A stator frame for reducing the temperature difference of the stator in a long-core permanent magnet wind turbine at high altitudes

Abstract

This invention discloses a stator frame for reducing the temperature difference of the stator in a long-core permanent magnet wind turbine at high altitudes, relating to the field of permanent magnet direct-drive wind turbine technology. The frame consists of a cavity formed by a first ring plate, a third ring plate, a fourth ring plate, and a fifth ring plate. A second ring plate divides the cavity into left and right chambers. Multiple axial stiffeners are spaced apart within each chamber, further dividing it into multiple axial cavities. These axial cavities are evenly distributed along the circumference of the stator frame. Ventilation channels on the second ring plate connect the left and right axial cavities, forming an axially longer cavity. Adjacent axially longer cavities are respectively an air inlet cavity and an air outlet cavity. The air inlet cavity is connected to the external air inlet space, and the air outlet cavity is connected to the external air outlet space. This reduces the difference in airflow in the stator core ventilation channels, thereby ensuring more sufficient air cooling for each core segment and the stator coils located within each core segment, improving the cooling effect.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet direct-drive wind turbine technology, specifically to a stator frame for reducing the stator temperature difference in high-altitude long-core permanent magnet wind turbines. Background Technology

[0002] Low-speed permanent magnet wind turbines operate at low speeds, only around 10 r / min. The pressure generated by the rotating parts is only a few Pascals, insufficient to drive airflow within the motor to remove operating losses. A dedicated fan is typically used as the primary pressure source for airflow. However, for larger-capacity low-speed permanent magnet wind turbines with longer cores, radial ventilation is employed. Cooling air passes through the stator, enters the air gap, diffuses to both ends of the core, and finally passes through the stator winding ends and ventilation ducts. Due to the longer core, the ventilation path for directly cooling the stator is long. Furthermore, structural limitations prevent the fans from being evenly distributed around the frame, resulting in uneven temperature distribution around the stator coils and core, 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 a Chinese patent, authorization announcement number CN110429747B, authorization announcement date November 20, 2020, entitled "A Method for Reducing the Circumferential Temperature Difference Between Motor Coils and Core," cooling air enters the large cavity from the lower air inlet duct. Simultaneously, the cooling air enters the air gap from the large cavity and cools the ends of the stator core. The cooling air enters the air gap and undergoes turbulence before entering the stator ventilation grooves for heat exchange. However, since the stator core is relatively long, the temperature of the cooling air during its journey from one end of the stator air gap to the other is affected by the heat generated by the stator core, stator coils, and rotor magnets. The temperature of the cooling air gradually increases as the travel distance increases, resulting in uneven cooling of each segment of the stator core and low cooling efficiency. Cooling air enters the air inlet cavity from the large cavity. Due to the small radial dimension of the air inlet cavity, the air resistance is high, resulting in less cooling air entering. This leads to shorter direct contact time with the stator core, shorter heat exchange time, and lower heat exchange efficiency. Furthermore, as the cooling air flows from one end of the air inlet cavity to the other, its temperature gradually increases due to the heat generated by the stator core and stator coils, further contributing to uneven cooling of each segment of the stator core and low cooling efficiency.

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

[0005] To address the shortcomings of the existing technology, this invention constructs a cooling path for the wind turbine by using a stator frame that reduces the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes. This cooling path cools the stator core and stator coils, and ensures that each segment of the stator core and the stator coils at each segment receive more sufficient cooling air, thereby improving the cooling effect, reducing the stator temperature difference, and increasing the efficiency of cooling air utilization. This allows the invention to adapt to the unfavorable conditions of lower air density at high altitudes.

