A rotor for a high-speed permanent magnet motor

Abstract

A rotor for a high-speed permanent magnet motor includes a rotor assembly and a pair of support bearings. The rotor assembly comprises a permanent magnet sheath, surface-mounted permanent magnets, a rotor core, and a pair of rotor shaft segments. The rotor core, surface-mounted permanent magnets, and permanent magnet sheath are coaxially mounted along the radial direction of the rotor assembly. The paired rotor shaft segments are respectively located at both ends of the rotor assembly and are connected to the rotor core, surface-mounted permanent magnets, and permanent magnet sheath. The paired support bearings are located at both ends of the rotor assembly and are correspondingly connected to the paired rotor shaft segments. Cooling medium channels are provided in the rotor core. This rotor, through its segmented structure, cuts off the eddy current conduction path inside the permanent magnets in both the circumferential and axial directions, thereby reducing eddy current losses and decreasing rotor heat generation. Furthermore, it fully utilizes the space occupied by the inter-pole filler to set up cooling medium channels, further improving heat dissipation efficiency and simplifying the structure.

Description

Technical Field

[0001] This invention relates to the field of motor equipment cooling technology, and more specifically, to a rotor for a high-speed permanent magnet motor. Background Technology

[0002] Compared to built-in permanent magnet rotors, the stronger air gap magnetic field, higher structural strength, and simpler topology are the main reasons why surface-mount permanent magnet rotors are widely used in high-speed motors. In low-power applications, the sheath of surface-mount permanent magnet rotors is mostly made of high-strength alloy materials. However, the complex air gap composite magnetic field will generate eddy current losses within the alloy sheath, leading to high rotor heat generation, and in severe cases, irreversible demagnetization of the permanent magnet. In high-speed, high-power applications, carbon fiber sheaths, with their high strength and low conductivity, are often used to improve the protection of the permanent magnet while reducing internal AC losses. However, carbon fiber sheaths are poor thermal conductors, and high-speed wind friction losses will cause heat to accumulate inside the rotor. Furthermore, the high-frequency components of the current time harmonics will generate severe eddy current losses within the permanent magnet, further exacerbating rotor heat generation and reducing the operational reliability of the permanent magnet.

[0003] To reduce the risk of high-temperature demagnetization of permanent magnets, two main measures are considered: suppressing eddy current losses in the permanent magnets and improving rotor heat dissipation efficiency. Regarding eddy current loss suppression, increasing the number of segments in the permanent magnet along the eddy current conduction direction can cut off the eddy current conduction path inside the permanent magnet, thereby weakening eddy current losses and reducing rotor heat generation. However, excessively increasing the number of permanent magnet segments will additionally increase the complexity of the rotor assembly, and the degree of eddy current loss suppression is limited. Furthermore, it cannot reduce the heat generated by high-speed wind friction losses, limiting the application potential of this method. Regarding improving rotor heat dissipation efficiency, existing methods mostly employ forced air cooling or liquid cooling to suppress temperature rise at high speeds. Forced air cooling requires simple auxiliary cooling equipment and is highly feasible. However, since the permanent magnets are encased inside the rotor, forced air cooling can only dissipate heat from the surface of the casing caused by wind friction losses, making it difficult to address the heat generated by eddy current losses inside the permanent magnets, resulting in limited cooling effectiveness. Compared to forced air cooling, liquid cooling, where the cooling fluid is in direct contact with the rotor, has a higher specific heat than cooling gas, enabling efficient heat dissipation. For example, patent (publication number: CN118300314A) discloses a liquid cooling topology for surface-mounted permanent magnet rotors, achieving efficient rotor heat dissipation. However, this topology requires additional cooling channels and guide plates, increasing the structural complexity of the high-speed permanent magnet rotor assembly and raising the risk of malfunctions during operation. Summary of the Invention

[0004] This invention provides a rotor for a high-speed permanent magnet motor, which utilizes the space between the permanent magnet pole fillers as a cooling channel for the rotor core, simplifying the existing rotor heat dissipation structure. While maintaining the rotor's structural shape, the rotor's weight is reduced, and the heat dissipation effect of the cooling medium on the rotor is improved.

