A method for reducing the temperature difference of the stator of a long-core permanent magnet wind turbine at high altitude

Abstract

The present invention discloses a method for reducing the temperature difference of the stator of a long-core permanent magnet wind turbine at high altitude, and relates to the technical field of ventilation and cooling of permanent magnet direct-drive wind turbines. In the present invention, cooling air enters an annular space from an air inlet duct to cool the non-driving end of the stator coil. At the same time, cooling air enters an air inlet cavity from the annular space, and the cooling air flows from the air inlet cavity to radial ventilation channels distributed circumferentially on the corresponding stator core, and enters an air gap. The cooling air flows from the air gap to an air outlet cavity, which corresponds to radial ventilation channels distributed circumferentially on the stator core, and then enters the air outlet cavity, and is discharged from a first air outlet duct installed on the ventilation space at the driving end. Each section of the stator core and the stator coil at each section of the stator core obtain more sufficient cooling air, thereby improving the cooling effect, reducing the stator temperature difference, and improving the cooling air utilization efficiency, thereby adapting to the unfavorable conditions of lower air density in high altitude areas.

Description

Technical Field

[0001] The present invention relates to the technical field of ventilation and cooling of permanent magnet direct-drive wind turbines, and in particular to a method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitudes, which is suitable for large-capacity permanent magnet low-speed wind turbines at high altitudes. Background Art

[0002] Low-speed permanent magnet wind turbine motors have a low speed of only around 10 r / min, and the pressure generated by the rotating components is only a few Pa, which is insufficient to drive air flow within the motor to remove losses during operation. A dedicated fan is generally used as the primary pressure source for air flow. Larger capacity permanent magnet low-speed wind turbine motors, however, have longer cores and utilize radial core ventilation. Cooling air passes through the stator, enters the air gap, diffuses toward both ends of the core, and finally passes through the stator winding ends and ventilation ducts. Because the core is longer, the ventilation path for direct stator cooling is long. Furthermore, due to structural limitations, fans cannot generally be evenly arranged around the circumference of the motor base. Consequently, the circumferential temperature distribution of the stator coils and core is uneven, with circumferential temperature differences reaching 30K-40K. This makes it difficult to further increase the electromagnetic load, impacting the motor's economic efficiency.

[0003] For example, in the Chinese patent, the authorization announcement number is CN110429747B, the authorization announcement date is November 20, 2020, and the name is a method for reducing the circumferential temperature difference between the motor coil and the core. In this method, the cooling air enters the large cavity from the air inlet duct below. The cooling air enters the air gap from the large cavity and cools the end of the stator core at the same time. The cooling air enters the air gap for turbulence and enters the stator ventilation groove for heat exchange. However, the stator core is relatively long. During the journey of the cooling air flowing from the air gap at one end of the stator to the other end of the stator, the temperature of the cooling air is affected by the heat dissipated by the stator core, stator coil, and rotor magnet. The cooling air temperature gradually decreases. The temperature of the cooling air gradually increases, and the cooling effect on the stator end is not significant. The longer the stroke, the higher the temperature of the cooling air flowing to the stator ventilation groove, resulting in uneven cooling of each section of the stator core and low cooling efficiency. The cooling air enters the air inlet cavity from the large cavity. Due to the small radial size of the air inlet cavity, the wind resistance is large, and the amount of cooling air entering is small. On the one hand, the direct contact time with the stator core is short, the time for heat exchange is short, and the heat exchange efficiency is low. On the other hand, when the cooling air flows from one end of the air inlet cavity to the other end, it is affected by the heat dissipated by the stator core and the stator coil. The cooling air temperature gradually increases, resulting in uneven cooling of each section of the stator core and low cooling efficiency.

[0004] Especially for high-altitude, large-capacity, permanent magnet, low-speed wind turbines, cooling is more difficult due to the low air density, further limiting the increase in the electromagnetic load of the motor. Summary of the Invention

[0005] To address the deficiencies of the above-mentioned prior art, the present invention provides a method for reducing the temperature difference of the stator of a long-core permanent magnet wind turbine at high altitudes. The cooling air path in the present invention cools the stator core and the stator coil, and each section of the stator core and the stator coil at each section of the stator core receive more sufficient cooling air, thereby improving the cooling effect, reducing the stator temperature difference, and improving the cooling air utilization efficiency, thereby adapting to the unfavorable conditions of lower air density in high altitude areas.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude, characterized in that cooling air enters an annular space from an air inlet duct to cool the non-driving end of the stator coil;

[0008] At the same time, cooling air enters the air inlet cavity from the annular space, flows from the air inlet cavity to the radial ventilation channels distributed on the circumference of the stator core, enters the air gap, flows from the air gap to the radial ventilation channels distributed on the circumference of the stator core in the air outlet cavity, then enters the air outlet cavity, flows from the air outlet cavity to the drive end ventilation space, and is discharged from the first air outlet duct;