[0006] This invention is achieved through the following technical solution:

[0007] A stator frame for reducing the stator temperature difference in high-altitude long-core permanent magnet wind turbines is characterized by: a central flange connected to the stator shaft; a second ring plate fixed on the central flange; a first ring plate on one side of the second ring plate; a third ring plate on the other side of the second ring plate; a fourth ring plate between the first and second ring plates, with one end of the fourth ring plate connected to the first ring plate and the other end connected to the second ring plate; and a fifth and sixth ring plate arranged sequentially between the second and third ring plates, each ring plate connected to the second and third ring plates respectively. The cavity is formed by the first, third, fourth, and fifth ring plates. The second ring plate divides the cavity into left and right chambers. Multiple axial stiffeners are set at intervals in the chambers, dividing the chambers into multiple axial cavities. The axial cavities are evenly distributed along the circumference of the stator base. Ventilation channels are set on the second ring plate to connect the left and right axial cavities to form an axially longer cavity. Adjacent axially longer cavities are respectively the air inlet cavity and the air outlet cavity. The air inlet cavity is connected to the external air inlet space, and the air outlet cavity is connected to the external air outlet space.

[0008] Furthermore, the first ring plate is provided with first ventilation channels at intervals along the circumference for connecting the air outlet cavity to the external air outlet space; the third ring plate is provided with second ventilation channels at intervals along the circumference for connecting the air inlet cavity to the external air inlet space.

[0009] Furthermore, the number of first ventilation channels provided on the first ring plate is the same as the number of second ventilation channels provided on the third ring plate.

[0010] Furthermore, the projections of the first ventilation duct and the second ventilation duct on the circumference alternate.

[0011] Furthermore, the radial dimensions of the air inlet and outlet chambers are not less than 100 mm to reduce wind friction loss at the air chamber location and ensure ventilation volume.

[0012] Furthermore, the axial length of the air inlet and outlet chambers is equal to the total length of the stator core, and is set to be 1500 mm or more.

[0013] Furthermore, the outer circle of the outer end face of the third ring plate serves as the installation space for the copper ring at the end of the wind turbine.

[0014] Furthermore, it also includes a seventh ring plate, an eighth ring plate, and a terminal box; the seventh ring plate is vertically connected to the third ring plate, the eighth ring plate is connected to the seventh ring plate, and the terminal box is located below the seventh ring plate, forming a wind turbine stator lead-out device structure.

[0015] Furthermore, the inner end face and the outer circle of the outer end face of the eighth ring plate are both machined with annular grooves for installing a sealing structure during the subsequent assembly of the wind turbine.

[0016] Furthermore, the first ring plate, second ring plate, third ring plate, fourth ring plate, fifth ring plate, sixth ring plate, seventh ring plate, and eighth ring plate are welded from carbon steel plates.

[0017] The working principle of this invention is as follows:

[0018] A stator frame for reducing the temperature difference of the stator in a high-altitude long-core permanent magnet wind turbine is installed on the back side of the stator core within the wind turbine. Cooling air cools the non-driving end of the stator coil and the copper ring in the external air intake space. Simultaneously, the cooling air enters the air intake cavity through the second ventilation channel 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 intake cavity. From the air gap, the cooling air flows to the air outlet cavity through the radial ventilation channels distributed on the corresponding circumference of the air outlet cavity, and then flows to the external air outlet space through the first ventilation channel to cool the driving end of the stator coil. Through the action of the air intake and air outlet cavities corresponding to the back side of the stator core's inner diameter, the air velocity through the corresponding radial ventilation channels is evenly distributed axially, reducing the difference in air volume in the radial ventilation channels. This ensures that each segment of the stator core and the stator coil at each segment receive sufficient and uniform cooling air, thereby improving the cooling effect.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. Compared to the method of cooling air entering from the air gap and then cooling through the radial ventilation channel, it can reduce the difference in air volume of the stator core radial ventilation channel, so that each core section and the stator coil in each core section can receive more sufficient air cooling and improve the cooling effect.

[0021] 2. The air inlet and outlet chambers of the base of the present invention are circumferentially distributed, which provides favorable conditions for the uniform distribution of the subsequent air inlet and outlet, and facilitates the cooling air to be more uniform on the circumference, thus ensuring the ventilation and cooling effect.

[0022] 3. The outer circle of the outer end face of the third ring plate can be used as the installation space for the copper ring at the end of the wind turbine. During ventilation and cooling, the copper ring can be cooled directly.