[0005] The technical solution adopted by the present invention to solve its technical problem is a rotor for a high-speed permanent magnet motor, wherein the rotor for a high-speed permanent magnet motor includes: a rotor assembly and a pair of support bearings;

[0006] The rotor assembly includes a permanent magnet sheath, a surface-mounted permanent magnet, a rotor core, and a pair of rotor shaft segments. The rotor core, the surface-mounted permanent magnet, and the permanent magnet sheath are coaxially sleeved one after another along the radial direction of the rotor assembly. The pair of rotor shaft segments are respectively located at both ends of the rotor assembly and are connected to the rotor core, the surface-mounted permanent magnet, and the permanent magnet sheath. The pair of support bearings are respectively located at both ends of the rotor assembly and are connected to the pair of rotor shaft segments one by one.

[0007] Preferably, the rotor core includes a first rotor core and a second rotor core, the first rotor core is sleeved outside the second rotor core, and the first rotor core and the second rotor core are connected.

[0008] Preferably, the first rotor core includes a first core body and a pair of core teeth;

[0009] The paired iron core teeth are evenly distributed circumferentially on the first iron core body. The surface-mount permanent magnets are evenly attached between adjacent iron core teeth so that a counter pole region is formed between adjacent iron core teeth. The iron core teeth are provided with tooth flow channels that extend through the axial direction of the first rotor iron core. The axial end face of the first iron core body is provided with iron core vent holes that are evenly distributed circumferentially. The iron core vent holes and the tooth flow channels are circumferentially offset.

[0010] Preferably, the second rotor core includes a core connector that mates with the core teeth and a second core body;

[0011] The core connectors are evenly distributed at the ends of the second core body and correspond to the core teeth. Each core connector has a core flow channel that communicates with the tooth flow channel for the flow of cooling medium. The first core body and the second core body are interference-fitted, and the first core body and the second core body are respectively connected to the rotor shaft segment.

[0012] Preferably, each rotor shaft section is provided with a shaft section vent hole, and the shaft section vent hole matches the iron core vent hole so that the rotor iron core is connected to the outside world to balance the air pressure.

[0013] Preferably, the rotor shaft section is further provided with a shaft section groove, and both the first iron core body and the second iron core body are provided with slots that cooperate with the shaft section groove, and the shaft section groove is engaged with the slot.

[0014] Preferably, each of the paired rotor shaft segments is provided with a shaft segment through hole, which is connected to the tooth flow channel and the iron core flow channel respectively. The shaft segment through hole connected to the tooth flow channel is used for the inflow of cooling medium, and the shaft segment through hole connected to the iron core flow channel is used for the outflow of cooling medium.

[0015] Preferably, the surface-mounted permanent magnets are arranged in segments along the axial direction of the rotor core, and the pole arc coefficient of the surface-mounted permanent magnets is less than 1.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention provides a high-speed permanent magnet motor rotor that utilizes the space between the permanent magnet pole fillers as a cooling channel for the rotor core. This simplifies existing rotor heat dissipation structures, reduces rotor weight while maintaining the rotor's structural shape, and improves the cooling effect of the cooling medium. It fully utilizes the space between the magnetic poles to create axial cooling channels, allowing the cooling fluid to be as close as possible to the permanent magnets, resulting in superior heat dissipation. Furthermore, it avoids the need for additional auxiliary structures for cooling channels, achieving structural simplification, integration, and high-efficiency heat dissipation.

[0018] Furthermore, the segmented structure of the rotor in the axial direction effectively reduces eddy current losses in the permanent magnets, further lowering the rotor's heat generation. Additionally, the segmented placement of the surface-mounted permanent magnets around the core ensures that the rotor for this high-speed permanent magnet motor also has a segmented structure in the circumferential direction, further cutting off the eddy current conduction path inside the permanent magnets in the circumferential direction, thus weakening eddy current losses and reducing rotor heat generation. This high-speed permanent magnet motor rotor, through its segmented structure in both the circumferential and axial directions, effectively cuts off the eddy current conduction path inside the permanent magnets, weakening eddy current losses and reducing rotor heat generation, while avoiding the increased complexity of the rotor assembly caused by excessively increasing the number of permanent magnet segments in a single direction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the rotor for the high-speed permanent magnet motor of the present invention;

[0020] Figure 2 This is a schematic diagram of the rotor assembly for the high-speed permanent magnet motor of the present invention;

[0021] Figure 3 This is a radial structural schematic diagram of the rotor assembly of the high-speed permanent magnet motor rotor of the present invention;

[0022] Figure 4 This is a schematic cross-sectional view of the rotor assembly of the high-speed permanent magnet motor of the present invention along the radial direction BB.

