Air-cooled island permanent magnet synchronous motor

Abstract

This invention provides an air-cooled island permanent magnet synchronous motor, comprising a motor body including several groups of disc motors stacked along the same axis, with a certain distance between the disc motors to form a heat dissipation gap; and a heat dissipation system including an air supply device and an air supply duct. The air supply device supplies air into the air supply duct, which extends to the heat dissipation gap between the disc motors and has an air outlet at the end face of the motor body. The airflow exits from the air supply duct and dissipates heat from the disc motors through the end face of the disc motors. This air-cooled island permanent magnet synchronous motor, through its motor body composed of multiple stacked disc motors, achieves direct drive operation of the air-cooled island blades at low speeds, thus optimizing the air-cooled island drive system, improving the energy utilization efficiency of the drive system, and facilitating maintenance. The heat dissipation system prevents abnormal temperature rise during disc motor operation, contributing to the long-term safe operation of the equipment.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, and specifically to an air-cooled island permanent magnet synchronous motor. Background Technology

[0002] Power plants generate electricity by driving turbines through the expansion of steam. To achieve the circulation of the working medium, the steam needs to be cooled in the loop before entering the next cycle. Steam cooling can be achieved using water cooling or air cooling. Integrated cooling equipment using air cooling is called an air-cooled island. The air-cooled island removes heat from the steam flowing within the fins by air flowing over the fin surface, causing the steam to condense. Existing air-cooled island equipment uses large AC motors for driving. Due to the limited low-speed performance of AC motors, high-speed operation is required, along with a bulky mechanical reducer for speed reduction. This firstly reduces the system's energy conversion efficiency, and secondly, it complicates the system composition, making daily maintenance difficult. Summary of the Invention

[0003] To address the problems of low energy conversion efficiency and complex system composition in existing air-cooled island drive systems, this invention provides an air-cooled island permanent magnet synchronous motor for direct drive of air-cooled islands.

[0004] The technical solution of the present invention provides an air-cooled island permanent magnet synchronous motor, comprising:

[0005] The motor body includes several groups of disc motors stacked along the same axis, with a certain distance between the disc motors to form a heat dissipation gap;

[0006] A heat dissipation system includes an air supply device and an air supply duct. The air supply device supplies air into the air supply duct. The air supply duct extends to the heat dissipation gap between the disc motors and provides an airflow outlet at the end face of the motor body. After the airflow is discharged from the air supply duct, it dissipates heat from the disc motor through the end face of the disc motor.

[0007] Preferably, the air supply duct includes a cooling air duct, which is disposed in the heat dissipation gap between the disc motors and at the cooling air ducts at both ends of the motor body, and the outer surface of the cooling air duct forms an air outlet channel with the end face of the disc motor.

[0008] Preferably, the cooling duct is an annular channel, the end face of the cooling duct is close to the end face of the disc motor, and air outlets are provided on the two opposite end faces of the cooling duct for releasing airflow.

[0009] Preferably, the cooling duct is an annular channel, and an air outlet is provided on the inner surface of the duct on the inner side of the two opposite end faces of the cooling duct, the air outlet being used to release airflow.

[0010] Preferably, the air supply duct further includes a main air duct, which connects the air supply device to multiple cooling air ducts, and the main air duct is used to transport the airflow provided by the air supply device to multiple sets of cooling air ducts.

[0011] Preferably, multiple sets of the cooling air duct winding motor are evenly arranged circumferentially.

[0012] Preferably, multiple sets of cooling air ducts are arranged from top to bottom, and the multiple sets of cooling air ducts are sequentially connected to the main air duct. The cross-sectional area of ​​the main air duct decreases sequentially as the cooling air ducts are connected.

[0013] Preferably, the heat dissipation system further includes a secondary air duct, which connects the cooling air duct and the main air duct, wherein the area of ​​the reduced flow channel cross-section of the main air duct is equal to the flow channel cross-section of the secondary air duct currently connected to the cooling air duct.

[0014] Preferably, the disc motor has heat dissipation fins arranged circumferentially on its motor end face, and a heat dissipation channel for airflow is formed between adjacent heat dissipation fins.

