Surface-mounted high-speed permanent magnet motor rotor structure adopting composite permanent magnet

Abstract

The invention relates to the technical field of permanent magnet motors, and provides a surface-mounted high-speed permanent magnet motor rotor structure adopting a composite permanent magnet, which comprises a rotor sheath, a working magnet, an auxiliary magnet and a rotating shaft, eddy-current loss can be effectively inhibited by adopting the structure differentiation design of combining the carbon fiber sheath with the composite permanent magnet; the auxiliary magnet is made of a low-conductivity and low-remanence material, so that eddy current caused by a high-frequency alternating magnetic field can be reduced; a working magnet is made of a high-conductivity and high-remanence material, so that the main magnetic flux output of the motor is enhanced, and the power density is improved; meanwhile, the carbon fiber sheath has the characteristics of low conductivity and high strength, so that extra magnetic field interference generated by permanent magnet eddy current can be reduced, and the mechanical property of the rotor can be enhanced; through collaborative optimization of the composite magnet material and the sheath, the scheme realizes balance between eddy current loss suppression and magnetic performance improvement, and is suitable for application scenarios of high power density and high-speed operation.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet motors, and in particular to a surface-mounted high-speed permanent magnet motor rotor structure using composite permanent magnets. Background Art

[0002] High-speed permanent magnet motors have the advantages of high efficiency and high power density, and are widely used in modern industry, transportation and other fields. However, as the speed increases, permanent magnet motors will generate higher eddy current losses during operation, especially during high-frequency operation. Due to the large eddy current losses, the overall efficiency of the motor will be reduced. At the same time, due to the poor heat dissipation conditions of the rotor part, the local temperature of the permanent magnet will be too high, resulting in irreversible demagnetization.

[0003] To address this issue, various methods have been proposed in the prior art to reduce eddy current losses in permanent magnets, including optimizing the permanent magnet shape, optimizing the permanent magnet material, adding a copper shielding layer to the permanent magnet surface, and segmenting the permanent magnet. However, these methods have certain limitations in practical applications, such as high processing difficulty and limited reduction effects. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-speed permanent magnet motor rotor structure using a composite permanent magnet surface-mounted structure to solve the problem that during the high-frequency operation of the permanent magnet motor, the overall efficiency of the motor is reduced due to large eddy current losses.

[0005] To achieve the above-mentioned object, the present invention provides a rotor structure of a surface-mounted high-speed permanent magnet motor using a composite permanent magnet. The rotor structure comprises: a rotor sleeve, a working magnet, an auxiliary magnet, and a rotating shaft. The working magnet is arranged on the rotating shaft, and the rotor sleeve is sheathed on the outermost auxiliary magnet.

[0006] There are three types of rotor structures. The first structure adopts a double-layer permanent magnet. The rotor structure from the outer layer to the inner layer is a rotor sleeve, auxiliary magnets, working magnets and rotating shaft in sequence; the second structure adopts a composite alternating permanent magnet structure. The rotor structure from the outer layer to the inner layer is a rotor sleeve, auxiliary magnets, working magnets, auxiliary magnets, working magnets and rotating shaft in sequence; the third structure is based on the first structure, and the auxiliary magnets are axially segmented to set magnets with different material properties. The other structures are the same as the first structure.

[0007] By designing a rotor with two layers of permanent magnets made of different materials, or alternating between them, the eddy current losses generated by the motor during high-speed operation are effectively reduced. Composite magnets contain two types of magnets: working magnets and auxiliary magnets. This structure not only significantly reduces eddy current losses but also improves the motor's power density and operating efficiency.

[0008] Furthermore, in the three structures, the axial lengths of the rotor sleeve, the working magnet and the auxiliary magnet are the same, and two adjacent layers of the structure are connected together.

[0009] Furthermore, the third structure is based on the first structure, and the auxiliary magnet is axially segmented. The magnet is divided into segments, namely the auxiliary magnet, the working magnet and the auxiliary magnet, and the total axial length of the segmented magnet is the same as the length of the inner working magnet.

[0010] Furthermore, the conductivity of the auxiliary magnet is less than 10000 s / m , the conductivity of the working magnet is greater than 500000s / m.

[0011] Furthermore, the remanence of the working magnet is greater than 1.1T, and the remanence of the auxiliary magnet is in the range of 0.3T-0.7T.

