Enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure

Abstract

An enhanced heat dissipation, low-loss, high-speed permanent magnet motor rotor structure comprises a solid shaft body, permanent magnets, and a carbon fiber protective sleeve. The solid shaft has spaced-apart rotor cooling rings and rotor dynamic balancing rings; the permanent magnets are mounted on the solid shaft body; the carbon fiber protective sleeve is assembled using a high-tension winding method; the permanent magnets have an unequal thickness structure, with their thickness distributed sinusoidally, and their outer surface is circular. In the rotor structure, the rotor cooling rings and rotor dynamic balancing rings are in direct contact with the cooling fluid in the air gap and the unequal-thickness permanent magnets, enabling the heat from the permanent magnets to be conducted to the cooling fluid through heat conduction and convection. Furthermore, the unequal-thickness permanent magnets improve the sinusoidal magnetic flux density of the air gap, effectively suppressing rotor eddy current losses. The combination of rotor loss suppression measures and high-efficiency rotor cooling technology achieves efficient thermal management of the high-speed permanent magnet motor rotor from both loss suppression and cooling perspectives.

Description

Technical Field

[0001] This invention relates to the field of high-speed permanent magnet motors, and in particular to a rotor structure for a high-speed permanent magnet motor with enhanced heat dissipation and low loss. Background Technology

[0002] High-speed permanent magnet motors are widely used in traditional industries and emerging green propulsion fields. As the core component of a high-speed permanent magnet motor, the rotor faces the risk of demagnetization of the permanent magnets and rotor damage due to high temperatures. Reasonable and effective rotor loss suppression measures and cooling technologies are crucial to ensuring the operational reliability of high-speed permanent magnet motors.

[0003] Carbon fiber sheaths are becoming a trend in high-speed permanent magnet motors due to their ability to provide greater preload to the rotor. However, carbon fiber sheaths have extremely low thermal conductivity, making it difficult for the heat from the permanent magnets to be carried away by the cooling fluid in the air gap when the cooling fluid flows through the sheath, resulting in low heat dissipation efficiency. One solution is to open axial flow channels in the rotor core, but this increases the difficulty of rotor manufacturing. On the other hand, Halbach permanent magnet arrays have gained some attention to improve the sinusoidal magnetic flux density in the air gap, but this leads to difficulties in permanent magnet mounting; while sinusoidally clipped parallel magnetized permanent magnets are relatively easy to assemble, their non-circular outer surface makes carbon fiber sheaths unsuitable. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology, such as the low heat dissipation efficiency of the carbon fiber sheath on the permanent magnet and the inability to effectively improve the sinusoidal magnetic flux density of the air gap, and to provide a rotor structure for a high-speed permanent magnet motor with enhanced heat dissipation and low loss.

[0005] The technical solution adopted by the present invention to solve its technical problem is an enhanced heat dissipation type low loss high speed permanent magnet motor rotor structure, including a solid rotating shaft body, a permanent magnet and a carbon fiber protective sleeve. The permanent magnet is a permanent magnet of unequal thickness and covers the outer peripheral surface of the solid rotating shaft body. The carbon fiber protective sleeve is sleeved on the outer peripheral surface of the permanent magnet of unequal thickness. The solid rotating shaft body has a rotor heat dissipation convex ring and a rotor dynamic balancing convex ring. A permanent magnet cavity is formed between the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring to accommodate permanent magnets of unequal thickness. The unequal thickness permanent magnets adopt a tile-shaped parallel magnetization method. Each pole permanent magnet is segmented along the circumference, and the thickness of adjacent permanent magnet segments in each pole permanent magnet is different to form unequal thickness permanent magnets. At the same time, the outer diameter of each permanent magnet segment is the same, but the inner diameter is different, so that the carbon fiber protective sleeve can be fitted on the outer surface of the unequal thickness permanent magnets.

[0006] Furthermore, two rotor heat dissipation convex rings and two rotor dynamic balancing convex rings are provided, and the two rotor heat dissipation convex rings are located between the two rotor dynamic balancing convex rings to form three permanent magnet cavities, and the three identical permanent magnets of unequal thickness are provided.

[0007] Furthermore, the rotor heat dissipation convex ring, the rotor dynamic balancing convex ring, and the carbon fiber protective sleeve have the same outer diameter.