[0009] The annular space is the space at the non-driving end of the stator coil, and the air inlet duct is used to allow cooling air to enter the annular space to cool the non-driving end of the stator coil; the driving end ventilation space is the space at the driving end of the stator coil, and the first air outlet duct is used to allow cooling air to exchange heat with the driving end of the stator coil in the driving end ventilation space and then be discharged from the first air outlet duct;

[0010] A cavity is formed between the stator core and the stator base, and a second radial ring plate is installed on the stator base, which divides the cavity into two left and right chambers; a plurality of axial ribs are arranged at intervals in the cavity, and the axial ribs divide the cavity into multiple axial cavities, and ventilation channels are provided on the second radial ring plate to connect the left and right axial cavities to form an axially longer axial cavity, and the axial cavities are evenly distributed along the circumference of the stator base, and the adjacent axially longer axial cavities are respectively the air inlet cavity and the air outlet cavity.

[0011] Furthermore, the stator frame includes a first ring plate, a second radial ring plate, a third ring plate and a plurality of axial ribs arranged in sequence on the inner diameter side back of the stator core, a fourth ring plate is arranged between the first ring plate and the second radial ring plate, one end of the fourth ring plate is connected to the first ring plate, and the other end is connected to the second radial ring plate; a fifth ring plate is arranged between the second radial ring plate and the third ring plate, one end of the fifth ring plate is connected to the second radial ring plate, and the other end is connected to the third ring plate, a cavity is surrounded by the first ring plate, the third ring plate, the fourth ring plate and the fifth ring plate, the cavity is divided into two left and right chambers by the second radial ring plate, and a plurality of axial ribs are arranged between the left and right chambers, The axial ribs divide the chamber into multiple axial cavities, which are evenly distributed along the circumference of the stator base. The axial cavities in the left and right chambers correspond to each other one by one, and ventilation holes are set on the second radial ring plate to connect the axial cavities in the left and right chambers to form an axially longer axial cavity; ventilation holes are set at intervals along the circumference of the first ring plate and the third ring plate, and the projection positions of the ventilation holes on the first ring plate and the ventilation holes on the third ring plate are alternated on the circumference; the connected axial cavities are connected to the annular space through the ventilation holes on the third ring plate to form an air inlet chamber, and the connected axial cavities are connected to the driving end ventilation space through the ventilation holes on the first ring plate to form an air outlet chamber.

[0012] Furthermore, the stator core is arranged in the rotor cylinder, the rotor magnet is arranged between the rotor cylinder and the stator core, and the ventilation channel steel is arranged between two adjacent stator core sections. The two stator core sections and the ventilation channel steel form a radially separated radial ventilation channel. The tensioning screw passes through multiple sections of the stator core, and both ends of the tensioning screw are fixed with stator end pressure plates; an air gap is set between the rotor magnet and the stator core.

[0013] Furthermore, the rotor cylinder is connected to the rotor non-drive end ring plate, the rotor non-drive end ring plate is connected to the sealing structure M, a copper ring is provided on the third ring plate, a sixth ring plate is provided below the copper ring, the sixth ring plate is located between the third ring plate and the rotor non-drive end ring plate, the sixth ring plate is respectively connected to the third ring plate and the rotor non-drive end ring plate, the sixth ring plate, the third ring plate, the stator end pressure plate, the rotor non-drive end ring plate, and the rotor cylinder form an annular space through which cooling air passes, an air inlet duct is provided on the rotor non-drive end ring plate, and the air inlet duct is connected to the annular space; the cavity surrounded by the rotor cylinder and the first ring plate is the drive end ventilation space; at the drive end of the stator coil, a first air outlet duct is installed on the rotor cylinder at this position.

[0014] Furthermore, the radial dimensions of the air inlet cavity and the air outlet cavity are not less than 100 mm.

[0015] Furthermore, the air gap value is 4-5 mm.

[0016] Furthermore, the axial height of the radial ventilation channel is 3-4 mm.

[0017] Furthermore, the total axial length of the multi-segment stator core is more than 1500 mm, the axial length of the stator core is 20-30 mm, and is evenly distributed in the axial direction.

[0018] Furthermore, the air inlet ducts and the first air outlet ducts are evenly distributed along the circumference, and the number thereof is 6-8, and the number of the blowers is the same as the number of the air inlet ducts.

[0019] Furthermore, the end of the first air outlet duct is connected to a dynamic-static separation structure with a seal, including a seventh ring plate, an eighth ring plate, a ninth ring plate, a tenth ring plate, a sealing pressure plate, and a C-type seal. The seventh ring plate is connected to the rotor cylinder, the seventh ring plate is connected to one end of the eighth ring plate, and rotates with the rotor cylinder. The ninth ring plate is connected to the cabin, the ninth ring plate is connected to the tenth ring plate, and the C-type seal is installed on the inner side of the tenth ring plate with the help of a sealing pressure plate, and is squeezed with the other end of the eighth ring plate to complete the sealing of the dynamic-static separation part. A space is enclosed by the seventh ring plate, the eighth ring plate, the ninth ring plate, the tenth ring plate and the C-type seal; a ventilation hole is opened at the corresponding position of the seventh ring plate to connect to the first air outlet duct, a ventilation hole is opened at the corresponding position of the ninth ring plate to connect to the second air outlet duct, the second air outlet duct is connected to the cabin air outlet, and the cooling air enters the space from the first air outlet duct, flows to the second air outlet duct and the cabin air outlet, and is discharged into the atmosphere.