[0012] Furthermore, the rotor sleeve is made of carbon fiber material; the auxiliary magnet is made of ferrite magnet or bonded NdFeB magnet; and the working magnet is made of sintered NdFeB magnet.

[0013] Furthermore, under the condition that the working magnet is a sintered NdFeB magnet, the relationship between the thickness of the working magnet, the thickness of the auxiliary magnet, and the remanence of the auxiliary magnet is:

[0014] y=9.3248+0.7302×B outer +2.4114×H outer +(-3.0476×H outer ×B outer )

[0015] Among them, B outer is the residual magnetism of the auxiliary magnet; H outer is the thickness of the auxiliary magnet.

[0016] Beneficial Effects: In high-speed radial permanent magnet motors, the use of a carbon fiber sheath combined with a differentiated composite permanent magnet structure can effectively suppress eddy current losses. The auxiliary magnets are made of low-conductivity, low-remanence materials to reduce eddy currents caused by high-frequency alternating magnetic fields. The working magnets are made of high-conductivity, high-remanence materials to enhance the motor's main magnetic flux output and improve power density. At the same time, the carbon fiber sheath has low conductivity and high strength, which not only reduces the additional magnetic field interference generated by the permanent magnet's eddy currents, but also enhances the rotor's mechanical properties. Through the coordinated optimization of the composite magnet material and the sheath, this solution achieves a balance between eddy current loss suppression and magnetic performance improvement, making it suitable for applications with high power density and high-speed operation.

[0017] Based on the implementation methods provided in the above aspects, this application can also be further combined to provide more implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a mechanical assembly diagram of a double-layer permanent magnet rotor structure according to an embodiment of the present invention;

[0020] Figure 2 This is a mechanical assembly diagram of an alternately arranged composite permanent magnet rotor structure according to an embodiment of the present invention;

[0021] Figure 3 This is a mechanical assembly diagram of a rotor structure that is axially divided into three sections and uses different magnetic materials according to an embodiment of the present invention;

[0022] Figure 4 The influence of outer permanent magnets of different materials and thicknesses on rotor eddy current losses;

[0023] Figure 5 The influence of outer permanent magnets of different materials and thicknesses on the consumption of inner permanent magnets;

[0024] Figure 6 Comparison of eddy current loss calculations for different rotor structures and single-layer jacket solutions.

[0025] Description of Figure Numbers:

[0026] 1. Rotor sleeve; 2. Auxiliary magnet; 3. Working magnet; 4. Rotating shaft. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0028] like Figures 1 to 3As shown, the present invention provides a high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount, the rotor structure includes: a rotor sleeve 1, a working magnet 3, an auxiliary magnet 2 and a rotating shaft 4; the working magnet 3 is arranged on the rotating shaft 4, and the rotor sleeve 1 is sleeved on the outermost auxiliary magnet 2; the rotor structure is provided with three structures, the first structure uses a double-layer permanent magnet, such as Figure 1 As shown, the rotor structure from the outer layer to the inner layer is the rotor sleeve 1, auxiliary magnet 2, working magnet 3 and shaft 4. Figure 1 As shown; the second structure adopts a composite alternating arrangement of permanent magnets, as shown Figure 2 As shown, the rotor structure from the outer layer to the inner layer is the rotor sleeve 1, the auxiliary magnet 2, the working magnet 3, the auxiliary magnet 2, the working magnet 3 and the shaft 4. Figure 2 The third structure is based on the first structure, the auxiliary magnet 2 is axially segmented to set the magnets of different material properties, the other structures are the same as the first structure, such as Figure 3 As shown; Figure 3 The working magnet 3 on the far left has the smallest inner diameter and is sleeved on the rotating shaft 4 ; the segmented auxiliary magnet 2 is sleeved on the working magnet 3 ; and the rotor sleeve 1 on the far right is sleeved on the segmented auxiliary magnet 2 .

[0029] Specifically, the working magnet 3 serves as the inner permanent magnet, and the working magnet 3 adopts high conductivity and high remanence material, which can provide a strong magnetic field to ensure that the motor has sufficient driving force when running at high speed; the neodymium iron boron permanent magnet is evenly distributed in the inner layer of the motor rotor to form a uniform inner magnetic field.