[0008] Furthermore, the distance between the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring is the same as the distance between the two rotor heat dissipation convex rings.

[0009] Furthermore, the solid rotating shaft body is made of magnetic alloy steel with high thermal conductivity, and the rotor heat dissipation convex ring and rotor dynamic balance convex ring are cut out by integrated cutting.

[0010] Furthermore, the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring are in direct contact with the cooling fluid in the air gap. At the same time, the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring are in direct contact with the unequal thickness permanent magnets, so as to conduct the heat of the unequal thickness permanent magnets into the cooling fluid in the air gap through the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring to form a heat dissipation path.

[0011] Furthermore, the heat from the unequal-thickness permanent magnet is sequentially transferred from the unequal-thickness permanent magnet to the rotor heat dissipation cam ring and the rotor dynamic balancing cam ring, and then to the cooling fluid, thus forming a heat dissipation path.

[0012] Furthermore, in each permanent magnet, the thickness of multiple permanent magnet segments is distributed according to a sinusoidal law.

[0013] Furthermore, the central angle of each segment of the permanent magnet is the same.

[0014] Furthermore, the outer surface of the solid rotating shaft body is aligned with the bottom surface of the unequal-thickness permanent magnet, and the unequal-thickness permanent magnet is attached to the permanent magnet cavity.

[0015] In summary, the present invention has the following beneficial technical effects: This invention discloses an enhanced heat dissipation, low-loss, high-speed permanent magnet motor rotor structure, achieving efficient thermal management of the high-speed permanent magnet motor rotor from two aspects: rotor loss suppression and efficient rotor cooling. The unequal thickness permanent magnet structure reduces rotor eddy current losses, while the rotor heat sink improves the heat dissipation efficiency of the permanent magnets. On one hand, rotor heat dissipation rings and rotor dynamic balance rings are formed on the solid shaft body through cutting, efficiently dissipating heat from the permanent magnets encased in a carbon fiber protective sleeve. The dissipated heat is carried away by the cooling fluid in the air gap between the rotor and stator through thermal convection, greatly improving the heat dissipation efficiency of the permanent magnets. On the other hand, the unequal thickness permanent magnet structure achieves sinusoidal magnetic flux density in the air gap under parallel magnetization, effectively reducing rotor eddy current losses. The rotor structure balances rotor loss suppression and efficient rotor cooling, achieving efficient thermal management of the high-speed permanent magnet motor rotor. Furthermore, the permanent magnet cavity on the shaft surface reduces the installation difficulty of the permanent magnets and the risk of sideslip. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of an embodiment of an enhanced heat dissipation type low loss high speed permanent magnet motor rotor structure according to the present invention; Figure 2 This is a schematic diagram of the heat dissipation path of the permanent magnet in an embodiment of the rotor structure of a low-loss, high-speed permanent magnet motor with enhanced heat dissipation according to the present invention. Figure 3 This is a simulation comparison diagram of the heat dissipation efficiency of an embodiment of the enhanced heat dissipation type low loss high speed permanent magnet motor rotor structure of the present invention; Figure 4 This is a schematic diagram of the formation of unequal-thickness permanent magnets in an embodiment of an enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to the present invention. Figure 5 This is a comparison diagram of the back EMF waveform of an embodiment of the enhanced heat dissipation type low loss high speed permanent magnet motor rotor structure of the present invention and the back EMF waveform of the conventional structure. Figure 6 This is a cross-sectional schematic diagram of an embodiment of an enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to the present invention. Figure 7 This is a schematic diagram of the solid shaft body structure of an embodiment of the rotor structure of a high-speed permanent magnet motor with enhanced heat dissipation and low loss according to the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Solid rotating shaft body; 101. First rotor heat dissipation convex ring; 102. Second rotor heat dissipation convex ring; 103. Permanent magnet cavity; 104. First rotor dynamic balancing convex ring; 105. Second rotor dynamic balancing convex ring; 2. Carbon fiber protective sleeve; 201. First carbon fiber sheath; 202. Second carbon fiber sheath; 203. Third carbon fiber sheath; 3. Permanent magnets of unequal thickness; 301. First permanent magnet; 302. Second permanent magnet; 303. Third permanent magnet; 4. Cooling fluid; 501. First heat dissipation path; 502. Second heat dissipation path. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0019] Reference Figure 1 The high-speed permanent magnet motor rotor of this embodiment includes a solid shaft body 1, a permanent magnet of unequal thickness 3 and a carbon fiber protective sleeve 2. The permanent magnet of unequal thickness 3 is mounted on the solid shaft body 1, while the carbon fiber protective sleeve 2 is sleeved on the outer surface of the permanent magnet of unequal thickness 3. In this embodiment, the pole arc coefficient of the ultra-high speed permanent magnet motor rotor is 1.