[0020] Furthermore, the sealing structure M includes a rotor non-driving end ring plate, a sealing mounting ring plate, a pressure block, a C-type seal, and a sealing ring plate. The sealing mounting ring plate, the pressure block, the C-type seal, and the sealing ring plate are installed on the rotor non-driving end ring plate. Grooves for installing C-type seals are processed on both end faces on the inner diameter side of the rotor non-driving end ring plate, and the C-type seal is fixed with the help of the pressure block. The C-type seal lips are all facing the inner diameter side, and are squeezed together with the sealing ring plate installed on the sealing mounting ring plate to complete the sealing at the dynamic and static separation of the wind turbine motor.

[0021] The working principle of the present invention is as follows:

[0022] The cooling air enters the annular space from the air inlet duct to directly cool the non-driving end of the stator coil. At the same time, the cooling air enters the air inlet cavity through the ventilation holes on the third ring plate. The cooling air then flows to the air gap through the radial ventilation channels distributed on the corresponding circumference of the air inlet cavity. The cooling air flows from the air gap to the air outlet cavity through the radial ventilation channels distributed on the corresponding circumference of the air outlet cavity, completing the cooling of each section of the stator core and the stator coil at each section of the stator core. After entering the air outlet cavity, the cooling air flows into the driving end ventilation space to cool the driving end of the stator coil, and the cooling air flows out from the first air outlet duct.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. Compared with the existing technology, the cooling air flows from the radial ventilation channels distributed on the circumference of the air inlet cavity to the air gap, and flows from the air gap to the radial ventilation channels distributed on the circumference of the air outlet cavity, and enters the air outlet cavity. Through the action of the air inlet cavity and the air outlet cavity corresponding to the back of the inner diameter of the stator core, the difference in air volume in the radial ventilation channels is reduced, so that each section of the stator core and the stator coil in each section of the stator core can obtain more sufficient cooling air, thereby improving the cooling effect.

[0025] 2. Compared with the existing technology, the cooling air directly cools the non-driving end of the stator coil and the copper ring, reducing the distance of the cooling air flowing to the non-driving end of the stator coil and the copper ring, and improving the utilization rate of the cooling air and the cooling effect.

[0026] 3. In the present invention, each section of the stator core is 20% shorter than the stator core of a conventional large-capacity permanent magnet low-speed wind turbine. Since the stator core and the coil are radially ventilated and cooled, the shorter the radial ventilation channel spacing, the greater the heat dissipation area of the stator core and the stator coil, thereby improving the cooling effect.

[0027] 4. In the present invention, the axial height of the radial ventilation channel is 3-4 mm, which is more than 10% smaller than that of the prior art. The reduction in the height of the radial ventilation channel can increase the number of radial ventilation channels without significantly increasing the total length of the core, thereby increasing the heat dissipation surface area and improving the cooling effect.

[0028] 5. In the present invention, multiple blowers, air inlet ducts and the first air outlet duct are evenly distributed on the circumference, which helps the cooling air flow more evenly on the circumference and helps ensure the ventilation and cooling effect.

[0029] In summary, the cooling air path and air gap turbulence of the present invention, as well as the reduction of the stator core length and the radial ventilation channel height, improve the cooling effect and reduce the stator temperature difference. Compared with the existing technology, the wind resistance is reduced by more than 30%, the axial temperature difference is reduced by more than 15%, and the circumferential temperature difference is reduced by 15% to 25%, thereby improving the utilization rate of the cooling air, thereby enabling the wind turbine to adapt to the unfavorable conditions of lower air density in high-altitude areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Longitudinal section of wind turbine generator;

[0031] Figure 2 Non-drive end view of wind turbine generator;

[0032] Figure 3 AA cross-section of wind turbine generator;

[0033] Figure 4 Cross-section of wind turbine motor BB;

[0034] Figure 5 Cross-section of wind turbine CC;

[0035] Figure 6 Partial view of sealing structure M;

[0036] Figure 7 Schematic diagram of the dynamic and static separation structure of the air outlet duct.