[0023] 4. The inner end face and outer circle of the outer end face of the eighth ring plate are both machined with annular grooves to install the sealing structure in the subsequent assembly of the wind turbine. The sealing structure completes the sealing at the separation point between the rotor and the stator, and the cooling air will not be lost from the separation point, ensuring the utilization rate of cooling air and providing more sufficient cooling air to directly cool the non-driving end of the stator coil. Attached Figure Description

[0024] Figure 1 Longitudinal section of the stator frame;

[0025] Figure 2 Cross section view of stator frame AA;

[0026] Figure 3 Cross section view of stator frame BB;

[0027] Figure 4 Cross section view of the stator frame (CC section);

[0028] Figure 5 Schematic diagram of the stator frame.

[0029] Reference numerals: 1-Center flange, 2-Second ventilation duct, 3-Ventilation duct, 4-First ventilation duct, 5-Seventh ring plate, 6-Eighth ring plate, 7-Cable outlet box, 8-Sixth ring plate, 9-First ring plate, 10-Second ring plate, 11-Third ring plate, 12-Axial stiffener, 13-Fourth ring plate, 14-Fifth ring plate, 15-External air outlet space, 16-External air inlet space, 17-Air inlet cavity, 18-Air outlet cavity. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0031] like Figures 1-5As shown, a stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes includes a central flange 1 connected to the stator shaft. A second ring plate 10 is fixed on the central flange 1. A first ring plate 9 is arranged on one side of the second ring plate 10, and a third ring plate 11 is arranged on the other side of the second ring plate 10. A fourth ring plate 13 is arranged between the first ring plate 9 and the second ring plate 10, with one end of the fourth ring plate 13 connected to the first ring plate 9 and the other end connected to the second ring plate 10. A fifth ring plate 14 and a sixth ring plate 8 are arranged vertically between the second ring plate 10 and the third ring plate 11, with the fifth ring plate 14 and the sixth ring plate 8 respectively connected to the second ring plate 10 and the third ring plate 11. 11 Connection; The 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 second ring plate 10 divides the cavity into two chambers, left and right. Multiple axial stiffeners 12 are arranged at intervals in the chamber, and the axial stiffeners 12 divide the chamber into multiple axial cavities. The axial cavities are evenly distributed along the circumference of the stator base. The second ring plate 10 is provided with ventilation channels 3 to connect the left and right axial cavities to form an axially longer axial cavity. The adjacent axially longer axial cavities are the air inlet cavity 17 and the air outlet cavity 18, respectively. The air inlet cavity 17 is connected to the external air inlet space 16, and the air outlet cavity 18 is connected to the external air outlet space 15.

[0032] Furthermore, the first ring plate 9 is provided with first ventilation channels 4 at intervals along the circumference for connecting the air outlet cavity 18 to the external air outlet space 15; the third ring plate 11 is provided with second ventilation channels 2 at intervals along the circumference for connecting the air inlet cavity 17 to the external air inlet space 16.

[0033] Furthermore, the number of first ventilation channels 4 provided on the first ring plate 9 is the same as the number of second ventilation channels 2 provided on the third ring plate 11.

[0034] Furthermore, the projections of the first ventilation channel 4 and the second ventilation channel 2 on the circumference alternate.

[0035] In this embodiment, by providing a first ventilation channel 4 and a second ventilation channel 2 at circumferential intervals along the first ring plate 9 and the third ring plate 11 respectively, half of the axially connected cavity is an air inlet cavity 17 and the other half is an air outlet cavity 18. The first ventilation channel 4 connects the air outlet cavity 18 to the external air outlet space 15, and the second ventilation channel 2 connects the air inlet cavity 17 to the external air inlet space 16. Since the air inlet cavity 17 is distributed circumferentially, the airflow is evenly distributed circumferentially after the cooling air enters the air inlet cavity 17, preventing uneven airflow distribution and thus avoiding uneven cooling. Example 2

[0036] This embodiment further elaborates and supplements the implementation of the present invention based on Embodiment 1.

[0037] The axial length of the air inlet cavity 17 and the air outlet cavity 18 is equal to the total length of the stator core, and is set to be 1500 mm or more.

[0038] The outer circle of the outer end face of the third ring plate 11 serves as the installation space for the end copper ring of the wind turbine. The stator frame constructs a cooling path for the wind turbine, ensuring sufficient cooling for the end copper ring.

