022] Figure 1 This is an overall axial sectional view of the motor of the present invention; Figure 2 This is a schematic diagram of the rotor core and permanent magnet arrangement and the misaligned magnetic isolation slot structure of the present invention; Figure 3 This is a schematic diagram of the flow path structure of the cooling system of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Example

[0024] like Figures 1 to 3 As shown, this embodiment provides a novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives, including a frame 1, a front end cover 2, a rear end cover 3, a stator assembly, a rotor assembly, a shaft 8, and a cooling system.

[0025] The front cover 2 and the rear cover 3 are respectively fixedly installed on the axial ends of the base 1 by bolts, forming a closed motor housing. The stator assembly is interference-fitted and fixed to the inner wall of the base 1, and the rotor assembly is fixedly assembled in the middle of the rotating shaft 8, with a uniform air gap between the rotor assembly and the stator assembly to achieve a coaxial clearance fit. The rotating shaft 8 is rotatably connected to the front cover 2 and the rear cover 3 by bearings 11.

[0026] The stator assembly includes a stator core 4 and three-phase armature windings 5. The stator core 4 adopts a multi-pole, multi-slot fractional-slot concentrated winding structure, with 2p = 40 poles and Q = 48 slots. The number of slots per pole per phase is q = 48 / (3 × 40) = 0.4. The stator core 4 is made of laminated silicon steel sheets, with optimized tooth and yoke parameters. The stator tooth width is 14.5 mm, and the stator yoke thickness is 7.5 mm. The stator core 4 adopts an integral structure, and the core lamination slots are fixed to the laminations by welding, improving the machining and assembly accuracy of the stator core 4 while reducing vibration and noise during motor operation.

[0027] The three-phase armature winding 5 adopts a flat wire forming winding with a slot fill factor ≥75%, insulation class H, and winding end length ≤40mm. Compared to traditional round wire windings, flat wire forming windings have the following advantages: First, the contact area between the flat wire and the stator slot wall is 30%–50% larger than that of round wire, allowing heat to be transferred more easily to the frame 1 through the slot wall, reducing winding temperature rise by 10–15℃; Second, the flat wire is densely arranged, increasing the slot fill factor from approximately 60% for round wire to over 75%, increasing the effective conductor cross-sectional area, reducing DC resistance by 15%–20%, and decreasing copper loss by approximately 10%; Third, the flat wire winding ends are regular and neat, with end length controllable to within 40mm, significantly reducing end leakage flux and copper loss. The winding pitch is 1, with each coil wound on only one stator tooth, simplifying the process, suitable for automated production, with no overlap between windings, and good phase-to-phase insulation.

[0028] The rotor assembly includes a rotor core 6 and permanent magnets 7. The rotor core 6 is formed by stacking silicon steel sheets, and the permanent magnets 7 are embedded inside the rotor core 6 using an internal V-shaped array structure, with two permanent magnets 7 per pole. The permanent magnets 7 are made of high-grade neodymium iron boron permanent magnet material N48, with a remanence Br=1.45T and coercivity Hc=1050kA / m. The V-shaped permanent magnet structure generates a significant reluctance torque component. The optimized magnetic circuit allows the reluctance torque and permanent magnet torque to superimpose over a wide speed range, increasing the output power by 25% compared to the traditional surface-mounted permanent magnet structure, with a torque density ≥20N·m / kg.

[0029] Non-uniform magnetic isolation slots 10 are formed on the outer circumferential edge of the rotor core 6. The slots are 4.6 mm wide and 22 mm deep. The core feature of the non-uniform magnetic isolation slots 10 is that the magnetic isolation slots of adjacent magnetic poles are staggered in the circumferential direction. Specifically, along the circumferential direction of the rotor core 6, the angle between the center line of the magnetic isolation slot of the first magnetic pole and the d-axis of the pole is α1, and the angle between the center line of the magnetic isolation slot of the adjacent second magnetic pole and the d-axis of the pole is α2, where α1 ≠ α2, meaning that the offset of the magnetic isolation slots of adjacent magnetic poles relative to their respective d-axis is different. This design, which achieves circumferential staggering of the magnetic isolation slots of adjacent magnetic poles on the same circumferential cross section, is fundamentally different from the spiral magnetic isolation slot structure with axial lamination staggering in the prior art.