[0037] Figure 1: 1-rotor cylinder, 2-rotor magnet, 3-rotor non-drive end ring plate, 4-copper ring, 5-sixth ring plate, 6-seal mounting ring plate, 7-stator coil, 8-stator core, 9-first ring plate, 10-second radial ring plate, 11-third ring plate, 12-axial rib plate, 13-fourth ring plate, 14-fifth ring plate, 15-drive end ventilation space, 16-annular space, 17-air inlet cavity, 18-air outlet cavity, 19-air inlet pipe Duct, 20-first air outlet duct, 21-air gap, 22-stator end pressure plate, 23-tensioning screw, 24-radial ventilation channel, 25-ventilation channel steel, 26-pressure block, 27-C-type seal, 28-sealing ring plate, 29-blower, 30-seventh ring plate, 31-eighth ring plate, 32-ninth ring plate, 33-tenth ring plate, 34-second air outlet duct, 35-cabin, 36-space, 37-sealing pressure plate, 38-sealing structure M. DETAILED DESCRIPTION

[0038] The following will be combined with the accompanying drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Solid and dashed arrows are used to distinguish between cold air and hot air flow in the drawings, and ⊕ and ⊙ are used in the cross-sectional diagrams to indicate the vertical inflow and outflow directions of the airflow. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1

[0040] A method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude, wherein cooling air enters the annular space 16 from an air inlet duct 19 to cool the non-driving end of the stator coil 7;

[0041] At the same time, cooling air enters the air inlet cavity 17 from the annular space 16, flows from the air inlet cavity 17 to the radial ventilation channels 24 distributed circumferentially on the stator core 8, enters the air gap 21, flows from the air gap 21 to the radial ventilation channels 24 distributed circumferentially on the stator core 8 in the air outlet cavity 18, then enters the air outlet cavity 18, flows from the air outlet cavity 18 to the drive end ventilation space 15, and is discharged from the first air outlet duct 20;

[0042] The annular space 16 is the space at the non-driving end of the stator coil 7, and the air inlet duct 19 is used to allow cooling air to enter the annular space 16 to cool the non-driving end of the stator coil 7. The driving end ventilation space 15 is the space at the driving end of the stator coil 7, and the first air outlet duct 20 is used to allow cooling air to be discharged from the first air outlet duct 20 after heat exchange with the driving end of the stator coil 7 in the driving end ventilation space 15.

[0043] A cavity is formed between the stator core 8 and the stator base, and a second radial ring plate 10 is installed on the stator base, which divides the cavity into two left and right chambers; a plurality of axial ribs 12 are arranged at intervals in the cavity, and the axial ribs 12 divide the cavity into multiple axial cavities, and ventilation channels are provided on the second radial ring plate 10 to connect the left and right axial cavities to form an axially longer axial cavity. The axial cavities are evenly distributed along the circumference of the stator base, and the adjacent axially longer axial cavities are respectively an air inlet cavity 17 and an air outlet cavity 18.

[0044] When implementing, Figure 1As shown, the cooling air enters the annular space 16 from the air inlet duct 19, and the cooling air directly cools the non-driving end of the stator coil 7. Compared with the prior art, the non-driving end of the stator coil 7 is directly cooled, which reduces the distance of the cooling air flowing to the non-driving end of the stator coil 7. On the one hand, the cooling air can contact the non-driving end of the stator coil more quickly. On the other hand, the cooling air passes through the annular space 16, and the heat exchange generated by the annular space 16 is relatively small, so that the temperature difference of the cooling air when it flows from one end of the annular space 16 to the other end is small, which has a good cooling effect on the stator core 8 far away from the air inlet cavity 17, and improves the utilization rate of the cooling air; in the prior art, when the cooling air flows from the air gap at one end of the stator to the other end of the stator, the temperature of the cooling air gradually increases due to the heat dissipated by the stator core, stator coil, and rotor magnetic steel, and the cooling effect on the stator end is not significant; the cooling air cools the non-driving end of the stator coil 7, and at the same time, the cooling air from the annular space 16 After entering the air inlet cavity 17, the cooling air flows to the radial ventilation channels 24 distributed on the circumference of the stator core 8 corresponding to the air inlet cavity 17, flows to the air gap 21, and flows from the air gap 21 to the radial ventilation channels 24 distributed on the circumference of the stator core 8 corresponding to the air outlet cavity 18; on the other hand, the radial dimensions of the air inlet cavity 17 and the air outlet cavity 18 are large, and the wind resistance is reduced when the cooling air enters the air inlet cavity 17, and the cooling air entering the air inlet cavity 17 will increase, even if the cooling air flows from one end of the air inlet cavity 17 to the other end of the air inlet cavity 17 At the end, the temperature of the cooling air will be partially increased due to the influence of the heat dissipated by the stator core 8 and the stator coil 7. However, since the cooling air entering the air inlet cavity 17 is sufficient, the difference in the air volume of the radial ventilation channel 24 is reduced, so that the contact area between the cooling air and the stator core 8 is large, the contact time is long, the heat exchange time is long, and the heat exchange effect is high, so that each section of the stator core 8 and the stator coil 7 at each section of the stator core 8 can obtain more sufficient cooling air, thereby improving the cooling effect and having a significant temperature reduction effect.