[0023] Figure 5 This is a schematic diagram of the structure of the first rotor core of the rotor used in the high-speed permanent magnet motor of the present invention.

[0024] Figure 6 This is a schematic diagram of the structure of the second rotor core of the rotor used in the high-speed permanent magnet motor of the present invention;

[0025] Figure 7 This is a schematic diagram of the rotor core flow channel of the rotor for the high-speed permanent magnet motor of the present invention;

[0026] Figure 8 This is a schematic diagram of the assembly of the first rotor core and the second rotor core of the rotor for the high-speed permanent magnet motor of the present invention.

[0027] Figure 9 This is a schematic diagram of the rotor shaft section of the rotor used in the high-speed permanent magnet motor of the present invention;

[0028] Figure 10 This is a schematic cross-sectional view of the rotor shaft section of the rotor for the high-speed permanent magnet motor of the present invention.

[0029] Figure 11 This is a schematic diagram of the axial cross-sectional structure of the three-dimensional assembly of the rotor for the high-speed permanent magnet motor of the present invention.

[0030] Explanation of reference numerals in the attached drawings: 1. Rotor assembly; 1-1. Rotor shaft section; 1-1-1. Shaft section vent hole; 1-1-2. Shaft section groove; 1-1-3. Shaft section through hole;

[0031] 2. Permanent magnet sheath; 3. Support bearing; 3-1. First support bearing; 3-2. Second support bearing;

[0032] 4. Surface-mounted permanent magnet; 4-1. First magnetic pole; 4-2. Second magnetic pole; 4-3. Third magnetic pole; 4-4. Fourth magnetic pole;

[0033] 5. Rotor core; 5-1. First rotor core; 5-1-1. Core vent hole; 5-1-2. Toothed flow channel; 5-1-3. Core teeth; 5-2. Second rotor core; 5-2-1. Core flow channel; 5-2-2. Core connector. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Numerous specific details are set forth in the following description to enable those skilled in the art to fully understand the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] In the description of the embodiments of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0038] like Figure 1 and Figure 2 As shown, a rotor for a high-speed permanent magnet motor includes: a rotor assembly 1 and a pair of support bearings 3; the rotor assembly 1 includes a permanent magnet sleeve 2, a surface-mount permanent magnet 4, a rotor core 5, and a pair of rotor shaft segments 1-1. The rotor core 5, the surface-mount permanent magnet 4, and the permanent magnet sleeve 2 are coaxially sleeved one after another along the radial direction of the rotor assembly 1. The pair of rotor shaft segments 1-1 are respectively located at both ends of the rotor assembly 1 and are connected to the rotor core 5, the surface-mount permanent magnet 4, and the permanent magnet sleeve 2. The pair of support bearings 3 are respectively located at both ends of the rotor assembly 1 and are connected to the pair of rotor shaft segments 1-1 one by one. A cooling medium flow channel is provided in the rotor core 5.

[0039] In this embodiment, the rotor of the high-speed permanent magnet motor is designed with a segmented structure in the axial direction, which effectively reduces the eddy current loss of the permanent magnet and further reduces the heat generation of the rotor. Furthermore, the surface-mounted permanent magnets make the rotor of the high-speed permanent magnet motor also segmented in the circumferential direction, thereby further cutting off the eddy current conduction path inside the permanent magnet in the circumferential direction, weakening eddy current losses, and reducing rotor heat generation. The segmented structure in both the circumferential and axial directions of the high-speed permanent magnet motor rotor effectively cuts off the eddy current conduction path inside the permanent magnet, weakening eddy current losses and reducing rotor heat generation, while avoiding the increased complexity of the rotor assembly 1 caused by excessively increasing the number of permanent magnet segments in a single direction. Furthermore, the high-speed permanent magnet motor rotor utilizes the space between the permanent magnet pole fillers in the rotor core 5 to set up cooling medium channels, further improving the rotor's heat dissipation efficiency and simplifying the rotor structure, avoiding further structural complexity.