[0015] Preferably, the disc motor includes a stator that is relatively fixed and a rotor that is relatively movable, with the rotor shaft arranged along the axis; the rotor has a rotor yoke perpendicular to the shaft, and magnets are arranged in a ring on both ends of the rotor yoke, with the outer surfaces of the magnets arranged on each end of the rotor yoke having opposite magnetic poles; the stator has coil windings evenly arranged in the annular region of the magnets outside the two ends of the rotor yoke.

[0016] Preferably, the rotor yoke is further provided with a magnet cover, the magnet cover having uniformly opened magnet grooves along the circumference for accommodating magnets, the magnets being fixed in the magnet grooves of the magnet cover, and the magnet cover being fastened to the rotor yoke for fixation.

[0017] Preferably, the shafts of several groups of disc motors are flexibly connected to transmit torque.

[0018] Preferably, one end of the rotating shaft is provided with a magnetic coupling disk perpendicular to the rotating shaft, and magnets are arranged in a ring on one side of the outer end face of the magnetic coupling disk, with the magnetic poles of adjacent magnets facing the outer side of the end face of the magnetic coupling disk being opposite. The rotating shafts of the stacked disc motors are basically collinear, and the magnetic coupling disks at the ends of the two rotating shafts are directly opposite and close to each other.

[0019] The air-cooled island permanent magnet synchronous motor of this invention achieves direct drive operation of the air-cooled island blades at low speeds through a motor body composed of multiple stacked disc motors. This eliminates the need for the original AC motor and reducer assembly, thus optimizing the air-cooled island drive system, improving energy utilization efficiency, and facilitating maintenance. Furthermore, to address heat dissipation issues during low-speed operation, the air-cooled island permanent magnet synchronous motor is equipped with a cooling system. This system forces airflow to the end faces of the disc motors through cooling ducts, achieving convective heat dissipation and preventing temperature rise during operation. This ensures that the permanent magnets inside the disc motors do not demagnetize due to high temperatures, and also contributes to the long-term safe operation of the equipment. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the air-cooled island permanent magnet synchronous motor of the present invention;

[0021] Figure 2 This is a schematic diagram of the heat dissipation system 2 of the air-cooled island permanent magnet synchronous motor of the present invention;

[0022] Figure 3 This is a schematic diagram of the cooling duct 221 of the air-cooled island permanent magnet synchronous motor of the present invention;

[0023] Figure 4 This is a schematic diagram of another embodiment of the cooling duct 221 of the air-cooled island permanent magnet synchronous motor of the present invention;

[0024] Figure 5 This is a schematic diagram of the disc motor 11 of the air-cooled island permanent magnet synchronous motor of the present invention;

[0025] Figure 6 This is a schematic diagram of the internal structure of the disc motor 11 of the air-cooled island permanent magnet synchronous motor of the present invention.

[0026] Figure 7 This is an exploded schematic diagram of the rotor 14 of the air-cooled island permanent magnet synchronous motor of the present invention;

[0027] Figure 8 This is a schematic diagram of the rotating shaft 12 of the air-cooled island permanent magnet synchronous motor of the present invention.

[0028] In the picture,

[0029] 1: Motor body 11: Disc motor 2: Cooling system 21: Air supply device 22: Air supply duct 11A: Cooling fins 11B: Cooling flow channel 221: Cooling air duct 222: Main air duct 223: Secondary air duct 21A: Air duct end face 21B: Air duct inner vertical surface 21H: Air outlet 13: Stator 14: Rotor 131: Motor end face 132: Coil winding 133: Winding core 141: Rotor yoke 142: Magnet 143: Magnet cover 431: Magnet slot 12: Shaft 121: Magnetic coupler disc Detailed Implementation

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions of the drawings do not represent the actual dimensions. They are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numeral represent similar or identical structures and are limited to illustrative purposes.