[0045] Even if the air outlet pipe in the prior art with the authorization announcement number CN110429747B and the authorization announcement date of November 20, 2020, and the name of a method for reducing the circumferential temperature difference between the motor coil and the core, is used as the air inlet, the air enters from the air outlet pipe, the cooling air enters the air outlet cavity, flows to the stator ventilation groove corresponding to the air outlet cavity, and is released from the stator after being discharged from the air gap. In this process, due to the small radial size of the air outlet cavity and the large wind resistance, the cooling air entering the air outlet cavity is small, which will lead to the heat dissipation area of the stator core. The heat exchange efficiency is low. When the cooling air flows from one end of the air outlet cavity to the other end, the temperature of the cooling air gradually rises due to the heat dissipated by the stator core and stator coil. The higher temperature cooling air flows into the stator ventilation groove, resulting in uneven cooling of each section of the stator core and low cooling efficiency. The cooling air flows from the stator ventilation groove to the air gap, from the air gap to the two ends of the stator, and then is released from the stator. Because the cooling air has already exchanged heat with the stator core before flowing from the air gap to the two ends of the stator for cooling, the cooling effect is low. Compared with the present invention, it is difficult to achieve the cooling effect of the present invention by using the air outlet duct as the air inlet in the prior art.

[0046] Example 2

[0047] This embodiment further elaborates and supplements the implementation of the present invention on the basis of Embodiment 1.

[0048] like Figure 1-Figure 5 As shown, the stator frame includes a first ring plate 9, a second radial ring plate 10, a third ring plate 11 and a plurality of axial ribs 12 arranged in sequence on the inner diameter side back of the stator core 8, a fourth ring plate 13 is arranged between the first ring plate 9 and the second radial ring plate 10, one end of the fourth ring plate 13 is connected to the first ring plate 9, and the other end is connected to the second radial ring plate 10; a fifth ring plate 14 is arranged between the second radial ring plate 10 and the third ring plate 11, one end of the fifth ring plate 14 is connected to the second radial ring plate 10, and the other end is connected to the third ring plate 11, a cavity is surrounded by the first ring plate 9, the third ring plate 11, the fourth ring plate 13 and the fifth ring plate 14, the cavity is divided into two left and right chambers by the second radial ring plate 10, and a spacer is arranged between the left and right chambers. Multiple axial ribs 12, the axial ribs 12 divide the chamber into multiple axial cavities, the axial cavities are evenly distributed along the circumference of the stator base, the axial cavities in the left and right chambers correspond to each other one by one, and ventilation channels are provided on the second radial ring plate 10 to connect the axial cavities in the left and right chambers to form an axially longer axial cavity; ventilation channels are provided on the first ring plate 9 and the third ring plate 11 at intervals along the circumference, and the projection positions of the ventilation channels on the first ring plate 9 and the ventilation channels on the third ring plate 11 on the circumference are alternated; the connected axial cavities are connected to the annular space 16 through the ventilation channels on the third ring plate 11 to form an air inlet chamber 17, and the connected axial cavities are connected to the driving end ventilation space 15 through the ventilation channels on the first ring plate 9 to form an air outlet chamber 18.

[0049] The stator core 8 is arranged in the rotor cylinder 1, and the rotor magnet 2 is arranged between the rotor cylinder 1 and the stator core 8. A ventilation channel steel 25 is arranged between two adjacent sections of the stator core 8. The two sections of the stator core 8 and the ventilation channel steel 25 form a radially separated radial ventilation channel 24. The tensioning screw 23 passes through the multiple sections of the stator core 8, and both ends of the tensioning screw 23 are fixed with stator end pressure plates 22; an air gap 21 is set between the rotor magnet 2 and the stator core 8.

[0050] The rotor cylinder 1 is connected to the rotor non-drive end ring plate 3, and the rotor non-drive end ring plate 3 is connected to the sealing structure M38. A copper ring 4 is provided on the third ring plate 11, and a sixth ring plate 5 is provided below the copper ring 4. The sixth ring plate 5 is located between the third ring plate 11 and the rotor non-drive end ring plate 3. The sixth ring plate 5 is respectively connected to the third ring plate 11 and the rotor non-drive end ring plate 3. The sixth ring plate 5, the third ring plate 11, the stator end pressure plate 22, the rotor non-drive end ring plate 3, and the rotor cylinder 1 form an annular space 16 for cooling air to pass through. An air inlet duct 19 is provided on the rotor non-drive end ring plate 3, and the air inlet duct 19 is connected to the annular space 16; the cavity surrounded by the rotor cylinder 1 and the first ring plate 9 is the drive end ventilation space 15; at the drive end of the stator coil 7, a first air outlet duct 20 is installed on the rotor cylinder 1 at this position.