[0040] Furthermore, there are no restrictions on the rotor sheath material in this high-speed permanent magnet motor rotor; it can be a lightweight, high-strength, low-conductivity carbon fiber sheath or an alloy metal sheath, depending on the application scenario. The rotor assembly 1 is a hollow structure to achieve lightweighting. The paired support bearings 3 include a first support bearing 3-1 and a second support bearing 3-2, which are respectively disposed on the left and right sides of the rotor assembly 1 to serve as rotational supports for the rotor.

[0041] like Figures 3-8 As shown, the rotor core 5 includes a first rotor core 5-1 and a second rotor core 5-2. The first rotor core 5-1 is sleeved on the outside of the second rotor core 5-2, and the first rotor core 5-1 and the second rotor core 5-2 are connected.

[0042] The first rotor core 5-1 includes a first core body and a pair of core teeth 5-1-3. The pair of core teeth 5-1-3 are evenly distributed circumferentially on the first core body. The surface-mount permanent magnet 4 is evenly attached between adjacent core teeth 5-1-3 so that a pole-opposite region is formed between adjacent core teeth 5-1-3. A tooth flow channel 5-1-2 is opened on the core teeth 5-1-3 and extends through the axial direction of the first rotor core 5-1. A circumferentially distributed core vent hole 5-1-1 is opened on the axial end face of the first core body. The core vent hole 5-1-1 and the tooth flow channel 5-1-2 are staggered circumferentially.

[0043] The second rotor core 5-2 includes a core connector 5-2-2 that mates with the core teeth 5-1-3 and a second core body. The core connectors 5-2-2 are evenly distributed at the ends of the second core body and correspond to the core teeth 5-1-3. Each core connector 5-2-2 has a core flow channel 5-2-1 that communicates with the tooth flow channel 5-1-2 to allow the flow of cooling medium. The first core body and the second core body are interference-fitted, and the first core body and the second core body are respectively connected to the rotor shaft section 1-1.

[0044] In this embodiment, the rotor core 5 of the high-speed permanent magnet motor rotor fully utilizes the inter-pole gap of the permanent magnets. The space traditionally occupied by the inter-pole filler is fully utilized through the arrangement of the core teeth 5-1-3, serving as a cooling channel for the rotor's cooling medium. Placing the cooling channel within the space occupied by the filler does not increase the rotor's structural complexity and eliminates the need for additional auxiliary structures to protect the rotor. Furthermore, it does not significantly affect the rotor's mechanical or electromagnetic properties. This allows the high-speed permanent magnet motor rotor to achieve efficient rotor cooling while reducing cooling complexity and cost. The radial cross-sectional shape of the toothed flow channel 5-1-2 is variable and can be rectangular, circular, or other shapes.

[0045] Furthermore, the segmented design of the rotor core in this invention is based on practical manufacturing feasibility, rather than being segmented for the sake of segmentation. If the rotor core can be manufactured in a single process, then adopting a monolithic structure for the rotor core would be more effective.

[0046] In a preferred embodiment, each rotor shaft segment 1-1 is provided with a shaft segment vent hole 1-1-1, which matches the core vent hole 5-1-1 to connect the rotor core 5 with the outside environment and balance the air pressure. In this embodiment, the shaft segment vent holes 1-1-1 and the core vent holes 5-1-1 have the same number in the circumferential direction, and the radial radius of the holes is the same as the circumferential angle. This is used to connect the inside of the rotor core 5 cavity with the external atmosphere, preventing sudden pressure changes inside the rotor core 5, which would affect the high-speed operation stability of the rotor.

[0047] See Figures 9-10 The rotor shaft section 1-1 is also provided with a shaft section groove 1-1-2. Both the first iron core body and the second iron core body are provided with slots that mate with the shaft section groove 1-1-2, and the shaft section groove 1-1-2 is engaged with the slot. Each pair of rotor shaft sections 1-1 is provided with a shaft section through hole 1-1-3, which communicates with the tooth flow channel 5-1-2 and the iron core flow channel 5-2-1, respectively. The shaft section through hole 1-1-3 communicating with the tooth flow channel 5-1-2 is used for the inflow of cooling medium, and the shaft section through hole 1-1-3 communicating with the iron core flow channel 5-2-1 is used for the outflow of cooling medium.