[0031] Figure 1 This is a schematic diagram of the overall structure of the air-cooled island permanent magnet synchronous motor of the present invention. The operating speed range of the large air-cooled island motor is approximately 30-150 RPM, and the operating torque depends on the specific operating conditions, generally ranging from 5-20 kN·m. Due to the good low-speed performance of the permanent magnet synchronous motor, it can be used to directly drive the air-cooled island blades to drive existing large AC motors and reducers, etc.

[0032] The air-cooled island permanent magnet synchronous motor further enhances its load drive performance by stacking multiple disc-type permanent magnet motors. As shown in the figure, the air-cooled island permanent magnet synchronous motor first includes a motor body 1 for power output. The motor body 1 includes several coaxially connected disc motors 11, which are stacked along the shaft. To achieve low-speed, high-torque output of the motor body 1, a large alternating current needs to be passed through the coil windings of the motor body 1, which leads to significant heat loss. However, due to the low rotor speed (less than 300 RPM), even with heat dissipation fins on the rotor, it is insufficient to effectively dissipate heat from the motor body 1 and maintain its thermal balance. Furthermore, at higher temperatures, the permanent magnets may demagnetize due to heat, resulting in a decrease in magnetic field strength and irreversible damage to the motor performance. Excessive temperatures can also damage the coil windings, posing potential safety risks. Therefore, the motor body 1 not only needs to perform basic drive functions but also requires a cooling system 2. The heat dissipation system 2 has an independent air supply device 21 and an air supply duct 22. The outlet of the air supply duct 22 extends into the outer side of the end face of each disc motor 11. The air supply device 21 can be a power-driven blade. The air supply device 21 blows air into the air supply duct 22, and the disc motor 11 is forced to dissipate heat through air convection.

[0033] Figure 2 This is a schematic diagram of the heat dissipation system 2. A heat dissipation gap is reserved between the disc motors 11. The air supply duct 22 includes a cooling air duct 221 disposed within the heat dissipation gap, cooling air ducts 221 at both ends of the motor body 1, and a main air duct 222 connecting the air supply device 21 and the cooling air ducts 221. External airflow driven by the air supply device 21 is delivered to the cooling air duct 221 via the main air duct 222 and ejected from the cooling air duct 221, flowing out into the outside through the gap between the end face of the disc motor 11 and the cooling air duct 221, thereby accelerating the gas flow at the end face of the disc motor 11 and thus accelerating the heat dissipation at the end face of the disc motor 11. Figure 2 In one specific embodiment of the air supply duct 22, multiple main air ducts 222 are distributed along the circumference of the motor body 1 after being led out from the air supply device 21. Preferably, the main air ducts 222 are evenly distributed along the circumference. Figure 2 In the case of two groups distributed at an angle of 180 degrees, the permanent magnet synchronous motor of the air-cooled island is usually set at the top of the air-cooled island, and the power shaft drives the blades and other devices below. Therefore, the air supply device 21 is often set at the top of the motor body 1. In order to connect the air supply device 21 and the cooling air duct 221, the main air duct 222 is led out from the air supply device 21 and extends downward along the edge of the disc motor 11, and connects to the cooling air duct 221 through the secondary air duct 223. As mentioned earlier, cooling air ducts 221 are installed in the gaps of the disc motor 11 and on the end face of the motor body 1. Therefore, multiple cooling air ducts 221 are installed from top to bottom. These multiple cooling air ducts 221 are sequentially connected to the main air duct 222. The cross-section of the main air duct 222 is stepped, shrinking once each time it connects to another main air duct 222. The reduction in the cross-section of the main air duct 222 is equal each time. The reduction in the cross-section of the main air duct 222 may not be equal to the cross-sectional area of ​​the currently connected secondary air duct 223, but it should be at least smaller than the cross-sectional area of ​​the secondary air duct 223 to ensure that the airflow entering the secondary air duct 223 is mainly determined by the main air duct 222 rather than by the secondary air duct 223. Of course, the preferred situation is that the reduced cross-sectional area of ​​the main air duct 222 is equal to the cross-sectional area of ​​the secondary air duct 223. This is to ensure that the airflow in each cooling air duct 221 is basically consistent.