[0051] During implementation, cooling air enters the annular space 16 from the air inlet duct 19 to cool the non-driving end and the copper ring 4 of the stator coil 7. At the same time, the cooling air enters the air inlet cavity 17 through the ventilation holes on the third ring plate 11, and then flows to the air gap 21 through the radial ventilation channels 24 distributed on the corresponding circumference of the air inlet cavity 17. The cooling air flows from the air gap 21 to the air outlet cavity 18 through the radial ventilation channels 24 distributed on the corresponding circumference of the air outlet cavity 18. The heat in the middle of the stator coil 7, the heat generated by the stator core 8, and the heat generated by the rotor magnetic steel 2 are taken away by the cooling air circulating in the radial ventilation channels 24 and the air gap 21, completing the cooling of each section of the stator core 8 and the stator coil 7 at each section of the stator core 8. After entering the air outlet cavity 18, the cooling air flows into the driving end ventilation space 15 from the ventilation holes set on the first ring plate 9 corresponding to the air outlet cavity 18 to cool the driving end of the stator coil 7, and the cooling air flows out from the first air outlet duct 20.

[0052] Example 3

[0053] This embodiment further elaborates and supplements the implementation manner of the present invention on the basis of Embodiment 1 or 2.

[0054] The radial dimensions of the air inlet cavity 17 and the air outlet cavity 18 are not less than 100 mm. Compared with the prior art, the wind resistance is reduced when the cooling air enters the air inlet cavity 17, and the cooling air entering the air inlet cavity 17 increases. Even if the cooling air is affected by the heat dissipated by the stator core 8 and the stator coil 7 when flowing from one end of the air inlet cavity 17 to the other end of the air inlet cavity 17, which causes the temperature of the cooling air to partially increase, the cooling air entering the air inlet cavity 17 is sufficient, reducing the difference in air volume in the radial ventilation channel 24. This allows the cooling air to have a long contact time with the stator core 8, a long heat exchange time, and a high heat exchange effect. As a result, each section of the stator core 8 and the stator coil 7 located at each section of the stator core 8 receive more sufficient cooling air, thereby improving the cooling effect and achieving a significant temperature reduction effect.

[0055] The air gap 21 is 4-5 mm to ensure that the cooling air has sufficient space to flow.

[0056] The axial height of the radial ventilation channels 24 is 3-4 mm. This is more than 10% smaller than that of the prior art. This reduction in the height of the radial ventilation channels 24 increases the number of radial ventilation channels 24 without significantly increasing the total length of the core, thereby increasing the heat dissipation surface area and improving the cooling effect.

[0057] The total axial length of the multi-segment stator core 8 is over 1500 mm, with the stator core 8 having an axial length of 20-30 mm and being evenly distributed in the axial direction. Compared with the prior art, each stator core 8 in the present invention is 20% shorter than the stator core 8 of conventional large-capacity permanent magnet low-speed wind turbines. Because the stator core 8 and stator coil 7 are cooled by radial ventilation, the shorter the spacing between the radial ventilation channels 24, the greater the heat dissipation area of the stator core 8 and stator coil 7, improving the cooling effect.

[0058] like Figure 2 As shown, the air inlet ducts 19 and the first air outlet ducts 20 are evenly distributed along the circumference, and the number is 6-8. The number of blowers 29 is the same as the number of air inlet ducts 19. The multiple blowers 29, air inlet ducts 19, and first air outlet ducts 20 are evenly distributed around the circumference, which helps to make the cooling air flow more even around the circumference and helps to ensure ventilation and cooling effects.

[0059] Example 4

[0060] This embodiment further elaborates and supplements the implementation manner of the present invention on the basis of Embodiment 1, Embodiment 2 or Embodiment 3.

[0061] like Figure 7As shown, the end of the first air outlet duct 20 is connected to a dynamic and static separation structure with a seal, including a seventh ring plate 30, an eighth ring plate 31, a ninth ring plate 32, a tenth ring plate 33 and a sealing pressure plate 37, and a C-type seal 27. The seventh ring plate 30 is connected to the rotor cylinder 1, and the seventh ring plate 30 is connected to one end of the eighth ring plate 31 and rotates with the rotor cylinder 1. The ninth ring plate 32 is connected to the nacelle 35, and the ninth ring plate 32 is connected to the tenth ring plate 33. The C-type seal 27 is installed on the inner side of the tenth ring plate 33 with the help of the sealing pressure plate 37, and is connected to the eighth ring plate 31. The other end is squeezed to complete the sealing of the dynamic and static separation part, and the seventh ring plate 30, the eighth ring plate 31, the ninth ring plate 32, the tenth ring plate 33 and the C-type seal 27 together enclose a space 36; the corresponding position of the seventh ring plate 30 is provided with a ventilation hole to connect to the first air outlet duct 20, and the corresponding position of the ninth ring plate 32 is provided with a ventilation hole to connect to the second air outlet duct 34, and the second air outlet duct 34 is connected to the air outlet of the cabin 35. The cooling air enters the space 36 from the first air outlet duct 20, flows to the second air outlet duct 34 and the air outlet of the cabin 35, and is discharged into the atmosphere.