[0030] The auxiliary magnet 2 serves as the outer permanent magnet, and the auxiliary magnet 2 is made of a material with low electrical conductivity and relatively low remanence. Both the inner permanent magnet and the outer permanent magnet can provide magnetic fields. The outer permanent magnet forms an auxiliary magnetic field to further enhance the overall magnetic field strength of the motor and effectively reduce eddy current losses. In actual engineering applications, the selection of inner and outer permanent magnet materials is carried out in combination with material properties and engineering practice, and is not limited to the reference cases provided in this patent.

[0031] The rotor sheath 1 is made of carbon fiber material. Carbon fiber has good properties such as high strength and light weight, which helps to improve the mechanical strength of the motor. The carbon fiber sheath is wrapped around the outside of the outer permanent magnet, effectively ensuring the overall strength of the motor.

[0032] The rotating shaft 4 is made of high-strength alloy steel to ensure sufficient mechanical strength and rigidity when rotating at high speed; both ends of the rotating shaft 4 are fixed inside the stator through high-precision bearings to ensure that the rotor runs smoothly at high speed.

[0033] Optionally, in the three structures, the axial lengths of the rotor sleeve 1 , the working magnet 3 and the auxiliary magnet 2 are the same, and two adjacent layers of the structure are connected together.

[0034] Optionally, the third structure is based on the first structure, and the auxiliary magnet 2 is axially segmented. The magnet is divided into three sections, namely the auxiliary magnet 2, the working magnet 3 and the auxiliary magnet 2. The total axial length of the segmented magnets is the same as the length of the inner working magnet 3. Figure 3 shown.

[0035] Optionally, the conductivity of the auxiliary magnet 2 is less than 10000 s / m, the electrical conductivity of the working magnet 3 is greater than 500000 s / m.

[0036] Optionally, the remanence of the working magnet 3 is greater than 1.1T, and the remanence of the auxiliary magnet 2 is in the range of 0.3T-0.7T.

[0037] Optionally, the rotor sleeve 1 is made of carbon fiber material, the working magnet 3 is made of sintered NdFeB magnet; and the auxiliary magnet 2 is made of ferrite magnet and bonded NdFeB magnet.

[0038] Optionally, when the working magnet 3 is a sintered NdFeB magnet, the relationship between the thickness of the working magnet 3 and the thickness of the auxiliary magnet 2 and the remanence of the auxiliary magnet 2 is:

[0039] y=9.3248+0.7302×B outer +2.4114×H outer +(-3.0476×H outer ×B outer )

[0040] Among them, B outer is the residual magnetism of the auxiliary magnet 2; H outer is the thickness of the auxiliary magnet 2 .

[0041] The following describes the specific embodiments of the present application with reference to the accompanying drawings:

[0042] Taking a 100kW, 20,000rpm surface-mount permanent magnet synchronous motor as an example, finite element simulation experiments show that when auxiliary magnet 2 uses a ferrite magnet, the eddy current loss values ​​for different rotor structures and single-layer sheath solutions are as follows:

[0043] Table 1 shows the eddy current loss values ​​of different rotor structures and single-layer sheath solutions

[0044]

[0045] From the above table and attached Figure 6It can be seen that the rotor eddy current loss of the first structural composite magnet designed by the present invention is reduced by 31.1% compared with the single-layer carbon fiber scheme, and is reduced by 43.1% compared with the single-layer titanium alloy scheme; the rotor eddy current loss of the second structural composite magnet is reduced by 28.5% compared with the single-layer carbon fiber scheme, and is reduced by 41% compared with the single-layer titanium alloy scheme; the rotor eddy current loss of the third structural composite magnet is reduced by 24% compared with the single-layer carbon fiber scheme, and is reduced by 37.21% compared with the single-layer titanium alloy scheme; Obviously, the three composite magnet structures designed by the present invention have obvious effect of suppressing rotor eddy current loss.

[0046] At the same time, when the auxiliary magnets 2 of the three rotor structures are ferrite magnets and bonded NdFeB magnets, through finite element simulation experiments, as shown in FIG. Figure 4 and 5 As shown in the figure, the influence of different thicknesses of the auxiliary magnet 2 on the rotor eddy current loss and the consumption of the working magnet 3 is demonstrated. The ferrite scheme has a more obvious effect in suppressing the rotor eddy current loss. When the thickness of the ferrite magnet increases from 1 mm to 5 mm, the rotor eddy current loss decreases from 232.24 W to 187.09 W, a decrease of 19.44%. However, when the auxiliary magnet 2 adopts a ferrite magnet, the consumption of the working magnet 3 increases with the increase of thickness. When the auxiliary magnet 2 adopts bonded NdFeB, although the effect of suppressing eddy current loss is worse than that of the ferrite scheme, the consumption of the working magnet 3 remains basically unchanged. Moreover, the smaller the air gap, the more obvious the suppression effect of the bonded NdFeB scheme on the rotor eddy current loss will be compared with the single-layer carbon fiber scheme under the same conditions.