[0034] Figure 3This is a schematic diagram of the cooling air duct 221. The cooling air duct 221 is positioned between the disc motors 11, with its end face 21A close to the disc motors 11 positioned on both sides of the cooling air duct 221. To ensure effective airflow, an air outlet channel or gap is provided between the disc motors 11 and the cooling air duct 221. Air outlet holes 21H are provided on the end face 21A of the air duct for airflow. Clearly, when the cooling air duct 221 is positioned between the disc motors 11, air outlet holes 21H should be provided on both sets of opposing end faces 21A of the cooling air duct 221, thereby creating airflow at the end faces of the disc motors 11 on both sides. There is another special case here. When the cooling air duct 221 is set on both ends of the motor body 1, only one side end face 21A of the cooling air duct 221 is close to the end face of the disc motor 11. Therefore, it is preferable to set the air outlet 21H on only one side end face 21A of the cooling air duct 221 that is close to the end face of the disc motor 11. Figure 4 In another embodiment of the cooling duct 221, air outlets 21H are provided on the inner surface 21B of the duct on the inner side of the connecting sides of the cooling duct 221. After the air is discharged from the air outlets 21H, it flows into the gap or channel between the disc motor 11 on the upper and lower sides and the end face of the duct to achieve heat exchange with the end face of the disc motor 11. The air outlets 21H can also be provided on both the end face 21A and the inner surface 21B of the duct. Preferably, the air outlets 21H should be evenly distributed circumferentially on the end face 21A or the inner surface 21B of the duct to ensure uniform heat dissipation of the end face of the disc motor 11 as much as possible.

[0035] Figure 5 This is a schematic diagram of the end face of the disc motor 11. The motor end face 131 of the disc motor 11 has circumferentially spaced heat dissipation fins 11A, and adjacent heat dissipation fins 11A form heat dissipation channels 11B. Air flowing out from the air outlet 21H is guided out through the heat dissipation channels 11B, simultaneously carrying away heat from the disc motor 11. The disc motor 11 not only guides airflow to improve heat dissipation but also increases the heat dissipation area of ​​the disc motor 11, thus further enhancing the heat dissipation effect.

[0036] Figure 6This is a schematic diagram of the internal structure of the disc motor 11. The disc motor 11 is similar in structure to a conventional electric motor, including a relatively fixed stator 13 and a relatively movable rotor 14. The rotor 14's shaft is arranged along the central shaft of the air-cooled island permanent magnet synchronous motor. The disc motor 11 is a permanent magnet synchronous motor with disc-shaped axial magnetic flux; therefore, its rotor 14 has a disc-shaped rotor yoke 141 perpendicular to the shaft 12. Magnets 142 are arranged in a ring on both ends of the rotor yoke 141, with the outer magnetic poles of the magnets 142 on each end face of the rotor yoke 141 opposite. Corresponding to the magnets 142 arranged on both ends of the rotor yoke 141, coil windings 132 are arranged on the motor end faces 131 of the motor body 1 on both sides of the rotor yoke 141. The coil windings 132 are wound on a winding core 133 and are evenly arranged along the ring-shaped area of ​​the aligning magnets 142 on the motor end face 131. After being energized, an alternating current is passed through the coil inside the magnet 142 to form a rotating magnetic field that drives the rotor 14 to rotate synchronously with the magnetic field. By changing the frequency of the current in the coil winding 132 through the controller, the rotation period of the magnetic field can be changed accordingly, thereby changing the synchronous speed of the rotor 14.