[0062] In this embodiment, the first air outlet duct is bent at 90 degrees, and the outlet of the first air outlet duct faces the non-driving end and is connected to the air outlet of the nacelle 35 .

[0063] like Figure 6 As shown, the sealing structure M38 includes a rotor non-driving end ring plate 3, a sealing mounting ring plate 6, a pressure block 26, a C-type seal 27, and a sealing ring plate 28. The sealing mounting ring plate 6, the pressure block 26, the C-type seal 27, and the sealing ring plate 28 are installed on the rotor non-driving end ring plate 3. Grooves for installing the C-type seal 27 are processed on both end faces on the inner diameter side of the rotor non-driving end ring plate 3, and the C-type seal 27 is fixed with the help of the pressure block 26. The lips of the C-type seal 27 are all facing the inner diameter side, and are squeezed together with the sealing ring plate 28 installed on the sealing mounting ring plate 6 to complete the sealing of the dynamic and static separation of the wind turbine.

Claims

1. A method for reducing the temperature difference of a long-core permanent magnet wind turbine stator at high altitude, characterized by: Cooling air enters the annular space (16) from the air inlet duct (19) to cool the non-driving end of the stator coil (7); At the same time, cooling air enters the air inlet cavity (17) from the annular space (16), flows from the air inlet cavity (17) to the radial ventilation channels (24) distributed circumferentially on the corresponding stator core (8), enters the air gap (21), flows from the air gap (21) to the radial ventilation channels (24) distributed circumferentially on the corresponding stator core (8) of the air outlet cavity (18), then enters the air outlet cavity (18), flows from the air outlet cavity (18) to the drive end ventilation space (15), and is discharged from the first air outlet duct (20); The annular space (16) is the space at the non-driving end of the stator coil (7), and the air inlet duct (19) is used to allow cooling air to flow into the annular space (16) to cool the non-driving end of the stator coil (7); the driving end ventilation space (15) is the space at the driving end of the stator coil (7), and the first air outlet duct (20) is used to allow cooling air to be discharged from the first air outlet duct (20) after heat exchange with the driving end of the stator coil (7) in the driving end ventilation space (15); A cavity is formed between the stator core (8) and the stator base, and a second radial ring plate (10) is installed on the stator base, and the second radial ring plate (10) divides the cavity into two left and right chambers; a plurality of axial ribs (12) are arranged at intervals in the chamber, and the axial ribs (12) divide the chamber into a plurality of axial cavities, and ventilation channels are provided on the second radial ring plate (10) to connect the left and right axial cavities to form an axially longer axial cavity, and the axial cavities are evenly distributed along the circumference of the stator base, and the adjacent axially longer axial cavities are respectively an air inlet cavity (17) and an air outlet cavity (18); The stator frame comprises a first ring plate (9), a second radial ring plate (10), a third ring plate (11) and a plurality of axial ribs (12) arranged in sequence on the inner diameter side back of the stator core (8); a fourth ring plate (13) is arranged between the first ring plate (9) and the second radial ring plate (10); one end of the fourth ring plate (13) is connected to the first ring plate (9) and the other end is connected to the second radial ring plate (10); a fifth ring plate (14) is arranged between the second radial ring plate (10) and the third ring plate (11); one end of the fifth ring plate (14) is connected to the second radial ring plate (10) and the other end is connected to the second radial ring plate (10). The end is connected to the third ring plate (11), and a cavity is formed by the first ring plate (9), the third ring plate (11), the fourth ring plate (13) and the fifth ring plate (14). The cavity is divided into two left and right chambers by the second radial ring plate (10). A plurality of axial ribs (12) are arranged between the left and right chambers. The axial ribs (12) divide the chamber into a plurality of axial cavities. The axial cavities are evenly distributed along the circumference of the stator frame. The axial cavities in the left and right chambers correspond to each other one by one. A ventilation duct is arranged on the second radial ring plate (10) to connect the axial cavities in the left and right chambers to form an axially longer axial cavity.

2. The method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to claim 1, characterized in that: Ventilation channels are arranged on the first ring plate (9) and the third ring plate (11) at intervals along the circumference, and the projection positions of the ventilation channels on the first ring plate (9) and the ventilation channels on the third ring plate (11) on the circumference are alternated; the connected axial cavity is connected to the annular space (16) through the ventilation channel on the third ring plate (11) to form an air inlet cavity (17), and the connected axial cavity is connected to the driving end ventilation space (15) through the ventilation channel on the first ring plate (9) to form an air outlet cavity (18).