[0030] The existing technology CN202610122770, which uses a spiral-type magnetic isolation slot misalignment, involves rotating the entire group of magnetic isolation slots by a fixed angle θ2 between adjacent axially aligned laminations to form a spiral distribution along the axial direction. In this scheme, the positions of the magnetic isolation slots for each magnetic pole on the same circumferential cross-section remain symmetrical; that is, the offset of the magnetic isolation slots for all magnetic poles relative to their respective d-axis is the same, and the inter-pole magnetic permeability still exhibits a periodic symmetrical distribution. This lack of ability to suppress high-order harmonic torque pulsations caused by asymmetry in inter-pole magnetic permeability is problematic. Furthermore, the spiral structure requires lamination to be rotated and stacked one by one for assembly, resulting in high process complexity.

[0031] The circumferential misalignment scheme of this invention directly breaks the periodic symmetry of the inter-pole magnetic permeability on the same circumferential cross-section. When the rotor rotates, the air gap magnetic flux density waveform under each magnetic pole experiences a controlled phase shift due to the difference in the position of the magnetic isolation slots. This causes the low-order harmonic components that cause torque pulsation to cancel each other out between the magnetic poles, rather than simply superimposing. This design suppresses the generation of torque pulsation at its source, with a more direct and efficient effect. The measured torque pulsation can be controlled within 5%. At the same time, the magnetic isolation slot misalignment can be achieved on the same lamination, eliminating the need for lamination-by-lamination rotation assembly, simplifying the manufacturing process and increasing production efficiency.

[0032] Furthermore, the staggered arrangement of the non-uniform magnetic isolation slots 10 optimizes the magnetic circuit distribution, reduces the leakage flux of the permanent magnet 7, and lowers the leakage flux coefficient from 0.25 to below 0.15, increasing the effective magnetic flux of the permanent magnet and improving the air gap magnetic density. At the same time, the staggered arrangement of the magnetic isolation slots breaks the periodicity of the eddy current path, disperses the rotor eddy current distribution, and reduces eddy current losses during high-frequency operation.

[0033] The cooling system includes a base water-cooled channel 9 and a rotor axial air-cooled channel. The base 1 is a welded steel plate structure. The inner wall of the base 1 has water channel ribs, which are welded and fixed to the base 1. The water channel ribs and the inner wall of the base 1 form the coolant flow path of the base water-cooled channel 9. The coolant flow rate in the base water-cooled channel 9 is controlled at 35 L / min. The coolant flows in from the inlet at one end of the base 1, flows along the annular channel around the inner wall of the base 1, and then flows out from the outlet at the other end, efficiently carrying away the heat generated by the stator winding copper loss and the stator core iron loss. The rotor axial air-cooled channel is located at the axial end of the rotor core 6. Ventilation holes are provided at both ends of the rotor. The airflow generated when the rotor rotates enters the axial air-cooled channel 12 from one end, flows axially through the interior of the rotor core 6, and then exits from the other end, carrying away the heat from the permanent magnet 7 and the rotor core 6.

[0034] The frame water-cooling channel 9 and the rotor axial air-cooling channel form a bidirectional composite cooling structure for the stator and rotor. Heat on the stator side is primarily conducted to the frame 1 through the stator core 4, and then carried away by the coolant in the frame water-cooling channel 9; heat on the rotor side is primarily carried away by the airflow in the rotor axial air-cooling channel. These two heat dissipation paths are independent yet complementary, forming a dual-path heat dissipation system from the stator to the frame and from the rotor to the air gap. Compared to the solution CN205123441, which only uses casing water cooling, the composite cooling structure of this invention increases the active heat dissipation capacity on the rotor side, reducing the permanent magnet temperature rise by 15-20°C; compared to the solution using only natural heat dissipation, the water-cooling channel improves the stator side heat dissipation efficiency by more than 50%. This composite cooling structure ensures that the overall motor temperature rise is ≤80K, the permanent magnet operating temperature remains stable within a safe range, and the problem of high-temperature demagnetization is completely solved.

[0035] The rotating shaft 8 is made of 42CrMo alloy structural steel with a quenched and tempered finish, and its diameter is optimized according to torque requirements. High-precision sealed cylindrical roller bearings and ball bearings are installed at both ends of the rotating shaft 8. The bearings employ an oil-filled structure to prevent dust and oil contamination, improving the stability and service life of the motor. The overall wall thickness of the base 1 meets the requirements for heavy-duty vibration and impact resistance, and conforms to the IEC61373 vibration and impact standard for rail transit equipment.