[0037] like Figure 7 As shown, a magnet cover 143 is also provided on the rotor yoke 141. As illustrated, to reliably fix the alternating magnets 142 on the rotor yoke 141 and to withstand the alternating stress during operation, the magnet cover 143 is also provided with uniformly spaced magnet slots 431 along the circumference to accommodate the magnets 142. The magnets 142 are placed or fixed in the magnet slots 431 of the magnet cover 143. The magnet cover 143 is fastened onto the rotor yoke 141 and fixed, thus reliably fixing the magnets 142 between the rotor yoke 141 and the magnet cover 143. To reduce the air gap distance between the magnets 142 and the coil winding 132, the bottom surface of the magnet cover 143 needs to be relatively thin to ensure a high axial magnetic flux density in the air gap. Typically, the thickness of the bottom surface of the magnet cover 143 is less than 2 mm. Besides reliably fixing the magnets 142, the magnet cover 143 also assists in the stable operation of the rotor 14. In reality, the radial dimension of rotor 14 is approximately 1000-2000 mm. Within this dimension, even slight tilting or vibration of the rotor yoke 141 will result in noticeable up-and-down fluctuations on the rotor yoke 141. To increase the torque of rotor 14, the air gap between rotor 14 and stator 13 is kept small to ensure sufficient magnetic flux density. Typically, the air gap density between rotor 14 and disc motor 11 is less than 3 mm. With such a small air gap, without the further protection of the magnet cover 143, even slight vibrations of rotor 14 could cause the rotor yoke 141 or magnet 142 to contact or collide with rotor 14, potentially leading to unstable rotor operation and even breakage of magnet 142.

[0038] The disc motors 11 are coaxially stacked, sharing a common shaft 12 that extends to the outside of the motor body 1 to drive components such as blades. However, considering the relatively large rotor radius of the disc motors 11, typically between 500-1000mm, coaxial arrangement with multiple rotors 14 fixed on the shaft 12 places higher demands on the installation accuracy of the rotors 14. The axial fluctuation of all rotors 14 must be less than ±2.5mm when the shaft 12 rotates, meaning the axial fluctuation must be less than the single-sided air gap. This presents significant challenges to the assembly of the rotors 14. Even if the rotors 14 achieve the aforementioned installation accuracy, the distance between the rotating supports at both ends of the shaft 12 after stacking multiple disc motors 11 will cause slight misalignment of the disc motors 11 during rotation due to installation deviations on both ends of the motor body 1. This coaxiality deviation, due to the increased radial dimension of the rotors 14, will prevent the axial deviation of the rotors 14 from being controlled within the aforementioned range, thus posing a potential risk of friction and collision between the rotors 14 and the stator 13. Therefore, the permanent magnet synchronous motor in this air-cooled island preferably connects the rotating shafts of the disc motors 11 using a flexible transmission method. This flexible transmission method allows for radial positional deviations between the shafts 12, with any axial deviations absorbed by the flexible transmission mechanism, while simultaneously achieving torque transmission between the shafts 12. The flexible rotation method can be implemented using contact mechanical transmission or non-contact electromagnetic transmission; magnetic coupling transmission is preferred to reduce impact during operation and avoid lateral forces on the support devices at both ends of the shafts 12 during transmission. In particular, it enables zero-phase-difference transmission between the disc motors 11. Figure 8 An embodiment of magnetic coupling transmission is provided. A magnetic coupling disk 121 perpendicular to the rotating shaft 12 is provided at one end of the rotating shaft 12. Magnets are arranged in a ring on one side of the outer end face of the magnetic coupling disk 121, and the magnetic poles of adjacent magnets facing the outer side of the end face of the magnetic coupling disk 121 are opposite. The rotating shafts 12 of the stacked disc motors 11 are basically collinear, and the magnetic coupling disks 121 at the ends of the two rotating shafts 12 are directly opposite each other. Torque output is achieved through the magnetic interaction between the magnetic coupling disks 121. Since there is no mechanical connection between the two magnetic coupling disks 121, even if there is a slight deviation between the rotating shafts 12 of the two disc motors 11, it will not affect the transmission between the rotating shafts 12, and no internal stress will be generated in the rotating shafts 12. Optionally, an isolation plate fixed to the housing of the disc motor 11 can be provided in the air gap between the magnetic coupling disks 121 to further avoid direct contact between the magnetic coupling disks 121.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An air-cooled island permanent magnet synchronous motor, characterized in that, include: The motor body (1) includes several groups of disc motors (11) stacked along the same axis, with a certain distance between the disc motors (11) to form a heat dissipation gap; the heat dissipation system (2) includes an air supply device (21) and an air supply duct (22), the air supply device (21) is used to supply air into the air supply duct (22), the air supply duct (22) extends into the heat dissipation gap between the disc motors (11) and to both ends of the motor body (1), the airflow is discharged from the air supply duct (22) and then passes through the end face of the disc motor (11) to dissipate heat from the disc motor (11); The air supply duct (22) includes a cooling air duct (221), which is disposed in the heat dissipation gap between the disc motors (11) and at both ends of the motor body (1). An air outlet channel is formed between the outer surface of the cooling air duct (221) and the end face of the disc motor (11). The cooling duct (221) is an annular channel. Air outlets (21H) are provided on the end face (21A) of the cooling duct (221) close to the end face of the disc motor (11) and on the two opposite end faces (21A) of the cooling duct (221) located in the heat dissipation gap. Alternatively, air outlets (21H) are provided on the inner vertical surface (21B) of the cooling duct (221) connecting the inner side of the two opposite end faces (21A). The air outlets (21H) are used to discharge airflow.