[0048] In this embodiment, the engaging connection between the shaft segment groove 1-1-2 and the groove opening effectively constrains the displacement of the rotor shaft segment 1-1, preventing the rotor shaft segment 1-1 from moving during use and effectively preventing rotor torque transmission failure. The shaft segment through hole 1-1-3 allows for the inflow and outflow of cooling medium, enabling rapid cooling of the rotor of this high-speed permanent magnet motor.

[0049] In a preferred embodiment, the surface-mount permanent magnets 4 are arranged in segments along the axial direction of the rotor core 5, and the pole arc coefficient of the surface-mount permanent magnets 4 is less than 1. To reserve axial cooling space between the poles of the permanent magnets, the pole arc coefficient of the permanent magnets must be less than 1. Furthermore, the magnetization method of a single pole of the permanent magnet can be arbitrarily selected, such as radial magnetization, parallel magnetization, or Halbach magnetization. In one embodiment, such as... Figure 4 As shown, taking a permanent magnet with 2 pole pairs as an example, the surface-mounted permanent magnet 4 is divided into four parts on the circumference, with each part forming a pole, such as 4-1 first magnetic pole, 4-2 second magnetic pole, 4-3 third magnetic pole and 4-4 fourth magnetic pole. The above four poles together form the 2-pole topology of the rotor assembly 1. There is an iron core tooth 5-1-3 between adjacent magnetic poles so that the cooling medium can quickly dissipate the heat during the operation of the magnetic pole.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A rotor for a high-speed permanent magnet motor, characterized in that, The rotor for the high-speed permanent magnet motor includes: a rotor assembly and a pair of support bearings; The rotor assembly includes a permanent magnet sheath, a surface-mount permanent magnet, a rotor core, and a pair of rotor shaft segments. The rotor core, the surface-mount permanent magnet, and the permanent magnet sheath are coaxially sleeved one after another along the radial direction of the rotor assembly. The pair of rotor shaft segments are respectively located at both ends of the rotor assembly and are connected to the rotor core, the surface-mount permanent magnet, and the permanent magnet sheath. The pair of support bearings are respectively located at both ends of the rotor assembly and are connected to the pair of rotor shaft segments one by one. The rotor core is provided with a cooling medium flow channel. The rotor core includes a first rotor core and a second rotor core. The first rotor core is sleeved on the outside of the second rotor core and the first rotor core and the second rotor core are connected. The first rotor core includes a first core body and a pair of core teeth. The pair of core teeth are evenly distributed circumferentially on the first core body. The surface-mount permanent magnet is evenly attached between adjacent core teeth so that a counter pole region is formed between adjacent core teeth. The core teeth are provided with tooth flow channels that extend along the axial direction of the first rotor core. The axial end face of the first core body is provided with circumferentially distributed core vent holes. The core vent holes and the tooth flow channels are circumferentially offset. Each pair of rotor shaft segments is provided with shaft segment through holes. The second rotor core includes a core connector that mates with the core teeth. Each core connector is provided with a core flow channel that communicates with the tooth flow channel for the flow of cooling medium. The shaft segment through holes are respectively connected to the tooth flow channel and the core flow channel. The shaft segment through holes that communicate with the tooth flow channel are used for the inflow of cooling medium, and the shaft segment through holes that communicate with the core flow channel are used for the outflow of cooling medium.

2. The rotor for a high-speed permanent magnet motor according to claim 1, characterized in that, The second rotor core includes the core connector that mates with the core teeth and the second core body; The core connectors are evenly distributed at the ends of the second core body and correspond to the core teeth. Each core connector has a core flow channel that communicates with the tooth flow channel for the flow of cooling medium. The first core body and the second core body are interference-fitted, and the first core body and the second core body are respectively connected to the rotor shaft segment.

3. The rotor for a high-speed permanent magnet motor according to claim 1, characterized in that, Each rotor shaft section is provided with a shaft section vent hole, which matches the vent hole of the iron core so that the rotor iron core can be connected to the outside world to balance the air pressure.

4. The rotor for a high-speed permanent magnet motor according to claim 1, characterized in that, The rotor shaft section is also provided with a shaft section groove, and the first iron core body and the second iron core body are both provided with a slot that matches the shaft section groove, and the shaft section groove is engaged with the slot.

5. The rotor for a high-speed permanent magnet motor according to any one of claims 1-4, characterized in that, The surface-mounted permanent magnets are arranged in segments along the axial direction of the rotor core, and the pole arc coefficient of the surface-mounted permanent magnets is less than 1.

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