[0039] It also includes a seventh ring plate 5, an eighth ring plate 6, and a terminal box 7; the seventh ring plate 5 is vertically connected to the third ring plate 11, the eighth ring plate 6 is connected to the seventh ring plate 5, and the terminal box 7 is located below the seventh ring plate 5, forming a wind turbine stator lead-out device structure.

[0040] The inner end face and outer circle of the outer end face of the eighth ring plate 6 are both machined with annular grooves for installing sealing structures during the subsequent assembly of the wind turbine.

[0041] The first ring plate 9, the second ring plate 10, the third ring plate 11, the fourth ring plate 13, the fifth ring plate 14, the sixth ring plate 8, the seventh ring plate 5, and the eighth ring plate 6 are welded from carbon steel plates. Example 3

[0042] This embodiment further elaborates and supplements the implementation of the present invention based on Embodiment 1 or Embodiment 2.

[0043] After assembling a stator frame for reducing the stator temperature difference in a high-altitude long-core permanent magnet wind turbine with the wind turbine, cooling air cools the non-driving ends and copper rings of the stator coils in the external air intake space 16. Simultaneously, the cooling air enters the air intake cavity 17 through the second ventilation channel 2, flows to the radial ventilation channels distributed on the circumference of the stator core corresponding to the air intake cavity 17, then flows to the air gap, and from the air gap to the air outlet cavity 18 through the radial ventilation channels distributed on the circumference of the stator core corresponding to the air outlet cavity 18. Finally, it flows through the first ventilation channel 4 to the external air outlet space 15 to cool the stator coils. The driving end of the coil is cooled; the circulating cooling air carries away the heat generated in the middle of the stator coil, the heat generated in the stator core, and the heat generated in the rotor magnet. Furthermore, the radial dimensions of the air inlet cavity 17 and the air outlet cavity 18 are large, which reduces the wind resistance when the cooling air enters the air inlet cavity 17. This increases the amount of cooling air entering the air inlet cavity 17, making the contact area between the cooling air and the stator large enough, resulting in sufficient and effective heat exchange. This allows each section of the stator core and the stator coil located in each section of the stator core to receive more cooling air, improving the cooling effect and significantly reducing the temperature.

[0044] In this embodiment, the radial dimensions of the air inlet cavity 17 and the air outlet cavity 18 are not less than 100 mm, which reduces wind resistance and ensures ventilation volume.

[0045] This invention improves the cooling effect, reduces the stator temperature difference, and increases the utilization efficiency of cooling air, thereby adapting to the unfavorable conditions of lower air density in high-altitude areas. Moreover, this invention has a simple structure and is easy to implement.

[0046] Even if the existing technology with authorization announcement number CN110429747B, authorization announcement date November 20, 2020, entitled "A Method for Reducing the Circumferential Temperature Difference between Motor Coils and Cores" uses the air outlet pipe as the air inlet, 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 exiting through the air gap. In this process, due to the small radial dimension of the air outlet cavity and the large air resistance, less cooling air enters the air outlet cavity, which leads to the cooling air coming into contact with the stator core. The reduced surface area results in low heat exchange efficiency. When cooling air flows from one end of the outlet cavity to the other, its temperature gradually increases due to the heat generated by the stator core and stator coils. The warmer air flows towards the stator ventilation groove, leading to uneven cooling of each section of the stator core and low cooling efficiency. Furthermore, the cooling air flows from the ventilation groove to the air gap, then from the air gap to both ends of the stator before being released. Since the cooling air has already exchanged heat with the stator core, its cooling effect is low when it flows from the air gap to the ends of the stator again. Compared to this invention, using the existing outlet duct as the inlet is unlikely to achieve the same cooling effect.