[0020] Reference Figure 1 and Figure 2 The solid shaft body 1 is made of magnetic alloy steel with high thermal conductivity. A rotor heat dissipation ring and a rotor dynamic balancing ring are formed on the outer circumferential surface of the solid shaft body 1 by machining. The outer diameters of the rotor heat dissipation ring and the rotor dynamic balancing ring are the same. A permanent magnet cavity 103 is formed in the space created by the machining on the solid shaft body 1. The rotor heat dissipation ring and the rotor dynamic balancing ring are located at both ends of the permanent magnet cavity 103. The permanent magnet cavity 103 is used to house permanent magnets 3 of unequal thickness. After the carbon fiber protective sleeve 2 is fitted onto the outer circumferential surface of the unequal thickness permanent magnets 3, the outer diameters of the rotor heat dissipation ring, the rotor dynamic balancing ring, and the carbon fiber protective sleeve 2 are the same, ensuring that the outermost layer of the solid shaft body 1 is a continuous surface.

[0021] Furthermore, the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring are both formed by machining, with two rotor heat dissipation convex rings located between the two rotor dynamic balancing convex rings. The two rotor heat dissipation convex rings are divided into a first rotor heat dissipation convex ring 101 and a second rotor heat dissipation convex ring 102, and the two rotor dynamic balancing convex rings are divided into a first rotor dynamic balancing convex ring 104 and a second rotor dynamic balancing convex ring 105. The interval between the two rotor heat dissipation convex rings is the same as the interval between the rotor heat dissipation convex rings and the rotor dynamic balancing convex rings, so that three permanent magnet cavities 103 are formed on the surface of the solid rotating shaft body 1, and correspondingly, three permanent magnets 3 of unequal thickness are provided. The three permanent magnets 3 of unequal thickness are divided into a first permanent magnet 301, a second permanent magnet 302 and a third permanent magnet 303 according to their positions on the solid rotating shaft body 1 from left to right. Correspondingly, the first permanent magnet 301 is fitted with a first carbon fiber sheath 201, the second permanent magnet 302 is fitted with a first carbon fiber sheath 202, and the third permanent magnet 303 is fitted with a third carbon fiber sheath 203.

[0022] The unequal-thickness permanent magnet 3 contacts the rotor heat dissipation ring or the rotor dynamic balancing ring for heat dissipation. Taking the heat dissipation of the first permanent magnet 301 as an example, the left side of the first permanent magnet 301 contacts the first rotor dynamic balancing ring 104, and the right side contacts the first rotor heat dissipation ring 101. The heat of the first permanent magnet 301 is conducted to the first rotor dynamic balancing ring 104 and the first rotor heat dissipation ring 101 through thermal conduction. The heat transferred to the first rotor dynamic balancing ring 104 and the first rotor heat dissipation ring 101 is carried away by the cooling fluid 4 in the air gap between the rotor and the stator through thermal convection, thus forming the first heat dissipation path 501. At the same time, because the alloy steel has a high thermal conductivity, it can conduct heat out of the first rotor dynamic balancing ring 104 and the first rotor heat dissipation ring 101. Compared with conducting heat out through the carbon fiber protective sleeve 2, the heat dissipation effect of the unequal-thickness permanent magnet 3 is improved. The heat dissipation method of the third permanent magnet is the same as that of the first permanent magnet 301. The second permanent magnet 302 is located between the first rotor heat dissipation ring 101 and the second rotor heat dissipation ring 102. The heat from the second permanent magnet 302 is conducted to the first rotor heat dissipation ring 101 and the second rotor heat dissipation ring 102 through thermal conduction, and then carried away by the cooling fluid 4 through thermal convection, thus forming the second heat dissipation path 502. With the three permanent magnets 3 of unequal thickness, and through the rotor heat dissipation ring and the rotor dynamic balancing ring, the heat dissipation efficiency of the rotor permanent magnet of the high-speed permanent magnet motor is greatly improved.