[0047] Fluent software was used to calculate the temperature field. The temperature rises of the working magnets of the single-layer titanium alloy sheath solution and the single-layer carbon fiber sheath solution with higher rotor eddy current loss were 134.21K and 141.71K, respectively. Among them, the rotor structure of the double-layer permanent magnet solution adopted in this patent has a temperature rise of 117.15K, which is 17.06K lower than that of the single-layer titanium alloy solution and 24.56K lower than that of the single-layer carbon fiber solution. The temperature rise calculation results show that the composite magnet solution provided by this patent can effectively reduce the temperature rise of the rotor part and reduce the irreversible demagnetization of the rotor permanent magnet due to high temperature.

[0048] Through reasonable design and material selection, this implementation scheme reduces eddy current losses while reducing the use of permanent magnet materials, thereby improving the efficiency and reliability of the surface-mounted high-speed permanent magnet motor and having broad application prospects.

Claims

1. A high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount type, characterized in that: The rotor structure comprises: a rotor sleeve (1), a working magnet (3), an auxiliary magnet (2) and a rotating shaft (4); the working magnet (3) is arranged on the rotating shaft (4), and the rotor sleeve (1) is sleeved on the outermost auxiliary magnet (2); The rotor structure is set to three types. The first structure adopts a double-layer permanent magnet, and the rotor structure is composed of a rotor sleeve (1), an auxiliary magnet (2), a working magnet (3) and a rotating shaft (4) from the outer layer to the inner layer. The second structure adopts a composite alternating arrangement permanent magnet structure, and the rotor structure is composed of a rotor sleeve (1), an auxiliary magnet (2), a working magnet (3), an auxiliary magnet (2), a working magnet (3) and a rotating shaft (4) from the outer layer to the inner layer. The third structure is based on the first structure, and the auxiliary magnet (2) is axially segmented to set magnets with different material properties. The other structures are the same as the first structure. The auxiliary magnet (2) and the working magnet (3) form a composite magnet.

2. The high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount type according to claim 1 is characterized in that: In the three structures, the axial lengths of the rotor sleeve (1), the working magnet (3) and the auxiliary magnet (2) are the same, and each layer of composite magnets is connected together.

3. The high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount type according to claim 1 is characterized in that: The third structure is based on the first structure, and the auxiliary magnet (2) is axially segmented. The magnet is divided into three sections, namely the auxiliary magnet (2), the working magnet (3) and the auxiliary magnet (2). The total axial length of the segmented magnets is the same as the length of the inner working magnet (3).

4. The high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount method according to claim 1 is characterized in that: The electrical conductivity of the auxiliary magnet (2) is less than 10,000 s / m, and the electrical conductivity of the working magnet (3) is greater than 500,000 s / m.

5. The high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount type according to claim 1 is characterized in that: The remanence of the working magnet (3) is greater than 1.1T, and the remanence of the auxiliary magnet (2) is in the range of 0.3T-0.7T.

6. The high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount type according to claim 1 is characterized in that: The rotor sheath (1) is made of carbon fiber material; The auxiliary magnet (2) is a ferrite magnet or a bonded neodymium iron boron magnet; The working magnet (3) is a sintered neodymium iron boron magnet.

7. The high-speed permanent magnet motor rotor structure using a composite permanent magnet surface mount method according to claim 1, characterized in that: Under the condition that the working magnet (3) is a sintered NdFeB magnet, the relationship between the thickness of the working magnet (3), the thickness of the auxiliary magnet (2), and the remanence of the auxiliary magnet (2) is: y=9.3248+0.7302×B outer +2.4114×H outer +(-3.0476×H outer ×B outer ) Wherein, y is the thickness of the working magnet (3); B outer is the residual magnetism of the auxiliary magnet (2); H outer is the thickness of the auxiliary magnet (2).

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