Claims

1. A stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes, characterized in that: The system includes a central flange (1) connected to a fixed shaft, a second ring plate (10) fixed on the central flange (1), a first ring plate (9) on one side of the second ring plate (10), a third ring plate (11) on the other side of the second ring plate (10), a fourth ring plate (13) between the first ring plate (9) and the second ring plate (10), one end of the fourth ring plate (13) being connected to the first ring plate (9), and the other end being connected to the second ring plate (10); a fifth ring plate (14) and a sixth ring plate (8) are arranged vertically between the second ring plate (10) and the third ring plate (11), and both the fifth ring plate (14) and the sixth ring plate (8) are connected to the second ring plate (10) and the third ring plate (11) respectively; the first ring plate (14) is connected to the second ring plate (10) and the third ring plate (11) respectively; the system is composed of a central flange (1) connected to a fixed shaft, a second ring plate (10) fixed on the central flange (1), a second ring plate (10) fixed on the central flange (1), a third ring plate (11) on the other side of the second ring plate (10), a third ring plate (11) on the other side of the second ring plate (10), a fourth ring plate (13) between the first ring plate (9) and the second ring plate (10), a fifth ring plate (14) and a sixth ring plate (8) between the second ring plate (10) and the third ring plate (11) respectively; the system is composed of a central flange (1) connected to a fixed shaft, a second ring plate (10) fixed on the central flange (1), a second ring plate (10) fixed on the central flange (1), a third ring plate (11) between the second ring plate (10) and the third ring plate (11) respectively; the system is composed of a central flange (1) connected to the second ring plate (10) and the third ring plate (11) respectively; the system is composed of a central flange (1 Plate (9), third ring plate (11), fourth ring plate (13) and fifth ring plate (14) form a cavity. Second ring plate (10) divides the cavity into left and right chambers. Multiple axial stiffeners (12) are set at intervals in the chamber. The axial stiffeners (12) divide the chamber into multiple axial cavities. The axial cavities are evenly distributed along the circumference of the stator base. Ventilation holes (3) are set on the second ring plate (10) to connect the left and right axial cavities to form a longer axial cavity. The adjacent longer axial cavities are the air inlet cavity (17) and the air outlet cavity (18). The air inlet cavity (17) is connected to the external air inlet space (16), and the air outlet cavity (18) is connected to the external air outlet space (15). The radial dimensions of the air inlet cavity (17) and the air outlet cavity (18) are not less than 100 mm.

2. The stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes as described in claim 1, characterized in that: The first ring plate (9) is provided with first ventilation channels (4) at intervals along the circumference for connecting the air outlet cavity (18) to the external air outlet space (15); the third ring plate (11) is provided with second ventilation channels (2) at intervals along the circumference for connecting the air inlet cavity (17) to the external air inlet space (16).

3. The stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes as described in claim 2, characterized in that: The number of first ventilation channels (4) provided on the first ring plate (9) is the same as the number of second ventilation channels (2) provided on the third ring plate (11).

4. A stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes, as described in claim 2 or 3, characterized in that: The projections of the first ventilation channel (4) and the second ventilation channel (2) on the circumference alternate.

5. A stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes, as described in claim 2 or 3, characterized in that: The axial lengths of the air inlet cavity (17) and the air outlet cavity (18) are equal to the total length of the stator core.

6. The stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes as described in claim 2, characterized in that: The outer circle of the outer end face of the third ring plate (11) serves as the installation space for the copper ring at the end of the wind turbine.

7. The stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes as described in claim 6, characterized in that: It also includes a seventh ring plate (5), an eighth ring plate (6) and a terminal box (7); the seventh ring plate (5) is vertically connected to the third ring plate (11), the eighth ring plate (6) is connected to the seventh ring plate (5), and the terminal box (7) is located below the seventh ring plate (5), forming a wind turbine stator lead-out device structure.

8. The stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes as described in claim 7, characterized in that: The inner end face and outer circle of the outer end face of the eighth ring plate (6) are both machined with annular grooves for installing a sealing structure in the subsequent assembly of the wind turbine.

9. A stator frame for reducing the stator temperature difference of a long-core permanent magnet wind turbine at high altitudes, as described in claim 7 or 8, characterized in that: The first ring plate (9), the second ring plate (10), the third ring plate (11), the fourth ring plate (13), the fifth ring plate (14), the sixth ring plate (8), the seventh ring plate (5), and the eighth ring plate (6) are welded from carbon steel plates.

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