3. The method for reducing the temperature difference of the stator of a long-core permanent magnet wind turbine at high altitude according to claim 2, characterized in that: The stator core (8) is arranged in the rotor cylinder (1), the rotor magnet (2) is arranged between the rotor cylinder (1) and the stator core (8), and a ventilation slot steel (25) is arranged between two adjacent stator core sections (8). The two stator core sections (8) and the ventilation slot steel (25) form a radially separated radial ventilation channel (24). The tensioning screw (23) passes through the multiple stator core sections (8), and both ends of the tensioning screw (23) are fixed by the stator end pressure plate (22); an air gap (21) is arranged between the rotor magnet (2) and the stator core (8).

4. The method for reducing the temperature difference of the stator of a long-core permanent magnet wind turbine at high altitude according to claim 3, characterized in that: The rotor cylinder (1) is connected to the rotor non-drive end ring plate (3), the rotor non-drive end ring plate (3) is connected to the sealing structure M (38), a copper ring (4) is provided on the third ring plate (11), a sixth ring plate (5) is provided below the copper ring (4), the sixth ring plate (5) is located between the third ring plate (11) and the rotor non-drive end ring plate (3), the sixth ring plate (5) is connected to the third ring plate (11) and the rotor non-drive end ring plate (3), respectively, and the sixth ring plate (5), the third ring plate (11), and the stator are connected to the rotor non-drive end ring plate (3). The rotor end pressure plate (22), the rotor non-driving end ring plate (3), and the rotor cylinder (1) form an annular space (16) through which cooling air passes. An air inlet duct (19) is provided on the rotor non-driving end ring plate (3), and the air inlet duct (19) is communicated with the annular space (16). The cavity enclosed by the rotor cylinder (1) and the first ring plate (9) is the driving end ventilation space (15). At the driving end of the stator coil (7), a first air outlet duct (20) is installed on the rotor cylinder (1) at this position.

5. The method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to any one of claims 1 to 4, characterized in that: The radial dimensions of the air inlet cavity (17) and the air outlet cavity (18) are not less than 100 mm.

6. A method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to any one of claims 1 to 4, characterized in that: The air gap (21) has a value of 4-5 mm.

7. A method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to any one of claims 1 to 4, characterized in that: The radial ventilation channel (24) has an axial height of 3-4 mm.

8. The method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to any one of claims 1 to 4, characterized in that: The total axial length of the multi-segment stator core (8) is more than 1500 mm, and the axial length of the stator core (8) is 20-30 mm and is evenly distributed in the axial direction.

9. The method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to any one of claims 1 to 4, characterized in that: The air inlet ducts (19) and the first air outlet ducts (20) are evenly distributed along the circumference and are 6-8 in number. The number of blowers (29) is the same as the number of air inlet ducts (19).

10. The method for reducing the temperature difference of the stator of a long-core permanent magnet wind turbine at high altitude according to claim 9, characterized in that: The end of the first air outlet duct (20) is connected to a dynamic and static separation structure with a seal, including a seventh ring plate (30), an eighth ring plate (31), a ninth ring plate (32), a tenth ring plate (33), a sealing pressure plate (37), and a C-type seal (27). The seventh ring plate (30) is connected to the rotor cylinder (1). The seventh ring plate (30) is connected to one end of the eighth ring plate (31) and rotates with the rotor cylinder (1). The ninth ring plate (32) is connected to the cabin (35). The ninth ring plate (32) is connected to the tenth ring plate (33). The C-type seal (27) is installed on the inner side of the tenth ring plate (33) with the help of the sealing pressure plate (37) and is connected to the eighth ring plate (31). The other end of the plate (31) is squeezed to complete the sealing of the dynamic and static separation part, and the seventh ring plate (30), the eighth ring plate (31), the ninth ring plate (32), the tenth ring plate (33) and the C-type seal (27) together enclose a space (36); a ventilation hole is opened at a corresponding position of the seventh ring plate (30) to connect to the first air outlet duct (20), and a ventilation hole is opened at a corresponding position of the ninth ring plate (32) to connect to the second air outlet duct (34), and the second air outlet duct (34) is connected to the air outlet of the cabin (35). The cooling air enters the space (36) from the first air outlet duct (20) and flows to the second air outlet duct (34) and the air outlet of the cabin (35) for discharge.

11. The method for reducing the temperature difference of a stator of a long-core permanent magnet wind turbine at high altitude according to claim 4, characterized in that: The sealing structure M (38) comprises a rotor non-driving end ring plate (3), a sealing mounting ring plate (6), a pressure block (26), a C-type seal (27), and a sealing ring plate (28). The sealing mounting ring plate (6), the pressure block (26), the C-type seal (27), and the sealing ring plate (28) are installed on the rotor non-driving end ring plate (3); grooves for installing the C-type seal (27) are processed on both end surfaces on the inner diameter side of the rotor non-driving end ring plate (3), and the C-type seal (27) is fixed with the help of the pressure block (26). The lips of the C-type seal (27) are all facing the inner diameter side, and are squeezed together with the sealing ring plate (28) installed on the sealing mounting ring plate (6) to complete the sealing of the dynamic and static separation of the wind turbine.

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