2. The air-cooled island permanent magnet synchronous motor according to claim 1, wherein The air supply duct (22) also includes a main air duct (222), which connects the air supply device (21) and multiple cooling air ducts (221). The main air duct (222) is used to transport the airflow provided by the air supply device (21) to multiple sets of cooling air ducts (221).

3. The air-cooled island permanent magnet synchronous motor as claimed in claim 2, wherein The main air duct (222) is evenly arranged in multiple sets along the circumference of the disc motor (11), and the cooling air duct (221) is arranged in multiple sets from top to bottom. The multiple sets of cooling air ducts (221) are connected to the main air duct (222) in sequence, and the flow channel cross section of the main air duct (222) decreases in sequence as the cooling air duct (221) is connected.

4. The air-cooled island permanent magnet synchronous motor as claimed in claim 3, wherein The heat dissipation system (2) further includes a secondary air duct (223), which connects the cooling air duct (221) and the main air duct (222). The area of ​​the reduced flow channel cross-section of the main air duct (222) is equal to the flow channel cross-section of the secondary air duct (223) currently connected to the cooling air duct (221).

5. The air-cooled island permanent magnet synchronous motor according to claim 1, wherein The disc motor (11) has heat dissipation fins (11A) arranged circumferentially on the motor end face, and a heat dissipation channel (11B) is formed between adjacent heat dissipation fins (11A) for airflow.

6. The air-cooled island permanent magnet synchronous motor according to claim 1, wherein The disc motor (11) includes a stator (13) that is fixed relative to each other and a rotor (14) that is movable relative to each other. The shaft (12) of the rotor (14) is arranged along the shaft. The rotor (14) has a rotor yoke (141) perpendicular to the shaft (12). Magnets (142) are arranged in a ring on both ends of the rotor yoke (141). The magnetic poles of the magnets (142) arranged on each end of the rotor yoke (141) are opposite. The stator (13) has coil windings (132) evenly arranged in the annular area of ​​the magnets (142) outside the two ends of the rotor yoke (141).

7. The air-cooled island permanent magnet synchronous motor as claimed in claim 6, wherein The rotor yoke (141) is also provided with a magnet cover (143). The magnet cover (143) has a magnet groove (431) evenly opened in the circumferential direction for accommodating the magnet (142). The magnet (142) is fixed in the magnet groove (431) of the magnet cover (143). The magnet cover (143) is fastened to the rotor yoke (141) for fixation.

8. The air-cooled island permanent magnet synchronous motor as claimed in claim 6, wherein One end of the rotating shaft (12) is provided with a magnetic coupling disk (121) perpendicular to the rotating shaft (12). Magnets are arranged in a ring on one side of the outer end face of the magnetic coupling disk (121). The magnetic poles of adjacent magnets facing the outer side of the end face of the magnetic coupling disk (121) are different. The rotating shafts (12) between the stacked disc motors (11) are basically collinear, and the magnetic coupling disks (121) at the ends of the two rotating shafts (12) are facing each other closely.

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