[0023] Reference Figure 3 The simulation results of the temperature field of the conventional rotor structure and the rotor structure proposed in this invention are presented in this embodiment under the same loss and cooling conditions. It can be seen that using the rotor structure proposed in this invention reduces the maximum rotor temperature by 32.87℃, which can effectively improve the rotor's heat dissipation capacity, and its heat dissipation efficiency is improved by at least 15%.

[0024] Furthermore, to suppress eddy current losses in the rotor, a permanent magnet structure with unequal thickness is employed, as shown in the schematic diagram below. Figure 4 As shown, in a conventional structure, the permanent magnets on the rotor are parallel magnetized tile-shaped, and the corresponding air gap magnetic flux density waveform is a flat-topped wave. To improve its sinusoidal nature, a sinusoidal permanent magnet structure with a thickness satisfying a sinusoidal relationship was obtained while keeping the volume of the permanent magnet constant. However, the outer surface of the sinusoidal permanent magnet is not circular, so a carbon fiber protective sleeve 2 cannot be used.

[0025] Therefore, the structure of the sinusoidal permanent magnet was redesigned. While its general shape remains similar to that of a sinusoidal permanent magnet, the outer circumference is circular to allow the use of a carbon fiber protective sleeve 2. Specifically, the sinusoidal permanent magnet is divided into multiple individual permanent magnets along the circumference. Using segments as units, the inner diameter of each segment is calculated while maintaining the total volume of each permanent magnet pole and the same outer diameter of each segment. This results in a tile-shaped permanent magnet. The magnetization direction within the permanent magnet is the same and parallel to the structure of unequal-thickness permanent magnets 3. The central angle of the unequal-thickness permanent magnets 3 is 90°. Four unequal-thickness permanent magnets 3 are placed inside the permanent magnet cavity 103 to surround the solid rotating shaft body 1. In this embodiment, each pole of unequal-thickness permanent magnet 3 is divided into 5 segments along the circumference, with each segment being 18°. Each segment is a separate unit, and the 5 segments are combined to form a pole of unequal-thickness permanent magnet 3. Furthermore, within this pole of unequal-thickness permanent magnet 3, the two segments at the very ends have the same thickness and are the thinnest, gradually increasing in thickness towards the center, with the thickest segment being in the middle. This achieves a sinusoidal distribution of the thickness of the multiple permanent magnet segments. It should be noted that this segmentation method is only one aspect of this embodiment. In other embodiments, the number of segments and whether each segment is equally divided are achieved using the same segmentation method, but the final segmentation result must have a circular outer surface and an overall shape approximating a sinusoidal permanent magnet, i.e., the thickest in the middle and the thinnest at both ends.

[0026] A comparison of the back electromotive force of a high-speed permanent magnet motor employing a unequal-thickness permanent magnet 3-structure with that of a conventional structure. Figure 5 As shown, the high-speed permanent magnet motor using unequal-thickness permanent magnets 3 with a sinusoidal thickness distribution exhibits extremely high back electromotive force sinusoidality. This also indicates that the sinusoidality of the air gap magnetic flux density is significantly improved, thereby effectively suppressing rotor eddy current losses.

[0027] Reference Figure 6 and Figure 7The outer circumferential surface of the solid rotating shaft body 1 corresponds to the structure of the unequal-thickness permanent magnet 3, meaning the permanent magnet cavity 103 also has an unequal-thickness structure. This allows the unequal-thickness permanent magnet 3 to correspond with the permanent magnet cavity 103 for installation. The unequal-thickness permanent magnet 3 is glued to the permanent magnet cavity 103, ensuring proper positioning during installation and preventing lateral slippage between the solid rotating shaft body 1 and the unequal-thickness permanent magnet 3 during high-speed rotation. When the outer surface of the unequal-thickness permanent magnet 3 is circular, the carbon fiber protective sleeve 2 is directly assembled onto the surface of the unequal-thickness permanent magnet 3 using a high-tension winding method.