[0036] The motor in this embodiment has a rated speed of 140 r / min, a rated output torque of 12276 N·m, a rated working efficiency of 94.5%, and a torque ripple of 3.2%. The stator winding temperature rise is 75 K and the permanent magnet temperature rise is 68 K. All performance indicators are superior to traditional traction motors, and it can be directly applied to the traction conditions of heavy-duty mining locomotives. Example

[0037] This embodiment provides a 200kW new energy locomotive low-speed high-torque permanent magnet direct drive traction motor, which differs from Embodiment 1 in the specific parameters of the stator core 4 and the rotor core 6.

[0038] The stator core 4 adopts a 24-slot / 16-pole fractional-slot concentrated winding structure with a modular three-section design. The length of a single core section is 260mm, the outer diameter of the stator core is 520mm, the inner diameter is 320mm, the tooth width is 12mm, and the yoke thickness is 18mm. The three-phase armature winding 5 adopts a 4×6mm flat wire forming winding with a slot fill factor of 78%, H-class insulation, and an end length of 70mm.

[0039] The rotor core 6 has an outer diameter of 318mm and an inner diameter of 120mm. The permanent magnets 7 are arranged in a built-in V-shape, with two N48 neodymium iron boron permanent magnets per pole. The remanence Br = 1.45T and the coercivity Hc = 1050kA / m. The non-uniform magnetic isolation slots 10 have a slot width of 3mm and a slot depth of 5mm, with adjacent pole magnetic isolation slots offset by 1.5 times the slot pitch.

[0040] In the cooling system, the coolant flow rate of the water-cooled channel 9 in the base is 1.2 m / s, and the inlet water temperature is 25℃; the air volume of the rotor axial air-cooled channel is 0.8 m³ / s.

[0041] Structural components: The base 1 is made of welded steel plate with an outer diameter of 650mm; the rotating shaft 8 is made of 42CrMo heat-treated steel with a shaft diameter of 150mm and high-precision sealed bearings are installed at both ends.

[0042] Performance testing showed that the motor has a rated efficiency of 94.5%, torque pulsation of 3.2%, stator winding temperature rise of 75K, and permanent magnet temperature rise of 68K, making it suitable for direct application in the traction conditions of heavy-duty mining locomotives. Example

[0043] This embodiment provides a 110kW new energy locomotive low-speed high-torque permanent magnet direct drive traction motor, which differs from Embodiment 1 in the pole slot matching and frame structure.

[0044] The machine has 12 poles and 18 slots. The frame 1 is made of integral cast steel. The permanent magnet 7 is made of N45 neodymium iron boron. In the cooling system, the coolant flow rate in the water-cooled channel 9 of the frame is 1.0 m / s, and the air volume in the rotor axial air-cooled channel is 0.6 m³ / s.

[0045] Test results show that the motor has a rated efficiency of 94.2%, torque pulsation of 4.1%, stable operation, and low vibration and noise, making it suitable for direct drive traction scenarios such as port tractors and rail engineering vehicles. Example

[0046] The difference between this embodiment and Embodiment 1 lies in the arrangement of the permanent magnets 7.

[0047] The permanent magnet 7 is embedded in the rotor core 6 using a built-in linear array structure. Two linear permanent magnets are set for each pole and arranged radially along the rotor core 6. The linear permanent magnet structure is suitable for installation conditions where radial space is limited. While ensuring the effective magnetic flux of the permanent magnet, it reduces the radial thickness of the rotor core 6, allowing the overall outer diameter of the motor to be further reduced.

[0048] The misalignment method of the non-uniform magnetic isolation slot 10 is the same as in Example 1, with adjacent magnetic pole magnetic isolation slots arranged in a circumferentially misaligned manner. Simulation verification shows that the torque ripple can be controlled within 4.8% by using a linear permanent magnet in conjunction with the misaligned structure of the non-uniform magnetic isolation slot, which meets the stability requirements of low-speed direct drive conditions. Example

[0049] The difference between this embodiment and Embodiment 1 lies in the misalignment of the non-uniform magnetic isolation groove 10.

[0050] In this embodiment, non-uniform magnetic isolation slots 10 are formed on the outer circumferential edge of the rotor core 6. The magnetic isolation slots of adjacent magnetic poles are staggered in the circumferential direction, and the amount of staggering changes alternately along the circumferential direction of the rotor. Specifically, the magnetic isolation slot of the first magnetic pole is offset by α1 relative to the d-axis, the magnetic isolation slot of the second magnetic pole is offset by α2 relative to the d-axis, the magnetic isolation slot of the third magnetic pole is offset by α1 relative to the d-axis, the magnetic isolation slot of the fourth magnetic pole is offset by α2 relative to the d-axis, and so on, forming an alternating odd and even staggered pattern.

[0051] This alternating misalignment mode further breaks the periodicity of the magnetic permeability distribution, allowing the specific harmonic components that cause torque ripple to completely cancel each other out between adjacent magnetic poles. Finite element simulations have verified that, compared to the uniform misalignment method, the alternating misalignment mode can reduce the 5th and 7th harmonic torque components by 35% and 28%, respectively, and further reduce the total torque ripple to 2.8%. Example

[0052] The difference between this embodiment and Embodiment 1 lies in the specific configuration of the cooling system.

[0053] The water-cooling channel 9 of the chassis adopts a ring-shaped series channel structure. The coolant enters from the inlet at the bottom of the chassis 1, spirals upward along the ring-shaped channel on the inner wall of the chassis 1, and flows out from the outlet at the top. The water channel ribs are distributed in a spiral shape on the inner wall of the chassis 1, guiding the coolant to flow along the spiral path, increasing the contact area and contact time between the coolant and the inner wall of the chassis 1, and improving the heat dissipation efficiency.

[0054] The rotor axial air-cooling channel has guide vanes at the axial end of the rotor core 6. When the rotor rotates, the guide vanes drive external air to enter the axial air-cooling channel 12 from one end, flow through the interior of the rotor core 6, and then exit from the other end, forming forced convection. This structure does not require an additional fan, and utilizes the rotor's own rotation to drive the airflow, making it simple and reliable.

[0055] Temperature field simulation verification shows that the composite cooling structure of this embodiment can raise the temperature of the stator winding to 72K and the temperature of the permanent magnet to 65K, and the heat dissipation effect is better than the straight-through flow channel structure of Embodiment 1.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0057] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Modifications or substitutions to the technical solutions described in the foregoing embodiments do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives, comprising a frame, a front cover, a rear cover, a stator assembly, a rotor assembly, a shaft, and a cooling system; the front cover and the rear cover are respectively fixedly installed at both axial ends of the frame to form a closed motor housing; the stator assembly is fixed to the inner wall of the frame, the stator assembly includes a stator core and a three-phase armature winding; the rotor assembly is fixedly assembled in the middle of the shaft, the rotor assembly includes a rotor core and a permanent magnet; a uniform air gap is maintained between the rotor assembly and the stator assembly; the shaft is rotatably connected to the front cover and the rear cover respectively via bearings; the cooling system includes a frame water-cooling channel and a rotor axial air-cooling channel, the frame water-cooling channel being opened inside the wall of the frame, and the rotor axial air-cooling channel being opened at the axial end of the rotor core.

2. The novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The stator core has a tooth width of 14.5 mm and a yoke thickness of 7.5 mm. The stator core is an integral structure and is fixed to the fasteners by welding through fastener slots.

3. The novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The non-uniform magnetic isolation groove has a width of 4.6 mm and a depth of 22 mm.

4. The novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The permanent magnet is a neodymium iron boron permanent magnet material, and the remanence of the permanent magnet Br≥1.2T and the coercivity Hc≥950kA / m.

5. The novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The base is made of welded steel plate. The inner wall of the base is provided with water channel ribs. The water channel ribs are welded and fixed to the base. The water channel ribs and the inner wall of the base form a coolant flow path for the water cooling channel of the base.

6. The novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The shaft is made of 42CrMo alloy structural steel and has been heat-treated. Both ends of the shaft are equipped with sealed cylindrical roller bearings and ball bearings.

7. A novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The coolant flow rate in the water-cooled channel of the base is 35L / min.

8. A novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The stator core adopts a multi-pole, multi-slot concentrated winding structure, with 40 poles and 48 slots. The three-phase armature winding is a flat wire forming winding with a slot fill factor of ≥75%, an insulation class of H, and an end length of ≤40mm.

9. A novel low-speed, high-torque permanent magnet direct-drive traction motor for new energy locomotives according to claim 1, characterized in that: The permanent magnets are embedded in the rotor core using a built-in V-shaped or straight array structure, with ≥2 permanent magnets per pole; the outer circumferential edge of the rotor core is provided with non-uniform magnetic isolation grooves, and the magnetic isolation grooves of adjacent magnetic poles are arranged in a staggered manner in the circumferential direction.

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