[0028] The implementation principle of an enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to an embodiment of the present invention is as follows: The enhanced heat dissipation, low-loss, high-speed permanent magnet motor rotor structure utilizes a rotor heat dissipation ring and a rotor dynamic balancing ring that are in direct contact with the permanent magnets and cooling fluid 4 to efficiently dissipate heat from the unequal-thickness permanent magnets 3, significantly improving the heat dissipation efficiency of the permanent magnets. The unequal-thickness permanent magnet 3 structure increases the sinusoidal nature of the air gap magnetic field, effectively reducing rotor eddy current losses. The combination of rotor loss suppression measures and efficient rotor cooling technology achieves efficient thermal management of the high-speed permanent magnet motor rotor. Furthermore, the polygonal shaft structure reduces the assembly difficulty of the permanent magnets and the risk of sideslip.

[0029] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component. Therefore, all equivalent changes made to the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A rotor structure for a high-speed permanent magnet motor with enhanced heat dissipation and low loss, characterized in that, It includes a solid rotating shaft body (1), a permanent magnet and a carbon fiber protective sleeve (2). The permanent magnet is a permanent magnet of unequal thickness (3) and is wrapped around the outer circumference of the solid rotating shaft body (1). The carbon fiber protective sleeve (2) is fitted on the outer circumference of the permanent magnet of unequal thickness (3). The solid rotating shaft body (1) has a rotor heat dissipation convex ring and a rotor dynamic balancing convex ring. A permanent magnet cavity (103) is formed between the rotor heat dissipation convex ring and the rotor dynamic balancing convex ring for placing unequal thickness permanent magnets (3). The unequal thickness permanent magnets (3) adopt a tile-shaped parallel magnetization method. Each pole permanent magnet is segmented along the circumference direction. In each pole permanent magnet, the thickness of adjacent permanent magnet segments is different to form unequal thickness permanent magnets (3). At the same time, the outer diameter of each permanent magnet segment is the same, but the inner diameter is different, so that the carbon fiber protective sleeve (2) can be sleeved on the outer surface of the unequal thickness permanent magnets (3).

2. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 1, characterized in that, Two rotor heat dissipation convex rings and two rotor dynamic balancing convex rings are provided, and the two rotor heat dissipation convex rings are located between the two rotor dynamic balancing convex rings to form three permanent magnet cavities (103). Three unequal thickness permanent magnets (3) are provided.

3. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 1, characterized in that, The rotor heat dissipation ring, rotor dynamic balance ring, and carbon fiber protective sleeve (2) have the same outer diameter.

4. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 2, characterized in that, The spacing between the rotor heat dissipation cam and the rotor dynamic balancing cam is the same as the spacing between the two rotor heat dissipation cams.

5. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 1, characterized in that, The solid rotating shaft body (1) is made of magnetic alloy steel with high thermal conductivity, and the rotor heat dissipation convex ring and rotor dynamic balance convex ring are cut out by integrated cutting.

6. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 1, characterized in that, The rotor heat dissipation ring and the rotor dynamic balancing ring are in direct contact with the cooling fluid (4) in the air gap. At the same time, the rotor heat dissipation ring and the rotor dynamic balancing ring are in direct contact with the unequal thickness permanent magnet (3). The heat of the unequal thickness permanent magnet (3) is conducted through the rotor heat dissipation ring and the rotor dynamic balancing ring into the cooling fluid (4) in the air gap to form a heat dissipation path.

7. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 6, characterized in that, The heat from the unequal thickness permanent magnet (3) is transferred sequentially from the unequal thickness permanent magnet (3) to the rotor heat dissipation ring and the rotor dynamic balance ring, and then to the cooling fluid (4) to form a heat dissipation path.

8. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 1, characterized in that, In each permanent magnet, the thickness of multiple permanent magnet segments is distributed according to a sinusoidal law.

9. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 8, characterized in that, The central angle of each segment of the permanent magnet is the same.

10. The enhanced heat dissipation type low-loss high-speed permanent magnet motor rotor structure according to claim 1, characterized in that, The outer surface of the solid rotating shaft body (1) is aligned with the bottom surface of the unequal thickness permanent magnet (3), and the unequal thickness permanent magnet (3) is attached to the permanent magnet cavity (103).

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